QSPR Studies on lgK_(ow) and lgK_(oc) of Fluorobenzenes and Property Parameters Based on HF and DFT Calculations

1 INTRODUCTION Quantitative structure-activity relationship (QSAR) equation could be employed to predict the biological activities of unknown compounds, which is signifi- cant for initial screening and evaluation of toxic compounds[1]. Soil sorption coeff…     

Combined bond-polarization basis sets for accurate determination of dissociation energies

Summary The effect of bond functions on the basis set superposition error (BSSE) is investigated at both SCF (self consistent field) and correlated levels for a number of basis sets using the pairwise additive function counterpoise (PAFC), the site-site function counterpoise (SSFC), and the newly proposed successive reaction counterpoise method (SRCP). BSSEs using bond functions are shown to be roughly twice those without bond functions, whereas the latter may still be quite sizeable. The addition of f functions dramatically decreases the bond function BSSE. The results obtained support the empirical decision in our earlier papers to neglect BSSE altogether.     

Examination of charge alternation in CH4 and CH3F from ab initio LCAO SCF MO wavefunctions and their localized bond orbitals

The question of whether or not fluorine substitution produces charge alternation is examined for CH₄ and CH₃F. Two sets of ab initio LCAO SCF MO wavefunctions (one a 3 G STO based one, the other a double zeta based one) are analyzed via charge density, localized CH bond moment, and population analysis calculations. Although both sets of wavefunctions show a slightly more negative H region in CH₃F relative to CH₄, in qualitative agreement with earlier work by Pople et al., the differences are small, and their sources are not clear. For example, in the 3 G calculations the CH localized orbital is the essential source of the increased density in CH₃F, while for the double zeta calculations the increased density is due to the tail of an F lone-pair orbital trans to the CH bond. Consideration of details of these studies as well as those from large STO based SCF MO wavefunctions by Arrighini et al., suggests that one will need very accurate wavefunctions to resolve the problem unambiguously.The Radiation Laboratory is operated under contract with the U.S. Atomic Energy Commission. This is AEC document no. COO-38-847.     

Synthesis of Pyrimidines,Thienopyrimidines, and Pyrazolopyrimidines

5-Ethoxycarbonyl-4-methyl-2-phenylpyrimidin-6(1H)-thione ( 3 ), which was prepared from the reaction of ethyl g -aminocrotonate 1 with benzoyl isothiocyanate ( 2 ) in refluxing acetone, was reacted with a series of halopgenated reagents to give S-alkyl derivatives 4a-g . Upon treatment of compounds 4a-c with sodium ethoxide were cyclized into thienopyrimidine 10a-c . Pyrimidinethione 3 was reacted with hydrazine hydrate to give hydroxypyrazolopyrimidine derivative 6 . The later compound was obtained by heating compound 4a with hydrazine hydrate under neat conditions, but when the reaction was carried using hydrazine hydrate in ethanol, the corresponding carbohydrazide 5 was produced.     

Electronic structure of Li− and F− calculated directly in momentum space

Summary A self-consistent field method is applied to compute directly in momentum space the electronic structures of the bound anions Li^– and F^– at the Hartree-Fock level. The convergence towards the Hartree-Fock limit, starting from STO-3G, 3–21G, 3–21+G and 6–311+G AO's, is stable and monotonous. Substantial improvement in the quality of the anion orbitals is noted already after one iteration. Particularly interesting is the efficiency with which the method modifies and improves the shape of the trial functions.     

Ab Initio Calculation of Room Temperature Ionic Liquid 1-Ethyl-3-Methyl-Imidazolium Chlorocuprate （I）

