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  • Author or Editor: G. Zhang x
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Abstract  

In an ongoing effort to understand the thermodynamic properties of proteins, ovalbumin, lactoglobulin, lysozyme are studied by adiabatic and differential scanning calorimetry over wide temperature ranges. The heat capacities of the samples in their pure, solid states are linked to an approximate vibrational spectrum with the ATHAS analysis that makes use of known group vibrations and a set of parameters, Θ1 and Θ3, of the Tarasov function for the skeletal vibrations. Good agreement is found between experiment and calculation with rms errors mostly within ±3%. The analyses were also carried out with an empirical addition scheme using data from polypeptides of naturally occurring amino acids. Due to space limitation, only selected results are reported.

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Chlorophyll content is positively correlated with photosynthetic rate. However, little is known about the genetic correlation between grain yield and chlorophyll content in the same wheat mapping population. The primary goal of the study was to detect the genetic basis of grain yield and chlorophyll content and their possible roles in the genetic improvement of grain yield in wheat. Here, quantitative trait loci (QTLs) for grain yield and chlorophyll content were studied using a set of 168 doubled haploid (DH) lines derived from a cross between two elite Chinese wheat cultivars, Huapei 3×Yumai 57. The DH population and parents were evaluated for grain yield and chlorophyll content in three environments. A total of 11 additive QTLs and 6 pairs of epistatic QTLs were detected for grain yield and chlorophyll content. Loci, such as Xcfd53, Xwmc718 , and Xwmc215 on chromosomes (e.g. 2D, 4A, and 5D) simultaneously controling grain yield and chlorophyll content, showed tight linkages or pleiotropisms. Three novel major QTLs, qGY5D, qChla5D , and qChlb5D , closely linked with the PCR marker Xwmc215 on chromosome 5D, accounted for 10.32%, 12.95%, and 23.29% of the phenotypic variance, respectively. The favorable alleles came from Yumai 57.

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Abstract  

The concept of crystallization dynamics method evaluating the miscibility of binary blend system including crystalline component was proposed. Three characteristic rates, nucleation, crystal growth rates (N*, G*) and growth rate of conformation (G c*) were used to evaluate the miscibility of PVDF/at-PMMA and PVDF/iso-PMMA by the simultaneous DSC-FTIR. N*, G* and G c* depended remarkably on both temperature and blend fraction (ϕPMMA) for PVDF/at-PMMA system, which indicated the miscible system. PVDF/iso-PMMA showed small ϕPMMA dependency of N*, G* and G c*, was estimated the immiscible system. The ΔT/T m 0 values, corresponding to Gibbs energy required to attend the constant G* and G c*, evaluated from G* and G c* showed the good linear relationships with different slope. The experimental results suggested that the concentration fluctuation existed in PVDF/iso-PMMA system.

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Abstract  

The crystallization dynamics of Nylon 66/Nylon 6 blends, the crystalline/crystalline polymer blends, was analyzed by DSC under isothermal conditions. The crystal growth rate (G) and the nucleation rate (N) depended on both the degree of supercooling (ΔT) and the blend mass fraction (ϕ). The ΔT /T m 0 values obtained at the fixed G, which corresponded to the chemical potential difference of molecules between liquid and crystal states, and the surface free energy parameters evaluated from G and N depended on ϕ for blends. The results suggested that Nylon 66/Nylon 6 blends with ϕN66≥0.80 or ϕN66≤0.15 are miscible.

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The relationship between plant communities and elevation in the Guandi mountainous area was studied. Data from 89 sampling units, each of 10 m x 20 m size, taken along an elevation gradient were analyzed by TWINSPAN, DECORANA and diversity and evenness indices. The samples were clustered into 23 groups by TWINSPAN, representing 23 vegetation types. The composition and distribution of communities varied greatly along the altitude gradient, suggesting that community diversity is closely related to elevation in the Guandi Mountains. This is due to the change of temperature and water-conditions along the elevation gradient. Species heterogeneity and evenness were significantly correlated with elevation along the entire gradient, but showing first a trend of increases and then decreases, corresponding to the hypothesis of maximum diversity at medium elevation. Species richness varied greatly in the study area, and was not significantly correlated with elevation.

