The thermodynamics and kinetics of the internal oxidation in dilute Cu-Al alloy are investigated. The internal oxidation of copper alloy containing 0.2 similar to 1.2 wt pet Al is studied in the temperature range from...The thermodynamics and kinetics of the internal oxidation in dilute Cu-Al alloy are investigated. The internal oxidation of copper alloy containing 0.2 similar to 1.2 wt pet Al is studied in the temperature range from 1073 K to 1273 K. A related equilibrium diagram is drawn. A mathematic model of oxidation layer depth is developed on the base of the experimental results. The experiments and investigation show that the formation rate of the internal oxidation layer is mainly controlled by the diffusion of O in matrix, the O concentration on the surface and the Al concentration in the alloy.展开更多
Abstract: Ultrafine SnOx thin films were prepared from tetrabtltyltin by RF glow dis charge polymerization. Annealing behaviour of films under air and gas-sensitive probesty were investigated. The ultrafine SnOx thin ...Abstract: Ultrafine SnOx thin films were prepared from tetrabtltyltin by RF glow dis charge polymerization. Annealing behaviour of films under air and gas-sensitive probesty were investigated. The ultrafine SnOx thin film with average part ide size of 6nm exhibited a high sensitivity of 30 to 500ppm EtOH at 200℃.展开更多
Under basic conditions 4-(N-methyl-sulfamylmethyl)aniline 1 reacted with ethyl 3bromopyruvate 2 in acetone to give the title compound 5. The structure of 5was established by MS, IR,1HNMR and 13CNMR spectra.
Energy band calculations of tetrathiafulvalene-metal bisdithiolenes (C6S8M)∞ (M= Ni, Pt) with the extended Huckel molecular orbital (EHMO) method show that the multiple overlaps among frontier molecular orbitals (FMO...Energy band calculations of tetrathiafulvalene-metal bisdithiolenes (C6S8M)∞ (M= Ni, Pt) with the extended Huckel molecular orbital (EHMO) method show that the multiple overlaps among frontier molecular orbitals (FMO) and the small band gap account for their conducting properties. Their estimated conductivities are in good agreement with experimental data. FMO are mainly composed of ligand orbitals.Differences of the band structures betWeen polymers and layered salts with the same building block are revealed.展开更多
The microstructure and properties of the oxide particle dispersion strengthened composite fabricated by internal oxidation method have been studied. Using nitrogen base atmosphere and a new process flow we can improve...The microstructure and properties of the oxide particle dispersion strengthened composite fabricated by internal oxidation method have been studied. Using nitrogen base atmosphere and a new process flow we can improve the quality of the MMCs and decrease the cost of the composites. The size of alumina is in the nanometer order of magnitude and the particles are well distributed. Under the condition of having good electrical conductivity, the composites have 1 to 2 times higher mechanical properties than those of pure Cu.展开更多
Thermal properties of PHB and PHB/PEG blends were investigated by differential scanning calorimetry (DSC) and melt index (MI) test. DSC thermograms indicate that two components of blend are miscible. From the DSC ther...Thermal properties of PHB and PHB/PEG blends were investigated by differential scanning calorimetry (DSC) and melt index (MI) test. DSC thermograms indicate that two components of blend are miscible. From the DSC thermogram, we can also conclude that the melting point of PHB descends with the increased content of PEG, this can improve PHB processing properties. From MI data, we may draw the same conclusion.展开更多
An anomalous Kerr loop was observed in an oriented LaBaMnO film annealed in oxygen. Many tiny crystal columns were observed with scanning tunneling microscope and magnetic force microscope. The magnetic moment m in th...An anomalous Kerr loop was observed in an oriented LaBaMnO film annealed in oxygen. Many tiny crystal columns were observed with scanning tunneling microscope and magnetic force microscope. The magnetic moment m in the column is perpendicular outward to the surface, which forms a surface phase with spin pinning state. This spin pinning results in the obvious asymmetrical Kerr loop of magneto-optical effect when the magnetic field is in the two opposite directions vertical to the surface.展开更多
