bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct observation of resonance scattering patterns in single silicon nanoparticles
Authors: Valuckas Vytautas , Paniagua-Domínguez Ramón , Fu Yuan Hsing , Luk'yanchuk Boris , Kuznetsov Arseniy I.
Published: March 2017

We present the first direct observation of the scattering patterns of electric and magnetic dipole resonances excited in a single silicon nanosphere. Almost perfectly spherical silicon nanoparticles were fabricated and deposited on a 30 nm-thick silicon nitride membrane in an attempt to minimize particle—substrate interaction. Measurements were carried out at visible wavelengths by means of the Fourier microscopy in a dark-field illumination setup. The obtained back-focal plane images clearly reveal the characteristic scattering patterns associated with each resonance and are found to be in a good agreement with the simulated results.
Membrane stress profiles from self-consistent field theory
Authors: Ting Christina L. , Müller Marcus
Published: March 2017

Using self-consistent field theory (SCFT), we develop an accurate, local expression for the stress profiles in membranes and soft matter interfaces, in general. The bond stresses are expressed in terms of pre-computed chain propagators, which are used to describe the statistical weight of the molecules and therefore require minimal additional calculations. In addition, we overcome the resolution limit of the molecular bond length by including the Irving and Kirkwood bond assignment and recover a constant normal stress profile across an interface. Using this theory, we find that the membrane lateral stress profile contains repulsive (positive) stresses in the regions of the head and tail groups, and attractive (negative) stresses near the hydrophobic/hydrophilic interface. We also verify that the zeroth and first moments of the stress profile correspond to the thermodynamic tension and product of the bending modulus and the spontaneous curvature, respectively.
Control of fluorescence in quantum emitter and metallic nanoshell hybrids for medical applications
Authors: Singh Mahi R. , Guo Jiaohan , J. Cid José M. , De Hoyos Martinez Jesús E.
Published: March 2017

We study the light emission from a quantum emitter and double metallic nanoshell hybrid systems. Quantum emitters act as local sources which transmit their light efficiently due to a double nanoshell near field. The double nanoshell consists of a dielectric core and two outer nanoshells. The first nanoshell is made of a metal, and the second spacer nanoshell is made of a dielectric material or human serum albumin. We have calculated the fluorescence emission for a quantum emitter-double nanoshell hybrid when it is injected in an animal or a human body. Surface plasmon polariton resonances in the double nanoshell are calculated using Maxwell's equations in the quasi-static approximation, and the fluorescence emission is evaluated using the density matrix method in the presence of dipole-dipole interactions. We have compared our theory with two fluorescence experiments in hybrid systems in which the quantum emitter is Indocyanine Green or infrared fluorescent molecules. The outer spacer nanoshell of double metallic nanoshells consists of silica and human serum albumin with variable thicknesses. Our theory explains the enhancement of fluorescence spectra in both experiments. We find that the thickness of the spacer nanoshell layer increases the enhancement when the fluorescence decreases. The enhancement of the fluorescence depends on the type of quantum emitter, spacer layer, and double nanoshell. We also found that the peak of the fluorescence spectrum can be shifted by changing the shape and the size of the nanoshell. The fluorescence spectra can be switched from one peak to two peaks by removing the degeneracy of excitonic states in the quantum emitter. Hence, using these properties, one can use these hybrids as sensing and switching devices for applications in medicine.
Arsenic antisite and oxygen incorporation trends in GaAs grown by water-mediated close-spaced vapor transport
Authors: Boucher Jason , Boettcher Shannon
Published: March 2017

Close-spaced vapor transport (CSVT) provides a plausible path to lower the costs of GaAs deposition as it uses only solid precursors and provides precursor utilization in principle approaching 100%. However, the use of H2O as a transport agent causes O to be incorporated in CSVT films, and O has been associated with a number of electrically active defect centers in GaAs, which decrease minority carrier lifetimes. Using deep-level transient spectroscopy, we study the effect of H2O concentration and substrate temperature on electron trap concentrations in n-type GaAs. We find that the most-prominent O-related center (ELO) typically has a much higher concentration than the center usually associated with As antisites (EL2), but that overall defect concentrations can be as low as those in films deposited by common vapor phase techniques. The trends with increasing H2O concentration suggest that ELO is most likely a defect complex with two As antisites. We also consider the optimal conditions for achieving high growth rates and low defect concentrations using CSVT. The results of this study have implications for the future CSVT growth using halide transport agents, where the ELO defect would be eliminated but EL2 might have a higher concentration.
Schottky barrier diode based on β-Ga2O3 (100) single crystal substrate and its temperature-dependent electrical characteristics
Authors: He Qiming , Mu Wenxiang , Dong Hang , Long Shibing , Jia Zhitai , Lv Hangbing , Liu Qi , Tang Minghua , Tao Xutang , Liu Ming
Published: March 2017

