bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural and magnetic properties of Co–Mn–Sb thin films
Authors: Meinert Markus , Schmalhorst Jan-Michael , Ebke Daniel , Liu Ning-Ning , Thomas Andy , Reiss Günter , Kanak Jaroslaw , Stobiecki Tomasz , Arenholz Elke
Published: March 2010

Thin Co–Mn–Sb films of different compositions were investigated and utilized as electrodes in alumina based magnetic tunnel junctions with CoFe counterelectrode. The preparation conditions were optimized with respect to magnetic and structural properties. The Co–Mn–Sb/Al–O interface was analyzed by x-ray absorption spectroscopy and magnetic circular dichroism with particular focus on the element-specific magnetic moments. Co–Mn–Sb crystallizes in different complex cubic structures depending on its composition. The magnetic moments of Co and Mn are ferromagnetically coupled in all cases. A tunnel magnetoresistance ratio of up to 24% at 13 K was found and indicates that Co–Mn–Sb is not a ferromagnetic half-metal. These results are compared to recent works on the structure and predictions of the electronic properties.
Effect of confining conduit on effective viscosity of dilute colloidal suspension
Authors: Navardi Shahin , Bhattacharya Sukalyan
Published: March 2010

In this article, we discuss the effect of the bounding cylinder on the rheology of a dilute suspension. We consider a colloidal solution of spherical particles flowing through a cylinder under creeping motion assumption. For transport of such particulate fluid, the increase in the viscous loss due to the existence of suspended particles can be described in terms of enhanced effective viscosity ηeff for the medium. Einstein’s formula quantifies this increase in viscosity when the flow-domain is unbounded. For bounded domain, however, the increase in viscosity is not only dictated by the properties of the solutes but also affected by the geometry of the confinement. We illustrate this effect of geometry on the effective viscosity by accurately resolving the viscous interaction between a freely suspended sphere and a confining cylinder. First, we take into account a solution of equal spheres, and present the effective viscosity for different cylinder to sphere size ratio as well as for different excluded volume near the cylinder periphery for electrostatic interactions. Then, we also consider a variation in size distribution and determine the rheological properties for different means and variances of the distribution.
Statistical mechanics of two hard spheres in a spherical pore, exact analytic results in D dimension
Authors: Urrutia Ignacio , Szybisz Leszek
Published: March 2010

This work is devoted to the exact statistical mechanics treatment of simple inhomogeneous few-body systems. The system of two hard spheres (HSs) confined in a hard spherical pore is systematically analyzed in terms of its dimensionality D. The canonical partition function and the one- and two-body distribution functions are analytically evaluated and a scheme of iterative construction of the D+1 system properties is presented. We analyze in detail both the effect of high confinement, when particles become caged, and the low density limit. Other confinement situations are also studied analytically and several relations between the two HSs in a spherical pore, two sticked HSs in a spherical pore, and two HSs on a spherical surface partition functions are traced. These relations make meaningful the limiting caging and low density behavior. Turning to the system of two HSs in a spherical pore, we also analytically evaluate the pressure tensor. The thermodynamic properties of the system are discussed. To accomplish this statement we purposely focus in the overall characteristics of the inhomogeneous fluid system, instead of concentrate in the peculiarities of a few-body system. Hence, we analyze the equation of state, the pressure at the wall, and the fluid-substrate surface tension. The consequences of new results about the spherically confined system of two HSs in D dimension on the confined many HS system are investigated. New constant coefficients involved in the low density limit properties of the open and closed systems of many HS in a spherical pore are obtained for arbitrary D. The complementary system of many HS which surrounds a HS (a cavity inside of a bulk HS system) is also discussed.
Heterogeneous integration and precise alignment of InP-based photonic crystal lasers to complementary metal-oxide semiconductor fabricated silicon-on-insulator wire waveguides
Authors: Karle T. J. , Halioua Y. , Raineri F. , Monnier P. , Braive R. , Le Gratiet L. , Beaudoin G. , Sagnes I. , Roelkens G. , van Laere F. , Van Thourhout D. , Raj R.
Published: March 2010

The integration of two-dimensional III-V InP-based photonic crystal and silicon wire waveguides is achieved through an accurate alignment of the two optical levels using mix-and-match deep ultraviolet (DUV)/electron beam lithography. The adhesively bonded structures exhibit an enhancement of light emission at frequencies where low group velocity modes of the photonic crystal line defect waveguides occur. Pulsed laser operation is obtained from these modes at room temperature under optical pumping. The laser light is coupled out of the Si waveguide via grating couplers directly to single mode fiber.
A generalized bosonic oscillator in the presence of a minimal length
Authors: Falek M. , Merad M.
Published: March 2010

We present an exact solution of the three-dimensional Duffin–Kemmer–Petiau oscillator for spins 1 and 0 in the momentum space with the presence of minimal length uncertainty by the technique of vector spherical harmonics. The eigenfunctions are determined for both cases and the energy eigenvalues equation are obtained. The limiting case is then deduced for a small parameter of deformation.
Energy dissipation and resolution of steep gradients in one-dimensional Burgers flows
Authors: Tran Chuong V. , Dritschel David G.
Published: March 2010

