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  • Author or Editor: M. Liu x
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Abstract  

The freezing and melting of water in semi-dilute (0.5–3.0%) solutions of the polysaccharide hyaluronanhave been investigated by modulated differential scanning calorimetry.High molecular weight hyaluronan inhibited nucleation of ice and significantly depressed thefreezing temperature in a dynamic scan conducted at –3.0°C min–1. Low molecular weight hyaluronan had a weaker and more variable effect on nucleation. Theeffects on nucleation, especially by the high molecular weight hyaluronan, are attributed tothe influence of a hyaluronan network on the formation of critical ice nuclei.Both high and low molecular weight hyaluronan reduced the melting temperature of ice by 0.4–1.1°C, depending on concentration. The enthalpy change associated with this transitionwas significantly reduced. If all of the enthalpy difference is attributed to the presence of non-freezing water, approximately 3.65 g water/g hyaluronan would be non-freezing. This result appears incompatible with published studies on hyaluronan samples of low water content. An alternative hypothesis and quantitative approach to analysis of the data are suggested. The data are interpreted in terms of a small amount of non-freezing water, and amuch larger boundary layer of water surrounding hyaluronan chains, which has slightly altered thermodynamic properties relative to those of bulk water. The boundary layer water behaves similarly to water trapped in small pores in solid materials and hydrogels.

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Abstract  

Blends of poly(ether-sulfone) (PES) and poly(phenylene sulfide) (PPS) with various compositions were prepared using an internal mixer at 290C and 50 rpm for 10 min. The thermal and dynamic mechanical properties of PES/PPS blends have been investigated by means of DSC and DMA. The blends showed two glass transition temperatures corresponding to PPS-rich and PES-rich phases. Both of them decreased obviously for the blends with PES matrix. On the other hand, Tg of PPS and PES phase decreased a little when PPS is the continuous phase. In the blends quenched from molten state the cold crystallization temperature of PPS was detected in the blends of PES/PPS with mass ratio 50/50 and 60/40. The melting point, crystallization temperature and the crystallinity of blended PPS were nearly unaffected when the mass ratio of PES was less than 60%, however, when the amount of PES is over 60% in the blends, the crystallization of PPS chains was hindered. The thermal and the dynamic mechanical properties of the PPS/PES blends were mainly controlled by the continued phase.

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Abstract  

Serials of halloysite nanotubes/polystyrene (HNTs/PS) nanocomposites with different contents of organo-modified halloysite nanotubes (organo-HNTs) were successfully prepared by the in situ bulk polymerization of styrene with the organo-HNTs as macromonomers. The percentage of grafting (PG%) of more than 230% was achieved, calculated from the results of the thermogravimetric analysis (TG). The TG results also showed that the thermal stabilities of the HNTs/PS nanocomposites prepared via the bulk polymerization were better than the pure polystyrene. And the maximum thermal degradation temperature of the nanocomposites increased with the increasing of the amount of the HNTs fillers added.

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Stripe rust, caused by Puccinia striiformis f. sp. tritici (PST), is one of the most serious diseases of wheat ( Triticum aestivum L.) worldwide. Of 94 Triticum durum/Aegilops tauschii synthetic wheat accessions tested, CI142 (Garza/Boy// Ae. squarrosa 271) was found to be resistant to 6 Chinese PST races. The resistance to stripe rust in CI142 was proven to be controlled by a single dominant gene, tentatively designated YrC142 . Gene postulation showed that the pathogenic specificity of CI142 is different from 21 other lines possessing known resistance genes, such as Yr10, Yr15, Yr24 , and Yr26 , located on chromosome 1B. Bulked segregant analysis (BSA) and F 2 segregation analysis of the CI142/Mingxian 169 cross were used to analyse the SSR markers linked to YrC142 . Five SSR markers were found to be closely associated with YrC142 in the order Xwmc419-YrC142-Xgwm273, Xbarc187-Xgwm18-Xwmc626 , in which the relative genetic distances of these SSR loci to the gene YrC142 were 5.4, 0.8, 0.8, 1.0, and 2.4 cM, respectively. Two SSR markers ( Xgwm273 −162 and Xgwm18 −168 ) distinguished YrC142 from Yr10, Yr15, Yr24 , and Yr26 , suggesting that these 2 SSR markers may be used as diagnostic ones for the gene in a wheat breeding program against stripe rust. Based on these findings, YrC142 is most likely a new gene or a new allele at the Yr26 locus, which provides an opportunity to diversify stripe rust-resistant resources for wheat breeding programs.

