bluuebunny/crossref_metadata_2025 huggingface dataset:
Unification of catalytic oxygen reduction and hydrogen evolution reactions: highly dispersive Co nanoparticles encapsulated inside Co and nitrogen co-doped carbon
Authors: Wang Y. , Nie Y. , Ding W. , Chen S. G. , Xiong K. , Qi X. Q. , Zhang Y. , Wang J. , Wei Z. D.
Published: April 2015

The elaborately synthesized Co nanoparticles encapsulated inside Co and nitrogen co-doped carbon catalysts with homogenous distribution of Co NPs exhibit evidently outstanding performances toward ORR/HER.
NIR light controlled release of caged hydrogen sulfide based on upconversion nanoparticles
Authors: Chen Wansong , Chen Min , Zang Qiguang , Wang Liqiang , Tang Feiying , Han Yajing , Yang Cejun , Deng Liu , Liu You-Nian
Published: April 2015

The first near-infrared light induced H2S release platform based on upconversion nanoparticles was constructed.
Tracking the transformations of mesoporous microspheres of calcium silicate hydrate at the nanoscale upon ibuprofen release: a XANES and STXM study
Authors: Guo Xiaoxuan , Wang Zhiqiang , Wu Jin , Hu Yongfeng , Wang Jian , Zhu Ying-Jie , Sham Tsun-Kong
Published: April 2015

XANES and STXM imaging of mesoporous CSH microspheres indicate that amorphous silica provide aggregation site of HAp, and amorphous CaCO3 was formed during CSH biomineralization.
Tetrazolate–azido–copper(ii) coordination polymers: tuned synthesis, structure, and magnetic properties
Authors: Xie Ya-Bo , Gan Lei , Carolina Sañudo E. , Zheng Haiyang , Zhao Jiongpeng , Zhao Minjian , Wang Bin , Li Jian-Rong
Published: April 2015

Two antiferrimagnetic tetrazolate–azido–copper(ii) coordination polymers, [Cu(tz)(N3)]n (1) and [Cu(tz)(N3)(NH3)2]n (2) with distinct topological structures were synthesized under different reaction conditions and structurally characterized.
Kinetic and mechanistic study of the reaction of OH radicals with methylated benzenes: 1,4-dimethyl-, 1,3,5-trimethyl-, 1,2,4,5-, 1,2,3,5- and 1,2,3,4-tetramethyl-, pentamethyl-, and hexamethylbenzene
Authors: Alarcón P. , Bohn B. , Zetzsch C.
Published: April 2015

Reversible formation of OH-adducts with methylated benzenes.
Selectively splitting a droplet using superhydrophobic stripes on hydrophilic surfaces
Authors: Song Dong , Song Baowei , Hu Haibao , Du Xiaosong , Zhou Feng
Published: April 2015

The droplet can be split by impinging on the hybrid hydrophobic–hydrophilic surface at a high velocity.
The preferred upconversion pathway for the red emission of lanthanide-doped upconverting nanoparticles, NaYF4:Yb3+,Er3+
Authors: Jung Taeyoung , Jo Hong Li , Nam Sang Hwan , Yoo Byeongjun , Cho Youngho , Kim Jongwoo , Kim Hyung Min , Hyeon Taeghwan , Suh Yung Doug , Lee Hohjai , Lee Kang Taek
Published: April 2015

Only one upconversion pathway turned out to be available for the red emission in NaYF4:Yb3+,Er3+/NaYF4 nanocrystals.
Photo- and electro-luminescence of four cuprous complexes with sterically demanding and hole transmitting diimine ligands
Authors: Zhang Qing , Chen Xu-Lin , Chen Jun , Wu Xiao-Yuan , Yu Rongmin , Lu Can-Zhong
Published: April 2015

The steric methyl group at emissive cuprous complexes largely increases both the PL and EL efficiency, while the carbazole appendage modestly improves the EL efficiency. So,4shows the highest efficiency with a CEmaxof 27.1 cd A−1and an EQEmaxof 8.7%.
Frustrated N-heterocyclic carbene–silylium ion Lewis pairs
Authors: Silva Valverde Miguel F. , Theuergarten Eileen , Bannenberg Thomas , Freytag Matthias , Jones Peter G. , Tamm Matthias
Published: April 2015

The reaction of a sterically demanding NHC affords frustrated carbene-trimethylsilylium ion pairs, which exhibit FLP-type reactivity such as carbon dioxide fixation and metal–halide bond activation.
Luminescent materials for solid-state lighting
Authors: Zysman-Colman Eli
Published: April 2015

Welcome to this Dalton Transactions themed issue on luminescent materials for solid-state lighting.
Reductive lignocellulose fractionation into soluble lignin-derived phenolic monomers and dimers and processable carbohydrate pulps
Authors: Van den Bosch S. , Schutyser W. , Vanholme R. , Driessen T. , Koelewijn S.-F. , Renders T. , De Meester B. , Huijgen W. J. J. , Dehaen W. , Courtin C. M. , Lagrain B. , Boerjan W. , Sels B. F.
Published: April 2015

A new generation lignocellulose biorefinery uses heterogeneous catalysis for the high-yield production of a handful of chemicals from wood.
A new scope for JAAS!
Authors: Vanhaecke Frank
Published: April 2015

Frank Vanhaecke, Chair of the Board of JAAS, explains the newly broadened journal scope.
AAFreqCoil: a new classifier to distinguish parallel dimeric and trimeric coiled coils
Authors: Wang Xiaofeng , Zhou Yuan , Yan Renxiang
Published: April 2015

