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The variations in mechanical properties of geopolymer concrete (GPC) prepared with treated recycled concrete aggregate (RCA) in conjunction with a modified two-stage mixing approach (M-TSMA (sp-ggbs)) have been studied in the present research. Since GPC is prepared using fly ash (FA) and ground granulated blast slag (GGBS) as an alternative to cement, it is sustainable and eco-friendly. Further, FA is partially replaced with silica powder (SP) to evaluate the mechanical properties of GPC. Additionally, RCA is treated with sodium silicate to strengthen the adhered mortar. Moreover, based on experimental results, Bayesian optimization Support Vector Regression (SVR) and Gaussian Process Regression (GPR) models are developed to predict the mechanical strengths of GPC mixtures. Results show that treating RCA with sodium silicate improves RCA's physical and mechanical characteristics. Furthermore, treated RCA and M-TSMA (sp-ggbs) enhance the mechanical strengths of GPC mixes, and these strengths can be accurately predicted using SVR and GPR models. • Examining the impact of silica powder on the properties of fly ash/GGBS-based GPC. • Sodium silicate (45 %, 7 days) enhances RCA's physical and mechanical properties. • Treated RCA and M-TSMA (sp-ggbs) improve the properties of ternary blend GPC. • Bayesian optimization algorithm tunes the hyperparameters of SVR and GPR models. • BOA-SVR and BOA-GPR models accurately predict the mechanical properties of GPC. [ABSTRACT FROM AUTHOR]

[Display omitted] • A modified two-stage mixing approach (M-TSMA sp-ggbs) for RAC is developed. • Fresh and mechanical properties of RAC mixed with M-TSMA sp-ggbs are observed. • Two surface treatment methods i.e., HCl and Na 2 SiO 3 solution are used to treat RCA. • Mechanical properties of RAC containing treated RCA along with M-TSMA sp-ggbs. • SVR model opted to predict the mechanical strength considering experimental result. The present study aims to make the concrete prepared with recycled concrete aggregate (RCA) more sustainable by evaluating workability and mechanical strength, i.e., compressive, flexural, and splitting tensile strength of recycled aggregate concrete (RAC). In the present study, RCA is used as a replacement for natural coarse aggregate, and replacement is done by 20%, 40%, 60%, 80%, and 100%. In the context of making RAC more sustainable, a modified two-stage mixing approach (M-TSMA (sp-ggbs)) is adopted. In this mixing approach, cement is replaced by 10% of silica powder and ground granulated blast slag (GGBS) and mixed with water to prepare a slurry, in which RCA is added in the pre-mixing stage. It is observed that the mechanical properties of concrete are slightly improved. Further, to improve RCA characteristics, RCA treatment is done using two surface treatment solutions, HCl and Na 2 SiO 3 ; (a) RCA is soaked in three different molarities, i.e., 0.5 M, 1 M, and 1.5 M of HCl solution, for 1 and 7 days, and (b) RCA is soaked in 15%, 30%, and 45% concentrations of Na 2 SiO 3 solution for 1 and 7 days. The RCA showing the best characteristics regarding water absorption, impact, and crushing value is considered for preparing the concrete mix. Now, the treated RCA is used to prepare sustainable RAC in conjunction with M-TSMA (sp-ggbs). The experimental results show that the workability of all concrete mixes is within the desired range. Moreover, the mechanical properties are significantly improved by considering RCA treated with 45% concentrations of Na 2 SiO 3 soaked for 7 days at a 60% replacement level along with M-TSMA (sp-ggbs). Further, this article used support vector machine regression (SVR) to predict the compressive, flexural, and splitting tensile strength based on the experimental values and the input variables. The SVR model predicted the compressive, flexural, and splitting tensile strength with 97%, 95%, and 88% accuracy. [ABSTRACT FROM AUTHOR]

