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This paper investigates the morphological stability of epitaxial films growing heteroepitaxially on ultra-thin substrates. The misfitting strain model is incorporated into the quasi-static mechanical equilibrium system. The interfacial evolution equation between the vapour and film phases is used to solve the film evolution. The perturbation method of normal modes is used to derive the analytical form of the normal-mode growth rate. Additionally, this paper investigates the dynamic behaviour of the vapour–film interface. The results of the study show that a decrease in substrate thickness tends to stabilize the system regardless of whether the stiffness ratio, ρ (i.e. the ratio of film stiffness to substrate stiffness) is less than, equal to or greater than unity. Furthermore, it is found that the effects of a finite substrate thickness on the stability behaviour of the system are quite profound, and that this is particularly true when the film thickness is close to hc with values of stiffness ratio greater than unity.

This paper employs a dual damascene simulation to study the filling mechanisms of a dual via for the ionized physical vapor deposition (IPVD) process. The study focuses principally upon the influence of incident atom energy and via geometry upon the final dual via coverage. Additionally, the improvement in coverage which results from the use of beveled edges within the via is also considered. The molecular dynamics (MD) method is employed to simulate the filling process. The simulation is based upon three MD models, namely the dual via model, the deposition model and the potential model. Furthermore, the simulation incorporates the thermal control layer marching algorithm in order to increase the accuracy of the solution and to reduce the computational time. The results of the study show that in general, the coverage of both vias improves as the incident energy of the deposited atom increases, i.e. the filling pattern changes from anti-conformal to conformal, and then finally to super-filling as the incid...

The goal of this special issue is to provide the platform for international discussion and exchange of information/ experience on the simulation of phenomena in and characteristics of materials at macroscopic and mesoscopic scales. In particular, these publications are the exhibitions and wide materials science and engineering of innovative, improved, and elegant research in macroscopic and/or mesoscopic computational materials science and engineering, containing the most advanced mathematical modeling methods and numerical methodology developments. For the sake of investigation of phenomena in materials science modeling and engineering at the macroscopic and mesoscopic scales, several powerful numerical tools, including first principle calculations, quantum molecular dynamics, molecular dynamics and molecular mechanics simulations, Monte Carlo method, finite element method, finite difference method, finite volume method, spectral element method, boundary element method, and computational fluid dynamics, are employed. Meanwhile, these tools are also applied on the research of materials (fluids, metals, polymers, rocks, ceramics, composites, biomaterials, nanomaterials, etc.), their structures (functional solids, soft matter, multiphase materials, tribology, coatings, etc.), and their characteristics (thermal, electronic, energetic, physical, structural, chemical, magnetic, or optical properties or a complicated combination of any of these properties). The analytical and numerical analyses and results of functional elements of these materials constitute the main and outstanding highlights of this special issue; moreover, important computational studies of others aspects also are brilliant and impressive, such as imperfections in materials and their resulting limitations, novel processes for advanced materials synthesis, engineering of material properties, environmental consideration in material performance, and solid materials on sintering/melting process during three-dimensional printing. It enables interdisciplinary collaboration between science and engineering technologists in the academic and industrial fields.

Appreciable 14N/15N equilibrium isotope effect has been observed for the electron-transfer process between N,N,N‘,N‘-tetramethyl-p-phenylenediamine (TMPD) and its radical cation perchlorate (TMPD+•...

