bluuebunny/crossref_metadata_2025 huggingface dataset:
FOCUSING LIGHT WITH TYPICAL SUBWAVELENGTH PATTERNED METALLIC STRUCTURES
Authors: GUO ZHEN , YAN LIANSHAN , WEN KUNHUA , LUO XIANGANG
Published: July 2012

Two typical subwavelength nano-lenses, nano-slits and nano-grooves, are investigated based on the diffraction and electromagnetic boundary condition. Detailed and systematic analyses for the focusing properties of the two structures with different geometrical parameters are carried out. Theoretical results agree well with those in the numerical simulations and experiments. Compared to the nano-grooves, nano-slits with appropriate geometrical parameters show higher efficiency and better focusing performance.
H2 INTERACTION WITH BIMETALLIC DIMERS SUPPORTED ON THE MgO(100) SURFACE: A DFT CLUSTER MODEL STUDY
Authors: MATCZAK PIOTR
Published: July 2012

The interaction between the H2 molecule and the PdAg , PdAu , PtAg and PtAu bimetallic dimers deposited on the MgO(100) surface is investigated using density functional theory (DFT). The bimetallic dimers, whose molecular axes are considered to be perpendicular to the support surface, are adsorbed on top of an oxygen atom. Within this adsorption mode, the dimers prefer the orientation in which their Pd or Pt end is closer to the oxygen atom. The Ag and Au ends of the MgO -supported dimers capture the H2 molecule with small exoenergetic effects. The spontaneous dissociation of H2 on these ends does not occur. Thus, the MgO support decreases the ability of the dimers to adsorb and dissociate the H2 molecule. From a catalytic viewpoint, it means that the activity of small bimetallic clusters toward the dissociative adsorption of H2 is reduced when they are arranged on MgO . On the other hand, the results of our calculations show that the presence of the MgO support strengthens the binding of H atoms inside the PdAu , PtAg and PtAu dimers.
DUPLEX Al2O3/DLC COATING ON 15SiCp/2024 ALUMINUM MATRIX COMPOSITE USING COMBINED MICROARC OXIDATION AND FILTERED CATHODIC VACUUM ARC DEPOSITION
Authors: XUE WENBIN , TIAN HUA , DU JIANCHENG , HUA MING , ZHANG XU , LI YONGLIANG
Published: July 2012

Microarc oxidation (MAO) treatment produces a thick Al2O3 coating on the 15SiCp/2024 aluminum matrix composite. After pretreatment of Ti ion implantation, a thin diamond-like carbon film (DLC) was deposited on the top of polished Al2O3 coating by a pulsed filtered cathodic vacuum arc (FCVA) deposition system with a metal vapor vacuum arc (MEVVA) source. The morphology and tribological properties of the duplex Al2O3 /DLC multiplayer coating were investigated by Raman spectroscopy, scanning electron microscopy (SEM) and SRV ball-on-disk friction tester. It is found that the duplex Al2O3 /DLC coating had good adhesion and a low friction coefficient of less than 0.07. As compared to a single Al2O3 or DLC coating, the duplex Al2O3 /DLC coating on aluminum matrix composite exhibited a better wear resistance against ZrO2 ball under dry sliding, because the Al2O3 coating as an intermediate layer improved load support for the top DLC coating on 15SiCp/2024 composite substrate, meanwhile the top DLC coating displayed low friction coefficient.
EFFECT OF SUBSTRATE TEMPERATURE ON MICRO-STRUCTURAL PROPERTIES OF Ti AND TiN FILMS DEPOSITED BY E-BEAM EVAPORATION TECHNIQUE
Authors: ARSHI NISHAT , LU JUNQING , KOO BON HEUN , LEE CHAN GYU , AHMED FAHEEM
Published: July 2012

We report the deposition of Ti and TiN films on Si/SiO2 (100) substrate using e-beam evaporation technique. The influence of substrate temperature on the structural and morphological properties has been studied. The structure and morphology of the deposited films were analyzed by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) measurements, respectively. XRD patterns reveal the FCC symmetry for both the Ti and TiN films. The grain size of the films was found to increase with the increase in substrate temperature. FESEM micrographs showed a smooth morphology of the film with columnar grain structure.
EFFECTS OF TEMPERATURE AND SPUTTERING POWER ON THE MORPHOLOGY AND OPTICAL CONSTANTS OF THIN TANTALUM FILMS
Authors: GAO SHANG , WANG SHUYUN , LIAN JIE , LI PING , WANG XIAO
Published: July 2012

A set of thin tantalum films was prepared by direct current (DC) magnetron sputtering using different substrate temperatures and sputtering power. In order to identify the optimal condition for hillock free thin tantalum (Ta) film deposition, AFM was employed to measure surface morphology of the Ta films and to research the effect of substrate temperatures and sputtering power on the films surface. The relationship between optical constants and film stress of thin Ta films was also investigated. The comparison of AFM results showed that thin Ta films deposited at 500 K with a sputtering power of 56 W produced a hillock free surface as well as minimum surface roughness. All films were also measured by spectroscopic ellipsometry (SE) to characterize their optical properties. Refractive index and extinction coefficient of thin Ta films obtained from SE results by using a 5-layer model increased simultaneously, when sputtering power increased and the substrate temperature remain unchanged. However when the power was a constant, the thin Ta film sputtered at 500 K had a lower refractive index and extinction coefficient than other samples sputtered with other substrate temperatures from 300 to 700 K.
WORK FUNCTION OF BORON CARBIDE: A DFT CALCULATION
Authors: HE CHUNSHAN , LI ZHIBING , WANG WEILIANG
Published: July 2012

