The molar heat capacity Cp,m of 1,2-cyclohexane dicarboxylic anhydride was measured in the temperature range from T=80 to 390 K with a small sample automated adiabatic calorimeter. The melting point Tm, the molar enthalpy ΔfusHm and the entropy ΔfusSm of fusion for the compound were determined to be 303.80 K, 14.71 kJ mol−1 and 48.43 J K−1 mol−1, respectively. The thermodynamic functions [HT-H273.15] and [ST-S273.15] were derived in the temperature range from T=80 to 385 K with temperature interval of 5 K. The thermal stability of the compound was investigated by differential scanning
calorimeter (DSC) and thermogravimetry (TG), when the process of the mass-loss was due to the evaporation, instead of its
Authors:H. Sun, X. Wang, Y. Liu, Z. Nan, and H. Zhang
In this paper studies on the oscillation regularity of the classical B–Z reaction system, and the calorimetric curves of the reaction system measured at three temperatures, 25, 27 and 29°C are described. A new way is presented for studying the regularity properties of chemical oscillation phenomena from the viewpoint of reaction heat effects.
The thermal decomposition studies for two palladium(II) complexes Pd(apyr)2Cl2 and Pd(pmpa)Cl2 (apyr=1–aminopyrene and pmpa=N–(2–pyridylmethylene)–1–pyrenylamine) were carried out in pure nitrogen using TG-DTG techniques. The non-isothermal kinetic parameters for the two complexes were evaluated employing the method suggested by Málek, esták, Koga et al. Based on the above results, thermal behaviour of the complexes were carefully discussed, which showed that not only the parameters value, but also the decomposition pattern and mechanism for complex 1 are different from complex 2.
Hydrated methanesulfonates Ln(CH3SO3)3nH2O (Ln=La, Ce, Pr, Nd and Yb) and Zn(CH3SO3)2nH2O were synthesized. The effect of atmosphere on thermal decomposition products of these methanesulfonates was investigated.
Thermal decomposition products in air atmosphere of these compounds were characterized by infrared spectrometry, the content
of metallic ion in thermal decomposition products were determined by complexometric titration. The results show that the thermal
decomposition atmosphere has evident effect on decomposition products of hydrated La(III), Pr(III) and Nd(III) methanesulfonates,
and no effect on that of hydrated Ce(III), Yb(III) and Zn(II) methanesulfonates.
To effectively extract organohalogens from human hair, two factors, the extracting time and hair length on the extraction
efficiency of organohalogens were studied by neutron activation analysis (NAA) and gas chromatograph-electron capture detector
(GC-ECD), respectively. Furthermore, the concentrations of extractable organohalogens (EOX) and extractable persistent organohalogens
(EPOX) in hair samples from angioma and control babies were also measured by the established method. The results indicated
that the optimal Soxhlet-extraction time for EOX and EPOX in hair was from 8 to 11 hours, and the extraction efficiencies
for organochlorine pesticides in hair were in the order of powder >2 mm>5 mm. Also, the mean levels of EOC1 and EPOC1 in hair
of the angioma babies were significantly higher than those in the control babies (PEOC1<0.01; PEPOC1<0.05), which implied the possible relationship between the environmental pollution and angioma.
Authors:Z. Lu, S. Chen, Y. Yu, J. Sun, and S. Xiang
Thermal behaviour of tri(O,O'-diisopropyldithiophosphate)cobalt(III), Co(dptp)3 and bis (O,O'-diethyldithiophosphate)nickel(II), Ni(detp)2 and its adducts with pyridine, Ni(detp)2(py)2 or 4-methylpyridine, Ni(detp)(mpy)2 in a dynamic nitrogen atmosphere was investigated by TG-DTG and DSC techniques, which showed a medium endothermic peak for
the evolution process of pyridine(or 4-methylpyridine) and a strong exothermic peak for that of O,O'-diethyldithiophosphate.
The thermal stability and decomposition patterns for these compounds were compared and interpreted in terms of structural
features such as bond character and steric effects. The kinetic parameters and mechanisms of every decomposition stage involved
for all these complexes were obtained employing the non-isothermal kinetic analysis method suggested by Malek et al., which
showed the kinetics mechanism for pyrolysis of pyridine(or 4-methylpyridine) is an S-B empirical model with lower activation
energy, while that of O,O'-dialkyldithiophosphate is a diffusion model. These results are in accord with the fact that two
ligands are of different type.
