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141.
Jorge L. B. Maciel Emerson A. Floriano Luis V. A. Scalvi Leandro P. Ravaro 《Journal of Materials Science》2011,46(20):6627-6632
Aiming for the investigation of insulating properties of aluminum oxide (Al2O3) layers, as well as the combination of this oxide with tin dioxide (SnO2) for application in transparent field effect transistors, Al thin films are deposited by resistive evaporation on top of
SnO2 thin films deposited by sol–gel dip-coating process. The oxidation of Al films to Al2O3 are carried out by thermal annealing at 500 °C in room conditions or oxygen atmosphere. X-ray diffraction data indicate that
tetragonal Al2O3 is indeed obtained. A simple device and electric circuit is proposed to measure the insulating properties of aluminum oxide
and the transport properties of SnO2 as well. Results indicate a fair insulation when four layers or Al2O3 are grown on the tin dioxide film, concomitant with thermal annealing between each layer. The current magnitude through the
insulating layer is only 0.2% of the current through the semiconductor film, even though the conductivity of the SnO2 alone is not very high (the average resistivity is 2 Ω cm), because no doping is used. The presented results are a good indication
that this combination may be useful for transparent devices. 相似文献
142.
R Herruzo Cabrera J Díez Sebastián A Baylin Larios D Nadal P Pe?a J García Caballero 《Canadian Metallurgical Quarterly》1998,111(18):687-691
BACKGROUND: The blood stream infections (BSI) are the principal nosocomial infection in the child hospitals. In this study we estimate the incidence of BSI associated with central venous catheterization, and estimate different risk and protective factors, through a multivariate study. MATERIAL AND METHODS: The study have followed in a prospective way during 6 months all the children with central venous catheterization (489 catheters), from the moment of insertion until withdrawal, collecting various data previous to the development of the infection: place of insert, type of catheter, duration, clinic information, microbiology, and the treatments administered through the catheter. In was accomplished an multivariate analysis with logistic regression, for two principal effect variables, the catheter colonization and the catheter related BSI. RESULTS: The incidence of catheter related BSI was 5.5% and for local infection 11.2%. The density of incidence was 3.15 and 6.42 for each 1,000 catheters-day, respectively. The logistic regression model included: colonization of the skin in the insertion point > 15 colonies, days with antibiotics through catheter, use of lipidic parenteral solutions and fever, previous to the infection. The area under the ROC curve was 0.72. CONCLUSIONS: In children with septicemias associated with central catheterization the predictors or sentry criterion for the decision on when to withdraw a catheter are colonization (> 15 colonies) of the insert point, together with the use of lipidic parenteral solutions or extended antibiotic treatment. 相似文献
143.
Recently there has been much interest in the direct detection of the dark matter candidates known as WIMPs. We are developing very sensitive detectors based on phonon detection with transition edge sensors on silicon substrates. These detectors will be deploy ed as part of the Cryogenic Dark Matter Search in collaboration with the Center for Particle Astrophysics. As we extend this technology to practical WIMP searches we will need much higher mass scale detectors. We have demonstrated detectors on 500 µm substrates. To reach the kilogram mass scales we need to pattern wafers that are an order of magnitude thicker with a detector that is at least two orders of magnitude more sensitive. Progress is reported on both these areas and a detector design is discussed. 相似文献
144.
Bazil Taha Ahmed Miguel Calvo Ramón Leandro De Haro Ariet 《Wireless Personal Communications》2004,31(1):19-31
The uplink capacity and the interference statistics (mean and variance) of the sectors of the cigar-shaped W-CDMA microcell are studied. A model with eighteen sectors is used to analyze the uplink. The microcells are assumed to exist in a long tunnel with at least nine base stations. The hybrid model of propagation is used in the calculations. The capacity and the interference statistics of the sectors are studied in terms of the most important parameters: sector radius, specific attenuation factor, antenna sidelobe levels, bend losses and the power control standard deviation error. 相似文献
145.
