Domain with Noncompactified Extra Dimensions in the Multidimensional Universe with Compactified Extra Dimensions

It is argued that in our Universe with compactified extra dimensions (ED) also domains exist with noncompactified ED. The multidimensional gravity (MD) on the principal bundle with structural group SU(3) is considered and a spherically symmetric solution in this theory is obtained. This solution is a wormhole-like object located between two null surfaces ds² = 0 and can be considered as a domain with noncompactified ED which is sewn to a 4D spacetime with compactified ED. In some sense these solutions are dual to black holes: they represent static spherically symmetric solutions under null surfaces, whereas black holes are static spherically symmetric solutions outside the event horizon.     

Induced growth of asymmetric nanocantilever arrays on polar surfaces

We report that the Zn-terminated ZnO (0001) polar surface is chemically active and the oxygen-terminated (000(-)1) polar surface is inert in the growth of nanocantilever arrays. Longer and wider "comblike" nanocantilever arrays are grown from the (0001)-Zn surface, which is suggested to be a self-catalyzed process due to the enrichment of Zn at the growth front. The chemically inactive (0001;)-O surface typically does not initiate any growth, but controlling experimental conditions could lead to the growth of shorter and narrower nanocantilevers from the intersections between (000(-)1)-O with +/- (01(-)10) surfaces.     

A comparative study of the electrodeposition and the aqueous chemical growth techniques for the utilization of ZnO nanorods on p-GaN for white light emitting diodes

Vertically well aligned zinc oxide nanorods (ZnO NRs) were grown on p-GaN by electrodeposition (ED) and aqueous chemical growth (ACG) techniques and the structures were employed to fabricate white light emitting diodes (LEDs). Room temperature current voltage (I–V$I–V$), photoluminescence (PL), and electroluminescence (EL) measurements were performed to investigate and compare both LEDs. In general, the I–V$I–V$ characteristics and the PL spectra of both LEDs were rather similar. Nevertheless, the EL of the ED samples showed an extra emission peak shoulder at 730 nm. Moreover, at the same injection current, the EL spectrum of the ED light emitting diode showed a small UV shift of 12 nm and its white peak was found to be broader when compared to the ACG grown LED. The broadening of the EL spectrum of the LED grown by ED is due to the introduction of more radiative deep level defects. The presented LEDs have shown excellent color rendering indexes reaching a value as high as 95. These results indicate that the ZnO nanorods grown by both techniques possess very interesting electrical and optical properties but the ED is found to be faster and more suitable for the fabrication of white LEDs.     

Measurement of the Casimir force between a gold sphere and a silicon surface with nanoscale trench arrays

We report measurements of the Casimir force between a gold sphere and a silicon surface with an array of nanoscale, rectangular corrugations using a micromechanical torsional oscillator. At distances between 150 and 500 nm, the measured force shows significant deviations from the pairwise additive formulism, demonstrating the strong dependence of the Casimir force on the shape of the interacting bodies. The observed deviation, however, is smaller than the calculated values for perfectly conducting surfaces, possibly due to the interplay between finite conductivity and geometry effects.     

Geodesic length spectrum on compact Riemann surfaces

In this paper we use techniques linking combinatorial structures (symbolic dynamics) and algebraic–geometric structures to study the variation of the geodesic length spectrum, with the Fenchel–Nielsen coordinates, which parametrize the surface of genus τ=2$\tau =2$. We explicitly compute length spectra, for all closed orientable hyperbolic genus two surfaces, identifying the exponential growth rate and the first terms of a growth series.     