Coiled coils are characteristic rope-like protein structures, constituted by one or more heptad repeats.
A low band-gap copolymer composed of thienyl substituted anthracene and diketopyrrolopyrrole compatible with multiple electron acceptors for high efficiency polymer solar cells
Authors: Jung Jae Woong , Jo Won Ho
Published: April 2015

A low band-gap polymer composed of thienylanthracene and DPP exhibits promising PCEs of 7.02% with PC71BM, and 4.23% with non-fullerene acceptor di-PBI, demonstrating the potential for universal electron donor polymer of polymer solar cells.
Facile solvothermal synthesis of porous ZnFe2O4 microspheres for capacitive pseudocapacitors
Authors: Zhu Maiyong , Zhang Xin , Zhou Yong , Zhuo Changhui , Huang Juncheng , Li Songjun
Published: April 2015

ZnFe2O4 microspheres, assembled by many primary nanocrystals, have been fabricated via a facile and cost-effective solvothermal approach and applied as pseudocapacitor electrode material.
Cyclic tetra[(indolyl)-tetra methyl]-diethane-1,2-diamine (CTet) impregnated hydrous zirconium oxide as a novel hybrid material for enhanced removal of fluoride from water samples
Authors: Rahman Nafisur , Haseen Uzma , Khan Mohammad Fazeel
Published: April 2015

A hybrid material was prepared by incorporating cyclic tetra[(indolyl)-tetra methyl]-diethane-1,2-diamine (CTet) into hydrous zirconium oxide (HZO)viathorough mixing of previously prepared CTet in methanol and stirred for 7 h at 27 °C.
Solution processed graphene–silicon Schottky junction solar cells
Authors: Larsen Lachlan J. , Shearer Cameron J. , Ellis Amanda V. , Shapter Joseph G.
Published: April 2015

Surfactant-assisted exfoliated graphene (SAEG) has been implemented in transparent conducting graphene films which, for the first time, were used to make SAEG–silicon Schottky junctions for photovoltaics.
Preparation of magnetic Ag/AgCl/CoFe2O4 composites with high photocatalytic and antibacterial ability
Authors: Xu Yuanguo , Zhou Teng , Huang Shuquan , Xie Meng , Li Hongping , Xu Hui , Xia Jiexiang , Li Huaming
Published: April 2015

The magnetically separable Ag/AgCl/CoFe2O4 photocatalyst possess high photocatalytic ability and antibacterial ability.
Catalytic metallodendrimers grafted on mesoporous polymethacrylate beads for the regioselective synthesis of β-amino alcohols under solvent-free conditions
Authors: Tiwari Richa , H. Daware Sachdeo , Kale Sandeep B.
Published: April 2015

Metallodendrimer-grafted mesoporous polymethyacrylate beads for the regioselective, solvent-free, efficient and scalable catalytic synthesis of β-amino alcohols at ambient temperature.
Highly stable ionic liquid-in-water emulsions as a new class of fluorescent sensors for metal ions: the case study of Fe3+ sensing
Authors: Bettoschi Alexandre , Bencini Andrea , Berti Debora , Caltagirone Claudia , Conti Luca , Demurtas Davide , Giorgi Claudia , Isaia Francesco , Lippolis Vito , Mamusa Marianna , Murgia Sergio
Published: April 2015

A stable fluorescent ionic liquid can act as a fluorescent sensor for metal ion recognition.
Au/graphene oxide/carbon nanotube flexible catalyst film: synthesis, characterization and its application for catalytic reduction of 4-nitrophenol
Authors: Yang Fan , Wang Chunxia , Wang Lina , Liu Chao , Feng Andong , Liu Xue , Chi Cheng , Jia Xilai , Zhang Liqiang , Li Yongfeng
Published: April 2015

We report a simple approach for fabricating flexible, free-standing and catalytic film composed of graphene oxide/carbon nanotube-Au. It shows excellent catalytic property in the reduction of 4-nitrophenol to 4-aminophenol reaction.
The size effect of Pt nanoparticles: a new route to improve sensitivity in electrochemical detection of As(iii)
Authors: Han Dong-Dong , Liu Zhong-Gang , Liu Jin-Huai , Huang Xing-Jiu
Published: April 2015

The size effect of Pt nanoparticles on detection of arsenic is clarified and the phenomenon is explained by anodic oxygen-transfer reactions and binding energy.
Nitrogen fixation catalyzed by ferrocene-substituted dinitrogen-bridged dimolybdenum–dinitrogen complexes: unique behavior of ferrocene moiety as redox active site
Authors: Kuriyama Shogo , Arashiba Kazuya , Nakajima Kazunari , Tanaka Hiromasa , Yoshizawa Kazunari , Nishibayashi Yoshiaki
Published: April 2015

Mo–N2complex bearing ferrocenes as redox-active units efficiently catalyses the formation of ammonia from molecular dinitrogen under ambient conditions.
Bending elasticity of vesicle membranes studied by Monte Carlo simulations of vesicle thermal shape fluctuations
Authors: Penič Samo , Iglič Aleš , Bivas Isak , Fošnarič Miha
Published: April 2015

Simulations of thermally fluctuating vesicles are used to obtain the bending stiffness of their membranes.
Improved oxide-ion conductivity of NdBaInO4by Sr doping
Authors: Fujii Kotaro , Shiraiwa Masahiro , Esaki Yuichi , Yashima Masatomo , Kim Su Jae , Lee Seongsu
Published: April 2015

