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- Author or Editor: X. Wang x
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Abstract
The effect of pH and concentration on the diffusion of 137Cs in the compacted bentonite is studied with capillary method at the ionic strength of 0.1M NaClO4. The apparent diffusion coefficient increases with increasing concentrations if the sorption of radionuclides is largely dependent on the radionuclide concentrations. The apparent diffusion coefficient decreases with increasing pH because most of the radionuclide sorption on the bentonite increases with increasing pH. The interlaminary space contributes significantly to the radionuclide diffusion and sorption in compacted bentonite. The relationship of the apparent diffusion coefficient and the effective diffusion coefficient of 137Cs is also discussed.
Abstract
In [10], the notion of homogeneous perfect sets as a generalization of Cantor type sets is introduced and their Hausdorff and lower box-counting dimensions are studied. In this paper, we determine their exact packing and upper box-counting dimensions based on the length of their fundamental intervals and the gaps between them. Some known results concerning the dimensions of Cantor type sets are generalized.
Abstract
This paper gives a characterization of finite groups G in which each cyclic subgroup either is normal in G or normalizes all subgroups of G.
Abstract
Direct anchoring of the synergistic extractant TOPO-P204 onto the inner walls of mesoporous molecular sieve generates a non-stoichiometric synergistic extractive membrane absorbent: MCM-TP which has well-spaced and structurally well defined active sites. Specifically, the feasibility of applying the MCM-TP absorbent with an absorption capacity of 0.02 mmol[Pd]/gabsorbent to the recovery of non-radioactive palladium from spent nuclear fuels has been examined showing an advantage over the liquid-liquid extraction or precipitation method. MCM-TP studied by powder XRD, TEM and29Si MAS NMR indicates that it has 35 Å regular, well-defined channels and an improved hydrothemal stability.
Summary
Dauricine has a variety of pharmacological properties including anti-inflammatory, anti-arrhythmic, and antihypertensive effects as well as reversing multidrug resistance (MDR) of cancer cells. While its therapeutic application is increasing, its bioavailability of different administration routes has not been studied. In the present study, we developed and validated a liquid chromatography/electrospray ionization mass spectrometry method (LC-MS/MS). Using this method, we quantified dauricine in rat plasma after administration via intravenous (i.v.) injection, per oral (p.o.), and intraperitoneal injection (i.p.). Our results indicated that this method detected plasma dauricine with a good linearity in the range of 1.95–1000.00 ng/mL (r = 0.9997). The extraction method showed an average intra- and inter-day recovery of 98.21–104.35% and 98.0–103.58%, respectively. Dauricine showed a fast absorption and widespread distribution after administration in all three tested routes. After intravenous administration (2.5, 5.0, 10.0 mg/kg), the pharmacokinetics of dauricine exhibited a first-order kinetics. In addition, dauricine showed a slow elimination with a long half-life (t 1/2z) and double peaks phenomenon following p.o. and i.p. administration. Furthermore, using area under the plasma concentration-time curve (AUC), we calculated absolute bioavailability, which was over twofold higher when administered via i.p. than via p.o. administration. The newly obtained information from our study will provide important reference for dauricine dose and administration route in designing dauricine therapy for applicable diseases.
Triclocarban (TCC) and triclosan (TCS) are used in a wide range of household and personal care products and have been the most frequently detected organic pollutants in both wastewater and surface water. This paper presented a rapid analytical method for simultaneous determination of TCC and TCS in wastewater. The method involves the extraction and cleanup of the target compounds by using silicon dioxide/polystyrene composite microspheres solid-phase extraction and detection with ultra-high-pressure liquid chromatography. Under the optimized conditions, the limits of detection were 0.028 μg/L and 0.040 μg/L for TCC and TCS, respectively. Under the concentrations of the spiking level ranging from 0.100 μg/L to 2.000 μg/L, the spiked recoveries of TCC and TCS in wastewater samples achieved in the range of 89.5–102.8% with RSD below 6.3% for TCC and 95.5–103.6% with RSD below 6.9% for TCS. This method was successfully used in monitoring the water samples from three traditional wastewater treatment plants.
