bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasmonically enhanced upconversion of 1500 nm light via trivalent Er in a TiO2 matrix
Authors: Lakhotiya Harish , Nazir Adnan , Madsen Søren P. , Christiansen Jeppe , Eriksen Emil , Vester-Petersen Joakim , Johannsen Sabrina R. , Jeppesen Bjarke Rolighed , Balling Peter , Larsen Arne Nylandsted , Julsgaard Brian
Published: December 2016

In this letter, we present a comparative experimental–simulation study of Au-nanodisc-enhanced upconversion of 1500 nm light in an Er3+ doped TiO2 thin film. The geometry of the Au nanodiscs was guided by finite-element simulations based on a single nanodisc in a finite computational domain and controlled experimentally using electron-beam lithography. The surface-plasmon resonances (SPRs) exhibited a well-known spectral red shift with increasing diameter, well explained by the model. However, an experimentally observed double-peak SPR, which resulted from inter-particle interactions, was expectedly not captured by the single-particle model. At resonance, the model predicted a local-field enhancement of the upconversion yield, and experimentally, the luminescence measurements showed such enhancement up to nearly 7 fold from a nanodisc with 315 nm diameter and 50 nm height. The upconversion enhancement agreed qualitatively with the theoretical predictions, however with 3–5 times higher enhancement, which was attributed to scattered light from neighboring particles.
A study on the conductivity in an argon magnetized plasma: A criterion for the resistive waves existence
Authors: Xaplanteris C. L. , Xaplanteris S. C.
Published: December 2016

As the resistive instabilities with their serious difficulty at the thermonuclear fusion programs have attracted much interest of the researchers, the present study has the ambition to provide an applicable and useful criterion for examining and identifying whether a observed plasma wave is resistive or not. A dispersion relation is obtained, by using the two fluids equation and considering that a resistive force exists, and then the growth rate can be solved. Subsequently, the resistance factor is calculated using the experimental values and data obtained. Finally, a comparison of the calculated resistance factor with the ones published in bibliography will be performed, which gives the expected answer about the type of the examined wave.
Nonlinear propagation of electrostatic travelling waves in degenerate dense magnetoplasmas
Authors: El-Shamy E. F. , Al-Chouikh R. C. , El-Depsy A. , Al-Wadie N. S.
Published: December 2016

The electrostatic travelling wave structures have been investigated in degenerate dense magnetoplasmas consisting of relativistic degenerate inertialess electrons and positrons, as well as nondegenerate inertial cold ions. The well known reductive perturbation method has been applied in obtaining the nonlinear Zakharov-Kuznetsov equation. The formation of the electrostatic solitary waves and periodic travelling waves is carried out by the bifurcation theory of planar dynamical systems. The results demonstrate that the nonlinear electrostatic travelling waves strongly depend on the concentration of positrons, the ion cyclotron frequency, and the direction cosines of the wave vector. The obtained results here may be useful for better understanding of the structure of nonlinear electrostatic travelling wave in dense plasmas, such as the interior of massive white dwarfs.
Parameter dependence of two-fluid and finite Larmor radius effects on the Rayleigh-Taylor instability in finite beta plasmas
Authors: Ito Atsushi , Miura Hideaki
Published: December 2016

The parameter dependence of two-fluid and finite Larmor radius (FLR) effects on the Rayleigh-Taylor (RT) instability in finite beta plasmas is examined based on extended magnetohydrodynamic (MHD) models. Four MHD models, the MHD model, two-fluid MHD model, MHD model with FLR effects, and two-fluid MHD model with FLR effects, are compared with each other with local and eigenmode analyses. For equilibria with nonuniform magnetic fields, the absence of complete stabilization of large wavenumber modes due to the FLR effect [Zhu et al., Phys. Rev. Lett. 101, 085005 (2008)] occurs for beta lower than the critical value for a small pressure gradient. For the two-fluid MHD model with the FLR term, it is shown that the absence of complete stabilization occurs for the beta different from that for the MHD model with the FLR term, the mode is not always most stable among those for the other models, depending on beta, and the coupling between RT mode and electron drift wave appears. The spatial dependence of the local analysis is examined in comparison with that of eigenfunctions. For the case of MHD with the FLR term, for large wavenumber modes, the growth rate of the eigenmode is larger than that of the local analysis at the center. In that case, the eigenfunction has two humps in the regions that are still unstable while the RT mode is completely stabilized at the center in the local analysis.
Excitation of azimuthal surface waves in the electron cyclotron frequency range by a rotating electron beam in presence of dissipation
Authors: Girka Igor O. , Thumm Manfred
Published: December 2016

Azimuthal surface waves are eigen-electromagnetic oscillations which propagate in cylindrical plasma filled waveguides across an axial stationary magnetic field. Their excitation by a flow of electrons which rotate along large Larmor orbits around the plasma column is well studied mostly in the collisionless approach. The influence of weak collisions between the plasma particles on the growth rate of such waves is studied here. Transfer from the mode of beam-plasma instability that takes place in the case of sufficiently high electron beam particle density and weak collisions to that of a beam dissipative instability that occurs if the beam density is low and the collision frequency is sufficiently high is demonstrated.
Molecular dynamics simulations of field emission from a prolate spheroidal tip
Authors: Torfason Kristinn , Valfells Agust , Manolescu Andrei
Published: December 2016

