bluuebunny/crossref_metadata_2025 huggingface dataset:
Size at birth is associated with blood pressure but not insulin resistance in 6–8 year old children in rural Nepal
Authors: Stewart C. P. , Christian P. , Schulze K. J. , Shah U. S. , Subedi G. , LeClerq S. C. , Khatry S. K.
Published: February 2010

Earlier, we reported that antenatal micronutrient supplementation reduced the risk of metabolic syndrome and microalbuminuria among offspring at 6–8 years of age in rural Nepal. In the same birth cohort, we examined associations of size at birth (weight, length and ponderal index), and gestational age, with cardiometabolic risk factors in childhood across all antenatal micronutrient interventions. There was an inverse association between birth weight and systolic blood pressure (SBP,β= −1.20 mm Hg/kg; 95% confidence interval (CI): −1.93, −0.46) and diastolic blood pressure (DBP,β= −1.24 mm Hg/kg; 95% CI: −2.00, −0.49). Current child body mass index was positively associated with SBP but not with DBP. Birth weight was unassociated with insulin resistance, but each kilogram of increase was associated with a reduced risk of high triglycerides (odds ratio (OR) = 0.64/kg; 95% CI: 0.41, 0.97) and an increased risk of high waist circumference (OR = 3.16/kg; 95% CI: 2.47, 4.41). In this rural Nepalese population of children 6–8 years of age with a high prevalence of undernutrition, size at birth was inversely associated with blood pressure and triglycerides and positively associated with waist circumference.
Bidecadal variability in the Bering Sea and the relation with 18.6 year period nodal tidal cycle
Authors: Osafune S. , Yasuda I.
Published: February 2010

Bidecadal variations are investigated in the Bering Sea, especially in the southeastern basin adjacent to the Aleutian passes, where vertical mixing may be strong because of the diurnal tide. Those variations found in this region are synchronized with the 18.6 year period nodal tidal cycle, and the temporal patterns are similar to ones around the northwestern subarctic Pacific near the Kuril Straits reported by a previous study. Salinity and density in the upper layer are high in the periods when the diurnal tide is strong. In the intermediate layer, layer thickness is large, and isopycnal potential temperature and apparent oxygen utilization are low in the same periods. It is shown that these variations are consistent with the patterns expected from the nodal modulation of vertical mixing, and a simple two‐dimensional model, assuming a balance between anomalous vertical mixing and advection of anomaly by the mean current, succeeds to some extent in explaining the variations of the upper layer salinity and isopycnal temperature and apparent oxygen utilization in the intermediate layer.
Human Urinary Kallidinogenase Suppresses Cerebral Inflammation in Experimental Stroke and Downregulates Nuclear Factor-κB
Authors: Chen Zhi-Bin , Huang Dan-Qing , Niu Feng-Nan , Zhang Xin , Li Er-Guang , Xu Yun
Published: February 2010

The purpose of this study is to investigate the possible mechanism and the neuroprotective effect of human urinary kallidinogenase (HUK) in cerebral ischemia. The mouse middle cerebral artery occlusion (MCAO) model was used. Mice were treated with HUK (20 PNAU/g per day, intravenous) or saline as control, from the beginning of reperfusion to 72 h. Neurological deficits, infarct size, and BWC were measured at 6, 24, 48, and 72 h after MCAO, respectively. Pathological changes of brain were observed by TUNEL assay. Inflammatory factors were measured by real-time PCR and western blotting. Activation of MAPKs, Akt, and nuclear factor-κB (NF-κB) was detected by western blotting. Our results indicated that HUK significantly improved neurofunction, decreased infarct size, and suppressed edema, as well as inflammatory mediators as compared with the vehicle group. Furthermore, HUK inhibited the NF-κB pathway and activated the MAPK/ERK pathway in this neuroprotection.
Robust Fitting of [11C]-WAY-100635 PET Data
Authors: Zanderigo Francesca , Ogden Robert Todd , Chang Chung , Choy Stephen , Wong Andrew , Parsey Ramin Vaziri
Published: February 2010

Fitting of a positron emission tomography (PET) time–activity curve is typically accomplished according to the least squares (LS) criterion, which is optimal for data having Gaussian distributed errors, but not robust in the presence of outliers. Conversely, quantile regression (QR) provides robust estimates not heavily influenced by outliers, sacrificing a little efficiency relative to LS when no outliers are present. Given these considerations, we hypothesized that QR would improve parameter estimate accuracy as measured by reduced intersubject variance in distribution volume ( V T) compared with LS in PET modeling. We compare V T values after applying QR with those using LS on 49 controls studied with [11C]-WAY-100635. QR decreases the standard deviation of the V T estimates (relative improvement range: 0.08% to 3.24%), while keeping the within-group average V T values almost unchanged. QR variance reduction results in fewer subjects required to maintain the same statistical power in group analysis without additional hardware and/or image registration to correct head motion.
Magnetic plasma confinement for laser ion source
Authors: Okamura M. , Adeyemi A. , Kanesue T. , Tamura J. , Kondo K. , Dabrowski R.
Published: February 2010