Lycopene content (LC) and soluble solid content (SSC) are important quality indicators for cherry tomatoes. This study attempted simultaneous analysis of inner quality of cherry tomato by Electronic nose (E-nose) using multivariate analysis. E-nose was used for data acquisition, the response signals were regressed by multiple linear regression (MLR) and partial least square regression (PLS) to build predictive models. The performances of the predictive models were tested according to root mean square and correlation coefficient (R2) in the training set and prediction set. The results showed that MLR models were superior to PLS model, with higher value of R2 and lower values of for RMSE firmness, pH, SSC, and LC. Together with MLR, E-nose could be used to obtain firmness, pH, soluble solid and lycopene contents in cherry tomatoes.
Abstract
A new thermokinetic reduced extent method for the product inhibition of single substrate enzyme-catalyzed reactions is proposed and compared with the traditional initial rate method in this paper. The arginase-catalyzed hydrolysis of L-arginine to L-ornithine and urea was studied at 37C in 40 mM sodium barbiturate-HCl buffer solution (pH=9.4). Michaelis constant (K m) for arginine and maximum velocity (V m) of the reaction were determined by initial method and thermokinetic method. The activation of exogenous manganese to this reaction was also studied. The product inhibition constant (K P), which cannot be obtained directly from the initial rate method, was determined by thermokinetic without adding L-ornithine to the reaction system. When the concentration of Mn2+ in cell is 0.1 mM, the enzyme gets its full activity. Incubation arginase with appropriate concentration of Mn2+resulted in increased Vmax and a higher sensitivity of the enzyme to product with no change in the K m for arginine. We suggest that the exogenous manganese ions in solution have just recovered the activity of arginase, which was lost in dissolving and dilution, but no effect on the mechanism of the reaction.
Summary
Supercritical fluid extraction (SFE) was used to extract shionone from Aster tataricus L. f. The effect of various parameters, i.e., temperature, pressure and sample particle size on yield was investigated with an analytical-scale SFE system to find the optimal conditions. The process was then scaled up by 50 times with a preparative SFE system under the optimized conditions of temperature 40 °C, pressure 30 MPa, and a sample particle size of 40–60 mesh. Then preparative high-speed counter-current chromatography was successfully used for isolation and purification of shionone from the SFE extract with a two-phase solvent system composed of n-hexane-methanol (2:1, volume ratio). The separation produced a total of 75 mg of shionone from 500 mg of the crude extract in one step separation with the purity of 98.7%, respectively, as determined by high-performance liquid chromatography (HPLC) and 92% recovery. The structure of shionone was identified by electrospray ionization-mass spectrometry (ESI-MS), hydrogen-1 nuclear magnetic resonance (1H-NMR), and carbon-13 nuclear magnetic resonance (13C-NMR).
Abstract
Two methods, e.g. initial rate method and thermokinetic reduced extent method were presented for studies on non-competitive inhibition. Arginase-catalyzed the hydrolysis of L-arginine toL-ornithine and urea and the inhibition of this reaction by sodium fluoride were studied in the absence and presence of exogenous of Mn2+at 37C in 40 mM sodium barbiturate-hydrochloric acid buffer solution (pH 7.4). Both methods were successively used to determine the values of K1. The advances and disadvantages of each method were compared in this paper. Exogenous Mn2+ could result in more sensitivity of arginase to F-1. Since the inhibition of arginase by F-1 depends on the pH values of the reaction system and behave as a non-competitive inhibition, it probably due to its small volume and high electronic density allow it access to the activity site of the enzyme and replaces of -OH2 (or -OH) as the bridge ligand with Mn(II, II) cluster. However, further studies are necessary to determine the modes of interaction of F-1 with bovine liver arginase.