M.C. Cabrera A. Saadoun A. Grompone T. Pagano M. Salhi R. Olivero M. del Puerto 《Food chemistry》2006,98(4):767-773
The present study was conducted to evaluate the ability of horse fat produced in Uruguay, compared with other lipid sources supplemented in the diet of laying hens, to modify the lipid composition and the n − 6/n − 3 fatty acid ratio of the produced eggs. For this purpose, 60 laying hens (Gallus domesticus) were fed for 30 days with five experimental diets (12 hens/diet) containing 3% sunflower oil (SO), rice oil (RO), beef tallow (BT), pressed-fat (PF), obtained by pressing fat from bovine viscera, and horse fat (HF) obtained from horse bone medulla. Throughout the trial, feeding rate, shell index, weight and total lipid contents of eggs, were not affected by the different diets. Feeding on the SO and RO diets significantly increased the amount of linoleic acid of the egg, although it was lower in the RO than in the SO eggs. Diet BT did not affect the saturated fatty acid content of the yolks. The diets with animal fats containing 18:3n − 3 (diets PF and HF), resulted in a significant increase in the n − 3 fatty acid contents of the eggs, through an increase of linolenic (18:3n − 3) and docosahexaenoic acid (DHA, 22:6n − 3) contents. Eggs from hens fed the HF diet showed increased linolenic acid (46 mg/yolk) and DHA (71 mg/yolk, 1.7% of total fatty acids) contents. These levels were obtained after two weeks of feeding. Moreover, the fatty acid profiles of eggs from treatment HF were not significantly affected by thermal treatment of the yolks. In conclusion, the fat from horse bone medulla, as produced in Uruguay, can be considered as a suitable lipid source for diets of laying hens, to modify the nutritional composition of the eggs in n − 3 PUFA content, especially DHA, and consequently, the n − 6/n − 3 fatty acid ratio. 相似文献
146.
L Ruiz J Romeu B Clotet M Balagué C Cabrera G Sirera A Ibá?ez J Martínez-Picado A Raventós C Tural A Segura M Foz 《Canadian Metallurgical Quarterly》1996,10(11):F39-F44
OBJECTIVE: To analyse plasma HIV-1 RNA levels as a marker of clinical stability and survival in a cohort of HIV-infected patients whose time of seroconversion is unknown. DESIGN: Retrospective cohort study. SETTING: Retrovirology laboratory and AIDS Unit in a teaching hospital. PATIENTS: A total of 916 samples from 302 patients, most on antiretroviral therapy, were analysed. Mean initial CD4 cell counts and HIV-1 RNA were 299 x 10(6)/l (range: 0-1600) and 134,261 copies/ml (range: < 200-4,300,000), respectively. Sixty-six cases had been diagnosed previously with AIDS. METHODS: Analysis of progression to AIDS and survival, according to initial and longitudinal viral load (VL) and CD4 cell count measurements was performed by Kaplan-Meier test. Relative risks were calculated by Cox's proportional hazards model. RESULTS: During a mean follow-up of 444 +/- 309 days, 29 patients developed AIDS and 21 died. Relative risk (RR) of progression related to the group with VL < 35,000 was: 10.4 when CD4 > or = 250 x 10(6)/l and VL > or = 35,000 (P = 0.001); and 45.3 when CD4 < 250 x 10(6)/l and VL > or = 35,000 (P < 0.0001). Cumulative probability of progression was: 0%, 0% and 12.3%, at the first, second and third year respectively, for patients with all their sequential VL determinations < 60,000; and 13.3%, 34.7% and 79.3% for patients who did not maintain VL values always < 60,000 (RR = 23; P < 0.0001). The minimum value of VL that reached statistical significance for the survival analysis was 100,000 copies/ml (P < 0.0001). CONCLUSIONS: VL > or = or < 35,000 is a better discriminant for progression than a CD4 cell count > or = or < 250 x 10(6)/l. Sequential VL determinations < 60,000 are associated with a better prognosis. 相似文献
147.