A laser ion source (LIS) can easily provide a high current beam. However, it has been difficult to obtain a longer beam pulse while keeping a high current. On occasion, longer beam pulses are required by certain applications. For example, more than 10 μs of beam pulse is required for injecting highly charged beams to a large sized synchrotron. To extend beam pulse width, a solenoid field was applied at the drift space of the LIS at Brookhaven National Laboratory. The solenoid field suppressed the diverging angle of the expanding plasma and the beam pulse was widened. Also, it was observed that the plasma state was conserved after passing through a few hundred gauss of the 480 mm length solenoid field.
Enhanced confinement in electron cyclotron resonance ion source plasma
Authors: Schachter L. , Stiebing K. E. , Dobrescu S.
Published: February 2010

Power loss by plasma-wall interactions may become a limitation for the performance of ECR and fusion plasma devices. Based on our research to optimize the performance of electron cyclotron resonance ion source (ECRIS) devices by the use of metal-dielectric (MD) structures, the development of the method presented here, allows to significantly improve the confinement of plasma electrons and hence to reduce losses. Dedicated measurements were performed at the Frankfurt 14 GHz ECRIS using argon and helium as working gas and high temperature resistive material for the MD structures. The analyzed charge state distributions and bremsstrahlung radiation spectra (corrected for background) also clearly verify the anticipated increase in the plasma-electron density and hence demonstrate the advantage by the MD-method.
Review on heavy ion radiotherapy facilities and related ion sources (invited)
Authors: Kitagawa A. , Fujita T. , Muramatsu M. , Biri S. , Drentje A. G.
Published: February 2010

Heavy ion radiotherapy awakens worldwide interest recently. The clinical results obtained by the Heavy Ion Medical Accelerator in Chiba at the National Institute of Radiological Sciences in Japan have clearly demonstrated the advantages of carbon ion radiotherapy. Presently, there are four facilities for heavy ion radiotherapy in operation, and several new facilities are under construction or being planned. The most common requests for ion sources are a long lifetime and good stability and reproducibility. Sufficient intensity has been achieved by electron cyclotron resonance ion sources at the present facilities.
Formation and conversion of defect centers in low water peak single mode optical fiber induced by gamma rays irradiation
Authors: Wen J. X. , Luo W. Y. , Xiao Z. Y. , Wang T. Y. , Chen Z. Y. , Zeng X. L.
Published: February 2010

The formation and conversion processes of defect centers in low water peak single mode optical (LWPSM) fiber irradiated with gamma rays were investigated at room temperature using electron spin resonance. Germanium electron center (GEC) and self-trapped hole center (STH) occur when the fibers are irradiated with 1 and 5 kGy cumulative doses, respectively. With the increase in irradiation doses, the GEC defect centers disappear, and new defect centers such as E′ centers (Si and Ge) and nonbridge oxygen hole centers (NBOHCs) generate. The generation of GEC and STH is attributed to the electron transfer, which is completely balanced. This is the main reason that radiation-induced attenuation (RIA) of the LWPSM fiber is only 10 dB/km at communication window. The new defect centers come from the conversion of GEC and STH to E′ centers and NBOHC, and the conversion processes cause bond cleavage, which is the root cause that the RIA of the LWPSM fiber significantly increases up to 180 dB/km at working window. Furthermore, the concentration of new defect centers is saturated easily even by increasing cumulative doses.
Thermal characterization of the SiO2-Ge2Sb2Te5 interface from room temperature up to 400°C
Authors: Battaglia J.-L. , Kusiak A. , Schick V. , Cappella A. , Wiemer C. , Longo M. , Varesi E.
Published: February 2010

The thermal conductivity of Ge2Sb2Te5 (GST) layers, as well as the thermal boundary resistance at the interface between the GST and amorphous SiO2, was measured using a photothermal radiometry experiment. The two phase changes in the Ge2Sb2Te5 were retrieved, starting from the amorphous and sweeping to the face centered cubic (fcc) crystalline state at 130°C and then to the hexagonal crystalline phase (hcp) at 310°C. The thermal conductivity resulted to be constant in the amorphous phase, whereas it evolved between the two crystalline states. The thermal boundary resistance at the GST-SiO2 interface was estimated to be higher for the hcp phase than for the amorphous and fcc ones.
Effect of particle size on the exchange bias of Fe-doped CuO nanoparticles
Authors: Yin S. Y. , Yuan S. L. , Tian Z. M. , Liu L. , Wang C. H. , Zheng X. F. , Duan H. N. , Huo S. X.
Published: February 2010

Effect of particle size on exchange bias in Fe-doped CuO nanoparticles is investigated, which are sintered at different temperatures from 350 to 650 °C, respectively. The structure and magnetic properties for different particle size samples were probed. It is found that the system shows magnetic properties transition from paramagnetic to ferromagnetic with increasing grain size, and exhibits the variations in exchange bias field (HEB) and coercivity (HC) at low temperature after field-cooled from 300 K. With the increase in the particles size, HEB decreases monotonously. Furthermore, vertical magnetization shift was also observed for the small particles. Exchange bias is attributed to the exchange coupling interactions between ferromagnetic and spin-glass-like (or antiferromagnetic) phase interface layers.
In situ spectroscopic ellipsometry study of the hydrogenation process of switchable mirrors based on magnesium-nickel alloy thin films
Authors: Yamada Y. , Bao S. , Tajima K. , Okada M. , Tazawa M. , Roos A. , Yoshimura K.
Published: February 2010