Traveling-wave solutions of the inviscid Burgers equation having smooth initial wave profiles of suitable shapes are known to develop shocks (infinite gradients) in finite times. Such singular solutions are characterized by energy spectra that scale with the wave number k as k−2. In the presence of viscosity ν>0, no shocks can develop, and smooth solutions remain so for all times t>0, eventually decaying to zero as t→∞. At peak energy dissipation, say t=t∗, the spectrum of such a smooth solution extends to a finite dissipation wave number kν and falls off more rapidly, presumably exponentially, for k>kν. The number N of Fourier modes within the so-called inertial range is proportional to kν. This represents the number of modes necessary to resolve the dissipation scale and can be thought of as the system’s number of degrees of freedom. The peak energy dissipation rate ϵ remains positive and becomes independent of ν in the inviscid limit. In this study, we carry out an analysis which verifies the dynamical features described above and derive upper bounds for ϵ and N. It is found that ϵ satisfies ϵ≤ν2α−1‖u∗‖∞2(1−α)‖(−Δ)α/2u∗‖2, where α<1 and u∗=u(x,t∗) is the velocity field at t=t∗. Given ϵ>0 in the limit ν→0, this implies that the energy spectrum remains no steeper than k−2 in that limit. For the critical k−2 scaling, the bound for ϵ reduces to ϵ≤3k0‖u0‖∞‖u0‖2, where k0 marks the lower end of the inertial range and u0=u(x,0). This implies N≤3L‖u0‖∞/ν, where L is the domain size, which is shown to coincide with a rigorous estimate for the number of degrees of freedom defined in terms of local Lyapunov exponents. We demonstrate both analytically and numerically an instance, where the k−2 scaling is uniquely realizable. The numerics also return ϵ and t∗, consistent with analytic values derived from the corresponding limiting weak solution.
Abnormal current increases induced under high electric fields in asymmetrical graphite-intrinsic-diamond-graphite structures fabricated with high-quality homoepitaxial chemical-vapor-deposited diamond layers
Authors: Hamada Mitsuhiro , Teraji Tokuyuki , Ito Toshimichi
Published: March 2010

In order to investigate an abnormal current amplification phenomenon appearing in high-quality chemical-vapor-deposited (CVD) diamond under high electric fields, we have measured current-voltage and electroluminescence (EL) characteristics of an asymmetric graphite-intrinsic-diamond-graphite (G-ID-G) structure specially fabricated with a high-quality homoepitaxial CVD diamond layer. The G-ID-G structure included a flat G layer and a protrusive G layer, both of which were thin graphitic ones suitably formed on the surface layers of the CVD diamond using well-focused 30 keV Ga ions. The measured current-voltage data demonstrated that the voltages yielding the same currents were substantially lower when the protrusive G layer was positively biased. It turned out that the currents were reproduced with a sum of two components, namely, one injected from the positively biased G layer to the diamond, probably due to the Fowler–Nordheim tunneling mechanism, and the other yielding abnormal current increases in the diamond under high fields of the order of 106 V/cm. Furthermore, substantial EL was observed only in the voltage region the abnormal current increases obviously occurred. These facts and field calculations using a finite element method suggest both hole injections from the G layer to the ID layer and high-field-induced excitations of valence electrons in the ID layer to the conduction bands by the impact ionization process. An increase in the applied voltage by 15% was estimated to give a hundredfold amplification of the current. The present analysis of the measured data is discussed in detail in relation to the local structure of the high-quality diamond.
Gaseous environment-sensitive fluorescence of YAG:Ce3+ nanocrystals
Authors: Feofilov S. P. , Arsentyev D. V. , Kulinkin A. B. , Gacoin T. , Mialon G. , Meltzer R. S. , Dujardin C.
Published: March 2010

The influence of the surrounding gaseous media on optically excited fluorescence of YAG:Ce nanoparticles was studied. It was observed that the 5d→4f fluorescence of Ce3+ ions in YAG nanoparticles dramatically depends on the pressure of the gaseous media surrounding the powder samples. The observations suggest the possibility of probing the pressure at the single molecule level with nanoparticles. It is suggested that the observed effects result from gas-molecule-assisted electron transfer between the nanoparticles and from modification of the surface of the particles by adsorption of gas molecules.
Local instabilities of flow in a flexible channel: Asymmetric flutter driven by a weak critical layer
Authors: Stewart Peter S. , Waters Sarah L. , Jensen Oliver E.
Published: March 2010

We examine the linear stability of two-dimensional Poiseuille flow in a long channel confined by a rigid wall and a massless damped-tensioned membrane. We seek solutions that are periodic in the streamwise spatial direction and time, solving the homogeneous eigenvalue problem using a Chebyshev spectral method and asymptotic analysis. Several modes of instability are identified, including Tollmien–Schlichting (TS) waves and traveling-wave flutter (TWF). The eigenmode for neutrally stable downstream-propagating TWF in the absence of wall damping is shown to have a novel asymptotic structure at high Reynolds numbers, not reported in symmetric flexible-walled channels, involving a weak but destabilizing critical layer at the channel centerline where the wave speed is marginally greater than the maximum Poiseuille flow speed. We also show that TS instabilities along the lower branch of the neutral curve are modified remarkably little by wall compliance, but can be either stabilized or destabilized by wall damping. We discuss the energy budget underlying TWF and briefly describe the structure of other flow-induced surface instabilities.
Analytic model for the breakup of a coasting beam with space charge in isochronous accelerators
Authors: Bi Yuanjie , Zhang Tianjue , Tang Chuanxiang , Huang Yongsheng , Yang Jianjun
Published: March 2010

