60 research outputs found

    Computational Polyethylene-Ceramic Composite Plate Design and Optimization

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    A composite designed Ultra High Molecular Weight Polyethylene (UHMWPE) reinforced by a material with a failure mode that will strengthen the system may significantly improve on modern armor designs. UHMWPE is considerably less dense than steel or high density ceramics. It is reasonable to consider making improvements to the weight-performance of armor by using the lower density UHMWPE and combining it with inserts of a high-density ceramic. A cellular ceramic encapsulated by rubber may significantly increase the amount of kinetic energy a composite will absorb through a phase transition. It is theorized that a series of ceramic inserts distributed in a polymer matrix will result in an increased impact resistance. Shock propagation in the ceramic will be minimal, and the elastomeric properties of the polymer will provide maximum tensile support. The ceramic inserts will act as a stress concentrator and physical resistor to the impacting object. When the ceramic inserts are shattered by the impactor they will impart a resistive force by forcing additional deformation in the polymer matrix. Study of design variations by examination of multiple geometries for the ceramic inserts will maximize the impact resistance of the structure. The resistance of the structure is enhanced by providing a multi-dimensional failure mode. The ceramic, once shattered, will still occupy space, forcing additional plastic deformation, and additional deformation in the impactor

    Epidemiology of West Nile Virus in the Eastern Mediterranean region: A systematic review

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    Background: West Nile Virus (WNV), a member of the genus Flavivirus, is one of the most widely distributed arboviruses in the world. Despite some evidence for circulation of WNV in countries summarized by the World Health Organization as the Eastern Mediterrian Region Office (EMRO), comprehensive knowledge about its epidemiology remains largely unknown. This study aims to provide a concise review of the published literature on WNV infections in the Eastern Mediterranean regional office of WHO (EMRO). Methodology/principal findings: A systematic review of WNV prevalence studies on humans, animals and vectors in the EMRO region was performed by searching: Web of Science, Science Direct, Scopus, PubMed, Embase and Google Scholar. Finally, 77 citations were included, comprising 35 seroprevalence studies on general population (24460 individuals), 15 prevalence studies among patients (3439 individuals), 22 seroprevalence studies among animals (10309 animals), and 9 studies on vectors (184242 vector species). Of the 22 countries in this region, five had no data on WNV infection among different populations. These countries include Kuwait, Bahrain, Oman, Syria and Somalia. On the other hand, among countries with available data, WNV-specific antibodies were detected in the general population of all investigated countries including Djibouti (0.3-60), Egypt (1-61), Iran (0-30), Iraq (11.6-15.1), Jordan (8), Lebanon (0.5-1), Libya (2.3), Morocco (0-18.8), Pakistan (0.6-65.0), Sudan (2.2-47), and Tunisia (4.3-31.1). WNV RNA were also detected in patient populations of Iran (1.2), Pakistan (33.3), and Tunisia (5.3 -15.9). WNV-specific antibodies were also detected in a wide range of animal species. The highest seropositivity rate was observed among equids (100 in Morocco) and dogs (96 in Morocco). The highest seroprevalence among birds was seen in Tunisia (23). In addition, WNV infection was detected in mosquitoes (Culex, and Aedes) and ticks (Argas reflexus hermanni). The primary vector of WNV (Culex pipiens s.l.) was detected in Djibouti, Egypt, Iran and Tunisia, and in mosquitoes of all these countries, WNV was demonstrated. Conclusions: This first systematic regional assessment of WNV prevalence provides evidence to support the circulation of WNV in the EMRO region as nearly all studies showed evidence of WNV infection in human as well as animal/vector populations. These findings highlight the need for continued prevention and control strategies and the collection of epidemiologic data for WNV epidemic status, especially in countries that lack reliable surveillance systems. © 2019 Eybpoosh et al

    Closed-Loop Recycling of Copper from Waste Printed Circuit Boards Using Bioleaching and Electrowinning Processes

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    International audienceIn the present study, a model of closed-loop recycling of copper from PCBs is demonstrated, which involves the sequential application of bioleaching and electrowinning to selectively extract copper. This approach is proposed as part of the solution to resolve the challenging ever-increasing accumulation of electronic waste, e-waste, in the environment. This work is targeting copper, the most abundant metal in e-waste that represents up to 20% by weight of printed circuit boards (PCBs). In the first stage, bioleaching was tested for different pulp densities (0.25–1.00% w/v) and successfully used to extract multiple metals from PCBs using the acidophilic bacterium, Acidithiobacillus ferrooxidans. In the second stage, the method focused on the recovery of copper from the bioleachate by electrowinning. Metallic copper foils were formed, and the results demonstrated that 75.8% of copper available in PCBs had been recovered as a high quality copper foil, with 99 + % purity, as determined by energy dispersive X-ray analysis and Inductively-Coupled Plasma Optical Emission Spectrometry. This model of copper extraction, combining bioleaching and electrowinning, demonstrates a closed-loop method of recycling that illustrates the application of bioleaching in the circular economy. The copper foils have the potential to be reused, to form new, high value copper clad laminate for the production of complex printed circuit boards for the electronics manufacturing industry. Graphic Abstract: [Figure not available: see fulltext.] © 2020, The Author(s)

    Evaluation of metabolomics profiles of grain from maize hybrids derived from near-isogenic GM positive and negative segregant inbreds demonstrates that observed differences cannot be attributed unequivocally to the GM trait