The hydrogenation process of switchable mirrors using magnesium-nickel alloy thin films including a thin palladium cap layer was analyzed by measuring the variation in ellipsometric angles Ψ and Δ using in situ spectroscopic ellipsometry. The process was divided into three phases and each phase was identified as follows. The first phase was the process in which the solid solution was formed because a Mg–Ni alloy in its metal state absorbs hydrogen. The second phase was the hydrogenation processes of the solid solution and the metal Pd layers. The third phase was the hydrogenation process of residual metal Pd in the Pd layer. In the initial state of the second phase, a hydride of the alloy was nucleated at the film/substrate interface as a result of hydrogenation of the solid solution, and a mixture layer of the hydride and solution was formed. With proceeding hydrogenation, the thickness of the mixture layer increased and the homogenous hydride layer was afterwards formed at the film/substrate interface. As a result of further hydrogenation, the Mg–Ni alloy layer was completely hydrogenated. After the alloy layer was completely hydrogenated, the hydrogenation of Pd was terminated.
Ag dendritic nanostructures for rapid detection of polychlorinated biphenyls based on surface-enhanced Raman scattering effect
Authors: Yang Yajun , Meng Guowen
Published: February 2010

We report a facile and efficient synthetic route for Ag dendritic nanostructures on Si wafer via an electroless deposition process. The formation of the Ag dendritic nanostructures is based on a self-assembled localized microscopic electrochemical cell model. These Ag dendritic nanostructures have exhibited very strong surface-enhanced Raman scattering (SERS) effect using rhodamine 6G as probe molecules, and have been used as SERS substrate for detection of low concentration polychlorinated biphenyl-77 with fast time response. The Ag dendritic nanostructures reported here have potentials as SERS substrates for fast detecting other polychlorobiphenyls.
Quantum dynamics of the H+CH4→H2+CH3 reaction in curvilinear coordinates: Full-dimensional and reduced dimensional calculations of reaction rates
Authors: Schiffel Gerd , Manthe Uwe
Published: February 2010

Full-dimensional quantum dynamics calculations for the H+CH4→H2+CH3 reaction using curvilinear coordinates are presented. A curvilinear coordinate system to describe reactions of the type X+YCH3→XY+CH3 is developed which facilitates efficient calculations using the multiconfigurational time-dependent Hartree (MCTDH) approach. To describe the bending motion of the X and Y atoms relative to the axis defined by the CH3 fragment, coordinates based on stereographic projection are introduced. These coordinates yield a kinetic energy operator free of singularities within the dynamically relevant region. Employing this curvilinear coordinate system, full-dimensional and reduced dimensional MCTDH calculations study the cumulative reaction probability (for J=0) and the thermal rate constant for the H+CH4 reaction on the Jordan-Gilbert potential energy surface [J. Chem. Phys. 102, 5669 (1995)]. The full-dimensional results agree very well with previous full-dimensional MCTDH results which used transition state based normal coordinates. The results of our eight-dimensional (8D) calculations are in reasonable agreement with the full-dimensional ones. They deviate significantly from older 8D results of Zhang et al. [J. Chem. Phys. 127, 234213 (2007)] but agree well with more recent results from the same group.
Strain effects on InxAl1−xN crystalline quality grown on GaN templates by metalorganic chemical vapor deposition
Authors: Miao Z. L. , Yu T. J. , Xu F. J. , Song J. , Lu L. , Huang C. C. , Yang Z. J. , Wang X. Q. , Zhang G. Y. , Zhang X. P. , Yu D. P. , Shen B.
Published: February 2010

In x Al 1 − x N epilayers (∼200 nm thick) under different strain states were grown on GaN templates by metalorganic chemical vapor deposition. When the strain is small (0.166≤x≤0.208), InxAl1−xN epilayers are almost fully coherent with the GaN templates, and the surface presents similar characteristic of small hillocks and uniform pits. In the case of large tensile strain, cracks emerged on the surface, but the surface morphology is less influenced compared to the samples with small strain. However, with large compressive strain, the surface roughness dramatically increased and additional smaller pits emerged with partial strain relaxation occurring during growth. In addition, the microstructures were further investigated by transmission electron microscopy. It is demonstrated that even slight relaxation of compressive strain can lead to notable influence on the structural quality and surface morphology of InxAl1−xN films.
Adhesion and the cold welding of gold-silver thin films
Authors: Akande Wali O. , Cao Yifang , Yao Nan , Soboyejo Wole
Published: February 2010

This paper presents the results of a combined experimental and theoretical study of adhesion in cold-welded Au–Ag interfaces that are relevant to the fabrication of organic electronic structures. Focused ion beam /transmission electron microscopy and electron energy loss spectroscopy techniques are used to reveal interfacial impurities associated with the cold welding of nanoscale Au and Ag thin films. A theoretical model is also developed and used to predict the contact profiles around impurities between cold-welded thin films. The model is shown to provide new insights into how adhesion affects the surface contacts that occur during cold welding. The implications of the results are then discussed for the design of cold-welding processes.
Influence of gap states on electrical properties at interface between bathocuproine and various types of metals
Authors: Sakurai Takeaki , Toyoshima Susumu , Kitazume Hikaru , Masuda Shigeru , Kato Hiroo , Akimoto Katsuhiro
Published: February 2010

