In this context, the results obtained in this study could be of great significance to the safety evaluation of PET samples in Ecuador and would allow analyzing the PET recycling processes and avoiding contamination by PET flakes from nonfood containers.Polyethylene terephthalate (PET) is the plastic packaging material most widely used to produce bottles intended for contact with food and beverages. However, PET is not inert, and therefore, some chemical compounds present in PET could migrate to food or beverages in contact, leading to safety issues. To evaluate the safety of PET samples, the identification of potential migrants is required. In this work, eight PET samples obtained from the Ecuadorian market at different phases of processing were studied using a well-known methodology based on a solvent extraction followed by gas chromatography–mass spectrometry analysis and overall migration test. Several chemical compounds were identified and categorized as lubricants (carboxylic acids with chain length of C12 to C18), plasticizers , thermal degradation products , antioxidant degradation products (from Irgafos 168 and Irganox), and recycling indicator compounds . Additionally, overall migration experiments were performed in PET bottles, resulting in values lower than the overall migration limit (10 mg/dm Polyethylene terephthalate (PET) is a plastic packaging material commonly used to produce bottles for drinking water, mineral water, carbonated beverages, and edible oils . This sePET bottle production generally consists of two phases: injection and blow-molding. In the injection phase, PET pellets are used to obtain amorphous preforms. Then, in the blow-molding phase, preforms are stretched to obtain biaxially oriented bottles. Some substances can be added to PET to improve the performance during the processing of bottles and to enhance their functional properties. Therefore, these additives could migrate to food in contact. Additionally, the bottle manufacturing processes can lead to polymer and additive degradation, generating compounds that could be potential migrants from PET bottles into foodstuff in contact .In the case of plastic packaging materials, migration tests for checking compliance are required in all articles intended to come into contact with foodstuffs, according to EU regulations ,7,8, wheThe methodologies to identify the potential migrants in plastic packaging materials commonly use solvent extraction followed by chromatographic separations and mass spectrometric detections, approaches which are complex and require laborious sample preparation ,14,15,16The migration of chemical compounds from PET bottles to a medium in contact has been extensively reported in the literature ,18,19,20In 2013, Ecuador implemented a regulatory framework for plastic materials and articles intended for food contact, adopting the European regulation about overall and specific migration. In the case of PET, the recycling chain to produce rPET in this market is relatively recent compared with developed countries. Moreover, to our best knowledge, no literature has been reported about the chemical compounds present in PET bottles in Ecuador. Thus, the objective of this work was to identify the potential migrants in PET samples at different phases of processing, such as resins, preforms, and bottles obtained from various suppliers of the Ecuadorian market. Samples were analyzed by GC-MS, and the compounds identified were then categorized according to their use and application in plastic packaging. Additionally, the overall migration of PET bottles was determined with the aim of evaluating the compliance of bottles with the overall migration limit established by regulations.Chloroform (99.5%), ethanol (99.9%), and a standard solution of a series of alkanes  were obtained from Sigma Aldrich .Samples of virgin PET pellets, preforms, and bottles were supplied by Ecuadorian companies specialized in the manufacturing of PET preforms and bottles intended for contact with beverages, mineral water, and edible oil.Two batches of samples were collected, each consisting of virgin pellets, preforms, and bottles. Additionally, 2 types of bottles were collected, resulting in the obtention of a total of 8 samples that were studied in this work. Batches were labeled P and T and bottles were labeled A and D, in reference to the name of the supplier company.The preform samples were ground using a Retsch MM 400 universal laboratory mill  in presence of liquid nitrogen to prevent any degradation during grinding; grinding was performed in order to increase the surface area and thus to improve the extraction efficiency. In the case of bottles, samples were cut into small square pieces of around 5 mm per side.For all samples, 5 g of material was placed in a cellulose thimble  and put in a Soxhlet apparatus with 200 mL of chloroform  in order to extract the chemical compounds from PET samples. The speed of Soxhlet extraction was equivalent to one cycle every 20–30 min. The extraction of each sample was carried out in triplicate.Then, extracts were concentrated to approximately 5 mL using a rotary evaporator  at 40 °C. After, the extract was filtered using a polytetrafluoroethylene (PTFE) membrane with a pore size of 0.45 µm  and was stored in a freezer at 4 °C before being analyzed.A volume of 2 μL of sample concentrated extract was injected in splitless mode into a gas chromatograph (GC) from Agilent Technologies, Model 7890A, coupled with a mass spectrometer 5975 INSERT. The GC was equipped with a capillary column DB5-MS . The carrier gas was He at 0.9 mL/min. The oven temperature program began with an initial temperature of 40 °C for 1 min, and then the temperature was increased at a rate of 3 °C/min to 300 °C and then maintained for 25 min. The mass spectrometer parameters used for identification of chemical compounds were as follows: electron impact ionization; electron energy, 15 eV; ion source, 230 °C; electron multiplier voltage, 3000 eV; transfer line, 305 °C; scanning, between 50 and 700 amu. The data were recorded by MSD ChemStation software  and the identification of the constituents was achieved using mass spectral matches with Wiley7 NIST 05 mass spectra database. To confirm identification, Kovats indices were determined. For that, a standard mixture of alkanes C7 to C40 in hexane was analyzed under the same conditions as the samples.v/v). PET bottle samples were cut into squares of 10 cm × 10 cm, and then they were cut into smaller pieces of 2.5 cm × 2.5 cm. PET squares were placed in a glass bottle with 100 mL of food simulant and sealed using a screw cap with silicon/PTFE septa. Then, the glass bottle was placed in an oven  at 40 °C. Three replicates for each PET bottle sample were carried out. After 10 days of conditioning time, the bottles were removed from the oven, and the squares of PET samples were removed from the bottles. Then, the bottles containing the simulant were placed in an oven at 115 °C in order to evaporate the simulant. When the bottles were dried, they were put inside a glass desiccator to reach room temperature. Finally, the bottles were weighed by an analytical balance  to verify that they reached constant weight. Finally, overall migration was determined by applying Equation (1): M is the overall migration in mg/dm2, m1 is the weight glass vial before overall migration, m2 is the weight glass vial after overall migration, and S is the area of PET in contact with food simulant.The overall migration (OM) was measured using a gravimetric method, in which the sample residue was weighed after the evaporation of a food simulant. The test conditions and simulant used for the OM assays were chosen according to the European Regulation 10/2011 . In thisWith the purpose of identifying the potential migrants in PET samples, a methodology based on solvent extraction followed by GC-MS analysis was used. The identification of chemical compounds was carried out using mass spectral matches with the Wiley7 NIST 05 mass spectra database and confirmed comparing their Kovats indices.The results showed the presence of several chemical compounds in the PET samples studied, identifying a total of 22 compounds; among them, 6 were identified in pellets, 9 were identified in preforms, and 20 were identified in bottles. The compounds identified in pellets and preforms are listed in After identification, the compounds were categorized according to their use and application in plastic packaging, such as lubricants, plasticizers, products of thermal degradation, degradation products of antioxidants, and recycling indicators. The chemical compounds identified are discussed below by category.Lubricants are a group of additives used to reduce the friction between the equipment surfaces and the polymer, promoting the flow of plastic over and through the equipment and preventing the plastic from sticking to the surfaces. The main lubricants used in plastic packaging materials are carboxylic acids, their esters and amides, polyethylene waxes, paraffin, stearates, and silicones. Generally, lubricants can be added to the plastic resin or applied externally .Lubricants identified in this study were carboxylic acids with chain lengths varying from C12 to C18, which are shown in Plasticizers are used in plastic packaging materials to improve their flexibility, extensibility, and processability. In this work, two plasticizers were found: triethyl phosphate and diethyl phthalate. The first one, triethyl phosphate, was identified in bottles P and D. The organophosphorus compounds are frequently used as plasticizers and flame retardants in plastic packaging; however, they are also used as antifoaming agents and additives in products such as lubricants and hydraulic fluids ,29. ThisThe second compound, diethyl phthalate, was found in pellets and in all bottles studied as shown in Some phthalates plasticizers for PET have been reported, such as dipentyl phthalate (DPP), diethyl phthalate (DEP), diisobutyl phthalate, and dibutyl phthalate (DBP) . Bis in order to ensure their biaxial orientation. So, one source of contamination of phthalates could be attributed to the compressed air that comes from pumps, filters, pipes, etc. . On the Additionally, In fact, during PET manufacturing, several degradation and decomposition reactions can occur. High temperatures and the presence of oxygen in the PET can promote thermo-mechanical and thermo-oxidative reactions generating numerous compounds in the polymer. In this context, several studies about the PET thermal degradation process have been reported in the literature ,35,36. TIn PET samples, three compounds were found that can be categorized as degradation products of antioxidants: 2,4-bis phenol in bottles P, T, and D; 2,6-di-tert-butyl-1,4-benzoquinone in bottles T and D; and 3,5-di-tert-butyl-4 hydroxybenzaldehyde in preforms P . LiteratThe presence of air during the melt processing of PET can lead to thermo-oxidative degradation. In order to prevent this degradation, antioxidants are added during polycondensation . BetweenMoreover, The results show the presence of two compounds that can be related to postconsumer recycled PET: limonene and benzophenone. Limonene was identified in preforms T and bottles T and D, whereas benzophenone was found in bottles P, T, and D . These tThe bottle-to-bottle recycling process of PET must successfully reduce the concentrations of chemical compounds sorbed previously by the bottles in their first use ; howeverAdditionally, two alkanes were identified in PET samples. Hexadecane was found in bottles P, and heneicosane was identified in bottles P, T, and A. The presence of alkanes was reported in the recycled PET , and hexFinally, two aliphatic aldehydes were identified in samples. Nonanal was found in bottles P, A, and D, whereas decanal was identified in bottles D. These compounds are very common in flavored soft drinks containers (Nerin 2003). In this sense, the presence of these aldehydes in PET bottles could be related to the use of recycled PET for the manufacture of bottles.Here, it should be noted that in 2018 the industrial sector