The Hartree-Fock method has been employed to investigate the electronic structures of EMIM^＋（1-ethyl-3-methyl-imidazolium^＋）, CuCl2^-, Cu2Cl3^-, CuCl3^2-, EMIM＋^-CuCl2^-, EMIM^＋-Cu2Cl3^-, and EMIM^＋-CuCl3^2- pairs. Full optimization and frequency analyses of EMIM^＋, CuCl2^-, Cu2Cl3^-, CuC13^-, eight initial EMIM^＋-CuCl2^-, six EMIM^＋-Cu2Cl3^-, and four EMIM^＋-CuCl3^2- geometries have been carried out using Gaussian-94 soft-package at 6-31＋G（d,p） basis set level for hydrogen, carbon, nitrogen, chlorine atoms and Hay-Wadt effective core potential for copper atom. The electronic structures of lowest energy of EMIM^＋-CuCl2^-, EMIM＋-Cu2Cl3^-, EMIM^＋-CuCl3^2-, single EMIM^＋, CuCl2^-, Cu2Cl3^-, and CuCl3^2- have been comparatively studied. The calculated results showed that EMIM^＋-CuCl2^- pair conformer of lowest energy was five ring parallel to Cl-Cu-Cl with 3.2A distance, EMIM^＋-CuCl3^2- pair conformer of lowest energy was five ring parallel to CuCl3^2-plane with 3.4A distance, and the optimized EMIM^＋-Cu2Cl3^- pair conformer of lowest energy was five ring perpendicular to Cl-Cu-Cl-Cu-Cl plane with 3.0A distance between the terminal Cl atoms and the 5-ring of EMIM^＋. The cohesion between cations and anions is brought about by C-H. C1 hydrogen bonds that are reinforced by charge assistance. The frequency analyses suggested that all stationary points are minimum because of no appearing of imaginary frequency. The assigned frequencies were in agreement with the experimental report. The low energy of interaction because of the bulkyasymmetry of EMIM＋ and the charge dispersion of cation and anion leads to the low melting point of the ionic liquids, EMIM^＋-CuCl2^-, EMIM^＋-Cu2Cl3^-, and EMIM^＋-CuCl3^2-. The interaction energy of EMIM^＋-CuCl2^-, EMIM^＋-Cu2Cl3^-, and EMIM^＋-CuCl3^2- is 309.0 kJ/mol, 316.8 kJ/mol, and 320.2 kJ/mol, respectively. The relationship of interaction energy via distance between cations and anions was also investigated by single point energy scan.     

1990～1999年湛江市婴幼儿发中Zn、Fe、Ca含量的调查分析

报道了１９９０ ～１９９９ 年湛江市０ ～３ 岁婴幼儿发中Ｚｎ 、Ｆｅ 、Ｃａ 含量的调查分析。结果显示： ①Ｚｎ 、Ｆｅ 、Ｃａ 含量十年的总平均值分别为６９－６２ ×１０ － ６ 、３７－１１ ×１０ － ６ 、５１１－６８ ×１０ － ６ ; 三种元素含量均在１９９０ 年最低, Ｚｎ 、Ｆｅ 含量于１９９３ 年明显升高, Ｃａ 含量于１９９４ 年明显升高, 以后几年趋于平衡; ②０ ～０－５ 岁组的三种元素含量均明显高于其他年龄组（ Ｐ＜ ０－０１ ） , 在其他年龄组中Ｚｎ 、Ｃａ 含量有性别差异（ Ｐ＜ ０－０１ ） 。     

有机非线性光学晶体NPP的AFM研究

有机二阶非线性光学活性晶体的分子设计和晶体工程是复杂而又引人注目的课题．有机非线性光学晶体N一忡硝基苯基）－LWe脯氨醇（NPP）是一个极为成功的自］子山．由于在＊＊P分子中引入了含手性碳原子和可形成分子间氢键的电子给体脯氨醇，使得其分子跃迁偶极矩与单科P21晶体结构的二重轴之间的夹角为586”．接近于理论优化值（54．74”），因此，＊＊P具有很高的宏观二阶非线性光学活性，其粉末二次谐波强度为尿素的150倍．自1984年首次报导以来，对它的晶体生长门和物理性质已进行了广泛深入的研究．原子力显微镜（＊＊M）能够以极高…     

HF molecules and poly(hydrogen fluoride) anions as ligands to metal centers

The paper is dealing with the two sets of the coordination compounds:

• (a) 

  the coordination compounds in which anhydrous HF is acting as a ligand to the metal ions

• (b) 

  the compounds in which poly(hydrogen–fluoride) anions of the type HnFn+1− (n = 1, 2, 3) are coordinated to the metal centers and connecting them in the 3D structures.