A systematic study on the energy level alignment, chemical interaction, and electron doping at interfaces between bathocuproine (BCP) and various types of metals (Au, Cu, Ag, Mg, and Ca) was carried out by performing ultraviolet photoelectron spectroscopy and electronic conductivity measurements. The energy level alignment at BCP/metal interfaces was found to depend on the metal work function (Φm). For BCP on Au and Cu, whose Φm exceeds 4.3 eV, the energy shift in the highest occupied molecular orbital (HOMO) level with respect to the metal Fermi level (EF) almost accords with the variation in Φm. For BCP on Ag, Mg, and Ca, whose Φm is below 4.3 eV, the HOMO energy level is fixed at 3.7 eV with respect to EF regardless of Φm and new electronic states, called gap states, appeared at BCP/metal interfaces. Since the appearance of gap states is correlated with the energy of the lowest unoccupied molecular orbital (LUMO) level with respect to EF, these states appear to have formed mainly through the interaction with the LUMO. A clear correlation between the density of the gap states and the vacuum level shift suggesting a charge redistribution at BCP/metal interfaces was found. The energy shift in the gap states, which may originate from the variation in the electron occupation of the states, directly affected the electronic conductivity of metal-doped BCP layers (doping metal=Au, Ag, and Ca). These results suggest the electron transfer from the metal EF to gap states plays an influential role in the electrical properties at BCP/metal interfaces.
Two-pulse driving of D+D nuclear fusion within a single Coulomb exploding nanodroplet
Authors: Last Isidore , Peano Fabio , Jortner Joshua , Silva Luis O.
Published: February 2010

This paper presents a computational study of D+D fusion driven by Coulomb explosion (CE) within a single, homonuclear deuterium nanodroplet, subjected to double-pulse ultraintense laser irradiation. This irradiation scheme results in the attainment (by the first weaker pulse) of a transient inhomogeneous density profile, which serves as a target for the driving (by the second superintense pulse) of nonuniform CE that triggers overrun effects and induces intrananodroplet (INTRA) D+D fusion. Scaled electron and ion dynamics simulations were utilized to explore the INTRA D+D fusion yields for double-pulse, near-infrared laser irradiation of deuterium nanodroplets. The dependence of the INTRA yield on the nanodroplet size and on the parameters of the two laser pulses was determined, establishing the conditions for the prevalence of efficient INTRA fusion. The INTRA fusion yields are amenable to experimental observation within an assembly of nanodroplets. The INTRA D+D fusion can be distinguished from the concurrent internanodroplet D+D fusion reaction occurring in the macroscopic plasma filament and outside it in terms of the different energies of the neutrons produced in these two channels.
Effect of imperfections on the tunneling enhancement phenomenon in symmetric double quantum dots
Authors: Totaro M. , Marconcini P. , Logoteta D. , Macucci M. , Whitney R. S.
Published: February 2010

The conductance of a pair of quantum dots, coupled through a tunnel barrier and connected to two external leads, exceeds the conductance of the tunnel barrier alone (tunneling enhancement effect) if the device is symmetrical, while it strongly decreases if the symmetry is destroyed. This device could then be used to implement a sensitive detector of symmetry breaking quantities, such as magnetic fields. We present a numerical study of the robustness of this phenomenon to the presence of imperfections. We find that, while a realistic amount of edge roughness in the depletion gates defining the structure does not compromise the enhancement effect significantly, and also lithographic errors can be compensated by properly tuning the voltages applied to the gates, the presence of randomly located ionized dopants in the heterostructure can strongly degrade the conductance enhancement and thus particular care has to be taken in terms of cleanliness and mobility of the heterostructure.
Increasing the coupling efficiency of a microdisk laser to waveguides by using well designed spiral structures
Authors: Liu Danyu , Hattori Haroldo T. , Fu Lan , Tan Hark Hoe. , Jagadish Chennupati
Published: February 2010

In this article, we optimize the coupling efficiency from a GaAs microdisk resonator into a single mode spiral waveguide. A classical microdisk resonator coupling light into a nonevanescent straight waveguide reaches a typical coupling efficiency of 67%. We show that the introduction of a spiral waveguide that works both as a waveguide and circular Bragg reflector can improve such efficiency to almost 90%. The same structure with the addition of a taper can couple up to 80% of the generated power into a slot waveguide.
Theoretical study of the structural stability, electronic, and magnetic properties of MBi (M=V, Cr, and Mn) compounds
Authors: Kahal L. , Ferhat M.
Published: February 2010

We present theoretical studies of the structural stability, electronic, and magnetic properties of MBi (M=V, Cr, Mn) compounds using the full-potential linear augmented plane wave method. To find the most stable structure for each compound, total energy calculations of several phases are considered, and magnetic and antiferromagnetic states for each compound are taken into consideration. Our calculation indicates that the antiferromagnetic NiAs structure is the stable state for VBi and CrBi, whereas MnBi is stable in the ferromagnetic hexagonal NiAs structure. Our results for the magnetic stability, the stable structure, and the structural parameters are in perfect agreement with theoretical calculation and experimental values. The calculated total magnetic moment for MnBi of 3.55 μB agrees with the measured moment of 3.60 μB. For the zinc-blende phase, our calculations predict that VBi, CrBi, and MnBi are half-metallic ferromagnet with a magnetic moment 2, 3, and 4 μB, respectively. The magnetism comes essentially from the d orbitals of V, Cr, and Mn atoms, while the half metallic character is the fingerprint of the p(Bi)-d(M) interaction. The exchange interaction increases, while the crystal field splitting decreases from V to Mn with the increases of the filling of the d bands of the transition metals M atoms, as a consequence: (i) For the spin-up channel, the antibonding state Γ12 is pushed close to Ef for VBi, while in CrBi and MnBi, this state is below the Fermi level for CrBi and MnBi, respectively. (ii) The t2g(Γ15) bands of both majority and minority spins are filled while the eg(Γ12) bands of minority spin are empty. (iii) The exchange splitting Δeg is roughly equal to A M, where M is the magnetic moment. We found A ∼0.93 μB/eV, 0.99 μB/eV, and 1 μB/eV for VBi, CrBi, and MnBi, respectively, this is close to the value of the exchange integral I of transition metals which have a value about 0.9 μB/eV. We also studied the effect of spin-orbit coupling on the half-metallicity of these compounds. We found a relative small reduction in polarization, ranging from above P=97,27% for CrBi, P=85.49% for CrBi to P=81.88%, for MnBi.
The maximum possible magnetocaloric ΔT effect
Authors: Zverev V. I. , Tishin A. M. , Kuz’min M. D.
Published: February 2010

