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T. Braun K.-F. Becker M. Koch V. Bader R. Aschenbrenner H. Reichl 《Microelectronics Reliability》2005,45(9-11):1672
Automotive under-the-hood electronics often have to withstand temperatures up to 175 °C in combination with harsh environment conditions. This paper gives an overview about the reliability potential of epoxy based encapsulants for automotive applications. Therefore the resistance of epoxy molding compound against typical automotive fluids at temperature of use is analyzed. Six epoxy molding compounds available on the market, showing high temperature automotive potential have been carefully selected to undergo a media resistance testing. For this purpose a dedicated mold tool has been designed and manufactured to prepare these encapsulants for material testing. Thermo-mechanical, mechanical and thermal properties had been determined in initial state directly after molding and after storage in aggressive fluids typical for automotive applications as e.g. gas oil, automatic transmission fluid (ATF), brake fluid or accumulator acid at the respective temperature of use. 相似文献
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W. Shang B. Robrahn F. Golding M. H. J. Koch 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2004,530(3):513-520
A data acquisition system for time resolved X-ray scattering experiments using linear, quadrant or area gas proportional detectors with delay line readout based on commercially available hardware (National Instruments) is described. The system can easily be configured for recording data from point detectors (e.g. photomultipliers and photodiodes) and/or ancillary data only. Applications involving measurements with two different types of time to digital converters illustrate the features and performances of the system. 相似文献
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Terahertz characterisation of building materials 总被引:1,自引:0,他引:1
Piesiewicz R. Kleine-Ostmann T. Krumbholz N. Mittleman D. Koch M. Kurner T. 《Electronics letters》2005,41(18):1002-1004
To obtain realistic models for propagation channels in future pico-cellular indoor terahertz communication systems it is necessary to know the reflective properties of building materials found in a typical office environment. The angular dependent reflection coefficients of different building materials were determined using terahertz time-domain spectroscopy in transmission geometry and Fresnel's equations. This approach is more efficient than a set of measurements in reflection geometry for different angles. Verification of the method with a set of such reflection measurements shows an excellent agreement. 相似文献
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The ability of oral lactobacilli to coaggregate with streptococci and actinomycetes was investigated. Of the 7 species of lactobacilli studied, only two were capable of coaggregation and the coaggregation was restricted to streptococci. Lactobacillus salivarius strains (2/4) coaggregated with Streptococcus salivarius, Streptococcus gordonii, Streptococcus crista and tufted Streptococcus sanguis II strains. Lactobacillus fermentum (2/3) coaggregated with S. gordonii and S. sanguis. The coaggregation between L. salivarius and S. salivarius, S. gordonii or tufted S. sanguis II strains was mediated by a protein on the surface of the lactobacilli and was not inhibited by lactose. The coaggregation between L. fermentum and the streptococci was mediated by protein on the surface of the streptococci and was inhibited by lactose. 相似文献
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KW Sax SM Strakowski PE Keck SL McElroy SA West SP Stanton 《Canadian Metallurgical Quarterly》1998,44(8):784-786
BACKGROUND: This study examined patients with a first-episode of affective psychosis during acute and compensated states in order to determine whether changes in attentional functioning over time were accompanied by changes in the severity of psychotic or affective symptoms. METHODS: Attentional performance was measured in patients (n = 27) using the degraded-stimulus continuous Performance Test (CPT) and symptoms were assessed at the time of index hospitalization, and 2 months after discharge. A comparison group of normal volunteers (n = 31) also performed the CPT two months apart. RESULTS: Patients performed significantly worse than controls at the initial testing but not at follow-up. The improvement in attentional performance significantly correlated with decreased severity of manic symptoms. CONCLUSIONS: Results suggest attentional dysfunction is a state-dependent characteristic of mania, and may provide an additional measure of clinical improvement following treatment. 相似文献
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Sodium tolerance in yeast is disrupted by mutations in calcineurin, a Ca2+/calmodulin-dependent protein phosphatase, which is required for modulation of Na+ uptake and efflux mechanisms. Five Na+-tolerant mutants were isolated by selecting for suppressors of calcineurin mutations, and mapped to the PMA1 gene, encoding the plasma membrane H+-ATPase. One mutant, pma1-alpha4, which has the single amino acid change Glu367 --> Lys at a highly conserved site within the catalytic domain of the ATPase, was analyzed in detail to determine the mechanism of Na+ tolerance. After exposure to Na+ in the culture medium, 22Na influx in the pma1 mutant was reduced 2-fold relative to control, consistent with a similar decrease in ATPase activity. Efflux of 22Na from intact cells was relatively unchanged in the pma1 mutant. However, selective permeabilization of the plasma membrane revealed that mutant cells retained up to 80% of intracellular Na+ within a slowly exchanging pool. We show that NHX1, a novel gene homologous to the mammalian NHE family of Na+/H+ exchangers, is required for Na+ sequestration in yeast and contributes to the Na+-tolerant phenotype of pma1-alpha4. 相似文献
10.
BACKGROUND: Diabetic patients with end-stage renal failure (ESRD) have a high cardiovascular morbidity and mortality. The underlying mechanisms are not completely elucidated. The aim of our study was to define predictors of death in diabetic patients with end-stage renal disease. PATIENTS AND METHODS: We performed a prospective study in 35 dialysis centres in Germany between 1985 and 1994. To evaluate predictors and risk factors in this population we examined 412 diabetic patients at the time of admission to dialysis treatment (peritoneal dialysis (PD) or haemodialysis (HD)). Classification of the type of diabetes was done according the criteria of the National Diabetes Data Group [1,2]. Items assessed at the time of admission were coronary artery disease (CAD), peripheral occlusive disease (POD), and stroke. CAD was defined as a history of myocardial infarction with the corresponding changes in the ECG or luminal narrowing by more than 50% in at least one coronary artery upon coronarangiography; POD was defined as claudication and/or brachial-tibial ratio (BTR) less than 0.9 or a history of amputation. Assessment of the nutritional state comprised body mass index, skinfold thickness of the upper arm and lateral thorax area, and urea concentration. Cholesterol, HDL, LDL, apolipoprotein A (ApoA-I) and B (ApoB), triglycerides, lipoprotein(a) (Lp(a)), and fibrinogen were measured. As an index of disturbed cardiac innervation beat-to-beat variation was measured. Outcome measurements were causes of death (i.e. cardiac and non-cardiac) and time of survival. RESULTS: One hundred and eighty of 412 (44%) patients died during the observation period. Patients who died were older (61 +/- 12 versus 53 +/- 15 years P < 0.0001), had lower skin fold thickness (13.1 +/- 6.0 versus 15.1 +/- 7.3 mm P < 0.04), lower ApoA-I (100 +/- 35 versus 111 +/- 32 mg/dl P < 0.005) and higher fibrinogen (515 +/- 146 versus 451 +/- 155 mg/dl P < 0.02). Type II diabetic patients had a lower mean survival time than type I (34 versus 66 months P < 0.0006). The mode of renal replacement therapy (PD or HD) had no adverse effect on survival time. Survivors less frequently had a history of CAD, POD and stroke than non-survivors. In multivariate analysis ApoA-I, fibrinogen, age and stroke were independent predictors of cardiac and non-cardiac death in diabetic patients with end-stage renal failure. Lipid values and nutritional state did not independently predict the overall and cardiovascular mortality. CONCLUSION: This study in dialysed diabetic patients identifies several predictors of death, some of which are susceptible to intervention. 相似文献