bluuebunny/crossref_metadata_2025 huggingface dataset:
TD-DFT calculations of UV absorption bands and their intensities in the spectra of some tetrahydroquinolines
Authors: Cooke María V. , Malvacio Ivana , Peláez Walter J. , Pepino Ana J. , Mazzieri María R. , Argüello Gustavo A.
Published: March 2015

A detailed analysis of the MOs involved in the electronic transitions of 1-benzenesulfonyl-1,2,3,4-tetrahydroquinolines is presented for the first time.
Energetic stability and photocatalytic activity of SrTiO3 nanowires: ab initio simulations
Authors: Bandura Andrei V. , Evarestov Robert A. , Zhukovskii Yuri F.
Published: March 2015

Ab initio simulations have been performed to describe, for the first time, energetic stability and photocatalytic activity of SrTiO3 nanowires.
Influence of ionic liquids as solvents for the chemical synthesis of poly(3-octylthiophene) with FeCl3
Authors: Park Tae-Joon , Kim Yong Seok , Kan Eunsung , Lee Sang Hyun
Published: March 2015

Ionic liquids were used as solvents for the oxidative polymerization of 3-octylthiophene. An excellent yield of 99% was obtained by using [BmIm][SbF6]. The effect of the IL structure on the oxidative polymerization was statistically analyzed.
The influence of various LiF concentrations on the cathodic electrochemical behavior at the tungsten electrode in Na3AlF6–Al2O3 molten salt
Authors: Tao Shaohu , Di Yuezhong , Liu Kejia , Zhao Kun , Feng Naixiang , Peng Jianping
Published: March 2015

The electrochemical deposition process of Al metal at the tungsten electrode in the melts of Na3AlF6–Al2O3 with various LiF concentrations was investigated at 1253 K by various electrochemical techniques.
Microbial cell lysis and nucleic acid extraction via nanofluidic channel
Authors: Kant Krishna , Yoo Jeongha , Amos Steven , Erkelens Mason , Priest Craig , Shapter Joe G. , Losic Dusan
Published: March 2015

This paper presents a microfluidic device with a nano-channel prepared by focused ion beam (FIB) milling for microbial cell lysis and nucleic acid extraction.
Correction: Au encapsulated into Al-MCM-41 mesoporous material: in situ synthesis and electronic structure
Authors: Fu Liangjie , Huo Chengli , He Xi , Yang Huaming
Published: March 2015

Correction for ‘Au encapsulated into Al-MCM-41 mesoporous material: in situ synthesis and electronic structure’ by Liangjie Fu et al., RSC Adv., 2015, 5, 20414–20423.
Correction: Enhanced adsorption of inorganic and organic pollutants by amine modified sodium montmorillonite nanosheets
Authors: Thirumavalavan Munusamy , Jhuang Ya-Ting , Lee Jiunn-Fwu
Published: March 2015

Correction for ‘Enhanced adsorption of inorganic and organic pollutants by amine modified sodium montmorillonite nanosheets’ by Munusamy Thirumavalavan et al., RSC Adv., 2015, 5, 20583–20594.
Highly efficient hydrogenation of carbon dioxide to formate catalyzed by iridium(iii) complexes of imine–diphosphine ligands
Authors: Liu Chong , Xie Jian-Hua , Tian Gui-Long , Li Wei , Zhou Qi-Lin
Published: March 2015

A new iridium catalyst containing an imine–diphosphine ligand was developed for the hydrogenation of CO2 to formate.
Novel polyvinylimidazolium nanoparticles as high-performance binders for lithium-ion batteries
Authors: Yuan Jiayin , Prescher Simon , Sakaushi Ken , Antonietti Markus
Published: March 2015

A series of polyvinylimidazolium-based nanoparticles were prepared via precipitation polymerization and tested as binders in cathodes of lithium ion batteries.
Förster resonance energy transfer, absorption and emission spectra in multichromophoric systems. II. Hybrid cumulant expansion
Authors: Ma Jian , Moix Jeremy , Cao Jianshu
Published: March 2015

We develop a hybrid cumulant expansion method to account for the system-bath entanglement in the emission spectrum in the multi-chromophoric Förster transfer rate. In traditional perturbative treatments, the emission spectrum is usually expanded with respect to the system-bath coupling term in both real and imaginary time. This perturbative treatment gives a reliable absorption spectrum, where the bath is Gaussian and only the real-time expansion is involved. For the emission spectrum, the initial state is an entangled state of the system plus bath. Traditional perturbative methods are problematic when the excitations are delocalized and the energy gap is larger than the thermal energy, since the second-order expansion cannot predict the displacement of the bath. In the present method, the real-time dynamics is carried out by using the 2nd-order cumulant expansion method, while the displacement of the bath is treated more accurately by utilizing the exact reduced density matrix of the system. In a sense, the hybrid cumulant expansion is based on a generalized version of linear response theory with entangled initial states.
Förster resonance energy transfer, absorption and emission spectra in multichromophoric systems. III. Exact stochastic path integral evaluation
Authors: Moix Jeremy M. , Ma Jian , Cao Jianshu
Published: March 2015

