Cannabis Grow

Although selection and/or identification of allelopathic plants from medicinals plants are much easier than other group of plants, isolation and identification of strong allelopathic substance is laborious, time consuming and need very sophisticated equipment’s. Hence, to date very few works have been conducted to isolate and characterize the allelopathic substances from allelopathic medicinal plants. A list of allelopathic substances isolated from different medicinal plants is given in Table 2. These substances showed strong phytotoxic potential against different target plant species under laboratory condition. However, their phytotoxic potential under field condition not yet reported. It is well known that even a substance showing strong phytotoxic activity on target plants in laboratory experiments, may not perform satisfactorily in the field conditions due to the influence of several soil factors like soil pH, organic carbon, organic matter and available nitrogen. Therefore, more emphasis should be given on evaluating the bio-activity of allelopathic substances or the allelopathic plant extracts in both laboratory and field condition.

If the extracts or the isolated compound shows strong activity in both conditions only then it could be recommend for new natural herbicide development. is a recently registered sulfonylurea herbicide for broad leaved weed control in white bean in Ontario . Therefore,cannabis grow equipment halosulfuron needs to be used along with a graminicide to provide broad spectrum control of problematic weeds in white bean.S-metolachloris a chloroacetanilide herbicide that is registered in white bean to control of key weeds in Ontario including Echinochloa spp., Setaria spp., Panicum spp., Digitaria spp., Solanum spp.and Amaranthus spp. .S-metolachlor tank mixed with halosulfuron cancontrol troublesome grass and broad leaved weeds in white bean.The S-metolachlor label has a dose range of 1050 to 1600 g∙ai∙ha−1 and the halosulfuron label has a dose range of 25 to 50 g∙ai∙ha−1. Earlier research has primarily focused on halosulfuron at 35 g∙ai∙ha−1 for weed control in white bean. Limited information exists on the effect of Smetolachlor plus lower doses of halosulfuron particularly at the lowest labelled dose of 25 g∙ai∙ha−1 for weed control in white bean.

Studies are needed to determine the appropriate application dose of halosulfuron alone or in tank mix with S-metolachlor for broad and comprehensive weed control in white bean. This information will allow producers to reduce their input costs and minimize crop losses from weed interference in white bean.The purpose of this research was to evaluate how doses of S-metolachlor and halosulfuron should be adjusted to control specific problematic weeds in white bean production.Agricultural practices have caused major changes in the composition and species richness of weed communities in the field.Arable weed species play an important role in supporting biological diversity in agro- ecosystems . Weed species that thrive in the field edges and may colonize cropped plots include Avena sterilis and Galium aparine , Conyza canadensisand Senecio vulgaris . In other studies, plant populations in field edges have not resulted in weed infestations in the adjacent crop in many studies.There is evidence that herbicide efficacy, increased crop competition and changes in cropping patterns have resulted in a gradual decline in weed abundance and diversity over recent decades.Herbicide use is a widespread practice detrimental to weeds and continued use of a single herbicide often results in weed composition shifts from highly susceptible species to those having greater tolerance to the herbicide . The most used herbicide in arable crops in Argentina is glyphosate which provides application flexibility, lacks of rotational restrictions and controls a broad spectrum of weeds.However, as a result of repeated use, species difficult to control with glyphosate have become more common in many countries and in Argentina as well.

Weed diversity may be concentrated in the crop edges, especially in the weed communities of conventional cereal fields . In Argentina, crop edges are narrow areas that are taken out from agriculture. In crop edges, insecticides, fungicides are not used and occasionaly, herbicides are applied. In the field plot, the most used herbicide is glyphosate-alone or in combination with residual herbicides . The objective of this study was to analyze weed abundance and diversity as well as the frequency of weeds tolerant or resistant to glyphosate in field plots and edges in the soybean central region of Argentina. Overall, MRPP indicated variations in species composition between edges and field crops. Two weed communities were identified according to season: Spring-summer and winter.Variations in weed species composition between seasons were also observed in another study .

World’s rice demand is projected to increase by 50% from 1997 to 2050 to keep pace with population growth .Compared to other field crops, rice is most widely grown under irrigated condition which accounts for about 50% of the total amount of water diverted for irrigation, which in itself accounts for 80% of the amount of fresh water diverted. This is due to the high unproductive water losses by evaporation, surface run-off, and percolation. Producing one kilogram of unprocessed rice grain under irrigation is estimated to use between 1500 and 5000 L of water, depending on the local climate, soil type and rice variety . This amount is about twice or even more than wheat or maize. However, declining water availability threatens the sustainability of traditional flood-irrigated rice ecosystems . In Asia, it is predicted that 17 million hectares of irrigated rice areas may have “physical water scarcity” and 22 million hectares areas may be subject to “economic water scarcity” by 2025 .

