bluuebunny/crossref_metadata_2025 huggingface dataset:
Unveiling Cerebral Leishmaniasis: parasites and brain inflammation in Leishmania donovani infected mice
Authors: Melo Guilherme D. , Goyard Sophie , Fiette Laurence , Boissonnas Alexandre , Combadiere Christophe , Machado Gisele F. , Minoprio Paola , Lang Thierry
Published: August 2017

Visceral leishmaniasis (VL) is a systemic disease with multifaceted clinical manifestations, including neurological signs, however, the involvement of the nervous system during VL is underestimated. Accordingly, we investigated both brain infection and inflammation in a mouse model of VL. Using bioluminescentLeishmania donovaniand real-time 2D-3D imaging tools, we strikingly detected live parasites in the brain, where we observed a compartmentalized dual-phased inflammation pattern: an early phase during the first two weeks post-infection, with the prompt arrival of neutrophils and Ly6Chighmacrophages in an environment presenting a variety of pro-inflammatory mediators (IFN-γ, IL-1β, CXCL-10/CXCR-3, CCL-7/CCR-2), but with an intense anti-inflammatory response, led by IL-10; and a re-inflammation phase three months later, extremely pro-inflammatory, with novel upregulation of mediators, including IL-1β, TNF-α and MMP-9. These new data give support and corroborate previous studies connecting human and canine VL with neuroinflammation and blood-brain barrier disruption, and conclusively place the brain among the organs affected by this parasite. Altogether, our results provide convincing evidences thatLeishmania donovaniindeed infects and inflames the brain.
Preparation of CH3NH3PbI3 thin films with tens of micrometer scale at high temperature
Authors: Zhang Hao , Tao Mian , Gao Baizhi , Chen Wei , Li Qi , Xu Qingyu , Dong Shuai
Published: August 2017

The fabrication of high-quality organic-inorganic hybrid halide perovskite layers is the key prerequisite for the realization of high efficient photon energy harvest and electric energy conversion in their related solar cells. In this article, we report a novel fabrication technique of CH3NH3PbI3 layers based on high temperature chemical vapor reaction. CH3NH3PbI3 layers have been prepared by the reaction of PbI2 films which were deposited by pulsed laser deposition, with CH3NH3I vapor at various temperatures from 160 °C to 210 °C. X-ray diffraction patterns confirm the formation of pure phase, and photoluminescence spectra show the strong peak at around 760 nm. Scanning electron microscopy images confirm the significantly increased average grain size from nearly 1 μm at low reaction temperature of 160 °C to more than 10 μm at high reaction temperature of 200 °C. The solar cells were fabricated, and short-circuit current density of 15.75 mA/cm2, open-circuit voltage of 0.49 V and fill factor of 71.66% have been obtained.
Titanium nanoparticles (TiO2)/graphene oxide nanosheets (GO): an electrochemical sensing platform for the sensitive and simultaneous determination of benzocaine in the presence of antipyrine
Authors: Mohamed Mona A. , Atty Shimaa A. , Merey Hanan A. , Fattah Taghreed A. , Foster Christopher W. , Banks Craig E.
Published: August 2017

An effective electrochemical sensing platform for the simultaneous determination of benzocaine (BEN) and antipyrine (ANT).
Spatial differentiation of Brønsted acid sites by probe molecule in zeolite USY using synchrotron X-ray powder diffraction
Authors: Ye Lin , Teixeira Ivo , Lo Benedict T. W. , Zhao Pu , Edman Tsang S. C.
Published: August 2017

A direct correlation of extra-framework Al3+ in a sodalite cage (HY) with the enhanced Brønsted acid site evaluated by synchrotron X-ray powder diffraction, Rietveld refinement and the use of a pyridine probe molecule.
Migratory insertion and hydrogenation of a bridging azide in a thiolate-bridged dicobalt reaction platform
Authors: Zhang Yixin , Tong Peng , Yang Dawei , Li Jianzhe , Wang Baomin , Qu Jingping
Published: August 2017

A thiolate-bridged dicobalt azide can undergo both N-migratory insertion upon thermolysis and hydrogenation by H2.
C(sp3)–F, C(sp2)–F and C(sp3)–H bond activation at silicon(ii) centers
Authors: Swamy V. S. V. S. N. , Parvin Nasrina , Vipin Raj K. , Vanka Kumar , Sen Sakya S.
Published: August 2017

Silylene, [PhC(NtBu)2SiN(SiMe3)2] (1) underwent C(sp3)–F, C(sp2)–F and C(sp3)–H bond activation with trifluoroacetophenone, octafluorotoluene, and acetophenone, respectively, under ambient conditions.
Deciphering the photosensitization mechanisms of hypericin towards biological membranes
Authors: Gattuso Hugo , Marazzi Marco , Dehez François , Monari Antonio
Published: August 2017

Molecular modeling and simulation allow unravelling the molecular basis of the photosensitization of biological membranes by the hypericin drug used in photodynamic therapy.
Self-assembly of a nanotube from a black phosphorus nanoribbon on a string of fullerenes at low temperature
Authors: Cai Kun , Shi Jiao , Liu Ling-Nan , Qin Qing-Hua
Published: August 2017

A string of fullerenes is used for generating a nanotube by self-assembly of a black phosphorus (BP) nanoribbon at a temperature of 8 K.
Extending charge separation lifetime and distance in patterned dye-sensitized SnO2–TiO2 μm-thin films
Authors: Saavedra Becerril Valeria , Sundin Elin , Mapar Mokhtar , Abrahamsson Maria
Published: August 2017