The oxide-ion conductivity of NdBaInO4has been increased by Sr doping.
NIR optical carbon dioxide sensors based on highly photostable dihydroxy-aza-BODIPY dyes
Authors: Schutting Susanne , Jokic Tijana , Strobl Martin , Borisov Sergey M. , Beer Dirk de , Klimant Ingo
Published: April 2015

Optical carbon dioxide sensors based on novel self-referenced NIR colorimetric dihydroxy-aza-BODIPY dyes are presented. They possess tunable dynamic ranges and unmatched photostability.
Controllable synthesis of Zn2GeO4:Eu nanocrystals with multi-color emission for white light-emitting diodes
Authors: He Huilin , Zhang Yuanhao , Pan Qiwen , Wu Guobo , Dong Guoping , Qiu Jianrong
Published: April 2015

Multi-color and white light emissions are detected in various Zn2GeO4:xEu nanostructures, based on the competition between the emission from Zn2GeO4 host and Eu3+ ions, which show a potential application for white light emitting diodes.
Energy‐efficient switching scheme in SAR ADC for biomedical electronics
Authors: Tong Xingyuan , Ghovanloo Maysam
Published: April 2015

An energy‐efficient switching scheme for a low‐power successive approximation register (SAR) analogue‐to‐digital converter (ADC) is proposed. Taking the parasitic capacitance of the capacitor array into consideration, the average switching energy of the proposed scheme can be reduced by 97.4% compared with the conventional architecture. The proposed scheme also reduces the number of capacitors in the capacitor array by 75.5% and hence achieves area efficiency with high performance.
Network polar coded cooperation with joint SC decoding
Authors: Ejaz Saqib , Yang Fengfan , Soliman Tamer H.M.
Published: April 2015

A network polar coded‐cooperative (NPCC) scheme with joint successive cancellation (SC) decoding at the destination is proposed. Plotkin's construction is employed to build polar codes; however, the proposed construction is opposite to the conventional method where two short codes jointly construct a longer length code. In the proposed construction the two short codes (subcodes) are derived from the longer length code. The proposed construction is then employed to achieve coded cooperation between two users, and also offers a network coding, which not only improves the data rate of the coded cooperative system but also improves the overall bit error rate performance which is shown with the help of numerical simulations.
Substrate‐integrated waveguide phase shifter with rod‐loaded artificial dielectric slab
Authors: Djerafi T. , Wu K. , Tatu S.O.
Published: April 2015

A substrate‐integrated waveguide (SIW) broadband phase shifter is presented and studied. The phase shift mechanism is based on the synthesis of an artificial dielectric slab using an array of metallic rods in the middle of a SIW. This technique enables a large phase shift within a compact size and enhances the density of integration. As an example, 45° and 90° phase shifters are designed and showcased on a single‐layer substrate at a centre frequency of 26 GHz. The amplitude imbalance between the two paths is also avoided while the phase error is less than 5° over a frequency band of 20–32 GHz or around 46% relative bandwidth. The measured return loss is found to be better than 12 dB over the whole frequency band.
Limited frequency interval Gramian‐based model reduction for generalised non‐singular discrete time systems
Authors: Imran Muhammad , Ghafoor Abdul , Sreeram Victor
Published: April 2015

A limited frequency interval Gramians‐based model reduction technique for generalised non‐singular discrete time systems is presented. The technique generalises the results of existing limited frequency interval Gramians‐based model reduction (of discrete time systems) schemes to general non‐singular discrete time systems. Numerical examples are also presented to illustrate the proposed technique.
Leveraging longitudinal driving behaviour data with data mining techniques for driving style analysis
Authors: Qi Geqi , Du Yiman , Wu Jianping , Xu Ming
Published: April 2015

Accurately understanding driving behaviour is of crucial importance for advanced driving assistant systems such as adaptive cruise control system and intelligent forward collision warning system. To understand different driving styles, this study employs the clustering method and topic model to extract latent driving states, which can elaborate and analyse the commonness and individuality of driving behaviour characteristics with the longitudinal driving behaviour data collected by the instrumented vehicle. To handle the large set of data and discover the valuable knowledge, the data mining techniques including ensemble clustering method based on the kernel fuzzy C‐means algorithm and the modified latent Dirichlet allocation model are employed in this study. The ‘aggressive’, ‘cautious’ and ‘moderate’ driving states are discovered and the underlying quantified structure is built for the driving style analysis.
Interoperability of eCall and ERA‐GLONASS in‐vehicle emergency call systems
Authors: Öörni Risto , Meilikhov Evgeni , Korhonen Timo Olavi
Published: April 2015

The objective of this study is to analyse the interoperability between pan‐European eCall and Russian ERA‐GLONASS in‐vehicle emergency call systems. The analysis is based on a definition of interoperability from International Telecommunication Union and related system standards of eCall and ERA‐GLONASS. The authors results indicate that the core functions of both systems – minimum set of data (MSD) transmission at the start of the call and establishing the related voice connection between vehicle occupants and a public safety answering point – will be available in the interworking scenarios analysed in this study. However, not all features of both systems will be available in use cases with interworking between the systems, such as SMS‐based MSD retransmission. The study indicates that further empirical tests are required to obtain more information on practical interoperability between the systems.
Doubly‐fed induction generator ride‐through fault capability using resonant controllers for asymmetrical voltage sags
Authors: Mendes Victor Flores , de Sousa Clodualdo Venicio , Hofmann Wilfried , Silva Selênio Rocha
Published: April 2015

