Interface microstructure and reaction in Gr/Al metal matrix composites

The interface structure in Gr/Al composites fabricated with liquid metal infiltration has been studied using transmission electron microscopy (TEM). Morphologies of interfacial reaction product, aluminium carbide Al₄C₃, formed at different manufacturing parameters were compared and, the growth mechanism of the carbide was studied by means of high resolution electron microscopy (HREM). It has been shown that the morphology of the carbide is intimately related to the processing parameters with which the composites were produced. There are two kinds of interfaces between the carbide and the aluminium matrix. They have different growth mechanisms and relative growth rates under different growth driving forces. Several crystal orientation relationships between the carbide and the aluminium matrix have been observed.     

Electrochemical Investigation on the Formation of Dy-Fe Alloy in Molten Chlorides

ＥｌｅｃｔｒｏｃｈｅｍｉｃａｌＩｎｖｅｓｔｉｇａｔｉｏｎｏｎｔｈｅＦｏｒｍａｔｉｏｎｏｆＤｙＦｅＡｌｏｙｉｎＭｏｌｔｅｎＣｈｌｏｒｉｄｅｓＬｉｕＧｕａｎｋｕｎ（刘冠昆），ＴｏｎｇＹｅｘｉａｎｇ（童叶翔），ＨｏｎｇＨｕｉｃｈａｎ（洪惠婵），Ｙａｎｇ...     

液体火箭发动机研制情况的一些回顾

４０年来，我国液体火箭发动机的研制工作取得了很大成绩。文中对发动机的一些研制情况作了回顾，对ＹＦ－７３和ＹＦ－７５氢氧发动机的设计特点、飞行结果作了简单叙述。对今后工作也提出了看法。     

Effects of interstitial oxygen on microstructure and mechanical properties of Ti-48Al-2Cr-2Nb with fully lamellar and duplex microstructures

The effect of added oxygen in the range of 1000 to 4000 wt ppm on the microstructures of a Ti-48Al-2Cr-2Nb alloy has been investigated and compared to the microstructures for a high-purity alloy. For specimens cooled from theα phase, interstitial oxygen stabilizes the lamellar microstructure with respect toγ grains, with higher than equilibrium values for theα ₂ volume fraction. For specimens cooled from theα +γ phase field, the lamellar microstructure still tends to be favored by oxygen, but it is found that the phase volume fractions are not significantly different from equilibrium values. This suggests that interstitial O essentially reduces the kinetics of theα toα +γ transformation. Thus, interstitial oxygen will have a strong effect on microstructures obtained by continuous cooling fromα, but significantly less on those, such as the duplex microstructure, obtained by long treatment in theα +γ phase field. In general, increased O content is well correlated with reduced ductility. Finally, the role of interstitial oxygen on this phase transformation is discussed.     

Synteny mapping of four genes from the short arm of human chromosome 19 to bovine chromosome 7

Four genes on the short arm of human chromosome 19 (HSA 19p) were assigned to bovine chromosome 7 (BTA 7) using a bovine x rodent somatic hybrid cell panel. These four genes were cartilage oligomeric matrix protein (COMP), lymphoblastic leukemia derived sequence 1 (LYL1), lysosomal alpha-mannosidase (MANB), and RAS oncogene family member RAB3A. Bovine sequence tagged sites were developed for the four genes and used for screening a bovine x rodent somatic cell panel. All four genes were mapped to bovine synteny group U22 (BTA 7) with a correlation coefficient of 0.901-1.000. This study confirms that the centromeric region of BTA 7 is conserved with HSA 19p.     

GaAs亚微米自对准工艺技术研究

总结了在５０ｍｍＧａＡｓ圆片上实现自对准介质膜隔离等平面工艺技术的研究，着重描述了离子注入、自对准亚微米难熔栅制备、钝化介质膜生长、干法刻蚀、电阻和电容制备等关键工艺的研究结果。这套工艺的均匀性、重复性好，在５０ｍｍＧａＡｓ圆片上获得了满意的成品率。采用这套工艺已成功地研制出多种性能良好的ＧａＡｓＩＣ和ＧａＡｓ功率ＭＥＳＦＥＴ，证明国家自然科学基金委员会这一重大课题的选择对发展我国ＧａＡｓＩＣ确实具有重大意义。     

Effect of quercetin on chemiluminescence of human platelets induced by arachidonic acid

Arachidonic acid (AA)-induced platelet chemiluminescence (CL) was measured with a lumiphotometer. Quercetin remarkably inhibited the CL, the IC50 of quercetin was 3 mumol.L-1. When quercetin plus aspirin, which inhibits only cyclooxygenase, was added, the inhibitory rate of platelet-CL obviously increased (P < 0.01). On the other hand, the quercetin had a scavenging effect on superoxide anion radical using alkaline sodium dithionite solution generation. The IC50 was 20.9 mumol.L-1. In addition, superoxide dismutase of 0.1 mg.ml-1 inhibited the platelet-CL by 97.8%, while mannitol, a hydroxyl radical scavenger, only by 43.3% at a concentration of 80 mg.ml-1. These results suggest that the mechanism of the inhibiting AA-induced platelet-CL by quercetin was associated with scavenging the superoxide anion radical directly and with inhibiting the cyclooxygenase.     

A microwave Gaussian-beam launcher with an active aperture-blockageto control the spot-size of the beam

A method of controlling the spot-size of a focused microwave Gaussian-beam using an active aperture-blockage is described. The Gaussian-beam launcher consists of an open-ended scalar-horn with a dielectric hyperhemisphere at its aperture. Also included is an AgI-pellet at the aperture-center with a provision to heat it with an external dc source. The scalar-horn plus the dielectric lens launch a Gaussian-beam; and, the AgI pellet when heated, becomes a superionic conductor offering an aperture-blockage. This results in a variation of the spot-size of the emergent-beam. Theoretical results and experimental data are furnished and compared