bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantum Chemistry Study on Local Structure and Properties of Amorphous Fe80P20 Alloy
Authors: Fang Zhi-gang , Hu Hong-zhi , Guo Jing-xue , Li Qiu-ju
Published: January 2011

According to the structure features of Fe80P20, a series of clusters Fe4P were designed and focused on studying the stability of local structure, charge distribution and chemical bond. Using the DFT method, energy and structure of Fe4P clusters were optimized and analyzed. The computational results showed that the energy of cluster 1(2) has the lowest energy, and the possibility of its existence in the Fe80P20 is high. Analyzing the transition states among the clusters, it was found that the clusters in the doublet state are more stable than those in the quartet state. The numbers of the FeP bond in the clusters play important roles in the cluster stability and electrons transfer properties. The more numbers of FeP bonds in the clusters, the higher the cluster stability, and the weaker the ability of P atom to get electron. The number of Fe atoms, which has bonding interactions with the P atom, is direct proportional to the average 3d orbit population of Fe atom. Basing on the orbital population, average magnetic moments of each Fe atom in the Fe4P clusters were calculated, and they are all smaller than that of single metal Fe atom. This suggests that all Fe4P clusters have soft magnetic property and they are expected to be perfect material for preparing soft magnetic apparatus.
Transient Absorption of the Chlorophyll a in Ethanol
Authors: Shi Ying , Shiu Y. J. , Su Charlene , Lin S. H. , Han Ke-li
Published: January 2011

The excited state of Chlorophyll a is investigated by femtosecond transient absorption. The transient absorption spectra of Q band and By band of Chlorophyll a in ethanol have been observed. The fast kinetics of Chlorophyll a which exhibit two ultrafast components were also measured. The one is assigned to transient absorption of the inhomogeneously broadened ground state absorption spectrum, while the other is the response of the solvent to the change of the electron configuration in the excited state due to solvation dynamics of the polar solvent molecules. To understand the anisotropy of Chlorophyll a in ethanol, the anisotropy profile was also performed by 405 nm excitation and found that the anisotropy profile is 0.143. The possible combination of da, db and at excitation of By band has been simulated.
Simulated Equations of State of MgSiO3 Perovskite
Authors: Liu Zi-jiang , Cheng Xin-lu , Zhang Fang-pei , Yang Xiang-dong , Guo Yuan
Published: January 2011

The equation of state of MgSiO3 perovskite under high pressure and high temperature is simulated using the molecular dynamics method. It was found that the molecular dynamics simulation is very successful in accurately reproducing the measured molar volumes of MgSiO3 perovskite over a wide range of temperatures and pressures. The simulated equation of state of MgSiO3 perovskite matched experimental data at up to 140 GPa at 300 K, as well as the fitting data of others and results from the first-principles simulation based on the local density approximation. The simulated equations of state of MgSiO3 perovskite at higher temperatures and higher pressures also correspond to the other calculations. In addition, the volume compression data of MgSiO3 perovskite is simulated up to 120 GPa at 300, 900, 2000 and 3000 K, respectively.
Theoretical Studies on Reaction Pathways of Samarium(II) Carbenoid-Promoteded Cyclopropanation Reaction of Ethylene
Authors: Geng Zhi-yuan , Zhang Xing-hui , Wang Yong-cheng , Fang Ran , Gao Li-guo , Chen Xiao-xia , Zhao Cun-yuan
Published: January 2011

In order to have efficient and highly stereoselective cyclopropanating reagents, the cyclopropanation reaction of ethylene promoted with Samarium(II) carbenoid [SimmonsSmith (SS) reagent] were studied by means of B3LYP hybrid density functional method. The geometries for reactants, transition states and products are completely optimized. All transition states were verified by the vibrational analysis and the intrinsic reaction coordinate (IRC) calculations. The results showed that, identical with the lithium carbenoid, CH3SmCH2X (X = Cl, Br and I) can fairly react with ethylene via both methylene transfer pathway (pathway A) and carbometalation pathway (pathway B). And the cyclopropanation reaction via methylene transfer pathway proceeds with a lower barrier and at lower temperatures.
Preparation of Well-aligned CNT Arrays Catalyzed with Porous Anodic Aluminum Oxide Template
Authors: Chen Xing , Huang Xing-jiu , Huang Jia-rui , Huang Zhong-ying , Xu Wei-hong , Liu Jin-huai
Published: January 2011

Well-aligned open-ended multi-walled carbon nanotube (MWCNT) arrays were prepared via chemical vapor deposition (CVD) method in porous anodic aluminum oxide (AAO) templates without depositing any transition metals as catalyst. Effects of the CVD temperature and heat treatment were studied in detail. Well-aligned open-ended MWCNT arrays were obtained at the CVD temperature above 600 C; when CVD temperature is reduced to around 550 C, CNTs, CNFs and other structures existed at the same time; no CNTs or carbon nanofibres (CNFs) could be found as the CVD temperature is below 500 C, and only amorphous carbon in the porous AAO template was found. Experimental results showed that the AAO template is catalytic during the CVD process, and it has the following two effects: to catalyze thermal decomposition of acetylene and to catalyze conversion of carbon decomposed from acetylene into CNTs or CNFs. Heat treatment could improve the graphitization degree, but it might also introduce new defects.
Mechanism and Kinetics of Thermal Dissociation of Inclusion Complex of -Cyclodextrin and 1-Methylcyclopropene
Authors: He Yi , Sun Ting
Published: January 2011

