Authors:J. Zeng, Z. Cao, D. Yang, F. Xu, L. Sun, L. Zhang, and X. Zhang
A series of PA-TD mixtures were prepared and their thermal properties were studied by DSC and thermal conductivity measurement.
The phase diagram of the binary system was constructed, which showed an eutectic behavior for the solid-liquid equilibrium
line. The eutectic composition of the binary system was at the mass fraction of TD near 0.7 with an eutectic temperature of
about 29°C. At TD side, PA was partially miscible in the TD solid matrix and the solid phase transition of TD had an effect
on the solidus line. The eutectic composition mixture could be viewed as a new phase change material with large thermal energy
Authors:B. Xue, X. Li, J. Wang, S. Yu, Z. Tan, and L. Sun
The heat capacities of trans-(R)-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid in the temperature range from 78 to 389 K were measured
with a precise automatic adiabatic calorimeter. The sample was prepared with the purity of 0.9874 mole fraction. A solid-liquid
fusion phase transition was observed in the experimental temperature range. The melting point, Tm, enthalpy and entropy of fusion, ΔfusHm, ΔfusSm, were determined to be 344.75±0.02 K, 13.75±0.07 kJ mol−1, 39.88±0.21 J K−1 mol−1, respectively. The thermodynamic functions of the sample, H(T)-H(298.15), S(T)-S(298.15) and G(T)-G(298.15), were reported with a temperature interval of 5 K. The thermal decomposition of the sample was studied by TG analysis, the
thermal decomposition starts at ca. 421 K and terminates at ca. 535 K, the maximum decomposition rate was obtained at 525
K. The order of reaction, pre-exponential factor and activation energy, are n=0.14, A=1.15·108 min−1, E=66.27 kJ mol−1, respectively.
Authors:J. Sun, J. Lu, X. Zhu, K. Zhang, Z. Lu, and J. Zhu
Polyacrylamide (PAM), poly(N,N-dimethylacrylamide) (PDMA) and poly(N,N-diethylacryl-amide) (PDEA) were synthesized by plasma-initiated polymerization. Both wet and dry polymers were prepared. The states of the water absorbed in the wet and dry samples were studied directly by means of TG, and the stabilities of the dry polymers in the process of thermal treatment were investigated by FT-IR. The activation energy of release of the bonded water was calculated by the Kissinger method. The water absorbed in the polymers was found to be in two states, i.e. weakly-bonded water and bonded water, and the absorbed water content varied with the monomer concentration, the plasma duration time and the type of polymer.
Authors:H. Yang, N. Tan, F. WU, H. Liu, M. Sun, Z. She, and Y. Lin
The uranium(VI) accumulation was studied in detail by using the biomass of mangrove endophytic fungus Fusarium sp.#ZZF51 from the South China Sea. The uranium(VI) biosorption process onto the tested fungus powders was optimized at pH 4.0,
adsorption time 60 min, and uranium(VI) initial concentration 50 mg L−1 with 61.89% of removal efficiency. According to Fourier transform infrared spectra for the tested fungus before and after
loaded with uranium(VI), the results showed that both of hydroxyl and carboxyl groups acted as the important roles in the
adsorption process. In addition, the experimental data were analyzed by using parameter and kinetic models, and it was obtained
that the Langmuir isotherm model and the pseudo-second-order kinetic model provided better correlation with the experimental
data for adsorption of uranium(VI).
Authors:Z.-D. Nan, Y. Xiang, X.-C. Zeng, H.-L. Zhang, and H.-T. Sun
The power-time curves of the growth of three strains of petroleum bacteria at different temperatures have been determined. A novel equation of a power-time curve has been proposed in this paper. The general formula to calculate the rate constant of the bacterial growth has been derived. The rate constants of the bacterial growth at different temperatures, the heat production per newly formed bacterium, the bacterial number at the end of the bacterial growth and the deceleration rate constant of the bacterial growth at 50.00°C, have been calculated. The optimum growth temperatures of the three strains have been obtained.
Authors:J. Wang, L. Huang, H. Ren, Z. Sun, and Q. Guo
Soil seed banks can act as an important source in forest regeneration, and the information on the seed bank composition is vital for determining the resilience of plant communities under severe environments such as urban settings. In this study, we examined the seed bank density and functional composition, and their relationships with aboveground vegetation in three remnant evergreen broad-leaved forests, i.e., PuGang (PG), LuoGang (LG), and DaLingShan (DLS) under urbanization in Guangzhou, South China. In both years of our study (2010–2011), seed density and species richness for overall soil seed banks and each classified life forms (tree, shrub, herb and grass) significantly differed among the forests and were much higher in the PG forest. The prevailing life forms in the seed banks were herbs and grasses, and the proportion of tree species Importance Value index (IV) of the seed banks was low. We did not detect significant difference in the percentage of exotic species seeds in the seed banks among the forests. The proportion of species with animal dispersal mode was much higher in the DLS forest than in the PG and LG forests. The similarity in species composition between standing vegetation and seed banks was low with the lower value in the DLS forest than in PG and LG forest. Our findings suggest that the regeneration potential of the soil seed banks is limited for the remnant forests in urban areas. Therefore, greater proactive and enhanced conservation efforts are thus needed.