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    Introduction: Past studies on plant metabolomes have highlighted the influence of growing environments and varietal differences in variation of levels of metabolites yet there remains continued interest in evaluating the effect of genetic modification (GM). Objectives: Here we test the hypothesis that metabolomics differences in grain from maize hybrids derived from a series of GM (NK603, herbicide tolerance) inbreds and corresponding negative segregants can arise from residual genetic variation associated with backcrossing and that the effect of insertion of the GM trait is negligible. Methods: Four NK603-positive and negative segregant inbred males were crossed with two different females (testers). The resultant hybrids, as well as conventional comparator hybrids, were then grown at three replicated field sites in Illinois, Minnesota, and Nebraska during the 2013 season. Metabolomics data acquisition using gas chromatography–time of flight-mass spectrometry (GC–TOF-MS) allowed the measurement of 367 unique metabolite features in harvested grain, of which 153 were identified with small molecule standards. Multivariate analyses of these data included multi-block principal component analysis and ANOVA-simultaneous component analysis. Univariate analyses of all 153 identified metabolites was conducted based on significance testing (α = 0.05), effect size evaluation (assessing magnitudes of differences), and variance component analysis. Results: Results demonstrated that the largest effects on metabolomic variation were associated with different growing locations and the female tester. They further demonstrated that differences observed between GM and non-GM comparators, even in stringent tests utilizing near-isogenic positive and negative segregants, can simply reflect minor genomic differences associated with conventional back-crossing practices. Conclusion: The effect of GM on metabolomics variation was determined to be negligible and supports that there is no scientific rationale for prioritizing GM as a source of variation.</p

    Product yields from the slow pyrolysis process of poultry litter

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    Thermochemical conversion provides an economical and environmentally sound route to dispose animal waste. This conversion process is particularly attractive for the disposal of poultry litter, allowing both biomass valorisation for energy production and safe disposal of the waste material. In the present study, different experimental and analytical techniques were used to investigate the slow pyrolysis process of poultry litter. Experimental runs to simulate a slow pyrolysis process were performed in a fixed bed reactor at constant temperature (400-800 \ub0C) under nitrogen flow. Products obtained were investigated both quantitatively and qualitatively using analytical methods. On-line FTIR techniques showed that the most significant compounds in the produced gas are carbon dioxide, carbon monoxide and methane. Elemental analysis revealed the elemental composition of poultry litter and of pyrolysis products, which contain significant amount of nitrogen and sulphur. The fate of these elements during the pyrolysis process was clarified. GC-MS results uncovered the compounds present in the bio-oil and help to investigate bio-oil potential use as a biofuel. Altogether, this study allows a better understanding of the slow pyrolysis behaviour and its potential in waste-to-energy applications

    Experimental and modeling study of the heat of biomass pyrolysis

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    The present study investigated the thermal effects in the pyrolysis conversion process of four energy crops, focusing on the influence of the experimental conditions on the heat of pyrolysis. The heat of pyrolysis and the residual char yield were measured by the integrated use of thermogravimetric analysis and differential scanning calorimetry, also taking advantage of a pressurized DSC cell. The explored parameters evidenced a significant influence on the heat of pyrolysis and on char yields. An increase of the operative pressure, as well as an increase in the initial weight of the sample, as well as the presence of a lid on the crucible, all resulted in higher char yields and in lower heat demands. These results confirm the presence of a competitive mechanism between the endothermic reactions of the primary decomposition process, leading to volatile formation, and the exothermic vapour-solid interactions, leading to secondary char formation. These findings can be interpreted considering that experimental conditions limiting mass transfer provide a higher residence time of the volatiles products from primary thermal degradation reactions. These primary volatiles react with the pyrolysis products, resulting in exothermic reactions with the formation of secondary char. The heterogeneous secondary reactions lead to carbon enrichment of the final residue

    Promoter region -318 C/T and -1661 A/G CTLA-4 single nucleotide polymorphisms and type 1 diabetes in North Indians

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    Single nucleotide polymorphisms (SNPs) of the CTLA-4 gene have been associated with manifestation of type 1 diabetes in several populations. We assessed the association of five SNPs present in the CTLA-4 gene [-318C/T, -1661A/G and -1722C/T in the promoter region, +49A/G in exon 1 and CT60 in the 3' untranslated region (UTR) region] with type 1 diabetes in North Indian subjects. Genotyping was performed in the patients (n = 130) and the healthy control (n = 180) subjects by polymerase chain reaction-fragment length polymorphism analysis using MseI, BbvI, BstEII and NcoI restriction endonucleases for the -318, -1661, -1722, +49 and CT60 SNPs, respectively. The frequency of G alleles at -1661 locus was significantly higher in the patient group compared with the control subjects. Although the frequency of T alleles at -318 SNP was significantly higher in patients with type 1 diabetes compared with the controls, it did not remain significant after Bonferroni correction for the number of alleles tested. The frequencies of C/T alleles and genotypes at -1722C/T and G allele at +49A/G and CT60 SNPs were not significantly different between the patient and the control groups. Of the various possible haplotypes constructed using the five genetic loci tested (-318, -1661, -1722, +49, CT60), the frequency of 'TGTAG' haplotype was significantly higher in the patients when compared with the controls. The results of the present study indicate that the presence of G allele at -1661 locus at the CTLA-4 gene (IDDM12 locus) is associated with increased susceptibility to type 1 diabetes in North Indians, whereas A allele is protective
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