航天发动机用的钛合金壳体

自从60年代初期以来,6Al—4V钛合金就被广泛地用于航天发动机壳体。本文描述了钛合金火箭发动机壳体(其最小极限抗拉强度的设计值达到175,000磅/英寸~2。)从锻件到加工成产品的工艺制造过程。对设计经验和该产品独特的工艺控制过程,如热处理和金相检验,也给予评论。本文对钛合金压力容器的优点,如多次使用、推力向量校准以及附加法兰和部件易于组合等,都作了介绍。     

The ankle ergometer: a new tool for quantifying changes in mechanical properties of human muscle as a result of spaceflight

A mechanical device for studying changes in mechanical properties of human muscle as a result of spaceflight is presented. Its main capacities are to allow during a given experiment investigation of both contractile and visco-elastic properties of a musculo-articular complex using respectively isometric contractions, isokinetic movements, quick-release tests and sinusoidal perturbations. This device is a motor driven ergometer associated to an experimental protocol designed for pre- and post-flight experiments. As microgravity preferentially affects postural muscles, the apparatus was designed to test muscle groups crossing the ankle joint. Three subjects were tested during the Euromir '94 mission. Preliminary results obtained on the european astronaut are briefly reported. During the next two years the experiments will be performed during six missions.     

New methods for microbial contamination monitoring: an experiment on board the MIR orbital station

Experiment T2, carried out during the Euromir'95 mission, was an important step toward innovative methods for spacecraft microbial contamination monitoring. A new standard sampling technique permitted samples to be analysed by different means. On board, two analysis methods were tested in parallel: Bioluminescence and Miniculture. In turn, downloaded samples are being analysed by polymerase chain reaction (PCR), a powerful and promising method for the rapid detection, identification and quantification of pathogens and biofouling agents in closed manned habitats.     

高校图书馆人力资源管理现状及对策

随着高新技术的发展,人力资源管理已成为影响高校图书馆建设与发展的重要因素。本文分析了高校图书馆人力资源管理中出现的误区,并从五个方面探讨了改善当前高校图书馆人力资源管理现状的对策和方法。     

固体推进剂火箭发动机最大性能

目前,广泛地应用热化学模型预算发动机的最大性能,而且模型假定流场是一维的。然而,实验与计算表明,其内部流动可能具有显著的横向总压梯度,这将引起性能偏离一维流模型的计算结果。但在整体分析的范围内研究了这些影响。发现对有喷管的发动机是可以忽略的。     

Taxane recovery from cells of Taxus in micro- and hypergravity

Cell suspension cultures of Taxus cuspidata produce taxanes that are released from the outer surface of cells into the culture medium as free and bound alkaloids. Paclitaxel (Taxol (TM)), is an anti-cancer drug in short supply. It has a taxane ring derived from baccatin III and a C-13 phenylisoserine side-chain. This drug is produced over a wide range of gravitational forces. Monoclonal and polyclonal antibodies to paclitaxel, baccatin III, and the C-13 phenylisoserine side chain were combined in multiple-labeling studies to localize taxanes and paclitaxel on cell surfaces or on particles released into the culture medium. Bioreactor vessel design altered the composition of taxanes recovered from cells in simulated microgravity. At 10(-2) and 2x10(-4)g, taxane recovery was reduced but biomass growth and percent paclitaxel was significantly increased. At 1 to 24g, growth was reduced with a significant recovery of total taxanes with low percent paclitaxel. Bound paclitaxel was also localized in endonuclease-rich fragmenting nuclei of individual apoptotic cells. A model is presented comprising TCH (touch) genes encoding enzymes that modify taxane-bearing xylan residues in cell walls, the calcium-sensing of gravitational forces by the cytoplasm, and the predisposition of nuclei to apoptosis. This integrates the adaptive physiological and biochemical responses of drug-producing genomes with gravitational forces.     

中国空军的志愿队

空中作战出现有志愿队 ,乃起自西班牙的佛朗哥内战时代 ,当时双方参与作战的飞行员 ,有来自英、美、苏联、德、意、法等国 ,他们参与的动机 ,多少与其本国的政治背景有关。彼此使用不同的机种 ,互相在空中逞强逞勇 ,借机表演一场国际性的空中比武而已 ,反正胜负都是西班牙人自己的事。我国自七七芦沟桥对日抗战之后 ,于翌年春中国空军已成立一志愿队 ,名为十四队 ,直属于航空委员会。当时航委会的主任是钱大钧将军。队部设在汉口公园内 ,队中的飞行员与地勤人员 ,中外国藉皆有 ,队长是美人史密斯( SMITH) ,年近四十 ,机务员是英人司密时 ,…     

涡轮叶栅前缘上游端壁气膜冷却的流场实验研究

对前缘上游端壁有单排和双排孔冷却的大尺寸低速涡轮导向叶栅进行了气动测量、热示踪和端壁流场显示,在吹风比1～3范围获得了叶栅内的详细流场、冷气的空间分布和端壁上的流动图案。结合先前测得的没有冷却时的流场数据,这些结果表明端壁气膜冷却对叶栅流场结构有重大影响,吹风比是主宰射流与二次流间相互作用的主要因素,双排孔喷射使冷气比单排孔喷射更贴近端壁。低吹风比喷射冷气不能到达压力面并被二次流逐渐卷离端壁;中吹风比喷射有效的抑制了二次流的形成,并使端壁流线偏向于无粘流流线,冷气很均匀的覆盖在端壁上。      

Sugar synthesis from a gas-phase formose reaction

Prebiotic possibilities for the synthesis of interstellar ribose through a protic variant of the formose reaction under gas-phase conditions were studied in the absence of any known catalyst. The ion-molecule reaction products, diose and triose, were sought by mass spectrometry, and relevant masses were observed. Ab initio calculations were used to evaluate protic formose mechanism possibilities. A bilateral theoretical and experimental effort yielded a physical model for glycoaldehyde generation whereby a hydronium cation can mediate formaldehyde dimerization followed by covalent bond formation leading to diose and water. These results advance the possibility that ion-molecule reactions between formaldehyde (CH(2)O) and H(3)O(+) lead to formose reaction products and inform us about potential sugar formation processes in interstellar space.