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  • Author or Editor: H. Gao x
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Abstract  

We have developed a thermogravimetric system (TG system) for condensable gas adsorption by modifying a standard thermogravimetric analyzer Cahn TG 2121 and performed isotherm measurements of water vapor adsorption on Fuji Davison type RD silica gel and ethanol vapor adsorption on Maxsorp II activated carbon. For the water vapor-silica gel data, our results compare favorably with the data reported by the manufacturer and those obtained from a volumetric method. This confirms the reliability of our TG system for adsorbents which do not swell significantly. In addition, our isotherm data also provide useful design information for the development of adsorption chillers.

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Abstract  

We show that a monotonically normal space X is paracompact if and only if for every increasing open cover {U α : α < κ} of X, there is a closed cover {F : n < ω, α < κ} of X such that F U α for n < ω, α < κ and F F if αβ.

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Among the progenies of crossing Triticum turgidum — Haynaldia villosa amphiploid with synthetic hexaploid wheat (T. carthlicum / Aegilops tauschii) Am3, two lines (SN030713 and SN05078), with good resistance to stripe rust and powdery mildew, were developed. Cytological studies demonstrated that SN030713 contained 42 chromosomes and formed 21 bivalents at meiotic metaphase I. SN05078 contained 28 chromosomes and formed 14 bivalents. Genomic in situ hybridization analysis using H. villosa V genomic DNA as the probe showed SN030713 and SN05078 had no large H. villosa chromosome fragments. PCR analysis with H. villosa specific primer pHv29 showed that H. villosa genetic materials were introgressed in these two lines. SSR analysis indicated that the genomic composition of SN030713 was 2n = 6x = 42 (AABBDD), and SN05078 was 2n = 4x = 28 (AABB). Introgressed Ae. tauschii genetic materials in SN05078 were also detected.

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Abstract  

A method for estimating the critical temperatures (T b) of thermal explosion for energetic materials is derived from Semenov’s thermal explosion theory and the non-isothermal kinetic equation dα/dt=A 0 T B f(α)e−E/RT using reasonable hypotheses. The final formula of calculating the value of T b is
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\left( {\frac{B} {{T_b }} + \frac{E} {{RT_b^2 }}} \right)$$ \end{document}
(T bT e0=1. The data needed for the method, E and T e0, can be obtained from analyses of the non-isothermal DSC curves. When B=0.5 the critical temperature (T b) of thermal explosion of azido-acetic-acid-2-(2-azido-acetoxy)-ethylester (EGBAA) is determined as 475.65 K.
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Extracts from lo-han-kuo (Siraitia grosvenorii) are of high sweetness and low calories, and they have been widely used as a natural sweetener to reduce the risk of obesity and diabetes. In the current study, lo-han-kuo extracts were extracted using subcritical water under different operation condition. The study revealed that the optimal extracting parameters were: extraction time of 20 min, extraction temperature of 140 °C, and the addition of 15% ethanol. Antioxidant activity, contents of total flavonoids, and total phenolic compounds of lo-han-kuo extracts were also investigated. A mathematical model was established to describe the relationship between antioxidant capacity and content of bioactive components in lo-han-kuo extract, and it was found that antioxidant capacity of the extracts was mainly attributed to the yields of total mogrosides (P<0.05).

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Abstract  

The curing kinetics of a bi-component system about o-cresol-formaldehyde epoxy resin (o-CFER) modified by liquid crystalline p-phenylene di[4-(2,3-epoxypropyl) benzoate] (p-PEPB), with 3-methyl-tetrahydrophthalic anhydride (MeTHPA) as a curing agent, were studied by non-isothermal differential scanning calorimetry (DSC) method. The relationship between apparent activation energy E a and the conversion α was obtained by the isoconversional method of Ozawa. The reaction molecular mechanism was proposed. The results show that the values of E a in the initial stage are higher than other time, and E a tend to decrease slightly with the reaction processing. There is a phase separation in the cure process with LC phase formation. These curing reactions can be described by the Šesták–Berggren (S–B) equation, the kinetic equation of cure reaction as follows:
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $${\frac{{{\text{d}}\alpha }}{{{\text{d}}t}}} = A\exp \left( { - {\frac{{E_{\text{a}} }}{RT}}} \right)\alpha^{m} \left( {1 - a} \right)^{n}$$ \end{document}
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Polyphenols in Chinese Kushui rose (Rosa sertata × Rosa rugosa) leaves were first extracted and analysed in this study. Among four fractions (ethyl ether, ethyl acetate, n-butanol, and water layer) of crude extracts, the ethyl acetate fraction showed the highest ABTS•+ scavenging activity, and the n-butanol fraction exhibited the maximum components in composition. On-line HPLC-ABTS•+ analysis indicated that there were more than 30 antioxidant compounds from Chinese Kushui rose leaves. The identified polyphenols could be classified into quercetin derivatives, gallic acid derivatives, and proanthocyanidins. Gallic acid was the most antioxidative compound.

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Abstract  

Nano-ZnO flakes were synthesized by calcination of the precursor of Zn(OH)2 obtained via the reactive ion exchange method between an ion exchange resin and ZnSO4 solution at room temperature. Scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscope, UV-Vis diffuse reflection spectrum and Na2EDTA titration were used to characterize the structure features and chemical compositions of the as-prepared ZnO. The results show that the as-prepared ZnO flakes have uniform structure and high purity. Heat capacities in the temperature range of 83 to 396 K were measured. The measured heat capacities values were compared with those of coarse crystal powders and the difference between this two heat capacity curves was analyzed.

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Abstract  

Both calorimetric determination of displacement adsorption enthalpies ΔH and measurement of adsorbed amounts of lysozyme (Lyz) denatured by 1.8 mol L−1 guanidine hydrochloride (GuHCl) on a moderately hydrophobic packings at 298 K, pH 7.0 and various salt concentrations were carried out. Based on the thermodynamics of stoichiometric displacement theory (SDT) the fractions of thermodynamic functions, which related to four subprocesses of denatured protein refolding on the surface, were calculated and thermodynamic analysis that which one of the subprocesses plays major role for contribution to the thermodynamic fractions was made in detail. The moderately hydrophobic surface can provide denatured Lyz energy and make it gain more conformation with surface coverage or salt concentration increment. The displacement adsorptions of denatured Lyz onto PEG-600 surface are exothermic, more structure-ordered and enthalpy driven processes.

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