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Barley yellow dwarf virus-GAV (BYDV-GAV) is one of the most serious viruses on wheat in China. In this study, five BYDV-GAV isolates collected from five regions in Northwestern China were sequenced. The complete genome sequences generated in this study along with nine genome sequences of BYDV-GAV isolates available in GeneBank were compared and analyzed. The comparative analysis indicated that the complete genomes of BYDV-GAV showed a low level of genetic diversity with nucleotide sequence identities ranging between 97.0% and 99.7%, and the RNA-dependent RNA polymerase gene (ORF1 + ORF2) was the most variable within the complete genome. Phylogenetic analysis indicated that the BYDV-GAV isolates in Northwestern China could be divided into two groups. In addition, two potential recombination events were detected among the 14 BYDV-GAV isolates. This study provided a detailed description of molecular characterization of BYDV-GAV in Northwestern China based on the complete genome sequences, which increased the understanding of genetic diversity of barley yellow dwarf viruses.

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Abstract  

In this work, an easy, fast and reliable measurement technique for the quantitative determination of retained fission gases in an irradiated oxide fuel was developed. Many experiments were conducted to determine the optimum conditions for fusion of an oxide fuel, for the quantitative collection and measurements of the released gases. Ion implantation technology was applied to make a krypton or xenon references in a solid matrix. A fragment of oxide fuel, about 0.1 g of an unirradiated SIMFUEL, was completely fused with excess metallic fluxes, 1.0 g of nickel and 1.0 g of tin, in a graphite crucible of a helium atmosphere for 120 s at 850 A as a mixture of metals and alloys. About 96 ± 3 to 98 ± 4% of the krypton and xenon that were injected into the instrument using a standard gas mixture was reproducibly recovered by collecting the releasing gas through the instrument for 120 s. Using the same fusion and collection conditions, it was possible to recover about 97 ± 3% of the injected krypton and xenon by fusing a fragment of SIMFUEL which was wrapped with krypton or xenon implanted aluminum foils. The recovery test results of krypton and xenon using ion planted aluminum foils gave encouraging results suggesting their potential use as a reference specimen. It was confirmed that a fragment of irradiated oxide fuel, 0.051 g, with a code burn-up of 56.9 MWd/MtU, was completely fused as the mixture of metals and alloys through the fusion conditions and more than 99% of the retained fission gases were recovered during the first fusion. Since no cryogenic trap was needed, the collected gas could be measured directly and thus the analysis time could be further reduced. Approximately 7 min was sufficient to finish the measurement of retained fission gases in the irradiated oxide fuel using the developed procedure.

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Thermal properties of polylactides

Effect of molecular mass and nature of lactide isomer

Journal of Thermal Analysis and Calorimetry
Authors: J. Ahmed, J. Zhang, Z. Song, and S. Varshney

Abstract  

A thermal analysis of a series of polylactides (PLA) was carried out based on the number of average molecular mass (M n), and the nature of isomer (D, L and DL). It is confirmed that the glass transition temperature (T g) of PLA increased as a function of molecular mass irrespective of isomer type except sample with a high polydispersity index. The melting temperature (T m) and enthalpy of crystal fusion (ΔH f) of L-isomer increased as the M n was increased from 1100 to 27500. The degree of crystallinity (χc%) increased as a function of molecular mass. However no crystallization peak was detected in the lower molecular mass range (550–1400). The non-isothermal crystallization behavior of the PLA melt was significantly influenced by the cooling rate. Both D and L isomers exhibited insignificant difference in thermal properties and DL lactides exhibited amorphous behavior at identical molecular masses. Change in microstructure showed significant difference between two isomers. Analysis of the FTIR spectra of these PLA samples in the range of 1200–1230 cm−1 supported DSC observation on crystallinity.

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Abstract  

In this work the analysis procedures of fission gas compositions and their isotopic distributions using a gas chromatography (GC) system and/or a quadrupole mass spectrometer (QMS) system were established, and their analysis results were reviewed in order to evaluate their analytical performance. Also, the accumulated data, up to now, regarding fission gas measurement were reviewed to discern any irradiation histories of the punctured fuel rods. A simple gas injection apparatus was designed and fabricated for the quantitative injection of a small volume of fission gas into the GC and the QMS system. With an appropriate temperature controlling of a molecular sieve 5A column, nitrogen, krypton and xenon of a mixture gas was clearly separated within 7 min. According to the analysis results, the relative standard deviation in the determination of fission gas compositions, krypton and xenon, by the GC analysis or by the QMS analysis was about 1%. Based on the review results of the isotopic ratios of krypton and xenon of the released fission gas, it is likely that no abnormally irradiated rods, i.e. defected rods, were included among the punctured rods.

