离子注入改进陶瓷表面可焊性机理分析

进行了Ni+( 1 3 0keV)、Ti( 1 50keV)离子注入Al2 O3(质量分数为 85% ) -ZrO2 (质量分数为 1 5% )陶瓷表面改性试验 ,对改性陶瓷材料表面进行了X -光衍射谱物相分析、表面导电性分析以及与不锈钢材料的非活性钎焊性能分析。结果表明 ,注Ni+和注Ti+陶瓷表层导电性未发现明显变化 ,而注Ti+的陶瓷表层材料在注入剂量达到3× 1 0 17ions/cm2 时其导电性有明显的提高 ,这是由于在陶瓷材料表层生成的钛氧化物的导电性较高的原故。离子注入确实可以显著提高陶瓷材料的可焊性 ,但提高陶瓷材料表面导电性并不是提高其钎焊性能的主要因素。     

Sterol glycosides and cerebrosides accumulate in Pichia pastoris, Rhynchosporium secalis and other fungi under normal conditions or under heat shock and ethanol stress

The occurrence of glycolipids such as sterol glycosides, acylated sterol glycosides, cerebrosides and glycosyldiacylglycerols was examined in the three yeast species Candida albicans, Pichia pastoris and Pichia anomala, as well as in the six fungal species Sordaria macrospora, Pyrenophora teres, Ustilago maydis, Acremonium chrysogenum, Penicillium olsonii and Rhynchosporium secalis. Cerebroside was found in all organisms tested, whereas acylated sterol glycosides and glycosyldiacylglycerols were not found in any organism. Sterol glycosides were detected in P. pastoris strain GS115, U. maydis, S. macrospora and R. secalis. This glycolipid occurred in both yeast and filamentous forms of U. maydis but in neither form of C. albicans. This suggests that sterol glycoside is not correlated with the separately grown dimorphic forms of these organisms. Cerebrosides and sterol glycosides from P. pastoris and R. secalis were purified and characterized by mass spectrometry and nuclear magnetic resonance spectroscopy. The cerebrosides are beta-glucosyl ceramides consisting of a saturated alpha-hydroxy or non-hydroxy fatty acid and a Delta4,8-diunsaturated, C9-methyl-branched sphingobase. Sterol glycoside from P. pastoris was identified as ergosterol-beta-D-glucopyranoside, whereas the sterol glucosides from R. secalis contain two derivatives of ergosterol. The biosynthesis of sterol glucoside in P. pastoris CBS7435 and GS115 depended on the culture conditions. The amount of sterol glucoside in cells grown in complete medium was much lower than in cells from minimal medium and a strong increase in the content of sterol glucoside was observed when cells were subjected to stress conditions such as heat shock or increased ethanol concentrations. From these data we suggest that, in addition to Saccharomyces cerevisiae, new yeast and fungal model organisms should be used to study the physiological functions of glycolipids in eukaryotic cells. This suggestion is based on the ubiquitous and frequent occurrence of cerebrosides and sterol glycosides, both of which are rarely detected in S. cerevisiae. We suggest P. pastoris and two plant pathogenic fungi to be selected for this approach.     

Culture characteristics of carotenoid-producing filamentous fungus T-1, and carotenoid production

The culture characteristics, carotenoid production, and associated biosynthetic pathway of strain T-1 were examined. As a result of examining the culture temperature and light irradiation, an increase of neurosporaxanthin and neurosporaxanthin beta-D-glucopyranoside was observed at a low temperature and 0 lx. It was suggested that highly polar carotenoids, such as neurosporaxanthin, and carotenoid glycosides were involved in the stabilization of membrane during nutrition storage other than the defense function of fungus bodies. Strain T-1 produced lycopene, beta-carotene, gamma-carotene, torulene, neurosporaxanthin, and neurosporaxanthin beta-D-glucopyranoside, as assessed by HPLC, LC-MS, and NMR analysis. Carotenoid biosynthesis begins with neurosporene, passing to lycopene and gamma-carotene through cyclization, and produces beta-carotene. In addition, it is saturated, gamma-carotene is converted to torulene, and neurosporaxanthin is produced. Thus, the carotenoid biosynthetic pathway in strain T-1 was estimated.     