An analytical model based on the negative mass instability is introduced in this paper to explain the formation of the breakup of a coasting beam into small clusters in isochronous machines such as the case observed by Pozdeyev and Rodriguez in a small isochronous ring. Solving Poisson’s equation in both charge and vacuum regions with the longitudinal beam density perturbation, the coherent radial space charge force which decreases the transition gamma is obtained. It is found that the modified transition gamma depends on the wave number of the density perturbation, longitudinal beam density distribution, beam intensity, and beam size. By combining the longitudinal space charge force caused by the perturbation and the modified transition gamma, a dispersion relation for a monoenergetic beam is derived and evaluated for the fastest-growing instability mode in terms of the beam parameters, such as energy, bunch length, intensity, and emittance. The fastest-growing negative mass mode number, which determines not only the cluster number but also the growth rate of the instability, is proportional to the orbit radius and inversely proportional to the initial beam size. With the growth of the instability, the particles at the points of local minimum density move to the ones of local maximum density, with the transition gamma increasing. Since the growth rate depends on the longitudinal density distribution, therefore, instead of a constant growth rate, our model shows that the growth rate decreases with time. The results above can be applied to both short and long wavelength limits. As an important application of this theory, the beam breakup effect in the isochronous cyclotron CYCIAE-100 is predicted.
Confinement effects of CdSe nanocrystals intercalated into mesoporous silica
Authors: Chen Shu-Fang , Liu Chuan-Pu , Eliseev Andrei A. , Petukhov Dmitry I. , Dhara Sandip
Published: March 2010

CdSe nanocrystals are intercalated into ordered hexagonal arrays of mesoporous silica. The nanocrystals are clearly confined in the channels and their size was estimated to be consistent with the pore size. Transmission electron microscopy suggests that CdSe nanocrystals have a spherical morphology and are stabilized from aggregation after intercalation. The shift of the longitudinal optical bands in the Raman spectra is caused by a combination of phonon confinement and strain effects from the compressed lattice of the intercalated CdSe nanocrystals and the experimental results agree well to the theoretical consideration.
Lanthanum induced larger polarization and dielectric relaxation in Aurivillius phase SrBi2−xLaxNb2O9 ferroelectric ceramics
Authors: Fang Pinyang , Fan Huiqing , Li Jin , Liang Fujun
Published: March 2010

Ferroelectric ceramics SrBi2−xLaxNb2O9 (SBLNO) were prepared by a solid state reaction process. X-ray diffraction analysis indicated that single phase layered perovskites were obtained. The maximum dielectric permittivity peak broadened gradually with the lanthanum content increasing indicated that the phase transition from normal ferroelectrics to relaxorlike ferroelectrics occurs in SBLNO. The modified Curie–Weiss (CW) law was used to describe the relaxor behavior of SBLNO ceramics. The relaxation indication coefficient (γ) was estimated from a quadratic fit of modified CW law and was found to be 1.71 and 1.72 for SBLN20 and SBLN30 specimens, respectively. The substitution of La3+ ions for Bi3+ ions in the Bi2O2 layers resulted in a shift in the Curie point to lower temperature and an increase in remanent polarization and electrical field-induced strain. The maximum strain for SBLN30 specimen was found to be about 2.5×10−5 at the 5 MV/m. The nature of relaxor behavior of SBLNO is attributed to the cationic disordering at nanoscale on A site by the La3+ substituted Bi3+ of Bi2O2 layers.
A study on the effect factors of sol-gel synthesis of yttrium aluminum garnet nanopowders
Authors: Yang Lin , Lu Tiecheng , Xu Hui , Zhang Wei , Ma Benyuan
Published: March 2010

Yttrium aluminum garnet (YAG) nanopowders were synthesized by sol-gel method using aluminum nitrate, yttrium nitrate, and citric acid as starting materials, de-ionized water, ethanol, and ethylene glycol as solvents, respectively. The phase formation process, state of particle size distribution (PSD), compositions, morphological characteristics, and thermal behavior of the powders were investigated by means of x-ray diffractometry, PSD, Fourier transform infrared, transmission electronic microscope, and thermogravimetry-differential scanning calorimetry. Results indicate that the formation and characteristics of precursor gel and YAG powder, such as the rate of gelation, average particle size, and powder agglomerate state, strongly depend on the stoichiometric amount of citric acid, the solvent composition, and the precalcination process. Highly crystalline, well-dispersed YAG nanopowder was obtained by calcining at 800 °C for 2 h in the presence of citric acid to nitrate ratio of 3, ethanol solvent, and precalcination process. According to the analysis of experimental results, sol-gel chemistry, DLVO theory, and steric effect, the effects of stoichiometric amount of citric acid, solvent composition, and precalcination process on the formation and characteristics of precursor gel and YAG powder have been discussed. Meanwhile, the overall synthesis mechanism in sol-gel method has been suggested.
Transient infrared absorption of t-CH3C(O)OO, c-CH3C(O)OO, and α-lactone recorded in gaseous reactions of CH3CO and O2
Authors: Chen Sun-Yang , Lee Yuan-Pern
Published: March 2010