Using time resolved Fourier transform EPR spectroscopy the photoreduction of duroquinone by triethylamine in methanol solution was investigated. It is found that the spin-polarized (CIDEP) duroquinone triplet deactivates by electron transfer from triethylamine generating duroquinone radical anion and amine radical cation, and by hydrogen transfer from the solvent generating durosemiquinone radical and hydroxymethyl radical, respectively. All radicals are observed at different conditions and are spin-polarized by triplet mechanism and partially by ST0 radical pair mechanism. The time dependence of FT-EPR intensities of radical cation and radical anion on the amine concentration is investigated in the range of 1 to 100 mM triethylamine. The contribution of the triplet mechanism to the spin polarization of radicals changes with different triethylamine concentrations. The durosemiquinone radical is found to be transformed into duroquinone radical anion in the presence of triethylamine in the solution. CIDNP experiments indicate that the hydrogen back transfer between the durosemiquinone radical and hydroxymethyl radical pair has a significant influence on the time behaviour of duroquinone radical anion. The intensity of triethylamine radical cation is found to be decreased with the increase of triethylamine concentration, which is interpreted that the triethylamine radical cation is deprotonated by the amine. Based on the FT-EPR results, a new complete mechanism is proposed.

Appreciable equilibrium isotope effects have been observed for electron-transfer process between N-methylphenothiazine (MPT) and the radical cation of its 15N- and/or N−13C-methyl-substituted analo...

To study the protective effect and preliminary mechanisms of asiatic acid against oxygen-glucose deprivation/reoxygenation (OGD/R) injury of PC12 cells, Na2S2O4 combined with low glucose induced damage of PC12 cells was served as OGD/R injury model in vitro. MTT method was used to evaluate cell survival. Ultraviolet spectrophotometry was performed to determine lactate dehydrogenase (LDH) leakage, lactic acid (LD) content, intracellular superoxide dismutase (SOD), malonyldialdehyde (MDA), and cellular Caspase-3 activity. Flow cytometry was applied to assay cell apoptosis. Na2S2O4 combined with low glucose induced significant cell survival rate decreasing compared with normal cells. Cell survival rate increasing, LDH leakage alleviating, LD producing inhibiting, SOD activity promotion, MDA content reducing, cell apoptotic rate decreasing and Caspase-3 activity inhibiting were observed when cells were preincubated with different concentration of asiatic acid (10, 1 and 0.1 micromol x L(-1)). Evident protective effect of asiatic acid against OGD/R injured PC12 cells was verified in our experiment, and the possible mechanisms were related to eliminating free radicals and inhibiting cell apoptosis.

An appreciable equilibrium isotope effect has been observed for electron transfer from phenothiazine (PT) to the radical cation of its N-15 substituted analogue ([N-15]PT+.), i,e, PT+[N-15]PT+.K reversible arrow PT+.+[N-15]PT via electron paramagnetic resonance analysis of the mixed radical cations formed from mixing the [N-15]phenothiazlne radical cation hexachloroantimonate and phenothiazine in acetonitrile (K=0.77+/-0.10 at 25 degrees C), and by physical separation of the neutral phenothiazines from the radical cation salts in the equilibrium mixture (K=0.83+/-0.10 at 25 degrees C), Infrared and Raman spectra of [N-14]- and [N-15]phenothiazines and their radical cations were measured to assign the vibrational frequency shifts caused by the heavy-atom substitution and radical cation formation, which gave an estimate of the enthalpy change of 441.7 J mol(-1) for the electron transfer process. These results reveal that N-15 substitution of phenothiazine decreases appreciably the ionization potential of the molecule, making it easier to lose an electron to form the corresponding radical cation in solution. (C) 1997 by John Wiley & Sons, Ltd.

Zinc telluride (ZnTe) compound is one of the attractive elements of the II–VI group also having wide range of applications such as switching devices, light-emitting diode, solar cells and photodetectors. In this paper, the microstructure and electrical properties of znic telluride thin films were studied by using thermal-furnace evaporation with emphasis on the effects of argon pressure and deposition temperature. Crystallinity, mobility, carrier concentration and sheet resistance are shown to be dependent on the argon pressure and deposition temperature. The grain size was increased with increasing the annealing temperature and decreasing the argon pressure. The highest carrier concentration of 1.9×10 16 cm -3 , the lowest sheet resistance of 3180 Ω/ and the largest mobility of 5.1×10 3 cm 2 V -1 S -1 are presented at an argon pressure of 100°sccm and a deposition temperature of 580°C, respectively.

