Tuning the Structural and Optoelectronic Properties of Cs2AgBiBr6 Double-Perovskite Single Crystals through Alkali-Metal Substitution

Lead-free double perovskites have great potential as stable and nontoxic optoelectronic materials. Recently, Cs₂AgBiBr₆ has emerged as a promising material, with suboptimal photon-to-charge carrier conversion efficiency, yet well suited for high-energy photon-detection applications. Here, the optoelectronic and structural properties of pure Cs₂AgBiBr₆ and alkali-metal-substituted (Cs_1−xY_x)₂AgBiBr₆ (Y: Rb⁺, K⁺, Na⁺; x = 0.02) single crystals are investigated. Strikingly, alkali-substitution entails a tunability to the material system in its response to X-rays and structural properties that is most strongly revealed in Rb-substituted compounds whose X-ray sensitivity outperforms other double-perovskite-based devices reported. While the fundamental nature and magnitude of the bandgap remains unchanged, the alkali-substituted materials exhibit a threefold boost in their fundamental carrier recombination lifetime at room temperature. Moreover, an enhanced electron–acoustic phonon scattering is found compared to Cs₂AgBiBr₆. The study thus paves the way for employing cation substitution to tune the properties of double perovskites toward a new material platform for optoelectronics.     

Efficient and stable electrocatalyst for hydrogen evolution reaction prepared by hybrid technique in surface engineering: Electrochemical and magnetron sputtering methods

Developing low-cost, stable, and robust electrocatalysts is significant for high effective hydrogen evolution reaction (HER). In this work, a coating system with Cu₂O/NiMoCu on stainless steel (SS) is employed as a highly active and stable catalyst for HER in acidic solutions. Electrochemical measurements for as-designed system on SS show a low onset overpotential, small Tafel slope of ～32 mV/decade and long-term durability over 7 days of HER operation. To further inspections of electrocatalytic behavior of as-prepared system in HER, the EIS measurements are performed at several overpotentials and temperatures. It is found that high hydrogen evolution activity and stability of Cu₂O/NiMoCu hybrid is likely due to special morphology of Cu₂O which result in large number of active sites for hydrogen adsorption, and a synergetic effect giving electronic structure suitable for the HER.     

Characterisation of spray‐dried microparticles containing iron coated by pectin/resistant starch

Iron is one of three major minerals in human body. However, the iron deficiency is a medical problem in developed and underdeveloped countries due to its poor oral absorption or insufficient iron intake. Encapsulation could solve problems associated with oral iron consumption. Various advantages including low cost, biodegradability, biocompatibility and large‐scale production have been included in the current study. In a modified encapsulation method, iron microparticles were prepared using low methoxy pectin and resistant starch during spray drying. Covalent and hydrogen bonds were formed between iron and pectin and between polymers, respectively. Particles sized 3.5 ± 1.14 μm and showed spherical shapes. The yield of particles was 72.07%, and solubility and loading efficiency were 33.64% ± 0.88 and 34.79%, respectively. In conclusion, using iron as a cross‐linker of pectin molecules resulted in microparticles with appropriate properties of lowering organoleptic changes and a better bioavailability especially in dairy‐based products for food fortification.     

Four Novel p.N385K,p.V36A,c.1033–1034insT and c.1417–1418delCT Mutations in the Sphingomyelin Phosphodiesterase 1 (SMPD1) Gene in Patients with Types A and B Niemann-Pick Disease (NPD)

Background: Types A and B Niemann-Pick disease (NPD) are autosomal-recessive lysosomal storage disorders caused by the deficient activity of acid sphingomyelinase due to mutations in the sphingomyelin phosphodiesterase 1 (SMPD1) gene. Methods: In order to determine the prevalence and distribution of SMPD1 gene mutations, the genomic DNA of 15 unrelated Iranian patients with types A and B NPD was examined using PCR, DNA sequencing and bioinformatics analysis. Results: Of 8 patients with the p.G508R mutation, 5 patients were homozygous, while the other 3 were heterozygous. One patient was heterozygous for both the p.N385K and p.G508R mutations. Another patient was heterozygous for both the p.A487V and p.G508R mutations. Two patients (one homozygous and one heterozygous) showed the p.V36A mutation. One patient was homozygous for the c.1033–1034insT mutation. One patient was homozygous for the c.573delT mutation, and 1 patient was homozygous for the c.1417–1418delCT mutation. Additionally, bioinformatics analysis indicated that two new p.V36A and p.N385K mutations decreased the acid sphingomyelinase (ASM) protein stability, which might be evidence to suggest the pathogenicity of these mutations. Conclusion: with detection of these new mutations, the genotypic spectrum of types A and B NPD is extended, facilitating the definition of disease-related mutations. However, more research is essential to confirm the pathogenic effect of these mutations.     