In Asia, where about 60% of the world’s population lives, food security is challenged by increasing food demand and threatened by declining water availability.It is, therefore, no longer feasible to flood rice fields for better crop establishment and weed control . Among different water-saving approaches, aerobic rice cultivation has come up with a huge success in different parts of the world.Growing rice in non-saturated and non-puddled aerobic soil is a promising water-wise technique of rice cultivation under the context of ever-mounting water scarcity. Growing rice under aerobic conditions requires 36% 41%less water than under the conventional method . In response to the labour and water shortage problem, cannabis drying racks some alternative rice production methods were suggested by researchers worldwide including alternate wetting and drying , system of rice intensification, and raised bed for saturated soil culture. Compared with flooded rice, aerobic rice had lower production cost, higher water productivity, and a comparable outcome.Weeds are a major yield limiting factor in rice production,and the literature reporting yield losses is numerous. Globally, actual rice yield losses due to pests have been estimated at 40%, of which weeds have the highest loss potential.

The worldwide estimated rice yield loss due to weeds is around 10%of the total production . Yield reduction due to weeds is more critical in direct seeded rice than in transplanted rice. In dry seeded aerobic rice,relative yield loss caused by weeds is 50% 91% , while in transplanted rice,yield loss has been estimated to be only 13% . Among the rice ecosystems,yield losses are the highest in aerobic rice . In extreme cases, weed infestation may cause complete failure of aerobic rice . Weeds persist by adapting to cultural practices, and every cultural practice influences the competitive ability of both the crop and weed resulting complex interactions.Cultural approaches play significant role to determine the competitiveness of a crop with weeds for above ground and below ground resources and hence might influence weed management . Integrated weed management strategies offer several options, but risks of developing resistant weed biotypes ,and environmental hazard resulting from herbicides from chemical control , and labor-intensive manual weeding methods demand aneco-friendly and less labor-dependent weed management system for sustainable aerobic rice production.As observed by many researchers, the performance of herbicides can be enhanced if crop varieties with higher weed competitiveness are used especially in herbicide-dominant systems.

Weed competitiveness comprises two components:weed suppressive ability—the ability to lessen weed growth through competition, and weed tolerance—the capability of maintaining potential yields in the presence of weeds . The potentiality of using weed competitive variety in integrated weed management has been documented in many crops including rice. The deployment of weed competitive variety is not only eco-friendly but also a very cost effective tool for integrated weed management. Considering the high vulnerability of aerobic rice to weeds, development of weed competitive aerobic rice variety has been suggested by many researchers .No work has so far been done to assess the ability of the huge pool of Bangladeshi rice germplasms to wrestle weeds under aerobic soil conditions. In this backdrop, the present study was undertaken to study the variation in weed competitiveness among selected high yielding rice varieties and to recognize agronomic traits conferring weed competitiveness of rice grown under aerobicsoil conditions.

Owing to their ability to self-renew and differentiate, CSCs are capable of regenerating the heterogeneous tumor population  after hormone ablation, which accounts for tumor relapse. Therefore, elimination of the bulk of frequently replicating tumor cells as well as the rare subset of slow, dividing stem-like cells that are responsible for tumor regeneration may represent a better therapeutic strategy in the treatment of prostate cancer. The therapeutic properties of the hemp plant, Cannabis sativa, have been known for many years, but the recreational use of its psychoactive effects has restricted its possible pharmaceutical application. In recent years cannabinoids and their derivatives have drawn renewed attention because of their diverse pharmacologic activities such as cell growth inhibition, anti-inflammatory effects, and tumor regression.

Cannabinoids have been shown to induce apoptosis in gliomas , PC-12 pheochromocytoma , CHP100 neuroblastoma , and hippocampal neurons  in vitro, and most interestingly, regression of C6-cell gliomas in vivo . Plant-derived cannabinoids, especially cannabidiol, are shown to be potent inhibitors of prostate carcinoma both in vitro and in vivo.Our case studies confirmed cannabinoid  efficacy in reducing muscle spasticity in multiple sclerosis , pain levels over a 12-month period  and Cannabis responsive head injury induced multiple disabilities . To date, cannabinoids have been successfully used in the treatment of nausea and vomiting , two common side effects that accompany chemotherapy in cancer patients. Nevertheless, the use of cannabinoids in oncology might be somehow underestimated since increasing evidence exist that plant, synthetic, and endogenous cannabinoids  are able to exert a growth inhibitory action on various cancer cell types. However, mobile vertical rack the precise pathways through which these molecules produce an antitumor effect has not been yet fully characterized, also because their mechanism of action appears to be dependent on the type of tumor cell under study.

