航空电气马达测试系统的研制

结合所完成的航空马达测试系统,论述航空马达的测试要求及实施方案,详细介绍其工作原理,包括加载系统、测量与显示系统及配电控制系统的结构和工作特点。最后指出了航空马达综合测试的发展方向。     

Double-helix coil for occlusion of large patent ductus arteriosus: evaluation in a chronic lamb model

Glyceraldehyde-3-phosphate dehydrogenase (G3PDH) is often used as a control gene for mRNA expression, however it has been proposed to be overexpressed in all hepatocellular carcinomas (HCC). Equal amounts of tumor and paired normal (T/N) RNA, based on OD260/280 nm, were compared using ethidium bromide staining, poly-T probing, gene-specific dot blot and Northern blots using control probes G3PDH, actin and histone H4. Using mRNA blots 13/20 surgical HCC pairs did not overexpress G3PDH. Those 7/20 intact samples which did appear to overexpress G3PDH on Northern blot could not be detected by poly-T probing of dot blots. The apparent overexpression was not specific for the control gene G3PDH nor for the malignancy HCC. It may represent partial mRNA degradation, or the presence of as yet unknown substances which interfere with absorption at 260/280 nm. We advise caution in selecting human T/N pairs for differential gene expression studies. For HCC, no clinicopathological variables, including cirrhosis, predicted whether a T/N sample pair was likely to be balanced or not.     

The effect of transdermal nicotine on digital perfusion in reformed habitual smokers

The effects of transdermal nicotine-assisted smoking cessation on digital perfusion and health-related quality of life were assessed in 10 chronic smokers. Components of digital blood flow were evaluated by digital temperature and laser Doppler fluxmetry before, during, and after a standardized cold challenge. Nutritional flow was measured by vital capillaroscopy; a quantitative perfusion profile was obtained by laser Doppler perfusion imaging. A battery of validated measures were used to evaluate health-related quality of life. The microvascular response of smokers was evaluated before smoking cessation and at 2 and 7 days after smoking cessation and was compared with the response of nonsmoking controls. Results demonstrated that a (1) cutaneous microvascular perfusion was lower in smokers than nonsmokers, (2) the acute administration of transdermal nicotine did not decrease cutaneous perfusion, (3) smoking cessation and transdermal nicotine normalized digital microvascular perfusion by 7 days, and (4) transdermal nicotine and smoking cessation did not negatively impact health-related quality of life.     

Fate of Escherichia coli O157:H7 in ground apples used in cider production

Survival of Escherichia coli O157:H7 in ground Golden Delicious, Red Delicious, Rome, and Winesap apples stored at 4, 10, and 25 degrees C was determined. E. coli O157:H7 populations were monitored for up to 18 days (4 degrees C), 12 days (10 degrees C), and 5 days (25 degrees C), when mold contamination became visible. At 25 degrees C, Red Delicious apples supported survival of E. coli O157:H7 better (P < 0.05) than the other cultivars, followed by Golden Delicious and Rome apples, which were not statistically different (P > 0.05). Winesap apples were the least favorable (P < 0.05) for survival of E. coli O157:H7 at 25 degrees C. E. coli O157:H7 was recovered at similar rates from Golden Delicious and Red Delicious apples, (P > 0.05), but pathogen populations increased in both cultivars (P < 0.05) during storage at 25 degrees C. At 10 degrees C, survival of E. coli O157:H7 was poorest (P < 0.05) in ground Red Delicious apples, while there was no significant difference in survival of E. coli O157:H7 among ground Golden Delicious, Rome, or Winesap cultivars (P > 0.05). When stored at 4 degrees C, Golden Delicious and Rome apples were not statistically different in supporting survival of the pathogen (P > 0.05). In general, apple pH increased during storage and was associated with mold growth. Results of this investigation indicate that there is no trend toward a particular apple cultivar supporting survival of E. coli O157:H7. However, variation in apple pH during storage can negatively or positively influence E. coli O157:H7 survival at 25 degrees C.     

Extension of the thermodynamics of small systems to open metastable states: an example

By using a simplified model of small open liquid-like clusters with surface effects, in the gas phase, it is shown how the statistical thermodynamics of small systems can be extended to include metastable supersaturated gaseous states not too far from the gas-liquid equilibrium transition point. To accomplish this, one has to distinguish between mathematical divergence and physical convergence of the open-system partition function.     

A Monte Carlo simulation of silicon nitride thin film microstructure in ultraviolet localized-chemical vapor deposition

Microstructural changes of surfaces and bulk of a SiN: H were investigated at the atomic level by a simulator. The simulator is based on a solid-on-solid type model for ultraviolet localized-chemical vapor deposition. The calculations consider the well-defined photolysis products adsorbed at atomic sites. Incorporation of main species is enabled by a Monte Carlo-Metropolis simulation technique. Photodeposition rates are obtained using bond dissociation energies. In this manner, the dependence of root-mean-square deviation of surface roughness and bulk porosity on operating conditions can be predicted. Photonucleation and photodeposition with a UV low pressure mercury lamp at low pressure and temperature were simulated onto indium phosphide substrate.     

Exploring the software development trilogy

Software development is concerned with more than just generation of code; the program must have the desired properties, and these must be demonstrated via suitable tests and correctness arguments. One way of viewing these aspects is to group them into programs, properties, and data. When represented as vertices in a triangle, the edges represent processes to produce one element from another. The research reported in this article aims at practical methods for automatic test generation by restricting the use of both predicate logic and programming constructs. It promises to eventually result in practical domain-specific programming languages, with a significant boost in both quality and productivity