The SF extract of hemp seed effectively scavenged the DPPH and ABTS radicals than ethanol extract

Accordingly, the ethanol and SF extracts hemp seed appears to both scavenge the free radicals and also restore the expression of antioxidant enzymes. Hence, the expression of antioxidant enzymes activity by hemp seed is might be ascribed to the presence of bio-active metabolites. This study is the first report on the expression of antioxidant enzymes by hemp seeds in HepG2 cells.It also up-regulate the expressions of SOD, GPx and CAT enzymes in concentration dependent manner. These findings strongly suggest that ethanol and SF extracts of hemp seed may participate in cellular protection as an antioxidant molecule and stimulate the expression of antioxidant enzymes. It could be concluded that hemp seeds appear to be a useful of source of a therapeutic agent for the treatment of oxidative stress mediated disorders. Recreational marijuana has been legalized for adults 21 years of age or older in several states beginning with Colorado and Washington in 2012. In 2014, Alaska, Oregon, and the District of Columbia voted to legalize recreational marijuana, followed by California, Massachusetts, Nevada, and Maine in 2016. We use data for students at Washington State University to explore the role legalization plays in marijuana use among college students, a population generally thought to be predisposed towards risky behavior, including marijuana use. Our main hypothesis is that legalization of recreational marijuana induces more students to use marijuana by lowering one or more of the costs of using it. These costs may include the threat of punishment, the price and/or availability of marijuana, a lack of social acceptability, and an inherent desire to be law-abiding. Throughout the U.S., marijuana access has been relaxed in three general ways: decriminalization, medical marijuana legalization , and recreational marijuana legalization . In the early 1970s, eleven states officially decriminalized the possession of small amounts of marijuana.Though there is some evidence that use may increase with decriminalization ,hydroponic grow tent most research finds no evidence for such an increase .

Since 1996, 28 states have legalized medical marijuana, which still prohibits recreational use. Most evidence shows that MML has not increased marijuana use among people younger than 21 , although Pacula, Powell, Heaton, and Sevigny find that MML increased use and abuse by those under and over the age of 21. Other studies find MML is associated with more non-medical use and abuse , more marijuana-related arrests and marijuana rehabilitation treatments , and a decrease in the price of illegal marijuana . There have been no direct assessments of the impact of RML on marijuana use of college students, though Cerdá et al. find some evidence that RML is associated with lower perceived risk and higher use for youth. Pacula predicts that use will increase. Hall and Lynskey predict that the price of marijuana will drop and heavy use will increase. Anderson, Hansen and Rees find evidence that RML has decreased the price of marijuana. Our population of interest in this paper is students at WSU in Pullman, Washington. Many changes with respect to marijuana law and availability have occurred in Washington in the past two decades. In 1998, Washington decriminalized marijuana for adult medical use, with qualifying conditions expanding in 2007, 2010, and 2011. In November 2012, Washington passed Initiative 502, which legalized the possession of marijuana for personal recreational use by people aged 21 and older and established a structure for licensing and taxing the production and distribution of recreational marijuana. Legal possession and use of marijuana took effect in December 2012. The first licensed retail stores opened in July 2014. In this paper, we investigate whether the 2012 legalization of recreational marijuana is associated with an increase in use above the long-term trend toward more use in Washington. We hypothesize that marijuana use at WSU increased after RML because both the direct and social costs of using went down. RML increases the availability of marijuana for those 21 and older, and likely for those under 21 as well. It is expected that RML lowers the price of marijuana , increasing demand. Legalization eliminates the threat of punishment to legal-age users, and sends a strong message about changing norms, lowering the social costs of marijuana use. Also, Moreno, Whitehill, Quach, Midamba, and Manskopf find that legalization may have caused some Washington college students to perceive marijuana as safer. The first indication that marijuana use may have changed in Washington after Initiative 502 is observed in the trend of reported marijuana use. Fig. 1 shows the proportion of students who reported using marijuana in the past 30 days across years. For comparison, we also include the proportions over time of students who reported using tobacco, alcohol, or illegal drugs other than marijuana.

To facilitate comparisons, proportions for use of each substance are presented as deviations from the 2012-use levels. We observe a substantial increase over a general upward trend in marijuana users after 2012. Use of the other substances does not show a similar increase. More rigorously, we test for changes against a linear trend in the reported use of marijuana at WSU after RML at the end of 2012 and after legal sales began in Pullman in October 2014. We find that the probability of having used marijuana in the past 30 days increased after RML and remained high though did not increase significantly again after the first marijuana stores opened. We also test for these same changes within specific subgroups of the population. First, we compare the change in use for legal-age students to those under 21, who are not directly affected by RML. We find that for those under 21, the probability of using marijuana increased both after RML and after legal sales began. For students age 21 and over we find no increase at either juncture that is statistically significant at conventional levels. Among other subgroups, we find consistent evidence of an especially large increase in the probability of use for females and for Black and Hispanic students . RML may also affect the use of tobacco, alcohol, or other drugs, either as a substitute or complement. Moreover, factors other than RML that affect marijuana use likely also change the use of other substances. We find no evidence for any systematic changes in the use of other substances that correspond directly with the changes in marijuana use after RML. We are also interested in the intensity of marijuana use, so we test whether the average frequency of marijuana use increased after RML or legal sales. These results show the intensity of marijuana increased after RML, but decreased again after legal sales commenced. Data limitations prevent us from including a reliable control group in the regressions.2 Thus, the estimated effect of RML from the above tests represents the actual treatment effect of RML only to the extent that the linear trend is a good proxy for what marijuana use would have been like without RML. We provide an alternative evaluation by comparing marijuana use at WSU to two national datasets. Although we are unable to include any co-variate controls in the national data after 2011, we calculate simple difference-in-differences estimations of the impact of RML at WSU using two national samples as counterfactuals.We use repeated cross-sectional data of undergraduate students at Washington State University , collected for the National College Health Assessment , a comprehensive health survey collected and made available by the American College Health Association.

WSU has participated in the NCHA in seven different survey years: 2005, 2006, 2008, 2010, 2012, 2014, and 2015. The total number of survey responses available is 14,485, with a mean of 2,069 students surveyed each year. Participants were randomly selected from the student population for all survey years except for 2012 and 2014; in those years, invitations were distributed to the entire student population. After eliminating observations for missing values, our sample contains 13,335 observations. The first column of Table 1 shows the number of students in each year of the WSU sample. The distribution of surveys across years for the excluded observations is nearly identical to the distribution for the whole sample. The NCHA surveys contain questions about students’ use of marijuana, tobacco, alcohol,cheap grow tents and other drugs. Our main variable of interest is a count of how many times a student used marijuana in the past 30 days. For tests 1 and 2, this variable is modified into a binary indicator of whether a student used marijuana at all in the past 30 days. Variables included as controls in our regressions include age, sex, race, and year in school. In other specifications, we also include respondents’ grade point average , type of residence, membership in a fraternity or sorority, and whether a student is international or if they have used tobacco, alcohol, or illegal drugs other than marijuana in the past 30 days. Table 2 provides summary statistics for these variables.Also included in this table are mean values for all variables both before and after the passage of Initiative 502, and summary statistics for the same variables in the national sample of NCHA data and in the NSDUH sample as available. The student population at WSU is about 53-percent male, 68-percent white, 3-percent Black, 5-percent Asian, 10-percent Hispanic, and 5-percent international. The distribution across years for undergraduates is about 23-percent first-year, 23-percent second-year, 24- percent third-year, and 31-percent fourth-year or more . The average GPA for students is about 3.08 . In 2014, the average age across all six campuses was 23 for undergraduate students .

Between 2013 and 2015, 21- to 24-percent of undergraduate students were in fraternities or sororities . Because the cited WSU population statistics are measured after 2012, we compare the NCHA sample statistics to the WSU population for observations after 2012. It appears that the NCHA sample is representative of the WSU population, except for an oversampling of white and Asian students and an under sampling of male and older students. In the NCHA surveys, students are encouraged to select all races that apply to them, which may explain the oversampling of white and Asian students.WSU population data for race is available from 2009 and the NCHA sample closely matches with respect to trends in race composition over time. specifically, the proportion of white students decreases, Black and Hispanic students increase, and Asian students remain constant since 2009. The average age of students in the NCHA sample is lower in part because it only includes students from the Pullman campus, which is WSU’s main undergraduate campus. Finally, there is a small difference in the proportion of male-to-female students in the sample, though this proportion is consistent before and after RML. For difference-in-differences calculations, we use two national-level data sources on marijuana use. First, we use a national sample from the NCHA survey beginning in 2005 that contains surveys from the spring and fall of each year until 2011 and from only fall in 2012 and 2013. Only schools that survey a random sample of students are included in the national dataset. According to the ACHA, the NCHA’s national data is reliable, valid, and suitable for use as a national reference group . We also use data from the National Survey on Drug Use and Health for 18–25-year-old college students from 2005 to 2015. Both national samples contain the same measures as the WSU sample for whether and how many times a respondent had used marijuana in the past 30 days. To more closely match the WSU sample, observations are excluded from the national samples that have missing values for any variables matching those included in the regressions. Table 1 displays the number of students, the number of schools, and the average number of students per school in each year of the national NCHA sample and the number of students in each year of the NSDUH sample. The difference-in-differences calculations are only a valid estimate of the effect of RML to the extent that the national data is a sufficient counterfactual to what we would see at WSU in the absence of RML. We evaluate the extent to which the WSU sample matches the national samples in the pre-RML period by first comparing the means in Table 2.

Models for each sub-cortical structure are based on a training set of manually traced images

Voxel-wise statistics were corrected at the cluster-level using Threshold-Free Cluster Enhancement to a Family-Wise Error rate of p b 0.05, with 5000 permutations. Nevertheless, as a further control for heritability, we conducted follow-up analyses by randomly selecting one user from each family such that there were no siblings within the sub-sample, resulting in 272 marijuana users. Identical analyses were performed using the full user sample and the unrelated sub-sample. These analyses were conducted using FSL’s randomise package, which performs permutation methods, without using exchange ability blocks. Following the PALM analyses, 5000 permutations were performed. Likewise, voxel wise results were corrected using Threshold-Free Cluster Enhancement to a FWE-corrected p b 0.05.We further processed the pre-processed diffusion images using FSL’s FDT toolbox and Tract-Based Spatial Statistics . Briefly, the diffusion tensor model was fit at each voxel yielding maps for fractional anisotropy , axial diffusivity , radial diffusivity , and mean diffusivity . These maps were then nonlinearly aligned to the FMRIB 1 mm FA template and skeletonized. This last step creates a skeleton which represents the centers of all fiber bundles that are generally common to all participants in the study. The skeleton was thresholded at FA b 0.3. The skeleton and nonlinear registration parameters were generated using the FA maps, and these transformations were subsequently applied to the other diffusion parameter maps. Voxel-wise statistics were then performed in this skeleton space.The effect of marijuana use on white matter was assessed with a linear parametric analysis across level of marijuana use. Participants reported a wide-range of levels of marijuana use in terms of age of first use as well as the number of times used over the lifetime, as shown in Fig. 1. Age of first use and times used were included as factors of interest and, as described above, all analyses included alcohol and tobacco use, age, gender, years of education, and Total Motion Index as co-variates. For a table of correlations between all co-variates see Table 1.Analyses of voxel wise gray matter morphometry were carried out with FSL-VBM an optimized VBM protocol carried out with FSL tools . First, structural images were brain-extracted and gray matter-segmented before being registered to the MNI 152 standard space using non-linear registration.

The resulting images were averaged and flipped along the x-axis to create a left-right symmetric,trimming tray study-specific gray matter template. Second, all native gray matter images were non-linearly registered to this study-specific template and “modulated” to correct for local expansion due to the non-linear component of the spatial transformation. The modulated gray matter images were then smoothed with an isotropic Gaussian kernel with a sigma of 3 mm. Finally, voxel wise GLM was applied using permutation-based non-parametric testing, correcting for multiple comparisons across space, using Threshold-Free Cluster Enhancement . Following Weiland et al. , we also performed a multivariate analysis on the effects of marijuana use on sub-cortical and cortical volumes and cortical thickness extracted with FreeSurfer.Rather than analyzing whether marijuana showed a multivariate effect across all 35 cortical regions contained in this table as did Weiland et al. , we chose an a priori approach, focusing on prefrontal regions and sub-cortical regions where marijuana has been shown to have significant effects . Regions of interest included 15 prefrontal cortical regions : medial and lateral orbitofrontal cortex, caudal anterior cingulate, caudal middle frontal, inferior frontal gyrus , rostral middle frontal, superior frontal, and frontal pole. Subcortical regions included nucleus accumbens, hippocampus, cerebellum cortex and white matter, thalamus, and amygdala. White matter volumes were included for the anterior and mid anterior corpus callosum.Shape analyses of sub-cortical ROIs were carried out using FSL’s FIRST tool . FIRST allows for a model-based segmentation and registration of anatomical images, where volumetric labels are parameterized as surface meshes.Vertex locations from each participant were projected onto the surface of the average shape , resulting in scalar projection values. This approach normalizes for brain size.