Modern grid codes worldwide determine specific requirements for the connection of wind energy conversion systems (WECSs) to the grid. One of the requirements is the ride‐through fault capability (RTFC) or low‐voltage ride‐through (LVRT), which defines that the plants must not be disconnected from the grid at certain levels of voltage sags and also must contribute to network stabilisation. The LVRT of the doubly‐fed induction generator (DFIG) technology is a well‐known problem, mainly during unbalanced grid voltage conditions. The present study extends the studies presented in the literature, analysing the DFIG behaviour during asymmetrical voltage sags using a frequency‐domain modelling. A modified resonant controller is proposed to improve the system response during voltage sags, and the analysis of the RTFC based on the converter limits is carried out. The proposed strategy is validated with simulation results of a 2 MW‐WECS and experimental results of a 25 kW scaled test bench.
A special class of Painlevé differential systems that generalize the elliptic functions
Authors: Gaffet B.
Published: April 2015

The elliptic functions of order 2 may be viewed as the ratios Z2/Z1 of the solutions of a differential system of the general form: Zi3/8d2Zj/Zid u2=ZjRii−ZiRiji≠j,i,j=1,…,n, where n = 2, u is the independent variable, and the Rij are the homogeneous quadratic functions of the n variables Zi. The general solution of systems of this form automatically consists, for all n, of purely meromorphic functions. For arbitrary values of n, the system consists of n (n − 1) equations for (n − 1) inhomogeneous variables Zi/Z1, and the question arises as to whether there may exist systems of the above form, with n > 2, which are equivalent to a non-over-determined differential system of p equations, when n-p-1 appropriately chosen algebraic constraints are imposed on the dependent variables. In the present work, we show that such systems do exist, with n = 4 and n = 8, and are in fact special cases of the Dyson model (1968) of a spinning cloud of ellipsoidal shape, expanding adiabatically into a vacuum.
Bubble nucleation in simple and molecular liquids via the largest spherical cavity method
Authors: Gonzalez Miguel A. , Abascal José L. F. , Valeriani Chantal , Bresme Fernando
Published: April 2015

In this work, we propose a methodology to compute bubble nucleation free energy barriers using trajectories generated via molecular dynamics simulations. We follow the bubble nucleation process by means of a local order parameter, defined by the volume of the largest spherical cavity (LSC) formed in the nucleating trajectories. This order parameter simplifies considerably the monitoring of the nucleation events, as compared with the previous approaches which require ad hoc criteria to classify the atoms and molecules as liquid or vapor. The combination of the LSC and the mean first passage time technique can then be used to obtain the free energy curves. Upon computation of the cavity distribution function the nucleation rate and free-energy barrier can then be computed. We test our method against recent computations of bubble nucleation in simple liquids and water at negative pressures. We obtain free-energy barriers in good agreement with the previous works. The LSC method provides a versatile and computationally efficient route to estimate the volume of critical bubbles the nucleation rate and to compute bubble nucleation free-energies in both simple and molecular liquids.
Microwave-induced thermogenetic activation of single cells
Authors: Safronov N. A. , Fedotov I. V. , Ermakova Yu. G. , Matlashov M. E. , Sidorov-Biryukov D. A. , Fedotov A. B. , Belousov V. V. , Zheltikov A. M.
Published: April 2015

Exposure to a microwave field is shown to enable thermogenetic activation of individual cells in a culture of cell expressing thermosensitive ion channels. Integration of a microwave transmission line with an optical fiber and a diamond quantum thermometer has been shown to allow thermogenetic single-cell activation to be combined with accurate local online temperature measurements based on an optical detection of electron spin resonance in nitrogen–vacancy centers in diamond.
Mass-velocity and size-velocity distributions of ejecta cloud from shock-loaded tin surface using atomistic simulations
Authors: Durand O. , Soulard L.
Published: April 2015

The mass (volume and areal densities) versus velocity as well as the size versus velocity distributions of a shock-induced cloud of particles are investigated using large scale molecular dynamics simulations. A generic three-dimensional tin crystal with a sinusoidal free surface roughness (single wavelength) is set in contact with vacuum and shock-loaded so that it melts directly on shock. At the reflection of the shock wave onto the perturbations of the free surface, two-dimensional sheets/jets of liquid metal are ejected. The simulations show that the distributions may be described by an analytical model based on the propagation of a fragmentation zone, from the tip of the sheets to the free surface, in which the kinetic energy of the atoms decreases as this zone comes closer to the free surface on late times. As this kinetic energy drives (i) the (self-similar) expansion of the zone once it has broken away from the sheet and (ii) the average size of the particles which result from fragmentation in the zone, the ejected mass and the average size of the particles progressively increase in the cloud as fragmentation occurs closer to the free surface. Though relative to nanometric scales, our model may help in the analysis of experimental profiles.
Formulation of a unified method for low- and high-energy expansions in the analysis of reflection coefficients for one-dimensional Schrödinger equation
Authors: Miyazawa Toru
Published: April 2015

We study low-energy expansion and high-energy expansion of reflection coefficients for one-dimensional Schrödinger equation, from which expansions of the Green function can be obtained. Making use of the equivalent Fokker-Planck equation, we develop a generalized formulation of a method for deriving these expansions in a unified manner. In this formalism, the underlying algebraic structure of the problem can be clearly understood, and the basic formulas necessary for the expansions can be derived in a natural way. We also examine the validity of the expansions for various asymptotic behaviors of the potential at spatial infinity.
Investigation of spin reorientation in YMn1−xFexO3 (x = 0.55, 0.6, 0.7, 0.8, 0.9, and 1.0) by Mössbauer spectroscopy
Authors: Lim Jung Tae , Choi Young Jai , Kim Chul Sung
Published: April 2015