Charge separation in dye sensitized SnO2–TiO2 μm-thin films was substantially extended by an innovative patterning design strategy.
Kinetics and dynamics of the C(3P) + H2O reaction on a full-dimensional accurate triplet state potential energy surface
Authors: Li Jun , Xie Changjian , Guo Hua
Published: August 2017

A full-dimensional accurate PES for the C(3P) + H2O reaction is developed using the PIP-NN method.
Structural variations in (CuL)2Ln complexes of a series of lanthanide ions with a salen-type unsymmetrical Schiff base(H2L): Dy and Tb derivatives as potential single-molecule magnets
Authors: Mahapatra Prithwish , Ghosh Soumavo , Koizumi Naoki , Kanetomo Takuya , Ishida Takayuki , Drew Michael G. B. , Ghosh Ashutosh
Published: August 2017

Five heterometallic Cu2Ln complexes (Ln = Gd, Tb, Dy, Ho and Er) have been synthesized using asymmetric Schiff base ligand. Among these, Cu2Tb and Cu2Dy complexes show field induced SMM behaviour.
Crystalline nickel manganese antimonate as a stable water-oxidation catalyst in aqueous 1.0 M H2SO4
Authors: Moreno-Hernandez Ivan A. , MacFarland Clara A. , Read Carlos G. , Papadantonakis Kimberly M. , Brunschwig Bruce S. , Lewis Nathan S.
Published: August 2017

NixMn1−xSb1.6−1.8Oy acts as a stable OER electrocatalyst for >168 h of operation in 1.0 M sulfuric acid.
Isosorbide synthesis from cellulose with an efficient and recyclable ruthenium catalyst
Authors: Keskiväli Juha , Rautiainen Sari , Heikkilä Mikko , Myllymäki Teemu T. T. , Karjalainen Jaakko-Pekka , Lagerblom Kalle , Kemell Marianna , Vehkamäki Marko , Meinander Kristoffer , Repo Timo
Published: August 2017

A recyclable Ru-based hydrogenation catalyst for the two-step conversion of lignocellulosic substrates into isosorbide.
Magnetic particles assisted capture and release of rare circulating tumor cells using wavy-herringbone structured microfluidic devices
Authors: Shi Wentao , Wang Shunqiang , Maarouf Ahmad , Uhl Christopher G. , He Ran , Yunus Doruk , Liu Yaling
Published: August 2017

Wavy-herringbone structured microfluidic devices promote capture and collection of rare tumor cells assisted by magnetic particles.
Tissue chips – innovative tools for drug development and disease modeling
Authors: Low L. A. , Tagle D. A.
Published: August 2017

The high rate of failure during drug development is well-known, however recent advances in tissue engineering and microfabrication have contributed to the development of microphysiological systems (MPS), or ‘organs-on-chips’ that recapitulate the function of human organs.
Microfluidics for exosome isolation and analysis: enabling liquid biopsy for personalized medicine
Authors: Contreras-Naranjo Jose C. , Wu Hung-Jen , Ugaz Victor M.
Published: August 2017

Breakthroughs in adapting microfluidic systems for exosome isolation, detection, and analysis are providing new tools to revolutionize personalized medicine.
Microparticle parking and isolation for highly sensitive microRNA detection
Authors: Kim Jae Jung , Chen Lynna , Doyle Patrick S.
Published: August 2017

We demonstrate a microfluidic platform that immobilizes hydrogel microparticles at defined locations, and encapsulates particles in monodisperse droplets for sensitive bioassays.
Fluorescence activated cell sorting via a focused traveling surface acoustic beam
Authors: Ma Zhichao , Zhou Yinning , Collins David J. , Ai Ye
Published: August 2017

Fluorescence activated sorting at the single cell level using a highly focused traveling surface acoustic wave beam (∼50 μm).
Ruthenium(ii) arene complexes showing DNA photobinding: the role of the basicity of the monodentate ligand
Authors: Chen Yongjie , Luo Xiaohe , Bai Lijuan , Hu Xuelian , Zhou Jing , Zhang Pu , Yu Yu
Published: August 2017

With a decrease in the basicity of the monodentate ligand X, the ligand photodissociation efficiencies of the complexes increase gradually.
Perylene diimide-based organic π-motif for differentiating CN− and F− ions by electron-transfer and desilylation mechanisms: applications to complex logic circuits
Authors: Singh Prabhpreet , Mittal Lalit Singh , Singh Harminder , Bhargava Gaurav , Kumar Subodh
Published: August 2017

PDI-SiHQ undergoes electron-transfer and desilylation reactions with CN− and F− ions to differentiate basic anions.
Exfoliated BN shell-based high-frequency magnetic core–shell materials
Authors: Zhang Wei , Patel Ketan , Ren Shenqiang
Published: August 2017

The miniaturization of electric machines demands high frequency magnetic materials with large magnetic-flux density and low energy loss to achieve a decreased dimension of high rotational speed motors.
Palladium-catalyzed allylic amination: a powerful tool for the enantioselective synthesis of acyclic nucleoside phosphonates
Authors: Azzouz Mariam , Soriano Sébastien , Escudero-Casao Margarita , Matheu M. Isabel , Castillón Sergio , Díaz Yolanda
Published: August 2017

Acyclic nucleoside phosphonate were prepared in high yield and up to 92% ee using an enantioselective palladium-catalyzed allylic substitution.
Aerobic thiyl radical addition/cyclization of N-methacryloyl benzamides for the synthesis of isoquinoline-1,3(2H,4H)-dione derivatives
Authors: Yuan Yan-qin , Kumar Pailla Santhosh , Zhang Chun-niu , Yang Ming-hua , Guo Sheng-rong
Published: August 2017

