bluuebunny/crossref_metadata_2025 huggingface dataset:
Sodiation vs. lithiation phase transformations in a high rate – high stability SnO2 in carbon nanocomposite
Authors: Ding Jia , Li Zhi , Wang Huanlei , Cui Kai , Kohandehghan Alireza , Tan Xuehai , Karpuzov Dimitre , Mitlin David
Published: February 2015

An SnO2-carbon nanocomposite was created by a self-assembly method. This showed promising electrochemical performance as both a Na and Li ion battery anode, with among the best cyclability and rate capability when tested against Na.
An ion exchange mediated shape-preserving strategy for constructing 1-D arrays of porous CoS1.0365 nanorods for electrocatalytic reduction of triiodide
Authors: Patil Supriya A. , Shinde Dipak V. , Lim Iseul , Cho Keumnam , Bhande Sambhaji S. , Mane Rajaram S. , Shrestha Nabeen K. , Lee Joong Kee , Yoon Tae Hyun , Han Sung-Hwan
Published: February 2015

A solution based ion exchange mediated strategy for constructing 1-D arrays of porous CoS1.0365 nanorod film from analogous 1-D array of Co3O4 film derived from pyrolysis of nanostructured cobalt hydroxycarbonate film.
Ultraviolet photocatalytic degradation of methyl orange by nanostructured TiO2/ZnO heterojunctions
Authors: Zha Ruhua , Nadimicherla Reddeppa , Guo Xin
Published: February 2015

High photocatalytic activities of TiO2/ZnO heterojunctions.
Efficient long lifetime room temperature phosphorescence of carbon dots in a potash alum matrix
Authors: Dong Xinwei , Wei Liangming , Su Yanjie , Li Zhongli , Geng Huijuan , Yang Chao , Zhang Yafei
Published: February 2015

Carbon dot composite powders show long phosphorescence lifetimes when the carbon dots are dispersed into a potash alum matrix.
PAQR3 modulates H3K4 trimethylation by spatial modulation of the regulatory subunits of COMPASS-like complexes in mammalian cells
Authors: Liu Chunchun , Zhang Yuxue , Hou Yongfan , Shen Liqiang , Li Yinlong , Guo Weiwei , Xu Daqian , Liu Gaigai , Zhao Zilong , Man Kaiyang , Pan Yi , Wang Zhenzhen , Chen Yan
Published: February 2015

Epigenetic control via histone methylation is important in transcriptional regulation and occurs in the nucleus. However, this process can be regulated spatially by a protein localized in the Golgi apparatus. Subcellular compartmentalization can therefore affect epigenetic modification.
Silencing efficacy prediction: a retrospective study on target mRNA features
Authors: Pascut Devis , Bedogni Giorgio , Tiribelli Claudio
Published: February 2015

Post-transcriptional gene silencing is a widely used method to suppress gene expression. Unfortunately only a portion of siRNAs do successfully reduce gene expression. Target mRNA secondary structures and siRNA-mRNA thermodynamic features are believed to contribute to the silencing activity. However, there is still an open discussion as to what determines siRNA efficacy. In this retrospective study, we analysed the target accessibility comparing very high (VH) compared with low (L) efficacy siRNA sequences obtained from the siRecords Database. We determined the contribution of mRNA target local secondary structures on silencing efficacy. Both the univariable and the multivariable logistic regression evidenced no relationship between siRNA efficacy and mRNA target secondary structures. Moreover, none of the thermodynamic and sequence-base parameters taken into consideration (H-b index, ΔG°overall, ΔG°duplex, ΔG°break-target and GC%) was associated with siRNA efficacy. We found that features believed to be predictive of silencing efficacy are not confirmed to be so when externally evaluated in a large heterogeneous sample. Although it was proposed that silencing efficacy could be influenced by local target accessibility we show that this could be not generalizable because of the diversity of experimental setting that may not be representative of biological systems especially in view of the many local protein factors, usually not taken into consideration, which could hamper the silencing process.
T helper 9 cells induced by plasmacytoid dendritic cells regulate interleukin-17 in multiple sclerosis
Authors: Ruocco Gabriella , Rossi Silvia , Motta Caterina , Macchiarulo Giulia , Barbieri Francesca , De Bardi Marco , Borsellino Giovanna , Finardi Annamaria , Grasso Maria Grazia , Ruggieri Serena , Gasperini Claudio , Furlan Roberto , Centonze Diego , Battistini Luca , Volpe Elisabetta
Published: February 2015

