Search Results

You are looking at 1 - 10 of 52 items for

  • Author or Editor: Y. Hu x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

We prove that the centered three-dimensional Wiener sausage can be strongly approximated by a one-dimensional Brownian motion running at a suitable time clock. The strong approximation gives all possible laws of iterated logarithm as well as the convergence in law in terms of process for the normalized Wiener sausage. The proof relies on Le Gall [10]șs fine L 2-norm estimates between the Wiener sausage and the Brownian intersection local times.

Restricted access

Abstract  

The kinetics of the first order autocatalytic decomposition reaction of highly nitrated nitrocellulose (HNNC, 14.14%N) was studied by using thermogravimetry (TG). The results show that the TG curve for the initial 50% of mass-loss of HNNC can be described by the first order autocatalytic equation

\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} $$\frac{{{\text{d}}y}}{{dt}} = - 10^{16.4} \exp \left( { - \frac{{210380}}{{RT}}} \right)y - 10^{16.7} \exp \left( { - \frac{{171205}}{{RT}}} \right)y(1 - y)$$ \end{document}
and that for the latter 50% mass-loss of HNNC described by the reaction equations
\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} $$\frac{{dy}}{{dy}} = - 10^{16.3} \exp \left( { - \frac{{169483}}{{RT}}} \right)y\quad (n = 1)$$ \end{document}
and
\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} $$\frac{{dy}}{{dt}} = - 10^{16.8} \exp \left( { - \frac{{165597}}{{RT}}} \right)y^{2.61} \quad (n \ne 1)$$ \end{document}

Restricted access

Abstract  

To obtain a biodegradable polymer material with satisfactory thermal properties, higher elongation and modulus of elasticity, a new copolyester, poly(hexylene terephthalate-co-lactide) (PHTL), was synthesized via direct polycondensation from terephthaloyl dichloride, 1,6-hexanediol and oligo(lactic acid). The resulting copolyesters were characterized by proton nuclear magnetic resonance (1H NMR), differential scanning calorimetry (DSC), thermogravimetry (TG) and wide-angle X-ray scattering (WAXS). By using the relative integral areas of the dyad peaks in 1H NMR spectrum of copolyesters PHTL, the sequence lengths of the hexylene terephthalate and lactide units in the resultant copolyesters are 3.5 and 1.5, respectively. Compared to poly(hexylene terephthalate) (PHT), PHTL has lower T m but higher T g due to the incorporation of lactide unit into the main chains of copolyesters. The degradation test of copolyesters under a physiological condition shows that the degradability of PHTL is sped up due to incorporation of lactide segments.

Restricted access

Biofortifying food crops with essential minerals would help to alleviate mineral deficiencies in humans. Detection of quantitative trait loci (QTLs) for mineral nutrient contents in rice was conducted using backcross inbred lines derived from an interspecific cross of Oryza sativa × O. rufipogon. The population was grown in Hangzhou and Lingshui, with the contents of Mg, Zn, Fe, Mn, Cu and Se in brown rice measured in both trials and that in milled rice tested in Hangzhou only. A total of 24 QTLs for mineral element contents were identified, including two for both the brown and milled rice, 17 for brown rice only, and five for milled rice only. All the seven QTLs detected for the mineral contents in milled rice and 13 of the 19 QTLs for the contents in brown rice had the enhancing alleles derived from O. rufipogon. Fifteen QTLs were clustered in seven chromosomal regions, indicating that common genetic-physiological mechanisms were involved for different mineral nutrients and the beneficial alleles could be utilized to improve grain nutritional quality by markerassisted selection.

Restricted access

A comparative proteomic analysis of grain proteins during five grain developmental stages of wheat cultivar Chinese Spring (CS) and its 1Sl/1B substitution line CS-1Sl(1B) was carried out in the current study. A total of 78 differentially expressed protein (DEP) spots with at least 2-fold expression difference were detected by two-dimensional electrophoresis (2-DE). Among these, 73 protein spots representing 55 differentially expressed proteins (DEPs) were successfully identified by matrix-assisted laser desorption/ionization time-offlight tandem mass spectrometry (MALDI-TOF/TOF-MS). Differential protein spots between the two genotypes were analyzed by cluster software, which revealed significant proteome differences. There were 39 common spots (including 33 DEPs) that showed significant difference between the two lines across five grain developmental stages, of which 14 DEP spots (including 11 DEPs) were mainly involved in carbohydrate metabolism that were encoded by the genes on 1B chromosome while 25 DEP spots (including 12 DEPs) were mainly related to stress response and gluten quality that were encoded by 1S1 chromosome. These results indicated that the Sl genome harbors more stress and quality related genes that are potential valuable for improving wheat stress resistance and product quality.

Restricted access

Rht18, derived from Triticum durum (tetraploid) wheat, is classified as a gibberellic acid (GA)-responsive dwarfing gene. Prior to this study, the responses of Rht18 to exogenous GA on agronomic traits in hexaploid wheat were still unknown. The response of Rht18 to exogenous GA3 on coleoptile length, plant height, yield components and other agronomic traits were investigated using F4:5 and F5:6 hexaploid dwarf lines with Rht18 derived from two crosses between the tetraploid donor Icaro and tall Chinese winter wheat cultivars, Xifeng 20 and Jinmai 47. Applications of exogenous GA3 significantly increased coleoptile length in both lines and their tall parents. Plant height was significantly increased by 21.3 and 10.7% in the GA3-treated dwarf lines of Xifeng 20 and Jinmai 47, respectively. Compared to the untreated dwarf lines, the partitioning of dry matter to ears at anthesis was significantly decreased while the partitioning of dry matter to stems was significantly increased in the GA3-treated dwarf lines. There were no obvious changes in plant height and dry matter partitioning in the GA3-treated tall parents. Exogenous GA3 significantly decreased grain number spike–1 while it increased 1000-kernel weight in both the dwarf lines and tall parents. Thus, applications of exogenous GA3 restored plant height and other agronomic traits of Rht18 dwarf lines to the levels of the tall parents. This study indicated that Rht18 dwarf mutants are GA-deficient lines with impaired GA biosynthesis.

Restricted access

Abstract  

This research investigated the influence of binary solutions of benzene and methanol for their vapor flammability characteristics. The different mixing ratios (100/0, 75/25, 50/50, 25/75 and 0/100 vol%) samples were injected into a 20-liter spherical explosion vessel under various initial temperatures (100, 150 and 200C) to study their flammability behaviors. According to the experimental results, the flammability diagram of mixtures can be completely illustrated and combined with specific safety-related properties such as lower explosion limit (LEL), upper explosion limit (UEL), minimum oxygen concentration (MOC), maximum explosion overpressure (P max), and gas or vapor deflagration index (K g). The experimental results showed that the UEL, P max and K g all increased with the temperature, pressure and oxygen concentration, whereas there was no significant variation on the part of LEL. The results can provide specific information on fire and explosion hazards for related industries.

Restricted access

Abstract  

Two methods for estimating the critical temperature (T b) of thermal explosion for the highly nitrated nitrocellulose (HNNC) are derived from the Semenov's thermal explosion theory and two non-isothermal kinetic equations, d/dt=Af()e–E/RT and d/dt=Af()[1+E/(RT)(1–T o/T)]e–E/RT, using reasonable hypotheses. We can easily obtain the values of the thermal decomposition activation energy (E), the onset temperature (T e) and the initial temperature (T o) at which DSC curve deviates from the baseline of the non-isothermal DSC curve of HNNC, and then calculate the critical temperature (T b) of thermal explosion by the two derived formulae. The results obtained with the two methods for HNNC are in agreement to each other.

Restricted access