High resolution molecular dynamics simulations with full Coulomb interactions of electrons are used to investigate field emission from a prolate spheroidal tip. The space charge limited current is several times lower than the current calculated with the Fowler-Nordheim formula. The image-charge is taken into account with a spherical approximation, which is good around the top of the tip, i.e., region where the current is generated.
Nonlinear oscillations and waves in multi-species cold plasmas
Authors: Verma Prabal Singh
Published: December 2016

The spatio-temporal evolution of nonlinear oscillations in multi-species plasma is revisited to provide more insight into the physics of phase mixing by constructing two sets of nonlinear solutions up to the second order. The first solution exhibits perfect oscillations in the linear regime and phase mixing appears only nonlinearly in the second order as a response to the ponderomotive forces. This response can be both direct and indirect. The indirect contribution of the ponderomotive forces appears through self-consistently generated low frequency fields. Furthermore, the direct and indirect contributions of the ponderomotive forces on the phase mixing process is explored and it is found that the indirect contribution is negligible in an electron-ion plasma and it disappears in the case of electron-positron plasma, yet represents an equal contribution in the electron-positron-ion plasma. However, the second solution does not exhibit any phase mixing due to the absence of ponderomotive forces but results in an undistorted nonlinear traveling wave. These investigations have relevance for laboratory/astrophysical multi-species plasma.
Lorentz covariant canonical symplectic algorithms for dynamics of charged particles
Authors: Wang Yulei , Liu Jian , Qin Hong
Published: December 2016

In this paper, the Lorentz covariance of algorithms is introduced. Under Lorentz transformation, both the form and performance of a Lorentz covariant algorithm are invariant. To acquire the advantages of symplectic algorithms and Lorentz covariance, a general procedure for constructing Lorentz covariant canonical symplectic algorithms (LCCSAs) is provided, based on which an explicit LCCSA for dynamics of relativistic charged particles is built. LCCSA possesses Lorentz invariance as well as long-term numerical accuracy and stability, due to the preservation of a discrete symplectic structure and the Lorentz symmetry of the system. For situations with time-dependent electromagnetic fields, which are difficult to handle in traditional construction procedures of symplectic algorithms, LCCSA provides a perfect explicit canonical symplectic solution by implementing the discretization in 4-spacetime. We also show that LCCSA has built-in energy-based adaptive time steps, which can optimize the computation performance when the Lorentz factor varies.
Pressure prediction model based on artificial neural network optimized by genetic algorithm and its application in quasi-static calibration of piezoelectric high-pressure sensor
Authors: Gu Tingwei , Kong Deren , Jiang Jian , Shang Fei , Chen Jing
Published: December 2016

This paper applies back propagation neural network (BPNN) optimized by genetic algorithm (GA) for the prediction of pressure generated by a drop-weight device and the quasi-static calibration of piezoelectric high-pressure sensors for the measurement of propellant powder gas pressure. The method can effectively overcome the slow convergence and local minimum problems of BPNN. Based on test data of quasi-static comparison calibration method, a mathematical model between each parameter of drop-weight device and peak pressure and pulse width was established, through which the practical quasi-static calibration without continuously using expensive reference sensors could be realized. Compared with multiple linear regression method, the GA-BPNN model has higher prediction accuracy and stability. The percentages of prediction error of peak pressure and pulse width are less than 0.7% and 0.3%, respectively.
Simultaneous thermal stability and phase change speed improvement of Sn15Sb85 thin film through erbium doping
Authors: Zou Hua , Zhu Xiaoqin , Hu Yifeng , Sui Yongxing , Sun Yuemei , Zhang Jianhao , Zheng Long , Song Zhitang
Published: December 2016

In general, there is a trade off between the phase change speed and thermal stability in chalcogenide phase change materials, which leads to sacrifice the one in order to ensure the other. For improving the performance, doping is a widely applied technological process. Here, we fabricated Er doped Sn15Sb85 thin films by magnetron sputtering. Compared with the pure Sn15Sb85, we show that Er doped Sn15Sb85 thin films exhibit simultaneous improvement over the thermal stability and the phase change speed. Thus, our results suggest that Er doping provides the opportunity to solve the contradiction. The main reason for improvement of both thermal stability and crystallization speed is due to the existence of Er-Sb and Er-Sn bonds in Er doped Sn15Sb85 films. Hence, Er doped Sn15Sb85 thin films are promising candidates for the phase change memory application, and this method could be extended to other lanthanide-doped phase change materials.
Magnetic anisotropy of quaternary GaMnAsP ferromagnetic semiconductor
Authors: Lee Hakjoon , Chang Jihoon , Chongthanaphisut Phunvira , Lee Sangyeop , Choi Seonghoon , Bac Seul-Ki , Nasir Alviu R. , Lee Sanghoon , Pardo A. , Dong Sining , Li X. , Liu X. , Furdyna J. K. , Dobrowolska M.
Published: December 2016

We report a systemeatic investigation of magnetic anisotropy of quaternary GaMnAsP ferromagnetic semiconductor films by magneto-transport. Hall measurements showed a transition of the easy magnetization direction from in-plane to out-of plane with incorporation of the P into the GaMnAs films. Quantitative information on magnetic anisotropy of the films is obtained by fitting the angular dependence of Hall resistance data to magnetic free energy using the coherent rotation model. Values of magnetic anisotropy parameters show that in-plane anisotropy decreases and out-of-plane anisotropy increases with increasing P content in these films. The out-of-plane magnetic anisotropy in GaMnAsP layers is further enhanced by low temperature annealing. By optimizing the growth and annealing conditions, we were able to obtain a Curie temperature of 125 K in such quaternary films, with strong out-of-plane anisotropy. This study showed that the magnetic anisotropy of the GaMnAsP films can be controlled by adjusting the concentration of the P, and by appropriate post-growth annealing.
Observation of polarization and thickness dependent third-harmonic generation in multilayer black phosphorus
Authors: Wu Hsin-Yu , Yen Yun , Liu Cheng-Hsien
Published: December 2016

