The gradient from green to red clearly shows a gradient of Portlandite concentration from the least concentrated in the ITZ to the most concentrated in the matrix.This clearly demonstrates the low hydration of the ITZ compared to the rest of the cement matrix.This type of observation helps define the ITZ and will allow researchers,in future studies,to compare the effect of different binders or fibers on the ITZ from a chemical point of view.Note that the blue part of the map corresponds to a problem of planarity of the sample – thus,the apparatus was unable to focus in this area,making the spectra of this zone invalid.This problem is due to the sample holder blocking the sample without the possibility of adjustment,and could be corrected in future studies by using a sample holder with an accurate adjustment.The semi-quantitative analysis on both the ITZ and the hydrated matrix through XRD analysis for a W/C = 0.5 sample  shows a drastic difference in the relative quantities of Portlandite and C3S that are characteristic of the hydrated and anhydrous phases respectively.DTA and TGA corroborates this analysis,since the hydrated matrix displays a significant endothermic reaction around 125 ◦C and a huge mass loss between 30 and 200 ◦C,corresponding to C–S–H dehydroxylation.Another mass loss occurs between 400 and 600 ◦C,coupled with a second endothermic reaction around 489 ◦C on the heat flow,that corresponds to the degradation of portlanditeCalculate the fitness function value again,update the best individual,and repeat until the evolutionary generation is reached.The best individual is the optimal parameter learned.To describe the sound absorption properties of the hemp plastic composites,eight specimens of different thickness,diameters were prepared.So,eight different specimens were prepared with four different thicknesses,two diameters.Table 2 shows the features of the specimens.Figure 6 shows the values of the sound absorption coefficient measured as a function of frequency.The Specimen ID is as shown in Table 2.The values of the absorption co-efficients are reported in the frequency range from 200 Hz to 4000 Hz,among them,the specimens with diameter of 50 mm are measured below 2000 Hz,the specimens with diameter of 100 mm are measured between 2000 Hz and 4000 Hz.We can see that the values of sound absorption co-efficient in the low frequency band is relatively smaller,as the frequency increases,the value increases.At about 830 Hz,the value is the largest,then decreases,and gradually increases at 1250 Hz until it approaches the maximum value.Moreover,we can see the greater thickness or diameter have a larger value of sound absorption co-efficient,almost at the maximum value.If we analyze the curve relating to the thickness of 10 mm,the diameter of 100 mm of specimens N4,N8,it can be found that the values of sound absorption co-efficient are largest among all curves,which are between 0.9 and 1.The analysis shows that the absorption of high frequency sound waves is mainly on the surface of the material,and the absorption of low frequency sound waves is inside the material.Therefore,trimming trays increasing the thickness of the material will increase the low frequency impedance,so enhance the absorption of sound waves.When the material thickness reaches a certain value,the absorption of intermediate and low frequency sound waves can be increased,but the absorption of high frequency sound waves is not obvious.

To simulate the absorption properties of the porous hemp plastic composites,the proposed model is implemented.Here,2800 pieces of data were collected containing the following fields,the first three properties were used as input,while the last one,was used as output.Subsequently,the model performance was analyzed.As shown in Fig.9,the three curves represented,respectively,the MSE values change with the number of iterations as training,validation,and test data were input for the model.There were 23 iterations in total.From 8th iteration,the mean squared error values decreased slowly,and after 17th iteration,the mean squared error values was basically unchanged,and thus,the model training was completed.Next,the model effectiveness was evaluated.Figure 10 shows the model conditions after model training,i.e.,the changes of gradient,damping factor,and generalization ability with the number of iterations.Initially,the gradient was the highest,and after 17th iteration,it tended to stabilize.The damping factor  was changed to 1 _x0005_ 10 6 from 17th iteration,and then remained constant,indicating the model convergence.The generalization ability curve was at 0 for the first 12 iterations,indicating that mean squared error values decreased continuously during this stage.After 17 iterations,mean squared error was basically unchanged overall,and thus,the iteration was completed.Finally,the model regression ability was visualized as shown in Fig.11,which visualizes the regression ability for all the model data,including the training,validation,and test data.The line formed by circles reflects the relationship between the input and measured sound absorption co-efficient data.The different color line represents the regression line,which reflects the relationship between the input and the model actual output data.The figure shows that the regression line was basically consistent with the measured data line.So,the proposed model regression effect was good.