A step-scan Fourier-transform infrared spectrometer coupled with a multipass absorption cell was utilized to monitor the transient species produced in gaseous reactions of CH3CO and O2; IR absorption spectra of CH3C(O)OO and α-lactone were observed. Absorption bands with origins at 1851±1, 1372±2, 1169±6, and 1102±3 cm−1 are attributed to t-CH3C(O)OO, and those at 1862±3, 1142±4, and 1078±6 cm−1 are assigned to c-CH3C(O)OO. A weak band near 1960 cm−1 is assigned to α-lactone, cyc-CH2C(O)O, a coproduct of OH. These observed rotational contours agree satisfactorily with simulated bands based on predicted rotational parameters and dipole derivatives, and observed vibrational wavenumbers agree with harmonic vibrational wavenumbers predicted with B3LYP/aug-cc-pVDZ density-functional theory. The observed relative intensities indicate that t-CH3C(O)OO is more stable than c-CH3C(O)OO by 3±2 kJ mol−1. Based on these observations, the branching ratio for the OH+α-lactone channel of the CH3CO+O2 reaction is estimated to be 0.04±0.01 under 100 Torr of O2 at 298 K. A simple kinetic model is employed to account for the decay of CH3C(O)OO.
The Ã-X̃ absorption of vinoxy radical revisited: Normal and Herzberg–Teller bands observed via cavity ringdown spectroscopy
Authors: Thomas Phillip S. , Chhantyal-Pun Rabi , Kline Neal D. , Miller Terry A.
Published: March 2010

The Ã-X̃ electronic absorption spectrum of vinoxy radical has been investigated using room temperature cavity ringdown spectroscopy. Analysis of the observed bands on the basis of computed vibrational frequencies and rotational envelopes reveals that two distinct types of features are present with comparable intensities. The first type corresponds to “normal” allowed electronic transitions to the origin and symmetric vibrations in the Ã state. The second type is interpreted in terms of excitations to asymmetric Ã state vibrations, which are only vibronically allowed by Herzberg–Teller coupling to the B̃ state. Results of electronic structure calculations indicate that the magnitude of the Herzberg–Teller coupling is appropriate to produce vibronically induced transitions with intensities comparable to those of the normal bands.
Room temperature photonic crystal band-edge lasing from nanopillar array on GaN patterned by nanosphere lithography
Authors: Fu Wai Yuen , Wong Kenneth Kin-Yip , Choi H. W.
Published: March 2010

An ordered GaN nanopillar array fabricated by nanosphere lithography exhibited room temperature photopumped lasing via the photonic crystal band-edge effect. With a monolayer of self-assembled nanospheres as hard mask, the ordered pattern was transferred to the sample to form nanopillars by inductively coupled plasma dry etch. Under pulsed optical excitation, room temperature lasing with a low lasing threshold of 30 mJ/cm2 was achieved. The dominant lasing peak, centered at 415.6 nm, corresponds to a band-edge mode at the Γ-point of the band diagram. A Q factor in the range of 600–700, and spontaneous emission coupling factor of 0.021 were evaluated.
Preparation and characterization of p-type semiconducting tin oxide thin film gas sensors
Authors: Liu Xiaodi , Zhang Dacheng , Zhang Yang , Dai Xiaotao
Published: March 2010

P-type conducting undoped tin oxide thin film gas sensor is fabricated by direct current reactive magnetron sputtering method and calcination technique. Physical characteristics of the undoped tin oxide thin films have been analyzed by Spectroscopic ellipsometer, x-ray diffraction (XRD), scanning electronic microscope, and atomic force microscopy. According to the ethanol sensitivity properties of the sensors, we find that the calcination temperature and the thickness of the films are correlated with the special p-type conducting type; the p-type ultrathin film (10 nm) gas sensor shows better gas sensitivity and less baseline shift. XRD studies indicate that the preferred unidentified diffraction peak at 33.082° favors the formation of p-type conducting. When the intensities of unidentified diffraction peak increases, the gas sensing properties is largely promoted. The response time of the p-type sensor is less than 1 s to 1000 ppm ethanol.
Identification of the controlling parameter for the set-state resistance of a TiO2 resistive switching cell
Authors: Song Seul Ji , Kim Kyung Min , Kim Gun Hwan , Lee Min Hwan , Seok Jun Yeong , Jung Ranju , Hwang Cheol Seong
Published: March 2010

This study examined the parameter controlling the set-state resistance (Rset) of a Pt/TiO2/Pt resistive switching (RS) cell in unipolar RS mode. Although the compliance current in the current-voltage sweep had some effect on the Rset, the uncontrolled flow of charge from the parametric analyzer prevented making an accurate estimation of the parameters. The current transient in pulse switching observed using a high-speed digital oscilloscope and physical modeling showed that the capacitive charge moves vigorously at the moment of on-switching, and Rset is governed by the level of migrating charge. The actual switching time was ⪡50 ns.
Liquid-vapor equilibria and interfacial properties of n-alkanes and perfluoroalkanes by molecular simulation
Authors: Amat Miguel A. , Rutledge Gregory C.
Published: March 2010

A molecular dynamics study is presented to assess the performance of a united-atom model in the prediction of liquid-vapor interfacial properties for short-chain perfluoroalkanes and their alkane counterparts. In particular, the ability of this model to discriminate between the surface-energy values of these two types of compounds was investigated over a wide temperature range corresponding to the liquid-vapor region. Comparisons with available experimental data and surface-tension predictions given by other force-field parameterizations, including those based on the more computationally demanding all-atom method, were performed to gauge the viability of this model. It was found that the model used in this study captures qualitatively the expected behavior of surface energy between alkanes and perfluoroalkanes and yields values that are in excellent agreement with experimental data, especially in the high-temperature limit as the critical temperature is approached.
Conductive junctions with parallel graphene sheets
Authors: Zheng Xiao , Ke San-Huang , Yang Weitao
Published: March 2010

