bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and assessment of photoluminescent properties of Ca4−2xAl6WO16:REx,Nax (RE = Eu3+, Dy3+ and Sm3+) phosphors
Authors: Dabre K. V. , Dhoble S. J.
Published: July 2015

The emission hue of rare earth (Eu3+, Dy3+ and Sm3+) activated Ca4Al6WO16 phosphors could be tuned from orange-red to near white by selecting proper activator.
Synthesis, characterisation and application of imidazolium based ionic liquid modified montmorillonite sorbents for the removal of amaranth dye
Authors: Lawal Isiaka A. , Moodley Brenda
Published: July 2015

The removal of amaranth dye using montmorillonite modified with an ionic liquid (IL) was investigated.
Asymmetric and symmetric solid-state supercapacitors based on 3D interconnected polyaniline–carbon nanotube framework
Authors: Khalid Mohd. , Tumelero Milton A. , Pasa Andre A.
Published: July 2015

In this work, we demonstrate multiwalled carbon nanotube (MWCNT)-assisted polyaniline (PANI) thin films to improve supercapacitor performance.
DBU-promoted cyclization of vinyl isocyanides with ethers via the functionalization of a C(sp3)–H bond for the synthesis of isoquinolines
Authors: Qian Ping , Du Bingnan , Zhou Jie , Mei Haibo , Han Jianlin , Pan Yi
Published: July 2015

A DBU-promoted cascade functionalization of a C(sp3)–H bond adjacent to oxygen and a radical cyclization reaction of vinyl isocyanides was developed to easily access multi-functionalized isoquinolines.
Synthesis and characterization of novel biobased benzoxazines from cardbisphenol and the properties of their polymers
Authors: Li Shengfang , Yan Shilin
Published: July 2015

Two types of novel biobased benzoxazine monomers (named as CBB and CBF, respectively) from cardbisphenol were synthesized by a solventless method.
Gold nanoclusters based dual-emission hollow TiO2 microsphere for ratiometric optical thermometry
Authors: Wang Chuanxi , Huang Yijun , Lin Huihui , Xu Zhenzhu , Wu Jiapeng , Humphrey Mark G. , Zhang Chi
Published: July 2015

The dual-emitting hollow TiO2 microspheres are prepared and they show dual emission fluorescence with single-excitation, which could be used as nanosensors for accurate measurement of temperature over the wide temperature range (20–80 °C).
Lysozyme adsorption in pH-responsive hydrogel thin-films: the non-trivial role of acid–base equilibrium
Authors: Narambuena Claudio F. , Longo Gabriel S. , Szleifer Igal
Published: July 2015

Protein adsorption on pH responsive gels shows emergent behavior due to the coupling between molecular organization, physical interaction and chemical equilibrium in soft confined materials.
Adsorption of rationally designed “surf-tides” to a liquid-crystal interface
Authors: Badami Joseph V. , Bernstein Chaim , Maldarelli Charles , Tu Raymond S.
Published: July 2015

The liquid crystal platform provides a sensitive and quantitative tool for the detection of peptide adsorption kinetics.
A porous metal–organic framework formed by a V-shaped ligand and Zn(ii) ion with highly selective sensing for nitroaromatic explosives
Authors: He Hongming , Song Yang , Sun Fuxing , Bian Zheng , Gao Lianxun , Zhu Guangshan
Published: July 2015

A porous MOF is used to detect nitroaromatic explosives by fluorescence quenching and spectral shift. It is amongst the most efficient porous material-based sensors for TNP.
Pyridomethene–BF2 complex/phenothiazine hybrid sensitizer with high molar extinction coefficient for efficient, sensitized solar cells
Authors: Lin Yan-Duo , Ke Bo-Yu , Chang Yuan Jay , Chou Po-Ting , Liau Kang-Ling , Liu Ching-Yang , Chow Tahsin J.
Published: July 2015

Organic dyes containing both phenothiazine and pyridomethene–BF2 moieties displayed the highest power-conversion efficiency 6.58% under AM 1.5G irradiation condition.
Ultra low band gap α,β-unsubstituted BODIPY-based copolymer synthesized by palladium catalyzed cross-coupling polymerization for near infrared organic photovoltaics
Authors: Squeo Benedetta M. , Gasparini Nicola , Ameri Tayebeh , Palma-Cando Alex , Allard Sybille , Gregoriou Vasilis G. , Brabec Christoph J. , Scherf Ullrich , Chochos Christos L.
Published: July 2015

NIR absorbing copolymers based on α,β-unsubstituted BODIPY dyes suitable for NIR organic photovoltaics.
Structure and crystallinity of water dispersible photoactive nanoparticles for organic solar cells
Authors: Pedersen E. B. L. , Pedersen M. C. , Simonsen S. B. , Brandt R. G. , Böttiger A. P. L. , Andersen T. R. , Jiang W. , Xie Z. Y. , Krebs F. C. , Arleth L. , Andreasen J. W.
Published: July 2015

By studying water dispersible photoactive nanoparticles used for organic photovoltaic devices, we provide new insights into the internal structure, crystallinity and the previously unreported drastic changes that occur when the particles are cast into a film.
8DSS-promoted remineralization of demineralized dentin in vitro
Authors: Liang Kunneng , Xiao Shimeng , Shi Wenyuan , Li Jianshu , Yang Xiao , Gao Yuan , Gou Yaping , Hao Liying , He Libang , Cheng Lei , Xu Xin , Zhou Xuedong , Li Jiyao
Published: July 2015

