bluuebunny/crossref_metadata_2025 huggingface dataset:
Method for operating mode identification of multi‐function radars based on predictive state representations
Authors: Ou Jian , Chen Yongguang , Zhao Feng , Liu Jin , Xiao Shunping
Published: September 2016

Operating mode identification of multi‐function radars (MFRs) is critical in radar threat evaluation and electronic jamming decisions. The hidden Markov model (HMM) in conventional methods relies on the MFR prior knowledge and cannot accurately describe the MFR signal sequence with regularity. An identifying method is presented that is based on predictive state representation (PSR) models without the help of prior information, which is unlikely to be obtained. Simulations of synthetic MFR signals are used to demonstrate the applicability of the novel method and to summarise the training parameter setting principles, which are of practical significance in applications of the method. The PSR‐based method is shown to be more effective than the HMM‐based methods, in particular when applied to the radar signal sequence with unknown regularity. The method also contains a novel approach to reducing the dimension of the system‐dynamics matrix, which enables the algorithm to perform well in conditions of heavy noise. Simulation results attest to the validity of the proposed method. With the proposed method, the operating modes of radars can be identified accurately, which is significant in supporting adaptive countermeasures against MFRs.
Trajectory estimation for ballistic missile in boost stage using robust filtering
Authors: Wang Xiaogang , Qin Wutao , Bai Yuliang , Cui Naigang
Published: September 2016

This study proposes a new estimation method, referred as the high‐degree cubature Huber‐based filtering (HCHF). The novel algorithm makes use of the fifth‐degree cubature rule to numerically compute Gaussian‐weighted integrals, which, with a set of non‐linear state equations, are used to compute weighted means and covariance required for measurement update. The measurement update is designed based on the Huber technique which is a combined minimum of l1 and l2 norm estimation. Therefore, the HCHF could exhibit robustness when the measurement noise is highly non‐Gaussian. The method is applied for tracking ballistic missile in presence of non‐Gaussian noise in satellite line‐of‐sight measurements. The tracking performance is compared with that of extended Kalman filtering and conventional cubature Kalman filtering. The simulation results verified the effectiveness of the proposed non‐linear filtering.
Clay bricks modified by implementing of N‐ and/or C‐TiO2: insight into self‐cleaning properties toward fatty contaminant
Authors: Janus Magdalena , Zatorska Justyna , Zając Kamila , Kusiak‐Nejman Ewelina , Czyżewski Adam , Morawski Antoni Waldemar
Published: September 2016

Clay bricks containing different kinds of titanium dioxide (TiO2) photocatalysts were obtained. The samples have shown high photocatalytic activity during thin layers of oleic acid deposited on their surface decomposition. The self‐cleaning effectiveness of the bricks was evaluated on the basis of the water contact angle measurements, or more precisely, wettability rate (WR) changes on the greasy surface layers. It appeared that despite the high‐temperature clay firing process (950°C), the presence of quartz and aluminosilicates in clay have caused the inhibition of anatase–rutile transformation. The highest photocatalytic efficiency, determined on the basis of the WR measurements, was observed for TiO2/nitrogen (N) and TiO2/N, carbon (C)‐loaded bricks. It should be noted that in the case of the bricks loaded with the TiO2/N,C photocatalyst, the carbon dopant present in the material was burnt out during the high‐temperature kiln firing. The N content in latter samples show closely the same results (∼0.03 and ∼0.04 wt% of N for brick loaded with TiO2/N and TiO2/N,C, respectively). In the context of the photocatalytic activity of studied materials, the N presence was found to be one of the most important feature.
Photon‐spin coherent manipulation of piezotronic nanodevice
Authors: Abdelrazek Ahmed Saeed , El‐banna Mohamed Mahmoud , Phillips Adel Helmy
Published: September 2016

The purpose of the present work is to investigate the spin dynamics of nanoscale junction formed of diluted ferromagnetic semiconductor as two leads and a curved semiconducting nanowire (NW). This NW is zinc oxide (ZnO) nanostructure, since it exhibits piezoelectric property. The spin transport characteristics of such junction is investigated by deducing the spin current for both parallel and antiparallel spin alignments using the effective mass method and Floquet theory. The effect of strain, generated due to bending the NW, on the spin current is investigated. Rashba spin‐orbit interaction, the influence of the photon energy of the induced ac‐field and magnetic field are considered. Numerical calculations show that the spin current, for both parallel and antiparallel spin alignments, varies with the induced strain strongly. This variation might be due to piezoelectric effect. Also, the strain gauge factor is calculated. Results for large gauges factor may find applications in different fields of nanotechnology. Results show that the spin transport characteristics are highly sensitive to strain mainly due to the shift in Fermi energy due to piezoelectric effect. Also, results show that the variation of Young's modulus of ZnO NW with strain and it might be monitored by giant magnetoresistance.
Estimation of the dimension of micropores and mesopores in single walled carbon nanotubes using the method Horvath–Kawazoe, Saito and Foley and BJH equations
Authors: Haghighatju Fateme , Hashemipour Rafsanjani Hassan , Esmaeilzadeh Feridun
Published: September 2016

