Comparative studies on the electrocatalytic hydrogen evolution property of Cu2SnS3 and Cu4SnS4 ternary alloys prepared by solvothermal method

The development of non-precious metal based electrocatalysts is essential for Hydrogen Evolution Reaction (HER) from the splitting of water. Recently copper tin sulphide (CTS) has gained attention due to its favourable properties in photovoltaic devices and photocatalysis. In this work, CTS has been explored as an electrocatalyst in HER. Cu₂SnS₃ (CTS (A)) and Cu₄SnS₄ (CTS (B)) are prepared by a simple solvothermal method. From the XRD analysis, tetragonal and orthorhombic phase is confirmed for CTS (A) and CTS (B), respectively. Morphology and composition of the prepared samples has been confirmed by SEM and EDAX analysis. Optical study reveals that the band gap energy is around 1.55 and 1.20 eV for CTS (A) and CTS (B), respectively. From photoluminescence studies, CTS (B) has been observed to have a greater recombination of charge carriers than CTS (A). The prepared materials were tested and compared for its performance as electrocatalysts for HER, where the current density of CTS (A) is higher than that of CTS (B). Furthermore, the calculated Tafel slope was 98 mV/dec and 110 mV/dec for CTS (A) and CTS (B), respectively. On the other hand, CTS (A) and CTS (B) have showed good stability even after 500 cycles in acidic medium.     

Low-cost and biodegradable cellulose/PVP/activated carbon composite membrane for brackish water treatment

A simple fabrication of a biodegradable membrane for use in water purification systems is presented in this work. Sodium carboxymethyl cellulose and PVP are dissolved in water and crosslinked with citric acid. The presence of glycerol has given immense flexibility and mechanical strength to the membrane. The addition of activated charcoal has enhanced its purification and dye adsorption capabilities at room temperature in dark and light conditions. The polymer semiconductor composites are completely soil degradable within a week and the membrane also exhibits good electrical conductivity when compared to the membrane without charcoal. The addition of glycerol has acted as molecular spacer between polymers composite's monomer backbone that allows good electron mobility of 9.9 cm² V⁻¹ s⁻¹. The dye adsorption efficiency of the material with two commonly used toxic textile dyes is found to be 100% for methyl orange and up to 57% for Rhodamine B within 3 h. The material shows good dye adsorption efficiency under dark and light conditions with acidic, neutral, and alkaline pH. Salt rejection was also found to increase from 25.3 to 64.4% with applied voltage. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48746.     

Ruthenium Pincer‐Catalyzed Acylation of Alcohols Using Esters with Liberation of Hydrogen under Neutral Conditions

Acylation of secondary alcohols using non‐activated esters, in particular symmetrical esters (such as ethyl acetate), is achieved under neutral conditions with the liberation of molecular hydrogen. This unprecedented, environmentally benign reaction is homogenously catalyzed by a dearomatized ruthenium pincer PNN complex.     

Optimizing Recursive Information Gathering Plans in EMERAC

In this paper we describe two optimization techniques that are specially tailored for information gathering. The first is a greedy minimization algorithm that minimizes an information gathering plan by removing redundant and overlapping information sources without loss of completeness. We then discuss a set of heuristics that guide the greedy minimization algorithm so as to remove costlier information sources first. In contrast to previous work, our approach can handle recursive query plans that arise commonly in the presence of constrained sources. Second, we present a method for ordering the access to sources to reduce the execution cost. This problem differs significantly from the traditional database query optimization problem as sources on the Internet have a variety of access limitations and the execution cost in information gathering is affected both by network traffic and by the connection setup costs. Furthermore, because of the autonomous and decentralized nature of the Web, very little cost statistics about the sources may be available. In this paper, we propose a heuristic algorithm for ordering source calls that takes these constraints into account. Specifically, our algorithm takes both access costs and traffic costs into account, and is able to operate with very coarse statistics about sources (i.e., without depending on full source statistics). Finally, we will discuss implementation and empirical evaluation of these methods in Emerac, our prototype information gathering system.     

Ruthenium Pincer‐Catalyzed Cross‐Dehydrogenative Coupling of Primary Alcohols with Secondary Alcohols under Neutral Conditions

Cross‐dehydrogenative coupling of primary alcohols with secondary alcohols to obtain mixed esters with the liberation of molecular hydrogen is achieved in high yield and good selectivity under neutral conditions, using a bipyridyl‐based PNN ruthenium(II) pincer catalyst.     

Infiltration and sustenance of viability of cells by amphiphilic biosynthetic biodegradable hydrogels

Amphiphilic biosynthetic hydrogels comprising natural polysaccharide alginate (I) and synthetic polyester polypropylene fumarate (II) units were prepared by crosslinking the copolymer of I and II with calcium ion and vinyl monomers viz, 2-hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA), butyl methacrylate (BMA) and N,N′-methylene bisacrylamide (NMBA). Three fast degradable hydrogels, ALPF-MMA, ALPF-HEMA and ALPF-BMA and one slow degradable hydrogel ALPF-NMBA were prepared. These hydrogels are amphiphilic and able to hold sufficient amount of proteins on their surfaces. All these hydrogels are found to be hemocompatible, cytocompatible and genocompatible. ALPF-NMBA promotes infiltration of L929 fibroblasts and 3D growth of H9c2 cardiomyoblasts and long-term viability.     

Direct Intramolecular Coupling of Primary/Secondary Alcohols with Secondary Alcohols for Macrocyclic Alkenylation Using Ni-Zeolite Catalyst Under Continuous-Flow Conditions

Herein, we report the direct intramolecular coupling of primary and secondary alcohols for the selective synthesis of macrocyclic olefins in the presence of Ni-zeolite catalyst under continuous flow. This reaction proceeds via dehydration of secondary alcohols to alkenes, which subsequently undergo intramolecular dehydrative coupling reaction with a primary alcohol to obtain moderate yields of macrocyclic olefins. This reaction is also effective for the coupling of secondary-secondary alcohols and alkene-alcohols to produce diverse macrocyclic olefin products. This unique approach has various advantages including step-economy, no additives and pre-functionalization required, inexpensive and reusable catalyst, and exemplification with 23 macrocycles in different ring sizes. The continuous flow macrocyclisation afforded higher productivity and space-time yield than the batch reaction conditions.