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  • Author or Editor: Y. Xia x
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Abstract  

Solvent extraction of uranyl nitrate in nitric acid medium with the binary system of DMHMP and DOSO has been investigated. It was found that synergistic effect occurs during the extraction of uranyl nitrate with benzene solution of DMHMP and DOSO, the binary species extracted UO2 (NO3)2·DMHMP·DOSO has been confirmed. From the data the equilibrium constants have been determined.

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A solvent extraction method was used to determine the stability constants of Np(V) complexes with fluoride and sulfate in 1.0M NaClO4 from 25 to 60 °C. The distribution ratio of Np(V) between the organic and aqueous phases was found to decrease as the concentrations of fluoride and sulfate were increased. Stability constants of the 1 : 1 Np(V)-fluoride complexes and the 1 : 1 Np(V)-sulfate and 1 : 2 Np(V)-sulfate complexes, dominant in the aqueous phase under the experimental conditions, were calculated from the effect of [F-] and [SO4 2-] on the distribution ratio. The enthalpy and entropy of complexation were calculated from the stability constants at different temperatures by using the Van't Hoff equation.

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Abstract  

Complexation of neptunium(V) with fluoride in aqueous solutions at elevated temperatures was studied by spectrophotometry and microcalorimetry. Two successive complexes, NpO2F(aq) and NpO2F2 , were identified by spectrophotometry in the temperature range of 10–70°C. Thermodynamic parameters, including the equilibrium constants and enthalpy of complexation between Np(V) and fluoride at 10–70°C were determined. Results show that the complexation of Np(V) with fluoride is endothermic and that the complexation is enhanced by the increase in temperature — a two-fold increase in the stability constants of NpO2F(aq) and more than five-fold increase in the stability constants of NpO2F2 as the temperature is increased from 10 to 70°C.

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Abstract  

Sulfate, one of the inorganic constituents in the groundwater of nuclear waste repository, could affect the migration of radioactive materials by forming complexes. Spectrophotometric and microcalorimetric titrations were performed to identify the Np(V)/sulfate complex and determine the equilibrium constants and enthalpy of complexation at 10–70°C. Results show that the complexation of Np(V) with sulfate is weak but slightly enhanced by the increase in temperature. The complexation is endothermic and becomes more endothermic with the increase in temperature. The enhanced complexation at elevated temperatures is due to the increasingly larger entropy of complexation that exceeds the increase in enthalpy, indicating that the complexation of Np(V) with sulfate is entropy-driven.

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Genotypes with various Vp-1B alleles perform different levels of pre-harvest sprouting (PHS) tolerance. In this study, 217 white-grained wheat cultivars, including 75 landraces, 39 historical cultivars, and 103 modern cultivars from five major regions of China, were examined to characterize the diversity of the Viviparous-1B ( Vp-1B ) locus associated with PHS tolerance. Four Vp-1B alleles were identified, three ( Vp-1Ba , Vp-1Bb and Vp-1Bc ) of which were previously reported in Chinese wheat cultivars. A new allele, Vp-1Be , was identified in the PHS tolerant landrace Hongheshangtou. Sequence analysis showed that Vp-1Be had an insertion of a 4-bp fragment, two SNPs, and a deletion of an 83-bp fragment compared with the nucleotide sequence of Vp-1Ba (AJ400713), all located in the third intron. Vp-1Be shared 97.80% similarity with the nucleotide sequence of AJ400713. The frequencies of Vp-1Ba , Vp-1Bb , and Vp-1Bc were 36.0%, 5.3%, and 57.3% in landraces; 23.1%, 7.7%, and 69.2% in historical cultivars; and 52.4%, 0%, and 47.6% in current cultivars, respectively.

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Abstract  

The complexation of plutonium(IV) with sulfate at variable temperatures has been investigated by solvent extraction method. A NaBrO3 solution was used as holding oxidant to maintain the plutonium(IV) oxidation state throughout the experiments. The distribution ratio of Pu(IV) between the organic and aqueous phases was found to decrease as the concentrations of sulfate were increased. Stability constants of the 1:1 and 1:2 Pu(IV)-HSO4 complexes, dominant in the aqueous phase, were calculated from the effect of [HSO4 ] on the distribution ratio. The enthalpy and entropy of complexation were calculated from the stability constants at different temperatures using the Van’t Hoff equation.