A highly effective dioxygen-triggered oxidative thiyl radical addition/cyclization of N-methacryloylbenzamides was explored. This method provides convenient access to a variety of useful sulfide-containing 4,4-disubstituted isoquinoline-1,3-diones.
(Co)polymers containing boron difluoride 3-cyanoformazanate complexes: emission enhancement via random copolymerization
Authors: Novoa Samantha , Gilroy Joe B.
Published: August 2017

Synthesis and photophysical characterization of (co)polymers containing an asymmetrically substituted BF2complex of a 3-cyanoformazanate ligand are reported.
Hierarchical porous ZnMn2O4microspheres assembled by nanosheets for high performance anodes of lithium ion batteries
Authors: Zeng Junsong , Ren Yanbiao , Wang Shengbin , Hao Yu , Wu Hao , Zhang Shichao , Xing Yalan
Published: August 2017

Hierarchical porous ZnMn2O4microspheres assembled by nanosheets are fabricated and they exhibit outstanding electrochemical performance for lithium-ion battery anodes.
An autonomous electrochemically-actuated microvalve for controlled transport in stand-alone microfluidic systems
Authors: Watanabe T. , Biswas G. C. , Carlen E. T. , Suzuki H.
Published: August 2017

An autonomous stand-alone microfluidic system using an electrochemically-actuated microvalve based on a single bi-metallic Zn/Pt electrode.
Correction: A miniaturised 3D printed polypropylene reactor for online reaction analysis by mass spectrometry
Authors: Scotti Gianmario , Nilsson Sofia M. E. , Haapala Markus , Pöhö Päivi , Boije af Gennäs Gustav , Yli-Kauhaluoma Jari , Kotiaho Tapio
Published: August 2017

Correction for ‘A miniaturised 3D printed polypropylene reactor for online reaction analysis by mass spectrometry’ by Gianmario Scotti et al., React. Chem. Eng., 2017, 2, 299–303.
Bistable curvature potential at hyperbolic points of nematic shells
Authors: Sonnet André M. , Virga Epifanio G.
Published: August 2017

At hyperbolic points, where the Gaussian curvature is negative, nematic shells with unequal elastic constants can exhibit two preferred alignments.
Möglichkeiten der universitären Einflussnahme auf die globale Preisgestaltung von Medikamenten
Authors: Jaehn Philipp , Inhoffen Johannes , Scheer Jana , Streicher Felix , Gesine Huhn Anna , Lance Christopher
Published: August 2017

Menschen in Ländern des globalen Südens sind einerseits von einem eigenen Spektrum an Krankheiten betroffen, andererseits stellen die Gesundheitskosten im Kontext der vorherrschenden Armut eine erhebliche Belastung dar. In diesen Ländern spielen außerdem auch nicht-übertragbare Krankheiten eine immer größere Rolle. Medikamentenforschung in Deutschland und die Preisgestaltung der Endprodukte rücken daher in einen globalen Kontext. Universitäten haben diesbezüglich aus 2 Gründen eine besondere Verantwortung. Erstens tragen sie zu einem nicht unerheblichen Teil, insbesondere durch geleistete Grundlagenforschung, zur Entwicklung neuer Medikamente bei. Zweitens ist die Universität eine gemeinnützige Institution und hat als solche die Verantwortung, neu erworbenes Wissen an die Öffentlichkeit zurückzugeben. Von der öffentlichen Gemeinschaft mitfinanzierte Innovationen sollten deshalb so verwertet werden, dass finanziell benachteiligte Individuen und Bevölkerungen weltweit Zugang dazu haben. Als ersten konkreten Schritt in diese Richtung fordern wir die Einführung einer global verantwortlichen Lizenzpolitik an deutschen Universitäten. Verschiedene Mechanismen unter dem Sammelbegriff „Equitable Licensing“ bieten eine Grundlage zur Realisierung dieses ambitionierten Vorhabens, wie es bereits von den Universitäten Tübingen, Münster und Freiburg praktiziert wird.
Anatomy of an innovation in IT service
Authors: Ghoshal Sankar , Roy Rahul Kumar
Published: August 2017

The case study covers aspects of service innovation in the IT services sector. The client Nordics is a global telecommunication major. They have a large and diverse set of IT business applications, most of which is on SAP applications. The subject of the case study is that of SAP Releases, the service of enhancing and creating new business functionalities in the existing business applications. The case is seen from the perspective of the Program Manager of the SAP Release service. This service is delivered by the IT Services major AVON. The case study covers the full lifecycle of the innovation in service, from the identification of the need, conceptualization and creation of the service offering up till pilot execution. The important aspects of innovation in the revenue model and service delivery model are also covered. The case can be analyzed from two perspectives, as a detailed lifecycle of a major innovation in service or as a requirement of dynamic capabilities in the IT service provider organization, to bring about that innovation.
High field electron transport in indium gallium nitride and indium aluminium nitride
Authors: Masyukov N. A. , Dmitriev A. V.
Published: August 2017

In this paper, we study theoretically the hot electron transport in two nitride semiconductor solid solutions, InxGa1−xN and InxAl1−xN, in the electric fields up to 30 kV/cm. We calculate the electron drift velocity field dependence at 77 and 300 K for the bulk samples with the electron concentration of 1 × 1018 and 1 × 1019 cm−3 and alloy composition x = 0, 0.25, 0.5, 0.75, and 1.
On-chip, high-sensitivity temperature sensors based on dye-doped solid-state polymer microring lasers
Authors: Wan Lei , Chandrahalim Hengky , Chen Cong , Chen Qiushu , Mei Ting , Oki Yuji , Nishimura Naoya , Guo L. Jay , Fan Xudong
Published: August 2017