A numerically exact path integral treatment of the absorption and emission spectra of open quantum systems is presented that requires only the straightforward solution of a stochastic differential equation. The approach converges rapidly enabling the calculation of spectra of large excitonic systems across the complete range of system parameters and for arbitrary bath spectral densities. With the numerically exact absorption and emission operators, one can also immediately compute energy transfer rates using the multi-chromophoric Förster resonant energy transfer formalism. Benchmark calculations on the emission spectra of two level systems are presented demonstrating the efficacy of the stochastic approach. This is followed by calculations of the energy transfer rates between two weakly coupled dimer systems as a function of temperature and system-bath coupling strength. It is shown that the recently developed hybrid cumulant expansion (see Paper II) is the only perturbative method capable of generating uniformly reliable energy transfer rates and emission spectra across a broad range of system parameters.
Development of an interpretive simulation tool for the proton radiography technique
Authors: Levy M. C. , Ryutov D. D. , Wilks S. C. , Ross J. S. , Huntington C. M. , Fiuza F. , Martinez D. A. , Kugland N. L. , Baring M. G. , Park H.-S.
Published: March 2015

Proton radiography is a useful diagnostic of high energy density (HED) plasmas under active theoretical and experimental development. In this paper, we describe a new simulation tool that interacts realistic laser-driven point-like proton sources with three dimensional electromagnetic fields of arbitrary strength and structure and synthesizes the associated high resolution proton radiograph. The present tool’s numerical approach captures all relevant physics effects, including effects related to the formation of caustics. Electromagnetic fields can be imported from particle-in-cell or hydrodynamic codes in a streamlined fashion, and a library of electromagnetic field “primitives” is also provided. This latter capability allows users to add a primitive, modify the field strength, rotate a primitive, and so on, while quickly generating a high resolution radiograph at each step. In this way, our tool enables the user to deconstruct features in a radiograph and interpret them in connection to specific underlying electromagnetic field elements. We show an example application of the tool in connection to experimental observations of the Weibel instability in counterstreaming plasmas, using ∼108 particles generated from a realistic laser-driven point-like proton source, imaging fields which cover volumes of ∼10 mm3. Insights derived from this application show that the tool can support understanding of HED plasmas.
Fragmentation of doubly charged HDO, H2O, and D2O molecules induced by proton and monocharged fluorine beam impact at 3 keV
Authors: Martin S. , Chen L. , Brédy R. , Bernard J. , Cassimi A.
Published: March 2015

Doubly charged ions HDO2+, H2O2+, and D2O2+ were prepared selectively to triplet or singlet excited states in collisions with F+ or H+ projectiles at 3 keV. Excitation energies of dications following two-body or three-body dissociation channels were measured and compared with recent calculations using ab initio multi-reference configuration interaction method [Gervais et al., J. Chem. Phys. 131, 024302 (2009)]. For HDO2+, preferential cleavage of O–H rather than O–D bond has been observed and the ratio between the populations of the fragmentation channels OD+_H+ and OH+_D+ were measured. The kinetic energy release has been measured and compared with previous experiments.
Communication: The absolute shielding scales of oxygen and sulfur revisited
Authors: Komorovsky Stanislav , Repisky Michal , Malkin Elena , Ruud Kenneth , Gauss Jürgen
Published: March 2015

We present an updated semi-experimental absolute shielding scale for the 17O and 33S nuclei. These new shielding scales are based on accurate rotational microwave data for the spin–rotation constants of H217O [Puzzarini et al., J. Chem. Phys. 131, 234304 (2009)], C17O [Cazzoli et al., Phys. Chem. Chem. Phys. 4, 3575 (2002)], and H233S [Helgaker et al., J. Chem. Phys. 139, 244308 (2013)] corrected both for vibrational and temperature effects estimated at the CCSD(T) level of theory as well as for the relativistic corrections to the relation between the spin–rotation constant and the absolute shielding constant. Our best estimate for the oxygen shielding constants of H217O is 328.4(3) ppm and for C17O −59.05(59) ppm. The relativistic correction for the sulfur shielding of H233S amounts to 3.3%, and the new sulfur shielding constant for this molecule is 742.9(4.6) ppm.
Tetrafluoroethane (R134a) hydrate formation within variable volume reactor accompanied by evaporation and condensation
Authors: Jeong K. , Choo Y. S. , Hong H. J. , Yoon Y. S. , Song M. H.
Published: March 2015

Vast size hydrate formation reactors with fast conversion rate are required for the economic implementation of seawater desalination utilizing gas hydrate technology. The commercial target production rate is order of thousand tons of potable water per day per train. Various heat and mass transfer enhancement schemes including agitation, spraying, and bubbling have been examined to maximize the production capacities in scaled up design of hydrate formation reactors. The present experimental study focused on acquiring basic knowledge needed to design variable volume reactors to produce tetrafluoroethane hydrate slurry. Test vessel was composed of main cavity with fixed volume of 140 ml and auxiliary cavity with variable volume of 0 ∼ 64 ml. Temperatures at multiple locations within vessel and pressure were monitored while visual access was made through front window. Alternating evaporation and condensation induced by cyclic volume change provided agitation due to density differences among water and vapor, liquid and hydrate R134a as well as extended interface area, which improved hydrate formation kinetics coupled with latent heat release and absorption. Influences of coolant temperature, piston stroke/speed, and volume change period on hydrate formation kinetics were investigated. Suggestions of reactor design improvement for future experimental study are also made.
2-D energy analyzer for low energy electrons
Authors: Karkare Siddharth , Cultrera Luca , Hwang Yoon-Woo , Merluzzi Richard , Bazarov Ivan
Published: March 2015