The inclusion-complex of CD-MCP (-cyclodextrin (-CD) including 1-methylcyclopropene (1-MCP)) was prepared and characterized. Basing on programmed-heating procedure and weight-temperature analysis, as well as the application of Satava-Sestak's, Ozawa's and Kissinger's methods, the mechanism and kinetics of thermal dissociation of this inclusion complex were studied. An additional mass loss is found at 170180 C. The mechanism of thermal dissociation of CD-MCP is dominated by a one-dimensional random nucleation and subsequent growth process (A2/3). The activation energy ES and the pre-exponential factor AS for the process are 102.14 kJ/mol and 3.63 1010 s1, respectively. This ES value shows that there is no strong chemical interactions between -CD and 1-MCP.
Effect of Parent Internal Excitation on Product State Distribution in Methyl Radical Photodissociation at 212.5 nm
Authors: Wu Guo-rong , Zhang Jing-hui , Harich Steven A. , Yang Xue-ming
Published: January 2011

Photodissociation dynamics of the CH3 radical at 212.5 nm excitation has been studied experimentally using the H atom Rydberg tagging time-of-flight method. CH3 radicals are produded by photodissociation of CH3I at 266 nm. Translational energy distribution and angular distribution for the CH2 product from CH3 photodissociation at different vibrational levels via the 3s Rydberg state have been measured. From these distributions, product J state distributions are obtained for photodissociation of different vibrationally excited CH3 radicals. The effect of parent vibrational as well as rotational excitation on the dissociation dynamics of CH3 is also investigated in detail. Experimental results in this work show that parent vibrational excitation in the umbrella mode has a significant effect on both rotational excitation and angular distribution of the CH2 product, while parent rotational excitation has obvious effect only on the angular distribution of CH2 product.
Photo-induced Intra-complex Reactions in Ca+-Pyridine
Authors: Wang Dong-sheng , Han Ke-li , Yang Shi-he
Published: January 2011

Photodissociation spectra of Ca+-pyridine complex was obtained by reflectron time of flight spectrum (RTOF). Two channels were found from difference photodissociation spectra, one was non-reactive Ca+ cation separation channel, the other one was active channel for product Ca+NH2. Product Ca+ was dominant in the whole region studied and the only product in 530-590 nm region, reactive product Ca+NH2 shared a little present in whole products. Action spectrum as a function of photolysis laser wavelength shows appearance peaks relevant to transitions of complex. Branching ratio supports the information of photodissociation too.
Numerical Analysis on Magnetic-induced Shear Modulus of Magnetorheological Elastomers Based on Multi-chain Model
Authors: Zhu Ying-shun , Gong Xing-long , Dang Hui , Zhang Xian-zhou , Zhang Pei-qiang
Published: January 2011

Based on the magnetic interaction energy, using derivative of the magnetic energy density, a model is proposed to compute the magnetic-induced shear modulus of magnetorheological elastomers. Taking into account the influences of particles in the same chain and the particles in all adjacent chains, the traditional magnetic dipole model of the magnetorheological elastomers is modified. The influence of the ratio of the distance between adjacent chains to the distance between adjacent particles in a chain on the magnetic induced shear modulus is quantitatively studied. When the ratio is large, the multi-chain model is compatible with the single chain model, but when the ratio is small, the difference of the two models is significant and can not be neglected. Making certain the size of the columns and the distance between adjacent columns, after constructing the computational model of BCT structures, the mechanical property of the magnetorheological elastomers composed of columnar structures is analyzed. Results show that, conventional point dipole model has overrated the magnetic-induced shear modulus of the magnetorheological elastomers. From the point of increasing the magnetic-induced shear modulus, when the particle volume fraction is small, the chain-like structure exhibits better result than the columnar structure, but when the particle volume fraction is large, the columnar structure will be better.
Non-premixed Combustion Model of Fluidized Bed Biomass Gasifier for Hydrogen-Rich Gas
Authors: Zhou Mi , Yan Li-feng , Guo Qing-xiang , Zhu Qing-shi
Published: January 2011

Fluidized bed biomass gasifiers can be employed to produce hydrogen-rich gas. A non-premixed combustion model is used for biomass air-steam gasification in the gasifier, and the simulations were carried out by using the FLUENT 6.0 software. The simulation results are compared with the experimental data. The effects of the steam to biomass ratio (S/B), the equivalence ratio (ER), and the size of biomass particles on the hydrogen yield were studied. Meanwhile, the distributions of hydrogen inside the gasifier at different conditions are also described.
Application of PCA and HCA to the Structure-Activity Relationship Study of Fluoroquinolones
Authors: Li Xiao-hong , Zhang Xian-zhou , Cheng Xin-lu , Yang Xiang-dong , Zhu Zun-lue
Published: January 2011

Density functional theory (DFT) was used to calculate molecular descriptors (properties) for 12 fluoroquinolone with anti-S.pneumoniae activity. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed to reduce dimensionality and investigate in which variables should be more effective for classifying fluoroquinolones according to their degree of an-S.pneumoniae activity. The PCA results showed that the variables ELUMO, Q3, Q5, QA, logP, MR, VOL and EHL of these compounds were responsible for the anti-S.pneumoniae activity. The HCA results were similar to those obtained with PCA. The methodologies of PCA and HCA provide a reliable rule for classifying new fluoroquinolones with anti-S.pneumoniae activity. By using the chemometric results, 6 synthetic compounds were analyzed through the PCA and HCA and two of them are proposed as active molecules with anti-S.pneumoniae, which is consistent with the results of clinic experiments.
Band Structure of Three-dimension Phononic Crystals
Authors: Yan Lin , Zhao He-ping , Wang Xiao-yun , Huang Guo-sheng , Peng Xiu-yan
Published: January 2011

