Effect of metal doping on the visible light absorption,electronic structure and mechanical properties of non-toxic metal halide CsGeCl3

Non-toxic metal halide perovskites have become forefront for commercialization of the perovskite solar cells and optoelectronic devices. In the present study, for the first time we show that particular metal doping in CsGeCl₃ halide can considerably enhance the absorbance both in the visible and ultraviolet light energy range. We have carried out DFT based first principles calculations on Mn-doped and Ni-doped CsGeCl₃ halide. We investigate the detailed structural, optical, electronic and mechanical properties of all the doped compositions theoretically. The study of the optical properties shows that the absorption edge of both Ni and Mn-doped CsGeCl₃ is shifted toward the low energy region (red shift) relative to the pristine one. An additional peak is observed for both doped profiles in the visible light energy region. The study of the mechanical properties demonstrates that both the doped samples are mechanically stable and ductile as the pristine CsGeCl₃. The study of the electronic properties shows that the excitation of photoelectrons is easier due to the formation of intermediate states in Mn-doped CsGeCl₃. As a result Mn-doped CsGeCl₃ exhibits higher absorptivity in the visible region than the Ni-doped counterpart. A combinational analysis indicates that CsGe_1−xMn_xCl₃ is the best lead free candidate among the inorganic perovskite materials for solar cell and optoelectronic applications.

We have studied the optical, electronic and mechanical properties of Ni and Mn-doped CsGeCl₃ using DFT calculations.     

Evaluation of residual stress and texture in isotope based Mg11B2 superconductor using neutron diffraction

Magnesium diboride (MgB₂) superconducting wires have demonstrated commercial potential to replace niobium–titanium (NbTi) in terms of comparable critical current density. Its higher critical temperature makes MgB₂ wire suitable for liquid-helium-free operation. We recently reported boron-11 isotope-based low-activation Mg¹¹B₂ superconducting wire with decent critical current density appropriate for low-cost superconducting fusion magnets. In this study, we have mainly focused on the neutron diffraction technique to measure the residual stress in Mg¹¹B₂ superconducting wire for the first time. The residual stress state was given qualitative and quantitative interpretation in terms of micro- and macrostress generation mechanisms based on the isotropic model confirmed by neutron texture measurements. The relationship between the stress/strain state in the wire and the transport critical current density is also discussed. This investigation could pave the way to further enhancement of the critical current density of low-activation Mg¹¹B₂ superconducting wires suitable for next-generation fusion grade magnets.

Magnesium diboride (MgB₂) superconducting wires have demonstrated commercial potential to replace niobium–titanium (NbTi) in terms of comparable critical current density.     

Diversity of carbapenemases in clinical isolates: The emergence of blaVIM-5 in Bangladesh

Global emergence and dissemination of carbapenemases are clinically threatening, notably in countries with endemic bla_NDM. To analyze the extent of carbapenemases in Bangladesh, 71 isolates were collected from 7 different clinical sources: wound swab (n = 38), pus (n = 13), urine (n = 9), blood (n = 4), tracheal aspirate (n = 3), pleural fluid (n = 1) and vaginal swab (n = 3) from Dhaka Medical College Hospital, Bangladesh. Among the isolates, 25 were resistant to at least one of the three carbapenems (imipenem, meropenem and doripenem), including 15 being resistant to all. These resistant isolates were identified as Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, P. hibiscicola, Proteus mirabilis, Providencia stuartii and Citrobacter sedlakii. Carbapenemase detection among these 25 isolates varied in individual phenotypic assays (83% in Modified Hodge Test, 50% in Combined Disk Test for Metallo-β-lactamase prediction) as compared with the genotypes observed (96% prevalence of various carbapenemases including bla_OXA-1,48, bla_NDM-1,5, bla_VIM-2,5). bla_OXA-48 was the most prevalent gene (84%) followed by bla_NDM (72%). Coexistence of multiple gene combination such as bla_NDM+bla_OXA-48+bla_OXA-1 was prevalent (48%). Harborage of bla_VIM-5 (n = 1) was characterized for the first time, while bla_NDM-5 (n = 5) was reported contemporarily with a recent study in Bangladesh. Presence of plasmids (64%) and integron class 1 (100%) signifies the transferable potential of resistant traits. The emergence of such new variants along with the presence of the mobile genetic elements demands strict surveillance and combating strategies.     

Differences in stakeholders’ and end users’ preferences of arsenic mitigation options in Bangladesh

Aim

Arsenic contamination of drinking water is a public health crisis. Since its detection in Bangladesh, the world’s most arsenic-affected country, organizations involved (i.e., stakeholders) have made great efforts by testing wells and installing safe water options. Yet, 20 million Bangladeshi are still at risk. It has been suggested that the discrepancy between stakeholders’ and end users’ preferences of arsenic mitigation options is one reason for the slow progress. Therefore, this study aimed at comparing stakeholders’ and end users’ preferences.

Subjects and methods

Three investigations were conducted in Bangladesh: a series of qualitative interviews with 22 stakeholders and two end user surveys with a total of 1,268 randomly selected households living in six arsenic-affected districts of Bangladesh.

Results

Stakeholders mostly preferred rural piped water supplies and deep tubewells, while their least preferred options were dug wells and arsenic removal filters. End users mostly preferred deep tubewells, well-sharing and rural piped water supplies, while dug wells were least preferred. End users identified several disadvantages of mitigation options, including long distances, great effort to collect water and difficult social situations. They further demonstrated moderate willingness to pay for a rural piped water supply, deep tubewells and pond sand filters, but lower willingness for other options.