The current boom of research activity in magnetocaloric materials science is fuelled by the expectation that new advanced refrigerants may be found whose ΔT will significantly surpass that of gadolinium (Gd) metal (2.6–2.9 K/T). Because of this expectation, the main effort in the field has been diverted from the important issues of refrigerator design to the routine characterization of magnetic materials. Estimating the maximum adiabatic temperature change that can be achieved in principle by applying a certain magnetic field, say 1 T, is a matter of priority. In this work the problem of maximum ΔT is approached from general principles. According to the most optimistic estimates, ΔT can never exceed ∼18 K/T, the more realistic upper limit lying somewhere in high single figures. We therefore deem it most unlikely that a refrigerant much better than Gd, in respect of the ΔT value, will ever be found.
Nonmonotonic plasma density profile due to neutral-gas depletion
Authors: Fruchtman A.
Published: February 2010

The dependencies in a gas discharge of the plasma density and of the neutral-gas depletion on the magnetic-field intensity and on the plasma particle flux are studied. It is shown that if plasma particle flux density outward of the discharge is fixed, varying the magnetic field intensity does not affect neutral-gas depletion. When there are plasma end losses along magnetic-field lines while neutral-gas is depleted, an increase in the magnetic field intensity results in a nonmonotonic plasma density profile across field lines. The plasma density then has a local minimum at the center of the discharge.
Invited Article: Local shear stress transduction
Authors: Kolitawong Chanyut , Giacomin A. Jeffrey , Johnson Leann M.
Published: February 2010

This is a comprehensive review of local direct measurement shear stress transducers. Transducers are first classified by their movement, measuring mode, and mechanism. These categories are then subclassified into active or passive movement, static or dynamic measuring mode, and rotational or translational mechanisms. Over 80 transducers are reviewed and tabulated. Finally, sources of transducer error are analyzed. Primary sources of error are transducer and housing misalignment, material ingress around the active face, active face roughness, and the effects of temperature gradients when making measurements on surfaces where temperature gradients develop.
Magnonic crystal based forced dominant wavenumber selection in a spin-wave active ring
Authors: Karenowska A. D. , Chumak A. V. , Serga A. A. , Gregg J. F. , Hillebrands B.
Published: February 2010

Spontaneous excitation of the dominant mode in a spin-wave active ring—a self-exciting positive-feedback system incorporating a spin-wave transmission structure—occurs at a certain threshold value of external gain. In general, the wavenumber of the dominant mode is extremely sensitive to the properties and environment of the spin-wave transmission medium, and is almost impossible to predict. In this letter, we report on a backward volume magnetostatic spin-wave active ring system incorporating a magnonic crystal. When mode enhancement conditions—readily predicted by a theoretical model—are satisfied, the ring geometry permits highly robust and consistent forced dominant wavenumber selection.
Plasmon band gap generated by intense ion acoustic waves
Authors: Son S. , Ku S.
Published: February 2010

In the presence of an intense ion acoustic wave, the energy-momentum dispersion relation of plasmons is strongly modified to exhibit a band gap structure. The intensity of an ion acoustic wave might be measured from the band gap width. The plasmon band gap can be used to block the nonlinear cascading channel of the Langmuir wave decay.
Nonuniformity of electron density in In-rich InGaN films deduced from electrolyte capacitance-voltage profiling
Authors: Knübel A. , Polyakov V. M. , Kirste L. , Aidam R.
Published: February 2010

In x Ga 1 − x N films with 0.4≤x≤1 are analyzed using electrolyte-based capacitance-voltage technique. In-rich InxGa1−xN for x>0.4 samples exhibit a strong surface electron accumulation. At x=0.4, the Fermi level at the surface is pinned to the conduction band edge indicating a crossover from surface accumulation to depletion. The measured Mott–Schottky plots are fitted using a model based on a Schrödinger–Poisson solver. By comparing the measured data to the fitting results, we conclude that a subsurface layer of ∼15 nm thickness with remarkably lower donor defect concentration is formed during the growth of InGaN films.
Temperature dependence of thermal conductivity enhancement in single-walled carbon nanotube/polystyrene composites
Authors: Jakubinek Michael B. , White Mary Anne , Mu Minfang , Winey Karen I.
Published: February 2010

The thermal conductivity of single-walled carbon nanotube (SWCNT)/polystyrene composites, prepared by a method known to produce a uniform distribution of SWCNT bundles on the micrometer length scale, was measured in the temperature range from approximately 140 to 360 K. The thermal conductivity enhancement (50% for 1 mass % at 300 K) is reasonably constant above room temperature but is reduced at the lower temperatures. This result is consistent with the expected, large contribution of interfacial thermal resistance in SWCNT/polymer composites. Enhancements in electrical conductivity show that 1 mass % loading is in the region of the electrical percolation threshold.
Effect of normal and parallel magnetic fields on the stability of interfacial flows of magnetic fluids in channels
Authors: Yecko Philip
Published: February 2010

