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Thermal analysis and degradation kinetics of thermoplastics

I. Staybelite Resin and its derivative Staybelite ester 10

Journal of Thermal Analysis and Calorimetry
Authors: J. W. Lin and W. Y. Wen

The thermal mechanical properties and degradation kinetics of Staybelite Resin, a thermoplastic, and its ester derivative Staybelite Ester 10 have been investigated using thermoanalytic methods. The thermogravimetric analyzer applied in the degradation studies has been interfaced with a minicomputer for data acquisition. The degradation kinetics of each thermosplastic have been satisfactorily attributed to an associated first-order process using a differential method.

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Summary

A simple and rapid capillary electrophoretic procedure for analysis of matrine and oxymatrine in Kushen medicinal preparations has been developed and optimized. Orthogonal design was used to optimize the separation and detection conditions for the two active components. Phosphate concentration, applied potential, organic modifier content, and buffer pH were selected as variable conditions. The optimized background electrolyte contained 70 mM sodium dihydrogen phosphate and 30% acetonitrile at pH 5.5; the separation potential was 20 kV. Each analysis was complete within 5 min. Regression equations revealed linear relationships (r > 0.999) between peak area and amount for each component. The detection limits were 1.29 μg mL−1 for matrine and 1.48 μg mL−1 for oxymatrine. The levels of the two active compounds in two kinds of traditional Chinese medicinal preparation were easily determined with recoveries of 96.57–106.26%. In addition, multiple linear regression and a non-linear model using a radial basis function neural network approach were constructed for prediction of the migration time of oxymatrine. The predicted results were in good agreement with the experimental values, indicating that a radial basis function neural network is a potential means of prediction of separation time in capillary electrophoresis.

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Abstract  

An attempt has been made to develop a radiochemical methodology for the decontamination of a trace amount of radioactive cesium from a bulk amount of natural NaCl by liquid-liquid extraction (LLX). Open chain crown ethers, of amide type, namely, N,N,N",N"-tetraphenyl-3,6-dioxaoctanediamide (TDD), N,N,N",N"-tetraphenyl-3,6,9-trioxaundecanediamide and N,N"-dinaphthyl-N,N"-diphenyl-3,6-dioxaoctanediamide (DDD) have been chosen for this purpose. The separation factor between Cs and Na is the highest when 10-4M TDD dissolved in nitrobenzene is used as extractant and 0.4M picric acid at pH 5.0 is used as aqueous phase. About 60% Cs is extracted in this condition in a single run.

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Abstract  

Multitracers were prepared by 80 MeV/A 12 C irradiation on thick gold foil at Heavy Ion Research Facility, Institute of Modern Physics, Lanzhou, China. The bulk gold was removed quantitatively from the multitracer solutions with a MIBK-HCl solution.

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Abstract

Vent sizing package 2 (VSP2) was used to measure the thermal hazard and runaway characteristics of 18650 lithium-ion batteries, which were manufactured by Sanyo Electric Co., Ltd. Runaway reaction behaviors of these batteries were obtained: 50% state of charge (SOC), and 100% SOC. The tests evaluated the thermal hazard characteristics, such as initial exothermic temperature (T 0), self-heating rate (dT dt −1), pressure-rise rate (dP dt −1), pressure temperature profiles, maximum temperature, and pressure which were observed by adiabatic calorimetric methodology via VSP2 using customized test cells. The safety assessment of lithium-ion cells proved to be an important subject. The maximum self-heating rate (dT dt −1)max and the largest pressure-rise rate (dP dt −1)max of Sanyo 18650 lithium-ion battery of 100% SOC were measured to be 37,468.8 °C min−1 and 10,845.6 psi min−1, respectively, and the maximum temperature was 733.1 °C. Therefore, a runaway reaction is extremely serious when a lithium-ion battery is exothermic at 100% SOC. This result also demonstrated that the thermal VSP2 is an alternative method of thermal hazard assessment for battery safety research. Finally, self-reactive ratings on thermal hazards of 18650 lithium-ion batteries were studied and elucidated to a deeper extent.