By using the plane-wave-expansion method, the band structure of three-dimension phononic crystals was calculated, in which the cuboid scatterers were arranged in a host with a face-centered-cubic (FCC) structure. The influences of a few factors such as the component materials, the filling fraction of scatterers and the ratio (RHL) of the scatterer's height to its length on the band-gaps of phononic crystals were investigated. It is found that in the three-dimension solid phononic crystals with FCC structure, the optimum case to obtain band-gaps is to embed high-velocity and high-density scatterers in a low-velocity and low-density host. The maximum value of band-gap can be obtained when the filling fraction is in the middle value. It is also found that the symmetry of the scatterers strongly influences the band-gaps. For RHL 1, the width of the band-gap decreases as RHL increases. On the contrary, the width of the band-gap increases with the increase of RHL when RHL is smaller than 1.
Al/GaSb Contact with Slow Positron Beam
Authors: Wang Hai-yun , Weng Hui-min , Ling C. C. , Ye Bang-jiao , Zhou Xian-yi
Published: January 2011

Annealing study of the Al/GaSb system was performed by using a slow positron beam and the measurement of X-ray diffraction. The S parameter against positron energy data were fitted by a three layer model (Al/interface/GaSb). It was found there was a 5 nm interfacial at the region between the Al layer and bulk in the sample of as-deposited. After the 400 C annealing, this interfacial region extends to over 40 nm and S parameter dramatically drops. This is possibly due to a new phase formation induced by the atoms' inter-diffusion at the interface. The annealing out of the open volume defects in the Al layer was revealed by the decrease of the S parameter and the increase of the effective diffusion length of the Al layer. Annealing behaviors of Sb and Lb of the GaSb bulk showed the annealing out of positron traps at 250 C. However, further annealing at 400 C induces formation of positron traps, which are possibly another kind of VGa-related defect and the positron shallow trap GaSb anti-site. The results of the X-ray diffraction experiment verified the conclusion of obtained by using positron technology.
Cu(II), Ni(II) Complexation with Acid Alizarine Blue B in the Presence of Cetyltrimethylammonium Bromide
Authors: Shen Rong , Gao Hong-Wen , Yu Han-Qing
Published: January 2011

The coordination reactions of Cu(II) and Ni(II) with acid alizarine blue B (AABB) in the presence of cetyltrimethylammonium bromide (CTAB) micelle were investigated using the microsurface adsorption-spectral correction technique (MSASC). The aggregation of AABB on CTAB followed the Langmuir isothermal adsorption law. The enrichment of AABB on CTAB sensitized the complexation between Cu(II) or Ni(II) and AABB. The binding ratio of AABB to CTAB was 1:2.5, and monomeric aggregate, AABB2CTAB5, was formed with an adsorption constant of 5.95105 at 20 C or 2.48105 at 40 C. In the ternary complexation, the ratio of AABB:Cu and AABB:Ni were 1:1 and 1:2.5, respectively. Two types of aggregates, Cu2AABB2CTAB80 and Ni5AABB2CTAB80, were formed.
Preparation and Fluorescence Properties of Co-doped Nanocomposite Film Based on Supra Molecular Structure
Authors: Li Gui-an , Li Xiu , Song Jian-ping , Li Fa-rong , Ma Shao-hua , Zhang Yu-rong , Fang Xiao-ling
Published: January 2011

A novel materials design procedure based on the co-doping of metal nanoparticle and azo dye compound (MNPADC) is developed to improve the properties of functional molecules. The synthesized materials were characterized by transmission electron micrograph (TEM), ultraviolet-visible absorption spectra (UV-Vis) and fluorescence spectra (FS). It was found that the fluorescence intensity of methyl orange (MO) was enhanced by 5 times in the aqueous composite system doped with silver nanoparticles whereas it was reduced by 15% and 20% in composite films with co-mixing and coating structures, respectively. The results indicate that the properties of functional molecules can be greatly improved in composite film with supra molecular structure and that the procedure presented here is effective.
Full Quantum State Resolved Scattering Dynamics of the F+H2HF+H Reaction at 5.02 kJ/mol
Authors: Qiu Ming-hui , Ren Ze-feng , Che Li , Dai Dong-xu , Harich Steve A. , Wang Xiu-yan , Yang Xue-ming
Published: January 2011

A crossed molecular beams, state-to-state scattering study was carried out on the F+H2HF+H reaction at the collision energy of 5.02 kJ/mol, using the highly sensitive H atom Rydberg tagging time-of-flight method. All the peaks in the TOF spectra can be clearly assigned to the ro-vibrational structures of the HF product. The forward scattering of the HF product at v=3 has been observed. The small forward scattering of the HF product at v=2 has also been detected. Detailed theoretical analysis is required in order to fully understand the dynamical origin of these forward scattering products at this high collision energy.
A Globalab initioPotential Energy Surface for F+H2HF+H
Authors: Xu Chuan-xiu , Xie Dai-qian , Zhang Dong-hui
Published: January 2011

A global three dimensional potential energy surface for the F+H2HF+H reaction has been developed by spline interpolation of about 15,000 symmetry-unique ab initio points, obtained from the multi-reference configuration interaction level with Davidson correction using the aug-cc-pV5Z basis set. In the entrance channel the spin-orbit coupling energy is also included.
STM Study of Moire Patterns on HOPG
Authors: Zhang Jian-fei , Cao Geng-yu
Published: January 2011

Moire patterns on HOPG were studied with scanning tunneling microscopy (STM). The results reveal that the observed Moire patterns originate from the defects locating several layers below the surface, which presents the first experimental evidence supporting the prediction that in HOPG the nanoscale electronic waves can propagate through several layers without obvious decay.
In situ Heating and Thermal Effects in Auger Electron Spectroscopy for GaN
Authors: Xu Fu-chun , Zhang Qi-he , Cen Dan-xia
Published: January 2011

