bluuebunny/crossref_metadata_2025 huggingface dataset:
Atmospheric particulate transport modelling in a controlled burn event
Authors: Leslie Lance M , Speer Milton S
Published: August 2010

Smoke pollution from controlled burning of forested areas can be a major problem for populated areas, even those at some distance from the site of the burning. In particular, Perth, the largest city in Western Australia, is affected by smoke from controlled forest burns to the south of the city when meteorological conditions advect smoke over the city. Such controlled burns are extensively carried out on an annual basis in spring, early summer and late autumn by the Western Australian Department of Conservation and Land Management (CALM) in the southwest forests, in order to reduce flammable fuels and mitigate the undesirable social, economic, environmental and human problems caused by destructive wildfires. In this article, results are presented from a mesoscale model prediction of smoke trajectories from a controlled burn event that took place in November, 1995. In this example, two meteorological factors, a strong sea‐breeze front and a mesoscale low pressure system, unexpectedly turned the smoke back from its initial trajectory over the ocean to directly over Perth itself. The result was very high smoke concentration levels over the city and associated health concerns to residents as well as disruption to transport including the closing of Perth airport. The mesoscale guidance was very accurate and can provide valuable guidance when run routinely. Copyright © 1998 Royal Meteorological Society
Is participation in food and income assistance programmes associated with obesity in California adults? Results from a state-wide survey
Authors: Leung Cindy W , Villamor Eduardo
Published: August 2010

Objective

Public assistance programmes may increase risk of obesity among adults. The current study assessed whether participation in the Supplemental Nutrition Assistance Program (SNAP; formerly the Food Stamp Program), Supplemental Security Income (SSI) or California Work Opportunities and Responsibilities to Kids (CalWorks) was associated with obesity, independent of socio-economic status and food insecurity.

Design

A cross-sectional analysis of the 2007 Adult California Health Interview Survey. Outcome measures included BMI and obesity. Distribution of BMI and prevalence of obesity were compared by participation in each programme, using weighted linear and binomial regression models in which BMI or obesity was the outcome, respectively, and programme participation was the predictor.

Setting

A population survey of various health measures.

Subjects

Non-institutionalized adults (n 7741) whose household income was ≤130 % of the federal poverty level.

Results

The prevalence of obesity was 27·4 %. After adjusting for sociodemographic characteristics, food insecurity and participation in other programmes, the prevalence of obesity was 30 % higher in SNAP participants (95 % CI 6 %, 59 %; P = 0·01) than in non-participants. This association was more pronounced among men than women. SSI participation was related to an adjusted 50 % higher prevalence of obesity (95 % CI 27 %, 77 %; P < 0·0001) compared with no participation. SNAP and SSI participants also reported higher soda consumption than non-participants of any programme. CalWorks participation was not associated with obesity after multivariable adjustment.

Conclusions

Participation in SNAP or SSI was associated with obesity independent of food insecurity or socio-economic status. The suggestion that these associations may be mediated by dietary quality warrants further investigation among low-income populations.
Young urban women and the nutrition transition in Jordan
Authors: Madanat Hala N , Lindsay Ryan , Campbell Tiffany
Published: August 2010

Objective

To determine the nutrition transition stage of female Jordanian college students.

Design

A cross-sectional survey was used to assess eating styles, disordered eating attitudes and behaviours, body esteem and dissatisfaction, and media influence.

Setting

Public and private universities in Jordan.

Subjects

A total of 255 subjects were recruited through a government-initiated youth campaign.

Results

The majority of participants had a normal BMI (70·6 %) with almost all (99·4 %) reporting restrained eating behaviour. Scores on the Eating Attitudes Test (EAT-26) indicated that 45·2 % of these female college students should be screening for eating disorders. Subscales of the Body Esteem Scale (BES) showed that these women did not have substantial body esteem issues and mean scores on the Sociocultural Attitudes Towards Appearance Questionnaire (SATAQ-3) indicated that overall these women did not feel the media was dictating the way their body should look. Where Jordanian women did feel pressure from Western media, there was a 6·7-fold increase in the likelihood that they wanted to lose weight. In addition, 48·2 % of the female college students desired to lose weight and 14·4 % desired weight gain, indicating a certain level of body dissatisfaction.

Conclusions

With low levels of overweight and obesity and a propensity towards eating based on external hunger cues, college-aged Jordanian women may be less advanced in their development through the nutrition transition than the general population of women. However, high levels of restrained eating and disordered eating attitudes and behaviours indicate the need for an intervention to address healthy weight-loss strategies, assess eating disorders and help maintain healthy body esteem.
‘Candidatus Accumulibacter’ gene expression in response to dynamic EBPR conditions
Authors: He Shaomei , McMahon Katherine D
Published: August 2010