A 2-D electron energy analyzer is designed and constructed to measure the transverse and longitudinal energy distribution of low energy (<1 eV) electrons. The analyzer operates on the principle of adiabatic invariance and motion of low energy electrons in a strong longitudinal magnetic field. The operation of the analyzer is studied in detail and a design to optimize the energy resolution, signal to noise ratio, and physical size is presented. An energy resolution better than 6 meV has been demonstrated. Such an analyzer is a powerful tool to study the process of photoemission which limits the beam quality in modern accelerators.
Development of pulsed neutron uranium logging instrument
Authors: Wang Xin-guang , Liu Dan , Zhang Feng
Published: March 2015

This article introduces a development of pulsed neutron uranium logging instrument. By analyzing the temporal distribution of epithermal neutrons generated from the thermal fission of 235U, we propose a new method with a uranium-bearing index to calculate the uranium content in the formation. An instrument employing a D-T neutron generator and two epithermal neutron detectors has been developed. The logging response is studied using Monte Carlo simulation and experiments in calibration wells. The simulation and experimental results show that the uranium-bearing index is linearly correlated with the uranium content, and the porosity and thermal neutron lifetime of the formation can be acquired simultaneously.
Gas-focused liquid microjets from a slit
Authors: Li Cheng , Krueger Kappy , Yang Weiwei , Duan Hongxu , Deng Weiwei
Published: March 2015

We report an experimental study on a new arrangement of flow focusing that uses a slit aperture. The slit can achieve similar flow chocking function as a classic circular aperture to established gas flow pressure drop. Fundamentally, the jetting mechanism and quantitative behavior of slit flow focusing are very similar to the classic flow focusing because of the singularity nature of the jet despite the drastically different aperture shapes. After re-scaling the jet shape, the axial coordinate with the hydraulic diameter of the slit, the experimental data follow closely with the universal jet profile derived in Gañán-Calvo, Ferrera, and Montanero [“Universal size and shape of viscous capillary jets: Application to gas-focused microjets,” J. Fluid Mech. 670, 427-438 (2011)] based on circular aperture. Practically, the slit configuration expands the possibility of manipulating the jets. The two thin plates that form the slit aperture can also be used as electrodes to apply electrohydrodynamic excitation to the jet for controlled jet breakup with narrower droplet size distribution. In addition, the modest throughput of a single flow focused jet can be increased by operating a linear array of jets focused and excited by the same slit.
Effective bond orders from two-step spin–orbit coupling approaches: The I2, At2, IO+, and AtO+ case studies
Authors: Maurice Rémi , Réal Florent , Gomes André Severo Pereira , Vallet Valérie , Montavon Gilles , Galland Nicolas
Published: March 2015

The nature of chemical bonds in heavy main-group diatomics is discussed from the viewpoint of effective bond orders, which are computed from spin–orbit wave functions resulting from spin–orbit configuration interaction calculations. The reliability of the relativistic correlated wave functions obtained in such two-step spin–orbit coupling frameworks is assessed by benchmark studies of the spectroscopic constants with respect to either experimental data, or state-of-the-art fully relativistic correlated calculations. The I2, At2, IO+, and AtO+ species are considered, and differences and similarities between the astatine and iodine elements are highlighted. In particular, we demonstrate that spin–orbit coupling weakens the covalent character of the bond in At2 even more than electron correlation, making the consideration of spin–orbit coupling compulsory for discussing chemical bonding in heavy (6p) main group element systems.
A simple way to test for collinearity in spin symmetry broken wave functions: General theory and application to generalized Hartree Fock
Authors: Small David W. , Sundstrom Eric J. , Head-Gordon Martin
Published: March 2015

We introduce a necessary and sufficient condition for an arbitrary wavefunction to be collinear, i.e., its spin is quantized along some axis. It may be used to obtain a cheap and simple computational procedure to test for collinearity in electronic structure theory calculations. We adapt the procedure for Generalized Hartree Fock (GHF), and use it to study two dissociation pathways in CO2. For these dissociation processes, the GHF wave functions transform from low-spin Unrestricted Hartree Fock (UHF) type states to noncollinear GHF states and on to high-spin UHF type states, phenomena that are succinctly illustrated by the constituents of the collinearity test. This complements earlier GHF work on this molecule.
Switchable Q-switched and modelocked operation in ytterbium doped fiber laser under all-normal-dispersion configuration
Authors: Mukhopadhyay Pranb K. , Gupta Pradeep K. , Singh Chandra Pal , Singh Amarjeet , Sharma Sunil K. , Bindra Kushvinder S. , Oak Shrikant M.
Published: March 2015

We have constructed an Yb-doped fiber laser in all-normal-dispersion configuration which can be independently operated in Q-switched or modelocked configuration with the help of a simple fiber optic ring resonator (FORR). In the presence of FORR, the laser operates in Q-switched mode producing stable pulses in the range of 1 μs-200 ns with repetition rate in the range of 45 kHz-82 kHz. On the other hand, the laser can be easily switched to mode-locked operation by disjoining the FORR loop producing train of ultrashort pulses of ∼5 ps duration (compressible to ∼150 fs) at ∼38 MHz repetition rate. The transmission characteristics of FORR in combination with the nonlinear polarization rotation for passive Q-switching operation is numerically investigated and experimentally verified. The laser can serve as a versatile seed source for power amplifier which can be easily configured for application in the fields that require different pulsed fiber lasers.
Ferroelectric and magnetic properties of multiferroic BiFeO3-La0.7Sr0.3MnO3 heterostructures integrated with Si (100)
Authors: Singamaneni Srinivasa Rao , Prater J. T. , Nori S. , Kumar D. , Lee Bongmook , Misra V. , Narayan J.
Published: March 2015