Multiple sclerosis (MS) is a chronic disease of the central nervous system (CNS) characterized by persistent inflammation orchestrated by cluster of differentiation (CD) 4 T helper (Th) cells. In particular, Th1 and Th17 cells amplify, whereas T regulatory (Treg) cells moderate inflammation. The role of other Th subsets in MS is not clear. In the present study, we investigated the generation of different Th responses by human dendritic cells (DCs) in MS. We compared the production of several Th cytokines by naive CD4+ T-cells polarized with myeloid and plasmacytoid DCs (mDCs and pDCs) in healthy donors (HD) and relapsing–remitting (RR)-MS patients. We found that resiquimod-stimulated mDCs were able to activate Th17 differentiation, whereas pDCs induced interleukin (IL)-10-producing Th cells. Surprisingly, resiquimod-stimulated pDCs from MS patients also significantly induced the differentiation of Th9 cells, which produce IL-9 and are known to be involved in allergic diseases. We investigated the potential role of IL-9 in MS. We found that IL-9 activated signal transducer and activator of transcription (STAT) 1 and STAT5 phosphorylation and interfered with IL-17 and interferon (IFN) regulatory transcription factor (IRF)-4 expression in Th17-polarized cells. Moreover, in the cerebrospinal fluid (CSF) of 107 RR-MS patients, IL-9 inversely correlated with indexes of inflammatory activity, neurodegeneration and disability progression of MS. High levels of IL-9 were associated with the absence of IL-17 in the CSF of RR-MS patients. Our results demonstrate a Th9-inducing potential of pDCs in MS, suggesting an immunoregulatory role leading to attenuation of the exaggerated Th17 inflammatory response.
Pigment epithelium-derived factor regulates microvascular permeability through adipose triglyceride lipase in sepsis
Authors: He Ting , Hu Jiongyu , Yan Guangning , Li Lingfei , Zhang Dongxia , Zhang Qiong , Chen Bing , Huang Yuesheng
Published: February 2015

The integrity of the vascular barrier, which is essential to blood vessel homoeostasis, can be disrupted by a variety of soluble permeability factors during sepsis. Pigment epithelium-derived factor (PEDF), a potent endogenous anti-angiogenic molecule, is significantly increased in sepsis, but its role in endothelial dysfunction has not been defined. To assess the role of PEDF in the vasculature, we evaluated the effects of exogenous PEDF in vivo using a mouse model of cecal ligation and puncture (CLP)-induced sepsis and in vitro using human dermal microvascular endothelial cells (HDMECs). In addition, PEDF was inhibited using a PEDF–monoclonal antibody (PEDF–mAb) or recombinant lentivirus vectors targeting PEDF receptors, including adipose triglyceride lipase (ATGL) and laminin receptor (LR). Our results showed that exogenous PEDF induced vascular hyperpermeability, as measured by extravasation of Evan's Blue (EB), dextran and microspheres in the skin, blood, trachea and cremaster muscle, both in a normal state and under conditions of sepsis. In control and LR–shRNA-treated HDMECs, PEDF alone or in combination with inflammatory mediators resulted in activation of RhoA, which was accompanied by actin rearrangement and disassembly of intercellular junctions, impairing endothelial barrier function. But in ATGL–shRNA-treated HDMECs, PEDF failed to induce the aforementioned alterations, suggesting that PEDF-induced hyperpermeability was mediated through the ATGL receptor. These results reveal a novel role for PEDF as a potential vasoactive substance in septic vascular hyperpermeability. Furthermore, our results suggest that PEDF and ATGL may serve as therapeutic targets for managing vascular hyperpermeability in sepsis.
The Clinical Evaluation: A Necessary Tool for the Dysphagia Sleuth
Authors: Coyle James L.
Published: February 2015

There is controversy about the necessity of clinical (bedside) swallowing examinations. Some argue that screening provides enough information to thoroughly manage a case. In instances in which the risk of an adverse event is very high, screening legitimizes short-term intervention to temporarily mitigate that risk. But comprehensive treatment based on screening is always an unguided and imprecise strategy because screening cannot identify the nature of the problem or the method that best treats the problem. As physicians and public health experts know, the diagnostic process begins with case-finding procedures that predict the presence of risk, and progresses through increasingly precise methods until the clinical problem is resolved. Sometimes the more costly gold standard examination is unnecessary. And sometimes the gold standard test is unavailable because the patient is seen in a system in which the infrastructure and expertise for conducting diagnostic instrumental testing are inaccessible, or because of wait lists, or funding issues. Such situations require the speech-language-pathologist (SLP) to determine how to gather the most and best information available under these constraints. This article will discuss the clinical examinations' role in the diagnostic process and refute the claim that it is unnecessary.
Special Considerations for the Pediatric Population Relating to a Swallow Screen Versus Clinical Swallow or Instrumental Evaluation
Authors: Delaney Amy L.
Published: February 2015

Careful consideration should be taken to determine how a swallow screen could be implemented in the pediatric population. A variety of factors to be considered include: age, developmental level, feeding experience of the child, diagnosis, the status of the child's dysphagia, and the setting where the patient is treated. A swallow screen might be feasible in specific situations in the pediatric population to identify aspiration risk in those with a change in normal swallow status. Yet, more research is needed to improve the accurate identification for the pediatric population of aspiration risk and other signs of dysphagia that warrant an instrumental assessment. While risk for aspiration is a concern in this population, it is not the only concern due to the dynamic changes in feeding and swallowing performance that occur throughout childhood. These dynamic changes require a thorough clinical observation that neither a swallow screening nor instrumental assessment can provide the clinician. Thus, the clinical swallow evaluation (CSE) remains the most comprehensive tool available to assess oral feeding skill development and function, as well as, to identify risk factors for not only aspiration, but for other aspects of dysphagia, which may warrant an instrumental assessment.
Low‐complexity ZF precoding method for downlink of massive MIMO system
Authors: Ren Yuwei , Xu GuiXian , Wang YingMin , Su Xin , Li ChuanJun
Published: February 2015