The Pt/β-Ga2O3 Schottky barrier diode and its temperature-dependent current-voltage characteristics were investigated for power device application. The edge-defined film-fed growth (EFG) technique was utilized to grow the (100)-oriented β-Ga2O3 single crystal substrate that shows good crystal quality characterized by X-ray diffraction and high resolution transmission electron microscope. Ohmic and Schottky electrodes were fabricated by depositing Ti and Pt metals on the two surfaces, respectively. Through the current-voltage (I-V) measurement under different temperature and the thermionic emission modeling, the fabricated Pt/β-Ga2O3 Schottky diode was found to show good performances at room temperature, including rectification ratio of 1010, ideality factor (n) of 1.1, Schottky barrier height (ΦB) of 1.39 eV, threshold voltage (Vbi) of 1.07 V, ON-resistance (RON) of 12.5 mΩ·cm2, forward current density at 2 V (J@2V) of 56 A/cm2, and saturation current density (J0) of 2 × 10−16 A/cm2. The effective donor concentration Nd − Na was calculated to be about 2.3 × 1014 cm3. Good temperature dependent performance was also found in the device. The Schottky barrier height was estimated to be about 1.3 eV–1.39 eV at temperatures ranging from room temperature to 150 °C. With increasing temperature, parameters such as RON and J@2V become better, proving that the diode can work well at high temperature. The EFG grown β-Ga2O3 single crystal is a promising material to be used in the power devices.
“Noiseless” thermal noise measurement of atomic force microscopy cantilevers
Authors: Pottier Basile , Bellon Ludovic
Published: March 2017

When measuring quadratic values representative of random fluctuations, such as the thermal noise of Atomic Force Microscopy (AFM) cantilevers, the background measurement noise cannot be averaged to zero. We present a signal processing method that allows to get rid of this limitation using the ubiquitous optical beam deflection sensor of standard AFMs. We demonstrate a two orders of magnitude enhancement of the signal to noise ratio in our experiment, allowing the calibration of stiff cantilevers or easy identification of higher order modes from thermal noise measurements.
Honey bees (Apis mellifera ligustica) swing abdomen to dissipate residual flying energy landing on a wall
Authors: Zhao Jieliang , Huang He , Yan Shaoze
Published: March 2017

Whether for insects or for aircrafts, landing is one of the indispensable links in the verification of airworthiness safety. The mechanisms by which insects achieve a fast and stable landing remain unclear. An intriguing example is provided by honeybees (Apis mellifera ligustica), which use the swinging motion of their abdomen to dissipate residual flying energy and to achieve a smooth, stable, and quick landing. By using a high-speed camera, we observed that touchdown is initiated by honeybees extending their front legs or antennae and then landing softly on a wall. After touchdown, they swing the rest of their bodies until all flying energy is dissipated. We suggested a simplified model with mass-spring dampers for the body of the honeybee and revealed the mechanism of flying energy transfer and dissipation in detail. Results demonstrate that body translation and abdomen swinging help honeybees dissipate residual flying energy and orchestrate smooth landings. The initial kinetic energy of flying is transformed into the kinetic energy of the abdomen's rotary movement. Then, the kinetic energy of rotary movement is converted into thermal energy during the swinging cycle. This strategy provides more insight into the mechanism of insect flying, which further inspires better design on aerial vehicle with better landing performance.
Zr doping on lithium niobate crystals: Raman spectroscopy and chemometrics
Authors: Kokanyan Ninel , Chapron David , Kokanyan Edvard , Fontana Marc D.
Published: March 2017

Raman measurements were investigated on Zr-doped lithium niobate LiNbO3 crystals with different concentrations. Spectra were treated by fitting procedure and principal component analysis which both provide results consistent with each other. The concentration dependence of the frequency on the main low-frequency optical phonons provides an insight of site incorporation of Zr ions in the host lattice. The threshold concentration of about 2% is evidenced, confirming the interest of Zr doping as an alternative to Mg doping for the reduction of the optical damage in lithium niobate.
Magnetic ordering induced ferroelectricity in α-Cu2V2O7 studied through non-magnetic Zn doping
Authors: Chattopadhyay Bidisa , Ahmed Md. A. , Bandyopadhyay S. , Singha R. , Mandal P.
Published: March 2017

We have studied the magnetic and electronic properties of Cu2-xZnxV2O7 by magnetization, specific heat, and dielectric measurements. X-ray structural analysis shows a Zn-mediated phase transition from the α- to the β-phase beyond a critical Zn concentration of xc = 0.15. While Cu2V2O7 exhibits a canted antiferromagnetism with an associated weak ferromagnetism in the α-phase, the β-phase is purely antiferromagnetic. The spin canting arises due to the Dzyaloshinskii-Moriya exchange interaction in the anti-symmetric α-phase. The temperature dependence of the heat capacity for the sample in the α-phase shows a clear lambda like transition at a temperature where the magnetic susceptibility also displays an anomaly and indicates an onset of long range magnetic ordering. Dielectric properties display a clear anomaly around the magnetic transition temperature in α-Cu2V2O7. The anomaly weakens with the increase in the Zn concentration and disappears at the doping level where α to β phase transition occurs. This confirms the existence of magneto-electric coupling in α-Cu2V2O7 but not in its β-phase. Analysis of the experimental data shows that magneto-electric coupling is non-linear in nature, which is in agreement with the Landau theory of continuous phase transition. So, α-Cu2V2O7 establishes itself as a promising candidate for magnetic multiferroics.
Dynamic stiffness of the contact between a carbon nanotube and a flat substrate in a peeling geometry
Authors: Li Tianjun , Champougny Lorène , Bellon Ludovic
Published: March 2017

