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Abstract  

The application of a microcalorimetric method to the study of extremophiles is described briefly. Using the LKB 2277 Bioactivity Monitor, the growth thermogenic curves of three strains of Halobacterium halobium were determined at 37C, and compared with the spectrophotometric curves. Then the suitable growth thermokinetic equation was established based on the characteristics of growth thermogenic curves. By using cycle-flow method, all of the growth thermogenic curves of H. halobium strains displayed a brief lag phase before the onset of exponential growth when they were cultured in Halo-2 medium.

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Abstract  

The radiation effect of γ-ray on polyether-urethane foam was studied. The gas products from irradiated samples were analyzed quantitatively and qualitatively by gas chromatography, the thermal property and radical intensity were determined by differential thermal gravimetry and electron spin resonance. The dynamic mechanical property, compression and tensile properties were analyzed. Positron annihilation lifetime of irradiated samples was also measured at room temperature in vacuum. The results show that the general mechanical properties of ETPU sample irradiated by γ-rays at a dose of 8.0·105 Gy is excellent, but there are considerable gas products and a great deal of radicals created, which indicates that the sample has been damaged by radiation. Relatively, the thermal stability of the sample remained fine.

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Abstract  

The characteristic properties of the chelating resin-3926(II) and the advantage of using it in the preconcentration procedure was described. The chemical recoveries determined by the trace technique were presented. The preconcentration procedure put forward in this paper may be used satisfactorily in neutron activation analysis.

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Abstract  

Multiwall carbon nanotubes (MWCNTs) oxidized by nitric acid solution were used to investigate the adsorption behavior of strontium from aqueous solutions similar to the nuclear waste media. The physical properties of both as produced and oxidized MWCNTs were studied by Boehm’s titration method and nitrogen adsorption/desorption. The results showed that the surface properties of MWCNTs such as specific surface area, functional groups and the total number of acid sites were improved after oxidation. Furthermore, the effect of solution conditions such as initial concentration of strontium(II), pH, ionic strength, MWCNT concentration and contact time were studied at room temperature. The results of this study showed that the adsorption of strontium(II) was significantly influenced by the pH value and the solution ionic strength. According to the Langmuir model, the maximum adsorption capacities of strontium(II) onto the as produced and oxidized MWCNTs were obtained as 1.62 and 6.62 mg g−1, respectively. The contact time to reach equilibrium was 100 min. The good adsorption of strontium(II) on oxidized MWCNTs at the lower ionic strength, the relatively high pH and the short equilibrium time indicate that the oxidized MWCNTs have great potential applications in the field of the environmental protection.

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Abstract  

Multiwall carbon nanotubes (MWCNTs) were modified by nitric acid solution and then used to study the adsorption of cesium from aqueous solution using a batch technique under ambient conditions. As produced and oxidized MWCNTs were characterized by nitrogen adsorption/desorption, Boehm’s titration method and Fourier transform infrared spectroscopy. The physical properties of MWCNTs such as functional groups, total number of acid sites and specific surface area were greatly improved after oxidation, and these were responsible for more sorption of cesium from aqueous solution and made them more dispersible in water. The adsorption of cesium ions as a function of contact time, initial concentration of cesium, pH, ionic strength and oxidized MWCNT concentrations was also investigated. The results showed that cesium adsorption percentage strongly depended on the pH value, oxidized MWCNT content and on the solution ionic strength. Kinetic data indicated that the adsorption process achieved equilibrium within 80 min. Equilibrium data for as produced and oxidized MWCNTs was well described by both Freundlich and Langmuir isotherms. The dominant mechanism of cesium adsorption on oxidized MWCNTs may be mainly attributed to ion exchange. This study suggests that oxidized MWCNTs can be a promising candidate for the removal of cesium from nuclear waste solution.

