关键词： Polyurethane   Molecular dynamic   Small angle scattering  

摘要： The influence of gamma irradiation on molecular dynamics, microstructures and mechanical properties of polyurethane (PU) elastomers with polyether (poly(tetramethylene glycol), PTMG) and polyester (poly(butylene adipate), PBA) soft segments has been studied. Dynamical mechanical analysis and broadband dielectric relaxation spectroscopy were used to investigate the molecular dynamics of PU elastomers. Interestingly, the alpha-relaxation exhibited contrasting tendency with irradiation dose for PTMG-PU and PBA-PU, demonstrating that main chain scission took place for PTMG soft segments, but main chain crosslink for PBA soft segments. The results of small-angle scattering technique indicated that the volume fraction of hard microdomains increase rapidly with irradiation dose. The microstructures of PTMG-PU were more susceptible to gamma irradiation compared with PEA-PU. The deterioration of tensile properties was not only related to irradiation damage of soft segments, but also caused by the destruction of the microstructures of hard microdomains. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： E   coli   lanthanum orthoferrite   perovskite   photocatalytic inactivation  

摘要： Lanthanum orthoferrites are a versatile class of catalysts. Here, the photocatalytic bactericidal performance of LaFeO3 (LF) to inactivate pathogenic microorganisms, i.e., Escherichia coli (E. coli), in water under simulated solar irradiation conditions was investigated. Various competing and contributing factors were covered to visualize the reaction medium consisting of E. coli K12 cells, organic sub-fractions formed by cell destruction, and LF surface. LF solar photocatalytic inactivation (SPCI) kinetics revealed the highest inactivation rate in ultrapure water as expected, followed by distilled water (DW), aqueous solution containing anions and cations (WM) and saline solution (SS). Characterization of the released organic matter was achieved by UV-vis and fluorescence spectroscopic techniques as well as organic carbon contents (DOC). Upon SPCI, significant amounts of K+ along with released protein contents were detected expressing cell wall destruction and lysis. Under the specified experimental conditions, in the presence of released intracellular organic and inorganic components via cell lysis, a significant count of E. coli was still present in SS, whereas almost all bacteria were removed in other matrices due to various challenging reasons. Based on the presented data, SPCI of E. coli using LF as a novel photocatalyst was successfully demonstrated as an alternative and promising method for disinfection purposes.

关键词： Triboelectric   Flexible   Self-powered   Nanogenerator  

摘要： The increasing interest in harvesting mechanical energy from day-to-day activities is gaining huge interest among researchers. We have fabricated a triboelectric nanogenerator (TENG) made of aluminum and PDMS film acting as positive and negative triboelectric layers. The layers are arranged in an arc-shaped structure with an air gap of 1 cm between the layers of the device. The PDMS layer is made by blending the polymer solution with the hardener in an appropriate ratio and dried to make the transparent and flexible polymer film. The device shows a maximum electrical response of 110 V and 260 nA voltage and current with the power density of 2.9 mW/m(2) at 100 M omega load resistance. Further, the device has been used for lighting green LEDs and charging commercial capacitors. An Arduino board was connected with LED and buzzer, which was triggered by the TENG device. This shows that with the proper usage of electronic components TENG can be used for self-powered sensors and with IoT applications.

关键词： Ether linkage   Molecular dynamics   Area per lipid   Area compressibility modulus   DPhPC bilayers   Structural stability  

摘要： In addition to its biological importance, DPhPC lipid bilayers are widely used in droplet bilayers, study of integral membrane proteins, drug delivery systems as well as patch-clamp electrophysiology of ion channels, yet their mechanical properties are not fully measured. Herein, we examined the effect of the ether linkage on the mechanical properties of ester- and ether-DPhPC lipid bilayers using all-atom molecular dynamics simulation. The values of area per lipid, thickness, intrinsic lateral pressure profile, order parameter, and elasticity moduli were estimated using various computational frameworks and were compared with available experimental values. Overall, a good agreement was observed between the two. The global properties of the two lipid bilayers are vastly different, with ether bilayer being stiffer, less ordered, and thicker than ester bilayer. Moreover, ether linkage decreased the area per lipid in the ether lipid bilayer. Our computational framework and output demonstrate how ether modification changes the mechano-chemical properties of DPhPC bilayers.

摘要： By using a convergent methodology, a novel series of N-arylated 4-yl-benzamides containing a bi-heterocyclic thiazole-triazole core was synthesized, and the structures of these hybrid molecules, 9a-k, were corroborated through spectral analyses. The in vitro studies of these multifunctional molecules demonstrated their potent carbonic anhydrase inhibition relative to the standard used. The kinetics mechanism was exposed by Lineweaver-Burk plots, which revealed that 9j inhibited carbonic anhydrase non-competitively by forming an enzyme-inhibitor complex. The inhibition constants K-i calculated from Dixon plots for this compound was 1.2 mu M. The computational study was also persuasive with the experimental results, and these molecules disclosed good results of all scoring functions and interactions, which suggested a good binding to carbonic anhydrase. So, it was predicted from the inferred results that these molecules might be considered as promising medicinal scaffolds for various diseases related to the uncontrolled production of this enzyme.