We developed a chip-scale temperature sensor with a high sensitivity of 228.6 pm/°C based on a rhodamine 6G (R6G)-doped SU-8 whispering gallery mode microring laser. The optical mode was largely distributed in a polymer core layer with a 30 μm height that provided detection sensitivity, and the chemically robust fused-silica microring resonator host platform guaranteed its versatility for investigating different functional polymer materials with different refractive indices. As a proof of concept, a dye-doped hyperbranched polymer (TZ-001) microring laser-based temperature sensor was simultaneously developed on the same host wafer and characterized using a free-space optics measurement setup. Compared to TZ-001, the SU-8 polymer microring laser had a lower lasing threshold and a better photostability. The R6G-doped SU-8 polymer microring laser demonstrated greater adaptability as a high-performance temperature-sensing element. In addition to the sensitivity, the temperature resolutions for the laser-based sensors were also estimated to be 0.13 °C and 0.35 °C, respectively. The rapid and simple implementation of micrometer-sized temperature sensors that operate in the range of 31 – 43 °C enables their potential application in thermometry.
TinyLev: A multi-emitter single-axis acoustic levitator
Authors: Marzo Asier , Barnes Adrian , Drinkwater Bruce W.
Published: August 2017

Acoustic levitation has the potential to enable novel studies due to its ability to hold a wide variety of substances against gravity under container-less conditions. It has found application in spectroscopy, chemistry, and the study of organisms in microgravity. Current levitators are constructed using Langevin horns that need to be manufactured to high tolerance with carefully matched resonant frequencies. This resonance condition is hard to maintain as their temperature changes due to transduction heating. In addition, Langevin horns are required to operate at high voltages (>100 V) which may cause problems in challenging experimental environments. Here, we design, build, and evaluate a single-axis levitator based on multiple, low-voltage (ca. 20 V), well-matched, and commercially available ultrasonic transducers. The levitator operates at 40 kHz in air and can trap objects above 2.2 g/cm3 density and 4 mm in diameter whilst consuming 10 W of input power. Levitation of water, fused-silica spheres, small insects, and electronic components is demonstrated. The device is constructed from low-cost off-the-shelf components and is easily assembled using 3D printed sections. Complete instructions and a part list are provided on how to assemble the levitator.
Phase-locked array of quantum cascade lasers with an intracavity spatial filter
Authors: Jia Zhiwei , Wang Lei , Zhang Jinchuan , Zhao Yue , Liu Chuanwei , Zhai Shenqiang , Zhuo Ning , Liu JunQi , Wang LiJun , Liu ShuMan , Liu Fengqi , Wang Zhanguo
Published: August 2017

We show a phase-locked array of quantum cascade lasers with an intracavity spatial filter based on the Talbot effect. All the laser arrays show in-phase operation from the threshold current to full power current with a near-diffraction-limited divergence angle. The maximum power is just about 5 times that of a single-ridge laser for an eleven-laser array device and 3 times for a seven-laser array device. The structure was analyzed by using the multi-slit Fraunhofer diffraction theory, showing very good agreement with the experimental results. Considering the great modal selection ability, simple fabricating process, and potential for achieving continuous wave operation, this phase-locked array may be a hopeful solution to obtain higher coherent power.
EUV stimulated emission from MgO pumped by FEL pulses
Authors: Jonnard Philippe , André Jean-Michel , Le Guen Karine , Wu Meiyi , Principi Emiliano , Simoncig Alberto , Gessini Alessandro , Mincigrucci Riccardo , Masciovecchio Claudio , Peyrusse Olivier
Published: August 2017

Stimulated emission is a fundamental process in nature that deserves to be investigated and understood in the extreme ultra-violet (EUV) and x-ray regimes. Today, this is definitely possible through high energy density free electron laser (FEL) beams. In this context, we give evidence for soft-x-ray stimulated emission from a magnesium oxide solid target pumped by EUV FEL pulses formed in the regime of travelling-wave amplified spontaneous emission in backward geometry. Our results combine two effects separately reported in previous works: emission in a privileged direction and existence of a material-dependent threshold for the stimulated emission. We develop a novel theoretical framework, based on coupled rate and transport equations taking into account the solid-density plasma state of the target. Our model accounts for both observed mechanisms that are the privileged direction for the stimulated emission of the Mg L2,3 characteristic emission and the pumping threshold.
Preliminary investigation on the radiation transfer in dynamic hohlraums on the PTS facility
Authors: Xiao Delong , Ye Fan , Meng Shijian , Ning Jiamin , Qin Yi , Hu Qingyuan , Huang Zhanchang , Yang Jianlun , Chen Faxin , Jiang Shuqing , Ding Ning , Xu Rongkun , Xue Chuang , Zhang Yang , Sun Shunkai , Shu Xiaojian
Published: August 2017

The radiation transfer in dynamic hohlraums on the PTS facility is preliminarily investigated in this paper. Simulation results show that as the accelerated wire-array plasma impacts onto the foam converter, energy thermalization takes place in a local interaction region near the boundary of the wire-array plasma and the foam converter, and then, high temperature radiation is gradually generated. Its transfer process largely depends on the radiation temperature and the mass density of the converter. When the mass ratio of the wire-array to the converter is near 1.0, the radiation temperature can be increased to about 120 eV with the PTS drive current. In this case, the radiation generated from the interaction region will quickly transfer to the center of the converter. The experimental end-on x-ray images present the overall process of radiation production and transfer of this kind of dynamic hohlraum. As the mass ratio is decreased, the radiation temperature will also be deceased, and the converter will become more opaque to the radiation. In the case of extremely low mass ratios such as lower than 0.3, the peak radiation temperature will be much lower than 100 eV, and the radiation transfers slowly to the interior of the converter and presents large non-uniformity, which is also observed in experiments on the PTS facility.
Effects of quantum statistical pressure on the Washimi-Karpman magnetization and power radiation in degenerate quantum Fermi-Dirac plasmas
Authors: Lee Myoung-Jae , Jung Young-Dae
Published: August 2017