The work functions of (001) and (00-1) surfaces of B4C are investigated with density functional theory and symmetry slab model. These two surfaces are found to be almost nonpolarized and their work functions are 5.15 eV and 5.46 eV, respectively.
TRIBOLOGICAL PROPERTIES OF CrN COATING UNDER LUBRICATION CONDITIONS
Authors: LUBAS JANUSZ
Published: July 2012

The paper presents research results of the influence of CrN coating on the friction parameters in friction pairs under lubricated friction conditions. The formed CrN homogeneous coating and CrN -steel 46Cr2 "ring" structure coating was matched under test conditions with a counterpart made from SAE-48 and SAE-783 bearing alloys. Tested sliding pairs were lubricated with 5W/40 Lotos synthetic engine oil. The tribological test was conducted on block-on-ring tester. The applied modification technologies of the surface layer of steel allowed for obtaining construction materials with pre-determined tribological characteristics required for the elements of friction pairs in lubricated contact. The results of the tests proved the possibility of implementing CrN coating in friction pairs, which work under mixed friction conditions. The results showed differences in the wear of bearing alloy, as the effect of the interaction between the co-operating surface layers and of the physiochemical changes of their surfaces, induced by external forces. The smallest wear of the bearing alloy occurs during the cooperation with the nitrided layer, whereas the largest wear occurs during the cooperation with the homogenous CrN coating. The CrN coating-46Cr2 steel "ring structure" decreases friction resistance during the start-up of the sliding pair, as well as lowers the level of the friction force and temperature in the friction area during co-operation with SAE-783 bearing alloys.
FABRICATION AND OPTOELECTRONIC PROPERTIES OF MgxZn1-xO ULTRATHIN FILMS BY LANGMUIR–BLODGETT TECHNOLOGY
Authors: TANG DONGYAN , FENG QIAN , JIANG ENYING , HE BAOZHU
Published: July 2012

By transferring Mg x Zn 1-x O sol and stearic acid onto a hydrophilic silicon wafer or glass plate, the Langmuir–Blodgett (LB) multilayers of Mg x Zn 1-x O (x:0, 0.2, 0.4) were deposited. After calcinations at 350°C for 0.5 h and at 500°C for 3 h, Mg x Zn 1-x O ultrathin films were fabricated. The optimized parameters for monolayer formation and multilayer deposition were determined by the surface pressure-surface (Π-A) area and the transfer coefficient, respectively. The expended areas of stearic acid with Mg x Zn 1-x O sols under Π-A isotherms inferred the interaction of stearic acid with Mg x Zn 1-x O sols during the formation of monolayer at air–water interface. X-ray diffraction (XRD) was used to determine the crystal structures of Mg x Zn 1-x O nanoparticles and ultrathin films. The surface morphologies of Mg x Zn 1-x O ultrathin films were observed by scanning probe microscopy (AFM). And the optoelectronic properties of Mg x Zn 1-x O were detected and discussed based on photoluminescence (PL) spectra.
MEDICINAL RADIOPHARMACEUTICAL CHEMISTRY OF METAL RADIOPHARMACEUTICALS
Authors: SAW MAUNG MAUNG
Published: July 2012

Metal complexes have been used as medicinal compounds. Metals have advantageous features over organic compounds. Significant applications of metal complexes are in the field of nuclear medicine. Radiopharmaceuticals are drugs containing radioisotopes used for diagnostic and therapeutic purposes.

The generalized targeting strategy for molecular imaging probe consists of three essential parts: (i) reporter unit or payload, (ii) carrier, and (iii) targeting system. Medicinal radiopharmaceutical chemistry pays special consideration to radioisotopes, as a reporter unit for diagnostic application or as a payload for therapeutic application. Targeting is achieved by a few approaches but the most common is the bifunctional chelator approach. While designing a radiopharmaceutical, a range of issues needs to be considered including properties of metal radioisotopes, bifunctional chelators, linkers, and targeting molecules. Designing radiopharmaceuticals requires consideration of two key words: "compounds of biological interest" and "fit for intended use." The ultimate goal is the development of new diagnostic methods and treatment.

Diagnostic metal radiopharmaceuticals are used for SPECT and PET applications. Technetium chemistry constitutes a major portion of SPECT and gallium chemistry constitutes a major portion of PET. Therapeutic radiopharmaceuticals can be constructed by using alpha-, beta minus-, or Auger electron-emitting radiometals. Special uses of medicinal radiopharmaceuticals include internal radiation therapy, brachytherapy, immunoPET, radioimmunotherapy, and peptide receptor radionuclide imaging and therapy.
GADOLINIUM(Gd)-BASED AND ION OXIDE NANOPARTICLE CONTRAST AGENTS FOR PRE-CLINICAL AND CLINICAL MAGNETIC RESONANCE IMAGING (MRI) RESEARCH
Authors: NG THIAN C.
Published: July 2012

It is known that one strength of MRI is its excellent soft tissue discrimination. It naturally provides sufficient contrast between the structural differences of normal and pathological tissues, their spatial extent and progression. However, to further extend its applications and enhance even more contrast for clinical studies, various Gadolinium (Gd)-based contrast agents have been developed for different organs (brain strokes, cancer, cardio-MRI, etc). These Gd -based contrast agents are paramagnetic compounds that have strong T 1-effect for enhancing the contrast between tissue types. Gd -contrast can also enhance magnetic resonance angiography (CE-MRA) for studying stenosis and for measuring perfusion, vascular susceptibility, interstitial space, etc. Another class of contrast agents makes use of ferrite iron oxide nanoparticles (including Superparamagnetic Ion Oxide (SPIO) and Ultrasmall Superparamagnetic Iron Oxide (USPIO)). These nanoparticles have superior magnetic susceptibility effect and produce a drop in signal, namely in [Formula: see text]-weighted images, useful for the determination of lymph nodes metastases, angiogenesis and arteriosclerosis plaques.
OBSERVATION OF REDUCTION IN CASIMIR FORCE WITHOUT CHANGE OF DIELECTRIC PERMITTIVITY
Authors: BANISHEV A. A. , CHANG C.-C. , CASTILLO-GARZA R. , KLIMCHITSKAYA G. L. , MOSTEPANENKO V. M. , MOHIDEEN U.
Published: July 2012

