Isoflavonoids from Astragalus membranaceus Hairy Roots

Chemistry of Natural Compounds -     

Identification of phytocompounds from Houttuynia cordata Thunb. as potential inhibitors for SARS-CoV-2 replication proteins through GC–MS/LC–MS characterization,molecular docking and molecular dynamics simulation

The COVID-19 pandemic caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a massive viral disease outbreak of international concerns. The present study is mainly intended to identify the bioactive phytocompounds from traditional antiviral herb Houttuynia cordata Thunb. as potential inhibitors for three main replication proteins of SARS-CoV-2, namely Main protease (Mpro), Papain-Like protease (PLpro) and ADP ribose phosphatase (ADRP) which control the replication process. A total of 177 phytocompounds were characterized from H. cordata using GC–MS/LC–MS and they were docked against three SARS-CoV-2 proteins (receptors), namely Mpro, PLpro and ADRP using Epic, LigPrep and Glide module of Schrödinger suite 2020-3. During docking studies, phytocompounds (ligand) 6-Hydroxyondansetron (A104) have demonstrated strong binding affinity toward receptors Mpro (PDB ID 6LU7) and PLpro (PDB ID 7JRN) with G-score of???7.274 and???5.672, respectively, while Quercitrin (A166) also showed strong binding affinity toward ADRP (PDB ID 6W02) with G-score -6.788. Molecular Dynamics Simulation (MDS) performed using Desmond module of Schrödinger suite 2020–3 has demonstrated better stability in the ligand–receptor complexes A104-6LU7 and A166-6W02 within 100 ns than the A104-7JRN complex. The ADME-Tox study performed using SwissADMEserver for pharmacokinetics of the selected phytocompounds 6-Hydroxyondansetron (A104) and Quercitrin (A166) demonstrated that 6-Hydroxyondansetron passes all the required drug discovery rules which can potentially inhibit Mpro and PLpro of SARS-CoV-2 without causing toxicity while Quercitrin demonstrated less drug-like properties but also demonstrated as potential inhibitor for ADRP. Present findings confer opportunities for 6-Hydroxyondansetron and Quercitrin to be developed as new therapeutic drug against COVID-19.

Graphic abstract

     

具有外部干扰的耦合时滞神经网络固定时间二分同步

针对结构平衡图与结构非平衡图的网络拓扑,考虑了一类具有外部干扰的耦合时滞神经网络模型,分别设计了其固定时间同步控制协议.借助固定时间稳定性理论与不等式技巧,获得了耦合网络在固定时间内达到同步的充分性判据,给出了具体的收敛时间上界,并验证了固定时间同步网络的鲁棒性与抗干扰性.为了扩大网络模型的适用性,考虑的神经网络激活函数为非连续的函数,可借助微分包含与集值李导数理论解释非连续微分方程的动力学行为.最后,分别在结构平衡图和非平衡图下对耦合神经网络的固定时间二分同步进行了数值仿真,验证了控制算法的有效性及理论结果的正确性.     

数字化转型背景下我国金融机构业务与技术融合发展的路径

近年来,我国金融行业数字化转型不断提速,金融机构数字化转型已迫在眉睫.金融机构面临的数字化转型环境包括3个方面:一是大数据走向跨界融合;二是人工智能加速发展;三是区块链等技术建立了新型连接关系.基于以上环境分析,文章认为金融机构数字化转型的核心在于业务与技术融合,需要在机制、组织、架构、人才和文化层面实行再造.     

大学生童年受忽视经历对自尊的影响:应对方式的中介作用

为研究大学生在童年时受到忽视与自尊水平、应对方式之间的关系,采用方便抽样法,向430名学生发放童年受忽视量表、简易应对方式量表和自尊量表,使用统计软件SPSS17.0进行数据整理与分析,结果表明,大学生在童年时受到的忽视与自尊、处理应对的积极方式是负相关关系(r=-0.164,r=-0.246,P<0.01),忽视与消极应对方式呈正相关关系(r=0.152,P<0.01);自尊与大学生采用积极的应对方式呈正相关关系(r=0.398,P<0.01),与采用消极的应对方式呈负相关关系(r=-0.217,P<0.01);不同的应对方式在面临忽视与自尊之间起着协调作用,积极应对方式的协调效果有29.4%,而消极应对方式的协调效果则只有12.6%,差距十分明显。因此,大学生在童年时受到忽视与自尊、不同的应对方式会收到完全不同的协调效果。     