An in situ heating system was built for the Auger electron spectroscopy to investigate the thermal effect of Auger lines. A GaN sample was studied in this system. The kinetic energy of Ga LMM and MVV Auger lines were observed to shift negatively with temperature increasing. By using ab initio calculation, the theoretical Ga MVV Auger line shape was fit, which well reflects the inner property of the line. The Auger shift with heating is related with the valence electron rearrangement in the thermal expansion of the local bonds.
Coincidence Doppler Broadening Study of Elemental Metals
Authors: Xi Chuan-ying , Ye Bang-jiao , Kong Wei , Weng Hui-min , Zhou Xian-yi , Han Rong-dian
Published: January 2011

Twenty pure elemental metal samples have been studied with a coincidence Doppler broadening system (CDB). The results show the relationship between the CDB spectra and the electronic structure of these samples. The experimental results are compared to simple theoretical predictions, which show that the high-momentum part of the Doppler-broadening spectra can be used to distinguish different elements.
Effects of Matrix-to-analyte Ratio and Laser Energy on Peptides Ion Signals
Authors: Zhou Liu-zhu , Zhu Yuan , Guo Xiao-yong , Zhao Wen-wu , Zheng Hai-yang , Gu Xue-jun , Fang Li , Zhang Wei-jun
Published: January 2011

A method of aerosol introduction for matrix-assisted laser desorption/ionization (MALDI) is described. The aerosol particles containing matrix and analyte enter directly into the aerosol time-of-flight mass spectrometer (ATOFMS) at atmospheric pressure. The scattered light signals from the aerosol particles are collected by a photomultiplier tube (PMT) and are passed on to an external electronic timing circuit, which determines particle size and is used to trigger a 266 nm pulsed Nd:YAG laser. The aerosol MALDI mass spectra and aerodynamic diameter of single particles can be obtained in real-time. Compared with other methods of liquid sample introduction, this method realizes detection of single particles and, more importantly, the sample consumption is lower. The effects of matrix-to-analyte ratio and laser pulse energy on analyte ion yield are examined. The optimal matrix-to-analyte ratio and laser energy are 50-110:1 and 200-400 J respectively.
Chemical Bond Properties and Isomer Shifts of Tl2Ba2Ca2Cu3O10
Authors: Yu Jin-ku , Li Dong-chun , Gao Fa-ming
Published: January 2011

Tl2Ba2Ca2Cu3O10 was reported to be a superconductor with a highest transition temperature of 125 K among the homologous series of Tl2Ba2Can1CunO2n+4. The direct information on the Cu ion site at the atomic level is important for elucidating the superconductivity mechanism. The local bond properties of Tl2Ba2Ca2Cu3O10 were studied using the average band-gap model. The calculated results show that the covalency of Cu(1)O bond is 0.561, and the average covalency of Cu(2)O is 0.296. Mossbauer isomer shifts of 57Fe in Tl2Ba2Ca2Cu3O10 were calculated using the chemical surrounding factor, defined by covalency and electronic polarizability. It is verified that for lower doping, Fe substitute the Cu at the Cu (1) site in forms of Fe3+ and Fe4+; for higher doping, Fe3+ and Fe4+ ion occupies Cu(1) and Cu(2) site respectively. The studies show that the determination of the correspondence between spectrum components and actual copper sites occupied by Mossbauer nucleus was made easier with the aid of the calculation results of the chemical bond parameters.
Two Types of Potential Oscillation During the Reduction of Dichromate on Gold Electrode in H2SO4 Solution
Authors: Jiang Xiao-chun , Chen Shu , Li Ze-lin
Published: January 2011

Two different types of potential oscillations have been identified for the first time during dichromate reduction on a gold electrode in a solution of dilute sulfuric acid. One occurs before hydrogen evolution due to the formation and dissolution of passivating films of low-valence chromium oxides, and the other generates, accompanying periodic hydrogen evolution, from the coupling of electrochemical reactions with diffusive and convective mass transport. More interestingly, these two types of oscillations correspond to two crossing loops in the cyclic voltammogram (CV). Such a relation of oscillations with crossed CVs will provide a new way to find electrochemical oscillatory systems systematically and rapidly.
Electronic Structures and Spectra of Isomers for C78O
Authors: Teng Qi-wen , Wu Shi , Xie Ming-hua
Published: January 2011

The semi-empirical INDO method was used to study the electronic structures and the spectra of all of the 34 possible isomers of C78O based on C78 with group C2v. This calculation can simulate positions of an additional oxygen atom in C78 and predict the spectroscopic characteristics of the isomers. The most stable geometry of C78O is the 73,78-C78O molecule with an epoxide structure. The added 73,78-bond is located between two hexagons (66) and is intersected by the shortest C2 axis in C78 with group C2v. Atomic orbitals of the oxygen atom play an important role in lowering HOMO energy of 73,78-C78O. Compared with C78 with group C2v, the blue-shift in the electronic absorption spectrum for 73,78-C78O was observed. The reason of the blue-shift effect was discussed, and the electronic transitions were assigned based on the theoretical calculations.
Chemical Vapor Deposition Mechanism of Copper Films on Silicon Substrates
Authors: Wu Song , Tao Bo , Shen Yong-ping , Wang Qi
Published: January 2011

