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1.
Alzheimer's disease(AD) is one of the most common types of dementia whose hallmarks include neurofibrillary tangles and senile plaques. The latter are mainly composed of amyloid-β proteins(Aβ), and it's suggested that Aβ may be the causative factor in AD pathogenesis. Immunotherapy targeting Aβ for preventing aggregation of Aβ and mildly clearing amyloid plaques has been a hot topic since 1999. Although the first clinical trial of Aβ vaccine, AN-1792, failed in phase II, its results suggested some key points in the design of Aβ vaccines. Avoiding the possible toxic Aβ specific T cell response and inducing a Th2 type cellular immune response may be beneficial for Aβ immunotherapy. Many associations and research groups are working on Aβ vaccine and some progress has been made in recent years. In this review, we have provided a detailed summary of past Aβ vaccines, which have been sorted by the immunogen, and we also discuss some recent progress and future perspectives. 相似文献
2.
In this paper,we have developed a highly efficient method for the direct preparation of propylene carbonate from propylene and carbon dioxide(CO2) using quaternary ammonium heteropolyphosphatotungstate–quaternary ammonium halide catalytic system with anhydrous hydrogen peroxide as an oxidant through one-pot two-step process.The effects of the amount of tetrabutylammonium bromide(TBAB),the concentration of hydrogen peroxide and other reaction conditions were investigated.The catalyst system gave an optimum propylene oxide yield(91%) at75°C in oxidation step and the highest propylene carbonate yield(99%) at 140°C and 3.0 MPa in cycloaddition step.Based on the results,a reaction mechanism has been proposed. 相似文献
3.
直流射频等离子体增强化学气相沉积类金刚石碳薄膜的结构及摩擦学性能研究 总被引:5,自引:7,他引:5
利用直流射频等离子增强化学气相沉积技术在单晶硅表面制备了类金刚石碳薄膜.采用Raman光谱、红外光谱、x射线光电子能谱和原子力显微镜等研究了薄膜的微观结构和表面形貌,在UMT-2MT型摩擦磨损试验机上考察了薄膜在不同载荷与滑动速度下的摩擦学性能。结果表明:所制备的类金刚石碳薄膜具有典型的类金刚石结构特征,薄膜均匀、致密,表面粗糙度小,硬度较高;薄膜与Si3N4陶瓷球对摩时显示出良好的抗磨减摩性能;随着试验载荷与滑动速度的提高,薄膜的摩擦系数降低,耐磨寿命降低;薄膜的减摩抗磨性能同其在Si3N4陶瓷球偶件磨损表面形成的转移膜相关。 相似文献
4.
中心裂纹圆盘应力强度因子的测试误差分析 总被引:1,自引:0,他引:1
本文在中心裂纹圆盘应力强度因子解析解的基础上,利用一阶微分法则,给出了与裂纹相对长度和加载角相关的应力强度因子(K 和K )的4个误差传递函数。这4个误差传递函数关于裂纹相对长度和加载角均是非线性的,它们既是误差分析的基础,又是合理确定裂纹相对长度和加载角的基础。分析结果表明,加载角的误差Δθ除了对纯 型K 的误差几乎没有影响,对纯 型K 影响较小外,对复合型K 、K 的误差均有较大影响。最后,本文建议裂纹相对长度的取值范围为0.4~0.6;还建议在复合型断裂试验时,必须依据对K 、K 的总体精度要求来严格控制加载角的精度。 相似文献
5.
YuchengWu YongZhang LideZhang 《中国颗粒学报》2004,2(1):19-24
Nanosized palladium particles were incorporated into mesoporous silica matrix to obtain nanocomposites using the sol-gel technique. Effects of the finely dispersed metallic palladium on the microstructure and properties of the nanocomposites were investigated. By means of X-ray diffraction and optical absorption, it was found that palladium particles were 5-9 nm in diameter and their uniform dispersion in the mesoporous silica depended on both the content of the palladium and the structural features of the silica matrix. The results showed that the mixing method of preparation led to wider size distribution of the nanosized particles as compared to the immersion method, but dispersed degree was reduced. Although the incorporation of nanosized palladium particles could not substantially induce significant structural changes of the matrix, the apparent red-shifted optical absorptions for the nanocomposites were observed as compared to the parent monolithic silica, particularly with increase in palladium loading and calcination temperature. 相似文献
6.
7.
Ruoyu Hong * Jianmin Ding Guoliang Zheng College of Chemistry Chemical Engineering Soochow University Suzhou P. R. China Institute of Process Engineering Chinese Academy of Sciences Beijing P. R. China IBM HYDA/- C Highway North Rochester MN USA *Author to whom correspondence should be addressed. E-mail: rhong@suda.edu.cn 《中国颗粒学报》2004,2(5):207-214
1. Introduction1.1 Silica nanoparticles and synthesis methods Silica (SiO2) nanoparticles are widely used in industry asan active filler for polymer reinforcement, a rheologicaladditive in fluids, a free flow agent in powders, and anagent for chemical mechanical polishing during IC (inte-grated circuit) fabrication (Sniegowski & de Boer, 2000).Silica powder is also used for producing silicon carbide(Koc & Cattamanchi, 1998) or opaque silica aerosols (Leeet al., 1995). Many methods can … 相似文献
8.
GuanliXu LinaXu ShunlongPan GuangzhiSong 《中国颗粒学报》2004,2(4):182-184
The effect of polyethyleneimine (PEI) concentration on the properties of titanium dioxide (TiO2) suspensions is studied with or without the addition of an electrolyte (barium acetate). Measurements of the apparent viscosity and the stability of TiO2 suspensions showed that PEI is an effective dispersant for TiO2 particles in suspension in the absence of an electrolyte, not only reducing the viscosity of the suspension but also increasing its stability. In the presence of an electrolyte, however, small quantities of polyethyleneimine could neither disperse the TiO2 particles nor de-crease the viscosity of the TiO2 suspensions; only PEI concentrations beyond saturation adsorption could perceptively improve the stabilitv of TiO2 suspensions. 相似文献
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10.
Xia Yang Ya-Jun Zhou Pei He Yun-Hua Guo Cong-Jun Liu Ke-Wu Yang 《中国化学快报》2014,25(10):1323-1326
In an effort to understand the recombination of a B2 metallo-β-lactamase(MβL),the binding of metals to apo-ImiS was studied by isothermal titration calorimetry and fluorescence spectra.The binding of Zn(Ⅱ),Co(Ⅱ) to apo-lmiS resulted in activation free energies △G_≠~θ values of 93.719 and 92.948 kJ mol~(-1),respectively,and increasing of fluorescence intensity at maxima emission of 340 nm. 相似文献