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Abstract  

In this paper the dependence of build-up233U,232U,233Pa and fission products from ThO2 irradiated in HFETR on integral thermal neutron fluxes and neutron spectra have been investigated. The yields of all above nuclides in ThO2 increase with the increase of integral thermal neutron fluxes at different neutron spectra. The values of233U/232Th increase with the increases of th and decreases with the increase of fast/thermal neutron ratios ( f/ th). The values of232U/233U increase with the increase of both th and f/ th ratio. The amount of fission products relative to original irradiated thorium decreases with the increase of f/ th ratios. These results could be used to evaluate the behaviour of thorium-based nuclear fuel in reactor.

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Summary

Silica-gel column chromatography and preparative reversed-phase high-performance liquid chromatography (RP-HPLC) were sequentially employed for the isolation of two antioxidants including gallic acid and methyl gallate from Folium Toonea Sinensis. An RP-HPLC-UV method was then developed and validated to rapidly determine their content in this herb with ethyl gallate as internal standard. The quantitation was performed on an XBridge Shield RP18 column (150 mm × 4.6 mm, 5 μm) under 40°C. The mobile phase consisting of acetonitrile and 0.1% formic acid aqueous solution was driven at 1.0 mL min−1 under gradient elution, and 270 nm was selected to monitor the separation. To evaluate the fitness for purpose of the method and to investigate the difference in the content of analytes among different samples, the leaves collected from five production sites were analyzed. The newly established method is suitable for routine analysis of gallic acid and methyl gallate in the herb and, hence, can assist in its quality assessment. It was also found that not only the content of two antioxidants but also the ratio varied significantly among different geographical origins. In addition, three samples from Yantai, Zumadian, and Zhenjiang were distinguished as they have a much higher content ratio than the other two.

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Uniformity in the height of main stem and tillers is a key factor affecting ideal plant type, a key component in super high-yielding rice breeding. An understanding of the genetic basis of the panicle layer uniformity may thus contribute to breeding varieties with good plant type and high yield. In the present study, a doubled haploid (DH) population, derived from a cross between indica rice variety Zhai-Ye-Qing 8 (ZYQ8) and japonica rice variety Jing-Xi 17 (JX17) was used to analyze quantitative trait loci (QTL) for panicle layer uniformity related traits. Six, four and three QTL were detected for the highest panicle height (HPH), lowest panicle height (LPH) and panicle layer dis-uniformity (PLD), respectively. qHPH-1-1 and qPLD-1 were located at the same interval on chromosome 1. The JX17 allele(s) of these QTL increased HPH and PLD by 2.57 and 1.26 cm, respectively. Similarly, qPLD-7 and qHPH-7 were located at the same interval on chromosome 7, where the ZYQ8 allele(s) increased HPH and PLD by 3.74 and 1.96 cm, respectively. These four QTL were unfavourable for panicle layer uniformity improvement because a decrease of the PLD was accompanied by decrease of the plant height. qPLD-6 and qLPH-6-1 were located at the same interval on chromosome 6, however here the JX17 allele(s) increased LPH, but decreased PLD, suggesting that this QTL was favourable for improvement of panicle layer uniformity. The markers identified in this study are potential for marker assisted breeding for the improvement of the panicle layer uniformity and ideal plant type.

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The aim of this study was to investigate the effects of maternal lead exposure on the learning and memory ability and expression of tau protein phosphorylation (P-tau) and beta amyloid protein (Aβ) in hippocampus of mice offspring. Pb exposure initiated from beginning of gestation to weaning. Pb acetate administered in drinking solutions was dissolved in distilled deionized water at the concentrations of 0.1%, 0.5% and 1% groups. On the 21 th of postnatal day, the learning and memory ability of the mouse pups was tested by Water Maze test and the Pb levels in blood and hippocampus of the offspring were also determined. The expression of P-tau and Aβ in hippocampus was measured by immunohistochemistry and Western blotting. The Pb levels in blood and hippocampus of all exposure groups were significantly higher than that of the control group ( P < 0.05). In Water Maze test, the performances of 0.5% and 1% groups were worse than that of the control group ( P < 0.05). The expression of P-tau and Aβ was increased in Pb exposed groups than that of the control group ( P < 0.05). Tau hyper-phosphorylation and Aβ increase in the hippocampus of pups may contribute to the impairment of learning and memory associated with maternal Pb exposure.

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