A planar octagon monopole UWB band-notched antenna is proposed and experimentally studied. It consists of an octagon patch with a modifed U-shaped notched, which intends to obtain frequency notched for WiMAX. The proposed antenna operates from 1.93 GHz to 11 GHz for return loss of less than -10dB with 5.26-6.4 GHz notched. The notch frequency of the proposed antenna can be adjusted by controlling the location of slot. The measured results are in reasonably good agreement with the simulated results. Details of the proposed antenna design and simulation results for UWB operations are presented and discussed.

The configurations and corresponding adsorption energies of Rh(n) (n = 4-13) nanoclusters on the boron nitride sheet are investigated by density functional theory (DFT). We use the force-matching method (FMM) to modify parameters of Morse and Tersoff potential functions. To elucidate the dynamical behaviors of Rh nanoclusters on the boron nitride sheet, molecular dynamics (MD) is applied with modified Morse potential function parameter. Finally, the square displacement (SD) is utilized the dynamics behavior of different size Rh nanoclusters at different temperatures.

The coupled extended Reynolds (which includes the effects of Navier-slip and flow rheology), elasticity deformation, and the load equilibrium (under a constant load condition) equations are solved simultaneously for the EHL problems. Results show that as the slip length increases or the flow index decreases, the film thickness decreases, the central pressure increases, the pressure spike decreases, the maximum pressure switches from the pressure spike to the central pressure, and the film shape and pressure profiles moves gradually toward the outlet. A proper combination of flow rheology and slip length could fulfill some preferred EHL conditions.

This paper proposed the pyramid microstructure (PYM) used on the base of the light guide as the micro-optical components to replace the conventional diffuser dot made by direct etching on the steel stamper. The PYM is made by MEMS technology, which uses silicon wafer as original mold of PYM and to replicate it on Ni micro-mold by using electroforming method. The effective optical design tool is used to find the optimal distribution of the PYM, which integrates the random microstructure generation scheme developed based on the molecular dynamics method and the optical commercial software. The SEM images show the intact PYM can be produced on the Si micro-mold and replicated fully on the Ni micro-mold by the electroforming process. The intact PYM on the base of the light guide can also be produced by the injection molding showing the complete transformation of the Ni micro-mold to the light guide. The luminance measurement of a 2.4 inches backlight module with 4 LEDs shows the average luminance of 4769 nit with 86.3% uniformity for the PYM on the base of light guide, which is 10% higher than that for the diffuser dot microstructure.

Infrared and resonance Raman spectra of thianthrene (Th), perdeuteriated thianthrene ([2H8]Th) and their radical cation perchlorates (Th˙+ClO–4 and [2H8]Th˙+ClO–4, respectively) have been measured. Comparison of the frequency shifts caused by the perdeuteriation and the radical cation formation of thianthrene enables evaluation of the free energy change of 137 cal mol–1 for the electron-exchange equilibrium Th +[2H8]Th˙+⇌ Th˙++[2H8]Th.

Based on analysis of matter-element theory applied in water quality assessment, enterprise competitiveness evaluation, human resource evaluation, and power quality evaluation, this paper put the theory into electricity services management and constructed an electricity supply service quality evaluation index system for the matter-element analysis model with combination of relevant research results. Then, through an example of quality grading, matter-element analysis model construction, correlation function calculated, weight calculated, and degree of membership determined to illustrate the validity of the theory. Analysis indicates that the matter-element theory applied to evaluate the power quality of service is effective, and has an objective and comprehensive characteristics of the evaluation results.