In massive multiple‐input–multiple‐output (MIMO) systems, the downlink zero‐forcing (ZF) precoding method needs to compute the pseudoinverse of large matrices, which introduces high computational complexity, especially when the number of antennas is large or infinite. Although, based on Neumann series expansion, several approximation algorithms could reduce the complexity, calculating the optimisation coefficients would cost large amounts of resources and produce large delay. A novel method, also based on Neumann series expansion, is proposed. In this method, the multiplication of full matrices is transformed into multiplication of diagonal matrices by hollow matrices, effectively reducing computational complexity. Meanwhile, consideration of a simple expression of optimisation coefficients so as to avoid large delay is very useful in high‐mobility scenarios. Analysis and simulation results show the effectiveness of the proposed method.
Non‐data‐aided timing recovery algorithm for MIL‐STD SOQPSK
Authors: Wang Qifeng , Huang Benxiong , Xu Zhengguang
Published: February 2015

The phase trajectory of military standard (MIL‐STD) shaped‐offset quadrature phase shift keying (SOQPSK) is analysed and the fourth‐power nonlinearity and phase accumulation technology is used to eliminate the self‐noise caused by symbol information. After the operation, the MIL‐STD SOQPSK signal is converted into a pure tone during a symbol period and the timing offset is estimated from the initial phase of the tone. Computer simulation shows that its estimation performance is remarkably close to the modified Cramer‐Rao bound and better than that of the existing non‐data‐aided method in terms of estimation accuracy.
Efficient variable step‐size diffusion normalised least‐mean‐square algorithm
Authors: Jung Sang Mok , Seo Ji‐Hye , Park PooGyeon
Published: February 2015

An efficient variable step‐size diffusion normalised least‐mean‐square algorithm is proposed via a mean‐square deviation (MSD) analysis for the distributed estimation. The proposed algorithm has two distinguishing features for computational efficiency. In the adaptation step, an intermittent adaptation rule that dynamically adjusts an update interval is proposed to reduce the redundant updates. In the diffusion step, instead of the existing combination rules, a selection rule is proposed to select the intermediate estimate of the most reliable node among its neighbour nodes for the estimate at each node. Moreover, to achieve both fast convergence rate and low steady‐state error, a variable step size is obtained by minimising the MSD.
Two‐way relay networks based on product relay
Authors: Xu Shengkai , Xu Dazhuan , Zhang Xiaofei , Shao Hanqin
Published: February 2015

Two‐way relay networks in additive white Gaussian noise channels are studied. A novel scheme based on the product relay is proposed and the whole block diagram is obtained. Furthermore, the presented analysis shows that the proposed scheme outperforms the traditional amplify‐and‐forward relay. Two‐way relay networks based on the product relay provide a better bit error ratio performance in high signal‐to‐noise ratio regions, which is consistent with the simulation result.
Microwave waveguide filter with broadside wall slots
Authors: Shang Xiaobang , Lancaster Michael J. , Dimov Stefan
Published: February 2015

An investigation into rectangular waveguide filters with open slots on the broad side walls is reported. This type of waveguide filter eliminates the need for direct contact between the two waveguide halves and intentionally leaves a gap in the middle of broad side walls. For X‐band (8.2–12.4 GHz) waveguides, such a gap can be nearly as wide as 9% of the internal waveguide width a, without introducing any significant radiation loss. A fifth‐order filter centred at 10 GHz with a fractional bandwidth of 2% is designed based on such a structure, and fabricated from aluminium and tested. There is good agreement between measurement and simulation results. This verifies the proposed structure as well as the design procedure.
Energy efficient reconfiguration for practical load combinations in distribution systems
Authors: Ali Ikbal , Thomas Mini S. , Kumar Pawan
Published: February 2015

Practically, loads are found to be voltage dependent and reconfiguration in distribution systems changes the node voltage profile. Hence reconfiguration affects the load behaviour. In this scenario, the traditional approach of defining energy efficient operation as mere loss minimisation does not give truly energy efficient results. Therefore this study defines energy efficiency as a multi‐variable function in terms of energy efficiency defining parameters and develops an energy efficiency performance index, in order to identify an energy efficient configuration. The proposed approach of reconfiguration gives more flexibility to utilities in operating the distribution system with improved power quality and reliability, and enables them to actively participate in a competitive deregulated environment. In this study, voltage dependent loads are modelled in the form of load combinations to represent the real world loads at a bulk delivery point of the distribution system.
Electrical method to measure the transient thermal impedance of insulated gate bipolar transistor module
Authors: Wang Mei‐Yu , Lu Guo‐Quan , Mei Yun‐Hui , Li Xin , Wang Lei , Chen Gang
Published: February 2015

The thermal characterisation of insulated gate bipolar transistor (IGBT) module is very important, since the production consistency and reliability are affected when IGBT is exploited in high temperature. To investigate the transient thermal behaviour of IGBT, a transient thermal impedance (Zth) measurement system was built using the electrical method with gate‐emitter voltage as temperature‐sensitive parameter. Factors affecting the Zth measurement, such as environment temperature, heating power, duty cycle and heating time, were discussed in detail. The Zth of each component within IGBT module was measured by selecting right heating time before thermal equilibrium. It is found that the Zth measurement has high accuracy and repeatability, which is helpful to understand how thermal performance of IGBT module varies with architecture and material properties for power electronic packaging.
High‐performance quasi‐Z‐source inverter with low capacitor voltage stress and small inductance
Authors: Yang Liqiang , Qiu Dongyuan , Zhang Bo , Zhang Guidong
Published: February 2015