Enhanced biological phosphorus removal (EBPR) activated sludge communities enriched in ‘Candidatus Accumulibacter’ relatives are widely used in wastewater treatment, but much remains to be learned about molecular-level controls on the EBPR process. The expression of genes found in the carbon and polyphosphate metabolic pathways in Accumulibacter was investigated using reverse transcription quantitative PCR. During a normal anaerobic/aerobic EBPR cycle, gene expression exhibited a dynamic change in response to external acetate, oxygen, phosphate concentrations and probably internal chemical pools. Anaerobic acetate addition induced expression of genes associated with the methylmalonyl-CoA pathway enabling the split mode of the tricarboxylic acid (TCA) cycle. Components of the full TCA cycle were induced after the switch to aerobic conditions. The induction of a key gene in the glyoxylate shunt pathway was observed under both anaerobic and aerobic conditions, with a higher induction by aeration. Polyphosphate kinase 1 from Accumulibacter was expressed, but did not appear to be regulated by phosphate limitation. To understand how Accumulibacter responds to disturbed electron donor and acceptor conditions, we perturbed the process by adding acetate aerobically. When high concentrations of oxygen were present simultaneously with acetate, phosphate-release was almost completely inhibited, and polyphosphate kinase 1 transcript abundance decreased. Genes associated with the methylmalonyl-CoA pathway were repressed and genes associated with the aerobic TCA cycle exhibited higher expression under this perturbation, suggesting that more acetyl-CoA was metabolized through the TCA cycle. These findings suggest that several genes involved in EBPR are tightly regulated at the transcriptional level.
Targeted interactomics reveals a complex core cell cycle machinery in Arabidopsis thaliana
Authors: Van Leene Jelle , Hollunder Jens , Eeckhout Dominique , Persiau Geert , Van De Slijke Eveline , Stals Hilde , Van Isterdael Gert , Verkest Aurine , Neirynck Sandy , Buffel Yelle , De Bodt Stefanie , Maere Steven , Laukens Kris , Pharazyn Anne , Ferreira Paulo C G , Eloy Nubia , Renne Charlotte , Meyer Christian , Faure Jean‐Denis , Steinbrenner Jens , Beynon Jim , Larkin John C , Van de Peer Yves , Hilson Pierre , Kuiper Martin , De Veylder Lieven , Van Onckelen Harry , Inzé Dirk , Witters Erwin , De Jaeger Geert
Published: August 2010

Cell proliferation is the main driving force for plant growth. Although genome sequence analysis revealed a high number of cell cycle genes in plants, little is known about the molecular complexes steering cell division. In a targeted proteomics approach, we mapped the core complex machinery at the heart of the Arabidopsis thaliana cell cycle control. Besides a central regulatory network of core complexes, we distinguished a peripheral network that links the core machinery to up‐ and downstream pathways. Over 100 new candidate cell cycle proteins were predicted and an in‐depth biological interpretation demonstrated the hypothesis‐generating power of the interaction data. The data set provided a comprehensive view on heterodimeric cyclin‐dependent kinase (CDK)–cyclin complexes in plants. For the first time, inhibitory proteins of plant‐specific B‐type CDKs were discovered and the anaphase‐promoting complex was characterized and extended. Important conclusions were that mitotic A‐ and B‐type cyclins form complexes with the plant‐specific B‐type CDKs and not with CDKA;1, and that D‐type cyclins and S‐phase‐specific A‐type cyclins seem to be associated exclusively with CDKA;1. Furthermore, we could show that plants have evolved a combinatorial toolkit consisting of at least 92 different CDK–cyclin complex variants, which strongly underscores the functional diversification among the large family of cyclins and reflects the pivotal role of cell cycle regulation in the developmental plasticity of plants.
Influence of Psychosocial Factors on Postpartum Weight Retention
Authors: Pedersen Pernille , Baker Jennifer L. , Henriksen Tine B. , Lissner Lauren , Heitmann Berit L. , Sørensen Thorkild I.A. , Nohr Ellen A.
Published: August 2010

For some women, pregnancy may increase the risk of future obesity with consequences for health and well‐being. Psychosocial factors may be partly responsible for this. The aim of this study was to examine the association between psychosocial factors during pregnancy and postpartum weight retention (PPWR) at 6 and 18 months. A total of 37,127 women in The Danish National Birth Cohort (DNBC; 1996–2002) participated in four telephone interviews before and after delivery. They gave information about their experience of distress, depression and anxiety, social support, and psychosocial burdens during pregnancy. PPWR was defined as retention ≥5 kg at 6 and 18 months postpartum according to a woman's prepregnancy weight. The associations were examined by use of logistic regression and presented as odds radios with 95% confidence intervals. Women who were more likely to feel depressed/anxious or distressed during pregnancy had a higher risk of PPWR at 6 months (1.35 (1.27; 1.44) and 1.30 (1.22; 1.38)) and 18 months (1.34 (1.24; 1.45) and 1.32 (1.23; 1.42)). Likewise, women who felt burdened by their economy or working situation had a higher risk of PPWR as did women with the lowest incomes or less education. Women who reported a high level of distress or depression/anxiety both during pregnancy and in the first 6 months of motherhood had the highest risk of PPWR 18 months postpartum (1.54 (1.39; 1.71) and 1.49 (1.32; 1.69), respectively). Feeling distressed, depressed, or anxious during pregnancy was associated with higher PPWR as was personal and economical burdens. Adverse psychosocial characteristics may be a common determinant of weight retention after childbirth.
Ionic polymer transducers in sensing: Implications of the streaming potential hypothesis for varied electrode architecture and loading rate
Authors: Gao Fei , Weiland Lisa M.
Published: August 2010

