Comparative study of three lignin fractions isolated from mild ball‐milled Tamarix austromogoliac and Caragana sepium

Six lignin fractions from mild ball‐milled Tamarix austromogoliac (TA) and Caragana sepium (CS) were sequentially isolated with 80% dioxane containing 0.05M HCl at 75°C for 4 h, 50% aqueous ethanol containing 1M triethylamine at 70°C for 4 h, and 8% aqueous NaOH at 45°C for 3 h. The results showed that the successive treatments made it possible to isolate lignin from wood with a high yield and purity, in which 89.4 and 90.6% of the original lignin from TA and CS were released, respectively. The lignin fractions isolated with the three‐step method were analyzed with Fourier transform infrared, ¹H‐ and ¹³C‐NMR, alkaline nitrobenzene oxidation, and gel permeation chromatography. It was found that the three lignin fractions isolated from TA were rich in syringyl units, and the molar ratio of the relatively total moles of vanillin, vanillic acid, and acetovanillin to the relatively total moles of syringaldehyde, syringic acid, and acetosyringone decreased from 1: 2.6 to 1 : 3.2 to 1: 3.6 in the lignin preparations, whereas this ratio in the corresponding lignin fractions isolated from CS was found to be 1.4 : 1, 1.1 : 1, and 1 : 1.4, respectively. More importantly, the results revealed that the sequential extractions of the mild ball‐milled TA and CS with 80% acidic dioxane, 50% alkaline ethanol, and 8% aqueous NaOH under the conditions used did not significantly cleave the β–O‐4 and α–O‐4 linkages in lignin macromolecules. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

彩涂卷钢涂层厚度对耐老化性能的影响

分析了目前国内外彩涂卷钢市场需求的现状,通过紫外人工加速老化试验,从涂层表面光泽保持率、色差以及表面粉化、开裂的角度,着重研究了彩板的不同面漆涂层厚度对彩板耐老化等相关性能的影响.用减薄涂层来降低彩板生产成本的方法,必然带来严重的质昔问题.     

茶树油的分子蒸馏精制及其GC/MS分析

利用新型、特殊分离技术——分子蒸馏对茶树油进行精制,并对精制后的茶树油进行GC/MS定性分析及其总离子流图的面积归一法定量分析。结果从粗茶树油中分离出了61种化合物,鉴定出36种组分,占总量的98.67%,其中4-松油醇高达49.56%,并且精制的茶树油符合国际标准(ISO 4730-1996)。     

Electrochemical behavior of magnesium alloys AZ91D,AZCe2, and AZLa1 in chloride and sulfate solutions

The influence of Cl⁻ and SO₄²⁻ on the electrochemical behavior of AZ91D, AZCe2, and AZLa1 was studied. For all alloys, there was a current plateau in the anodic polarization curves in Na₂SO₄ solutions. In 0.5% NaCl solution, there was a small current plateau, whereas there was none in the 3.5% and 5% NaCl solutions. This indicated that SO₄²⁻ is less aggressive than Cl⁻. The range of the current plateau decreased with increasing SO₄²⁻ concentration. For all alloys, the high frequency capacitive loop in the Nyquist plots decreased with increasing concentration consistent with the decrease in corrosion resistance with increasing Cl⁻ and SO₄²⁻ concentration.     

ZrO2颗粒对Si3N4/SiO2陶瓷复合材料性能的影响

通过加入ZrO2颗粒作为增强相,利用ZrO2的相变微裂纹增韧来改善Si2M4/SiO2陶瓷材料的力学性能.当ZrO2含量为15%时,材料的抗弯强度最高,达194.8 MPa.     

因势利导 疏管结合——淄博市“美食街”地段影响流动商贩分布的因素研究

该文从实地调查淄博市“美食街”地段中的流动商贩入手,对流动商贩的经营商品和辅助工具的种类、地段中的用地性质、消费者购买路线、地段中的道路宽度四个影响流动商贩分布的因素进行了研究和分析,从而寻找和总结出流动商贩存在的必要性以及其在哪些层面影响了我们的城市,以便对流动商贩提出合理的规划布局原则和人性化的管理建议。     

基于战略的企业项目组合设计与管理

在知识经济飞速发展的今天,创新将逐渐成为整个社会创造财富的主要方式。随着企业创新数量的增加,企业必须对各种创新采用基于战略的项目组合管理方法,从企业战略的角度对备选项目进行选择,并对多个项目进行组合管理。在这一过程中,企业应当综合地分析企业的战略发展需要与企业能力,包括资金能力、技术能力等,以企业长期价值最大化为目标对企业的项目组合进行设计,并制定计划,依靠主动出击来实现企业的项目组合管理。     

供水管网GIS的开发与维护

以佛山市南海区供水管网信息系统建设为例,详细介绍了GIS的建立,可为拟建供水管网GIS的城市提供参考;介绍了GIS建成后的日常维护,提出在GIS基础数据收集、整理、录入过程中工作流程化管理的重要性.     

Impulse response solution to the three-dimensional vector radiative transfer equation in atmosphere-ocean systems. I. Monte Carlo method

We have developed a powerful 3D Monte Carlo code, as part of the Radiance in a Dynamic Ocean (RaDyO) project, which can compute the complete effective Mueller matrix at any detector position in a completely inhomogeneous turbid medium, in particular, a coupled atmosphere-ocean system. The light source can be either passive or active. If the light source is a beam of light, the effective Mueller matrix can be viewed as the complete impulse response Green matrix for the turbid medium. The impulse response Green matrix gives us an insightful way to see how each region of a turbid medium affects every other region. The present code is validated with the multicomponent approach for a plane-parallel system and the spherical harmonic discrete ordinate method for the 3D scalar radiative transfer system. Furthermore, the impulse response relation for a box-type cloud model is studied. This 3D Monte Carlo code will be used to generate impulse response Green matrices for the atmosphere and ocean, which act as inputs to a hybrid matrix operator-Monte Carlo method. The hybrid matrix operator-Monte Carlo method will be presented in part II of this paper.     

Substrate effect on in-plane dielectric and microwave properties of Ba(Sn0.15Ti0.85)O3 thin films

The microstructure and in-plane dielectric and microwave properties of Barium tin titanate Ba(Sn_0.15Ti_0.85)O₃ (BTS) thin films grown on (1 0 0) LaAlO₃ and (1 0 0) MgO single-crystal substrates through sol–gel process were investigated. X-ray diffraction and field emission scanning electron microscopy were used to characterize crystal structure of phases and microstructure of the thin films, respectively. Microwave properties of the films were measured from 1 to 10 GHz by the interdigital capacitor configuration. The obvious differences in the dielectric and microwave properties are attributed to the stress in the films, which result from the lattice mismatch and difference in the thermal expansion coefficients between the film and substrates. This work clearly reveals the highly promising potential of BTS films for application in tunable microwave devices.