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A sensitive and simple liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method for determination of dasatinib in rat plasma using one-step protein precipitation was developed. After addition of carbamazepine as internal standard (IS), protein precipitation by acetonitrile was used as sample preparation. Chromatographic separation was achieved on an SB-C18 (2.1 mm × 150 mm, 5 μm) column with methanol-0.1% formic acid as mobile phase with gradient elution. Electrospray ionization (ESI) source was applied and operated in positive ion mode; selective ion monitoring (SIM) mode was used to quantification using target fragment ions m/z 488.2 for dasatinib and m/z 338.7 for the IS. Calibration plots were linear over the range of 10–1000 ng mL−1 for dasatinib in rat plasma. Lower limit of quantification (LLOQ) for dasatinib was 10 ng mL−1. Mean recovery of dasatinib from plasma was in the range 82.2%–93.6%. Relative standard deviation (RSD) of intra-day and inter-day precision were both less than 8%. This developed method is successfully used in pharmacokinetic study of dasatinib in rats.

Open access

New high-molecular-weight glutenin (HMW glutenin) sequences isolated from six Psathyrostachys juncea accessions by thermal asymmetric interlaced PCR differ from previous sequences from this species. They showed novel modifications in all of the structural domains, with unique C-terminal residues, and their N-terminal lengths were the longest among the HMW glutenins reported to date. In their repetitive domains, there were three repeatable motif units: 13-residue [GYWH(/I/Y)YT(/Q)S(/T)VTSPQQ], hexapeptide (PGQGQQ), and tetrapeptide (ITVS). The 13-residue repeats were restricted to the current sequences, while the tetrapeptides were only shared by D-hordein and the current sequences. However, these sequences were not expressed as normal HMW glutenin proteins because an in-frame stop codon located in the C-termini interrupted the intact open reading frames. A phylogenetic analysis supported different origins of the P. juncea HMW glutenin sequences than that revealed by a previous study. The current sequences showed a close relationship with D-hordein but appeared to be more primitive.

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Cereal Research Communications
Authors: S.F. Dai, D.Y. Xu, Z.J. Wen, Z.P. Song, H.X. Chen, H.Y Li, J.R. Li, L.Z. Kang, and Z.H. Yan

A novel 4.0-kb Fy was sequenced and bacterially expressed. This gene, the largest y-type HMW-GS currently reported, is 4,032-bp long and encodes a mature protein with 1,321 amino acid (AA) residues. The 4.0-kb Fy shows novel modifications in all domains. In the N-terminal, it contains only 67 AA residues, as three short peptides are absent. In the repetitive domain, the undecapeptide RYYPSVTSPQQ is completely lost and the dodecapeptide GSYYPGQTSPQQ is partially absent. A novel motif unit, PGQQ, is present in addition to the two standard motif units PGQGQQ and GYYPTSPQQ. Besides, an extra cysteine residue also occurs in the middle of this domain. The large molecular mass of the 4.0-kb Fy is mainly due to the presence of an extra-long repetitive domain with 1,279 AA residues. The novel 4.0-kb Fy gene is of interest in HMW-GS gene evolution as well as to wheat quality improvement with regard to its longest repetitive domain length and extra cysteines residues.

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Journal of Thermal Analysis and Calorimetry
Authors: J. Zhi, W. Tian-Fang, L. Shu-Fen, Z. Feng-Qi, L. Zi-Ru, Y. Cui-Mei, L. Yang, L. Shang-Wen, and Z. Gang-Zhui

Abstract  

The effects of aluminum (Al) and nickel (Ni) powders of various grain sizes on the thermal decomposition of ammonium perchlorate (AP) were investigated by TG and DSC in a dynamic nitrogen atmosphere. The TG results show that Al powders have no effect on the thermal decomposition of AP at conventional grain size, while the nanometer-sized Ni powders (n-Ni) have a great influence on the thermal decomposition of AP with conventional and superfine grain size. The results obtained by DSC and an in situ FTIR analysis of the solid residues confirmed the promoting effects of n-Ni. The effects of n-Ni have been ascribed to its enhancement on the gas phase reactions during the second step decomposition of conventional grain size AP.

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