Explored is the mechanism of streaming potential in the sensing response of ionic polymer transducers, sometimes referred to as ionic polymer metal composites. It is argued that, unlike previous hypotheses, the streaming potential hypothesis is insensitive to the assumed ionomer morphology, and accommodates experimental observation of sensing under shear loading. As demonstration a simplified model for sensing under bending deformation is presented for a material system displaying a cylindrical channel morphology. Specific demonstration scenarios considered include predicting the evolution of sensing with electrode particulate volume fraction and type. In addition, evolution of sensing for both step and oscillatory loading is considered.
Characterization of electron self-injection in laser wake field acceleration due to the parametric resonance
Authors: Zhidkov A. , Koga J. , Hosokai T. , Fujii T. , Oishi Y. , Nemoto K. , Kodama R.
Published: August 2010

The wave-breaking processes originating from a parametric resonance in the wake of a laser pulse in the absence of pulse overfocusing are thoroughly analyzed via multidimensional particle-in-cell simulations. The processes play a key role in the electron self-injection in the laser-driven acceleration of high energy, monoenergetic electrons in plasma channels. The resonance character of the charge loading in the first, second, and third injections is shown; its effect on the electron acceleration is demonstrated.
Absence of ferromagnetic order in high quality bulk Co-doped ZnO samples
Authors: de Carvalho H. B. , de Godoy M. P. F. , Paes R. W. D. , Mir M. , Ortiz de Zevallos A. , Iikawa F. , Brasil M. J. S. P. , Chitta V. A. , Ferraz W. B. , Boselli M. A. , Sabioni A. C. S.
Published: August 2010

Bulk Zn1−xCoxO samples were synthesized via standard solid-state reaction route with different Co molar concentrations up to 21%. A detailed microstructural analysis was carried out to investigate alternative sources of ferromagnetism, such as secondary phases and nanocrystals embedded in the bulk material. Conjugating different techniques we confirmed the Zn replacement by Co ions in the wurtzite ZnO structure, which retains, however, a high crystalline quality. No segregated secondary phases neither Co-rich nanocrystals were detected. Superconducting quantum interference device magnetometry demonstrates a paramagnetic Curie–Weiss behavior with antiferromagnetic interactions. We discuss the observed room temperature paramagnetism of our samples considering the current models for the magnetic properties of diluted magnetic semiconductors.
Low temperature photoluminescence and cathodoluminescence studies of nonpolar GaN grown using epitaxial lateral overgrowth
Authors: Häberlen M. , Badcock T. J. , Moram M. A. , Hollander J. L. , Kappers M. J. , Dawson P. , Humphreys C. J. , Oliver R. A.
Published: August 2010

Low temperature cathodo- and photoluminescence has been performed on nonpolar a-plane GaN films grown using epitaxial lateral overgrowth. In films overgrown at a low V–III ratio, the emission spectrum is dominated by “yellow” and “blue” luminescence bands, attributed to recombination at point defects or impurities. The intensity of this emission is observed to decrease steadily across the window region along the −c direction, possibly due to asymmetric diffusion of a point defect/impurity species. When overgrown at a higher V–III ratio, the near band edge and basal-plane stacking fault emission intensity increases by orders of magnitude and a donor–acceptor pair band is observed. Using monochromatic cathodoluminescence imaging, the various emission features are correlated with the microstructure of the film. In particular, the peak energy of the basal-plane stacking fault emission is seen to be blueshifted by ∼15 meV in the wing relative to the window region, which may be related to the different strain states in the respective regions.
Linear complex polarization propagator in a four-component Kohn–Sham framework
Authors: Villaume Sebastien , Saue Trond , Norman Patrick
Published: August 2010

An algorithm for the solution of the linear response equation in the random phase approximation is presented. All entities including frequency arguments, matrices, and vectors, are assumed to be complex, and it represents the core equation solver needed in complex polarization propagator approaches where nonstimulated relaxation channels are taken into account. Stability and robustness of the algorithm are demonstrated in applications regarding visible, ultraviolet, and x-ray spectroscopies. An implementation of the algorithm at the level of four-component relativistic, noncollinear, density functional theory for imaginary (but not complex) frequency arguments has been achieved and is used to determine the electric dipole dispersion interaction coefficients for the rubidium and cesium dimers. Our best estimates for the C6 coefficients of Rb2 and Cs2 are equal to 14.0×103 and 21.9×103 a.u., respectively.
Temperature dependent capacitance and conductance-voltage characteristics of Au/polyvinyl alcohol(Co,Zn)/n-Si Schottky diodes
Authors: Bülbül M. M. , Bengi S. , Dökme İ. , Altındal Ş. , Tunç T.
Published: August 2010

The temperature dependence of capacitance-voltage (C-V) and conductance-voltage (G/w-V) characteristics of Au/polyvinyl alcohol (Co,Zn-doped)/n-Si Schottky diodes (SDs) was investigated by considering series resistance effect in the temperature range of 80–400 K. The C-V and G/w-V characteristics confirm that the series resistance (Rs) and interface state density (Nss) of the diode are important parameters that strongly influence the electric parameters of SDs. The crossing of the G/w-V curves appears as an abnormality compared to the conventional behavior of ideal SDs. It is thought that the presence of series resistance keeps this intersection hidden and unobservable in homogeneous SDs but it appears in the case of inhomogeneous SDs. In addition, the high frequency Cm and Gm/w values measured under both reverse and forward bias were corrected for the effect of series resistance to obtain the real diode capacitance and conductance.
Current-driven ion cyclotron instability of multicomponent field-aligned sheared flow
Authors: Chibisov D. V. , Mikhailenko V. S. , Stepanov K. N.
Published: August 2010