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Journal of Thermal Analysis and Calorimetry
Authors: C. Zeng, J.-C. Zhu, Y. Liu, Y. Yang, J.-Y. Zhu, Y.-P. Huang, and P. Shen

Abstract  

Microcalorimetry was used to study the influence of NaCl concentration on Halobacterium salinarum growth. From the thermogenic curves and thermokinetic parameters of H. salinarum growth in different concentrations of NaCl, it was found that the optimum NaCl concentration for H. salinarum growth was not a wide range from 3.5 mol L–1 to NaCl saturation (about 5.2 mol L–1), as is generally acknowledged, but just around 230 g L–1 (approximately 3.9 mol L–1). And when external NaCl concentration was above 230 g L–1, the growth metabolism of H. salinarum decreased constantly with the increasing of NaCl concentration. These have never been described before. Further investigation by transmission electron microscopy revealed that H. salinarum growing in approaching NaCl saturation underwent plasmolysis, which interpreted the novel finding of microcalorimetry perfectly. Our work shows that microcalorimetry may reveal more and newer details about microbial growth than the existing methods do. These details are significant to understand biological processes.

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Biofortifying food crops with essential minerals would help to alleviate mineral deficiencies in humans. Detection of quantitative trait loci (QTLs) for mineral nutrient contents in rice was conducted using backcross inbred lines derived from an interspecific cross of Oryza sativa × O. rufipogon. The population was grown in Hangzhou and Lingshui, with the contents of Mg, Zn, Fe, Mn, Cu and Se in brown rice measured in both trials and that in milled rice tested in Hangzhou only. A total of 24 QTLs for mineral element contents were identified, including two for both the brown and milled rice, 17 for brown rice only, and five for milled rice only. All the seven QTLs detected for the mineral contents in milled rice and 13 of the 19 QTLs for the contents in brown rice had the enhancing alleles derived from O. rufipogon. Fifteen QTLs were clustered in seven chromosomal regions, indicating that common genetic-physiological mechanisms were involved for different mineral nutrients and the beneficial alleles could be utilized to improve grain nutritional quality by markerassisted selection.

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Abstract  

A separation procedure of trace platinum from large amounts of mercury and other interfering elements is described. After irradiation, the HgO target was dissolved in concentrated HCl solution. The thallium fraction was removed by solvent extraction with ether. In the aqueous phase after extraction the radioisotope of platinum produced by irradiation was precipitated as (NH4)2PtCl6 by adding a saturated solution of NH4Cl in the presence of H2PtCl6·6H2O as stable carrier. The decontamination factor of mercury, gold and thallium and the recovery of platinum in the process of separation are satisfactory.

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Abstract  

This study investigates uptake of cesium and strontium from aqueous solution similar to nuclear waste on three samples of titanium molybdophosphate (TMP) synthesized under various conditions. Effects of concentration of sodium nitrate, pH and contact time on the uptake of cesium and strontium have been studied by bath method. The results showed that TMP has high affinity toward cesium and strontium at pH > 2 and relatively low concentration of sodium nitrate. Kinetic data indicated that cesium uptake process to achieve equilibrium was faster than strontium. Cesium and strontium breakthrough curves were examined at 25 °C using column packed with H3O+ form of TMP and breakthrough curves showed symmetrical S-shaped profiles. At the same time, the calculated breakthrough capacity for cesium was higher than strontium. The results of desorption studies showed that over 99% of cesium and strontium was washed out of column by using 4 M NH4Cl solution. This study suggests that TMP can have great potential applications for the removal of strontium and specially cesium from nuclear waste solution.

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The purpose of this study was to measure the effect of co-lyophilized polymers on the crystallization of amorphous sucrose, and to test for a possible relationship between the ability of an additive to raise theT g of a sucrose-additive mixture, relative to theT g of pure sucrose, and its ability to inhibit crystallization. Differential scanning calorimetry was used to measure the glass transition temperature,T g, the non-isothermal crystallization temperature,T c, and the induction time for crystallization,Q, of sucrose in the presence of co-lyophilized Ficoll or poly(vinylpyrrolidone) (PVP). The effect of these polymers on the crystallization of sucrose was significant as demonstrated by a marked increase inT c, and in the induction time (Q) in the presence of relatively small amounts (1–10%) of additive. Surprisingly, small amounts of polymeric additive had no effect on theT g of sucrose, although at higher concentrations, theT g increased proportionally. Thus, it appears that the inhibition of sucrose crystallization by the additition of small amounts of a higher-T g component cannot be attributed solely to changes in molecular mobility associated with an increase inT g.

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