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Abstract  

Highly oriented single crystal antimony nanowire arrays have been synthesized within anodic aluminum oxide (AAO) template by pulsed electrodeposition. Thermal behavior and oxidation analysis of the antimony nanowires have been investigated by means of thermogravimetry and differential scanning calorimetry in Ar and air atmosphere, respectively. Compared to bulk antimony, the antimony nanowires exhibit a lower sublimation temperature at 496.4°C. Evident oxidation of the Sb nanowires occurs at 429.8°C in air atmosphere and α-Sb2O4 nanowires have been obtained as the oxidation product. The results indicate that the sublimation and the oxidation of the antimony nanowires in the AAO template is a slow multi-step process. The present results are of relevance when processing antimony nanowries for thermoelectric applications at high temperatures.

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Abstract  

Thermal behaviors of two mixed-ligand complexes, [Ni(PMPP-SAL)(Py)3] and [Cu(PMPP-SAL)Py]·MeOH, (PMPP-SAL=1-phenyl-3-methyl-4-(salicylidene hydrazide)-propenylidene-pyrazolone-5, Py=pyridine), were studied by TG-DTG-DTA in dynamic air atmosphere. The complexes show the loss of pyridine molecule is followed by the decomposition of the PMPP-SAL anion and give respective metal oxides as residues. Meanwhile, the Ozawa-Flynn-Wall model-free analyses and multivariate non-linear regressions were applied to perform single and overall steps optimization. Kinetic parameters were given and the most probable mechanism functions were suggested in this study.

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Epimedium pubescens Maxim. and Epimedium koreanum Nakai. are two common and confused species of Herba Epimedii in Chinese Pharmacopoeia 2010 edition. Different species and growing conditions lead to chemical differences between the two species which may result in the improper clinical usage. In this work, a new method based on rapid-resolution liquid chromatography combined with time-of-flight mass spectrometry (RRLC/TOFMS) has been developed for identification and differentiation of major flavonoids in two kinds of Epimedium extract and rat plasma. The compounds were identified effectively based on the accurate extract masses and formulae acquired by RRLC/TOFMS. The fragmentation rules deduced by collision-induced dissociation (CID) were successfully implemented in distinguishing some of the isomers, further validating the results. By using the combined analytical techniques, a total of 40 major flavonoids in extracts of two kinds of Epimedium were identified within 30 min, including 31 common components and 9 characteristic components. After oral administration, three prototype compounds in rat plasma were detected by comparing the constituents measured in vitro with those in vivo, and five metabolites were identified by contrasting the fragmentation rules. The identification and structural elucidation of the chemical constituents provided essential data for further pharmacological and clinical studies on different species of Epimedium.

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Abstract  

The free-radical bulk polymerization of 2,2-dinitro-1-butyl-acrylate (DNBA) in the presence of 2,2′-azobisisobutyronitrile (AIBN) as the initiator was investigated by DSC in the non-isothermal mode. Kissinger and Ozawa methods were applied to determine the activation energy (E a) and the reaction order of free-radical polymerization. The results showed that the temperature of exothermic polymerization peaks increased with increasing the heating rate. The reaction order of non-isothermal polymerization of DNBA in the presence of AIBN is approximately 1. The average activation energy (92.91±1.88 kJ mol −1) obtained was smaller slightly than the value of E a=96.82 kJ mol−1 found with the Barrett method.

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Abstract  

2,2-dinitropropyl acrylate (DNPA), 2,2-dinitrobutyl acrylate (DNBA) and 2,2-dinitrobutyl methacrylate (DNBMA) were synthesized and the kinetics of their free-radical polymerization in the presence of 2,2′-azobisisobutyronitrile (AIBN) were investigated by DSC in the non-isothermal mode. The kinetics of the free-radical polymerization as estimated by the Kissinger and Ozawa methods showed that the reaction is disfavoured by increasing steric hindrance around the acrylyl double bond. The rate constants calculated from the activation parameters showed the structural dependency. The polymerization kinetics revealed that the polymerizability of three monomers decreased due to the presence of substituent methyl groups on the acrylyl double bond and 2,2-dinitrobutyl on ester group. Thus, the polymerization tendency increased in the order DNPA>DNBA>DNBMA.

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