As the above analysis,inputting the specimen data with different thickness and diameter into the proposed model,numerical simulation of sound absorption co-efficient at different frequencies can be obtained,and there is only minute deviation between the simulations and the measured values.So,the proposed model can lessen the costs involved to the measurement procedures.In addition,porous hemp plastic composites are environmentally friendly,light weight,creep resistance,good sound absorption properties,easy to manufacture,and low cost,which are suitable for noise reduction in intermediate and low frequency noise areas.For example,the material can be made into various sound absorbers to reduce noise in places where noise reduction is needed,such as hotel rooms,car interiors,conference rooms and so on,so as to provide people with a quiet environment.Anthropogenic greenhouse gas emission has emerged as the most dominating factor for climate change which is liable for an increase of nearly 1  C of global temperature above pre-industrial level.As a consequence,it is gradually leading world habitants to extinction by opening vulnerabilities of natural systems.Temperatures exceeding species’ physiological tolerances,changes in precipitation patterns,melting ice caps and rising sea levels,positive impact on harmful species,extreme weather events,disease outbreaks,increased incidence of skin cancer,shifting wind patterns,and expanding fungal diseases,cropping season changes affecting agricultural yield,severe food shortage,and negative impact on livestock are just a few of the most feared vulnerabilities.In recognition of the issue,The United Nations Intergovernmental Panel on Climate Change in 2018 has set a threshold of 1.5  C temperature increase in average warming above preindustrial level,meaning that a rise in global warming beyond this level would make the planet less than suitable for human life.In accordance,scientists advise taking control of greenhouse gas emissions,low carbon economy,development of renewable resources,technological changes,and forestation for stopping global temperature rise.Being aligned with the Paris Agreement,UK and France have already set an aim to “net-zero” emissions by 2050.

As an adaptation,efforts are in place for decreasing fossil energy consumption,greater attention has been put on optimal management and use of natural resources along with the development of renewable resources.In 2017,The European Union was able to arrange 17.5% of its consumed energy from renewable resources and aims to reach 32% by 2030.Global deforestation accounts for approximately 12–15% of anthropogenic greenhouse gas emissions; thereby,forestation is considered one of the most valuable strategies for reducing atmospheric carbon concentration since it works as an essential carbon sink.Enhancement of forest carbon stock has been added to the United Nation’s REDD þ initiative in 2008; the Bonn Challenge,among the others,is working for awareness and restoration of forest globally,intending to restore 350 million ha of forest by 2030.Since woody forestation takes a longer time,scientists emphasize fast-growing short-rotation forestation as a means of quick carbon sink and source of biomass for fuel.Due to these environmental concerns and balancing regulations,renewable raw materials of natural origin like kenaf,hemp,flax,jute etc.,are attracting more attention in different industrial sectors for their competitive physical properties against man-made counterparts and capability of higher carbon sinking.Industrial hemp has emerged as a highly successful commercial crop due to its carbon-sequestering property,higher biomass production,and various end-use products.Researchers believe that it can be successfully used as a cover crop since it can remediate contaminated soils through phytoremediation and can be produced without pesticides.Even hemp residues can act as botanical insecticides or miticides and inhibitors to soil nematodes and pathogenic fungi .It can replenish the soil by killing and displacing other tiny crops or weeds and absorbing heavy metals from soils.Hemp can be used for insulation and acoustic purpose in the building sector,paper industry,medicinal purpose,textile industry,bio-fuel,cosmetics industry,food and beverage industry,and fiber can be used as reinforcement in polymer matrix composites or in bio-composite as a substitute of glass and carbon fiber.The important uses of different parts of the hemp plant in various fields have been shown in Figure 1.Hemp is classified as industrial hemp containing less than 0.2% Δ9- tetrahydrocannabinol  and drug type hemp with greater than 0.2% THC .Although the history of the uses of hemp dates back to 5000–4000 BC,prohibition on its cultivation was imposed in many countries in the 20th century because it resembled marijuana.

