Preliminary Structural Data Revealed That the SARS-CoV-2 B.1.617 Variant's RBD Binds to ACE2 Receptor Stronger Than the Wild Type to Enhance the Infectivity

The evolution of new SARS-CoV-2 variants around the globe has made the COVID-19 pandemic more worrisome, further pressuring the health care system and immunity. Novel variations that are unique to the receptor-binding motif (RBM) of the receptor-binding domain (RBD) spike glycoprotein, i. e. L452R-E484Q, may play a different role in the B.1.617 (also known as G/452R.V3) variant's pathogenicity and better survival compared to the wild type. Therefore, a thorough analysis is needed to understand the impact of these mutations on binding with host receptor (RBD) and to guide new therapeutics development. In this study, we used structural and biomolecular simulation techniques to explore the impact of specific mutations (L452R-E484Q) in the B.1.617 variant on the binding of RBD to the host receptor ACE2. Our analysis revealed that the B.1.617 variant possesses different dynamic behaviours by altering dynamic-stability, residual flexibility and structural compactness. Moreover, the new variant had altered the bonding network and structural-dynamics properties significantly. MM/GBSA technique was used, which further established the binding differences between the wild type and B.1.617 variant. In conclusion, this study provides a strong impetus to develop novel drugs against the new SARS-CoV-2 variants.     

全透明高压反应釜甲烷水合物动力学实验

水合物的生长和分解规律对开发海洋天然气水合物资源，实现深水天然气水合物气液固多相管道输送都具有重要意义。为了进一步揭示水合物的生长和分解特性，本文采用高压全透明反应釜装置，进行了温度0～30℃、压力3.35～8.16MPa和搅拌速率200～1000r/min范围内的16组甲烷水合物生长和分解动力学实验研究。结果表明：实验过程可分为水合物诱导期、快速生长期、缓慢生长期以及分解期这4个阶段。在水合物快速生长阶段，获得了温度、压力、搅拌电机扭矩和水合物生长速率随时间的变化规律，观察到了水合物颗粒的均相和非均相分布状态。通过加热促使水合物分解，揭示了分解阶段温度、压力和分解速率等关键参数的变化规律以及水合物块的分解形态。分析表明，水合物颗粒的分布状态与水合物浆液的流动性直接相关；水合物块的静态分解过程受到分解气传质控制。     

高温氢工质热物理性质计算分析

氢工质在新能源与动力、航天推进、化工材料等领域有着广泛应用。通过开展高温氢工质热力学与输运性质研究，建立了原子态氢、分子态氢、热解平衡态氢的热物理性质计算模型，开发了热物性计算程序Prop_H_H2，适用范围为温度100~3 500 K、压力104~5×107 Pa 。验证表明，Prop_H_H2在适用范围内计算氢工质的物性参数合理可靠，在温度200~3 000 K、压力104~107 Pa范围内，程序预测值更加准确，相对偏差在±5%左右。本研究可为氢工质相关的航天推进、应用物理学、能源动力等行业的科研和应用提供支持借鉴。     

High-pressure hydrogen storage performances of ZrFe2 based alloys with Mn,Ti, and V addition

The microstructure of ZrFe₂-based alloys were modified by alloying with the Mn, Ti, and V, aiming to obtain proper hydriding/dehydriding plateau features for the high-pressure application. The multi-component ZrFe₂-based alloys show a wide tunable range in the plateau pressure via the interaction of Ti, Mn, and V. Further, the V addition plays the best role to improve the hysteresis in absorption-desorption isotherms, while the proper addition amount Ti helps to realize a low plateau slope as well as a high plateau pressure. Among the investigated alloys, Zr_1.05Fe_1.6Mn_0.4 shows a relatively high dehydriding pressure of 20.58 atm at 298 K, while Zr_1.05Fe_1.7Mn_0.2V_0.1 with C15 structure shows the lowest hysteresis. Overall, too much of Ti and Mn would promote the transformation of the C15 to C14 structure with large hysteresis and low plateau pressure.     

Suppressing Ion Migration across Perovskite Grain Boundaries by Polymer Additives

Passivation of organometal halide perovskites with polar molecules has been recently demonstrated to improve the photovoltaic device efficiency and stability. However, the mechanism is still elusive. Here, it is found that both polymers with large and small dipole moment of 3.7 D and 0.6 D have negligible defect passivation effect on the MAPbI₃ perovskite films as evidenced by photothermal deflection spectroscopy. The photovoltaic devices with and without the polymer additives also have comparable power conversion efficiencies around 19%. However, devices with the additives have noticeable improvement in stability under continuous light irradiation. It is found that although the initial mobile ion concentrations are comparable in both devices with and without the additives, the additives can strongly suppress the ion migration during the device operation. This contributes to the significantly enhanced electrical-field stress tolerance of the perovskite solar cells (PVSCs). The PVSCs with polymer additives can operate up to −2 V reverse voltage bias which is much larger than the breakdown voltage of −0.5 V that has been commonly observed. This study provides insight into the role of additives in perovskites and the corresponding device degradation mechanism.     

