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排序方式: 共有57条查询结果,搜索用时 62 毫秒
1.
Brett Ammundsen Gary R. Burns Ali Amran Stig E. Friberg 《Journal of Sol-Gel Science and Technology》1995,4(1):23-29
The effects of thermal treatment on composite materials prepared by the gelation of sols comprising large concentrations of metal oxide precursor salts have been investigated, in order to determine the compositional and thermal requirements for forming spinel magnesium manganates in such systems. The preparative technique has been found to give rise to derived gel materials in which the metal oxide phase, in the form of regular spherical particles, is dispersed throughout a continuous silica matrix. Silica-supported mixed magnesium and manganese spinel oxide phases were obtained for systems comprising at least 30 wt% metal nitrate after heating to temperatures between 700 and 850°C, but not without concomitant formation of Mn2O3 and modification of the silica network by magnesium. 相似文献
2.
3.
P. Morin M. B. Amran S. Favier R. Heimburger M. Leroy 《Fresenius' Journal of Analytical Chemistry》1992,342(4-5):357-362
Summary Capillary zone electrophoresis (CZE) in capillary silica columns has been used for the separation of arsenite (AsO
2
–
), arsenate (AsO
4
3–
), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The separation of these ionic species has been achieved using a capillary silica column (72 cm×50 m i.d.) with an acidic phosphate buffer and with an on-column UV detection (190 nm). Optimization of experimental parameters (pH, temperature, voltage) were studied. The selectivity of the separation can be improved by working in the pH-range of 4.5–6.5. For analytical inorganic separations of UV-absorbing anions, capillary zone electrophoresis has advantages because of the relatively simple equipment, the short analysis time (15 min), the high efficiency and the low mass detection limit (40 pg for arsenate). 相似文献
4.
5.
AA Yan LI Kai CAO ZhongHua & HU WenRui Key Laboratory of Microgravity 《中国科学:物理学 力学 天文学(英文版)》2011,(2)
The dependency of the critical Marangoni number on the geometrical aspect ratio of the floating half zone is essential to predict the onset of oscillatory thermocapillary convection.The experimental studies in the microgravity conditions on floating half zones of several centimeters in diameter have predicted that the critical Marangoni number increases with the increasing aspect ratio,and the terrestrial experimental studies have predicted the contradictory conclusion for floating half zones of several mil... 相似文献
6.
Non-Gravitational Effects with Density-Matching in Evaluating the Influence of Sedimentation on Colloidal Coagulation
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The method of density matching between the solid and liquid phases is often adopted to effectively eliminate the effect of sedimentation of suspensions in studies on dynamic behaviour of a colloidal system. However, the associated changes in the solvent composition may bring side effects to the properties investigated and therefore might lead to a faulty conclusion if the relevant correction is not made. To illustrate the importance of this side effect, we present an example of the sedimentation influence on the coagulation rate of suspensions of 2μm (diameter) polystyrene. The liquid mixtures, in the proper proportions of water (H2O), deuterium oxide (D2O) and methanol (MeOH) as the liquid phase, density-matched and unmatched experiments are performed. Besides the influence of viscosity, the presence of methanol in solvent media, used to enhance the sedimentation effect, causes significant changes (reduction) in rapid coagulation rates compared to that in pure water. Without the relevant corrections for those non-gravitational factors it seems that gravitational sedimentation would retard the coagulation. The magnitude of the contribution from the non-gravitational factor is quantitatively determined, making the relevant correction possible. After necessary the influence of the sedimentation on coagulation rates at corrections for all factors, our experiments show that the initial stage of the coagulation is not observable. 相似文献
7.
8.
Zidan Mohamed M. Houmani Amran Ab. Majid Shahidan Radiman Zaharudin Ahmad 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(2):271-277
226Ra is a member of the 238U natural decay series and is one of the most important isotope to be determined among the naturally occurring nuclides in
environmental samples. In order to evaluate the radiation dose from 226Ra, it is important to know its mobility in different types of soils. The aim of the present study is to quantify the influence
of physico-chemical soil properties on 226Ra adsorption. The distribution coefficients (K
d-value) of 226Ra in Selangor soil series samples were measured in one core, at three depth levels to evaluate the adsorbability of 226Ra. The soil samples were spiked with 226Ra tracer and the activities of 226Ra in the separated phase from batch sorption test were measured by a low background but high efficiency well-type HPGe detector.
Several physico-chemical soil properties were also characterised for each soil samples. Pearson’s correlation and stepwise
multiple regression test were applied at the 0.05 level of significance throughout all analysis to determine the relationships
and influences between distribution coefficients (K
d-value) of 226Ra with physicochemical soil properties for the Selangor soil series. The observed K
d value was in the range of 50.55–172.28 mL g−1 (mean: 93.20 ± 46.99 mL g−1). The regression showed that the highest positive correlations were observed for organic matter (OM) and cation exchange
capacity (CEC) (r = 0.96**, 0.81**, respectively) with K
d-values. The results indicate that the stepwise multiple regression model incorporating the soil’s OM and CEC accounts for
98% of the variability in distribution coefficients of 226Ra. 相似文献
9.
S. M. Jones A. Amran S. E. Friberg B. Katz G. C. Farrington 《Journal of Dispersion Science and Technology》2013,34(1):97-117
ABSTRACT Materials which display ionic conductivity were produced by the sol-gel and microemulsion-gel methods. The charging and discharging characteristics were investigated and it was found that a single ionic species was responsible for the conduction, the ionic species being residual protons from the initial component mixture. The complex impedence of various samples was measured and the ionic conductivities ranged in value from 9 × 10?8 to 1 × 10?5 ohm?1 cm?1. An Arrhemius plot for a microemulsion-gel revealed that the energy of activation was 0.15 eV. 相似文献
10.