陨石矿物中微包裹体及陨石微结构的研究

本文利用电子显微镜对不同的陨石样品进行观察研究,发现了陨石中有小于1微米的原生及次生微包裹体;在吉林、东台、溧水的陨石及熔壳中,观察到多种不同成因的微结构类型,反映出陨石在形成至陨落过程中经历了凝聚、熔融、旋转、冷凝及星体间撞击等作用。为了探讨陨石陨落时的溶融特征及温度,对陨石样品加温后,在电子显微镜下观察,结果表明,不同温度下的陨石样品具明显不同的熔融结构,吉林陨石在900-1050℃产生熔融。     

Memristance controlling approach based on modification of linear M–q curve

The memristor has broad application prospects in many fields, while in many cases, those fields require accurate impedance control. The nonlinear model is of great importance for realizing memristance control accurately, but the im- plementing complexity caused by iteration has limited the actual application of this model. Considering the approximate linear characteristics at the middle region of the memristance-charge （M-q） curve of the nonlinear model, this paper pro- poses a memristance controlling approach, which is achieved by linearizing the middle region of the M-q curve of the nonlinear memristor, and establishes the linear relationship between memristances M and input excitations so that it can realize impedance control precisely by only adjusting input signals briefly. First, it analyzes the feasibility for linearizing the middle part of the M-q curve of the memristor with a nonlinear model from the qualitative perspective. Then, the lin- earization equations of the middle region of the M-q curve is constructed by using the shift method, and under a sinusoidal excitation case, the analytical relation between the memristance M and the charge time t is derived through the Taylor series expansions. At last, the performance of the proposed approach is demonstrated, including the linearizing capability for the middle part of the M-q curve of the nonlinear model memristor, the controlling ability for memristance M, and the influence of input excitation on linearization errors.     

非线性力学中的比较原理与应用

本文研究一类无限维非线性力学系统,即具有有限时间滞后的泛函微分方程描述的系统.建立了一类ЛРЧ型比较原理,并将其应用于时间滞后系统的平均原理及其在两种度量下的实用稳定性问题.     

苯和1-辛烯对Ce（Ⅳ）Y分子筛选择性吸附脱硫的影响

选取苯和1-辛烯作为模拟汽油中的芳烃和烯烃,分别研究它们对Ce(Ⅳ)Y分子筛选择性吸附脱硫的影响.结果表明,吸附剂的选择性吸附脱硫性能随着模拟油中苯和1-辛烯含量的增加而显著降低.借助傅立叶变换红外光谱(FT-IR)、紫外漫反射光谱(UV-DRS)技术研究发现.Ce(Ⅳ)Y分子筛对苯和1-辛烯的吸附模式及影响脱硫的机理是不同的.Ce(Ⅳ)Y分子筛阳离子和苯形成π络合作用,作用力较弱,容易脱附;而与1-辛烯的双键发生σ-π络合,不容易脱附.在Ce(Ⅳ)Y分子筛选择性吸附含苯模拟油中的硫化物时,由于苯的存在,苯和噻吩在分子筛表面存在严重竞争吸附,影响了吸附剂的选择性脱硫.而在含1-辛烯的模拟油中,由于1-辛烯直接和分子筛发生强相互作用,占据了吸附剂的活性位,导致Ce(Ⅳ)Y分子筛的脱硫性能显著降低.     

Highly efficient construction of spirocyclic chromanone-pyrrolidines via Cu(I)/TF-BiphamPhos-catalyzed asymmetric 1,3-dipolar cycloaddition

A facile synthesis of highly functional spiro-[4-chromanone-3,3'-pyrrolidine] bearing one unique spiro quarternary and three tertiary stereogenic centers is developed in excellent stereoselectivity for the first time.     

以4,4′-二(苯并咪唑-1-甲基)联苯及邻苯二甲酸根构筑的锌配位聚合物的合成、晶体结构及荧光性质(英文)

水热法合成了1个新的锌配位聚合物[Zn(bbmb)(Pht)]n(bbmb=4,4′-二(苯并咪唑-1-甲基)联苯;H2Pht=邻苯二甲酸),对其进行了红外光谱、元素分析、PXRD和TGA等表征,并用X-射线单晶衍射法测定了配合物的单晶结构。该配合物属单斜晶系,P21/c空间群,为二维层状结构。晶胞参数为a=1.085 28(10)nm,b=2.286 7(2)nm,c=1.218 53(12)nm,β=102.589(3)°,V=2.951 3(5)nm3,Z=4。室温固态荧光测试显示,配合物在416 nm(λmax)具有强的荧光吸收。     

风沙运动的电场-流场耦合模型及气固两相流数值模拟

沙尘暴和尘卷风等风沙运动的静电场是空气流场中沙粒间的碰撞摩擦带电及沙粒粒径的分层效应引起的, 本文耦合沙粒摩擦荷电模型和风沙运动气固两相流模型, 提出了离散单元法与计算流体动力学结合的数值方法. 数值模拟计算表明电荷呈中性的沙粒临界直径为300 μm; 在充分发展的水平风沙流中, 细小的沙粒带负电, 较大直径的沙粒带正电, 所模拟的沙粒带电的荷质比及水平风洞试验段的电场强度与实验测量值一致, 验证了风沙运动的电场-流场耦合模型及数值计算方法的合理性. 本文基于沙粒摩擦荷电机理的风沙运动气固两相流模型提供了理解风沙运动静电场产生的一种物理机理.     

插入生长AlGaAs薄膜对InAs量子点探测器性能的影响

利用分子束外延生长获得的两个InAs量子点样品制备了n型的量子点红外探测器.对于其中一个器件,在InAs量子点有源区的底部和顶部分别插入生长了AlGaAs势垒层.利用透射电阻显微技术研究了两个样品的结构特性;利用光致发光光谱和光电流谱研究了两个器件的光电性质.实验结果表明,AlGaAs层的插入对器件的探测性质有显著的影响.利用有三维效质量近似模型的计算结果,指认了带内光电流谱中峰结构的起源. 关键词： InAs 量子点 AlGaAs薄膜 光致发光光谱 有效质量近似模型     

Broadening of Photoluminescence by Nonhomogeneous Size Distribution of Self-Assembled InAs Quantum Dots

The photoluminescence spectrum （PL） of InAs quantum dots （QDs） at 80 K is studied by comparison between the theoretical calculation and experimental measurement. The Gaussian line shape is used to approximate the size distribution of QDs. Its mean volume and the standard full width at half maximum （FWHM） of the PL spectrum. size deviation are well correlated with the peak and The experimental PL spectrum is well reproduced by the theoretical model based on the effect mass approximation including the size distribution without any adjustable parameters. Compared with the standard size deviation value σ = 9 × 10^-2 determined by atomic force microscopic method a small value σ = 7 × 10^-2 is obtained by the best fitting process from the measured and calculated PL spectra.     

Synthesis and Characterization of Transition Metal Methanesulfonates and their Catalytic Behavior in Biginelli Reactions

A series of transition metal methanesulfonates were prepared and characterized by FTIR and TG. Characteristic peaks for the methyl and sulfonyl groups were observed in the i.r. spectra. The number of crystal waters and the process of dehydration and decomposition were determined by TG. The catalytic behavior of transition metal methanesulfonates in Biginelli one-pot cyclocondensation of aldehydes, 1,3-dicarbonyl compounds and urea in absolute EtOH under refluxing temperatures was investigated. The products, 3,4-dihydropyrimidinones, were characterized by elemental analysis, ¹H n.m.r. and FTIR. The experimental results showed transition metal methanesulfonates were efficient for the Biginelli reaction.