摘要：
The frequency domain power spectra of acoustic emission (AE) signals from different metal-acid reaction processes such as 6111 Al-alloy-hydrochloric acid (HCl) and 7070 Al-alloy-HCl for evolving hydrogen gases were obtained by fast Fourier transform (FFT) program and used for chemical analysis of different metal materials. Averaged power spectra from these processes and their corresponding characteristics were extracted. The characteristic AE frequency signals could be used for chemical pattern recognition of different metal materials like 6111 and 7050 aluminum alloys from the metal-acid reaction processes, that the principal component analysis (PCA) with appropriate frequency selection procedure gave a satisfactory classification with a correct rate of 78.1%. The back-propagation (BP) algorithm of artificial neural network (ANN) could give better recognition of AE signals for 6111 and 7050 alloys with a correct rate of 100%. Moreover, the AE energetic parameters are linearly correlated with the pH value of the acidic buffer solution, which opens a new possibility for quantitatively analytical application of AE signals on metal materials.
作者机构：
[黄可龙; 戴益民] School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China;[Zeng, Ju-Lan; 李浔; 曹忠; 戴益民] School of Chemistry and Biological Engineering, Changsha University of Science and Technology, Changsha 410004, China;[Zeng, Ju-Lan; 李浔; 曹忠; 戴益民] Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation, Changsha University of Science and Technology, Changsha 410004, China
通讯机构：
School of Chemistry and Chemical Engineering, Central South University, China
摘要：
One-three-dimensional metal-organic frameworks Mg1.5(C12H6O4)1.5(C3H7NO)2 (MgNDC) has been synthesized solvothermally and characterized by single crystal XRD, powder XRD, FT-IR spectra. The low-temperature molar heat capacities of MgNDC were measured by temperature modulated differential scanning calorimetry (TMDSC) over the temperature range from 205 to 470 K for the first time. No phase transition or thermal anomaly was observed in the experimental temperature range. The thermodynamic parameters of MgNDC such as entropy and enthalpy relative to reference temperature of 298.15 K were derived based on the above molar heat capacities data. Moreover, the thermal stability and decomposition of MgNDC was further investigated through thermogravimetry (TG)–mass spectrometer (MS). Three stages of mass loss were observed in the TG curve. TG–MS curve indicated that the oxidative degradation products of MgNDC are mainly H2O, CO2, NO, and NO2.
期刊：
International Journal of Hydrogen Energy,2011年36(18):11785-11793 ISSN：0360-3199
通讯作者：
Sun, Li-Xian
作者机构：
[Sun, Li-Xian; Liu, Shu-Sheng; Zhang, Jian] Chinese Acad Sci, Dalian Inst Chem Phys, Mat & Thermochem Lab, Dalian 116023, Peoples R China.;[Liu, Shu-Sheng] Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China.;[Xu, Fen] Liaoning Normal Univ, Fac Chem & Chem Engn, Dalian 116029, Peoples R China.;[Cao, Zhong] Changsha Univ Sci & Technol, Sch Chem & Biol Engn, Changsha 410004, Hunan, Peoples R China.;[Liu, Ying-Liang] Jinan Univ, Dept Chem, Guangzhou 510632, Guangdong, Peoples R China.
通讯机构：
[Sun, Li-Xian] C;Chinese Acad Sci, Dalian Inst Chem Phys, Mat & Thermochem Lab, Dalian 116023, Peoples R China.
关键词：
Metal hydride;Magnesium;Titanium fluoride;Mechanism;Kinetics;Thermodynamics
摘要：
MgH2–Li3AlH6 mixture shows a mutual activation effect between the components. But the dehydrogenation kinetics is still slow, especially at temperature as low as 250 °C. Hereby, an additive (TiF3) was introduced into the mixture in the present study. The reaction mechanisms were studied by the combined analyses of X-ray diffraction (XRD), thermogravimetric analysis (TGA), as well as thermodynamic calculations. A two-step ball milling method could reduce the mechanical decomposition of Li3AlH6 effectively and was adopted. During milling, Li3AlH6 reacts with TiF3 and produces Al3Ti while MgH2 remains stable. All the species are well mixed after milling and the grain size is as small as 100 nm. During TGA test, all the reactions occur at lower temperatures compared with undoped mixture, especially the dehydrogenation of MgH2, which shows a decrease of 60 °C. Its activation energy is reduced by 32.0 kJ mol−1. The first three isothermal (250 °C) cycles indicate that the kinetics of dehydrogenation has been greatly enhanced, showing a reversible capacity of 4.5 wt.% H2. The time needed for the 1st dehydrogenation has been shortened to 3600 s from 8000 s for the undoped mixture. These improvements are mainly attributed to the catalytic effect of the in-situ formed Al3Ti. But there is no influence on the rehydrogenation kinetics and the enthalpy of the dehydrogenation of MgH2 is unchanged.
