bluuebunny/crossref_metadata_2025 huggingface dataset:
Importance of minority carrier response in accurate characterization of Ge metal-insulator-semiconductor interface traps
Authors: Taoka Noriyuki , Yamamoto Toyoji , Harada Masatomi , Yamashita Yoshimi , Sugiyama Naoharu , Takagi Shinichi
Published: August 2009

The ac signal response of majority and minority carriers at interface traps has been systematically investigated for Ge metal-insulator-semiconductor (MIS) interfaces by the conductance method. The conventional model including only the majority carrier response is compared with a newly proposed model, which includes the majority and minority carrier responses at interface traps. It is found that the conventional model cannot represent the measured conductance-frequency (G-F) curves of a Ge MIS capacitor near room temperature. It is revealed, on the other hand, that the modified model including the both types of carrier responses can accurately represent the measured G-F curves under the bias conditions from depletion to weak inversion even near room temperature. This demonstrates that the analysis including the both types of carriers responses is quite important in applying the conductance method to the Ge MIS capacitors near room temperature and that the model gives the accurate interface properties. As a result, the electron capture cross section of the Ge MIS capacitors is found to be almost independent of energy as is the case of a Si metal-oxide-semiconductor interface, suggesting that the defect structure similar to the Si MOS interface could be formed at the Ge MIS interface.
Localized ferromagnetic resonance force microscopy in Permalloy-cobalt films
Authors: Nazaretski E. , Obukhov Yu. , Martin I , Pelekhov D. V. , Cha K. C. , Akhadov E. A. , Hammel P. C. , Movshovich R.
Published: August 2009

We report ferromagnetic resonance force microscopy (FMRFM) experiments on a juxtaposed continuous films of Permalloy and cobalt. Our studies demonstrate the capability of FMRFM to perform local spectroscopy of different ferromagnetic materials. Theoretical analysis of the uniform resonance mode near the edge of the film agrees quantitatively with experimental data. Our experiments demonstrate the micron scale lateral resolution in determining local magnetic properties in continuous ferromagnetic samples.
Development and performance test of a soft x-ray polarimeter and ellipsometer for complete polarization analysis
Authors: Imazono Takashi , Sano Kazuo , Suzuki Yoji , Kawachi Tetsuya , Koike Masato
Published: August 2009

A new apparatus for polarimetric and ellipsometric measurements based on the rotating-analyzer method in the soft x-ray region has been designed, constructed, and installed in the soft x-ray beamline (BL-11) at the SR Center of Ritsumeikan University, Shiga, Japan. It can realize the optical configurations for the complete polarization analysis by using six independently movable drive shafts. A demonstration of the capabilities of the apparatus has been performed using Mo/Si multilayer polarizers deposited by an ion beam sputtering method. It is for the first time shown that the degree of linear polarization of monochromatized light from the BL-11 is approximately 87% at 92 eV since the beamline has been constructed.
Surface treatment and bulk density of ions in nematic liquid crystals
Authors: Alexe-Ionescu A. L. , Barbero G. , Ciuchi F. , Mazzulla A. , Scaramuzza N.
Published: August 2009

The frequency dependence of the electrical impedance of a planar nematic sample in the shape of a slab is investigated. The measurements are performed by means of an external voltage of small amplitude (a few tens of millivolts) in such a manner that the liquid crystal behaves as a linear system from the electrical point of view. In this framework, the nematic orientation induced by the external field is absent because the applied voltage is smaller than the critical one for the transition of Freedericksz for the considered geometry. Our measurements indicate that the real part of the impedance presents a large plateau, finishing at the frequency of Debye. Whereas the imaginary part diverges in the low frequency region, indicating that the electrodes of the cell behave as blocking electrodes. From the value of the plateau of the resistance of the cell and from the frequency of Debye, we can conclude that the surface treatment to orient the nematic liquid crystal has a strong influence on the bulk density of ions. The experimental data relevant to the real and imaginary part of the impedance of the cell have been analyzed with a model based on the equations of continuity for the positive and negative ions and on the equation of Poisson for the actual electrical potential across the sample. By assuming that there is only a type of positive and negative ions and that the electrodes are perfectly blocking, except adsorb ions, we show that the agreement between theoretical predictions and experimental data is good.
Influence of annealing atmosphere on the magnetic properties of SiO2/Fe/SiO2 sandwiched nanocomposite films
Authors: Zhu P. L. , Xue F. , Liu Z. , Fan Y. L. , Jiang Z. M. , Yang X. J.
Published: August 2009

The magnetic properties of SiO2/Fe/SiO2 nanocomposite films are studied by magnetic force microscopy and vibrating sample magnetometer. The films were fabricated by alternately depositing SiO2, Fe, and SiO2 on Si substrates with magnetron sputtering followed by thermal annealing. It is found that the annealing atmosphere significantly influences the sample structure, composition, and magnetic properties. The samples annealed in forming gas show much better magnetic properties than those annealed in vacuum and in N2. The saturation magnetization can reach 200 emu/g, fairly close to the value of bulk Fe, and the coercivity can reach 400 Oe, much higher than 10 Oe of the bulk Fe. X-ray photoelectron spectroscopic depth profile measurement was carried out to study the mechanism of the strong influence of annealing atmosphere. For the samples annealed in forming gas, Fe nanoparticles are mildly oxidized, forming thin shells of Fe2O3 surrounding them, which is beneficial for maintaining the ferromagnetic behavior and enhancing the coercivity of nanoparticles.
Near-field heat transfer mediated by surface wave hybridization between two films
Authors: Ben-Abdallah Philippe , Joulain Karl , Drevillon Jérémie , Domingues Gilberto
Published: August 2009