A versatile metal-organic chemical vapor deposition (MOCVD) system was designed and constructed. Copper ilms were deposited on silicon (100) substrates by chemical vapor deposition (CVD) using Cu(hfac)2 as a recursor. The growth of Cu nucleus on silicon substrates by H2 reduction of Cu(hfac)2 was studied by atomic force microscopy and scanning electron microscopy. The growth mode of Cu nucleus is initially olmer-Weber mode (island), and then transforms to Stranski-Rastanov mode (layer-by-layer plus island). The mechanism of Cu nucleation on silicon (100) substrates was further investigated by X-ray photoelectron spectroscopy. From Cu2p, O1s, F1s, Si2p patterns, the observed C=O, OH and CF3/CF2 should belong to u(hfac) formed by the thermal dissociation of Cu(hfac)2. H2 reacts with hfac on the surface, producing H. With its accumulation, OH reacts with hfac, forming HO-hfac, and desorbs, meanwhile, the copper xide is reduced, and thus the redox reaction between Cu(hafc)2 and H2 occurs.
Hydrothermal Synthesis of Exfoliative LDH in the Presence of Glycine
Authors: Li Bao-guang , Hu Yuan , Chen Zu-yao
Published: January 2011

Exfoliative Mg/Al layered double hydroxide (Mg/Al-LDHGly) was obtained via hydrothermal synthesis in he presence of glycine. The product prepared by hydrothermal reaction for 10 h at 120C possesses high hermal stability and maximal crystallite size in a, c directions. TEM and SEM analyses show that Mg/Al-LDHGly was of well-crystallized hexagonal product with stacks of slightly curved layers. Benefiting from echanism investigation on its gradual delamination in formamide, rapid delamination of Mg/Al-LDHGly at room temperature was realized, which provided fundamental for preparation of (Mg/Al-LDHGly)/polymer anocomposites by using exfoliation-adsorption method.
Study of Electroless Ni-P-CNTs Composite Plating
Authors: Kong Ji-lan , Zhou Shang-qi , Ren Qin , Zhang Xi
Published: January 2011

The electroless Ni-P-carbon nanotubes composite plating was studied on the copper substrate. Metallurgical microscope, scanning electronic microscope, X-ray diffractometer and micro hardness tester were used o study the structure, constitution and performance of the electroless Ni-P-carbon nanotubes composite deposit. Experiential results show that, with the increment of carbon nanotubes content in electroless plating solution, the grain size on the sample surface decreases whereas the density of grains and the hardness or composite deposit increases. Moreover, adding carbon nanotubes not only improves the degree of crystallization for the composite deposit but also helps their transformation from the amorphous state to the anocrystal state.
Influence of Different Surfactants on Morphology of Single Crystal Ce2O(CO3)2H2O and Formation Mechanism
Authors: Mei Yan , Han Ye-bin , Nie Zuo-ren
Published: January 2011

Three kinds of ultra-fine Ce2O(CO3)2H2O powders with different morphologies were prepared by adding CTAB, PEG19000 and OP-10 to a solution of Ce2O(NO3)36H2O and urea according to the principle and the characteristics of the homogeneous precipitation method. The products were characterized by TEM and XRD. The results showed that the precursor was a single crystal, and that different surfactants had different influences on the morphology of the products. The cationic surfactant CTAB had little effect on crystal morphology merely reducing its size. Nonionic surfactants PEG19000 and OP-10 are both able to change the crystal morphology to a much greater extent. Adding PEG19000 produces an array of rod-like particles with ordered formation and uniform dimension. Meanwhile, in the system of OP-10, a sort of flower-like pattern with a dispersed center can be prepared. The formations of ultra-fine Ce2O(CO3)2H2O powders with different morphologies occurred because of the mechanism of formation and grain growth.
Micro-structure of PECVD Diamond Films by Slow Positron Beam
Authors: Xu Yan , Weng Hui-min , Ye Bang-jiao , Wang Hai-yun , Peng Cheng-xiao , Xi Chuan-ying , Cheng Bin , Zhou Xian-yi , Han Rong-dian
Published: January 2011

The microstructure of diamond films was studied by slow positron beam and Raman spectroscopy. For the Raman spectroscopy experiment on diamond films, a high fraction of the sp3 hybridized bond was detected in samples. Positron annihilation spectra analysis further illuminated that the concentration and types of defects were different in each sample. S-E curves of all samples showed that diamond crystal structures had obvious variation in each sample. These results indicated that positron annihilation spectroscopy was an effective means to measure microstructure of diamond films.
UV and IR Studies on Heterofullerene C76BN
Authors: Wu Shi , Teng Qi-wen
Published: January 2011

Twenty-two possible isomers for C76BN were studied by INDO methods. The two most stable geometries are 52,53-C76BN and 29,28-C76BN, in which boron and nitrogen atoms are connected with each other and located at the 6/6 bond near the longest axis of C78(C2v). Electronic spectra of C76BN were investigated with INDO/SCI method. UV absorptions of C76BN are red-shifted compared with those of C78(C2v). The structures and IR spectra for the four stable isomers of C76BN were calculated by AM1 method. It was indicated that the substitution of the BN unit weakens the conjugation of carbon atoms, leading to the decrease of IR frequencies.
A Possible Form of NNS Distribution for Degenerate Spectra
Authors: Xiao Chang-ming , Zhao Nan-rong , Luo Jiu-li
Published: January 2011

To expose the statistical properties of the degenerated spectrum, with the aid of the random matrix theory, a possible form of the NNS distribution function of the degenerate spectrum was proposed by providing a solution in terms of the same-degeneracy case. The results indicate that the target spectrum is transformed into two sub-spectra: a random one and a regular one, and that the repulsion level of the regular spectrum is also decreased.
Simulation of Melting Behavior of the MgSiO3 Perovskite Under Lower Mantle Conditions
Authors: Liu Zi-jiang , Sun Xiao-wei , Yang Xiang-dong , Cheng Xin-lu , Guo Yun-dong
Published: January 2011