We experimentally investigate the power, polarization, and thickness dependence of third-harmonic generation in multilayer black phosphorus (BP) flakes. We observe that the third-harmonic response radiated from BP is highly dependent on the polarization of the excitation owing to the anisotropic nature of BP, as well as being very sensitive to the flake thickness owing to the interference effects between surface and bulk nonlinear contributions. Compared to the linear optical microscopic examination, the demonstrated third-harmonic generation can be used for nonlinear optical identification of the crystal orientation and thickness of multilayer BP with higher contrast and fewer restrictions on substrate materials.
Optimization of the multi-slot cavity and drift in a 0.34 THz extended interaction klystron
Authors: Li Shuang , Wang Jianguo , Wang Guangqiang , Wang Dongyang , Teng Yan , Zeng Peng
Published: December 2016

The configurations of the cavity and drift tube used in a 0.34 THz Extended Interaction Klystron (EIK) are theoretically studied. The results from particle-in-cell (PIC) simulations are presented and discussed. Based on the small signal theory, the coupling coefficient and beam conductance at the gaps were studied, leading to optimization of the multi-slot cavity. The physical analysis of electron movement was carried out to study the influence of electron drifting on device performance. PIC simulations were conducted with the results compared to analytical theory. Good agreement was achieved between analytical predictions and simulations, demonstrating the feasibility of the theoretical approach. The performances of an EIK under different conditions such as mismatching and self-oscillation indicate that an optimized structure can produce an output power of 143 W and a gain of 38.1 dB, demonstrating its potential to be a highly stable and reliable source of coherent sub-terahertz radiation.
Hydrogen production using variable and fixed speed wind farm topologies in a utility grid
Authors: Okedu Kenneth E.
Published: December 2016

This paper presents hydrogen production in a utility grid that is composed of variable and fixed speed wind farms. The variable speed wind farm is made of Doubly Fed Induction Generator (DFIG) wind turbines, while the fixed speed wind farm is composed of only Induction Generator wind turbines. To achieve smoothening of the wind farm terminals, Flexible AC Transmission System devices of an Energy Capacitor System with a DC chopper type and Static Synchronous Compensator were used to stabilize the fixed speed wind farms. The power converters of the DFIGs were used to provide reactive power during dynamic periods to achieve stability of the variable speed wind farm. Since the amount of wind energy required producing hydrogen is insignificant and also by taking advantage of the smoothed terminal of the wind farms, a hydrogen generator composed of a rectifier and electrolyzer is connected to the wind farms to produce hydrogen. The produced hydrogen gas thereby acts as a means of transportation to power fuel cell cars. The cooperative control strategies of the system were developed in the visual simulation Power System Computer Aided Design/Electromagnetic Transient Including DC environment. The results obtained show that it is more cost effective to use the variable speed wind farm topology in hydrogen gas production. The effect of the low pass filter time constant in the electrolyzer circuitry was also investigated in the production of hydrogen gas. On the basis of the same grid energy in the utility network, the average time required to fill the hydrogen tanks using high pass filter time constant is shorter.
Quasi-coherent thermal radiation with multiple resonant plasmonic cavities
Authors: Liao Chun Yen , Wang Chih-Ming , Cheng Bo Han , Chen Yi-Hao , Tsai Wei-Yi , Feng De-Yu , Yeh Ting-Tso , Yen Ta-Jen , Tsai Din Ping
Published: December 2016

This paper proposes a 1D plasmonic multilayer structure as a high-contrast mid-infrared thermal emitter with three distinct resonant wavelengths. The three resonance modes, based on the localized surface plasmon, provide an omnidirectional thermal emission. The emissivity spectrum reveals high polarization and strongly angle-independent properties. The resonance-assisted emissivity can be as high as 19.5 dB relative to off-resonant sideband emissivity. Such extremely low sideband emissivity makes the proposed plasmonic thermal emitter an efficient, high-contrast emitter, which will be useful for thermophotovoltaic and thermal sensing applications.
Stiffness-mass decoupled silicon disk resonator for high resolution gyroscopic application with long decay time constant (8.695 s)
Authors: Zhou Xin , Xiao Dingbang , Wu Xuezhong , Wu Yulie , Hou Zhanqiang , He Kaixuan , Li Qingsong
Published: December 2016

We propose a stiffness-mass decoupling concept for designing large effective mass, low resonant frequency, small size, and high quality factor micro/nanomechanical resonators. This technique is realized by hanging lumped masses on the frame structure. An example of a stiffness-mass decoupled silicon disk resonator for gyroscopic application is demonstrated. It shows a decay time constant of 8.695 s, which is at least 5 times longer than that of the pure frame silicon disk resonator and is even comparable with that of the micromachined three-dimensional wine-glass resonators made from diamond or fused silica. The proposed design also shows a Brownian noise induced angle random walk of 0.0009°/√h, which is suitable for making an inertial grade MEMS gyroscope.
Adiabatic electron affinity of pentacene and perfluoropentacene molecules studied by anion photoelectron spectroscopy: Molecular insights into electronic properties
Authors: Masubuchi Tsugunosuke , Sugawara Yoshito , Nakajima Atsushi
Published: December 2016