Using the general formalism of the fluctuational electrodynamics we extend the classical theory of near-field heat transfer between massive materials to any couple of films. An analytic expression for the net flux exchanged between two films in nonequilibrium thermal situation is derived. We show that the finite size effects and specifically hybridization of nondegenerated surface modes throughout the intrafilm cavity radically change the features of noncontact heat exchanges. This result should have important implications in the study of near-field heat transport between nanostructured materials.
The edge spectrum of Chern insulators with rough boundaries
Authors: Prodan Emil
Published: August 2009

Chern insulators are periodic band insulators with the property that their projector onto the occupied bands has a nonzero Chern number. From numerical calculations, it is known that a Chern insulator with a homogeneous boundary displays a continuum spectrum that fills the entire insulating gap. The local density of states corresponding to this part of the spectrum is localized near the boundary, hence the terminology edge spectrum. An interesting question arises, namely, if a rough boundary, which can be seen as a strong random potential acting on these quasi-one-dimensional states, would destroy the continuum edge spectrum. Numerical simulations seem to indicate that the answer is no. The present paper shows how the question can be answered analytically by connecting the expectation value of the charge edge current to the index of a Fredholm operator, which remains invariant under arbitrary deformations of the boundary.
Electron Hall mobility in GaAsBi
Authors: Kini R. N. , Bhusal L. , Ptak A. J. , France R. , Mascarenhas A.
Published: August 2009

We present measurements of the electron Hall mobility in n-type GaAs1−xBix epilayers. We observed no significant degradation in the electron mobility with Bi incorporation in GaAs, up to a concentration of 1.2%. At higher Bi concentration (≥1.6%) some degradation of the electron mobility was observed, although there is no apparent trend. Temperature dependent Hall measurements of the electron mobility suggest neutral impurity scattering to be the dominant scattering mechanism.
Atomically resolved Larmor frequency detection on Si(111)-7×7 oxide surface
Authors: Sainoo Yasuyuki , Isshiki Hironari , Shahed Syed Mohammad Fakruddin , Takaoka Tsuyoshi , Komeda Tadahiro
Published: August 2009

We demonstrate that the electron spin resonance–scanning tunneling microscope can detect the Larmor frequency of a single spin with the atomic scale resolution on the oxygen-adsorbed Si(111)-7×7 surface. The spin signal from the Si dangling bond was detected on the oxygen-induced bright Si adatom with the Larmor frequency corresponding to g∼2.00. However, no peak was detected on the dark adatom that is tied with an oxygen atom and the dangling bond is disappeared.
Ab initio electronic and optical spectra of free-base porphyrins: The role of electronic correlation
Authors: Palummo Maurizia , Hogan Conor , Sottile Francesco , Bagalá Paolo , Rubio Angel
Published: August 2009

We present a theoretical investigation of electronic and optical properties of free-base porphyrins based on density functional theory and many-body perturbation theory. The electronic levels of free-base porphine (H2P) and its phenyl derivative, free-base tetraphenylporphyrin (H2TPP) are calculated using the ab initio GW approximation for the self-energy. The approach is found to yield results that compare favorably with the available photoemission spectra. The excitonic nature of the optical peaks is revealed by solving the Bethe–Salpeter equation, which provides an accurate description of the experimental absorption spectra. The lowest triplet transition energies are in good agreement with the measured values.
M
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loop tracer based on digital signal processing for low frequency characterization of extremely thin magnetic wires
Authors: Butta M. , Infante G. , Ripka P. , Badini-Confalonieri G. A. , Vázquez M.
Published: August 2009

A high-sensitivity ac hysteresis loop tracer has been developed to measure the low frequency hysteresis loop of soft magnetic materials. It has been applied successfully to characterize straight pieces of amorphous glass-covered microwires with metallic nucleus down to 1.5 μm thick. Based on the electromagnetic induction law, the proposed design is extremely simple and exploits the capabilities of commercially available data acquisition cards together with digital signal processing in order to achieve high-sensitivity without the need of expensive analog equipment.
Production of a single spin-rotational state [(J,M)=(2,2)] selected molecular oxygen (Σ3g−) beam by a hexapole magnet
Authors: Kurahashi Mitsunori , Yamauchi Yasushi
Published: August 2009