The adsorption isotherm of the single walled carbon nanotubes (CNTs) is measured. The mathematical models for calculating pore size distribution (PSD) are modified. The PSD of sample is determined using Horvath–Kawazoe (KH), Saito and Foley (SF) and Barrett–Joyner–Halenda (BJH) methods. An average potential function has been determined inside the slit‐like and cylindrical pores. Since all of the regions of CNTs have same type that adsorbed nitrogen in the same conditions, the calculated PSDs from HK, SF and BJH models have same trend in both interior and exterior surfaces. By adding the adsorption term on outer surface, HK, SF and BJH models have been developed hence the pore volume increased.
Syngas production through methane oxy‐steam reforming over a Ni/SiO2 nanocatalyst prepared by a modified impregnation method
Authors: Hosseini Seyed Mohammad Sadegh , Hashemipour Hassan , Talebizadeh Alireza
Published: September 2016

Synthesis gas can be converted into a number of important energy carriers and fuels and it is playing a growing role in the energy sector. In this work oxy‐steam reforming of methane was performed over a modified 5%Ni/SiO2 catalyst in a fixed bed reactor at atmospheric pressure with the aim of producing syngas with high yield. The modified catalyst was synthesised by oleylamine‐assisted impregnation method and characterised by X‐ray diffraction, Fourier‐transformed infrared spectroscopy, N2 physisorption measurement, temperature‐programmed H2 reduction and transmission electron microscopy. For the comparative study, an unmodified 5%Ni/SiO2 catalyst was also prepared by conventional impregnation method. The reaction test results demonstrated that the value of methane conversion and the yield of syngas over the modified catalyst were almost 2 and 2.5 times more than ones over the unmodified catalyst. During the 10 h stability test, catalytic activity of the modified catalyst remained at high and constant values (92.5%) while the unmodified catalyst was rapidly deactivated during the stability test. The effective catalytic performance of the modified catalyst was related to the nanosize nickel species that interacted with the silica support strongly.
Fast-ion Dα spectrum diagnostic in the EAST
Authors: Hou Y. M. , Wu C. R. , Huang J. , Heidbrink W. W. , von Hellermann M. G. , Xu Z. , Jin Z. , Chang J. F. , Zhu Y. B. , Gao W. , Chen Y. J. , Lyu B. , Hu R. J. , Zhang P. F. , Zhang L. , Gao W. , Wu Z. W. , Yu Y. , Ye M. Y. ,   EAST Team
Published: September 2016

In toroidal magnetic fusion devices, fast-ion D-alpha diagnostic (FIDA) is a powerful method to study the fast-ion feature. The fast-ion characteristics can be inferred from the Doppler shifted spectrum of Dα light according to charge exchange recombination process between fast ions and probe beam. Since conceptual design presented in the last HTPD conference, significant progress has been made to apply FIDA systems on the Experimental Advanced Superconducting Tokamak (EAST). Both co-current and counter-current neutral beam injectors are available, and each can deliver 2-4 MW beam power with 50-80 keV beam energy. Presently, two sets of high throughput spectrometer systems have been installed on EAST, allowing to capture passing and trapped fast-ion characteristics simultaneously, using Kaiser HoloSpec transmission grating spectrometer and Bunkoukeiki FLP-200 volume phase holographic spectrometer coupled with Princeton Instruments ProEM 1024B eXcelon and Andor DU-888 iXon3 1024 CCD camera, respectively. This paper will present the details of the hardware descriptions and experimental spectrum.
Electron induced inelastic and ionization cross section for plasma modeling
Authors: Verma Pankaj , Mahato Dibyendu , Kaur Jaspreet , Antony Bobby
Published: September 2016

The present paper reports electron impact total inelastic and ionization cross section for silicon, germanium, and tin tetrahalides at energies varying from ionization threshold of the target to 5000 eV. These cross section data over a wide energy domain are very essential to understand the physico-chemical processes involved in various environments such as plasma modeling, semiconductor etching, atmospheric sciences, biological sciences, and radiation physics. However, the cross section data on the above mentioned molecules are scarce. In the present article, we report the computation of total inelastic cross section using spherical complex optical potential formalism and the estimation of ionization cross section through a semi-empirical method. The present ionization cross section result obtained for SiCl4 shows excellent agreement with previous measurements, while other molecules have not yet been investigated experimentally. Present results show more consistent behaviour than previous theoretical estimates. Besides cross sections, we have also studied the correlation of maximum ionization cross section with the square root of the ratio of polarizability to ionization potential for the molecules with known polarizabilities. A linear relation is observed between these quantities. This correlation is used to obtain approximate polarizability volumes for SiBr4, SiI4, GeCl4, GeBr4, and GeI4 molecules.
A physically constrained classical description of the homogeneous nucleation of ice in water
Authors: Koop Thomas , Murray Benjamin J.
Published: September 2016

