MORPHOLOGY OF SUB-CRITICAL GROWTH ON STRESS CORROSION CRACKING AND PLASTIC ZONE AT CRACK TIP

用抛光的恒载荷试样对40CrNiMoA和AISI4330M两种高强度钢在水介质中应力腐蚀裂纹的产生和扩展进行了金相跟踪观察,研究了裂纹亚临界扩展的形貌。结果表明:表面裂纹前端产生阴影区(塑性变形区),它的形貌随钢种不同而不同。对于40CrNiMoA,阴影区是扩展、闭合,再扩展、再闭合。而对于4330M,阴影区不闭合,近乎平行扩展。只有在刚开始加载、阴影区呈耳朵状时,它才反映了裂纹尖端的塑性区。在以后绝大部分的扩展过程中,阴影区并不代表裂纹尖端的塑性,而只反映产生剪切唇所引起的变形,且与裂纹的“突进”(Pop-in)密切有关,必须和小范围屈服断裂力学中裂纹尖端的塑性区相区别。     

Use of psychotropic drugs in gynecological, surgical, and medical wards of general hospitals

Using 1985 and 1988 American Hospital Association data, this study examines 1,523 hospitals nationwide and concludes that hospitals' ownership of skilled nursing facilities helps minimize the transaction costs associated with post-acute patient transfers while productively using empty hospital beds. Unfortunately, such ownership creates complex cost, quality, and accessibility trade-offs in terms of the skilled nursing care provided.     

Relationship between the included levels of coffee pulp and the protein content in rations for monogastric animals

The purpose of this research was to determine the effect of including fresh and ensilaged coffee pulp in rations for monogastric animals, and find the best protein and coffee pulp levels in rations for rats. Fresh coffee pulp and pulp ensilaged for 12 months were used; both kinds of pulp were sun-dried before incorporating them into the rations. The chemical analyses of the pulps revealed a lower content in caffeine, tannins, chlorogenic acid and caffeic acid in the ensilaged pulp than in fresh coffee pulp. Thirty-two experimental rations were prepared, 16 with fresh coffee pulp and 16 with the ensilaged by-product, distributed into four different protein levels (10, 15, 20 and 25%), and three levels of pulp (15, 30 and 45%) for each protein level. The rations thus prepared were fed to Wistar albino rats for a six-week period. The parameters used to measure the effect of the two types of pulp were mortality rate, food consumption, weight gain, food conversion and apparent digestibility of the rations. Ensilaged pulp had a higher nutritive value, lower toxicity and better digestibility than fresh pulp. The increase in the protein level of the ration resulted in partial protection against the negative effects of coffee pulp on the performance of animals, since this improved as the protein level of the ration increased.     

OCVD carrier lifetime in PNN diode structures with axial carrier lifetime gradient

The OCVD (open circuit voltage decay) method is the generally used method for the determining of carrier lifetime in the structures of semiconductor devices. This paper is focused on power diode (P⁺NN⁺) structures, in which is realised a carrier lifetime gradient to influence the current and voltage waveforms during the reverse recovery process. A theoretical analysis of the general features of voltage decay courses in OCVD measurements on diode structures with an axial carrier lifetime gradient in the diode base is presented. Some results obtained from both simulations and experimental measurements are discussed in the paper.     

Shaping the Internet: the dynamics

Earlier, the author discussed five components of an Internet architecture (middleware; user interface; delivery system; application; and data). He completes that schema by describing the four dynamics: user processes, software development; data management; and system management. The distinction between components and dynamics can be illuminated by an analogy: if the components are features in a landscape, the dynamics are forces like wind and water currents that shape them. The components and dynamics are inseparable, and their interactions comprise the environment in which the Internet “lives”. Instead of trying to suggest the next level of detail for the four dynamics, the author gives examples of how the dynamics influence the evolution of the components and vice versa. The dynamics are susceptible to our influence (unlike the laws of gravity), so all of us have a hand in shaping the Internet by our choices as technology developers and users. The author looks at how the Internet components and dynamics affect one another     

A case of high-flow priapism successfully treated with percutaneous selective embolization of the internal pudendal artery

Relatively rare high-flow priapism is most frequently caused by contusion or direct injury of the cavernous artery with a subsequent uncontrolled inflow of arterial blood into the cavernous bodies. Knowledge of this pathophysiology and the development of intervention radiology made a more selective therapeutic approach possible. The authors present a report on a case of arterial or high-flow priapism which was successfully resolved by a minimally invasive approach--percutaneous superselective transcatheter embolization of the internal pudendal artery.     

Detection of soluble interleukin-2 receptor in the serum of patients with non-Hodgkin''s lymphoma

Falls are the most common type of injury among the elderly, and the source of both functional and psychological morbidity. The aim of this study was to validate the Elderly Fall Screening Test (EFST). In a community primary-care clinic, the members 60 years or older who were functionally independent were screened. Of the 568 elderly persons who met these criteria, 361 were interviewed once and 283 persons were re-interviewed a year later. The EFST, a five-item test, was used to divide participants into low- and high-risk groups. Concurrent criterion validity was assessed by physical examinations conducted by physicians who were blind as to the risk designation. Using data from the follow-up interview, predictive validity was assessed on both fall-related and general health measures. Based on the results of the EFST, 28% of the respondents were designated as being at high risk for falls (i.e. having a score of two or more risk items). The results of physicians' examinations corroborated the screening test results in 75% of the cases, with 83% sensitivity and 69% specificity. In the follow-up interview, the high-risk group, as compared to the low-risk group, was more likely to have high scores on EFST, a fall in the past month or year, frequent near falls, and an injurious fall. Those with high EFST scores were more likely to report four or more sick days in the past six months, a hospitalization in the past year, poor self-rated health, a decline in health in the past 6 months, and symptoms of depression. The EFST has both criterion and predictive validity. It can be useful in community-based prevention programmes with functionally independent elderly people.     

A note on trap recombination in high voltage device structures

The carrier lifetime is a very important parameter influencing all important characteristics of bipolar devices both discrete and integrated structures and carrier lifetime tailoring is an important part of power semiconductor device technology. In presented paper, recombination through traps (centres with a deep energy level between edge of bandgap and Fermi level) is discussed in more details. It has been shown that some traps can considerably influence recombination rate in silicon and that at some traps a considerable temperature dependence of the centre cross-sections may be found. This is demonstrated in the case of iridium traps with a deep energy level 0.28 eV below the conduction band which capture cross-section temperature dependence has been found σ_p+σ_n∝T^−6.5. Further, the problem on low injection carrier lifetime in low-doped layers of high voltage semiconductor devices is also discussed.