A state-selected O2(Σ3g−) molecular beam, in which nearly 100% of the molecules are in the spin-rotational state of (J,M)=(2,2), has been produced by combining a supersonic seeded O2 beam with a hexapole magnet. The (2,−2) beam has also been obtained by the state inversion of the (2,2) beam through the nonadiabatic passage in a reversing longitudinal magnetic field along the beam axis. The intensities of the other (2,M) states, which appear when applying additional transverse magnetic fields to the reversing field region, were well reproduced by the Majorana’s formula for J=2. The (2,±2) beam, for which we can determine the spin and rotational angular momenta of O2 almost independently, is the most promising probe for studying the spin effects as well as the steric effects in O2 molecular scattering.
Photoluminescence and electron paramagnetic resonance studies of springlike carbon nanofibers
Authors: Gupta Bipin Kumar , Shanker V. , Arora Manju , Haranath D.
Published: August 2009

Carbon nanofiber (CNF) with springlike and double-helix structures has been synthesized by catalytic thermal pyrolysis of an acetylene precursor at 850–950 °C using iron nanopowder and thiophene as catalyst and promoter, respectively. High resolution electron microscopy revealed a higher d-spacing (∼3.46 Å) of (002) crystal plane than customary multiwalled carbon nanotube (MWCNT) (3.37 Å) that helps in sustaining mechanical shocks better than MWCNTs. The large surface to volume ratio of springlike CNF does provide many delocalized free electrons to enhance the photoluminescence activity. Electron paramagnetic resonance signal showed a single narrow line having g-value 2.0024±0.0002 and spin contribution 3.4956×10−16 spins/g.
Line tension of a two dimensional gas-liquid interface
Authors: Santra Mantu , Bagchi Biman
Published: August 2009

In two dimensional (2D) gas-liquid systems, the reported simulation values of line tension are known to disagree with the existing theoretical estimates. We find that while the simulation erred in truncating the range of the interaction potential, and as a result grossly underestimated the actual value, the earlier theoretical calculation was also limited by several approximations. When both the simulation and the theory are improved, we find that the estimate of line tension is in better agreement with each other. The small value of surface tension suggests increased influence of noncircular clusters in 2D gas-liquid nucleation, as indeed observed in a recent simulation.
Ab initio thermodynamic evaluation of Pd atom interaction with CeO2 surfaces
Authors: Mayernick Adam D. , Janik Michael J.
Published: August 2009

Palladium supported on ceria is an effective catalytic material for three-way automotive catalysis, catalytic combustion, and solid-oxide fuel cell (SOFC) anodes. The morphology, oxidation state, and particle size of Pd on ceria affect catalytic activity and are a function of experimental conditions. This work utilizes ab initio thermodynamics using density functional theory (DFT) (DFT+U) methods to evaluate the stability of Pd atoms, PdOx species, and small Pd particles in varying configurations on CeO2 (111), (110), and (100) single crystal surfaces. Over specific oxygen partial pressure and temperature ranges, palladium incorporation to form a mixed surface oxide is thermodynamically favorable versus other single Pd atom states on each ceria surface. For example, Pd atoms may incorporate into Ce fluorite lattice positions in a Pd4+ oxidation state on the CeO2 (111) surface. The ceria support shifts the transition between formal Pd oxidation states (Pd0, Pd2+, Pd4+) relative to bulk palladium and stabilizes certain oxidized palladium species on each surface. We show that temperature, oxygen pressure, and cell potential in a SOFC can influence the stable states of palladium supported on ceria surfaces, providing insight into structural stability during catalytic operation.
The photon haystack and emerging radiation detection technology
Authors: Runkle Robert C. , Smith L. Eric , Peurrung Anthony J.
Published: August 2009

The resources devoted to interdicting special nuclear materials have increased considerably over the last several years in step with growing efforts to counter nuclear proliferation and nuclear terrorism. This changing landscape has led to a large amount of research and development that aims to improve the effectiveness of technology now deployed worldwide. Interdicting special nuclear materials is most commonly addressed by detecting and characterizing emitted gamma rays, but modest signature emissions can be obscured by attenuating material and must be differentiated from large and highly variable environmental background emissions. It is a daunting technical challenge to identify special nuclear materials via gamma-ray detection, but a host of new detection technologies is now emerging. This challenge motivates our review of special nuclear material signatures, the physics of detection approaches, emerging technologies, and performance metrics. The use of benchmark gamma-ray sources aids our discussion.
The role of a delay time on the spatial structure of chaotically advected reactive scalars
Authors: Tzella Alexandra , Haynes Peter H.
Published: August 2009

The stationary-state spatial structure of reacting scalar fields, chaotically advected by a two-dimensional large-scale flow, is examined for the case for which the reaction equations contain delay terms. Previous theoretical investigations have shown that, in the absence of delay terms and in a regime where diffusion can be neglected (large Péclet number), the emergent spatial structures are filamental and characterized by a single scaling regime with a Hölder exponent that depends on the rate of convergence of the reactive processes and the strength of the stirring measured by the average stretching rate. In the presence of delay terms, we show that for sufficiently small scales all interacting fields should share the same spatial structure, as found in the absence of delay terms. Depending on the strength of the stirring and the magnitude of the delay time, two further scaling regimes that are unique to the delay system may appear at intermediate length scales. An expression for the transition length scale dividing small-scale and intermediate-scale regimes is obtained and the scaling behavior of the scalar field is explained. The theoretical results are illustrated by numerical calculations for two types of reaction models, both based on delay differential equations, coupled to a two-dimensional chaotic advection flow. The first corresponds to a single reactive scalar and the second to a nonlinear biological model that includes nutrients, phytoplankton, and zooplankton. As in the no delay case, the presence of asymmetrical couplings among the biological species results in a nongeneric scaling behavior.
A ultraviolet-visible-near infrared photodetector using nanocrystalline Si superlattice
Authors: Yu Zhenrui , Aceves-Mijares Mariano
Published: August 2009