Polymer-mediated and ultrasound-assisted crystallization of ropivacaine: Crystal growth and morphology modulation

The objective of this research was to modify the crystal shape and size of poorly water-soluble drug ropivacaine, and to reveal the effects of polymeric additive and ultrasound on crystal nucleation and growth. Ropivacaine often grow as needle-like crystals extended along the a-axis and the shape was hardly controllable by altering solvent types and operating conditions for the crystallization process. We found that ropivacaine crystallized as block-like crystals when polyvinylpyrrolidone (PVP) was used. The control over crystal morphology by the additive was related to crystallization temperature, solute concentration, additive concentration, and molecular weight. SEM and AFM analyses were performed providing insights into crystal growth pattern and cavities on the surface induced by the polymeric additive. In ultrasound-assisted crystallization, the impacts of ultrasonic time, ultrasonic power, and additive concentration were investigated. The particles precipitated at extended ultrasonic time exhibited plate-like crystals with shorter aspect ratio. Combined use of polymeric additive and ultrasound led to rice-shaped crystals, which the average particle size was further decreased. The induction time measurement and single crystal growth experiments were carried out. The results suggested that PVP worked as strong nucleation and growth inhibitor. Molecular dynamics simulation was performed to explore the action mechanism of the polymer. The interaction energies between PVP and crystal faces were calculated, and mobility of the additive with different chain length in crystal-solution system was evaluated by mean square displacement. Based on the study, a possible mechanism for the morphological evolution of ropivacaine crystals assisted by PVP and ultrasound was proposed.     

Statistical properties of a single-mode laser driven by additive and multiplicative coloured noises with a coloured cross-correlation for different correlation times

We study a system for a single-mode laser driven by additive and multiplicative coloured noises with a coloured cross-correlation. The analytical expression of the stationary intensity distribution (SID) for the laser is derived in the case of three different correlation times. The influences of each stochastic parameter on the SID are discussed, the effects of the noise "colour" and the cross-correlation of noises on the mean intensity , the variance, λ_2(0), and the skewness,λ_3(0) of the single-mode laser are investigated. We find that there are colourful phase transitions for the SID above a threshold, and re-entrant transitions induced by the "colour" of the additive noises. Further research of the curves of -τ_i, λ_2(0)-τ_i, and λ_3(0)-τ_i (i=1,2,3) (where τ_i is the correlation time) shows that the output intensity not only increases with the additive noise correlation time τ_2 and the cross-correlation time τ_3, but also the quality of the output of laser beams is optimized.     

Theoretical and experimental studies of Ag-Pt interactions for supported Ag-Pt bimetallic catalysts

The electronic structure and chemical properties of catalysts prepared by the electroless deposition (ED) of Ag onto Pt/SiO₂ were studied using a combination of X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. XPS studies revealed a negative shift (up to −0.75 eV) in the Ag 3d binding energy (BE) relative to bulk Ag. Both the magnitude and direction of the shift are consistent with DFT calculations of model Ag/Pt(1 1 1) surfaces. DFT calculations have also been employed to study the adsorption of two probe molecules, carbon monoxide and 1-epoxy-3-butene (EpB), on the model surfaces. Combined with previously published reports, the results presented here suggest that (1) the AgPt/SiO₂ catalysts that are most active for hydrogenation of the EpB olefin function consist of an adlayer of Ag on Pt rather than a surface or bulk alloy and that (2) the higher activity and selectivity of ED-prepared Ag-Pt/SiO₂ catalysts for CC hydrogenation of EpB to 1-epoxybutane are consistent with computed electronic (ligand) and bifunctional effects.     

Nanorheology: An investigation of the boundary condition at hydrophobic and hydrophilic interfaces

It has been shown that the flow of a simple liquid over a solid surface can violate the so-called no-slip boundary condition. We investigate the flow of polar liquids, water and glycerol, on a hydrophilic Pyrex surface and a hydrophobic surface made of a Self-Assembled Monolayer of OTS (octadecyltrichlorosilane) on Pyrex. We use a Dynamic Surface Force Apparatus (DSFA) which allows one to study the flow of a liquid film confined between two surfaces with a nanometer resolution. No-slip boundary conditions are found for both fluids on hydrophilic surfaces only. Significant slip is found on the hydrophobic surfaces, with a typical length of one hundred nanometers. Received 21 December 2001 and Received in final form 3 August 2002 RID="a" ID="a"e-mail: ccottin@dpm.univ-lyon1.fr RID="b" ID="b"Present address.     