Pentacene (C22H14, PEN) and perfluoropentacene (C22F14, PFP) are considered promising building blocks of organic semiconductors. Using gas-phase anion photoelectron spectroscopy, the adiabatic electron affinity of PEN and PFP molecules is determined to be 1.43 ± 0.03 and 2.74 ± 0.03 eV, respectively, and the S0–T1 transition energies of PEN and PFP are evaluated to be 0.96 ± 0.06 and 0.72 ± 0.05 eV, respectively. Photoelectron spectra indicate that the vibronic coupling in PFP is stronger than that in PEN. Quantum chemistry calculations demonstrate that the strong vibronic coupling originates from significant structural displacement upon electron injection to PFP.
Fourier-transform microwave spectroscopy of dimethyl-substituted Criegee intermediate (CH3)2COO
Authors: Nakajima Masakazu , Endo Yasuki
Published: December 2016

Pure rotational transitions of the dimethyl-substituted Criegee intermediate (dimethyl carbonyl oxide, acetone oxide), (CH3)2COO, were observed in the discharge plasma of a C(CH3)2I2/O2 gas mixture by Fourier-transform microwave spectroscopy. The observed spectra show small splittings due to the internal rotations of the two methyl groups. Precise rotational constants of the molecule and the barrier heights of the methyl internal rotations were experimentally determined.
Solvothermal synthesis and good microwave absorbing properties for magnetic porous-Fe3O4/graphene nanocomposites
Authors: Zeng Xiaojun , Yang Bai , Yang Haozhe , Zhu Lingyu , Yu Ronghai
Published: December 2016

The magnetic porous-Fe3O4/graphene nanocomposites have been fabricated by a facile solvothermal method. The porous Fe3O4 nanospheres are embedded uniformly in the graphene oxide (GO) sheets to form a 3D Fe3O4/GO nanocomposite network. The dielectric properties for the Fe3O4/GO composites can be greatly improved by the 7 wt% GO additions. Good impedance matching can be also obtained in these Fe3O4/GO composites, which is proved to dominate their excellent microwave absorbing properties including the minimum reflection loss (RL) value of -43.7 dB at 6.8 GHz with a sample thickness of 5 mm and a broad absorption bandwidth of 5.92 GHz (below -10 dB). These porous-Fe3O4/GO composites also exhibit the good structural stability and low density, which shows their great potential application in high-performance electromagnetic microwave-absorbing materials.
Electromagnetic time reversal focusing of near field waves in metamaterials
Authors: Chabalko Matthew J. , Sample Alanson P.
Published: December 2016

Precise control of electromagnetic energy on a deeply subwavelength scale in the near field regime is a fundamentally challenging problem. In this letter we demonstrate the selective focusing of electromagnetic energy via the electromagnetic time reversal in the near field of a metamaterial. Our analysis begins with fundamental mathematics, and then is extended to the experimental realm where focusing in space and time of the magnetic fields in the near field of a 1-Dimensional metamaterial is shown. Under time reversal focusing, peak instantaneous fields at receiver locations are at minimum ∼200% greater than other receivers. We then leverage the strong selective focusing capabilities of the system to show individual and selective powering of light emitting diodes connected to coil receivers placed in the near field of the metamaterial. Our results show the possibility of improving display technologies, near field imaging systems, increasing channel capacity of near field communication systems, and obtaining a greater control of energy delivery in wireless power transfer systems.
A novel NiZn ferrite integrated magnetic solenoid inductor with a high quality factor at 0.7–6 GHz
Authors: Wang Xinjun , Chen Huaihao , Shi Xiaoling , Gao Yuan , Lin Hwaider , Jones John G. , Howe Brandon M. , Brown Gail J. , Sun Nian X.
Published: December 2016

Integrated inductor is one of the fundamental components and has been widely used in radio frequency integrated circuits (RFICs). It has been challenging to achieve simultaneously high inductance and quality factor, particularly at GHz frequencies. In this work, we reported a novel integrated solenoid inductor with a magnetic NiZn ferrite as the core material, which was deposited by a low-cost spin spray technique. These integrated inductors showed a significant improvement in both inductance and quality factor at GHz frequencies over their air core counterparts. A stable inductance was observed within a wide frequency ranged from 700 MHz to 6 GHz. The peak value of quality factor reached 23, a relatively higher value not reported for solenoid inductors up to date. Our results indicate that the integrated inductor are promising for applications in RFICs.
The irreversible structural change in Mn1.1Fe0.9P0.8Ge0.2: Evidence for a magnetic driver
Authors: Liu Xubo , Ryan D. H. , Cranswick L. M. D. , Liu D. M. , Zhang H. G. , Yue Ming , Altounian Z.
Published: December 2016

Neutron powder diffraction measurements complemented by first-principles density functional theory (DFT) calculations have been used to study the irreversible change that accompanies the reversible magnetocaloric transition (MCT) in Mn1.1Fe0.9P0.8Ge0.2. We observe the growth and loss of long-period antiferromagnetism as we pass through the MCT for the first time and the development of significant strain in the cycled material. We attribute both the reversible and irreversible changes to the distance dependence of the Mn-Mn exchange in the Mn-P(Ge) ab–plane layers.
Reduced complexity of multi-track joint 2-D Viterbi detectors for bit-patterned media recording channel
Authors: Myint L. M. M. , Warisarn C.
Published: December 2016