We report a simple silicon/Si nanocrystal superlattice/indium tin oxide structure as a photodetector, which shows a very high photosensitivity in a wide wavelength range from ultraviolet (UV) to near infrared. The fabrication of this photodetector structure is easily integrated into a standard process of Si microelectronics. The light and dark current versus voltage characteristics and photoluminescence of the photodetector show that the optical down-conversion of UV light by the superlattice layer is the main reason of the enhanced UV response.
Electrical control of singlet-triplet entanglement in lateral quantum dot molecules
Authors: Qu Fanyao , Iório G. L. , Lopez-Richard V. , Marques G. E.
Published: August 2009

We study effects of spin-orbit coupling and electron-electron correlation, which can be electrically tuned, on the singlet-triplet entanglement in double lateral quantum dots charged with two electrons. We have found that the magnetic character of a double-dot system can be changed from diamagnetic to paramagnetic, only by adjusting the strength of spin-orbit coupling. Coulomb interaction leads to an unusual singlet-triplet energy splitting, accompanied by a shift of this transition energy to the lower magnetic field side in the energy spectrum.
Homogeneous nucleation rate measurements in supersaturated water vapor II
Authors: Brus David , Ždímal Vladimír , Uchtmann Hermann
Published: August 2009

The homogeneous nucleation of water was studied experimentally in this work using a thermal diffusion cloud chamber; droplets were counted by the photomultiplier method and helium was used as a carrier gas. The nucleation rates range from 3×10−2 to 3×101 cm−3 s−1 and six isotherms from 295 to 320 K with step of 5 K are measured. The experimental setup and obtained data are mutually compared to our previous publication [Brus et al., J. Chem. Phys. 129, 174501 (2008)], where the droplets were counted using digital photography and image processing. The molecular content of the critical clusters was estimated from the slopes of experimental data. The measured isothermal dependencies of the nucleation rate of water on the saturation ratio were compared with previously published data of others, several theoretical predictions, and the former nucleation onset data. The aim of the present investigation was to show for the first time that nucleation results can be quantitatively reproduced with two different experimental setups operated in different ways.
Enhanced performance of silicon quantum dot light-emitting diodes grown on nanoroughened silicon substrate
Authors: Kim Baek Hyun , Davis Robert F. , Cho Chang-Hee , Park Seong-Ju
Published: August 2009

We report the effect of a nanoroughened Si substrate on silicon quantum dot (Si QD) light-emitting diodes (LEDs). The electroluminescence of Si QD LEDs grown on the nanoroughened Si substrate was remarkably improved by 493% at an injection current of 90 mA compared to those of Si QD LEDs grown on the flat Si substrate. The electrical and optical enhancements were attributed to the enhanced inhomogeneous local electric field on the nanoroughened Si surface and the angular randomization of photons emitted from Si QDs at the nanoroughened surface of silicon nitride layer containing Si QDs.
Raman stress mapping of CdS nanosheets
Authors: Montazeri Mohammad , Smith Leigh M. , Jackson Howard E. , Yarrison-Rice Jan M. , Choi Young-Jin , Park Jae-Gwan
Published: August 2009

Spatially resolved Raman scattering is used to probe the strain distribution in CdS nanosheets. We observe both significant strains and a significant strain gradient across the nanosheets. The magnitude of the strain suggests that electronic properties of the CdS nanosheets will be influenced as well. Using spatially resolved photoluminescence spectroscopy, we show that the band gap of the nanosheet experiences changes in the energy gap of 20 meV across the width of the nanosheet, which are consistent with our observations of the strain.
Resonant response of forced complex networks: The role of topological disorder
Authors: Chen Hanshuang , Shen Yu , Hou Zhonghuai , Xin Houwen
Published: August 2009

We investigate the effect of topological disorder on a system of forced threshold elements, where each element is arranged on top of complex heterogeneous networks. Numerical results indicate that the response of the system to a weak signal can be amplified at an intermediate level of topological disorder, thus indicating the occurrence of topological-disorder-induced resonance. Using mean field method, we obtain an analytical understanding of the resonant phenomenon by deriving the effective potential of the system. Our findings might provide further insight into the role of network topology in signal amplification in biological networks.
Nonlinear skin effect in a collisionless plasma
Authors: Froese A. M. , Smolyakov A. I. , Sydorenko D.
Published: August 2009

