Anisotropic Poisson Effect and Deformation‐Induced Fluorescence Change of Elastic 9,10‐Dibromoanthracene Single Crystals

Elastic organic crystals have attracted considerable attention as next‐generation flexible smart materials. However, the detailed information on both molecular packing change and macroscopic mechanical crystal deformations upon applied stress is still insufficient. Herein, we report that fluorescent single crystals of 9,10‐dibromoanthracene are elastically bendable and stretchable, which allows a detailed investigation of the deformation behavior. We clearly observed a Poisson effect for the crystal, where the short axes (b and c‐axes) of the crystal are contracted upon elongation along the long axis (a‐axis). Moreover, we found that the Poisson's ratios along the b‐axis and c‐axis are largely different. Theoretical molecular simulation suggests that the tilting motion of the anthracene may be responsible for the large deformation along the c‐axis. Spatially resolved photoluminescence (PL) measurement of the bent elastic crystals reveals that the PL spectra at the outer (elongated), central (neutral), and inner (contracted) sides are different from each other.     

Hit identification against peptidyl-prolyl isomerase of Theileria annulata by combined virtual high-throughput screening and molecular dynamics simulation approach

Theileria annulata secretes peptidyl prolyl isomerase enzyme (TaPIN1) to manipulate the host cell oncogenic signaling pathway by disrupting the tumor suppressor F-box and WD repeat domain-containing 7 (FBW7) protein level leading to an increased level of c-Jun proto-oncogene. Buparvaquone is a hydroxynaphthoquinone anti-theilerial drug and has been used to treat theileriosis. However, TaPIN1 contains the A53 P mutation that causes drug resistance. In this study, potential TaPIN1 inhibitors were investigated using a library of naphthoquinone derivatives. Comparative models of mutant (m) and wild type (wt) TaPIN1 were predicted and energy minimization was followed by structure validation. A naphthoquinone (hydroxynaphthalene-1,2-dione, hydroxynaphthalene-1,4-dione) and hydroxynaphthalene-2,3-dione library was screened by Schrödinger Glide HTVS, SP and XP docking methodologies and the docked compounds were ranked by the Glide XP scoring function. The two highest ranked docked compounds Compound 1 (4-hydroxy-3-[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxynaphthalene-1,2-dione) and Compound 2 (6-acetyl-1,4,5,7,8-pentahydroxynaphthalene-2,3-dione) were used for further molecular dynamics (MD) simulation studies. The MD results showed that ligand Compound 1 was located in the active site of both mTaPIN1 and wtTaPIN1 and could be proposed as a potential inhibitor by acting as a substrate antagonist. However, ligand Compound 2 was displaced away from the binding pocket of wtTaPIN1 but was located near the active site binding pocket of mTaPIN1 suggesting that could be selectively evaluated as a potential inhibitor against the mTaPIN1. Compound 1 and Compound 2 ligands are potential inhibitors but Compound 2 is suggested as a better inhibitor for mTaPIN1. These ligands could also further evaluated as potential inhibitors against human peptidyl prolyl isomerase which causes cancer in humans by using the same mechanism as TaPIN1.     

Experimental and Modeling Investigation of Radical Homopolymerization of 2‐(Methacryloyloxyethyl) Trimethylammonium Chloride in Aqueous Solution

The radical homopolymerization kinetics of 2‐(methacryloyloxyethyl) trimethylammonium chloride (TMAEMC) in aqueous solution is investigated across a wide range of initial monomer contents (5–35 wt%), ionic strengths, and pH levels using an in‐situ NMR technique to track monomer consumption over the complete conversion range. Molar mass distributions (MMD) of the final homopolymers are also examined, with additional batch and semi‐batch experiments conducted in a stirred vessel. The rates of monomer conversion and polymer MMDs are dependent on initial monomer content but almost entirely independent of pH and the presence of salts, with some acceleration of rate observed for low monomer levels at very high salt concentration. To aid with the interpretation of these results, the conductivity and counterion activity of monomer and polymer mixtures are measured to determine the extent of electrostatic interactions at various levels of conversion. These results are combined with recently reported measurements of TMAEMC homopropagation kinetics to develop a TMAEMC homopolymerization model that captures the systematic decrease in rates of monomer conversion observed with increased initial monomer content during batch polymerization as well as provides a good representation of semi‐batch polymerization.     