Intense picosecond X-Ray pulses from laser plasmas by use of nanostructured "Velvet" targets

We describe the optical, radiative, and laser-plasma physics of a new type of nanostructured surface especially promising as a very high absorption target for high-peak-power subpicosecond laser-matter interaction. This oriented-nanowire material, irradiated by 1 ps pulses at intensities up to 10(17) W cm(-2), produces picosecond soft x-ray pulses 50x more efficiently than do solid targets. We compare this to "smoke" or metallic clusters, and solid nanogroove-grating surfaces; the "metal-velvet" targets combine the high yield of smoke targets with the brief emission of grating surfaces.     

Semidensities on Odd Symplectic Supermanifolds

We consider semidensities on a supermanifold E with an odd symplectic structure. We define a new -operator action on semidensities as the proper framework for the Batalin-Vilkovisky (BV) formalism. We establish relations between semidensities on E and differential forms on Lagrangian surfaces. We apply these results to Batalin-Vilkovisky geometry. Another application is to (1.1)-codimensional surfaces in E. We construct a kind of pull-back of semidensities to such surfaces. This operation and the -operator are used for obtaining integral invariants for (1.1)-codimensional surfaces.     

Studying the effect of hydrogen on diamond growth by adding C10H10Fe under high pressures and high temperatures

In this paper, hydrogen-doped industrial diamonds and gem diamonds were synthesized in the Fe–Ni–C system with C₁₀H₁₀Fe additive, high pressures and high temperatures range of 5.2–6.2?GPa and 1250–1460°C. Experimental results indicate similar effect of hydrogen on these two types of diamonds: with the increasing content of C₁₀H₁₀Fe added in diamond growth environment, temperature is a crucial factor that sensitively affects the hydrogen-doped diamond crystallization. The temperature region for high-quality diamond growth becomes higher and the morphology of diamond crystal changes from cube-octahedral to octahedral. The defects on the {100} surfaces of diamond are more than those on the {111} surfaces. Fourier transform infrared spectroscopy (FTIR) results indicate that the hydrogen atoms enter into the diamond crystal lattice from {100} faces more easily. Most interestingly, under low temperature, nitrogen atoms can also easily enter into the diamond crystal lattice from {100} faces cooperated with hydrogen atoms.     

Systematic prediction of kinetically limited crystal growth morphologies

We develop a new, combined experimental and theoretical approach to make reliable predictions for the limiting case of surface reaction kinetics controlled growth. We solve the inverse problem of determining the growth velocity from observations of the evolution of the morphology of GaN islands grown by metalorganic chemical vapor deposition and make use of crystal symmetry and established theorems. We are able to predict the growth for both convex and concave surfaces, with faceted and curved features. We also give a general guideline for deducing growth velocities from experimental observations.     

Theoretical study of the initial stage of InN growth on cubic zirconia (111) substrates

An initial stage of InN growth on cubic zirconia (111) substrates has been investigated using first‐principles calculations based on density functional theory (DFT). We have evaluated adsorption energies of indium and nitrogen atoms on cubic zirconia (111) surfaces, and have found that the differences in the adsorption energies of the indium atoms at various adsorption sites were small, indicating that the migration of the indium atoms on zirconia (111) surfaces occurs readily. On the other hand, we have found that the differences in the adsorption energies of the nitrogen atoms at various adsorption sites were large, implying that the nitrogen atoms tend to stay at the stable site with the largest adsorption energy, which was identified as the O–Zr bridge site. These results suggest that the first layer of InN films is the nitrogen layer. In addition, we have found that the energetically favorable arrangement is comprised of InN(0001)//cubic zirconia (111) and InN $ [11\bar 20] $ //cubic zirconia $ [1 \bar 10], $ which is quite consistent with previously obtained experimental data. Furthermore, the hybridization effect between N 2p and O 2p plays a crucial role in determining the interface structure for the growth of InN on cubic zirconia (111) surfaces. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

An effective Hamiltonian approach to quantum random walk

In this article we present an effective Hamiltonian approach for discrete time quantum random walk. A form of the Hamiltonian for one-dimensional quantum walk has been prescribed, utilizing the fact that Hamiltonians are generators of time translations. Then an attempt has been made to generalize the techniques to higher dimensions. We find that the Hamiltonian can be written as the sum of a Weyl Hamiltonian and a Dirac comb potential. The time evolution operator obtained from this prescribed Hamiltonian is in complete agreement with that of the standard approach. But in higher dimension we find that the time evolution operator is additive, instead of being multiplicative (see Chandrashekar, Sci. Rep. 3, 2829 (18)). We showed that in the case of two-step walk, the time evolution operator effectively can have multiplicative form. In the case of a square lattice, quantum walk has been studied computationally for different coins and the results for both the additive and the multiplicative approaches have been compared. Using the graphene Hamiltonian, the walk has been studied on a graphene lattice and we conclude the preference of additive approach over the multiplicative one.     