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Summary

A new high-performance liquid chromatography (HPLC) method has been developed and validated for determination of enantiomeric purity of thiazolidine-2-carboxylic acid within a short run time of less than 10 min. The method was based on pre-column derivatization of thiazolidine-2-carboxylic acid with aniline, and complete separation of enantiomers has been achieved on a Chiralcel OD-H analytical column (250 × 4.6 mm) using n-hexane-isopropanol (85:15 v/v) as mobile phase at a flow rate of 1.0 mL min−1 under UV and optical rotation (OR) detection. Detection wavelength was set at 254 nm. Then the effects of mobile phase and temperature on enantioselectivity were further evaluated. The method was validated with respect to precision, accuracy, linearity, limit of detection (LOD), limit of quantification (LOQ), and robustness. The recoveries were between 98.5 and 101.3% with percentage relative standard deviation less than 1.16%. The LOD and LOQ for the aniline derivatives of (+)-thiazolidine-2-carboxylic acid were 4.9 and 16.4 μg mL−1 and for the aniline derivatives (−)-thiazolidine-2-carboxylic acid were 5.1 and 17.2 μg mL−1, respectively.

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Abstract  

The sorption/desorption of radioruthenium was investigated by the batch method in sea water system at ambient temperature on the surface sediments obtained around the Daya Bay of Guangdong Province, where the first nuclear power station of China has been running from 1994. It was found that the sorption percentage was obtained to be around 40% for all the surface sediments in 60 minutes. Then, the sorption percentage goes up slowly. The sorption percentage of radioruthenium reached around 80% in 113 days (2713 hours). The distribution coefficients decreased from 3.16·104 to 1.35·103 ml/g with the increasing of sediment concentration in the range of 4–10000 mg/l. The results of the desorption experiments suggest that the sorption of radioruthenium is irreversible with 81.5% relative hysteresis coefficient.

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Abstract  

Effects of pH, ionic strength and fulvic acid on sorption of radiocobalt on montmorillonite and its Al-pillared and cross-linked samples were studied using batch technique. The results indicate that the sorption of cobalt is strongly dependent on pH values and independent of ionic strength. Fulvic acid enhances the sorption of cobalt slightly at low pH, but has no influence at high pH values. Surface complexation is considered the main mechanism of cobalt sorption to montmorillonite. The sequences of FA/Co2+ additions to the system did not affect cobalt sorption.

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Abstract  

Three kinds of marine bivalves (wild Saccostrea cucullata, aquacultured Perna viridis and aquacultured Pinctada martens), collected from Daya Bay, the South China Sea, were used to investigate the bio-accumulation of radioruthenium in the glass aquarium with natural seawater (pH 8.20, 35‰ salinity, filtered by 0.45 μm) at ambient temperature under laboratory feeding conditions. The experimental results show that the stead-state of biology concentration factor (BCF, ml/g) of radioruthenium was approached around 6 days for most species of bivalves. The values of BCF in shells are the highest in organs all the three bivalves. The orders of BCF values (ml·g−1) are as: Perna viridis (33.2) < Saccostrea cucullata (47.0) < Pinctada martensi (208.4) for shells and Saccostrea cucullata (1.5) < Pinctada martensi (2.2) ≈ Perma viridis (2.4) for soft tissues, respectively, after exposed for 14 days. The rate constants of uptake and elimination of radioruthenium on marine bivalves were also discussed by first-order kinetics model. The Pinctada martensi may be applicable to be an indicator for monitoring radioruthenium among the three bivalves.

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Abstract  

The effects of Amoxicillin Sodium and Cefuroxime Sodium on the growth of E. coli DH5α were investigated by microcalorimetry. The metabolic power-time curves of E. coli DH5α growth were determined by using a TAM air isothermal microcalorimeter at 37�C. By evaluation of the obtained parameters, such as growth rate constants (k), inhibitory ratio (I), the maximum heat power (P m) and the time of the maximum heat power (t m), one found that the inhibitory activity of Amoxicillin Sodium vs. E. coli DH5α is enhanced with the increasing of the Amoxicillin Sodium concentration, and the Cefuroxime Sodium has a stimulatory effect on the E. coli DH5α growth when the concentration is about 1 μg mL−1. The IC50 for the Amoxicillin Sodium and the Cefuroxime Sodium are 1.6 and 2.0 μg mL−1, respectively, it implicates that the E. coli DH5α is more sensitive to Amoxicillin Sodium than Cefuroxime Sodium.

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