Pt／Ti爆炸焊接及爆后轧制双金属断面形态与界面结构分析

用扫描电镜、能谱、Ｘ射线衍射仪对Ｐｔ／Ｔｉ爆炸焊接及爆后轧制双金属断面形态与界面结构进行的分析表明：爆炸焊接界面上有断续的新生化合物层，此层是由ＰｔＴｉ、ＰｔＴｉ３、Ｐｔ５Ｔｉ３等化合物组成的混合组织，有很高的结合强度，强制拉断在界面Ｐｔ侧。爆后轧制态界面上有大量龟裂块；化合物减少，以ＰｔＴｉ、Ｐｔ３Ｔｉ为主，龟裂块是导致沿界面拉开的原因。     

时效对Cu-1.0Ni-0.25Si-0.10Zn合金硬度与导电率的影响

分析了时效与冷变形对Cu 1.0Ni 0 .2 5Si 0 .10Zn合金的硬度与导电率的影响规律 ,结果表明 :合金经 85 0℃固溶处理后在 4 5 0℃时效时 ,第二相呈弥散分布 ,表现出较大的稳定性 ,在 5 2 5℃时效时第二相的析出速度较快 ,时效后可获得较高的导电率 ;时效前的冷变形可以加速时效析出过程 ,在时效的初期尤为明显。合金采用分级时效工艺处理后 ,可得到高的硬度 (HV171)和较高的导电率 (5 9.5 %IACS)。     

上海及其邻区潜在地质灾害的活动构造背景

分析了上海及其邻区的２０００多个钻孔资料，完成了两条四系构造钻孔部面及两条长蹑离氧浓度探测剖面，从而初步揭示出发育于上海及其邻区第四系松软盖层内的“韧性剪切构造”。     

低温处理后由低钾诱发的大鼠心室肌触发性活动

大鼠心室肌纤维经低温(4℃)处理19—21小时后,动作电位幅度及复极50％时的动作电位时程无明显变化,而复极90％的时程明显延长。低钾(0.75—1.5mmol/L)灌流可使低温处理的标本产生迟后去极化(DAD)以及由此产生触发性活动(TA)。施与额外电刺激对TA无影响,或引起该节律的重排,然而不能使之终止。肾上腺素(1μg/ml)或高钙(5.4mmol/L)可以增加DAD幅度,从而使TA更易发生。TI~+(1.5mmol/L)及Mn~(2+)(3mmol/L)可抑制DAD及TA。以上结果表明,低温处理后大鼠心室肌细胞电生理特性发生改变,对钠钾泵抑制剂—低钾—敏感性增高,因而易产生DAD及TA。     

Functional and biochemical characteristics of mitochondrial fractions from rat liver in cold-induced oxidative stress

We determined characteristics of rat liver mitochondrial fractions, resolved at 1000 (M₁), 3000 (M₃), and 10,000 g (M₁₀) after 2 and 10 days cold exposure. In all groups, the M₁ fraction exhibited the highest oxidative capacity, oxidative damage, H₂O₂ production rate, and susceptibility to stress conditions, and the lowest antioxidant levels. Cold exposure increased cytochrome oxidase activity in all fractions and succinate-supported O₂ consumption in the M₁ and M₁₀ fractions during state 3 and state 4 respiration, respectively. With succinate, the H₂O₂ release rate increased in all fractions during state 4 and state 3 respiration, whereas with pyruvate/malate, it increased only during state 4 respiration. Increases in tissue mitochondrial proteins caused a faster H₂O₂ flow from the mitochondrial to cytosolic compartment, which was limited by the reduction in the M₁ fraction. Despite increased liposoluble antioxidant levels, cold also caused enhanced oxidative damage and susceptibility to oxidative challenge and Ca²⁺-induced swelling in all fractions. These changes leading to elimination of H₂O₂-overproducing mitochondria avoided excessive tissue damage. We propose that triiodothyronine, whose levels increase in the cold environment, brings about the biochemical changes producing oxidative damage and those limiting its extent.Received 16 July 2004; received after revision 27 September 2004; accepted 18 October 2004     