It has been reported that cannabinoids can act through different cellular mechanisms, e.g., by inducing apoptosis, cell-cycle arrest, or cell growth inhibition, but also by targeting angiogenesis and cell migration  . Furthermore, the antitumor effects of plant, synthetic and endo-cannabinoids can be mediated by activation of either CB1  or CB2 receptors or both  . After the discovery of the two specific molecular targets for THC, CB1, and CB2 , it became clear that most of the effects of marijuana in the brain and peripheral tissues were due to activation of these two G-protein-coupled cannabinoid receptors. However, evidence is also accumulating that some pharmacological effects of marijuana are due to Cannabis components different from Tetrahydro-cannabinol. Indeed, C. sativa contains at least 400 chemical components, of which 66 have been identified to belong to the class of the cannabinoids . The main limitation of the possible future use of THC in oncology might be represented by adverse effects principally at the level of the central nervous system, consisting mostly of perceptual abnormalities, occasionally hallucinations . However, most non-THC plant cannabinoids seem to be devoid of direct psychotropic properties. In particular, it has been ascertained that cannabidiol is nonpsychotropic   and may even mitigate THC psychoactivity by blocking its conversion to the more psychoactive 11-hydroxy-THC .

Moreover, it has been recently found that systematic variations in its constituents  do not affect the behavioral or neurophysiological responses to marijuana . Finally, it has been also shown that, unlike THC, systemic administration to rats of cannabigerol does not provoke poly-spike discharges in the cortical electroencephalogram during wakefulness and behavioral depression . These and other observations reinforce the concept that at least cannabidiol, cannabigerol, and cannabichromene lack psychotropic activity and indicate that for a promising medical profile in cancer therapy, research should focus on these compounds, which so far have been poorly studied with regard to their potential antitumor effects. By keeping this goal in mind, we decided to investigate the antitumor properties of plant cannabis. We screened two distinct chemically characterized Cannabis extracts , where the presence of nonpsychotropic cannabinoids along with THC has been reported to mitigate the potential side effects of the latter compound in clinical trials . Despite research efforts, little is known about the prostatic cancer stem cells which were suggested to play an important role in tumor initiation, progression, and chemoresistance . Because CSCs are believed to contribute to chemoresistance, we reasoned that the chemosensitizing effect of cannabis may be mediated through targeting of prostate CSCs.

Various sentinel studies in the country reported that the prevalence of alcohol and other substance use among students’ population was high. Nevadomsky, in a study of drug use among secondary students in southern Nigeria, reported a prevalence of alcohol use to be 65%, tobacco 24% . The author reported that use of benzodiazepines, cannabis and amphetamines among the subjects were less common. Vázquel, in a study of prevalence of psychoactive substance use and dependence among Spanish university students, reported that 86.5% had consumed psychoactive substances, and 10.5% satisfied DSM IV criteria for dependence on nicotine, alcohol, caffeine or cannabis . Mason et al., in a study of substance use, social networks, and the geography of urban adolescents in Washington, USA, reported a prevalence of psychoactive substance use among the respondents as 65% .

The au thors reported that most popular psychoactive substances used were alcohol, cannabis and cocaine. Tobacco was not measured in the study as a primary psychoactive substance as some participants  can legally use it. Centre for Disease Control and Prevention , cannabis grow system reported a high prevalence of cannabis use  among teenagers aged 16 to 19 years . Substance Abuse and Mental Health Services Administration , reported a high prevalence of cannabis use  among young adults aged 18 to 25 years . In Tanzania, Kalula, in a qualitative study of cannabis use among young people, reported an increasing trend of cannabis use among youths aged 15 to 25 years with a prevalence rate of 5% . Adebiyi et al., in a study of tobacco use among out of school adolescents aged 10 to 19 years in Ibadan, Southwestern Nigeria, reported a prevalence of tobacco use as 20.5% . However, the study was limited to tobacco use. Information on the use of psychoactive substances among motorcyclists in Nigeria and more specifically in Northern Nigeria is limited. The current study aims to determine the socio-demographic characteristics of psychoactive substance users among commercial motorcycle operators in a selected local council Area in Kano, Nigeria.

We hypothesized that the socio-demographic characteristics of psychoactive substance users among commercial operators in Kano will be similar to what is found in other parts of Nigeria and the world. In this study, the younger age groups were found to be more likely to use psychoactive substances compared to those who were older than 35 years. This is in agreement with other studies done among commercial motorcyclists in Zaria, north western Nigeria and Nnewi, south eastern Nigeria. However, it differs from a study in southwestern Nigeria among refugees from Liberia, where respondents in the age group used psychoactive substances more than the younger age group of 18 to 30 years . The socio-cultural differences between Nigeria and Liberia may explain the observed difference. All the participants in this study were males because only males operate commercial motorcycles in Kano state. Studies have shown that males are more likely to abuse drugs compared to females. All the respondents were Moslems, which is the predominant religion in Kano state. Majority of the respondents participated regularly in their religious activities, which may partly account for the low prevalence of psychoactive substance use in them. This is consistent with the findings of similar studies in Ilorin and Abeokuta where significant association was found between substance use and religiosity, with those who were very religious being less likely to use psychoactive substances.

