超音速气动雾化制粉机理的实验研究及分析

本文根据雾化模拟实验,提出了初次雾化模型。并利用已有超音速气动知识,对这一模型进行了定性的解释和定量的描述,给出粒度分布和冷却速率的解析表达式,对雾化工艺参数的选择有一定的指导意义。     

紧束缚模型方法及其在DNA分子中的应用

近年来,紧束缚模型方法被广泛应用于计算生物大分子体系.本文从第一性原理出发,根据紧束缚近似的思想,推导出生物大分子体系中的单电子运动方程.在此基础上给出了紧束缚模型方法中所涉及参数(在位能和迁移积分)的计算公式,在理论上完善了紧束缚模型方法.我们将所提出的参数化方法应用于理想B型DNA分子,给出了各种序列组合下的在位能和迁移积分.此外,我们还计算了周期性DNA分子poly(A)-poly(T)和poly(G)-poly(C)中空穴在位能和迁移积分随格点间距离的变化,为改进现有的SSH极化子模型提供了新的思路,有助于DNA中电荷输运的极化子机理的研究.     

Off-on-off luminescent switching of a dye containing imidazo[4,5-f][1,10]phenanthroline

A new acid-base fluorescent switch containing both imidazo[4,5-f][1,10]-phenanthroline and triphenylamine groups has been synthesized.Its fluorescence emissions and absorptions can be reversibiy changed through protonation/deprotonation of imidazole and amine moiety by controlling the intramolecular charge transfer(ICT) process,leading to off-on-off fluorescent molecular switching.     

Effects of cosolvent on formation and morphology of microspheres in precipitation polymerization of divinylbenzene in supercritical carbon dioxide

Precipitation polymerizations of divinylbenzene(DVB) in pure supercritical carbon dioxide,and parallel runs with presence of a cosolvent were carried out.The results showed that use of acetone as the cosolvent contributed greatly to the formation of the monodisperse microspheres.PDVB microspheres,with obviously higher uniformity than reported up to date,were achieved using 6-7 mL of acetone in a reactor of 50 mL with DVB concentration of 0.4 mol/L under 16 MPa,a much lower pressure than previously reported without use of cosolvent.     

G-Protein-Coupled Receptor–Membrane Interactions Depend on the Receptor Activation State

G-protein-coupled receptors (GPCRs) are the largest family of human membrane proteins and serve as primary targets of approximately one-third of currently marketed drugs. In particular, adenosine A₁ receptor (A₁AR) is an important therapeutic target for treating cardiac ischemia–reperfusion injuries, neuropathic pain, and renal diseases. As a prototypical GPCR, the A₁AR is located within a phospholipid membrane bilayer and transmits cellular signals by changing between different conformational states. It is important to elucidate the lipid–protein interactions in order to understand the functional mechanism of GPCRs. Here, all-atom simulations using a robust Gaussian accelerated molecular dynamics (GaMD) method were performed on both the inactive (antagonist bound) and active (agonist and G-protein bound) A₁AR, which was embedded in a 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) lipid bilayer. In the GaMD simulations, the membrane lipids played a key role in stabilizing different conformational states of the A₁AR. Our simulations further identified important regions of the receptor that interacted distinctly with the lipids in highly correlated manner. Activation of the A₁AR led to differential dynamics in the upper and lower leaflets of the lipid bilayer. In summary, GaMD enhanced simulations have revealed strongly coupled dynamics of the GPCR and lipids that depend on the receptor activation state. © 2019 Wiley Periodicals, Inc.     

Accurate prediction of relative binding affinities of a series of HIV-1 protease inhibitors using semi-empirical quantum mechanical charge

A major challenge in computer-aided drug design is the accurate estimation of ligand binding affinity. Here, a new approach that combines the adaptive steered molecular dynamics (ASMD) and partial atomic charges calculated by semi-empirical quantum mechanics (SQMPC), namely ASMD-SQMPC, is suggested to predict the ligand binding affinities, with 24 HIV-1 protease inhibitors as testing examples. In the ASMD-SQMPC, the relative binding free energy (ΔG) is reflected by the average maximum potential of mean force (<PMF>_max) between bound and unbound states. The correlation coefficient (R²) between the <PMF>_max and experimentally determined ΔG is 0.86, showing a significant improvement compared with the conventional ASMD (R² = 0.52). Therefore, this study provides an efficient approach to predict the relative ΔG and reveals the significance of precise partial atomic charges in the theoretical simulations.     

压力对硫醇分子膜电输运性质的影响

利用密度泛函理论和弹性散射格林函数方法,对硫醇分子膜的电学特性进行了理论模拟,计算结果表明,分子结的导电能力随着压力增加而增加,对单分子构成的分子结来说,电流的增加主要是由于电极距离的变化导致单个分子与电极的耦合增强,对于由多个分子构成的分子膜来说,由于外加压力的变化,导致分子结的链内隧穿和链间隧穿几率增大,从而导致导...     

Novel tri-carbazole modified fluorene host material for highly efficient solution-processed blue and green electrophosphorescent devices

A series of novel solution-processable small-molecule host materials: 2DPF-TCz, 2SBF-TCz, 27DPF-TCz, and 27SBF-TCz comprising a fluorene monomer as the rigid core and tri-carbazole as the periphery have been designed and synthesized, and their optical, electrochemical, and thermal properties have been fully characterized. The host materials exhibit high glass-transition temperatures (231–310 °C) and high triplet energy levels (2.61–2.73 eV). High-quality amorphous thin films can be obtained by spin-coating the host materials from solutions. It is found that the HOMO level of the host materials can be tuned by linking the tri-carbazole unit to the 2,7 positions of the fluorine core, resulting in appropriate HOMO energy levels (−5.36 to −5.23 eV) for improved hole-injection in the device. Solution-processed blue and green electrophosphorescent devices bases on the developed host materials exhibit high efficiencies of 21.2 and 34.8 cd A⁻¹, respectively.     

Functoriality of automorphic L-functions through their zeros

Let E be a Galois extension of Q of degree , not necessarily solvable. In this paper we first prove that the L-function L(s,π) attached to an automorphic cuspidal representation π of GLm(EA) cannot be factored nontrivially into a product of L-functions over E. Next, we compare the n-level correlation of normalized nontrivial zeros of L(s,π1)···L(s,πk), where πj, j = 1,...,k, are automorphic cuspidal representations of GLmj(QA), with that of L(s,π). We prove a necessary condition for L(s,π) having a factoriz...     

Design,synthesis and in vivo anti-hyperglycemic activity of gem-dimethyl-bearing C-glucosides as SGLT2 inhibitors

A series of gem-dimethyl-bearing C-glucosides were designed and synthesized as SGLT2 inhibitors,with anhydrous aluminum chloride-mediated Friedel-Crafts alkylation to construct the gem-dimethyl functionality being the key step.The in vivo anti-hyperglycemic activity was evaluated with mice oral glucose tolerance test(OGTT),and all the synthesized compounds showed significant but less potent anti-hyperglycemic activity than the positive control dapagliflozin.