of beverages of Ecuador announced the use of around 25% of recycled material in the production of PET bottles, showing this value on the labels of bottles. Additionally, in December 2020, a new national regulation on single-use plastics products was adopted in Ecuador, giving a term of 4 years to the industrial sector to use 30% of recycled PET in the production of bottles . ConsequIn order to identify the chemical compounds at different phases of the processing of PET bottles, we compared the results obtained in pellets, preforms, and bottles of suppliers P and T. The results showed 13 chemical compounds identified in samples P and 12 compounds in samples T, as shown in Additionally, compounds identified in preforms but not in pellets were 3,5-di-tert-butyl-4-hydroxybenzaldehyde in preforms P and p-xylene, benzaldehyde, dl-limonene, and benzoic acid in preforms T. As mentioned before, the presence of 3,5-di-tert-butyl-4-hydroxybenzaldehyde is related to the degradation of butylated hydroxytoluene (BHT) , whereasThe compounds identified in preforms and bottles T were dl-limonene and benzoic acid, the first one being a recycling indicator and the second one being a product formed from thermal degradation of the polymer. Regarding the compounds identified only in PET bottles, the results showed the presence of p-xylene, nonanal, triethyl phosphate, phenol, 2,4-bis-, and hexadecane in bottles P and 2,6-di-tert-butyl-1,4-benzoquinone, phenol, 2,4-bis-, heptadecanoic acid, and heneicosane in bottles T. The presence of p-xylene, nonanal, 2,6-di-tert-butyl-1,4-benzoquinone, and phenol, 2,4-bis- could be explained by thermal degradation of polymer or additives during the processing of bottles. Moreover, the compounds identified in PET bottles such as triethyl phosphate and heptadecanoic acid should show their use as plasticizers in PET. Finally, the results showed possible contamination of bottles P and T with hexadecane and heneicosane by using PET flakes from nonfood containers.From a qualitative point of view, it can be mentioned that the chromatograms of the preform samples presented a higher number of peaks compared to the chromatograms of the bottle samples. The pellets presented the lowest number of peaks, as can be observed in Additionally, some peaks present in the chromatograms of PET samples could not be identified, due to the limits of the methodology used in this study; however, the main unknown peaks detected in the samples are presented as 2 in bottles P, 4.7 ± 1.44 mg/dm2 in bottles T, 3.00 ± 0.79 mg/dm2 in bottles A, and 3.40 ± 0.67 mg/dm2 in bottles D. These results were lower than the maximum limit established by regulations (10 mg/dm2) [2 [The overall migration tests of the PET bottles were carried out using food simulant “A” (aqueous foods), according to European regulation. The results of global migration were 1.2 ± 0.32 mg/dm mg/dm2) ; however/dm2) [2 .Several potential migrants were identified in eight PET samples intended for contact with food: 6 compounds in resins, 9 compounds in preforms, and 20 compounds in PET bottles. The compounds identified were categorized as lubricants (C12–C18 carboxylic acids), plasticizers, products of thermal degradation, degradation products of antioxidants, and recycling indicators. Hexadecanoic acid and octadecanoic acid were found in all samples, which could be related to their use as lubricant components in the studied samples. Diethyl phthalate and alkanes found in the bottles studied in this work could be explained by contamination during processing or the use of PET recycled flakes from nonfood containers. Moreover, the values of overall migration found in PET bottle samples were lower than the limit established by regulations; consequently, they may be used for contact with water and soft drinks. The results obtained in this study could be of great significance to the safety evaluation of PET samples in Ecuador and would allow analyzing the PET recycling processes and avoiding contamination by PET flakes from nonfood applications.


Purpose: Short track speed skating is a racing sport with racing tactics are equally crucial to speed and technical skating skills. Therefore, to investigate the relationship between starting and finishing positions for elite skaters and subsequently, explore pacing patterns for champions are necessary.Methods: To investigate a pattern of effective tactical positioning strategy, Kendall’s tau-b correlations between starting and finishing position were calculated, with 500 m races having the most positive correlation .Results: Furthermore, starting position distributions of winners in each round, as well as the fluctuations in champion starting positions across rounds were analyzed. Our findings showed that skaters on the first track were inclined to win the rounds in 500, 1,000, and 1,500 m , and the differences between starting and finishing positions for champions were minimized in semi-finals. Meanwhile, the pacing patterns were gaining more fluctuations by the increase of race distances for champions, as the average standard deviation of lap rankings equaled 0.90, 1.15, and 2.21 for 500, 1,000, and 1,500 m races, respectively.Conclusion: In conclusion, elite skaters should adopt flexible tactics at the lowest cost of energy consumption. The overall variability of lap ranking in long-distance races were distinctly higher than it in short distance. Short track speed skating is a competitive way of ice speed skating. During races, competitors are pitched against each other in groups ranging from four to six and skate on an oval ice track with a length of 111.12 meters. The races are fast and furious with fastest speed reaching 91 kilometers per hour and skaters who continuously scramble for advantage often feel fatigue, frequently tackling with opponents to ground with them. Skaters are required to allocate the available energy that is known as pacing . Many thIn addition, short track speed skating is a racing game that tests the speed, technical skating ability and aggressiveness of its competitors. In contrast to conventional long-track speed skating, contestants race against each other instead of the clock. This means the final rankings are determined by the relative positions between skaters rather than the finishing time per short track speed skating player. To win the game, strength quality , push-ofThe lanes of the first qualifying round of skating are drawn by the Competitors Steward, a software that can assign random lane numbers to athletes, and for the subsequent rounds, the lane positions will be decided by the results from the preceding qualifying round according to the specific regulations of short track speed skating from ISU  . More spA study on the influence of starting position on finishing position in 500 m races showed a significant positive correlation between them especially in semi-finals and finals regardless of genders. This study was based on data from the five seasons between 1999–2000 and 2003–2004 of 500 m races at the ISU Short Track World Cups . MuehlbaAs a result, finishing times are irrelevant in short track speed skating as long as skaters finish ahead of opponents. The current studies explored the differences in variability between and within races, and demonstrated how analyses of such variability could provide insights into tactical pacing decisions ,b. More Although position analysis and pacing strategy have demonstrated prominent roles in short track speed skating races, current researches on this topic are inadequate with limited data, and yet no literature, to the best of our knowledge, is dedicated to the exploration of pacing patterns for champions. This study will first verify the previous findings with a new larger dataset, and then focus on the winners in each round to investigate the distribution of their starting positions. The variations of champion starting positions during the rounds are also explored to examine positioning strategies of these medalists. Finally, the pacing patterns for champions in 500, 1,000, and 1,500 m events are rigorously analyzed.This paper deeply investigated the relationship between the positions and rankings from 121 competitions (World Cup Series / Championships / Olympic Games) from 2007/2008 to 2019/2020 season. All data were created and assessed the validity and reliability from the official website of International Skating Union (ISU), under the consent of the terms and conditions of the data source. The original dataset comprised of 183,158 items of match information , with each piece representing split time of each athlete, name of competitions, rounds and laps numbers. After data cleaning, which attempted to discard data when penalties or disqualifications occurred, 67,258 pieces of data altogether containing the temporal information about 500, 1,000, and 1,500 m competitions in the preliminary, heat, quarter-final, semi-final and final rounds were thus eliminated. Hence, filtered dataset consisted of 115,900 pieces of data which were labeled by sorts of attributes, such as race distance, competition, gender, name, country and so forth, would be conducted via multi-dimensional analysis. For further analysis of race behaviors for champions, 173 female and 247 male champions were announced out of 4,313 female and 5,212 male individual races .Starting positions were marked as 1 to 4 , and 1 to 6  that represent inner to outer lanes. The Kendall’s tau-b correlation was analyzed to evaluate the correlation between starting and finishing positions of the race. The correlation coefficient interpretations vary with magnitudes of values lower than 0.2 or 0.2 to 0.5 or greater than 0.5, suggesting low, moderate and strong correlations, respectively. And the significance level was set as P < 0.05. Correlation coefficient analysis was conducted via the SPSS (version 16.0). Moreover, we sketched the starting position distributions for round winners and obtained the dynamical evolution between starting and finishing positions in different rounds for champions in order to realize the most optimal match strategy. We also calculated the mean value and standard deviation of rankings per laps for champions in all rounds to obtain pacing patterns and individual skating styles for elite skaters.P < 0.05) and progressively decreasing by 1,000 m  and 1,500 m . An exception was 3,000 m, because the correlation coefficient evidently exceeded 1,000 and 1,500 m . To figure out the abnormal phenomenon of 3,000 m, the correlations of 3,000 m Super-final and 3,000 m Relay were further calculated, respectively. 