More than 88% of the respondents were married, and more than 60% had between one and 5 children, in keeping with the study in Ilorin among long distance drivers with more than 95% of the subjects married with children . It would seem that marriage had a moderating effect on substance use by the respondents, as use of cannabis, stimulants, inhalants and opiates was more among the respondents who were single. This is line with a study among 62 patients who use/abuse psychoactive substances, at the drug abuse unit of the Federal Neuropsychiatric Hospital, Aro, Abeokuta, where it was observed that the patients were mostly single . This finding also corroborates a study by Ansari-Moghaddam et al. in Iran which found that singles were twice more likely to use substances compared to those who were married . Most of the participants in this study had some form of education, up to secondary school, which is consistent with the study in Ilorin and Zaria where more than 68% had some form of education ranging from primary to tertiary education.

In the Southeastern US, alfalfa is increasingly grown as a companion crop inbermuda grass pastures. It offers producers a significant profit potential through selling hay, or by grazing or conserving the surplus as haylage. Most of these growers were attracted to alfalfa because they have seen enormous improvement in the quality of their hay, and they were able to save on the application of nitrogen fertilizer. Studies evaluating the sustainability of production of alfalfa inter seeded in Bermuda grass showed that alfalfa competes well with Bermuda grass,even in drought conditions . Another part of the forage system in the region is cereal rye that is grown for late fall and early winter grazing when Bermuda grass goes dormant. The allelopathic effect of rye has been recognized since the early 1980’s, and a number of studies have illustrated the extent and severity of rye allelopathy over other species .

Rye reduced the density and biomass of weed species such as red root pig weed and common lambs quarters,mobile vertical rack when used as cover crop mulch in soybean, and enhanced soybean yield .Utilization of winter rye cover crop reduced corn biomass yield by 10% to 15%and the effect was more severe under no-till system . The role of cereal rye to suppress weeds was described extensively. To control weeds in other crops, rye can be utilized as cover or mulch. However, to control weeds, highly allelopathic rye cultivars are required . The influence of rye residue on germination of different plant species such as lettuce , proso millet, and corn was described . Barnes and Putnam reported the effect of two phytotoxic compounds from rye:on germination of various dicots and monocots such as, lettuce , tomato ,barnyard grass , cressetc.. Another phytotoxic compound extracted from rye is hydroxamic acid, which is exuded from plant roots and can reduce weed biomass by up to80% compared to other cover crops . Further, the Hx released from rye also inhibits the growth of other species such as Avena fatua .

The term “allele pathy” refers mostly to detrimental interactions between plant species, and is triggered by allele chemicals produced by one of the plants . In addition to producing allele chemicals, allelopathic crops and their residues also produce microbial toxins at the time of decomposition, which jointly create aphytotoxic environment . Allelo chemicals are released from plant roots,leaves, and stems and affect other crops within the same area . Allelopathy has been exploited for controlling weeds either by growing allelopathic crops prior to planting main crops or by isolating and applying the active natural compounds from the allelopathic crop as natural herbicides. Crops such as rice , wheat , barley , oat , cereal rye , soybeanetc. have been recognized for their allelopathic activities . Similarly, allelopathy of some legumes such as black gram, mung bean etc. have also been reported . Allelo pathy has been used to manage weeds and is considered as natural herbicides that are safer to the environment compared to synthetic herbicides . For instance, phytotoxic products from sorghum and Sudan grass hybrids were effective in suppressing alfalfa, Johnson grass, annual ryegrass , common lambs quarters and large crabgrass .

Similarly,rice hull incorporated alfalfa-rice-byproducts were reported as very effective allelopathic materials to inhibit weed emergence in paddy fields . Alfalfa pellets were effective in suppressing the emergence of Eleo-charis acicularis and Rotalaindica when applied at the dose of three tons ha−1. Additionally, alfal fade composed roots acted as allele pathic agents on blady grass and reduced seed germination by 50% . Alfalfa is also recognized forits own auto toxicity and researchers have recommended not planting alfalfa seed in an established alfalfa stand .In recent years, scientists have acknowledged allele pathy as a biotechnological tool to manage weeds targeting either the transfer of allelopathic genes from donor plants to the crop of interest through breeding or genetic engineering, or by enhancing the crop itself to produce phytotoxins via cell cultures . In rice,scientists have explored the variability in allelopathy among different cultivars and identified quantitative trait loci associated with rice allelopathy .