The physical properties of the Washimi-Karpman ponderomotive magnetization are investigated in relativistically degenerate quantum Fermi-Dirac plasmas including the influence of quantum statistical degeneracy pressure. The induced magnetization and power radiation due to the Washimi-Karpman ponderomotive interaction are obtained in Fermi-Dirac plasmas. It is found that the ponderomotive magnetization decreases with an increase of the relativistic degeneracy parameter. It is also shown that the quantum statistical degeneracy pressure effect is more significant in small frequency and large wave number domains than that in large frequency and small wave number domains. In addition, it is found that the ponderomotive power radiation decreases with an increase of the relativistic degeneracy parameter in Fermi-Dirac plasmas. The variations of the Washimi-Karpman magnetization and power radiation due to the physical characteristics of degenerate quantum Fermi-Dirac plasmas are also discussed.
Comprehensive magnetohydrodynamic hybrid simulations of fast ion driven instabilities in a Large Helical Device experiment
Authors: Todo Y. , Seki R. , Spong D. A. , Wang H. , Suzuki Y. , Yamamoto S. , Nakajima N. , Osakabe M.
Published: August 2017

Alfvén eigenmodes (AEs) destabilized by the neutral beam injection (NBI) in a Large Helical Device experiment are investigated using multi-phase magnetohydrodynamic (MHD) hybrid simulation, which is a combination of classical and MHD hybrid simulations for fast ions. The fast ion distribution is simulated with NBI, collisions, and losses in the equilibrium magnetic field in the classical simulation, while the MHD hybrid simulation takes account of the interaction between fast ions and an MHD fluid, in addition to the classical dynamics. It is found in the multi-phase hybrid simulation that the stored fast ion energy is saturated due to the interaction with AEs at a lower level than that of the classical simulation. Two groups of AEs with frequencies close to those observed in the experiment are destabilized alternately at each hybrid simulation. Firstly destabilized are two toroidal Alfvén eigenmodes whose frequency is close to the local minimum of the upper Alfvén continuous spectrum. Secondly destabilized is a global Alfvén eigenmode whose frequency is located well inside the Alfvén continuous spectrum gap. In addition, two AEs whose frequencies are close to that of the ellipticity-induced Alfvén eigenmode are observed with a lower amplitude. When the hybrid simulation is run continuously, the interchange mode grows more slowly than the AEs, but becomes dominant in the long time scale. The interchange mode oscillates with a constant amplitude and a frequency of ∼1 kHz. The interchange mode reduces the stored fast ion energy to a lower level than that of the AEs.
Photo-induced droop in blue to red light emitting InGaN/GaN single quantum wells structures
Authors: Ngo Thi Huong , Gil Bernard , Damilano Benjamin , Valvin Pierre , Courville Aimeric , de Mierry Philippe
Published: August 2017

The variation of the internal quantum efficiency (IQE) of single InGaN quantum well structures emitting from blue to red is studied as a function of the excitation power density and the temperature. By changing the well width, the indium content, and adding a strain compensation AlGaN layer, we could tune the intrinsic radiative recombination rate by changing the quantum confined Stark effect, and we could modify the carrier localization. Strong quantum confined Stark effect and carrier localization induce an increase in the carrier density and then favor Auger non-radiative recombination in the high excitation range. In such high excitation conditions with efficient Auger recombination, the variation of the IQE with the photo-excitation density P is ruled by a universal power law independent of the design: IQE = IQEMAX – a log10P with a close to 1/3. The temperature dependences of the different recombination mechanisms are determined. At low temperature, both quantum confined Stark effect and carrier localization trigger electron-electron repulsions and therefore the onset of the Auger effect. The increase in the value of coefficient C with changing temperature reveals indirect Auger recombination that relates to the interactions of the carriers with other phonons than the longitudinal optical one.
First-principles molecular dynamics study of deuterium diffusion in liquid tin
Authors: Liu Xiaohui , Zheng Daye , Ren Xinguo , He Lixin , Chen Mohan
Published: August 2017

Understanding the retention of hydrogen isotopes in liquid metals, such as lithium and tin, is of great importance in designing a liquid plasma-facing component in fusion reactors. However, experimental diffusivity data of hydrogen isotopes in liquid metals are still limited or controversial. We employ first-principles molecular dynamics simulations to predict diffusion coefficients of deuterium in liquid tin at temperatures ranging from 573 to 1673 K. Our simulations indicate faster diffusion of deuterium in liquid tin than the self-diffusivity of tin. In addition, we find that the structural and dynamic properties of tin are insensitive to the inserted deuterium at temperatures and concentrations considered. We also observe that tin and deuterium do not form stable solid compounds. These predicted results from simulations enable us to have a better understanding of the retention of hydrogen isotopes in liquid tin.
Equilibrium potential well due to finite Larmor radius effects at the tokamak edge
Authors: Lee W. W. , White R. B.
Published: August 2017