The main purpose of this work is the review of the above mentioned compounds which were recently isolated in our laboratory. The coordination of the metal centers and their connection in the three-dimensional network are illustrated with their crystal structures. A very brief review of the achievements of some other groups is also mentioned where it is appropriate.     

重度糖尿病患者血清中金属元素钾,钠,钙,镁的分析

对６０例重度中老年糖尿病患者进行了血清中钾、钠、钙、镁的含量测定，并与正常对照组进行了比较。     

The numerical simulation of the mechanical failure behavior of shear thickening fluid/fiber composites: A review

This study reveals the finite element modeling of mechanical failure behavior of shear thickening fluid (STF)/fiber composites under impact. Numerical analysis and finite element modeling of the rheological properties of non-Newtonian fluid, STF are introduced. This review summarizes the model coupling methods in finite element modeling and the mechanical failure behavior prediction models of STF/fiber composites under impact. Further, the influencing factors on the accuracy of mechanical failure simulation models are analyzed. Factors such as the friction between fibers, shear rate, filler particles in the fibers, hysteresis effect and the boundary conditions should be considered in simulating the shear thickening effect of the composites.     

Highly Efficient Circularly Polarized Luminescence from Chiral Au13 Clusters Stabilized by Enantiopure Monodentate NHC Ligands

Chiral Au nanoclusters have promising application prospects in chiral sensing, asymmetric catalysis, and chiroptics. However, enantiopure superatomic homogold clusters with crystallographic structures emitting bright circularly polarized luminescence (CPL) remain challenging. In this study, we designed chiral N-heterocyclic carbenes (NHCs), and for the first time enantioselectively synthesized a pair of monovalent cationic superatomic Au₁₃ clusters. This new enantiomeric pair of clusters has a quasi-C₂ symmetric core and exhibited CPL with an unprecedent solution-state quantum yield (QY) of 61 % among those of the atomically precise Au nanoclusters. DFT calculations provided insights into the circular dichroism behavior, and revealed the origin of CPL from superatomic Au clusters. This work opens a new avenue for developing novel homochiral nanoclusters using chiral NHC ligands and provides fundamental understanding of the origin of the chiroptics of metal clusters.     

质膜微囊的分离及原子力显微镜研究

采用非去污剂在OptiPrep梯度中漂浮超声处理质膜的方法, 从鼠肺中分离质膜微囊, 在原子力显微镜下以不同条件进行了观察. 该非去污剂法能分离出完整的质膜微囊, 在去离子水稀释500倍的条件下得到了清晰的质膜微囊的原子力显微镜图片, 建立了一种新的快速分离完整质膜微囊的方法和用原子力显微镜观测质膜微囊结构的新方法.     

The influence of micro- and nanoparticles on model atomically flat surfaces on crystallization of polyethylene

Crystallization of high density polyethylene (PE) from the melt on model atomically flat solid surfaces decorated with micro- and nanoparticles of gold or NaCl of different size and densities is investigated. The morphology of the contact layer of PE after its detachment from the support is studied using atomic force microscopy (AFM). It is shown that the nucleating and ordering effect of the solid on PE crystallization depends to a large extend on the nanostructure of its surface, in particular on the size of the atomically flat domains and on the presence of nanoscopic obstacles. The minimum size of the flat domain which can significantly influence the PE crystallization is estimated to be of the order of 150 nm.     

等离子体增强MOCVD法生长ZnO薄膜

利用等离子体增强MOCVD法生长出 ZnO薄膜，用X射线衍射谱观察到位于 2θ34．56°处（0002）的衍射峰，表明ZnO沿c方向呈柱状生长．通过荧光光谱，观察到来自于激子的高强度的近带边紫外光发射（375um）．紫外发射光强度与深能级复合发射光强度比高达 193，显示出材料的高质量，并通过原子力显微镜加以验证．为了实现高阻ZnO薄膜，利用高温富氧分段退火和用N2 气进行掺氮两种方法生长高阻ZnO薄膜．结果表明，电阻率由0．65 Ω·cm分别升高到1100 Ω·cm（分段退火）和5×104Ω·cm（掺氮）．进一步比较发现，掺氮的样品不仅电阻率高，而且光荧光特性好，显示出更高的薄膜质量．     