Additional information is provided on the effect of the significant (up to 35%) reduction in the magnitude of the Casimir force between an Au-coated sphere and an indium tin oxide film which was observed after UV treatment of the latter. A striking feature of this effect is that the reduction is not accompanied with a corresponding variation of the dielectric permittivity, as confirmed by direct ellipsometry measurements. The measurement data are compared with computations using the Lifshitz theory. It is shown that the data for the untreated sample are in a very good agreement with theory taking into account the free charge carriers in the indium tin oxide. The data for the UV-treated sample exclude the theoretical results obtained with account of free charge carriers. These data are found to be in a very good agreement with theory disregarding the free charge carriers in an indium tin oxide film. A possible theoretical explanation of our observations as a result of phase transition of indium tin oxide from metallic to dielectric state is discussed in comparison with other related experiments.
VACUUM SUPERCONDUCTIVITY, CONVENTIONAL SUPERCONDUCTIVITY AND SCHWINGER PAIR PRODUCTION
Authors: CHERNODUB M. N.
Published: July 2012

In a background of a very strong magnetic field a quantum vacuum may turn into a new phase characterized by anisotropic electromagnetic superconductivity. The phase transition should take place at a critical magnetic field of the hadronic strength (Bc ≈ 1016 Tesla or eBc ≈ 0.6 GeV2 ). The transition occurs due to an interplay between electromagnetic and strong interactions: virtual quark–antiquark pairs popup from the vacuum and create – due to the presence of the intense magnetic field – electrically charged and electrically neutral spin-1 condensates with quantum numbers of ρ mesons. The ground state of the new phase is a complicated honeycomblike superposition of superconductor and superfluid vortex lattices surrounded by overlapping charged and neutral condensates. In this talk we discuss similarities and differences between the superconducting state of vacuum and conventional superconductivity, and between the magnetic–field–induced vacuum superconductivity and electric–field–induced Schwinger pair production.
THE HEISENBERG-EULER EFFECTIVE ACTION: 75 YEARS ON
Authors: DUNNE GERALD V.
Published: July 2012

On this 75th anniversary of the publication of the Heisenberg-Euler paper on the full non-perturbative one-loop effective action for quantum electrodynamics I review their paper and discuss some of the impact it has had on quantum field theory.
ZETA FUNCTION REGULARIZATION IN CASIMIR EFFECT CALCULATIONS AND J. S. DOWKER'S CONTRIBUTION
Authors: ELIZALDE EMILIO
Published: July 2012

A summary of relevant contributions, ordered in time, to the subject of operator zeta functions and their application to physical issues is provided. The description ends with the seminal contributions of Stephen Hawking and Stuart Dowker and collaborators, considered by many authors as the actual starting point of the introduction of zeta function regularization methods in theoretical physics, in particular, for quantum vacuum fluctuation and Casimir effect calculations. After recalling a number of the strengths of this powerful and elegant method, some of its limitations are discussed. Finally, recent results of the so called operator regularization procedure are presented.
QUANTUM FIELD THEORY IN GRAPHENE
Authors: FIALKOVSKY I. V. , VASSILEVICH D. V.
Published: July 2012

This is a short non-technical introduction to applications of the Quantum Field Theory methods to graphene. We derive the Dirac model from the tight binding model and describe calculations of the polarization operator (conductivity). Later on, we use this quantity to describe the Quantum Hall Effect, light absorption by graphene, the Faraday effect, and the Casimir interaction.
THE CASIMIR EFFECT FOR GENERALIZED PISTON GEOMETRIES
Authors: FUCCI GUGLIELMO , KIRSTEN KLAUS
Published: July 2012

In this paper we study the Casimir energy and force for generalized pistons constructed from warped product manifolds of the type I ×f N where I = [a, b] is an interval of the real line and N is a smooth compact Riemannian manifold either with or without boundary. The piston geometry is obtained by dividing the warped product manifold into two regions separated by the cross section positioned at R ∈ (a, b). By exploiting zeta function regularization techniques we provide formulas for the Casimir energy and force involving the arbitrary warping function f and base manifold N.
ENERGY DENSITY AND PRESSURE IN POWER-WALL MODELS
Authors: FULLING S. A. , MILTON K. A. , WAGNER JEF
Published: July 2012

A finite ultraviolet cutoff near a reflecting boundary yields a stress tensor that violates the basic energy-pressure relation. Therefore, a "soft" wall described by a power-law potential, which needs no ad hoc cutoff, is being investigated by the collaboration centered at Texas A&M University and the University of Oklahoma. Progress is reported here.
STRONG-FIELD QED AND HIGH POWER LASERS
Authors: HEINZL THOMAS
Published: July 2012

This contribution presents an overview of fundamental QED processes in the presence of an external field produced by an ultra-intense laser. The discussion focusses on the basic intensity effects on vacuum polarisation and the prospects for their observation. Some historical remarks are added where appropriate.
CASIMIR EFFECT: THEORY AND EXPERIMENTS
Authors: LAMBRECHT ASTRID , REYNAUD SERGE
Published: July 2012