We report on the electrical, ferroelectric, and magnetic properties of BiFeO3 (BFO)-La0.7Sr0.3MnO3 heterostructures deposited epitaxially onto Si(100) substrates. Temperature dependent (200–350 K) current-voltage (I-V), switching spectroscopy piezo-response force microscopy (SSPFM), and temperature dependent (5–300 K) anisotropic magnetization measurements have been performed. The BFO (100-nm thick)-based device structures were fabricated with a 250 nm thick La0.7Sr0.3MnO3 bottom electrode and 200 μm circular top Pt electrodes. I-V measurements performed at various temperatures indicated that the devices retained their as-deposited characteristics and exhibited non-leaky behavior up to at least 50 cycles. The temperature-dependent measurements showed clear diode-like behavior and resistive (hysteretic) switching behaviour. Characteristic butterfly loops (of several cycles) were observed in the PFM amplitude signals of the BFO film. In addition, the phase signal indicated a clear (180°) switching behavior at the switching voltage of 4–5 V, providing unambiguous evidence for the occurrence of ferroelectricity in BFO films integrated on Si (100). The temperature- and angle-dependent zero field cooled isothermal (5 K) magnetization measurements were consistent with the presence of uniaxial magnetic anisotropy. This work makes an important step for the fabrication of CMOS-compatible BFO devices for memory applications.
Influence of tensile stress on permeability properties of type 304 stainless steel
Authors: Kinoshita K.
Published: March 2015

The permeability properties of type SUS304 stainless steel (SUS304 steel) were evaluated under different values of tensile stress using the electromagnetic impedance method. The impedance–magnetic-field curve of SUS304 steel, which corresponds to the permeability–magnetic field-curve, was measured under tensile stresses of 0, 70, and 140 MPa for specimens subjected to prestrains of 5% to 40% to change the martensite fraction. The impedance curves were measured in the length (tensile) direction and the width direction. The results showed that the tensile direction was the magnetic hard axis of the martensite phase in SUS304 steel. The applied stress sensitivity of the permeability in SUS304 steel was affected by the volume fraction, residual stress, stress distribution according to the orientation angle of the martensite phase, and their interactions.
Macroscopic spin-orbit coupling in non-uniform magnetic fields
Authors: Tabat N. , Edelman H. S. , Song D. , Vogt T.
Published: March 2015

Translational dynamics of aggregated magnetic nano-particles placed in a rotating external magnetic field is described. It is observed and explained that aggregates that spin within a radially decreasing field strength must execute an orbital motion of their center of mass in a sense that counters their spin rotation. This orbital motion is tightly coupled to the spin dynamics of the aggregates. An analytical model for the canonical variables describing the orbital motion is derived and shown to be in good agreement with the measured values.
Influence of temperature on the magnetic properties of electroplated L1 CoPt thick films
Authors: Garraud Alexandra , Oniku Ololade D. , Arnold David P.
Published: March 2015

This paper reports the magnetic properties of 2 μm thick electroplated isotropic L10 CoPt films on silicon at temperatures ranging from 300 K to 790 K, as well as the room-temperature properties of the films after various thermal cycles. Electroplated equiatomic CoPt layers require a post-deposition annealing typically at ∼973 K to induce L10 ordering so that they exhibit hard magnetic properties at room temperature. However, the influence of temperature on these post-deposition annealed films is an important consideration for their utility in end applications. Here, a reversible temperature coefficient of remanence of −0.11% K−1 is measured along with a maximum operating temperature of 400 K (recovery to 95% of the initial remanence). The maximal energy density of the films is reduced by 50% at a temperature of 550 K. However, the original room-temperature magnetic properties are shown to be fully recoverable by remagnetization after various thermal cycles—800 K for 15 min in Ar, 373 K for 168 h in air, and 358 K for 168 h in air at 85% relative humidity. These investigations indicate that the electroplated L10 CoPt layers, like bulk, exhibit good thermal robustness, satisfying a key requirement for their use in end applications, such as magnetic microsystems.
A detailed microscopic study of the heat transfer at a water gold interface coated with a polymer
Authors: Soussi J. , Volz S. , Palpant B. , Chalopin Y.
Published: March 2015

We investigate in detail the mechanisms of heat relaxation at a gold:water interface and address the effect of a polymer (DHLA-Jeffamine) coated at the surface. We demonstrate that above a low surface density limit, the adjunction of polymers significantly enhances the interface conductance from the metal to the fluid. From molecular dynamics simulations, we have computed the corresponding increase of thermal conductance. The physical origin of this effect is analyzed in terms of transmission spectra. Transient non-equilibrium simulations finally compare the profile of the thermal field generated with and without the polymer.
Impact of x-ray dose on the response of CR-39 to 1–5.5 MeV alphas
Authors: Rojas-Herrera J. , Rinderknecht H. G. , Zylstra A. B. , Gatu Johnson M. , Orozco D. , Rosenberg M. J. , Sio H. , Seguin F. H. , Frenje J. A. , Li C. K. , Petrasso R. D.
Published: March 2015