The melting curve of MgSiO3 perovskite was simulated using molecular dynamics method combining with the effective pair potentials under the lower mantle conditions. It was shown that the state equation simulated for MgSiO3 perovskite is very successful in reproducing accurately the experimental data over a wide range of pressure. The pressure dependence of the simulated melting temperature of MgSiO3 perovskite is in agreement with the recent experimental data. The melting curve simulated for MgSiO3 is very steep at pressures below 60 GPa first, then it becomes smooth with increasing pressure. At the core mantle boundary pressure 135 GPa, MgSiO3 perovskite melts at 6500 K, which is significantly lower than that of the extrapolations of the experimental data from Zerr and Boehler.
Molecular Dynamics Simulation of MgO Melting at High Pressure
Authors: Li Shou-yi , Liu Zheng-lai , Nan Ya-gong , Zhang Zhi-rong
Published: January 2011

Molecular dynamics simulation was used to study the melting of MgO at high pressures. The melting temperature of MgO was accurately obtained at elevated temperature and high pressure after corrections based on the modern theory of melting. The calculated melting curve was compared with the available experimental data and other theoretical results at the pressure range of 0-135 GPa. The corrected melting temperature of MgO is in good agreement with the results from Lindemann melting equation and the two-phase simulated results below 15 GPa.
Synthesis and Morphological Evolution of CuGaS2 Nanostructures via a Polyol Method
Authors: Liu Qiang-chun , Tang Kai-bin
Published: January 2011

Using ethylene glycol as solvent and reductant, CuCl22H2O, (NH2)2CS and self-prepared GaCl3 as the starting materials, CuGaS2 nanostrucutures were synthesized on a large scale at 220 C. Powder X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscope, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were used to characterize the products. It demonstrated the evolution of the CuGaS2 particles from spherical assemblies to flowerlike morphology, over time, at 220 C. Simultaneously, we elucidated the specific roles of reaction temperature, reaction time and solvent in the formation of the final CuGaS2 nanostructures. A possible formation mechanism of CuGaS2 nanostructures was also discussed. The room temperature photoluminescence spectrum showed blue-shift and an increase of intensity, with a decrease in the sizes of CuGaS2 particles.
Ordered Arrangement of Micro-beads in Single Line by Micromolding in Capillaries
Authors: Li Heng , Zhu Jian-hua , Shi Jin-xia , He Ping-sheng
Published: January 2011

An effective procedure was demonstrated to arrange spherical micro-beads into ordered, long, line-shape arrays by means of ``micromolding in capillaries'' in soft lithography. Polystyrene (PS) micro-beads with 2-3mm of diameter were used as units and arranged by molding in continuous micro-channels formed by the conformal contact between a glass substrate and an elastomeric stamp with micrometer-scale line patterns on the surface. An aqueous emulsion of PS micro-beads filled these channels by capillary action and was allowed to solidify. The stamp was then removed. The PS micro-beads could be assembled into a string of long line-shape arrays, and the strings were then joined by heating them to their softening temperature. In order to separate the PS micro-bead string from the substrate, the glass was covered with a thin layer of Al or polymethyl methacrylate. After the Al layer was dissolved, the string of PS micro-beads would be released. A string of micrometer scale PS beads can be used as a simple and direct ``model'' of a real macromolecular chain. It is hopeful to show an analogue with the condensed process of real macromolecules in a mesoscopic scale using the ``string of PS micro-beads''.
Preparation and Electrical Properties of (Ca, Mn)-codoped Ba1xSrxTiO3 Solid Solution
Authors: Liu Jun-sheng , Fan Guang-neng
Published: January 2011

(Ca, Mn)-codoped Ba1xSrxTiO3 (BST) solid solution, i.e. Ba0.4Sr0.5Ca0.08Mn0.02TiO3, was successfully synthesized via sol-gel process. The product was characterized by TG-DTA thermal analyses, XRD, TEM. The effects of both curing temperature and applied voltage on the resistance, etc. were investigated. It showed that the structure of BST was unable to be changed even though it was codoped by Ca2+ and Mn2+. TEM photographs demonstrated the influence of curing temperature on the morphologies of the tested samples. The dependence of resistance on the curing temperature illustrated that (Ca, Mn)-codoped BST was capable of exhibiting the positive temperature coefficient (PTC) effect at low frequency; nevertheless, it might display the negative temperature coefficient (NTC) effect at other frequencies. The relationships between the resistance and applied voltage revealed that the resistance property of (Ca, Mn)-codoped BST appeared at low frequencies, but its property of capacitive reactance might present at high frequency. These findings mean that the electrical property of BST can be adjusted by codoping method. These phenomena can be explained by the grain boundary resistance effect, Heywang model and ion polarization theory.
Ab initioStudy of Radical-Molecule Reaction: F+CH2CHCH3
Authors: Wang Ling , Wang Xiu-yan , Yang Xue-ming
Published: January 2011

The radical-molecule reaction F+propene (CH2CHCH3) was studied in detail by using the Becke's three parameter Lee-Yang-Parr-B3LYP/6-311G(d,p) and coupled cluster with single, double, and triple excitations-CCSD(T)/6-311+G(2d,2p). It is shown that F+propene reaction mainly occurs through complex-formation mechanism: F attacks the double bond of propene leading to the formation of complex 1 and complex 2. As the two radical complexes are metastable, they can quickly dissociate to H+C3H5F, CH3+C2H3F and HF+C3H5. Based on the ab initio calculations, the CH3+C2H3F is the main channel, and the H elimination and HF forming channels also provide some contribution to products. The calculated values are in good agreement with the recently reported experimental results.
Theoretical Studies on Structures and Relative Stability for Polynitrohexaazaadamantanes
Authors: Xu Xiao-juan , Xiao He-ming , Wang Gui-xiang , Ju Xue-hai
Published: January 2011