Authors:Z. Deng, J. Tian, J. Chen, C. Sun, Y. Zhang, and Y. Wang
wheat is unique to China and has been improved by introducing good germplasm. In order to clear the subunits background of
wheat, sodium dodecyl sulphate polyacrylamide-gel electrophoresis (SDS-PAGE) was used to detect the high and low molecular weight glutenin subunits (HMW-GS and LMW-GS) compositions in BC1F1, F2 and F3 generations from
wheat. Twenty-five alleles and 49 HMW-GS compositions at the
loci were detected in different generations. Null and subunit 1 were mainly existed at
, and 7 + 8 and 7 + 9 were primarily detected at
in different generations. Subunit combination 5 + 10 mainly appeared in BC1F1, while 2 + 12 major presented in F2 and F3 generations. HMW-GS compositions null, 7 + 8, 5 + 10 and null, 7 + 9, 5 + 10 showed higher frequencies than other banding patterns, followed by null, 14 + 15, 5 + 10 and null, 7 + 9, 2 + 12 combinations. In addition, some rare subunit combinations such as 14 + 15, 13 + 16, 17 + 18, 4 + 12, 2 + 10 and 5 + 12 were found in different generations. Eighteen alleles and 51 LMW-GS compositions at
loci were found in different generations.
d showed higher frequencies than others among three generations. There were mainly a, b, c alleles at
. Thirty, 31 and 14 different combinations were detected in BC1F1, F2 and F3 populations, respectively. There were some good combinations such as
a for different quality characteristics. So some desirable subunit combinations could be selected from different generations and new cultivars with good quality under distinct subunits background should be bred from
wheat in future.
Authors:S. Wang, Z. Tan, Y. Di, F. Xu, M. Wang, L. Sun, and T. Zhang
As one primary component of Vitamin B3, nicotinic acid [pyridine 3-carboxylic acid] was synthesized, and calorimetric study and thermal analysis for this compound
were performed. The low-temperature heat capacity of nicotinic acid was measured with a precise automated adiabatic calorimeter
over the temperature rang from 79 to 368 K. No thermal anomaly or phase transition was observed in this temperature range.
A solid-to-solid transition at Ttrs=451.4 K, a solid-to-liquid transition at Tfus=509.1 K and a thermal decomposition at Td=538.8 K were found through the DSC and TG-DTG techniques. The molar enthalpies of these transitions were determined to be
ΔtrsHm=0.81 kJ mol-1, ΔfusHm=27.57 kJ mol-1 and ΔdHm=62.38 kJ mol-1, respectively, by the integrals of the peak areas of the DSC curves.
Authors:Y.-J. Song, S.-H. Meng, F.-D. Wang, C.-X. Sun, and Z.-C. Tan
Polyimide BTDA-ODA sample was prepared by polycondensation or step-growth polymerization method. Its low temperature heat capacities were measured by an adiabatic calorimeter in the temperature range between 80 and 400 K. No thermal anomaly was found in this temperature range. A DSC experiment was conducted in the temperature region from 373 to 673 K. There was not phase change or decomposition phenomena in this temperature range. However two glass transitions were found at 420.16 and 564.38 K. Corresponding heat capacity increments were 0.068 and 0.824 J g–1 K–1, respectively. To study the decomposition characteristics of BTDA-ODA, a TG experiment was carried out and it was found that this polyimide started to decompose at ca 673 K.
Optimization of extraction ratio (ER) of tree peony seed protein (TPSP) was investigated using response surface methodology (RSM). The second-degree equation for ER of TPSP had high coeffi cient (0.9625) of determination. The probability (P) value of regression model signifi cance was less than 0.001 by analysis of central composite rotatable design. Relationships of ER to pH, liquid/solid ratio, squares of all factors, and cross-product factors (x2x3, x2x4, x3x4) were signifi cant (P<0.05). Whereas, extraction time, temperature, and cross-product terms (x1x2, x1x3, x1x4) were not signifi cant factors (P>0.05). Optimum extraction conditions were 3.42 h, pH 9.50, 50.80 ºC, and 9.54 ml g–1 of liquid/solid ratio with the maximum ER (43.60%) . SDS-PAGE indicated TPSP had mainly four proteins (180, 100, 60, and 35 kDa) with four subunits of 60, 48, 38, and 23 kDa. TPSP had a good amino acid composition with abundant essential amino acids (39.76%) determined by amino acid analysis.