The 8DSS peptide successfully induced nano-crystals precipitation on the collagen matrix. The completely demineralized dentin was effectively remineralized and its mechanical properties were significantly improved.
Triggering DRAM/SRAM memory behaviors by single atom substitution to alter the molecular planarity
Authors: Hu Haiyan , He Jinghui , Zhuang Hao , Shi Erbo , Li Hua , Li Najun , Chen Dongyun , Xu Qingfeng , Lu Jianmei , Wang Lihua
Published: July 2015

A novelty: achieving different types of memory devices through single atom substitution to alter the molecular planarity thus improves the intramolecular dihedral angle.
Non-clinical development of ozanezumab: a humanised antibody targeting the amino terminus of neurite outgrowth inhibitor A (Nogo-A)
Authors: Lynch Anthony M. , Cleveland Matthew , Prinjha Rabinder , Kumar Umesh , Stubbs Robert , Wuerthner Jens
Published: July 2015

Ozanezumab (GSK1223249) is a humanised, Fc-disabled, monoclonal antibody (mAb) which targets the amino terminus of Neurite Outgrowth Inhibitor A (Nogo-A) which is currently being developed for the treatment of amyotrophic lateral sclerosis (ALS).
Implementation study of wearable sensors for activity recognition systems
Authors: Rezaie Hamed , Ghassemian Mona
Published: July 2015

This Letter investigates and reports on a number of activity recognition methods for a wearable sensor system. The authors apply three methods for data transmission, namely ‘stream‐based’, ‘feature‐based’ and ‘threshold‐based’ scenarios to study the accuracy against energy efficiency of transmission and processing power that affects the mote's battery lifetime. They also report on the impact of variation of sampling frequency and data transmission rate on energy consumption of motes for each method. This study leads us to propose a cross‐layer optimisation of an activity recognition system for provisioning acceptable levels of accuracy and energy efficiency.
Electron accommodation dynamics in the DNA base thymine
Authors: King Sarah B. , Stephansen Anne B. , Yokoi Yuki , Yandell Margaret A. , Kunin Alice , Takayanagi Toshiyuki , Neumark Daniel M.
Published: July 2015

The dynamics of electron attachment to the DNA base thymine are investigated using femtosecond time-resolved photoelectron imaging of the gas phase iodide-thymine (I−T) complex. An ultraviolet pump pulse ejects an electron from the iodide and prepares an iodine-thymine temporary negative ion that is photodetached with a near-IR probe pulse. The resulting photoelectrons are analyzed with velocity-map imaging. At excitation energies ranging from −120 meV to +90 meV with respect to the vertical detachment energy (VDE) of 4.05 eV for I−T, both the dipole-bound and valence-bound negative ions of thymine are observed. A slightly longer rise time for the valence-bound state than the dipole-bound state suggests that some of the dipole-bound anions convert to valence-bound species. No evidence is seen for a dipole-bound anion of thymine at higher excitation energies, in the range of 0.6 eV above the I−T VDE, which suggests that if the dipole-bound anion acts as a “doorway” to the valence-bound anion, it only does so at excitation energies near the VDE of the complex.
Defects evolution and their impacts on conductivity of indium tin oxide thin films upon thermal treatment
Authors: Li Qichao , Mao Wenfeng , Zhou Yawei , Yang Chunhong , Liu Yong , He Chunqing
Published: July 2015

Indium tin oxide (ITO) thin films were deposited on silicon substrates by radio-frequency magnetron sputtering. The influence of annealing temperature on the crystallite, surface morphology, defects evolution, and electrical property of the thin films was studied. The conductivity of the ITO films was significantly enhanced by two orders of magnitude by increasing the annealing temperature up to 600 °C, which was interpreted in point view of defects evolution in ITO films as revealed by positron annihilation. It was interesting to find that positron diffusion length was amazingly comparable to crystallite size in ITO films annealed below 300 °C, indicating positrons were preferentially localized and annihilated in defects around crystallite boundaries. By further increasing the temperature, positron diffusion length was far beyond the grain size with little increment. This demonstrated that defects were effectively removed around grain boundaries. The results indicated defect structure around crystallite/grain boundaries played an important role on carrier transportation in nanocrystal ITO films.
Formation of GaN quantum dots by molecular beam epitaxy using NH3 as nitrogen source
Authors: Damilano B. , Brault J. , Massies J.
Published: July 2015

Self-assembled GaN quantum dots (QDs) in AlxGa1−xN (0.3 ≤ x ≤ 1) were grown on c-plane sapphire and Si (111) substrates by molecular beam epitaxy using ammonia as nitrogen source. The QD formation temperature was varied from 650 °C to 800 °C. Surprisingly, the density and size of QDs formed in this temperature range are very similar. This has been explained by considering together experimental results obtained from reflection high-energy electron diffraction, atomic force microscopy, and photoluminescence to discuss the interplay between thermodynamics and kinetics in the QD formation mechanisms. Finally, possible ways to better control the QD optical properties are proposed.
Observation of hydrodynamic processes of radiation-ablated plasma in a small hole
Authors: Li Hang , Song Tianming , Yang Jiamin , Zhu Tuo , Lin Zhiwei , Zheng Jianhua , Kuang Longyu , Zhang Haiying , Yu Ruizhen , Liu Shenye , Jiang Shaoen , Ding Yongkun , Hu Guangyue , Zhao Bin , Zheng Jian
Published: July 2015

