Search Results

You are looking at 31 - 40 of 54 items for

  • Author or Editor: B. Li x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

The thermal decomposition of Eu2(BA)6(bipy)2 (BA=C2H5N 2, benzoate; bipy=C10H8N2, 2,2'-bipyridine)and its kinetics were studied under the non-isothermal condition by TG-DTG, IR and SEM methods. The kinetic parameters were obtained from analysis of the TG-DTG curves by the Achar method, the Madhusudanan-Krishnan-Ninan (MKN) method, the Ozawa method and the Kissinger method. The most probable mechanism function was suggested by comparing the kinetic parameters. The kinetic equation for the first stage can be expressed as: dα/dt=Aexp(–E/RT)3(1–α)2/3.

Restricted access

Saccharomyces cerevisiae MERIT.ferm was used as mono- and mixed-cultures with Williopsis saturnus var. mrakii NCYC500 in mango wine fermentation. A ratio of 1:1000 (Saccharomyces:Williopsis) was chosen for mixed-culture fermentation to enable longer persistence of the latter. The monoculture of S. cerevisiae and mixed-culture was able to ferment to dryness with 7.0% and 7.7% ethanol, respectively. The monoculture of W. mrakii produced 1.45% ethanol. The mango wines fermented by S. cerevisiae alone and the mixed-culture were more yeasty and winey, which reflected their higher amounts of fusel alcohols, ethyl esters and medium-chain fatty acids. The mango wine fermented by W. mrakii alone was much less alcoholic, but fruitier, sweeter, which corresponded to its higher levels of acetate esters.

Restricted access

Abstract  

Antifreeze protein (AFP) can lower the freezing point by inhibiting the growth of ice crystals. In this article, the thermal hysteresis activity (THA) of a plant AFP was measured with differential scanning calorimetry (DSC). As is shown, when the amount of ice in the sample was less than 5% THA of this AFP reached as high as 0.35°C. The secondary structure of this AFP was studied with circular dichroism (CD). The CD spectrum from 195to 240 nm indicated a well-defined secondary structure consisting 11% α-helix, 34%antiparallel β-sheet and 55% random coil.

Restricted access

Abstract  

The low-temperature heat capacities of 1-hexadecanol have been measured with an automatic adiabatic calorimeter over the temperature range from 80 to 370 K. A solid-liquid phase transition was observed at T m=322.225±0.002 K and the molar enthalpy and entropy of fusion were determined to be 57.743±0.008 kJ mol−1 and 179.19±0.04 J K−1 mol−1, respectively. The purity, the real melting point (T 1) and the ideal melting point without any impurity or absolutely purity (T 0) of the sample under investigation were determined to be 99.162 mol%, 322.21 and 322.34 K, respectively, by fractional melting method. According to the polynomial equation of heat capacity and thermodynamic relationship, the thermodynamic functions of the compound relative to the reference temperature 298.15 K were calculated in the temperature ranges of 80 to 370 K with an interval of 5 K. In addition, further researches of thermal properties for this compound were carried out by means of TG/DTG.

Restricted access

Abstract  

Microcalorimetric measurements of the polymerization of actin in the presence of 100 mM KCl and 2 mM MgCl2were carried out with a Calvet MS-80 microcalorimeter at temperatures from 293.15 to 310.15 K. It was observed that the polymerization of actin was endothermic and the enthalpy change for actin polymerization was temperature-dependent. The enthalpy change ΔHowas fitted to ΔHo(kJ mol-1)=434.0-1.16 (T/K) and the change in heat capacity ΔCp ocalculated from ΔHowas -1.16 kJ (mol K)-1in the above range of temperatures. The direct calorimetry results showed that the enthalpy and entropy change for actin polymerization could not be obtained from measurements of the critical concentration and the only way to assess the enthalpy change for the polymerization of actin and similar reactions lies in the use of calorimetry.

Restricted access

Rice sheath blight, caused by Rhizoctonia solani, is the most serious disease in the southern rice producing regions of China. The use of resistant varieties is the most economic strategy to control the disease. In this paper, a seedling inoculation method was used to evaluate rice germplasm resources for resistance to sheath blight. A total of 363 rice varieties were evaluated with a set of R. solani isolates. The results indicated that the rice varieties generally lacked resistance to R. solani, and no highly resistant/immune (HR) variety was found. However, two varieties displayed clear resistance (R) and 37 showed moderate resistance (MR) to the fungus. Overall, hybrid rice varieties have better resistance than conventional rice varieties, and among hybrid rice varieties, those with the II-32A sterile line genetic background were the most resistant. The results also indicated significant interactions between rice varieties and pathogen isolates, suggesting that an understanding of local R. solani populations is needed when recommending varieties to local growers.

Restricted access

Abstract  

Two compounds of antimony trichloride and bismuth trichloride with valine are synthesized by solid phase synthesis at room temperature. Their compositions, determined by element analysis, are Sb(C5H10O2N)3·2H2O and Bi(C5H10O2N)2Cl·0.5H2O. The crystal structure of antimony complex with valine belongs to triclinic system and its lattice parameters are: a=0.9599 nm, b=1.5068 nm, c=1.9851 nm, α=92.270, β=95.050, γ=104.270. The crystal structure of bismuth complex with valine belongs to monoclinic system and its lattice parameters are: a=1.6012 nm, b=1.8941 nm, c=1.839 nm, β=99.73°. The far-infrared spectra and infrared spectra show that the amino group and carboxyl of valine may be coordinated to antimony and bismuth, respectively, in two compounds. The TG-DSC results also reveal that the complexes were formed.

Restricted access

We described the structure of two different morphological gall types, subglobular and fusiform in Ephedra distachya. The gall midge, Xerephedromyia ustjurtensis Fedotova (Diptera: Cecidomyiidae) induces both types of gall formation. Galls are persistent resinous stem swellings usually subglobular and rarely fusiform in shape. Mature galls are solid, hard, indehiscent woody structure with many circular exit holes on their surface. Galls are anatomically similar, but different from the unaffected stems. The mean number of larval cavities varied significantly between subglobular and fusiform galls, while variation of diameter of the larval cavities was not significant between the gall morphotypes. We documented significant (p < 0.05) variation in total gall densities between sexes of Ephedra distachya, where male plants (mean = 0.89 ± 0.15) supporting higher gall densities than females (mean = 0.36±0.04). Total gall densities varied significantly (p < 0.05) among three sample populations of E. distachya and exhibited an increasing trend from mesic to xeric sites along an altitudinal gradient. Gall size also varied between plant sexes and among sites.

Restricted access

Numerous studies showed that lipid transfer proteins (LTPs) play important roles in flower, development, cuticular wax deposition and pathogen responses; however, their roles in abiotic stresses are relatively less reported. This study characterized the function of a maize LTP gene (ZmLTP3) during drought stress. ZmLTP3 gene was transferred into maize inbred line Jing2416; subsequently the glyphosate and drought tolerance of the over-expression (OE) lines were analyzed. Analysis showed that OE lines could significantly enhance drought tolerance. Transgenic maize lines OE6, OE7 and OE8 showed lower cell membrane damage, higher chlorophyll contents, higher protective enzymes activities, better growth and development under drought condition. The results strongly indicated that overexpression of ZmLTP3 could increase drought tolerances in maize.

Restricted access