In this work the feasibility of a corrosion resistant non-carbon noble metal support for PEMFC cathode catalysts has been investigated and compared with a traditional carbon black support. We developed an antimony doped tin oxide (ATO) material which has reasonable electrical conductivity (0.7 S/cm) and surface area (50 m 2 /g). ATO and carbon black (CB) supported Platinum (Pt) electrocatalysts have been prepared by modifying the well-known polyol process. Electrochemical characterizations of the supported catalysts were done to measure the ECSA via cyclic voltammetry, ORR activity via RDE, Pt corrosion via load cycling, support corrosion via potential cycling and finally the catalysts were processed to MEAs for single cell performance tests. ATO supported catalyst showed improved corrosion resistance properties in 0.5 M H 2 SO 4 in three electrode system. However, lower performance than CB supported catalyst has been found after processing to MEAs for single cell tests at defined operating conditions. Electrochemical Impedance Spectroscopy has also been used as a diagnostic tool to asses MEA performance. [ABSTRACT FROM AUTHOR]

The zoonosis anthrax caused by the bacterium Bacillus anthracis has a broad geographical distribution. Active enzootic areas are typically located away from central and northern Europe where cases of the disease occur only sporadically and in limited numbers. In contrast, a few out of the 64 districts of Bangladesh are hyper-endemic for anthrax and there the disease causes major losses in live-stock. In this study we genotyped eight strains of B. anthracis collected from the districts of Sirajganj and Tangail in 2013. All these strains belonged to canSNP group A.Br.001/002 Sterne differing only in a few of 31 tandem-repeat (MLVA)-markers. Whole genome sequences were obtained from five of these strains and compared with genomic information of B. anthracis strains originating from various geographical locations. Characteristic signatures were detected defining two “Bangladesh” clusters potentially useful for rapid molecular epidemiology. From this data high-resolution PCR assays were developed and subsequently tested on additional isolates from Bangladesh and Central Europe. Remarkably, this comparative genomic analysis focusing on SNP-discovery revealed a close genetic relationship between these strains from Bangladesh and historic strains collected between 1991 and 2008 in The Netherlands and Germany, respectively. Possible explanations for these phylogenetic relationships are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Bangladesh has been severely hit by highly pathogenic avian influenza H5N1 (HPAI-H5N1). However, little is known about the genetic diversity and the evolution of the circulating viruses in Bangladesh. In the present study, we analyzed the hemagglutinin gene of 30 Bangladeshi chicken isolates from 2007 through 2010. We analyzed the polybasic amino acid sequence motif of the cleavage site and amino acid substitution pattern. Phylogenetic history was reconstructed using neighbor-joining and Bayesian time-scaled methods. In addition, we used Mantel correlation tests to analyze the relation between genetic relatedness and spatial and temporal distances. Neighbor-joining phylogeography revealed that virus circulating in Bangladesh from 2007 through 2010 belonged to clade 2.2. The results suggest that clade 2.2 viruses are firmly entrenched and have probably become endemic in Bangladesh. We detected several amino acid substitutions, but they are not indicative of adaptation toward human infection. The Mantel correlation test confirmed significant correlation between genetic distances and temporal distances between the viruses. The Bayesian tree shows that isolates from waves 3 and 4 derived from a subgroup of isolates from the previous waves grouping with a high posterior probability (pp=1.0). This indicates the possibility of formation of local subclades. One surprising finding of spatio-temporal analysis was that genetically identical virus caused independent outbreaks over a distance of more than 200km and within 14 days of each other. This might indicate long distance dispersal through vectors such as migratory birds and vehicles, and challenges the effectiveness of movement restriction around 10km radius of an outbreak. The study indicates possible endemicity of the clade 2.2 HPAI-H5N1 virus in Bangladesh. Furthermore, the formation of a subclade capable of transmission to humans cannot be ruled out. The findings of this study might provide valuable information for future surveillance, prevention and control programme. [Copyright &y& Elsevier]