The density function theory at the B3LYP/6-31G* level was employed to study the structures, including the total energies (EZPE), the geometries, the oxygen balances (OB100), the dipole moments, of polynitro-hexaazaadamantanes (PNHAAs) and the potential candidates of high energy density compounds (HEDCs). The structural parameters of PNHAAs, such as the the maximum NNO2 bond length (LBmax), the least NN Mulliken population (BNN), the least negative charge on the nitro group (QNO2) and OB100, were studied to predict their relative stability or sensitivity (the easiness for initiating a detonation, high sensitivity means low stability). It was found that the same conclusion was drawn from the four parameters. With the number of nitro groups increasing, the stabilities of these compounds decrease. OB100 failed in identifying the isomers, but the EZPE energy and the dipole moment were considered to give more reliable results for the isomers.
DFT Study on the Intermolecular Substrate-mediated Interaction Energy in the Self-assembly of Alkanethiols on Silver
Authors: Xie Rong , He Tian-jing , He Li , Chen Dong-ming , Liu Fan-chen
Published: January 2011

The B3LYP/LanL1MB and B3LYP/LanL2DZ methods for Ag atom in conjunction with the 6-31G(d) basis set for S, C and H atoms were used to optimize the geometries and calculate the energies for (SCH3)mAg20 (m=1-4), respectively. A single molecular adsorption energy of (SCH3)m (m=1-4) on Ag20 and the inter-molecular substrate-mediated interaction energy were evaluated. The results revealed that there is a proportional relation between the single molecular adsorption energy and the substrate-mediated intermolecular interaction energy. The results qualitatively demonstrated the semi-empirical expression for the substrate-mediated interaction energy proposed previously by us is consistent with the results of the density functional theory.
Theoretical Research on Scattering Resonance States of Reaction I+HI(=0)IH(=0)+I: Partial Potential Energy Surface and One-dimensional Quantum Reactive Scattering Calculation
Authors: Wang Hua-yang , Sun Xiao-min , Cai Zheng-ting , Feng Da-cheng
Published: January 2011

Based on the vibrational potential curves coupled with the minimum energy reaction path, the partial potential energy surface of the reaction I+HIIH+I was constructed at the QCISD(T)//MP4SDQ level with pseudo potential method. And the formation mechanism of the scattering resonance states of this reaction was well interpreted with the partial potential energy surface. The scattering resonance states of this reaction should belong to Feshbach resonance because of the coupling of the vibrational mode and the translational mode. With the one-dimensional square potential well model, the resonance width and lifetime of the I+HI(=0)IH(=0)+I state-to-state reaction were calculated, which preferably explained the high-resolved threshold photodetachment spectroscopy of the IHI anion performed by Neumark et al..
Crystal Structure of 3S-hydroxy-7 Melleine
Authors: Liu Xiao-hong , Xu Fang , Zhang Yi , Liu Li-hong , Huang Hua-rong , She Zhi-gang , Lin Yong-cheng , Chan Winglai
Published: January 2011

A new compound, 3S-hydroxy-7 melleine was isolated from the endophytic fungus Xylariasp No.2508 from the mangrove tree on the South China Sea coast. It was the first time that this kind of compound was isolated from marine fungus. The structure was elucidated by NMR data, infrared spectrum (IR) and mass spectrometry (MS). In addition, its structure was determined by the single-crystal X-ray diffraction analysis. It crystallized in monoclinic, space group P21 with a=10.8884(19) , b=7.2284(13) , c=13.398(2) , =104.217(3), C10H10O4H2O, Mr=212.20, V=1022.2(3) 3, Z=4, Dc=1.379 mg/m3, F(000)=448, =0.112 mm-1, the final R=0.0498, R=0.101 for 2407 observed reflections (I>2(I)). The molecular backbone of the compound includes a benzopyran ring. By comparing with the melting point and the optical rotation of the known 3R-hydroxy-7 melleine in literature, the absolute configuration of the compound was determined as 3S. It didn't exhibit antibacterial activity against Gram-positive bacterium Staphylococcus aureus at 200 g/disk in the preliminary test.
Interactions of 1-hexyl-3-methylimidazolium Bromide with Acetone
Authors: Zhai Cui-ping , Wang Jian-ji , Xuan Xiao-peng , Wang Han-qing , Chen Miao
Published: January 2011

1H and 13C NMR chemical shifts were determined to investigate the interactions of acetone with a room temperature ionic liquid 1-hexyl-3- methylimidazolium bromide [C6mim]Br at various mole fractions. Changes in chemical shifts of hydrogen nuclei and of carbon nuclei with the acetone concentration indicated the formation of hydrogen bond between anion of the ionic liquid and methyl protons of acetone. The NMR results were in good agreement with the ab initio computational results.
Theoretical Study on the Reaction Mechanism of CH2F Radical with HNCO
Authors: Li Lai-cai , Shang Jing , Liu Jun-ling
Published: January 2011

The reaction mechanism of CH2F radical with HNCO was investigated by density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. The geometries of the reactants, the intermediates, the transition states and the products were optimized. The transition states were verified through the vibration analysis. The relative energies were calculated at the QCISD(T)/6-311++G**//B3LYP/6-311++G(d,p) level. Seven feasible reaction pathways of the reaction were studied. The results indicate that the pathway (5) is the most favorable to occur, so it is the main pathway of the reaction.
Effect of Cobalt Precursor on Microstructures and Visible Light Photoactivity of Doped TiO2 Powders
Authors: Shi Jing-ying , Leng Wen-hua , Cao Jiang-lin , Zhang Jian-qing , Cao Chu-nan
Published: January 2011