In the hohlraum used in laser indirect-drive inertial confinement fusion experiments, hydrodynamic processes of radiation-ablated high-Z plasma have a great effect on laser injection efficiency, radiation uniformity, and diagnosis of hohlraum radiation field from diagnostic windows (DW). To study plasma filling in the DWs, a laser-irradiated Ti disk was used to generate 2–5 keV narrow energy band X-ray as the intense backlighter source, and laser-produced X-ray in a hohlraum with low-Z foam tamper was used to heat a small hole surrounded by gold wall with 150 μm in diameter and 100 μm deep. The hydrodynamic movement of the gold plasma in the small hole was measured by an X-ray framing camera and the results are analyzed. Quantitative measurement of the plasma areal density distribution and evolution in the small hole can be used to assess the effect of plasma filling on the diagnosis from the DWs.
Reduced density-matrix functional theory: Correlation and spectroscopy
Authors: Di Sabatino S. , Berger J. A. , Reining L. , Romaniello P.
Published: July 2015

In this work, we explore the performance of approximations to electron correlation in reduced density-matrix functional theory (RDMFT) and of approximations to the observables calculated within this theory. Our analysis focuses on the calculation of total energies, occupation numbers, removal/addition energies, and spectral functions. We use the exactly solvable Hubbard dimer at 1/4 and 1/2 fillings as test systems. This allows us to analyze the underlying physics and to elucidate the origin of the observed trends. For comparison, we also report the results of the GW approximation, where the self-energy functional is approximated, but no further hypothesis is made concerning the approximations of the observables. In particular, we focus on the atomic limit, where the two sites of the dimer are pulled apart and electrons localize on either site with equal probability, unless a small perturbation is present: this is the regime of strong electron correlation. In this limit, using the Hubbard dimer at 1/2 filling with or without a spin-symmetry-broken ground state allows us to explore how degeneracies and spin-symmetry breaking are treated in RDMFT. We find that, within the used approximations, neither in RDMFT nor in GW, the signature of strong correlation is present, when looking at the removal/addition energies and spectral function from the spin-singlet ground state, whereas both give the exact result for the spin-symmetry broken case. Moreover, we show how the spectroscopic properties change from one spin structure to the other.
Dislocations in laser-doped silicon detected by micro-photoluminescence spectroscopy
Authors: Nguyen Hieu T. , Han Young , Ernst Marco , Fell Andreas , Franklin Evan , Macdonald Daniel
Published: July 2015

We report the detection of laser-induced damage in laser-doped layers at the surface of crystalline silicon wafers, via micron-scale photoluminescence spectroscopy. The properties of the sub-band-gap emission from the induced defects are found to match the emission characteristics of dislocations. Courtesy of the high spatial resolution of the micro-photoluminescence spectroscopy technique, micron-scale variations in the extent of damage at the edge of the laser-doped region can be detected, providing a powerful tool to study and optimize laser-doping processes for silicon photovoltaics.
Discontinuities-free complete-active-space state–specific multi–reference coupled cluster theory for describing bond stretching and dissociation
Authors: Zaporozhets Irina A. , Ivanov Vladimir V. , Lyakh Dmitry I. , Adamowicz Ludwik
Published: July 2015

The earlier proposed multi–reference state-specific coupled-cluster theory with the complete active space reference [CASCC; Lyakh et al., J. Chem. Phys. 122, 024108 (2005)] suffered from a problem of energy discontinuities when the formal reference state was changing in the calculation of the potential energy curve (PEC). A simple remedy to the discontinuity problem is found and is presented in this work. It involves using natural complete active space self-consistent field active orbitals in the complete active space coupled-cluster calculations. The approach gives smooth PECs for different types of dissociation problems, as illustrated in the calculations of the dissociation of the single bond in the hydrogen fluorine molecule and of the symmetric double-bond dissociation in the water molecule.
Electrical dependence on the chemical composition of the gate dielectric in indium gallium zinc oxide thin-film transistors
Authors: Tari Alireza , Lee Czang-Ho , Wong William S.
Published: July 2015

Bottom-gate thin-film transistors were fabricated by depositing a 50 nm InGaZnO (IGZO) channel layer at 150 °C on three separate gate dielectric films: (1) thermal SiO2, (2) plasma-enhanced chemical-vapor deposition (PECVD) SiNx, and (3) a PECVD SiOx/SiNx dual-dielectric. X-ray photoelectron and photoluminescence spectroscopy showed the Vo concentration was dependent on the hydrogen concentration of the underlying dielectric film. IGZO films on SiNx (high Vo) and SiO2 (low Vo) had the highest and lowest conductivity, respectively. A PECVD SiOx/SiNx dual-dielectric layer was effective in suppressing hydrogen diffusion from the nitride layer into the IGZO and resulted in higher resistivity films.
Circuit electromechanics with single photon strong coupling
Authors: Xue Zheng-Yuan , Yang Li-Na , Zhou Jian
Published: July 2015

