B12-nAlnN12 (n=0, 6, 12) 的稳定性和电子结构研究

通过Al取代B在B12N12中掺杂,基于密度泛函理论对B6Al6N12的稳定性进行了系统研究．表明在B6Al6N12中,Al和B倾向于相对分开．在最稳定结构中,B原子和Al原子分别处在笼的两半．我们还分析了B12-nAlnN12 (n=0, 6, 12)的电子结构,B12N12的能隙为6.84eV,掺Al后其能隙明显变窄,Al12N12和B6Al6N12的能隙分别为3.91eV和4.08eV．NBO分析表明,B12N12中B/N原子的电荷分别为±1.17,Al12N12中Al/N 原子的电荷分别为±1.85．在B6Al6N12中,B/Al原子上的电荷分别为1.06~1.12和1.86~1.91,N原子上的电荷为-1.18~-1.83．     

B12-nAlnN12 (n=0, 6, 12) 的稳定性和电子结构研究

通过Al取代B在B12N12中掺杂,基于密度泛函理论对B6Al6N12的稳定性进行了系统研究．表明在B6Al6N12中,Al和B倾向于相对分开．在最稳定结构中,B原子和Al原子分别处在笼的两半．我们还分析了B12-nAlnN12 (n=0, 6, 12)的电子结构,B12N12的能隙为6.84eV,掺Al后其能隙明显变窄,Al12N12和B6Al6N12的能隙分别为3.91eV和4.08eV．NBO分析表明,B12N12中B/N原子的电荷分别为±1.17,Al12N12中Al/N 原子的电荷分别为±1.85．在B6Al6N12中,B/Al原子上的电荷分别为1.06~1.12和1.86~1.91,N原子上的电荷为-1.18~-1.83．     

{Cu2[C12H18N2O7S]2[C10H8N2]}n聚合物的合成及晶体结构

采用铜(Ⅰ)盐和邻香草醛缩氨基甲磺酸席夫碱以及4,4'-联吡啶在乙醇溶液中合成了具有三维网状的配位聚合物,通过元素分析、红外光谱对配位聚合物进行了表征,并利用X射线单晶衍射仪对其结构进行了鉴定.晶体结构分析表明,该标题配合物属单斜晶系,空间群P2(1)/c,晶胞参数为a=1.1956nm,6=0.8464nm,c=2....     

(C_5H_(11)N_2)~+和(C_7H_(12)N_2)~(2+)的NMR研究

结合1H NMR,13C NMR谱,分别对钨、钼配合物{WO2(C10H6O2)2(C5H11N2)2[H2N(CH2)3NH2]}3(1),{(C5H11N2)2[H2N(CH2)3NH2][MoO2(C10H6O2)2]}(2),{(C7H12N2)2[MoO2(C10H8O2)2]}(3)晶体结构中小分子环进行了归属.其中,配合物1和2中(C5H11N2)+的NMR研究证实了六元环由1,3-丙二胺和乙腈化合而成,配合物3中(C7H12N2)2+的NMR谱图证实了七元环由乙二胺和乙酰丙酮化合而成,并且推导出这些亲核加成-消除反应的反应机理.配合物1~3中的小分子环的合成在其它体系中尚未见报导,而在合成它们的反应中作为新产物随主体晶体析出,并由晶体结构解析和NMR得到了证实.     

乙炔-氧气混合气体强爆轰参数的理论估算与实验研究

 针对非定常的气相强爆轰过程,建立了气相爆轰的理论计算模型,结合C-J理论和多方气体物态方程,对乙炔-氧气混合气体的强爆轰参数进行了理论估算,并在激波管中开展了化学计量比的乙炔-氧气混合气体的强爆轰实验。对比研究表明：爆速的理论估算值与实验值符合较好,证实了采用C-J理论估算气相强爆轰参数的可行性,计算数据具有一定的参考价值。     

Simulation of nanoparticle coagulation in radio-frequency C_2H_2/Ar microdischarges

The nanoparticle coagulation is investigated by using a couple of fluid models and aerosol dynamics model in argon with a 5% molecular acetylene admixture rf microdischarges,with the total input gas flow rate of 400 sccm.It co-exists with a homogeneous,secondary electron-dominated low temperature γ-mode glow discharges.The heat transfer equation and flow equation for neutral gas are taken into account.We mainly focused on investigations of the nanoparticle properties in atmospheric pressure microdischarges,and discussed the influences of pressure,electrode spacing,and applied voltage on the plasma density and nanoparticle density profiles.The results show that the characteristics of microdischarges are quite different from those of low pressure radio-frequency discharges.First,the nanoparticle density in the bulk plasma in microdischarges is much larger than that of low pressure discharges.Second,the nanoparticle density of 10 nm experiences an exponential increase as soon as the applied voltage increases,especially in the presheath.Finally,as the electrode spacing increases,the nanoparticle density decreased instead of increasing.     

