软弱围岩中隧洞衬砌裂缝机理分析

本文针对一实际膨胀性围岩隧洞工程中衬砌出现裂缝的现象,应用引进的岩土工程仿真分析软件ＦＩＮＡＬ对隧洞施工期的围岩变形与薄拱片钢筋混凝土衬砌结构的内力、强度特性进行了较系统的数值仿真分析。分析中考虑了围岩本身的膨胀、流变特性,重点探讨了衬砌支护时间和回填灌浆质量对衬砌裂缝的影响。分析结果表明：ａ．该隧洞围岩在运行期受膨胀压力的影响较小;ｂ衬砌支护时间是一重要因素,但在本文条件下仍不是主要原因;ｃ．回     

Geometrical nonlinear deformation model and its experimental study on bimorph giant magnetostrictive thin film

The geometrical nonlinearity of a giant magnetostrictive thin film (GMF) can be clearly detected under the magnetostriction effect. Thus, using geometrical linear elastic theory to describe the strain, stress, and constitutive relationship of GMF is inaccurate. According to nonlinear elastic theory, a nonlinear deformation model of the bimorph GMF is established based on assumptions that the magnetostriction effect is equivalent to the effect of body force loaded on the GMF. With Taylor series method, the numerical solution is deduced. Experiments on TbDyFe/Polyimide (PI)/SmFe and TbDyFe/Cu/SmFe are then conducted to verify the proposed model, respectively. Results indicate that the nonlinear deflection curve model is in good conformity with the experimental data.     

Effect of initial pH on formation of hollow calcium carbonate particles by continuous CO2 gas bubbling into CaCl2 aqueous solution

Hollow calcium carbonate (CaCO₃) particles are synthesized by continuous bubbling CO₂ gas into CaCl₂ aqueous solution. In order to study the formation kinetics of the hollow CaCO₃ particles, the transmitted light strength of the CaCl₂ solution during the reaction was measured automatically with an on-line monitoring. It was verified that the pH for the formation of the hollow particles depended on the reaction temperature. Higher initial pH of the CaCl₂ solution resulted in the higher ratio of hollow particles as compared to that obtained at lower pH.     

超磁致伸缩执行器磁滞非线性建模与控制

针对超磁致伸缩执行器的磁滞非线性问题,应用Priesach理论模型建立了执行器的磁滞模型,并根据其逆模型设计了前馈补偿器,同时设计了磁滞模型的自适应算法和动态调整前馈补偿器的参数,最终实现对执行器磁滞非线性进行补偿和控制。仿真和试验结果表明该模型能够很好的描述执行器的磁滞非线性,采用自适应算法有效地改善了执行器输出位移的磁滞非线性,减小了系统的非线性误差,提高了执行器的控制精度。     

Application of hydrophilic ionic liquid treatment to the morphological observations of hydrated porous ceramic green bodies

In this study, a simple and convenient method for observing the surface morphology of hydrated porous ceramic green bodies is proposed. The porous hyrdoxyapatite (HAp) green body was prepared by a gelcasting process and was dried in a humid chamber from 90 to 50% relative humidity at 25 °C before subsequent treatment with a hydrophilic ionic liquid (IL). The surface morphology of the IL-treated porous HAp green body was observed using FE-SEM. The results showed that the pore morphology and microstructure of the HAp green body was readily observable without evidence of charging. The as-prepared sample showed pores approximately 300–600 μm in diameter, which gradually contracted to approximately 200–400 μm upon drying in the humid chamber. Following sintering at 1000 °C, the pores had further contracted to approximately 100–300 μm. The IL binds with the surrounding water to prevent the sample from drying in vacuum and acts as a conductive media, allowing the HAp ceramics to be observed in the electron microscope. In comparison to the micro-focused X-ray CT analysis, the fine pore structure (less than 100 μm) could only be observed using FE-SEM when the porous body had also been subjected to the IL treatment.     

Expression of matrix metalloproteinases 2 and 9 in regenerating skeletal muscle: a study in experimentally injured and mdx muscles

Matrix metalloproteinases (MMPs) cooperatively degrade all components of the extracellular matrix (ECM). Remodeling of ECM during skeletal muscle degeneration and regeneration suggests a tight regulation of matrix-degrading activity during muscle regeneration. In this study, we investigated the expression of MMP-2 and MMP-9, in normal muscles and their regulation during regeneration process. We further investigated their secretion by C2C12 myogenic cell line. Two models of muscle degeneration-regeneration were used: (1) normal muscles in which necrosis was experimentally induced by cardiotoxin injection; (2) mdx muscles which exhibit recurrent signs of focal myofiber necrosis followed by successful regeneration. MMPs were studied by zymography; their free activity was quantified using 3H-labeled gelatin substrate and mRNA expression was followed by Northern hybridization. Muscle degeneration-regeneration was analyzed by conventional morphological methods and in situ hybridization was performed on muscle sections to identify the cells expressing these MMPs. Results show that MMP-2, but not MMP-9 expression, is constitutive in normal muscles. Upon injury, the active form of MMP-2 is transiently increased, whereas MMP-9 is induced within 24 h and remains present for several days. Quantitative assays of free gelatinolytic activity show a progressive and steady increase that culminates at 7 days postinjury and slowly returns to normal levels. In adult mdx mice, both pro and active forms of MMP-2 and MMP-9 are expressed. Northern blot results support these findings. Zymography of C2C12-conditioned medium shows that myogenic cells produce MMP-2. By in situ hybridization we localized MMP-9 mRNA in inflammatory cells and putative activated satellite cells in injured muscles. Our data allow the correlation of the differential expression of pro and/or active forms of MMP-2 and MMP-9 with different stages of the degeneration-regeneration process: MMP-9 expression is related to the inflammatory response and probably to the activation of satellite cells, whereas MMP-2 activation is concomitant with the regeneration of new myofibers.     