The effect of an imposed magnetic field on the linear stability of immiscible two-fluid Poiseuille flow in a channel is examined for low Reynolds numbers. Surface tension acts on the interface, the fluids have different densities and viscosities, and one fluid is magnetic (ferrofluid). A Langevin function is used to model the fluid magnetization, resulting in a nonlinear permeability; the stability properties depend on this permeability relation both directly and indirectly, through the base state solution. Uniform magnetic fields applied normal or parallel to the interface both lead to an interfacial instability. Normal fields excite longer wavelength modes, generally having higher growth rates, but parallel fields can excite faster growing modes in high permeability fluids at large applied field strength. Whether or not the field stabilizes or destabilizes the flow depends on the viscosity and layer thickness ratios in a simple way, while the placement of the magnetic fluid layer does not play a major role. Growth rates predicted for realistic microchannel conditions are shown to be large enough to make ferrofluid manipulation a practical method of control.
Alternating photoinduced mass transport triggered by light polarization in azobenzene containing sol-gel films
Authors: Fabbri F. , Lassailly Y. , Lahlil K. , Boilot J. P. , Peretti J.
Published: February 2010

Combined shear-force and near-field optical microscopies are used for real-time monitoring of the formation of photoinduced surface relief gratings in photochromic thin films containing azobenzene derivatives. The correlated optical and topographical images provide evidence that the direction of the photoinduced matter migration is defined by the light polarization pattern and that, for a given light intensity pattern, modulating the polarization between two orthogonal states gives rise to alternating mass transport.
Photoinduced inverse spin-Hall effect: Conversion of light-polarization information into electric voltage
Authors: Ando K. , Morikawa M. , Trypiniotis T. , Fujikawa Y. , Barnes C. H. W. , Saitoh E.
Published: February 2010

The photoinduced inverse spin-Hall effect was observed in a Pt/GaAs hybrid structure. In the GaAs layer, circularly polarized light generates spin-polarized carriers, inducing a pure spin current into the Pt layer through the interface. This pure spin current is, by the inverse spin-Hall effect in the Pt layer, converted into electric voltage. By changing the direction and ellipticity of the circularly polarized light, the electromotive force varies systematically, consistent with the prediction of the photoinduced inverse spin-Hall effect. The observed phenomenon allows the direct conversion of circular-polarization information into electric voltage; this phenomenon can be used as a spin photodetector.
Quantum dot solar cell: Materials that produce two intermediate bands
Authors: Jenks Steven , Gilmore Robert
Published: February 2010

Placing intermediate bands within the energy gap of a semiconductor has been proposed as a way to increase solar cell efficiency. In this work, possible energy band configurations are determined, which achieve a theoretical efficiency greater than 70%. One way to create these bands is by utilizing quantum dot technology. Quantum dot materials and parameters are identified, which closely match the intermediate band energies that provide the maximum theoretical efficiency. The sensitivity of the efficiency as a function of the intermediate band energy levels is investigated. In addition, the minimum distances between the quantum dot materials required to prevent band overlap are determined.
Controllability of threshold voltage in Ag-doped ZnO nanowire field effect transistors by adjusting the diameter of active channel nanowire
Authors: Kim Kyoungwon , Debnath Pulak Chandra , Park Dong-Hoon , Kim Sangsig , Lee Sang Yeol
Published: February 2010

Silver doped zinc oxide nanowires (NWs) were synthesized on (0001) sapphire substrate by hot-walled pulsed laser deposition. Both enhancement mode and depletion mode NW field effect transistors (FETs) were fabricated. The shift of threshold voltage of silver doped zinc oxide NW FET was observed from 2.45 to −3.2 V depending on the diameter of NWs without any significant changes of the subthreshold swing, carrier concentration, and on/off ratios. We demonstrate that the transfer characteristics of silver doped zinc oxide NW FETs were closely related with the size of NW diameter and control the shift of threshold voltage.
Long lifetime of free excitons in ZnO tetrapod structures
Authors: Lee S.-K. , Chen S. L. , Hongxing D. , Sun L. , Chen Z. , Chen W. M. , Buyanova I. A.
Published: February 2010

Time-resolved photoluminescence (PL) is employed to characterize optical quality of ZnO tetrapods. PL decay of free excitons (FE) is concluded to contain two components with time constants of 1 and 14 ns at room temperature. The fast PL decay is attributed to nonradiative recombination whereas the slow decay is suggested to mainly represent FE radiative lifetime, based on correlation between thermally induced increases in the PL linewidth and FE lifetimes. The results underline superior optical quality of the tetrapods as the decay time of the slow PL component is comparable to the longest lifetimes reported to date for ZnO.
Weak-antilocalization signatures in the magnetotransport properties of individual electrodeposited Bi Nanowires
Authors: Marcano N. , Sangiao S. , Plaza M. , Pérez L. , Pacheco A. Fernández , Córdoba R. , Sánchez M. C. , Morellón L. , Ibarra M. R. , De Teresa J. M.
Published: February 2010