In circuit electromechanics, the coupling strength is usually very small. Here, replacing the capacitor in circuit electromechanics by a superconducting flux qubit, we show that the coupling among the qubit and the two resonators can induce effective electromechanical coupling which can attain the strong coupling regime at the single photon level with feasible experimental parameters. We use dispersive couplings among two resonators and the qubit while the qubit is also driven by an external classical field. These couplings form a three-wave mixing configuration among the three elements where the qubit degree of freedom can be adiabatically eliminated, and thus results in the enhanced coupling between the two resonators. Therefore, our work constitutes the first step towards studying quantum nonlinear effect in circuit electromechanics.
Effects of hot electron inertia on electron-acoustic solitons and double layers
Authors: Verheest Frank , Hellberg Manfred A.
Published: July 2015

The propagation of arbitrary amplitude electron-acoustic solitons and double layers is investigated in a plasma containing cold positive ions, cool adiabatic and hot isothermal electrons, with the retention of full inertial effects for all species. For analytical tractability, the resulting Sagdeev pseudopotential is expressed in terms of the hot electron density, rather than the electrostatic potential. The existence domains for Mach numbers and hot electron densities clearly show that both rarefactive and compressive solitons can exist. Soliton limitations come from the cool electron sonic point, followed by the hot electron sonic point, until a range of rarefactive double layers occurs. Increasing the relative cool electron density further yields a switch to compressive double layers, which ends when the model assumptions break down. These qualitative results are but little influenced by variations in compositional parameters. A comparison with a Boltzmann distribution for the hot electrons shows that only the cool electron sonic point limit remains, giving higher maximum Mach numbers but similar densities, and a restricted range in relative hot electron density before the model assumptions are exceeded. The Boltzmann distribution can reproduce neither the double layer solutions nor the switch in rarefactive/compressive character or negative/positive polarity.
The effects of dilution on turbulence and transport in C-Mod ohmic plasmas and comparisons with gyrokinetic simulations
Authors: Ennever P. , Porkolab M. , Candy J. , Staebler G. , Reinke M. L. , Rice J. E. , Rost J. C. , Ernst D. , Fiore C. , Hughes J. , Terry J. ,   Alcator C-Mod Team
Published: July 2015

Main ion dilution has been predicted by gyrokinetic simulations to have a significant effect on ion thermal transport in C-Mod ohmic plasmas. This effect was verified experimentally with a specific set of experiments on C-Mod in which ohmic deuterium plasmas across the linear ohmic confinement (LOC) through the saturated ohmic confinement (SOC) regimes were diluted by seeding with nitrogen gas (Z = 7) injection. The seeding was observed to increase the normalized ion temperature gradients (ITGs) by up to 30% without a corresponding increase in the gyrobohm normalized ion energy flux, indicating a change in either the stiffness or the critical ion temperature gradient associated with ITG turbulence. The seeding also reversed the direction of the intrinsic toroidal rotation in plasmas slightly above the normal intrinsic rotation reversal critical density. GYRO simulations of the seeded and unseeded plasmas show that the seeding affected both the critical gradient and the stiffness. For plasmas in the LOC regime, the dilution primarily increased the critical gradient, while for plasmas in the SOC regime the dilution primarily decreased the stiffness. At r/a = 0.8, where the experimental fluxes were above marginal stability, local GYRO predicted and experimental energy fluxes agreed, except for Qi in the SOC regime where GYRO under-predicted the experimental energy flux. At r/a = 0.6, where the experimental fluxes were close to marginally stable, local GYRO predicted ITG modes to be strongly unstable and are responsible for both Qi and Qe (with Qi > Qe), as opposed to the experiment where Qi < Qe. In contrast, global GYRO in this region predicted the ITG modes to be closer to marginal stability, and accurately predict the experimental Qi when the Ti profile is modified within experimental uncertainties. The fact that Qe is always less than Qi in the r/a = 0.6 simulations with kθρs≤1 indicates that high-k electron temperature gradient driven (ETG) modes must be included in future simulations and may be responsible for the electron energy transport in this case.
Ion acceleration enhanced by target ablation
Authors: Zhao S. , Lin C. , Wang H. Y. , Lu H. Y. , He X. T. , Chen J. E. , Cowan T. E. , Yan X. Q.
Published: July 2015

Laser proton acceleration can be enhanced by using target ablation, due to the energetic electrons generated in the ablation preplasma. When the ablation pulse matches main pulse, the enhancement gets optimized because the electrons' energy density is highest. A scaling law between the ablation pulse and main pulse is confirmed by the simulation, showing that for given CPA pulse and target, proton energy improvement can be achieved several times by adjusting the target ablation.
The pattern of parallel edge plasma flows due to pressure gradients, recycling, and resonant magnetic perturbations in DIII-D
Authors: Frerichs H. , Schmitz O. , Evans T. , Feng Y. , Reiter D.
Published: July 2015