The Casimir effect is a crucial prediction of Quantum Field Theory which has fascinating connections with open questions in fundamental physics. The ideal formula written by Casimir does not describe real experiments and it has to be generalized by taking into account the effects of imperfect reflection, thermal fluctuations, geometry as well as the corrections coming from surface physics. We discuss these developments in Casimir physics and give the current status in the comparison between theory and experiment after years of improvements in measurements as well as theory.
FURTHER GRAVITATIONAL WAVE MODES FROM HIGHER ORDER GRAVITY
Authors: CAPOZZIELLO SALVATORE , DE LAURENTIS MARIAFELICIA
Published: July 2012

It is shown that linearizing higher order theories of gravity, further gravitational massive modes emerge. Besides massless spin-2, also spin-0 and spin-2 massive and ghost fields have to be considered. We investigate the possible detectability of such additional modes on the stochastic cosmic background of gravitational waves by ground-based and space interferometric detectors and calculate the detectable energy density of the spectrum. In conclusion, these massive modes could be of interest for direct detection by the forthcoming LISA experiment.
SOMMERFELD'S IMAGE METHOD IN THE CALCULATION OF VAN DER WAALS FORCES
Authors: DE MELO E SOUZA REINALDO , KORT-KAMP W. J. M. , SIGAUD C. , FARINA C.
Published: July 2012

We show how the image method can be used together with a recent method developed by C. Eberlein and R. Zietal to obtain the dispersive van der Waals interaction between an atom and a perfectly conducting surface of arbitrary shape. We discuss in detail the case of an atom and a semi-infinite conducting plane. In order to employ the above procedure to this problem it is necessary to use the ingenious image method introduced by Sommerfeld more than one century ago, which is a generalization of the standard procedure. Finally, we briefly discuss other interesting situations that can also be treated by the joint use of Sommerfeld's image technique and Eberlein-Zietal method.
TIME-DEPENDENT ROBIN BOUNDARY CONDITIONS IN THE DYNAMICAL CASIMIR EFFECT
Authors: FARINA C. , SILVA HECTOR O. , REGO ANDRESON L. C. , ALVES DANILO T.
Published: July 2012

Motivated by experiments in which moving boundaries are simulated by time-dependent properties of static systems, we discuss the model of a massless scalar field submitted to a time-dependent Robin boundary condition (BC) at a static mirror in 1 + 1 dimensions. Using a perturbative approach, we compute the spectral distribution of the created particles and the total particle creation rate, considering a thermal state as the initial field state.
MODIFIED DISPERSION RELATIONS: FROM BLACK-HOLE ENTROPY TO THE COSMOLOGICAL CONSTANT
Authors: GARATTINI REMO
Published: July 2012

Quantum Field Theory is plagued by divergences in the attempt to calculate physical quantities. Standard techniques of regularization and renormalization are used to keep under control such a problem. In this paper we would like to use a different scheme based on Modified Dispersion Relations (MDR) to remove infinities appearing in one loop approximation in contrast to what happens in conventional approaches. In particular, we apply the MDR regularization to the computation of the entropy of a Schwarzschild black hole from one side and the Zero Point Energy (ZPE) of the graviton from the other side. The graviton ZPE is connected to the cosmological constant by means of of the Wheeler-DeWitt equation.
FEYNMAN DIAGRAMS FOR DISPERSION INTERACTIONS OUT OF EQUILIBRIUM — TWO-BODY POTENTIALS FOR ATOMS WITH INITIAL EXCITATION
Authors: HAAKH HARALD R. , SCHIEFELE JÜRGEN , HENKEL CARSTEN
Published: July 2012

Diagrammatic techniques are well-known in the calculation of dispersion interactions between atoms or molecules. The multipolar coupling scheme combined with Feynman ordered diagrams significantly reduces the number of graphs compared to elementary stationary perturbation theory. We review calculations of van der Waals-Casimir-Polder forces, focusing on two atoms or molecules, one of which is excited. In this case, calculations of the corresponding force are notorious for mathematical issues connected with the spontaneous decay of the excitation. Treating such unstable states in a full non-equilibrium theory provides a physical interpretation of apparent contradictions in previous results and underlines the importance of decay processes for the intermolecular potential. This may have important implications on reactions in biological systems, where excited states may be relatively long-lived and the resonant intermolecular force may result in directed Brownian motion.
RADIATION DAMPING AND THE ELECTRON MASS SHIFT IN HIGH INTENSITY LASER FIELDS
Authors: HARVEY CHRISTOPHER , MARKLUND MATTIAS
Published: July 2012

We explore the effects of radiation damping on electrons in a high intensity laser pulse. From classical simulations it is found that an electron can get captured in the beam focus, solely because of its radiation back reaction. This capture regime is considered in the context of an intensity-dependent mass shift of the electron. It is demonstrated that the mass shift is not just a classical effect, occurring also in the (strong field) QED theory. Using the QED process of nonlinear Compton scattering as an example, we show that the condition for the onset of electron capture is the same as the definition of the center-of-mass frame for the effective mass kinematics.
QUANTUM-CIRCUIT ANALOG OF THE DYNAMICAL CASIMIR EFFECT AT FINITE TEMPERATURES
Authors: MATSUO SHIGEMASA , FUJII TOSHIYUKI , HATAKENAKA NORIYUKI
Published: July 2012

We proposed a quantum-circuit analog of dynamical Casimir effect by using a superconducting quantum circuit. The proposed system can be regarded as a time-dependent harmonic oscillator, resulting in squeezing of a quantum flux trapped in the system. Here we develop our theory taking into account finite temperatures, in order to contact with experiments like circuit-QED. We present numerical results of occupation probability distributions produced by non-stationary boundary effect at various temperatures.
COVARIANT GRAVITY WITH LAGRANGE MULTIPLIER CONSTRAINT
Authors: NOJIRI SHIN'ICHI
Published: July 2012