We study the physics of adhesion and the contact mechanics at the nanoscale with a peeling experiment of a carbon nanotube on a flat substrate. Using an interferometric atomic force microscope and an extended force modulation protocol, we investigate the frequency response of the stiffness of the nano-contact from DC to 20 kHz. We show that this dynamic stiffness is only weakly frequency dependent, increasing by a factor 2 when the frequency grows by 3 orders of magnitude. Such behavior may be the signature of amorphous relaxations during the mechanical solicitation at the nano-scale.
The effect of disorder on spin hall conductance in the bulk states of HgTe/CdTe heterostructure
Authors: Wu Hai-Bin , Zhang Ying-Tao , Liu Jian-Jun
Published: March 2017

By using the Green's function method, we have investigated spin Hall conductance (SHC) in a four terminal quantum spin Hall insulator. The results show that the intrinsic spin orbit coupling in a HgTe/CdTe hetero-structure interface naturally leads to separate probability distributions for the two spins in coordinate space, which leads to the spin Hall effect in our proposed device. We also find that the SHC of bulk states exhibits an oscillatory behavior as a function of the device width and persists at a broad device width. In addition, we calculate the effects of disorder on the SHC of the bulk states of non-trivial and trivial topology. The results indicate that the spin up and spin down conductances show different degrees of suppression by disorder; thus the SHC could be significantly enhanced by the disorder. This kind of property has a great value to practical applications.
Angular magnetoresistance oscillations in the tunneling conductance of a metallic heterojunction
Authors: Smith M. F. , Khudwilat Alongkorn
Published: March 2017

The interlayer magnetoresistance of a metallic sandwich junction, i.e., a junction of the form MM′M, where M is an atomic layer of one metal and M′ an atomic layer of a different metal, is calculated semiclassically. According to the picture developed below, an electron follows a semiclassical cyclotron orbit on one M layer and, upon reaching an intersection between M and M′ Fermi surfaces, can tunnel to the other M layer via M′. It tunnels back to the original M layer at a different Fermi surface intersection, having accumulated a magnetic field-dependent phase factor. The resulting angle-dependent magnetoresistance oscillations exhibit discrete frequencies, associated with pairs of intersections of the M and M′ Fermi surfaces. These oscillations persist down to relatively weak magnetic fields because they are less susceptible to destructive interference than the continuum of frequencies seen for bilayer MM junctions. The MM′M trilayer exhibits large magnetoresistance with fields perpendicular to the junction because an increase in cyclotron frequency reduces the tunneling probability at Fermi surface intersections. The distinctive magnetoresistance of the trilayer junction could be exploited to study the electronic structure of metallic interfaces.
Thermoelectric studies of nanoporous thin films with adjusted pore-edge charges
Authors: Hao Qing , Zhao Hongbo , Xu Dongchao
Published: March 2017

In recent years, nanoporous thin films have been widely studied for thermoelectric applications. High thermoelectric performance is reported for nanoporous Si films, which is attributed to the dramatically reduced lattice thermal conductivity and bulk-like electrical properties. Porous materials can also be used in gas sensing applications by engineering the surface-trapped charges on pore edges. In this work, an analytical model is developed to explore the relationship between the thermoelectric properties and pore-edge charges in a periodic two-dimensional nanoporous material. The presented model can be widely used to analyze the measured electrical properties of general nanoporous thin films and two-dimensional materials.
Retrodirective tracking of a moving target using phase conjugate light generated in a Fabry–Pérot Nd:YAG laser
Authors: Kawakami K. , Komurasaki K. , Okamura H.
Published: March 2017

This report describes the retrodirective tracking of a target moving at a constant speed using a Fabry–Pérot laser resonator-type self-starting phase conjugator. Three-dimensional pointing ability was confirmed with this system: the generated phase conjugate light can focus at a target position. To track the moving targets, target-reflected light is Doppler-shifted, which causes wash-out of the gain grating. To address this problem, numerical analysis and experiments showed that shortening the pulse width is an efficient means of eliminating the gain grating wash-out effect. For the measured target speeds of 0–80 mm/s, the phase conjugate light output is unaffected when the pulse width of 18 ns was used, in contrast to the case of 400 μs pulse width, where the phase conjugate light output rapidly decreased as the target speed approached 10 mm/s. Numerical simulation revealed that phase conjugate light can even be generated for fast-moving targets such as space debris in low-earth-orbit with pulses of several tens of picoseconds. Unlike conventional mechanical gimbal steering methods, this system is applicable for wireless energy transfer to rapidly moving objects.
Recombination parameters of lifetime-limiting carrier-induced defects in multicrystalline silicon for solar cells
Authors: Vargas Carlos , Zhu Yan , Coletti Gianluca , Chan Catherine , Payne David , Jensen Mallory , Hameiri Ziv
Published: March 2017

