Strain-dependent deformation behavior in nanocrystalline metals

The deformation behavior as a function of applied strain was studied in a nanostructured Ni-Fe alloy using the in situ synchrotron diffraction technique. It was found that the plastic deformation process consists of two stages, undergoing a transition with applied strain. At low strains, the deformation is mainly accommodated at grain boundaries, while at large strains, the dislocation motion becomes probable and eventually dominates. In addition, current results revealed that, at small grain sizes, the 0.2% offset criterion cannot be used to define the macroscopic yield strength any more. The present study also explained the controversial observations in the literature.     

Selective Oxidation of Aryl Ketones to a-Diketones with 4-Aminoperoxybenzoic Acid Supported on Silica Gel in Presence of Air

4-Aminoperoxybenzoic acid supported on silica gel in presence of air was found to be a selective and convenient oxidant for the oxidation of methylene groups in aryl ketones to convert them to -diketones.     

Application of a Sawdust/Fe3O4 and Sawdust/Fe3O4/PEI as a Selective Adsorbent for Pb(II) Removal

Based on the advantages of Fe₃O₄ nanoparticles (MNPs), sawdust (SD), and polyethlenimine (PEI) respectively, the SD/MNPs/PEI composites with layered structure were synthesized. The features of the nanocomposites were characterized and experimental conditions were used to evaluate the potential of SD/ MNPs and SD/MNPs/PEI nanocomposites in removing lead ions Pb2+ in a batch system. By cross-linking PEI on the SD/ MNPs, chelating group on the surface of adsorbent is made, which increases the ability of the nanocomposite to attract Pb(II) from aqueous solutions. Results show an increase in the adsorption by about 31% on SD/MNPs, by about 98% in SD/MNPs/PEI.

     

The kinetic and thermodynamic study of the removal of Cr(VI) ion from aqueous solution by human hair waste

The removal of Cr(VI) ions from aqueous solution by human hair waste is investigated by using UV–Vis spectrophotometer technique. The morphological analysis of the human hair was also investigated by the scanning electron microscopy, Fourier transforms infrared spectroscopy and X-ray photoelectron spectroscopy. The influence of various physicochemical effective parameters such as pH, ionic strength, adsorbent amount, contact time, initial concentration of metal ion on removal of Cr(VI) ions by human hair process was also studied. The optimum conditions for this adsorption process were obtained at pH = 2 and contact time of 150 min while the highest Cr(VI) uptake is recorded for 0.5 g of the adsorbent per 100 ml of solution. Three isotherms models including Langmuir, Freundlich and Temkin were applied to describe the equilibrium data. It was found that the experimental data were well described by Freundlich isothermal model. The maximum adsorption capacity was found to be 11.64 mg g^?1.The thermodynamic study data showed that the adsorption process of Cr(VI) on human hair is an endothermic, spontaneous and physisorption reaction. The kinetics of the adsorption process was studied using three kinetics models including Lagergren-first-order, pseudo-second-order and Elovich model. The obtained data are indicated that the adsorption processes of Cr(VI) over human hair could be described by the pseudo-second-order kinetic model.     

A chiral furocoumarin

The furocoumarin 1,2‐di­hydro‐2‐(1,2‐di­hydroxy­prop‐2‐yl)‐8H‐furo­[2,3‐h]­benzo­pyran‐8‐one crystallizes from methanol–water as the monohydrate C₁₄H₁₄O₅·H₂O. Both chiral centers have the S configuration. Both OH groups and both H atoms of the water mol­ecule form intermolecular hydrogen bonds with O?O distances in the range 2.7686 (18)–2.8717 (18) Å.     

Complete order amenability of the Fourier algebra

We define complete order amenability and first complete order cohomology groups for quantized Banach ordered algebras and show that the vanishing of the latter is equivalent to the operator amenability for the Fourier algebra.     

A class of homogeneous superspaces associated to odd involutions

Periodica Mathematica Hungarica - A new generalization of Grassmannians in supergeometry, called $$nu $$ -Grassmannians, are constructed by gluing $$nu $$ -domains. By a $$nu $$ -domain, we mean...     

Multi‐component reaction‐functionalized chitosan complexed with copper nanoparticles: An efficient catalyst toward A3 coupling and click reactions in water

A novel bio‐nanocomposite nanocatalyst with highly dispersed particles is synthesized through covalent functionalization of chitosan biopolymer by the multicomponent reaction (MCR) strategy. Surface functionalization of chitosan through MCR is led to the grafting of carboxamide type ligands with a high affinity toward complexation with copper nanoparticles. The catalytic activity of the synthesized catalyst was explored in various transformations such as A³ coupling and click reactions in water. Reusability and non‐hazardous nature of the catalyst, mild reaction conditions, operational simplicity, high yielding, and using water as a solvent are the main advantages of this catalytic protocol.     

All‐Nanoporous Hybrid Membranes: Redefining Upper Limits on Molecular Separation Properties

New membrane‐based molecular separation processes are an essential part of the strategy for sustainable chemical production. A large literature on “hybrid” or “mixed‐matrix” membranes exists, in which nanoparticles of a higher‐performance porous material are dispersed in a polymeric matrix to boost performance. We demonstrate that the hybrid membrane concept can be redefined to achieve much higher performance if the membrane matrix and the dispersed phase are both nanoporous crystalline materials, with no polymeric phase. As the first example of such a system, we find that surface‐treated nanoparticles of the zeolite MFI can be incorporated in situ during growth of a polycrystalline membrane of the MOF ZIF‐8. The resulting all‐nanoporous hybrid membrane shows propylene/propane separation characteristics that exceed known upper‐bound performance limits defined for polymers, nanoporous materials, and polymer‐based hybrid membranes. This serves as a starting point for a new generation of chemical separation membranes containing interconnected nanoporous crystalline phases.     

Cobalt Doped Titanium Dioxide Nanoparticles: Synthesis,Characterization and Electrocatalytic Study

In this work, green synthesis of cobalt doped titanium dioxide (Co‐TiO₂) has been carried out in aqueous medium using gelatin. The Co‐TiO₂ particles have been characterized using transmission electron microscopy (TEM), X‐ray diffraction (XRD), energy dispersive X‐ray (EDAX), FT‐IR spectroscopy and voltammetry techniques. XRD results show pure Co‐TiO₂ and TiO₂ powders with average crystallite size about 12 nm and 15 nm, respectively. Co loaded in TiO₂ hasn't influence crystalline structure. Moreover, efficient Co‐TiO₂‐based anode was fabricated by casting of the Co‐TiO₂ solution on glassy carbon electrode (Co‐TiO₂/GCE). The electrocatalysis of oxygen evolution reaction (OER) at Co‐TiO₂/GCE has been examined using linear scanning voltammetry (LSV) in alkaline media. The OER is significantly enhanced at Co‐TiO₂/GCE, as demonstrated by a negative shift in the LSV curve at the Co‐TiO₂/GCE compared to that obtained at the unmodified one. The value of energy saving of oxygen gas at a current density of 5 mA cm^?2 is 12.6 kW h kg^?1. The low cost as well as the marked stability of the modified electrode make it promising candidate in industrial water electrolysis process.