We review on the models of gravity with a constraint by the Lagrange multiplier field. The constraint breaks general covariance or Lorentz symmetry in the ultraviolet region. We report on the F(R) gravity model with the constraint and the proposal of the covariant (power-counting) renormalized gravity model by using the constraint and scalar projectors. We will show that the model admits flat space solution, its gauge-fixing formulation is fully developed, and the only propagating mode is (higher derivative) graviton, while scalar and vector modes do not propagate. The preliminary study of FRW cosmology indicates to the possibility of inflationary universe solution is also given.
A NOTE ON LONGITUDINAL FIELDS IN THE WEYL EXPANSION OF THE ELECTROMAGNETIC GREEN TENSOR
Authors: PIEPLOW GREGOR , HAAKH HARALD R. , HENKEL CARSTEN
Published: July 2012

Many calculations of dispersion interactions between atoms and macroscopic bodies or between two bodies make use of Green tensors. The expansion of this tensor in polarizations allows for an anatomic interpretation of the interaction. In planar systems with partial translation invariance, the Weyl representation of the Green tensor is often applied. Although it is transverse in this representation, we argue that the field it describes contains nonradiative parts as well. This can be seen by calculating the Green tensor in the momentum representation and observing certain cancellations among longitudinal and transverse contributions.
PHASE DIAGRAM FOR ASYMMETRIC PLANAR FERMIONIC SYSTEMS IN THE PRESENCE OF EXTERNAL FIELDS
Authors: RAMOS RUDNEI O. , MANSO PATRÍCIA H. A.
Published: July 2012

The phase diagram of planar fermionic systems, with four-fermion interactions, are studied when external magnetic fields in different directions are applied to the system. The application of external fields can lead to an asymmetric system, which with the combined effects due to temperature and chemical potential, can lead to a rich phase diagram with multiple critical points. The phase transition we are primarily interested in studying is that of the metal-insulator type, in which our model is particularly well suitable. The relation between the phase transition with chiral symmetry breaking and the emergence of a gap (or the presence of a nonvanishing chiral vacuum expectation value) in the planar fermionic system, as a function of the different magnetic fields applied, is analyzed in details. The applications of our results in the context of condensed matter and quantum field theory at low dimensions are discussed.
CASIMIR ENERGY AND ENTROPY BETWEEN PERFECT METAL SPHERES
Authors: RODRIGUEZ-LOPEZ PABLO
Published: July 2012

We calculate the Casimir energy and entropy for two perfect metal spheres in the large and short separation limit. We obtain nonmonotonic behavior of the Helmholtz free energy with separation and temperature, leading to parameter ranges with negative entropy, and also nonmonotonic behavior of the entropy with temperature and with the separation between the spheres. The appearance of this anomalous behavior of the entropy is discussed as well as its thermodynamic consequences.
STOCHASTIC QUANTIZATION AND CASIMIR FORCES: PISTONS OF ARBITRARY CROSS SECTION
Authors: RODRIGUEZ-LOPEZ PABLO , BRITO RICARDO , SOTO RODRIGO
Published: July 2012

Recently, a method based on stochastic quantization has been proposed to compute the Casimir force and its fluctuations in arbitrary geometries. It relies on the spectral decomposition of the Laplace operator in the given geometry. Both quantum and thermal fluctuations were considered. Here we use this method to compute the Casimir force on the plates of a finite piston of arbitrary cross section. Asymptotic expressions valid at low and high temperatures, as well as short and long distances are obtained. The case of a piston with triangular cross section is analyzed in detail. The regularization of the divergent stress tensor is described.
SIGNIFICANCE OF MANY-BODY CONTRIBUTIONS TO CASIMIR ENERGIES
Authors: SHAJESH K. V. , SCHADEN M.
Published: July 2012

Irreducible many-body contributions to Green's functions and Casimir energies are defined. We show that the irreducible three-body contribution to Casimir energies are significant and can be more than twenty percent of the total interaction energy. Irreducible three-body contribution for three parallel semitransparent plates in the limit when two plates overlap is obtained in terms of irreducible two-body contributions and shown to be finite and well defined in this limit.
PATH INTEGRAL QUANTUM MECHANICS IN CURVED SPACE-TIME: A NEW PERSPECTIVE
Authors: SINGH DINESH , MOBED NADER
Published: July 2012

A new approach to path integral quantum mechanics in curved space-time for a scalar particle is presented in terms of local curvature involving Fermi or Riemann normal co-ordinates. This approach involves use of a local time translation operator with Lie transport that, while strictly non-unitary in form, nonetheless yields the correct expression for the curved space-time free-particle Lagrangian in the sum-over-histories, with additional terms corresponding to a curvature-dependent violation of probability. These terms simultaneously induce a breakdown of time-reversal symmetry at the quantum mechanical level, and also a violation of the weak equivalence principle at the particle's Compton wavelength scale. Furthermore, the scalar propagator generates a gravitational analogue of the Aharonov-Bohm effect and Berry's phase through the appearance of an overall gauge-invariant phase factor. Future directions to follow from this initial research are presented.
CASIMIR EFFECT ACROSS A LAYERED MEDIUM
Authors: TOMAŠ MARIN-SLOBODAN
Published: July 2012

Using nonstandard recursion relations for Fresnel coefficients involving successive stacks of layers, we extend the Lifshitz formula to configurations with an inhomogeneous, n-layered, medium separating two planar objects. The force on each object is the sum of a Lifshitz like force and a force arising from the inhomogeneity of the medium. The theory correctly reproduces very recently obtained results for the Casimir force/energy in some simple systems of this kind. As a by product, we obtain a formula for the force on an (unspecified) stack of layers between two planar objects which generalizes our previous result for the force on a slab in a planar cavity.
CASIMIR PRESSURE IN MDS-STRUCTURES
Authors: YUROVA V. A. , BUKINA M. N. , CHURKIN Yu. V. , FEDORTSOV A. B. , KLIMCHITSKAYA G. L.
Published: July 2012

