烟碱型乙酰胆碱受体吡啶基胺类配体的构效关系研究

采用分子动力学模拟退火技术寻找了一类新型烟碱型乙酰胆碱受体吡啶基胺类配体分子的优势构象，用分子力学方法进行了结构优化，再用半经验量子化学方法中的AM1方法进一步优化，并做了电子结构计算.用计算所得物化参数对配体亲和性进行多元线性回归分析，回归结果表明：化合物pKi值与分子最低空轨道能量(ELUMO)、吡啶基所带总电荷(Qp)及分子构象相关.根据计算结果对该类化合物与受体的作用机制和作用位点进行了讨论.     

超声心动图联合动态心电图检查对急性心肌梗死诊断和预后评估的价值

为探讨超声心动图联合动态心电图检查在急性心肌梗死(AMI)患者诊断和预后评估中的应用价值,本研究选取2016年6月~2018年6月我院收治并确诊的100例AMI患者作为观察组,另选取同期100例非冠心病患者作为对照组。以AMI患者心源性死亡为终点事件,将观察组分为死亡组(n=15)和存活组(n=85)。所有患者均采用飞利浦IU-Elite及EPIQ5彩色多普勒超声诊断仪进行超声心动图检查,采用DMS-3004A进行标准的12导联动态心电图检查。比较各组患者心率震荡指标[震荡起始(TO)、震荡斜率(TS)]、心率变异性指标[NN间期标准差(SDNN)、QT离散度(QTd)、经心率校正的QT离散度(QTcd)]及心功能指标[左心室舒张末期内径(LVEDD)、左心室射血分数(LVEF)]水平的变化。结果显示,观察组TO、QTd、QTcd、LVEDD均明显高于对照组,TS、SDNN、LVEF均明显低于对照组,差异有统计学意义(P<0.05)。死亡组TS、SDNN均明显低于存活组,差异有统计学意义(P<0.05);死亡组TO高于存活组,QTd、QTcd、LVEF、LVEDD均低于存活组,但差异无统计学意义(P>0.05)。本研究结果表明,AMI患者心率震荡(HRT)明显减弱甚至消失,HRV、LVEF明显降低,LVEDD、QTd明显增大,QT间期明显延长。超声心动图和动态心电图联合检查对AMI患者诊断及预后评估均有重要的临床应用价值。     

Heterofullerenes: Structure and property predictions,possible uses and synthesis proposals

Summary Substituting carbon atoms of fullerenes by heteroatoms and vacancies will lead to new and yet unknown spherical-shaped molecules termed hereafter as heterofullerenes. The enormous structural diversity of these molecules is investigated and their structural, electronic and thermochemical properties are predicted using semiempirical computations. Computational results for complexes with ions lead to the hypothesis that these molecules behave like microscopic Faraday cages in which the electrons concentrate on the outer side of the sphere. It is predicted that some of these heterofullerenes are structurally and electronically similar to phthalocyanines and related molecules but offer many additional advantages. Potential uses such as adding heterofullerenes to fullerene materials, as superior starting materials for the fabrication of diamonds, as catalysts in hydrogenation reactions, as components of materials dominated until now by phthalocyanines, etc., are discussed. Simple synthetic routes to these compounds that are based on minor alternations of existing methods for fullerene production are proposed. On the basis of the thermochemical calculations, we believe that the most promising possibility consists of using metal cyanide/graphite composite target rods instead of pure graphite rods as in a conventional fullerene synthesis.     

Comparison Between the IR Spectra and the Structure of the Two Conformations of a Diazabicyclanol

Abstract

In the two stable conformations of the diazabicyclanol 3, 7-dimethyl-3, 7-diazabicyclo[3. 3. 1]nonan-9-ol, chair-chair (Va) and chair-boat (Vb), the infrared spectra (200–4000 cm^?1) were recorded, compared and their vibrations analysed. Using the AMI senlempirical method, the geometry was fully optimized in both forms, and the theoretical Infrared spectra were calculated and compared. In the (Vb) conformation, the IR spectra were recorded in CCl₃D, CCl₄ and S₂C solvents. Some correlations were established.     

Functional magnetic resonance imaging reference phantom

Functional magnetic resonance imaging (fMRI) is widely used to pinpoint active brain areas. Changes in neuronal activity modulate the local blood oxygenation level, and the associated modulation of the magnetic field homogeneity can be detected with magnetic resonance imaging. Thus, the blood oxygenation level-dependent (BOLD) fMRI indirectly measures neuronal activity. Similar modulation of magnetic field homogeneity was here elicited by other means to generate a BOLD-like change in a new phantom constructed to provide reference activations during fMRI. Magnetic inhomogeneities were produced by applying current to coils located near the phantom containing 1.5 ml of Gd-doped water. The signal-to-noise ratio of the images, produced by gradient-recalled echo-planar imaging, varied between 104 and 107 at a selected voxel when the field was and was not inhomogenized, respectively. The contrast of signals between homogeneous and inhomogeneous conditions was generally stable, except in 3% of time points. During the periods of greatest deviations an observable change would have been detected in a simultaneously measured BOLD signal. Such changes could result from the imaging method or occur through glitches in hardware or alterations in the measurement environment. With identical measurement setups, the phantom could allow comparing intersession or intersubject brain activations.     