3,000 m Super-final race displayed the lowest correlation coefficient  in all the race distances while the 3,000 m Relay  supplied the highest value.The correlations between starting and finishing position by different race distances and rounds were shown in P < 0.05) and the similar tendency was found in 1,000 m race although all the rounds were positively correlated. On the contrary, in 1,500 and 3,000 m race, correlation coefficients of Heats were also far lower than the final rounds. There was no specific linear relation about the correlation between starting and finishing position among quarter-final, semi-final and final rounds.Furthermore, there were various trends in correlation coefficients across rounds in different race distances. Like 500 m of the column , the corThis research mainly concentrated on the individual races, so that only 500, 1,000, and 1,500 m races were further investigated. Gender in this research was not considered since no conclusions on sexually significant differences had been derived from prior studies.The mean values and standard deviations of lap rankings for champions in 500 m, 1,000 and 1,500 m were computed –4, respeThe purposes of the present study are twofold. Firstly, investigate the relationship between starting and finishing positions for elite skaters in short track speed skating races. Secondly, explore pacing patterns for champions. Consequently, four statistical experiments were progressively conducted. (i) We calculated the correlations between starting and finishing position on the basis of rounds in all competitions to investigate the overall impacts of starting lanes on final ranking. (ii) The starting position distribution of winners was examined accordingly in each round based on the first part. (iii) Dynamical evolution of starting and finishing positions were analyzed for champions. These sequential characteristics revealed the strategic patterns of elite short track speed skating athletes. (iv) Pacing patterns for champions in varied competitions were studied as we examined the position per lap along with standard deviation and the maximal margin.The positive correlations are seen in 500 to 3,000 m events, which are consistent with findings in To seek for the theoretically optimal distribution of energy and improve the tactical considerations have already gained much attention in cross-country running , rowing The use of artificial intelligence technologies to visualize and analyze data gains favor in modern sports science , due to Our findings indicate that elite skaters should adopt a strategy to conserve energy during the qualifying rounds before coming to the semi-finals, however, they should maintain excellent performance to advance to the final round. Meanwhile, round winners were largely split amongst the top 3 starting lanes in preliminary, heat, quarter-final and semi-final races in 500, 1,000, and 1,500 m competitions. Although long-distance race champions started from widely dispersed places but finished with similar pacing patterns, the overall variability of lap ranking in 1,500 m races were distinctly higher than it in short distance (500 m races).The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.LS and KT designed the study. KT supervised the study. TG and FL performed the experiments. LS, TG, and KT wrote the manuscript. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


T method, geNorm, NormFinder, and RefFinder were applied to obtain the genes most suitable to be considered as references for measuring the levels of expression in glioma samples. The results show that PKM and TPI1 are two novel genes suitable for genic expression studies on gliomas. Finally, we analyzed the expression of genes involved in metabolic pathways in clinical samples of brain gliomas of different CNS WHO grades. RT-qPCR analysis showed that in CNS WHO grade 3 and 4 gliomas, the expression levels of HK1, PFKM, GAPDH, G6PD, PGD1, IDH1, FASN, ACACA, and ELOVL2 were higher than those of CNS WHO grade 1 and 2 glioma biopsies. Hence, our results suggest that reference genes from metabolic pathways have different expression profiles depending on the stratification of gliomas and constitute a potential model for studying the development of this type of tumor and the search for molecular targets to treat gliomas.Gliomas are heterogeneous, solid, and intracranial tumors that originate from glial cells. Malignant cells from the tumor undergo metabolic alterations to obtain the energy required for proliferation and the invasion of the cerebral parenchyma. The alterations in the expression of the genes related to the metabolic pathways can be detected in biopsies of gliomas of different CNS WHO grades. In this study, we evaluated the expression of 16 candidate reference genes in the HMC3 microglia cell line. Then, statistical algorithms such as BestKeeper, the comparative ΔC Glioma is the most common and lethal tumors of the central nervous system (CNS); in the USA alone, an incidence rate of 3.22 per 100,000 population is reported [Gliomas account for approximately 55% of malignant primary brain tumors, and in approximately 70% of cases, the glioma is classified as an astrocytoma CNS WHO grade 4 (GBM) —a very aThe RT-qPCR technique has become the method of choice for the quantification of accurate gene expression . The advGAPDH), β actin (ACTB), β glucuronidase (GUSB), hypoxanthine guanine phosphoribosyl transferase (HPRT1), hydroxymethylbilane synthase (HMBS), TATA-box binding protein (TBP), and small ribosomal subunit (18S). However, some studies have reported that these common genes show variability in expression levels in different samples and experimental conditions [TBP and HPRT1, 14-3-3 protein zeta/delta (YWHAZ), and 60S ribosomal protein L13a (RPL13A) [Among the most common genes used as reference genes in RT-qPCR studies are glyceraldehyde-3-phosphate dehydrogenase  ,18,19, tHK1), phosphofructokinase muscle (PFKM), triosephosphate isomerase 1 (TPI1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate kinase (PKM), lactate dehydrogenase A (LDHAL6A), glucose-6-phosphate dehydrogenase (G6PD), phosphogluconate dehydrogenase 1 (PGD1), transketolase 1 (TKT1), succinate dehydrogenase B (SDHB), fatty acid synthase (FASN), acetyl CoA carboxylase (ACACA), fatty acid elongase 2 (ELOVL2), and TATA-binding protein (TBP) for expression analysis in RT-qPCR in brain glioma biopsies. The MHC3 microglia cell line was used to evaluate candidate reference genes, and stability was analyzed using statistical algorithms such as BestKeeper, the comparative ΔCT method, geNorm, NormFinder, and RefFinder. Furthermore, a gene expression analysis was performed in brain glioma biopsies from pediatric patients, as knowing the alterations in the expression levels of genes that encode proteins that participate in metabolic pathways can provide potentially important clinical outcome markers or targets for therapeutics in gliomas.Therefore, the aim of this study was to evaluate the suitability of 16 candidate reference genes: hexokinase 1 (HK1), phosphofructokinase muscle (PFKM), triosephosphate isomerase 1 (TPI1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate kinase (PKM), lactate dehydrogenase A (LDHAL6A), glucose-6-phosphate dehydrogenase (G6PD), phosphogluconate dehydrogenase 1 (PGD1), transketolase 1 (TKT1), succinate dehydrogenase B (SDHB), fatty acid synthase (FASN), acetyl CoA carboxylase (ACACA), fatty acid elongase 2 (ELOVL2), and TATA-binding protein (TBP) for expression analysis in RT-qPCR in brain glioma biopsies. The MHC3 microglia cell line was used to evaluate candidate reference genes, and stability was analyzed using statistical algorithms, such as BestKeeper, the comparative ΔCT method, geNorm, NormFinder, and RefFinder. Furthermore, a gene expression analysis was performed in brain glioma biopsies from pediatric patients, since knowing the alterations in the expression levels of genes that encode proteins that participate in metabolic pathways can provide potentially important clinical outcome markers or targets for therapeutics in gliomas.Therefore, the aim of this study was to evaluate the suitability of sixteen candidate reference genes: hexokinase 1 , three of these genes belong to the pentose phosphate pathway (PPP) , one gene participates in the Krebs cycle (SDHB), and finally, three genes are involved in the fatty acid synthesis pathway . Besides, we included three suitable reference genes previously reported as aGAPDH, bGAPDH, and TBP [Reference genes have been identified as those that have functions in essential biological processes including molecular transport, RNA metabolism, oxidative phosphorylation, proteolysis, protein translation, regulation of protein metabolism, and cell cycle control. Based above, sixteen candidate genes encoding enzymes involved in essential metabolic pathways for cell survival such as glycolysis, the pentose phosphate pathway, the Krebs cycle, and fatty acid synthesis  were sel and TBP ,18,19.http://www.ncbi.nlm.nih.gov/geo, accessed on 8 July 2021). This database includes 276 glioma samples from grade 1 to grade 4 as well as 8 controls samples [http://www.ncbi.nlm.nih.gov/geo/geo2r/, accessed on 8 July 2021) [p values and limit the false positives cases, with a cut of p < 0.05. The log2-fold change (logFC) for the analyzed genes is showed in A target screening of our sixteen candidate genes was done using database analysis in silico to reinforce our selection. We searched and selected the GSE16011 glioma database from the Gene Expression Omnibus database (ly 2021)  method tGAPDH and TBP in this analysis and observed a similar tendency that our gene selection. These graphs were obtained using the online software Morpheus .Then, the expression values were displayed in a heatmap . A boxplhttps://www.ncbi.nlm.nih.gov/pmc/, accessed on 11 May 2019). The primers were designed with lengths of 18–22 base pairs (bp) and a mean alignment temperature (Tm) of 60 °C ± 2 °C, and the formation of secondary structures and dimers was verified with the online program OligoEvaluatorTM from Sigma Aldrich . The primers were designed to amplify from 180 to 200 bp fragments corresponding to each gene (w/v) agarose gel electrophoresis, stained with Midori Green Advance , and finally analyzed in the MultiDoc-It (UVP) equipment.The sequences of the primer pairs for the sixteen candidate reference genes used in this study were designed based on the mRNA sequences of the selected genes  obtainedach gene . The pri® CRL-3304™). The HMC3 cells were cultured in Eagle’s Minimum Essential Medium (EMEM) and supplemented with 10% fetal bovine serum  and antibiotics (100 U/mL penicillin and 100 μg/mL streptomycin), according to the manufacturer’s instructions. Cells were grown for 72 h and cultured at 37 °C, 5% CO2, in a humidified atmosphere. The experiments were carried out with cultures in the log phase of growth (before the culture reached the monolayer).A microglia-derived cell line was used in this study to validate the reference genes, thus the HMC3 cell line was purchased from the American Type Culture Collection  in accordance with the Declaration of Helsinki. All the glioma tumors had novo origin and did not receive chemotherapy before surgery. The tumor sample was resected, a portion was preserved for this study, and the other portion was submitted to the pathology service to identify the tumor grade. The characteristics of the pediatric glioma samples are given in w/v) agarose gel electrophoresis. The samples were treated with 1 U of DNase I enzyme . The cDNA was synthesized using oligo (dT) 18 primers (Thermo Fisher Scientific), and RevertAid reverse transcriptase (Thermo Fisher Scientific). The brain glioma biopsies was disrupted using the TissueLyser system  for 60 s at 25 Hz. Total RNA extraction and cDNA synthesis was performed as mentioned above. All the synthesized cDNAs were quantified and stored at −70 °C until use.The total RNA of HMC3 cell line was purified using the TRIzol method , following the manufacturer’s instructions. The quality of RNA was assessed at 260/280 nm and the integrity was evaluated on 2.0%  in the StepOnePlusTM Real-Time PCR Systems platform , which was carried out according to the MIQE guidelines [The amplification of the specific PCR products of the sixteen genes proposed in this study  was deteidelines . The RT-T) values for each reference gene previously obtained from RT-qPCR were analyzed with four statistical algorithms for the evaluation and selection of reference genes: BestKeeper [T method [T method, geNorm, and NormFinder, and calculates the geometric mean (geomean) for each reference gene to give the ranking index of stability [To determine of expression stability of the sixteen candidate genes in this study, the cycle threshold  was analyzed using the 2−ΔΔCt method, employing the PKM reference gene for normalization [We evaluated the expression levels of the selected metabolic gene profile in HMC3 cells and glioma samples using the best reference gene according to the stability value obtained previously. The relative change in the gene expression of the target genes , followed by the PFKM, GAPDH, and ACACA genes, with values between 17 and 23 cycles. Finally, the least-expressed genes were HK1, TPI1, PKM, LDHAL6A, PGD1, TKT1, SDHB, FASN, ELOV2, aGAPDH, bGAPDH, and TBP with CT values between 26 and 34 cycles.The transcriptional levels of the sixteen candidate reference genes were determined using RT-qPCR to compare the levels of mRNA of each gene. As seen in TPI1, GAPDH, PKM, G6PD, TKT1, SDHB, ACACA, aGAPDH, bGAPDH, and TBP. The presence of a single peak in the curves indicates the alignment