The effect of velocity shear of the magnetic field-aligned plasma flow on excitation of the current-driven electrostatic oxygen ion cyclotron instability in the presence of hydrogen ions is considered by using kinetic formalism. It is shown that an increase of velocity shear as well as relative concentration of oxygen ions lead to a decrease of the instability threshold. The influence of the relative concentration of oxygen ions and velocity shear on the growth rate is investigated. For a weak velocity shear the growth rate decreases with reducing of the oxygen concentration, however for a strong shear the growth rate due to the presence of hydrogen ions may increase.
Pathways of mechanical unfolding of FnIII10: Low force intermediates
Authors: Caraglio M. , Imparato A. , Pelizzola A.
Published: August 2010

We study the mechanical unfolding pathways of the FnIII10 domain of fibronectin by means of an Ising-like model, using both constant force and constant velocity protocols. At high forces and high velocities our results are consistent with experiments and previous computational studies. Moreover, the simplicity of the model allows us to probe the biologically relevant low force regime, where we predict the existence of two intermediates with very close elongations. The unfolding pathway is characterized by stochastic transitions between these two intermediates.
Ultrafast deactivation processes in the 2-aminopyridine dimer and the adenine-thymine base pair: Similarities and differences
Authors: Ai Yue-Jie , Zhang Feng , Cui Gang-Long , Luo Yi , Fang Wei-Hai
Published: August 2010

2-aminopyridine dimer has frequently been used as a model system for studying photochemistry of DNA base pairs. We examine here the relevance of 2-aminopyridine dimer for a Watson–Crick adenine-thymine base pair by studying UV-light induced photodynamics along two main hydrogen bridges after the excitation to the localized π1π∗ excited-state. The respective two-dimensional potential-energy surfaces have been determined by time-dependent density functional theory with Coulomb-attenuated hybrid exchange-correlation functional (CAM-B3LYP). Different mechanistic aspects of the deactivation pathway have been analyzed and compared in detail for both systems, while the related reaction rates have also be obtained from Monte Carlo kinetic simulations. The limitations of the 2-aminopyridine dimer as a model system for the adenine-thymine base pair are discussed.
Strain-induced magnetoresistance for novel strain sensors
Authors: Xu Xiaoyong , Li Mei , Hu Jingguo , Dai Jun , Xia Weiwei
Published: August 2010

The strain-induced magnetoresistance (MR) has been investigated in detail by simulating the spin-rotation in spin-valve structures. The results show that the strain-induced anisotropy can be utilized to control the relative orientation of the spins in the two adjacently arranged ferromagnetic layers because each layer responds to the external strain differently, thus the strain-induced MR is exhibited. The MR dependencies on magnitude and orientation of strain have been described in detail. Especially, we highlight first the behavior of MR induced by the direction of strain with respect to the magnetic easy axis. In addition, the effects of some magnetic parameters on strain-induced MR have been presented, respectively. This work clarifies further the strain-induced MR mechanism to provide a theoretical support both for a number of experiments and for the design of the MR strain sensors.
Spin-component-scaling second-order Møller–Plesset theory and its variants for economical correlation energies: Unified theoretical interpretation and use for quartet N3
Authors: Varandas A. J. C.
Published: August 2010

The spin-component-scaling second-order Møller–Plesset theory proposed by Grimme, the scaled opposite-spin variant of Head-Gordon and co-workers, and other variants of the theory to treat the electron correlation energy are examined. A refinement of scaled opposite-spin theory for strong chemical interactions is suggested where the scaled correlation contribution is chosen such as to mimic closely the one obtained by more sophisticated methods of the coupled cluster type. With the scaling factor chosen to vary in a simple statistical manner with the number of opposite-spin electron pairs of the system, the parameters have been calibrated from standard coupled cluster type calculations for a chosen ab initio test data set. The new approach, termed as variable-scaling opposite spin, aims to be applicable at any regions of the molecule configuration space where second-order Møller–Plesset perturbation theory converges. It thus benefits of all advantages inherent to the original theory, which makes it an attractive approach on a computational cost basis. Because the method in one of its formats fails size-extensivity, the consequences and remedies of this are analyzed. Illustrations are presented for many molecules utilizing Dunning-type basis sets, in particular, for a detailed analysis of N3 in its lowest quartet state, which does not belong to the test set. Extrapolations of the calculated raw energies to the complete one-electron basis set limit are also reported, giving the most reliable estimates available thus far of the energetics for the N(S4)+N2 exchange reaction. All spin-component-scaling schemes are known to show difficulties in dealing with weak interactions of the van der Waals type, which has justified the design of specific variants of the theory according to the property and regime of interactions. Several variants of the theory are then examined using a second test set of molecules, and shown to be linked via a coordinate that evolves gradually between two known extreme regimes. It is further shown that such a coordinate can be specified via a constrained Feenberg-type scaling approach, a theory whose merits are also explored.
On the mechanism of atmospheric pressure plasma plume
Authors: Chen Longwei , Zhao Peng , Shu Xingsheng , Shen Jie , Meng Yuedong
Published: August 2010