The skin effect in a warm collisionless plasma is studied via one-dimensional advective particle-in-cell simulations. It is found that the skin depth exhibits nonlinear behavior at low frequencies. A simple model describing the nonlinear behavior of the skin depth is proposed and shown to match the results of the simulations well. The transitions between local, anomalous, and nonlinear skin effect regimes are investigated in the parameter space of wave frequency and amplitude.
Trapped rainbow effect in visible light left-handed heterostructures
Authors: Zhao X. P. , Luo W. , Huang J. X. , Fu Q. H. , Song K. , Cheng X. C. , Luo C. R.
Published: August 2009

We experimentally demonstrate the trapped rainbow in tapered left-handed heterostructures (LHHs) at visible frequencies. The employed left-handed metamaterials (LHMs) are isotropic with the size of hundreds of square millimeter. Specifically, the LHMs sample at visible frequencies has a broad spectral range and low loss, making it an intrinsic optical response for the LHHs. It is found that the frequency components of the wave packet separate at positions with different guide thicknesses only if the inclination of tapered LHHs is greater than zero and smaller than the critical value.
Strong and ductile nanostructured Cu-carbon nanotube composite
Authors: Li Hongqi , Misra Amit , Horita Zenji , Koch Carl C. , Mara Nathan A. , Dickerson Patricia O. , Zhu Yuntian
Published: August 2009

Nanocrystalline carbon nanotube (CNT)—reinforced Cu composite (grain size <25 nm) with high strength and good ductility was developed. Pillar testing reveals that its strength and plastic strain could be as large as 1700 MPa and 29%, respectively. Compared with its counterpart made under the same condition, an addition of 1 wt % CNTs leads to a dramatic increase in strength, stiffness and toughness without a sacrifice in ductility. Microstructural analysis discloses that in the Cu matrix, CNTs could be distributed either at grain boundaries or inside grains and could inhibit dislocation nucleation and motion, resulting in an increase in the strength.
Study on the formation of dodecagonal pyramid on nitrogen polar GaN surface etched by hot H3PO4
Authors: Qi S. L. , Chen Z. Z. , Fang H. , Sun Y. J. , Sang L. W. , Yang X. L. , Zhao L. B. , Tian P. F. , Deng J. J. , Tao Y. B. , Yu T. J. , Qin Z. X. , Zhang G. Y.
Published: August 2009

Hot phosphor acid (H3PO4) etching is presented to form a roughened surface with dodecagonal pyramids on laser lift-off N face GaN grown by metalorganic chemical vapor deposition. A detailed analysis of time evolution of surface morphology is described as a function of etching temperature. The activation energy of the H3PO4 etching process is 1.25 eV, indicating the process is reaction-limited scheme. And it is found that the oblique angle between the facets and the base plane increases as the temperature increases. Thermodynamics and kinetics related factors of the formation mechanism of the dodecagonal pyramid are also discussed. The light output power of a vertical injection light-emitting-diode (LED) with proper roughened surface shows about 2.5 fold increase compared with that of LED without roughened surface.
Intermediate-band material based on GaAs quantum rings for solar cells
Authors: Wu Jiang , Shao Dali , Li Zhenhua , Manasreh M. O. , Kunets Vasyl P. , Wang Zhiming M. , Salamo G. J.
Published: August 2009

The intermediate-band concept is invoked to explain the photoresponse spectra obtained for unbiased devices fabricated from GaAs quantum rings grown by a droplet epitaxy technique on lattice-matched Al0.3Ga0.7As barriers. The photoresponse spectra where measured at room temperature in the visible-near-infrared spectral range. The presence of the intermediate band in the device active region is confirmed by measuring the mid-infrared photoresponse, which is attributed to the intersubband transitions in the conduction band. The photocurrent was measured at room temperature and found to be about four orders of magnitude larger than the dark current in the voltage range of ± 4.0 V.
Excellent field emission from semialigned carbon nanofibers grown on cylindrical copper surface
Authors: Mahanandia P. , Arya V. , Bhotla P. V. , Subramanyam S. V. , Schneider J. J. , Nanda K. K.
Published: August 2009

We report the field emission from carbon nanofibers (CNFs) grown directly on cylindrical copper by a simple pyrolysis technique. The turn-on field is 0.17 V/μm and the emission current density is 0.9 mA/cm2 at 0.35 V/μm. The emission current is stable at a field of 0.35 V/μm and 6.5×10−6 Torr. The excellent field emission behavior is attributed to the sp2 phase in CNFs and the stable emission is due to the direct growth. The direct growth on cylindrical cathode is advantageous for field emission.
A large magnetoinductance effect in La0.67Ba0.33MnO3
Authors: Naik V. B. , Rebello A. , Mahendiran R.
Published: August 2009

We report four probe impedance (Z=R+iX) of La0.67Ba0.33MnO3 at f=100 kHz under different dc bias magnetic fields. The ac resistance (R) exhibits a peak around TP=325 K which is accompanied by a rapid increase and a peak in the reactance (X) in a zero field. The magnetoreactance (ΔX/X) exhibits a sharp peak close to TP and its magnitude (≈60% in H=1 kG) exceeds that of the ac magnetoresistance (ΔR/R=5%). It is suggested that the magnetoreactance arises from changes in the self inductance of the sample rather than the capacitance.
Crystallization times of Ge–Te phase change materials as a function of composition
Authors: Raoux S. , Cheng H.-Y. , Caldwell M. A. , Wong H.-S. P.
Published: August 2009