specificity and thereby confirms that the primers are suitable to be used in amplification reactions to obtain the desired products under the predicted alignment temperature. However, for the genes HK1, PFKM, LDHAL6A, PGD1, FASN, and ELOVL2, we observed more than one peak, apparently due to the dimer primers, so these last genes were not suitable for the analysis of gene expression. The temperature of dissociation (Tm) value for the RT-qPCR products from the genes evaluated was between 75 °C (TBP) and 83 °C (TPI1). With respect to the control without nucleic acid (NTC), no signal was detected, which indicates the absence of contamination.To confirm the specificity of all the primers, melt curves analyses were performed for the sixteen genes. In TPI1, PKM, GAPDH, G6PD, SDHB, TKT1, ACACA, aGAPDH, bGAPDH, and TBP as the final candidate reference genes. Next, we evaluate their expression stability to select the appropriate reference gene to measure the gene expression levels in brain glioma biopsies.Thus, we selected T values and the coefficient variance (CV) for each gene. Genes with SD values > 1 are considered unstable and therefore are not suitable to be used as reference genes [PKM, TPI1, GAPDH, and aGAPDH genes are the best candidates, as they showed less variation according to the calculated deviation (lower dispersion CT), while the TKT1, SDHB, G6PD, ACACA, bGAPDH, and TBP genes had higher dispersion values.To identify the best reference gene, we used as criteria a stable expression and minimum variability in HMC3 cells. Whereby, the expression stability of the ten final candidate reference genes was analyzed with the BestKeeper program. This algorithm calculates the standard deviation (SD) of the Cce genes . The resT method, which compares the relative expression by pairs of genes within each sample to identify the genes suitable for expression studies. The comparation will provide information on which genes show less variability and a more stable expression among the genes analyzed [PKM, TPI1, GAPDH, and aGAPDH genes showed a relatively stable expression. Regarding the analysis with the geNorm program a stability value M for a particular gene; a low value of M indicates a high stability in the expression, the M values calculated for the eleven candidate reference genes are shown in PKM, TPI1, GAPDH, aGAPDH, TKT1 and SDHB genes are the most stable reference genes, with M values of 0.017, 0.017, 0.035, 0.053, 0.768 and 1.446, respectively, while the G6PD, ACACA, bGAPDH, and TBP genes showed M values above 1.5, which is the limit suggested by the geNorm program [PKM, TPI1, GAPDH, aGAPDH, TKT1 and SDHB as among the six most stable reference genes    were intPKM, TPI1, and GAPDH. Therefore, the PKM gene was used as a reference gene to measure the expression levels of genes of metabolic pathways in brain glioma biopsies of pediatric patients diagnosed with different CNS WHO grades of gliomas, because it showed the best stability ranking in the statistical analyses.After validating and selecting the most appropriate reference genes to measure the gene expression levels, we found that the most suitable genes were HK1), phosphofructokinase muscle (PFKM), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), triosephosphate isomerase 1 (TPI1), and lactate dehydrogenase (LDHAL6A). We found that the HK1, PFKM, GAPDH, and LDHAL6A genes were overexpressed in all the clinical samples analyzed compared with the HMC3 microglia cell line . As seen in IDH1 gene was overexpressed in all clinical samples, and the expression level correlates with the grade of the tumor. In CNS WHO grade 3 and 4 tumors, we found a greater overexpression 5 to 155-fold in CNS WHO grade 1 and 2 gliomas and 2305 to 5167-fold in CNS WHO grade 3 and 4 gliomas. With respect to the SDHB gene : PKM > TPI1 > GAPDH > aGAPDH > TKT1 > SDHB > G6PD > ACACA > PGD1 > b > TBPGAPDH . Later, in the validation of the RT-qPCR assays, some of them were found to be unspecific and/or inefficient . This highlights the importance of selecting appropriate reference genes for mRNA quantification by RT-qPCR, because the use of non-validated reference genes can lead to questionable results and errors in data interpretation [The results show that it is not easy to identify a universal reference gene that possesses all the ideal characteristics. In the initial endpoint PCR analysis of the sixteen genes, three genes were not amplified  to continue the glycolytic pathway. However, the glioma cells could obtain G3P from the PPP, and thus, the TPI enzyme expression did not increase  and reduced flavin adenine dinucleotide (FADH2), which are oxidized in the electron transport chain (ETC) to produce adenosine triphosphate (ATP) [IDH1 gene, we found that it is overexpressed in all clinical samples and correlates with the grade of the tumor. In the process of cancer development, the metabolic activity of cancer cells is increased; consequently, an increase in intracellular ROS is observed, related to a wide spectrum of activities [IDH1 gene in CNS WHO grade 3 and 4 gliomas.Besides this, genes that code for Krebs cycle proteins such as te (ATP) . Regarditivities . To prevSDHB gene has been identified as a tumor suppressor, with even alterations in SDH activity leading to succinate accumulation. Various reports have shown that the expression levels of SDH and succinate and fumarate production can be altered in cancer cells [SDHB, meanwhile the samples of CNS WHO grade 2 showed an expression level of 1.7 and 5.7-fold, and CNS WHO grade 3 and 4 samples showed overexpression of 2.6 to 7.47-fold. Besides this, the level of overexpression of the SDHB gene is lower compared with that of the IDH1 gene. The lowest expression of SDHB probably causes a decrease in the amount of SDHB enzyme translated, inducing an altered metabolic phenotype by accumulating succinate and leading to a bioenergetic shift from mitochondrial respiration to cytosolic glycolysis [SDHB in hepatocellular carcinoma cell lines leads to an alteration in energy metabolism and an almost complete loss of mitochondrial membrane potential, as well as a decrease in the expression of Complex III and IV of oxidative phosphorylation, causing an increase in the acidity of the medium, an increase in glucose uptake, and an overexpression of hexokinase 1 (HK1) [HK1 overexpression found in the present work.The SDH enzyme has been classically considered to be a mitochondrial enzyme with the unique characteristic of participating in both the Krebs cycle and ECT. Furthermore, several studies have highlighted the role of succinate in biological processes other than metabolism, with tumorigenesis being the most prominent . For thier cells ,46. Our ycolysis . It has  1 (HK1) , which iFASN gene was overexpressed in CNS WHO grade 3 and 4 glioma samples in the range of 72 to 180-fold. These results agree with a study performed by Tao et al. [FASN were higher in CNS WHO grade 3 and 4 gliomas (62-fold) than in CNS WHO grade 1 and 2 gliomas. The overexpression of FASN has also been reported in different human tumors, such as adenocarcinoma of the prostate, ovarian neoplasm, and thyroid [ACACA and ELOVL2 genes have been analyzed in clinical samples of pediatric gliomas, and a relationship was also found between the level of overexpression and the CNS WHO grade of the glioma, indicating that these genes could also be useful biomarkers in the diagnosis and progression of gliomas.Besides, when we analyzed relevant genes in the fatty acid synthesis pathway, we found that the o et al. , where t thyroid ,51,52,53Finally, although the research objective was to determine the differential expression levels of genes of metabolic pathways, our results should be interpreted with care. They cannot be entirely representative of the different grades of gliomas. Due to the scope of this initial research project, the variation represented in the results is limited according to the number of samples analyzed. This preliminary study involved only seven glioma tumor biopsies, and an increase in sample size being necessary to confirm the relationship between the expression levels of the metabolic genes analyzed and the CNS WHO grade glioma. Furthermore, another limitation of the study is that despite having managed to find and propose two new reference genes for expression studies in Gliomas, we performed the analysis variation of the candidate reference genes studied only in a single cell line.PKM and TPI1 genes could be used as reference genes to normalize and quantify the expression of target genes in pediatric gliomas samples by RT-qPCR. This is the first report on the stability of the expression of the different candidate reference genes that participate in metabolic pathways in gliomas. The analysis of the expression levels of the genes involved in important metabolic pathways for glioma cells revealed that, in order to meet the needs of the highly proliferative cells of gliomas, they undergo metabolic remodeling, which can be summarized as an increase in glucose consumption for a higher production of glycolytic ATP and lactate as the final product, where the overexpression of genes involved in glycolysis such as HK1, PFKM, GAPDH, and LDHAL6A was observed. Besides this, the overexpression of some genes involved in the PPP was also demonstrated , which will probably allow the glioma cells a more significant enzymatic activity in this pathway, thus the cells obtain precursors for nucleotide synthesis and maintaining redox homeostasis. Finally, the Krebs cycle and fatty acid synthesis pathways play central roles in cellular metabolism; we also found that the IDH1, SDHB, FASN, ACACA, and ELOV2 genes were overexpressed, resulting in significant disturbances in the cellular metabolism of gliomas.The results obtained in this study suggest that the


Iron is a critical element for living cells in terrestrial life. Although iron metabolism is strictly controlled in the body, disturbance of iron homeostasis under certain type of condition leads to innate and adaptive immune response. In innate immunity, iron regulates macrophage polarizations, neutrophils recruitment, and NK cells activity. In adaptive immunity, iron had an effect on the activation and differentiation of Th1, Th2, and Th17 and CTL, and antibody response in B cells. In this review, we focused on iron and immune regulation and listed the specific role of iron in macrophage polarization, T-cell activation, and B-cells antibody response. In addition, correlations between iron and several diseases such as cancer and aging degenerative diseases and some therapeutic strategies targeting those diseases are also discussed. Iron is involved in the formation of neutrophil extracellular traps (NETs). Transferrin secreted by human neutrophils promotes tumor metastasis.3. Iron plays a pivotal role not only in the development and proliferation but also in the activation and function of NK cells when virus infection occurred.4. Iron inhibits differentiation and activation of Th1, Th2, Th17, and Treg cells; on the other hand, iron as adjuvant promotes Th1 and Th2 cells immune response. Iron promotes CTL differentiation.5. Targeting iron and immune regulation in cancer offered us new insight into promising therapies.Iron, as a critical trace element, plays a critical role in terrestrial life. Multiple cellular activities such as synthesis of DNA, production of ATP, and respiration of mitochondrion are influenced by iron . As an eClearly, iron is inherently an essential factor in the survival, development, and differentiation of cells, tissues, and organs. However, disruption of iron homeostasis is linked to the disorders of nervous, cardiovascular, and hematological systems . Indeed,Innate immunity acts as the first defense by natural mechanical barriers including skin, mucus, and gastric acid, protecting host from pathogens invasion. Several types of cells like macrophages, neutrophils, and dendritic cells participate in innate immunity. They respond rapidly once pathogens invade and activate inflammatory response immediately, followed by the initiation of adaptive immunity . PathogeMacrophages show three different types of polarizations in response to microenvironment: un-activated M0 (un-activated), M1 , and M2 . M1 macrophages show a proinflammatory phenotype that secretes proinflammatory cytokines like TNF⁃α and IL⁃1β. M2 macrophages secrete TGF⁃β and PDGF. Moreover, M2 macrophages could be classified as several subtypes, namely, M2A, M2b, M2C, and M2d . M1 macrM1 polarization is characterized by the secretion of inflammatory cytokines  and increase in expressions of some iron metabolism proteins like ferroprotin (FPN), transferrin receptor 1 (TfR1), CD163, ferritin, and HO-1, while M2 polarization appears to be with opposite changes in those proteins . Mechani3+/Fe2+ redox state  are expressed in neutrophils, making it possible for neutrophils to uptake or release iron upon stimulations. Iron is an essential element in the functioning of neutrophils . Iron-deox state . In addiox state , 33. Recox state . On the ox state , demonst disease , 36–38.  