bluuebunny/crossref_metadata_2025 huggingface dataset:
A porous nanobranched structure: an effective way to improve piezoelectricity in sputtered ZnO thin films
Authors: Laurenti M. , Canavese G. , Stassi S. , Fontana M. , Castellino M. , Pirri C. F. , Cauda V.
Published: August 2016

ZnO nanomaterials are gaining lots of attention due to their biocompatible nature coupled with promising piezoelectric properties, envisioning a new generation of lead-free smart materials.
Metal oxide–zeolite composites in transformation of methanol to hydrocarbons: do iron oxide and nickel oxide matter?
Authors: Mann Joshua , Doluda Valentin Yu , Leonard Clara , Losovyj Yaroslav B. , Morgan David Gene , Bukalov Sergey S. , Shifrina Zinaida , Stein Barry D. , Cherkasov Nikolay , Rebrov Evgeny V. , Harms Zachary D. , Pink Maren , Sulman Esther M. , Bronstein Lyudmila
Published: August 2016

Novel, hierarchical zeolites modified with both Fe3O4 and NixOy nanoparticles have been developed and studied in the methanol-to-hydrocarbon process.
MOF surface method for the ultrafast and one-step generation of metal-oxide-NP@MOF composites as lithium storage materials
Authors: Yan Chang Sheng , Gao Heng Ya , Le Gong Le , Ma Lu Fang , Dang Li Long , Zhang Le , Meng Pan Pan , Luo Feng
Published: August 2016

The ultrafast and one-step generation of Fe2O3@MOF composites is for the first time achieved using a so-called ‘MOF surface’ method.
Doped graphenes as anodes with large capacity for lithium-ion batteries
Authors: Zhou Liujiang , Hou Z. F. , Gao Bo , Frauenheim Thomas
Published: August 2016

To understand the chemical doping effect on the lithium (Li) storage of graphene, we have performed first-principles calculations to study the adsorption and diffusion of Li adatoms on boron (B)- and nitrogen (N)-doped graphenes, which include individual and paired B (and N) dopants in graphene.
Nanodiamond–PMO for two-photon PDT and drug delivery
Authors: Jimenez Chiara Mauriello , Knezevic Nikola Z. , Rubio Yolanda Galàn , Szunerits Sabine , Boukherroub Rabah , Teodorescu Florina , Croissant Jonas G. , Hocine Ouahiba , Seric Martina , Raehm Laurence , Stojanovic Vanja , Aggad Dina , Maynadier Marie , Garcia Marcel , Gary-Bobo Magali , Durand Jean-Olivier
Published: August 2016

We report nanodiamond–PMO nanosystems which generate ROS upon two-photon excitation.
n-Type conductivity bound by the growth temperature: the case of Al0.72Ga0.28N highly doped by silicon
Authors: Kakanakova-Georgieva A. , Sahonta S.-L. , Nilsson D. , Trinh X. T. , Son N. T. , Janzén E. , Humphreys C. J.
Published: August 2016

While increasing temperature is essential for reducing carbon and oxygen incorporation, it reduces the incorporation of silicon as a donor.
Human serine racemase is allosterically modulated by NADH and reduced nicotinamide derivatives
Authors: Bruno Stefano , Marchesani Francesco , Dellafiora Luca , Margiotta Marilena , Faggiano Serena , Campanini Barbara , Mozzarelli Andrea
Published: August 2016

Serine racemase catalyzes both the synthesis and the degradation of d-serine, an obligatory co-agonist of the glutamatergic NMDA receptors. It is allosterically controlled by adenosine triphosphate (ATP), which increases its activity around 7-fold through a co-operative binding mechanism. Serine racemase has been proposed as a drug target for the treatment of several neuropathologies but, so far, the search has been directed only toward the active site, with the identification of a few, low-affinity inhibitors. Following the recent observation that nicotinamide adenine dinucleotide (reduced form) (NADH) inhibits serine racemase, here we show that the inhibition is partial, with an IC50 of 246 ± 63 μM, several-fold higher than NADH intracellular concentrations. At saturating concentrations of NADH, ATP binds with a 2-fold lower affinity and without co-operativity, suggesting ligand competition. NADH also reduces the weak activity of human serine racemase in the absence of ATP, indicating an additional ATP-independent inhibition mechanism. By dissecting the NADH molecule, we discovered that the inhibitory determinant is the N-substituted 1,4-dihydronicotinamide ring. Particularly, the NADH precursor 1,4-dihydronicotinamide mononucleotide exhibited a partial mixed-type inhibition, with a KI of 18 ± 7 μM. Docking simulations suggested that all 1,4-dihydronicotinamide derivatives bind at the interdimeric interface, with the ring positioned in an unoccupied site next to the ATP-binding site. This newly recognized allosteric site might be exploited for the design of high-affinity serine racemase effectors to finely modulate d-serine homeostasis.
Effectiveness of power electronic voltage regulators in the distribution network
Authors: Watson Jeremy D. , Watson Neville R. , Das Bhaba
Published: August 2016

Steady‐state voltage levels will be a significant problem in the future distribution network due to a high penetration of new technologies, particularly photovoltaics. A smart transformer which incorporates a fixed tap transformer with a power electronic voltage regulator has the potential to mitigate this problem by varying the line voltage automatically in response to changes in loading. This study considers various control strategies for the voltage regulator and looks at the potential impact that a smart transformer could have on reducing system voltage violations. These impact studies are performed on a computer model of an entire utility's distribution system in New Zealand.
Investigation of SiC trench MOSFET with floating islands
Authors: Qingwen Song , Xiaoyan Tang , Yimeng Zhang , Yuming Zhang , Yimen Zhang
Published: August 2016