纤维层厚度对陶瓷复合靶板抗弹性的影响

用12.7mm穿燃弹对几种不同厚度玻纤布配置的陶瓷复合靶板进行垂直侵彻试验,以研究陶瓷复合靶板面基板间纤维层厚度对靶板抗枪弹性能的影响。试验以有效弹速下弹丸对靶板的总穿深作为靶板抗弹性能的衡量指标,作以比较。试验结果表明,随面基板间玻纤布的厚度增加靶板防护能力降低。从应力波、约束机制、背强效应等方面对其原因作了分析。     

缩比件弹体侵彻混凝土过程相似律研究

在模拟实验条件下 ,研究了不同缩比件钨合金弹体侵彻混凝土过程的相似性。结果表明 ,钨合金弹体侵彻混凝土靶体时 ,在高速区侵彻深度与弹速间存在线性关系 ;弹体直径较大时 ,可以把不同直径弹体侵彻过程受到的平均压力看作相等 ,并且侵彻过程存在几何相似性     

Effect of active oxygen species on the productivity of torularhodin by Rhodotorula glutinis No. 21

The effect of active oxygen species on the productivity of torularhodin, an effective antioxidant, by soil yeast, Rhodotorula glutinis no. 21, was examined. Methylene blue, methyviologen and AAPH [2,2'-azobis(2-amidinopropane) dihydrochloride] were used as generators of singlet oxygen, superoxide anion radicals and peroxy radicals, respectively. All of them indicated effectiveness at a dose of 1.0 x 10(-10) to 3.0 x 10(-6) M. Addition of these generators to the culture medium had almost no influence on the biosynthesis of beta-carotene, whereas it had marked enhancement on those of torulene and torularhodin. Production of uric acid by xanthineoxidase remained unchanged at a torularhodin concentration of up to 100 microM. This result suggests that torularhodin does not directly affect the productivity of superoxide anions. It has been proved that torularhodin has a more potent effect on the scavenging of peroxyl radicals and inhibits substrate degradation by singlet oxygen more effectively than beta-carotene does. Continuous addition of methylene blue enhanced the torularhodin accumulation more markedly than single addition.     

晶粒尺寸对疲劳应力强度因子门坎值的影响

本文探讨了PCrNilMoVA及PCrNi3MoVA钢的晶粒尺寸和疲劳应力强度因子门坎值△K_(th)之间的关系。实验结果表明,随d增大,△K_(th)也相应地增大。 文中基于位错理论,提出疲劳应力强度因子门坎值△K_(th)由两部分组成,即:△K_(th)=△K_(th)~*+△K_(th)~d,△K_(th)~*与晶粒尺寸无关;△K_(th)~d表示使裂纹尖端激发出来的位错能够到达晶界的条件,它与√d呈正比关系。模型与实验结果相一致。     

夹层材料抗弹效益表征参量研究

对采用不同夹层材料的动态防护单元进行了抗弹性能试验研究,并对部分方案的射流出靶姿态拍摄了X光照片。试验结果表明,夹层材料的波阻抗(pc)是动态防护单元抗弹效益的表征參量。通过对试验结果分析,提出动态防护单元夹层材料的选用原则。     

钨合金穿甲弹侵彻装甲反向喷溅金属流的性态

通过解剖钨合金穿甲模拟弹侵彻装甲钢时在装甲钢中留下的弹坑发现 ,当装甲是 2 0 0℃回火态时 ,弹坑坑口直径大于弹杆直径 ,弹坑内没有留下反向喷溅金属流的残留物 ;当装甲是 4 70℃回火态时 ,在坑口附近出现反向喷溅金属流的堆积物。由于出现这些堆积物使坑口直径小于弹体直径。坑口附近的堆积物曾是熔化了的装甲 ,在堆积物中还有没有熔化、呈块状的装甲颗粒 ,在堆积物中没有钨或钨合金的痕迹。这些结果表明 ,侵彻过程中穿甲弹的挤压是将装甲液体化 ,凿是将装甲凿成颗粒 ,使其成为反向喷溅的金属流 ,即液态金属和颗粒的混合物     

SiC－TiC陶瓷韧化机制探讨

采用ＣＶＤ法合成ＳｉＣ－ＴｉＣ陶资，探讨了ＴｉＣ含量与断裂韧性之间的关系。结果表明，当ＴｉＣ体积含量为４０％时，断裂韧性高达７．０ＭＰａ·ｍ１／２韧化效应归功于闭合效应以及弯曲效应。断裂韧性与体积含量之间存在ＫＩＣ＝［（ＫＩＣ０）＋Ｂｖｉ］　ＫＩＣ０＝（１＋Ａ）ＫＩＣｍ关系。建立的韧化模型与实验结果相一致。