等差布极电测深在岩溶路基勘察中应用效果分析

该文简介等差布极电测深的方法技术 ,并对电测深影响因素和典型溶洞异常特征等方面进行研究分析。这种电测深法在实际应用中取得了满意的效果     

ZXT-3型恒定给矿控制系统的研究

介绍了以ＺＸＴ－３恒定给矿控制器及智能型ＳＲ－５３调节器为核心的恒定给矿控制系统。该系统的传感器为ＨＣＳ系列核子秤，执行器为给料电动机。通常情况下，可以实现每小时５～１００ｔ的物料流量控制，检测精度达到０．５％，控制精度达到１％，可广泛用于计量及恒定给料部门。     

石灰粉煤灰固化天津滨海软土试验研究

天津滨海新区大面积分布的海积软土含水量高、孔隙比大、强度较低,对工程的安全建设和使用存在很大影响,在工程实践中常需要进行固化处理。本文以石灰粉煤灰为固化材料,通过大量室内试验,以及微观结构测试,研究其对天津滨海软土的改良效果。室内试验结果表明,二灰土各项力学性质明显提高,即压缩性降低,水稳性良好,无侧限抗压峰值应变及三轴峰值应变较小,由于其强度很大程度依赖于土体颗粒间的胶结作用,一旦破坏,二次抗压强度则较低。微观结构测试分析表明,石灰粉煤灰与软土在拌合均匀状态下,经一系列物理化学作用,土体颗粒胶结成土团粒,粒间孔隙也得到填充。随着龄期的增长,二灰土孔隙数量减少,等效直径减小,土体颗粒数量减少,等效直径增大;而随着压力的增大,二灰土表现出孔隙数量增多而孔隙等效直径减小,颗粒数量和等效直径变化较小的趋势。室内试验与微观测试认为石灰粉煤灰可用于固化天津滨海软土,是一种经济合理的固化剂。     

临时密闭在矿井通风中的应用

对“板闭和杠子墙”临时密闭进行了介绍。此类密闭一般采用比较轻便的、易运输的材料构筑,工艺简单,并能在短时间内完成;虽然在建筑质量的坚固性和封堵的严密性上不及永久密闭,但在矿井通风中若无法满足运输及时间的要求时,临时密闭可发挥其自身的独特作用。     

碳纤维复合材料在酸雨模拟液中的失效行为

为研究酸雨模拟液中碳纤维复合材料的失效行为,采用电化学阻抗法(EIS)研究碳纤维复合材料在酸雨模拟溶液中的失效过程,力学性能测试通过万能试验机进行,由傅里叶红外光谱仪(FT-IR)和X射线光电子能谱仪(XPS)进行失效反应机理分析,并采用扫描电子显微镜(SEM)观察复合材料截面形貌。结果表明:全时浸泡试样的阻抗图谱变化不大,树脂层起到较好的屏蔽作用。外加恒电位阴极极化作用下试样破坏较快,介质快速渗入树脂层,引起试样低频阻抗模值和容抗弧半径的大幅下降,阻抗谱初期呈现扩散控制特征,随时间延长转为电荷转移和扩散的混合控制。全时浸泡条件下试样的力学性能变化不大,外加恒电位阴极极化条件下试样的弯曲和层间剪切性能大幅下降,树脂与基体间的界面结合力降低。试样在全时浸泡条件下基本不发生化学反应,外加恒电位阴极极化可促进碳纤维复合材料中树脂的水解,使树脂基体破碎,并生成疱状反应产物,加速材料的失效。     

Thermoelastic Damping in the Axisymmetric Vibration of Circular Microplate Resonators with Two-Dimensional Heat Conduction

Predicting thermoelastic damping (TED) is crucial in the design of high Q micromechanical resonators. Circular plates are common elements in the microresonators. In the past, some analytical models have been developed for TED in circular microplate resonators. However, to obtain a simple analytical expression, the previous models neglected the temperature gradient along the radial and circumferential directions, only the heat conduction through the thickness of the circular plate was considered. Thus the previous models cannot be used for general purpose design and optimization of microplate resonators. This paper presents a new analytical model for the TED in the circular microplates vibrating in the axisymmetric mode. Compared with the previous models, the present model considers two-dimensional heat conduction over thermoelastic temperature gradients along the thickness direction and the radial direction. The temperature field is represented by the product of the Bessel series along the radial direction and an unknown function along the thickness direction, which is determined in the solution procedure. The present model is validated by comparison with the previous model and the finite element method (FEM) model.     

