共查询到20条相似文献,搜索用时 31 毫秒
1.
采用富氧燃烧实验方法,通过光学显微镜、扫描电子显微镜和能谱仪等手段对GH4169和GH4202高温合金燃烧试样进行分析,建立合金燃烧质量、热量和氧传输模型,探究两种合金的富氧燃烧机理并提出提高新型高温合金抗燃烧性能的措施.结果表明:GH4202与GH4169合金在富氧条件下均发生燃烧,GH4202抗燃烧性能优于GH4169;两种合金以液相进行燃烧,在合金燃烧前沿存在由未完全燃烧的金属颗粒和氧化物组成\ 相似文献
2.
BACKGROUND: Cytokines and cytokine receptors are involved in the systemic and local inflammatory response in patients with urinary tract infections. METHODS: We examined urine and serum concentrations of soluble IL-6 receptor (sIL-6R), IL-10 and granulocyte colony-stimulating factor (G-CSF) in 29 women with acute pyelonephritis caused by Escherichia coli 2 weeks after the infection, during the subsequent episode of cystitis or asymptomatic bacteriuria and also later when the same patients were free from bacteriuria. Concentrations of sIL-6R, IL-10 and G-CSF were related to the expression of five virulence markers of E. coli and to glomerular filtration rate (GFR) after pyelonephritis. RESULTS: On admission because of acute pyelonephritis the serum concentration of sIL-6R was similar to that of 12 healthy controls. Two weeks after the infection when all patients had received antibiotic treatment, the serum concentration of sIL-6R was significantly higher compared to that on admission (p < 0.001) and also higher compared to healthy controls (p = 0.001). Patients with increased concentrations of sIL-6R in serum 2 weeks after infection had significantly lower GFR at follow-up (p < 0.05). Patients with acute pyelonephritis had higher concentrations of G-CSF and IL-10 in serum compared to healthy subjects (p < 0.001 and p = 0.06, respectively). G-CSF in serum was higher in patients infected by E. coli producing cytotoxic necrotizing factor (p < 0.05). Patients infected by strains producing hemolysin had lower concentrations of sIL-6R (p < 0.001). Patients with detectable levels of the anti-inflammatory cytokine IL-10 in serum had significantly higher concentrations of IL-6 and the soluble tumor necrosis factor receptors I and II in serum as compared to patients in whom IL-10 was not detectable (p < 0.001, p = 0.001 and p < 0.05, respectively. CONCLUSION: These investigations, together with our previous findings summarized in this paper, contribute to an increased understanding of the local and systemic inflammatory response arising in response to acute pyelonephritis. 相似文献
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
AV Greco B Ricci G Ghirlanda G Fedeli L Altomonte A Rebuzzi 《Canadian Metallurgical Quarterly》1976,67(45):2902-2918
Recently it has been studied a possible pathogenetic role of GH in diabetic angiopathy. The purpose of the present study was to verify whether the diabetic retinopathy is associated or not with a high plasma GH level. In an attempt to answer this question we did the dosage of plasma GH after a oral glucose load (110 g), Insulin (0,1 U/Kg) i.v., and arginin i.v. (25 g/30'). The plasma GH measurements were approximately the same as in normal patients. The Authors underline the importance of GH in pathophysiology of diabetic angiopathy and report all recent literature on this argument. 相似文献
13.
14.
为研究高铌高磷GH4169C高温合金在高温长期时效过程中的组织稳定性,通过场发射扫描电镜和数显布氏硬度计对GH4169和GH4169C两合金分别经600、650、704及720℃时效30~10000 h的显微组织和硬度变化进行对比分析。结果表明:在服役温度(650℃)范围内长期时效,GH4169合金和GH4169C合金均表现优异的稳定性;在服役温度以上长期时效,GH4169合金和GH4169C合金稳定性较差,短时间内,合金组织就出现失稳。对比而言,704℃时GH4169C合金组织稳定性较GH4169合金高,而720℃时GH4169C合金组织稳定性劣于GH4169合金。分析认为,GH4169C合金由于提高Nb含量和P含量使的γ'相稳定性增加,得以在服役温度以上(704℃)表现比GH4169合金更为优异的组织稳定性,但Nb含量的提高也引起啄相含量的增加,导致组织稳定性下降。在超高温(720℃)下,GH4169C合金稳定性劣于GH4169合金。由此推知,相比GH4169合金,改型GH4169C合金在使用温度上有所提高,但提高有限,在超高温下,其稳定性反而降低。 相似文献
15.
16.
NY Chen WY Chen LJ Striker GE Striker JJ Kopchick 《Canadian Metallurgical Quarterly》1997,138(2):851-854
Bovine growth hormone (bGH) transgenic (Tg) mice have been shown to possess enhanced growth phenotypes and exhibit severe glomerulosclerosis. One amino acid substitution in GH, i.e. G119R in bGH or G120R in human (h) GH, results in GH antagonists (GHAs). GHA-Tg mice exhibit dwarf phenotypes and normal kidneys. In order to investigate the possibility of GHAs as pharmaceutical agents for the treatment of human diseases with excessive GH levels, we cross bred mice that express bGH with those that express hGHA. Double positive Tg mice were identified that express both genes although at different levels. Kidney histological studies revealed that the double positive Tg mice with high GHA/GH expression ratios possessed normal or near normal kidneys, whereas those with low GHA/GH ratios exhibited glomerulosclerosis similar to GH-Tg mice. Thus, co-expression of GH and GHA genes in vivo results in animal phenotypes and kidney histopathologies which are a reflection of the relative expression levels of each gene. 相似文献
17.
《钢铁研究学报(英文版)》2015,(8)
GH4169 alloy has been widely used in fields such as aviation, aerospace, and petrochemical, because of its excellent combination of mechanical and processing properties. These properties include good high-temperature strength, excellent creep and fatigue resistance, and good processing and welding performance. The requirement for high performance, high reliability, and long service life of modern engines has led to the incentive to develop GH4169 alloys with improved performance, such as increased temperature-bearing capacity, improved creep endurance, and better fatigue resistance. Advances during the past thirty years in basic research and industrial technology related to GH4169 alloy were systematically summarized, including advances in alloy modification, melting process optimization, and hot deformation technology. 相似文献
18.
研究了一种新型预熔渣电渣重熔GH3128、GH2132合金的钢锭表面质量、易烧损元素的烧损规律。对电渣锭的头尾,从表面到中心进行了Al、Ti等元素的化学分析和光谱扫描。实验结果表明,使用此预熔渣电渣熔炼GH3128、GH2132合金,可以有效的改善钢锭表面质量,并很好的控制合金的Al、Ti元素烧损。 相似文献
19.
介绍了宝山钢铁股份有限公司特钢事业部首次生产GH99合金锻棒的研究工作。通过热力学相图计算制定了2000t快锻机生产GH99合金棒材的终锻温度以及相应的钢锭加热温度,研究了不同加热温度和终锻温度对GH99合金Φ250快锻棒材组织和性能的影响。结果表明,锻棒横低倍组织无缺陷,但是,加热温度和终锻温度过低时,棒材表面会因变形温度低于动态再结晶温度而残留部分原始拉长晶粒。加热温度和终锻温度过高时,因原始晶粒在加热过程中过分长大,边缘处在变形过程中残留部分大的原始拉长晶粒。在合适的加热温度和终锻温度下,棒材的心部、R/2处和表面均获得了均匀且较细小的晶粒组织,在此条件下,合金具有良好的室温、高温综合性能。 相似文献