The silicon carbide trench metal‐oxide‐semiconductor field‐effect transistors (SiC UMOSFET) with P+ floating island (FLI) which shields the gate oxide at the bottom of the gate trench from the high electric field during the blocking state and enhances the breakdown voltage (BV), is presented in this study using two‐dimensional simulations. The effects of doping concentration, length and position of FLI on BV, electric field distribution and specific on‐resistance (Ron,sp) are studied, thereby providing particularly useful guidelines for the design of this new type of device when considering the breakdown of the gate oxide layer. For the suitable device design, the results indicate that BV and Baliga figure of merit are, respectively, increased by 150 and 439% compared with a conventional SiC UMOSFET. At the same time, the SiC FLI UMOSFET has smaller gate‐drain capacitance and better switching performance compared with the conventional UMOSFET on the condition of the same drift layer parameters. FLI introduced have almost no influence on the recovery characteristics of body diode.
DC voltage control strategy of chain star STATCOM with second‐order harmonic suppression
Authors: Wang Yingjie , Chai Yushuo , Tang Jianbo , Yuan Xibo , Xia Chenyang
Published: August 2016

Chain static synchronous compensators (STATCOMs) with star structure produce second‐order harmonic fluctuations on the DC side. This effect is often ignored and only the average voltage value is taken into consideration when describing this system for control purpose. In this study, the unbalance of per‐phase DC voltages caused by active power absorbed and consumed by the chain is analysed. The steady‐state expressions regarding the average capacitor voltage balancing between phase clusters as well as the suppression of second‐order harmonic fluctuation are obtained, respectively, based on the injection of fundamental and third‐order harmonic zero‐sequence voltages. Although the expressions are helpful to understand the essence of DC capacitor voltage control, this method has complicated calculation process and the calculation results may be beyond the modulation limit. Therefore, it is not conducive in real‐time control. For this reason, a new control strategy based on the instantaneous zero‐sequence voltage injection is proposed. The evaluation function with the transient variables is established to get the instantaneous value of the zero‐sequence voltage including fundamental and third‐order harmonic components. The fundamental and third‐order harmonic zero‐sequence voltages are automatically allocated to fully use the remaining modulation capacity. Finally, simulation and experimental results are provided, which verifies the correctness of the theoretical analysis and the high performance of the proposed method.
Random nearest level modulation strategy of multilevel cascaded H‐bridge inverters
Authors: Qi Chen , Tu Pengfei , Wang Peng , Zagrodnik Michael A.
Published: August 2016

Power converters using deterministic pulse width modulation (PWM) schemes have discrete and high harmonics concentrated at well‐defined frequencies. In this study, two random PWM strategies to reduce the harmonic spikes for multilevel cascaded H‐bridge (CHB) inverters are proposed. The proposed strategies select two nearest voltage levels to approximate output voltage based on simple geometrical calculations and randomly vary the pulse position of output voltage by choosing a random output instant of two nearest levels. The first proposed strategy provides two discrete pulse positions and one of them is selected by a random bit. The continuous varying of pulse position is generated in the second strategy, where a random interval varying from zero to sampling period is used to delay the beginning instant of pulse position. A maximum degree of freedom can be achieved in the second proposed strategy with lower harmonic spikes but higher commutation frequency, in comparison with the first strategy. A five‐level CHB inverter controlled by TMS320F28335 DSP is tested and the experimental results compared with the deterministic PWM strategy validate the proposed strategies.
Surgical Approaches to Non-thyrogenic and Non-thymic Mediastinal Tumors of the Thoracic Inlet
Authors: Liu Yu , Lu Tao , Fan Hong , Xu Songtao , Ding Jianyong , Lin Zongwu , Wang Qun
Published: August 2016

Background Non-thyrogenic and non-thymic mediastinal tumors of the thoracic inlet are in close proximity to several important vessels and nerves. The narrow confines of the thoracic inlet make complete excision of these tumors difficult, and selecting the appropriate surgical approach is important to successful resection.

Methods Records from 57 patients who presented to our department with non-thyrogenic and non-thymogenic tumors of the thoracic inlet from November 2004 to November 2015 were reviewed. All but one of the patients received surgical treatment. Thirty-two tumors were excised via video-assisted thoracic surgery (VATS). Other approaches included thoracotomy, supraclavicular incision, supraclavicular incision plus thoracotomy/VATS, and a posterior midline approach with semi-laminectomy combined with VATS.

Results Tumors were resected completely in 54 cases and partially in one. One procedure (VATS) was aborted. There were no surgical mortalities, but there were some postoperative complications. The majority of the tumors were benign neurogenic tumors.