We study the electrical resistivity of individual Bi nanowires of diameter 100 nm fabricated by electrodeposition using a four-probe method in the temperature range 5–300 K with magnetic fields up to 90 kOe. Low-resistance Ohmic contacts to individual Bi nanowires are achieved using a focused ion beam to deposit W-based nanocontacts. Magnetoresistance measurements show evidence for weak antilocalization at temperatures below 10 K, with a phase-breaking length of 100 nm.
Remarkable increase in the efficiency of N,N′-dimethylquinacridone dye heavily doped organic light emitting diodes under high current density
Authors: Liu Huihui , Yan Fei , Li Wenlian , Chu Bei , Su Wenming , Su Zisheng , Wang Junbo , Hu Zhizhi , Zhang Zhiqiang
Published: February 2010

We demonstrated a remarkable rise of external quantum efficiency (EQE) of N,N′-dimethylquinacridone (DMQA) heavily doped organic light-emitting diodes with tris-(8-hydroxyquinolinato) aluminum as host at large current density. The EQE of 5.0 wt % DMQA doped device increased 42% as the current density rises from 20 to 300 mA/cm2. At 300 mA/cm2, the EQE of 1.8 wt % DMQA doped device equals to that of the optimal concentration (0.8 wt %) doped device, which behaves a flat trend curve with the increase of current density. Whereas, another green fluorescent dye (Coumarin6) doped device with the same structure indicates straight falling dependence of EQE on increasing current density. The EQE increase is attributed to the dissociation of excimer species formed by interaction of higher concentration DMQA molecules into DMQA monomer excitons under high current density.
Electrical characterization of single-walled carbon nanotubes in organic solar cells by Kelvin probe force microscopy
Authors: Liu Liming , Li Guangyong
Published: February 2010

The electrical role (donor or acceptor) of single-walled carbon nanotubes (SWCNTs) in organic solar cells remains controversial in the literature. Using Kelvin probe force microscopy (KPFM) to investigate SWCNTs on regioregular poly 3-hexylthiophene (P3HT) film as well as on P3HT and methanofullerene blended film, we have observed that photoinduced holes transport from active layer to SWCNTs, which indicates that SWCNTs work as donor materials. Moreover, KPFM study of SWCNTs on P3HT film reveals that the relatively low power conversion efficiency of P3HT/SWCNTs solar cells is attributed to deficient photoexcited carrier transport between P3HT and SWCNTs because of inefficient exciton dissociation.
Localized Hartree product treatment of multiple protons in the nuclear-electronic orbital framework
Authors: Auer Benjamin , Hammes-Schiffer Sharon
Published: February 2010

An approximation for treating multiple quantum nuclei within the nuclear-electronic orbital (NEO) framework for molecular systems is presented. In the approximation to NEO-Hartree–Fock, the nuclear wave function is represented by a Hartree product rather than a Slater determinant, corresponding to the neglect of the nuclear exchange interactions. In the approximation to NEO-density functional theory, the nuclear exchange-correlation functional is chosen to be the diagonal nuclear exchange interaction terms, thereby eliminating the nuclear self-interaction terms. To further enhance the simplicity and computational efficiency, the nuclear molecular orbitals or Kohn–Sham orbitals are expanded in terms of localized nuclear basis sets. These approximations are valid because of the inherent localization of the nuclear orbitals and the numerical insignificance of the nuclear exchange interactions in molecular systems. Moreover, these approximations lead to substantial computational savings due to the reduction in both the number of integrals that must be calculated and the size of the matrices that must be diagonalized. These nuclear Hartree product approximation (HPA) methods scale linearly with the number of quantum protons and are highly parallelizable. Applications to a water hexamer, glycine dimer, and 32-water cluster, where all hydrogen nuclei are treated quantum mechanically, illustrate the accuracy and computational efficiency of the nuclear HPA methods. These strategies will facilitate the implementation of explicitly correlated NEO methods for molecular systems with multiple quantum protons.
Compatibility between shape equation and boundary conditions of lipid membranes with free edges
Authors: Tu Z. C.
Published: February 2010

Only some special open surfaces satisfying the shape equation of lipid membranes can be compatible with the boundary conditions. As a result of this compatibility, the first integral of the shape equation should vanish for axisymmetric lipid membranes, from which two theorems of nonexistence are verified: (i) there is no axisymmetric open membrane being a part of torus satisfying the shape equation; (ii) there is no axisymmetric open membrane being a part of a biconcave discodal surface satisfying the shape equation. Additionally, the shape equation is reduced to a second-order differential equation while the boundary conditions are reduced to two equations due to this compatibility. Numerical solutions to the reduced shape equation and boundary conditions agree well with the experimental data [A. Saitoh et al., Proc. Natl. Acad. Sci. U.S.A. 95, 1026 (1998)].
Colour patterns in the sea urchin, Heliocidaris erythrogramma, suggest limited connectivity across the Southern and Pacific Ocean coastlines of Australia
Authors: Beck Hayden J. , Styan Craig A.
Published: February 2010

