Materials: solidification and ostwald ripening of near-monotectic zinc-lead alloys

Studies of melting and resolidification were carried out on Spacelab 1 on the zinc-lead binary, an alloy which exhibits a miscibility gap in the liquid state. The possibility of maintaining the state of homogeneous dispersion of lead in the zinc matrix in a microgravity environment was verified. The second objective of the experiment was to study Ostwald ripening of the lead droplets (manifested as slow coarsening of the droplets) within the region of immiscibility. An increase in droplet size was observed and may have been due to Ostwald ripening, although the effect on droplet size of precipitation during cooling must be analyzed before this can be determined conclusively.     

Panting in dogs: unidirectional air flow over evaporative surfaces

In dogs which are panting due to a heat load, most of the respired air enters through the nose and leaves through the mouth. Different patterns of flow are, however, possible. The unidirectional flow over the evaporative (nasal) surfaces is an important mechanism for regulating the amount of heat dissipated in panting.     

Supramolecular Materials: Self-Organized Nanostructures

Miniaturized triblock copolymers have been found to self-assemble into nanostructures that are highly regular in size and shape. Mushroom-shaped supramolecular structures of about 200 kilodaltons form by crystallization of the chemically identical blocks and self-organize into films containing 100 or more layers stacked in a polar arrangement. The polar supramolecular material exhibits spontaneous second-harmonic generation from infrared to green photons and has an adhesive tape-like character with nonadhesive-hydrophobic and hydrophilic-sticky opposite surfaces. The films also have reasonable shear strength and adhere tenaciously to glass surfaces on one side only. The regular and finite size of the supramolecular units is believed to be mediated by repulsive forces among some of the segments in the triblock molecules. A large diversity of multifunctional materials could be formed from regular supramolecular units weighing hundreds of kilodaltons.     

Potassium: argon dating of iron meteorites

The potassium:argon age of the metal phase of Weekeroo Station iron meteorite, determined by neutronactivation analysis, is about 10(10) years; it is similar to ages previously measured for other iron meteorites, but distinctly disagrees with a strontium: rubidium age of 4.7 X 10(9) years measured by other workers on silicate inclusions in this meteorite.     

山地果园拆装单向牵引式双轨运输机的设计

为克服现有山地果园轨道运输机无法搬移、户外施工难度大、批量生产困难和设备利用率低等问题,设计了一种山地果园拆装单向牵引式双轨运输机,分析该机的总体结构及绳径选择、轨道最小倾角、轨道最长长度、轨道最小转弯半径和断绳制动装置的工作原理,并进行样机运载试验。计算与分析结果显示:运输机钢丝绳直径为7.7mm,轨道最小倾角为5.7°,轨道最长长度为170m,轨道最小水平转弯半径为7m,最小垂直转弯半径为2m。运载试验结果显示:运输机上行平均速度为0.51m/s,下行平均速度为0.54m/s,平均能耗为1.235kW·h,使用有效度为100%。这表明该运输机可适用于山地果园运送肥料和果品等,亦可搭载喷雾机或果枝修剪机械等进行作业。     

猪的脱毛、落屑症

近年来，随着集约化养猪业的发展，在猪场内一种较为常见的以擦痒、脱毛、落屑甚或擦痒部位皮肤组织增生变厚为主要症状的“脱毛”、“落屑”病较为常见(统称为“脱毛症”或“皮肤病”)，给养殖户造成不必要的经济损失。 对猪脱毛、落屑的发病原因，较为常见的有寄生虫性皮肤病和过敏性皮肤病两类。还有湿疹、霉菌性皮肤病、感光过敏性皮肤病、维生素缺乏症也能引起这种症状。……     

Materials: tribology experiment in zero gravity

A tribology experiment in zero gravity was performed during the orbital flight of Spacelab 1 to study the motion of liquid lubricants over solid surfaces. The absence of a significant gravitational force facilitates studies of the motion of liquid lubricants over solid surfaces as controlled by interfacial and capillary forces. Observations were made of phenomena associated with the liquid on one solid surface and also with the liquid between a pair of closely spaced surfaces. Typical photographic records obtained on Spacelab 1 are described.     

牙科铸造合金与口腔组织的生物性反应

牙科铸造合金应用于临床已有百年的历史,在过去20年中,随着治疗要求提高,新型牙科合金飞速发展,其成分和种类发生了巨大的改变,而且关于这些合金的生物安全性也越来越引起人们的关注.本文将就此综述牙科铸造合金与口腔组织的生物性反应的研究进展.     

Chondrules: first occurrence in an iron meteorite

Complete chondrules and fragments of chondrules have been found within silicate inclusions from the octahedrite iron meteorite Netschaevo. The bulk chemical composition, mineralogy, and mineral chemistry indicate that this chondritic material has properties intermediate between those of the H-group chondrites and those of the enstatite chondrites.     

Butler, missouri: an unusual iron meteorite

The Butler iron meteorite has been found to have, with respect to other iron meteorites, an unusually high cobalt content (1.4 percent by weight), unusually high germanium contents in the kamacite and the taenite phases, and an unusually low cooling rate (0.5 degrees C/10(6) years). It is suggested that Butler formed in a different environment from that of the rest of the iron meteorites.     

魏源研究的新材料 --道光甲辰科会试石朱卷

魏源的道光二十四年甲辰(公元1844年)科会试石朱卷为<魏源集>及其它著作集所失收,也未见当今学术界在魏源研究的著作、文章中提及、引用过它.这些魏源研究的新材料对进一步全面、深入地研究魏源,特别对研究他的人才思想具有重要意义.     

Organic Glasses: A New Class of Photorefractive Materials

The performance of amorphous organic photorefractive (PR) materials in applications such as optical data storage is generally limited by the concentration of active molecules (chromophores) that can be incorporated into the host without forming a crystalline material with poor optical quality. In polymeric PR systems described previously, performance has been limited by the necessity of devoting a large fraction of the material to inert polymer and plasticizing components in order to ensure compositional stability. A new class of organic PR materials composed of multifunctional glass-forming organic chromophores is described that have long-term stability and greatly improved PR properties.