Conclusions Most tumors of the thoracic inlet are benign and can be removed via VATS. Thoracotomy is the appropriate approach for large tumors, particularly in cases where the first to second rib cannot be visualized. A supraclavicular approach is recommended for resection of tumors arising from the brachial plexus, and a supraclavicular approach combined with VATS or thoracotomy may be useful for larger masses. A posterior midline approach with semi-laminectomy combined with VATS is appropriate for dumbbell-shaped tumors.
Resolving hot spot microstructure using x-ray penumbral imaging (invited)
Authors: Bachmann B. , Hilsabeck T. , Field J. , Masters N. , Reed C. , Pardini T. , Rygg J. R. , Alexander N. , Benedetti L. R. , Döppner T. , Forsman A. , Izumi N. , LePape S. , Ma T. , MacPhee A. G. , Nagel S. , Patel P. , Spears B. , Landen O. L.
Published: August 2016

We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution imaging of stagnated plasma cores (hot spots) of spherically shock compressed spheres and shell implosion targets. By utilizing circular tungsten and tantalum apertures with diameters ranging from 20 μm to 2 mm, in combination with image plate and gated x-ray detectors as well as imaging magnifications ranging from 4 to 64, we have demonstrated high-resolution imaging of hot spot plasmas at x-ray energies above 5 keV. Here we give an overview of the experimental design criteria involved and demonstrate the most relevant influences on the reconstruction of x-ray penumbral images, as well as mitigation strategies of image degrading effects like over-exposed pixels, artifacts, and photon limited source emission. We describe experimental results showing the advantages of x-ray penumbral imaging over conventional Fraunhofer and photon limited pinhole imaging and showcase how internal hot spot microstructures can be resolved.
On the determination of the crystal-vapor surface free energy, and why a Gaussian expression can be accurate for a system far from Gaussian
Authors: Modak Viraj P. , Wyslouzil Barbara E. , Singer Sherwin J.
Published: August 2016

The crystal-vapor surface free energy γ is an important physical parameter governing physical processes, such as wetting and adhesion. We explore exact and approximate routes to calculate γ based on cleaving an intact crystal into non-interacting sub-systems with crystal-vapor interfaces. We do this by turning off the interactions, ΔV, between the sub-systems. Using the soft-core scheme for turning off ΔV, we find that the free energy varies smoothly with the coupling parameter λ, and a single thermodynamic integration yields the exact γ. We generate another exact method, and a cumulant expansion for γ by expressing the surface free energy in terms of an average of e−βΔV in the intact crystal. The second cumulant, or Gaussian approximation for γ is surprisingly accurate in most situations, even though we find that the underlying probability distribution for ΔV is clearly not Gaussian. We account for this fact by developing a non-Gaussian theory for γ and find that the difference between the non-Gaussian and Gaussian expressions for γ consist of terms that are negligible in many situations. Exact and approximate methods are applied to the (111) surface of a Lennard-Jones crystal and are also tested for more complex molecular solids, the surface of octane and nonadecane. Alkane surfaces were chosen for study because their crystal-vapor surface free energy has been of particular interest for understanding surface freezing in these systems.
Comparison of implosion core metrics: A 10 ps dilation X-ray imager vs a 100 ps gated microchannel plate
Authors: Nagel S. R. , Benedetti L. R. , Bradley D. K. , Hilsabeck T. J. , Izumi N. , Khan S. , Kyrala G. A. , Ma T. , Pak A.
Published: August 2016

The dilation x-ray imager (DIXI) [T. J. Hilsabeck et al., Rev. Sci. Instrum. 81, 10E317 (2010); S. R. Nagel et al., ibid. 83, 10E116 (2012); S. R. Nagel et al., ibid. 85, 11E504 (2014)] is a high-speed x-ray framing camera that uses the pulse-dilation technique to achieve a temporal resolution of less than 10 ps. This is a 10 × improvement over conventional framing cameras currently employed on the National Ignition Facility (NIF) (100 ps resolution), and otherwise only achievable with 1D streaked imaging. A side effect of the dramatically reduced gate width is the comparatively lower detected signal level. Therefore we implement a Poisson noise reduction with non-local principal component analysis method [J. Salmon et al., J. Math. Imaging Vision 48, 279294 (2014)] to improve the robustness of the DIXI data analysis. Here we present results on ignition-relevant experiments at the NIF using DIXI. In particular we focus on establishing that/when DIXI gives reliable shape metrics (P0, P2, and P4 Legendre modes, and their temporal evolution/swings).
Fokker-Planck equation in the presence of a uniform magnetic field
Authors: Dong Chao , Zhang Wenlu , Li Ding
Published: August 2016

The Fokker-Planck equation in the presence of a uniform magnetic field is derived which has the same form as the case of no magnetic field but with different Fokker-Planck coefficients. The coefficients are calculated explicitly within the binary collision model, which are free from infinite sums of Bessel functions. They can be used to investigate relaxation and transport phenomena conveniently. The kinetic equation is also manipulated into the Landau form from which it is straightforward to compare with previous results and prove the conservation laws.
Existence of solutions for a Schrödinger system with linear and nonlinear couplings
Authors: Li Kui , Zhang Zhitao
Published: August 2016

We study an important system of Schrödinger equations with linear and nonlinear couplings arising from Bose-Einstein condensates. We use the Nehari manifold to prove the existence of a ground state solution; moreover, we give the sign of the solutions depending on linear coupling; by using index theory and Nehari manifold, we prove that there exist infinitely many positive bound state solutions.
Dynamical tunneling versus fast diffusion for a non-convex Hamiltonian
Authors: Pittman S. M. , Tannenbaum E. , Heller E. J.
Published: August 2016