In p-type multicrystalline silicon solar cells, carrier-induced degradation (CID) can cause up to 10% relative reduction in conversion efficiency. Although, a great concern has been drawn on this degradation in the photovoltaic community, the nature of this degradation is still yet unknown. In this contribution, the recombination parameters of the responsible defect causing this degradation are extracted via temperature and injection dependent lifetime spectroscopy. Three wafers from three different ingots were processed into cell precursor and lifetime structures for the study. Similar defect recombination parameters were obtained for all samples. Two candidates for the defect energy level were identified: Et − Ei = −(0.32 ± 0.05) eV or Et − Ei = (0.21 ± 0.05) eV in the lower and upper bandgap halves, respectively. The capture cross section ratios were found to be k = 56 ± 23 or k = 49 ± 21 for the lower and upper bandgap halves, respectively. Contrary to previous studies, these parameters have been extracted for the responsible defect of CID, without making assumptions regarding the defect energy level. The result allows to model and to predict the impact of this defect on the solar cell efficiency.
Localization of open-shell molecular orbitals via least change from fragments to molecule
Authors: Li Hongyang , Liu Wenjian , Suo Bingbing
Published: March 2017

Both top-down and bottom-up localization schemes are proposed for constructing localized molecular orbitals (LMOs) of open-shell systems, via least change from fragments to molecule. The success of both schemes stems from (1) the primitive fragment LMOs that are local not only in space but also in energy and (2) the “conquer step” that allows arbitrary assignment of the unpaired electrons to fragments. Moreover, integral occupations are retained, so as to facilitate subsequent treatment of electron correlation and excitation.
The nature of the chemical bond in BeO0,−, BeOBe+,0,−, and in their hydrogenated products HBeO0,−, BeOH, HBeOH, BeOBeH+,0,−, and HBeOBeH
Authors: Kalemos Apostolos
Published: March 2017

The nature of the chemical bond in BeO0,−, BeOBe+,0,−, and in their hydrogenated products HBeO0,−, BeOH, HBeOH, BeOBeH+,0,−, and HBeOBeH has been studied through single and multi reference correlation methods. In all these species, excited and ionized atomic states participate in a resonant way making chemically possible molecules that have been termed hypervalent and explain also the “incompatible” geometrical structure of some species.
Electrical transport properties in Co nanocluster-assembled granular film
Authors: Zhang Qin-Fu , Wang Lai-Sen , Wang Xiong-Zhi , Zheng Hong-Fei , Liu Xiang , Xie Jia , Qiu Yu-Long , Chen Yuanzhi , Peng Dong-Liang
Published: March 2017

A Co nanocluster-assembled granular film with three-dimensional cross-connection paralleled conductive paths was fabricated by using the plasma-gas-condensation method in a vacuum environment. The temperature-dependent longitudinal resistivity and anomalous Hall effect of this new type granular film were systematically studied. The longitudinal resistivity of the Co nanocluster-assembled granular film first decreased and then increased with increasing measuring temperature, revealing a minimum value at certain temperature, Tmin. In a low temperature region (T<Tmin), the barrier between adjacent nanoclusters governed the electrical transport process, and the temperature coefficient of resistance (TCR) showed an insulator-type behavior. The thermal fluctuation-induced tunneling conduction progressively increased with increasing temperature, which led to a decrease in the longitudinal resistivity. In a high temperature region, the TCR showed a metallic-type behavior, which was primarily attributed to the temperature-dependent scattering. Different from the longitudinal resistivity behavior, the saturated anomalous Hall resistivity increased monotonically with increasing measuring temperature. The value of the anomalous Hall coefficient (RS) reached 2.3 × 10−9 (Ω cm)/G at 300 K, which was about three orders of magnitude larger than previously reported in blocky single-crystal Co [E. N. Kondorskii, Sov. Phys. JETP 38, 977 (1974)]. Interestingly, the scaling relation (ρxyA∝ρxxγ) between saturated anomalous Hall resistivity (ρxyA) and longitudinal resistivity (ρxx) was divided into two regions by Tmin. However, after excluding the contribution of tunneling, the scaling relation followed the same rule. The corresponding physical mechanism was also proposed to explain these phenomena.
Meta-atom microfluidic sensor for measurement of dielectric properties of liquids
Authors: Awang Robiatun A. , Tovar-Lopez Francisco J. , Baum Thomas , Sriram Sharath , Rowe Wayne S. T.
Published: March 2017

High sensitivity microwave frequency microfluidic sensing is gaining popularity in chemical and biosensing applications for evaluating the dielectric properties of liquid samples. Here, we show that a tiny microfluidic channel positioned in the gaps of a dual-gap meta-atom split-ring resonator can exploit the electric field sensitivity to predict the dielectric properties of liquid samples. Employing an empirical relation between resonant characteristics of the fabricated sensor and the complex permittivity of water-ethanol or water-methanol mixtures produces good congruence to standardized values from the literature. This microfluidic sensor offers a potential lab-on-chip solution for liquid dielectric characterization without external electrical connections.
Visualizing near-field coupling in terahertz dolmens
Authors: Halpin Alexei , Mennes Christiaan , Bhattacharya Arkabrata , Gómez Rivas Jaime
Published: March 2017

Strong interactions between resonant structures in the near-field occur at length scales shorter than the wavelength, and can be exploited for modifying the propagation of electromagnetic radiation. Dolmen-like structures, formed by a rod supporting a dipolar (bright) resonance and two orthogonal rods with a quadrupolar (dark) resonance at the same frequency, represent a geometry of significant interest for near-field electromagnetic coupling. These structures demonstrate electromagnetically induced transparency (EIT) through coupling between these resonances, concurrently providing a sharp spectral selectivity in transmission and large group velocity reduction. We use near-field terahertz scanning microscopy to map the electric fields in the vicinity of a metallic dolmen in both amplitude and phase. In this way, we directly measure the interaction between bright and dark modes in the time-domain, revealing the physics resulting in EIT. We experimentally demonstrate the hybridization of bright and dark modes accompanying the near-field coupling, as well as the excitation of the dark mode at the frequency of the far-field transparency.
Specific heat anomaly in relaxor ferroelectrics and dipolar glasses
Authors: Kutnjak Z. , Pirc R.
Published: March 2017