We present here a systematically theoretical study on the nonlinearities and their structure-property relationship of cyanovinyl-substituted donor-acceptor molecules by virtue of semiempirical PM3/AM1-FF approach. Goo...We present here a systematically theoretical study on the nonlinearities and their structure-property relationship of cyanovinyl-substituted donor-acceptor molecules by virtue of semiempirical PM3/AM1-FF approach. Good consistency between measured and calculated hyperpolarizabilities is obtained. Results show that conformation has a significant effect on hyperpolarizabilities. The torsion angle change between two conjugated parts of the molecular systems can substantially alter the nonlinearities. The total amount of charge transfer difference from donor to acceptor has been introduced to understand the microscopic nature of the nonlinear optical properties for the title molecules. General guidelines may be sought out in the search of molecules with large values of beta. Some molecules with large molecular hyperpolarizabilities can be predicted by the optimization for the longer pi-electron systems with both acceptor and donor groups.展开更多
Four folding patterns (～15, ～30-40, ～60 and ～90-110 nm) of the higher_order structure of chromatin in chicken erythrocytes have been observed with an atomic force microscope (AFM) under near natural conditions. Re...Four folding patterns (～15, ～30-40, ～60 and ～90-110 nm) of the higher_order structure of chromatin in chicken erythrocytes have been observed with an atomic force microscope (AFM) under near natural conditions. Results showed that the chromatin in the interphase nucleus of chicken erythrocyte was not in a disorganized form but represented a higher_order conformation. The thin sections of the chromatin in the nucleus of chicken erythrocyte were examined with a transmission electron microscope (TEM). Compared with TEM, AFM had the advantages that the samples did not need the preparation procedures such as fixing, sectioning and staining, and thus were closer to their native condition.展开更多
In order to investigate the recognition mechanism and the relationship between structure and function of minihelix DNA with Tryptophanyl-tRNA Synthetase (TrpRS), TrpRS from Bacillus Subtilis was purified. Four minihel...In order to investigate the recognition mechanism and the relationship between structure and function of minihelix DNA with Tryptophanyl-tRNA Synthetase (TrpRS), TrpRS from Bacillus Subtilis was purified. Four minihelix DNAs were chemically synthesized and the photoreactive reagent s4T was incorporated into three of them at the positions of G73, T72 and T55 corresponding to tRNATrp. The apparatus for uv crosslinking was devised and the parameters for uv crosslinking were optimized. The results indicated that the G73 and T72 base of minihelix DNA interacted with TrpRS directly. The uv crosslinking reaction was improved by the dose of uv irradiation and the concentration of both TrpRS and minihelix DNA.展开更多
文摘The thermodynamics and kinetics of the internal oxidation in dilute Cu-Al alloy are investigated. The internal oxidation of copper alloy containing 0.2 similar to 1.2 wt pet Al is studied in the temperature range from 1073 K to 1273 K. A related equilibrium diagram is drawn. A mathematic model of oxidation layer depth is developed on the base of the experimental results. The experiments and investigation show that the formation rate of the internal oxidation layer is mainly controlled by the diffusion of O in matrix, the O concentration on the surface and the Al concentration in the alloy.
文摘Abstract: Ultrafine SnOx thin films were prepared from tetrabtltyltin by RF glow dis charge polymerization. Annealing behaviour of films under air and gas-sensitive probesty were investigated. The ultrafine SnOx thin film with average part ide size of 6nm exhibited a high sensitivity of 30 to 500ppm EtOH at 200℃.
文摘Under basic conditions 4-(N-methyl-sulfamylmethyl)aniline 1 reacted with ethyl 3bromopyruvate 2 in acetone to give the title compound 5. The structure of 5was established by MS, IR,1HNMR and 13CNMR spectra.
