Carbohydrate-based nanostructured catalysts: applications in organic transformations

The requirement of green and sustainable materials to prepare heterogeneous catalysts has intensified for practical reasons over the past few decades. Carbohydrates are possibly the most plentiful and renewable organic materials in nature with inimitable physiochemical properties, plausible low-cost and large-scale production, and sustainability features could be exploited in the generation of nanostructured heterogeneous catalysts. This review article outlines the organic transformations catalyzed by diverse carbohydrate-based nanostructured catalysts in greener and environmentally friendly processes. Selected examples are highlighted for a variety of organic reactions exploiting the proposed catalysts’ reactivity and reusability, and interactions with the intrinsic nature of the applied carbohydrate supports; advantages and speculated challenges of the introduced catalysts are deliberated as well.     

Some Theorems on Leibniz n-Algebras from the Category Un(Lb)

We study the Leibniz n-algebra Un(∑),whose multiplication is defined viathe bracket of a Leibniz algebra ∑ as[x1,...,xn]=[x1,[...,[xn-2,[xn-1,xn]]...]].Weshow that Un(∑) is simple if and only if ∑ is a simple Lie algebra.An analog of Levi'stheorem for Leibniz algebras in Un(Lb) is established and it is proven that the Leibnizn-kernel of Un(Σ) for any semisimple Leibniz algebra Σ is the n-algebra Un(Σ).     

外腔反馈对半导体激光器振荡特性的影响

通过有效反射系数的引入，根据激光谐振腔的自再现条件和对腔内光子密度、载流子密度方程的求解，分析了外腔反馈对半导体激光器的阈值增益、振荡频率和输出功率等振荡特性的影响，并通过实验进行了验证.外腔反馈后，半导体激光器的阈值电流从420mA降为370mA，输出功率的斜率效率获得了提高，理论计算的输出功率曲线与实验结果符合的很好. 关键词： 半导体激光器 外腔反馈 振荡特性     

稀掺杂GaNxAs1－x(x≤0.03)薄膜的调制光谱研究

利用室温下压电调制反射光(PzR)谱技术系统测量了N掺杂浓度为0.0%—3%的分子束外延生长GaN_xAs_1-x薄膜，并对图谱中所观察的光学跃迁进行了指认.在GaN_0.005As_0.995和GaN_0.01As_0.99薄膜的PzR谱中观察到此前只在椭圆偏振谱中才看到的N掺杂相关能态E₁+Δ₁+Δ_N.当N掺杂浓度达到 关键词： 压电调制反射光谱(PzR) xAs_1-x薄膜')" href="#">GaN_xAs_1-x薄膜 分子束外延(MBE)     

On Best Approximations from RS-sets in Complex Banach Spaces

The concept of an RS-set in a complex Banach space is introduced and the problem of best approximation from an RS-set in a complex space is investigated. Results consisting of characterizations, uniqueness and strong uniqueness are established,     

LAXS investigation of finger phantoms

Osteoporosis is a bone condition that is caused mainly by the degradation of trabecular and cortical bone resulting in the decrease of bone strength and eventually leads to bone fracture. A low angle X-ray scattering (LAXS) system that uses mainly the coherent scattering process for the characterisation of materials was constructed to study such bone conditions. Several finger phantoms were fabricated to simulate bone of varying densities. The LAXS method was able to identify the changes in bone density quite well by comparing energy dispersive X-ray diffraction patterns as well as the angular patterns. Quantitative information can be extracted from such patterns that relate to bone loss. Signature patterns at low exposure times were produced in order to reduce the dose received with reasonable identification power but at slightly higher statistical errors compared with long exposure patterns. Use of other parameters to increase the sensitivity was attempted.     

Thermal behavior of metallodendrimers possessing bis(terpyridinyl)Ru(II) connectivity and different surface functionality

A series of metallodendrimers, assembled by means of bis(terpyridinyl)Ru^(II) connectivity on poly(propylene imine) dendrimer scaffolds, with homogeneous or heterogeneous surfaces, were prepared. Differential scanning calorimetry and thermogravimetric analysis were used to determine their thermal behavior, glass‐transition temperatures, and the decomposition kinetics and temperatures; no synergy effects for these properties were observed for the heterogeneously surfaced constructs in contrast to the corresponding homogeneously coated materials, which exhibited different values depending on their surface functionalities. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1487–1495, 2004     

p+209Bi核反应微观数据的理论计算

利用光学模型、激光模型、蒸发模型及扭曲波玻恩近似理论,对入射能量从阈能到300MeV,p+²⁰⁹Bi的中子反应截面、剩余核截面、出射粒子的多重数进行了理论计算及分析,并将计算结果与实验数据进行了比较.同时得到一组能量到50?0MeV与实验数据符合很好的光学势参数.     

Entanglement system,Casimir energy and black hole

We investigate the connection between the entanglement system in Minkowski spacetime and the black hole using the scaling analysis. Here we show that the entanglement system satisfies the Bekenstein entropy bound. Even though the entropies of two systems are the same form, the entanglement energy is different from the black hole energy. Introducing the Casimir energy of the vacuum energy fluctuations rather than the entanglement energy, it shows a feature of the black hole energy. Hence the Casimir energy is more close to the black hole than the entanglement energy. Finally, we find that the entanglement system behaves like the black hole if the gravitational effects are included properly.     

Magnetic and electrical transport properties of delta-doped amorphous Ge:Mn magnetic semiconductors

We report on the growth and characterization of delta-doped amorphous Ge:Mn diluted magnetic semiconductor thin films on GaAs (0 0 1) substrates. The fabricated samples exhibit different magnetic behaviors, depending on the Mn doping concentration. The Curie temperature was found to be dependent on both the Mn doping concentration and spacing between the doping layers. A sharp drop in magnetization and rise in resistivity are observed at low temperature in samples with high Mn doping concentrations, which is also accompanied by a negative thermal remanent magnetization (TRM) in the higher temperature range. The temperature at which the magnetization starts to drop and the negative TRM appears show a correlation with the Mn doping concentration. The experimental results are discussed based on the formation of ferromagnetic regions at high temperature and antiferromagnetic coupling between these regions at low temperature.