Safflower seedlings remain in the rosette stage for 3 to 4 weeks after emergence and the canopy closure occurs late in the season; hence, early-emerging weeds species can easily outgrow and shade the crop . Trifluralin, EPTC, ethalfluralin, and S-metolachlor are the preemergence /preplant incorporated herbicides labeled for use in safflower. Trifluralin was the first herbicide labeled for use in safflower . It is effective on some annual grasses, but does not adequately control Brassica species,kochia, and Russian-thistle. These weed species are particularly troublesome in safflower production areas of this region, including Montana .Furthermore, the need for soil-incorporation of trifluralin, ethalfluranlin, andEPTC for optimum weed control often limits their use in no-tillage semi-arid cropping systems of this region. Smetolachlor applied PRE controls annual grasses and few broadleaf weeds such as pigweeds .During 1980s, sulfonylurea herbicides such as chlorsulfuron, metsulfuron,and thiameturon were tested, particularly for post emergence broadleaf weed control, in safflower.

Previous studies found that safflower exhibits variable tolerance to these SU herbicides, and moderate to severe injury may occur if applied to safflower plants less than 15-cm tall.This is a major limitation in using these SU herbicides for early-season POST weed control, cannabis grow tray especially for weeds such as kochia and Russian-thistle, which can emerge very early in the spring before or with safflower seedlings in the US Great Plains. Thifensulfuron is the only POST herbicide currently labeled for broad leaf weed control in safflower in the US . However, the widespread occurrence of ALS-resistant kochia and Russian-thistle in Montana and several other states in the US Great Plain srenders thifensulfuron in effective for controlling these weed biotypes in safflower.Therefore, there is a need to investigate alternative herbicide programs for improved broadleaf weed control in safflower, especially kochia and Russian-thistle, and to facilitate registration of new products for use in safflower.The objective of this research was to investigate effective PRE soil-residual herbicide programs for improved crop safety and season-long broad leaf weed control in safflower.

All data were subjected to ANOVA using the MIXED procedure in SAS 9.3 . Data on crop injury and weed control were arcsine-transformed and weed density data were square-root-transformed before analysis to improve homogeneity of variances and normality of residuals. Non transformed means are presented in tables based on the interpretations from the transformed data. Year, herbicide treatment, and their interactions were fixed effects, and replication and interactions involving this variable were random effects in the model. Data were pooled across locations whenever year by herbicide treatment interaction was not significant. Means were separated using Fisher’s protected LSD test at P < 0.05. The 2016 growing season was slightly wetter compared to the 2015 growing season. However, the treatment by year interaction was not significant on safflower visual injury, weed density, percent weed control, or safflower grain yield; therefore, data were pooled over years. Organic rice has started to gain popularity as the safer and healthier alternative,especially in developed countries .

Demand for organic rice is increasing with up to 50,000 acres produced in the USA . In US, organic rice farmland has increased almost six times since 1995 to now . However, current organic rice production in US is unable to meet the current market demand. Organic rice buyers in the US are importing large percentages of their rice from Cambodia.Major challenges in organic rice production include nutrient optimization,weed management and variety selection . Weed competition is one of the prime yield limiting biotic constraints in rice . Uncontrolled weed can reduce rice yield by 44% to 94% . Weeds even can cause total crop failure .Through selection of weed competitive cultivars, the weed emergence and its subsequent growth can be suppressed . Thus, varietal selection can be alternative to weed management in organic rice. Likewise, flooding and cover cropping are tools in integrated weed management for organic rice production.

Epidemiological evidence has linked lung disease, increased respiratory and cardiovascular symptoms, chronic bronchitis and chronic obstructive disease and emphysema to marijuana smoking.In some instances,marijuana use can cause alteration and sometimes loss in memory characterized by slowed reaction time,hampered information processing, un-coordinated motorre actions and performance, and attention deficiency that result in mood disorder syndrome, psychosis and schizophrenia . Accordingly, a review on the effects of marijuana smoking on the lungs found out that prolonged cannabis smoking leads to lung cancer and cancers of the upper aero digestive tract . Moreover,a brief exposure to second hand marijuana smoke leads to acute vascular endothelial dysfunction.Nonetheless, lack of sober mental control due to the detrimental effects of marijuana among intoxicated drivers has been reported to increase the risk of road accident.