However,after being correctly classified and realizing its environmental and financial benefits,this prohibition is now lifted for industrial hemp.A resurgence in hemp cultivation is seen since the European Union and the US,and other countries,have legalized the cultivation of industrial hemp,and many other countries have reintroduced hemp cultivation with low THC levels.For example,from 2020 Florida Department of Agriculture and Consumer Services is allowing its cultivation with the potential of building a $20–$30 billion industry in the state whereas Europe observed a record amount of hemp cultivation amounting to 33,000 ha in 2016.The authors in this review have discussed potential uses of hemp in different sectors from the perspective of a green environment with up-to date knowledge with the belief that other than financial benefits,multipurpose uses of hemp can be a noticeable response to global warming and climate change.Hemp is one of the ancient plants cultivated by humans for textile use.Currently,trim trays more than 30 countries are involved in the global hemp trade due to its capability of growing in pesticide and herbicide-free environment,noticeable resistance to rodents,fungus and many types of weeds,wide geographical range of cultivation,and multipurpose uses.According to FAO Stat,three major hemp-producing countries by production area are Canada,North Korea,and France.It requires similar soil preparation to other break crops with pH 6.0–7.5.It grows well on loose,well-drained loam soils with a mean temperature between 16 – 27  C and high moisture.The final yield depends on sowing density,nitrogen level,harvest time,and it can grow up to 0.31 m in a week.Hemp is a tall,annual crop with a low labor-intensive production process and can be accomplished in a short cropping period.Hemp cultivation has become more appealing to farmers than flax because it has a lower chance of crop failure.It guarantees higher yields  while also enhancing soil nutrition.The industrial norms for producing this crop are generally guided by organic cultivation to maintain the fiber quality in terms of fineness,strength and color.Hemp fiber cultivation requires about 77.63 percent less cost in fertilization,seeds,field operation,and irrigation costs than cotton,the most recognized natural fiber.It shows many unique properties that differ from other natural fibers by their aseptic properties,high absorbency,protection against UV radiation,and free from allergenic effect.The chemical composition of hemp and some other vegetable fibers has been shown in Table 1,indicating that hemp has higher cellulose,satisfactory hemicellulose and lower content of lignin and pectin,which are advantageous for various processing and uses.The fiber extraction process comprises four steps: retting,breaking,scutching and hackling.Field retting  and water retting  are the most common retting methods.During retting,pectins are broken down,and naturally grown bacteria and fungi bind the fiber together.Then,with the help of flfluted rollers,stems are broken down.Next,the stems are separated by beater during scutching,followed by hackling process,and finally combing is done to separate and straighten the fibers.As an ancient raw material,hemp had been used for paper making since 105 AD in China.

The technology later disappeared due to emerging of wood-based paper,state-of-the-art technology and market demand.The sourcing,processing,and management of non-woody material like hemp for producing quality paper are now obvious for several reasons.Until the end of the nineteenth century,hemp and wastage of hemp-made household stuff like clothes,ropes,rags and sails had contributed 75–90% of raw materials to global paper production.The first copy of the Bible was written onto hemp papers and the glorious history of hemp paper has been associated with the declaration of independence and the constitution of the US.Papers are said to be sustainable in all formats,but sourcing raw materials require sustainable forestry management .Since the twentieth century,wood has been considered the primary raw material in paper industries.According to Food and Agriculture Organization,40% of the raw materials for the paper industry come directly from wood,and a total of 89–92% is supplied from wood-based materials.The increasing need for paper is continuously putting pressure on forests per capita,whereas regional restrictions are being imposed worldwide by local governments to save forests and the environment.The situation declares the urgency to find new fast-growing raw materials for paper at the place of conventional wood plants.Therefore,from this century,non-woody raw materials like straws,bamboo,kenaf,hemp etc.,got considerable interest as raw material for paper-making to reduce the increasing pressure on forest wood resources .In 2010,non-woody fibrous plants contributed 8–11% to global pulp production and the growth rate is estimated to record a 2.5% compound annual growth rate  by 2027.Non-woody raw materials offer easier pulpability,quality bleached pulp,and specialty paper from the selective part of the plants.Hemp yields more biomass than wood,offering even two times more useable fibers than forests.Industrial hemp consists of a maximum of 77% cellulose which is three times more than wood and other agricultural wastes.This indicates a quadruple amount of paper can be produced from hemp against forests grown in the same area.In addition,hemp is a short rotation crop that can be harvested after four months of cultivation,whereas hardwood and softwood plants require 8–12 years and 20–80 years,respectively in rotation cycles.Again,the opportunity to recycle hemp bast fiber-made papers is twice that of wood-based papers .Hemp stalks are composed of long bast fibers and hurds,where the latter is four times more by weight than fiber.

