密封电磁继电器失效机理一致性判别方法研究

航空航天用密封电磁继电器对长期带载可靠性要求较高,通常使用加速退化试验预测其可靠寿命。多应力的加速退化试验中,要求密封电磁继电器失效机理一致,否则得出的寿命预测将有较大偏差。因此加速退化试验失效机理一致性研究,对提高密封电磁继电器可靠寿命预测的准确性具有重要意义。首先基于似然比检测原理,提出一致性判别准则;进而对某典型密封电磁继电器设计加速退化试验,分析试验数据,运用所提准则对其进行一致性检验;得出一致性结论后,实施破坏性物理试验分析永磁体和簧片的退化,对结论进行验证,得到所提一致性判别准则的有效性。

Expression of subtypes of somatostatin receptors in hepatic stellate cells

AIM: To elucidate the mechanism by which somatostatin and its analogue exert the influence on liver fibrosis, and to investigate the mRNA expression of somatostatin receptors subtypes (SSTRs) and the distribution of somatostatin analogue octreotide in rat hepatic stellate cells (HSCs). METHODS: HSCs were isolated from Sprague Dawley (SD) rats by in situ perfusion and density gradient centrifugation. After several passages, the mRNA expression of 5 subtypes of SSTRs were assessed by reverse transcription-polymerase chain reaction (RT-PCR). HSCs were planted on coverslip and co-cultured with octreotide tagged by FITC. Then the distribution of FITC fluorescence was observed under laser scanning confocal microscope (LSCM) in 12-24 h. RESULTS: There were mRNA expression of SSTR2, SSTR3 and SSTR5 but not SSTR1 and SSTR4 in SD rat HSCs. The mRNA expression level of SSTR2 was significantly higher than that of other subtypes (P<0.01). FITC fluorescence of octreotide was clearly observed on the surface and in the cytoplasm, but not in the nuclei of HSCs under LSCM. CONCLUSION: The effect exerted by somatostatin and its analogues on HSCs may mainly depend on the expression of SSTR2, SSTR3 and SSTR5. Octreotide can perfectlycombine with HSCs, and thereby exerts its biological activity on regulating the characters of active HSCs. This provides a potential prevention and management against liver fibrosis.

Modulation of GdCl_3 and Angelica Sinensis polysaccharides on differentially expressed genes in liver of hepatic immunological injury mice by cDNA microarray

AIM: To study the modulating effect of GdCl3 and Angelica Sinensis polysaccharides (ASP) on differentially expressed genes in liver of hepatic immunological mice by cDNA microarray.METHODS: Hepatic immunological injury was induced by lipopolysaccharide (LPS ip, 0.2 mg.kg-1) in bacillus calmetteguerin (BCG ip, 1 mg.kg-1) primed mice; A single dose of 20 mg.kg-1 GdCl3 was simultaneously pretreated and 30 mg.kg-1 ASP (ig, qd×7 d) was administrated when the BCG+LPS was primed. The mice were sacrificed at the end of the 7th day after ip LPS for 6 h and the liver was removed quickly. The PCR products of 512 genes were spotted onto a chemical material-coated glass plate in array. The DNAs were fixed to the glass plate after series of treatments. The total RNAs were isolated from the liver tissue, and were purified to mRNAs by Oligotex.Both mRNAs from the normal liver tissue and the liver tissue from the mice with hepatic immunological injury or that pretreated with GdCl3 or ASP were reversely transcribed to cDNAs with the incorporation of fluorescent dUTP to prepare the hybridization probes. The mixed probes were hybridized to the cDNA microarray. After highstringent washing, the cDNA microarray was scanned for fluorescent signals and showed differences between the two tissues.RESULTS: Among the 512 target genes, 18 differed in liver tissue of hepatic immunological injury mice, and 6 differed in those pretreated by ASP, 7 differed in those pretreated by GdCl3.CONCLUSION: cDNA microarray technique is effective in screening the differentially expressed genes between two different kinds of tissue. Further analysis of those obtained genes will be helpful to understand the molecular mechanism of hepatic immunological injury and to study the intervention of drug. Both ASP and GdCl3 can decrease the number of the differentially expressed genes in liver tissue of mice with hepatic immunological injury.

Mathematical modeling of elastic inverted pendulum control system

Inverted pendulums are important objects of theoretical investigation and experiment in the area of control theory and engineering. The researches concentrate on the rigid finite dimensional models which are described by ordinary differential equations (ODEs) .Complete rigidity is the approximation of practical models ; Elasticity should be introduced into mathematical models in the analysis of system dynamics and integration of highly precise controller. A new kind of inverted pendulum, elastic inverted pendulum was proposed, and elasticity was considered. Mathematical model was derived from Hamiltonian principle and variational methods, which were formulated by the coupling of partial differential equations (PDE) and ODE. Because of infinite dimensional, system analysis and control of elastic inverted pendulum is more sophisticated than the rigid one.

Influence of Kupffer cells on hepatic signal transduction as demonstrated by second messengers and nuclear transcription factors

AIM: To understand the influence of Kupffer cell (KC) on signal transduction pathways in the liver.METHODS: To decrease selectively the number and function of KC, Kunming mice were ip injected with a single dose of gadolinium chloride (GdCl3, 20 mg.kg-1), the time-effect relationship assessment was performed after 1 d, 3 d and 6 d. sALT, sGST, liver glycogen content, phagocytic index,and expression of CD68 were assessed as the indexes of hepatotoxicity and functions of KC respectively, and morphology of KC was observed with transmission electron microscopy. Furthermore, cAMP, PGE2 level, nitric oxide(NO)content, and mRNA expression of NFkappaBp65, Erk1, STAT1 were examined.RESULTS: GdCl3 could selectively cause apoptosis of KC and obvious reduction of KC's activity, but no hepatotoxicity was observed. One day after KC blockade, NO, PGE2, cAMP contents in the liver were reduced 21.0 %, 6.94-fold, 8.3 %,respectively, and mRNA expression of NFkappaBp65 was decreased 3.0-fold. The change tendency of NO, PGE2,and cAMP contents and mRNA expression of NFkappaBp65 were concomitant with recovery of the functions of KC.The contents of NO, PEG2, cAMP were increased when the functions of KC was recovered. However, all of the changes could not return to the normal level except NO content after 6 d Gdcl3 treatment. No obvious changes were found in STAT1 and Erk1 mRNA expression in the present study.CONCLUSION: Hepatic NO, PGE2, cAMP level and mRNA expression of NFkappaBp65 are closely related with the status of KC. It suggests that KC may play an important role in the cell to cell signal transduction in the liver.