disease , 36–38.  disease . In some disease .Recently, Vollger et al. indicated that the iron chelator deferoxamine (DFO) promotes the formation of neutrophil extracellular traps (NETs), which are closely related to antibacterial peptides, histones, and proteases in human neutrophils . This suTherefore, the specific role of iron in neutrophil is confusing; whether iron promotes neutrophil production or not, and the underlying mechanisms in iron-induced neutrophil recruitment and inflammation remain to be further explored in the future Table 2.Activation of NK cells usually leads to the elimination of pathogens through releasing of several particles , and the expression of TRAIL or FasL. These ligands serve as death receptor ligands and therefore induce target cell apoptosis. Cytokines such as interferon (IFN)-γ and tumor necrosis factor (TNF) produced by NK cells not only activate immune response but also make NK cells become sensitive to other cytokines  , 43. Act+ CD11b+ NK cells. Moreover, systematic low iron level influenced by hepcidin resulted in the suppression of NK cell activation and production of IFN-γ. Besides, they also showed that sufficient serum iron is critical to the metabolism of NK cells and their activity against virus infection  encoded by TFRC cause combined immunodeficiency . Iron, aDisturbance of iron homeostasis is common in infection, cancer, and autoimmune diseases. Pathophysiology or therapeutic regulation of iron has an impact on the outcome of those diseases .Pathogens grow fast under the condition of free iron in blood and thus promote pathogenicity to the host. Transportation of iron is regulated differently due to the nature of pathogen or the level of iron in cells. A fascinating phenomenon is that iron overload diseases such as thalassemia or primary hemochromatosis often lead to the host more susceptible to infection; in contrast, modest iron deficiency can prevent malaria . A decreOne of the metabolic markers that malignant tumors have is the disorder of iron metabolism due to its high metabolic activity . ROS indCurrently, as a novel anti-cancer strategy, using immunotherapy-induced autoimmune system to find out and destroy tumor has become promising. Hence, understanding the interaction among iron, immune system, and cancer seems to be important. In lung cancer, tumor-associate macrophage (TAM) containing iron has been demonstrated to increase ROS level and secrets proinflammatory cytokines  to kill tumor cells . Indeed,in vitro .The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


The effects of the preparation conditions for the waveguide applied volume holographic gratings (VHGs) were experimentally investigated. The optimum preparation conditions for holographic recording were revealed. After optimization, the peak of VHG diffraction efficiency reached 99%, the diffractive wavelength bandwidth increased from 13 nm to 22 nm, and the corresponding RIM was 0.06. To prove the wide application prospect of the acrylate-based photopolymer in head-mounted augmented reality (AR) displays, green monochromatic volume holographic waveguides were fabricated. The display results showed that the prototype was able to achieve a 28° diagonal FOV and possessed a system luminance of 300 cd/m Volume holographic waveguide is considered to be a potential optical solution for augmented reality (AR) glasses because of its high optical efficiency, low cost, small size and light weight ,2,3,4. TCurrently, there are many kinds of holographic recording materials, including dichromate gelatin, silver salt, photoresist, photopolymer, etc. . Among tTo date, the influences of preparation conditions on the holographic properties of acrylate-based photopolymers have not been systematically studied. Therefore, it is urgent to develop an optimized preparation method for fabricating holographic waveguides with acrylate-based photopolymers for waveguide display.Erythrosin B (EB) is an excellent photosensitizer and is commonly used in photopolymerization initiation systems of photopolymer ,27. In tThe acrylate-based photopolymer consisted of four main components, polyvinyl acetate, N-vinyl carbazole (NVC), tetrahydrofurfuryl acrylate, 2-phenoxyethy acrylate purchased from Wraio, Guangzhou, China, which are the key components for polymerization in the photo-initiation process. -4,4′,5,5′-tetraphenyl-1,2′-biimidazole (BCIM)) purchased from Tronly, Changzhou, China served as the free radical photo-initiator, which is related to the monomers. The dye EB purchased from Sigma-Aldrich, Burlington, MA, USA, is sensitive to green wavelength bands and has an absorption peak at 533 nm. The concentration ratios of the components are listed in After weighing all the components listed above, they were mixed in a glass beaker using a magnetic stirrer at a rate of 1000 r/min for about 1 h, mixing the components thoroughly to form a uniform solution. Then, the dissolved photopolymer solution was coated onto a 1-mm-thick BK7 transparent glass plate using an electric wet film coater . The glass plate coated with the wet photopolymer solution was dried in a dark clean room for several hours to obtain a 12-um-thick photopolymer holographic dry plate. Since all the components were evenly dispersed in the solvent, the photopolymer holographic dry plate samples appeared clear without any impurities under the red safety light.n = 1.52) was used to fill the gap.The holographic setup for the waveguide applied VHGs is shown in The in-coupling and out-coupling VHGs for the holographic waveguide were mirror symmetrical . When thAs shown in in and the transmitted intensity Io of the probe beam were measured using a laser power meter . The diffraction efficiency was calculated asBoth the exposure parameters  and post-treatment parameters  have a significant effect on the performance of holographic optical elements (HOEs) prepared by the photopolymer. Therefore, we analyzed the diffraction efficiency, diffractive wavelength bandwidth, and RIM evolution of waveguide applied VHGs under different combinations of the above-mentioned preparation conditions. The diffraction efficiency plays an important role in describing the holographic performance, which was investigated first. In 0 represents the average refractive index of the volume grating, Δn is the RIM of the holographic recording material, Λ is the grating period, and The diffractive efficiency curve under different wavelengths ranging from 450 nm to 600 nm was obtained using a visible ultraviolet spectrophotometer . On the basis of the designed grating parameters, the measured peak diffraction efficiency and the diffraction efficiency curve, we were able to deduce the RIM of the samples using the rigorous finite element method (FEM) model for the VHGs. The FEM model setup was introduced in our previous work [2, and the dark reaction time, UV curing time, baking time and temperature were 4 min, 3 min, 5 min and 100 °C, respectively. With the increment of exposure dosage, all the peak diffraction efficiencies of samples underwent an obvious promotion, as shown in Firstly, we examined the influences of exposure dosage on the holographic properties of the VHG samples. To compare the holographic performances under different exposure dosages, the photopolymer was illuminated under the same light intensity and prepared under similar post-treatment conditions. The exposure intensity was set at 10 mW/cmThe photo-polymerization reaction mechanism was well demonstrated by the experimental results. At initial exposure, the photosensitizer was continuously consumed, initiating monomer polymerization. The concentration of the photosensitizers and monomers in the bright region decreased continuously, forming a huge concentration difference between bright and dark regions. Due to the concentration gradient, the photosensitizers and monomers in the dark regions form a refractive index modulation, so the diffraction efficiency increased rapidly. With the progress of the reaction and polymerization, concentration differences of components between bright and dark regions decreased gradually, thus slowing down the increase in diffraction efficiency.2, which means that the light sensitivity of acrylate photopolymer is very high. We can also see that the peak diffraction efficiency reached 92%, the maximum diffractive wavelength bandwidth reached around 13 nm, and the corresponding RIM was 0.03.In addition, the exposure dosage that resulted in the peak diffraction efficiency of the VHGs was only 30 mJ/cm2) and post-treatment with different light intensities, as shown in 2 to 8 mW/cm2). However, the peak diffraction efficiency changed significantly when the light intensity was below 1 mW/cm2. In general, photo-polymerization occurs only when the recording light intensity reaches a certain threshold [2), will the material be photoinduced to polymerize. On the other hand, low light intensity means that it is necessary to extend the exposure time, and then the environmental vibration and temperature changes will affect the exposure quite a lot. Additionally, the higher the intensity of the light exposure, the more photons enter the materials within a certain period of time, leading to an increase in the photoinduced reaction rate and mutual diffusion rate between the photosensitizers and the monomers. Therefore, the light intensity also affects the polymerization speed of the photopolymers. After further optimizing the light intensity, the peak diffraction efficiency, diffractive wavelength bandwidth and RIM increased to about 94.4%, 15 nm and 0.035, as shown in Similarly, samples were illuminated under the same exposure dosage  at a baking temperature of 90 °C. 2, the dark reaction time, UV curing time, baking time and temperature were 3 min, 2 min, 5 min and 90 °C). After testing, the diffraction efficiency and diffractive wavelength bandwidth of the waveguide applied VHGs reached 99% and 22 nm, and the corresponding RIM reached 0.06, as shown in On the basis of the above optimization process, we prepared the monochromatic green holographic waveguide using the optimum exposure and post-treatment parameters (the exposure intensity was set as 4 mW/cmOn the basis of the experimental results, it was found that exposure dosage determines the degree of polymerization in the process of holographic recording, leading more monomers with small molecular weight to polymerize into chains. Exposure intensity determines the consumption rate of photosensitizer and polymerization rate of monomers, improving the speed of the VHG formation. By analyzing the effects of the post-treatment process, we found that the excited writing monomers could completely diffuse and polymerize into chains during the dark reaction time. In addition, UV curing irreversibly bleached the residual initiator dyes and cured binders, which helped to fix the formed grating structure. Then, the polymerized monomers needed to be cured by baking, forming a refractive index modulation between the light curing and the thermosetting of the monomers.As shown in 2 and 300 cd/m2, respectively, and were measured using a point luminance meter CS 200, so the