The CR-39 nuclear track detector is used in many nuclear diagnostics fielded at inertial confinement fusion (ICF) facilities. Large x-ray fluences generated by ICF experiments may impact the CR-39 response to incident charged particles. To determine the impact of x-ray exposure on the CR-39 response to alpha particles, a thick-target bremsstrahlung x-ray generator was used to expose CR-39 to various doses of 8 keV Cu-Kα and Kβ x-rays. The CR-39 detectors were then exposed to 1–5.5 MeV alphas from an Am-241 source. The regions of the CR-39 exposed to x-rays showed a smaller track diameter than those not exposed to x-rays: for example, a dose of 3.0 ± 0.1 Gy causes a decrease of (19 ± 2)% in the track diameter of a 5.5 MeV alpha particle, while a dose of 60.0 ± 1.3 Gy results in a decrease of (45 ± 5)% in the track diameter. The reduced track diameters were found to be predominantly caused by a comparable reduction in the bulk etch rate of the CR-39 with x-ray dose. A residual effect depending on alpha particle energy is characterized using an empirical formula.
Communication: Observation of dipole-bound state and high-resolution photoelectron imaging of cold acetate anions
Authors: Huang Dao-Ling , Zhu Guo-Zhu , Wang Lai-Sheng
Published: March 2015

We report the observation of a dipole-bound state and a high-resolution photoelectron imaging study of cryogenically cooled acetate anions (CH3COO−). Both high-resolution non-resonant and resonant photoelectron spectra via the dipole-bound state of CH3COO− are obtained. The binding energy of the dipole-bound state relative to the detachment threshold is determined to be 53 ± 8 cm−1. The electron affinity of the CH3COO neutral radical is measured accurately as 26 236 ± 8 cm−1 (3.2528 ± 0.0010 eV) using high-resolution photoelectron imaging. This accurate electron affinity is validated by observation of autodetachment from two vibrational levels of the dipole-bound state of CH3COO−. Excitation spectra to the dipole-bound states yield rotational profiles, allowing the rotational temperature of the trapped CH3COO− anions to be evaluated.
Communication: Equilibrium rate coefficients from atomistic simulations: The O(3P) + NO(2Π) → O2(X3Σg−) + N(4S) reaction at temperatures relevant to the hypersonic flight regime
Authors: Castro-Palacio Juan Carlos , Bemish Raymond J. , Meuwly Markus
Published: March 2015

The O(3P) + NO(2Π) → O2(X3Σg−) + N(4S) reaction is among the N- and O- involving reactions that dominate the energetics of the reactive air flow around spacecraft during hypersonic atmospheric re-entry. In this regime, the temperature in the bow shock typically ranges from 1000 to 20 000 K. The forward and reverse rate coefficients for this reaction derived directly from trajectory calculations over this range of temperature are reported in this letter. Results compare well with the established equilibrium constants for the same reaction from thermodynamic quantities derived from spectroscopy in the gas phase which paves the way for large-scale in silico investigations of equilibrium rates under extreme conditions.
Demonstration of neutron detection utilizing open cell foam and noble gas scintillation
Authors: Lavelle C. M. , Coplan M. , Miller E. C. , Thompson Alan K. , Kowler A. L. , Vest Robert E. , Yue A. T. , Koeth T. , Al-Sheikhly M. , Clark Charles W.
Published: March 2015

We present results demonstrating neutron detection via a closely spaced converter structure coupled to low pressure noble gas scintillation instrumented by a single photo-multiplier tube (PMT). The converter is dispersed throughout the gas volume using a reticulated vitreous carbon foam coated with boron carbide (B4C). A calibrated cold neutron beam is used to measure the neutron detection properties, using a thin film of enriched 10B as a reference standard. Monte Carlo computations of the ion energy deposition are discussed, including treatment of the foam random network. Results from this study indicate that the foam shadows a significant portion of the scintillation light from the PMT. The high scintillation yield of Xe appears to overcome the light loss, facilitating neutron detection and presenting interesting opportunities for neutron detector design.
Generation of electromagnetic waves from 0.3 to 1.6 terahertz with a high-Tc superconducting Bi2Sr2CaCu2O8+δ intrinsic Josephson junction emitter
Authors: Kashiwagi Takanari , Yamamoto Takashi , Kitamura Takeo , Asanuma Kentaro , Watanabe Chiharu , Nakade Kurama , Yasui Takaki , Saiwai Yoshihiko , Shibano Yuuki , Kubo Hiroyuki , Sakamoto Kazuki , Katsuragawa Takuya , Tsujimoto Manabu , Delfanazari Kaveh , Yoshizaki Ryozo , Minami Hidetoshi , Klemm Richard A. , Kadowaki Kazuo
Published: March 2015

To obtain higher power P and frequency f emissions from the intrinsic Josephson junctions in a high-Tc superconducting Bi2Sr2CaCu2O8+δ single crystal, we embedded a rectangular stand-alone mesa of that material in a sandwich structure to allow for efficient heat exhaust. By varying the current-voltage (I-V) bias conditions and the bath temperature Tb, f is tunable from 0.3 to 1.6 THz. The maximum P of a few tens of μW, an order of magnitude greater than from previous devices, was found at Tb∼55 K on an inner I-V branch at the TM(1,0) cavity resonance mode frequency. The highest f of 1.6 THz was found at Tb=10 K on an inner I–V branch, but away from cavity resonance frequencies. A possible explanation is presented.
Simple characterization of electronic processes in perovskite photovoltaic cells
Authors: Miyano Kenjiro , Yanagida Masatoshi , Tripathi Neeti , Shirai Yasuhiro
Published: March 2015

Electronic properties of perovskite lead-halide photovoltaic cells have been studied. The dc current/voltage characteristics were found to be well fitted by a standard diode equation under optical excitation and in the dark, while the impedance spectroscopy revealed a pronounced slow process under light illumination, which is absent in the dark. A simple model is proposed, which can explain all aspects of the observed behavior quantitatively and consistently.
Observations of imposed ordered structures in a dusty plasma at high magnetic field
Authors: Thomas Edward , Lynch Brian , Konopka Uwe , Merlino Robert L. , Rosenberg Marlene
Published: March 2015

