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- Author or Editor: X. Wang x
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Abstract
The kinetics of protein thermal transition is of a significant interest from the standpoint of medical treatment. The effect of sucrose (0–15 mass%) on bovine serum albumin denatured aggregation kinetics at high concentration was studied by the iso-conversional method and the master plots method using differential scanning calorimetry. The observed aggregation was irreversible and conformed to the simple order reaction. The denaturation temperature (T m), the kinetic triplets all increased as the sucrose concentration increased, which indicated the remarkable stabilization effect of sucrose. The study purpose is to provide new opportunities in exploring aggregation kinetics mechanisms in the presence of additive.
Abstract
The interactions of lanthanide ions (Ln3+) with bovine serum albumin (BSA) under mimetic physiological conditions (310.15 K, pH 6.7, 0.1MNaCl) were studied by microcalorimetry. For the first time, based on Two Sets of Independent Sites Model, molar enthalpies (Δr H m1, Δr H m2) and coordination number (n 1, n 2) of the two sets of binding sites with different affinity were obtained directly from the microcalorimetric results. It was shown that the interactions are endothermic and entropy-driving processes. By combining with fluorescence spectroscopy, other thermodynamic parameters (Δr G m1, Δr S m1) were determined for high-affinity specific sites.
Abstract
2,2-dinitropropyl acrylate (DNPA), 2,2-dinitrobutyl acrylate (DNBA) and 2,2-dinitrobutyl methacrylate (DNBMA) were synthesized and the kinetics of their free-radical polymerization in the presence of 2,2′-azobisisobutyronitrile (AIBN) were investigated by DSC in the non-isothermal mode. The kinetics of the free-radical polymerization as estimated by the Kissinger and Ozawa methods showed that the reaction is disfavoured by increasing steric hindrance around the acrylyl double bond. The rate constants calculated from the activation parameters showed the structural dependency. The polymerization kinetics revealed that the polymerizability of three monomers decreased due to the presence of substituent methyl groups on the acrylyl double bond and 2,2-dinitrobutyl on ester group. Thus, the polymerization tendency increased in the order DNPA>DNBA>DNBMA.
Summary
Rapid high-performance liquid chromatographic methods with evaporative light scattering detection (HPLC-ELSD) and electrospray ionization multistage mass spectrometry (HPLC-ESI-MSn) have been established and validated for simultaneous qualitative and quantitative analysis of eight steroidal saponins in ten batches of Gongxuening capsule (GXN), a widely commercially available traditional Chinese preparation. The optimum chromatographic conditions entailed use of a Kromasil C18 column with acetonitrile-water (30:70 to 62:38, υ/υ) as mobile phase at a flow rate of 1.0 mL min−1. The drift tube temperature of the ELSD was 102°C and the nebulizing gas flow rate was 2.8 L min−1. Separation was successfully achieved within 25 min. LC-ESI-MSn was used for unequivocal identification of the constituents of the samples by comparison with reference compounds. The assay was fully validated for precision, repeatability, accuracy, and stability, then successfully applied to quantification of the eight compounds in samples. The method could be effective for evaluation of the clinical safety and efficacy of GXN.
Abstract
The surface structure of triuranium octaoxide (U3O8) and the effect of CO on surface behaviour have been studied by X-ray photoelectron spectroscopy (XPS). An intensity analysis of the composite U4f photoelectron spectrum of U3O8 shows that this compound should be written as U2 VIUIVOg. After exposure to 7.2·106 L CO (1 L=1.33·10–4 Pa·s), the oxygen content in the surface is decreased and the O1s/U4f ratio decreases about 10%. The investigation indicated that the surface layer of triuranium octaoxide was partially reduced in the atmosphere of carbon monoxide.
Abstract
The surface reactions of uranium metal with carbon monoxide at 25 and 200 °C have been studied by X-ray photoelectron spectroscopy (XPS); respectively. Adsorption of carbon monoxide on the surface layer of uranium metal leads to partial reduction of surface oxide and results in U4f photoelectron peak shifting to the lower binding energy. The content of oxygen in the surface oxide is decreased and O1s/O4f ratio decreases with increasing the exposure of carbon monoxide. The investigation indicates the surface layer of uranium metal has resistance to further oxidation in the atmosphere of carbon monoxide.
Abstract
A new method of thermal desorption chromatography, in which hydrogen is used as carrier instead of helium, and a water bath instead of an air bath, is presented for determining the specific surface area of uranium compounds. The method proposed has a higher accuracy and a better applicability.
Abstract
We prove that the conjugate convolution operators can be used to calculate jumps for functions. Our results generalize the theorems established by He and Shi. Furthermore, by using Lukács and Móricz's idea, we solve an open question posed by Shi and Hu.
Maize seeds from inbred line Mo17, susceptible to Sugarcane mosaic virus (SCMV), were investigated for SCMV seed transmission. The seed quality significantly influenced the seed transmission rate. There were more infected seedlings derived from larger seeds than smaller seeds in both golden (G) and buff (B) seed groups, the proportion of infected seedlings in G1 was similar to G2 and B1, and significantly higher than the others (P < 0.05 or P < 0.01). While the proportion of SCMV seed transmission was higher in golden (3.9%) than buff seeds groups (2.3%), and there were significantly difference (P < 0.05) between the both colors seeds. However the percentage of infected seedlings was closely related to the location of seeds on ears, most infected seedlings were derived from seeds of the middle (Part III) and mid-base regions (Part IV), and the both parts (Parts III and IV) were significantly higher than that of Part I (P < 0.05). Fisher’s exact test indicated that the seed quality was associated significantly with the efficiency of SCMV seed transmission.
Abstract
The '
in-diffusion
method was used to study the diffusion behavior of Eu(III) in compacted bentonite. The results (K
d, apparent and effective diffusion coefficients) derived from the capillary method are in good agreement with the literature data for similar bentonite dry densities and similar radionuclide concentrations, and fits the Fick's second law very well. The method was used to study the effect of solution concentration (10-7-10-3 mol/l) on the diffusion and sorption behavior in compacted bentonite. The experiments were carried out in synthetic groundwater, at room temperature. The results suggested that the diffusion of Eu(III) in the bentonite was independent on the density of bentonite, but dependent on the solution concentration. In agreement to the literature, the K
d values from the capillary experiments are in most cases lower than those from batch experiments, they are about one-half to one-third the value to those from batch experiments. The difference between the K
dvalues from capillary and batch experiments are a strong function of the bulk density of the bentonite. The results suggest that the content of interlaminary space plays a very important role to the transport of Eu(III) in compacted bentonite.