For the purpose of unveiling the parameters influencing the length of atmospheric pressure plasma plume, an over 165 cm long argon plasma plume is generated in the quartz tube attached to the nozzle of the device. Dependence of plasma length on discharge parameters such as applied voltage, frequency of power supply, and argon gas flow rate was investigated. Experimental results indicated that (a) the applied voltage plays crucial roles on plasma plume length, that is, the plasma plume length exponentially increases with the applied voltage, (b) the plasma plume length increases with frequency, more obviously when the applied voltage is higher, (c) the plasma plume length increases with argon gas flow rate, reaches its maximum at critical value of the gas flow rate, and then decreases again. An evaluation of the physical phenomena involved in streamer propagation, particularly of the energy balance, was investigated. The numerical results were qualitatively consistent with previous experimental results by successfully indicating the high velocity of “plasma bullet” and providing physical mechanism of energy balance determining streamer length.
Determining the three-phase coexistence line in methane hydrates using computer simulations
Authors: Conde M. M. , Vega C.
Published: August 2010

Molecular dynamics simulations have been performed to estimate the three-phase (solid hydrate-liquid water-gaseous methane) coexistence line for the water-methane binary mixture. The temperature at which the three phases are in equilibrium was determined for three different pressures, namely, 40, 100, and 400 bar by using direct coexistence simulations. In the simulations water was described by using either TIP4P, TIP4P/2005, or TIP4P/Ice models and methane was described as simple Lennard-Jones interaction site. Lorentz–Berthelot combining rules were used to obtain the parameters of the cross interactions. For the TIP4P/2005 model positive deviations from the energetic Lorentz–Berthelot rule were also considered to indirectly account for the polarization of methane when introduced in liquid water. To locate the three-phase coexistence point, two different global compositions were used, which yielded (to within statistical uncertainty) the same predictions for the three-phase coexistence temperatures, although with a somewhat different time evolution. The three-phase coexistence temperatures obtained at different pressures when using the TIP4P/Ice model of water were in agreement with the experimental results. The main reason for this is that the TIP4P/Ice model reproduces the melting point of ice Ih.
Lifetimes of heavy-Rydberg ion-pair states formed through Rydberg electron transfer
Authors: Cannon M. , Wang C. H. , Dunning F. B. , Reinhold C. O.
Published: August 2010

The lifetimes of K+∙∙Cl−, K+∙∙CN−, and K+∙∙SF6− heavy-Rydberg ion-pair states produced through Rydberg electron transfer reactions are measured directly as a function of binding energy using electric field induced detachment and the ion-pair decay channels discussed. The data are interpreted using a Monte Carlo collision code that models the detailed kinematics of electron transfer reactions. The lifetimes of K+∙∙Cl− ion-pair states are observed to be very long, >100 μs, and independent of binding energy. The lifetimes of strongly bound (>30 meV) K+∙∙CN− ion pairs are found to be similarly long but begin to decrease markedly as the binding energy is reduced below this value. This behavior is attributed to conversion of rotational energy in the CN− ion into translational energy of the ion pair. No long-lived K+∙∙SF6− ion pairs are observed, their lifetimes decreasing with increasing binding energy. This behavior suggests that ion-pair loss is associated with mutual neutralization as a result of charge transfer.
Numerical study of in situ preconcentration for rapid and sensitive nanoparticle detection
Authors: Yang Kai , Wu Jie
Published: August 2010

This paper presents a numerical study of a preconcentrator design that can effectively increase the binding rate at the sensor in a real time manner. The particle enrichment is realized by the ac electrothermal (ACET) effect, which induces fluid movement to carry nanoparticles toward the sensor. The ACET is the only electrical method to manipulate a biological sample of medium to high ionic strength (>0.1 S/m, e.g., 0.06× phosphate buffered saline). The preconcentrator consists of a pair of electrodes striding over the sensor, simple to implement as it is electrically controlled. This preconcentrator design is compatible and can be readily integrated with many types of micro- to nanosensors. By applying an ac signal over the electrodes, local vortices will generate a large velocity perpendicular to the reaction surface, which enhances transport of analytes toward the sensor. Our simulation shows that the binding rate at the sensor surface is greatly enhanced. Our study also shows that the collection of analytes will be affected by various parameters such as channel height, inlet velocity, and sensor size, and our results will provide guidance in optimization of the preconcentrator design.
Plasmon-assisted photoluminescence enhancement of single-walled carbon nanotubes on metal surfaces
Authors: Sakashita Takerou , Miyauchi Yuhei , Matsuda Kazunari , Kanemitsu Yoshihiko
Published: August 2010

We demonstrated photoluminescence (PL) enhancement in single carbon nanotubes using localized surface plasmons. Single nanotube spectroscopy revealed triple the PL intensity enhancement for carbon nanotubes on rough Au surfaces as on fused silica surfaces. The PL enhancement depends on the excitation wavelength and distance between the carbon nanotubes and the Au surface. The degree of PL enhancement is determined by the electric field enhancement from the localized surface plasmon and the energy transfer from the carbon nanotube to the metal surface.
Insights from Monte Carlo simulations on charge inversion of planar electric double layers in mixtures of asymmetric electrolytes
Authors: Wang Zhi-yong , Ma Yu-qiang
Published: August 2010