The occurrence of these events is hypothesized by the fact that when one smokes marijuana joint, he/she is four times exposed to carbon monoxide and five times more tar deposition than a single tobacco cigarette due to more deep inhalation and longer holding breath times and lack of cannabis cigarette filters . Consequently, psychiatric disorders among marijuana smokers have been associated with acute and chronic smoking . As a result, young cannabis users are likely to experience a deficiency in mental performance characterized by slowness in information processing, amnesia and deprived attention which adversely affects their learning faculties. In addition, pregnant women who get exposed to cannabis are more likely to experience weakened visualization and dexterity, and may give birth to children that are prone to abnormal behaviors .Once the presence of cannabis is detected in the human central nervous system, it excites the production of dopamine and endogenous opioids which inhibits the secretion of acetylcholine responsible for pharmacological changes in the brain leading to a decrease of glutamatergic synaptic transmission which causes brain functioning abnormalities among the cannabis smoking communities.

The endocannabinoid system receptors, cannabinoid receptor type 1 and cannabinoid receptor type 2 offer inhibitory function, whereCB1 receptor act on the production of cyclic adenosine monophosphate pathway once they receive a signal from adenyl cyclase inhibitor activation while CB2 receptor plays an important role in blocking inflammatory activity and tissue damage. Therefore, brain structural abnormality has been observed in chronic cannabis smokers with more effects imposed on the grey and white matter density. Moreover, variable brain activity among cannabis consumers has been reported and compared to non-smokers in which greater brain activation is observed in the prefrontal region of smokers while hypo-activation is noted along the left superior parietal cortex due to high concentrations of the two cannabinoids, THC and CBD, THC alters the hippo campal capacity and neurochemistry while on the other hand, CBD defends against toxic variations .Nonetheless, cerebral stroke, one of the leading causes of death has been associated with cannabis intake according to a number of preclinical studies and scientific case reports.

Scientifically, neurological stroke and Alzheimer’s disease solely result from exposure to reactive oxygen species such as peroxynitrite,hydrogen peroxide, epoxides etc. and oxidative stress pathways that cause tissue and cellular damage, conditions which are largely promoted by cannabis smoking.Accordingly, THC is a potential agent of oxidative stress and a threat in the initiation of ischemic stroke.Pharmacological and toxicological properties of cannabis are contributed by eighteen classes of chemicals which include hydrocarbons, sugars, simple fatty acids, terpenes, amino acids, and nitrogenous compounds. Accordingly, cannabis has been used for treating oncology patients, epileptic patients ,and management of inflammatory bowel disease , neurological and psychiatric disorders , and sometimes in children to treat autism spectrum disorder, fetal alcohol spectrum disorder and in pregnant mothers in the management of hyperemis gravidarum.This has been attributed to the non-psychoactive cannabinoid CBD which interacts with the CB2 receptor that gets activated to reduce pain, seizures and inflammations in patients, and sometimes in the management of epilepsy, schizophrenia and post-traumatic stress disorders . Evidently,therapeutic capacity of THC against chronic pain and sclerosis neurologicalailments has also been documented .

Amorphous cellulose and hemicellulose are mostly responsible for the high water uptake of natural fibers, since they contain numerous easily accessible hydroxyl groups which give a high level of hydrophilic character to fibers.Although UV light makes up only about 5% of sunlight, it is responsible for most of the sunlight damage to the materials, especially polymers, exposed outdoors. This is because photochemical effectiveness of light increases with decreasing wavelength. This rupture causes changes in molecular weight, formation of cross-links, and reaction with oxygen. These structural changes lead to gross physical changes such as chalking, cracking, surface embrittlement,discolouring and loss of tensile and impact strength .In one study on the effect of weathering on polyester resin, the resin was exposed to actinic rays in a twin arcfadeometer . An exposure of 400 – 700 hours was considered equivalent to one year of outdoor exposure.

Initially there was no visible change after several hundred hours of exposure. Then the yellowing of the samples suddenly became noticeable. The tensile strength of the resin deteriorated from 66 MPa to 47 MPa after 2400 hours of exposure. Similarly the flexural strength deteriorated from 90 MPa to 82 MPa after same exposure period.To simulate the physical damage caused by sunlight it is not necessary to reproduce the entire spectrum of sunlight. In many cases it is only necessary to simulate the short wavelength. To overcome the problem of UV light, ultraviolet absorbers, such as carbon black or aromatic ketones, are added to polymers.The amount of moisture absorbed by the polymer matrix composite depends on the matrix type, exposure time, component geometry, relative humidity, temperature, and exposure conditions. Typical consequences of exposure of composite materials to these environments are: plasticisation of matrix, resulting in reduction in glass transition temperature and usable range, changes in dimensions and fibre/matrix debonding due to matrixand fibre swelling, enhanced creep and stress relaxation, resulting in increased ductility, change in coefficient of expansion, reduction in ultimate strength and stiffness, matrix cracking, and chain scission .