Preparation, microstructure and degradation performance of biomedical magnesium alloy fine wires

With the development of new biodegradable Mg alloy implant devices, the potential applications of biomedical Mg alloy fine wires are realized and explored gradually. In this study, we prepared three kinds of Mg alloy fine wires containing 4 wt% RE(Gd/Y/Nd) and 0.4 wt% Zn with the diameter less than 0.4 μm through casting, hot extruding and multi-pass cold drawing combined with intermediated annealing process. Their microstructures, mechanical and degradation properties were investigated. In comparison with the corresponding as-extruded alloy, the final fine wire has significantly refined grain with an average size of 3–4 μm, and meanwhile shows higher yield strength but lower ductility at room temperature. The degradation tests results and surface morphologies observations indicate that Mg–4Gd–0.4Zn and Mg–4Nd–0.4Zn fine wires have similar good corrosion resistance and the uniform corrosion behavior in SBF solution. By contrast, Mg–4Y–0.4Zn fine wire shows a poor corrosion resistance and the pitting corrosion behavior.     

全循环干馏炉内油页岩颗粒流动规律

采用离散元方法建立了300 t/d气体全循环油页岩干馏炉三维数学模型,研究了干馏过程中油页岩颗粒的流动行为;搭建了1:6比例的干馏炉冷态物理模型,验证了数学模型的准确性。结果表明,油页岩颗粒在炉内流动过程中流型呈现“一”→波浪型→“W”→不规则“V”的演变过程。颗粒与炉墙壁面的摩擦,使流动形态沿半径方向呈现波浪型,中心柱与阿西结构的阻滞作用使流型进一步变为“W”型与不规则的“V”型,促进了干馏段的颗粒混合,有利于干馏过程的进行;干馏段结构的支撑和分流作用,使得干馏段下部颗粒结构疏松,颗粒在此阶段加速流动,同时阿西结构的分流作用使气体热载体与油页岩颗粒发生剧烈的掺混,提高了换热面积。冷却段炉壁顶角区域出现的“死料区”,可能导致物料黏结,进一步堵塞出料口,影响干馏过程的顺利进行。对炉内相互作用力进行分析表明,炉内相互作用力大小主要在0~200N,1000N以下约占90%,在可承受载荷范围内;炉内磨损分析表明,法向累计接触能较小,切向累计接触能较大且集中在阿西结构下部,表明颗粒的流动摩擦是磨损的主要原因,实际干馏中,气体热载体会与油页岩颗粒发生掺混换热,磨损情况会更严重。     

集成预润滑式发动机机油泵试验研究

为解决发动机启动过程中,润滑油不能及时输送到各摩擦副表面,短时间内处在边界摩擦或固体干摩擦润滑状态下产生剧烈磨损的问题,设计气动马达辅助驱动的集成预润滑式机油泵总成作为解决方案。依托于发动机润滑系统试验台架,通过改变润滑系统的初始状态（贫油或富油）、气动马达的进气压力,进行发动机的预润滑过程及冷启动过程试验研究。结果表明：集成预润滑式发动机机油泵在进气压力2~6 bar的工况下能够迅速建立起稳定的1 bar以上的主油道机油压力;当进气压力为3 bar时,发动机冷启动主油道油压达到标定油压的时间提前7~8 s。可见,集成预润滑式机油泵总成能够有效地进行发动机启动预润滑,避免在发动机冷启动阶段轴承等运动摩擦副发生固体干摩擦而导致的磨损。     

水泥冷再生技术在沥青路面大修工程中的应用

水泥冷再生施工工艺应用于沥青路面大修工程中,既能减少破除路面造成的污染,又能降低工程造价,缩短施工工期,可采用半幅封闭施工而不中断交通.本文结合具体的工程实例,对水泥冷再生基层技术施工工序和要点进行了详细介绍,并就其工程造价与传统工艺造价进行了比较.