摘要：
A new potential enantioselective catalyst derived from ferrocene, 1-{(R)-1-[(S)-2-(diphenylphosphino)ferrocenyl]ethyl}-benzimidazole (DPFEB), was prepared and its absolute structure was characterized by means of single crystal X-ray diffraction. The molar heat capacity of DPFEB was measured by means of temperature modulated differential scanning calorimetry over the temperature range of 200–530 K, and the thermodynamic functions of [H
T
− H
298.15] and [S
T
− S
298.15] were calculated. Further more, thermogravimetry experiment revealed that DPFEB exhibited a three step thermal decomposition process with the final residual of 28.7%.
摘要：
A novel optical biosensor with gold surface bound silver nanoparticles has been constructed for detection of oncogene of c-Myc tagged DNA plasmid, which exhibited distinct optical properties of localized surface plasmon resonance. The silver colloidal nanoparticles were prepared by using chemical reduction method with sodium citrate, starch and silver nitrate, which were characterized by using UV-Vis absorption spectroscopy, transmission electron microscopy, and cyclic voltammetry, indicating that the silver colloidals were pure, sphere-shaped and narrow- dispersed size distribution with a diameter of 11.70 ± 1.94 nm. The silver nanoparticles were well assembled on the gold substrate with 1,4-dithiothreitol. In the subsequent linking step with compounds of L-cysteine, 3-mercaptopropionic acid, and sodium thioglycolate/HCl, L-cysteine exhibited best characteristics for linking with Ag nanoparticles and formed a nice sensing film by conjugating with a antibody of c-Myc (3C7), mouse monoclonal IgG. The c-Myc antibody immobilized optical biosensor can be well applied to determination of c-Myc tagged DNA plasmid with good regeneration ability. The detection limit was evaluated to be 1.0 pg/μL.
关键词：
Recognition mechanism;Isopropanol;Calixarene derivative;C-H center dot center dot center dot pi bond;Host-guest interaction;Environment detection
摘要：
The adsorption characteristics of four calixarene supramolecular compounds, like RCT, PCT, MRCT, and TBCA, as coating materials of quartz crystal microbalance sensors responding to isopropanol vapor have been investigated in this paper. The results showed that the RCT was the best coating material for isopropanol vapor when the coating mass reached 20.41 μg. The frequency shift of RCT coated QCM and the concentration of isopropanol vapor had a good linear relationship and sensitivity. Comparing with the gas chromatography, the QCM sensor could be well used for the determination of isopropanol vapor with a recovery rate of 95.22~108.1 %, and the two methods showed a well consistent examination result. Also, the sensor possessed good reversibility, reproducibility and stability, indicating that the RCT coated QCM sensor can be applied for the detection of the atmospheric polutant of isopropanol vapor in practice. The mechanism of the calixarene derivative for recognition of the isopropanol molecule has been preliminarily discussed.
摘要：
In order to improve the therapeutic efficacy of retinoid carboxylic acids, a novel retinoate was designed and synthesized with 4-aminophenol as a linker from solanesol and 13-cis-retinoic acid. The synthetic procedure and characterization of the retinoate are described.
摘要：
2-substituted benzimidazole-zinc and 2-substituted benzimidazole-copper complexes were main components of organic solderability preservativ(OSP) in PCB producing process and affect the thermal stability of OSP film. So these four complexes were prepared by 2-substituted-benzimidazole reacting with zinc ion and copper ion, the complexes crystals were determined by IR, its thermal stabilities were studied by TG method. The results indicated that the thermal stability of 2-substituted benzimidazole-zinc is higher than the 2-substituted benzimidazole-copper, and the thermal decomposition mechanism was presented.