In case of natural fibre reinforced composites, additional problems are encountered because of hydrophilic nature of natural fibres. The moisture content of natural fibres can vary between 5% and 10%. This can lead to dimensional variations in composites and also affects mechanical properties of composites. It can cause fibres to swell and ultimately rot through attack by fungi. A possible solution is to improve fibre-matrix interface by using compatibilizers and adhesion promoters. With better adhesion, the moisture sensitivity is usually reduced .Also surface treatments of fibres with silanes can make the fibres more hydrophobic.The study of weathering properties of natural fibre composites is a new and growing field. The use of accelerated weathering testing is a preferred method for this purpose whereby the outdoor exposure conditions are simulated in laboratory in controlled atmosphere and in accelerated conditions which can reproduce the damage to the material in few days or weeks that actually occurs over months or years of outdoor exposure.A number of studies have recently been carried out which have examined the effects of accelerated weathering on the properties of natural fibre composites. Generally, all types of natural fibre composites show fading of colour and reduction in mechanical properties following exposure to natural and accelerated weathering conditions.

The use of coupling agents, fibre surface treatments, ultraviolet absorbers and pigments to improve the weathering resistance has been reported to have positive effects on composites. The effect of UV radiation only and UV radiation plus condensation on weight of these composites is shown in Figure 3. It was observed that the composites started to lose weight soon after exposure to these conditions. The increase in weight loss for UV exposed composites was greater than for UV plus condensation exposed composites. Whereas UV exposed composites lost nearly 3.2% of their original weight following 250 hours of exposure,UV plus condensation exposed composites lost only about 0.2% of their original weight following same exposure time. It has been shown that when unsaturated polyester resins are heated, the polymer chain begins to dissociate chemically and that polyesters have maximum photochemical sensitivity at wavelength of 325 nm. Since the UV radiation used in this study had a wavelength of 340 nm, it is expected that this resulted indegradation of the upper polyester layer of the composites resulting in loss of weight. This degradation is a manifestation of chain scission and breaking of bonds between polymer molecules following exposure to UV radiation.However following increased exposure times, as the UV radiation interacted with the hemp fibres, the fibres offered more resistance to UV radiation.

The increasing environmental awareness, growing global waste problems and continuously rising high crude oil prices have motivated governments all over the world to increase the legislative pressure. This in turn promotes researchers, industries and farmers to develop the concepts of environmental sustainability and reconsider renewable resources. Renewable resources from agricultural or forestry products form a basis for new industrial products or alternative energy sources, such as hemp fibre. Hemp fibres have long been valued for their high strength and long fibre length, and used extensively in the fabrication of ropes and sails, as well as for paper and textiles. Hemp fibres consist of different hierarchical microstructures, whereby microfibrils serve as basic units.

The microfibrils are embedded in a matrix of hemicelluloses and form the different cell wall layers of an elementary fibre, which generally has a large average diameter ranging from 10 to 50 m.The elementary fibres are bonded together with pectin’s and small amounts of lignin framing the next level of microstructure, i.e. technical fibres, with a diameters ranging from 50 to 100 m . These filaments are fixed together with a pectin-lignin matrix to form fibre bundles in the cortex of plant stems. Thus, bast fibres are bundles of individual strands of fibres held to-gether by a pectin-lignin interface. The fibres of never dried hemp contain numerous de-formations. All these deformations appear where there is a change in microfibril direction and a distorsion of the fibrils. The deformations can be seen under polarized light, but the largest of them also could be dis-cerned without polarisers.

The deformation of fibres can affect the strain distribution in elementary fibre, leading to localized strain concentrations , and hence reduce both compressive strength and tensile strength , which was also proved by a finite element modeling of the tensile behaviour of single flax and hemp fibre. The fibres in the matrix may break at the point with deformations , and the concentration of stresses around the deformation could act as the site of initiation of fibre-matrix debonding as well as for the formation of micro-cracks in the matrix which contribute to global fracture of composite. Limited work conducted on the breaking behaviour of wood pulp, cotton , and flaxalso indicated that the break behaviour of the primary and secondary cell wall of the flax fibres was different from that of wood and cotton . The primary cell wall generally breaks in a brittle manner, whereas the secondary cell wall, bridged by fibrils, splits relatively easily along the length direction. The experience has highlighted that it is not possible to use or appropriate to compare data available from different investigations reported in the literatures.

Microstructural defects, fibre abstraction and processing are all yet to be studied. This pa-per is an attempt to characterize the surface and reveal the failure mechanism of elementary hemp fibres. Systematic and improved methodologies and advanced technologies have been developed to investigate the microfibril angles of elementary hemp fibres and the crystallinity of hemp fibres. The surface of hemp fibres after tensile loading and fracture of fibres after breaking were also observed carefully to characterize the surface and reveal the failure mechanism of elementary hemp fibres. This paper is the first of a series of papers from an intensive research programme aiming at a better understanding of natural fibre resources and the develop-ment of their high strength composites for applications in various industrial sectors. The purpose of this article is two-fold. First, we advocate the use of mathematical models to characterize the learning process for researchers interested in exploring the effects of marijuana on learning and memory. While articles contain the results of statistical tests, to our knowledge no previous article has promoted the use of mathematical models to characterize potential learning and memory effects either on marijuana or other plant based products purporting to improve memory.