Authors:J. Zeng, Z. Cao, D. Yang, L. Sun, and L. Zhang
One of the greatest challenges in the application of organic phase change materials (PCMs) is to increase their thermal conductivity
while maintaining high phase change enthalpy. 1-Tetradecanol/Ag nanowires composite PCM containing 62.73 wt% (about 11.8 vol%)
of Ag nanowires showed remarkably high thermal conductivity (1.46 W m−1 K−1) and reasonably high phase change enthalpy (76.5 J g−1). This behavior was attributed to the high aspect ratio of Ag nanowires, few thermal conduct interfaces, and high interface
thermal conductivity of Ag nanowires in the composite PCM. These results indicated that Ag nanowires might be strong candidates
for thermal conductivity enhancement of organic PCMs.
Authors:Y. Sun, Q. Wang, S. Yang, G. Sheng, and Z. Guo
The nano-iron oxyhydroxides (α- and γ-FeOOH) were synthesized by using three ferrous and ferric salts (FeSO4, FeCl2, Fe(NO3)3) as iron precursors under alkaline conditions. Morphologies of nano-iron oxyhydroxides were characterized by employing X-ray
powder diffraction (XRD) and specific surface area (SSA) analysis respectively. The occurrence of needle-like shape of nano-goethite
and rod-like shape of nano-lepidocrocite were attributed to hydrolysis of Fe3+ cations and/or oxidization of Fe2+ at alkaline conditions in terms of XRD analysis. The N2-BET SSA and BJH (Barrett–Joyner–Halenda) pore size analysis showed that internal SSA of nano-lepidocrocite is higher than
that of nano-goethite, although they have similar N2-BET SSAs. The distribution of average pore size of nano-iron oxyhydroxides are higher than that of predominant pore size
due to formation of the heterogeneous nanoparticles under the experimental conditions. These nanoparticles possess the high
sorption capacity and the strong affinity for contaminants. Application of nano-iron oxyhydroxides in environmental engineering
plays an important role to remove a variety of contaminants, such as heavy-metal ions and organic pollutants.
Authors:Z. Sun, C. Segebade, D. Wells, and J. Green
Photon activation analysis (PAA) includes extensive data evaluation that is sensitive to error. In order to save time and
minimize human error, a new computer program—photon activation analysis system (PAAS)—was designed, built and implemented
using the SQL language and Asp.net technology to analyze PAA data. Given peak information from PAA spectra and aided by a
photonuclear data library, the program identifies the product isotopes, recognizes the possible nuclear reactions, and evaluates
the concentration of target elements. Uncertainties of concentrations are estimated using standard error propagation techniques.
The program can be accessed conveniently anywhere the internet is available and gives a fast and reliable determination of
the trace elemental content of samples. Furthermore, this program also allow one to search its database for the information
of general photonuclear reactions (e.g. energy lines, line intensities, target and product nuclides, photonuclear reactions,
cross sections, natural abundance, etc.) and estimating the activity even before the activation begins. By switching the nuclide
libraries, the program could also be expanded to neutron activation analysis and charged particle activation analysis (CPAA)
without any difficulty. This program can be a versatile tool for the daily use of the nuclear and radiochemistry laboratories
that conduct activation analysis.
Molar heat capacities
of acetaminophen were precisely measured with a small sample precision automated
adiabatic calorimeter over the temperature range from 80 to 330 K. A solid-solid
transition at 149.96 K was found from the Cp,m-T curve. The polynomial functions of Cp,.m(J
K-1 mol-1) vs. T were established
on the heat capacity measurements by means of the least square fitting method.
processes of acetaminophen have been studied by thermogravimetry. And the
thermal decomposition kinetics parameters, such as activation energy E, pre-exponential factor A
and reaction order n, were calculated by
TG-DTG techniques with the Freeman-Carroll method, Kissinger method
and Ozawa method. Accordingly the thermal decomposition kinetics equation
of acetaminophen is expressed as: dα/dt=2.67107e-89630/RT(1-α)0.23.
The process of fusion has been investigated through
DSC. The melting point, molar enthalpy and entropy of fusion are to be (441.890.04)
K, 26.490.44 kJ mol-1 and 59.801.01
J K-1 mol-1,