Liquid water can persist in a supercooled state to below 238 K in the Earth’s atmosphere, a temperature range where homogeneous nucleation becomes increasingly probable. However, the rate of homogeneous ice nucleation in supercooled water is poorly constrained, in part, because supercooled water eludes experimental scrutiny in the region of the homogeneous nucleation regime where it can exist only fleetingly. Here we present a new parameterization of the rate of homogeneous ice nucleation based on classical nucleation theory. In our approach, we constrain the key terms in classical theory, i.e., the diffusion activation energy and the ice-liquid interfacial energy, with physically consistent parameterizations of the pertinent quantities. The diffusion activation energy is related to the translational self-diffusion coefficient of water for which we assess a range of descriptions and conclude that the most physically consistent fit is provided by a power law. The other key term is the interfacial energy between the ice embryo and supercooled water whose temperature dependence we constrain using the Turnbull correlation, which relates the interfacial energy to the difference in enthalpy between the solid and liquid phases. The only adjustable parameter in our model is the absolute value of the interfacial energy at one reference temperature. That value is determined by fitting this classical model to a selection of laboratory homogeneous ice nucleation data sets between 233.6 K and 238.5 K. On extrapolation to temperatures below 233 K, into a range not accessible to standard techniques, we predict that the homogeneous nucleation rate peaks between about 227 and 231 K at a maximum nucleation rate many orders of magnitude lower than previous parameterizations suggest. This extrapolation to temperatures below 233 K is consistent with the most recent measurement of the ice nucleation rate in micrometer-sized droplets at temperatures of 227–232 K on very short time scales using an X-ray laser technique. In summary, we present a new physically constrained parameterization for homogeneous ice nucleation which is consistent with the latest literature nucleation data and our physical understanding of the properties of supercooled water.
Two-color vibrational, femtosecond, fully resonant electronically enhanced CARS (FREE-CARS) of gas-phase nitric oxide
Authors: Stauffer Hans U. , Roy Sukesh , Schmidt Jacob B. , Wrzesinski Paul J. , Gord James R.
Published: September 2016

A resonantly enhanced, two-color, femtosecond time-resolved coherent anti-Stokes Raman scattering (CARS) approach is demonstrated and used to explore the nature of the frequency- and time-dependent signals produced by gas-phase nitric oxide (NO). Through careful selection of the input pulse wavelengths, this fully resonant electronically enhanced CARS (FREE-CARS) scheme allows rovibronic-state-resolved observation of time-dependent rovibrational wavepackets propagating on the vibrationally excited ground-state potential energy surface of this diatomic species. Despite the use of broadband, ultrafast time-resolved input pulses, high spectral resolution of gas-phase rovibronic transitions is observed in the FREE-CARS signal, dictated by the electronic dephasing timescales of these states. Analysis and computational simulation of the time-dependent spectra observed as a function of pump–Stokes and Stokes–probe delays provide insight into the rotationally resolved wavepacket motion observed on the excited-state and vibrationally excited ground-state potential energy surfaces of NO, respectively.
Molybdenum disulfide catalyzed tungsten oxide for on-chip acetone sensing
Authors: Li Hong , Ahn Sung Hoon , Park Sangwook , Cai Lili , Zhao Jiheng , He Jiajun , Zhou Minjie , Park Joonsuk , Zheng Xiaolin
Published: September 2016

Acetone sensing is critical for acetone leak detection and holds a great promise for the noninvasive diagnosis of diabetes. It is thus highly desirable to develop a wearable acetone sensor that has low cost, miniature size, sub-ppm detection limit, great selectivity, as well as low operating temperature. In this work, we demonstrate a cost-effective on-chip acetone sensor with excellent sensing performances at 200 °C using molybdenum disulfide (MoS2) catalyzed tungsten oxide (WO3). The WO3 based acetone sensors are first optimized via combined mesoscopic nanostructuring and silicon doping. Under the same testing conditions, our optimized mesoporous silicon doped WO3 [Si:WO3(meso)] sensor shows 2.5 times better sensitivity with ∼1000 times smaller active device area than the state-of-art WO3 based acetone sensor. Next, MoS2 is introduced to catalyze the acetone sensing reactions for Si:WO3(meso), which reduces the operating temperature by 100 °C while retaining its high sensing performances. Our miniaturized acetone sensor may serve as a wearable acetone detector for noninvasive diabetes monitoring or acetone leakage detection. Moreover, our work demonstrates that MoS2 can be a promising nonprecious catalyst for catalytic sensing applications.
Ionization at a solid-water interface in an applied electric field: Charge regulation
Authors: Okamoto Ryuichi , Onuki Akira
Published: September 2016

We investigate ionization at a solid-water interface in an applied electric field. We attach an electrode to a dielectric film bearing silanol or carboxyl groups with an areal density Γ0, where the degree of dissociation α is determined by the proton density in water close to the film. We show how α depends on the density n0 of NaOH in water and the surface charge density σm on the electrode. For σm > 0, the protons are expelled away from the film, leading to an increase in α. In particular, in the range 0 < σm < eΓ0, self-regulation occurs to realize α ≅ σm/eΓ0 for n0 ≪ nc, where nc is 0.01 mol/L for silica surfaces and is 2 × 10−5 mol/L for carboxyl-bearing surfaces. We also examine the charge regulation with decreasing the cell thickness H below the Debye length κ−1, where a crossover occurs at the Gouy-Chapman length. In particular, when σm ∼ eΓ0 and H ≪ κ−1, the surface charges remain only partially screened by ions, leading to a nonvanishing electric field in the interior.
Recombination activity of light-activated copper defects in p-type silicon studied by injection- and temperature-dependent lifetime spectroscopy
Authors: Inglese Alessandro , Lindroos Jeanette , Vahlman Henri , Savin Hele
Published: September 2016