YMn1−xFexO3 (x = 0.55, 0.6, 0.7, 0.8, 0.9, and 1.0) polycrystalline samples were prepared by the solid-state-reaction method. The crystal structure and magnetic properties of samples were investigated with x-ray diffractometer (XRD), vibrating sample magnetometer, and Mössbauer spectroscopy. The XRD patterns at 295 K, analyzed by Rietveld refinement method, showed that all samples were single-phased orthorhombic of Pnma with both Bragg (RB) and structure (RF) factors less than 5%. Mössbauer spectra of all samples were obtained at various temperatures ranging from 4.2 to 500 K, and the spectra below TC were fitted by least-square method as a function of the Fe and Mn distribution. Isomer shift (δ) values of all samples indicated that the charge states were Fe3+. In addition, temperature-dependent hyperfine field (Hhf), averaged electric quadrupole shift 〈EQ〉, and averaged isomer shift 〈δ〉 have shown abrupt changes around TSR due to the change in the charge state of Mn ions.
Recent advances in symmetric and network dynamics
Authors: Golubitsky Martin , Stewart Ian
Published: April 2015

We summarize some of the main results discovered over the past three decades concerning symmetric dynamical systems and networks of dynamical systems, with a focus on pattern formation. In both of these contexts, extra constraints on the dynamical system are imposed, and the generic phenomena can change. The main areas discussed are time-periodic states, mode interactions, and non-compact symmetry groups such as the Euclidean group. We consider both dynamics and bifurcations. We summarize applications of these ideas to pattern formation in a variety of physical and biological systems, and explain how the methods were motivated by transferring to new contexts René Thom's general viewpoint, one version of which became known as “catastrophe theory.” We emphasize the role of symmetry-breaking in the creation of patterns. Topics include equivariant Hopf bifurcation, which gives conditions for a periodic state to bifurcate from an equilibrium, and the H/K theorem, which classifies the pairs of setwise and pointwise symmetries of periodic states in equivariant dynamics. We discuss mode interactions, which organize multiple bifurcations into a single degenerate bifurcation, and systems with non-compact symmetry groups, where new technical issues arise. We transfer many of the ideas to the context of networks of coupled dynamical systems, and interpret synchrony and phase relations in network dynamics as a type of pattern, in which space is discretized into finitely many nodes, while time remains continuous. We also describe a variety of applications including animal locomotion, Couette–Taylor flow, flames, the Belousov–Zhabotinskii reaction, binocular rivalry, and a nonlinear filter based on anomalous growth rates for the amplitude of periodic oscillations in a feed-forward network.
Size dependent compressibility of nano-ceria: Minimum near 33 nm
Authors: Rodenbough Philip P. , Song Junhua , Walker David , Clark Simon M. , Kalkan Bora , Chan Siu-Wai
Published: April 2015

We report the crystallite-size-dependency of the compressibility of nanoceria under hydrostatic pressure for a wide variety of crystallite diameters and comment on the size-based trends indicating an extremum near 33 nm. Uniform nano-crystals of ceria were synthesized by basic precipitation from cerium (III) nitrate. Size-control was achieved by adjusting mixing time and, for larger particles, a subsequent annealing temperature. The nano-crystals were characterized by transmission electron microscopy and standard ambient x-ray diffraction (XRD). Compressibility, or its reciprocal, bulk modulus, was measured with high-pressure XRD at LBL-ALS, using helium, neon, or argon as the pressure-transmitting medium for all samples. As crystallite size decreased below 100 nm, the bulk modulus first increased, and then decreased, achieving a maximum near a crystallite diameter of 33 nm. We review earlier work and examine several possible explanations for the peaking of bulk modulus at an intermediate crystallite size.
Decay of transverse correlations in quantum Heisenberg models
Authors: Björnberg Jakob E. , Ueltschi Daniel
Published: April 2015

We study a class of quantum spin systems that include the S=12 Heisenberg and XY-models and prove that two-point correlations exhibit exponential decay in the presence of a transverse magnetic field. The field is not necessarily constant, it may be random, and it points in the same direction. Our proof is entirely probabilistic and it relies on a random loop representations of the correlation functions, on stochastic domination and on first-passage percolation.
A scheme to produce high density and high temperature plasma for opacity measurement
Authors: Xu Yan , Wu SiZhong , Zheng WuDi
Published: April 2015

The opacity of shock-compressed material is of general scientific interest for astrophysical plasmas and for inertial confinement fusion research. A proposal is suggested to produce high temperature plasma with density around 1 g/cm−3. Two types of opacity target (the sandwich target and the foam enhanced sandwich target) are investigated numerically. The foam enhanced sandwich target has structure of foam–solid-sample-solid-foam. The foam will increase laser absorption efficiency and the ablating pressure. Hydrodynamic simulations confirm that the laser can be fully absorbed by the under-critical-density foam and a faster shock is produced inside the CH layer. High intensity lasers heat opacity target from both sides. The CH layers must be thick enough to keep the laser away from the sample. The laser-driven shocks move inward and collide at the center. Part of their kinetic energy is converted into internal energy and high density and high temperature local thermodynamic equilibrium sample plasma is produced. The plasma produced by laser heating the foam enhanced sandwich target has higher sample temperature than by laser heating the sandwich target. It may be useful for measuring the opacity of shock compressed material in laboratory.
On uniform plasma generation for the large area plasma processing in intermediate pressures
Authors: Kim Hyun Jun , Hwang Hye-Ju , Kim Dong Hwan , Cho Jeong Hee , Chae Hee Sun , Chung Chin-Wook
Published: April 2015