The same models of marijuana use generated for the white matter analyses were used here. Again, PALM was used to perform multi-level block permutation analyses. In order to identify which, if any, sub-region of the hippocampus, amygdala, or nucleus accumbens exhibited a shape difference, we referred to the Jülich histological atlas contained in FSL. Because FIRST only reports changes at the surface of the structure and does not contain information about which deep levels of a structure are impacted, these sub-region labels represent approximations.We then examined the effects of marijuana use on white matter diffusion parameters . The group comparison showed no significant effects, possibly suggesting that the frequency of marijuana use in the HCP sample is not severe enough to replicate previous studies, which largely focused on comparisons of non-users and daily marijuana users. In line with this possibility, there were no linear effects of the number of times used on white matter coherence in users. As shown in Fig. 2, age of first use had a positive association with FA as well as a negative association with RD, such that an earlier age of first use was associated with lower FA and greater RD in a large cluster of right hemisphere white matter. These tracts primarily subsisted of the Superior Longitudinal Fasciculus , Inferior Longitudinal Fasciculus , and Forceps Major and Minor. The SLF connects the prefrontal cortex and parietal cortex and is involved in executive functions , and the ILF connects the temporal and occipital cortices, has been shown to affected byadolescent marijuana abuse . The Forceps Major and Minor are extensions of the corpus callosum connecting the left and right occipital and frontal lobes, respectively. Thus, even though most of the effects on FA and RD were found in the right hemisphere, communication between the left and right hemispheres may be impacted by marijuana age of onset.When examining the subset of unrelated marijuana users, we confirmed the negative effect of an earlier age of first use on FA and RD in the SLF, as shown in Fig. 3. Increased RD has been related to demyelination in neurodegenerative diseases such as multiple sclerosis , suggestive of a neurotoxic effect with early age of first use of marijuana. These findings taken together, and in line with previous studies , suggest that an earlier age of onset is associated with decreased coherence of white matter. Moreover, these results suggest that marijuana use has an impact on the development of these white matter tracts during adolescence.We then investigated whether the shape of the hippocampus, amygdala, or accumbens was impacted by marijuana use. For the full sample of users, the results are shown in Fig. 4. There was a trend for a significant negative relationship between the number of times used and scalar values in the left amygdala .

Participants with a higher number of times used showed more inward deflection in the superficial group of the left amygdala. In the right nucleus accumbens, there was a significant positive relationship between age of first use and shape, such that participants with an earlier age of onset of use showed greater outward deflection. This finding suggests that a later age of first use is related to more outward deflection of the right anterior nucleus accumbens. In the left hippocampus cornu ammonis and posterior hippocampus subiculum, a greater number of times used was associated with greater inward deflection . The effects of the number of times used marijuana in the restricted sample closely mirrored those in the full sample. In the left superficial amygdala there was a trend for participants with a higher number of times used to show more inward deflection . Likewise, the same pattern was observed in the left hippocampus cornu ammonis . For age of first use, however, there was the opposite pattern , albeit in the left posterior nucleus accumbens , suggesting that a later age of first age is associated with a more inward deflection of the left posterior nucleus accumbens. This latter finding is similar to that observed by Gilman et al. who found that more frequent use was associated with an inward deflection of the nucleus accumbens. When comparing users and non-users,trim tray pollen significant effects on shape were discovered in the right amygdala and left hippocampus. There were two clusters in the right amygdala, one in the dorsal superficial group and another in the ventral laterobasal group, that showed more outward deflection in users compared to non-users. Similarly, in the left ventral anterior hippocampus , users showed more outward deflection compared to non-users. This region was more ventral and anterior to the cluster in the subiculum that showed a negative association with times used in users. These group results are somewhat surprising, as the correlational analyses within users showed inward deflections in more heavy users. However, the left and right nucleus accumbens also showed opposite patterns of inward and outward deflections with greater use, respectively. Thus, one possibility is that marijuana has differential effects in the left and right hemispheres. Nevertheless, Gilman et al. found more inward deflections for heavy users in both left and right nucleus accumbens and the right amygdala.Despite a trend of de-criminalization and softening societal views, the scientific literature on the effects of marijuana on the brain has not yet reached a consensus. Work with adolescents has consistently shown that heavy marijuana use leads to disruptions in the integrity of white matter . However, work investigating the effects of marijuana on the morphometry of gray matter and sub-cortical regions has yielded inconsistent findings, with several papers even providing strong evidence that heavy marijuana has no effects on brain morphometry . The current study took a broad look at this question using a multi-modal neuroimaging approach on data from almost 500 participants reporting varying levels of recreational marijuana use. These data from the HCP include the highest quality neuroimaging data publically available, with almost twice the resolution for structural images , and using state of the art diffusion imaging . This large dataset enabled us to investigate parametric associations between marijuana use and cortical and sub-cortical brain morphometry and white matter integrity. An advantage of this dataset is that it represents a representative community sample, with great variability in race,ethnicity, gender, education level, mental health symptoms, and drug use . Moreover, such ‘big data’ sets like the HCP are becoming more and more commonplace , and it will be important to mine these datasets to discover new insights about the functions and organization of the human brain. Importantly, this data set provided information on age of first use providing information on whether or not use occurred during early adolescence. Adolescence is a time of critical brain development for white matter tracts, with white matter volume increasing into young adulthood . Heavy marijuana use during this critical period may impact development , and specifically, a number of frontal and association white matter tracts show decreased white matter integrity with heavy adolescent use. Recently, Becker et al. found that over the course of two years, young adults with an adolescent onset of marijuana use showed reduced longitudinal development of FA in key frontal, central, and parietal white matter tracts. The current findings are largely consistent with those reports. We found that an earlier age of first use was associated with decreased FA and increased RD in long-range tracts including the forceps minor, Superior Longitudinal Fasciculus, and Inferior Longitudinal Fasciculus. Given that the average age of participants in the current study was 29.2, the effects of marijuana on white matter appear to be long lasting, persisting 10–20 years after the first use of marijuana. Future, studies should examine the effects of duration of use on the trajectory of brain development. With regards to shape, a recent meta-analysis has suggested that the sub-cortical structure most consistently implicated in showing an effect of marijuana use is the hippocampus . Consistent with that finding, we observed that anterior aspects of the hippocampus showed shape differences due to the number of times marijuana has been used. This finding is interesting as anterior and posterior sub-regions of the hippocampus have dissociable roles in memory, with the anterior portion being involved more in memory encoding and the posterior portion being involved more in memory retrieval ; however, an exploratory analysis revealed no connection between hippo-campal or amygdala shape and memory performance in these participants .

The issue of marijuana legalization has been divided and debated across political stances

In recent years,however,the public health policy regarding marijuana legalization has been swiftly changing in the United States.As of April 2018,nine states – Alaska,California,Colorado,Maine,Massachusetts,Nevada,Oregon,Vermont,and Washington – and the District of Columbia have enacted laws to authorize the production,distribution,and possession of marijuana.A total of 29 states and DC have allowed medical use of marijuana for patients with approved health conditions.States with medical marijuana laws have an evident form of patient registry,and they provide protection against arrest for possession up to a limited amount of marijuana for medical use.In the U.S.,marijuana legalization may be one of the most controversial issues including legal,policy,health,and economic considerations.For example,marijuana legalization has been a highly contested public health issue between state and federal drug laws.Also,the essential question may be whether marijuana has medical value.The national controversy over marijuana legalization has included discussion of both the benefits and risks of non-medical marijuana use.Additionally,it is important to consider economic effects of marijuana legalization.Communication researchers have examined how the news media can influence public perceptions or attitudes toward certain issues by using the notion of framing.According to Gamson and Modigliani,a frame refers to a key organizing theme or idea that provides meaning to issues or events reported in a news story.A frame is an idea organizer that packages an issue in a specific way,telling what the issue is about.Media frames suggest how the public can interpret an issue or event,and framing involves selection and salience.Thus,news framing can influence the public’s perceptions about public health policy including marijuana legalization.

Drugs have been described mainly as objects of government enforcement and negative connotations of use in the mainstream news outlets.In the issue of marijuana legalization,roll bench a variety of organizing themes can be presented.For example,a marijuana legalization story can be framed as a legislation issue,in which news stories primarily emphasize the legislative proceedings regarding marijuana use and marijuana legalization.Previous studies have explored how American news media frame the marijuana policy,including medical use of marijuana and recreational use of marijuana.Analyzing newspaper articles between June 2008 and June 2009,Vickovic and Fradella found that U.S.newspapers mainly discussed medical marijuana as legal and regulatory issues and passage of medical marijuana news.Although it is very prominently discussed in terms of public health,legal,policy,and economic perspectives,researchers had paid little attention to how the media presented this issue.In order to reduce the gap in the literature,we make an attempt to comprehensively investigate media frames about marijuana legalization.First,we examine the organizing theme of marijuana legalization stories.More specifically,this study investigates how U.S.newspapers present the issue of marijuana legalization from 1995 to 2014.Also,we look at whether the frequency of organizing themes remains steady or not over time.As a recent survey shows,public opinion on legalizing marijuana has dramatically changed.Second,we explore the tone of each news article.specifically,this study examines how the tones of marijuana legalization are presented and changed over time between 1995 and 2014.Coleman et al.suggest that story tone assumes affective perspective,providing the story a positive,neutral,or negative connotation.affective attributes consider audience’s emotional responses to media stories.Examining the tone of ethanol stories in U.S.newspapers,for example,Kim et al.categorized story tone into pro-ethanol,anti-ethanol or neutral.They found that 48% of stories described a bio-fuel issue as neutral.In this study,the story tone refers to answering the question of whether the story is overall in support of or in opposition to marijuana legalization.

Additionally,the political orientation of news outlets has been considered as a major factor that can influence the tone of news stories.Thus,it can be predicated that liberal newspapers tend to describe marijuana legalization with a positive tone more often than conservative newspapers.To select newspapers from both states where marijuana is allowed and illegal,we analyzed a total of 10 newspapers published in the United States.Considering the location,circulation,and political orientation of newspapers,three categories were selected for analysis: national newspapers,newspapers in states where marijuana is illegal,and newspapers in states where medical marijuana is legal.These newspapers were available at the search databases.According to the 2008 and 2012 presidential endorsements,liberal newspapers include the New York Times,the Washington Post,the Denver Post,the Seattle Times,and the San Francisco Chronicle,while others are conservative newspapers.News articles were retrieved using a key word search of three search engines: the Lexis-Nexis,the News Bank,and the Factiva databases.The keywords “medical marijuana” OR “marijuana use” OR “marijuana legalization” OR “legal marijuana,” appearing in the headline or the lead paragraph of the Lexis-Nexis database,in the lead or first paragraph of the News Bank database,and in the text of the Factiva database were used to find articles of coverage selected for this study between 1995 and 2014.This search yielded a total of 4186 articles – including editorials – from the 10 newspapers,and we produced a manageable systematic random sample of about 75 articles from each paper.This study excluded unrelated stories where marijuana was simply mentioned without being the main focus or where reported marijuana related crimes.After excluding these unrelated articles,a total of 640 articles were analyzed.The coding instrument was developed through a comprehensive review of news stories and previous studies.

Coding was conducted by one of the authors and one graduate student.Coders first read a story carefully,and then decided an organizing theme of each story by examining what was the main focus.Because researchers paid little attention to examining news frames of marijuana legalization,more than 100 news articles were carefully reviewed to find out organizing themes in stories related to marijuana legalization and medical marijuana.Then,six organizing themes were identified after examining marijuana legalization stories and previous studies.Each story was categorized into one of the six organizing themes: legislation,law enforcement,youth drug use,economy,patients,and medical effects.When coders found more than two themes in an article,they checked both.The description of organizing themes is presented in Table 1.Coders then coded overall tones of a story.This study used the way to indicate overall tones examined by the previous studies.Coders first decided that each paragraph was positive,neutral,or negative toward medical or recreational use of marijuana.There were three major considerations to examine: what was emphasized in the headline and lead,how the balance or imbalance of the pros and cons of marijuana use were described,and how the metaphor mentioned in each story were related to positive or negative social norms.Coders then decided story tone as an ordinal category by classifying 1 to a negative,2 to a neutral,or 3 to a positive story.When at least two-thirds of the paragraphs could be considered as either negative or positive,coders selected one of either category.Otherwise,the story was coded as neutral.Two coders coded articles after having conducted a series of training and pilot-test sessions.Intercoder reliability was calculated by double coding a random sub-sample of the data.Intercoder reliability corrected for agreement by chance ranged between 0.79 and 1.00 with an average reliability of 0.88.This study aims to answer the question of how U.S.newspapers have presented the issue of marijuana legalization between 1995 and 2014.Newspapers have largely described marijuana legalization as a law enforcement issue rather than an economic issue or a medical issue.Taken together,our findings are consistent with previous studies that have revealed that marijuana has been mainly discussed as a legal and policy issue.Framing can affect the way the readers evaluate a certain issue,influencing their judgment.Thus,it can be argued that Americans are more likely to evaluate marijuana legalization as a public policy issue,rather than a public health issue.There can be several explanations for these findings.First,marijuana legalization is essentially the theme about the legislative acts.A number of legislative measures that allow for recreational use of marijuana have been passed since 2012.Second,marijuana stories often involved conflicts between federal and state governments,between enforcement agencies and citizens,and between governors and congresses.