The presence of copper contamination is known to cause strong light-induced degradation (Cu-LID) in silicon. In this paper, we parametrize the recombination activity of light-activated copper defects in terms of Shockley—Read—Hall recombination statistics through injection- and temperature dependent lifetime spectroscopy (TDLS) performed on deliberately contaminated float zone silicon wafers. We obtain an accurate fit of the experimental data via two non-interacting energy levels, i.e., a deep recombination center featuring an energy level at Ec−Et=0.48−0.62 eV with a moderate donor-like capture asymmetry (k=1.7−2.6)  and an additional shallow energy state located at Ec−Et=0.1−0.2 eV, which mostly affects the carrier lifetime only at high-injection conditions. Besides confirming these defect parameters, TDLS measurements also indicate a power-law temperature dependence of the capture cross sections associated with the deep energy state. Eventually, we compare these results with the available literature data, and we find that the formation of copper precipitates is the probable root cause behind Cu-LID.
Exciton formation assisted by longitudinal optical phonons in monolayer transition metal dichalcogenides
Authors: Thilagam A.
Published: September 2016

We examine a mechanism by which excitons are generated via the longitudinal optical (LO) phonon-assisted scattering process after optical excitation of monolayer transition metal dichalcogenides. The exciton formation time is computed as a function of the exciton center-of-mass wavevector, electron and hole temperatures, and carrier densities for known values of the Fröhlich coupling constant, LO phonon energy, lattice temperature, and the exciton binding energy in layered structures. For the monolayer MoS2, we obtain ultrafast exciton formation times on the sub-picosecond time scale at charge densities of 5 × 1011 cm–2 and carrier temperatures less than 300 K, in good agreement with recent experimental findings (≈0.3 ps). While excitons are dominantly created at zero center-of-mass wavevectors at low charge carrier temperatures (≈30 K), the exciton formation time is most rapid at non-zero wavevectors at higher temperatures (≥120 K) of charge carriers. The results show the inverse square-law dependence of the exciton formation times on the carrier density, consistent with a square-law dependence of photoluminescence on the excitation density. Our results show that excitons are formed more rapidly in exemplary monolayer selenide-based dichalcogenides (MoSe2 and WSe2) than sulphide-based dichalcogenides (MoS2 and WS2).
Measurement of deuterium density profiles in the H-mode steep gradient region using charge exchange recombination spectroscopy on DIII-D
Authors: Haskey S. R. , Grierson B. A. , Burrell K. H. , Chrystal C. , Groebner R. J. , Kaplan D. H. , Pablant N. A. , Stagner L.
Published: September 2016

Recent completion of a thirty two channel main-ion (deuterium) charge exchange recombination spectroscopy (CER) diagnostic on the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] enables detailed comparisons between impurity and main-ion temperature, density, and toroidal rotation. In a H-mode DIII-D discharge, these new measurement capabilities are used to provide the deuterium density profile, demonstrate the importance of profile alignment between Thomson scattering and CER diagnostics, and aid in determining the electron temperature at the separatrix. Sixteen sightlines cover the core of the plasma and another sixteen are densely packed towards the plasma edge, providing high resolution measurements across the pedestal and steep gradient region in H-mode plasmas. Extracting useful physical quantities such as deuterium density is challenging due to multiple photoemission processes. These challenges are overcome using a detailed fitting model and by forward modeling the photoemission using the FIDASIM code, which implements a comprehensive collisional radiative model.
Alignment and absolute wavelength calibration of imaging Bragg spectrometers
Authors: Bertschinger G. , Marchuk O. , Barnsley R.
Published: September 2016

In the present and the next generation of fusion devices, imaging Bragg spectrometers are key diagnostics to measure plasma parameters in the hot core, especially ion temperature and plasma rotation. The latter quantities are routinely obtained using the Doppler-width and -shift of the emitted spectral lines, respectively. Line shift measurements require absolute accuracies Δλ/λ of about 10 ppm, where λ-is the observed wavelength. For ITER and the present fusion devices, spectral lines of He-and H-like argon, iron, and krypton as well as Ne-like tungsten are foreseen for the measurements. For these lines, Kα lines can be found, some in higher order, which fit into the narrow energy window of the spectrometers. For arbitrary wavelength settings, Kα lines are also used to measure the miscut of the spherical crystals; afterwards the spectrometers can be set according to the geometrical imaging properties using coordinate measurement machines. For the spectrometers measuring Lyα lines of H-like ions, fluorescence targets can provide in situ localized calibration lines on the spectra. The fluorescence targets are used best in transmission and are excited by the thermal x-ray radiation of the plasma. An analytic theory of fluorescence is worked out.
Existence of multi-bump solutions for the fractional Schrödinger-Poisson system
Authors: Liu Weiming
Published: September 2016

This paper considers the fractional Schrödinger-Poisson system in ℝ3. We prove that the problem has m-bump solutions under some given conditions which are given in the Introduction. Moreover, the system has more and more multi-bump solutions as ϵ → 0.
Molecular beam epitaxy growth of monolayer niobium diselenide flakes
Authors: Hotta Takato , Tokuda Takuto , Zhao Sihan , Watanabe Kenji , Taniguchi Takashi , Shinohara Hisanori , Kitaura Ryo
Published: September 2016

Monolayer niobium diselenide (NbSe2) is prepared through molecular beam epitaxy with hexagonal boron nitride (hBN) as substrates. Atomic force microscopy and the Raman spectroscopy have shown that the monolayer NbSe2 grown on the hBN possesses triangular or truncated triangular shape whose lateral size amounts up to several hundreds of nanometers. We have found that the precisely controlled supply rate and ultraflat surface of hBN plays an important role in the growth of the monolayer NbSe2.
Nanoscale plasmonic coupler with tunable direction and intensity ratio controlled by optical vortex
Authors: Liu Ting , Wang Shouyu
Published: September 2016