Evaluation of a Combined Quantum Chemical Method Used in Calculating O?H Bond Dissociation Enthalpy

O? H bond dissociation enthalpies (BDE) for a variety of substituted phenols were calculated using a combined quantum chemical method. It is found that the calculated O? H BDE correlated well with the recommended values, except for ortho‐tert‐butyl substituted phenols. For the electron‐donating group substituted phenols the calculated O? H BDE are slightly higher than the recommended values, however, for the electron‐withdrawing group substituted phenols the calculated O? H BDE are slightly lower than the recommended values.     

基于表面增强拉曼光谱技术的心肌生物标志物检测

心血管疾病(CVD)是全球最主要的死亡原因,急性心肌梗死(AMI)是心血管疾病致死的主要病因,安全快速地诊断AMI对于降低患者的死亡率至关重要。因常用的检测方法如心电图(ECG)缺乏足够的敏感性,寻找并针对AMI生物标志物开展高灵敏检测已成为早期检测AMI重要手段。心肌肌钙蛋白I(cTnI)、肌酸激酶同工酶(CK-MB)和肌红蛋白(Myo)是目前公认的检测AMI的重要心肌生物标志物。在过去的几十年里,许多生物传感器被开发出来用于检测心肌生物标志物,其中基于表面增强拉曼光谱(SERS)的心肌生物标志物检测技术迅速发展,并表现出独特的技术优势和广阔的应用前景。本文首先介绍了多种心肌生物标志物及其与AMI的关联,在此基础上概述主要的心肌生物标志物检测方法的原理、优势及局限性,重点介绍近年来新兴的SERS技术及其在心肌生物标志物传感方面的最新研究进展,并对该技术在AMI诊断方面的应用前景以及有待突破的瓶颈进行了讨论和展望。     

聚醚醚酮微结构及反应特性的量子化学研究

利用AM1对聚醚醚酮重复单元进行条件优化,得出了此分子的最优构型,明确了聚醚醚酮分子链的微观构象,并在此构象基础上进行量子化学计算,给出了健序、净电荷、前线轨道等信息,从理论上研究了聚醚醚酮的磺化反应及热分解反应的一些特性.     

Reaction mechanisms in peptide synthesis. Part 1. Semiquantitative characteristics of the reactivity of 2-methyl-5(4H)-oxazolone with water and ammonia in the gas phase and weakly polar media

Summary 2,4-Dialkyl-5(4H)-oxazolones are well-recognized intermediates in some aminolysis reactions in peptide synthesis. Using the MOPAC molecular orbital programs, detailed geometric and energetic characteristics of the elementary reaction pathways for the additions of water and ammonia to 2-methyl-5(4H)-oxazolone have been determined at the AM1 level. The results demonstrate that the additions must be parsed into a two-step mechanism involving formation of the -hydroxyimine followed by tautomerization to the parent N-acetylamino acid or amide.     

The effect of the valent state of the heteroatom on the spectrochemical evidence of conjugation in allyl compounds of sulfur and phosphorus

The effect of valency of the heteroatom on the spectrochemical evidence of the conjugation in allyl derivatives of S^II,VI and P^III,IV was studied by quantum chemical methods. The geometric and electronic structures of thetrans- andgauche-conformers, including those for allyl compounds of P^V with equatorial or axial P-C bonds, were calculated. According to the calculations, inversion of the higher occupied molecular orbitals (MO) and the convergence of their energies resulting from the replacement of weak n,-conjugation by strong ,-conjugation should occur on going from S^II and P^III to S^VI and P^V. Increasing the interaction between the higher occupied MO of the fragments in the non-planar conformation of the molecule causes strengthening of the spectral evidence of conjugation: a decrease in the first ionization potential and a bathochromic shift of the long-wavelength absorption band in the electronic spectrum. The increased relative stability of thegauche-conformers of allyl compounds of hypervalent elements was explained by the through-space interaction between the vacant d-orbitals of the S^VI and P^V atoms and the -orbital of the C=C bond. Charge transfer between the molecular fragments makes the major contribution to the energy of conjugation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 43–47, January, 1995.The work was carried out with the financial support of the Russian Foundation for Basic Research (Project No. 93-03-5566).