Radial plasma discharge characteristics in the range of 450 mm were studied in a dual inductively coupled plasma (ICP) source, which consisted of a helical ICP and the side type ferrite ICPs. Since the energy relaxation length is shorter than the distance between each of the ferrite ICPs in an intermediate pressure (600 mTorr), local difference in the plasma ignition along the antenna position were observed. In addition, large voltage drop in the discharge of the ferrite ICPs causes an increase in the displacement current to the plasma, and separate discharge mode (E and H mode) according to the antenna position was observed. This results in non-uniform plasma distribution. For the improvement in the discharge of the ferrite ICPs, a capacitor which is placed between the ends of antenna and the ground is adjusted to minimize the displacement current to the plasma. As a result, coincident transitions from E to H mode were observed along the antenna position, and radially concave density profile (edge focused) was measured. For the uniform density distribution, a helical ICP, which located at the center of the discharge chamber, was simultaneously discharged with the ferrite ICPs. Due to the plasma potential variation through the simultaneous discharge of helical ICP and ferrite ICPs, uniform radial distribution in both plasma density and electron temperature are achieved.
Induced magnetic anisotropy in Si-free nanocrystalline soft magnetic materials: A transmission x-ray diffraction study
Authors: Parsons R. , Yanai T. , Kishimoto H. , Kato A. , Ohnuma M. , Suzuki K.
Published: April 2015

In order to better understand the origin of field-induced anisotropy (Ku) in Si-free nanocrystalline soft magnetic alloys, the lattice spacing of the bcc-Fe phase in nanocrystalline Fe94−xNb6Bx (x = 10, 12, 14) alloys annealed under an applied magnetic field has been investigated by X-ray diffraction in transmission geometry (t-XRD) with the diffraction vector parallel and perpendicular to the field direction. The saturation magnetostriction (λs) of nanocrystalline Fe94−xNb6Bx was found to increase linearly with the volume fraction of the residual amorphous phase and is well described by taking into account the volume-weighted average of two local λs values for the bcc-Fe nanocrystallites (−5 ± 2 ppm) and the residual amorphous matrix (+8 ± 2 ppm). The lattice distortion required to produce the measured Ku values (∼100 J/m3) was estimated via the inverse magnetostrictive effect using the measured λs values and was compared to the lattice spacing estimations made by t-XRD. The lattice strain required to produce Ku under the magnetoelastic model was not observed by the t-XRD experiments and so the findings of this study suggest that the origin of magnetic field induced Ku cannot be explained through the magnetoelastic effect.
Disentangling longitudinal and shear elastic waves by neo-Hookean soft devices
Authors: Chang Zheng , Guo Hao-Yuan , Li Bo , Feng Xi-Qiao
Published: April 2015

Longitudinal and shear elastic waves are often spatially entangled in solid media and are difficult to be separated from each other. An efficient approach is proposed to physically split the two types of elastic waves by using soft hyperelastic materials. Invoking the hyperelastic transformation theory, we demonstrate that the longitudinal and shear elastic waves possess distinct characteristics and propagate in different paths in a deformed neo-Hookean material. This principle enables us to design tunable, broadband, and lossless wave-mode splitters by using a simple-shear-deformed neo-Hookean solid. Both theoretical analysis and numerical simulations confirm the high performance of the proposed soft device.
Reduction of stimulated Brillouin backscattering with plasma beam smoothing
Authors: Yahia V. , Masson-Laborde P.-E. , Depierreux S. , Goyon C. , Loisel G. , Baccou C. , Borisenko N. G. , Orekhov A. , Rienecker T. , Rosmej O. , Teychenné D. , Labaune C.
Published: April 2015

Plasma induced incoherence (PII) can strongly modify the growth rates of stimulated scattering instabilities. A special double-target design was used to quantify the effect of PII on stimulated Brillouin scattering (SBS). Successive shots using all or part of these targets led to the characterization of temporal and spatial incoherence of a laser pulse after propagation through a foam plasma and to the quantification of the reduction of SBS from the second target. Numerical simulations were used to identify the main physical mechanisms in play.
Photoelectric sheath formation around small spherical objects in space
Authors: Misra Shikha , Mishra S. K. , Sodha M. S.
Published: April 2015

The formation of a photoelectron sheath around positively charged small (∼cm) spherical objects roaming in near earth space due to the solar radiation (with continuous spectrum) and the solar wind plasma has been investigated. The sheath structure has been derived, taking into account anisotropic photoelectron flux with the Poisson equation, spherical geometry of the object, and half Fermi Dirac distribution of photoelectron velocities. Two cases, viz., when the object is illuminated by (i) isotropic or (ii) unidirectional (parallel beam) radiation, have been analyzed. The analysis predicts a spherically symmetric sheath in case of isotropic illumination, while a symmetry in sheath about a θ=π/4 is seen in case of parallel beam illumination; θ is the angle of incidence which is the angle made by the normal to a surface element with the direction of incidence of solar radiation. The radial and angular profiles of the electric potential and electron density in the photoelectron sheath have been evaluated and illustrated graphically; the dependence of the sheath structure on the solar wind plasma parameters, material properties of the spherical object, and its size have been discussed.
Reconstruction of magnetic domain structure using the reverse Monte Carlo method with an extended Fourier image
Authors: Tokii Maki , Kita Eiji , Mitsumata Chiharu , Ono Kanta , Yanagihara Hideto , Matsumoto Makoto
Published: April 2015