Absence of basement membranes after targeting the LAMC1 gene results in embryonic lethality due to failure of endoderm differentiation

Centrosome duplication and separation are of central importance for cell division. Here we provide a detailed account of this dynamic process in Dictyostelium. Centrosome behavior was monitored in living cells using a gamma-tubulin-green fluorescent protein construct and correlated with morphological changes at the ultrastructural level. All aspects of the duplication and separation process of this centrosome are unusual when compared with, e.g., vertebrate cells. In interphase the Dictyostelium centrosome is a box-shaped structure comprised of three major layers, surrounded by an amorphous corona from which microtubules emerge. Structural duplication takes place during prophase, as opposed to G1/S in vertebrate cells. The three layers of the box-shaped core structure increase in size. The surrounding corona is lost, an event accompanied by a decrease in signal intensity of gamma-tubulin-green fluorescent protein at the centrosome and the breakdown of the interphase microtubule system. At the prophase/prometaphase transition the separation into two mitotic centrosomes takes place via an intriguing lengthwise splitting process where the two outer layers of the prophase centrosome peel away from each other and become the mitotic centrosomes. Spindle microtubules are now nucleated from surfaces that previously were buried inside the interphase centrosome. Finally, at the end of telophase, the mitotic centrosomes fold in such a way that the microtubule-nucleating surface remains on the outside of the organelle. Thus in each cell cycle the centrosome undergoes an apparent inside-out/outside-in reversal of its layered structure.     

Dipyridamole modulated Tc-99m sestamibi lung SPECT in small cell lung cancer

PURPOSE: In this study, the authors wanted to determine whether dipyridamole-modulated MIBI (dipyridamole-MIBI) could enhance the prediction of the response to chemotherapy in patients with small cell lung cancer. METHODS: Twenty-seven patients with biopsy-proved small cell lung cancer (25 men, 2 women; mean age, 61 +/- 7 years) underwent dipyridamole-MIBI SPECT 3 to 7 days before starting chemotherapy (80 mg/m2 etoposide and 80 mg/m2 cisplatin every 3 or 4 weeks for at least two cycles). Tomographic images before and after dipyridamole (0.84 mg/kg) were acquired 1 hour after injection of 370 (10 mCi) and 1,110 (30 mCi) MBq MIBI, respectively. The response to chemotherapy was grouped as specified as complete response (CR), partial (PR), no change (NC), or progressive disease (PD), according to the change in tumor size on chest roentgenography and CT. Patients showing CR and PR were classified as responders, and those who showed NC and PD were considered nonresponders. RESULTS: Among the 27 patients, 22 were responders (3 CR, 19 PR) and 5 were nonresponders (3 NC, 2 PD). The tumor-to-normal lung ratio (T:NL) of responders was significantly higher than that of nonresponders. The diagnostic accuracy of the T:NL ratio to differentiate responders and nonresponders was 33.3%, with a cutoff value of 2.5, which was significantly improved to 77.8% when an increased T:NL ratio after dipyridamole was assigned to a nonresponder. Furthermore, all patients with CR showed diminished T:NL ratios after dipyridamole, and all patients with NR showed an increased T:NL ratio after dipyridamole. CONCLUSION: Dipyridamole-MIBI SPECT could enhance the prediction of response to chemotherapy in patients with small cell lung cancer.     

Studies on the substitution of inorganic fertilizers with organic manure and their effect on soil fertility in rice—wheat rotation

Field studies on the substitution of N and P fertilizers with farm yard manure (FYM) and their effect on the fertility status of a loamy sand soil in rice—wheat rotation are reported. The treatments consisted of application of 12 t FYM ha^–1 in combination with graded levels of N and P. Application of fertilizer N, FYM and their different combinations increased the rice yield significantly. There was no significant response to P application. The magnitude of response to the application of 12 t FYM and its combined use with each of 40 kg and 80 kg N ha^–1 was 0.7, 2.2 and 3.9 t ha^–1 respectively. Application of 120 kg N ha^–1 alone increased the yield by 3.9 t ha^–1, and was comparable to rice yield obtained with 80 kg N and 12 t FYM ha^–1. This indicated that 12 t FYM ha^–1 could be substituted for 40 kg N as inorganic fertilizer in rice. In addition FYM gave residual effects equivalent to 30 kg N and 13.1 kg P ha^–1 in the succeeding wheat. The effect of single or combined use of inorganic fertilizers and FYM was significantly reflected in the build up of available N, P, K and organic carbon contents of the soil. The relationship for predicting rice yield and nutrients uptake were also computed and are discussed.     

数据挖掘在Internet信息导航系统中的应用研究

面对浩瀚的Ｉｎｔｅｒｎｅｔ信息资源,如何从中快速地获得所需的有价值的知识,是信息时代的一个重要研究课题。数据挖掘是近年来用于开发信息资源的一种新的数据处理技术,本文首先给出了基于数据挖掘的Ｉｎｔｅｒｎｅｔ信息导航系统的一般处理过程,而后着重讨论了数据挖掘在其中的信息收集、查询服务方面的应用。