optical efficiency of the whole system is about 3%. The diagonal FOV and the eye relief were designed to be 28° and 15 mm. The display results are shown in The luminance of the micro-OLED and the holographic waveguide display module are around 10,000 cd/mTo verify the thermal stability of the prepared holographic waveguide, we baked three samples in an oven at a constant temperature of 60 °C for 2.5 h. The experimental results show that the diffraction efficiency of the VHGs remained almost unchanged, as shown in In this paper, we investigated the optimal conditions of a green light-sensitive acrylate-based photopolymer, and a monochromatic green holographic waveguide was fabricated to verify its potential application in an AR diffractive waveguide.In the optimization research, the influence of the exposure parameters and post-processing conditions on the diffraction performance were investigated. We successfully increased the polymerization speed and degree of photopolymerization by adjusting the exposure intensity, exposure dosage, baking time, and baking temperature.2, a higher diffraction efficiency could not be achieved.We found that, as the exposure dosage increased, the diffraction efficiency quickly increased to 60%, then the increasing speed of diffraction efficiency became slow, although the exposure dosage was continually increasing. On the other hand, we studied the threshold of exposure intensity and found that when the light intensity was lower than 1 mw/cmAdditionally, in the post-processing stage, proper dark-reaction and UV curing were able to effectively improve the holographic performances of VHGs. A dark reaction of 2 min was able to improve the diffraction efficiency significantly. Compared with the other preparation parameters, the UV curing time had no obvious effect on the peak diffraction efficiency. The peak diffraction efficiency increased slowly with the increment of baking temperature, and when the baking temperature was 90 °C, the efficiency reached a maximum of 99.1%. A baking time of 2 min was able to rapidly increase the diffraction efficiency from 39% to 80%, while the corresponding RIM also improved from 0.01 to 0.025. After 2 min, the growth slowed down until reaching its maximum value.2, the corresponding diffractive wavelength bandwidth reached around 22 nm, proving that the acrylate-based photopolymer had a good capacity with wide FOV and high optical efficiency for holographic waveguide display.It was also found that when the diffraction efficiency reached its maximum value of 99%, the diffractive wavelength bandwidth still continuously increased with increasing RIM. When the RIM of VHGs reached 0.06, with an exposure dosage of 30 mJ/cmTo verify the application potential of this material in waveguide displays, we prepared a monochromatic green holographic waveguide and further developed a compact AR display system. A monochromatic green near-eye display with FOV 28° was achieved, and the display results proved that this photopolymer can be regarded as a high-performance holographic recording material that could find wide application in the field of waveguide display.


Miniopterus natalensis; one in two species from the Rhinolophoidea superfamily; and one in four species from the Pteropodidae family. The regions affected by the gene conversions were generally extensive and always encompassed extracellular domains. Overall, we demonstrate that CCR2 and CCR5 have been subject to extensive gene conversion in multiple species of bats. Considering that bats are known to be large reservoirs of virus in nature, these results might indicate that chimeric CCR2-CCR5 genes might grant some bat species a selective advantage against viruses that rely in the extracellular portions of either CCR2 or CCR5 as gateways into the cell.Chemokine receptors are an important determinant for the infectiousness of different pathogens, which are able to target the host cells by binding to the extracellular domains of these proteins. This is the mechanism of infection of HIV-1, among other concerning human diseases. Over the past years, it has been shown that two chemokine receptors, CCR2 and CCR5, have been shaped by events of gene conversion in different mammalian lineages, which has been linked to a possible selective advantage against pathogens. Here, by taking advantage of available bat genomes, we present the first insight of CCR2 and CCR5 evolution within the Chiroptera order. In total, four independent events of recombination between CCR2 and CCR5 were detected: two in a single species,  Chemokine receptors are a family of seven-transmembrane-spanning G proteins important to immunological pathway signaling due to their binding ability with chemokines. They are composed of an extracellular N-terminus, an intracellular C-terminus and seven transmembrane helices TM1-7), which are intercalated by three intracellular ICL1-3) and three extracellular (ECL1-3) loops -7, which,3. Chemo and threOver the past years, it was shown that gene conversion events have shaped two chemokine receptors, CCR2 and CCR5, in several clades of mammals ,17,18,19Bats species (Chiroptera order) have been frequently suggested as the source of outbreaks of multiple human zoonotic diseases, making them useful animal models for the fields of immunology and virology. Some examples of such diseases include rabies, Marburg virus, Ebola virus, Middle East respiratory syndrome coronavirus, and, more recently, severe acute respiratory syndrome coronavirus-2, all of which are believed to have recent ancestry in bat species and to have later been transmitted to humans by virus spillover ,21,22,23https://www.ncbi.nlm.nih.gov/, accessed on 22 December 2021). In one species, Myotis lucifugus, the CCR2 gene was found as a pseudogene and, therefore, it was not included in our dataset. For the remaining species, a single copy of both CCR2 and CCR5 was found. Additionally, Homo sapiens, Macaca mulatta, Canis lupus familiaris and Choloepus didactylus CCR2 and CCR5 genes were included in the dataset as outgroups, resulting in a final dataset of 43 sequences. The sequences were then aligned using the ClustalW2 algorithm [The coding DNA sequences (CDSs) of CCR2 and CCR5 genes from 18 bat species were manually extracted from the NCBI database  phylogenetic tree with the MEGA software ,28 and 1For the detection of recombination events, the sequence alignment dataset was analyzed under six different algorithms  implemented in the Recombination Detection Program (RDP) . To keepMiniopterus natalensis , one containing the remaining CCR5 sequences, and one containing the remaining CCR2 CDSs sequences. The fact that M. natalensis CCR2 and CCR5 genes were clustered together in a separate group indicate that these sequences are more similar to each other than to their respective orthologs, which prompted us to investigate whether gene conversion could explain the phylogeny of the obtained tree.In this study, our main goal was to determine whether the CCR2 and CCR5 genes of bats were affected by gene conversion during their evolutionary history. For that, CCR2 and CCR5 CDSs from 18 different bat species were retrieved from public databases . Bats inTo search for signals of gene conversion in our dataset, we used the RDP software  to analyPteropus alecto, P. vampyrus, P. giganteus, and Rousettus aegyptiacus). The region affected by this recombination included residues 284 to 344 of the CCR2 protein in these species, spanning over part of TM6, ECL3, TM7, and part of the C-terminus (CCR2 gene in Pteropodidae before the radiation of this family (~25 mya) [Rhinolophus ferrumequinum and Hipposideros armiger). This time, the recombinant gene was identified to be CCR5, instead of CCR2. The region involved in this recombination was also considerably more extensive, ranging from residues 66 to 191 and spanning over part of TM1, ICL1, TM2, ECL1, TM3, ICL2, and part of TM4  . Anothert of TM4 B. In thet of TM4 B, the CC in CCR5 . Lastly, ML tree . The fir ML tree C. The se ML tree C. M. natbination , suggestFelis catus) and other lineages of mammals, Vàzquez-Salat et al. [F. catus CCR2 and CCR5 has shown that gene conversion in this species is also not restricted to TMs and ICLs [In a previous study of recombination between the CCR2 and CCR5 in cats (t et al.  have sugt et al. ,32. Howeand ICLs , suggestPlasmodium vivax [Plasmodium vivax interact directly with chemokine receptors in order to infect the cell [Plasmodium vivax infection has been shown to rely on the extracellular portion of another chemokine receptor, DARC [Alternatively, host–pathogen interactions have also been proposed as a factor driving the selection of CCR2-CCR5 recombinants ,16,17. Tum vivax ,9,10,11.the cell . Similaror, DARC . Yet, itBecause bats are known to be reservoirs of viruses in nature, it is tempting to speculate that the gene conversion events between CCR2 and CCR5 observed in this group is due to the existence of viruses that have used these proteins as gateways for infection in the past, driving a selective force that has resulted in the fixation of CCR2-CCR5 chimeric forms. However, no virus with these characteristics has yet been identified in bats. Additionally, it has been shown that gene conversion among clustered, closely related genes is not uncommon in nature, suggesting that the fixation of CCR recombinants might be due to random chance . Therefo


Polymer composites have been identified as the most innovative and selective materials known in the 21st century. Presently, polymer concrete composites (PCC) made from industrial or agricultural waste are becoming more popular as the demand for high-strength concrete for various applications is increasing. Polymer concrete composites not only provide high strength properties but also provide specific characteristics, such as high durability, decreased drying shrinkage, reduced permeability, and chemical or heat resistance. This paper provides a detailed review of the utilization of polymer composites in the construction industry based on the circular economy model. This paper provides an updated and detailed report on the effects of polymer composites in concrete as supplementary cementitious materials and a comprehensive analysis of the existing literature on their utilization and the production of polymer composites. A detailed review of a variety of polymers, their qualities, performance, and classification, and various polymer composite production methods is given to select the best polymer composite materials for specific applications. PCCs have become a promising alternative for the reuse of waste materials due to their exceptional performance. Based on the findings of the studies evaluated, it can be concluded that more research is needed to provide a foundation for a regulatory structure for the acceptance of polymer composites. The growing climate challenges and the scarcity of new natural resources in construction projects have moved the research momentum towards sustainability. The concept of a ‘circular economy’ (CE) has become one of the effective ways of achieving long-term sustainability ,2,3. TheTypical concrete has some drawbacks, such as utilization of natural resources in an excessive quantity, low compressive properties at an early age, and environmental hazards ,14,15. GPolymer concrete is a construction material made from a monomer/aggregate product that has been polymerized. The aggregates are bound together by the polymer matrix monomer, and the produced composite is known as concrete. The idea of polymer concrete started in the late 1950s. These materials were designed to be used as a substitute for cement in specific construction applications. Polymer concrete was first used for construction cladding and other applications. It was widely adopted as a repair material afterward due to its fast cure time, superior bonding properties, ability to reinforce steel, improved strength, and toughness ,25. Poly2 emissions. The accessibility of raw materials, the performance of the system, and the latest synthesis results all support the use of the polymer concrete model for the