关键词： Strain rate sensitivity   Stress relaxation   Slip   Twinning  

摘要： Strain rate sensitivity and activation volume that dictate the kinetics of plastic deformation along with strain hardening response determine the plastic deformation behaviour of novel high entropy alloys. Although, the deformation behaviour of FCC single-phase Cantor alloy exhibits some similarity to that of conventional FCC solid solutions, the deformation behaviour over a wide range of temperature, strain rate, strain and grain size is unexplored. More importantly, theoretical understanding of solid solution strengthening, stacking fault energy and dislocation activation in 100 percent solute high entropy alloys (HEAs) and their flow kinetics is not yet established. This necessitates development of combined experimental and computational approaches to realise the mechanistic design of new single-phase and multiphase transformative FCC HEAs to achieve optimum combination of strength and ductility in the novel complex concentrated alloys. ? 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

关键词： Asymptotic analysis  

摘要： This paper investigates the influence of the material properties on the deceleration dynamics of a deformable cylinder rolling with slipping on a half-space of the same material. The interaction of the cylinder and the half-space is described by the 2D quasistatic contact problem of viscoelasticity (Goryacheva: J Appl Math Mech 37(5):877-885, 1973;Contact mechanics in tribology. Kluwer, Dordrecht 1998) which includes as limiting cases the absolutely rigid and elastic materials. Full dynamical analysis of the problem including the phase portrait, the dependence of the deceleration distance on the mechanical properties of the contacting bodies and on the friction coefficient is provided. The qualitative features of deceleration are justified by asymptotic analysis.

关键词： SiO2 nanotube   CNT   Poly lactic-co-glycolic acid   DFT   Molecular dynamics   Mechanical properties  

摘要： For the first time in this work, computational investigations using density functional theory (DFT) were employed to figure out the interaction of the Poly lactic-co-glycolic acid (PLGA) monomer with Carbon nanotube (CNT) and SiO2 nanotube (SiO2NT). The DFT method was used to calculate the binding energy between the PLGA monomer and these nanotubes for the most stable configuration. The achieved results demonstrate that PLGA monomer chemisorbed onto the surface of SiO2NT (E-b= -1.11eV). In contrast, the nature of interaction for the CNT (E-b= - 0.27eV) complex is physisorption and the PLGA monomer interacts with CNT through non-covalent interaction. The findings display that the interaction between PLGA and SiO2NT, owing to the smaller equilibrium interval and superior binding energy is more potent than CNT. Furthermore, the electronic properties of the most stable configuration were evaluated by computing the electronic density of state (DOS). Afterward, the mechanical properties of the SiO2NT, PLGA polymer chains, and PLGA/SiO2NT nanocomposite were studied by Molecular Dynamics (MD) simulations. The Universal, Dreiding, and COMPASS force fields were utilized to compute Young's modulus, bulk, and shear moduli of these configurations. The obtained results indicate that the interaction of PLGA with SiO2NT surface rises Young's modulus and shear and bulk moduli of PLGA. As a result, the inclusion of SiO2NT to the PLGA polymer matrix increase PLGA mechanical properties. We have also studied the influence of temperature on the mechanical properties of PLGA nanocomposite. The results revealed that the Young modulus of PLGA nanocomposite reduces by increasing the temperature. The outcomes of the present investigation could be precious for scholars to discover the potential uses of the PLGA nanocomposite in the biomedical field ranging from bone tissue engineering to drug delivery.

关键词： Crystallization   Liquids   Polymerization   Compression   Phase transitions  

摘要： High-pressure tuned polymerization kinetics have been examined to elucidate the (photon-assisted) polymerization mechanism of phenylacetylene (PA, C6H5C CH3) under different stimuli including high-pressure, physical state, and UV radiation effects by using in situ FTIR spectroscopy. The pressure-induced glass-forming and crystalline states of PA are found to be formed at different compression rates. The experimental results suggest that the polymerization is induced in the glass-forming state at a very low pressure in contrast to that in the crystal phase where much higher threshold pressure is required. The measured rate constants were found to strongly depend on the pressure, the physical state, and UV radiation. In particular, the rate constant reduced to different extents either by UV irradiation or upon phase transition. The derived activation volumes from the rate constants allow the direct comparison and elucidation of photoactivation and environmental effects on the polymerization. Finally, the diffusion-controlled 1D polymer growth processes were suggested for the glass-forming state or the crystal state at specific pressures. Overall, the mechanistic insights of this work provide guidance of optimizing the multiplexed reaction conditions for the production of the conducting poly(PA).

关键词： 发电厂   机械动力设备   检修管理  

摘要： 电厂电气设备的检修管理直接关系到电厂设备能否安全稳定运行,也是电厂工作人员的安全保障。随着社会发展和技术进步,传统的电气设备维修技术已不能满足生产需求。因此,需要在原有的技术基础上进行改进和完善,从强化设备维修技术管理层着手,全面提升电气设备的运营效率,节约维修成本,在保证技术水平先进的基础上,实现检修和维护技术的科学化和现代化。