Dusty plasmas have been studied in argon, rf glow discharge plasmas at magnetic fields up to 2 T, where the electrons and ions are strongly magnetized. In this experiment, plasmas are generated between two parallel plate electrodes where the lower, powered electrode is solid and the upper, electrically floating electrode supports a semi-transparent, titanium mesh. We report on the formation of an ordered dusty plasma, where the dust particles form a spatial structure that is aligned to the mesh. We discuss possible mechanisms that may lead to the formation of the “dust grid” and point out potential implications and applications of these observations.
Gate-tunable photocurrent in ZnO nanowires mediated by nanowire-substrate interface states
Authors: Yang Liangliang , Wang Qiaoming , Tao Xin , Taylor Shelby P. , Gu Yi
Published: March 2015

We report the observation of gate-tunable photocurrent in ZnO nanowires under optical excitation in the visible regime. Particularly, the photocurrent can be tuned by one order of magnitude with moderate changes in the backgate voltages (from −10 V to 10 V), and by more than two orders of magnitude within an extended range of the backgate voltage (several tens of volts). Using scanning photocurrent microscopy, single-nanowire photocurrent spectroscopy, and numerical calculations, we suggest that this gate tunability originates from the nanowire/substrate (Si3N4) interface states, where the electron occupation of these states and the excitation of electrons are controlled by the backgate voltage. This external gate tunability of the photocarrier generation facilitated by interface states provides an additional way to control photodetecting and photovoltaic properties, and this approach can also be extended to other nanostructures, such as two-dimensional semiconductors, where the surface effects are significant.
Spin-orbit torque induced spike-timing dependent plasticity
Authors: Sengupta Abhronil , Al Azim Zubair , Fong Xuanyao , Roy Kaushik
Published: March 2015

Nanoelectronic devices that mimic the functionality of synapses are a crucial requirement for performing cortical simulations of the brain. In this work, we propose a ferromagnet-heavy metal heterostructure that employs spin-orbit torque to implement spike-timing dependent plasticity. The proposed device offers the advantage of decoupled spike transmission and programming current paths, thereby leading to reliable operation during online learning. Possible arrangement of such devices in a crosspoint architecture can pave the way for ultra-dense neural networks. Simulation studies indicate that the device has the potential of achieving pico-Joule level energy consumption (maximum 2 pJ per synaptic event) which is comparable to the energy consumption for synaptic events in biological synapses.
Manipulation of nanoscale V-pits to optimize internal quantum efficiency of InGaN multiple quantum wells
Authors: Chang Chiao-Yun , Li Heng , Shih Yang-Ta , Lu Tien-Chang
Published: March 2015

We systematically investigated the influence of nanoscale V-pits on the internal quantum efficiency (IQE) of InGaN multiple quantum wells (MQWs) by adjusting the underlying superlattices (SLS). The analysis indicated that high barrier energy of sidewall MQWs on V-pits and long diffusion distance between the threading dislocation (TD) center and V-pit boundary were crucial to effectively passivate the non-radiative centers of TDs. For a larger V-pit, the thicker sidewall MQW on V-pit would decrease the barrier energy. On the contrary, a shorter distance between the TD center and V-pit boundary would be observed in a smaller V-pit, which could increase the carrier capturing capability of TDs. An optimized V-pit size of approximately 200–250 nm in our experiment could be concluded for MQWs with 15 pairs SLS, which exhibited an IQE value of 70%.
Force-rebalanced Lorentz force magnetometer based on a micromachined oscillator
Authors: Sonmezoglu S. , Li M. , Horsley D. A.
Published: March 2015

This paper presents a 3-axis Lorentz force magnetometer based on an encapsulated micromechanical silicon resonator having three orthogonal vibration modes, each measuring one vector component of the external magnetic field. One mode, with natural frequency (fn) of 46.973 kHz and quality factor (Q) of 14 918, is operated as a closed-loop electrostatically excited oscillator to provide a frequency reference for 3-axis sensing and Lorentz force generation. Current, modulated at the reference frequency, is injected into the resonator, producing Lorentz force that is centered at the reference frequency. Lorentz force in the first axis is nulled by the oscillator loop, resulting in force-rebalanced operation. The bandwidth and scale-factor of this force-rebalanced axis are independent of resonator Q, improving the sensor's temperature coefficient from 20 841 ppm/ °C to 424 ppm/ °C. The frequencies of the other two modes are closely spaced to the first mode's reference frequency and are demonstrated to track this frequency over temperature within 1 ppm/K. Field measurements in these two axes are conducted open-loop and off-resonance, ensuring that the scale-factor is independent of Q to first order and producing a measurement bandwidth of over 40 Hz.
Development of an Australian practice-based research network as a community of practice
Authors: Dijkmans-Hadley Bridget , Bonney Andrew , Barnett Stephen R.
Published: March 2015

There are many aspects of the communities of practice (CoP) framework that are applicable to the development of a practice-based research network (PBRN), where the focus is upon building primary health-care workers’ research capacity and research questions. However, there is limited literature focussed on the application of CoP principles applied to research capacity building in Australia. The purpose of this paper is to demonstrate, through a case study, how a developing PBRN, the Illawarra and Southern Practice Research Network, successfully applied the theoretical foundation of CoP to develop a PBRN in a time- and resource-limited context.
Australian academic primary health-care careers: a scoping survey
Authors: Barton Christopher , Reeve Joanne , Adams Ann , McIntyre Ellen
Published: March 2015