development of sustainable infrastructure materials. Reports have been published on a variety of curing methods, such as ambient temperature curing, elevated temperature curing, and water curing. The earlier studies have shown that after one day of soaking at room temperature, polymer concrete reaches about 70% to 75% of its strength. Normal concrete normally produces a 20% strength gain after one day of curing [Waste materials from steel industries are also rich in calcium and silica resources, which are important for the production of various calcium silicates and also mineralogical forms of calcium silicate. Rice husk and bagasse are examples of biomass waste that can be turned into ashes, which contain around 80–90% amorphous silica. For polymer concrete applications, this amorphous type of silica can save money. It is a known fact that waste materials such as fly ash from power stations have excellent pozzolanic characteristics and are being replaced by 30% in cement manufacturing. Moreover, fly ash in amounts up to 100% is being used as a building material owing to a process called geo-polymerization. The synergistic strategy to reuse industrial waste will serve as a model for developing building materials that reduce COf curing ,40. In pf curing . Composif curing ,44,45,46Review the potential advantages of polymer concrete composites for the climate, then present a summary of the most important results concerning their mechanical properties, such as compressive, flexural, and splitting tensile strength.Examine the durability performance of polymer-modified concrete under a variety of adverse climatic conditions, and study its structural properties based on research findings.Collect data from earlier studies that used SCMs and industrial byproducts to partially replace conventional concrete for a better comparative analysis of their mechanical properties and then propose rankings that will help with the selection of SCM products for sustainable concrete production.This review study aims to:Agricultural, municipal, and industrial wastes are used as supplementary cementitious materials in making polymer concrete. The physical and chemical properties of the used waste materials were comprehensively studied and analyzed in terms of their pozzolanic properties for potential use in sustainable concrete ,48.50) [Many researchers have investigated the incorporation of the industrial waste (IW)-I product rice husk ash as a cement substitution or as a fine aggregate (sand) in concrete structure projects ,52,53,5450) . Convers50) .2/g in comparison with a RHA particle size of 95 2/g. Another research study reported the highest compressive strength of 51.8 MPa with a RHA particle size of 11.5 Detailed studies have shown that the size of the particle, its specific surface area, the W/C ratio, and the cement substitution level influence the cementitious properties of RHA. Similarly, it was reported that the impact of the specific surface area of RHA quite often overwhelms that of the particle size ,60,61. Gr manner . Compare50, BET SSA, and SiO2. The experiment was performed at a cement replacement rate of 20% RHA and a w/c ratio of 0.5, and higher modification ratios were applied using the abovementioned formulas. The findings show that RHA’s pozzolanic contribution changes with the average particle size, the grinding time, the w/c ratio, the SSA, and the cement substitution dosages of RHA, as displayed in For analysis, the experimental results provided by Zunino and Lopez  were useFurthermore, the optimum pozzolanic output was observed at a 30% substitution level of cement with an average particle size of 14.467 er study . AdditioFor all median-size particles, researchers  measured actions ,62,64,65Moreover, close attention should be paid to the production line and molecular structure together with the other concrete/cement additives used in RHAC to increase RHA’s pozzolanic efficiency in concrete ,66. The 3S  and C2S  differs with the type of cement and the quantity of Jamil et al.  revealedoduction . The stuThe usage of RHA as a SCM in the production of concrete can result in negative effects, such as decreased flowability, a high-water demand, flow blockages, and increased requirements for superplasticizers. A significant reduction in the concrete’s strength at a high level of RHA, low chloride permeability, and the ASR mechanism in alkaline solution are also stated. All such crucial consequences can be minimized by a thorough study of rice husk ash and the RHAC design phase and the use of suitable RHA content in concrete applications.The industrial waste (IW)-II product silica fume (SF) has also been used for numerous construction purposes and utilized as a cement additive and filler material and for curing purposes ,75,76,77The incorporation of the industrial waste (IW)-III product fly ash as a cementitious material in concrete and in different applications has been studied by several researchers ,89,90,91The adverse effects of high-volume fly ash concrete (HVFAC) include increased setting times, low strength at initial stages, project delays, cold weather concreting issues, and low resistance to sodium silicate salt carbonation . To prevThe industrial waste (IW)-IV product ground-granulated blast furnace slag (GGBFS) is used in geopolymer concrete (GPC) and alkaline-activated slag (AAS)-based cement production ,99,100. 2CO3 and H2SO4 are the benefits of using waste glass (WG) [The industrial waste (IW)-V product waste glass (WG) can be used as a SCM or a filler in a variety of applications, including ultra-lightweight fiber-reinforced concrete (ULFRC) and burned bricks ,113,114.ass (WG) ,120. Theass (WG) ,121,122.ass (WG) . ThroughAn activation process is required to avoid a gradual increase in or low strength at initial stages and to intensify the cementing properties of SCMs in the production of green concrete. Among other benefits, it will gain long-term durability at early or later stages . The act2SO4), sodium silicate (Na2SiO3), and acids 2, K2SO4, TiO2, calcium formate) are a few chemical activators that have been reported in prior studies and used in sustainable and green concrete. Chemical activators may be incorporated into a milling process or coupled with temperature-monitored activation to lessen the overall cost of materials [2SO4 addition produced greater strength in comparison with simple activation [To enable the reactivity of the concrete materials, temperature activation tends to refer to temperatures above room temperature. Air and water are common activation channels used during activation driven by temperature. Activation mediated by a SCM requires the utilization of a SCM to intensify pozzolanic effects. Glass particles activated at a high temperature (50 °C) generate pozzolanic actions that also depend upon their composition . The paraterials . For exativation .2 content, less alkali, an unreactive carbon footprint, a good grindability index, a smaller particle diameter, higher strength, and the development of microstructural features [3 by sonication increased the hydration rate, setting period, and compressive strength of SCCs. Intake of colloidal nano-silica achieved a decrease in the initial and final setting times and sometimes increased the CS. Quicklime (CaO) was suggested for high-volume fly-ash-based applications in another study because it provides a significant benefit to both the initial and older-age strength of concrete [Chemical activation has such benefits as a decline in the setting period, strength at early ages, a reduction in material costs, excessive SiOfeatures ,131,132.features ,134. Thefeatures  confirmeconcrete . The intconcrete . Lithiumconcrete .2, and GGBFSS. Bernal et al. [SCM-controlled activation was used to increase the bond strength, limit the setting time, attain initial and final-age strength, and lower the bond strength ,142,143.l et al.  proposedl et al. ,125.2CO3, which was derived from the results in terms of CS. In fly-ash binders, they also found that the SiO2/Na2O ratio and its pH tend to play a key role in cement-based matrix activation and binder strength creation. De Vargas et al. [2/Na2O played an important role in the creation of a geopolymer concrete with FA in terms of improved CS, composition, and microstructure. If the CS concentration rises, the molar concentration rises as well, resulting in longer curing or heat curing times. The inclusion of 5% silica fume to replace the slag in AAS pastes enhanced the compressive strength up to a temperature of 800 °C for SCM-controlled activation [The output of mechanical activation depends upon the activation type used according to a study conducted by Kumar et al. . Their as et al.  found thtivation . Due to tivation .In AAS blends for SCM-controlled activation, adding 5% SF as a substitute for slag increased the compressive strength up to a temperature of 800 °C . BecauseThe polymer concrete production process varies as it depends entirely on the composite materials to be used as well as the target strength. The authors of  proposedThe performance of particle packing by a granular inspection of all structural members is one of the evaluation techniques that can be used in green concrete ,153. OthThe slump test is used to determine how compacted concrete behaves in a cone when subjected to gravitational force. This test is also a measure of the strength of the fresh concrete. Bentz et al.  suggesteConversely, Keertana and Gobhiga  found thThe increased water absorption and high specific surface area of RHA material resulted in a reduction in slump . This coThe amount of time it takes to transport, place, and compact concrete is known as the setting time . It was Based on the shape and quantity of FA used during concrete construction, researchers  found a The strength properties and workability of a RHA-blended concrete mix were improved with the incorporation of up to 30% RHA as a cement replacement according to a study by Ikpong and Okpala . The ini3; sand content, 40%; normal SCM content, 500 kg/m3; UPFA content, between 30% and 40%; and a suitable amount of superplasticizer. Generally, proper consideration should be given to ensure that the SCC is capable of keeping its desired fresh properties, such as flowability, permeability, prevention of segregation, reasonable viscosity, and the ability to flow under its weight by using an aggregate of small size.Fresh properties of SCC produced with ultra-pulverized fly ash (UPFA) have also been examined and should satisfy the following criteria: slump test, 240 to 270 mm; slump flow, 600 to 750 mm; and L-box test, 35 to 80 m/s, as recommended by Xie et al. . When thRHA generated by unregulated burning could be used in new residential building projects according to . ConcretWorkability refers to the ability to handle, place, compact, and finish a concrete mix . The add3, 400 kg/m3, and 450 kg/m3, the flow values were found to be 670–880 mm, 670–740 mm, and 670–780, respectively.Hot weather conditions influence the characteristics of fresh cement pastes and concrete . Similar3 was developed to prevent a rapid initial concrete setting time and a substantial strength reduction [A waste solid within the range 0.37 to 0.41 with a cement content of <400 kg/meduction . The woreduction . The numeduction . It is aeduction . Likewis2, 80 N/mm2, and 79 N/mm2) by incorporating SF, RHA, and SF with nano silica [2 after curing for 28 days. The inclusion of lime in HVFAC and a binder in geopolymers is used to attain their CS efficiently [For a better comparative analysis, the compressive strength (CS) observed in various green concretes by various authors is presented in o silica ,204. SF iciently . Due to iciently ,204. Theiciently . Variousiciently . Likewisiciently . Chindapiciently  documenticiently ,223,224.2 with cement + RHA + Nano A + PPO by the quaternary method. This result is supported by another study that used OPC + 20% of FA + 1.5% of steel fibers + a water-reducing admixture. Later on, they used cement + FA + RHA with the ternary method. Walczak et al. [Many articles on the flexural behavior of green concrete can be