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Temuujin) (Gantulga Lkhagva) Mon, 30 May 2022 12:00:26 +0000 OJS 60 Homolytic B–Cl bond dissociation energies of chloroborane-type molecules <p>This study reports accurate gas-phase homolytic B–Cl bond dissociation energies, obtained using the benchmark-quality W1w thermochemical protocol, for a set of 25 chloroborane-type molecules (known herein as the BCl25BDE dataset). The BDEs of these species differ by as much as 136.5 kJ mol<sup>-1</sup> at 298 K, with (BH<sub>2</sub>)<sub>2</sub>BCl having the lowest BDE (388.5 kJ mol<sup>-1</sup> at 298 K) and (CH<sub>3</sub>)HBCl having the highest (525.1 kJ mol<sup>-1</sup> ). Using the W1w BDEs as reference values, the accuracy of a diverse set of more economical DFT procedures (which may be applied to the study of molecules sufficiently large that the use of benchmark-quality methods such as W1w is rendered computationally prohibitive) have been investigated. As a result of this analysis, the most accurate methods for the computation of B–Cl BDEs are ωB97/A'VQZ (MAD = 3.0 kJ mol<sup>-1</sup> ) and M06/A'VTZ (MAD = 3.2 kJ mol<sup>-1</sup> ). The double-hybrid functional DSD-PBEP86 in conjunction with the A'VQZ basis set (MAD = 4.0 kJ mol<sup>-1</sup> ) was found to give the lowest largest deviation (LD = 6.4 kJ mol-1 ) of any of methods considered in this assessment study.</p> Wen Lu, Robert J. O’Reilly Copyright (c) 2022 Wen Lu, Robert J. O’Reilly Fri, 19 Aug 2022 00:00:00 +0000 Effect of various transition metal ions on mordanting stage of yak wool bleaching process <p style="font-weight: 400;">Yak wool is a smooth, warm, and durable natural protein-structured fiber that could compete with cashmere and other high-end protein-structured fibers on the market. However, it suffers from drawing consumers’ attention due to the lack of color due to the shortfall of the yak wool bleaching technology. Herein, we studied the applicability of various transition metals, i.e., copper (II), cobalt (II), iron (II), and nickel (II) salts, as a mordanting reagent based on their effect on the hydrogen peroxide decomposition reaction and the morphological and mechanical properties of the bleached yak wool with the presence of these transition metal. Our study suggested that the iron (II) ion was the most efficient reagent for the mordant bleaching since it provided less fiber damage, relatively high strength, and elongation to the bleached yak wool with good whiteness, while the Cu (II) was the least favorable agent for the yak wool bleaching process.</p> Dashjargal Arildii, Otgontsetseg Ranaajav, Odonchimeg Genenbat, Amarzaya Bazarvaani, Sarangerel Davaasambuu Copyright (c) 2022 Dashjargal Arildii, Otgontsetseg Ranaajav, Odonchimeg Genenbat, Amarzaya Bazarvaani, Sarangerel Davaasambuu Wed, 26 Oct 2022 00:00:00 +0000 A quantum chemical study of the interaction of carboxylic acids with DMSO <p>Quantum chemical computational methods, which use quantum mechanics and molecular dynamics theory, have developed rapidly in the past few decades, and quantum chemical computation has penetrated almost all fields of chemistry. Hydrogen bonds are ubiquitously common weak intermolecular interactions. Moreover, the bonding mechanism of hydrogen bonds is considered to be different from that of chemical bonding. Because of the difficulty of experimental studies, a more accurate calculation of hydrogen bonding from theory is a more convenient and direct method to understand hydrogen bonding. Density functional theory (DFT) is the most widely used general function in quantum chemical calculations, giving accurate results for most chemical systems. In this paper, the geometries of the hydrogen-bonded dimer complex of acetic acid and DMSO was structurally optimized and potential energy surface was determined. The geometries of four related hydrogen-bonded dimer complexes were fully optimized using the M06-2X/6-311++G (3d, 2p) exchange-correlation functional with DFT-D3(BJ) empirical dispersion correction. We found that hydrogen bonding is a mixture of electrostatic interactions and covalent bonding, and that hydrogen bonding is a kind of force with different percentages of electrostatic and covalent character, rather than a special force independent of chemical bonding. Thus, more clearly defining our inherent classification of forces between substances provides a new perspective for our future study of weak interactions such as hydrogen bonding.</p> Mu Ren, Ao Rigele, Na Shun, Narantsogt Natsagdorj Copyright (c) 2022 Mu Ren, Ao Rigele, Na Shun, Narantsogt Natsagdorj Fri, 27 May 2022 00:00:00 +0000 Efficiency of KOH-activated carbon for removal of heavy metal pollution from water <p>The study to reduce heavy metals pollution from water using the KOH-activated carbon was studied the factors affecting the adsorption capacities of Cu(II) and Pb(II), in particular, initial metals concentration, pH of the solution, and contact time in static conditions. Using X-ray photoelectron spectroscopy and FTIR analysis to determine the elemental composition and surface functional groups of the activated carbon surface, the presence of oxygen-related functional groups was observed. The maximum adsorption capacities were 135.8 mg g<sup>-1</sup> and 31.0 mg g<sup>-1</sup> for removal of lead and copper solutions with the initial concentration of 300 mg L<sup>-1</sup> of metal at 318 K, respectively. The removal percentage was found to be higher for Pb (II) when compared with Cu (II).</p> Narandalai Byamba-Ochir, Nazgul Muratbyek, Narangarav Tumen-Ulzii, Ariunaa Alyeksandr, Nasantogtokh Oyunchimeg Copyright (c) 2022 Narandalai Byamba-Ochir, Nazgul Muratbyek, Narangarav Tumen-Ulzii, Ariunaa Alyeksandr, Nasantogtokh Oyunchimeg Fri, 27 May 2022 00:00:00 +0000 Development technology of starter cultures using lactic acid bacteria isolated from fermented Camel milk with cholesterol lowering ability <p>The aim of the study is to develop a technology of starter cultures for fermented milk using new strains of lactic acid bacteria isolated from Mongolian traditional fermented camel milk. “<em>Khoormog</em>” samples are collected from Inner Mongolia, China. Totally 230 <em>Lactobacillus </em>strains are isolated and screened by acid-, bile- tolerance, lactose decomposition and acid production ability. The cholesterol lowering abilities and adhesiveness on Caco-2 are evaluated. The top 2 strains are identified as <em>Lactobacillus</em><em> plantarum</em>. These 2 strains are prepared as the starter cultures in milk fermentation. The development technology of starter cultures is studied.</p> Sarengaole, Tsend-Ayush Chuluunbat, Bayinjirigala, Menghebilige Copyright (c) 2022 Sarengaole, Tsend-Ayush Chuluunbat, Bayinjirigala, Menghebilige Mon, 30 May 2022 00:00:00 +0000