The crystallization times of Ge–Te phase change materials with variable Ge concentrations (29.5–72.4 at. %) were studied. A very strong dependence of the crystallization time on the composition for as-deposited, amorphous films was confirmed, with a minimum for the stoichiometric composition GeTe. The dependence is weaker for melt-quenched, amorphous material and crystallization times are between one to almost four orders of magnitude shorter than for as-deposited materials. This is promising for applications because recrystallization from the melt-quenched phase is the relevant process for optical and solid state memory, and fast crystallization and weak dependence on compositional variations are desirable.
Optical contrast and clarity of graphene on an arbitrary substrate
Authors: Wang Xuefeng , Zhao Ming , Nolte David D.
Published: August 2009

A molecularly thin dielectric film on a multilayer substrate can be treated as an additive perturbation of the substrate reflection coefficient r, for which the perturbation depends only on r and the optical properties of the film. This general result is applied to the problem of graphene on arbitrary substrates that seek to maximize the film contrast. We define clarity to describe the graphene image quality in the presence of charge-coupled device noise. A substrate with r=1 produces the highest graphene clarity in most practical situations.
Tunable thermal conductivity of Si1−xGex nanowires
Authors: Chen Jie , Zhang Gang , Li Baowen
Published: August 2009

By using molecular dynamics simulation, we demonstrate that the thermal conductivity of silicon-germanium nanowires (Si1−xGex NWs) depends on the composition remarkably. The thermal conductivity reaches the minimum, which is about 18% of that of pure Si NW, when Ge content is 50%. More interesting, with only 5% Ge atoms (Si0.95Ge0.05 NW), SiNW’s thermal conductivity is reduced to 50%. The reduction of thermal conductivity mainly comes from the localization of phonon modes due to random scattering. Our results demonstrate that Si1−xGex NW might have promising application in thermoelectrics.
Light-induced EPR spectroscopy of charge carriers photoinduced in polymer/fullerene bulk heterojunctions
Authors: Krinichnyi V. I. , Yudanova E. I.
Published: August 2009

Composites of conjugated polymers with fullerenes are perspective materials for polymer photovoltaics. Light-induced EPR (LEPR) study of magnetic, relaxation, and dynamic parameters of polaron-fullerene radical pairs photoinduced in fullerene-modified poly(3-alkylthiophenes) is described. Weak interaction between positively charged polaron and negatively charged fullerene ion radical in the pairs allowed to determine separately all their magnetic, relaxation, and dynamics parameters. Paramagnetic susceptibility of charge carriers reflects their activation dynamics and spin exchange in the composite. Decay of long-living polaron and fullerene anion radical depends on a spatial distance between them and the energy of exciting photons. One-dimensional polaron diffusion along the polymer chain and fullerene rotation near its own main molecular axis were shown to follow the activation Elliot hopping model and to be governed by photon energy. The deviation in activation energies for dynamics of charge carriers and the difference in their dependence on the exciting photon energy prove the noninteracting character of charge carriers photoinduced in the polymer/fullerene composite. The dependence of the main magnetic, relaxation, and dynamics parameters of charge carriers on the phonon energy was ascribed to inhomogeneous distribution of polymer and fullerene domains in bulk heterojunctions. This inhomogeneity decreases by the annealing of the composite.
Superhydrophobic behavior achieved from hydrophilic surfaces
Authors: Wang Jiadao , Liu Fengbin , Chen Haosheng , Chen Darong
Published: August 2009

The superhydrophobic behavior of a surface can be generally attributed to the combination of its chemical composition and microscale texture. The surface can be both hydrophobic and rough, and the roughness enhances its hydrophobicity. For a natural or artificial surface, superhydrophobic behavior is generally induced by a structured hydrophobic surface. This paper proposes an alternative; that is the superhydrophobic behavior can be obtained from a structured hydrophilic surface. The superhydrophobic behavior of a T-shape micropillar surface coated with diamond-like carbon has been achieved, which experimentally proved the proposed hypothesis that superhydrophobicity can be created from a hydrophilic surface through surface microstructure modification.
Temperature dependence of electronic energy transfer in PbS quantum dot films
Authors: Lü Wei , Kamiya Itaru , Ichida Masao , Ando Hiroaki
Published: August 2009

Colloidal PbS quantum dots dispersed as close-packed film and in polystyrene (PS) matrix are prepared and photoluminescence (PL) spectra are measured in the temperature range of 5–300 K. The integrated PL intensity of the close-packed film increases as the temperature is raised from 5 to 120 K, and then decreases to 300 K, while that of the PS film decreases monotonously. This abnormal behavior of the close-packed film can be explained by a thermally activated electronic energy transfer model, which is supported by time resolved PL measurements.
Softening of the tunneling gap in modulation-doped GaAs/AlGaAs asymmetric coupled double quantum wells in magnetic fields
Authors: Shin Y. H. , Park Y. H. , Perry C. H. , Simmons J. A. , Takamasu T. , Kim Yongmin
Published: August 2009