Conclusion

Stakeholders’ and end users’ preferences converged for deep tubewells and rural piped water supplies, while well-sharing was preferred by end users, but not by stakeholders. The results suggest installing deep tubewells and rural piped water supplies with greater priority. Furthermore, stakeholders’ preferences to promote well-sharing should be enhanced.     

Rheological Behavior of High-Performance Shotcrete Mixtures Containing Colloidal Silica and Silica Fume Using the Bingham Model

There have been numerous studies on shotcrete based on strength and durability. However, few studies have been conducted on rheological characteristics, which are very important parameters for evaluating the pumpability and shootability of shotcrete. In those studies, silica fume has been generally used as a mineral admixture to simultaneously enhance the strength, durability, pumpability, and shootability of shotcrete. Silica fume is well-known to significantly increase the viscosity of a mixture and to prevent material sliding at the receiving surface when used in shotcrete mixtures. However, the use of silica fume in shotcrete increases the possibility of plastic shrinkage cracking owing to its very high fineness, and further, silica fume increases the cost of manufacturing the shotcrete mixture because of its cost and handling. Colloidal silica is a new material in which nano-silica is dispersed in water, and it could solve the above-mentioned problems. The purpose of this research is to develop high-performance shotcrete with appropriate levels of strength and workability as well as use colloidal silica for normal structures without a tunnel structure. Thereafter, the workability of shotcrete with colloidal silica (2, 3, and 4%) was evaluated with a particle size of 10 nm and silica fume replacement (4 and 7%) of cement. In this study, an air-entraining agent for producing high-performance shotcrete was also used. The rheological properties of fresh shotcrete mixtures were estimated using an ICAR rheometer and the measured rheological parameters such as flow resistance and torque viscosity were correlated with the workability and shootability. More appropriate results will be focusing on the Bingham model properties such that the main focus here is to compare all data using the Bingham model and its performance. The pumpability, shootability, and build-up thickness characteristics were also evaluated for the performance of the shotcrete. This research mainly focuses on the Bingham model for absolute value because it creates an exact linear line in a graphical analysis, which provides more appropriate results for measuring the shotcrete performance rather than ICAR rheometer relative data.     

A review on non-edible oil as a potential feedstock for biodiesel: physicochemical properties and production technologies

There is increasing concern regarding alleviating world energy demand by determining an alternative to petroleum-derived fuels due to the rapid depletion of fossil fuels, rapid population growth, and urbanization. Biodiesel can be utilized as an alternative fuel to petroleum-derived diesel for the combustion engine. At present, edible crops are the primary source of biodiesel production. However, the excessive utilization of these edible crops for large-scale biodiesel production might cause food supply depletion and economic imbalance. Moreover, the utilization of edible oil as a biodiesel feedstock increases biodiesel production costs due to the high price of edible oils. A possible solution to overcome the existing limitations of biodiesel production is to utilize non-edible crops oil as a feedstock. The present study was conducted to determine the possibility and challenges of utilizing non-edible oil as a potential feedstock for biodiesel production. Several aspects related to non-edible oil as a biodiesel feedstock such as overview of biodiesel feedstocks, non-edible oil resources, non-edible oil extraction technology, its physicochemical and fatty acid properties, biodiesel production technologies, advantages and limitation of using non-edible oil as a feedstock for biodiesel production have been reviewed in various recent publications. The finding of the present study reveals that there is a huge opportunity to utilize non-edible oil as a feedstock for biodiesel production.

There is increasing concern regarding alleviating world energy demand by determining an alternative to petroleum-derived fuels due to the rapid depletion of fossil fuels, rapid population growth, and urbanization.     

Newly designed analogues from SARS-CoV inhibitors mimicking the druggable properties against SARS-CoV-2 and its novel variants

The emerging variants of SARS coronavirus-2 (SARS-CoV-2) have been continuously spreading all over the world and have raised global health concerns. The B.1.1.7 (United Kingdom), P.1 (Brazil), B.1.351 (South Africa) and B.1.617 (India) variants, resulting from multiple mutations in the spike glycoprotein (SGp), are resistant to neutralizing antibodies and enable increased transmission. Hence, new drugs might be of great importance against the novel variants of SARS-CoV-2. The SGp and main protease (M^pro) of SARS-CoV-2 are important targets for designing and developing antiviral compounds for new drug discovery. In this study, we selected seventeen phytochemicals and later performed molecular docking to determine the binding interactions of the compounds with the two receptors and calculated several drug-likeliness properties for each compound. Luteolin, myricetin and quercetin demonstrated higher affinity for both the proteins and interacted efficiently. To obtain compounds with better properties, we designed three analogues from these compounds and showed their greater druggable properties compared to the parent compounds. Furthermore, we found that the analogues bind to the residues of both proteins, including the recently identified novel variants of SARS-CoV-2. The binding study was further verified by molecular dynamics (MD) simulation and molecular mechanics/Poisson Boltzmann surface area (MM/PBSA) approaches by assessing the stability of the complexes. MD simulations revealed that Arg457 of SGp and Met49 of M^pro are the most important residues that interacted with the designed inhibitors. Our analysis may provide some breakthroughs to develop new therapeutics to treat the proliferation of SARS-CoV-2 in vitro and in vivo.

Three designed inhibitors with potential inhibition efficacy against the emerging variants of SARS coronavirus-2 (SARS-CoV-2).