We present a novel mechanism for producing an equilibrium potential well near the edge of a tokamak. Briefly, because of the difference in gyroradii between electrons and ions, an equilibrium electrostatic potential is generated in the presence of spatial inhomogeneity of the background plasma, which, in turn, produces a well associated with the radial electric field, Er, as observed at the edge of many tokamak experiments. We will show that this theoretically predicted Er field, which can be regarded as producing a long radial wavelength zonal flow, agrees well with recent experimental measurements. The relationship between the equilibrium configuration used in this study and that of the Woltjer-Taylor state will be discussed.
Gyrokinetic particle simulations of the effects of compressional magnetic perturbations on drift-Alfvenic instabilities in tokamaks
Authors: Dong Ge , Bao Jian , Bhattacharjee Amitava , Brizard Alain , Lin Zhihong , Porazik Peter
Published: August 2017

The compressional component of magnetic perturbation δB∥ can play an important role in drift-Alfvenic instabilities in tokamaks, especially as the plasma β increases (β is the ratio of kinetic pressure to magnetic pressure). In this work, we have formulated a gyrokinetic particle simulation model incorporating δB∥, and verified the model in kinetic Alfven wave simulations using the Gyrokinetic Toroidal Code in slab geometry. Simulations of drift-Alfvenic instabilities in tokamak geometry shows that the kinetic ballooning mode (KBM) growth rate decreases more than 20% when δB∥ is neglected for βe=0.02, and that δB∥ has stabilizing effects on the ion temperature gradient instability, but negligible effects on the collisionless trapped electron mode. The KBM growth rate decreases about 15% when equilibrium current is neglected.
Analytical solution of the tokamak equilibrium. I. The fixed-boundary case
Authors: Ludwig G. O.
Published: August 2017

This article presents an analytical method to evaluate the equilibrium of plasmas in axisymmetric, nested magnetic configurations relevant for tokamak experiments. The emphasis is in the use of spectral representations of the magnetic flux surfaces and variational methods to solve the Grad-Shafranov equation. Approximate solutions are obtained based on power series expansions of the variational moment equations and sectionally continuous representations of the Fourier amplitudes. The method is applied to an up-down asymmetric configuration of an ITER-like tokamak in a fixed-boundary equilibrium. The free-boundary case is treated in the Paper II [G. O. Ludwig, Phys. Plasma 24, 092503 (2017)].
Analytical solution of the tokamak equilibrium. II. The free-boundary case
Authors: Ludwig G. O.
Published: August 2017

The free-boundary tokamak equilibrium problem is investigated by a surface current equivalence method applied on the plasma boundary. In addition, use is made of a spectral representation for the internal plasma flux surfaces as presented in Paper I [G. O. Ludwig, Phys. Plasma 24, 092502 (2017)]. The surface current distribution is determined by the Cauchy condition imposed by the external equilibrium coils on the plasma boundary. A self-consistent approximate analytic equilibrium is calculated for an up-down asymmetric configuration of the plasma contained by a simplified set of poloidal field coils representing an ITER-like tokamak.
Hopf/steady-state mode interaction in a vertical slot—Effect of 1:4 resonance
Authors: Fujimura Kaoru , Tsunoda Shuhei
Published: August 2017

Hopf/steady-state mode interaction in a vertical slot with side-wall heating is revisited. Linear stability analysis reveals that a pair of Hopf modes and a steady mode share the critical Grashof number at a crossover Prandtl number P*=12.454 256 44. About a quarter century ago, the non-resonant mode interaction between the critical modes was investigated for a Prandtl number close to P*. In the present paper, we claim that the critical Hopf modes and the steady mode have wavenumbers approximately in a ratio of 1:4. We then examine the effect of 1:4 resonance on the Hopf/steady mode interaction although the 1:4 resonance arises at the quartic-order approximation. This implies that the resonance is so weak that its effect of phase coupling is expected to be negligibly small compared with the effect of coupling acting through the moduli of amplitudes arising at the cubic order. We find, however, that the resonance is indispensable for the bifurcation of symmetric mixed modes with phase differences of 0 and π, from which an asymmetric mixed mode bifurcates.
Note: Planetary gravities made simple: Sample test of a Mars rover wheel
Authors: Viera-López G. , Serrano-Muñoz A. , Amigó-Vega J. , Cruzata O. , Altshuler E.
Published: August 2017

We introduce an instrument for a wide spectrum of experiments on gravities other than our planet’s. It is based on a large Atwood machine where one of the loads is a bucket equipped with a single board computer and different sensors. The computer is able to detect the falling (or rising) and then the stabilization of the effective gravity and to trigger actuators depending on the experiment. Gravities within the range 0.4 g–1.2 g are easily achieved with acceleration noise of the order of 0.01 g. Under Martian gravity, we are able to perform experiments of approximately 1.5 s duration. The system includes features such as WiFi and a web interface with tools for the setup, monitoring, and data analysis of the experiment. We briefly show a case study in testing the performance of a model Mars rover wheel in low gravities.
Dirac cones in two-dimensional acoustic metamaterials
Authors: Dai Hongqing , Xia Baizhan , Yu Dejie
Published: August 2017

Dirac cones show many extraordinary properties, including Klein tunneling, pseudo-diffusive behavior, phase reconstruction, and topological edge states, and are thus attracting increasing research attention. However, no studies of Dirac cones on a subwavelength scale have been reported to date. In this paper, subwavelength-scale Dirac cones are realized using acoustic metamaterials that consist of hexagonal arrays of hexagonal columns with Helmholtz resonators. We have calculated the band structures of the three types of unit cells that are yielded by space group symmetry operations of the triangular Helmholtz resonators. The results show that these acoustic metamaterials with Helmholtz resonators can be used successfully to reduce the Dirac cone frequencies. Subwavelength Dirac cones of acoustic metamaterials with p6 mm or p6 symmetries are robust to rotation, while subwavelength Dirac cones of acoustic metamaterials with p31m symmetry are sensitive to rotation. In addition, the Dirac cone frequency decreases gradually with increasing filling ratio, which indicates a possible way to control wave propagation on the subwavelength scale. Numerical simulation results show that acoustic metamaterials can behave like zero-refractive-index media and can be applied to acoustic tunneling. The acoustic metamaterials designed in this work offer a route towards the design of functional acoustic devices operating on subwavelength scales.
Proposal of highly efficient photoemitter with strong photon-harvesting capability and exciton superradiance
Authors: Matsuda Takuya , Ishihara Hajime
Published: August 2017

