Perylene Bisimide In-chain Polyethylene with Unique Self-assembly Nanostructure through Acyclic Diene Metathesis (ADMET) Polymerization

A novel perylene tetracarboxylic acid bisimide(PTCBI) in-chain polyethylene(PE) was first prepared via acyclic diene metathesis(ADMET) polymerization of PTCBI-functionalized α,ω-diene monomer. The polymers could spontaneously self-assemble into hollow cylindrical structures in which the π-π interaction between adjacent PTCBI moieties was enhanced and the electron mobility was possibly promoted. The hydrogenation of as-obtained polymer was readily accomplished, affording the desired precision PTCBI in-chain PE with a saturated backbone, which showed high glass transition temperature(Tg = 63 °C), relatively wide range of light absorption(λ = 200-575 nm), and higher LUMO level(-3.62 e V). It can therefore serve as a superior model for facile construction of functional polyolefin and soluble PTCBI polymer with ordered architecture.     

The role of the local environment in determining the sizes of the magnetic moments in Fe3Al

A local environment approach is used to calculate the sizes of the magnetic moments in ordered Fe₃Al. A simple model based on a LCAO model and Stoner theory gives results in good agreement with experiment. Calculations were performed self-consistently using the recursion method. The role of the aluminium is investigated and it is shown that it is essential to include the aluminium sp band but the results are insensitive to its details.     

KrF激光泵浦H2受激拉曼放大

利用KrF激光泵浦高压H_2,在同轴前向的受激拉曼散射(SRS)作用下,产生受激拉曼放大,1阶Stokes光对泵浦光的转换效率为17.2％,并对影响放大过程和转换效率的若干因素作了分析。     

碘-四氯化碳萃取光度法间接测定食品中的痕量过氧化氢

在 p H1.0— 3.0稀硫酸介质中 ,一定的反应条件下 ,过氧化氢与碘化钾反应 ,释放出一定量的碘 ,建立了碘 -四氯化碳萃取光度法间接测定痕量过氧化氢。共存离子基本上不干扰测定 ,过氧化氢的检测限为0 .0 5 μg·m L-1;回收率在 94 %— 98%之间 ,结果令人满意     

Efficient 1.3-μm electroluminescence from high concentration boron-diffused silicon p+-n junctions Invited Paper

Electroluminescence peaking at 1.3 μm is observed from high concentration boron-diffused silicon p+-n junctions. This emission is efficient at low temperature with a quantum efficiency 40 times higher than that of the band-to-band emission around 1.1μm, but disappears at room temperature. The 1.3-μm band possibly originates from the dislocation networks lying near the junction region, which are introduced by high concentration boron diffusion.     

On <Emphasis Type="Italic">C</Emphasis>*-algebras related to constrained representations of a free group

We consider representations of the free group F ₂ on two generators for which the norm of the sum of the generators and their inverses is bounded by some number μ ∈ [0, 4]. These μ-constrained representations determine a C*-algebra A _μ for each μ ∈ [0, 4]. If μ = 4, this gives the full group C*-algebra of F ₂. We prove that these C*-algebras form a continuous bundle of C*-algebras over [0, 4] and evaluate their K-groups.     

A note on allocation of portfolio shares of random assets with Archimedean copula

This paper further studies the single-period portfolio allocation of risk assets under the assumption that random returns having increasing utility and Archimedean copula. The shares of risk assets in the optimal allocation are proved to be ordered when marginal returns have the likelihood ratio order, and sufficient conditions for the joint density of returns of a multivariate risk to be arrangement increasing is built as well.     

Heterogeneous copper‐catalyzed oxidative coupling of oxime acetates with sodium sulfinates: An efficient and practical synthesis of β‐keto sulfones

An efficient and practical route to β‐keto sulfones has been developed through heterogeneous oxidative coupling of oxime acetates with sodium sulfinates by using an MCM‐41‐supported Schiff base‐pyridine bidentate copper (II) complex [MCM‐41‐Sb,Py‐Cu (OAc)₂] as the catalyst and oxime acetates as an internal oxidant, followed by hydrolysis. The reaction generates a variety of β‐keto sulfones in good to excellent yields. This new heterogeneous copper (II) catalyst can be easily prepared via a simple procedure from readily available and inexpensive reagents and exhibits the same catalytic activity as Cu (OAc)₂. MCM‐41‐Sb,Py‐Cu (OAc)₂ is also easy to recover and is recyclable up to eight times with almost consistent activity.