The conflict perspective is a popular frame because conflict is a recognized news value.Thus,this conflict may influence journalists to report marijuana stories as a law enforcement theme.Third,a medical effect theme and a patients theme might appear less often because we examined stories related to recreational use as well as medical use.Nonetheless,criticism of newspapers’ tendency to define marijuana stories as legislation or law enforcement stories may be justified.Because these themes were clearly dominant,the issues surrounding medical marijuana were not commonly highlighted in the news.Although the issue of marijuana is important in terms of public health approach,our findings indicated that journalists paid little attention to the medical effect theme when covering marijuana stories.Our findings also revealed that organizing themes appeared differently according to the presidential periods.First,newspapers frequently described marijuana stories with a legislation theme during the Obama administration period.Since Colorado and Washington initially allowed for recreational use of marijuana in 2012,other seven more states have followed.As Griffin et al.pointed out,the passage of drying rack cannabis laws significantly increased news stories.During this period,frequent legislative activities caused media attention.Second,an economy theme more frequently appeared since 2009.Block also found that marijuana legalization was discussed mainly as a business issue in 2014.In particular,many news stories reported the expected and actual economic effects of legalization during those years.Third,a youth drug use theme peaked during the first Clinton administration period,and then it has decreased.Interestingly,according to Monitoring the Future survey,the actual use among youth was somewhat declined between 1995 and 2008.Thus,newspapers probably reflected this trend.Although more than half articles described the issue of marijuana with a neutral tone,positive stories were published more frequently than negative stories.These findings can be explained by two-sided framed stories,which often result in a neutral tone.As Sniderman and Theriault indicate,the public should make choices between several competing values in real politics.In a two-sided frame,a story presents both frames of an issue.For example,the media may present reasons to both support and oppose marijuana legalization in the same story.Over the past decade,the political discourse around marijuana legalization has been dominated by competing frames over the legal,law enforcement,economic,and public health consequences of proposed state and federal government policies.These two-sided or non-framed articles likely present the issue with a neutral tone.Our findings have several limitations.First,we examined only newspapers.If marijuana stories were retrieved from other sources for 20 years,1995 to 2014,it could be very hard to manage the sample.Thus,one of the major reasons to analyze only newspapers was to obtain a manageable sample size.Also,newspapers still provide a useful channel to deliver information,as they can play a key role in setting the agenda for other news media.

In addition,many mainstream newspapers have provided their online versions through their own web pages and social media.Thus,news stories from these newspapers can be widely exposed to Americans.Future research should include other news sources.Second,the selection of newspapers has limitations.Because some newspapers were not available through online search engines,we examined less representative newspapers,which can cause concerns regarding the generalizability of the findings.Thus,it is necessary for future research to include more representative newspapers as much as possible.Third,it can be pointed out that the categories of themes were inductively determined because there have been only a few previous studies on the topic of marijuana legalization.The coding categories used in this study may raise questions about the results in terms of validity and reliability.Thus,future studies should test the same categories that this study used and then develop more correct coding categories.Lastly,the time period for this study was between 1995 and 2014.Although marijuana was initially legalized in 2012,the first recreational sales were in 2014.Thus,news stories during 2014 could be quite different than stories from previous years.The development of high-performance materials made from natural resources is increasing worldwide due to their abundant source in the nature,low cost,light weight and high specific modulus in contrast to the synthetic fibers.In addition,they are biodegradable,renewable,have low specific weight,high specific strength and stiffness than glass fibers,ease of processing,reduced wear,good thermal and acoustic insulating properties.Hemp fiber is recently gaining attention as diversified reinforcing applications in composite industry,housing,railways and aerospace applications due to its high specific strength and stiffness.Hemp offers excellent mechanical strength and Young’s modulus.However,the foremost limitation of natural fibers used as reinforcement is the poor interfacial adhesion between polar hydrophilic natural fibers and non-polar hydrophobic polymers.Different coupling agents have been used to increase compatibility between natural fibers and thermoplastic matrices,thereby augmenting the composite’s performance.The increasing use of polyethylene in number of applications is posing a serious environmental threat and thus the researchers are motivated to undertake studies concerning recycling of polymer waste.The literature consulted so far reveals that the studies pertaining to mechanical characterization of hemp fiber reinforced polyethylene composites,especially containing recycled PE,are rather scant.In the light of these facts,it is decided to investigate the mechanical behavior of hemp fiber-recycled PE composites.

Amygdala activation was lower to both negative and positive words in heavy users compared with controls

Average beta weights from eight clusters showing a significant difference between groups were extracted using MarsBaR and imported into IBM SPSS Statistics v22 for further analysis.In addition,amygdala activation was examined based on a prior study of marijuana use and emotional processing.A mask of left and right amygdala was created using the automated anatomical labeling atlas in Wake Forest University Pickatlas.A threshold of p <.05 was used.In the whole-brain two-sample t-test,the heavy marijuana users had less activation compared with controls during NEG in four clusters: right middle frontal and dorsolateral superior frontal gyri,right middle and superior temporal gyri,right calcarine fissure and surrounding cortex,including cuneus and lingual gyri,and right superior temporal gyrus and insula.During POS,heavy users had less activation in the right inferior parietal lobe and increased activation in the right dorsolateral superior frontal gyrus relative to controls.In the amygdala region of-interest analyses,ebb flow heavy users had less activation in the right and left amygdalae during NEG and in the right and left amygdalae during POS compared with controls.See Table 3 for all whole brain and region of interest results.To determine whether differences in activation to neutral words were impacting these group differences,we conducted an independent samples t-test in SPM8 using the contrast of neutral words vs.rest.Partial correlations between brain activation and emotional functioning at scan time and at follow-up are reported in Table 4.There were negative correlations between negative emotionality measured at scan time and activation in right STG/insula and left amygdala during NEG.There was also a negative correlation between negative emotionality at scan time and activation in right amygdala during POS.

Positive correlations were observed between resiliency measured at follow-up and activation in caudal dlPFC and cuneus/lingual gyrus during NEG.A negative correlation was observed between negative emotionality at follow-up and activation in caudal dlPFC during NEG.No other correlations passed correction for multiple comparisons.Mediation analyses therefore focused on these two brain regions and resiliency and negative emotionality at follow-up.The goal of this work was to investigate the impact of heavy marijuana use during adolescence on later emotional functioning,as well as potential brain function mediators of this effect.Using a prospective design,we investigated two outcomes related to emotional functioning: negative emotionality and resiliency.We found that heavy marijuana users did not differ from controls in emotional functioning early in adolescence when marijuana use was initiated,whereas in late adolescence/early adulthood,heavy users had more negative emotionality and less resiliency than controls.To investigate the impact of adolescent marijuana use on emotion-related brain functioning,we compared neural responses to emotional words in heavy marijuana users and controls.Compared with controls,heavy users had less activation in emotion processing and integration regions,including the right insula,prefrontal cortex,and occipital cortex during the viewing of negative words,and in a region involved in attentional control during the viewing of positive words.Further,we found heightened activation to positive words in the dorsolateral prefrontal cortex among heavy users.Activation in prefrontal cortex during the viewing of negative stimuli mediated an association between marijuana use and both negative emotionality and resiliency at follow-up.

Activation in visual association regions of the occipital cortex mediated an association between marijuana use and later resiliency,but not negative emotionality.A main finding of this prospective study is that marijuana use in adolescence may impact later emotional functioning.Heavy marijuana users scored higher on negative emotionality than controls at the approximate ages of 20 and 23,whereas groups did not differ at approximately age 13,when heavy users initiated use.Furthermore,exploratory analyses revealed that negative emotionality decreased from early adolescence to young adulthood in controls—consistent with normative changes —but not in heavy users.Importantly,we observed an association between greater lifetime marijuana use occasions and higher negative emotionality at age 20,after controlling for early levels of negative emotionality.These findings are in line with other longitudinal work showing that adolescent marijuana users had increased depression,anxiety,and suicidality in young adulthood,but marijuana use was not associated with premorbid differences in negative affect.Thus,the current results add to previous work supporting an association between early marijuana use and later negative affectivity.We also investigated the impact of marijuana use on resiliency,as self-regulation plays a critical role in emotional functioning.We found no difference between groups in resiliency at the age of marijuana initiation,whereas differences emerged in late adolescence/early adulthood,with lower resiliency in the heavy use group.Although conceptualized as a temperament/personality trait,evidence indicates that resiliency improves throughout adolescence and into adulthood in healthy individuals.Furthermore,lifetime occasions of marijuana use was negatively correlated with resiliency,even after taking into account early level of resiliency.Resiliency is inversely related to depression and internalizing problems in children and emerging adults,and positively related to effective social interaction and social status.A reciprocal longitudinal relationship has been demonstrated between resiliency and positive emotionality from adolescence to early adulthood,as well as with the effective management of negative emotions.

It is possible,therefore,that adolescent marijuana use may impact emotional functioning partially through an influence on resiliency; however further work in a larger sample is required to determine these longitudinal relationships.A central goal of this study was to characterize the neural mechanisms through which adolescent marijuana use exerts its effects on later emotional functioning.We found that activation in the right prefrontal cortex to negative words mediated the association between heavy marijuana use and both negative emotionality and resiliency at follow-up.Specifically,activation in the right middle frontal gyrus and dorsolateral superior frontal gyrus was lower in heavy users than controls,an effect that was associated with decreased resiliency and increased negative emotionality at follow-up.This area of the prefrontal cortex has been referred to as the caudal dorsolateral prefrontal region and is closely connected with motor and supplementary motor regions.Prior work has found activation of the caudal dlPFC and associated regions during the reading of high-arousal emotional words.The supplementary motor and premotor regions are important for emotion processing and empathy and may regulate approach-withdrawal tendencies to emotional stimuli by integrating limbic and motor responses.A recent meta-analysis found that activation in these regions decreased to negative stimuli in alexithymia,a trait characterized by difficulties with experiencing and processing emotions.The current findings suggest that heavy marijuana use during adolescence may impact caudal dlPFC functioning,impairing the processing and integration of emotional stimuli and lead to increased negative emotionality.Additionally,we found that activation in the occipital cortex to negative emotional stimuli mediated the relationship between marijuana use and later resiliency.specifically,activation in the cortical region surrounding the calcarine fissure,including portions of the right cuneus and lingual gyrus,was lower in heavy marijuana users than controls.This activation was further associated with decreased resiliency at follow-up,when controlling for resiliency at the time of scan.Although the cuneus and lingual gyrus are classically considered as visual processing and integration regions,there is a large literature associating both regions with aspects of emotion functioning,including the processing of emotional faces,high-arousal emotional words,and emotional film clips,pot drying as well as the evaluation of one’s own emotional state.Cuneus activation has also been associated with the ability to attribute mental states to others,termed “theory of mind”.

A recent study reported that adult marijuana users had differences in brain activation compared with controls during a ToM task,including lower activation in the right cuneus.Therefore,an impact of heavy marijuana use during adolescence on the functioning of occipital regions involved in the evaluation of emotional stimuli with respect to oneself and to others may impair self-regulation of emotional processes.In addition to the regions found to mediate later outcome,heavy marijuana users had less activation than controls in the insula to negative words.These findings are consistent with previous work showing adolescent marijuana users had reduced cerebral blood flow in the insula compared with controls.Furthermore,studies of adult marijuana users found less activation in the insula to loss outcomes during a monetary incentive task and to errors in an inhibitory control task compared with controls.The insula is critical to the integration of emotional and homeostatic information,and may be involved in translating interoceptive signals into conscious feelings.For example,the magnitude of insula activation while participants evaluated their own emotional and bodily states was found to be associated with social anxiety and neuroticism.Insula activation has also been associated with self-report measures of anxiety and anticipation of aversive exposure in anxiety-prone individuals.Here we found less insula activity to negative words in heavy marijuana users compared with controls,which was further associated with more negative emotionality at the time of scan.Together,this evidence suggests that heavy marijuana use may lead to impairment in the integration of emotional experience.Activation of the amygdala was also reduced in heavy marijuana users compared to controls—an effect observed for both negative and positive words.Along with the insula,the amygdala is part of a network involved in translating interoceptive responses to emotional stimuli into emotional experience.Blunted amygdala response has been observed in individuals with difficulties experiencing and processing emotions.Acutely,cannabidiol,a psychoactive component of cannabis,has been shown to decrease amygdala activation to anxiety-inducing emotional stimuli; this effect was further associated with a reduction in electrodermal activity,supporting links among marijuana,amygdala functioning,and interoceptive response to emotion.Furthermore,prior evidence indicates that the impact of marijuana use on amygdala-mediated emotional responding is not restricted to negative stimuli.Gruber et al.reported less amygdala activation in adult heavy marijuana smokers compared with controls to both happy and angry faces presented below the level of conscious processing.Here we found less amygdala activation to both positive and negative words in heavy marijuana users compared with controls,which further correlated with negative emotionality.Therefore,marijuana may have an impact on amygdala functioning that impairs general emotional arousal and integration.