We propose a system of highly efficient photoemitters comprising metal-molecule multilayered structures. In the proposed structure, the absorption in the molecular layer is greatly enhanced through quantum interference between the split modes arising from the coupling of the layered excitons and the plasmons sustained by the metal layer. Furthermore, the large interaction volume between surface plasmons and excitons causes exciton superradiance, which results in the extremely efficient photoemission. This finding indicates the possibility of designing highly efficient photoemitters based on simple layered structures.
Size-dependent piezoelectricity of molybdenum disulfide (MoS2) films obtained by atomic layer deposition (ALD)
Authors: Huang Yazhou , Liu Lei , Sha Jingjie , Chen Yunfei
Published: August 2017

As a member of transition metal dichalcogenides, MoS2 is an ideal low-dimensional piezoelectric material, which makes it attract wide attention for potential usage in next generation piezoelectric devices. In this study, the size-dependent piezoelectricity of MoS2 films with different grain sizes obtained at different temperatures by atomic layer deposition (ALD) was determined, which indicates that the grain size is critical to the piezoelectric constant. When the grain size is less than 120 nm, the piezoelectric constant increases with the increase in the grain size. Moreover, the piezoelectric constant first increases and then decreases with the increase in the film thickness. Therefore, piezoelectric constants of these MoS2 films can be modulated by changing the growth temperature and applying different ALD cycles.
Structural and electronic properties of MoS2, WS2, and WS2/MoS2 heterostructures encapsulated with hexagonal boron nitride monolayers
Authors: Yelgel C. , Yelgel Ö. C. , Gülseren O.
Published: August 2017

In this study, we investigate the structural and electronic properties of MoS2, WS2, and WS2/MoS2 structures encapsulated within hexagonal boron nitride (h-BN) monolayers with first-principles calculations based on density functional theory by using the recently developed non-local van der Waals density functional (rvv10). We find that the heterostructures are thermodynamically stable with the interlayer distance ranging from 3.425 Å to 3.625 Å implying van der Waals type interaction between the layers. Except for the WS2/h-BN heterostructure which exhibits direct band gap character with the value of 1.920 eV at the K point, all proposed heterostructures show indirect band gap behavior from the valence band maximum at the Γ point to the conduction band minimum at the K point with values varying from 0.907 eV to 1.710 eV. More importantly, it is found that h-BN is an excellent candidate for the protection of intrinsic properties of MoS2, WS2, and WS2/MoS2 structures.
Electrical spin transport in cylindrical silicon nanowires with CoFeB/MgO contacts
Authors: Park Tae-Eon , Min Byoung-Chul , Park Hee Gyum , Lee Jaejun , Jo Moon-Ho , Jang Chaun , Koo Hyun Cheol , Choi Heon-Jin , Chang Joonyeon
Published: August 2017

We examined electrical spin transport in cylindrical silicon nanowires (Si NWs) using the lateral nonlocal spin-valve (NLSV) geometry with CoFeB/MgO contacts. The use of a thin MgO layer as the tunnel barrier in the NLSV devices provided an optimum resistance-area product for spin transport measurements in the Si NWs. A robust NLSV spin signal of over 3.95 kΩ and clear minor loops were observed at 1.8 K in the Si NWs heavily doped with phosphorous. Furthermore, the NLSV magnetoresistance was strongly influenced by the local magnetizations resulting from the ferromagnetic (FM) electrodes being attached to the cylindrically shaped Si NW, with these magnetizations differing from those of bulk ferromagnets. These local micro-magnetic configurations of the FM electrodes led to intriguing NLSV spin signals associated with the Hanle effect. Our study of spin transport in the heavily doped Si NWs provides a sound basis for developing applications of nanoscale semiconductor spintronic devices.
Blood constituents of free-ranging eastern grey kangaroos (Macropus giganteus)
Authors: Green-Barber Jai M. , Ong Oselyne T. W. , Kanuri Anusha , Stannard Hayley J. , Old Julie M.
Published: August 2017

Baseline haematology, blood chemistry and acute phase protein parameters have not previously been published for free-ranging eastern grey kangaroos (Macropus giganteus). Eight eastern grey kangaroos, including three adult males, three adult females and two subadult males from two different populations, were examined. Assays assessed the antibacterial activity of kangaroo serum against one Gram-positive and three Gram-negative bacteria. The kangaroo serum had a strong antibacterial response to Klebsiella pneumoniae, and moderate responses to Escherichia coli and Staphylococcus aureus. The presence and level of acute phase proteins, haptoglobin and serum amyloid A in kangaroos was investigated. Haptoglobin and serum amyloid A were present in kangaroo serum, but only haptoglobin was elevated in a kangaroo with capture myopathy and necrotic wounds. The findings of this study provide preliminary data on health parameters of free-ranging eastern grey kangaroos. These parameters can be used to assist in assessing health in free-ranging populations.
Relationship between nitrogen resorption and leaf size in the aroid vine Rhodospatha oblongata (Araceae)
Authors: Mantovani André , Mantuano Dulce , Arcoverde de Mattos Eduardo
Published: August 2017

