从静电作用探讨化学键的本质及其教学实践

当前中学的化学键教学中，过分强调Lewis“八隅体结构”，忽视静电作用力，导致学生不能认识到化学键的本质，且传统教学方法中，元素的二分法导致化学键的二分法，不利于学生思维的发展。借鉴国外相关研究，在考虑学生认知水平的基础上，尝试从强调化学键静电作用的本质和引入电负性的角度设计教学内容，帮助学生构建正确的化学键本质观。     

Applications of the Differential Calculus to Nonlinear Elliptic Operators with Discontinuous Coefficients

The paper concerns Dirichlet’s problem for second order quasilinear non-divergence form elliptic equations with discontinuous coefficients. We start with suitable structure, growth, and regularity conditions ensuring solvability of the problem under consideration. Fixing then a solution u ₀ such that the linearized at u ₀ problem is non-degenerate, we apply the Implicit Function Theorem. As a result we get that for all small perturbations of the coefficients there exists exactly one solution u ≈ u ₀ which depends smoothly (in W ^2,p with p larger than the space dimension) on the data. For that, no structure and growth conditions are needed and the perturbations of the coefficients can be general L ^∞-functions of the space variable x. Moreover, we show that the Newton Iteration Procedure can be applied in order to obtain a sequence of approximate (in W ^2,p ) solutions for u ₀.     

编码式光纤光栅传感阵列解调方案的论证

介绍了编码式光栅传感阵列的结构及其传感信号的特点。采用梳状结构对编码式光纤光栅传感阵列进行解调，利用被测光谱通过阵列波导光栅不同通道时输出的不同光强的比值确定被测光的波长。该文分别从理想状态和存在背景反射的状态论证了本文提出的方案的可行性，分析了噪声引起的误差。该系统不但适合于解调大容量的波长信息，而且在解调时不存在任何机械移动部分便可以快速、同时测量多个波长。     

一种对中子相对不灵敏的大动态脉冲γ辐射探测器

使用CeF₃闪烁体配以CHT3,CHT5型大线性电流光电倍增管,组合成光电探测器.实验测量表明:CeF₃光电探测器对⁶⁰Coγ灵敏度约为常规塑料闪烁体ST401探测器的0.5—0.6倍,而对于脉冲DT中子,CeF₃探测器灵敏度相对于同尺寸闪烁体ST401探测器的灵敏度低约1个量级,探测器线性电流大于1.5A,暗流小于10nA,是一种对中子相对不灵敏的大动态脉冲γ辐射探测器.     

电负性与原子价层轨道能

用密度泛函理论论证了原子价层轨道能与元素电负性之间的密切关系，说明如何用原子价层轨道能对元素电负性的概念进行解释，从而使周期表中元素电负性更容易被理解和计算。     

Preparation of Dodecyl Dimethyl Benzyl Ammonium Bromide-Doped Cubic CaCO<Subscript>3</Subscript> with Antibacterial Properties

CaCl₂ encapsulated was placed in the hydrothermal reactor of an aqueous solution of Na₂CO₃ and dodecyl dimethyl benzyl ammonium bromide for synthesis of two samples of calcium carbonate by an improved hydrothermal method and one-pot method. Their crystal structure, morphology, chemical composition, and thermal stability of the synthesized samples of calcium carbonate were investigated by XRD, FTIR, SEM, EDS and TGDSC. The sterilization activity of the as-prepared samples was evaluated by killing of Sarcina lutea bacteria. The results indicated that the regular cube capsule-assisted calcium carbonate prepared by hydrothermal process was doped with dodecyl dimethyl benzyl ammonium bromide. Under the same condition, the spindle-shaped calcium carbonate synthesized the one-pot method was not doped with dodecyl dimethyl benzyl ammonium bromide. Among the samples of calcium carbonate, capsule-assisted calcium carbonate had shown better antibacterial effect for Sarcina lutea: in 48 h after its inhibition a zone diameter was 12.3 mm.     