The finding of an association between negative emotionality and reduced activation of the insula and amygdala is opposite to effects described in the depression and anxiety literature,which reports enhanced activation to negative stimuli.However,a longitudinal study of individuals with comorbid major depression and marijuana dependence found that greater marijuana use was associated with reduced amygdala activation to emotional stimuli.This suggests that the mechanism through which marijuana impacts negative emotionality differs from the mechanism underlying depression and anxiety.For example,the associations between insula and amygdala functioning and negative emotionality in the current study may be more pertinent to differences in the experience and processing of emotions rather than depression and anxiety.Finally,heavy marijuana users showed reduced activity in the right inferior parietal lobule and greater activation in the right dlPFC during the viewing of positive words.The inferior parietal cortex is part of an attentional system involved in the automatic allocation of attention to task-relevant information,whereas the dlPFC is involved in more effortful attentional control.Thus,the current results suggest a decrease in automatic attention to positive words in heavy users with a corresponding increase in effortful attentional control necessary to attend to the task.This is consistent with prior work demonstrating heightened activation of right-hemisphere prefrontal attentional control circuitry in adolescent marijuana users,which may reflect the need for increased effort in attending to task-related stimuli.The results of this study should be considered with a few limitations in mind.First is the relatively small sample size,suggesting that results should be interpreted as somewhat preliminary,and further,that additional differences between groups may have been missed.Furthermore,although there is evidence of sex differences in the impact of marijuana on emotional functioning,this study was not adequately powered to investigate sex as a moderator.It will be important to address this issue in future work.Second,the control group included individuals who had occasional marijuana use in adolescence.The impact of low levels of marijuana use on brain development is not known; therefore an ideal control group would have no marijuana use.However,given the high levels of comorbid alcohol and marijuana use in adolescence,it was infeasible to create a marijuana-naïve control group while maintaining similar levels of alcohol use across groups.Third,the majority of participants in this study had a family history of AUD,which may limit the generalizability of results to those at heightened risk for behavioral and emotional problems.Using aprospective design,we found that heavy marijuana users who began using in adolescence had higher negative emotionality and lower resiliency in their early twenties.Furthermore,differences in neural responses to emotionally-laden words mediated the associations between marijuana use and later negative emotionality and resiliency in these subjects.Because marijuana use is on the rise while perceptions of harm are decreasing,this is timely work.It adds to a growing body of evidence pointing to adverse effects of adolescent marijuana use on emotional functioning and is the first to characterize the functional neural correlates of these effects prospectively.

Hemp hurds are commonly used as a filler in the manufacture of hemp concrete

Measurements show that values of thermal conductivity coefficient for composites are in a range 0.125- 0.065 W·m-1·K-1.In the paper,it was reported,that the thermal conductivity coefficients of hardened composites based on MgO-cement and unmodified hemp shives of another origin were 0.111- 0.23 W·m-1·K-1 and comparable to other building materials such as aerated autoclaved concrete.The obtained values of absorbability of composites made with chemically treated hemp shives are higher than in the case of referential composite.According to the measurements,bulk density of composites was found to be in the range of 1220-1440 kg·m-3.As shown,only chemical treatment of hemp shives with NaOH leads to slightly higher density value of composite compared to composite based on unmodified hemp shives.In the case of composites with modified hemp shives,the highest value of compressive strength was recorded for composite made from hemp shives treated by Ca2.Decrease in compressive strength values for all samples with chemically treated hemp shives in comparison to referential composite was observed.This fact is contrary to previously published data on lime composites based chemically treated hemp fibres >23@.The obtained results are difficult to interpret.It is most likely that many factors could cause this phenomen.Various unfavourable factors acting when processing the hemp shives and mixture could be considered in clarifying of this fact,e.g.short time of hardening,content of crystalline cellulose,varying polymerization degrees of cellulose and degradation of hemp fibres surface,heterogeneity of hemp shive slices in comparison to fibres as well as used binder MgO-cement,grow cannabis in containers mainly the action of alkaline components combination.

Measurements show that values of thermal conductivity coefficient for composites are in a range 0.125- 0.065 W·m-1·K-1.In the paper,it was reported,that the thermal conductivity coefficients of hardened composites based on MgO-cement and unmodified hemp shives of another origin were 0.111- 0.23 W·m-1·K-1 and comparable to other building materials such as aerated autoclaved concrete.The obtained values of absorbability of composites made with chemically treated hemp shives are higher than in the case of referential composite.According to the measurements,bulk density of composites was found to be in the range of 1220-1440 kg·m-3.As shown,only chemical treatment of hemp shives with NaOH leads to slightly higher density value of composite compared to composite based on unmodified hemp shives.In the case of composites with modified hemp shives,the highest value of compressive strength was recorded for composite made from hemp shives treated by Ca2.Decrease in compressive strength values for all samples with chemically treated hemp shives in Maximum power consumption comes to building heating,which depends on the efficiency of building envelopes.Building sector energy consumption covers 50% of the total energy consumption.Reducing building energy cost it is necessary to increase the energy efficiency of complex elements in envelopes,both in their production and operational conditions.In order to build environmentally friendly,energy efficient and affordable buildings,it is appropriate to link the agricultural and construction industries.Environmentally friendly buildings can only be built when there is the use of renewable resources.Insulation materials are increasingly used in the production of renewable resources such as hemp,flax,jute straw,various kinds of wood.Hemp is one of the most rational plant because all of its parts are used in industry.Hemp seeds are used for the edible oil extraction and bio-diesel production,bast fibers are used in special paper production,cars,construction and other industries.Fiber is obtained by soaking the hemp stalks in order to separate the fibers and non-fibrous components called hurds.Hemp hurds are ligneous woody tissues,which are considered as fiber products obtained by secondary manufacturing.Although the usage of new hemp hurds is being developed,but most of them are used for animal litter and in construction only 5%.The hemp fiber insulation is made of composite materials.

Scientists investigated the material from hemp fibers,hurds and a binder,they exhibited low thermal conductivity which varied from 0.0393 W/ to 0.0486 W/,when density was from 40.3 kg/m3 to 77.9 kg/m3 respectively.Conducted analysis by Finnish scientists has showed that the thermal insulation materials made from hemp or hemp and flax fiber mixture with density varying from 5 kg/m3 to 100 kg/m3 have the thermal conductivity ranging from 0,033 W/ to 0.094 W/.Hemp hurds are suitable for the production of thermal insulation composites due to their porous structure consisting of small pores,and due to this good strength and thermal properties can be achieved.Hemp hurds are loose-fill material,so it can be characterized by two types of porosity,i.e.internal particles porosity and porosity of the particles formed between particles.By the method of 3D tomography foreign scientists had determined that porosity of hemp hurds was of 57%.The size of pores formed between the particles depends on the texture of hurds and it is about 1 mm.The inner porosity of hemp hurds consists of 15% of 70 μm sized pores and 85% of 400 μm pores.Foreign scientists studied hemp concrete,in which the binding material was lime.The results showed that compressive strength was from 0.2 to 1.2 MPa and the modulus of elasticity – from 3 to 90 MPa.Elford 2008 also investigated the thermal conductivity of hemp concrete with lime binder.The thermal conductivity of specimens with a density ranging from 417 kg/m3 to 551 kg/m3 varied from 0.179 W/ to 0.485 W/.Swedish scientists studied the mechanical properties of composite materials from hemp hurds,fibers and several different binding materials.Compressive strength of mixture of cement and lime and only cement,varied from 0.15 MPa to 0.83 MPa,and the modulus of elasticity varied from 12.6 MPa to 28.0 MPa respectively when the density of the specimens ranged from 587 kg/m3 to 733 kg/m3.Literature analysis has shown that lime is usually used as a binding material for tests of composites from hemp hurds.The usage of other binding materials has been barely studied,so the aim of this work is to figure out how to use binder in order to obtain omptimal strength and thermal insulating properties.Now-a-days,natural fibers reinforced composites exhibit the superior mechanical properties than synthetic fiber reinforced polymer composites due to its inherent properties.

The mechanical properties such as tensile strength,flexural and impact strengths of natural and synthetic fibers reinforced polymer composites with different fiber volume were evaluated by Ramesh et al..The result indicated that,there is the significant improvement in mechanical properties and the process of hybridization reduces the risks related to the environmental concern.Sapuan et al. fabricated the composites by using banana fiber is a waste product of banana cultivation and which is easily available in tropical countries like malaysia and south india.This fiber has many advantages and holding high mechanical strength when compared to the synthetic fibers.They have prepared three samples with different geometries and evaluated the maximum stress value and young’s modulus along two directions and found the maximum deflection under the maximum load conditions.Ramesh et al. carried out an experiment to evaluate the tensile and flexural properties of hybrid composites and the results are compared.Form the experiment,they found that the incorporation of natural fibers such as sisal/jute with glass fiber improve the tensile and flexural strength and these composites play a vital role in the field of engineering and technology.They suggested that these hybrid composites can be used for medium strength applications.Venkateshwaran et al. studied the mechanical properties such as tensile strength,flexural strength,impact strength and water absorption rate of sisal and banana fibers reinforced epoxy composite materials.They have observed that there is the significant improvement in mechanical strength and reduction in water absorption rate while hybridizing the sisal fiber up to 50% by weight with banana fiber reinforced epoxy composites.The banana and GFRP composites have good tensile property with minimum deflection when compared to the flax and GFRP composites.Also the banana and flax fiber reinforced composites holds more flexural and impact strengths when compared to the flax and glass fiber reinforced polymer composites.Natural fiber reinforced composites are renewable,biodegradable,environment friendly,light weight material when compared to the synthetic fiber reinforced composites.The potential applications of these composites are growing rapidly in many engineering fields especially the cost of the material is main factor and to improve erosive environment.The mechanical properties of sodium hydroxide treated natural fiber composites under saturation pressure can be improved without any major changes in mechanical behavior.Yuanjian and Isaac have investigated the impact and fatigue behavior of non-woven hemp fiber composites which is reinforced with polyester and found that there is the remarkable improvement in such properties.Li have evaluated and correlated the compressive strength,flexural strength,toughness,pot for cannabis specific gravity and water absorption rate of hemp fiber reinforced composites with different compositions.

The water absorbing ratio and the linear specific gravity of the composites are gradually reduced by adding the hemp fiber with concrete matrix.They have observed that the fiber content by weight is the important factor which affects the compressive and flexural strength of HFRC.Hemp fiber has superior reinforcement property while increasing tensile property and strong toughness in an alkali environment.Kobayashi et al. investigated the processing and characterization of hemp fiber textile composites with micro-braiding technique and found that the hemp fiber is suitable reinforcement for textile composites.Kabir et al. studied the mechanical property of chemically treated hemp fiber reinforced composites.They found that due to the rapid climate changes in environment,the physical and geometrical characteristics of natural fiber and synthetic fiber components are affected and the fibers are undergoes some irregularities and lose the maximum load carrying capacity of the materials in engineering applications.For better surface finish of the hemp fiber composites the chemical treatment process like alkali,acetyl and silane treatments are carried out.From this study they have found that the tensile strength of untreated fiber composites is much greater than the chemically treated fiber composites.The natural fiber reinforced composites were fabricated with hemp/paper/epoxy and flax/paper/epoxy by adding the paper on the both surfaces of hemp or flax unidirectional fibers and the composites are tested under tensile loading conditions.These tensile properties are compared with unidirectional composites with absence of paper between layers of composites.They found that the unidirectional natural fiber composite with one or two layers of thin paper holds the minimum variability in tensile strength and elastic modulus.The tensile strength and delamination properties of laminated composites with paper were improved when compared to without paper unidirectional composites and the modulus are slightly reduced when compared to epoxy composites.Banerjee et al. have conducted the micro-mechanics analysis of hybrid composites by using FEA software.The different hybrid laminates are prepared by using short carbon fibers and glass fibers which is reinforced with polypropylene.In this study,the elastic constant and strength properties have evaluated by using analytical formula and the results are compared with FEA results.They have observed that the negligible variability in elastic constants and longitudinal strength properties.They also found that the significant variability in transverse strength properties.Many researchers have reviewed the experimental data about hybrid composites and they observed that rule of hybrid mixtures is the prime factor to predict the mechanical properties of unidirectional interplay hybrid composites.In the present experimental study,the mechanical properties of banana–hemp–glass fiber reinforced composite materials are evaluated.The banana–hemp–glass fiber reinforced composite materials are fabricated by hand lay-up process.The properties such as tensile,flexural and impact strengths are studied and presented in detail.The results indicated that the addition of banana and hemp fibers in the glass fiber composite materials improve the mechanical properties.The base plate was cleaned of rust by scrubbing with an abrasive paper.Then the surface was allowed to dry after cleaning it with a thinner solution.After drying,the surface was coated with silicon gel.The surface was given a few minutes to get it set for the mold lay-up.The epoxy resin and the hardener are mixed in the proportion of 10:1.The curing time or the pot life,which is how it is usually notified in the laboratory charts,was 20 minutes once mixed.The care must be taken so that the resin does not cure in the curing pot itself.A constant watch over the blend in the pot was made with the aid of a stop watch.Initially the natural fibers are dried with sunlight for 3 to 5 hours.The first laminate is fabricated by using banana and glass fibers with epoxy resin over the base plate.This laminate consists of three layers glass fiber and two layers banana fiber was fabricated by hand lay process.The size of the fabricated laminate is restricted to 300×300×4 mm.The top,middle and bottom layers of each laminate are consist of glass fiber and the second and fourth layers are filled with natural fibers.Similarly the hemp-glass fiber and banana-hemp-glass fibers with epoxy resin laminates are prepared by same hand lay method.Then the three sets hybrid laminate was cured under the loaded condition for 12 hours with the help of the weight press.