A high‐performance quasi‐Z‐source inverter (qZSI) is presented in this study. The proposed circuit has the four advantages: (i) reduction in voltage stress across the Z‐network capacitor, (ii) voltage source and inverter bridge share the same ground point, (iii) reduced inrush current during start‐up, (iv) wide range of load operation even with a small inductance in the Z‐network. The proposed qZSI can be controlled as the traditional ZSI. This study analyses the operation principle of the proposed circuit and carries out its parameter design. Finally, experimental results are presented to validate the operation of the proposed qZSI.
Analysis of DC–DC power supply systems for pulsed loads from green electronics perspective
Authors: Garate Jose I. , Ibarra Edorta , Martínez de Alegría Iñigo , Kortabarria Iñigo , Araujo Jose A.
Published: February 2015

Discontinuous loads frequently compromise the performance of their power source and electronics. They cause the voltage and current ripple at the source and load, and introduce electromagnetic interferences. Also, they affect the efficiency of the power source. The aforementioned issues are particularly relevant in battery powered electronics. In order to minimise these unwanted effects, it is necessary to introduce a power supply architecture between the load and the source that should filter and/or regulate the currents and voltages. This architecture could be made solely of passive components or could use DC–DC regulators. The present work classifies and characterises the most relevant architectures available. A novel switched power supply architecture for pulsed loads with adaptive input current is also introduced. A mathematical analysis of the conditions and characteristics that the regulated architectures should fulfil to obtain the maximum performance in terms of efficiency and green electronics is provided. The simulation and experimental results shown in this study demonstrate the theoretical analysis.
Optimisation for stealth target detection based on stratospheric balloon‐borne netted radar system
Authors: Barbary Mohamed , Zong Peng
Published: February 2015

This study deals with an improvement of radar cross section (RCS) of stealth target model such as F‐117A with a higher aspect vision, and proposes a new detection technique based on stratospheric balloon‐borne netted radar system. Normally, it is very difficult to statistically model a stealth target by conventional analytically probability density function (pdf) expressions. Thus, a novel non‐parametric detection technique using time difference of arrival (TDOA) and physical optics (PO) approximation method is proposed. Finally, Legendre orthogonal polynomials (LOP) using to reconstruct the pdf of stealth RCS predicted by PO. The potential problem of proposed scheme is instability of the platform caused by sudden gusts of winds. The balloon flight control is studied in detail by considering external force of wind that is typical random process with Dryden turbulence spectrum. The proposed geometrical structure of radar system is composed of one transmitter and multiple receivers. To achieve high accuracy of locating a stealth target, the proposed scheme uses accuracy RCS measurement to compute Stealth target position. Simulations demonstrate that proposed scheme using one transmitter and multiple balloon‐borne receivers give much higher location accuracy comparing to other geometrical systems because of increasing the PO – scattered field with higher aspect angles.
Shock-induced deformation of nanocrystalline Al: Characterization with orientation mapping and selected area electron diffraction
Authors: Wang L. , E J. C. , Cai Y. , Zhao F. , Fan D. , Luo S. N.
Published: February 2015

We investigate shock-induced deformation of columnar nanocrystalline Al with large-scale molecular dynamics simulations and implement orientation mapping (OM) and selected area electron diffraction (SAED) for microstructural analysis. Deformation mechanisms include stacking fault formation, pronounced twinning, dislocation slip, grain boundary (GB) sliding and migration, and lattice or partial grain rotation. GBs and GB triple junctions serve as the nucleation sites for crystal plasticity including twinning and dislocations, due to GB weakening, and stress concentrations. Grains with different orientations exhibit different densities of twins or stacking faults nucleated from GBs. GB migration occurs as a result of differential deformation between two grains across the GB. High strain rates, appropriate grain orientation and GBs contribute to deformation twinning. Upon shock compression, intra-grain dislocation and twinning nucleated from GBs lead to partial grain rotation and the formation of subgrains, while whole grain rotation is not observed. During tension, stress gradients associated with the tensile pulse give rise to intra-grain plasticity and then partial grain rotation. The simulated OM and SAED are useful to describe lattice/grain rotation, the formation of subgrains, GB migration and other microstructures.
Numerical modeling of the 3D dynamics of ultrasound contrast agent microbubbles using the boundary integral method
Authors: Wang Qianxi , Manmi Kawa , Calvisi Michael L.
Published: February 2015