The Casimir pressure on the dielectric layer in metal-dielectric-semiconductor (MDS) structures is calculated in the framework of the Lifshitz theory at nonzero temperature. In this calculation the standard parameters of semiconductor devices with a thin dielectric layer are used. We consider the thickness of a layer decreasing from 40 to 1 nm. At the shortest thickness the Casimir pressure achieves 8 MPa. At small thicknesses the results are compared with the predictions of nonrelativistic theory.
Phase Structure and Microwave Dielectric Properties of Low-Firing Zn1-x(Li1/2Sm1/2)xWO4Ceramics
Authors: Liu Xiaobin , Zhou Huanfu , Fang Liang , Chen Xiuli , Wang Yiliang , Liao Wei
Published: July 2012

Zn1-x(Li1/2Sm1/2)xWO4(0≤x≤1) ceramics were prepared by the conventional solid-state reaction method. The sintering behavior, phase structure, and microwave dielectric properties of Zn1-x(Li1/2Sm1/2)xWO4ceramics were investigated. By substituting Li1/2Sm1/2for Zn, the sintering temperature of ceramics was reduced from 1100 °C to below 900 °C and the main phase changed from sanmartinite monoclinic ZnWO4to scheelite tetragonal (Li1/2Sm1/2)WO4. The microwave dielectric properties of the sintered ceramics varied with increasing (Li1/2Sm1/2) content and were in agreement basically with the Lichtenecker empirical logarithmic rule. In particular, the temperature coefficient of resonate frequency values (τf) can be adjusted to zero. Typically, 0.4 mol (Li1/2Sm1/2) substituted Zn0.6(Li1/2Sm1/2)0.4WO4ceramic exhibited good microwave dielectric properties with a relative permittivity of 16.8, aQ×fvalue of 11,800 GHz, and a τfvalue of 7 ppm/°C.
Improved Light Extraction of GaN-Based Light-Emitting Diodes by an Ion-Damaged Current Blocking Layer
Authors: Lee Keon Hwa , Kang Ki Man , Hong Gi Cheol , Kim Seung Hwan , Sun Woo Young , Yang Gye Mo
Published: July 2012

In this study we investigate an InGaN layer damaged by the bombardment of energetic oxygen ions that is placed beneath a p-electrode to act as a current blocking layer (CBL). This method not only increases light output power but also alleviates the current crowding problem. Our tests showed that the light output power was increased by 10% at 60 mA compared to conventional light-emitting diodes (LEDs). Additionally, our method improves LED productivity and effectiveness as it creates a nearly planar insulation layer through disordering or Ga sputtering of the InGaN surface and Ga2O3 formation.
Reed–Solomon Volumetric Coding with Matched Interleaving for Holographic Data Storage
Authors: Gu Huarong , Cao Liangcai , He Qingsheng , Jin Guofan
Published: July 2012

For various error patterns, including random errors, burst errors, and inhomogeneously distributed errors, in the holographic data storage (HDS) channel, a Reed–Solomon volumetric coding with matched interleaving (RSVC-MI) scheme is proposed in this paper. The RSVC-MI scheme combines the advantages of the RSVC scheme and the matched interleaving scheme, makes full use of the priori knowledge of the error patterns in the HDS channel, distributes errors more uniformly, and decodes data iteratively in three dimensions. It is able to eliminate the influences of non-uniform distribution of errors within a page and across pages, overcome the effects of burst errors, correct random errors, and effectively reduce the symbol error rate (SER) of the HDS channel.
Enhancement of Cycling Performance by Li2O–Sn Anode for All-Solid-State Batteries
Authors: Jee Seung Hyun , Lee Seok Hee , Kim Dong-Joo , Kwak Ji-Yeon , Nam Sang-Cheol , Yoon Young Soo
Published: July 2012

A solid-state half-cell structure with a Sn–Li2O composite (SLC) anode/LiPON/Li was prepared to improve upon the cycling stability at the second discharging cycle of the non-Li anode thin films for all-solid-state batteries. Based on the cycling behaviors of the all-solid half cell with SLC and pure Sn thin film electrodes at first and second discharging cycles, cycling stability at the initial charging–discharging cycle of the all-solid-state battery system was improved. The high retention value of SLC thin film electrodes with LiPON solid electrolyte might originate from (1) the structural stability of the SLC thin film, and (2) suppression of crack formation at the SLC surface owing to an increasing surface mechanical strength of the SLC thin film by the LiPON deposition on it. These results indicate that the SLC thin film has a high possibility as the stable solid anode material for use as an all-solid-state battery.
Residual Clamping Force and Dynamic Random Access Memory Data Retention Improved by Gate Tungsten Etch Dechucking Condition in a Bipolar Electrostatic Chuck
Authors: Lee Chung-Yuan , Lai Chao-Sung , Yang Chia-Ming , Wang David HL , Lin Betty , Lee Siimon , Huang Chi-Hung , Wei Chen Chang
Published: July 2012