Visualization of the magnetic domain structure is indispensable to the investigation of magnetization processes and the coercivity mechanism. It is necessary to develop a reconstruction method from the reciprocal-space image to the real-space image. For this purpose, it is necessary to solve the problem of missing phase information in the reciprocal-space image. We propose the method of extend Fourier image with mean-value padding to compensate for the phase information. We visualized the magnetic domain structure using the Reverse Monte Carlo method with simulated annealing to accelerate the calculation. With this technique, we demonstrated the restoration of the magnetic domain structure, obtained magnetization and magnetic domain width, and reproduced the characteristic form that constitutes a magnetic domain.
Electronic configurations and magnetic anisotropy in organometallic metallocenes
Authors: Nawa Kenji , Kitaoka Yukie , Nakamura Kohji , Akiyama Toru , Ito Tomonori
Published: April 2015

Electronic configurations and magnetic anisotropy of organometallic metallocenes (MCp2s) were investigated by means of first principles calculations based on the constraint density functional theory. The results predict that the ground states for M = Cr, Mn, Fe, Co, and Ni are the E32g,E22g,A11g,E21g, and A32g states, respectively. The magnetizations of the CoCp2 and NiCp2 energetically favor highly orienting along the perpendicular and parallel directions to the cyclopentadienyl (Cp) plane, respectively, and the others show almost no preference for the magnetic easy axis.
Anti-damping spin transfer torque through epitaxial nickel oxide
Authors: Moriyama Takahiro , Takei So , Nagata Masaki , Yoshimura Yoko , Matsuzaki Noriko , Terashima Takahito , Tserkovnyak Yaroslav , Ono Teruo
Published: April 2015

We prepare the high quality epitaxial MgO(001)[100]/Pt(001)[100]/NiO(001)[100]/FeNi/SiO2 films to investigate the spin transport in the NiO antiferromagnetic insulator. The ferromagnetic resonance measurements of the FeNi under a spin current injection from the Pt by the spin Hall effect revealed the change of the ferromagnetic resonance linewidth depending on the amount of the spin current injection. The results can be interpreted that there is an angular momentum transfer through the NiO. A high efficient angular momentum transfer we observed in the epitaxial NiO can be attributed to the well-defined orientation of the antiferromagnetic moments and the spin quantization axis of the injected spin current.
Efficient prediction of terahertz quantum cascade laser dynamics from steady-state simulations
Authors: Agnew G. , Grier A. , Taimre T. , Lim Y. L. , Nikolić M. , Valavanis A. , Cooper J. , Dean P. , Khanna S. P. , Lachab M. , Linfield E. H. , Davies A. G. , Harrison P. , Ikonić Z. , Indjin D. , Rakić A. D.
Published: April 2015

Terahertz-frequency quantum cascade lasers (THz QCLs) based on bound-to-continuum active regions are difficult to model owing to their large number of quantum states. We present a computationally efficient reduced rate equation (RE) model that reproduces the experimentally observed variation of THz power with respect to drive current and heat-sink temperature. We also present dynamic (time-domain) simulations under a range of drive currents and predict an increase in modulation bandwidth as the current approaches the peak of the light–current curve, as observed experimentally in mid-infrared QCLs. We account for temperature and bias dependence of the carrier lifetimes, gain, and injection efficiency, calculated from a full rate equation model. The temperature dependence of the simulated threshold current, emitted power, and cut-off current are thus all reproduced accurately with only one fitting parameter, the interface roughness, in the full REs. We propose that the model could therefore be used for rapid dynamical simulation of QCL designs.
Switching times of nanoscale FePt: Finite size effects on the linear reversal mechanism
Authors: Ellis M. O. A. , Chantrell R. W.
Published: April 2015

The linear reversal mechanism in FePt grains ranging from 2.316 nm to 5.404 nm has been simulated using atomistic spin dynamics, parametrized from ab-initio calculations. The Curie temperature and the critical temperature (T*), at which the linear reversal mechanism occurs, are observed to decrease with system size whilst the temperature window T*<T<TC increases. The reversal paths close to the Curie temperature have been calculated, showing that for decreasing system size the reversal path becomes more elliptic at lower temperatures, consistent with the decrease in the Curie temperature arising from finite size effects. Calculations of the minimum pulse duration show faster switching in small grains and are qualitatively described by the Landau-Lifshitz-Bloch equation with finite size atomistic parameterization, which suggests that multiscale modeling of FePt down to a grain size of ≈3.5 nm is possible.
A metal-insulator-metal electron emitter based on a porous Al2O3 film
Authors: Xue Tao , Liang Zhi-Hu , Zhang Xiao-Ning , Liu Chun-Liang
Published: April 2015

A metal-insulator-metal electron emitter containing a sandwiched insulator layer composed of porous aluminum oxide Al2O3 was fabricated. The electron emission characteristics of the electron emitter were investigated under vacuum and xenon. Treatment with H3PO4 and rapid thermal oxidation increased the electric field inside the insulator and improved the quality of porous Al2O3, resulting in higher efficiency and less fluctuation of electron emission. The maximum current and efficiency of electron emission reached 1.05 mA/cm2 and 51.2%, respectively, under a pressure of 1.0×10−4 Pa. In addition, electrons were injected into xenon and 147 nm vacuum ultraviolet emission was detected in xenon at a pressure of 5.0 × 102 Pa. This electron emitter has a great potential for use as an ultraviolet radiation source.
Organisations and regional innovative capability: the case of the chambers of commerce and industry in Germany
Authors: Maennig Wolfgang , Ölschläger Michaela , Schmidt-Trenz Hans-Jörg
Published: April 2015