Heliocidaris erythrogramma is a widespread Australian sea urchin whose colour varies greatly. Here we report large-scale, hierarchically structured surveys, testing for patterns in colouration of H. erythrogramma associated with wave exposure, and consistency between populations from the Pacific and Southern Oceans. Along the Southern Ocean coastline, more urchins with white dermis were found in (ocean swell-exposed) open coast regions, whereas more urchins with red dermis were usually found in the (ocean swell-protected) bay regions. In contrast, only red dermis urchins were found in both open coast and bay regions along the Pacific coastline. Spine colour was found to be independent of test colour within locations and, while no differences in the frequencies of spine colours were detected between regions of different wave exposure, differences were detected across 1–100s of km within coastlines. Large differences in the frequencies of spine colours were also detected between the two coastlines. Clear differences in two independent characteristics of colour between Southern Ocean and Pacific coastlines, combined with intermediate patterns at a location near the junction of these coastlines, suggest that large-scale morphological patterns might reflect intra-specific genetic differentiation within H. erythrogramma, large-scale environmental differences between temperate Australian coastlines, or an interaction between these two factors.
Demography of a large exploited grouper, Plectropomus laevis: Implications for fisheries management
Authors: Heupel Michelle R. , Williams Ashley J. , Welch David J. , Davies Campbell R. , Adams Samantha , Carlos Gary , Mapstone Bruce D.
Published: February 2010

Species in the coral trout complex Plectropomus spp. are some of the most desired and exploited in the Indo-Pacific, although data are limited for most species. Demographic parameters of blue-spot coral trout, Plectropomus laevis, were estimated on the basis of specimens collected from five regions of the Great Barrier Reef and Torres Strait, Australia, between 1995 and 2005 to define demography and population status over a broad range. In total, 1249 individuals were collected to estimate growth, mortality and reproductive parameters. Growth parameters based on the von Bertalanffy model were K = 0.096 year–1, L∞ = 1159 mm fork length (FL) and the best-fit model suggested non-asymptotic growth over the size and age ranges represented in the sample. Maximum age was 16 years, total mortality was estimated at 0.39 (±0.031), and estimated size and age at first maturity were 299 mm FL (range: 299–872) and at 1 year (range: 1–6.5), respectively, with the size range over which sex change occurred at 460–872 mm FL. Population parameters and available relative abundance estimates indicated that long-term sustainable harvest rates of P. laevis will be lower than those for P. leopardus and species-specific size-based management measures are necessary to ensure the species is not overfished.
Edge patterns in aquatic invertebrates explained by predictive models
Authors: Macreadie Peter I. , Connolly Rod M. , Jenkins Gregory P. , Hindell Jeremy S. , Keough Michael J.
Published: February 2010

Predictive frameworks for understanding and describing how animals respond to habitat fragmentation, particularly across edges, have been largely restricted to terrestrial systems. Abundances of zooplankton and meiofauna were measured across seagrass–sand edges and the patterns compared with predictive models of edge effects. Artificial seagrass patches were placed on bare sand, and zooplankton and meiofauna were sampled with tube traps at five positions (from patch edges: 12, 60 and 130 cm into seagrass; and 12 and 60 cm onto sand). Position effects consisted of the following three general patterns: (1) increases in abundance around the seagrass–sand edge (total abundance and cumaceans); (2) declining abundance from seagrass onto sand (calanoid copepods, harpacticoid copepods and amphipods); and (3) increasing abundance from seagrass onto sand (crustacean nauplii and bivalve larvae). The first two patterns are consistent with resource-distribution models, either as higher resources at the confluence of adjacent habitats or supplementation of resources from high-quality to low-quality habitat. The third pattern is consistent with reductions in zooplankton abundance as a consequence of predation or attenuation of currents by seagrass. The results show that predictive models of edge effects can apply to aquatic animals and that edges are important in structuring zooplankton and meiofauna assemblages in seagrass.
Interactome analysis of longitudinal pharyngeal infection of cynomolgus macaques by group A
Streptococcus
Authors: Shea Patrick R. , Virtaneva Kimmo , Kupko John J. , Porcella Stephen F. , Barry William T. , Wright Fred A. , Kobayashi Scott D. , Carmody Aaron , Ireland Robin M. , Sturdevant Daniel E. , Ricklefs Stacy M. , Babar Imran , Johnson Claire A. , Graham Morag R. , Gardner Donald J. , Bailey John R. , Parnell Michael J. , DeLeo Frank R. , Musser James M.
Published: February 2010

Relatively little is understood about the dynamics of global host–pathogen transcriptome changes that occur during bacterial infection of mucosal surfaces. To test the hypothesis that group A
Streptococcus
(GAS) infection of the oropharynx provokes a distinct host transcriptome response, we performed genome-wide transcriptome analysis using a nonhuman primate model of experimental pharyngitis. We also identified host and pathogen biological processes and individual host and pathogen gene pairs with correlated patterns of expression, suggesting interaction. For this study, 509 host genes and seven biological pathways were differentially expressed throughout the entire 32-day infection cycle. GAS infection produced an initial widespread significant decrease in expression of many host genes, including those involved in cytokine production, vesicle formation, metabolism, and signal transduction. This repression lasted until day 4, at which time a large increase in expression of host genes was observed, including those involved in protein translation, antigen presentation, and GTP-mediated signaling. The interactome analysis identified 73 host and pathogen gene pairs with correlated expression levels. We discovered significant correlations between transcripts of GAS genes involved in hyaluronic capsule production and host endocytic vesicle formation, GAS GTPases and host fibrinolytic genes, and GAS response to interaction with neutrophils. We also identified a strong signal, suggesting interaction between host γδ T cells and genes in the GAS mevalonic acid synthesis pathway responsible for production of isopentenyl-pyrophosphate, a short-chain phospholipid that stimulates these T cells. Taken together, our results are unique in providing a comprehensive understanding of the host–pathogen interactome during mucosal infection by a bacterial pathogen.