The temperature and electric field dependence of the specific heat of relaxor ferroelectrics and dipolar glasses is investigated by means of a Landau-type theoretical model. It is shown that the dipolar specific heat, which is due to the randomly interacting polar nanoregions in relaxors and electric dipoles in dipolar glasses, is negative in a temperature region below the permittivity maximum. Also, it follows that for sufficiently low values of the field, where the induced polarization shows a quasi linear field dependence, the dipolar specific heat is proportional to the second temperature derivative of the dielectric polarization. This quantity can be extracted from the experimental temperature profile of the polarization, thus enabling an indirect experimental estimate of the negative specific heat, which is demonstrated for a set of representative relaxor and dipolar glass systems.
Spall strength of liquid copper and accuracy of the acoustic method
Authors: Cai Y. , Wu H. A. , Luo S. N.
Published: March 2017

We investigate spallation in liquid copper at high strain rates induced by planar shock loading with classical molecular dynamics simulations. Spallation simulations are performed at different initial temperatures, shock durations, and shock strengths. Loading may have pronounced effects on spall strength. The acoustic method for deducing spall strength and strain rate from free surface velocity histories is discussed in detail and compared to direct simulations. The effects of temperature rise induced by shock wave, tension attenuation, sound speed, and density on the accuracy of the acoustic method are examined; the contributing factors to errors are identified; and the modifications to the choice of sound speed and density are proposed to improve the accuracy of the acoustic method.
High-speed tomography of local-plasma-induced rapid microwave sintering of aluminum
Authors: Xu Feng , Liu Wenchao , Xiao Yu , Dong Bo , Hu Xiaofang , Wu Xiaoping
Published: March 2017

In this work, we used in situ high-speed synchrotron radiation computed tomography to verify that a local microwave plasma occurs during microwave sintering of aluminum. The local plasma originated from strong electric field enhancement in the intersection of a T-shaped pair of needle-shaped particles. We proposed a rapid evolution mechanism, the key parameters of which were determined on the basis of the characteristics of the microstructure. The electric field enhancement decreased with increasing angle between the electric field and the needle-shaped particle, and increased with increasing particle length. These results may lead to further research into microwave sintering and to the realization of uniform sintering.
Strain-mediated 180° switching in CoFeB and Terfenol-D nanodots with perpendicular magnetic anisotropy
Authors: Wang Qianchang , Li Xu , Liang Cheng-Yen , Barra Anthony , Domann John , Lynch Chris , Sepulveda Abdon , Carman Greg
Published: March 2017

A micromagnetic and elastodynamic finite element model is used to compare the 180° out-of-plane magnetic switching behavior of CoFeB and Terfenol-D nanodots with perpendicular magnetic easy axes. The systems simulated here consist of 50 nm diameter nanodots on top of a 100 nm-thick PZT (Pby[ZrxTi1-x]O3) thin film, which is attached to a Si substrate. This allows voltage pulses to induce strain-mediated magnetic switching in a magnetic field free environment. Coherent and incoherent switching behaviors are observed in both CoFeB and Terfenol nanodots, with incoherent flipping associated with larger or faster applied switching voltages. The energy to flip a Terfenol-D memory element is an ultralow 22 aJ, which is 3–4 orders more efficient than spin-transfer-torque. Consecutive switching is also demonstrated by applying sequential 2.8 V voltage pulses to a CoFeB nanodot system with switching times as low as 0.2 ns.
Macroparticle generation in DC arc discharge from a WC cathode
Authors: Zhirkov Igor , Polcik Peter , Kolozsvári Szilard , Rosen Johanna
Published: March 2017

We have studied macroparticle generation from a tungsten carbide cathode used in a dc vacuum arc discharge. Despite a relatively high decomposition/melting point (∼3100 K), there is an intensive generation of visible particles with sizes in the range 20–35 μm. Visual observations during the discharge and scanning electron microscopy of the cathode surface and of collected macroparticles indicate a new mechanism for particle formation and acceleration. Based on the W-C phase diagram, there is an intensive sublimation of carbon from the melt resulting from the cathode spot. The sublimation supports the formation of a sphere, which is accelerated upon an explosion initiated by Joule heating at the critical contact area between the sphere and the cathode body. The explosive nature of the particle acceleration is confirmed by surface features resembling the remains of a splash on the droplet surface.
Development of a correction method for the time-of-flight prompt gamma-ray analysis
Authors: Huang M. , Toh Y. , Ebihara M. , Kimura A. , Nakamura S.
Published: March 2017

A new analytical technique, time-of-flight prompt gamma-ray analysis, has been developed at the Japan Proton Accelerator Research Complex. In order to apply it to accurate elemental analysis, a set of Fe and Au reference samples were measured to examine the several factors which affect the number of detected events. It was found that major contributing factors included attenuations of neutrons and gamma rays in the sample, live-time fraction and signal pile-up correction. A simulation model was built for the estimation of neutron and gamma-ray attenuations. A simple empirical formula was proposed to calculate the signal pile-up correction factor. The whole correction method has proven to be accurate and reliable.
Thermal performance of Fe-Cr-Nb-B systems in magnetic hyperthermia
Authors: Astefanoaei Iordana , Chiriac Horia , Stancu Alexandru
Published: March 2017