This study was undertaken to provide a snapshot of the academic primary health-care workforce in Australia and to provide some insight into research capacity in academic primary health care following changes to funding for this sector. A convenience sample of individuals self-identifying as working within academic primary health care (n = 405) completed an anonymous online survey. Respondents were identified from several academic primary health-care mailing lists. The survey explored workforce demographics, clarity of career pathways, career trajectories and enablers/barriers to ‘getting in’ and ‘getting on’. A mix of early career (41%), mid-career (25%) and senior academics (35%) responded. Early career academics tended to be female and younger than mid-career and senior academics, who tended to be male and working in ‘balanced’ (teaching and research) roles and listing medicine as their disciplinary background. Almost three-quarters (74%) indicated career pathways were either ‘completely’ or ‘somewhat unclear’, irrespective of gender and disciplinary backgrounds. Just over half (51%) had a permanent position. Males were more likely to have permanent positions, as were those with a medical background. Less than half (43%) reported having a mentor, and of the 57% without a mentor, more than two-thirds (69%) would like one. These results suggest a lack of clarity in career paths, uncertainty in employment and a large number of temporary (contract) or casual positions represent barriers to sustainable careers in academic primary health care, especially for women who are from non-medicine backgrounds. Professional development or a mentoring program for primary health-care academics was desired and may address some of the issues identified by survey respondents.
Assessing potential effects of land use and climate change on mammal distributions in northern Thailand
Authors: Trisurat Yongyut , Kanchanasaka Budsabong , Kreft Holger
Published: March 2015

Context
Tropical ecosystems are widely recognised for their high species richness and outstanding concentrations of rare and endemic species. Previous studies either focussed on the effects of deforestation or climate change, whereas studies on the combined effects of these two major threats are limited.

Aims
This research aimed to model current and future distributions of medium- to large-sized mammal species on the basis of different land-use and climate-change scenarios in 2050 and to assess whether the predicted effects of land-use change are greater than those of climate change and whether the combined effects of these drivers are greater than those of either individual driver.

Methods
The present article demonstrates a method for combining nationwide wildlife-inventory data, spatially explicit species-distribution models, current and predicted future bioclimatic variables, other biophysical factors and human disturbance to map distributions of mammal species on the basis of different land-use and climate-change scenarios and to assess the role of protected areas in conservation planning.

Key results
Seventeen medium- to large-sized mammal species were selected for modelling. Most selected species were predicted to lose suitable habitat if the remaining forest cover declines from the current level of 57% to 50% in 2050. The predicted effects of deforestation were stronger than the effects of climate change. When climate and land-use change were combined, the predicted impacts were more severe. Most species would lose suitable habitat and the average shift in species distribution was greater than 40%.

Conclusions
The predicted effects were positive for only a few species and negative for most species. Current and future centres of mammal-species richness were predicted in large and contiguous protected forests and the average contribution of existing and proposed protected areas in protecting the focal species will increase from 73% to 80% across all scenarios.

Implications
The present research advances the current understanding of the ecology of 17 medium- to large-sized mammal species with conservation relevance and the factors that affect their distributions at the landscape scale. In addition, the research demonstrated that spatially explicit models and protected areas are effective means to contribute to protection of mammal species in current and future land-use and climate-change scenarios.
Assessment of ABT-263 activity across a cancer cell line collection leads to a potent combination therapy for small-cell lung cancer
Authors: Faber Anthony C. , Farago Anna F. , Costa Carlotta , Dastur Anahita , Gomez-Caraballo Maria , Robbins Rebecca , Wagner Bethany L. , Rideout William M. , Jakubik Charles T. , Ham Jungoh , Edelman Elena J. , Ebi Hiromichi , Yeo Alan T. , Hata Aaron N. , Song Youngchul , Patel Neha U. , March Ryan J. , Tam Ah Ting , Milano Randy J. , Boisvert Jessica L. , Hicks Mark A. , Elmiligy Sarah , Malstrom Scott E. , Rivera Miguel N. , Harada Hisashi , Windle Brad E. , Ramaswamy Sridhar , Benes Cyril H. , Jacks Tyler , Engelman Jeffrey A.
Published: March 2015

Significance

Small-cell lung cancer (SCLC) is an aggressive carcinoma with few effective treatment options beyond first-line chemotherapy. BH3 mimetics, such as ABT-263, promote apoptosis in SCLC cell lines, but early phase clinical trials demonstrated no significant clinical benefit. Here, we examine the sensitivity of a large panel of cancer cell lines, including SCLC, to ABT-263 and find that high Bcl2-interacting mediator of cell death (BIM) and low myeloid cell leukemia 1 (MCL-1) expression together predict sensitivity. SCLC cells relatively resistant to ABT-263 are sensitized by TORC1/2 inhibition via MCL-1 reduction. Combination of ABT-263 and TORC1/2 inhibition stabilizes or shrinks tumors in xenograft models, in autochthonous SCLC tumors in a genetically engineered mouse model, and in a patient-derived xenograft SCLC model. Collectively, these data support a compelling new therapeutic strategy for treating SCLC.
Quorum-sensing
Salmonella
selectively trigger protein expression within tumors
Authors: Swofford Charles A. , Van Dessel Nele , Forbes Neil S.
Published: March 2015

