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41.
Intergranular stress corrosion cracking(ISCC) of α-brass in neutral Mattsson's solutionwas found to be controlled by an unusual"W"-shaped galvanic cell whose cathode is thegrain boundary oxide film (G.B.0. film) andsurface film and the anode is fresh metal atthe cracked tip on both sides of the G.B.0.film. Redox reactions involved in the cellhave been proposed here. According to thismdel, initidtion of ISCC is caused by therupturing of surface film along grain boundaries,thus forming a galvanic cell. Propagation ofISCC resulted from alternate advances of G.B.0.film and dissolution on both sides of G.B.0.film caused by the effect of electrochemicalreaction. This work developed an effective approachto investigate the embrittlement process atthe tip of the crack, by increasing the lengthof the embrittlement region through constantstrain test and distinguishing the morphologyand the nature of the corrosion products byoptical microscopy and scanning electronmicroscopy (SEH). 相似文献
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This study attempted to identify the major sources of work-related stress among telephone operators, with special emphasis on computer monitoring and telephone surveillance. A cross-sectional random sample of over 700 telephone operators participated in a questionnaire survey (response rate = 88%). The survey included items designed to measure perceived stress, management practices, specific job stressors and monitoring preferences. Call-time pressure items were most strongly linked to job stress by operators, with 70% reporting that difficulty in serving a customer well and still keeping call-time down contributed to their feelings of stress to a large or very large extent. About 55% of operators reported that telephone monitoring contributed to their feelings of job stress. If given the opportunity, 44% of operators stated they would prefer not to be monitored by telephone at all, while 23% stated they would prefer some monitoring; 33% had no preference. The setting of inappropriate individual-call-time objectives, which may be consistently unachievable for some operators and which create conflict between management demands for quantity and quality and also between workers values concerning quality and productivity demands, appears to be the most stress-inducing aspect of the job. In terms of telephone surveillance, the issues of timeliness and specificity of feedback appear to be less important than call-time pressure. 相似文献
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A simple phase-characterization method for spatial light modulators is proposed. The low-cost method permits high-precision measurement and provides data for the setting of the spatial-light-modulator operating point in the phase-modulation mode. The dynamic phase response is used to perform efficient kinoform recording. In order to record the kinoform, we modify the global iterative coding to compute phase holograms. Finally, modified phase-phase correlation is introduced. The phase-phase correlator permits sharper correlation peaks, better energy transmission, and higher discrimination than an amplitude-phase correlation. Optical experimental results are presented. 相似文献
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HH Holm 《Canadian Metallurgical Quarterly》1998,24(6):779-791
"Interventional ultrasound," defined as any diagnostic and therapeutic procedure performed under ultrasound guidance was first introduced in Europe, where its early development took place in Vienna, in Copenhagen, in Italy and in Switzerland. However, many of the applications of interventional ultrasound have been based on important pioneer work using other less-suitable needle guiding methods from the pre-ultrasound era. The European contributions to "interventional ultrasound" have especially been in the development of new puncture equipment, in the dissemination of various biopsy techniques, and draining procedures and, more recently, in the development of many different tissue-ablation techniques. The above contributions, which are outlined in this historical review, have, together with significant contributions from the rest of the world-not least from the United States and Japan-created a most efficient diagnostic as well as therapeutic tool for the benefit of our patients. 相似文献
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A Doan G Thinakaran DR Borchelt HH Slunt T Ratovitsky M Podlisny DJ Selkoe M Seeger SE Gandy DL Price SS Sisodia 《Canadian Metallurgical Quarterly》1996,17(5):1023-1030
Mutations in a gene encoding a multitransmembrane protein, termed presenilin 1 (PS1), are causative in the majority of early-onset cases of AD. To determine the topology of PS1, we utilized two strategies: first, we tested whether putative transmembranes are sufficient to export a protease-sensitive substrate across a lipid bilayer; and second, we examined the binding of antibodies to specific PS1 epitopes in cultured cells selectively permeabilized with the pore-forming toxin, streptolysin-O. We document that the "loop," N-terminal, and C-terminal domains of PS1 are oriented toward the cytoplasm. 相似文献
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In this paper we use data derived from interviews with 215 female homicide offenders incarcerated or on parole in New York to examine their drug use prior to and at the time of the homicide, their victims' drug use, and their perceptions as to the drug-relatedness of the homicides. We found that about 7 out of 10 respondents had been regular users of some drug at some point in their lives prior to their incarceration, while over half had been addicted to a substance. Over one-third of the respondents who were present at the scene were "high" on a drug at the time, while about half of the victims of these homicides used drugs before the homicide. Almost two-thirds of the homicides committed by respondents who were present at the scene were perceived to be drug-related. Alcohol, crack, and powdered cocaine were the drugs most likely to be related to these homicides. The implications of our findings are discussed. 相似文献
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