Authors:S. Qiu, H. Chu, J. Zhang, Y. Qi, L. Sun, and F. Xu
The low-temperature molar heat capacities of CoPc and CoTMPP were measured by temperature modulated differential scanning
calorimetry (TMDSC) over the temperature range from 223 to 413 K for the first time. No phase transition or thermal anomaly
was observed in the experimental temperature range for CoPc. However, a structural change was found to be nonreversible for
CoTMPP in the temperature range of 368–403 K, which was further validated by the results of IR and XRD. The molar enthalpy
ΔHm and entropy ΔSm of phase transition of the CoTMPP were determined to be 3.301 kJ mol−1 and 8.596 J K−1 mol−1, respectively. The thermodynamic parameters of CoPc and CoTMPP such as entropy and enthalpy relative to reference temperature
298.15 K were derived based on the above molar heat capacity data. Moreover, the thermal stability of these two compounds
was further investigated through TG measurements. Three steps of mass loss were observed in the TG curve for CoPc and five
steps for CoTMPP.
Authors:F. Tian, L. Sun, S. C. Mojumdar, J. E. S. Venart, and R. C. Prasad
The transient hot-wire method is considered the most accurate technique to measure the thermal conductivity of fluids. In this study, a transient hot wire instrument which employs 25.4-μm-diameter tantalum wire with an insulating tantalum pentoxide coating has been used. This hot-wire cell with a thin insulating layer is suitable for measurement of the thermal conductivity of electrically conducting and polar liquids. Measurements of the thermal conductivity of 50 wt% solution of PAA [poly (acrylic acid)] in water and PAA–Na in 50 wt% water are reported here. These measurements were obtained in the temperature range of 299–368 K at 1 atmospheric pressure. The measurement of thermal conductivity is estimated to be accurate within ±4%.
Authors:F. Xu, L. Sun, Z. Tan, X. Lan, P. Yu, and T. Zhang
The heat capacities of berberine sulphate [(C20H18NO4)2SO43H2O] were measured from 80 to 390 K by means of an automated adiabatic calorimeter. Smoothed heat capacities, HT-H298.15 and ST-S298.15 were calculated. The loss of crystalline water started at about 339.30.2 K, and its peak temperature was 365.80.6 K. The
peak temperature of decomposition for berberine sulphate was at about 391.40.4 K by DSC curve. TG-DTG analysis of this material
was carried out in temperature range from 310 to 970 K. TG and DSC curves show that there is no melting in the whole heating
Authors:L. Tian, N. Ren, J. Zhang, H. Liu, S. Sun, H. Ye, and K. Wu
The two complexes of [Ln(CA)3bipy]2 (Ln = Tb and Dy; CA = cinnamate; bipy = 2,2′-bipyridine) were prepared and characterized by elemental analysis, infrared
spectra, ultraviolet spectra, thermogravimetry and differential thermogravimetry techniques. The thermal decomposition behaviors
of the two complexes under a static air atmosphere can be discussed by thermogravimetry and differential thermogravimetry
and infrared spectra techniques. The non-isothermal kinetics was investigated by using a double equal-double steps method,
the nonlinear integral isoconversional method and the Starink method. The mechanism functions of the first decomposition step
of the two complexes were determined. The thermodynamic parameters (ΔH≠, ΔG≠ and ΔS≠) and kinetic parameters (activation energy E and the pre-exponential factor A) of the two complexes were also calculated.
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:D. Wang, A. Bai, X. Lin, L. Fang, X. Shu, X. Shi, Q. Sun, and X. Wang
Supercritical fluid extraction (SFE) was used to extract shionone from Aster tataricus L. f. The effect of various parameters, i.e., temperature, pressure and sample particle size on yield was investigated with an analytical-scale SFE system to find the optimal conditions. The process was then scaled up by 50 times with a preparative SFE system under the optimized conditions of temperature 40 °C, pressure 30 MPa, and a sample particle size of 40–60 mesh. Then preparative high-speed counter-current chromatography was successfully used for isolation and purification of shionone from the SFE extract with a two-phase solvent system composed of n-hexane-methanol (2:1, volume ratio). The separation produced a total of 75 mg of shionone from 500 mg of the crude extract in one step separation with the purity of 98.7%, respectively, as determined by high-performance liquid chromatography (HPLC) and 92% recovery. The structure of shionone was identified by electrospray ionization-mass spectrometry (ESI-MS), hydrogen-1 nuclear magnetic resonance (1H-NMR), and carbon-13 nuclear magnetic resonance (13C-NMR).
Authors:B. Liu, Z. Tan, Z. Nan, P. Liu, L. Sun, F. Xu, and X. Lan
A solid complex of rare-earth compounds with alanine, [ErY(Ala)4(H2O)8](ClO4)6 (Ala=alanine), was synthesized, and a calorimetric study and thermal analysis for it was performed through adiabatic calorimetry
and thermogravimetry. The low-temperature heat capacity of [ErY(Ala)4(H2O)8](ClO4)6 was measured with an automated adiabatic precision calorimeter over the temperature range from 78 to 377 K. A solid-solid
phase transition was found between 99 and 121 K with a peak temperature at 115.78 k. The enthalpy and entropy of the phase
transition was determined to be 1.957 Kj mol-1, 16.90 j mol-1 k-1, respectively. Thermal decomposition of the complex was investigated in the temperature range of 40~550C by use of the thermogravimetric
and differential thermogravimetric (TG/DTG) analysis techniques. The TG/DTG curves showed that the decomposition started from
120 and ended at 430C, completed in three steps. A possible mechanism of the thermal decomposition was elucidated.
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:Chien C. Lin, C. F. Wang, Y.C. Sun, J. H. Chao, and C. L. Tseng
experiments have been carried out to investigate the effects of gamma-radiation
on iodine aerosols under various chemical conditions. The results indicate that
iodide ions (I-) in aerosol can be readily oxidized to I2
and HIO, and some iodide ions may be converted to organic iodine when organic
additives are present in the KI solution from which the aerosol is generated.
The results also suggest that the chemical transformation of irradiated iodine
aerosol depends on the chemical environment both carrier gas and iodide