Direct visualization of the nanoscopic three‐phase structure and stiffness of NBR/PVC blends by AFM nanomechanical mapping

The PeakForce Quantitative Nanomechanical Mapping based on atomic force microscope (AFM) is employed to first visualize and then quantify the elastic properties of a model nitrile rubber/poly(vinyl chloride) (NBR/PVC) blend at the nanoscale. This method allows us to consistently observe the changes in mechanical properties of each phase in polymer blends. Beyond measuring and discriminating elastic modulus and adhesion forces of each phase, we tune the AFM tips and the peak force parameters in order to reliably image samples. In view of viscoelastic difference in each phase, a three‐phase coexistence of an unmixed NBR phase, the mixed phase, and PVC microcrystallites is directly visualized in NBR/PVC blends. The nanomechanical investigation is also capable of recognizing the crosslinked rubber phase in cured rubber. The contribution of the mixed phase was quantified and it was found that the mechanical properties of blends are mainly determined by the homogeneity and stiffness of the mixed phase. This study furthers our understanding the structure–mechanical property relationship of thermoplastic elastomers, which is important for their potential design and applications. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 662–669     

Ni~(26+)离子态分辨光复合过程的R矩阵理论研究

利用基于相对论R矩阵理论的DARC程序系统计算了Ni 25+离子基态1s22s(2S1/2)和激发态1s22p(2P1/2,2P3/2)的光电离截面,并通过细致平衡原理获得了统一的光复合过程(即辐射复合和双电子复合)态分辨的截面,计算结果给出了辐射复合与双电子复合过程间的干涉效应.为了标识和分析KLL共振能区所有的共振峰,基于相对论组态相互作用理论(RCI)的FAC程序被用来计算共振峰的能量、强度及其相关的双激发态的辐射、俄歇跃迁几率以及共振宽度等.利用统一的光复合截面进一步得到了KLL双电子复合过程的伴线强度,并与孤立共振近似下FAC的计算结果以及以前的理论和实验结果进行了比较,对存在的一致性和偏差进行了分析和讨论.     

深水铺管船的动力定位能力评估系统

为解决评估铺管船作业能力的难题,提出一种适用于评估铺管船动力定位能力的方法,开发了动力定位能力评估程序系统,并针对高海况环境条件设计了优化的辅助作业方案.采用数值计算方法对铺管船作业期间的平均二阶力、风载荷以及流载荷进行仿真计算,建立了环境载荷与动力定位系统提供的推力之间的平衡关系,给出了用于评估铺管船动力定位能力的系统模块,采用动力定位能力包络线的方式表达动力评估结果.在高海况作业中给出安全建议,即采用辅助拖轮作用于船舶适当位置以增强动力定位能力,从而降低工程作业风险.     

Integral closure of a quartic extension

Let R be a Noetherian unique factorization domain such that 2 and 3 are units,and let A=R[α]be a quartic extension over R by adding a rootαof an irreducible quartic polynomial p(z)=z4+az2+bz+c over R.We will compute explicitly the integral closure of A in its fraction field,which is based on a proper factorization of the coefficients and the algebraic invariants of p(z).In fact,we get the factorization by resolving the singularities of a plane curve defined by z4+a(x)z2+b(x)z+c(x)=0.The integral closure is expressed as a syzygy module and the syzygy equations are given explicitly.We compute also the ramifications of the integral closure over R.     

习近平的新时代科技创新全球视野

 当前世界新一轮科技与产业革命正蓄势待发，中共中央总书记、国家主席、中央军委主席习近平以全球视野提出了新时代科技创新的指导思想。习近平指出：新时代中国必须采取科技创新全球视野系列举措，瞄准世界科技前沿，实施科技开放创新；构建世界科技命运共同体，实现世界各国合作共赢共享发展；采取"非对称性"赶超战略，取得后发超越；全面提升科技创新全球化，增强科技创新全球竞争力和世界影响力。分析表明，新时代习近平科技创新全球视野是引领和指导中国科技创新发展和建成世界科技强国的重大方略。