Ultrasound contrast agents (UCAs) are microbubbles stabilized with a shell typically of lipid, polymer, or protein and are emerging as a unique tool for noninvasive therapies ranging from gene delivery to tumor ablation. While various models have been developed to describe the spherical oscillations of contrast agents, the treatment of nonspherical behavior has received less attention. However, the nonspherical dynamics of contrast agents are thought to play an important role in therapeutic applications, for example, enhancing the uptake of therapeutic agents across cell membranes and tissue interfaces, and causing tissue ablation. In this paper, a model for nonspherical contrast agent dynamics based on the boundary integral method is described. The effects of the encapsulating shell are approximated by adapting Hoff’s model for thin-shell, spherical contrast agents. A high-quality mesh of the bubble surface is maintained by implementing a hybrid approach of the Lagrangian method and elastic mesh technique. The numerical model agrees well with a modified Rayleigh-Plesset equation for encapsulated spherical bubbles. Numerical analyses of the dynamics of UCAs in an infinite liquid and near a rigid wall are performed in parameter regimes of clinical relevance. The oscillation amplitude and period decrease significantly due to the coating. A bubble jet forms when the amplitude of ultrasound is sufficiently large, as occurs for bubbles without a coating; however, the threshold amplitude required to incite jetting increases due to the coating. When a UCA is near a rigid boundary subject to acoustic forcing, the jet is directed towards the wall if the acoustic wave propagates perpendicular to the boundary. When the acoustic wave propagates parallel to the rigid boundary, the jet direction has components both along the wave direction and towards the boundary that depend mainly on the dimensionless standoff distance of the bubble from the boundary. In all cases, the jet directions for the coated and uncoated bubble are similar but the jet width and jet velocity are smaller for a coated bubble. The effects of shell thickness and shell viscosity are analyzed and determined to affect the bubble dynamics, including jet development.
Small angle scattering methods to study porous materials under high uniaxial strain
Authors: Le Floch Sylvie , Balima Félix , Pischedda Vittoria , Legrand Franck , San-Miguel Alfonso
Published: February 2015

We developed a high pressure cell for the in situ study of the porosity of solids under high uniaxial strain using neutron small angle scattering. The cell comprises a hydraulically actioned piston and a main body equipped with two single-crystal sapphire windows allowing for the neutron scattering of the sample. The sample cavity is designed to allow for a large volume variation as expected when compressing highly porous materials. We also implemented a loading protocol to adapt an existing diamond anvil cell for the study of porous materials by X-ray small angle scattering under high pressure. The two techniques are complementary as the radiation beam and the applied pressure are in one case perpendicular to each other (neutron cell) and in the other case parallel (X-ray cell). We will illustrate the use of these two techniques in the study of lamellar porous systems up to a maximum pressure of 0.1 GPa and 0.3 GPa for the neutron and X-ray cells, respectively. These devices allow obtaining information on the evolution of porosity with pressure in the pore dimension subdomain defined by the wave-numbers explored in the scattering process. The evolution with the applied load of such parameters as the fractal dimension of the pore-matrix interface or the apparent specific surface in expanded graphite and in expanded vermiculite is used to illustrate the use of the high pressure cells.
Global strong spherically symmetric solutions to the full compressible Navier-Stokes equations with stress free boundary
Authors: Bian Dongfen , Guo Boling , Zhang Jingjun
Published: February 2015

In this paper, we are concerned with the global strong spherically symmetric solutions to the full compressible Navier-Stokes equations with large initial data in the case that the viscosity coefficients μ, λ are both constants and the heat conductivity coefficient κ(θ) ∼ const(1 + θq), q ≥ 1. We show that the three dimensional full compressible Navier-Stokes equations away from symmetry center with the free boundary condition have a unique global strong solution.
Magnetic axis safety factor of finite β spheromaks and transition from spheromaks to toroidal magnetic bubbles
Authors: Bellan Paul M. , Paccagnella Roberto
Published: February 2015

The value of the safety factor on the magnetic axis of a finite-beta spheromak is shown to be a function of beta in contrast to what was used in Bellan, Phys. Plasmas 9, 3050 (2002); this dependence on beta substantially reduces the gradient of the safety factor compared to the previous calculation. The method for generating finite-beta spheromak equilibria is extended to generate equilibria describing toroidal magnetic “bubbles,” where the hydrodynamic pressure on the magnetic axis is less than on the toroid surface. This “anti-confinement” configuration can be considered an equilibrium with an inverted beta profile and is relevant to interplanetary magnetic clouds as these clouds have lower hydrodynamic pressure in their interior than on their surface.
High magnetic field and temperature tuning of up-conversion luminescence in Mn2+-doped (Er3+/Yb3+): NaYF4
Authors: Wang Ya-Lan , Zhang Jun-Pei , Han Jun-Bo , Hao Zhong-Hua , Wang Qu-Quan
Published: February 2015

Upconversion luminescence properties of (Yb3+/Er3+): NaYF4 and Mn2+ doped (Yb3+/Er3+): NaYF4 nanocrystals have been investigated under pulsed high magnetic field. The emission ratio of red to green of the bare (Yb3+/Er3+): NaYF4 nanocrystals increases by about 42% as the magnetic field increases from 0 T to 40 T. While for Mn2+ doped (Yb3+/Er3+): NaYF4 nanocrystals, the ratio keeps almost unchanged due to the energy transferring between Mn2+ and Yb3+/Er3+. The effects of temperature on the upconversion emissions are also compared for the two types of nanocrystals. Our observations have prospective applications in biological imaging and magnetic field detection.
Electronic structure of a graphene superlattice with massive Dirac fermions
Authors: Lima Jonas R. F.
Published: February 2015