Hemp seeds could be considered a sodium-free food, as whole and hulled hemp seeds contained less than 5 mg/100 g.Notwithstanding the foregoing, the real contribution of hemp seeds to NRVs is lower because their serving size is approximately 30 g.As it can be seen in Fig.1b, whole hemp seeds could be considered a source of potassium and calcium, but the contribution to NRVs of 30 g would be only 9% and 7%, respectively.However, the contribution to manganese and copper NRVs of a serving size were higher than 40% in both whole and hulled hemp seeds.The contribution to manganese NRV stood out because the consumption of 30 g of whole hemp seeds would exceed an intake of 100% NRV.In this view, the interpretation of the claims can be confusing for the consumer due to the fact that they are linked to the presence of these compounds in 100 g of seeds without taking into account the serving size.Phytate content, expressed as g PAE/100 g, is shown in Table 3.The average phytate content in whole hemp seeds was 2.80 g/100 g, being ‘Carmagnola’ and ‘Tiborszallasi’ the varieties with the lowest phytate content, 2.66 mg/100 g, and ‘Fedora 17’ the variety with the highest, 3.08 g/100 g.The phytate content was higher in hulled hemp seeds, 4.00 g/100 g on average.Mattila et al. reported a phytic acid content of 3.5 g/100 g, which was higher than the phytate contents of this work.Their result was expressed in dry matter, so it would be lower if expressed in fresh weight and closer to the maximum valued obtained in this work, which was higher than 3 g/100 g.Schultz et al. analysed different varieties and their average value was 2.67 g/100 g, very close to the average value obtained in this work.It was not possible to find previous studies about phytate content in hulled hemp seeds.

Based on phytate and phosphorus content, phosphorus from phytates  and the proportion of phosphorus from phytates with respect to total phosphorus content were calculated.The phosphorus from phytate calculation is indicative, as different phytates have a different number of phosphate groups and they are expressed in this work as PAE.So,grow tent indoor the proportion of phosphorus from phytates with respect to total phosphorus content is also indicative, but it provides information about phosphorus bioavailability.In whole hemp seeds, the proportion of phosphorus from phytates with respect to total phosphorus content was higher than 90%, and it was even higher in hulled hemp seeds.These results indicate that almost all of the phosphorus is found as phytates in hemp seeds, so its bioavailability is supposed to be low.From phytate, iron, and zinc contents, the phytates/zinc and phytates/zinc molar ratios were calculated, according to Dahdouh et al., and included in Table 3.It is considered that iron bioavailability is affected by a phytates/iron molar ratio above 1 , and whole and hulled hemp seeds showed values higher than 20 and 30, respectively.In the case of zinc, a phytates/zinc molar ratio above 15 is considered to compromise its bioavailability.All the samples analysed had phytates/zinc molar ratios much higher than 15, even above 60.The fractional absorption of phosphorus is higher than that of calcium and it is recommended a calcium/phosphorus molar ratio should range between 1.4 and 1.9 for a suitable equilibrium and absorption of both elements.Considering the calcium and phosphorus contents shown in Table 2, the calcium/phosphorus molar ratio ranged from 0.12 to 0.20 in whole hemp seeds and from 0.04 to 0.07 in hulled hemp seeds.These values were very low, especially in hulled seeds, due to their higher phosphorus content and their lower calcium content.All values were much lower than the recommendation, so the calcium absorption could be compromised because of the high content of phosphorus.