This paper attempts to resolve the issue of the nature of the 0.01-0.1 cm−1 peak splittings observed in high-resolution IR spectra of polyatomic molecules. One hypothesis is that these splittings are caused by dynamical tunneling, a quantum-mechanical phenomenon whereby energy flows between two disconnected regions of phase-space across dynamical barriers. However, a competing classical mechanism for energy flow is Arnol’d diffusion, which connects different regions of phase-space by a resonance network known as the Arnol’d web. The speed of diffusion is bounded by the Nekhoroshev theorem, which guarantees stability on exponentially long time scales if the Hamiltonian is steep. Here we consider a non-convex Hamiltonian that contains the characteristics of a molecular Hamiltonian, but does not satisfy the Nekhoroshev theorem. The diffusion along the Arnol’d web is expected to be fast for a non-convex Hamiltonian. While fast diffusion is an unlikely competitor for longtime energy flow in molecules, we show how dynamical tunneling dominates compared to fast diffusion in the nearly integrable regime for a non-convex Hamiltonian, as well as present a new kind of dynamical tunneling.
Measuring a hidden coordinate: Rate-exchange kinetics from 3D correlation functions
Authors: Berg Mark A. , Darvin Jason R.
Published: August 2016

Nonexponential kinetics imply the existence of at least one slow variable other than the observable, that is, the system has a “hidden” coordinate. We develop a simple, but general, model that allows multidimensional correlation functions to be calculated for these systems. Homogeneous and heterogeneous mechanisms are both included, and slow exchange of the rates is allowed. This model shows that 2D and 3D correlation functions of the observable measure the distribution and kinetics of the hidden coordinate controlling the rate exchange. Both the mean exchange time and the shape of the exchange relaxation are measurable. However, complications arise because higher correlation functions are sums of multiple “pathways,” each of which measures different dynamics. Only one 3D pathway involves exchange dynamics. Care must be used to extract exchange dynamics without contamination from other processes.
The effects of main-ion dilution on turbulence in low q95 C-Mod ohmic plasmas, and comparisons with nonlinear GYRO
Authors: Ennever P. , Porkolab M. , Candy J. , Staebler G. , Reinke M. L , Rice J. E. , Rost J. C. , Ernst D. , Hughes J. , Baek S. G. ,   Alcator C-Mod Team
Published: August 2016

Recent experiments on C-mod seeding nitrogen into ohmic plasmas with q95 = 3.4 found that the seeding greatly reduced long-wavelength (ITG-scale) turbulence. The long-wavelength turbulence that was reduced by the nitrogen seeding was localized to the region of r/a≈0.85, where the turbulence is well above marginal stability (as evidenced by Qi/QGB≫1). The nonlinear gyrokinetic code GYRO was used to simulate the expected turbulence in these plasmas, and the simulated turbulent density fluctuations and turbulent energy fluxes quantitatively agreed with the experimental measurements both before and after the nitrogen seeding. Unexpectedly, the intrinsic rotation of the plasma was also found to be affected by the nitrogen seeding, in a manner apparently unrelated to a change in the electron-ion collisionality that was proposed by other experiments.
Particle-in-cell simulation study of the scaling of asymmetric magnetic reconnection with in-plane flow shear
Authors: Doss C. E. , Cassak P. A. , Swisdak M.
Published: August 2016

We investigate magnetic reconnection in systems simultaneously containing asymmetric (anti-parallel) magnetic fields, asymmetric plasma densities and temperatures, and arbitrary in-plane bulk flow of plasma in the upstream regions. Such configurations are common in the high-latitudes of Earth's magnetopause and in tokamaks. We investigate the convection speed of the X-line, the scaling of the reconnection rate, and the condition for which the flow suppresses reconnection as a function of upstream flow speeds. We use two-dimensional particle-in-cell simulations to capture the mixing of plasma in the outflow regions better than is possible in fluid modeling. We perform simulations with asymmetric magnetic fields, simulations with asymmetric densities, and simulations with magnetopause-like parameters where both are asymmetric. For flow speeds below the predicted cutoff velocity, we find good scaling agreement with the theory presented in Doss et al. [J. Geophys. Res. 120, 7748 (2015)]. Applications to planetary magnetospheres, tokamaks, and the solar wind are discussed.
Emission and afterglow properties of an expanding RF plasma with nonuniform neutral gas density
Authors: Chaplin Vernon H. , Bellan Paul M.
Published: August 2016

We describe some notable aspects of the light emission and afterglow properties in pulsed, high-density (1018–1020 m−3) argon inductively coupled discharges initiated following fast gas injection. The plasma was created in a long, narrow discharge tube and then expanded downstream of the radiofrequency (RF) antenna into a large chamber. Fast camera images of the expanding plasma revealed a multi-phase time-dependent emission pattern that did not follow the ion density distribution. Dramatic differences in visible brightness were observed between discharges with and without an externally applied magnetic field. These phenomena were studied by tracking excited state populations using passive emission spectroscopy and are discussed in terms of the distinction between ionizing and recombining phase plasmas. Additionally, a method is presented for inferring the unknown neutral gas pressure in the discharge tube from the time-dependent visible and infrared emission measured by a simple photodiode placed near the antenna. In magnetized discharges created with fast gas injection, the downstream ion density rose by Δni∼1018 m−3 in the first ∼100 μs after the RF power was turned off. The conditions conducive to this afterglow density rise are investigated in detail, and the effect is tentatively attributed to pooling ionization.
Magnetism and electronic structure of CoFeCrX (X = Si, Ge) Heusler alloys
Authors: Jin Y. , Kharel P. , Lukashev P. , Valloppilly S. , Staten B. , Herran J. , Tutic I. , Mitrakumar M. , Bhusal B. , O'Connell A. , Yang K. , Huh Y. , Skomski R. , Sellmyer D. J.
Published: August 2016