氢气在硫化钼分子簇上解离的DFT研究

A DFT study of H2 dissociation on a series of Mo x S y clusters was performed, including homolytic and heterolytic dissociation. The preference for the two pathways on these models show much difference, as the Mo coordination number increases, the homolytic dissociation becomes easier, whereas the heterolytic dissociation becomes more difficult. Furthermore, frontier orbital theory was used to analyze the dissociation mechanisms of these two pathways. It was found that the symmetry and energy gap of Mo x S y’s HOMO and H2’s LUMO are the decisive factors in H2 activation.     

溶剂法制备天然橡胶结合胶的研究

结合胶是未硫化的混炼胶中不能被其良溶剂溶解的那部分橡胶。用化学溶剂法制备结合胶具有药品用量小、实验过程操作简单,重现性好等优点。通过讨论橡胶加入量、炭黑用量、反应时间、静置时间等因素,确定了溶剂法制备结合胶的最佳工艺参数,并与混炼法制备的结合胶进行了性能对比。结果表明,橡胶在甲苯溶液中的质量浓度约为0.02g/mL、橡胶和炭黑的质量比为2∶1、反应时间为14h、静置时间为72h的工艺参数下,可以制得高质量结合胶。混炼法制备的结合胶的质量比溶剂法制备的结合胶的质量大。但是其具有与溶剂法结合胶相同的抽提温度曲线,在结合胶的实验研究中,可以用溶剂法代替混炼法。     

A density functional theory study of methane activation on MgO supported Ni9M1 cluster: role of M on C–H activation

Methane activation is a pivotal step in the application of natural gas converting into high-value added chemicals via methane steam/dry reforming reactions. Ni element was found to be the most widely used catalyst. In present work, methane activation on MgO supported Ni–M (M = Fe, Co, Cu, Pd, Pt) cluster was explored through detailed density functional theory calculations, compared to pure Ni cluster. CH₄ adsorption on Cu promoted Ni cluster requires overcoming an energy of 0.07 eV, indicating that it is slightly endothermic and unfavored to occur, while the adsorption energies of other promoters M (M = Fe, Co, Pd and Pt) are all higher than that of pure Ni cluster. The role of M on the first C–H bond cleavage of CH₄ was investigated. Doping elements of the same period in Ni cluster, such as Fe, Co and Cu, for C–H bond activation follows the trend of the decrease of metal atom radius. As a result, Ni–Fe shows the best ability for C–H bond cleavage. In addition, doping the elements of the same family, like Pd and Pt, for CH₄ activation is according to the increase of metal atom radius. Consequently, C–H bond activation demands a lower energy barrier on Ni–Pt cluster. To illustrate the adsorptive dissociation behaviors of CH₄ at different Ni–M clusters, the Mulliken atomic charge was analyzed. In general, the electron gain of CH₄ binding at different Ni–M clusters follows the sequence of Ni–Cu (–0.02 e) < Ni (–0.04 e) < Ni–Pd (–0.08 e) < Ni–Pt (–0.09 e) < Ni–Co (–0.10 e) < Ni–Fe (–0.12 e), and the binding strength between catalysts and CH ₄ raises with the CH₄ electron gain increasing. This work provides insights into understanding the role of promoter metal M on thermal-catalytic activation of CH₄ over Ni/MgO catalysts, and is useful to interpret the reaction at an atomic scale.     

用Shedlovsky方法求解298.15K时硫酸氧钒离子对解离常数

采用电导法测定了水溶液中298.15 K时VOSO4·n H2O(s)的电导率,通过Origin数据拟合求出极限摩尔电导;采用改进的Ostwald稀释定律和改进的Davies方程求解活度系数,进而求得溶液的真实离子强度;采用Shedlovsky方法求解硫酸氧钒离子对的解离常数。经过数据处理得到了298.15 K时硫酸氧钒极限摩尔电导率Λ0为209.205 020 9S·dm2/mol,硫酸氧钒离子对的解离常数Kd为0.001 756 218,进而可以研究其他相关热力学性质。     

The Role of Higher Lying Electronic States in Charge Photogeneration in Organic Solar Cells

The role of excess photon energy on charge generation efficiency in bulk heterojunction solar cells is still an open issue for the organic photovoltaic community. Here, the spectral dependence of the internal quantum efficiency (IQE) for a poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b]­dithiophene)‐alt‐4,7‐(2,1,3‐benzothiadiazole)]:6,6‐phenyl‐C₆₁‐butyric acid methyl ester (PCPDTBT:PC60BM)‐based solar cell is derived combining accurate optoelectronic characterization and comprehensive optical modeling. This joint approach is shown to be essential to get reliable values of the IQE. Photons with energy higher than the bandgap of the donor material can effectively contribute to enhance the IQE of the solar cell. This holds true independently of the device architecture, reflecting an intrinsic property of the active material. Moreover, the nanomorphology of the bulk heterojunction plays a crucial role in determining the IQE spectral dependence: the coarser and more crystalline, the lesser the gain in IQE upon high energy excitation.