The establishment of conductive graphene-molecule-graphene junction is investigated through first-principles electronic structure calculations and quantum transport calculations. The junction consists of a conjugated molecule connecting two parallel graphene sheets. The effects of molecular electronic states, structure relaxation, and molecule-graphene contact on the conductance of the junction are explored. A conductance as large as 0.38 conductance quantum is found achievable with an appropriately oriented dithiophene bridge. This work elucidates the designing principles of promising nanoelectronic devices based on conductive graphene-molecule-graphene junctions.
Space-charge-limited current in organic light emitting diodes
Authors: Torricelli Fabrizio , Zappa Dario , Colalongo Luigi
Published: March 2010

A physically based mathematical model for the dc current of single-carrier organic light emitting diodes is presented. The model accounts for the most important physical quantities that influence the carrier mobility and thus the device current itself: temperature, charge carrier concentration, and electric field. It is rigorously developed basing on the variable range hopping transport theory and extends the pioneering work of Mark and Helfrich [J. Appl. Phys. 33, 205 (1962)] to large electric fields typical of light emitting diodes. It was validated on experimental data collected from devices of different materials in a wide range of operating conditions. Thanks to the effective electric field approach, the mathematical expression is simple, accurate and suitable for CAD applications.
Energy-harvesting device with mechanical frequency-up conversion mechanism for increased power efficiency and wideband operation
Authors: Jung Seok-Min , Yun Kwang-Seok
Published: March 2010

In this paper, we propose an energy-harvesting device that uses snap-through buckling for mechanical frequency-up conversion. The proposed device consists of buckled slender bridges with a proof mass and cantilever beams attached on them. When subjected to a low-frequency vibration above the threshold acceleration value, the buckled bridges snap through between two equilibrium states, providing high acceleration to the attached piezoelectric cantilever beams and thus causing them to resonate at a high frequency. A maximum power of 131 μW was generated at an excitation frequency of 30 Hz and a peak acceleration of 30 m/s2 by using a proposed device.
Hot electron transport in magnetic tunnel transistors with an epitaxial MgO tunnel barrier
Authors: Nagahama Taro , Saito Hidekazu , Yuasa Shinji
Published: March 2010

We fabricated fully epitaxial magnetic tunnel transistors (MTTs) consisting of a Fe(001)/MgO(001) emitter and a Fe(001) based on a n-GaAs(001) collector. We observed much higher transfer ratio (α) and magnetocurrent (MC) ratio than those of the previously reported MTTs that had an amorphous AlO barrier. These improvements are due to the coherent tunneling and single-crystalline base layer. In addition, a pronounced peak structure appeared in the emitter bias dependence of α, which might be attributed to the interface resonance states at the Fe(001)/GaAs(001) interface.
Frequency dependent electrical measurements of amorphous GeSbSe chalcogenide thin films
Authors: Mirsaneh M. , Furman E. , Ryan J. V. , Lanagan M. T. , Pantano C. G.
Published: March 2010

A commercial bulk chalcogenide glass (Ge28Sb12Se60) was used as a source to fabricate amorphous thin films via thermal evaporation technique. At low frequencies (<1 MHz) impedance spectroscopy was performed to measure electrical properties. To measure ac conductivity at microwave frequencies, a split resonance cavity technique was applied for which a model based on parallel arrangement of substrate and film capacitors was developed. This model was used to extract tan δ and ac conductivity of the films. Microwave ac conductivity was correlated with the extrapolated low frequency conductivity data confirming applicability of the universal law commonly observed in amorphous semiconductors.
Real-time atomic force microscopy imaging of photoinduced surface deformation in AsxSe100−x chalcogenide films
Authors: Trunov M. L. , Lytvyn P. M. , Nagy P. M. , Dyachyns’ka O. M.
Published: March 2010

We present direct measurements of the kinetics of surface relief gratings (SRGs) formation in amorphous AsxSe100−x (20≤xAs≤50) thin films. SRGs are induced in different holographic schemes of recording using near-band-gap light and their growth is further facilitated by illumination with an interference pattern and observed in real time by in situ atomic force microscopy. It is found that the kinetics of SRG formation depends upon film composition and incident light polarization. The light-stimulated vectorial surface deformations are maximized for Se-rich glasses and increase even further by additional illumination during recording.
Laser induced fluorescence spectroscopy of the jet-cooled carbon dioxide cation (C12O2+ and C13O2+)
Authors: Gharaibeh Mohammed A. , Clouthier Dennis J.
Published: March 2010

The Ã Π2u-X̃ Π2g band systems of jet-cooled C12O2+ and C13O2+ have been recorded by laser-induced fluorescence (LIF) techniques. Very intense, vibrationally cold expansions of these cations have been obtained using a pulsed electric discharge jet with a precursor mixture of carbon dioxide or C13 labeled CO2 in high pressure argon. The LIF bands have been partially rotationally analyzed to obtain band origins which yielded an accurate measure of the excited state vibronic energy levels. The energy levels of both isotopologues were fitted with a Renner–Teller model that included spin-orbit coupling, Fermi resonance and anharmonic terms. Single vibronic level emission spectra were also recorded for the C13O2+ ion and the ground state energy levels fitted using the same Renner–Teller model. The isotope relations have been used to test the validity of the derived parameters. The results give a through description of the vibronic energy levels in the ground and first excited electronic states of the carbon dioxide cation.
Limits of open circuit voltage in organic photovoltaic devices
Authors: Lo M. F. , Ng T. W. , Liu T. Z. , Roy V. A. L. , Lai S. L. , Fung M. K. , Lee C. S. , Lee S. T.
Published: March 2010