The structural, electronic, and magnetic properties of CoFeCrX (X = Si, Ge) Heusler alloys have been investigated. Experimentally, the alloys were synthesized in the cubic L21 structure with small disorder. The cubic phase of CoFeCrSi was found to be highly stable against heat treatment, but CoFeCrGe disintegrated into other new compounds when the temperature reached 402 °C (675 K). Although the first-principle calculation predicted the possibility of tetragonal phase in CoFeCrGe, the tetragonal phase could not be stabilized experimentally. Both CoFeCrSi and CoFeCrGe compounds showed ferrimagnetic spin order at room temperature and have Curie temperatures (TC) significantly above room temperature. The measured TC for CoFeCrSi is 790 K but that of CoFeCrGe could not be measured due to its dissociation into new compounds at 675 K. The saturation magnetizations of CoFeCrSi and CoFeCrGe are 2.82 μB/f.u. and 2.78 μB/f.u., respectively, which are close to the theoretically predicted value of 3 μB/f.u. for their half-metallic phases. The calculated band gaps for CoFeCrSi and CoFeCrGe are, respectively, 1 eV and 0.5 eV. These materials have potential for spintronic device applications, as they exhibit half-metallic electronic structures with large band gaps, and Curie temperatures significantly above room temperature.
Insights into the spurious long-range nature of local rs-dependent non-local exchange-correlation kernels
Authors: Lu Deyu
Published: August 2016

A systematic route to go beyond the exact exchange plus random phase approximation (RPA) is to include a physical exchange-correlation kernel in the adiabatic-connection fluctuation-dissipation theorem. In the previous study [D. Lu, J. Chem. Phys. 140, 18A520 (2014)], we found that non-local kernels with a screening length depending on the local Wigner-Seitz radius, rs(r), suffer an error associated with a spurious long-range repulsion in van der Waals bounded systems, which deteriorates the binding energy curve as compared to RPA. We analyze the source of the error and propose to replace rs(r) by a global, average rs in the kernel. Exemplary studies with the Corradini, del Sole, Onida, and Palummo kernel show that while this change does not affect the already outstanding performance in crystalline solids, using an average rs significantly reduces the spurious long-range tail in the exchange-correlation kernel in van der Waals bounded systems. When this method is combined with further corrections using local dielectric response theory, the binding energy of the Kr dimer is improved three times as compared to RPA.
Optimal configuration of distributed generators in an integrated energy system
Authors: Tang Yiyuan , Gu Wei , Wang Zhihe , Luo Zhao , Wang Jun
Published: August 2016

The increasing penetration of distributed generators (DGs) makes further interconnection of multiple energy carriers possible. In this paper, an integration model comprising IEEE-33 bus distribution network and a correspondingly designed water system is proposed with DG coupling of thermal and electrical energy. The integrated energy system incorporates the constraints of the distribution network, water system, and DGs and ensures that the electrical and thermal demands of the integrated energy system are satisfied simultaneously by energy flow. An optimal procedure including optimal sizing, positioning, and operation of DGs and gas boilers in a given system was implemented while minimizing the total costs of investment and operation. The model constitutes a mixed integer nonlinear problem, as it takes the power flow calculation and the nonlinear characteristics of DG efficiency into consideration. Therefore, the particle swarm optimization algorithm is employed to simulate the proposed model. The simulation results in conjunction with numerical studies reveal the impact of the water system on the optimal configuration of DGs and the advantages of the integrated energy system on economic considerations, voltage level, and net loss.
High-dynamic-range neutron time-of-flight detector used to infer the D(t,n)4He and D(d,n)3He reaction yield and ion temperature on OMEGA
Authors: Forrest C. J. , Glebov V. Yu. , Goncharov V. N. , Knauer J. P. , Radha P. B. , Regan S. P. , Romanofsky M. H. , Sangster T. C. , Shoup M. J. , Stoeckl C.
Published: August 2016

Upgraded microchannel-plate–based photomultiplier tubes (MCP-PMT’s) with increased stability to signal-shape linearity have been implemented on the 13.4-m neutron time-of-flight (nTOF) detector at the Omega Laser Facility. This diagnostic uses oxygenated xylene doped with diphenyloxazole C15H11NO + p-bis-(o-methylstyryl)-benzene (PPO + bis-MSB) wavelength shifting dyes and is coupled through four viewing ports to fast-gating MCP-PMT’s, each with a different gain to allow one to measure the light output over a dynamic range of 1 × 106. With these enhancements, the 13.4-m nTOF can measure the D(t,n)4He and D(d,n)3He reaction yields and average ion temperatures in a single line of sight. Once calibrated for absolute neutron sensitivity, the nTOF detectors can be used to measure the neutron yield from 1 × 109 to 1 × 1014 and the ion temperature with an accuracy approaching 5% for both the D(t,n)4He and D(d,n)3He reactions.
Absolute calibration of neutron detectors on the C-2U advanced beam-driven FRC
Authors: Magee R. M. , Clary R. , Korepanov S. , Jauregui F. , Allfrey I. , Garate E. , Valentine T. , Smirnov A.
Published: August 2016