We study the electronic and transport properties of a graphene-based superlattice theoretically by using an effective Dirac equation. The superlattice consists of a periodic potential applied on a single-layer graphene deposited on a substrate that opens an energy gap of 2Δ in its electronic structure. We find that extra Dirac points appear in the electronic band structure under certain conditions, so it is possible to close the gap between the conduction and valence minibands. We show that the energy gap Eg can be tuned in the range 0 ≤ Eg ≤ 2Δ by changing the periodic potential. We analyze the low energy electronic structure around the contact points and find that the effective Fermi velocity in very anisotropic and depends on the energy gap. We show that the extra Dirac points obtained here behave differently compared to previously studied systems.
Homogenization of the boundary value for the Neumann problem
Authors: Zhao Jie
Published: February 2015

In this paper, we study the convergence rates for homogenization problems for solutions of partial differential equations with rapidly oscillating Neumann boundary data. Such a problem raised due to its importance for higher order approximation in homogenization theory. High order approximation gives rise to the so-called boundary layer phenomenon. As a consequence, we obtain the pointwise and W1,p convergence results. Our techniques are based on Fourier analysis.
Excitation of Kelvin Helmholtz instability by an ion beam in a plasma with negatively charged dust grains
Authors: Rani Kavita , Sharma Suresh C.
Published: February 2015

An ion beam propagating through a magnetized dusty plasma drives Kelvin Helmholtz Instability (KHI) via Cerenkov interaction. The frequency of the unstable wave increases with the relative density of negatively charged dust grains. It is observed that the beam has stabilizing effect on the growth rate of KHI for low shear parameter, but for high shear parameter, the instability is destabilized with relative density of negatively charged dust grains.
Proof-of-principle demonstration of Nb3Sn superconducting radiofrequency cavities for high Q applications
Authors: Posen S. , Liepe M. , Hall D. L.
Published: February 2015

Many future particle accelerators require hundreds of superconducting radiofrequency (SRF) cavities operating with high duty factor. The large dynamic heat load of the cavities causes the cryogenic plant to make up a significant part of the overall cost of the facility. This contribution can be reduced by replacing standard niobium cavities with ones coated with a low-dissipation superconductor such as Nb3Sn. In this paper, we present results for single cell cavities coated with Nb3Sn at Cornell. Five coatings were carried out, showing that at 4.2 K, high Q0 out to medium fields was reproducible, resulting in an average quench field of 14 MV/m and an average 4.2 K Q0 at quench of 8 × 109. In each case, the peak surface magnetic field at quench was well above Hc1, showing that it is not a limiting field in these cavities. The coating with the best performance had a quench field of 17 MV/m, exceeding gradient requirements for state-of-the-art high duty factor SRF accelerators. It is also shown that—taking into account the thermodynamic efficiency of the cryogenic plant—the 4.2 K Q0 values obtained meet the AC power consumption requirements of state-of-the-art high duty factor accelerators, making this a proof-of-principle demonstration for Nb3Sn cavities in future applications.
Child-Langmuir flow with periodically varying anode voltage
Authors: Rokhlenko A.
Published: February 2015

Using the Lagrangian technique, we study settled Child-Langmuir flows in a one dimensional planar diodes whose anode voltages periodically vary around given positive values. Our goal is to find analytically if the average currents in these systems can exceed the famous Child-Langmuir limit found for the stationary current a long time ago. The main result of our study is that in a periodic quasi-stationary regime the average current can be larger than the Child-Langmuir maximum even by 50% compared with its adiabatic average value. The cathode current in this case has the form of rectangular pulses which are formed by a very special triangular voltage modulation. This regime, i.e., periodicity, shape of pulses, and their amplitude, needs to be carefully chosen for the best performance.
Plasmonic ultra-broadband polarizers based on Ag nano wire-slit arrays
Authors: Han Chunrui , Tam Wing Yim
Published: February 2015

We propose ultra-broadband reflective and absorptive polarizers in the visible range using multi-scaled Ag nano wire-slit arrays. The nano arrays can be tuned from reflective to absorptive by incorporating Ag wires/strips with different lengths/widths. The ultra-broadband nature of the absorptive array, with averaged absorption as high as ∼80%, is due to collective excitations of plasmonic resonances in the Ag wires/strips with different length scales. The nano arrays are realized experimentally by using a simple two-times shadowing vapor deposition method. They exhibit broadband transmission difference, in good agreement with simulations. Our multi-scaled nano array design has potential applications as broadband linear polarizers and anti-reflective materials in both optics and photovoltaics.
Reduction of heat capacity and phonon group velocity in silicon nanowires
Authors: Marchbanks Christopher , Wu Zhigang
Published: February 2015

We report on ab initio linear-response calculations of lattice vibrations in narrow silicon nanowires on the order of 1 nm along the [001], [011], and [111] growth directions. The confinement and nanowire structure substantially alter phonon distributions, resulting in an 15% to 23% reduction in heat capacity and an averaged decrease of 31% in acoustic velocities compared with bulk silicon. Based on these, we estimate an improvement up to 4 fold on thermoelectric performance due solely to the modified lattice vibrations in narrow silicon nanowires over bulk silicon.
Imaging nanowire plasmon modes with two-photon polymerization
Authors: Gruber Christian , Hirzer Andreas , Schmidt Volker , Trügler Andreas , Hohenester Ulrich , Ditlbacher Harald , Hohenau Andreas , Krenn Joachim R.
Published: February 2015