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Abstract  

In this work some calorimetric measurements were also carried out on the electrorefining silver by using different current densities with a Calvet type microcalorimeter at room temperature. The ratio (R) of the measured heat (

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m) to the input electric energy (
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in) and the excess heat (
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ex), i.e., difference between
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m and
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in during the electrorefining process, were discussed in terms of general thermodynamics. It was found that the R and
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ex for silver were related with the current density or cell voltage employed in the experiment. The results obtained here also indicate that the heat generation under different conditions, such as different currents or voltages may be caused partially by the irreversibility of the process or by some unknown processes.

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The essential oil extracted from Nardostachys chinensis Batal (NCB) was analyzed by gas chromatography-mass spectrometry (GC-MS) combined with two chemometric resolution methods (CRM), heuristic evolving latent projections (HELP), and selective ion analysis (SIA). Qualitative analysis was performed by comparing the obtained pure mass spectra with those in National Institute of Standards and Technology (NIST) mass spectra database. Identification of some compounds was assisted by comparison of programmed temperature retention indices (PTRIs). The quantitative results were obtained by overall volume integration (OVI). A total of 69 compounds in the essential oil of N. chinensis Batal were identified, accounting for 93.98% of the total content. The major compounds were (−)-spathulenol, epiglobulol, trans-longipinocarveol, and patchouli alcohol which contribute to the antimicrobial and antioxidant activity. The results showed that the efficiency and reliability were greatly improved by use of chemometric techniques and programmed temperature retention index as assistants of GC-MS in identification of the plant essential oil.

Open access

Abstract  

A microcalorimetric technique based on the bacterial heat-output was explored to evaluate the effect of Mn(II) on Bacillus thuringiensis. The power-time curves of the growth metabolism of B. thuringiensis and the effect of Mn(II) on it were studied using an LKB-2277 BioActivity Monitor, ampoules method, at 28C. For evaluation of the results, the maximum peak-heat output power (P max) in the growth phase, the growth rate constants (k), the log phase heat effects (Q log ), and the total heat effect in 23 h (Q T) for B. thuringiensis were determined. Manganese has been regarded as the essential biological trace element. Mn(II) of different concentration have different effects on B. thuringiensis growth metabolism. High concentration (800-1600 μg mL-1) of Mn(II) can promote the growth of B. thuringiensis; low concentration (500-800 μg mL-1) can inhabit its growth.

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Thioacetamide (TAA) is a potent hepatotoxicant in acute and chronic hepatic injury. The study examined the protective effect of sesame oil against TAA-induced hepatic injury in rats. Hepatic injury was induced by intraperitoneal injection of 100 mg/kg of TAA for 24 h. Triple doses of sesame oil (1, 2, or 4 mL/kg) was given orally 0, 6, and 12 h after TAA treatment. TAA significantly increased serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. Sesame oil decreased serum AST and ALT levels and significantly inhibited hepatic lipid peroxidation and nitric oxide levels compared with TAA-alone group. Further, sesame oil significantly inhibited TAA-induced hepatic neutrophil activation marker myeloperoxidase activity. However, sesame oil did not affect hepatic tumor necrosis factor, IL-1β and IL-10 generation in TAA-treated group. In conclusion, sesame oil protects against TAA-induced hepatic injury and oxidative stress via the inhibition of neutrophil activation. However, inflammatory cytokines may not be involved in sesame-oil-associated hepatic protection against TAA in rats.

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Abstract  

The concentrations of ten trace and dopant elements in GaAs semiconductor were determined by reactor neutron activation analysis after removal of As by evaporation of AsCl3. The retentions of the elements of interest were measured using radiotracers. The concentrations of doping elements (Te, Cr and Zn) in commercial GaAs samples were compared to the limit of detection of these elements to analyze the possibility to use NAA for concentration depth profiling measurements. The NAA results were compared with those of electrical measurements and SIMS and the discrepancies found are discussed.

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