It was found that the residual clamping force of bipolar electrostatic chucks created by the residual charge between a wafer and an electrode would not only cause a wafer sticking problem but also degrade dynamic random access memory (DRAM) data retention performance. The residual clamping force and data retention fail bit count (FBC) of DRAM showed strong correlations to the gate tungsten etch dechucking process condition. Wafer sticking only degraded DRAM cell retention performance, and did not influence any in-line measurement or electrical parameters. Electrical characterization analysis of the FBC proved that the retention loss was mainly due to junction leakage rather than gate-induced-drain-leakage current. A new approach was proposed to suppress this leakage by introducing N2 gas instead of O2 to supply more plasma charges for neutralizing the wafer surface residual charges. The wafer shift dynamic alignment (DA) offset and retention FBC could be reduced by 50 and 40%, respectively. Poor data retention was suspected because of the compressive stress caused by wafer sticking DA shift resulting in a high electric field at the junction and an increase in junction leakage at the storage node.
Neutrino Masses from the Top Down
Authors: Langacker Paul
Published: July 2012

General classes of mechanisms for generating small neutrino masses are surveyed from a top-down (superstring) perspective. In particular, string constructions have motivated various possibilities involving higher-dimensional operators, string instantons, and wave-function overlaps in large or warped extra dimensions. These constructions may yield small Dirac masses, Majorana masses via the Weinberg operator, or Majorana masses from a seesaw mechanism, although the last typically differ in detail from the more conventional Grand Unified Theory models. Possibilities for mixing between light, active neutrinos and sterile neutrinos are surveyed.
Twenty-First Century Lattice Gauge Theory: Results from the Quantum Chromodynamics Lagrangian
Authors: Kronfeld Andreas S.
Published: July 2012

Quantum chromodynamics (QCD) reduces the strong interactions, in all their variety, to a simple nonabelian gauge theory. It clearly and elegantly explains hadrons at short distances, which has led to its universal acceptance. Since its advent, however, many of its long-distance, emergent properties have been believed to be true without having been demonstrated to be true. This article reviews various results in this regime that have been established with lattice gauge theory, directly from the QCD Lagrangian. This research sheds light on the origin of hadron masses, its interplay with dynamical symmetry breaking, and other intriguing features such as the phase structure of QCD. Also, nonperturbative QCD is quantitatively important to many aspects of particle physics (especially the quark flavor sector), nuclear physics, and astrophysics. This review also surveys some of the most interesting connections to those subjects.
Tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone initiates and enhances pancreatitis responses
Authors: Alexandre M. , Uduman A. K. , Minervini S. , Raoof A. , Shugrue C. A. , Akinbiyi E. O. , Patel V. , Shitia M. , Kolodecik T. R. , Patton R. , Gorelick F. S. , Thrower E. C.
Published: July 2012

Clinical studies indicate that cigarette smoking increases the risk for developing acute pancreatitis. The nicotine metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a major cigarette smoke toxin. We hypothesized that NNK could sensitize to pancreatitis and examined its effects in isolated rat pancreatic acini and in vivo. In acini, 100 nM NNK caused three- and fivefold activation of trypsinogen and chymotrypsinogen, respectively, above control. Furthermore, NNK pretreatment in acini enhanced zymogen activation in a cerulein pancreatitis model. The long-term effects of NNK were examined in vivo after intraperitoneal injection of NNK (100 mg/kg body wt) three times weekly for 2 wk. NNK alone caused zymogen activation (6-fold for trypsinogen and 2-fold for chymotrypsinogen vs. control), vacuolization, pyknotic nuclei, and edema. This NNK pretreatment followed by treatment with cerulein (40 μg/kg) for 1 h to induce early pancreatitis responses enhanced trypsinogen and chymotrypsinogen activation, as well as other parameters of pancreatitis, compared with cerulein alone. Potential targets of NNK include nicotinic acetylcholine receptors and β-adrenergic receptors; mRNA for both receptor types was detected in acinar cell preparations. Studies with pharmacological inhibitors of these receptors indicate that NNK can mediate acinar cell responses through an nonneuronal α7-nicotinic acetylcholine receptor (α7-nAChR). These studies suggest that prolonged exposure to this tobacco toxin can cause pancreatitis and sensitize to disease. Therapies targeting NNK-mediated pathways may prove useful in treatment of smoking-related pancreatitis.
Importance of apical membrane delivery of 1,25-dihydroxyvitamin D3 to vitamin D-responsive gene expression in the colon
Authors: Koszewski Nicholas J. , Horst Ronald L. , Goff Jesse P.
Published: July 2012

Synthetic conjugation of a glucuronide to 1,25-dihydroxyvitamin D3 (1,25D3) to produce β-25-monoglucuronide-1,25D3 (βGluc-1,25D3) renders the hormone biologically inactive and resistant to mammalian digestive enzymes. However, β-glucuronidase produced by bacteria in the lower intestinal tract can cleave off the glucuronide, releasing the active hormone. In mice given a single oral dose of 1,25D3, 24-hydroxylase (Cyp24a1) gene expression was strongly enhanced in the duodenum, but not in the colon, despite circulating concentrations of 1,25D3 that peaked at ∼3.0 nmol/l. In contrast, in mice treated with an equimolar dose of βGluc-1,25D3, Cyp24a1 gene expression increased 700-fold in the colon but was significantly weaker in the duodenum compared with mice treated with 1,25D3. Similar results were observed with another vitamin D-dependent gene. When administered subcutaneously, 1,25D3 weakly stimulated colon Cyp24a1 gene expression while βGluc-1,25D3 again resulted in strong enhancement. Surgical ligation to block passage of ingesta beyond the upper intestinal tract abolished upregulation of colon Cyp24a1 gene expression by orally and subcutaneously administered βGluc-1,25D3. Feeding βGluc-1,25D3 for 5 days revealed a linear, dose-dependent increase in colon Cyp24a1 gene expression but did not significantly increase plasma 1,25D3 or calcium concentrations. This study indicates that the colon is relatively insensitive to circulating concentrations of 1,25D3 and that the strongest gene enhancement occurs when the hormone reaches the colon via the lumen of the intestinal tract. These findings have broad implications for the use of vitamin D compounds in colon disorders and set the stage for future therapeutic studies utilizing βGluc-1,25D3 in their treatment.
A New Rapid and Sensitive Spectrophotometric Method for Determination of a Biopolymer Chitosan
Authors: Badawy Mohamed E. I.
Published: July 2012