High resolution plasma transport simulations with the EMC3-EIRENE code have been performed to address the parallel plasma flow structure in the boundary of a poloidal divertor configuration with non-axisymmetric perturbations at DIII-D. Simulation results show that a checkerboard pattern of flows with alternating direction is generated inside the separatrix. This pattern is aligned with the position of the main resonances (i.e., where the safety factor is equal to rational values q=m/n for a perturbation field with base mode number n): m pairs of alternating forward and backward flow channel exist for each resonance. The poloidal oscillations are aligned with the subharmonic Melnikov function, which indicates that the plasma flow is generated by parallel pressure gradients along perturbed field lines. An additional scrape-off layer-like domain is introduced by the perturbed separatrix which guides field lines from the interior to the divertor targets, resulting in an enhanced outward flow that is consistent with the experimentally observed particle pump-out effect. However, while the lobe structure of the perturbed separatrix is very well reflected in the temperature profile, the same lobes can appear to be smaller in the flow profile due to a competition between high upstream pressure and downstream particle sources driving flows in opposite directions.
Floating and sinking of self-assembled spheres on liquid-liquid interfaces: Rafts versus stacks
Authors: Jones Steven G. , Abbasi Niki , Ahuja Abhinav , Truong Vivian , Tsai Scott S. H.
Published: July 2015

The floating and sinking of objects on fluid-fluid interfaces occurs in nature and has many important implications in technology. Here, we study the stability of floating self-assembled spheres on an oil-water interface, and how the sphere deposition geometry affects the size limits of the assemblies before they collapse and sink through the interface. Specifically, we compare the critical size of particle rafts to particle stacks. We show that, on liquid-liquid interfaces, monolayer rafts and stacked spheres exhibit different scaling of the critical number of spheres to the Bond number—the dimensionless ratio of buoyancy to interfacial tension effects. Our results indicate that particle stacks will sink with a lower threshold number of particles than particle rafts. This finding may have important implications to engineering applications where interfacial assemblies are not monolayers.
Suppression of turbulent resistivity in turbulent Couette flow
Authors: Si Jiahe , Colgate Stirling A. , Sonnenfeld Richard G. , Nornberg Mark D. , Li Hui , Colgate Arthur S. , Westpfahl David J. , Romero Van D. , Martinic Joe
Published: July 2015

Turbulent transport in rapidly rotating shear flow very efficiently transports angular momentum, a critical feature of instabilities responsible both for the dynamics of accretion disks and the turbulent power dissipation in a centrifuge. Turbulent mixing can efficiently transport other quantities like heat and even magnetic flux by enhanced diffusion. This enhancement is particularly evident in homogeneous, isotropic turbulent flows of liquid metals. In the New Mexico dynamo experiment, the effective resistivity is measured using both differential rotation and pulsed magnetic field decay to demonstrate that at very high Reynolds number rotating shear flow can be described entirely by mean flow induction with very little contribution from correlated velocity fluctuations.
Electron self-injection into the phase of a wake excited by a driver laser in a nonuniform density target
Authors: Yu Q. , Gu Y. J. , Li X. F. , Huang S. , Kong Q. , Kawata S.
Published: July 2015

It is well known that if electrons are externally injected into a density upramp, then their dephasing lengths will be extended greatly, and thus these electrons will gain more energy. However, we find that a density upramp can also be used to control the beam's collimation and the emittance that occurs by self-injection in the gradient. When electrons self-inject into the wakefield in a density gradient, an electron filtering mechanism is found to occur in the injection process. Electrons with high transverse velocities are scattered and only electrons with high longitudinal to transverse velocity ratios can be candidate electrons for self-injection. This causes the trapped electrons to be more highly collimated. In addition, the injection occurs near the axis, which causes the accelerated electron beam to have reduced emittance. An ultra-collimated electron beam with an angle spread of ∼1° and emittance of ∼0.01 mm mrad is generated by a 2.5-dimensional particle-in-cell (2.5-D PIC) simulation.
Junction optimization in HgCdTe: Shockley-Read-Hall generation-recombination suppression
Authors: Schuster J. , DeWames R. E. , DeCuir E. A. , Bellotti E. , Wijewarnasuriya P. S.
Published: July 2015

Heterojunction device design concepts are leveraged to reduce depletion layer generation-recombination (G-R) dark current in planar P+-on-n SWIR HgCdTe infrared detectors. Shockley-Read-Hall (SRH) depletion dark current (when present) is expected to be the dominant dark current component at low temperatures, and in fact, it is beneficial for the transition from diffusion to G-R to be at such relatively low temperatures. However, it is empirically observed that even for relatively long values of the SRH lifetime (20 μs), the transition occurs at relatively high temperatures (>200 K) for material with a cut-off wavelength of 2.5 μm. A key device design parameter of P+-on-n photodiodes is the position of the electrical junction relative to the hetero-metallurgical interface. Junction formation via p-type arsenic implantation into the narrow-gap absorber layer is typically chosen for efficient collection of diffusion current, however, other configurations are possible as well. In this letter, we numerically explore the conditions that reduce depletion dark current without reducing the quantum efficiency (QE). The findings support the assertion that device design conditions exist in SWIR HgCdTe that essentially eliminate the depletion dark current without significantly reducing the QE.
Influence of tantalum underlayer on magnetization dynamics in Ni81Fe19 films
Authors: Kwon Jae Hyun , Deorani Praveen , Yoon Jungbum , Hayashi Masamitsu , Yang Hyunsoo
Published: July 2015