Monte Carlo simulations of a planar negatively charged dielectric interface in contact with a mixture of 1:1 and 3:1 electrolytes are carried out using the unrestricted primitive model under more realistic hydrated ion sizes. Two typical surface charge densities are chosen to represent the systems from the weak to strong coupling regimes. Our goal is to determine the dependence of the degree of charge inversion on increasing concentration of both mono- and trivalent salts and to provide a systematic study on this peculiar effect between short-range and electrostatic correlations. The numerical results show that addition of monovalent salt diminishes the condensation of trivalent counterions due to either the favorable solvation energy or the available space constraints. As the concentration of trivalent salt increases, on the other hand, the inclusion of the ionic size and size asymmetry results in a damped oscillatory charge inversion at low enough surface charge and another counterintuitive surface charge amplification. It is proposed that both of the anomalous events in the weak coupling regime are thought to be entropic in origin which is completely different from the electrostatic driven charge inversion in the strong coupling regime. In addition, the electrostatic images arising from the dielectric mismatch lead to a decaying depletion effect on the structure of double layer with growing salt concentration in the case of low charged interface but have no effect at high surface charge values. The microscopic information obtained here points to the need for a more quantitative theoretical treatment in describing the charge inversion phenomenon of real colloidal systems.
Dynamics of pressure propulsion of a sphere in a viscous compressible fluid
Authors: Felderhof B. U.
Published: August 2010

A mechanical model of pressure propulsion of a sphere in a viscous compressible fluid is studied on the basis of the linearized Navier–Stokes equations. It is assumed that chemical reactions in the neighborhood of the sphere cause pressure waves which push the sphere. A simple expression is derived for the displacement after a single pulse on the basis of a generalized Faxén theorem. The cooperation of many pulses leads to stochastic behavior of the sphere displacement due to randomness in position of the pulses relative to the sphere surface and due to randomness in time of expansion events.
Chaotic properties of quantum transport in Ni–Nb–Zr–H glassy alloys
Authors: Fukuhara Mikio , Ban Masanobu
Published: August 2010

We analyzed the dynamic evolution of an ensemble of electrons performing macroscopic resonant tunneling for room-temperature millimeter-sized Coulomb oscillation in Ni–Nb–Zr–H glassy alloys as a function of the cluster size and boundary length using a one-dimensional Kronig–Penny model with a stepwise potential. The reflection coefficient showed a stagnant chaos around a narrow torus for a superlattice with a cluster size of 0.55 nm and a boundary distance of 0.23 nm. The transmission and reflection coefficients showed stationary chaotic behavior in periodic units with decreasing boundary distance rather than increasing cluster size.
Scaling of high-order harmonic efficiencies with visible wavelength drivers: A route to efficient extreme ultraviolet sources
Authors: Falcão-Filho Edilson L. , Lai Chien-Jen , Hong Kyung-Han , Gkortsas Vasileios-Marios , Huang Shu-Wei , Chen Li-Jin , Kärtner Franz X.
Published: August 2010

Scaling of high-order harmonic generation (HHG) efficiency versus drive wavelength is experimentally studied using 800 and 400 nm pulses and theoretically modeled for visible drive wavelength. We demonstrate good agreement of experimental results with the calculations from a recently established semianalytic HHG model and discuss the feasibility of efficient-HHG-based extreme ultraviolet sources driven by visible ultrafast lasers. Our study shows that efficiencies of >10−5 can be achieved at ∼90 eV by selecting appropriate drive wavelengths with He under good phase matching conditions.
Nanomeasurements of electronic and mechanical properties of fullerene embedded Si(111) surfaces
Authors: Huang Chih-Pong , Su Chih-Chuan , Su Wan-Sheng , Hsu Chiao-Fang , Ho Mon-Shu
Published: August 2010

This study describes the feasibility of fabricating of a single layer of fullerene embedded Si surface through a controlled self-assembly mechanism in an ultrahigh vacuum (UHV) chamber. The characteristics of the fullerene embedded Si surface are investigated directly using UHV-scanning probe microscopy. Additionally, the band gap energy and field emission parameters, including turn-on field and the field enhancement factor β of the fullerene embedded Si substrate, are determined using a high-voltage source measurement unit and UHV-scanning tunneling microscopy, respectively. Moreover, the nanomechanical properties, which represent the stress of the fullerene embedded Si substrates, are assessed by an environment atomic force microscope (AFM) and UHV-AFM, respectively. Results of this study demonstrate that a single layer of the fullerene embedded surface has superior properties for nanotechnology applications owing to the ability to control the self-assembly mechanism of fabrication.
Rate-dependence of the switching field distribution in nanoscale granular magnetic materials
Authors: Hovorka O. , Evans R. F. L. , Chantrell R. W. , Berger A.
Published: August 2010

The external field sweep-rate dependence of the intrinsic switching field distribution in perpendicular recording media is investigated. We derive a scaling relationship for switching field distributions at different sweep-rates, which we then validate by means of large-scale kinetic Monte Carlo simulations based on interacting Stoner–Wohlfarth particles. After demonstrating the possible occurrence of large differences between switching field distributions at slow time scales of conventional magnetometry and very fast processes relevant in magnetic recording, we propose a technique for extrapolating between these very different sweep-rates.
Stochastic simulation of photon propagation in Si for extreme-ultraviolet mask-defect inspection
Authors: Pei Ting-Hang , Tsai Kuen-Yu , Li Jia-Han
Published: August 2010