In magnetic hyperthermia, the temperature control within the malignant tissues is an important step to increase the efficiency of the therapy. A temperature analysis is a good method to improve the heating process of the magnetic particles injected within tissues. This paper analyzes the thermal effects induced within malignant tissues by the magnetic systems like: magnetite and Fe-Cr-Nb-B when an external time-dependent magnetic field is applied. The heat generation by Néel and Brown relaxations was modeled using the thermal and magnetic properties of the Fe-Cr-Nb-B particles experimentally determined. A lognormal particle size distribution was considered for these magnetic systems with dimensions from 5 nm to 30 nm. After their injection at the center of the tumor, according to the solution of the transient convection-diffusion equation in a porous medium, the mass concentration of the particles within ferrofluid has a spatial and temporal distribution. The ferrofluid injection process was modeled using the Brinkman equations. The ferrofluid injection rate during the injection process influences significantly the spatial distribution of the particle concentration and temperature field within tumor. Higher values of the ferrofluid flow rate determine a strong convection of the particles to the tumor center. As a consequence, the temperature gradients within tumor are smaller. The performance in Magnetic Hyperthermia of Fe-Cr-Nb-B magnetic systems is discussed.
Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices with an AlAsSb/GaSb superlattice barrier
Authors: Haddadi A. , Chevallier R. , Dehzangi A. , Razeghi M.
Published: March 2017

Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices on GaSb substrate have been demonstrated. An AlAs0.10Sb0.90/GaSb H-structure superlattice design was used as the large-bandgap electron-barrier in these photodetectors. The photodetector is designed to have a 100% cut-off wavelength of ∼2.8 μm at 300 K. The photodetector exhibited a room-temperature (300 K) peak responsivity of 0.65 A/W at 1.9 μm, corresponding to a quantum efficiency of 41% at zero bias under front-side illumination, without any anti-reflection coating. With an R × A of 78 Ω·cm2 and a dark current density of 8 × 10−3 A/cm2 under −400 mV applied bias at 300 K, the nBn photodetector exhibited a specific detectivity of 1.51 × 1010 cm·Hz1/2/W. At 150 K, the photodetector exhibited a dark current density of 9.5 × 10−9 A/cm2 and a quantum efficiency of 50%, resulting in a detectivity of 1.12 × 1013 cm·Hz1/2/W.
Revealing the electronic structure of LiC6 by soft X-ray spectroscopy
Authors: Zhang L. , Li X. , Augustsson A. , Lee C. M. , Rubensson J.-E. , Nordgren J. , Ross P. N. , Guo J.-H.
Published: March 2017

The electronic structure of LiC6 has been investigated by soft X-ray absorption and emission spectroscopies. The results reveal that upon full lithiation of graphite, the Li 2s electrons are transferred into the carbon π* states in a near rigid-band behavior, resulting in the increased density of states near EF and the shift of σ* states to lower energies. In addition, the resonant inelastic X-ray scattering spectra of LiC6 do not show strong dispersive features as that of graphite, indicating that the crystal momentum is not conserved during the scattering process due to the delocalization of electrons in the intermediate state.
Combined foliar selenium and zinc biofortification in field pea (Pisum sativum): accumulation and bioavailability in raw and cooked grains
Authors: Poblaciones Maria J. , Rengel Zed
Published: March 2017

Millions of people have an inadequate intake of selenium (Se) and zinc (Zn), and foliar biofortification may minimise these problems. To evaluate the efficacy of combined foliar Se and Zn fertilisation in field pea (Pisum sativum L.) grains, foliar Se and Zn applications were tested individually and in all combinations (0, 0.03% or 0.06% (w/v) NaSeO4, and 0, 0.25% or 0.5% (w/v) ZnSO4.7H2O) at early grain filling. Plant growth was not influenced by any of the treatments. There was a positive relationship between total Se or Zn concentration in raw or cooked grains and respective Se or Zn application dose. Grain Zn accumulation was positively influenced by the combined application of Se and Zn. Grain cooking caused a slight decrease in grain Se (by 7.4%) and Zn concentrations (by 19%); however, cooking enhanced Zn bioavailability. The consumption of 100 g of cooked, biofortified field peas would provide ~50% of recommended daily intake of Zn and 45% of Se. The present study successfully biofortified field peas with Se and Zn, with the combined foliar application of Se and Zn being the best option.
Pastureland transfer as a livelihood adaptation strategy for herdsmen: a case study of Xilingol, Inner Mongolia
Authors: Zhang Meiyan , Zhang Lizhong , Zhang Yaoqi , Xu Yecheng , Chen Jiquan
Published: March 2017