Dynamical behavior of water confined inside a capped single-walled carbon nanotube (SWCNT) is investigated at different temperatures via the Molecular Dynamics (MD) Simulation method. Water in a SWCNT behaves in the fashion of random walk and increases amplitudes with temperature. Moreover, the SWCNT’s tip vibrates more significantly as temperature increases. The water molecules embedded nanotubes exhibit less thermal noise amplitude, indicating increases in effective stiffness in the water-nanotube composite. Further, the vibrational amplitude of a water-embedded SWCNT’s tip is more noticeable during the initial transient state at the beginning of our MD simulations, and gradually decays, and reaches a steady state, as MD simulation time increases. The variation of vibrating amplitude of the SWCNT’s tip increases linearly as temperature increases when no water is present inside. The tip vibration exhibits the largest amplitude when temperature is at the boiling point of water. Moreover, the tip vibration increases monotonically as temperature increases, providing information to estimate the effective Young’s modulus of the water-nanotube composite. The diffusion pathways of water inside a SWCNT are also studied in terms of temperature changes.Copyright © 2008 by ASME

Analysis System for Bridge Test (Chinese name abbr.: QLJC) is an application software specially designed for bridge test to analyze the static and dynamic character of bridge structures, calculate efficiency ratio of load test, pick up the results of observation points and so on. In this paper, research content, system design, calculation theory, characteristics and practical application of QLJC is introduced in detail.

In the present study, DNA typing for HLA-DRB1, DQB1 and DPB1 was performed using polymerase chain reaction-sequencing based typing (PCR-SBT) method in 144 random selected Jing ethnic individuals inhabiting in South China. Allele frequencies and two-locus haplotypes (DRB1-DQB1) were statistically analyzed and 20 DPB1 alleles, 27 DRB1 and 20 DQB1 were detected. The most frequent DPB1 allele was DPB1*0501 with the percentage of 36.9% followed by DPB1*1301 (15.7%), DPB1*0401 (11.0%) and DPB1*020102 (9.8%). Among the 27 detected DRB1 alleles, DRB1*120201 (13.8%) was most commonly observed followed by DRB1*150201, *030101 and *090102 alleles with the frequencies of 9.4%, 9.1% and 8.3%, respectively. Among the 20 detected DQB1 alleles the most predominant one was DQB1*030101/0309 (19.9%). DQB1*050201 (19.1%), DQB1*0201/0202 (16.1%) and DQB1*050101 (12.3%) were also frequently observed in Jing population. Statistical analysis of two-locus haplotypes showed that DRB1*120201-DQB1*030101/DRB1*120201-DQB1*0309 (HF = 9.4%, D = 6.65x10(-2)) was most predominant followed by DRB1*030101-DQB1*0201/DRB1*030101-DQB1*0202 (HF = 8.1%, D = 6.66 x 10(-2)). The comparison of HLA class II allele and haplotype frequencies in Jing with those in other populations all over the world and a dendrogram based on the DRB1, DQB1 and DPB1 genes suggested that Jing ethnic population has an origin of Southeast Asia and is belonged to the southern group of Chinese populations.

The most stable structures of three ultrathin tungsten nanowires were predicted by the simulated annealing basin-hopping method (SABH) with the penalty algorithm. The predicted structures of tungsten nanowires indicate the tungsten nanowires at this small scale do not possess the B.C.C. configuration in bulk tungsten material. By molecular dynamics (MD) simulation, the mechanical properties including the Young's modulus, yielding stress, and strength of these wires were determined by the tensile test after the analysis of the stress–strain profiles. Besides, in order to understand the feasibility of application of tungsten nanowire on nanodevices, the thermal stability of these ultrathin tungsten nanowires was also investigated at room temperature (300 K) by molecular dynamics (MD).

Water decomposition process was investigated by ab initio molecular dynamic simulations using a model of (H(2)O)(2)(+) clusters. The proton transfer (PT) process from the cationic H-donor water to the H-acceptor water for the formation of (HO˙)·H(3)O(+) was predicted as about 90 fs on average calculated at CCSD level of theory. The valence-electron transfer (VET) process through the formation of hemibond interaction between neutral and cationic water, (H(2)O)(2)(+), was also identified in several collected trajectories. Both PT and VET processes were found to propagate along two orthogonal reaction coordinates, the former was through an intermolecular hydrogen bond and the latter required oxygen-oxygen hemibonding. Significant difference of the theoretical electronic transitions along the VET trajectories was also observed in comparison with the non-VET cases, being calculated at SAC-CI level. The strong absorption features of hemibonding (H(2)O)(2)(+) may introduce an interesting consideration for experimental design to monitor the water decomposition process.

