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11.
Roberto Leoni Bruno Buonomo Gabriella Castellano Francesco Mattioli Guido Torrioli Luciana Di Gaspare Florestano Evangelisti 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2004,520(1-3):44-47
We discuss the performance, of a normal metal hot electron bolometer (NHEB) that we have measured at 0.3 K. We found that the noise equivalent power was limited by the amplifier noise. To improve the NHEB power response and to make it more robust and reliable we propose to substitute the normal metal with heavily doped silicon. The heavily doped silicon behaves like a metal with lower carrier concentration and has a smaller electron–phonon thermal coupling. We have fabricated superconductor-doped silicon-superconductor contacts (S-Sm-S) and we have used them as thermometers and coolers. 相似文献
12.
Miriam A Martinello Mauro Villegas Maria del C Pramparo 《Journal of the science of food and agriculture》2007,87(8):1559-1563
A process of physical refining wheat germ oil using the technique of molecular distillation (MD) is presented in this work. Wheat germ oil was obtained from the germ by solvent extraction using hexane and also by cold pressing. The oil extracted with hexane was degummed and bleached before deacidification in order to modify the parameters of phosphorus and color. The goal in carrying out the stage of physical refining by MD was to preserve the maximum amount of original antioxidative potential obtained from extraction of the crude oil. The effect of evaporation temperature of one‐stage MD on the efficiency of free fatty acid elimination was studied. The antioxidant portion was followed by means of analytic determination of tocopherols by high‐performance liquid chromatography. Tocopherol retention up to 98% was achieved in the oil extracted by pressing, and yields of up to 96% were achieved in the oil extracted with hexane. Copyright © 2007 Society of Chemical Industry 相似文献
13.
In this work a new class of numerical methods for the BGK model of kinetic equations is presented. In principle, schemes of
any order of accuracy in both space and time can be constructed with this technique. The methods proposed are based on an
explicit–implicit time discretization. In particular the convective terms are treated explicitly, while the source terms are
implicit. In this fashion even problems with infinite stiffness can be integrated with relatively large time steps. The conservation
properties of the schemes are investigated. Numerical results are shown for schemes of order 1, 2 and 5 in space, and up to
third-order accurate in time. 相似文献
14.
LA Pérula de Torres J Martínez de la Iglesia J Espejo Espejo MV Rubio Cuadrado I Enciso Berge FJ Fonseca del Pozo JM Aranda Lara 《Canadian Metallurgical Quarterly》1997,20(8):425-434
OBJECTIVE: To describe the health status of a population over 60 years and to study their relationship with several socio-demographic variables. DESIGN: A cross-sectional study, population based. SETTINGS: A community. PARTICIPANTS: A randomized sample of 1,103 non institutionalized people over 60 years living in the city of Cordoba (Spain). MEASUREMENTS AND MAIN RESULTS: By mean of a personal interview at home we used the OARS-MFAQ-VE questionnaire. Low self-rated health was associated with the age, to be female sex, a low cultural background, and a low income. Only 5.2% of the study people do not suffered any illness and 56% state that their health problems are major problems for doing their current activities. 4.9% declared to have some degree of physical incapacity. 3.7% of elderly population has an important cognitive deficit. CONCLUSIONS: The majority of elderly people has good health. Age is related with a poor health. Women have more health problems than men. 相似文献
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I Zapater Serrano C Lample Lacasa MA Blanch Labrador MP Lozano Arranz C del Agua Arias-Camisón 《Canadian Metallurgical Quarterly》1997,50(9):947-951
OBJECTIVE: To evaluate the ability of computerized tomography (CT) to stage transitional cell carcinoma of the upper urinary tract. METHODS: 29 transitional cell carcinoma of the upper urinary tract submitted to nephroureterectomy were retrospectively evaluated. All 29 tumors had preoperative CT scans performed to stage the lesion. The pathological staging was compared to that of CT. RESULTS: 10 of the 29 tumors had CT evidence of tumor extension and 19 had localized noninvasive tumor on CT. Of the 10 patients with CT findings of tumor extension, 2 (20%) had superficial tumors and 8 (80%) had tumors that invaded into the adventitial fat, renal parenchyma or perirenal fat (pT3, pT4). Of the 19 patients with localized noninvasive tumor on CT, 13 (68%) had superficial tumors and 6 (32%) had pT3 or pT4 tumors. CT sensitivity for tumor invasion was 57% with a specificity of 87.5%. CONCLUSIONS: Our analysis shows that CT is of limited value in staging these tumors. When CT demonstrates direct tumor extension through the renal pelvic or ureteral wall, it is a sensitive indicator of high-stage tumor. However, the results obtained in low stage tumors must be viewed with caution. 相似文献
17.
The effect of crude oil n-paraffin molecular weight distribution on wax crystallization risk was studied. Sixteen highly paraffinic crude oils from Eastern Venezuela were characterized, in terms of hydrocarbon family distribution, by High Temperature Simulate Distillation (HTSD), Gel Permeation Chromatography (GPC), and wax content. n-Paraffin chain length was correlated with crude oil cloud point and pour point. It was demonstrated that high molecular weight linear paraffins are responsible for crude oil wax precipitation. A quantitative correlation between molecular weight distribution and crude oil flowing properties was also obtained. It was found that the wider the molecular weight distribution, the lower is the wax crystallization risk. Blends of different paraffinic crude oils were prepared and their flowing properties were evaluated in comparison with the original crudes. Cloud points below the mean value were obtained. In some cases, a synergistic effect was observed (cloud points below the minimum of the two crude oils). Blends of some of these crudes with condensates afforded improvements on crude oil flow and a reduction of wax crystallization tendency (cloud point). This phenomenon can be attributed to a combination of two factors: I. increases in C24-n-paraffins, and II. a wider molecular weight distribution. 相似文献
18.
Arnaud C. Feron P. Boustimi M. Grosso P. Bosc D. Guignard P. 《Electronics letters》2003,39(17):1249-1250
Numerical results on polymer surrounded by an air micro-ring coupled to waveguides are presented. The FDTD method predicts a filter width of 1.4 nm and an extraction efficiency of almost 80% for a gap of 0.15 /spl mu/m. 相似文献
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