The grassland is the most important resource for the herdsmen in Inner Mongolia, China. In the 1980s, pastureland was administratively allocated based on household size. The subsequent changes in socioeconomic and new household characteristics suggest that adjustment is needed for more efficient land use. This study reviewed the recent progress of the rental market and investigated the herdsmen’s behaviours regarding grassland market transactions in Xilingol League, Inner Mongolia. The economic assumption is that there exists a variation in values by household for each given parcel of land, which drives land transfer to users who can generate higher values. Each household is characterised by its initial pasture landholding, herding facilities and demographics. But the gain from the transfer must be deducted from the transaction costs, and cooperative membership can significantly reduce the transaction costs. An econometric model is developed and tested with data collected from household surveys in the Xilingol League. The results indicate that household size is the most significant variable for land transfer in the long run. Herdsmen have been dynamically adjusting herding equipment and pasture landholdings, allocating labour between herding and non-herding activities in response to these changes in society. Cooperative organisation was found to be significant in facilitating land transfer due to its role in reducing transaction costs. Higher quality land with higher rent is also found to be more likely to transfer since the percentage of the transaction cost is lower than lower quality land.
Incorporating fine-scale drought information into an eastern US wildfire hazard model
Authors: Peters Matthew P. , Iverson Louis R.
Published: March 2017

Wildfires in the eastern United States are generally caused by humans in locations where human development and natural vegetation intermingle, e.g. the wildland–urban interface (WUI). Knowing where wildfire hazards are elevated across the forested landscape may help land managers and property owners plan or allocate resources for potential wildfire threats. In an earlier paper, we presented a model showing monthly hazards of wildfire across Ohio, Pennsylvania and New Jersey at a 30-m resolution. Here, we refine the spatial resolution of drought conditions by incorporating a 4×4-km gridded self-calibrated drought index, include mean winter temperature to restrict hazards from being modelled into locations possibly covered by snow, and compare the performance of the updated models with the original ones. The area under the curve values for the updated models were within 10% of the values for the original models, but the refinement of drought conditions resulted in a less generalised probability of hazards, potentially increasing the applicability of these models. Among the 12 monthly models, the wildland–urban interface had the highest contribution followed by a weighed drought frequency index.
Magnetization dynamics and its scattering mechanism in thin CoFeB films with interfacial anisotropy
Authors: Okada Atsushi , He Shikun , Gu Bo , Kanai Shun , Soumyanarayanan Anjan , Lim Sze Ter , Tran Michael , Mori Michiyasu , Maekawa Sadamichi , Matsukura Fumihiro , Ohno Hideo , Panagopoulos Christos
Published: March 2017

Significance

Ferromagnetic resonance (FMR) is considered a standard tool in the study of magnetization dynamics, with an established analysis procedure. We show there is a missing piece of physics to consider to fully understand and precisely interpret FMR results. This physics manifests itself in the dynamics of magnetization and hence in FMR spectra of ferromagnets, where interfacial anisotropy is a fundamental term. Advances in ferromagnetic heterostructures enabled by developing cutting-edge technology now allow us to probe and reveal physics previously hidden in the bulk properties of ferromagnets.
Partner abundance controls mutualism stability and the pace of morphological change over geologic time
Authors: Chomicki Guillaume , Renner Susanne S.
Published: March 2017

Significance

Some epiphytes gain most of their nutrients from ants that nest in plant-provided cavities, accessible only through plant-formed entrance holes. We use a large clade of such epiphytes to study when mutualisms break down and how this affects the symbiont filtering system. Results support three theoretical predictions: (i) only generalist symbioses returned to a non–ant-associated state; (ii) evolutionary returns to an ant-free state occur where partners are rare, in our system at high altitudes; and (iii) the rate of hole-diameter evolution increases drastically after mutualism breakdown, suggesting release from stabilizing selection exerted by mutualistic ants. This highlights the importance of partner abundances in determining mutualistic strategy and explains the convergent evolution of ant/plant symbioses in ant-rich tropical lowlands.
Population Genomic Analysis of Brook Trout in Pennsylvania's Appalachian Region
Authors: Buonaccorsi V. P. , Malloy J. , Peterson M. , Brubaker K. , Grant C. J.
Published: March 2017

Informed conservation of stream fishes requires detailed understanding of the effects of both natural processes and anthropogenic activities on genetic diversity. Brook Trout Salvelinus fontinalis, a salmonid native to eastern North America, typically resides in cold, high‐quality stream ecosystems. The species has not only faced historical anthropogenic pressures, but also confronts current and future pressures. In a genetic analysis we used a reduced representation sequencing method (ddRADseq) to characterize 63 individuals from 23 streams where Brook Trout are native in the Appalachian region of Pennsylvania. A total of 2,590 loci passed filtering criteria, and 53% displayed significant association with a major stream drainage basin (Susquehanna or Allegheny; mean FST = 0.085). Mapping of the sequencing reads to the Atlantic Salmon Salmo salar genome revealed no clustering of high interdrainage FST values to specific genome regions. Evidence for genetic heterogeneity within each drainage basin was also detected. Stepwise regression of observed heterozygosity against geographic and environmental features revealed that drainage basin and effective area of watersheds were significant predictors of observed heterozygosity of Brook Trout within streams. Natural features such as waterfalls and major drainage basin, as well as the effects of dams and acid‐mine drainage have fragmented habitat and shaped genetic diversity within Brook Trout populations in the Appalachian region of Pennsylvania, overall indicating the vulnerability of this species to increased industrialization.