The effect of tantalum (Ta) underlayer is investigated in Ni81Fe19 thin films for magnetization dynamics. The damping parameters extracted from spin wave measurements increase systematically with increasing Ta thickness, whereas the damping parameters from ferromagnetic resonance measurements are found to be weakly dependent on the Ta thickness. The difference is attributed to propagating properties of spin wave and short spin diffusion length in Ta. The group velocity of spin waves is found to be constant for different Ta thicknesses, and nonreciprocity of spin waves is not affected by the Ta thickness. The experimental observations are supported by micromagnetic simulations.
Investigation of the flickering of La2O3 and ThO2 doped tungsten cathodes
Authors: Hoebing T. , Hermanns P. , Bergner A. , Ruhrmann C. , Traxler H. , Wesemann I. , Knabl W. , Mentel J. , Awakowicz P.
Published: July 2015

Short-arc lamps are equipped with tungsten electrodes due to their ability to withstand a high thermal load during operation. Nominal currents of more than one hundred amperes lead to a cathode tip temperature near the melting point of tungsten. To reduce the electrode temperature and, thereby, to increase the maintenance of such lamps, ThO2 or tentatively La2O3 are added to the electrode material. They generate a reduced work function by establishing a monolayer of emitter atoms on the tungsten surface. Emitter enrichments on the lateral surface of doped cathodes are formed. They are traced back to transport mechanisms of emitter oxides in the interior of the electrode and on the electrode surface in dependence of the electrode temperature and to the redeposition of vaporized and ionized emitter atoms onto the cathode tip by the electric field in front. The investigation is undertaken by means of glow discharge mass spectrometry, scanning electron microscope images, energy dispersive x-ray spectroscopy, and through measurements of the optical surface emissivity. The effect of emitter enrichments on the stability of the arc attachment is presented by means of temporally resolved electrode temperature measurements and by measurements of the luminous flux from the cathode-near plasma. They show that the emitter enrichments on the lateral surface of the cathode are attractive for the arc attachment if the emitter at the cathode tip is depleted. In this case, it moves along the lateral surface from the cathode tip to sections of the cathode with a reduced work function. It induces a temporary variation of the cathode tip temperature and of the light intensity from the cathode-near plasma, a so-called flickering. In particular, in case of lanthanated cathodes, strong flickering is observed.
Density matrix embedding in an antisymmetrized geminal power bath
Authors: Tsuchimochi Takashi , Welborn Matthew , Van Voorhis Troy
Published: July 2015

Density matrix embedding theory (DMET) has emerged as a powerful tool for performing wave function-in-wave function embedding for strongly correlated systems. In traditional DMET, an accurate calculation is performed on a small impurity embedded in a mean field bath. Here, we extend the original DMET equations to account for correlation in the bath via an antisymmetrized geminal power (AGP) wave function. The resulting formalism has a number of advantages. First, it allows one to properly treat the weak correlation limit of independent pairs, which DMET is unable to do with a mean-field bath. Second, it associates a size extensive correlation energy with a given density matrix (for the models tested), which AGP by itself is incapable of providing. Third, it provides a reasonable description of charge redistribution in strongly correlated but non-periodic systems. Thus, AGP-DMET appears to be a good starting point for describing electron correlation in molecules, which are aperiodic and possess both strong and weak electron correlation.
Formation of shallow boron emitters in crystalline silicon using flash lamp annealing: Role of excess silicon interstitials
Authors: Riise Heine Nygard , Schumann Thomas , Azarov Alexander , Hübner Renè , Skorupa Wolfgang , Svensson Bengt G. , Monakhov Edouard
Published: July 2015

Shallow, Boron (B)-doped p+ emitters have been realized using spin-on deposition and Flash Lamp Annealing (FLA) to diffuse B into monocrystalline float zone Silicon (Si). The emitters extend between 50 and 140 nm in depth below the surface, have peak concentrations between 9 × 1019 cm–3 and 3 × 1020 cm–3, and exhibit sheet resistances between 70 and 3000 Ω/□. An exceptionally large increase in B diffusion occurs for FLA energy densities exceeding ∼93 J/cm2 irrespective of 10 or 20 ms pulse duration. The effect is attributed to enhanced diffusion of B caused by Si interstitial injection following a thermally activated reaction between the spin-on diffusant film and the silicon wafer.
Pressure-induced kinetics of the α to ω transition in zirconium
Authors: Jacobsen M. K. , Velisavljevic N. , Sinogeikin S. V.
Published: July 2015

Diamond anvil cells (DAC) coupled with x-ray diffraction (XRD) measurements are one of the primary techniques for investigating structural stability of materials at high pressure-temperature (P-T) conditions. DAC-XRD has been predominantly used to resolve structural information at set P-T conditions and, consequently, provides P-T phase diagram information on a broad range of materials. With advances in large scale synchrotron x-ray facilities and corresponding x-ray diagnostic capabilities, it is now becoming possible to perform sub-second time resolved measurements on micron sized DAC samples. As a result, there is an opportunity to gain valuable information about the kinetics of structural phase transformations and extend our understanding of material behavior at high P-T conditions. Using DAC-XRD time resolved measurements, we have investigated the kinetics of the α to ω transformation in zirconium. We observe a clear time and pressure dependence in the martensitic α-ω transition as a function of pressure-jump, i.e., drive pressure. The resulting data are fit using available kinetics models, which can provide further insight into transformation mechanism that influence transformation kinetics. Our results help shed light on the discrepancies observed in previous measurements of the α-ω transition pressure in zirconium.
Self-catalyzed growth of pure zinc blende ⟨110⟩ InP nanowires
Authors: Yan Xin , Zhang Xia , Li Junshuai , Wu Yao , Ren Xiaomin
Published: July 2015