We propose a recessed pyramid microstructure (PYM) to be used on the base of the light guide as micro-optical components to replace the conventional diffuser dot made by direct etching on the steel stamper. The PYM is made by microelectromechanical systems technology, which uses a silicon wafer for the original PYM mold, which is replicated on a Ni micromold using the electroforming method. An effective optical design tool is used to find the optimal PYM distribution integrating the random microstructure generation scheme based on the molecular dynamics method into optical commercial software. The scanning electron microscopy images show intact PYMs can be produced on the Si micromold and then replicated fully on the Ni micromold by the electroforming process. An intact PYM on the base of the light guide can then be produced by injection molding, completing the transformation of the Ni micromold for use in the light guide. The luminance measurement of a 2.4-in. backlight module with four LEDs shows an average luminance of 4769 nit with 86.3% uniformity for the PYM on the base of light guide, 10% higher than that of the diffuser dot microstructure.

This paper studies the buckling phenomena and mechanical behavior of single-walled carbon nanotubes (SWNTs) and double-walled carbon nanotubes (DWNTs) via molecular dynamics simulations. The Tersoff interatomic C–C potential is adopted. Using a dimensionless parameter, slenderness ratio (SR, the ratio of length to diameter), we investigate the mechanical behavior of long and short nanotubes under compression through their buckling modes, total strain energy and strain energy density, as well as post-buckling. The curvatures of strain energy provide a means to measure the Young’s modulus of the nanotubes. Moreover, jumps in either the strain energy or strain energy density indicate identical mechanical buckling strains, and are studied in relation to buckling modes. In our simulations, a transition time is observed for short nanotubes to reach stable vase-like buckling mode, indicating a time-dependent property of nanotubes. Furthermore, nanotubes with small SR can bear higher compressive load after their first buckling. In addition, nanotubes with same chirality exhibit roughly the same elastic modulus, regardless of their lengths, when applied compressive strains are less than 5% strain. However, long nanotubes show smaller buckling strength. Effects of temperature at 300 K on buckling strength for SWNT are also discussed in connection to our present study at 1 K.

The low-energy electronic states and energy gaps of carbon nanocones in an electric field are studied using a single-π-band tight-binding model. The analysis considers five perfect carbon nanocones with disclination angles of 60°, 120°, 180°, 240° and 300°, respectively. The numerical results reveal that the low-energy electronic states and energy gaps of a carbon nanocones are highly sensitive to its geometric shape (i.e. the disclination angle and height), and to the direction and magnitude of an electric field. The electric field causes a strong modulation of the state energies and energy gaps of the nanocones, changes their Fermi levels, and induces zero-gap transitions. The energy-gap modulation effect becomes particularly pronounced at higher strength of the applied electric field, and is strongly related to the geometric structure of the nanocone.

A moire topographic instrument has been successfully used in a clinic for making topograms of the living body. This instrument has three optical advantages: (1) its sensitivity can be adjusted; (2) the gratings adopt a suitable depth and the measurable depth is 150 mm; (3) it has smooth grating lines with outfocusing for eliminating noise. Eighty-five percent of the moire topograms of a scoliotic patient agree with the x rays.

A moire topographic model of a living body has been successfully used in clinical studies. This model has three optical advantages: its sensitivity can be adjusted; the measurable depth is very large (~150 mm); smooth grating lines with outfocusing eliminate the noise. This moire topographic method has demonstrated an 88% conformation with x-ray diagnoses. The forward bending test was also used, and a conformation rate of 64% was obtained. (About 5000 children were examined.)