A novel photoalignment film for ferroelectric liquid crystal based on self-assembled monolayer method

A novel strategy based on self-assembly technology was devised for design of photosensitive material as a ferroelectric liquid crystal (FLC) alignment layer. This development offers new tools for the study and control at the molecular level of the interaction of FLCs with solid surfaces. The photoreactive material was self-assembled to the substrate by covalent bond linkage due to a special chemical adsorption reaction. Through ester bond linkage, a cyano group with strong polarity was introduced to be terminus of the film. Under irradiation of linearly polarised ultraviolet light, an optically anisotropic self-assembled film was easily obtained. The irradiated film was demonstrated to result in homogenous alignment of FLC by optical transmittance measurements and polarising optical microscopy images of a FLC cell at different rotation angles. The alignment quality of the FLC on this self-assembled monolayer film is comparable to that of commercial rubbed polyimide film. Furthermore, it was also found that the fine alignment of the FLC may be related to the smoothness of the self-assembled film surface owing to its polar end.     

混煤氮的热解析出特性及燃料NO_x的形成规律

混煤氮的热解析出特性及燃料ＮＯ_ｘ的形成规律邱建荣，马毓义，曾汉才，吕焕尧，喻秋梅（华中理工大学煤燃烧国家重点实验室武汉４３００７４）关键词：混煤，ＮＯ_ｘ，混合比，燃烧。ＥＭＩＳＳＩＯＮＯＦＮＩＴＲＯＧＥＮＣＯＭＰＯＵＮＤＳＡＮＤＮＯ_ｘＦＯＲＭＡＴ?..     

不同喹啉不溶物的特性及对中间相转化过程的影响

采用￣１３Ｃ－ＮＭＲ、ｘ－ｒａｙ衍射、扫描和透射电镜研究了二种ＱＩ──原生ＱＩ、次生ＱＩ（喹啉不溶物）结构，并通过热转化试验考察了它们对中间相热转化过程的影响。结果表明，原生ＱＩ是由炭黑状固体小圆球组成，并包含有煤粉、焦粉等夹杂物，属非晶态混和物。它在中间相转化过程中，促使中间相小球体较早生成，并阻碍中间相球体融并，导致中间相热转化最终固体产物的镶嵌结构生成。次生ＱＩ微晶排列有序性较好，属中间相组织或中间相前躯体，对中间相的成长过程有利。     

Feasibility study on strengthening heating effect of high power short pulse laser on biological tissue by micro/nano metal particles

A new method for enhancing the heating effect of high power short pulse laser on biological tissue by micro/nano metal particles was proposed. Theoretical analysis of the influences of the micro/nano particle kind, the concentration and the microcosmic distribution of micro/nano particles on the temperature response was carried out with a multi-layer hyperbolic heat conduction model with volumetric heat generation. The results indicate that embedding micro/nano particles could improve the surface temperature increase of biological tissue with short duration and reduce the deeper material temperature under the same heating condition, which would help strengthen the heating effects of high power short pulse laser on biological tissue. This study may open a new technical approach for improving laser applications.     

Dechlorination and oxidation for waste poly(vinylidene chloride) by hydrothermal catalytic oxidation on Pd/AC catalyst

Hydrothermal catalytic oxidation was an effective method in the dechlorination and oxidation of waste poly(vinylidene chloride) (PVC) on Pd/AC catalyst. The PVC was decomposed by hydrothermal catalytic oxidation in the system of NaOH at appropriate temperature in our experiments. The degree of dechlorination and oxidation increased with increasing concentration of H₂O₂, reaching up to 90% and 50% under the condition of 180 °C and 0.5 MPa pressure. The main products were Cl⁻ and CO₂, and the rest comprises a range of water-soluble organic acids, which were nontoxic and can be treated by biological purification. Therefore, the hydrothermal catalytic oxidation had significant potential in application for treatment of chlorinated waste plastics.     

An alternative interpretation of the optical spectra for Fe-doped KTaO3 crystals

In this paper, the excitation spectrum and luminescence at 14 569, 17 225, 18 829 and 14 659 cm^-1 for Fe³⁺ ion at the K⁺ site of KTaO₃ crystals are assigned, respectively, to the ⁶A₁(S)→⁴T₁(G), ⁴T₂(G), ⁴E₁(G)[⁴A₁(G)] and ⁴T₁(G)→⁶A₁(S) transitions rather than to the ⁶A₁(S)→⁴T₁(G), ²T₂(I), ⁴T₂(G) and ⁴T₁(G)→⁶A₁(S) transitions given in a previous paper [Bryknar et al., Radiat. Eff. Def. Solids 149(1999)51]. On the basis of this assignment, the reasonable optical spectrum parameters (in particular, the cubic field parameter Dq≈−640 cm⁻¹) are obtained. The validity of this assignment is discussed.     

Fabrication of gradient refractive index ball lenses using the method of combination of ion exchanging and sagging

Based on the Fick’s diffusion equations, the distribution function of refractive index of a gradient refractive index ball lens (GRIN ball lens/GBL) is derived. Lithium containing silicate glass is fabricated and GRIN ball lenses (GBLs) which diameters are from 0.3 mm to 3.0 mm are made by the method of combination of Ion exchanging and sagging in sodium nitrate. Refractive index profiles of these GBLs are measured by interferometer, and the performances such as effective focal length (EFL), back focal length (BFL) and numerical aperture (NA) between GBLs and homogeneous ball lenses (HBLs) are compared. Results show that the distribution of the index of refraction is parabolic curve and its Δn is about 0.0002, the performances of the former are super to the latter.     

Influence of Mg/Er co‐doping on the principal laser parameters of LiNbO3 crystals

Mg: Er: LiNbO₃ crystals were grown by the Czochralski technique with various concentrations of MgO = 2 mol%, 4 mol%, 6 mol% and the fixed concentration of Er₂O₃= 1 mol% in the melt, and the 8 mol%Mg: 1 mol%Er: LiNbO₃ crystal was fabricated by the Czochralski technique with special technology process. The crystals were treated by polarization, reduction and oxidation. The segregation coefficients of Mg²⁺ and Er³⁺ in Mg: Er: LiNbO₃ crystals were measured by X‐ray fluorescence spectrograph, as well as the crystal's defect structure and optical properties were analyzed by the UV‐Vis, IR and fluorescent spectroscopy. The pump wavelength and the surge wavelength were determined. Using m‐line method tested optical damage resistance of those crystals, the results show that photodamage threshold of Mg: Er: LiNbO₃ crystals are higher than that of Er: LiNbO₃ crystal, and the oxidation treat could enhance the photodamage resistant ability of crystals while the reduction treat could depress the ability. The optical damage resistance of 8 mol%Mg: 1 mol%Er: LiNbO₃ crystal was the strongest among the samples, which was two orders magnitude higher than that of 1 mol%Er: LiNbO₃ crystal. The dependence of the optical properties on defect structure of Mg: Er: LiNbO₃ crystals was discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)