Finitely additive states and completeness of inner product spaces

For any unit vector in an inner product space S, we define a mapping on the system of all -closed subspaces of S, F(S), whose restriction on the system of all splitting subspaces of S, E(S), is always a finitely additive state. We show that S is complete iff at least one such mapping is a finitely additive state on F(S). Moreover, we give a completeness criterion via the existence of a regular finitely additive state on appropriate systems of subspaces. Finally, the result will be generalized to general inner product spaces.     

Persistency of material element deformation in isotropic flows and growth rate of lines and surfaces

We explore the consequence of isotropy on the growth of material lines and surfaces in complex flows. We show that the key parameter is the persistency , defined as the product of a typical stretching rate to its associated coherence time . In particular, we derive the dependence of the net growth rate of both lines and surfaces on . Their growth rates increase strongly with increasing persistencies for small , and then saturate for . Making use of measurements of Girimaji and Pope [1], we estimate the persistency to be of order 1 in isotropic turbulence. We then comment on the evolution of the shape of an initially spherical material blob. While its length increases, one of its tranverse dimension increases slowly and the other one decreases. This quasi-two-dimensional deformation leads a final ribbon-shape. Received 10 November 1999 and Received in final form 14 August 2000     

Monitoring the polyamide 11 degradation by thermal properties and X‐ray fluorescence spectrometry allied to chemometric methods

The influence of temperature (110 and 120 °C) on the ageing of piping made from polyamide 11 (PA‐11) containing 10–12% of plasticizer was studied using deionized water (pH ≈ 7.0). A clean analytical methodology has been employed for quality control of polymeric materials: energy‐dispersive X‐ray fluorescence spectrometry (ED‐XRF). It provides a fast and suitable technique to characterize chemical elements because of its multielemental capability, good sensitivity, high precision, short analytical time, and nondestructive nature. Herein, the content of additive in PA‐11 was monitored from ED‐XRF measurements where the abundance of the S line is directly related to the ageing time, agreeing with the thermogravimetric analysis. The XRF data were allied to chemometric treatment to classify PA‐11 samples according to the amount of additive and weight average molar mass change, predicting the ageing time, and viscosity values of PA‐11. Therefore, the XRF can be used as a clean analytical methodology to monitor the PA‐11 degradation, thus eliminating the use of toxic organic solvents (necessary to viscosity measurements) and reducing the working time. Also, the effect of hydrolysis on the structure over time and the material morphology were monitored through measurements of dynamic mechanical analysis and differential scanning calorimetry. Copyright © 2012 John Wiley & Sons, Ltd.     

Atomistic simulation of mineral surfaces: Studies of surface stability and growth

Atomistic simulation represents a valuable methodology for interpreting and predicting surface structures. The emphasis of our work is to develop and apply this approach to understanding the role of surface defects and additives in modifying the structure and stability of mineral surfaces. The basis of our approach is energy minimisation which allows us to evaluate the most stable surface configurations. The utility and limitations of this approach will be illustrated via a number of examples. These include describing the factors governing the stability of mineral surfaces and applying these considerations to understanding the surfaces of olivine and spinel. In addition, we are beginning to address the water-solid interface. We find a wide variation in the reactivity of the different surfaces of rock-salt oxides from (100) which show only physisorption, through stepped surfaces which show dissociative adsorption to (111) which forms the hydroxide. One way of determining the interaction between surfaces and additives is the modification of crystal growth thus we are also concerned with attempting to model the growth process. However, the low index surfaces often grow via screw dislocations. Therefore preliminary work on modelling the interaction of screw dislocations with surfaces of MgO will be described.