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  • Author or Editor: G. Zhang x
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Abstract  

A series of UO2 2+ complex with monoamide ligand was isolated. The complexes have been characterized with the aid of 13C and 1HNMR spectroscopic studies. The result shows that the amide ligand directly coordinates to the uranyl(VI) ion through its carbonyl group. The change of the value of the chemical shift due to the complexation has been discussed.

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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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Abstract  

A simple direct labeling method was used to synthesize the iodinated ultrafine polystyrene particles. The assay of X-ray photoelectron spectroscopy (XPS) as well as Fourier-transform infrared (FT-IR) spectroscopy indicated the formation of stable covalent bond to aryl group of the polymer particles. The purified radioiodinated product was incubated with serum of rat, and then evaluated by in vitro stability test. The result showed that these synthesized ultrafine polystyrene particles were unmetabolized at 2 hours post-exposure, indicating the potential useful application of this labeled polymer particles as a promising probe in biomedical sciences.

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The simultaneous DSC-FTIR was used for the observation of crystallization and melting of poly(vinylidene fluoride) (PVDF) and its blends with poly(methyl methacrylate) (PMMA) and poly(ethyl methacrylate) (PEMA). The isothermal crystallization was carried out under the condition of both α-form and γ-form crystallized competitively. The crystal growth rate of α -form and γ -form were evaluated from the absorbance changes at 795 cm-1 (α -form, CH2 rocking) and 810 cm-1 (γ -form, CH2 rocking) obtained by the DSC-FTIR. The crystal growth rate of γ -form decreased at the same crystallization temperature in the order of PVDF/syn-PMMA, PVDF/PEMA and PVDF/at-PMMA, which was corresponding to the order of interaction parameter. The mechanism of α -g transition of PVDF in the miscible blends with at-PMMA, syn-PMMA and PEMA was evaluated from the relationship between the decrease of α -form and the increase of γ -form. The critical crystallization temperature, at which the transformation from α -form to γ -form proceeded only in the solid state, shifted to higher temperature side in the order of interaction parameter.

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Abstract  

The quality of measurement of heat capacity by differential scanning calorimetry (DSC) is based on the symmetry of the twin calorimeters. This symmetry is of particular importance for the temperature-modulated DSC (TMDSC) since positive and negative deviations from symmetry cannot be distinguished in the most popular analysis methods. Three different DSC instruments capable of modulation have been calibrated for asymmetry using standard non-modulated measurements and a simple method is described that avoids potentially large errors when using the reversing heat capacity as the measured quantity. It consists of overcompensating the temperature-dependent asymmetry by increasing the mass of the sample pan.

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Abstract  

The miscibility of crystalline syndiotactic polystyrene (SPS)/non-crystalline atactic polystyrene (APS) blend was estimated by the crystallization dynamics method, which evaluated the nucleation rate, the crystal growth rate and the surface free energy parameter. The melting temperature depression suggested that SPS/APS blends were the miscible system but not in molecular level. The relationship between the blend content and the chemical potential difference evaluated at a constant crystal growth rate showed a good linear relationship. These facts suggested that SPS/APS blends contained the concentration fluctuation with the size between few nm to less than 80 nm.

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Eight malting barley cultivars were used to investigate the cultivar and environmental effects on grain protein components and the relationships between protein fractions and β -amylase or β -glucanase activity. The results showed there was a great variation for three protein fraction (albumin, hordein and glutelin) contents over cultivars and locations, and a distinct difference in each protein fraction content between the locations for a given cultivars. Correlation analysis indicated that β -amylase activity was significantly correlated with three protein fraction contents and there was a negative correlation between glutelin content and β -amylase activity, but β -amylase activity positively correlated with albumin or hordein content. Furthermore, there was a significant positive correlation between total protein content and β -glucanase activity, and we found the hordein and glutelin content did not show correlated with β -glucanase activity but the albumin content was a significantly negative correlation with β -glucanase activity.

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Abstract  

The mixing state of poly(vinylidene fluoride) (PVDF) and two amorphous polymers,poly(methyl methacrylate) (PMMA) and poly(isopropyl methacrylate) (PiPMA) were investigated from the viewpoint of crystallization dynamics using simultaneous DSC-FTIR method. The crystallization rate (R *) and the growth rate of trans-gauche-trans-gauche’ (TGTG’) conformation (Rc *) depended on both the blend content (ϕ) and the crystallization temperature for PVDF/PMMA. The temperature and ϕ dependency of R * and Rc * were almost the same for PVDF/PMMA. However, R * and Rc * depended scarcely on f for PVDF/PiPMA, and the temperature dependency of R * differed from that of Rc * for PVDF/PiPMA. These results showed that PVDF and PMMA were miscible on molecular level, and that PVDF/PiPMA was immiscible and the concentration fluctuation existed in the PVDF-rich phase.

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Abstract  

We have conducted thermal and X-ray diffraction experiments on binary mixtures of symmetric stearic-oleic mixed-acid triacylglycerol (TAG) (1,3-distearoyl-2-oleoyl-glycerol: SOS) and asymmetric stearic-oleic mixed-acid TAG (1,2-dioleoyl-3-stearoyl-sn-glycerol: OOS), in which optically active sn-OOS was employed. We found that SOS–OOS mixtures exhibited immiscible monotectic or peritectic mixing behavior. This result was consistent with previous study on binary mixtures of 1,3-dipalmitoyl-2-oleoyl-glycerol (POP) and 1,2-dioleoyl-3-palmitoyl-rac-glycerol (OOP), in which racemic rac-OOP molecules were employed. The differences between the SOS–OOS and POP–OOP mixtures were in the polymorphic behavior of the fractions of POP and SOS. No effect was found from using an optically active (sn-OOS) or racemic mixture (rac-OOP) as an asymmetric oleic–oleic-saturated acid TAG. From the two results, we may conclude that an immiscible phase was formed in the binary mixtures of symmetric saturated-oleic-saturated TAGs and asymmetric oleic–oleic-saturated TAGs, of both racemic and optically active types. This result stands in contrast to mixtures of SOS–OSO (1,3-dioleoyl-2-stearoyl-glycerol), SOS–SSO (1,2-distearoyl-3-oleoyl-rac-glycerol), POP–OPO (1,3-dioleoyl-2-palmitoyl-glycerol), and POP–PPO (1,2-dipalmitoyl-3-oleoyl-rac-glycerol), all of which exhibited molecular-compound-forming behavior with molecular compound crystals at an equal ratio of the binary mixtures. Molecular-level mechanisms to explain this difference are discussed, based on possible roles of glycerol groups acting during the mixing processes of saturated–unsaturated mixed-acid TAGs.

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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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