This paper presents calorimeter measurement for the thermal decomposition of n-propyl nitrate (NPN), isopropyl nitrate (IPN) and 2-ethylhexyl nitrate (EHN). Similar experimental results of triethylene
glycol dinitrate (tri-EGDN) and tetraethylene glycol dinitrate (tetra-EGDN) are included for comparison. The potential energy
surfaces (PESs) along O-NO2 bond stretch are investigated using the DFT (B3P86, B3PW91 and B3LYP), ab initio Hartree-Fock and PM3 methods. The good coincidence
of experimental with theoretical results indicates that initial stage in the thermal decomposition of five nitrates is only
unimolecular homolytical dissociation of the O-NO2 bonds and the activation energies of thermolysis by DSC correspond to the energies of O-NO2 bond scission of nitrates.
In our invention, FCC (fluid catalytic cracking) dry gas could be used to react with benzene without any special purification, and more than 90% ethylene was converted to ethylbenzene. The phenomenon of carbon deposition over catalyst surface was obvious and leads to a deactivation of catalyst, so it is important to study the behavior of carbon deposition of catalyst during alkylation of benzene. The influence of several factors such as temperature, reaction time, reactant concentration of the amount and the kinetics of carbon deposition were investigated, during which carbon depositing rate equations were obtained for different reactant.
Authors:L. Chen, W. Song, J. Lv, L. Wang, and C. Xie
Aluminum (Al) nanopowders with mean diameter of about 50 nm and passivated by alumina (Al2O3) coatings were prepared by an evaporation route: laser heating evaporation. Thermal properties of the nanopowders were investigated
by simultaneous thermogravimetric-differential thermal analysis (TG-DTA) in dry oxygen environment, using a series of heating
rates (5, 10, 20, 30, 50 and 90°C min−1) from room temperature to 1200°C. With the heating rates rise, the onset and peak temperatures of the oxidation rise, and
the conversion degree of Al to Al2O3 varies. However, the specific heat release keeps relatively invariant and has an average value of 18.1 kJ g−1. So the specific heat release is the intrinsic characteristic of Al nanopowders, which can represent the ability of energy
Authors:X. Chen, W. Feng, W. Miao, Y. Yu, Y. Shen, C. Wan, and J. Peng
The power-time curves of Tetrahymena thermophila exposed to tributyltin (TBT) were detected by microcalorimetry. Metabolic rate (r) decreased significantly while peak time
(PT) increased with the enhancement of TBT level. Compared with the measured multibiomarker including catalase, lactate dehydrogenase,
glutathione S-transferase, ATPase and membrane fluidity, PT and r could be sensitive biomarkers for assessing TBT toxicity at cellular level. The effective concentrations obtained by them
were consistent to those obtained by the protozoan community toxicity test. As a result, the microcalorimetric assay of T. thermophila had a great potential in assessing TBT acute toxicity and monitoring TBT pollution in the freshwater ecosystem.
Authors:Q. Chen, M. Cao, W. Xiang, Q. Sun, J. Zhang, R. Hou, Z. Yan, Z. Yang, J. Liu, and J. Zhao
The forward and reverse cDNA subtractive libraries before and after the toxic effect of α-amanitin were constructed by suppression subtractive hybridization and randomly selected clones from each subtractive library were screened by PCR and dot blot hybridization. A total of 85 genes with altered expression were finally identified, with 41 genes from the forward library and 44 from the reverse library. Subsequently, the antagonistic effects of candidate traditional Chinese medicines were evaluated based on the genetic transcription levels of the genes with significant altered expression, including Catnβ, Flt3-L, IL-7r and Rpo2-4. The results indicated that
(L.) Gaert and
had significant down-regulated effects on the transcription level of Catnβ that was up-regulated by α-amanitin, and the two herbs also up-regulated the transcription levels of Flt3-L and Rpo2-4.
(L.) had significant up-regulated effects on the IL-7r that was down-regulated by α-amanitin. These preliminary studies suggested that
were effective antagonists against the toxicity of α-amanitin.
Authors:J. Chen, E. Hildebrandt, H. Delaney, W. Boivin, E. Bialas, E. Attas, and M. Heinrich
Automated alpha and gamma spectrometry systems have been fabricated to analyze large numbers of samples in batches and to perform on-line analysis for a number of experiments concurrently. Specially designed sample changers for alpha and gamma spectrometry and gamma scanners for used fuel and in-situ glass leach experiments have been built. These communicate through digital interfaces, microprocessors, microcomputers and programmable controllers to a Nuclear Data model ND6700 computer/spectrometer. Application software for data entry and reports has been written to interact with Nuclear Data software to pemit easy and efficient operation.
Authors:W. Zhang, K. Ungar, J. Chen, N. St-Amant, and B. Tracy
A quantitative method to determine the activity concentration of 226Ra in soil samples was established using high performance environmental gamma-ray spectrometry. In this method, a semi-empirical
calibration procedure was developed for full energy peak efficiency calculation utilizing the elemental composition of the
soil sample. Aatami software was used to deconvolute the 235U and 226Ra doublet at 185.7 keV and 186.2 keV, respectively, and to fit the baseline of the soil gamma-spectrum for the determination
of 226Ra activity. The results indicated that the Aatami doublet deconvolution procedure provides a rapid and accurate analysis
of a complicated spectrum in comparison with other cumbersome spectral interference correction methods. The study also compared
the results with those obtained by radon progeny (214Pb, or 214Bi) measurements and found that the deconvolution method provided a more accurate 226Ra activity as it is independent of the error caused by radon diffusion. This error can be quite large since the amount of
escaped radon gas through the sample container walls and sealing cannot be accurately quantified.
Authors:Y. Chen, L. Tan, W. Zhou, J. Su, Y. Yang, and Y. Hu
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 Tm but higher Tg 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.
Authors:W. Wang, S. Luan, Y. Chen, L. Cal, Y. Jia, S. Ruan, and J. Duan
New complexes of the non-natural amino acid (p-iodo-phenylalanine) with divalent cobalt and nickel ions have been synthesized. The composition of the complexes is [M(IC6H4CH2CHNH2COO)2]2.5H2O (M=Co, Ni) and the crystal structure belongs to orthorhombic system. Infrared spectra indicate the nature of bonding in the
complex. The first stage in the thermal decomposition process of the complex shows the presence of crystal water. The thermal
decomposition process of cobalt complex differs from that of nickel. The intermediate and final residues in the thermal decomposition
process have been analyzed to check the pyrolysis reactions. Thermal analysis indicates that the iodine atom of the ligand
may coordinate to the metal ion in the lattice.
Authors:J. Chen, G. Grant, W. Boivin, M. Heinrich, A. Kerr, and R. Tkachuk
A study has been carried out to determine the levels of radioisotopes in five Canadian grains from pre-(1985) and post-Chernobyl (1986) crop years. In addition, the radioisotope levels were determined in grains from the 1988 crop year consisting of wheats, oats, barley, corn and oil seeds which included flax, sunflower and canola. The grain and oil-seed samples were ashed to reduce their volume, and the gammaemitters137Cs and40K were determined using a high-purity germanium detector and a high-purity germanium well detector. The90Sr activity measurements required further ashing of the samples followed by chemical separations and -counting of the separated daughter90Y. The results for the 1985, 1986 and 1988 crop years are discussed and compared with results from grain crops obtained during years of atmospheric bomb tests in the 1950's.