Extreme-ultraviolet (EUV) light is used to inspect the Si photomask by analyzing the reflective photons. We demonstrated the re-emitting EUV photons from the flat Si surface and a two-dimensional semicircular Si defect by using the Monte Carlo method with a Gaussian phase function, respectively. The results of a model based on the Feynman path integral matches those of the Monte Carlo method very well by multiplying a correction function. The intensity of re-emitting photons from the defect can offer enough signals at the angle intersecting the surface less than 20°.
Electrically pumped ultraviolet random lasing from heterostructures formed by bilayered MgZnO films on silicon
Authors: Tian Ye , Ma Xiangyang , Li Dongsheng , Yang Deren
Published: August 2010

We report on electrically pumped ultraviolet random lasing (RL) from heterostructures formed by bilayered MgZnO films on silicon, where Mg0.15Zn0.85O and MgxZn1−xO (x=0.25 or above) films act as the light-emitting and barrier layers, respectively. While, with a barrier layer composed of a Mg0.20Zn0.80O film, only spontaneous electroluminescence occurs in the heterostructures. It has thus been proved that a large enough conduction-band offset (ΔEc) is necessary for the electrically pumped RL from the MgZnO film-based heterostructures. The ΔEc required herein is estimated to be ∼0.17 eV. The mechanism for the results as mentioned above has been tentatively elucidated.
An integrated, self-priming dielectric elastomer generator
Authors: McKay Thomas , O’Brien Benjamin , Calius Emilio , Anderson Iain
Published: August 2010

Dielectric elastomer generators are a form of variable capacitor electricity generator with a high energy density and high flexibility. Currently, dielectric elastomer generators require external circuitry which makes the system bulkier and less flexible. In this paper we present a system that minimizes the external circuitry to six diodes so that high energy density and flexibility is maintained at the system level. An energy density of 12.6 mJ/g was experimentally demonstrated, comparing favorably with similarly sized electromagnetic and electrostatic power generators.
Contribution of optical phonons to thermal boundary conductance
Authors: Beechem Thomas , Duda John C. , Hopkins Patrick E. , Norris Pamela M.
Published: August 2010

Thermal boundary conductance (TBC) is a performance determinant for many microsystems due to the numerous interfaces contained within their structure. To assess this transport, theoretical approaches often account for only the acoustic phonons as optical modes are assumed to contribute negligibly due to their low group velocities. To examine this approach, the diffuse mismatch model is reformulated to account for more realistic dispersions containing optical modes. Using this reformulation, it is found that optical phonons contribute to TBC by as much as 80% for a variety of material combinations in the limit of both inelastic and elastic scattering.
Tunnel barrier photoelectrodes for solar water splitting
Authors: Guo Lian , Hung David , Wang Weigang , Shen Weifeng , Zhu Leyi , Chien Chia-Ling , Searson Peter C.
Published: August 2010

Tunnel barrier photoelectrodes, with a thin inorganic tunnel barrier layer that isolates the semiconductor electrode from the electrolyte while allowing current flow across the interface, are a possible solution to the problem of photocorrosion in solar water splitting. In this approach, selection of the semiconductor for the light absorber is decoupled from selection of the tunnel barrier material that provides chemical stability. Here we demonstrate a proof-of-principle of this approach with TiO2/MgO tunnel barrier photoelectrodes.
Anisotropy in electronic, optical, and mechanical properties of superhard body-centered tetragonal C4 phase of carbon
Authors: Wei P. Y. , Sun Y. , Chen X.-Q. , Li D. Z. , Li Y. Y.
Published: August 2010

By hybrid density functional theory, we have investigated anisotropies in the electronic, optical, and mechanical properties of the body centered tetragonal C4 phase of carbon. We predict a strong electronic anisotropy associated with the in-plane carbon-carbon covalent bonds and the zigzag carbon chains along the c-direction (out-of-plane), which results in a state-resolved directional distribution of valence electrons at the top of the valence band. The calculated adsorption spectra display highly anisotropic features which are already manifested at ambient pressure by a substantial difference (2 eV) for the absorption edges between the in-plane and out-of-plane components of the tetragonal cell. Similar anisotropic features in the elastic compressibility are also discussed.
Carrier dynamics of Mg-doped indium nitride
Authors: Ahn H. , Yu K.-J. , Hong Y.-L. , Gwo S.
Published: August 2010

Recently, we have reported a significant enhancement (>500 times in intensity) in terahertz emission from Mg-doped indium nitride (InN:Mg) films compared to undoped InN. It was found that the intensity of terahertz radiation strongly depends on the background electron density. In this letter, we present the results on ultrafast time-resolved reflectivity measurement employed to investigate the carrier dynamics of InN:Mg. We find that the decay time constant of InN:Mg depends on background electron density in the same way as terahertz radiation does. The spatial redistribution of carriers in diffusion and drift is found to be responsible for the recombination behavior as well as terahertz radiation.
Scanning probe based observation of bipolar resistive switching NiO films
Authors: Lee Min Hwan , Song Seul Ji , Kim Kyung Min , Kim Gun Hwan , Seok Jun Yeong , Yoon Jung Ho , Hwang Cheol Seong
Published: August 2010