A novel approach of spectrophotometric quantification of chitosan based on one-step depolymerization with sodium nitrite followed by reaction of the end product with thiobarbituric acid has been proposed, optimized, and validated. In this process, chitosan is converted into 2,5-anhydro-D-mannose that reacts with thiobarbituric acid to form pink color. The color that resulted from the reaction was stabilized and measured at 555 nm. The method optimization was essential as many procedural parameters influenced the accuracy of the determination including hydrolysis conditions, thiobarbituric acid concentration, reaction time, pH, reaction temperature, and color stability period. Under given optimized conditions that appeared to be critical, chitosan was quantitatively analyzed and the calibration graph was linear over the range of 10–50 μg/mL (). This approach was applied for determination of chitosan in pharmaceutical formulation (chitocal) and had a recovery rate of higher than 96%. The developed method is easy to use and highly accurate.
Impact of Ge4+ Ion as Structural Dopant of Ti4+ in Anatase: Crystallographic Translation, Photocatalytic Behavior, and Efficiency under UV and VIS Irradiation
Authors: Štengl Václav , Grygar Tomáš Matys , Velická Jana , Henych Jiří , Bakardjieva Snejana
Published: July 2012

Nanometric particles of germanium‐doped TiO2 were prepared by homogeneous hydrolysis of TiOSO4 and GeCl4 in an aqueous solution using urea as the precipitation agent. Structural evolution during heating of these starting Ge‐Ti oxide powders was studied by X‐ray diffraction (XRD) and high‐temperature X‐ray powder diffraction (HTXRD). The morphology and microstructure changes were monitored by means of scanning electron microscopy (SEM), Raman and infrared spectroscopy (IR), specific surface area (BET), and porosity determination (BJH). The photocatalytic activity of all samples was determined by decomposition of Orange II dye under irradiation at 365 nm and 400 nm. Moderate doping with concentration upto value 2.05 wt.% positively influences azo dye degradation under UV and Vis light. Further improvement cannot be achieved by higher Ge doping. Effect of the annealing (200, 400, and 700°C) on photocatalysis and other properties has been assessed.
A Novel Weighted Support Vector Machine Based on Particle Swarm Optimization for Gene Selection and Tumor Classification
Authors: Abdi Mohammad Javad , Hosseini Seyed Mohammad , Rezghi Mansoor
Published: July 2012

We develop a detection model based on support vector machines (SVMs) and particle swarm optimization (PSO) for gene selection and tumor classification problems. The proposed model consists of two stages: first, the well-known minimum redundancy-maximum relevance (mRMR) method is applied to preselect genes that have the highest relevance with the target class and are maximally dissimilar to each other. Then, PSO is proposed to form a novel weighted SVM (WSVM) to classify samples. In this WSVM, PSO not only discards redundant genes, but also especially takes into account the degree of importance of each gene and assigns diverse weights to the different genes. We also use PSO to find appropriate kernel parameters since the choice of gene weights influences the optimal kernel parameters and vice versa. Experimental results show that the proposed mRMR-PSO-WSVM model achieves highest classification accuracy on two popular leukemia and colon gene expression datasets obtained from DNA microarrays. Therefore, we can conclude that our proposed method is very promising compared to the previously reported results.
Nonequilibrium Thermal Dynamic Modeling of Porous Medium Vacuum Drying Process
Authors: Zhang Zhijun , Kong Ninghua
Published: July 2012

Porous medium vacuum drying is a complicated heat and mass transfer process. Based on the theory of heat and mass transfer, a coupled model for the porous medium vacuum drying process is constructed. The model is implemented and solved using COMSOL software. The water evaporation rate is determined using a nonequilibrium method with the rate constant parameter Kr.  Kr values of 1, 10, 1000, and 10000 are simulated. The effects of vapor pressures of 1000, 5000, and 9000 Pa; initial moistures of 0.6, 0.5, and 0.4 water saturation; heat temperatures of 323, 333, and 343 K; and intrinsic permeability of 10−13, 10−14, and 10−15 m2 are studied. The results facilitate a better understanding of the porous medium vacuum drying process.
Optical and Structural Properties of Silicon Nanocrystals Embedded in SiOx Matrix Obtained by HWCVD
Authors: Coyopol A. , García-Salgado G. , Díaz-Becerril T. , Juárez H. , Rosendo E. , López R. , Pacio M. , Luna-López J. A. , Carrillo-López J.
Published: July 2012

The interest in developing optoelectronic devices integrated in the same silicon chip has motivated the study of Silicon nanocrystals (Si‐ncs) embedded in SiOx (nonstoichiometric silicon oxides) films. In this work, Si‐ncs in SiOx films were obtained by Hot Wire Chemical Vapor Deposition (HWCVD) at 800, 900, and 1000°C. The vibration modes of SiOx films were determined by FTIR measurements. Additionally, FTIR and EDAX were related to get the proper composition of the films. Micro‐Raman studies in the microstructure of SiOx films reveal a transition from amorphous‐to‐nanocrystalline phase when the growth temperature increases; thus, Si‐ncs are detected. Photoluminescence (PL) measurement shows a broad emission from 400 to 1100 nm. This emission was related with both Si‐ncs and interfacial defects present in SiOx films. The existence of Si‐ncs between 3 and 6 nm was confirmed by HRTEM.