Magnetophotoluminescence emissions were measured from modulation doped GaAs/AlGaAs asymmetric double quantum wells, wherein a thin barrier (25 Å) was sandwiched between a single quantum well (SQW) and a single heterojuction (SHJ). In the SQW, Landau level mixing is observed at the quantum Hall states. At ν<2, the lowest Landau level transition undergoes an exciton transition. For the SHJ region, the free carrier transitions become excitonic at the crossing point of the GaAs free exciton and the tunneling band gap shows a marked softening. An exciton-exciton interaction is shown to be responsible for the behavior of the subband energy levels in magnetic fields.
Modulating the surface states of electric field assembled CuO nanowires by electrochemical deposition method
Authors: Wang Lixiang , Cheng Gang , Jiang Xiaohong , Wang Shujie , Zhang Xingtang , Du Zuliang
Published: August 2009

In this paper, the electrochemical deposition and anneal method has been developed to modulate the contact performance of electric field assembled CuO nanowires. After modulation, the current increases about two orders. The I-V curves indicate that before and after modulation, the current transport properties are both dominated by the reverse current of Schottky barriers under image force model. The current increase results from the formation of another current pathway, i.e., the CuO nanowire@nanoparticles/Pt electrode structure, in which the surface states in metal-semiconductor interface are largely reduced by passivating dangling bonds, and the barrier height decreases about 105 meV.
Cardiovascular Disease in Regional Queensland: A Case Study Identifying the Implications for Changing the Primary Health Care Educational Paradigm
Authors: Moxham Lorna , Arnold Trevor , Coutts Aaron , Michaels Alice , Ray Robin
Published: August 2009

Australia is perceived by many as the 'lucky' country and the image that has been portrayed to the rest of the world is one that projects a nation of tanned, active, healthy, and sports-loving individuals. This image is outdated and instead Australia is a nation with a national health problem. The health problem is having an impact which is increasingly problematic for governments. It has long been recognised that primary prevention, can be developed in two ways: by using a whole of population approach or through selective targeting (Naidoo & Wills, 1998). Within this context, this paper has chosen to explore and discuss a selective targeting approach through a case analysis of cardiovascular disease in regional Australia. In Australia, cardiovascular disease continues to be one of the major causes of death. This fact is a matter of great concern to all Australians but is particularly significant for people living in the regional city of Rockhampton, Central Queensland, where the death rate from cardiovascular disease is significantly higher than it is for the rest of the state of Queensland (354.4 deaths per 100,000 people per year compared with 310.6, Harper & Taylor, 1997, p. 21). The high death rate from heart disease in Queensland is even higher than the Australian average (Harper & Taylor, 1997, p. 22). Research previously conducted has revealed certain trends regarding cardiovascular disease. This research extends the available knowledge by measuring the cost in economic terms to the community. The findings explain the implications for Rockhampton employers and places regional health professionals in a better position to develop further research as well as to implement and explain alternative health strategies.
Continuing Uncertainties for Victorian Municipal Public Health Plans
Authors: McBride Tony , Hulme Alana
Published: August 2009

This paper discusses the current state of play in Victorian municipal public health planning and practice. It questions whether a legislative vehicle is still appropriate to realise local government's potential to affect its populations' health. The paper draws on four recent studies focused on the metropolitan experience. The impact of the radical local government restructuring in the mid-1990s and Compulsory Competitive Tendering were evident in the overlapping findings. These included: increased legitimacy for planning; an ambivalent policy environment; inconsistent support within councils; a paradox about external collaboration; limited community participation; and confusion about models for municipal health planning. However, there was a complex tapestry of positive and negative stories, perspectives, capacities and public health practices, reflecting the sectors' inherent geographical and political diversity. The continuing constraints on effective practice suggest that a reliance on State government legislation as the driving force for councils' approach to public health might no longer be the most productive approach. Public health advocates within and across councils need to help councils develop their own local rationales for action. To support this, the State government should act to create a more supportive and consistent policy environment.
The Attitudes of Health Professionals to the Psychological Preparation of Children for Hospitalisation
Authors: A. Whelan Thomas , J. Kirkby Robert
Published: August 2009

Research into the perceptions of health care staff about the psychological impact of medical procedures on children and their parents has been sparse. Those findings that have been published suggest that there are discrepancies between parent and health care provider perceptions of the hospital experience. It appears that health care staff, in particular medical practitioners, are inclined to overestimate satisfaction with the information they provide and underestimate the extent of emotional problems experienced by children and their parents. In addition, research has indicated that children report dissatisfaction with the information that they are given by either medical staff or their parents. Given the therapeutic and economic benefits of psychological preparation procedures, it seems surprising that research into the views of health staff about the importance of preparation programs has been ignored by investigators.
Piloting Case Conferencing Between GPs and Mental Health Services: Phase II of the Northern Queensland Rural Division of General Practice Mental Health Program
Authors: Alsop Maureen , F. Harris Mark , Powell-Davies Gawaine , Battye Kristine , Gerhardt Karin
Published: August 2009