BrO-H2O 及 HOBr-H2O复合物偶合方式的理论研究

在6-311++G(d,p)水平上采用四种方法讨论了两种BrO-H₂O和三种HOBr-H₂O复合物的构型性质。在两种BrO-H₂O复合物中，结合能为11.37–13.92 J/mol的复合物2 （电子态为²A′）最稳定，该复合物是通过BrO中的Br原子和水中的O原子结合的。三种HOBr-H₂O复合物中，复合物3和4的结合能约为16.30–21.32 J/mol，三种复合物的稳定顺序为：复合物3 ≈ 复合物4 > 复合物5。     

具有U构型的二{1-甲硫基-1-[1-苯基-1-(1-苯基-3-甲基-5-氧代-4,5二氢吡唑-4-烯)-甲氨基]亚氨甲基}二硫醚的晶体结构

The reaction of 1-phenyl-3-methyl-4-benzoyl-2,5-dihydro-1H-pyrazol-5-one (PMBP) and methyldithiocarbazate (mdtc) in methanol results in formation of a yellow crystalline solid, adduct of 1-phenyl-3-methyl-4benzoyl-2,5-dihydro-lH-pyrazol-5-one and methyldithiocarbazate. When the yellow solids were dissolved in a mixture of methanol and ether (1:4), a red crystal, which is an oxidation product of the former, was obtained by allowing solvent to evaporate for a few days at room temperature. The X-ray analysis of the red crystal indicates that it is a novel disulfide with a special structure like a “U” conformation in the solid state.     

Direct measurement of the energy thresholds to conformational isomerization in tryptamine: experiment and theory

The methods of stimulated emission pumping-hole filling spectroscopy (SEP-HFS) and stimulated emission pumping population transfer spectroscopy (SEP-PTS) were applied to the conformation-specific study of conformational isomerization in tryptamine [TRA, 3-(2-aminoethyl)indole]. These experimental methods employ stimulated emission pumping to selectively excite a fraction of the population of a single conformation of TRA to well-defined ground-state vibrational levels. This produces single conformations with well-defined internal energy, tunable over a range of energies from near the zero-point level to well above the lowest barriers to conformational isomerization. When the SEP step overcomes a barrier to isomerization, a fraction of the excited population isomerizes to form that product. By carrying out SEP excitation early in a supersonic expansion, these product molecules are subsequently cooled to their zero-point vibrational levels, where they can be detected downstream with a third tunable laser that probes the ground-state population of a particular product conformer via a unique ultraviolet transition using laser-induced fluorescence. The population transfer spectra (recorded by tuning the SEP dump laser while holding the pump and probe lasers fixed) exhibit sharp onsets that directly determine the energy thresholds for conformational isomerization in a given reactant-product conformer pair. In the absence of tunneling effects, the first observed transition in a given X-Y PTS constitutes an upper bound to the energy barrier to conformational isomerization, while the last transition not observed constitutes a lower bound. The bounds for isomerizing conformer A of tryptamine to B(688-748 cm(-1)), C(1)(860-1000 cm(-1)), C(2)(1219-1316 cm(-1)), D(1219-1282 cm(-1)), E(1219-1316 cm(-1)), and F(688-748 cm(-1)) are determined. In addition, thresholds for isomerizing from B to A(<1562 cm(-1)), B to F(562-688 cm(-1)), and out of C(2) to B(<747 cm(-1)) are also determined. The A-->B and B-->A transitions are used to place bounds on the relative energies of minima B relative to A, with B lying at least 126 cm(-1) above A. The corresponding barriers have been computed using both density functional and second-order many-body perturbation theory methods in order to establish the level of theory needed to reproduce experimental results. While most of the computed barriers match experiment well, the barriers for the A-F and B-F transitions are too high by almost a factor of 2. Possible reasons for this discrepancy are discussed.     

红外碳硫测定仪测定铁矿石中硫

采用红外碳硫仪对铁矿石中硫进行测定，通过对助熔剂各类、助熔剂的加入量，助熔剂的比例，称样量、试样加入顺序等条件进行试验，选择了测定铁矿石中硫的最佳条件，此法的测定范围为0．01％－4．0％。