However, it has been previously said that phosphorus contained in hemp seeds is difficult to assimilate because it is in the phytate form, so the calcium/phosphorus molar ratio would not represent a real competition in terms of absorption.Another anti-nutritional compound that could reduce the calcium bio-accessibility in plant foods is oxalic acid.It is said that an oxalic acid/ calcium ratio higher than 2.25 could compromise calcium absorption.Considering the calcium contents shown in Table 2 and the oxalic acid content previously reported by Alonso–Esteban et al., the oxalic acid/calcium ratio was lower than 2.25 in all samples, with average values of 0.56 and 1.27 in whole and hulled hemp seeds, respectively.So, the presence of oxalic acid in hemp seeds could not compromise calcium bio-accessibility.Oxalate/calcium molar ratio would be even lower due to the higher molecular weight of oxalates, so there would be no risk according to Israr et al. and Udomkun et al., who indicate that an oxalate/calcium molar ratio higher than 2 could be hazardous.The impeachment of phosphorus, iron, zinc and calcium absorption due to their chemical forms and the presence of anti-nutrients, reveals that using just the numerical contents of nutrients to make nutritional or health claims in foods, is not a suitable tool for a proper information to consumers, since their contents may not be totally available for the human body.The bio-accessibility of other mineral elements would not be compromised by phytates or oxalates.However, future studies concerning mineral element bio-accessibility and bio-availability in whole and hulled hemp seeds should be carried out in order to evaluate if they are a good dietetic source of mineral elements.Hemp  is a plant well known for its content of bio-active cannabinoids, a group of secondary metabolites unique for the genus Cannabis.These compounds are produced by specialized glands in the leaf epidermis, occurring more densely in the inflorescence and less in the leaves.Four cannabinoids are present at high quantities, cannabidiolic acid  and Δ-9-tetrahydrocannabinolic acid,which decarboxylate at elevated temperatures to form cannabidiol  and Δ-9-tetrahydrocannabinol  respectively.Cannabinol  is a degradation product of THC.Due to their interactions with the human endocannabinoid system, these compounds are of special interest for their therapeutic potential in neurological disorders.

THC is a psychoactive compound with effective doses between 10 and 20 mg THC, while the other three cannabinoids are nonpsychoactive compounds or exert only a low psychoactivity.Therefore, it is the presence of THC in hemp food products that is of special interest for food control purposes.However, it is not only the original THC content of the starting material that is being considered, but also the formation of additional THC due to conversions in the course of industrial processing or preparation by the consumer, such as that of THCA into THC.It is known that hot temperatures increase THCA decarboxylation to form THC, whereas this conversion does not occur in the human body.Formation of THC could also possibly occur by conversion of CBD under acidic conditions.However CBD-to-THC conversion was never actually observed, neither under specific light or temperature regimes nor in a simulated gastric juice.Consequently, THC formation by this route is likely not relevant for food products.In Austria, cultivars of Cannabis sativa with a THC-content below 0.3% are not regulated by the Narcotic Substances Act.However, cultivation in Europe is only subsidized when using cultivars from the Common EU Catalogue of Varieties of Agricultural Plant Species.In a fiber hemp, CBDA is the major cannabinoid.However, even these varieties are never completely free of THC.That is one of the reasons why EFSA assessed the human exposure to THC and established an acute reference dose  of 1 μg Δ9-THC/kg body weight for the use of fiber type hemp in food.Hemp leaves have become very popular as ingredients for herbal teas , either as hemp-only tea or as part of tea mixtures.These herbal teas are usually prepared as infusions by pouring boiling water on the plant material and allowing to steep for a defined period of time.The preparation of herbal infusions is not well standardized, specifically, water temperature will shift while cooling down during the extraction process.It can be expected, that because of their lipophilic nature, even under optimum extraction conditions, only a fraction of the cannabinoids are transferred into a herbal infusion.However, there is no validated, generally recognized method for analyzing cannabinoids in infusions, partially due to issues in recovering lipophilic compounds from water.In order to address the former challenge a response-surface modelling approach was used to cover a range of water temperatures, water volumes and steeping times for the preparation of an infusion.To address the latter, rather than attempting to determine the cannabinoid contents in the tea liquid, the cannabinoid contents of the starting plant material before infusion and the residue after infusion were compared and loss or gain of the major cannabinoids for this aqueous extraction was calculated.The upper leaves of Cannabis sativa L.var.‘Fiona’ were harvested before flowering and dried at room temperature.

