Studies on the defect structure for Cu2+ in CdSe nanocrystals

The defect structure for Cu²⁺ in CdSe nanocrystals is theoretically studied by analyzing the spin Hamiltonian parameters of this impurity center. This center is ascribed to Cu²⁺ occupying the octahedral interstitial site, rather than the tetrahedral substitutional Cd²⁺ site proposed by previous work. The Cu²⁺ center exhibits slight tetragonal elongation distortion (characterized by the elongation parameter ρ ≈ 0.03) due to the Jahn–Teller effect. The theoretical spin Hamiltonian parameters and optical transition show good agreement with the experimental data. The above unusual defect structure (occupation and symmetry) for Cu²⁺ in CdSe nanocrystals is discussed, as compared with the conventional trigonally distorted tetrahedral Cu²⁺ centers in bulk II–VI semiconductors.     

Law of Large Numbers for Random Walk with Unbounded Jumps and Birth and Death Process with Bounded Jumps in Random Environment

We study a random walk with unbounded jumps in random environment. The environment is stationary and ergodic, uniformly elliptic and decays polynomially with speed \(Dj^{-(3+\varepsilon _0)}\) for some \(D>0\) and small \(\varepsilon _0>0.\) We prove a law of large numbers under the condition that the annealed mean of the hitting time of the lattice of the positive half line is finite. As the second part, we consider a birth and death process with bounded jumps in stationary and ergodic environment whose skeleton process is a random walk with unbounded jumps in random environment. Under a uniform ellipticity condition, we prove a law of large numbers and give the explicit formula of its velocity.     

Studying quantum current magnification in mesoscopic coupling metallic rings

We propose a quantum Hamiltonian and obtain the relationship between external magnetic field and currents of three mesoscopic coupling rings. The impact of coupling on quantum current magnification in the system is studied. It is found that the quantum current magnification effect strongly depend on both the external magnetic flux and the coupling factors. As a result, by taking use of coupling rings, we can design some circuits to transfer and communicate signals.     

磺酰胺型多齿配体的合成

有机金属配合物涉及了许多重要的生命过程,配体和配合物的合成及性质研究都越来越受到人们的重视。磺酰胺类化合物,磺酰胺中氨基氢的酸性可与酚类化合物相比拟,对金属离子有较强的配位能力,并且比酚试剂不易氧化,还可改变磺酰胺的空间体积和亲脂性。本文报道一类新的磺酰胺型多齿配体的合成,并证明它们能与金属离子形成配合物。     

4-R-6-羟甲基-2-[N-(苯并氮杂-15-冠-5)甲基]苯酚的合成及晶体结构

以酚羟基为中心功能基的多齿配体可以络台多种金属离子,形成单核或双核金属络合物。合成含酚羟基多齿配体时,一般总是先把酚羟基用硫酸二甲酯醚化加以保护,在完成其它反应之后,再用去甲基化试剂还原出酚羟基。从原料盼到最终产:品的获得,至少需要进行五步反应。我们采用不保护酚羟基的合成路线,     

In situ preparation of poly(ethylene terephthalate)-SiO2 nanocomposites

Poly(ethylene terephthalate) (PET)/silica nanocomposites were synthesized by using the in situ polymerization approach. Sol-gel transformation based on the hydrolysis and condensation of tetraethoxysilane (TEOS) is used to prepare the inorganic phase, concurrent with condensation polymerization of terephthalic acid and ethylene glycol to produce the PET matrix. Due to the simultaneous formation of the polymer matrix and the inorganic networks, a macrophase separation is avoided, and the resulting materials have a high degree of homogeneity. The morphology and the crystallization behavior of the composites were examined by scanning electron microcopy (SEM) and differential scanning calorimetry (DSC), respectively.     

脂肪族方酰胺多齿配体的合成

曾合成并研究了以1,3-双苯氨基方酸内翁盐为骨架,在苯环的2-位对称引入多甘醇醚链的双臂型方酰胺多齿配体,其中某些化合物既能作为配体对UO~2^2^+及ZγO^2^+等刚性离子配位,又能与配体NH~3发生作用,以它作为中性载体的氨选择性电极可望用于NH~3的测定。在脂肪胺的方酸内翁盐型多齿配体中,因无芳环的共轭,四碳环及其上氧之电荷状态将有所不同,这必将影响整个分子的性质。本文对这类化合物的合成进行探索,找到了行之有效的合成方法,并由此制得了九个方酰胺配体5(a～i),其中5i可作为聚酰胺等的稳定剂,其余均未见文献报道。     

2,5-二取代芳基-1,3,4-噻二唑衍生物的微波法合成

在微波辐射下，Lawesson试剂与相应的二芳基甲酰肼反应，生成2，5-二芳基-1，3，4-噻二唑衍生物．反应时间短，产率高．所有产物结构经^1H NMR，IR，MS和元素分析确认．     

N-丁基马来酰亚胺/苯乙烯微乳液共聚合研究

研究了氘代氯仿中Ｎ－丁基马来酰亚胺（ＮＢＭＩ）和苯乙烯（Ｓｔ）的络合性能。以十二烷基硫酸钠（ＳＤＳ）和正戊醇（ＰＴＬ）为复合乳化剂,配制了含有ＮＢＭＩ（Ｍ１）和Ｓｔ（Ｍ２）的Ｏ／Ｗ微乳液。用过硫酸钾引发该体系进行微乳液共聚合。固定乳化剂的浓度为〔ＳＤＳ〕＝０．２１ｍｏｌ／Ｌ,〔ＰＴＬ〕＝０．２８ｍｏｌ／Ｌ,详细研究了聚合温度、单体配比和引发剂用量对共聚合动力学的影响。用元素分析法确定共聚物的组成,     

On signed majority total domination in graphs

We initiate the study of signed majority total domination in graphs. Let G = (V, E) be a simple graph. For any real valued function f: V and S V, let . A signed majority total dominating function is a function f: V {–1, 1} such that f(N(v)) 1 for at least a half of the vertices v V. The signed majority total domination number of a graph G is = min{f(V): f is a signed majority total dominating function on G}. We research some properties of the signed majority total domination number of a graph G and obtain a few lower bounds of .This research was supported by National Natural Science Foundation of China.