CO2 reforming of methane over Ni/SBA-15 prepared with β-cyclodextrin – Role of β-cyclodextrin in Ni dispersion and performance

Ni/SBA-15-CD(1/X) catalysts were prepared by the impregnation of a certain amount of Ni(NO₃)₂ and various contents of β-cyclodextrin (CD), in which 1/X indicates the molar ratio of CD to Ni. The physicochemical properties of the catalysts were characterized by BET, XRD, TEM, TPR and TGA, and their catalytic performance in the CO₂ reforming of methane to syngas was evaluated using a fixed-bed quartz reactor. The characterization results revealed that Ni/SBA-15-CD(1/X) prepared with n(CD)/n(Ni) ratios in the range of 1/66–1/33 possessed smaller NiO particles and exhibited stronger interactions between NiO and SBA-15, whereas NiO particles were not well-dispersed on Ni/SBA-15-CD(1/X) catalysts prepared with further CD addition (1/X = 1/8 and 1/1). The reaction results indicated that the better-dispersed Ni/SBA-15-CD(1/X) catalysts, such as Ni/SBA-15-CD(1/66), Ni/SBA-15-CD(1/50) and Ni/SBA-15-CD(1/33), exhibited higher conversions and stronger abilities to resist carbon deposition. Regarding the role of CD in dispersing Ni particles, it could be speculated that complexes were formed between CD and Ni²⁺, as well as NO₃⁻, which would change the state of Ni species during the impregnation and heat treatment processes.     

共聚物阻垢剂AA/APEY的合成及性能研究

以丙烯酸（AA）、大分子单体烯丙基聚氧乙烯基羧酸（APEY）为原料,利用自由基聚合反应在水相中制得聚醚型无磷共聚物阻垢剂AA/APEY.研究了共聚物单体质量配比、阻垢剂用量对AA-APEY阻碳酸钙、磷酸钙和硫酸钙性能的影响.结果表明AA/APEY具有优异的阻垢性能.     

Skp2 Regulates Subcellular Localization of PPARγ by MEK Signaling Pathways in Human Breast Cancer

Nuclear hormone receptor family member PPARγ plays an important role in mammary gland tumorigenesis. Previous studies have shown PPARγ has cytoplasmic activities upon tetradecanoyl phorbol acetate (TPA) stimulation. However, the clinical pathological significance of cytoplasmic PPARγ is not completely understood in human breast cancer. Skp2 is oncogenic, and its frequent amplification and overexpression correlated with the grade of malignancy. In this study, the role of cytoplasmic PPARγ and Skp2 expression was investigated in human breast cancer progression. Therefore, immunohistochemical analysis was performed on formalin-fixed paraffin sections of 70 specimens. Furthermore, Western blot and immunofluorescence microscopy analysis were used to study the relationship between expression of cytoplasmic PPARγ and Skp2 expression in human breast cancer cells in vitro. Results showed that the expression of cytoplasmic PPARγ was positively correlated with Skp2 expression (p < 0.05), and correlated significantly with estrogen receptor (p = 0.026) and pathological grade (p = 0.029), respectively. In addition, Skp2 overexpression can provoke cytoplasmic localization of PPARγ upon MEK1-dependent mechanisms in human breast cancer cells by nuclear-cytosolic fractionation technology and immunofluorescence microscopy analysis. Using RNA interference technology, we also found that down-regulated Skp2 reduced the phosphorylation level of MEK1 and significantly reversed TPA-induced nuclear export of PPARγ in MDA-MB-231 cells. The changes in the subcellular localization of PPARγ may represent a novel target for selective interference in patients with breast cancer.     

Design of robust non‐fragile H∞ filters for uncertain neutral stochastic systems with distributed delays

This paper deals with the problem of robust non‐fragile H_∞ filtering for neutral stochastic systems with distributed delays and norm‐bounded parameter uncertainties. Attention is focused on the design of a filter which is subject to gain variations, such that the filtering error system is robustly stochastically stable with a prescribed H_∞ performance level for all admissible uncertainties. A delay‐dependent sufficient condition for the solvability of this problem is obtained in terms of a linear matrix inequality. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society