We demonstrate the self-catalyzed vapor-liquid-solid growth of ⟨110⟩ InP nanowires (NWs) by metal organic chemical vapor deposition. The ⟨110⟩ InP nanowire is formed via a spontaneous kinking from the original ⟨111⟩ growth direction, which is attributed to instabilities at the liquid/solid interface caused by a fast In incorporation into the droplet. The NW length before kinking has a nearly linear relationship with the diameter, offering a way to control the NW morphology for different applications. The ⟨110⟩ nanowire exhibits pure zinc blende crystal structure and a narrower emission linewidth in comparison with a typical ⟨111⟩ nanowire, demonstrating its potential applications in high-performance electronic and photonic devices.
On-chip beamsplitter operation on single photons from quasi-resonantly excited quantum dots embedded in GaAs rib waveguides
Authors: Rengstl U. , Schwartz M. , Herzog T. , Hargart F. , Paul M. , Portalupi S. L. , Jetter M. , Michler P.
Published: July 2015

We present an on-chip beamsplitter operating on a single-photon level by means of a quasi-resonantly driven InGaAs/GaAs quantum dot. The single photons are guided by rib waveguides and split into two arms by an evanescent field coupler. Although the waveguides themselves support the fundamental TE and TM modes, the measured degree of polarization (∼90%) reveals the main excitation and propagation of the TE mode. We observe the preserved single-photon nature of a quasi-resonantly excited quantum dot by performing a cross-correlation measurement on the two output arms of the beamsplitter. Additionally, the same quantum dot is investigated under resonant excitation, where the same splitting ratio is observed. An autocorrelation measurement with an off-chip beamsplitter on a single output arm reveal the single-photon nature after evanescent coupling inside the on-chip splitter. Due to their robustness, adjustable splitting ratio, and their easy implementation, rib waveguide beamsplitters with embedded quantum dots provide a promising step towards fully integrated quantum circuits.
Note: Radiochemical measurement of fuel and ablator areal densities in cryogenic implosions at the National Ignition Facility
Authors: Hagmann C. , Shaughnessy D. A. , Moody K. J. , Grant P. M. , Gharibyan N. , Gostic J. M. , Wooddy P. T. , Torretto P. C. , Bandong B. B. , Bionta R. , Cerjan C. J. , Bernstein L. A. , Caggiano J. A. , Herrmann H. W. , Knauer J. P. , Sayre D. B. , Schneider D. H. , Henry E. A. , Fortner R. J.
Published: July 2015

A new radiochemical method for determining deuterium-tritium (DT) fuel and plastic ablator (CH) areal densities (ρR) in high-convergence, cryogenic inertial confinement fusion implosions at the National Ignition Facility is described. It is based on measuring the 198Au/196Au activation ratio using the collected post-shot debris of the Au hohlraum. The Au ratio combined with the independently measured neutron down scatter ratio uniquely determines the areal densities ρR(DT) and ρR(CH) during burn in the context of a simple 1-dimensional capsule model. The results show larger than expected ρR(CH) values, hinting at the presence of cold fuel-ablator mix.
Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials
Authors: Roy Chowdhury Dibakar , Xu Ningning , Zhang Weili , Singh Ranjan
Published: July 2015

Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.
Hydrogenated arsenenes as planar magnet and Dirac material
Authors: Zhang Shengli , Hu Yonghong , Hu Ziyu , Cai Bo , Zeng Haibo
Published: July 2015

Arsenene and antimonene are predicted to have 2.49 and 2.28 eV band gaps, which have aroused intense interest in the two-dimensional (2D) semiconductors for nanoelectronic and optoelectronic devices. Here, the hydrogenated arsenenes are reported to be planar magnet and 2D Dirac materials based on comprehensive first-principles calculations. The semi-hydrogenated (SH) arsenene is found to be a quasi-planar magnet, while the fully hydrogenated (FH) arsenene is a planar Dirac material. The buckling height of pristine arsenene is greatly decreased by the hydrogenation, resulting in a planar and relatively low-mass-density sheet. The electronic structures of arsenene are also evidently altered after hydrogenating from wide-band-gap semiconductor to metallic material for SH arsenene, and then to Dirac material for FH arsenene. The SH arsenene has an obvious magnetism, mainly contributed by the p orbital of the unsaturated As atom. Such magnetic and Dirac materials modified by hydrogenation of arsenene may have potential applications in future optoelectronic and spintronic devices.
Coupling of transit time instabilities in electrostatic confinement fusion devices
Authors: Gruenwald J. , Fröhlich M.
Published: July 2015