Two-dimensional (2-D) interference is one of the prominent challenges in ultra-high density recording system such as bit patterned media recording (BPMR). The multi-track joint 2-D detection technique with the help of the array-head reading can tackle this problem effectively by jointly processing the multiple readback signals from the adjacent tracks. Moreover, it can robustly alleviate the impairments due to track mis-registration (TMR) and media noise. However, the computational complexity of such detectors is normally too high and hard to implement in a reality, even for a few multiple tracks. Therefore, in this paper, we mainly focus on reducing the complexity of multi-track joint 2-D Viterbi detector without paying a large penalty in terms of the performance. We propose a simplified multi-track joint 2-D Viterbi detector with a manageable complexity level for the BPMR’s multi-track multi-head (MTMH) system. In the proposed method, the complexity of detector’s trellis is reduced with the help of the joint-track equalization method which employs 1-D equalizers and 2-D generalized partial response (GPR) target. Moreover, we also examine the performance of a full-fledged multi-track joint 2-D detector and the conventional 2-D detection. The results show that the simplified detector can perform close to the full-fledge detector, especially when the system faces high media noise, with the significant low complexity.
The effect of shallow vs. deep level doping on the performance of thermoelectric materials
Authors: Song Qichen , Zhou Jiawei , Meroueh Laureen , Broido David , Ren Zhifeng , Chen Gang
Published: December 2016

It is well known that the efficiency of a good thermoelectric material should be optimized with respect to doping concentration. However, much less attention has been paid to the optimization of the dopant's energy level. Thermoelectric materials doped with shallow levels may experience a dramatic reduction in their figures of merit at high temperatures due to the excitation of minority carriers that reduces the Seebeck coefficient and increases bipolar heat conduction. Doping with deep level impurities can delay the excitation of minority carriers as it requires a higher temperature to ionize all dopants. We find through modeling that, depending on the material type and temperature range of operation, different impurity levels (shallow or deep) will be desired to optimize the efficiency of a thermoelectric material. For different materials, we further clarify where the most preferable position of the impurity level within the bandgap falls. Our research provides insight on why different dopants often affect thermoelectric transport properties differently and directions in searching for the most appropriate dopants for a thermoelectric material in order to maximize the device efficiency.
Band diagrams and field distribution of squarely-modulated slab metallic gratings
Authors: Lee Jih-Yin , Hung Yu-Ju
Published: December 2016

The optical transmission properties of squarely-modulated metallic gratings has been widely investigated. This study used rigorous-coupled wave analysis (RCWA) to re-examine in detail the band structure of a laminated metal film with squarely-modulated metallic gratings located at the top. The top structure was shown to modify the long-range surface plasmon polariton modes (LRSPP) at both interfaces of the thin metal film. When the thickness of the intact metal film was altered, the coupling between the two interfaces presented intriguing behavior. If the thickness of the metallic film was 30nm, the field achieved strong coupling similar to that of a two-level system. When the thickness was decreased to 10nm, the band branch possessing negative group velocity was dominant. Our results also verify that the first-order Fourier expansion of the gratings determined the energy position of bands at k||=0, whereas the second-order term caused band gap opening. Introducing an asymmetrical component to the grating profile intensified the opening effect at k||=0 due to an increase in the amplitude of the second-order Fourier component.
Magnon transport controlled by local parametric excitation
Authors: Tateno Yuma , Ando Kazuya
Published: December 2016

We report that magnetostatic magnon transport can be controlled by local parametric excitation of short-wavelength magnons. We found that the parametrically excited magnon either enhances or suppresses the traveling magnetostatic magnons, depending on the frequency of the magnetostatic magnons. Our time-domain measurements of the magnon transport show that the change in the static magnetization due to the creation of the parametrically excited magnons is responsible for the control of the magnetostatic magnon transport. This result provides insight into magnon-based devices without complex microprocessing.
Improvement in thrust force estimation of solenoid valve considering minor hysteresis loop
Authors: Yoon Myung-Hwan , Choi Yun-Yong , Hong Jung-Pyo
Published: December 2016

Solenoid valve is a very important hydraulic actuator for an automatic transmission in terms of shift quality. The same form of pressure for the clutch and the input current are required for an ideal control. However, the gap between a pressure and a current can occur which brings a delay in a transmission and a decrease in quality. This problem is caused by hysteresis phenomenon. As the ascending or descending magnetic field is applied to the solenoid, different thrust forces are generated. This paper suggests the calculation method of the thrust force considering the hysteresis phenomenon and consequently the accurate force can be obtained. Such hysteresis occurs in ferromagnetic materials, however the hysteresis phenomenon includes a minor hysteresis loop which begins with an initial magnetization curve and is generated by DC biased field density. As the core of the solenoid is ferromagnetic material, an accurate thrust force is obtained by applying the minor hysteresis loop compared to the force calculated by considering only the initial magnetization curve. An analytical background and the detailed explanation of measuring the minor hysteresis loop are presented. Furthermore experimental results and finite element analysis results are compared for the verification.
Thermoelectric detection of inclusions in metallic biomaterials by magnetic sensing
Authors: Carreon Hector
Published: December 2016