Plasmonic couplers with tunable direction and intensity ratio controlled by exciting optical vortex are proposed in this paper. The nanoscale structure is rather simple only composed of two thin parallel slits. By modulating topological charges and sizes of the exciting optical vortex, different coupling directions and various directional coupling ratios can be obtained with fixed structure. The proposed plasmonic structure is not only a controllable plasmonic coupler but also a topological charge detector which can determine the direction of phase twisting in a wide range. It is believed that the extremely compact structure can be potentially used in future logic photonic and plasmonic systems.
Signal asymmetries in the anomalous Hall effect of bilayer magnetic nanostructures
Authors: Griffiths R. A. , Nutter P. W. , Neumann A. , Thönnißen C. , Wilhelm E.-S. , Thomson T.
Published: September 2016

We propose an interpretation for the signal asymmetry observed in anomalous Hall effect (AHE) transport measurements of magnetic nanostructures patterned from bilayer magnetic thin films. Experimental data and simulations demonstrate that the signal asymmetry observed in hysteresis loops arises due to a combination of the anomalous Hall effect together with a contribution from longitudinal giant magnetoresistance (GMR). The effect shows a high-sensitivity to nanoscale misalignments in Hall cross geometry. Consequently, the complex nature of the origin of electrical signals should be taken into account when undertaking any transport measurements on magnetic bilayer nanostructures, such as GMR or spintronic devices.
Field-free spin Hall effect driven magnetization switching in Pd/Co/IrMn exchange coupling system
Authors: Kong W. J. , Ji Y. R. , Zhang X. , Wu H. , Zhang Q. T. , Yuan Z. H. , Wan C. H. , Han X. F. , Yu T. , Fukuda Kenji , Naganuma Hiroshi , Tung Mean-Jue
Published: September 2016

All electrical manipulation of magnetization is crucial and of great important for spintronics devices for the sake of high speed, reliable operation, and low power consumption. Recently, widespread interests have been aroused to manipulate perpendicular magnetization of a ferromagnetic layer using spin-orbit torque (SOT) without field. We report that a commonly used antiferromagnetic material IrMn can be a promising candidate as a functional layer to realize field-free magnetization switching driven by SOT in which IrMn is employed to act as both the source of effective exchange bias field and SOT source. The critical switching current density within our study is Jc = 2.2 × 107 A/cm2, which is the same magnitude as similar materials such as PtMn. A series of measurements based on anomalous Hall effect was systematically implemented to determine the magnetization switching mechanism. This study offers a possible route for IrMn application in similar structures.
Study of the time-resolved, 3-dimensional current density distribution in solid metallic liners at 1 MA
Authors: Bott-Suzuki S. C. , Cordaro S. W. , Caballero Bendixsen L. S. , Atoyan L. , Byvank T. , Potter W. , Kusse B. R. , Greenly J. B. , Hammer D. A.
Published: September 2016

We present a study of the time varying current density distribution in solid metallic liner experiments at the 1 MA level. Measurements are taken using an array of magnetic field probes which provide 2D triangulation of the average centroid of the drive current in the load at 3 discrete axial positions. These data are correlated with gated optical self-emission imaging which directly images the breakdown and plasma formation region. Results show that the current density is azimuthally non-uniform and changes significantly throughout the 100 ns experimental timescale. Magnetic field probes show clearly motion of the current density around the liner azimuth over 10 ns timescales. If breakdown is initiated at one azimuthal location, the current density remains non-uniform even over large spatial extents throughout the current drive. The evolution timescales are suggestive of a resistive diffusion process or uneven current distributions among simultaneously formed but discrete plasma conduction paths.
Reduction of neoclassical polarization current contribution to NTM evolution
Authors: Qu Hongpeng , Peng Xiaodong , Wang Feng , Wang Aike , Shen Yong
Published: September 2016

The neoclassical polarization current, which can be generated by a time-dependent electric field resulting from magnetic island rotation, is believed to play an important role in the initial stage of the neoclassical tearing mode (NTM) evolution in tokamak plasmas. In the previous analytical description of the neoclassical polarization current contribution to the evolution of NTMs in the limit of low collision frequency (νii≪εω, νii is ion collision frequency, ε is the inverse aspect ratio, and ω is the island propagation frequency in the plasma rest frame), the width of magnetic islands has been assumed to be much larger than the finite-banana-width (FBW) of the trapped ions in order to solve the drift-kinetic equation of ions by using the perturbation method. In this paper, we introduce a new analytical approach to investigate the neoclassical polarization current contribution to the NTM evolution without the assumption of the large island width by solving the drift-kinetic equation in a so-called ion-banana-center coordinate system. The results show that, when the island width is comparable to the FBW of the thermal ion, the neoclassical polarization current term in the equation of the NTM evolution is much smaller than the previous analytical expression but matches well with the empirical anticipation commonly adopted in experiments.
Ultrathin MoS2 and WS2 layers on silver nano-tips as electron emitters
Authors: Loh Tamie A. J. , Tanemura Masaki , Chua Daniel H. C.
Published: September 2016

