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101.
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R Herruzo-Cabrera L Malo-González ME Calle Purón MJ Vizcaíno-Alcaide J Del Rey-Calero 《Canadian Metallurgical Quarterly》1993,9(4):442-446
A cross-sectional study was performed to obtain risk factors for hepatitis B disease, HBsAg carriers and immunised personnel, among 2470 workers in a general hospital in Madrid, Spain. The data obtained were analyzed with multiple logistic regression to obtain beta coefficients for variables. The results of the analysis show that being a nurse or being regularly exposed to blood are the most important risk factors for hepatitis B acquisition. The length of time working at the same job activity was also a risk factor. The resulting beta coefficients allow the construction for a hepatitis non-immunised, HBsAg carrier and immunised HBV status, which can select subjects for a hepatitis B vaccination program. 相似文献
105.
María P. Albano Liliana B. Garrido 《Journal of Materials Synthesis and Processing》2002,10(4):211-218
Si3N4powders coated with 6 wt% Y2O3and 4 wt% Al2O3were prepared by coprecipitation. The resulting powders were dispersed in water at different pH values and with addition of various amounts of ammonium polyacrylate (NH4PA) to produce 32 vol% slips. The influence of the amount of NH4PA solution added and pH on the rheological properties of 32 vol% coated Si3N4slips were studied. In addition, the sintered density of cast samples was determined and related to the degree of slip dispersion. The adsorption of the NH4PA on the coated particle surface was rather high and the surface became saturated near 0.86 mg/m2at pH 9.2. High NH4PA concentrations (1.7–3 wt%) were necessary to obtain well dispersed 32 vol% coated Si3N4slips at pH 9.2. The best stabilization was obtained with the addition of 2.3 wt% NH4PA; in this condition, the viscosity reached a minimum value of 35 mPa.s at 100 s–1. The slip viscosity increased with increasing pH from 9.2 to 10.2. Slips with low viscosities gave a more dense packing of cast samples and consequently higher sintered density values. 相似文献
106.
Certain new sulfide-smelting processes and coal-gasification processes generate high-strength sulfur dioxide streams, for
which a new process for converting sulfur dioxide to elemental sulfur needs to be developed because no process exists that
is generally and economically applicable to the treatment of such streams. A thermodynamic and experimental investigation
to develop a new process for converting sulfur dioxide to elemental sulfur by a cyclic process involving calcium sulfide and
calcium sulfate without generating secondary pollutants was carried out. In this process, the starting raw material, calcium
sulfate, is reduced by a suitable reducing agent, such as hydrogen, to produce calcium sulfide, which is used to reduce sulfur
dioxide to elemental sulfur vapor and calcium sulfate. The latter is, in turn, reduced to regenerate calcium sulfide. In this
Part I, detailed experimental results are presented on the kinetics of the reaction between sulfur dioxide and calcium-sulfide
pellets, which produces elemental sulfur and calcium sulfate. The experiments were carried out at temperatures between 1023
and 1088 K and sulfur-dioxide partial pressures between 9 and 60 kPa by the use of a thermogravimetric analysis (TGA) technique.
The rate of this reaction was demonstrated by the conversion of 40 pct calcium-sulfide pellets obtained from the hydrogen
reduction of fresh calcium sulfate in 10 minutes at 1073 K under a sulfur-dioxide partial pressure of 43 kPa. The reactivity
decreased somewhat during the first three cycles but remained largely unchanged thereafter up to the tenth cycle. This characteristic
of the pellets is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants.
A pore-blocking model was found to fit the reaction rate. The reaction is first order with respect to sulfur-dioxide partial
pressure and has an activation energy of 101 to 134 kJ/mol (24 to 32 kcal/mol) for calcium-sulfide pellets reacted and regenerated
several different times. Sulfur dioxide-containing streams from certain sources, such as the regenerator off-gas from an integrated-gasification,
combined-cycle, desulfurization unit and new sulfide-smelting plants, contain much higher partial pressures of SO2. In these cases, the rate of the first reaction is expected to be proportionally higher than in the test conditions reported
in this article. The reduction kinetics of calcium-sulfate pellets with hydrogen gas is reported in the accompanying Part
II. 相似文献
107.
Microbiological denitrification of red beet juice 总被引:1,自引:0,他引:1
Dorota Walkowiak-Tomczak 《European Food Research and Technology》2002,215(5):401-406
The purpose of study was the determination of optimal conditions for red beet juice denitrification by Paracoccus denitrificans bacteria as well as the evaluation of the usefulness of microbiologically treated juice for the production of a natural colouring preparation for foods. Total reduction of nitrates was found during bacterial culturing at 25 and 30 °C, at an initial pH of 7.0-8.0 and juice osmotic pressure of 900-1100 mOsm/kg. Microbiological denitrification procedure affected colour, taste and aroma of the juice. However, the use of juice as food colouring and component was made feasible by acidification and partial evaporation of water together with volatile substances. 相似文献
108.
Generation of Technology-Independent Retargetable Analog Blocks 总被引:1,自引:0,他引:1
R. Castro-López F. V. Fernández F. Medeiro A. Rodríguez-Vázquez 《Analog Integrated Circuits and Signal Processing》2002,33(2):157-170
This paper introduces a complete methodology for retargeting of analog cells to different sets of specifications. This methodology is technology-independent, thus allowing the migration, from one technology to another, of the circuit under retargeting. Careful integration of the device sizing and layout generation tasks via the incorporation of layout constraints during the sizing process allows to generate fully functional designs in a few minutes. The methodology is illustrated via the retargeting of a fully-differential Miller-compensated two-stage operational amplifier for a new set of specifications and two different technological processes.An erratum to this article can be found at 相似文献
109.
110.
George Ter-Stepanian 《Bulletin of Engineering Geology and the Environment》2002,61(3):197-205
The paper discusses the postulated suspension force, by which it is possible to explain some enigmatic phenomena observed
in different types of mass movements. This force is generated in thick suspensions as a result of friction between sinking
solid particles and static water. The suspension force is related to the seepage force but they have opposite directions.
Both forces form flow networks. Having explained the suspension force, the paper describes how this influences the movement
of material, particularly in debris flows. Enigmatic features and the mechanism of debris flows and lahars are explained by
virtue of the suspension force.
Electronic Publication 相似文献