Pharmacoinformatics and molecular dynamic simulation studies to identify potential small-molecule inhibitors of WNK-SPAK/OSR1 signaling that mimic the RFQV motifs of WNK kinases

The WNK-SPAK/OSR1 signaling is a complex of serine and threonine protein kinases that involves in the regulation of human blood pressure. The WNK kinases phosphorylate and activate SPAK and OSR1 kinases through the interaction of RFQV motifs of WNK kinases with the C-terminal domains of SPAK and OSR1. Upon phosphorylation, SPAK and OSR1 phosphorylate key ion co-transporters such as Na⁺-[K⁺]-2Cl⁻ (NKCC_1-2) and K⁺-Cl⁻ (KCC_1-4), which are essential for electrolytes balance and blood pressure regulation. Targeting the binding site of the RFQV motifs of WNK kinases on the C-terminal domain (CTD) of SPAK and OSR1 has emerged as a valuable approach to inhibit the WNK-SPAK/OSR1 signaling pathway. Herein, an effort has been intended to pinpoint non-peptidic small-molecules that could disrupt the binding of SPAK/OSR1 to WNK kinases, hence, inhibit the SPAK and OSR1 phosphorylation and activation by WNK kinases through pharmacoinformatics and molecular dynamic simulation methodologies. A sequential structure-based virtual screening of a focus protein-protein interaction chemical library composed of 11,870 compounds lead to the identification of three compounds having good lead-compound properties with respect to their predicted inhibitory constants, pharmacophore fit scores, binding affinities, ADME-T parameters, drug-likeness properties and ligand efficiency metrics. The mechanism of interaction and binding stability of these compounds to OSR1-CTD were confirmed using molecular docking and dynamic simulation studies. Hence, the identified compounds may have therapeutic potential as novel antihypertensive agents subjected to experimental validation.     

Snap-through path in a bistable dielectric elastomer actuator

The dielectric elastomer (DE) has attracted significant attention due to its desired features, including large deformation, fast response, and high energy density. However, for a DE actuator (DEA) utilizing a snap-through deformation mode, most existing theoretical models fail to predict its deformation path. This paper develops a new finite element method (FEM) based on the three-parameter Gent-Gent model suitable for capturing strain-stiffening behaviors. The simulation results are verified by experiments, indicating that the FEM can accurately characterize the snap-through path of a DE. The method proposed in this paper provides theoretical guidance and inspiration for designing and applying DEs and bistable electroactive actuators.     

碳纤维复合材料冲击模型率相关修正方法与试验研究

目前先进航空发动机的风扇叶片均采用复合材料结构,为了研究其在工作过程中可能受到的冲击损伤,即碳纤维增强树脂基复合材料受到高速冲击后的损伤与破坏过程,对其准静态下的正交各向异性本构模型和失效准则进行修正,建立了应变率相关的三维动态本构及损伤模型．该模型考虑了材料模量、强度和断裂韧性与应变率的相关性,并采用基于断裂韧性的渐进损伤模式对刚度进行折减来控制破坏过程．开展了不同应变率下的动态试验,得到基体方向拉伸与剪切的动态响应数据,拟合得到相应的动态修正因子．将该模型结合修正因子植入数值软件进行仿真计算,分析结果表明,所建立的率相关本构及损伤模型能够更准确地模拟层合板受冲击过程的损伤和破坏,与试验吻合较好．     