2-dimensional (2D) inorganic analogues of graphene such as MoS2 and WS2 present interesting opportunities for field emission technology due to their high aspect ratio and good electrical conductivity. However, research on 2D MoS2 and WS2 as potential field emitters remains largely undeveloped compared to graphene. Herein, we present an approach to directly fabricate ultrathin MoS2 and WS2 onto Ag nano-tips using pulsed laser deposition at low temperatures of 450–500 °C. In addition to providing a layer of chemical and mechanical protection for the Ag nano-tips, the growth of ultrathin MoS2 and WS2 layers on Ag led to enhanced emission properties over that of pristine nano-tips due to a reduction of the effective barrier height arising from charge injection from Ag to the overlying MoS2 or WS2. For WS2 on Ag nano-tips, the phasic mixture was also an important factor influencing the field emission performance. The presence of 1T-WS2 at the metal-WS2 interface in a hybrid film of 2H/1T-WS2 leads to improvement in the field emission capabilities as compared to pure 2H-WS2 on Ag nano-tips.
Giant cross-polarization conversion of terahertz radiation by plasmons in an active graphene metasurface
Authors: Polischuk O. V. , Melnikova V. S. , Popov V. V.
Published: September 2016

Results of theoretical investigation of the cross-polarization conversion of terahertz (THz) radiation by the graphene metasurface formed by a periodic array of graphene nanoribbons located at the surface of a high-refractive-index dielectric substrate are presented. Giant polarization conversion at the plasmon resonance frequencies takes place without applying external DC magnetic field. Pumping graphene by its direct optical illumination or diffusion pumping allows for compensating the Drude losses in graphene and leads to further enhancement of the polarization conversion. It is shown that the total polarization conversion can be achieved in the total internal reflection regime of THz wave from the graphene metasurface at room temperature.
Sub-5 μm-thick spalled single crystal Si foils by decoupling crack initiation and propagation
Authors: Lee Yong Hwan , Kim Yong-Jae , Han Seung Min Jane , Song Hee-eun , Oh Jihun
Published: September 2016

Spalling of a brittle semiconductor substrate is an attractive method for fabricating sub-50 μm thick single crystal semiconductor wafers in large area. Here, a spalling process to fabricate single crystal Si foils with controlled thicknesses ranging from sub-5 to 38 μm is demonstrated using electroplated Ni stressor layers on Si substrates. In this study, the thickness profile of the Ni stressor layer was varied by changing the Ni electroplating current density, and the effect of thickness variation on the crack initiation and propagation in the underlying Si substrate was evaluated. The critical Ni thickness for crack initiation in our Ni/Si bilayer system was determined and we also show that the crack propagation depth, i.e., spalled Si thickness, is proportional to the thickness of the Ni layer at the central area of the Si wafer. Ni layer plated using 40 mA/cm2 resulted in sub-5 μm thick Si foil. In addition, the spalling mechanics of a Ni/Si bilayer system was analytically explored to give insight into the requirements of the Ni stressor layer for crack initiation.
Molecular spin on surface: From strong correlation to dispersion interactions
Authors: Zhang Yachao
Published: September 2016

A reliable prediction of magnetic properties of surface-supported molecules containing 3d/4f spin carriers has challenged the electronic structure theory for decades. Here we tackle this problem with Hubbard-U corrected van der Waals density functional (vdW-DF), incorporating strong correlation effects of the localized electrons and dispersion interactions involved in the molecule-surface binding. By fitting the spin state energetics of a series of Fe(ii) compounds with varying ligand field strength, we find that the optimal U value for vdW-DF is much smaller than that for the local density approximation (LDA) while quite similar to that for the generalized gradient approximation (GGA). We show that although vdW-DF+U overestimates largely the metal-ligand bond distance, the predicted adiabatic high-spin-low-spin energy splitting ΔEHL is only slightly changed with respect to that obtained using the LDA+U geometries consistent with experiment. Then we use Cu(111)-supported metallocene (M(C5H5)2, M = Fe, and Co) as a prototype example to explore the effects of the molecule-surface interactions. We show that the non-local dispersion interactions, poorly described by LDA and GGA while reasonably captured by vdW-DF, are critical for reproducing ΔEHL at large molecule-surface distances. Besides, we find that ΔEHL is decreased by the molecule-metal contact, which is shown to weaken the local ligand field around the magnetic center.
Note: An in situ method for measuring the non-linear response of a Fabry-Perot cavity
Authors: Bu Wenhao , Liu Mengke , Xie Dizhou , Yan Bo
Published: September 2016

The transfer cavity is a very important frequency reference for laser stabilization and is widely used for applications such as precision measurements and laser cooling of ions or molecules. But the non-linear response of the piezoelectric ceramic transducer (PZT) in the Fabry-Perot cavity limits the performance of the laser stabilization. Thus, measuring and controlling such non-linearity is essential. Here we report an in situ, optical method to characterize this non-linearity by measuring the resonant signals of a dual-frequency laser. The differential measurement makes it insensitive to the laser and cavity drifts, while maintaining a very high sensitivity. It can be applied for various applications with PZTs, especially in an optical lab.
Platinum nanoclusters in silica: Photoluminescent properties and their application for enhancing the emission of silicon nanocrystals in an integrated configuration
Authors: Bornacelli J. , Silva-Pereyra H. G. , Rodríguez-Fernández L. , Avalos-Borja M. , Oliver A.
Published: September 2016