Mathematical models have much to recommend them for the study of marijuana and other plant based products. Such models can easily summarize large amounts of data, direct research, stimulate the development of theory, and guide therapeutic intervention. They can also be used to test claims made by advocates of plant based products that such products improve learning and memory.Second, we advocate the use of the first order system transfer function. We have used this model in a wide variety of studies ranging from the assessment of memory in drug addicts and alcoholics to the detection of memory impairment in individuals suffering from either Type-2 diabetes mellitus or multiples clerosis. The model has also been applied to both the child and adult versions of the California Verbal Learning Test .

Other frontal areas and regions of the parietal lobe, as well as subcortical areas are also affected by marijuana exposure. Moreover, the three circuits involved in response inhibition,namely the frontal-striatal thalamic circuit, the cingulo-opercular circuit and frontal-parietal circuit, are all still under development during adolescence.Therefore,the overactive brain regions observed in this investigation may be due not only to the current marijuana use but also to the relatively long term marijuana exposure during those crucial years in adolescence.The strength of this study was the ability to control foran unparalleled number of lifestyle variables including IQ, current nicotine and alcohol use and prenatal marijuana,nicotine, and alcohol exposure. The well controlled sample strengthens the validity of the results and provides outcomes that are able to shed light on more exclusive contributions of marijuana on the response inhibition network than previous studies.

The limitations of the study include that the sample was small and a primarily Caucasian, middle-class population.Thus, these results cannot be generalized to other ethnic or socioeconomic status populations. However,this is a low risk population and these effects are significant, suggesting that a high risk population would be even more likely to show a negative impact of marijuana use given the other risk factors.The present study also used a block design rather than an event related design. Thus, an event-related study may have helped to separate response inhibition from other cognitive processes. It is also difficult to ever truly remove a drug’s effect from a BOLD study and thus it must be considered that current use of nicotine impacted the result seven after using it as a covariate. Similarly, there was no measure of alcohol consumption on the day of testing other than the self-report of each participant. Although the self-report and urine sample values were highly correlated for those drugs tested in the urine, this was an oversight for the alcohol consumption and should be rectified with the addition of a breath alcohol level assessment in future research.

Finally, there was no abstinence period for the participants of either group. However,careful statistical analyses were performed including and not including those participants who smoked marijuana on the day of testing. Even though these analyses had less power than the reported results, the same positive relationship between amount of marijuana smoked and neural activity was observed. This suggests that the reported results are indicative of the regular marijuana use and not only acute marijuana effects. Future research will test participants who have stopped using marijuana for at least 6 months.In conclusion, adolescent use of marijuana can have detrimental effects on the brain that can be observed in young adulthood. The findings in this study suggest that increase in neural activation with increased marijuana use may be due to a form of neural compensation or an altered neural development, or both. Also, this may occur not only in the prefrontal cortex but also in the extensive neural network required for inhibitory control, a cognitive process important for executive functioning and thus success in establishing and reaching appropriate goals during adulthood.

The valorization of plant biomass through the use of ligneous resources for the design and production of composite structures is a current issue in the research sector and applications in automotive, construction, goods and leisure industries are more and more observable. This visibility is demonstrated by the manufacturing of equipments such as: prostheses, tennis rackets, turbine blades, vehicle doors, shutters and roofs, etc.. Moreover, the use of products obtained from these materials is in line with the Kyoto Protocol’s requirements for sustainable development and environmental protection . Thus, the rush to substitute synthetic fibers with natural fibers in composite structures is justified.Apart from their eco-friendly aspect, biofibers stand out for remarkable specific mechanical properties and relatively low cost. However, their qualities depend on the quality of the fabrication. The choice of the manufacturing process of an ecological composite requires the knowledge of some fundamental elements. Thermal behaviours such as the maximum degradation temperature and the thermal stability range of the fiber are indispensable. Physical characteristic slike porosity, density and water absorption capacity have to be specified.In addition to these parameters,crystallinity rate and chemical composition of the fibre will be an undeniable asset.The natural fibers characteristics depend on a number of factors like the age of the plant from which the fibers are extracted, the part of the plant where the fibers are located and the fibers extraction technique used .The plant fibers most widely used as reinforcement for composite materials a reflax, sisal, hemp, jute and kenaf .