Spatial innovation models focus on the region and highlight the social and economic interactions of the actors as a main factor in regional innovative output. This paper examines the role of German chambers of commerce and industry (CCIs), which could be relevant for the innovation process through: (1) moderating or founding regional and local (innovative) initiatives; (2) creating and maintaining formal and informal networks; (3) building reputations and providing references; (4) providing information and advisory services; (5) conducting final examinations in vocational training; and (6) founding educational institutions. The empirical analyses show a positive impact of CCI expenditures on the number of start-ups and the number of patents, as well as a positive impact of seminar and information day participation on the number of start-ups. The results lead to the assumption that the network effect (functions 2 and 3) plays a more important role than providing pure information and advice (function 4).
Phylogenetic diversity within the endemic brown trout Duero lineage: implications for conservation and management
Authors: Vera M. , García-Marín J. L. , Martinez P. , Bouza C.
Published: April 2015

Brown trout display great phenotypic and genetic variability. Use of mitochondrial DNA (mtDNA) variation has allowed the definition of seven different lineages in this species to date. One of them, the Duero (DU) lineage, was initially detected in the inner section of the Duero River in Spain, where it showed a parapatric distribution with the more widely distributed Atlantic (AT) lineage. Later mtDNA-RFLP (restriction fragment length polymorphism) studies detected the DU lineage in northern Spanish basins (Galicia). The aim of this work was to ascertain the origin and variability of these DU populations outside the Duero drainage. Using complete mtDNA control region sequencing, 11 novel DU haplotypes were identified. Several of them could be assigned to an endemic group in Galicia consistent with the long-time presence of the DU lineage outside the Duero River, and excluding a recent origin by human translocations. The DU haplotype group observed in north-western Iberian basins was estimated to diverge from that of the Duero River more than 100000 years ago. We therefore advocate for conservation strategies at regional and local scales rather than focussed in a single ESU as proposed in earlier works.
Seed availability, landscape suitability and the regeneration of perennial grasses in moderately degraded rangelands in semiarid Australia
Authors: Bean Judith M. , Melville Gavin J. , Hacker Ronald B. , Clipperton Stephen P.
Published: April 2015

Two experimental sites were selected in the semiarid rangelands of north-west New South Wales, Australia. The sites had contrasting soil types and vegetation communities, but were similar in the existence of topographically high areas occupied by populations of perennial grasses. Adjacent slopes had very low numbers of perennial grass plants, indicating a moderate level of degradation. Shrubs, including Eremophila sturtii R.Br. (turpentine), were present but had not thickened to cause severe degradation. The topographically high areas were fenced as seed production areas. Replicates of a control and two cultural treatments: (1) piles of fine branches of turpentine placed along the topographic contour and (2) pits dug by a revolving metal drum, were established on the adjacent slopes. Maximum regeneration of perennial grasses took place, during favourable seasonal weather conditions, under the piles of branches on the site characterised by long gentle slopes of relatively impervious hard-setting red earths. Seed availability was not a limiting factor and a significant amount of seed was apparently sourced from the seed production areas. The piles of branches were very effective in promoting germination and survival of the perennial grasses, Monachather paradoxus Steud. and Aristida jerichoensis (Domin) Henrad, and species with large seed-retaining inflorescences, but not Thyridolepis mitchelliana (Nees) S.T. Blake. The piles of branches increased capture of seed, developed an improved seedbed and established a more mesic micro-environment and were, therefore, effective in enhancing natural landscape processes. At the site characterised by a medium-textured lithosol, even during favourable seasonal weather conditions, numbers of new plants were much lower. Pits were obliterated during the first heavy rains and the piles of branches had a negative impact on the survival of the second cohort of T. mitchelliana. At both sites, levels of germination and survival needed for regeneration of perennial grasses only occurred where a treatment effective in enhancing natural landscape processes had been established prior to favourable seasonal conditions. Pits were not effective in doing this at either site, nor for any of the perennial grass species.
Computational-guided discovery and characterization of a sesquiterpene synthase from
Streptomyces clavuligerus
Authors: Chow Jeng-Yeong , Tian Bo-Xue , Ramamoorthy Gurusankar , Hillerich Brandan S. , Seidel Ronald D. , Almo Steven C. , Jacobson Matthew P. , Poulter C. Dale
Published: April 2015

Significance

This paper describes a novel strategy for predicting the function of terpene synthases. Functional assignment of terpene synthases is a daunting task because product selectivity is not high in many terpene synthases, and mutations in and near the active sites of selective enzyme can result in synthesis of different products. Using a homology model of an unknown terpene synthase, we developed an algorithm that predicted the enzyme synthesizes a linear triquinane. We confirmed this prediction; specifically, the enzyme converts farnesyl diphosphate to a linear triquinine sesquiterpene: (5
S
,7
S
,10
R
,11
S
)-cucumene. The findings highlight the potential for using computational approaches to assist in the discovery and characterization of unknown terpene synthases.
THE GBT 67–93.6 GHz SPECTRAL LINE SURVEY OF ORION-KL
Authors: Frayer D. T. , Maddalena Ronald J. , Meijer M. , Hough L. , White S. , Norrod R. , Watts G. , Stennes M. , Simon R. , Woody D. , Srikanth S. , Pospieszalski M. , Bryerton E. , Whitehead M. , Ford P. , Mello M. , Bloss M.
Published: April 2015

We present a 67–93.6 GHz spectral line survey of Orion-KL with the new 4 mm Receiver on the Green Bank Telescope (GBT). The survey reaches unprecedented depths and covers the low-frequency end of the 3 mm atmospheric window which has been relatively unexplored previously. The entire spectral-line survey is published electronically for general use by the astronomical community. The calibration and performance of the 4 mm Receiver on the GBT is also summarized.