We studied photoluminescence of ion implanted platinum nanoclusters embedded in silica. Pt ions were implanted at 2 MeV and the Pt nanoclusters were then nucleated by thermal treatment under either argon, air, or a reducing atmosphere of hydrogen and nitrogen. The nanoclusters showed broad photoluminescence spectra (400 to 600 nm) with a maximum intensity at 530 nm. The photoluminescence intensity of the Pt nanoclusters was sensitive to the ion fluence used during the ion implantation, and luminescence quenching was observed in samples fabricated at high Pt-ion fluence. A hybrid system composed of silicon nanocrystals and platinum nanoclusters embedded in a silica matrix was also made. The photoluminescence of the hybrid system spanned the entire visible spectrum, and emission from the silicon nanocrystals was enhanced.
Six dimensional X-ray Tensor Tomography with a compact laboratory setup
Authors: Sharma Y. , Wieczorek M. , Schaff F. , Seyyedi S. , Prade F. , Pfeiffer F. , Lasser T.
Published: September 2016

Attenuation based X-ray micro computed tomography (XCT) provides three-dimensional images with micrometer resolution. However, there is a trade-off between the smallest size of the structures that can be resolved and the measurable sample size. In this letter, we present an imaging method using a compact laboratory setup that reveals information about micrometer-sized structures within samples that are several orders of magnitudes larger. We combine the anisotropic dark-field signal obtained in a grating interferometer and advanced tomographic reconstruction methods to reconstruct a six dimensional scattering tensor at every spatial location in three dimensions. The scattering tensor, thus obtained, encodes information about the orientation of micron-sized structures such as fibres in composite materials or dentinal tubules in human teeth. The sparse acquisition schemes presented in this letter enable the measurement of the full scattering tensor at every spatial location and can be easily incorporated in a practical, commercially feasible laboratory setup using conventional X-ray tubes, thus allowing for widespread industrial applications.
Two-dimensional semiconductors: The case of silver thiolates
Authors: Massote Daniel V. P. , Mazzoni Mario S. C.
Published: September 2016

In this work, we apply first-principles calculations to investigate the electronic and structural properties of a layered compound based on the hexagonal arrangement of silver and sulfur atoms, a material that has been already synthesized and crystallographically characterized. We focus on the mono- and multilayer structures derived from the bulk material, showing that they hold great promise in applications related to nanotechnology. In particular, their direct band gaps may be greatly modulated by external fields as a result of a Stark effect, and a semiconductor-metal transition is predicted to take place for field magnitudes significantly smaller than those required to produce the same phenomenology in other nanostructures.
A reduced-order representation of the Schrödinger equation
Authors: Cheng Ming-C.
Published: September 2016

A reduced-order-based representation of the Schrödinger equation is investigated for electron wave functions in semiconductor nanostructures. In this representation, the Schrödinger equation is projected onto an eigenspace described by a small number of basis functions that are generated from the proper orthogonal decomposition (POD). The approach substantially reduces the numerical degrees of freedom (DOF’s) needed to numerically solve the Schrödinger equation for the wave functions and eigenstate energies in a quantum structure and offers an accurate solution as detailed as the direct numerical simulation of the Schrödinger equation. To develop such an approach, numerical data accounting for parametric variations of the system are used to perform decomposition in order to generate the POD eigenvalues and eigenvectors for the system. This approach is applied to develop POD models for single and multiple quantum well structure. Errors resulting from the approach are examined in detail associated with the selected numerical DOF’s of the POD model and quality of data used for generation of the POD eigenvalues and basis functions. This study investigates the fundamental concepts of the POD approach to the Schrödinger equation and paves a way toward developing an efficient modeling methodology for large-scale multi-block simulation of quantum nanostructures.
Proximate composition, cholesterol concentration and lipid oxidation of meat from chickens fed dietary spice addition (Allium sativum, Piper nigrum, Capsicum annuum)
Authors: Puvača N. , Kostadinović Lj. , Popović S. , Lević J. , Ljubojević D. , Tufarelli V. , Jovanović R. , Tasić T. , Ikonić P. , Lukač D.
Published: September 2016

The effects of supplementing spices, including garlic, black pepper and hot red pepper, in broiler chicken diet on proximate composition, cholesterol content and lipid oxidation of breast and thigh with drumstick meat, skin and liver were investigated. Meat proximate composition included measurements of moisture, protein, fat and ash content. Cholesterol content of tissue homogenates was performed by high-performance liquid chromatography–DAD analyses, while lipid oxidation of white and red meat, as well as liver, was expressed as a concentration of thiobarbituric acid reactive substances (TBARS) (mg malondialdehyde (MDA)/kg tissue). For biological research, eight treatments with a total of 1200 broiler chickens of hybrid line Hubbard were formed, with four replicates. In the control treatment, the chickens were fed with commercial mixtures of standard composition and quality based on corn flour and soybean meal. Experimental treatments were fed with the same commercial mixtures, except with addition of spices. At the end of the experiment and on the basis of gained results, it can be concluded that the chickens in experimental treatments with hot red pepper achieved statistically significantly (P < 0.05) higher final body masses (2460.6 and 2442.4 g) than did the chickens in the control and other treatments. Black pepper showed a positive and significant (P < 0.05) influence on improving the protein content in breast meat (24 g/100 g), hot red pepper lowered the cholesterol concentrations in meat (24.7 g/100 g in red meat), skin (87.4 g/100 g) and liver (263.1 g/100 g), while black pepper significantly (P < 0.05) reduced lipid oxidation in breast (0.05 mg MDA/kg tissue) and thigh with drumstick (0.12 mg MDA/kg tissue). On the basis of obtained findings, it can be concluded that the dietary spice herbs had a positive influence on a proximate composition of chicken meat, cholesterol concentrations and lipid oxidation process.
Effects of dietary vitamin B6 on the skeletal muscle protein metabolism of growing rabbits
Authors: Liu G. Y. , Wu Z. Y. , Zhu Y. L. , Liu L. , Li F. C.
Published: September 2016