Received August 15, 2016; accepted January 17, 2017 Published online March 24, 2017
Glu–Phe from onion (Allium Cepa L.) attenuates lipogenesis in hepatocytes
Authors: Lee Yu Geon , Cho Jeong–Yong , Hwang Eom Ji , Jeon Tae–Il , Moon Jae–Hak
Published: March 2017

A Glu–Phe (EF) was isolated from onion (Allium cepa L. cv. Sunpower). The chemical structure of EF was determined by nuclear magnetic resonance and electrospray ionization–mass (ESI−MS) spectroscopy. We showed that EF reduced lipid accumulation in mouse hepatocytes by inhibiting the expression of sterol regulatory element-binding protein-1c (SREBP–1c) and its lipogenic target genes. We also found that AMP-activated protein kinase (AMPK) was required for the inhibitory effect of EF on lipid accumulation in mouse hepatocytes. Furthermore, EF was qualified in nine onion cultivars by selective multiple reaction-monitoring detection of liquid chromatography–ESI−MS. These results suggest that EF could contribute to the beneficial effect of onion supplement in maintaining hepatic lipid homeostasis.
Short-step syntheses of naturally occurring polyoxygenated aromatics based on site-selective transformation
Authors: Yamashita Yasunobu , Biard Alan , Hanaya Kengo , Shoji Mitsuru , Sugai Takeshi
Published: March 2017

Wogonin and astringin were synthesized from inexpensive chrysin and piceid in short steps. The key feature of these syntheses is site-selective transformation. The target molecules were obtained in 27 and 62% yields from the starting materials, respectively.
A Comparison of Red Snapper Reproductive Potential in the Northwestern Gulf of Mexico: Natural versus Artificial Habitats
Authors: Glenn Hilary D. , Cowan James H. , Powers Joseph E.
Published: March 2017

The majority of the research on adult Red Snapper Lutjanus campechanus in the Gulf of Mexico has been conducted at artificial habitats (in particular, low-relief artificial reefs off the coast of Alabama) and more recently on oil and gas platforms off the coast of Louisiana. However, previous studies indicate that there are differences in Red Snapper demographics and reproductive biology between habitats and regions within the Gulf. Despite the lack of study of natural reefs and banks in the Gulf, these areas are believed to be the historical centers of Red Snapper abundance. This study sampled Red Snapper from habitats that include reefs located more than 125 km offshore, making them difficult to reach for routine sampling. The results indicate significant differences in Red Snapper reproductive biology between females collected on adjacent artificial and natural habitats. Annual fecundity estimates were almost 20-fold higher in fish collected from natural habitats. Due to the high number of artificial habitats in the Gulf, these results suggest that accounting for metapopulation differences in reproductive potential is important in evaluating the status of this resource.
Children's daily activities: age variations between 8 and 12 years old across 16 countries
Authors: Rees Gwyther
Published: March 2017

This article uses information reported by over 54,000 children aged 8–12 years old about their daily activities in a diverse sample of 16 countries across four continents. It explores between-country similarities and differences in patterns of activities across this age range. The analysis focuses on four topics identified in previous research – involvement with housework, the emphasis on educational activities, the balance between active and sedentary leisure activities, and the balance between time spent with family and friends. The results suggest diverging age variations in children's activities across countries between the ages of 8 and 12 including tentative evidence of differences between low-income and high-income countries. They also highlight the need to understand children's daily activities within the specific context of individual countries.
Retail Intermediation and Local Foods
Authors: Richards Timothy J. , Hamilton Stephen F. , Gomez Miguel , Rabinovich Elliot
Published: March 2017

Direct sales of local foods, for instance through farmer's markets, have reached a plateau, while intermediated sales (through more traditional retailers) are still rising rapidly. We provide an explanation for the growth of intermediated local foods based on the observation that consumers prefer to buy local foods as part of a shopping basket that includes both local and non‐local items. We test our hypothesis using data from a natural experiment conducted by Relay Foods, an online retailer based in the U.S. state of Virginia, and a multi‐variate logit model of shopping‐basket demand. We find significant complementarities among items in a sample shopping basket that are not reflected in estimates from a discrete‐choice model of category demand. Estimates of a structural pricing‐and‐local‐content model reveal important incentives for retailers to offer local foods as part of a broader selection of grocery items.
Constructing linkage maps in the genomics era with MapDisto 2.0
Authors: Heffelfinger Christopher , Fragoso Christopher A , Lorieux Mathias
Published: March 2017

Motivation

Genotyping by sequencing (GBS) generates datasets that are challenging to handle by current genetic mapping software with graphical interface. Geneticists need new user-friendly computer programs that can analyze GBS data on desktop computers. This requires improvements in computation efficiency, both in terms of speed and use of random-access memory (RAM).

Results

MapDisto v.2.0 is a user-friendly computer program for construction of genetic linkage maps. It includes several new major features: (i) handling of very large genotyping datasets like the ones generated by GBS; (ii) direct importation and conversion of Variant Call Format (VCF) files; (iii) detection of linkage, i.e. construction of linkage groups in case of segregation distortion; (iv) data imputation on VCF files using a new approach, called LB-Impute. Features i to iv operate through inclusion of new Java modules that are used transparently by MapDisto; (v) QTL detection via a new R/qtl graphical interface.

Availability and Implementation

The program is available free of charge at mapdisto.free.fr.

Supplementary information

Supplementary data are available at Bioinformatics online.