Open circuit voltage (Voc) of organic photovoltaic devices has been interpreted with either the metal-insulator-metal (MIM) model or the energy offset between highest occupied molecular orbital (HOMO) of the donor and the lowest unoccupied molecular orbital (LUMO) of the acceptor (HOMOD-LUMOA). To elucidate the relation between Voc and the two models, we have used electrodes of a wide range of work functions to connect the CuPc/C60 organic photovoltaic devices. We found that when the work function difference (Δϕelectrodes) between ITO and Al electrode is in the range −3 and 0 eV, Voc increases linearly with Δϕelectrodes as prescribed by the MIM model. Outside this range, Voc saturates with values close to that given by the HOMOD-LUMOA less the exciton binding energy.
Spin wave mode transition induced by surface anisotropy and characteristic length in magnetic nanoparticles
Authors: Zhou Peiheng , Zhang Li , Deng Longjiang
Published: March 2010

In magnetic nanoparticles with cylindrical symmetry of the magnetization configurations, spin wave mode transition (SWMT) is predicted for the case of a surface anisotropy parallel to the uniform magnetization. Theoretical investigation has shown that a characteristic length can be determined to evaluate the spatial influence of the spin wave mode excited by surface anisotropy. This knowledge implies SWMT occurs as the particle size exceeds the corresponding characteristic length. An indirect experimental observation of the SWMT is also provided. These results can be utilized for ferromagnetic resonances control in magnetic devices.
Thermal stability of TiN metal gate prepared by atomic layer deposition or physical vapor deposition on HfO2 high-K dielectric
Authors: Wu L. , Yu H. Y. , Li X. , Pey K. L. , Pan J. S. , Chai J. W. , Chiu Y. S. , Lin C. T. , Xu J. H. , Wann H. J. , Yu X. F. , Lee D. Y. , Hsu K. Y. , Tao H. J.
Published: March 2010

In this paper, the thermal stability of TiN metal gate with various composition prepared by different preparation technology [(e.g., atomic layer deposition (ALD) or physical vapor deposition (PVD)] on HfO2 high-K dielectric is investigated and compared by physical and electrical analysis. After annealing of the TiN/HfO2 stack at 1000 °C for 30 s, it is observed that: (1) Nitrogen tends to out-diffuse from TiN for all the samples; (2) Oxygen from the interfacial layer (IL) between HfO2 and Si tends to diffuse toward TiN. PVD Ti-rich TiN shows a wider oxygen distribution in the gate stack, and a thinner IL than the N-rich sample. Ti penetration into HfO2 is also observed in the Ti-rich sample, which can potentially lead to the dielectric break-down. Besides, the oxygen out-diffusion can be significantly suppressed for ALD TiN compared to the PVD TiN samples.
Application of thermal lens response to monitor health status of red blood cells: A quantitative study of the cell death process by extracting thermal diffusivity and size
Authors: Vasudevan Srivathsan , Chen George Chung Kit , Andika Marta
Published: March 2010

We explore monitoring the death process of individual red blood cells (RBC) quantitatively by using thermal lens (TL) response. TL response is a noninvasive excitation/probe technique that reflects photothermal parameters (e.g., absorption, thermal diffusivity, size, etc.). Since these parameters of cells change significantly during certain biological processes, real-time TL response was performed to monitor RBC death process when incubated with ionomycin. Theoretical model developed was applied to curve-fit the TL response for extracting thermal diffusivity and size of cells. Thermal diffusivity of dying RBC is found increased by 1.7 times in comparison with healthy cell.
Dynamic behavior of a liquid marble based accelerometer
Authors: Zeng H. , Zhao Y.
Published: March 2010

This paper reports dynamic behavior of a liquid-state accelerometer prototype, which uses a liquid marble as the inertial proof mass. The governing equation is developed in comparison with the solid-state proof mass in a conventional accelerometer. Numerical analysis and experimental validation show that with appropriate parameters, resonance frequency of the sensor can be designed below 10 Hz, which falls into the range of low frequency body motion. The work provides the basis for development of a new paradigm of motion sensing with reduced fabrication and assembly complexity, which is promising for next generation accelerometers for low frequency motion detection.
Plasmonic dark field microscopy
Authors: Hu Houdong , Ma Changbao , Liu Zhaowei
Published: March 2010

We propose plasmonic dark field microscopy, which utilizes a chip-scale integrated plasmonic multilayered structure to substitute the bulky and expensive conventional condenser optics. Experimental results show that we can get high contrast image using the compact, low-cost, and alignment free plasmonic dark field microscopy.
Graphene mode locked, wavelength-tunable, dissipative soliton fiber laser
Authors: Zhang Han , Tang Dingyuan , Knize R. J. , Zhao Luming , Bao Qiaoliang , Loh Kian Ping
Published: March 2010

Atomic layer graphene possesses wavelength-insensitive ultrafast saturable absorption, which can be exploited as a “full-band” mode locker. Taking advantage of the wide band saturable absorption of the graphene, we demonstrate experimentally that wide range (1570–1600 nm) continuous wavelength tunable dissipative solitons could be formed in an erbium doped fiber laser mode locked with few layer graphene.
Functional delivery of viral miRNAs via exosomes
Authors: Pegtel D. Michiel , Cosmopoulos Katherine , Thorley-Lawson David A. , van Eijndhoven Monique A. J. , Hopmans Erik S. , Lindenberg Jelle L. , de Gruijl Tanja D. , Würdinger Thomas , Middeldorp Jaap M.
Published: March 2010