found in the literature, as shown in k et al.  observed2O3 (NA). These synergistic interactions also activated the superior properties of the steel fiber mortar. The prestressed steel-fiber-reinforced concrete in beams attained the second highest flexural strength, which showed a similar pattern. This means that the addition of fibers strengthens the energy absorption efficiency of structural members and increases their overall flexural strength. The flexural properties of concrete can be improved by using various fibers, such as reinforced fibers, polypropylene fibers, and nano-Al2O3, as reported in several studies [The highest flexural strength was achieved using a steel fiber mortar made with polypropylene fibers, RHA, and nano-alumina. Polypropylene fibers increased the compressive strength of the mortar paste by creating a bridging effect, increasing the fracture energy and thus the flexural qualities of the mortar. Conversely, the capacity of the concrete matrix to load the fibers was improved by nano-Al studies ,212,213.Authors have reported that shrinkage is increased with increasing brick dust content because brick dust can absorb water . It was The authors of  reportedThe need for pre-wetted LWAs in HVFAC was proposed by Barrett et al.  to triggThe use of quaternary cement mixtures  was suggested by Serdar et al.  to achieBased on research, it has been proven that the addition of fly ash causes a decline in creep because of the increase in the modulus of elasticity, which also leads to a reduction in the volume of the paste in the concrete . For cemTo prevent shrinkage, Yang et al.  proposedMoreover, it was observed that an improved pozzolanic and pore refinement effect produces a significant reduction in the water absorption and void ratio with an increment in the waste glass powder addition . A studyIn addition, when the polymeric percentage of concrete is increased, impact on water absorption and porosity has also been discussed ,251,252,Considering the different curing conditions, the compressive strength of the cement mortars made from different combinations of PC, GGBS and PFA at different curing ages. It shows that with the increase in duration of curing time, the CS increase with the increase of GGBS and PFA content for mortar development  and are The replacement of rice husk ash in concrete improves its resistance to chloride attacks . It was SF shows superior resistance to chloride ion attacks (40% and 14.3% higher than that of RHA). Both were replaced at similar percentages (5% and 10%) with a w/c ratio of 0.6 and tested after 3 days of curing . A decreHPC was prepared with combined mix proportions of 25% RHA and 10% SF . The res2 and alkaline content), the percentage of SCM, the form of the alkali–aggregate interaction, the amount, and the cement’s fineness [Siddique and Bennacer  reportedfineness . SCMs mifineness .2O) < 3 kg/m3 were observed in another study. Their findings were verified in another study that showed that RHA created by controlled incineration had a stronger ASR inhibitory action similar to that of the remaining RHA induced by uncontrolled burning [However, contrary findings on this RHA effect on ASR in concrete have been documented in another study . To cont burning . A reducMoreover, it was observed that SF is more useful for controlling the expansion of ASR in mortar as compared with RHA . A partiectively ,123,268.ectively . FA and ectively . In conc2CO3. The authors also mentioned that the color scheme of the glass had no major effect on the ASR and the thermal stability [Researchers  found thtability . They suThe author of  studied At <300 °C, SF had a significant impact on excess CS. In SFC using 10% SF as a cement substitute, the strength retention was 84.1%, 85.2%, 68.8%, and 26.8% at temperatures of 100, 200, 300, and 400 °C. At 6 percent of cement replacement, the strength quality was higher than the average values of 84.1 percent, 85.2 percent, 68.8 percent, and 26.8 percent . The los2 at a replacement percentage of 70% with OPC at a 400 °C temperature in the development of HVFAC. It was lower in comparison with the 67 N/mm2 and 52 N/mm2 for SF content in stimulated alkali paste as observed by the author under similar temperature conditions [Rashad et al.  observednditions . In addtnditions . At temp2 to 24.9 N/mm2. At the same temperature, control samples showed a 54.7 percent reduction in CS. The disparity in microstructure in both the HSC and control specimens was linked to the degradation of HSC, which incorporates 9 percent SF by weight of cement. A negligible reduction in CS at 100 and 400 °C and a serious decline at 400 °C (approximately between 55 and 80 percent) was reported. The authors of [2 and about an 11 percent decrease in volume under a high temperature of 800 °C in comparison with untreated control specimens. The increase in CS was due to its low water absorption, the availability of a significant amount of void space, and possibly the solid content ratio.At an elevated temperature (800 °C), HSC produced with SF at 15.4 percent and FA with a cement replacement of 38.5 percent showed a significant reduction in CS of 74.4 percent from 97.3 N/mmthors of  confirmethors of  claimed 2SiO3 to KOH was 2.5 and in the case of the FA/activator ratio 2.5 was recommended. Both the polymerization reaction and sintering are responsible for an improvement in the strength of GPs at high temperatures. Another research study [2 in the GP-blended cement paste, melting of the glass fibers, and greater incoherence in the mortar and sand were all linked to a loss of strength.For fire safety and performance improvement in GPC, the FA/activator ratio was found to be the most significant factor. The desired ratio of Nach study  confirmech study  recordedAccording to , incinerWhen GGBS is used as a sand substitute in an alkali-activated slag (AAS) mortar, researchers  demonstrConcrete made of fine glass waste as a sand replacement was given the highest CS in comparison with coarse WGC and WGC containing a mixture of both fine and coarse particles . The bes2SO4, 20% of the cement be replaced by RHA. The acid attack resilience was directly related to the ratio of (SiO2 + Al2O3 + Fe2O3)/CaO. RHA’s increased resistance was also attributed to its dense microstructure, its structural and pozzolanic effects, and the existence of Al2O3. A 25% RHA cement substitution with 0.1H2SO4 resulted in a strength increase [In binary cementitious products, RHA has a higher resistance to a sulfate threat than FA. Despite this, the RHA mortar’s strength improved by 7% after 90 days of immersion in a 5% solution of sodium sulfate and a 20% cement alternative, which compares favorably to 0% for FA  In compaincrease .2, 53.5 N/mm2, 56 N/mm2, and 61.5 N/mm2 to a better Blaine fineness of 3000 cm3/g, 3900 cm3/g, 4800 cm3/g, and 9300 cm3/g, respectively [4) and ferric oxide inside the concrete structure [3A) content has been used [The immunity of FA and SF to several chemicals  has been investigated . The autectively . The opttructure . Chemicaeen used .3S and C2S is attributed to the creation of portlandite, which promotes the penetration of sulfate when extracted and produces spacious ingredients (gypsum and ettringite). Similarly, GGBS outperformed FA in terms of resistance to a MgSO4 attack due to its higher CS2 content [3 or CaSO4 [The chemical susceptibility of GGBS in the presence of lime is determined by its high toxicity, the amount of Ca in the cement matrix, and its dispersion within that sample . GGBS ou content . In conc content . Moreoveor CaSO4 . Compareor CaSO4 . Despiteor CaSO4  claimed or CaSO4 . Glass for CaSO4 .According to Ganjian and Pouya , when ex2 emissions and using substitutes in cement production, can help in polymer-modified concrete. Two institutes of international repute (Heidelberg Cement and RWTH) have developed an ecofriendly concrete concept using olives and basalt. Using carbonized minerals for the development of construction materials will be helpful. Two institutes, Heidelberg Cement and Aachen University-RWTH, are supported by the Potsdam Institute for Advanced Sustainability Studies (IASS) and the Dutch start-up Green Minerals for this research [Materials produced by following an environmentally friendly ideology, such as reducing COresearch . Figure A major challenge in the development of polymer concrete composites is ensuring compliance with regulatory standards. Other challenges include minimum clinker concentrations, the chemical characteristics of cement, the insufficiency of the data available in the literature over the last 20 years, and the diversity of polymer concrete applications. Therefore, more research is required for a better understanding of polymer concrete’s behavior . As a reRegulations and inexpensive technology for the efficient development and manufacturing of polymer concrete and relevant information are needed to support and understand the introduction of new standards and regulations . To raisSimilarly, innovative and economical activators are needed to promote the long-term advancement and production of PCC. Characterization methods that are both cheap and economical are also desired, particularly in developing economies where funding for research and development is limited. Construction firms, academic institutions, and research centers should be paid to pioneer the manufacture and use of polymer concrete composites in their construction projects. Moreover, new research hubs should also be established to support the continued advancement of polymer concrete materials and construction methods. Domestic production techniques should be supported in order to generate low-cost green composite materials and decrease dependency on costly technology. One of the most productive, economical, novel, and sustainable strategies to boost the effectiveness of concrete buildings is to use waste materials as well as alternative composites, e.g., SCMs and coarse aggregates, in polymer concrete production.Polymer concrete composites are made from different types of industrial, municipal, and agricultural wastes. Polymer concrete composites are identical to normal concretes; however, they are made entirely of polymer matrices rather than cement and contain two co-binders, namely mineral cement and a high proportion of polymer. Owing to variations in the development goals, capabilities, and ability levels of the local construction industry, the strategies adopted in each country to promote the use of polymer concrete in buildings will be different. Polymer concrete composites, which incorporate waste products and modern, substitute materials such as SCMs and aggregates, constitute one of the most effective, inexpensive, advanced, and ecofriendly ways to improve the quality of concrete buildings. Polymer concrete composites can be used in large-scale construction projects all over the world. Proper measures and cooperation between building organizations are actively needed to promote the concept of sustainable concrete in construction. Besides this, more demonstration projects, as well as further research and development, are needed to develop environmentally friendly material binders to minimize the need for OPC. For the building industry, polymer concrete is strongly advised due to its natural, technological, and economic advantages.Moreover, future research should focus on the following. Guidelines for the advancement of resources for polymers that endorse industrial waste could be developed for use across the world. Based on the sources of raw material and the mineralogical nature of industrial materials, a precise model framework for polymer concrete could be established. Due to the disproportionate emission of carbon during the cement manufacturing process, the contribution to global warming of cement factories still alarms environmentalists. As a result, supplemental industrial or agricultural wastes can be used as a raw material to minimize energy consumption. Under the circular economy model, industrially focused polymer design parameters could be defined to establish region-specific and raw resource materials.