Phase two of the Northern Queensland Rural Division of General Practice Mental Health program involved the piloting of case conferencing between General Practitioners (GPs) and mental health professionals in three rural communities. The initial findings suggest that this model supports GPs by increasing their confidence in the management of patients with whom they find it most challenging to work. Mental health professionals indicate that the opportunity to consult with GPs on a regular basis is important to their clinical work, and see the primary focus of these consultations as a means for communicating with GPs. The case conferencing also led to modest improvements in relationships between GPs and mental health service providers.
Chronic Illness and Ethnicity
Authors: O'Neill Cas , Silk Gerry , Lowe Gillian , Lee Renee , Cinar Sultan , Nguyen Hong , Ngo Binh
Published: August 2009

The expectations which both consumers and service providers bring to health care relationships are based on ethnicity and culture, as well as on individual and family characteristics, education and social circumstances. This article looks at the relationship between ethnicity and prevalence of illness; the interplay between ethnicity and social disadvantage; some cultural meanings attributed to illness; and how meanings may affect treatment. Four accounts are given of how two chronic illnesses - asthma and diabetes - may be viewed within the Timorese, Chinese, Turkish and Vietnamese communities.
SAFE Schools: Developing Community Health Partnerships
Authors: Morriss Mary , Mann Susan , Byrnes Tess
Published: August 2009

The SAFE (Safe Accident Free Environment) Schools Project is an innovative injury prevention project which focuses on health and safety issues relevant to the City of Onkaparinga catchment area. Specifically, this project was relevant for the education of school students as it linked with the nationally developed school curriculum, Health and Physical Education Statement and Profile (Curriculum Coorporation, 1994), in particular the components relating to 'Safety, Community Practices and Health of Populations' (Curriculum Coorporation, 1994). The project used a collaborative approach to involve students at primary school level in learning how to identify and respond to safety hazards that affect their everyday lives. Local primary schooI staff, a community health team from Noarlunga Health Services (NHS), community members and key people from local service agencies worked together to involve the students in a creative and practical way in learning about safety hazards. Students developed skills in identifying and reporting safety hazards in their school and local community with opportunities to develop and work with a process that provides positive action in regard to safety hazards.
Translating Principles into Practice: Lessons from Canada
Authors: Kushner Carol
Published: August 2009

The paper offers an overview of the status of primary care reform in Canada with some lessons outlining factors conducive to and against its implementation. Because health systems differ from one another, and depend on cultural and political contexts, these lessons may or may not apply to other jurisdictions.
Koori Primary Health Care in Victoria: Developments in Service Planning
Authors: Anderson Ian , Young Harriet , Markovic Milica , Manderson Lenore
Published: August 2009

The Alma Ata 1978 Declaration on primary health care has conventionally been applied in developing countries, where medically trained personnel and other highly skilled health professionals and medical infrastructure are limited. Although such concepts have salience in relatively resource rich countries such as Australia, it is in Aboriginal and Torres Strait Islander health policy that they have become pivotal. A growing national focus on the development of Aboriginal primary health care capacity followed the release of the National Aboriginal Health Strategy (NAHS) in 1989 (Anderson, 1997). This focus consolidated further, following the evaluation of the National Aboriginal Health Strategy implementation in 1994 which preceded the transfer of administrative responsibility for the Commonwealth Aboriginal health program from the Aboriginal and Torres Strait Islander Commission (ATSIC) to the Commonwealth Health portfolio (DHFS, 1994). Within the strategic framework provided by federal state agreements, the development of primary health care services is a priority. In the current national policy framework domains of policy and strategy development have been identified as key developmental themes.
Towards Integrated Service Delivery for Primary Health Care: Can Programs Meet People's Lives?
Authors: Lin Vivian
Published: August 2009

The primary health care sector faces a number of challenges. Some of these are in the form of persistent problems which include, inter alia, health disparities in resources and outcomes, a fragmented health system, issues of power with respect to priority setting and resource allocation, and a poor information and evidence base with which to allocate resources and evaluate outcomes. These problems are perennially accompanied by a gap between the rhetoric of policy and the reality of implementation. Neo-liberal reforms present a series of challenges to primary health, with the introduction of unit-cost funding, competitive tendering and increased user pays. Changing epidemiological patterns, the rise of evidence-based medicine, and new information and communication technology all question accepted methods of practice. Eroding community confidence in government and professionals, and the growing polarisation of society are also cause for concern. Three areas for development in primary health care policy and practice may provide the keys for dealing with these challenges. These are, first, the development of integrated service delivery models, which move away from narrowly defined single purpose programs delivered by one provider. Second, the development of innovative policy and managerial tools that support the objectives of primary health care while addressing the concerns of policy makers. Finally, the development of a strategic research and development agenda that effectively links policy, research and practice.
The Art and Science of Health Promotion
Authors: Moodie Rob
Published: August 2009

Science seldom proceeds in the straightforward logical manner imagined by outsiders. Instead, its steps forward (and sometimes backward) are often very human events in which personalities and cultural traditions play major roles.