Metal nanowires sustain propagating surface plasmons that are strongly confined to the wire surface. Plasmon reflection at the wire end faces and interference lead to standing plasmon modes. We demonstrate that these modes can be imaged via two-photon (plasmon) polymerization of a thin film resist covering the wires and subsequent electron microscopy. Thereby, the plasmon wavelength and the phase shift of the nanowire mode picked up upon reflection can be directly retrieved. In general terms, polymerization imaging is a promising tool for the imaging of propagating plasmon modes from the nano- to micro-scale.
Three dimensional passivated-electrode insulator-based dielectrophoresis
Authors: Nakidde Diana , Zellner Phillip , Alemi Mohammad Mehdi , Shake Tyler , Hosseini Yahya , Riquelme Maria V. , Pruden Amy , Agah Masoud
Published: February 2015

In this study, a 3D passivated-electrode, insulator-based dielectrophoresis microchip (3D πDEP) is presented. This technology combines the benefits of electrode-based DEP, insulator-based DEP, and three dimensional insulating features with the goal of improving trapping efficiency of biological species at low applied signals and fostering wide frequency range operation of the microfluidic device. The 3D πDEP chips were fabricated by making 3D structures in silicon using reactive ion etching. The reusable electrodes are deposited on second glass substrate and then aligned to the microfluidic channel to capacitively couple the electric signal through a 100 μm glass slide. The 3D insulating structures generate high electric field gradients, which ultimately increases the DEP force. To demonstrate the capabilities of 3D πDEP, Staphylococcus aureus was trapped from water samples under varied electrical environments. Trapping efficiencies of 100% were obtained at flow rates as high as 350 μl/h and 70% at flow rates as high as 750 μl/h. Additionally, for live bacteria samples, 100% trapping was demonstrated over a wide frequency range from 50 to 400 kHz with an amplitude applied signal of 200 Vpp. 20% trapping of bacteria was observed at applied voltages as low as 50 Vpp. We demonstrate selective trapping of live and dead bacteria at frequencies ranging from 30 to 60 kHz at 400 Vpp with over 90% of the live bacteria trapped while most of the dead bacteria escape.
Enhancement of spin-Seebeck effect by inserting ultra-thin Fe70Cu30 interlayer
Authors: Kikuchi D. , Ishida M. , Uchida K. , Qiu Z. , Murakami T. , Saitoh E.
Published: February 2015

We report the longitudinal spin-Seebeck effects (LSSEs) for Pt/Fe70Cu30/BiY2Fe5O12 (BiYIG) and Pt/BiYIG devices. The LSSE voltage was found to be enhanced by inserting an ultra-thin Fe70Cu30 interlayer. This enhancement decays sharply with increasing the Fe70Cu30 thickness, suggesting that it is not due to bulk phenomena, such as a superposition of conventional thermoelectric effects, but due to interface effects related to the Fe70Cu30 interlayer. Combined with control experiments using Pt/Fe70Cu30 devices, we conclude that the enhancement of the LSSE voltage in the Pt/Fe70Cu30/BiYIG devices is attributed to the improvement of the spin-mixing conductance at the Pt/BiYIG interfaces.
First-principles study on the effect of SiO2 layers during oxidation of 4H-SiC
Authors: Ono Tomoya , Saito Shoichiro
Published: February 2015

The effect of SiO2 layers during the thermal oxidation of a 4H-SiC(0001) substrate is examined by performing the first-principles total-energy calculations. Although it is expected that a CO molecule is the most preferable product during the oxidation, CO2 molecules are mainly emitted from the SiC surface at the initial stage of the oxidation. As the oxidation proceeds, CO2 emission becomes less favorable and CO molecules are emitted from the interface. We conclude that the interface stress due to the lattice constant mismatch between 4H-SiC(0001) and SiO2 is responsible for the removal of C during the oxidation, resulting in the characteristic electronic property of the interface fabricated by the thermal oxidation.
Electrical controlled magnetism in FePt film with the coexistence of two phases
Authors: Yang Y. T. , Wen J. H. , Xiong Y. Q. , Ma L. , Lv L. Y. , Cao Q. Q. , Wang D. H. , Du Y. W.
Published: February 2015

A series of FePt films with different magnetic structures are deposited on Pb(Mg1/3Nb2/3)O3–PbTiO3 substrates. By applying an electric field across the piezoelectric single crystal substrate, an magnetoelectric effect is observed in FePt/Pb(Mg1/3Nb2/3)O3–PbTiO3 heterostructure due to the phase transformation between face-centered cubic and face-centered tetragonal phases in the film. Taking advantage of the different coercivity caused by the electric field, the sign of magnetization can be manipulated reversibly at room temperature with the electric field switching on or off. Based on this experimental result, we demonstrate a model for the technology of information storage, in which data can be written electrically without false writing.
Noise suppression in curved glass shells using macro-fiber-composite actuators studied by the means of digital holography and acoustic measurements
Authors: Mokrý P. , Psota P. , Steiger K. , Václavík J. , Doleček R. , Lédl V. , Šulc M.
Published: February 2015

