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  • Author or Editor: W. Li x
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Abstract  

Blends of known amounts of α- and β-PP crystals were prepared from pure α- and pure β-PPsamples. Their fusion behaviours were studied by differential scanning calorimetry (DSC).The fusion heats of the α- and β-crystals were approximated from the DSC curves and compared with those calculated on the basis of the compositions of the blends. A correction function was found which improved the accuracy of the respective fusion heats significantly from the DSC analysis. The correction function can be used to determine the respective fusion heats of a PP sample which contains an unknown mixture of the α- and β-crystals.

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It is widely reported that the productivity-richness relation (PRR) is highly variable, and several field studies suggest that the PRR varies with observational scale. Here we provide the first experimental study to test whether the PRR is scale-dependent when all replicate ecosystems have similar initial conditions. We also test the relation between productivity and compositional dissimilarity, and whether the PRR varies with ecosystem size. Moderately complex replicated microcosms were assembled consisting of a range of protozoa, algae, and a diverse bacterial flora. We found that the PRR of protozoan and algal communities varied with observational scale, but was unrelated to ecosystem size. Specifically, protozoan and algal richness increased monotonically with productivity at the local scale, but became flattened at the regional scale. This varying PRR at different scales occurred because dissimilarity among replicates decreased with productivity. Thus, in this model system, our experimental approach found a different form of scale dependence than previous field research. We speculate that this difference results from different processes governing extinctions at low levels of productivity.

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Abstract  

By using 188Re as a radiotracer, the extraction behavior of Re(VII) by a tertiary amine extractant N-235 from HCl and the back-extraction behavior of Re(VII) by HNO3 and ammonia were studied. A chemical separation procedure, which combined the acid alumina column and solvent extraction was established. The procedure was rapid and efficient for the separation of 186Re from 186W irradiated by 16 MeV deuterons. No-carrier-added 186ReO4 saline solution with high specific volume activity was obtained. The overall recovery yield of 186Re was about 85%.

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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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Summary  

Single aerosol particles were analyzed in the ambient air of the center of Shanghai by scanning proton microprobe to obtain characteristic X-ray spectra (micro-PIXE) which were considered to be the fingerprints of these aerosol particles. The origin of the lead-containing particles was identified by the combination of the micro-PIXE spectra with pattern recognition technique. It was found that the most of the lead-containing particles were derived from vehicle exhaust, coal combustion and soil dust.

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To identify feedback signal(s) controlling nitrate uptake by wheat roots, the effects of 13 amino acids on time course of net nitrate influx have been investigated. A new non-invasive technique of measuring net nitrate influx with a high time resolution of minutes has enabled us to make this comparison. The results showed that glutamate caused a rapid and large decrease of net nitrate influx by roots. Aspartic acid, asparagine, glutamine caused a relatively slow decrease of net nitrate influx with a lag of 0.5–1.5 h. Other amino acids had a small effect or even no effect. It is speculated that glutamate is most likely to be a negative feedback signal.

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Abstract

In this article, the enthalpy of dissolution for oxymatrine in 0.15 M citric acid solution is measured using a RD496-2000 Calvet Microcalorimeter at 36.5 °C under atmospheric pressure. The differential enthalpy (Δ dif H m) and molar enthalpy (Δ sol H m) were determined for oxymatrine dissolution in 0.15 M citric acid solution. On the basis of these experimental data and calculated results, the kinetic equation, half-life, Δ sol H m, Δ sol G m, and Δ sol S m of the dissolution process were also obtained.

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Abstract

Laburnine's dissolution behaviors in glucose and saline solution were studied by a micro-calorimetry method. The measured integral and differential heats of solution were utilized to build equations of the solute and the heat, so that dissolution thermodynamic equations and half-time periods, Δsol H m, Δsol G m, and Δsol S m were obtained. The results show that this study does not only provide a simple method for the determination of the half-life period for a drug but also offer a theoretical reference for the clinical application of laburnine.

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Abstract

In this article, the enthalpies of dissolution of resveratrol in dimethyl sulfoxide (DMSO) were measured using a RD496-2000 Calvet microcalorimeter at 298.15 K under atmospheric pressure. The differential enthalpy (Δdif H m) and molar enthalpy (Δsol H m) of dissolution of resveratrol in DMSO were determined, and the relationship between heat and the amount of solute was also established. Based on the thermodynamic and kinetic knowledge, the corresponding kinetic equation, half-life, Δsol H m, Δsol S m, Δsol G m, the relative partial molar enthalpy (Δsol H m(partial)) and the relative apparent molar enthalpy (Δsol H m(app)) of the dissolution process were obtained. The results showed that this study not only provided a simple method for the determination of the half-life for a drug, but also offered a theoretical reference for the clinical application of resveratrol.

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Youzimai is a widespread wheat landrace and has been used extensively in breeding programs in China. In order to assess the genetic variation between and within Youzimai accessions, samples of 31 landrace accessions of wheat, all called ‘Youzimai’, were collected from 6 geographic regions in China and evaluated using morphological traits, seedling resistance to powdery mildew, gliadin and microsatellite markers. Typical differences among accessions were observed in morphological characteristics. Forty-five (58.4%) of 77 assayed SSR markers showed polymorphism over the entire collection and total 226 alleles were identified with an average of 5.02 alleles per locus. SSR data indicated that the accessions from Hebei province were the most diverse, as evidenced by greatest number of region-specific alleles and highest diversity index. These accessions, therefore, probably experienced the most substantial morphological and molecular evolution as a result of various natural and anthropomorphic influences. On the other hand, differentiation in gliadin phenotypes was found among seeds within 80.6% of total accessions and average 61.5% of entire collections showed heterogeneous and comprised resistant plants in reaction to powdery mildew, suggesting the presence of a wide diversity within the wheat landrace. By developing an intimate knowledge of the available wheat genotypes, appropriate selections can be made for commercial application in order to conserve and exploit the diversity of the wheat landraces.

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