含中心裂纹梯度纳晶金属的数值模拟

梯度纳晶金属由于其微观组织的梯度分布,力学属性也呈现梯度变化,这使得其表现出不同于传统均匀材料的断裂行为．利用材料力学参数的梯度分布来表征梯度纳晶金属中晶粒尺寸的梯度变化,并编写ABAQUS和MATLAB脚本程序建立分层有限元模型．通过数值模拟计算了含有初始中心裂纹的梯度纳晶金属在受远端均匀拉应力作用下的裂尖J积分,分别研究了屈服应力梯度、裂纹角度和裂纹长度对金属材料断裂韧性的影响,并与传统粗晶进行了对比．结果表明梯度纳米结构的存在导致梯度纳晶金属内部的中心裂纹两端表现出不同的断裂韧性,小晶粒一侧裂尖的抗裂韧性优于大晶粒一侧裂尖,且屈服应力梯度绝对值越大,两者差距越大．梯度纳晶金属的断裂韧性受中心裂纹角度和长度变化的影响与传统粗晶金属基本一致,同时在晶粒尺寸梯度的作用下梯度纳晶的裂尖J积分略低于粗晶,即整体上拥有更好的抗裂韧性．     

颗粒流体系统的格子Boltzmann数值方法研究进展

介绍Euler-Lagrange框架下基于格子Boltzmann方法LBM (Lattice Boltzmann Method)发展的两种不同层次(即不同时-空尺度和精度)的颗粒流体系统离散模拟方法,即格子Boltzmann颗粒解析直接数值模拟(LB-based PR-DNS)方法和格子Boltzmann离散颗粒模拟(LB-based DPS)方法,总结了Euler-Euler框架下基于格子Boltzmann双流体模型(LB-based TFM)方面的探索研究。LB-based PR-DNS方法中颗粒尺寸远大于格子步长,能够直接解析出流体在颗粒表面的流动以及颗粒所受完整的动力学信息;LB-based DPS方法中格子步长远大于颗粒直径,其在计算精度、时间耗费和计算效率之间能达到很好的平衡,可获得流体的宏观平均流动及颗粒的运动轨迹信息。LB-based DNS和DPS是探索颗粒流体系统的有力手段,但LB-based TFM应用于模拟颗粒流体系统仍需进一步探索。     

各向同性超弹性本构模型数值计算及验证

现有多种形式的橡胶本构模型试图预测橡胶力学性质,其中部分模型已写入有限元软件中用于仿真计算,还存在较多拟合性较好的模型无法在有限元材料库中直接获得。本文详述了由不变量和主伸长率描写的各向同性超弹性本构模型的数值实现方法,并结合最新的本构模型开发了UHYPER和UMAT子程序。将UHYPER用于有限元实现对多孔橡胶板的拉伸仿真,对比仿真和试验结果,验证子程序的正确性以及评估本构模型预测复杂应变场的准确性;将UMAT用于单轴、等双轴和剪切拉伸的有限元仿真,对比仿真和本构模型理论结果,验证子程序的可靠性。结果表明,有限元仿真结果与理论结果拟合较好,子程序能够契合本构模型的力学描述,所述方法可以用于超弹性材料的数值计算。     

回转窑多粒径颗粒流动与偏析的DEM模拟与实验研究

为明晰回转窑内颗粒的运动行为及偏析机理,以绿豆、黄豆和黑豆为颗粒介质,依次对3种装填顺序下的颗粒流动过程进行离散元模拟与实验研究,以颗粒质量分数和平均粒度为判据,对颗粒偏析进行评价。结果表明,回转窑内颗粒流动区可分为自由滚落区、渗流呆滞区以及窑壁携带区,自由滚落区颗粒流速最大,而渗流呆滞区流速最小。窑内颗粒沿轴向输运过程发生径向偏析,形成夹层结构,小颗粒受渗流作用在渗流呆滞区中心形成内核,大粒径和中等粒径颗粒集中在自由滚落区和窑壁携带区。窑内颗粒力链分布不均匀,强力链分布于近窑壁区,弱力链分布于自由滚落区和渗流呆滞区,且渗流呆滞区力链细而密集。当窑头附近不同粒径颗粒存在轴向速度差时,颗粒在轴向发生掺混,并产生径向偏析。