In order to develop photoactive cobalt-doped TiO2 for the degradation of organic pollutants using visible light irradiation, the effects of cobalt precursor on TiO2 microstructure were investigated. Three cobalt-precursors, i.e. CoCl2, Co(NO3)2 and CoSO4 with two doping levels (nominally 1% and 10%), and two annealing temperatures (400 and 800 C) were adopted to prepare the doped titania through the sol-gel method. The powder samples were characterized with XRD, SEM, BET surface area analysis and UV-Vis absorption spectroscopy, and their photocatalytic activities were evaluated by the degradation of aniline under visible light irradiation. The results showed that the distribution of titania phases, particle size, morphology, surface area and the optical absorption of the catalysts were greatly dependent on the cobalt precursors. Samples prepared from Co(NO3)2, especially for those doped at 1% and calcined at 400 C, showed the highest photocatalytic activity towards the degradation of aniline, and the possible reasons are discussed briefly.
Vibrational Spectra of Nonrigid Molecule HCP in an Algebraic Model
Authors: Hou Xi-wen , Qiao An-qin , Cheng Chuan-ming
Published: January 2011

An algebraic Hamiltonian for the two coupled nonlinear vibrations of highly excited nonrigid molecule HCP was presented. The Hamiltonian reduces to the conventional one in a limit which was expressed in terms of harmonic oscillator operators. It showed that the algebraic model can better reproduce the data than the conventional model by fitting the observed data of HCP.
Two-dimensional ATR-FTIR Spectroscopic Study on the Water Diffusion Behavior in Polyimide/Silica Nanocomposite
Authors: Shen Yi , Wang Hai-tao , Zhong Wei , Wu Pei-yi
Published: January 2011

To consider the reliability and performance of electronic devices based on polyimide derivatives, dynamic water sorption and diffusion behavior in a polyimide derivative: poly(4'4-oxydiphenylene pyromellitimide) (PMDA-ODA)/silica nanocomposite was investigated by two-dimensional ATR-FTIR spectroscopy, by which three states of water molecules owning different H-bonding strength were distinguished. The amounts and strength of H-bonding also played a significant role in determining the diffusion rate of the different states of water molecules. The type of aggregated water molecules which also formed H-bonding with silicic acid (residues) or polyimide system was the last one diffusing to the polymer side in contact with the ATR crystal element because the polymeric matrix blocked their diffusion to a great extent. The diffusion coefficient was also estimated to gain the information of the dynamic diffusion behavior.
DFT Investigation of O2 Adsorption on Si(001)-(221):H
Authors: Deng Xiao-yan , Yang Chun , Zhou Ming-xiu , Yuc Wei-fei , Li Jin-shan
Published: January 2011

A novel model was developed to theoretically evaluate the O2 adsorption on H-terminated Si(001)-(221) surface. The periodic boundary condition, the ultrasoft pseudopotentials technique based on density functional theory (DFT) with generalized gradient approximation (GGA) functional were applied in our ab initio calculations. By analyzing bonding energy on site, the favourable adsorption site was determined. The calculations also predicted that the adsorption products should be Si=O and H2O. This theoretical study supported the reaction mechanism provided by Kovalev et al. The results were also a base for further investigation of some more complex systems such as the oxidation on porous silicon surface.
Self-diffusion Coefficient Model Based on Activation Energy and Free Volume
Authors: Yin Xiao-yong , Song Hai-hua
Published: January 2011

A new model for self-diffusion coefficients was proposed based on both the concepts of molecular free volume and activation energy. The unknown parameters of this model were clearly defined and compared with the Chapman-Enskog model. At the same time a new method for calculating activation energy was devised and applied to the new model. In addition, the free volume was defined by implementing the generic van der Waals equation of state, the radial distribution function of which was obtained by using the Morsali-Goharshadi empirical formula. Under the same conditions, the new model was better than the original free volume model.
Physical and Electrochemical Characterization of LiCo0.8M0.2O2 (M=Ni,Zr) Cathode Films for All-solid-state Rechargeable Thin-film Lithium Batteries
Authors: Li Chi-lin , Liu Wen-yuan , Fu Zheng-wen
Published: January 2011

LiCo0.8M0.2O2 (M=Ni,Zr) films were fabricated by radio frequency sputtering deposition combined with conventional annealing methods. The structures of the films were characterized with X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM) techniques. It was shown that the 700C-annealed LiCo0.8M0.2O2 has an -NaFeO2-like layered structure. All-solid-state thin-film batteries (TFBs) were fabricated with these films as the cathode and their electrochemical performances were evaluated. It was found that doping of electrochemically active Ni and inactive Zr has different effects on the structural and electrochemical properties of the LiCoO2 cathode films. Ni doping increases the discharge capacity of the film while Zr doping improves its cycling stability.
Ultrasonic Study on Charge Ordering in Nd0:5Ca0:5Mn1xAlxO3 (x=0,0.03)
Authors: Liu Yi , Kong Hui , Su Jin-rui , Zh Chang-fei
Published: January 2011

The ultrasonic, magnetic and transport properties of Nd0:5Ca0:5Mn1xAlxO3 (x=0,0.03) were studied from 15 to 300 K. The temperature dependencies of resistivity and magnetization show that Nd0:5Ca0:5MnO3 undergoes a charge ordering transition at TCO 257 K. An obvious softening of the longitudinal sound velocity above TCO and a dramatic stiffening below TCO accompanied by an attenuation peak were observed. These features imply a strong electron-phonon interaction via the Jahn-Teller effect in the sample. Another broad attenuation peak was observed at around Tp 80 K. This anomaly is attributed to the phase separation between the antiferromagnetic (AFM) and paramagnetic (PM) phases and gives a direct evidence for spin-phonon coupling in the compound. For the x=0.03 sample, both the minimum of sound velocity and attenuation peaks shift to a lower temperature. The results indicate that the charge ordering and CE-type AFM state in Nd0:5Ca0:5MnO3 are both partially suppressed by replacing Mn with Al.