Electric Field-driven Acid-base Transformation: Proton Transfer from Acid(HBr/HF) to Base(NH3/H2O)

The proton-transfer between ammonia/water and HF/HBr without and with the stimulus of external electric fields(E_ext) was investigated with the ab initio calculations. When external electric field is applied, the proton transfer occurs, resulting in ion-paired H₄N⁺X^- and H₃O⁺X^-(X=Br and F) from hydrogen-bonded complexes in view of the great changes of geometrical structures, dipole moments, frontier molecular orbitals and potential energy surfaces in the critical external electric fields(E_c) of 1.131×107 V/cm for H₃N-HBr, 1.378×108 V/cm for H₃N-HF, 9.358×107 V/cm for H₂O-HBr and 2.304×108 V/cm for H₂O-HF, respectively. Furthermore, one or three excess electrons can trigger the proton transfer from H₃N-HBr and H₃N-HF to H₄N⁺Br^- and H₄N⁺F^-, while two and four excess electrons can induce the proton transfer from H₂O-HBr and H₂O-HF to H₃O⁺Br^- and H₃O⁺F^-, respectively. Compared with that of the analogous NH₃/H₂O-HCl systems, the strength of E_c of proton transfer increases from HBr to HCl and HF for either H₃N-HX or H₂O-HX series, which is understandable by the fact that the acidity sequence is HBr>HCl>HF. And the larger of acidity of conjugated acid, the smaller of needed E_c. On the other hand, the E_c for the systems of NH₃ with a stronger basicity is generally smaller than that of H₂O systems for the same conjugated acid.     

Influence of intramolecular Sn-chalcogen interactions on the conformational preferences for three diorganotin(IV) xanthates

The influence of intramolecular Sn-chalcogen interactions on the stability of different coordination possibilities available for three diorganotin(IV) xanthates [Me₂Sn(MeOCS₂)₂ (1), Ph(Me)Sn(MeOCS₂)₂ (2) and Ph₂Sn(MeOCS₂)₂ (3)] by means of theoretical methods is presented herein. A comparison of results obtained at the RHF level of theory employing STO3G, 3-21G^∗∗ and augmented triple zeta quality basis sets developed for relativistic pseudopotentials is shown. RHF-STO3G all-electron calculations followed by fourth order Møeller-Plesset calculations were carried out in order to study the effect of electron correlation. It was observed that the use of correlation consistent basis sets yielded stability trends which reflect previous observations for similar xanthate molecular systems. The stabilization of the above conformers is assessed through an NBO analysis and the calculation of energy barriers by potential energy surface scans for the conformational changes. The approach described herein improves the theoretical results obtained in [M.I. Mohamed-Ibrahim, S.S. Chee, M.A. Buntine, M.J. Cox, E.R. Tiekink, Organometallics 19 (2000) 5410], where these three compounds were originally reported. It was concluded that secondary bonding in these compounds is best described by means of the computational paradigm herein described.     

Assembly of Two‐Dimensional DNA Crystals Carrying N4‐[2‐(tert‐Butyldisulfanyl)ethyl]cytosine Residues

DNA Lattices carrying two cytosine residues bearing the N⁴‐[(tert‐butyldisulfanyl)ethyl] group at the apex of hairpin topological markers are prepared for first time. We show that these residues are important for the deposition of DNA lattices on gold surfaces.     

La0.67Ca0.33Mn1-xAlxO3体系的结构和输运特性研究

研究了Al离子的Mn位替代对巨磁阻材料La0.67Ca0.33MnO3体系的结构和输运特性的影响。结果表明,随Al3 替代量的增加,在整个替代范围内,晶胞体积表现出单调减小的规律。体系的电阻率急剧增加,绝缘体 金属转变温度TIM向低温方向移动,且与Al3 替代量存在线性关联。对少量Al3 替代量,在T>TIM的高温区域体系的输运特性满足热激活模型,在T相似文献