In the C-2U fusion energy experiment, high power neutral beam injection creates a large fast ion population that sustains a field-reversed configuration (FRC) plasma. The diagnosis of the fast ion pressure in these high-performance plasmas is therefore critical, and the measurement of the flux of neutrons from the deuterium-deuterium (D-D) fusion reaction is well suited to the task. Here we describe the absolute, in situ calibration of scintillation neutron detectors via two independent methods: firing deuterium beams into a high density gas target and calibration with a 2 × 107 n/s AmBe source. The practical issues of each method are discussed and the resulting calibration factors are shown to be in good agreement. Finally, the calibration factor is applied to C-2U experimental data where the measured neutron rate is found to exceed the classical expectation.
Nonlinear piezomagnetoelastic harvester array for broadband energy harvesting
Authors: Upadrashta Deepesh , Yang Yaowen
Published: August 2016

This article proposes an array of nonlinear piezomagnetoelastic energy harvesters (NPEHs) for scavenging electrical energy from broadband vibrations with low amplitudes (<2 m/s2). The array consists of monostable NPEHs combined to generate useful power output (∼100 μW) over wide bandwidth. The nonlinearity in each of the NPEHs is induced by the magnetic interaction between an embedded magnet in the tip mass of cantilever and a fixed magnet clamped to the rigid platform. The dynamic responses of two NPEHs, one with attractive configuration and the other with repulsive configuration, are combined to achieve a bandwidth of 3.3 Hz at a power level of 100 μW. A parametric study is carried out to obtain the gap distances between the magnets to achieve wide bandwidth. Experiments are performed to validate the proposed idea, the theoretical predictions, and to demonstrate the advantage of array of NPEHs over the array of linear piezoelectric energy harvesters (LPEHs). The experiments have clearly shown the advantage of NPEH array over its linear counterpart under both harmonic and random excitations. Approximately, 100% increase in the operation bandwidth is achieved by the NPEH array at harmonic excitation level of 2 m/s2. The NPEH array exhibits up to 80% improvement in the accumulated energy under random excitation when compared with the LPEH array. Furthermore, the performance of NPEH array with series and parallel connections between the individual harvesters using standard AC/DC interface circuits is also investigated and compared with its linear counterpart.
Compact electret energy harvester with high power output
Authors: Pondrom P. , Sessler G. M. , Bös J. , Melz T.
Published: August 2016

Compact electret energy harvesters, based on a design recently introduced, are presented. Using electret surface potentials in the 400 V regime and a seismic mass of 10 g, it was possible to generate output power up to 0.6 mW at 36 Hz for an input acceleration of 1 g. Following the presentation of an analytical model allowing for the calculation of the power generated in a load resistance at the resonance frequency of the harvesters, experimental results are shown and compared to theoretical predictions. Finally, the performance of the electret harvesters is assessed using a figure of merit.
Oxygen vacancy mediated enhanced photo-absorption from ZnO(0001) nanostructures fabricated by atom beam sputtering
Authors: Solanki Vanaraj , Joshi Shalik R. , Mishra Indrani , Kabiraj D. , Mishra N. C. , Avasthi D. K. , Varma Shikha
Published: August 2016

The nanoscale patterns created on the ZnO(0001) surfaces during atom beam irradiation have been investigated here for their photo absorption response. Preferential sputtering, during irradiation, promotes Zn-rich zones that serve as the nucleation centers for the spontaneous creation of nanostructures. Nanostructured surfaces with bigger (78 nm) nanodots, displaying hexagonal ordering and long ranged periodic behavior, show higher photo absorption and a ∼0.09 eV reduced bandgap. These nanostructures also demonstrate higher concentration of oxygen vacancies which are crucial for these results. The enhanced photo-response, as observed here, has been achieved in the absence of any dopant elements.
Chemical-free n-type and p-type multilayer-graphene transistors
Authors: Dissanayake D. M. N. M. , Eisaman M. D.
Published: August 2016

A single-step doping method to fabricate n- and p-type multilayer graphene (MG) top-gate field effect transistors (GFETs) is demonstrated. The transistors are fabricated on soda-lime glass substrates, with the n-type doping of MG caused by the sodium in the substrate without the addition of external chemicals. Placing a hydrogen silsesquioxane (HSQ) barrier layer between the MG and the substrate blocks the n-doping, resulting in p-type doping of the MG above regions patterned with HSQ. The HSQ is deposited in a single fabrication step using electron beam lithography, allowing the patterning of arbitrary sub-micron spatial patterns of n- and p-type doping. When a MG channel is deposited partially on the barrier and partially on the glass substrate, a p-type and n-type doping profile is created, which is used for fabricating complementary transistors pairs. Unlike chemically doped GFETs in which the external dopants are typically introduced from the top, these substrate doped GFETs allow for a top gate which gives a stronger electrostatic coupling to the channel, reducing the operating gate bias. Overall, this method enables scalable fabrication of n- and p-type complementary top-gated GFETs with high spatial resolution for graphene microelectronic applications.
A single crystalline InP nanowire photodetector
Authors: Yan Xin , Li Bang , Wu Yao , Zhang Xia , Ren Xiaomin
Published: August 2016