文摘Energy band calculations of tetrathiafulvalene-metal bisdithiolenes (C6S8M)∞ (M= Ni, Pt) with the extended Huckel molecular orbital (EHMO) method show that the multiple overlaps among frontier molecular orbitals (FMO) and the small band gap account for their conducting properties. Their estimated conductivities are in good agreement with experimental data. FMO are mainly composed of ligand orbitals.Differences of the band structures betWeen polymers and layered salts with the same building block are revealed.
文摘The microstructure and properties of the oxide particle dispersion strengthened composite fabricated by internal oxidation method have been studied. Using nitrogen base atmosphere and a new process flow we can improve the quality of the MMCs and decrease the cost of the composites. The size of alumina is in the nanometer order of magnitude and the particles are well distributed. Under the condition of having good electrical conductivity, the composites have 1 to 2 times higher mechanical properties than those of pure Cu.
文摘Thermal properties of PHB and PHB/PEG blends were investigated by differential scanning calorimetry (DSC) and melt index (MI) test. DSC thermograms indicate that two components of blend are miscible. From the DSC thermogram, we can also conclude that the melting point of PHB descends with the increased content of PEG, this can improve PHB processing properties. From MI data, we may draw the same conclusion.
文摘An anomalous Kerr loop was observed in an oriented LaBaMnO film annealed in oxygen. Many tiny crystal columns were observed with scanning tunneling microscope and magnetic force microscope. The magnetic moment m in the column is perpendicular outward to the surface, which forms a surface phase with spin pinning state. This spin pinning results in the obvious asymmetrical Kerr loop of magneto-optical effect when the magnetic field is in the two opposite directions vertical to the surface.
基金Project supported by the State Science and Technology Commission and the National Natural Science Foundation of China.
文摘We present here a systematically theoretical study on the nonlinearities and their structure-property relationship of cyanovinyl-substituted donor-acceptor molecules by virtue of semiempirical PM3/AM1-FF approach. Good consistency between measured and calculated hyperpolarizabilities is obtained. Results show that conformation has a significant effect on hyperpolarizabilities. The torsion angle change between two conjugated parts of the molecular systems can substantially alter the nonlinearities. The total amount of charge transfer difference from donor to acceptor has been introduced to understand the microscopic nature of the nonlinear optical properties for the title molecules. General guidelines may be sought out in the search of molecules with large values of beta. Some molecules with large molecular hyperpolarizabilities can be predicted by the optimization for the longer pi-electron systems with both acceptor and donor groups.
文摘Four folding patterns (～15, ～30-40, ～60 and ～90-110 nm) of the higher_order structure of chromatin in chicken erythrocytes have been observed with an atomic force microscope (AFM) under near natural conditions. Results showed that the chromatin in the interphase nucleus of chicken erythrocyte was not in a disorganized form but represented a higher_order conformation. The thin sections of the chromatin in the nucleus of chicken erythrocyte were examined with a transmission electron microscope (TEM). Compared with TEM, AFM had the advantages that the samples did not need the preparation procedures such as fixing, sectioning and staining, and thus were closer to their native condition.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 39730120) the Chinese Academy of Sciences (Grant No. KSCX 2-2-04).
文摘In order to investigate the recognition mechanism and the relationship between structure and function of minihelix DNA with Tryptophanyl-tRNA Synthetase (TrpRS), TrpRS from Bacillus Subtilis was purified. Four minihelix DNAs were chemically synthesized and the photoreactive reagent s4T was incorporated into three of them at the positions of G73, T72 and T55 corresponding to tRNATrp. The apparatus for uv crosslinking was devised and the parameters for uv crosslinking were optimized. The results indicated that the G73 and T72 base of minihelix DNA interacted with TrpRS directly. The uv crosslinking reaction was improved by the dose of uv irradiation and the concentration of both TrpRS and minihelix DNA.