Noncoding regulatory microRNAs (miRNAs) of cellular and viral origin control gene expression by repressing the translation of mRNAs into protein. Interestingly, miRNAs are secreted actively through small vesicles called “exosomes” that protect them from degradation by RNases, suggesting that these miRNAs may function outside the cell in which they were produced. Here we demonstrate that miRNAs secreted by EBV-infected cells are transferred to and act in uninfected recipient cells. Using a quantitative RT-PCR approach, we demonstrate that mature EBV-encoded miRNAs are secreted by EBV-infected B cells through exosomes. These EBV-miRNAs are functional because internalization of exosomes by MoDC results in a dose-dependent, miRNA-mediated repression of confirmed EBV target genes, including
CXCL11/ITAC
, an immunoregulatory gene down-regulated in primary EBV-associated lymphomas. We demonstrate that throughout coculture of EBV-infected B cells EBV-miRNAs accumulate in noninfected neighboring MoDC and show that this accumulation is mediated by transfer of exosomes. Thus, the exogenous EBV-miRNAs transferred through exosomes are delivered to subcellular sites of gene repression in recipient cells. Finally, we show in peripheral blood mononuclear cells from patients with increased EBV load that, although EBV DNA is restricted to the circulating B-cell population, EBV BART miRNAs are present in both B-cell and non-B-cell fractions, suggestive of miRNA transfer. Taken together our findings are consistent with miRNA-mediated gene silencing as a potential mechanism of intercellular communication between cells of the immune system that may be exploited by the persistent human γ-herpesvirus EBV.
The Decision to Prescribe: Influences and Choice
Authors: Thistlethwaite J.E. , Ajjawi Rola , Aslani Parisa
Published: March 2010

Prescribing is a fundamental activity of general practice and prescriptions are a major cost to the health service. Yet the art and practical details of prescribing are rarely learnt in medical school; junior doctors lack confidence in writing prescriptions ( Illing, 2008 ). Prescribing is not straightforward and involves a complicated decision-making process, by both patient and doctor, whose intricacies and governing factors are not yet well understood but where inadequate skills translate to suboptimal prescribing (Jackson et al., 2002). The prescribing process is not simply about choosing a medicine and writing a prescription.
Skin Malignancy
Authors: Wallis Katy , Gurusinghe Dilnath , Shiner Alice
Published: March 2010

Skin malignancies are extremely common with over 100 000 new cases diagnosed in the UK every year. Skin lesions may be a presenting complaint or identified as an incidental finding during consultation.
Depression in the Elderly
Authors: Funnell Emma
Published: March 2010

Depression is the most common mental illness in the elderly, with an estimated 15% of the elderly population living in the community having clinically significant depressive symptoms. It is of medical and social importance as it is associated with increased morbidity and mortality, poor quality of life and increased social dependence. Recognition of depression in this age group has been found to be poor, with more patients presenting with somatic physical symptoms. Treatment can also be difficult compared with younger patients, with increased prevalence of side effects of medication, polypharmacy and poor compliance. Primary care practitioners are therefore crucial in the detection and early instigation of appropriate treatment. This article looks at the risk factors, presentation and treatment options for depression in the elderly age group.
Fatigue and Lethargy in Palliative Care
Authors: Morgan Ken
Published: March 2010

Fatigue is the most common symptom experienced by patients with chronic progressive illnesses such as cancer, chronic heart failure (CHF), chronic obstructive pulmonary disease (COPD) and multiple sclerosis (MS). While it is normal to feel fatigue when the body or mind has been exerted, pathological fatigue is pervasive, may occur with little or no exertion and may not be relieved by sleep or rest. Fatigue has both physical and psychological components. It may manifest physically as a feeling of weakness or psychologically as mental tiredness, lack of motivation and reduced concentration.
Association of Gastric Heterotopic Pancreas and Esophageal Atresia in Children
Authors: Moreau Brigitte , Lévesque Dominique , Faure Christophe
Published: March 2010

Objectives:

Esophageal atresia with or without tracheo‐esophageal fistula is a frequent malformation that occurs in about 1 of 3000 live births. It can be associated with other congenital malformations. The aim of this study was to measure the frequency of heterotopic pancreas (HP) in children with esophageal atresia (EA) and to evaluate possible linkage with other malformations.

Materials and Methods:

All patients with EA were prospectively followed since 2005 at Hôpital Sainte‐Justine and since 2006 at the Montreal Children's Hospital. We compared 91 patients who underwent gastroscopy during that period with 182 control patients who submitted to gastroscopy for other indications. The presence or the absence of HP and its localization were noted in both groups. The following data were also collected on patients with EA: sex, gestational age, EA type, and other malformations.

Results:

Seventeen (18.7%) of the 91 patients with EA had gastric HP compared with 1 (0.5%) in the control group (OR 42, 95% confidence interval 7–249, P < 0.001). There were no differences between patients with or without HP regarding sex, prematurity, EA type, and the presence or absence of other congenital abnormalities.