Single crystalline nanowires are critical for achieving high-responsivity, high-speed, and low-noise nanoscale photodetectors. Here, we report a metal-semiconductor-metal photodetector based on a single crystalline InP nanowire. The nanowires are grown by a self-catalyzed method and exhibit stacking-fault-free zinc blende crystal structure. The nanowire exhibits a typical n-type semiconductor property and shows a low room temperature dark current of several hundred pA at moderate biases. A photoresponsivity of 6.8 A/W is obtained at a laser power density of 0.2 mW/cm2. This work demonstrates that single crystalline InP nanowires are good candidates for future optoelectronic device applications.
HIV incidence among gay men and other men who have sex with men in 2020: where is the epidemic heading?
Authors: Stahlman Shauna , Lyons Carrie , Sullivan Patrick S. , Mayer Kenneth H. , Hosein Sean , Beyrer Chris , Baral Stefan D.
Published: August 2016

The goal to effectively prevent new HIV infections among gay, bisexual, and other men who have sex with men (MSM) is more challenging now than ever before. Despite declines in the late 1990s and early 2000s, HIV incidence among MSM is now increasing in many low- and high-income settings including the US, with young, adolescent, and racial/ethnic minority MSM being among those at highest risk. Potentiating HIV risks across all settings are individual-, network-, and structural-level factors such as stigma and lack of access to pre-exposure prophylaxis (PrEP) and antiretroviral treatment as prevention. To make a sustained impact on the epidemic, a concerted effort must integrate all evidence-based interventions that will most proximally decrease HIV acquisition and transmission risks, together with structural interventions that will support improved coverage and retention in care. Universal HIV treatment, increased access to HIV testing, and daily oral PrEP have emerged as integral to the prevention of HIV transmission, and such efforts should be immediately expanded for MSM and other populations disproportionately affected by HIV. Respect for human rights and efforts to combat stigma and improve access to prevention services are needed to change the trajectory of the HIV pandemic among MSM.
Alternative haplotypes of antigen processing genes in zebrafish diverged early in vertebrate evolution
Authors: McConnell Sean C. , Hernandez Kyle M. , Wcisel Dustin J. , Kettleborough Ross N. , Stemple Derek L. , Yoder Jeffrey A. , Andrade Jorge , de Jong Jill L. O.
Published: August 2016

Significance

Antigen presentation genes are exceptionally polymorphic, enhancing immune defense. Polymorphism within additional components of the MHC pathway, particularly the antigen processing genes, may also shape immune responses. Using transcriptome, exome, and whole-genome sequencing to examine immune gene variation in zebrafish, we uncovered several antigen processing genes not found in the reference genome clustered within a deeply divergent haplotype of the core MHC locus. Our data provide evidence that these previously undescribed antigen processing genes retain ancient alternative sequence lineages, likely derived during the formation of the adaptive immune system, and represent the most divergent collection of antigen processing and presentation genes yet identified. These findings offer insights into the evolution of vertebrate adaptive immunity.
Near-atomic cryo-EM structure of PRC1 bound to the microtubule
Authors: Kellogg Elizabeth H. , Howes Stuart , Ti Shih-Chieh , Ramírez-Aportela Erney , Kapoor Tarun M. , Chacón Pablo , Nogales Eva
Published: August 2016

Significance

PRC1 (protein regulator of cytokinesis 1) is critical to cellular architecture through its interaction with microtubules to form antiparallel microtubule arrays, like those in the spindle midzone. Here, cryo-EM studies describe, in close to atomic detail, the interaction of PRC1 with the microtubule surface. Together with previous studies, our structure leads to a model of how PRC1 promotes the establishment of stable, higher-order microtubule arrays.
Multimodality, politics and ideology
Authors: Machin David , van Leeuwen Theo
Published: August 2016

This journal’s editorial statement is clear that political discourse should be studied not only as regards parliamentary type politics. In this introduction we argue precisely for the need to pay increasing attention to the way that political ideologies are infused into culture more widely, in entertainments media, software, administrative processes, children’s apps, healthcare and even office furniture design. We point to the way that there have been massive shifts away from traditional state forms of politics to the rule of neoliberalism and the power of the corporation which, like the former regime of power, requires meanings and identities which can hold them in place. We explain the processes by which critical multimodal discourse analysis can best draw out this ideology as it is realized through different semiotics resources.
Software as ideology
Authors: Kvåle Gunhild
Published: August 2016

Software has become ubiquitous in higher education, especially often taken-for-granted Microsoft Word. Educational writing involves more than horizontal lines of text, but also multimodal representations. When students write in Word, the affordances of the program constrain what multimodal representations of knowledge they can and cannot make. Software such as Word is not neutral tool-kits, but also historical and semiotic constructs loaded with social values and ideologies. By taking a social semiotic approach to Word and SmartArt, this article shows how this software is pre-loaded with values and styles from office management. These values are then infused into education, in the case this article investigates, grammar models in language studies.
Humour, ridicule and the de-legitimization of the working class in Swedish Reality Television
Authors: Eriksson Göran
Published: August 2016

Drawing on tools from Multimodal Critical Discourse Analysis this paper analyses the editing techniques in a Swedish docu-soap showing that humour is used to ridicule the working-class participants, representing them as slow, inflexible, undynamic and unstylish. The paper places this within broader discursive shifts in Sweden where the rise of neoliberalism requires a dismantling of the welfare state, legitimized partly though establishing the lower social economic groups as morally flawed and themselves responsible for their increasingly disadvantaged situation as social inequalities increase.
An Experimental Evaluation of Electrofishing Catchability and Catch Depletion Abundance Estimates of Larval Lampreys in a Wadeable Stream: Use of a Hierarchical Approach
Authors: Harris Julianne E. , Jolley Jeffrey C. , Silver Gregory S. , Yuen Henry , Whitesel Timothy A.
Published: August 2016