The detectability of small inclusions and subtle imperfections by magnetic measurements that senses thermoelectric currents produced by a temperature gradient is ultimately limited by the intrinsic thermoelectric anisotropy and inhomogeneity of the material to be inspected. The probability of detection (POD) of a given material flaw is determined by the resulting signal-to-noise ratio rather than by the absolute magnitude of the signal itself. The strength of the magnetic field to be detected greatly depends on the physical nature of the host medium and dimensions of the imperfection. This paper presents experimental data for the magnetic field produced by thermoelectric currents around tin inclusions in different host medium such as 316LVM stainless steel and Ti-6Al-4V titanium alloy under external thermal excitation. The diameter of the inclusions and the lift-off distance varied from 0.39 to 3.175 mm and from 1 to 10 mm, respectively. A 0.6 °C/cm temperature gradient in the samples produced peak magnetic flux densities ranging from 0.1 to 280 nT, that was measured by a fluxgate magnetometer. The numerical results were found to be in good agreement with theoretical predictions and demonstrated that both property anisotropy and gradient in thermoelectric materials can significantly influence the induced thermoelectric currents and magnetic fields.
Pure spin currents in Ge probed by inverse spin-Hall effect
Authors: Bottegoni F. , Zucchetti C. , Finazzi M. , Isella G. , Ciccacci F.
Published: December 2016

We perform photoinduced inverse spin-Hall effect (ISHE) measurements on a Pt/Ge(001) junction at room temperature. The spin-oriented electrons are photogenerated at the Γ point of the Ge Brillouin zone using circularly-polarized light. After the ultrafast Γ−L scattering in the Ge conduction band, which partially preserves the spin polarization, electrons diffuse into the Pt layer where spin-dependent scattering with Pt nuclei yields a transverse electromotive field EISHE. The ISHE signal dependence as a function of the incident photon energy is investigated and interpreted in the frame of a one-dimensional spin drift-diffusion model. This allows estimating the electron spin lifetime at the L-valleys to be τs=1 ns.
Magnetic properties of Sm-Fe-N bulk magnets produced from Cu-plated Sm-Fe-N powder
Authors: Saito Tetsuji , Deguchi Tomoe , Yamamoto Hitoshi
Published: December 2016

In this study, Cu-plated Sm-Fe-N powder was prepared for consolidation by the SPS method. The structures and magnetic properties of Sm-Fe-N bulk magnets produced from the Cu-plated Sm-Fe-N powder were examined. It was found that the powder could be consolidated into bulk materials at low temperatures of 473–673 K. The Sm-Fe-N magnet produced at a temperature of 473K from the Cu-plated Sm-Fe-N powder showed a high coercivity of 9.5 kOe, close to that of the Sm-Fe-N powder.
Prolonged silicon carbide integrated circuit operation in Venus surface atmospheric conditions
Authors: Neudeck Philip G. , Meredith Roger D. , Chen Liangyu , Spry David J. , Nakley Leah M. , Hunter Gary W.
Published: December 2016

The prolonged operation of semiconductor integrated circuits (ICs) needed for long-duration exploration of the surface of Venus has proven insurmountably challenging to date due to the ∼ 460 °C, ∼ 9.4 MPa caustic environment. Past and planned Venus landers have been limited to a few hours of surface operation, even when IC electronics needed for basic lander operation are protected with heavily cumbersome pressure vessels and cooling measures. Here we demonstrate vastly longer (weeks) electrical operation of two silicon carbide (4H-SiC) junction field effect transistor (JFET) ring oscillator ICs tested with chips directly exposed (no cooling and no protective chip packaging) to a high-fidelity physical and chemical reproduction of Venus’ surface atmosphere. This represents more than 100-fold extension of demonstrated Venus environment electronics durability. With further technology maturation, such SiC IC electronics could drastically improve Venus lander designs and mission concepts, fundamentally enabling long-duration enhanced missions to the surface of Venus.
Coercivity of Nd-Fe-B hot-deformed magnets produced by the spark plasma sintering method
Authors: Saito Tetsuji , Nozaki Shunji , Sajima Yusuke , Nishio-Hamane Daisuke
Published: December 2016

The effects of Nd-Cu alloy powder addition on the microstructures and magnetic properties of Nd-Fe-B hot-deformed magnets produced by the spark plasma sintering (SPS) method were investigated. The addition of a small amount of Nd-Cu alloy powder, up to 2%, significantly increased the coercivity of the Nd-Fe-B hot-deformed magnets without deteriorating the crystallographic alignment of the Nd2Fe14B phase. The Nd-Fe-B hot-deformed magnet with 2% Nd-Cu alloy powder had the same remanence value as the Nd-Fe-B hot-deformed magnet without Nd-Cu alloy powder addition, but the magnet with 2% Nd-Cu alloy powder exhibited higher coercivity and a higher maximum energy product than the magnet without Nd-Cu alloy powder addition.
Zinc doped copper ferrite particles as temperature sensors for magnetic resonance imaging
Authors: Hankiewicz Janusz H. , Alghamdi Noweir , Hammelev Nicholas M. , Anderson Nick R. , Camley Robert E. , Stupic Karl , Przybylski Marek , Zukrowski Jan , Celinski Zbigniew J.
Published: December 2016