Nitrogen resorption (NR) from senescing leaves enhances nutrient conservation in plants. Leaf area in lianescent aroid vines increases dramatically as the plant ascends vertically on its host. In Rhodospatha oblongata Schott, the largest leaves have up to 35 times the area and 50 times the N content of the smallest. We hypothesised that despite the costs of reallocating nitrogen within the plant, the huge increase in nitrogen cost to produce larger new leaves in R. oblongata should lead to increased NR from large leaves, mitigating the high demands on N acquisition from primary sources. The amount of veins available per unit leaf area may however constrain the ability to reutilise nitrogen within the plant. It was found that N concentration was 2–3% in green and 1–2% in senescent leaves, independent of leaf area, whereas vein density increased with leaf area. N use efficiency, resorption efficiency, and proficiency were not affected by leaf area; however, results indicate that R. oblongata does not have a conservative use of N despite occurring in oligotrophic soils. The absence of increased N resorption indicates that R. oblongata may have the capacity to acquire large amounts of soil and aerial N to produce new larger leaves, which after leaf fall may positively affect litter decomposition.
Influence of auxin and phenolic accumulation on the patterns of cell differentiation in distinct gall morphotypes on Piptadenia gonoacantha (Fabaceae)
Authors: Bedetti Cibele Souza , Bragança Gracielle Pereira , Isaias Rosy Mary dos Santos
Published: August 2017

The cascade of biochemical changes occurring at sites of gall development seems to involve a group of common metabolites in plants, namely, the phenolics. Phenolic accumulation has been commonly related to chemical defence, but their primary role seems to be the regulation of cell hypertrophy in galls. Such regulation implies phenolics–auxin (IAA) association at some cell re-differentiation sites, and determines final gall shapes. Herein, we investigated phenolic and auxin accumulation in four gall systems, grouped in two morphotypes, namely lenticular and globoid, induced on pinnulas of Piptadenia gonoacantha (Mart.) J.F.Macbr. Changes in the direction and type of cell expansion between non-galled pinnula and galls were also evaluated. Galling insects associated to lenticular and globoid gall morphotypes promoted changes in host plant cells, leading to the development of different cell sizes, different degrees of anisotropy, and different directions of cell expansion. The accumulation of IAA–phenolics compartmentalised on the basis of gall morphotype, i.e. in the cells of superior and lateral inferior cortices in the lenticular gall morphotypes, and throughout the outer cortex in the globoid gall morphotypes. The sites of accumulation of IAA and phenolics coincided with the most hypertrophied regions, influencing on the determination of the final gall shape.
Nasopharyngeal infection byStreptococcus pyogenesrequires superantigen-responsive Vβ-specific T cells
Authors: Zeppa Joseph J. , Kasper Katherine J. , Mohorovic Ivor , Mazzuca Delfina M. , Haeryfar S. M. Mansour , McCormick John K.
Published: August 2017

Significance

Superantigen toxins were defined over 25 years ago for their ability to activate T cells in a T-cell receptor β-chain variable domain-dependent manner. This “Vβ-specific” T-cell activation is the hallmark feature of the superantigen, and although these toxins can mediate dangerous human disease such as toxic shock syndrome, mechanisms that explain why bacteria produce superantigens have remained enigmatic. Herein, we provide evidence thatStreptococcus pyogenesutilizes superantigens to target functional, Vβ-specific T cells to promote a state of colonization providing a mechanism that helps explain why bacteria produce toxins that specifically activate T cells of the adaptive immune system. This work also implicates the superantigen exotoxins as potential vaccine candidates against this globally important, human-specific pathogen.
Lethality of MalE-LacZ hybrid protein shares mechanistic attributes with oxidative component of antibiotic lethality
Authors: Takahashi Noriko , Gruber Charley C. , Yang Jason H. , Liu Xiaobo , Braff Dana , Yashaswini Chittampalli N. , Bhubhanil Sakkarin , Furuta Yoshikazu , Andreescu Silvana , Collins James J. , Walker Graham C.
Published: August 2017

Significance

Understanding the molecular basis of the lethality of antibiotics and certain other stresses is complicated because cell death can result from direct inhibition of a critical biological process as well as from reactive oxygen species (ROS) generated by events metabolically downstream of the direct interaction of the agent with its target. Prior evidence has indicated that the ROS-dependent component of antibiotic lethality is due in part to lethal DNA problems resulting from the incorporation of oxidized nucleotides into DNA and incomplete DNA repair. Our observations unexpectedly indicate that the predominant mechanism of lethality from a hybrid protein that jams the machinery that translocates proteins across the cytoplasmic membrane shares attributes with the ROS-dependent component of antibiotic lethality.
Residual stress and microstructural features of friction-stir-welded GL E36 shipbuilding steel
Authors: Lemos G. V. B. , Cunha P. H. C. P. , Nunes R. M. , Bergmann L. , dos Santos J. F. , Clarke T.
Published: August 2017

The purpose of the present study was to fulfil the knowledge gap concerning residual stresses evaluation of friction stir welded GL E36 shipbuilding steel. Plates of 6 mm thickness were welded using two different welding speeds (1 and 3 mm s−1) at a constant rotational speed of 500 rev min−1. This led to different thermal cycles and the objective is to analyse the resulting microstructures and residual stress states. Therefore, in this work, residual stresses were evaluated by X-ray diffraction; metallography and microhardness testing were performed to support these measurements. Results showed that welds produced with different heat inputs have distinguishable residual stress distributions. Increases in the welding speed led to higher residual stress and microhardness in the stir zone.