Significance

Nonpathogenic
Salmonella
localize to tumors and can be engineered to secrete anticancer proteins, but tumor-specific expression is essential to prevent systemic toxicity. To reduce unwanted side effects in healthy tissue, we integrated
Salmonella
with a quorum-sensing (QS) switch that only initiates drug expression in the tightly packed colonies present within tumors. Using an in vitro 3D-tumor-on-a-chip device and in vivo mouse models, we show that QS
Salmonella
specifically initiates protein expression within cancerous tissue while remaining uninduced in livers. Protein expression was triggered when inducer molecules from enough close neighbors reached a critical concentration. Because of these selective qualities, QS
Salmonella
are a promising tool for tumor-specific delivery of therapeutic proteins.
Genomically amplified Akt3 activates DNA repair pathway and promotes glioma progression
Authors: Turner Kristen M. , Sun Youting , Ji Ping , Granberg Kirsi J. , Bernard Brady , Hu Limei , Cogdell David E. , Zhou Xinhui , Yli-Harja Olli , Nykter Matti , Shmulevich Ilya , Yung W. K. Alfred , Fuller Gregory N. , Zhang Wei
Published: March 2015

Significance

Glioblastoma is the most common and aggressive type of glioma, with a median survival of 15 mo. A major obstacle to effective treatment is de novo or acquired resistance to standard-care therapies, including radiation and temozolomide. Enhanced DNA repair can allow damaged or mutated cells to survive, contributing to resistance and tumor recurrence. We have identified Akt3 as the dominant Akt isoform that robustly stimulates glioma progression. We also discovered key roles for Akt3 in activating DNA repair pathways, which led to enhanced survival of human glioblastoma cells following radiation or temozolomide treatment. Our work has potential broad application to multiple cancer types in which Akt3 is expressed. Blocking this pathway may help prevent or alleviate DNA repair-mediated therapeutic resistance.
Locating landmarks on high-dimensional free energy surfaces
Authors: Chen Ming , Yu Tang-Qing , Tuckerman Mark E.
Published: March 2015

Significance

The problem of generating and navigating high-dimensional free energy surfaces is a significant challenge in the study of complex systems. The approach introduced represents an advance in this area, and its ability to generate and organize the key features of a high-dimensional free energy surface, i.e., its landmarks, with high efficiency impacts numerous problems in the materials and biomolecular sciences for which prediction of optimal structures is key. These include polypeptide and nucleic acid structure and crystal design and structure prediction. Moreover, as the algorithm targets the free energy surface, candidate structures can be ranked based on their relative free energies, which is not possible with algorithms that target only the bare potential energy surface.
Salient features of otoacoustic emissions are common across tetrapod groups and suggest shared properties of generation mechanisms
Authors: Bergevin Christopher , Manley Geoffrey A. , Köppl Christine
Published: March 2015

Significance

Healthy ears not only detect sound but can emit it as well. These sounds can occur either spontaneously and continuously or in response to acoustic stimulation. Evoked emissions are increasingly used as clinical diagnostic tools. The mechanisms underlying their generation, however, are incompletely understood. In particular, otoacoustic emissions occur in a wide variety of species, from frogs to humans, suggesting basic, shared principles. Here, we analyzed both spontaneous and evoked otoacoustic emissions from a bird and a lizard. We relate these data to those from humans and suggest that otoacoustic emissions originate from similar biomechanical principles despite gross differences in the underlying anatomy of the ear.
Structure and dynamics of the MKK7–JNK signaling complex
Authors: Kragelj Jaka , Palencia Andrés , Nanao Max H. , Maurin Damien , Bouvignies Guillaume , Blackledge Martin , Jensen Malene Ringkjøbing
Published: March 2015

Significance

In the mitogen-activated protein kinase (MAPK) pathways, N-terminal intrinsically disordered regulatory domains of the MAPK kinases (MKK) control signaling specificity by binding to their cognate MAPKs via docking sites carrying homologous recognition sequences. MKK7 activates the c-Jun N-terminal kinase (JNK) pathway and is the only MKK containing three motifs within its regulatory domain. Here we obtain a comprehensive picture of the structure, dynamics, affinity, stoichiometry, and kinetics of the MKK7–JNK signaling complex. Importantly, we show using a combination of X-ray crystallography and NMR exchange spectroscopy that the second docking site of MKK7 binds to JNK via two alternative binding modes, providing insight into the regulation of signaling specificity by short linear motifs.
Retroviral vectors elevate coexpressed protein levels in
trans
through cap-dependent translation
Authors: Gou Yongqiang , Byun Hyewon , Zook Adam E. , B. Singh Gurvani , Nash Andrea K. , Lozano Mary M. , Dudley Jaquelin P.
Published: March 2015

Significance

Translation is a key process that is regulated by cellular health and responses to the environment, including virus infection. We show here that introduction of lentivirus and gammaretroviral vectors into cells by transfection increased translation (superinduction) of cotransfected genes but not most endogenous proteins. Superinduction was independent of the unfolded protein, stress, and interferon responses and did not require retroviral vector transcription. Retroviral vectors elevated cap-dependent translation initiation without increased mammalian target of rapamycin (mTOR) kinase activity. Thus, DNA sequences from HIV-1 and other retroviruses increase translation of cotransfected genes in
trans
by mTOR complex 1-independent signaling. Our results suggest that retroviral DNA manipulates translation, which has practical implications for protein expression and design of vectors for transfection assays, DNA vaccines, and shRNA knockdown experiments.