Not only did the hemp knitted fabric keep the primacy in the heat transfer ability but also became the most conductive

Accordingly,a higher value of the coefficient indicates a larger surface area of the pores.Before the wear trial test,the surface area of open pores was the lowest for PAN knitted fabric,which can be easily observed visually in Fig.1.After the wear trial test,the stitch surface coefficient reduced for all the knitted fabrics,even for the PAN knit whose stitch density did not change after the wear and care cycles.This can be explained by the changes in the PAN yarn geometry.Besides,the difference between the knits in the size of the interstitial pores became smaller after undergoing the wear trial test which also can be seen in Fig.1d,e and f.The stitch volume coefficient indicates the ratio between the volume occupied by a stitch and the volume filled with yarn within the stitch.Thus,a higher value of the stitch volume coefficient indicates higher open space in a stitch.The interaction of the yarn and knit parameters resulted in the highest stitch volume coefficient for the wet relaxed hemp knitted fabric indicating the less volume within a stitch filled with yarn.After the wear trial test,the hemp knit still had the highest volume of open pores in the stitches.The changes,in percentage,in the geometrical parameters of the knitted fabrics after the wear trial test are summarized in Table 6.As can be noted,the hemp/PAN knitted fabric has undergone the biggest change in the porosity and stitch surface coefficient.This may be due to the fact that this knit was actually produced from two yarns with different intrinsic properties which in turn were induced by different fibre type.As expected,the smallest change was observed in the geometry of the PAN knit.Although conduction,convection and radiation mechanisms synchronize in the heat transfer through textile materials,cannabis grow euipment the conduction of heat by fibres is considered to be the most dominant.

However,the convective heat transfer through single jersey knitted fabrics can be an important factor considering their distinctive open structure.Therefore,besides the thermal conductivity of the knitted fabrics,their heat transfer coefficient was determined.According to the obtained results,the hemp knitted fabric exhibited the highest heat transfer coefficient meaning that its ability to transfer heat was higher,whereas the hemp/PAN and PAN knits were characterized by the same heat transfer coefficient.On the other hand,the hemp and hemp/PAN knitted fabrics exhibited comparable thermal conductivity.This led to the conclusion that the heat convection was favoured to a greater extent in the hemp knit which can be attributed to its higher open space.The thermal conductivity of the PAN knit was higher as compared to other knits,although a higher amount of air in the PAN yarn was supposed to slow down the conduction of heat especially in the pure PAN knit.In addition,the thermal conductivity of acrylic fibres is known to be lower than that of cellulose fibres.We believe that this can be explained by the findings of Kawabata according to which the thermal conductivity of a fibre is about ten times higher along its axis than across its width,and Stankovic et al.who confirmed that yarn hairiness is responsible for an increase in thermal conductivity of the fabric since the protruding fibres are arranged parallel to the heat flow.The acrylic yarn was much hairy comparing to the hemp yarn which must have contributed to an increase in thermal conductivity of the PAN knit.Despite more intimate contact among fibres in the hemp yarn in comparison to the PAN yarn,which is a presumption of higher thermal conductivity,the introduction of the hemp yarn into the hemp/PAN knit diminished the positive effect of fibres orientation,and reduced the thermal conductivity of the knit.On the other hand,the lower diameter of the hemp yarn increased the size of interstices in the hemp/ PAN knitted fabric contributing to the convection of heat,and therefore,the heat transfer coefficient was the same for the hemp/ PAN and PAN knits.In other words,the PAN and hemp/PAN knitscan transfer the same amount of heat but the conduction mechanisms prevailed in the PAN knitted fabric.The thermal properties of the knitted fabrics changed after undergoing wear and care cycles in the way that the differences in the thermal parameters among the knits became more distinctive,as can be noted in Fig.3.With an increase in stitch density of the hemp knit,the size of open pores reduced after the wear trial test,which must have resulted in a reduction in the convective heat transfer.This is an indication that the conduction of heat became the dominant mechanism of heat transfer through the hemp knit.

The explanation for this is in the fact that with an increase in stitches density,the number of interlacing points between yarn segments per unit area of the knit increases.In such a way,the contact area between the fibres was increased which improved the conduction of heat.Unlike the same values of the heat transfer coefficient for the hemp/PAN and PAN knitted fabrics before the wear trial test,the heat transfer coefficient of the hemp/PAN knit became higher than that of the PAN knit after the period of wear and care of the garments.This can be attributed to an increase in the stitch density of the hemp/PAN knitted fabric after the wear trial test by which the higher contact area between the fibres was enabled; hence the higher thermal conductivity and heat transfer coefficient.The thermal conductivity of the PAN knit reduced after the wear trial test which was attributed to the reorientation of the fibre ends as already explained.The fibre ends became perpendicularly oriented to the heat flow which reduced the conduction of heat.To determine the transient thermal parameters of the knitted fabrics,their specific heat was measured and given in Table 7 along with their volume heat capacity which was calculated by multiplying specific heat by bulk density of the material.Heat capacity of polymer materials is determined by the molecular structure and state of the polymer,and therefore the wet relaxed hemp and PAN knitted fabrics differed between each other in the specific heat capacity.Although the specific heat capacity of the hemp/PAN knitted fabric was quite close to that of the hemp knit,they differed in the volume heat capacity due to the difference in their bulk density.After the wear trial test,the specific heat capacities of the knitted fabrics changed as a result of the changes in the fibres morphology,which influenced the thermal vibrational motions at microscopic level.The pure hemp knit exhibited the biggest change in the specific heat capacity which can be explained by the fact that it was entirely produced of hydrophilic fibres.Although the hemp/PAN knit experienced the biggest change in the geometry at the macroscopic level,it seems that the changes at the microscopic level were closer to the PAN knit.Since the thermal diffusivity is a measure of rapidity of the heat transmission through the fabric,the higher value of this parameter indicates that the thermal balance will be reached more quickly,which is desirable for both summer and winter clothing textiles.The thermal diffusivity is directly proportional to the thermal conductivity and inversely proportional to the volume heat capacity causing the PAN knit to have the highest value of thermal diffusivity which is about 76% and 42% higher than that of the hemp and hemp/PAN knits,respectively.

The thermal absorptivity quantifies the transient heat conduction when human skin touches a fabric,which normally has the lower temperature than that of the skin due to which heat flows away from the skin.The higher the fabric thermal absorptivity,the higher the temperature drop in the skin,and the more intense the feeling of coolness at the first moment of contact with the fabric.It has been known that hygroscopic fibres provide cooler feeling to the fabric,whereas acrylic fibres are considered to be among the warmest.Indeed,the hemp knitted fabric was characterised by the highest thermal absorptivity,followed by the hemp/PAN and PAN knits.The changes in the transient thermal properties of the knitted fabrics after the period of wear and care of the garments are graphically shown in Fig.5.It can be observed that the order of the knits in terms of thermal diffusivity changed.Having the lowest thermal diffusivity before the wear trial test,the hemp knit exhibited the highest thermal diffusivity after the test.Since the specific heat capacity of the worn and washed hemp knit reduced,it seemed that increased thermal conductivity had a more important effect on the thermal diffusivity of this knit.The thermal diffusivity of the hemp/ PAN knitted fabric changed from being between those of the other two knits to being the lowest one.This is a consequence of the highest specific heat capacity of the hemp/PAN knit due to which it was characterized by even the highest volume heat capacity.The thermal absorptivity of the knits altered after the wear trial test,mobile grow system but the extent and direction of these changes seemed dependent on the changes in the geometry and thermal characteristics of the knits.Considering that the square of thermal absorptivity of a fabric is directly proportional to its volume heat capacity and thermal conductivity,it seems that the highest value of thermal absorptivity of the hemp knit resulted from its highest thermal conductivity which compensated for a reduction in the specific heat capacity.Observed increase in the thermal conductivity of the hemp/PAN knit after the wear trial test led to an increase in the thermal absorptivity regardless of the reduced specific heat capacity which was compensated by the increased bulk density of the knit.Although the specific heat capacity of the PAN knit was reduced to the lowest extent,and its bulk density was almost unchanged,the decrease in thermal conductivity after the wear trial test caused the thermal absorptivity of the PAN knit to become lower.

Discussed effects of the repeated wear and care cycles of the knitted fabrics are summarized in Table 8.Considering all parameters describing the thermal behaviour of the knitted fabrics in both steady-state and transient conditions,the hemp knitted fabric underwent the biggest changes.The most drastic change was the increase in the thermal diffusivity,followed by the thermal conductivity increase.The thermal absorptivity increased to the lowest extent as a consequence of the decrease in the volume heat capacity.It seems that the changes in the geometry of the PAN knit and fibre morphology,which occurred during the repeated wear and care cycles,exhibited a synergetic effect and caused both steady-state and thermal parameters to decrease.Hemp/ PAN knitted fabric exhibited the similar increase in the heat transfer coefficient,thermal conductivity and thermal diffusivity,while the increase in the thermal absorptivity was a bit lower due to unchanged volume heat capacity.Even though the hemp/PAN knitted fabrics underwent the biggest changes in the geometry after the wear trial test,the increase in thermal characteristics was moderate in comparison to that of the hemp knit.This can be explained by the fact that the hemp knit after undergoing the wear trial test was characterized by the densest arrangement of fibres and yarns within.Generally,the most important is the positive trend of the investigated thermal comfort parameters of the hemp and hemp/PAN knitted fabrics during their usage.After the wear trial test,the hemp/ PAN knitted fabric exhibited the thermal parameters which were approximately the average of those of the hemp and PAN knits,which could be attributed to the same linear density of the hemp and acrylic yarns.Therefore,it seems reasonable to expect that the thermal properties of the hemp/PAN blends can be designed by choosing an adequate combination of yarns with different linear density.By comparing the values of the thermal parameters of the hemp/PAN knitted fabric after the wear trial test with those of the hemp knit before the test,it can be concluded that the hemp/PAN knit has kept the “hemp character” after its usage.Within the broader context,the applied design of the experiment which included wear trial testing of textile products in real life conditions made it possible to observe changes in designed fabric’s properties at the exploitation stage.In such a way,durability of product’s performances can be evaluated.In spinning sector,blended yarns can be produced as a mixture of different fibres in the blow room following the steps of carding,drawing,roving and spinning or by the combination of different fibre containing slivers in the drawing stage of the yarn spinning.The blending method proposed in this study offers the knitwear companies a new possibility for designing their own fibre blends exclusively by choosing yarns available on the market,and consequently for savings and for increase their market competitiveness.In consideration of the fact that the production of knitted goods has an advantage over woven textiles in terms of tactile comfort,production cost and environmental point of view,this study aims to offer a more sustainable design approach to the development of comfortable cellulose based clothing textiles.

The morphological modification of hemp fibers is also observed by scanning electron microscopy

The intrauterine environment is a determinant for fetal development,and any perturbation that occurs during this critical period of life can predispose individuals to later life diseases.Therefore,more studies are needed to recognize and better understand the impacts of smoking marijuana during pregnancy and its impacts on future health.These aspects and the spreading legalization of recreational use of this drug deserve critical evaluation.Hemp is one of the most productive and useful plants known for a long time,it’s used exclusively for the production of medicines,in the textile field,and also used for the preparation of the drug.However,the transformation of hemp generates a high proportion of waste.Consequently,the development of recycling processes for such wastes present a great interest to the researchers,this waste has integrated the field of composite materials as reinforcing element where he has already been used in composite materials with polypropylene,unsaturated polyester and other composites.Reinforced composites with natural fibers have attracted recently more attention in order to take advantage of their low cost,low density,biodegradability and availability,ease of implementation,their high specific modulus,and ability to be recycled ,etc.These benefits are of interest for applications in various fields such as daily life,automotive …,which require lightweight materials with high performance,opportunities for retraining,the minimum impact on the environment,and reduce the cost of the material.The most serious concerned problem with natural fibers is its hydrophilic nature because they are composed of lignocellulose,cannabis grow facility which contains hydroxyl groups.These fibers are therefore incompatible with hydrophobic thermoplastics,such as polyolefin and have low moisture resistance.

These characteristics are weak points for the uses of vegetable fibers as polymer reinforcements.It is then necessary to improve them so as to avoid penalizing mechanical properties.Another important factor is the dispersion of the fibers for obtaining high mechanical properties.These problems are the main limitations to the use of such fibers as reinforcement in polymers.Thus the matrix fiber interface makes it possible to predict the physicochemical properties of the composite materials; a force applied directly to the matrix on the surface of a composite,is transferred to the nearest fiber and propagates through the fiber at the interface.Incompatible interface,leads to inhomogeneous distribution of the forces which disrupts the mechanical properties of the composites.By cons,a good interface can allow the composite has the ability to withstand stress,even after several fibers are cut because the force can be transferred to non-broken fibers.Several studies have studied the changes cellulose fiber surface properties to enhance their adhesion with a polymer matrix and reduce moisture absorption.It has been shown that an appropriate treatment applied to the fibers may result in compatibility with the polymer matrix,which improves the quality of the composites.Various methods such as plasma treatment,alkali,heat,graft copolymerization,treatment with silane or with other chemicals have improved the compatibility of the fibers with the matrix.It is therefore essential to know the chemical surface interactions between the different constituents of the composites before performing a mechanical characterization of the whole.The main objective of this paper is to study the effect of hemp fibers treatment on their individual properties and their interfacial properties when are mixed with the polyurethane matrix.the improvement of interfacial properties of hemp fibers with the polyurethane matrix,contribute to increasing the composite material properties,the choice of the hemp fibers and the matrix is due to their thermal characteristics tested in this study,this incorporation allows the manufacture of a biodegradable composite insulation.The effect of alkali treatment at different concentration on hemp fibers is shown in the Fig.1a; it is observed that the treatment does not affect the cellulosic structure since characteristic bands of cellulose appear in the same wave number.