A model of the behavior of transit time instabilities in an electrostatic confinement fusion reactor is presented in this letter. It is demonstrated that different modes are excited within the spherical cathode of a Farnsworth fusor. Each of these modes is dependent on the fusion products as well as the acceleration voltage applied between the two electrodes and they couple to a resulting oscillation showing non-linear beat phenomena. This type of instability is similar to the transit time instability of electrons between two resonant surfaces but the presence of ions and the occurring fusion reactions alter the physics of this instability considerably. The physics of this plasma instability is examined in detail for typical physical parameter ranges of electrostatic confinement fusion devices.
Hydrodynamic consideration of the finite size effect on the self-diffusion coefficient in a periodic rectangular parallelepiped system
Authors: Kikugawa Gota , Nakano Takeo , Ohara Taku
Published: July 2015

In the present study, we use molecular dynamics (MD) simulations to provide an insight into the system size effect on the self-diffusion coefficient of liquids in the periodic rectangular parallelepiped system, from the hydrodynamic perspective. We have previously shown that in the rectangular box system, the diffusivity exhibits anomalous behaviors, i.e., the diffusion tensor appears to be anisotropic despite the bulk liquid simulation and the diffusion component in the direction along the short side of rectangular box with a high aspect ratio exceeding the diffusivity in the infinite system [Kikugawa et al., J.Chem. Phys. 142, 024503 (2015)]. So far, the size effect on the diffusivity has been intensively studied in the cubic system and has been interpreted quite well by the theoretical considerations employing the hydrodynamic interaction. Here, we have extended the hydrodynamic theory to be applied to periodic rectangular box systems and compared the theoretical predictions with MD simulation results. As a result, the diffusivity predicted by the hydrodynamic theory shows good agreement with the MD results. In addition, the system size effect was examined in a rod-shaped rectangular box in which the two shorter side lengths were equivalent and a film-type rectangular box in which the two longer side lengths were equivalent. It is of interest that we found that the aspect ratio, at which the diffusivity coincides with that in the infinite system, is a universal constant independent of the cross-sectional area for the rod system or the thickness for the film system. By extracting the universal structure in the hydrodynamic description, we also suggested a simplified approximate model to accurately predict the size effect on the diffusivity over a practical range of aspect ratios.
Relative importance of physical and biological factors regulating tintinnid populations: a field study with frequent samplings in Sendai Bay, Japan
Authors: Kazama Takehiro , Urabe Jotaro
Published: July 2015

To examine factors regulating the summer population dynamics of tintinnid species, temporally high-frequency observations of tintinnid ciliates were performed in Hiroura Estuary in Sendai Bay. Sampling was conducted on alternate days from 5 July to 2 August, 2010 at three estuary sites to examine which environmental (water temperature, salinity and tidal level change) and biological (abundances of Chl-a, bacteria, protozoans and zooplankton) factors are important for determining temporal changes in abundance and apparent population change rates for tintinnid species. During the study period, 20 tintinnid species were found and showed drastic population changes within a few days, resulting in different tintinnid assemblages from the first to the second half of the study period. Multivariate analysis and generalised linear mixed models showed that several environmental and biological factors were related significantly with the abundance and apparent population change rate of each tintinnid species, but no effect of potential predators such as copepods was found for the abundance and change rate. These results suggest that physicochemical and food conditions play more important roles than predation pressure in short-term temporal changes of tintinnid populations during summer in estuary environments.
Controlling inputs from the land to sea: limit-setting, cumulative impacts and ki uta ki tai
Authors: Schiel David R. , Howard-Williams Clive
Published: July 2015

The coastal zone worldwide is not well served by management policies that fail to deal effectively with land-sourced contaminants from streams, rivers and urban runoff. We discuss this using examples from New Zealand, where there is a wide recognition of such problems but little effective policy that specifically accounts for the interconnectedness of the land-to-freshwater-to-sea domain. Increasing land-use intensification, mostly in arable pasture, has greatly increased the nutrient load to the coast and has contributed to the already high sediment loading of coastal waters. We argue that renewed effort is needed for a more holistic approach to management, encapsulated in the New Zealand Maori concept of ki uta ki tai – an appreciation of mountains-to-sea connections. Limit-setting, especially of nitrogen from terrestrial sources, seems to a main way forward for reducing loads and halting cumulative effects. However, this must account for current impacts and also the ‘load to come’ because of time lags associated with accumulated groundwater nutrients and cumulative impacts in receiving waters. Despite many approaches being tried, there are increasing impacts of catchment activities on coasts worldwide. The need is therefore great for new approaches, renewed effort, and for a very long-term perspective to ensure effective and enduring solutions.
Estimating antiretroviral treatment coverage rates and viral suppression rates for homosexual men in Australia
Authors: De La Mata Nicole L. , Mao Limin , De Wit John , Smith Don , Holt Martin , Prestage Garrett , Wilson David P. , Petoumenos Kathy
Published: July 2015

Gay and other men who have sex with men (GMSM) are disproportionally affected by the HIV epidemic in Australia. The study objective is to combine a clinical-based cohort with a community-based surveillance system to present a broader representation of the GMSM community to determine estimates of proportions receiving antiretroviral therapy (ART) and/or with an undetectable viral load. Between 2010 and 2012, small increases were shown in ART uptake (to 70.2%) and proportions with undetectable viral load (to 62.4%). The study findings highlight the potential for significantly increasing ART uptake among HIV-positive GMSM to reduce the HIV epidemic in Australia.