This study aimed to evaluate the effects of dietary vitamin B6 on the skeletal muscle protein metabolism and expression of transcription and growth factor of growing rabbits. Two hundred, healthy, rabbits with similar bodyweights were randomly assigned to one of five dietary groups with 40 animals per group. The dietary groups consisted of the following different vitamin B6 supplementation levels: 0, 5, 10, 20 and 40 mg/kg. The feeding trial lasted 60 days. The results showed that dietary vitamin B6 elicited significant effects on the fore and hind leg muscle ratio (the fore and hind leg muscle weight/the liveweight; P < 0.05) and on serum total amino acids (T-AA), blood urea and insulin-like growth factor 1 (IGF1) content (P < 0.05). Additionally, expression of IGF1, myogenic determination factor (MYOD) and myogenin (MYOG), myocyte regulation factor 5 (MYF5), myostatin (MSTN) and WW domain-containing E3 proteasome ubiquitin ligase 1 (WWP1) mRNA in the loin (M. longissimus dorsi) were affected by vitamin B6 in diets (P < 0.05). The immunoblot analysis revealed that dietary vitamin B6 elicited significant effects on IGF1, MYOG and WWP1 expression in the loin (P < 0.05). Our results indicate that the addition of dietary vitamin B6 can significantly alter the protein metabolism of growing rabbits and that an appropriate vitamin B6 supplementation level is 20 mg/kg for 3–5-month-old growing rabbits (the basic diet vitamin B6 content was 4.51 mg/kg).
Leaf decomposition of cork oak under three different land uses within a montado of southern Portugal
Authors: Arosa Maria Luísa , Costa Sofia R. , Freitas Helena
Published: September 2016

This study compared litter decomposition dynamics of cork oak at three sites under different land-uses (grassland, shrubland and woodland), in a montado ecosystem in Southern Portugal. The montado is a protected habitat within the EU Habitats Directive, but the long-term persistence of cork oak is endangered in these ecosystems, with health of poor cork oak and low natural regeneration rates being the main causes of degradation. Moreover, human management has resulted in the conversion of woodlands to grasslands and may have long-term effects on soil nutrient availability, eventually modifying soil nutrient budgets. Knowledge of the ecological processes is therefore relevant for ecosystem management and species conservation. In the study, the estimated amount of leaf fall from cork oak showed no significant differences between land uses, despite the positive influence of tree crown size on leaf fall. Decomposition was affected by season, vegetation cover, leaf thickness and litter quality. Differences in land use that exposed soil to harsh climate conditions negatively affected soil microbial dynamics, resulting in lower decomposition rates in the more disturbed sites with lower canopy cover.
A two-year field assessment on the effect of slow release of nitrogenous fertiliser on N2O emissions from a wheat cropping system
Authors: Bordoloi Nirmali , Baruah K. K.
Published: September 2016

Nitrous oxide (N2O) is considered a major contributor to global climate change in addition to carbon dioxide and methane. A significant quantity of N2O emission originates from agriculture, largely from high rates of fertiliser application. We studied N2O emissions from wheat field to evaluate the effect of different forms of fertilisers and the potential for emission reduction. Field experiments were conducted for two consecutive seasons with four fertilisers, namely inorganic fertiliser (NPK), starch-coated urea (SCU), neem-coated urea (NCU), and urea alone (UA) in a tropical wheat ecosystem. Gas samples were collected from the field at weekly intervals using the static chamber technique and analysed with a gas chromatograph. The cumulative N2O emissions were higher from the NPK amended field (3.19kgN2O-Nha–1) followed by UA (3.05kg N2O-N ha–1). The SCU, NCU, and UA amendments decreased the total N2O emissions by 23%, 12%, and 4%, respectively (P<0.05) over the application of NPK. The results indicate a good correlation of N2O emissions with soil organic carbon, soil NO3–-N, NH4+-N, leaf area, and plant biomass. The application of SCU resulted in higher grain productivity and was the most effective substitute for conventional fertiliser in terms of reducing N2O emissions from a tropical wheat ecosystem.
Change in modal meanings
Authors: Hilpert Martin
Published: September 2016

This paper discusses how modal auxiliaries fit into a constructional view of language and how this view allows us to think in new ways about diachronic meaning change in modal auxiliaries. These issues will be illustrated on the basis of a diachronic corpus-based study of the modal auxiliary may, specifically focusing on changes in its collocational preferences during the past 200 years. The main point of this paper is the claim that a constructional view needs to take account of the mutual associations between modal auxiliaries and the lexical elements with which they occur. Changes in these mutual associations are usefully understood as change in a complex network of constructions.