Each extraction experiment was performed with an analysis sample of approximately 1.5 g that represented a portion of a laboratory sample of approximately 800 g.These portions were arrived at by dividing the total laboratory sample with a riffle divider in nine serial steps, grow tent hydroponic at each step into halves.In order to establish that the resulting portions were actually true aliquots of the original laboratory sample, 14 randomly chosen presumptive aliquots were tested for their cannabinoid contents.For CBD and CBDA the relative standard deviations were 3.8% and 2.7%, respectively.For THC and THCA the relative standard deviations were 3.6% and 3.0% respectively.From this we concluded that our laboratory analysis samples were in fact true aliquots, that the measured cannabinoid values were in fact reliable base values for the following recovery experiments and that the observed RSD% values for repeatability likely represented but measurement uncertainty.Food products prepared from fiber-type hemp cultivars, poor in THC, but rich in CBD, have become very popular.Besides hemp oil, beverages like hemp beer and CBD rich food supplements, infusions from inflorescences and/or leaves that are widely used either as single ingredient or in herbal tea mixtures.Lipophilic cannabinoids are only marginally soluble in water, and to some extent, the cannabinoids in a herbal infusion may become adsorbed onto small particles suspended in the tea.Thus, due to their lipophilicity and potential adsorption issues, analysis of cannabinoids in an infusion is difficult and not reproducible.Therefore, this paper focuses on the quantitation of cannabinoids in the residue of the hemp leaves after preparing the infusion, using HPLC/UV.In the process of preparing an infusion of plant material, the solvent will extract the soluble constituents thus reducing the remaining content in the plant residue, but no extraction occurs for insoluble compounds.In our case, the contents of CBD and THC in hemp leaves residues after infusion were even increased, when compared to the starting plant material, presumably due to decarboxylation of their corresponding acid-forms at higher temperatures.Increase or decrease of a particular cannabinoid’s content in the hemp leaf residues appear primarily related to the lipophilicity of the compound  of 5.95 , 6.25 , 6.33 and 6.63 and the extent of decarboxylation.

Some peculiar differences were observed for different extraction temperatures regarding the cannabinoids content before and after tea preparation.Taschwer and Schmid  found in plant material dried at 50 ◦C no conversion of THCA to THC, whereas complete decarboxylation was recorded at 100 ◦C and 150 ◦C, but only after 2 h and 1 h, respectively.Therefore decarboxylation cannot be expected to play an important role when preparing a herbal infusion by pouring boiling water over the plant material with a steeping time of 10 min , but has to be considered for decoctions.THC may also degrade to CBN under certain conditions.However, degradation of THC to CBN is insignificant at boiling temperature of water and 15 min extraction time , as also confirmed by our study.The solubility of THC in water at 23 ◦C is 2.8 mg/l.The solubility of the other cannabinoids in water should theoretically increase in the order THC < THCA < CBD < CBDA  but are not yet experimentally proven.Solubility of cannabinoids at higher water temperatures is also unknown, but likely increasing as e.g.observed for solubility of saturated fatty acid in water.However, a spiking experiment with pure THCA and THC to boiling water  showed only 63% recovery or THCA  and only 17% for THC.Calculating for better comparability the differences between hemp leaves before and after tea preparation at 43 ◦C for 15 min in a volume of 150 ml  resulted in 26.46 mg/l CBDA, 1.24 mg/l CBD, 0.82 mg/l THCA and 0.37 mg/l THC.