E. Flores J. M. Cabrera J. M. Prado 《Metallurgical and Materials Transactions A》2004,35(13):1097-1103
The present work shows that clustering of particles promotes deviation in the classical mathematical expressions describing
the grain growth control by second-phase particles. On the basis of experimental results and theoretical laws, a semiempirical
expression to predict the limiting grain size is presented. The latter expression takes account of agglomeration phenomena
and can be extended to large volume fractions of particles, conditions under which classical theories clearly fail. The equation
remains valid as far as the nucleation of precipitates takes place at random. From a practical point of view, it is shown
that volume fractions larger than 0.12 cannot significatively control the grain size because of the increased probability
for clustering. 相似文献
148.
Performance assessment through bootstrap 总被引:4,自引:0,他引:4
Cho K. Meer P. Cabrera J. 《IEEE transactions on pattern analysis and machine intelligence》1997,19(11):1185-1198
A new performance evaluation paradigm for computer vision systems is proposed. In real situation, the complexity of the input data and/or of the computational procedure can make traditional error propagation methods infeasible. The new approach exploits a resampling technique recently introduced in statistics, the bootstrap. Distributions for the output variables are obtained by perturbing the nuisance properties of the input, i.e., properties with no relevance for the output under ideal conditions. From these bootstrap distributions, the confidence in the adequacy of the assumptions embedded into the computational procedure for the given input is derived. As an example, the new paradigm is applied to the task of edge detection. The performance of several edge detection methods is compared both for synthetic data and real images. The confidence in the output can be used to obtain an edgemap independent of the gradient magnitude 相似文献
149.
JR Beramendi Calero E Pastor Menchaca JM Galdeano Miranda P Beltrán de Heredia J Pérez García J Alcíbar Villa D Rodrigo Carbonero A Cabrera Duro 《Canadian Metallurgical Quarterly》1998,49(3):284-288
Fe(II)-tetrakis-N,N,N',N'(2-pyridylmethyl) ethylenediamine (Fe-TPEN) catalyzes the dismutation of superoxide, and blocks the toxic effect of paraquat on Escherichia coli growth and survival. We examined antioxidative effects of Fe-TPEN on lipid peroxidation and t-butyl hydroperoxide induced cell damage. Fe-TPEN inhibited the FeSO4/H2O2 induced lipid peroxidation in the rat liver homogenates with an IC50 value of 30.2 microM, and protected Ac2F cell damage by t-butyl hydroperoxide in a dose-dependent manner (EC50 value is 2.6 microM). Also, hepatoprotective effect of Fe-TPEN (5 mg/kg, i.p.) was investigated using CCl4 induced liver injury in rats. This complex inhibited the elevation of serum alanine aminotransferase (AST) and aspartate aminotransferase (ALT) levels in CCl4 induced liver injuries, and improved submassive necrosis and fatty degeneration of the hepatocytes. Fe-TPEN also prevented the loss of total and nonprotein SH contents, glutathione peroxidase and glutathione-S-transferase activity in cytosol of rat liver. Although the exact mechanism of action is not clear, antioxidative properties as well as attenuation of hepatocellular defense systems by Fe-TPEN seem to be important on its potent hepatoprotective effect in CCl4-intoxicated rat. 相似文献
150.
Leandro A. Mozzoni Pengyin Chen Ruben O. Morawicki Navam S. Hettiarachchy Kristofor R. Brye & Andy Mauromoustakos 《International Journal of Food Science & Technology》2009,44(11):2089-2099
Vegetable soybeans are marketed fresh or frozen, either shelled or in pods. The objective of this research was to characterise the change in quality attributes of vegetable soybean with boiling time (0–20 min), and presence/absence of pods, using an electrical-resistance stove or a steam-jacketed kettle. Trypsin inhibitor activity (TIA), texture, colour, soluble sugars, nitrogen, calcium and iron content were analysed. Blanching using a steam-jacketed kettle for approximately 2 min rendered 80% inactivation of TIA, and resulted in high colour, texture and sucrose. There were no differences between blanching in pods or shelled for TIA, colour and texture; however, blanching in pods prevented losses of sucrose. Blanching did not affect iron, mono- and oligosaccharide levels, but increased nitrogen and calcium content. Additionally, we observed that all traits decreased linearly with cooking time when using an electrical-resistance stove, except for calcium and nitrogen that increased, and oligosaccharides that remained constant. 相似文献