The small band due to the C-H bending and C-O stretching of hemicellulose was shifted to a higher wave number indicating the removal of hemicellulose at the surface after treatment.The C-H stretching in aromatic methoxyl group and methylene group of lignin structure begins to disappear while increasing the percentage of NaOH in the solution.Increasing the percentage of NaOH in the solution leads to the removal of an amount of hemicellulose and lignin from the fiber surface,NaOH treatments dissolved a portion of hemicellulose and lignin constituents from the fibers which increases the amount of cellulose exposed on the fiber surface,thereby increasing the number of reaction sites.The FTIR spectra of the fibers treated with silane solution after alkali treatment were presented in Fig.1b It can be observed the appearance of a new absorption bands in the region from 800 to 1800 cm−1,and these are specific to the silane coupling agents.The band at 1203 cm−1 is assigned to the vibrations of Si O-cellulose,indicating that the prehydrolyzed silane has reacted with the hydroxyl groups on the fiber surface.The observed band at 709–780 cm−1,caused by the vibrations of Si O-linkages,indicates that the prehydrolyzed silane has led to self-condensation reactions,giving rise to a siloxane polymer.These results demonstrate that several reactions take place between the silane coupling agents and the fiber surface during the treatment.This is in agreement with the results reported in the literature.Fig.2 shows images obtained on untreated and treated fibers.It can be seen that the untreated fibers have more compounds at the surface.The surface of untreated fibers is covered with fats,waxes or polysaccharides such as the lignin,hemicelluloses or pectins and therefore much rougher.This indicated that hemp fiber structure consists of cellulose microfibrils covered with hemicellulose and lignin.From these micro-graphs it can be seen that the cellulosic fiber surface was covered by non-cellulosic constitute.The treated fibers have a smaller diameter than the untreated fibers and their surface roughness is reduced due to the partial dissolution of the amorphous portions of the fibers.More the percentage treatment increases the fiber surface becomes depleted of non-cellulosic material.

The shows a change in the appearance of the fiber surface which may be due to the formation of silane-coupling agent on the surface of hemp fibers,the fiber surface was completely covered which confirmed the time required to achieve the equilibrium adsorption respected.Natural fibers are semi-crystalline materials composed generally of an amorphous part basically consisting of the macromolecules of lignin and hemicellulose and a crystalline portion of cellulose.The X-ray diffractograms of treated and untreated hemp fibers are indicated in Fig.3,they show the presence of peaks characteristic to cellulose molecule located at,15.2° and 16.6°,correspond respectively to the crystallographic plans 002,101 and 101.The measuring crystallinity index by Segal method presented in Table 1 reveals an improvement of crystallinity rate when the treatment percentage increase,which suggests that the alkali treatment removes non crystalline portion of the fiber increasing the percentage of cellulose in the fiber,this improvement has been observed up to 8% of NaOH treatment,after we have seen a decrease in the crystallinity index,this may be caused by the increased concentration of NaOH affecting the cellulose structure.Other study entrusted the increasing of crystallinity index after the alkaline treatment to the change of the crystalline structure of the cellulose.Studies have shown that Na + has a favourable diameter and is capable to expanding the space between the lattice planes.This leads to the formation of a network cellulose-Na-I,with relatively large distances between the cellulose molecules.The created spaces are filled with water molecules.In this structure,the -OH groups of the cellulose are converted to -ONa groups,widening the dimensions of the molecules.Subsequent washings with water will remove the Na ions bonds and convert the cellulose into a new crystalline structure of cellulose II.Sodium hydroxide allows for complete processing of the cellulose network I cellulose II with a higher crystallinity index.The resistance of the natural fibers is affected by many factors,the high molecular weight of cellulose chains,the crystal structure of the fibers and the microfibrillar angle are the most influences parameters of the mechanical properties of plant fibers.Fig.4a and b show the tensile strength and Young’s modulus respectively of untreated and alkali hemp fibers it can be seen that the treatment increase tensile strength and young’s modulus,this augmentation is observed up to 8% of treatment after this percentage,it is noticed the decrease in mechanical properties of hemp fiber.The increase in mechanical properties is mainly due to the partial removal of hemicellulose and lignin which causes the increase in the crystallinity index of the fibers and therefore the fibers becomes more rigid.The elimination of a certain amount of lignin and hemicellulose allows the relaxation of the microfibrils and their reorganization along the principal axis of the fiber giving rise to a more rigid structure,cannabis grow system the increase in the percentage of NaOH eliminates over amount of lignin and hemicellulose which will create more space empty that the microfibrils reorganizes.

Progressive augmentation of concentration in sodium hydroxide can damage the crystalline structure of the cellulose and therefore has a negative effect on the mechanical properties of the fiber which was observed at 10% of treatment.This behavior has been observed in previous works.The progressive increase in the crystal index of the fibers allows the improvement of the mechanical properties of the fibers,which can increase the mechanical properties of the composite materials after their insertion in a polymer matrix.The alkaline treatment leads to the elimination of a certain amount of impurity and wax on the surface of the hemp fibers which increases the diameter as well as the number of pores on the surface of the fibers and consequently the thermal conductivity increases.The increases of the treatment concentration are accompanied by the increase of the thermal conductivity it has been noticed in another work dealing with oil-palm fibers.The alkali treatment led to a small increase in the value of the thermal conductivity of 13% and 15% for the alkali fibers at 5% and 8% successively after these percentages we notice a strong increase of 24%.Fig.6 show the thermal conductivity of the hemp fibers measured at three temperatures.As the temperature increases,the thermal conductivity of the samples increases because in this case the vibration of the phonons is the thermal carrier and the moisture in the natural fiber begins to evaporate and escapes from the sample.In view of the results obtained,the hemp fibers have a very good conductivity.They can then be used as insulation in cold production or preservation systems in particular compared to polyurethane and polystyrene foam or glass wool which has an average conductivity of 40 mW/m.K.Several experimental techniques are used to predict the mechanical behavior of the fibers after their insertion in composite materials,the fragmentation test,the micro-bond test the push-out test and the pull-out test.These techniques make it possible to calculate the interfacial shear stress IFSS by measuring the maximum force exerted on the fiber in order to extract it from the composite material.Fig.7 shows that pull the fibers from the polyurethane matrix are carried out in three steep.Firstly,the force evolves non-linearly,or it is carried directly by the matrix and transferred from the matrix to the fiber by the fibermatrix interface,during the second stage,the force reaches its maximum and then begins to decrease,this is due to less interpenetration between the matrix and the surface of the fiber,indicating a release of stored energy.This reduction in the tensile force is triggered by the extraction of the fibers from the matrix which takes place after the fracture of the adhesive at the fiber-matrix interface,which makes the fiber detached and starts to slide.Tobacco smoke can cause numerous health related issues.While cigarette smoking is associated with the development of certain respiratory diseases,the causal link between the onset of asthma and smoking has not been established.To date,studies that examined the association between cigarette smoking and incident asthma have shown mixed results.Previous work on the topic has reported an increased risk for adults and adolescents but others reported no statistically significant associations.Although what causes the onset of asthma is still relatively unknown,experts in the field have reported that cigarette smoking or exposure to second hand smoke can certainly trigger asthma symptoms and severity.Overall cigarette smoking or second hand smoke can relate to many long term respiratory health issues,but it can also inflfluence more immediate issues for people with asthma including increased coughing and airway inflammation.For adults in California,cigarette smoking was associated with asthma severity,worse asthma-specific quality of life and greater hospitalization for asthma.Furthermore,active cigarette smoking for people with asthma can lead to accelerated loss of lung function and a decreased response to corticosteroids over time.In the past,studies on smoking behaviour in adolescents was focused on cigarette use; however,more recently other types of smoking such as water pipes,marijuana or now electronic cigarettes have emerged as a concern.

A recent toxicogenomic study conducted in our laboratory compared three different cigarette smoke condensates

It should be noted that the mycelium specimen under 98 % RH reached the maximum mass gain around the seventh day in the sorption test, and after that underwent mass loss and showed signs of mould growth on the surface. As a result, maximum mass gain instead of equilibrium mass is used to calculate the equilibrium moisture content at 98 % RH as shown in Fig. 6. The equilibrium moisture content under the desorption process is only slightly higher than the adsorption process, and no significant variation between both curves for all samples. Thermogravimetric analysis of the samples is shown in Fig. 9. All four samples are thermally stable up to about 200 ◦C, and thereafter start to decompose and reach their maximum rate of weight loss between 300 and 350 ◦C. It is, therefore, necessary to protect these insulation composites from fire hazards with other fire and heat resistant components, e.g. bricks, sheathing boards, etc. The decomposition process of the samples follows a similar trend, corresponding to hemicelluloses being pyrolyzed in the range of 200 and 300 ◦C, depolymerized cellulose in the range of 300 and 350 ◦C, lignin components pyrolyzed in the range of 225 and 450 ◦C. For cork composite, depolymerization of suberin appears between 400 and 500 ◦C. The second peak at 400 ◦C is also observed on the grass composite, contributed by other recycled materials mixed in the composite. Likewise, a similar small peak can be noticed for the hemp composite where recycled materials are also used. All composites end their volatile emissions at around 450 ◦C with a remaining char residue of around 20 to 30 % of the original dry weight. Based on the thermal conductivity findings in Fig. 7, the insulation thickness for both wall types and all four studied insulation materials are formulated to achieve an overall R-value of 4.7 K⋅m2⋅W− 1 as per the Dutch requirement for an exterior wall in a residential building, or equivalent to a U-value of 0.205 W⋅m− 2⋅K− 1. The thicknesses are listed in Table 4,cannabis grow system and it can be seen that all four materials require a higher wall thickness in comparison to reference Cellulose insulation material.

The transient thermal transmittance U-value of the investigated insulation materials under two different wall types and six different climates are investigated and summarized in Fig. 10. Only transient Uvalues in the ‘heating period’ from October to March are included as the U-value under warmer months will yield non-sensible results and is not of interest in this study. In general, all four insulation materials display matching trends of transient U-value under a combination of the same climate and wall type, however, diverge significantly when compared across different climates or wall types of the same material. Under continental climate Dfa , Dfb and Dfc , the insulated walls provide uniform thermal insulation performance close to the designed U-value at 0.205 W⋅m− 2⋅K− 1 in the heating period. Higher transient Uvalues however are observed on the walls under temperate climates Cfa , Cfb and Cfc , coincide with their milder and wetter climate profiles. On the whole, the insulated timber frame walls perform better than the brick walls, in particular under temperature climates, when a similar initial designed U-value is set for all cases. This is a consequence of the thicker and denser brick layers which hamper the moisture transport in the wall assemblies, causing higher moisture accumulation in the insulation material. This pattern reaffirms the central role of exterior climates and type of building envelop design in the evaluation of building insulation performance, when a similar category of insulation materials are to be considered, in this case, the bio-based insulation materials. If without considering durability aspects from potential deterioration due to mould growth under a humid environment, or no concern of overall wall thickness owing to the thickness of insulation layer required for the intended U-value, there is no specific material to be recommended based on their transient U-value performance. However, when the wall thickness is of interest, the cork composite with its less demanding thickness requirement is the preferred selection compared to other investigated bio-based materials, followed by the grass composites. The equilibrium moisture content in the investigated bio-based insulation composites under two different wall types and six different climates in a simulated year is shown in Fig. 11.

Mycelium composite shows the highest moisture content under all climates and wall types, while cork composite shows the lowest and the most regulated moisture content throughout the year in general. Both grass and hemp composites exhibit similar moisture content to the reference cellulose insulation material. These dynamic moisture content of the composites are in agreement with their sorption isotherm, i.e. higher sorption capacity of mycelium composite and the opposite for cork composite. Higher moisture content in an insulation layer can be found at the near-interfaced layers, in the case of the selected wall type and climates, they are either at layers next to the exterior sheathing board or behind the interior sheathing board.A few observations can be generalized based on the climate types: for Cfa and Dfa , moisture tends to accumulate at the exterior interface during the winter period and interior interface during the summer period; for Cfb , Dfb and Dfc , moisture accumulation is generally found on the exterior interface during the winter period, and while the moisture content is increasing on the interior interface during summertime it is still not exceeding that of the exterior side; and for Cfc , the moisture content at the exterior interface is always higher than the interior interface. It can be established that the insulation layer at the exterior interface has the highest averaged moisture content under all six climates, and consequently is most likely subjected to mould growth and degradation compared to other parts of insulation under different climate conditions. In terms of wall type, insulation material inside the timber frame walls have generally lower moisture content at the exterior interface than those inside brick walls across different climates except Dfc. The opposite trend is observed at the interior interface where the insulation layer in timber frame walls has higher moisture content compared to brick walls. Note that no vapour retarder is included in the design of all simulated walls to retard the vapour diffusion process, and a ventilated air cavity is included in all cases to provide additional hygrothermal regulation to the overall wall assembly. After exposing the test specimen for four weeks to high humidity in a desiccator filled with water, the specimen is visually inspected with the naked eye and microscope for the presence of mould. Fig. 13 shows photos taken on the specimen with and without high humidity conditioning. The fungal growth on the test specimen is assessed according to ISO 846 and the intensity scales of mould growth are assigned to them in Table 5. Note that mould growth was already observed on mycelium composite conditioned under 98 % RH in the sorption test, as discussed in section 3.1.