We investigate the use of Cu0.35Zn0.65Fe2O4 particles as temperature-dependent sensors in magnetic resonance imaging (MRI). This material has a Curie temperature near 290 K, but in the large magnetic fields found in MRI scanners, there is a significant temperature-dependent magnetic moment near body temperature; 310 K. When the ferrite particles are doped into an agar gel, the temperature-dependent magnetic moment leads to a temperature-dependent broadening of the NMR linewidth for water protons and to a temperature-dependent image intensity for MRI, allowing one to make temperature maps within objects. The temperature resolution is about 1.3 K.
Fast response of superconducting hot-electron bolometers with a twin-slot nano-antenna for mid-infrared operation
Authors: Kawakami Akira , Shimakage Hisashi , Horikawa Junsei , Hyodo Masaharu , Saito Shingo , Tanaka Shukichi , Uzawa Yoshinori
Published: December 2016

In this study, the use of nano-antennas to improve the response performance of infrared detectors is proposed, and the design and fabrication of antennas that operate in the infrared range is demonstrated. Prototypes of a mid-infrared superconducting hot-electron bolometer (HEB) formed by a twin-slot antenna with a niobium nitride strip were fabricated. When the bolometer was irradiated with mid-infrared (λ = 4.89 μm) pulsed light, responses with clear polarization dependency were observed. When the HEB was biased close to the critical current under mid-infrared pulsed light irradiation, the detector output synchronized with the trigger signal was observed. The output waveforms comprised voltage pulse trains, and the full width at half maximum of the pulse was evaluated to be approximately 0.3 ns.
Experimental ex-vivo validation of PMMA-based bone cements loaded with magnetic nanoparticles enabling hyperthermia of metastatic bone tumors
Authors: Harabech Mariem , Kiselovs Normunds Rungevics , Maenhoudt Wim , Crevecoeur Guillaume , Van Roost Dirk , Dupré Luc
Published: December 2016

Percutaneous vertebroplasty comprises the injection of Polymethylmethacrylate (PMMA) bone cement into vertebrae and can be used for the treatment of compression fractures of vertebrae. Metastatic bone tumors can cause such compression fractures but are not treated when injecting PMMA-based bone cement. Hyperthermia of tumors can on the other hand be attained by placing magnetic nanoparticles (MNPs) in an alternating magnetic field (AMF). Loading the PMMA-based bone cement with MNPs could both serve vertebra stabilization and metastatic bone tumor hyperthermia when subjecting this PMMA-MNP to an AMF. A dedicated pancake coil is designed with a self-inductance of 10 μH in series with a capacitance of 0.1 μF that acts as resonant inductor-capacitor circuit to generate the AMF. The thermal rise is appraised in beef vertebra placed at 10 cm from the AMF generating circuit using optical temperatures sensors, i.e. in the center of the PMMA-MNP bone cement, which is located in the vicinity of metastatic bone tumors in clinical applications; and in the spine, which needs to be safeguarded to high temperature exposures. Results show a temperature rise of about 7 °C in PMMA-MNP whereas the temperature rise in the spine remains limited to 1 °C. Moreover, multicycles heating of PMMA-MNP is experimentally verified, validating the technical feasibility of having PMMA-MNP as basic component for percutaneous vertebroplasty combined with hyperthermia treatment of metastatic bone tumors.
MgO-C interlayer for grain size control in FePt-C media for heat assisted magnetic recording
Authors: Varaprasad B. S. D. Ch. S. , Zhou Bing , Mo Tong , Laughlin David E. , Zhu Jian-Gang
Published: December 2016

Currently, the most common recording media used for heat assisted magnetic recording is granular L10 based FePt-C directly deposited on a highly textured polycrystalline MgO underlayer. In this study, a thin granular MgO-C interlayer is inserted between the MgO underlayer and the granular L10-FePt-C magnetic layer to control the grain size of the magnetic media. By varying the deposition conditions of the MgO-C interlayer, we can vary the size of the L10-ordered FePt grains from about 10.5 nm to 7.6nm, while keeping the carbon composition in the magnetic layer unchanged. With the optimized interlayer, the L10-FePt-C media of grain size to 7.6 nm shows good squareness and perpendicular coercivity of 47 kOe as well as an order parameter of S = 0.85.
Achromatopsia mutations target sequential steps of ATF6 activation
Authors: Chiang Wei-Chieh , Chan Priscilla , Wissinger Bernd , Vincent Ajoy , Skorczyk-Werner Anna , Krawczyński Maciej R. , Kaufman Randal J. , Tsang Stephen H. , Héon Elise , Kohl Susanne , Lin Jonathan H.
Published: December 2016

Significance

The unfolded protein response regulator activating transcription factor 6 (
ATF6
) was recently identified as a novel genetic cause of the cone photoreceptor disease achromatopsia. ATF6 upregulates genes that help cells cope with endoplasmic reticulum stress. We identified the pathomechanisms of all
ATF6
achromatopsia mutations. Class 1 ATF6 mutants show impaired endoplasmic reticulum (ER)-to-Golgi trafficking and diminished production of the transcriptional activator fragment. Class 2 mutants encode the intact ATF6 transcriptional activator domain with full activity. Class 3 mutants have defective basic leucine zipper (bZIP) domains with abrogated function. Patient fibroblasts show increased apoptosis after ER stress. Our findings reveal that human
ATF6
mutations interrupt distinct steps of ATF6 activation. ER stress-associated damage may underlie the pathology of achromatopsia arising from
ATF6
.
Two distinct pools of B12analogs reveal community interdependencies in the ocean
Authors: Heal Katherine R. , Qin Wei , Ribalet Francois , Bertagnolli Anthony D. , Coyote-Maestas Willow , Hmelo Laura R. , Moffett James W. , Devol Allan H. , Armbrust E. Virginia , Stahl David A. , Ingalls Anitra E.
Published: December 2016