Conclusions:

This study demonstrates, for the first time, that gastric HP is associated with EA irrespective of other malformations.
Validation of a Monoclonal Stool Antigen Test for Diagnosing Helicobacter pylori Infection in Young Children
Authors: Raguza Daniele , Machado Rodrigo Strehl , Ogata Silvio Kazuo , Granato Celso Francisco H , Patrício Francy Reis S , Kawakami Elisabete
Published: March 2010

Background and Objective:

The monoclonal stool antigen test for diagnosing Helicobacter pylori infection in children has been tested in developed countries, showing sensitivity and specificity higher than 90%. However, its accuracy in young children from developing countries is not well established. The aim of the study was to determine the accuracy of the monoclonal stool antigen test for diagnosing H pylori infection in children up to 7 years old.

Patients and Methods:

Two hundred seventy‐six patients (53.6% female; ages 0.35–6.99 years) were evaluated. Gold standard positive culture or positive histology and rapid urease tests were performed. The test (Amplified IDEIATM Hp StAR) was done according to the manufacturer's instructions. Results were expressed as optical density (OD) and an OD more than or equal to 0.190 was considered positive. Additionally, a receiver operating characteristic curve was used to find the best cutoff.

Results:

The monoclonal stool antigen test for diagnosing H pylori infection showed 100% sensitivity (95% confidence interval [CI] 92.7%–100%) and 76.2% specificity (95% CI 70.1%–81.4%), considering the manufacturer's cutoff. After setting a new cutoff with the receiver operating characteristic curve (OD = 0.400), sensitivity remained 100% (95% CI 92.7%–100%), but the specificity improved to 97.7% (95% CI 94.7%–99%). At ages up to 2 years, sensitivity was 100% (95% CI 43.8%–100%) and specificity was 100% (95% CI 92.4%–100%); at ages 2 to 4 years, 100% (95% CI 80.6%–100%) and 97.6% (95% CI 96%–99.2%); at ages older than 4 years, 100% (95% CI 88.6%–100%) and 96.6% (95% CI 94.7%–98%), respectively.

Conclusions:

The monoclonal stool antigen test is accurate for diagnosing H pylori in children younger than 7 years old, but it must be locally validated in order to find the best cutoff for each population.
Fat Malabsorption in Cystic Fibrosis: Comparison of Quantitative Fat Assay and a Novel Assay Using Fecal Lauric/Behenic Acid
Authors: Dorsey Jill , Buckley Donna , Summer Suzanne , Jandacek Ronald J , Rider Therese , Tso Patrick , Narkewicz Michael R , Heubi James E
Published: March 2010

Objectives:

The gold standard for the diagnosis of fat malabsorption, the 72‐hour fat balance study, requires a 3‐day collection to generate a coefficient of fat absorption (CFA). We hypothesized that a new test using behenic acid (behenate test) as a nonabsorbable lipid marker may provide a facile means to assess fat absorption. The study proposed to answer 2 questions: first, whether the behenate test correlated with the gold standard and, second, whether the CFA improved when taking pancreatic enzymes during meals instead of taking them before meals.

Patients and Methods:

The study compared the behenate test with the gold standard in 15 patients with cystic fibrosis during 3 arms that require 3‐ to 4‐day hospitalization: first, taking pancreatic enzymes before meals; second, taking it during meals; and third, without taking it.

Results:

The mean CFA was 78.3% when pancreatic enzymes were taken during meals and 80.4% when these enzymes were taken before meals. Correlation between the CFA and the behenate test for collections during all 3 arms was r2 = 0.219 (P = 0.001).

Conclusions:

Timing of ingestion of pancreatic enzymes does not significantly alter the CFA. Although the CFA correlates with the behenate test, the correlation is not robust enough to justify replacement of the gold standard by this test. It is unclear whether the poor correlation between tests relates to intermeal variability in fat excretion or other factors; however, the behenate test may be suitable as a screening test for the detection of fat malabsorption.
Atopy Patch Test for Early Diagnosis of Cow's Milk Allergy in Preterm Infants
Authors: Dupont C , Soulaines P , Lapillonne A , Donne N , Kalach N , Benhamou PH
Published: March 2010

Atopy patch test may help early diagnosis of cow‐milk allergy in preterm infants. In the retrospective analysis of 5 girls and 9 boys, born at 31 ± 2 (mean ± SD) weeks of gestation and presenting digestive symptoms at age 42 ± 18 days, 10 had a complete recovery following the shift to an exclusive feeding with an amino acid–based formula. Cow‐milk–skin prick tests and specific immunoglobulin E were always negative, whereas the atopy patch test was positive in 7 of the 10 infants with complete recovery.
Serum Markers May Distinguish Biliary Atresia From Other Forms of Neonatal Cholestasis
Authors: Wang Hongtao , Malone James P , Gilmore Petra Erdmann , Davis Alan E , Magee John C , Townsend R Reid , Heuckeroth Robert O
Published: March 2010

Background:

Biliary atresia (BA) is the most serious liver disease in infants. Diagnosis currently depends on surgical exploration of the biliary tree. Noninvasive tests that distinguish BA from other types of neonatal liver disease are not available.

Patients and Methods:

To identify potential serum biomarkers that classify children with neonatal cholestasis, we performed 2‐dimensional difference gel electrophoresis, statistical analysis, and tandem mass spectrometry using serum samples from 19 infants with BA and 19 infants with non‐BA neonatal cholestasis.

Results:

Eleven potential serum biomarkers were found that could in combination classify children with neonatal cholestasis.

Conclusions:

Although no single biomarker or imaging test adequately distinguishes BA from other types of neonatal cholestasis, combinations of biomarkers, imaging tests, and noninvasive clinical criteria should be further explored as potential tests for rapid and accurate diagnosis of BA.