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1.
Catalytic hydrolysis of NaBH4 and NH3BH3 has been studied. It was shown that the nature of the support and the active component of the catalyst affect the H2 generation rate. Despite similar sizes of rhodium particles formed on the surface of different supports (γ-Al2O3, TiO2, carbon), their reactivity is different. Rh/TiO2 with low rhodium concentration (1 wt.%) is the most active catalyst both in the hydrolysis of NaBH4 and NH3BH3. The obtained results show that the rhodium chloride interaction with titania determines the reactivity of rhodium particles formed under action of NaBH4 medium. TEM, DRS UV–vis and XPS were used to characterize the catalysts.  相似文献   
2.

Background  

Excess body fat is a major risk factor for disease primarily due to its endocrine activity. In recent years several criteria have been introduced to evaluate this factor. Nevertheless, treatment need is currently assessed only on the basis of an individual's Body Mass Index (BMI), calculated as body weight (in kg) divided by height in m2. The aim of our study was to determine whether application of the BMI, compared to adiposity-based criteria, results in underestimation of the number of subjects needing lifestyle intervention.  相似文献   
3.
Towards real CAD     
Present-day computer-aided design (CAD) packages play only a small part in the area of mechanical engineering design, which involves the synthesis and embodiment of physical components to perform a pre-determined function without unwanted side effects. The computer cannot properly help the designer in this task until it is able to capture and process the function requirements of the design. This paper describes the computer system being developed for this purpose at the Engineering Design Centre at Cambridge University Engineering Department. The paper also explores some of the geometrical and programming implications raised.  相似文献   
4.
Aluminium-neodymium oxide-aluminium thin film capacitors have been prepared by thermal evaporation and the d.c. conduction properties of these films have been studied. The thicknesses of the films have been determined by a multiple beam interferometer. The current-voltage power-law dependence showed that the conduction in these films is space-charge limited. The linear dependence of the current density on the square root of the applied field confirmed the exponential trap distribution. The trap density has been found to be of the order of 1026 m–3. It has also been observed that the Schottky type of conduction is predominant in the high-field region and the height of the Schottky barrier has been determined. It is seen that the conduction mechanism is an activated process with the activation energy decreasing with increasing field.  相似文献   
5.
The evaluation of the exploration risk in the oil industry is a fundamental component of the decision process related to the exploratory phase. In this paper the two basic components of the exploratory risk: trap geometry and trapped hydrocarbon quantities (fluid), are compounded in a single coherent uncertainty and sensitivity approach. The results clarify that the model geometry influences each Petroleum System Modeling step and that the geometric uncertainty is correlated with the fluid uncertainty. The geometric uncertainty evaluation makes use of geostatistical techniques that produce a number of possible realizations of the trap geometry, all compatible with available data. The evaluation of the fluid uncertainty, through a Monte Carlo methodology, allows us to compute the possible quantities of oil and gas, generated in a basin and migrated from the hydrocarbon source location to each single trap. The final result is the probability distribution of oil and gas for each trap in the basin, together with other useful indicators like: the hydrocarbon filling probability map, the closure probability map, the drainage area probability map, the spilling paths probabilities, the trap-filling scenarios.  相似文献   
6.
This paper presents the current understanding of the flame retardant mechanism of Casico?. The study includes the flame retardant effect of each individual component: ethylene–acrylate copolymer, chalk and silicone elastomer, as well as the formation of an intumescent structure during heating. The flame retardant properties were investigated by cone calorimetry and oxygen index tests. To obtain insight into the flame retardant mechanism, heat treatment under different conditions has also been performed. The results indicate that the flame retardant mechanism of Casico is complex and is related to a number of reactions, e.g. ester pyrolysis of acrylate groups, formation of carbon dioxide by reaction between carboxylic acid and chalk, ionomer formation and formation of an intumescent structure stabilized by a protecting char. Special emphasis is given to the formation of the intumescent structure and its molecular structure as evaluated from 13C MAS‐NMR and 29Si MAS‐NMR, ESCA and XRD analysis. After treatment at 500°C the intumescent structure consists mainly of silicon oxides and calcium carbonate and after treatment at 1000°C the intumescent structure consists of calcium silicate, calcium oxide and calcium hydroxide. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
7.
Pyrrole was successfully electropolymerized at a copper–nickel electrode in a near-neutral sodium oxalate solution containing Cu2+ cations to generate a homogenous and adherent polypyrrole film. The presence of the Cu2+ ions increased both the rate of the electropolymerization reaction and the adherence of the polymer at the CuNi interface. In the absence of these cations, oxidation of the electrode occurred generating a nickel-rich layer that was not sufficiently conducting, under the electropolymerization conditions employed, to facilitate the electron-transfer reaction and the electropolymerization of pyrrole.These films remained stable and exhibited significant corrosion protection properties in acidified and neutral 0.1 mol dm−3 NaCl solutions even on polarization of the electrodes to high anodic potentials.  相似文献   
8.
Of the several sources of acoustic information for distance perception, those arising from motion of the listener or sound source have received little attention. This motion-related information (recently called acoustic tau) is described, and experiments evaluating its utilization are presented. Accuracy and consistency at walking to the locations of briefly presented sounds were better when people listened while walking than while standing still. Manipulations of the sound to simulate shorter or longer target distances produced appropriate undershooting but not overshooting. The results indicate that people use motion-related acoustic information about distance to guide their locomotor actions, although they do not take full advantage of this information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
9.
10.
The diffusion coefficient of the cationic dye Anilana Red BL in the anionically modified polyester fiber Dilana has been calculated regarding a general diffusion-immobilization model. In the model the mobile species are distinguished from the immobilized ones. In computations of Sand's equation and experimentally determined sorption isotherm of the dye in the fiber, the rate-of-dyeing curve and the concentration profiles of the dye in the same fiber were employed. The diffusion coefficient of the mobile species of Anilana Red BL in the fiber is two orders of magnitude higher than the average diffusion coefficient obtained from Hill's equation and the apparent diffusion coefficient calculated by the Boltzmann–Matano method.  相似文献   
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