Significance

Cobalamin (vitamin B12)-dependent organisms span all domains of life, making procurement of the vitamin from the few prokaryotic producers an essential function in organismal interactions. Yet not all key producers of cobalamin have been identified in the ocean. We show that in the marine environment, select heterotrophic bacteria and Thaumarchaeota produce cobalamin, while Cyanobacteria, the most abundant phytoplankton on earth, supply and use pseudocobalamin. These chemically distinct cofactors support different members of the microbial community because they are not interchangeable as cofactors in enzymes. Our findings identify key organisms supporting cobalamin-based interdependencies that underpin primary production and microbial interactions in the ocean.
Loss of the golgin GM130 causes Golgi disruption, Purkinje neuron loss, and ataxia in mice
Authors: Liu Chunyi , Mei Mei , Li Qiuling , Roboti Peristera , Pang Qianqian , Ying Zhengzhou , Gao Fei , Lowe Martin , Bao Shilai
Published: December 2016

Significance

It has been known for many years that the Golgi apparatus, the central organelle of the secretory pathway, is fragmented upon neurodegenerative disease. However, it has remained an open question whether Golgi disruption contributes to neuronal death, as seen in disease, or is simply a consequence of this process. Here, we show that knocking out the Golgi protein GM130 in mice causes Golgi fragmentation and impaired secretory trafficking in Purkinje neurons, resulting in cell death and ataxia. The cell death and ataxia are first observed in postnatal development, but worsen with age. These findings indicate that targeted disruption of the Golgi apparatus can result in neuronal loss in vivo, supporting the view that Golgi dysfunction can contribute to neurodegeneration.
Tracking solvents in the skin through atomically resolved measurements of molecular mobility in intact stratum corneum
Authors: Pham Quoc Dat , Topgaard Daniel , Sparr Emma
Published: December 2016

Significance

Our skin is regularly exposed to solvents in cosmetics, washing and sanitary agents, and drug formulations. The uptake of solvents into the skin may change essential properties of the skin, for example, its protective barrier function, as well as its flexibility and softness. Herein different solvents relevant to skin formulations and sanitary products were added to samples of intact stratum corneum (SC), which is the outer layer of the skin. The solvent molecules can be tracked inside SC, showing reduced mobility. Furthermore, the solvents induce fluidity in SC components. These changes depend on solvent identity and concentration and on SC hydration conditions. Changes in SC components can be related to changes in macroscopic properties of SC, including skin barrier function.
Holocene carbonate record of Lake Kivu reflects the history of hydrothermal activity
Authors: Votava Jillian E. , Johnson Thomas C. , Hecky Robert E.
Published: December 2016

Significance

Lake Kivu is unusually stratified as a result of active volcanism nearby, with warmer, more saline water holding high concentrations of methane and CO
2
, underlying cooler fresh water. We find that the history of carbonate sedimentation in Lake Kivu reflects the timing and duration of past hydrothermal input to the lake. The stable isotopic composition of aragonite (CaCO
3
) and the lake’s calcium budget reveal the strong link between hydrothermal input and aragonite deposition, which has occurred intermittently over just the past 3.1 ky. The sporadic injection of hydrothermal fluids and gases to the lake signals the difficulty of predicting future trends and potential for catastrophic degassing, which would be potentially fatal to >2 million people living near the lake shore.
The importance of urban gardens in supporting children's biophilia
Authors: Hand Kathryn L. , Freeman Claire , Seddon Philip J. , Recio Mariano R. , Stein Aviva , van Heezik Yolanda
Published: December 2016

Significance

Nature exposure is an important determinant of human mental and physical well-being, but rapid urbanization means that accessing natural areas is increasingly challenging. Children in particular are thought to show a deep affective affiliation with life (biophilia), and health disorders, such as attention-deficit hyperactivity disorder, stress, obesity, and depression, are attributed to lack of interaction with wild nature, termed “nature-deficit disorder.” We tested biophilia in children by quantitatively evaluating the availability and use of biodiverse spaces, and found no evidence of preference for biodiverse or wild areas, even where children had access to highly biodiverse areas. Because of constrained movements, children’s exposure to nature occurred mostly in private gardens, which are disappearing with densification and ongoing loss of private greenspace.
APE2 Zf-GRF facilitates 3′-5′ resection of DNA damage following oxidative stress
Authors: Wallace Bret D. , Berman Zachary , Mueller Geoffrey A. , Lin Yunfeng , Chang Timothy , Andres Sara N. , Wojtaszek Jessica L. , DeRose Eugene F. , Appel C. Denise , London Robert E. , Yan Shan , Williams R. Scott
Published: December 2016

Significance

Zf-GRF domains are found in more than 100 eukaryotic architectures, including key proteins modulating DNA damage response and transcription. We establish the apurinic/apyrimidinic endonuclease 2 (APE2) Zf-GRF domain as a prototypical member of the Zf-GRF class of nucleic acid-binding modules, and through structural analysis reveal that the APE2 protein is composed of a compacted three-stranded β-sheet and a CHCC Zn
2+
-binding site, harboring structure-specific ssDNA-binding activity. Notably, the ssDNA-binding region of APE2 Zf-GRF is required for the 3′-5′ end resection of oxidative DNA damage and activation of the ATR-Chk1 DNA damage response pathway following oxidative stress. This distinct regulatory mechanism of APE2 exonuclease activity by ssDNA binding via Zf-GRF may extend to other Zf-GRF–containing proteins.