Discolouring on the hemp composite can be perceived with naked eyes and fungi are distinguished easily under a microscope. For the grass composite, no obvious mould growth or discolouring is observed with the naked eye, however, deterioration of the fibres is noticeable under the microscope. No apparent deterioration, mould growth or discolouring is detected on the cork composite. These results are in agreement with the literature: similar mould development can be distinguished with the naked eye on the mycelium-miscanthus test sample by Dias et al.; fungi contamination can be observed under a microscope on hemp shiv composites by Viel et al.; on the other hand mould development on grass and cork composite is not presented on the literature. Marijuana smoke is a complex mixture composed of thousands of chemical compounds,many of which are qualitatively similar to those found in tobacco smoke.Like tobacco smoke,marijuana smoke has been associated with numerous adverse pulmonary effects in humans including airway inflammation,chronic bronchitis,edema,mucus hypersecretion,and the impairment of large airway function and lung efficiency.Moreover,Aldington et al.showed that the impairment of large airway function and lung efficiency is 2.5–5 times greater in marijuana smokers than tobacco smokers.Like tobacco smoke,previous studies have also shown marijuana smoke to be genotoxic both in vitro and in vivo.In addition,it is suspected that marijuana smoke may be carcinogenic.Indeed,some agencies such as the California Environmental Protection Agency have placed marijuana smoke on their list of chemicals known to cause cancer.However,since there is a paucity of marijuana-only smoking populations to complete definitive studies,epidemiological studies conducted to date are limited in scope,and often confounded by concurrent tobacco smoking.Therefore,a clear and widely accepted empirical link between marijuana smoking and cancer does not exist.Information on the pharmacokinetics of marijuana smoke,and the mechanisms by which it may cause adverse effects,is also limited.Several mechanisms have been proposed including genotoxicity,alterations in endocrine function,alterations in cell signaling pathways,marijuana grow system and immune suppression.However,many of these findings are based on the testing of individual cannabinoids found in marijuana smoke,as opposed to the whole smoke or smoke condensate.

Genome-wide expression profiling may provide information to permit a better understanding of the toxicological pathways perturbed by exposure to marijuana smoke.Currently,there are no published studies that have used a whole genome toxicogenomics approach to evaluate responses to marijuana smoke.However,Sarafifian et al.employed a targeted stress response gene expression array to evaluate the effects of 9-tetrahydrocannabinol,the main psychoactive component of marijuana,on human small airway epithelial cells.They observed significant changes in genes related to xenobiotic metabolism,DNA damage response,inflammation and apoptosis.micro-array technology has been used more extensively to evaluate gene expression changes following exposure to tobacco smoke.For example,Sen et al.reviewed 28 studies examining transcriptional responses to complex mixtures including whole cigarette smoke and cigarette smoke condensate,and included in vivo and in vitro studies using human and rodent tissues.It was determined that the pathways most frequently affected by tobacco smoke were oxidative stress response,xenobiotic metabolism,inflammation/immune response,and matrix degradation.Other micro-array studies have noted a DNA damage response leading to cell cycle arrest and apoptosis to be among the top pathways affected by tobacco smoke.The results of this study showed extensive overlap with the affected pathways highlighted in the review by Sen et al..Our study also showed that gene expression is remarkably similar across cigarette brands,and there is limited variation in the genotoxic potency of cigarette smoke condensates.In contrast to these findings,our earlier work revealed that tobacco and marijuana smoke condensates differ substantially in terms of their genotoxicity.More specifically,MSC were observed to be significantly more cytotoxic and mutagenic than matched tobacco smoke condensates.In addition,TSC appeared to induce chromosomal damage in a concentration-dependent manner,whereas matched marijuana condensates did not.The mechanisms underlying these differences in toxicity are unclear and warrant further investigation.As an extension of our previous work,the objective of the present study is to employ a toxicogenomics approach to compare and contrast the molecular pathways that are perturbed by MSC and TSC.A murine pulmonary epithelial cell line was employed for in vitro exposures to both MSC and TSC.The results show that the pathways perturbed by MSC as compared to TSC are largely similar.However,subtle differences in gene expression provide insight into mechanisms underlying the observed differences in toxicities.The tobacco samples consisted of a popular Canadian brand of fine-cut tobacco obtained from a local retail store.The cigarettes contain Virginia flue-cured tobacco,which is distinct from the mixed tobacco blends typically found in American cigarettes.The cannabis samples consisted of a standardized product,grown under strictly controlled and documented conditions.The product was obtained from Prairie Plant Systems Inc.,and all samples were from harvest #55.Upon harvest,flowering heads were dried to a moisture content of approximately 10%,milled to 10 mm,packaged and irradiated.The preparation and combustion of the cannabis and tobacco cigarettes was conducted by Labstat International Inc.as described previously.Briefly,samples of marijuana and tobacco were laid out on aluminum trays and conditioned at a temperature of 22 ◦C and a relative humidity of 60% for 48 h.775 mg of each product was transferred to a cigarette-rolling device,and cigarettes were prepared using commercially available cigarette papers,all without filters.All cigarettes were stored in sealed plastic bags until combustion.Samples were removed from the bags and conditioned for a minimum of 48 h prior to smoking,as required by ISO 3402:1999.The cigarettes were smoked according to a modified smoking regime intended to reflect marijuana smoking behavior.

Maternal cigarette smoking is typically considered to be a risk factor for SPTB and SGA

Data from this analysis were obtained from the SCreening for Pregnancy Endpoints study, which aimed to build a clinical database and pregnancy bio-bank to screen candidate markers of pregnancy complications. The SCOPE study recruited nulliparous women with singleton pregnancies between November 2004 and February 2011 from one centre in each of Australia, New Zealand, and Ireland, and three centres in the United Kingdom. Ethical approval was obtained from local ethics committees [New Zealand AKX/02/00/364, Australia REC 1712/5/2008, London, Leeds and Manchester 06/MRE01/98 and Cork ECM5 05/02/08] and all women provided written informed consent. Women were invited to participate prior to 15 weeks’ gestation when attending hospital antenatal clinics, obstetricians, general practitioners or community midwives, and were interviewed and examined by a research midwife at 15 ± 1 and 20 ± 1 weeks of gestation. The exclusion criteria included women who were considered to be at high risk of PE, SGA or PTB due to underlying medical conditions , previous cervical knife cone biopsy, three terminations or three miscarriages or if their pregnancy was complicated by a known major fetal anomaly or abnormal karyotype, or if they received interventions that may modify pregnancy outcome. Details of maternal age, BMI and socioeconomic index1, medical and family history, along with dietary and lifestyle questionnaires with self-reported marijuana and cigarette smoking were recorded at 15 weeks’ and 20 weeks’ gestation and entered into an internet-accessed, password-protected centralised database with a complete audit trail. The number of episodes of marijuana use over 3 months was also recorded at 15 weeks and 20 weeks of gestation. Other drug use was also recorded, including cocaine, amphetamines, substance 1 a scale between 10 and 90 generated using an algorithm involving age, income and education. A higher score indicates higher socioeconomic status. It is a validated measure of individual socioeconomic status. P, Ecstasy, opiates, and hallucinogens, with less than 0.6% of women who have taken these drugs 3 months prior to or during pregnancy in SCOPE, but there were insufficient data to be included for analysis.

Self- reported marijuana and cigarette smoking status were classified into five categories in univariable and multi-variable analysis,hydro tray with ‘non-smoking’ or ‘never used marijuana’ as the reference categories. The number of reported episodes of marijuana use was included as a continuous variable for frequency effect estimation. Use was self-reported where women provided the number of joints or cones used. Spontaneous preterm birth was defined as birth at less than 37 weeks of gestation that was not a result of medical or obstetric intervention. Small for gestational age was defined as a birthweight of less than the 10th customised centile, adjusted for maternal height, weight, parity, ethnicity, gestational age at delivery and infant sex. Preeclampsia was defined as gestational hypertension accompanied by proteinuria. Gestational diabetes mellitus was defined as a fasting glucose of 5.5 mmol/L or higher in a Glucose Tolerance Test, a 2 h level of 8 mmol or higher, or a random glucose level of 11 nmol/L or higher. Universal screening was not employed for GDM in the UK and Ireland, where only women identified at risk based on factors such as family history and BMI were screened.A total of 5588 participants were included in the analysis, with 1155participants recruited from Australia, 2014 from New Zealand, 1765 from Ireland, and 654 from the United Kingdom. Within the 1514 pregnancies with complications, 278 had PE, 633 had SGA, 236 had SPTB, 470 had GHT, and 143 had GDM. Details on age, BMI, SEI, as well as marijuana use and cigarette smoking status were complete for all participants. Marijuana and cigarette smoking status were compared between non-cases and each of the outcomes separately using Fisher’s exact test. Although about 4% of women had more than one pregnancy complication, each outcome was analysed separately compared with non-cases. Continuous factors, including maternal age, BMI and SEI were compared using Student’s t-test. To investigate the effects of marijuana use between smokers and non-smokers, analysis of marijuana use, stratified by cigarette smoking status for each outcome was performed. Breslow-Day test was used to assess the homogeneity of the odds of marijuana use between cigarette smokers and non-smokers, along with an adjusted common odds estimated from Mantel-Haenszel test.

Marijuana and cigarette smoking status were then analysed with mixed effects logistic regression to determine the association with pregnancy outcomes, adjusting for maternal age, BMI and SEI, and with recruiting centre differences accounted for as a random effect. Interaction tests were also performed by comparing logistic regression models that included interaction terms. A linear mixed model was also fitted for length of gestation, with quadratic terms for the number of times marijuana was used over the preceding 3 months at 15 and 20 weeks of gestation, age, and BMI, to investigate the dose effect of marijuana and cigarette smoking status on the length of gestation adjusted for other factors in the model. The estimated power of this analysis, involving logistic regression with interaction terms, is 0.99. All statistical analyses were performed using R version 3.2.0.It was important to determine whether the association with marijuana use was due to concomitant cigarette smoking. Breslow Day test showed no evidence of heterogeneity in the association of marijuana use and pregnancy outcomes between smokers and nonsmokers , which indicates that the association between marijuana and SPTB was consistent regardless of cigarette smoking status. Hence, when comparing any marijuana use, three months prior to or during pregnancy, between cigarette smokers and non-smokers, there was a significant independent association between any marijuana use and SPTB. While the association between marijuana use and SPTB was independent of smoking status, the Mantel-Haenszel test further indicated that the overall association was also significant , with an adjusted common odds of 2.28. That is, the odds of SPTB for any marijuana use three months prior to or during pregnancy was more than doubled for both cigarette smokers and non-smokers. Regarding the interaction effect of marijuana in women who ceased cigarette smoking during pregnancy, results from Breslow Day test on the homogeneity of the odds of any marijuana use , between women who continued cigarette smoking before 20 weeks’ gestation and those who stopped smoking, showed no evidence of heterogeneity,with a Mantel-Haenszel adjusted odds of 1.97. This indicated that the effect of marijuana use was not only independent of any cigarette smoking three months prior to or during pregnancy , but was also consistent, with nearly doubled odds, irrespective of whether cigarette smoking ceased prior to 20 weeks’ gestation.

Results from Logistic regression with an interaction term between marijuana use and cigarette smoking status also showed no significant interaction effects on SPTB.The results from linear mixed modelling showed that marijuana use in first or second trimester had significant effects on length of gestation, when adjusted for age, BMI, SEI, cigarette smoking status, and alcohol consumption. The predicted length of gestation was lower for women who continued to use marijuana at 20 weeks of gestation for both cigarette smokers and non-smokers, with an estimated gestation of less than 37 weeks when more than 100 episodes of marijuana use within the previous three months before 20 weeks’ gestation. It should be noted that there was a small but significant decrease in the predicted length of gestation for cigarette smokers compared to non-smokers. However, our data show that continued marijuana use at 20 weeks of gestation has a greater effect on gestation irrespective of cigarette smoking status. Linear mixed modelling indicates a modest reduction in gestation in women who ceased marijuana use at 15 weeks’ gestation. However, in women who continued to use marijuana at 20 weeks’ gestation, there was a much greater decline in gestational age at delivery.Marijuana use is increasing in women of reproductive age and its continued use in pregnancy has been of concern for some time. In addition, we have anecdotal evidence to suggest that some pregnant women are using marijuana to reduce nausea in early Fig. 2. Predicted length of gestation and number of episodes of marijuana use in women who did or did not also smoke cigarettes in the previous 3 months. Note: actual range of marijuana use 0–450 episodes in 3 months. pregnancy. In this large prospective cohort of nulliparous women we have demonstrated that continued maternal use of marijuana at 20 weeks’ gestation is a major contributing risk factor for SPTB. Univariable analysis showed a significant association of marijuana use at 20 weeks’ gestation with SPTB and also SGA, but when adjusted for other factors,planting table in particular cigarette smoking, marijuana use was only a significant independent risk factor for SPTB. Furthermore, if marijuana use was continued at 20 weeks’ gestation, women were over five times more likely to deliver preterm than nonusers. Of the women who continued to use marijuana at 20 weeks’ gestation and delivered preterm, nearly 64% delivered at less than 32 weeks’ gestation. Our data do not have sufficient power to determine whether there is a gestational age prior to 20 weeks by which it is advisable to cease marijuana use. Hence, at this stage we recommend that it is prudent to abstain from marijuana use during pregnancy.

