Effect of ion impinging on the microstructure and field emission of carbon nanotubes

Effects of ion impinging on the microstructure and field electron emission properties of screen-printed carbon nanotube films were investigated. We observed that the plasma treatment modified the microstructure of CNTs along with the remarkable increase of emission site density. With the prolongation of ion impinging time, the emission current falls down first, and then rises up to higher than that of the untreated films. It is proposed that the change of emission characteristics is due to the different emission mechanisms. After the treatment, electrons are emitted predominantly from the nano-nodes on the tube wall instead from the nanotube tips.     

Synthesis and characterization of new bis(1-aryliminomethylenylnaphthalen-2-oxy)nickel complexes and their catalytic behavior for vinyl polymerization of norbornene

The synthesized 1-aryliminomethylenylnaphthalen-2-ol derivatives reacted with nickel chloride to form bis(1-aryliminomethylenylnaphthalen-2-oxy)nickel complexes. All resultant compounds were structurally characterized by elemental analyses, IR and H NMR, and the structures of the formed complexes were elucidated by X-ray crystal structure analysis. The complexes show high catalytic activities for the vinyl polymerization of norbornene in the presence of methylaluminoxane. The catalytic activity variations have been followed by gas chromatography through monitoring the conversion of norbornene.     

Jensen's inequality for g-expectation: part 1

Briand et al. (Electron. Comm. Probab. 5 (2000) 101–117) gave a counterexample and proposition to show that given g,g-expectations usually do not satisfy Jensen's inequality for most of convex functions. This yields a natural question, under which conditions on g, do g-expectations satisfy Jensen's inequality for convex functions? In this paper, we shall deal with this question in the case that g is convex and give a necessary and sufficient condition on g under which Jensen's inequality holds for convex functions. To cite this article: Z. Chen et al., C. R. Acad. Sci. Paris, Ser. I 337 (2003).     

力矩教学剖析

力矩在物理课教学中占有举足轻重的地位．力矩的概念并不难理解，但应用起来却涉及到很多知识点，且能翻出不少新花样．让我们来看下面的问题：放在地面上的板条箱(如图)，受到R=120N力的作用．试求该力对点A的力矩：(1)根据力臂计算；(2)根据该力在作用点B处的分力计算；(3)根据该力在作用线上其它某一适当点处的分力计算．     

半导体激光器发射光谱实验仪

设计了一种半导体激光器发射光谱实验仪 ,可以用来观测LD发射的荧光光谱、激光光谱 ,以及了解光栅外腔选取单纵模、压窄线宽、波长调谐的机理 .该实验仪结构紧凑 ,物理概念清晰 ,适用于大专院校的光学实验教学     

2,9-disubstituted 1,10-phenanthroline nickel complexes: Syntheses,characterization, and their ethylene oligomerization

Nickel complexes 1–4 ligated with 2,9-disubstituted-1,10-phenanthroline were synthesized and characterized by FT-IR spectra and elemental analysis. The molecular structure of complex 2 was confirmed by X-ray crystal diffraction analysis. Activated with methylaluminoxane (MAO), those complexes showed moderate activities for ethylene oligomerization. Published in Kinetika i Kataliz, 2007, Vol. 48, No. 5, pp. 710–714. This article was submitted by the authors in English.     

Buckling of a stiff thin film on a compliant substrate in large deformation

A finite-deformation theory is developed to study the mechanics of thin buckled films on compliant substrates. Perturbation analysis is performed for this highly nonlinear system to obtain the analytical solution. The results agree well with experiments and finite element analysis in wavelength and amplitude. In particular, it is found that the wavelength depends on the strain. Based on the accurate wavelength and amplitude, the membrane and peak strains in thin films, and stretchability and compressibility of the system are also obtained analytically.     

Miscibility and phase structure of binary blends of polylactide and poly(methyl methacrylate)

Blends of amorphous poly(DL‐lactide) (DL‐PLA) and crystalline poly(L‐lactide) (PLLA) with poly(methyl methacrylate) (PMMA) were prepared by both solution/precipitation and solution‐casting film methods. The miscibility, crystallization behavior, and component interaction of these blends were examined by differential scanning calorimetry. Only one glass‐transition temperature (T_g) was found in the DL‐PLA/PMMA solution/precipitation blends, indicating miscibility in this system. Two isolated T_g's appeared in the DL‐PLA/PMMA solution‐casting film blends, suggesting two segregated phases in the blend system, but evidence showed that two components were partially miscible. In the PLLA/PMMA blend, the crystallization of PLLA was greatly restricted by amorphous PMMA. Once the thermal history of the blend was destroyed, PLLA and PMMA were miscible. The T_g composition relationship for both DL‐PLA/PMMA and PLLA/PMMA miscible systems obeyed the Gordon–Taylor equation. Experiment results indicated that there is no more favorable trend of DL‐PLA to form miscible blends with PMMA than PLLA when PLLA is in the amorphous state. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 23–30, 2003