Some lamprey species are in decline, and assessments of local abundance could benefit research and conservation. In wadeable streams, larval lampreys are collected by using specialized backpack electrofishing techniques, although catchability has not been sufficiently evaluated. We assessed removal models for estimating the local abundance of larval lampreys in experimental net‐pen enclosures within a wadeable stream. Known numbers of larvae were seeded at densities of 4–130 larvae/m2 into 1‐m2 enclosures that were lined with fine sand and placed into Cedar Creek, Washington (Columbia River basin). Depletion sampling in each enclosure (n = 69) was conducted by three to five electrofishing passes, and abundance was estimated by six removal models that assumed different catchability functions. Catchability averaged 0.28. For the standard removal model, which assumed that catchability varied independently by enclosure but not by pass, the 95% highest posterior density credible intervals (95% HPD‐CIs) were very large relative to the abundance estimates. Models assuming that catchability was either equal or a random factor among all enclosures and passes generally produced accurate (mean bias = −0.04) estimates of abundance, and 95% HPD‐CIs were much smaller. Based on our data set, the expected bias of abundance estimates for 80% of simulations was less than 20% if five passes were completed from at least four randomly selected quadrats and if catchability was assumed to be a random factor. Additional sampling may be needed at low lamprey densities (especially <4 larvae/m2). Our results suggest that local abundance of larval lampreys in wadeable streams can be effectively estimated by depletion sampling at multiple 1‐m2 quadrats and by use of a hierarchical removal model.

Received June 12, 2015; accepted April 20, 2016 Published online August 5, 2016
Life History Diversity of Steelhead in Two Coastal Washington Watersheds
Authors: Hall Jason , Roni Philip , Bennett Todd , McMillan John , Hanson Karrie , Moses Raymond , McHenry Mike , Pess George , Ehinger William
Published: August 2016

We used PIT tags implanted in juvenile Oncorhynchus mykiss to monitor movement into and out of two coastal Washington State rivers, East Twin River and West Twin River. Movement patterns revealed at least 18 life histories of steelhead O. mykiss with variations in age and seasonal migration of juveniles, juvenile use of the ocean prior to migration, years spent in the ocean, season of adult return, and iteroparity. While most migrants left the river in their first fall or winter, we did not detect any returning adults from these age‐0 migrants. Adults were only produced from age‐1 and older migrants, of which most were age‐2 spring migrants that returned after two summers in the ocean. Our results indicated a positive relationship between fish length at tagging and the probability of being detected as a migrant, while the probability of a migrant leaving at age 1 and older decreased with increasing length at tagging among fish that were detected as migrants. We hypothesize that fish attaining a large enough size early in life to survive over the winter but not big enough to trigger migration at age 0 were more likely to remain in the river to become age‐1 migrants, which were more likely to produce a returning adult steelhead. We also found evidence that density‐dependent growth may influence juvenile steelhead migration patterns and production of migrants as evidenced by increasing contributing‐adult steelhead escapement being negatively related to average cohort body size, probabilities of fish being detected as migrants, and production of age‐1 and older migrants. We anticipate that the findings of this study can be used to inform the development of steelhead recovery strategies for East Twin and West Twin rivers, which have experienced recent declines in adult returns much like other North Pacific Ocean stocks.

Received January 20, 2016; accepted May 18, 2016 Published online August 5, 2016
A high-temperature deformation model based on dislocation movement for wrought aluminium alloys
Authors: Hu H. E. , Wang X. Y.
Published: August 2016

This paper presents a high-temperature deformation model based on dislocation movement for wrought aluminium alloys, which can exhibit the dynamic recovery and dynamic recrystallisation processes of a wrought aluminium alloy at the same time. In the model, work hardening corresponds to the increase of dislocation density. Dynamic recovery occurs in two ways, namely by the condensation of dislocations into new low-angle boundaries, and by the absorption of dislocations into pre-existing boundaries. High- and low-angle boundaries disappear by the sweeping of high-angle boundary migration. The prediction of the model is presented for the high-temperature deformation of the 7050 aluminium alloy. Predicted true stress–strain curves and microstructure evolution from the model are consistent with experimental data.
On arithmetic lattices in the plane
Authors: Fukshansky Lenny , Guerzhoy Pavel , Luca Florian
Published: August 2016

We investigate similarity classes of arithmetic lattices in the plane. We introduce a natural height function on the set of such similarity classes, and give asymptotic estimates on the number of all arithmetic similarity classes, semi-stable arithmetic similarity classes, and well-rounded arithmetic similarity classes of bounded height as the bound tends to infinity. We also briefly discuss some properties of the

j
j

-invariant corresponding to similarity classes of planar lattices.
Uniformly continuous orbit equivalence of Markov shifts and gauge actions on Cuntz–Krieger algebras
Authors: Matsumoto Kengo
Published: August 2016

We introduce a notion of uniformly continuous orbit equivalence as a subequivalence relation of continuous orbit equivalence of one-sided topological Markov shifts. It is described in terms of gauge actions on the associated Cuntz–Krieger algebras and continuous full groups of the Markov shifts.