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.
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
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: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:B. Chen, L.-W. Li, Y.-J. Lin, Z.-H. Wang, and G.-D. Lu
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.
Authors:N. Li, Y. Zong, B.L. Liu, W.J. Chen, and B. Zhang
Purple pericarp is an interesting and useful trait in Triticum aestivum, but the molecular mechanism behind this phenotype remains unclear. The allelic variation in the MYB transcriptors is associated with the phenotype of pigmented organs in many plants. In this study, a MYB transcription factor gene, TaMYB3, was isolated using homology-based cloning and a differentially expressed gene mining approach, to verify the function of the MYB transcriptor in the purple pericarp. The coding sequence of TaMYB3 in cultivar Gy115 was the same as that in cultivar Opata. TaMYB3 was localized to FL0.62–0.95 on chromosome 4BL. The TaMYB3 protein contains DNA-binding and transcription-activation domains, and clustered on a phylogenetic tree with the MYB proteins that regulates anthocyanin and proanthocyanin biosynthesis. TaMYB3 localized in the nuclei of Arabidopsis thaliana and wheat protoplasts after it was transiently expressed with PEG transformation. TaMYB3 induced anthocyanin synthesis in the pericarp cells of Opata in the dark in collaboration with the basic helix–loop–helix protein ZmR, which is also the function of ZmC1. However, TaMYB3 alone did not induce anthocyanin biosynthesis in the pericarp cells of the white grain wheat cultivar Opata in the light after bombardment, whereas the single protein ZmR did. Light increased the expression of TaMYB3 in the pericarp of Gy115 and Opata, but only induced anthocyanin biosynthesis in the grains of Gy115. Our results extend our understanding of the molecular mechanism of the purple pericarp trait in T. aestivum.
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: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.
Authors:J. Chen, E. Hildebrandt, H. Delaney, W. Boivin, E. Bialas, 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.