Powder x-ray diffraction and Rietveld analysis of (C_2H_5NH_3)_2CuCl_4

Structural properties of the organic-inorganic hybrid(C_2H_5NH_3)_2CuCl_4 have been investigated by means of x-ray powder diffraction and Rietveld analysis. A structural phase transition from Pbca to Aba2 occurs at T_4= 240 K, which results in a paraelectric–ferroelectric phase transition. The release of the Jahn–Teller distortion with increasing temperature toward T_4 is revealed by the structural analysis.     

一些含-CH2CH2N(CH3或C2H5)2基团的药物对辐照红细胞膜中硫代巴比妥酸反应物及超弱化学发光强度的影响

用硫代巴比妥酸反应的荧光分析法和超微弱发光法检测了十种含—CH_2CH_2N(CH_3或C_2H_5).基团的临床应用药物对辐照膜脂过氧化的影响,结果表明绝大多数被试药物有较强的抗膜脂过氧化作用.此外,黄嘌吟-黄嘌吟氧化酶系统的实验表明部分被试药物具有较强的减少O_2的能力.对药物结构与其抗膜脂过氧化效率之间的关系进行了初步探讨,结果提示:具有多元环及一正电中心的—CH_2CH_2N(CH_3或C_2H_5)_2化合物可能多为膜脂过氧化的抑制物.     

[Co(H2O)4(NCS)2](18-C-6)配合物的NMR研究

该文测定了最近合成的[Co(H₂O)₄(NCS)₂](18-C-6)的¹H、¹³C、¹⁴N核磁共振谱,验证了其配合物的结构,并用红外光谱(IR)作了进一步的确定.     

N2（A）及N（2D）对IF（X）的传能研究

在微波放电系统中,对NH_3-F-F_2-CF_3I体系进行研究,结果表明,向IF(X)传能的诸多媒介中,N_2(A)及N(~2D)起着主要作用,并且这一结论在经微波激发后的N_2与CF_3I的直接反应中得到了进一步证实。     

维生素B12的激光共振拉曼光谱研究

本文用激光共振拉曼光谱研究了维生素Ｂ１２位于２７０－７８０ｃｍ＾－１的低频振动光谱。认为３４４，４７６和４８８ｃｍ＾－１拉曼峰分别是腺嘌呤，Ｃｏ－ＣＮ和Ｃｏ－ＣＨ３振动模。用实验证明了维生素Ｂ１２在５１４．５ｎｍ激光作用下发生部分光解，而且Ｃｏ－ＣＨ３比Ｃｏ－ＣＮ更容易断裂。测得了光照Ｂ１２后光解速曲线。     

Mode transition in dusty micro-plasma driven by pulsed radio-frequency source in C_2H_2/Ar mixture

Physical qualities of dusty plasma in the pulsed radio-frequency C_2H_2/Ar microdischarges are carefully investigated by a one-dimensional hydrodynamic model and aerosol dynamics model.Since the thermophoretic force has a great effect on the nanoparticle density spatial distribution,the neutral gas energy equation is taken into accounted.The effects of pulse parameters(dust ratio,modulation frequency) on the nanoparticle formation and growth process are mainly discussed.The calculation results show that,as the duty ratio increases,the mode transition from the sheath oscillation(a regime) to the secondary electron heating(7 regime) occurred,which is quite different from the conventional pulsed discharge.Moreover,the effect of modulation frequency on the width of sheath and plasma density is analyzed.Compared with the H_2CC~-ions,the modulation frequency effect on the nanoparticles density becomes more prominent.     

High-temperature Raman spectroscopic study of vanadoborate Na_3VO_2B_6O_(11)

Raman spectra of a vanadoborate(Na3VO2B6O11) crystal from room temperature up to the melting point have been recorded. The main internal vibrational modes of the crystal have been assigned. It was found that all the Raman bands exhibit decreases in frequency and the widths of the Raman bands increase with the increase of temperature. However,no phase transition was observed under 525℃. The micro-structure of its melt was studied by quantum chemistry ab initio calculation. The continuous three-dimensional network of the crystal collapsed and transformed into VO_4 and VBO_6 clusters during the melting process with an isomerization reaction from four-coordinated boron to a three-coordinated species.     

氢分子在Mg2Ni(010)面的吸附与分解

本文采用基于密度泛函理论(DFT)的第一原理赝势平面波(PW-PP)方法,对氢分子在Mg2Ni(010)面的吸附与分解进行了研究,我们发现氢分子以Hor1的方式吸附在表面层Ni原子的顶位时吸附能最高,为0.6769eV,这表明氢分子最可能以Hor1的方式吸附在表面层Ni原子的顶位,此时氢分子跟表面的距离( )和氢分子的键长( )分别为1.6286Å和0.9174Å. 在分子吸附的基础上计算了氢分子沿着选取的反应路径分解时的反应势垒,发现要使氢分子分解需要0.2778eV的活化能,而氢分子分解时的吸附能为0.8390eV,分解后两个氢原子的距离为3.1712Å. 在分子吸附和分解吸附时氢原子跟正下方的Ni原子都有较强的相互作用,氢原子所得到的电子主要来自氢分子正下方的Ni原子.     