Based on the current findings and some earlier reports, it is likely that maternal marijuana use is an independent risk factor for SPTB. It has been shown that the active compound of marijuana and its metabolites are able to cross the placental barrier and thereby have the potential to directly affect perinatal outcomes. Whereas the results from this study are in agreement with other studies, it needs to be noted that a few American and a UK prospective cohort studies did not find an association between marijuana use and SPTB. However, these studies have a higher percentage of black race, whereas there are 89.9% Caucasians in this study. Although the studies have also adjusted for ethnicity, age, BMI, and other lifestyle factors, interaction tests were not performed in the analysis to examine the interaction effects of marijuana use and cigarette smoking on pregnancy outcomes.While African American ethnicity has been associated with an increased risk of SPTB, it has also been commonly associated with lower socio-economic status. The relationship of low SEI with pregnancy complications was apparent in this study, where SEI was significantly negatively associated with PE, GHT, GDM, SGA, and SPTB. When adjusted for age, BMI, cigarette smoking, and marijuana use, higher SEI was a protective factor, with a 1–2% decrease in the risk of PE per unit increase in SEI. Similar trends were also seen in previously published SCOPE data. However, the results from the current study showed no significant interaction effects between marijuana use and SEI, suggesting that the association between marijuana use and SPTB was also independent of socio-economic status. Despite a borderline significance for alcohol consumption at 15 weeks’ gestation for PE risk, our results are consistent with a study by Klonoff-Cohen et al., which showed that maternal alcohol consumption does not appear to have a significant association with preeclampsia. Alcohol consumption during first trimester was not associated with SPTB, consistent with a previous SCOPE publication. However, continued alcohol consumption at 20 weeks’ gestation is a protective factor for SPTB, and a recent study by Lundsberg et al. also showed that alcohol consumption during third trimester was associated with a decreased risk of PTB but not when consumed during early pregnancy. The mechanism of this effect is still unknown. However, as maternal alcohol consumption may damage the fetus we cannot recommend it during pregnancy and indeed the National Health and Medical Research Council Guidelines recommend against its use in pregnancy.Indeed, maternal cigarette smoking at 20 weeks’ gestation was significantly associated with risk of SPTB and SGA in univariable tests, but no longer significant for SPTB when adjusted for other factors, including BMI, SEI, age, and marijuana. Similar results have been found previously in a study by Dekker et al, which incorporated multiple novel risk factors for SPTB. In the current study an association was seen between smoking and SPTB , but cigarette smoking was not found to be an independent risk factor for SPTB after adjustment for marijuana use. Nevertheless, continued cigarette smoking is a significant risk factor for many pregnancy complications including stillbirth, placental abruption and SGA and women should be encouraged to quit before or in early pregnancy.

Marijuana use also has a role as a risk factor for myocardial infarction

Hemp is an annual herb plant which is used for production fibre for such as rope, sail and clothing as well as the seed crushed for oil, food and feed. Due to the outer portion of the hemp stem contains strong and long bast, fibre provides a strength and high quality textile, while inner of the stem so called hurd also used for paper and building material. After Thai royal project interested in developing industrial hemp as an economic crop to support the hill tribes, the quality seed are needed to propagate and disperse for the farmer. In addition, the cultivation of hemp is being permitted in Thailand especially in the north, but under strict control and monitoring by office of the narcotics control board of Thai. Hemp is determined a dioecious crop and seed production is required a wider space from plant to plant than producing as fibre. In addition as an annual crop, cultivated seed are usually sown in early March and late of May, and harvested in the end of November under preferable natural temperature 14 – 27 ºC. Therefore, they are attractive to produce exceed seed supply and then stored for one or several years for cultivation. Storage of seed is an important process of plant production to avoid unfavourable environmental conditions and the acceleration of the deteriorations, which is started after harvest. Storage conditions play an important role to maintain high seed quality, which directly related to environmental conditions. However, the sensitivity of seed to high temperature is depended on the water content that the higher moisture content, the looser viability. Seed deterioration is associated with the genotype, seed history and their physiological and chemical compositions. As in hemp, seed is determined as an orthodox seed that can be dried to low moisture content and stored at low temperature for several years. Nonetheless, the seed contain 20 – 25% protein, 20 – 30% carbohydrates, 10 – 15% insoluble fibre and especially 25 -35% oil which was considered to be the major contributors to seed deterioration as previous demonstrations of soybean , peanut and sunflower. For hemp seed, it was suggested that seed should be dried until the moisture content lower than 12%. Consequently,vertical farming for further storage, either high or low relative humidity affected the moisture equilibrium of seed due to hygroscopic property. Then, the type of container was important for protecting moisture immigration. 

As in closely fibre species such as kenaf , seed stored at 8% mc remains viable for up to 5.5 years when stored at 8 ºC and stored above 10 ºC and 12% mc showed significant decrease in seed viability. In parallel, Meints and Smith, also found that germination of kenaf under ideal conditions remained high in seed stored up to 4 years at 10 ºC and did not show appreciable differences in field emergence or performance through the growing season. Determination of hemp seed qualities which were derived from segregation of the local land race would assist the Royal project and further seed supplier in reliable on fibre hemp production. The objectives of this study were to determine the impact of storage conditions and hemp seed quality losses during year storage. These experiments were conducted to compare storage condition affecting different hemp seed cultivars by observing the physiological of seed qualities. The moisture contents at which these changes are observed among cultivars, and continuously involve in the change of stored seed quality. The seed cv. RPF2 contained higher moisture content than the others and also showing lower initial germination illustrated significantly decreased with storage time when packed in both seal aluminium foil and plastic bag at ambient temperature. McDonald stated that the effect of high temperatures on seeds quality is highly dependent on their water content and the loss of viability was more rapid when the seed contain high moisture. However, the quality of seed packed in both materials was not different during 5 month, but after that aluminium foil had an adverse effect on reduction of seed viability and vigour than plastic bag during 5 – 8 month. This suggested that high moisture content seeds might be closely oppressed to dry air and then water remove to the surface because of hygroscopic of which higher moisture content was observed in seed packed in aluminium foil. The change of moisture content was not different when seed stored in aluminium foil at 15, 4 and –4 ºC, while the seed germination and vigour was also remained. The result revealed that aluminium foil has better water and oxygen proved properties than plastic bag made from polypropylene which the exchange were 0.0914/m2 /hr and 0.2472/m2 /hr for oxygen; 65 g-water/m2/hr and 1378 g-water/m2/hr for water, respectively. This suggested that initial moisture content and germination are the main factor for providing seed longevity. Hemp seed containing high moisture content stored at room temperature maintained the germination and vigour only up to 5 months of storage, after that the conditions and aging was deleterious to seed viability. Seed deterioration is associated with various biochemicals, metabolic and physiological alteration including loss of membrane integrity and cell compartmentalization, decreasing in ATP production and impairment of RNA and protein biosynthesis. 

Moreover, lipid peroxidation and free radicals were considered to be the major contributors to seed deterioration , especially, at high temperature, it was mainly related to membrane damage and alteration of energy metabolisms as demonstrated in sunflower. In the other hand, seed germination and vigour of low seed moisture content as cv. RPF3 contained in aluminium foil at room temperature remained viable. This previous study mentioned that the dehydration of seed could prevent thermal denaturation. Marijuana use dates back to 2727 BC to Chinese Emperor Shen Nung. After spreading through the Greek and Roman empires and into the Islamic empire of North Africa and the Middle East, it was brought to the Western hemisphere by the Spanish. Originally lauded for its utility as fiber, it was not until its migration into North America that it began to be used in a similar fashion as it is today. Used in the form of hemp, it was seen throughout society as rope, clothing and even paper. While marijuana has been used by Americans recreationally for years, it is a subject that is becoming more commonplace in our modern society. According to the National Institutes of Health, marijuana use in 2015e2016 rose from 4.1% to 9.5% of the U.S. adult population. With more states eliminating the legal ramifications of its use and a growing debate about its federal legality, this is a subject that routinely makes local and national headlines. With a diverse array of commercial products becoming available from chocolate squares to oral sprays, marijuana is also no longer restricted to a rolled cigarette. The medical community has also joined the debate. The most obvious correlation between medicine and marijuana is medicinal marijuana. Marijuana’s effects have been well documented, allowing the push for its use as medicine within multiple specialities. Proponents of its use point to its effects on the endocannabinoid system. Studies show that through its impact on different pathways it may be used as an analgesic, immunosuppressant, muscle relaxant, anti-inflammatory agent, appetite modulator, antidepressant, antiemetic, bronchodilator, neuroleptic, antineoplastic and antiallergen. Medical marijuana also differs in chemical composition, containing a higher tetrahydrocannabinol concentration and less cannabinol than the recreational version. This is even before taking into consideration the various extraneous agents that may be found within the available recreational drug.

There is however, very little, if any research evaluating marijuana’s use in surgery. This paucity of literature presents a problem. While many surgeons may ask about recreation drug use including marijuana, many other drugs have established evidence based outcomes that allow variation in surgical planning as needed. However, when it comes to marijuana, surgeons are left to determine what to do with this information on their own.Despite the multiple studies on the physiologic effects of marijuana use, clinical studies, if any, are not cited in the medical literature. This study reviews the literature available on marijuana’s effects and discusses potential complications that may result within the surgical setting. With a reported estimation of 10%e20% of patients between the ages of 18 and 25 years regularly using marijuana, this review seeks to become an initial step for further exploration of the subject and to reveal why there is a need for more in-depth research.Due to limited research and reviews on this subject, information was utilized from articles on surgery in various fields, such as orthopedic, dental and bariatric with anesthesia considerations and general topics related to marijuana also examined. The following information was gathered: marijuana’s prevalence in the United States, marijuana’s effects on the cardiovascular system and pulmonary system, potential coagulopathies, marijuana’s effects in relation to anesthesiology, evidence based screening methods for recreational drug use, potential surgical complications that may result from marijuana use,flood tray and recommendations on marijuana use and surgery.When marijuana is smoked, THC and other cannabinoids are absorbed rapidly through the lungs with effects peaking in 15 minutes. These effects can persist for up to a dose-dependent 4 hours in the acute setting. When ingested orally however, onset of effects is slower but has a longer duration of action , due to continued absorption in the gut. This is despite a lower bioavailability due to first-pass metabolism by the liver which results in a blood concentration 25% of what is obtained if smoked. The cognitive/psychomotor effects can be present for up to 24 hours regardless of administration route. Cannabinoids are highly lipid soluble. This leads to a slow release into the bloodstream with a single dose not fully eliminated for up to 30 days. The cardiovascular effects of marijuana use range from benign to worrisome based on the timeline of use and dosage.

In a series single blind study comparing the effects of high and low doses of THC in healthy young men, tachycardia was induced beginning within the time of inhalation, and persisting at least 90 minutes, with the maximum heart rate reached at an average of 30 minutes. The study also found a significant elevation in systolic and diastolic blood pressures as well as the presence of premature ventricular contractions in subjects who received the higher doses. These experiments showed a correlation between the dose and the tachycardic and cardiovascular changes. In addition, Malit et al.’s study on the effects of intravenous THC found the majority of patients to exceed the 100 beats per minute mark but also experience intermittent spikes in heart rate with a possible etiology of psychological distress. Beaconsfield et al. postulated a mechanism of beta adrenergic stimulation for the tachycardia as he was able to block the tachycardia with the use of propranolol. Pharmacology lays credence to this. At lower or moderate doses, marijuana increases sympathetic activity reducing parasympathetics and producing an elevation in heart rate, cardiac output and blood pressure. However, the opposite is true as the dosage increases. At high doses, the parasympathetic system takes over, leading to bradycardia and hypotension with animal studies postulating that the sympathetic inhibition occurs due to the bioactive constituent of cannabis’s effects on the CB1 receptors. In addition to sinus tachycardia, marijuana use has been linked to multiple electrocardiogram changes in various case reports. Daccarrett et al. found Brugadalike changes in a 19 year old male with a known history of cannabis use and no anatomical/functional abnormalities. A case was also reported in which cannabis use was linked to the development of atrial flutter and atrial fibrillation, while other studies have reported the presence of sinus bradycardia and AV block.Aronow et al., found that while comparing marijuana to placebo, cannabis causes an increase in carboxyhemoglobin, a resultant increase in myocardial oxygen demand, decrease in oxygen supply as well as an induction of platelet aggregation. One case report showed a 21 year old male who presented with a ST elevation myocardial infarction due to plaque rupture as a complication of marijuana use. In Mittleman et al.’s analysis of over 3,800 cases of myocardial infarction, 124 patients reported use within the last year of which 37 reported use within 24 hours, with 9 reporting use within an hour of the event. The study found a statistically significant 4.8 fold increase in myocardial infarction within the first hour of marijuana use. In fact, as THC content of marijuana increases, there are a growing number of clinical studies demonstrating the association between cannabis use and adverse cardiovascular events. One such study followed 1913 adults prospectively and demonstrated that in patients with prior myocardial infarction, marijuana use up to once per week increased risk of death 2.5 fold while more frequent use yielded a fourfold risk of dying.