The switching mechanism of the bipolar resistive switching behavior on NiO films was examined using local probe based measurements. Unlike the unipolar switching normally observed on a metal-insulator-metal structure, repetitive bipolar switching was observed on NiO films when a local probe was used as the top electrode. Surface potential and current maps obtained after the anodic/cathodic bias application through the scanning probe both in air and under high vacuum suggested that the resistive switching is caused mainly by the electrochemical redox reaction at the electrode-film interface rather than by charge drift within the NiO film.
Extensive analysis of the luminescence properties of AlGaN/GaN high electron mobility transistors
Authors: Meneghini M. , Stocco A. , Ronchi N. , Rossi F. , Salviati G. , Meneghesso G. , Zanoni E.
Published: August 2010

This paper reports on an extensive analysis of the electroluminescence spectra of GaN-based high-electron mobility transistors (HEMT) submitted to different bias regimes. The results described within this paper indicate that: (i) under ON-state bias conditions, HEMT can emit a weak luminescence signal, localized at the edge of the gate toward the drain side; (ii) for low drain voltage levels, the electroluminescence spectrum has a Maxwellian shape, which is typical for hot carrier luminescence; (iii) for high drain voltage levels, parasitic emission bands are generated, possibly due to the recombination of hot electrons through defect-related sites. Electroluminescence data are compared with results of cathodoluminescence measurements, to provide an interpretation for the experimental results.
Angle-robust resonances in cross-shaped aperture arrays
Authors: Lin L. , Roberts A.
Published: August 2010

Computational and experimental investigations of angle-dependent light transmission through nanometric cross-shaped aperture arrays in thin metal films are presented. It is shown that high-transmission associated with the excitation of localized surface plasmons within the apertures can be tailored to exhibit polarization- and angle-independent performance.
Inositol-requiring enzyme 1α is a key regulator of angiogenesis and invasion in malignant glioma
Authors: Auf Gregor , Jabouille Arnaud , Guérit Sylvaine , Pineau Raphaël , Delugin Maylis , Bouchecareilh Marion , Magnin Noël , Favereaux Alexandre , Maitre Marlène , Gaiser Timo , von Deimling Andreas , Czabanka Marcus , Vajkoczy Peter , Chevet Eric , Bikfalvi Andreas , Moenner Michel
Published: August 2010

Inositol-requiring enzyme 1 (IRE1) is a proximal endoplasmic reticulum (ER) stress sensor and a central mediator of the unfolded protein response. In a human glioma model, inhibition of IRE1α correlated with down-regulation of prevalent proangiogenic factors such as VEGF-A, IL-1β, IL-6, and IL-8. Significant up-regulation of antiangiogenic gene transcripts was also apparent. These transcripts encode SPARC, decorin, thrombospondin-1, and other matrix proteins functionally linked to mesenchymal differentiation and glioma invasiveness. In vivo, using both the chick chorio-allantoic membrane assay and a mouse orthotopic brain model, we observed in tumors underexpressing IRE1: (
i
) reduction of angiogenesis and blood perfusion, (
ii
) a decreased growth rate, and (
iii
) extensive invasiveness and blood vessel cooption. This phenotypic change was consistently associated with increased overall survival in glioma-implanted recipient mice. Ectopic expression of IL-6 in IRE1-deficient tumors restored angiogenesis and neutralized vessel cooption but did not reverse the mesenchymal/infiltrative cell phenotype. The ischemia-responsive IRE1 protein is thus identified as a key regulator of tumor neovascularization and invasiveness.
Probing in vivo Mn2+speciation and oxidative stress resistance in yeast cells with electron-nuclear double resonance spectroscopy
Authors: McNaughton Rebecca L. , Reddi Amit R. , Clement Matthew H. S. , Sharma Ajay , Barnese Kevin , Rosenfeld Leah , Gralla Edith Butler , Valentine Joan Selverstone , Culotta Valeria C. , Hoffman Brian M.
Published: August 2010

Manganese is an essential transition metal that, among other functions, can act independently of proteins toeitherdefend againstorpromote oxidative stress and disease. The majority of cellular manganese exists as low molecular-weight Mn2+complexes, and the balance between opposing “essential” and “toxic” roles is thought to be governed by the nature of the ligands coordinating Mn2+. Until now, it has been impossible to determine manganese speciation within intact, viable cells, but we here report that this speciation can be probed through measurements of1H and31P electron-nuclear double resonance (ENDOR) signal intensities for intracellular Mn2+. Application of this approach to yeast (Saccharomyces cerevisiae) cells, and two pairs of yeast mutants genetically engineered to enhance or suppress the accumulation of manganese or phosphates, supports an in vivo role for the orthophosphate complex of Mn2+in resistance to oxidative stress, thereby corroborating in vitro studies that demonstrated superoxide dismutase activity for this species.
Personal Pronouns in the Kakavandi Laki Dialect of Harsin (Kermanshah, Iran)
Authors: Mirdehghan Mahinnaz , Moradkhani Simin
Published: August 2010

This study aims to analyze the positions and syntactic functions of dependent and independent personal pronouns in the Kakavandi Laki dialect in the region of Harsin (Kermanshah/Iran), an endangered dialect of Persian. The paper provides a morpho-syntactic description and investigates the dialectal characteristic positions of the pronominals in regard to their syntactic functions, which illustrate noticeable differences in comparison to Persian. The main functions under investigation include: subjective, objective, oblique and possessives, on the basis of which the pronominal positional variety is classified in the dialect. The study further examines the dialectal agreement patterns which demonstrate both ergative and non-ergative features.