不同LET 12C6+离子对生防菌BJ1的辐射诱变效应

选取高低两个LET点(40和60keV/m),剂量点分别为50,100,200,400,600Gy进行辐照处理,研究了生防菌的存活率与突变率的关系,抑菌谱以及活性等。结果表明,在高LET条件下,低剂量辐照就可以得到较多的突变体,并且BJ1有较高的存活率和突变谱,有利于筛选优良的正突变体。因此高LET较低LET有更为明显的辐射诱变效应。     

Measurement of the total reaction cross section for the mirror nuclei ~(12)N and ~(12)B

The mirror nuclei 12N and 12B are separated by the Radioactive Ion Beam Line in Lanzhou(RIBLL) at HIRFL from the breakup of 78.6 MeV/u 14N on a Be target.The total reaction cross-sections of 12N at 34.9 MeV/u and 12B at 54.4 MeV/u on a Si target have been measured by using the transmission method.Assuming 12N consists of a 11C core plus one halo proton,the excitation function of 12N and 12B on a Si target and a C target were calculated with the Glauber model.It can fit the experimental data very well.The ch...     

Quantitative assessment of reparameterized PM6 (rPM6) for hydrogen abstraction reactions

In the present study, the usability of semiempirical quantum mechanical methods for calculating bond dissociation energy (BDE) was investigated systematically. Density functional theory (DFT) methods with the B3LYP and B97-1 functionals were used for comparison. We introduced a new test set for BDE, called BDE200, which covers a wide range of compounds including large aromatic compounds. The use of BDE200 test set revealed that the accuracy of the methods studied was ordered from best to worst as: B97-1 > B3LYP > rPM6 >> PM7 > PM6 > AM1 > PM3. In addition to the improved accuracy of rPM6 for predicting BDE, it was found that rPM6 can provide a quantitative correlation between BDE values and reactivity. The rPM6 calculated activation enthalpies for C–H hydroxylation catalysed by the compound I of cytochrome P450 were proportional to the calculated and experimental C–H BDE values, in line with the results of previous DFT studies. We believe that rPM6 can help develop a database, for instance, for the determination of site of metabolism.     

H2S在五边形BCN上的吸附与解离的第一性原理计算研究

基于密度泛函理论的第一性原理计算方法,研究了H2S分子在五边形BCN上的吸附与解离过程. 研究结果表明,五边形BCN结构的B原子是H2S分子的最稳定的活性吸附位点. H2S分子在该活性位点极易解离,其初步解离过程为放热反应且分解势垒仅为0.208 eV,并形成稳定的HS/H产物. 深入研究发现,H2S分子初步解离后的五边形BCN表面,可直接分解后续吸附的H2S分子. 该研究结果为五边形BCN对H2S分子的吸附解离机制提供理论借鉴,并且首次提出五边形BCN可作为功能性材料净化有害气体H2S的理想候选者.     

Aromaticity of Heterofullerenes C18BxNy (x+y=2) and Their Molecular Ions

采用拓扑共振能(TRE)和百分拓扑共振能(%TRE)方法研究了从富勒烯C20(Ih)产生的异质富勒烯C18N2、C18B2和C18BN的所有可能的异构体和分子离子的芳香性．讨论了C18BxNy异构体的芳香性和杂原子在C20(Ih)中取代位置间的关系．结果表明,中性状态和阳离子状态时各异构体的TRE都为负值,具有反芳香性．但它们高价阴离子的TRE都为正值,具有芳香性．C18N2、C18B2 和C18BN中都是杂原子在1,11-取代的异构体最稳定．异质富勒烯都比C20的芳香性高．在中性状态下的稳定性顺序为C18N2>C18BN>C18B2>C20．在形成闭壳层结构时的稳定性顺序为C18B28->C206->C18BN6->C18N24-．理论上预测C22BxNy的高价阴离子具有很高的芳香性．     

C6H6分子振动能谱的涨落统计特征

分析了C6 H6 分子振动能谱的涨落统计特征 .研究结果显示 ,C6 H6 分子振动能谱的涨落统计特征属于低Poisson型 ,即谱刚度值大于Poisson型与Wigner型 ,而能谱分维函数值则小于Poisson型与Wigner型 ,这是一种与通常的Poisson型、Wigner型完全不同的类型 ,该特性在一定程度上反映了C6 H6 分子结构的特殊性 .