The paper presents methods and experimental results of the semi-active control of noise transmission in a curved glass shell with attached piezoelectric macro fiber composite (MFC) actuators. The semi-active noise control is achieved via active elasticity control of piezoelectric actuators by connecting them to an active electric shunt circuit that has a negative effective capacitance. Using this approach, it is possible to suppress the vibration of the glass shell in the normal direction with respect to its surface and to increase the acoustic transmission loss of the piezoelectric MFC-glass composite structure. The effect of the MFC actuators connected to the negative capacitance shunt circuit on the surface distribution of the normal vibration amplitude is studied using frequency-shifted digital holography (FSDH). The principle of the used FSDH method is described in the paper. The frequency dependence of the acoustic transmission loss through the piezoelectric MFC-glass composite structure is estimated using measurements of the specific acoustic impedance of the curved glass shell. The specific acoustic impedance is measured using two microphones and a laser Doppler vibrometer (LDV). The results from the LDV measurements are compared with the FSDH data. The results of the experiments show that using this approach, the acoustic transmission loss in a glass shell can be increased by 36 dB in the frequency range around 247 Hz and by 25 dB in the frequency range around 258 Hz. The experiments indicate that FSDH measurements provide an efficient tool that can be used for fast and accurate measurements of the acoustic transmission loss in large planar structures.
Role of the GP liaison nurse in a community health program to improve integration and coordination of services for the chronically ill
Authors: McNab Justin , Paterson Janis , Fernyhough Joanne , Hughes Rod
Published: February 2015

This paper explores the role of the General Practitioner Liaison Nurse (GPLN) in improving integration and coordination of services within Primary Health Care. This position can play a major role in care coordination and cultural change. The GPLN within HealthOne Mt Druitt (HOMD) identifies patients’ needs and facilitates communication, case conferencing and care coordination between health and other providers. The priority areas of children and their families at risk or with significant unmet needs, and chronic aged and complex care, were identified as target areas. This paper focuses on the GPLN within the chronic aged and complex care service model. The GPLN within HOMD was able to improve coordination and integration of services for patients of the facility. Activities included organising multidisciplinary services and addressing psychosocial issues. Patients and community health staff identified the importance of the role for improving coordination and integration of services. Decision and policy makers saw the position as vital to the implementation, operation and sustainability of HOMD.
Primary health-care responses to methamphetamine use in Australian Indigenous communities
Authors: MacLean Sarah , Harney Angela , Arabena Kerry
Published: February 2015

Crystal methamphetamine (commonly known as ‘ice’) use is currently a deeply concerning problem for some Australian Indigenous peoples and can cause serious harms to individual, families and communities. This paper is intended to support best practice responses by primary health-care staff working with Australian Indigenous people who use methamphetamine. It draws on a systematic search of relevant databases to identify literature from January 1999 to February 2014, providing an overview of prevalence, treatment, education and harm reduction, and community responses. The prevalence of methamphetamine use is higher in Indigenous than non-Indigenous communities, particularly in urban and regional settings. No evidence was identified that specifically related to effective treatment and treatment outcomes for Indigenous Australians experiencing methamphetamine dependence or problematic use. While studies involving methamphetamine users in the mainstream population suggest that psychological and residential treatments show short-term promise, longer-term outcomes are less clear. Community-driven interventions involving Indigenous populations in Australia and internationally appear to have a high level of community acceptability; however, outcomes in terms of methamphetamine use are rarely evaluated. Improved national data on prevalence of methamphetamine use among Indigenous people and levels of treatment access would support service planning. We argue for the importance of a strength-based approach to addressing methamphetamine use, to counteract the stigma and despair that frequently accompanies it.
Transitioning to routine breast cancer risk assessment and management in primary care: what can we learn from cardiovascular disease?
Authors: Phillips Kelly-Anne , Steel Emma J. , Collins Ian , Emery Jon , Pirotta Marie , Mann G. Bruce , Butow Phyllis , Hopper John L. , Trainer Alison , Moreton Jane , Antoniou Antonis C. , Cuzick Jack , Keogh Louise
Published: February 2015

To capitalise on advances in breast cancer prevention, all women would need to have their breast cancer risk formally assessed. With ~85% of Australians attending primary care clinics at least once a year, primary care is an opportune location for formal breast cancer risk assessment and management. This study assessed the current practice and needs of primary care clinicians regarding assessment and management of breast cancer risk. Two facilitated focus group discussions were held with 17 primary care clinicians (12 GPs and 5 practice nurses (PNs)) as part of a larger needs assessment. Primary care clinicians viewed assessment and management of cardiovascular risk as an intrinsic, expected part of their role, often triggered by practice software prompts and facilitated by use of an online tool. Conversely, assessment of breast cancer risk was not routine and was generally patient- (not clinician-) initiated, and risk management (apart from routine screening) was considered outside the primary care domain. Clinicians suggested that routine assessment and management of breast cancer risk might be achieved if it were widely endorsed as within the remit of primary care and supported by an online risk-assessment and decision aid tool that was integrated into primary care software. This study identified several key issues that would need to be addressed to facilitate the transition to routine assessment and management of breast cancer risk in primary care, based largely on the model used for cardiovascular disease.