氧化铝厂渣浆泵机械密封的失效形式及改进措施

本文介绍了渣浆泵机械密封的失效形式,并根据长期现场工作经验,分析了机械密封泄漏的主要原因,据此提出了改进措施,通过对动静环密封面倒角,改变密封面尺寸及载荷系数后有效地解决了由于径向跳动过大而引起的密封面刮碰擦裂的失效问题。     

阳泉市煤矿采空区地质因素对公路的破坏

介绍了阳泉市煤矿采空区对公路建设所造成的危害，对其上覆岩层变形破坏的地质因素及其破坏机理作了分析，指出应该采取各种措施减少对公路的破坏。     

In situ polymerization and characterization of polyester‐based polyurethane/nano‐silica composites

Polyester‐based polyurethane/nano‐silica composites were obtained via in situ polymerization and investigated by Fourier‐transform infrared spectroscopy (FTIR), or FTIR coupled with attenuated total reflectance (FTIR‐ATR), Transmission electron microscopy (TEM), atomic force microscopy (AFM), an Instron testing machine, dynamic mechanical analysis (DMA) and ultraviolet‐visible spectrophotometry (UV‐vis). FTIR analysis showed that in situ polymerization provoked some chemical reactions between polyester molecules and nano‐silica particles. FTIR‐ATR, TEM and AFM analyses showed that both surface and interface contained nano‐silica particles. Instron testing and DMA data showed that introducing nano‐silica particles into polyurethane enhanced the hardness, glass temperature and adhesion strength of polyurethane to the substrate, but also increased the resin viscosity. UV‐vis spectrophotometry showed that nano‐silica obtained by the fumed method did not shield UV radiation in polyurethane films. Copyright © 2003 Society of Chemical Industry     

预应力钢-混凝土组合梁的应用与研究

回顾了预应力钢 混凝土组合梁国内外应用与研究历史 ,分析了现有规范及理论的不足 ,并指出了有待解决的问题。     

Stress distribution on [100] Si wafer mapped by novel I-V analysis of MOS tunneling diodes

The current-voltage (I-V) characteristics of metal-oxide-semiconductor tunneling diodes distributed over a 3-in Si wafer were analyzed to investigate the stress distribution on the wafer. Generally, the substrate injection saturation current (J/sub sat/) decreases as the gate injection leakage current (J/sub g/) increases, the latter being dominated by oxide thickness via a trap related mechanism. A universal curve to fit all analyzed data was found and it is suggested that devices with extremely high (low) J/sub sat/ at a given J/sub g/ should be located in areas of the silicon lattice with relatively high external compressive (tensile) stress because of the stress-induced bandgap variation effect. The mapped locations of the highly stressed devices on a 3-in [100] Si wafer correspond to the patterns of slips caused by thermal stress during rapid thermal processing, as described in previous reports.     

Renal R2 chemoreceptor activity is attenuated after back heating in the rat

The aim of the present study was to determine the afferent connections of the nucleus accumbens in snakes, in particular its catecholaminergic input. For that purpose, in vitro and in vivo applications of retrograde tracers in the nucleus accumbens of Elaphe guttata were combined with tyrosine hydroxylase (TH) immunohistochemistry. Both techniques revealed telencephalic inputs to the nucleus accumbens originating from the diagonal band of Broca, ventral pallidum, amygdaloid complex, and dorsal cortex. Major diencephalic inputs arise from the dorsomedial thalamic nucleus and the hypothalamus. In the brainstem, a few retrogradely labeled cells were observed in the raphe nucleus and the locus coeruleus. Considerably more cells were found in the midbrain tegmentum. Within the confines of the locus coeruleus and, in particular, the midbrain tegmentum, retrogradely labeled cells stained also for TH suggesting that those areas constitute the major catecholaminergic input to the nucleus accumbens of snakes. The experimental approach used in the present study, in particular the in vitro technique, seems to be very suited for studying the development of basal ganglia organization of reptiles in the near future.     

Synthesis, characteristics and oxygen-sensitive properties of SrMgxTi 1 − xO3 nanocrystals

SrMg_xTi_{1 - x}O₃ nanocrystals (x = 0.1–0.6) were synthesized by the stearic acid gel method. Powder samples were characterized by X-ray diffraction and X-ray photoelectron (XP) spectroscopy. The results showed that the lattice parameter a and the O 1s XP spectrum changed not only with the Mg content x but also with the grain size d of the samples. The conductivity of a thick film specimen fabricated on an aluminium oxide wafer was investigated in a nitrogen—oxygen atmosphere.     

MEASUREMENT OF THE SPECIFIC SURFACE AREA OF POWDERS BY THIN LAYER WICKING

The specific surface areas (A) of different clay mineral powders were measured by both the BET method and by thin layer wicking. The values of A for the BET and the wicking experiments coincided within a few percent. Thus, the simple and inexpensive thin layer wicking approach may well suffice to obtain reliable specific surface area values for most powders. From the wicking data it is also possible to obtain a rough estimate of the average particle size.