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  • Author or Editor: C. Li x
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Summary

Two rapid, sensitive and reproducible methods for the determination of baclofen(BAL) in urine and plasma based on high-performance liquid chromatography (HPLC) with UV-vis and fluorescent detection, respectively, were developed for the first time using a new synthesized fluorescent label, 6-oxy-(N-succinimidylacetate)-9-(2′-methoxycarbonyl) fluorescein (SAMF). The optimal derivatization yield was achieved in borate buffer (pH 8.0) for 15 min at room temperature (25 °C). With a mixture of methanol and water containing 5 mmol L−1 sodium citrate buffer (pH 5.0) as mobile phase, BAL was determined at λ = 455 nm with UV-vis detection and at λ ex/λ em = 488/520 nm with FD detection. The detection limits are 1.065 × 10−3 mg mL−1 and 1.065 × 10−2 mg mL−1 with HPLC-UV-vis and HPLC-FD, respectively. The proposed method has been successfully applied to the analysis of BAL in human urine and plasma samples. The established method is rapid (15 min of derivatization process and 10 min of chromatographic run), reproducible and sensitive.

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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.

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Abstract  

In order to enrich the thermokinetic research methods and enlarge the applicable range of the thermokinetic time-parameter method, the integral and differential thermokinetic equations of consecutive first-order reaction have been deduced, and the mathematical models of the time-parameter method for consecutive first-order reactions have been proposed in this paper. The rate constants of two steps can be calculated from the same thermoanalytical curve measured in a batch conduction calorimeter simultaneously with this method. The thermokinetics of saponifications of diester in aqueoushanol solvent has been studied. The experimental results indicate that the time-parameter method for the consecutive first-order reaction is correct.

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Authors: C. Liu, S. Li, X. Wang, Z. Wang, H. Wang, R. Li, C. Xin, B. Li, L. Jiang and C. Jia

Abstract  

The migration of 99Tc in unsaturated Chinese loess was investigated in-situ with a tracer method. Quartz containing 3H (HTO) and 99Tc (99TcO4 -) was introduced into the bottom of an experimental pit which was then backfilled at the field test site. Then core soil samples were taken and cut vertically into 1 cm long slices. The slice samples were analyzed by liquid scintillation techniques in the laboratory. The results indicate that the migration pattern of 99Tc was quite similar to that of 3H and the vertical diffusion coefficients of 99Tc and 3H were calculated as (4.7±0.4).10-2 cm2/d and (7.8±0.4).10-2 cm2/d, respectively.

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Authors: C. Liu, Z. Wang, S. Li, Y. Yang, B. Li, H. Jiang, L. Jiang, L. Wang and D. Li
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The purpose of this study was to evaluate the ability of Lactobacillus rhamnosus to bind patulin (PAT) in the buffer solution and apple juice. The binding of L. rhamnosus to PAT was reversible, which improved the stability of the bacterial complex. The ability to bind PAT can be enhanced with the inactivation of the strain by high temperature and acid treatment. Acid-treated bacteria had the highest PAT binding rate of 72.73±1.05%. The binding rates of acid and high temperature (121 °C) treatments were increased by 21.37% and 19.15%, respectively. L. rhamnosus showed the best detoxification ability to PAT at 37 °C, where the binding rate reached 50.9±1.03%. When the dose of inactivated bacteria powder was 0.02 g ml−1, the minimum concentration of PAT in apple juice was 0.37 µg ml−1. The addition of the L. rhamnosus inactivated powder did not affect the quality of the juice product and effectively bound the PAT in apple juice.

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Authors: H. Quan, Z. Ge, Z. Li, C. Yin, K. Zhong, Z. Hao, H. Li and F. Ji

Abstract  

The desorption behaviour (desorption temperature and extent of desorption) of HF,HCFC-133a (CF3CH2Cl) and HFC-134a (CF3CH2F) on γ-AlF3 or catalyst supported on γ-AlF3 was studied using an adsorption apparatus and TG, DTA and DSC methods. On the basis of the results a reaction mechanism was proposed for the preparation of HFC-134a. The γ-AlF3 employed for preparing the catalyst was expected to be stable below 550C based on the crystalline phase transition temperature of γ-AlF3.

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A synthetic autopolyploid was developed from diploid Aegilops tauschii, D genome progenitor of common wheat (Triticum aestivum). The tetraploid Ae. tauschii displayed a markedly larger organ size than the diploid donor. Fluorescence in situ hybridization (FISH) and DNA marker analysis revealed that there is no clear variation at either the chromosomal or DNA level between the diploid and tetraploid plants. We analyzed the variation in cytosine methylation patterns between the diploid and tetraploid plants by methylation-sensitive amplified polymorphism (MSAP) and detected 228 and 232 methylated sites in diploid and tetraploid plants, respectively. Statistical comparison indicated that the tetraploid Ae. tauschii genotype displayed no significant difference in polymorphic methylation level compared to the diploid ones. Twenty-two different genomic fragments displaying different methylation behavior during the ploidy conversions were isolated and sequenced. It demonstrated that alterations in the level of methylation have the most profound effects on coding genes. We demonstrated that there are some genes expressions modified by DNA methylation may be correlated with phenotypic alteration after autotetraploidization.

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Authors: C. Li, X. Ma, A. Wang, E. Nevo and G. Chen

The aerial surface of land plants is protected by a cuticle against abiotic and biotic stresses. A better understanding of the determinants of cuticle formation and function has the potential to contribute to the breeding of more drought tolerant and disease resistant crop varieties. Two doubled haploid (DH) mapping populations, Steptoe × Morex populations and OWB-dominant × recessive populations were exploited to genetically position homologs of a set of known cuticle-associated genes. These genes were also placed on a consensus map, BinMap2005, which includes 27 eceriferum (cer) loci. Of the 49 known cuticle-associated genes, 21 identified a homolog in barley, and of these, 14 were mapped. There was a complete linkage between HvCER6 and cer-zg, suggesting the possibility that HvCER6 is the candidate gene of CER-ZG. Positioning known cuticle-associated genes on a consensus map containing cuticle mutant loci may guide the selection of candidate genes for cuticle mutants, and thus facilitate the isolation of cuticle-associated genes in barley.

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