Techniques,perspectives, and challenges of bioactive peptide generation: A comprehensive systematic review

Due to the digestible refractory and absorbable structures of bioactive peptides (BPs), they could induce notable biological impacts on the living organism. In this regard, the current study was devoted to providing an overview regarding the available methods for BPs generation by the aid of a systematic review conducted on the published articles up to April 2019. In this context, the PubMed and Scopus databases were screened to retrieve the related publications. According to the results, although the characterization of BPs mainly has been performed using enzymatic and microbial in‐vitro methods, they cannot be considered as suitable techniques for further stimulation of digestion in the gastrointestinal tract. Therefore, new approaches for both in‐vivo and in‐silico methods for BPs identification should be developed to overcome the obstacles that belonged to the current methods. The purpose of this review was to compile the recent analytical methods applied for studying various aspects of food‐derived biopeptides, and emphasizing generation at in vitro, in vivo, and in silico.     

A developed single-phase cascaded multilevel inverter with reduced number of circuit devices

In this paper, an advanced configuration for multilevel voltage source inverters is proposed. The proposed topology can be used as symmetric and asymmetric inverter. In asymmetric mode, DC sources’ magnitudes are defined in a way that the number of output voltage levels gets more than the case when the symmetrical DC sources are applied. In this regard, to calculate the magnitudes of required DC voltage sources, several different solutions are proposed. In multilevel inverters, the overall cost, circuit size and so installation area, complexity of control scheme and reliability are directly dependent on the number of circuit devices needed. The provided comparison study among suggested inverter in all defined solutions, CHB and recently proposed converters validates that the proposed modular inverter uses reduced number of circuit devices. The provided simulation and experimental results confirm the feasibility of the proposed structure and show that the obtained results are in good agreements.     

One-pot three-component synthesis of some novel ethyl 3-alkyl-2-thioxo-2,3-dihydrothiazole-4-carboxylates under solvent- and catalyst-free conditions at room temperature

A green and efficient one-pot three-component synthesis of some novel ethyl 3-alkyl-2-thioxo-2,3-dihydrothiazole-4-carboxylates from the reaction of primary alkyl or benzyl amines, carbon disulfide and ethyl bromopyruvate is introduced. This straightforward technique gave the looked-for products in high yields during 1.5–3?h without need for catalyst or solvent assistance.     

Ethanol and chitosan production from wheat hydrolysate by Mucor hiemalis

BACKGROUND: High glucose and ethanol tolerance is among the most important requirements of ethanol‐producing microorganisms. The purpose of this study was evaluation of filamentous fungus Mucor hiemalis for ethanol production from wheat and starch hydrolysates with high glucose concentration. RESULTS: The results showed high tolerance of the fungus in fermentation of the hydrolyzates with high glucose concentrations (as high as 190 g L^?1). Interestingly, increasing the glucose concentration from 15 to 190 g L^?1 was accompanied by enhancement of initial sugar uptake rate. Ethanol was the most important metabolite obtained during all fermentations and its concentration reached over 50 g L^?1. Beside ethanol, chitosan was another valuable product of the process. Glucosamine, a precursor of chitosan, made up 37.3–46.7% of the cell wall of this fungus. CONCLUSIONS: M. hiemalis is a promising microorganism for simultaneous production of ethanol and chitosan from substrates with high sugar concentrations. © 2012 Society of Chemical Industry     

Numerical and Experimental Biomass Separation from Fermentation Process by Minihydrocyclones

Biomass particle separation is challenging in the pharmaceutical industry because of the smallness and lightness of such particles. Centrifugation is applied conventionally for batch separation. However, imposing multiple wash steps in order to eliminate culture residues and the high risk of extrinsic contamination hamper batch techniques. In this research, minihydrocyclones were introduced to provide a better solution for the mentioned limitations in continuous processes. Numerical separation of methylotrophic yeast from fermentation broth was carried out in three hydrocyclones with different lengths, and the most efficient one was examined experimentally. Three various feed flow rates and seven feed concentrations were evaluated. The concentration of biomass suspension in the product was raised to 20 %.