bluuebunny/crossref_metadata_2025 huggingface dataset:
Manganese
Authors: Chakraborty Sudipta , Martinez-Finley Ebany , Caito Sam , Chen Pan , Aschner Michael
Published: July 2014

Manganese (Mn) is an essential metal that is responsible for several physiological functions, including proper immune function, bone growth, digestion, reproduction, energy metabolism and antioxidant defences. However, excessive exposure to this metal can result in an irreversible condition known as “manganism”, a disease that primarily results in Parkinsonian-like symptomatology. Although the mechanisms by which Mn is absorbed into the digestive tract are not completely clear, a number of uptake mechanisms have been identified on the surface of enterocytes. These include import of Mn2+ via the divalent metal transporter 1 (DMT1) and uptake of Mn3+ via complexation with the protein transferrin (Tf). Upon entering the blood, Mn is distributed diffusely throughout the body, with the brain, bone, kidneys and liver acquiring the highest accumulation. A variety of transporters regulate Mn import, including DMT1 or Tf-Tf receptor internalization, choline transporter, citrate transporter, voltage-gated and store-operated calcium channels, and the zinc transporters ZIP8/14. Recent findings suggest a role for the magnesium transporter HIP14 and the P-type transmembrane ATPase ATP13A2 in Mn uptake across cellular membranes. Mn serves as an important cofactor for many enzymes that are key in regulating general cellular function. Intracellular buffering mechanisms also include preferential sequestration within mitochondria. Finally, Mn export has yet to be fully understood, but new evidence points to the iron exporter ferroportin as a potential exporter. This chapter will address the various processes associated with maintenance of optimal Mn levels and the consequences of improper Mn homeostasis.
Development of ssDNA aptamers for the capture and detection of Salmonella typhimurium
Authors: Moon Jihea , Kim Giyoung , Park Saetbyeol
Published: July 2014

There is a global need for methods allowing rapid detection of pathogens in food samples, particularly for methods amenable for use in biosensors.
Simultaneous determination of niclosamide and its degradates in water by LC-MS/MS
Authors: Doran Gregory , Stevens Mark M.
Published: July 2014

A new method for the analysis of niclosamide (NIC) and its primary degradates 2-chloro-4-nitroaniline (2C4NA), aminoniclosamide (AN), hydroxyniclosamide (HN) and 5-chlorosalicylic acid (5CSA) in environmental water samples was developed using direct injection LC-MS/MS.
Organometallic macromolecules with piano stool coordination repeating units: chain configuration and stimulated solution behaviour
Authors: Cao Kai , Ward Jonathan , Amos Ryan C. , Jeong Moon Gon , Kim Kyoung Taek , Gauthier Mario , Foucher Daniel , Wang Xiaosong
Published: July 2014

PFpP with piano stool coordination repeating units (Fe-acyl complex) adopts linear chain configuration with a P–Fe–C backbone surrounded by aromatic groups, exhibiting stimulated solution behaviour in DMSO.
Ammonium betaines: efficient ionic nucleophilic catalysts for the ring-opening polymerization of l-lactide and cyclic carbonates
Authors: Guillerm Brieuc , Lemaur Vincent , Cornil Jérôme , Lazzaroni Roberto , Dubois Philippe , Coulembier Olivier
Published: July 2014

Ammonium betaines: the missing piece between hydrogen-bonding and nucleophilic-based ROP catalysts.
Tuning of surface wettability of RGO-based aerogels for various adsorbates in water using different amino acids
Authors: Liu Wenjun , Wang Yongke , Li Zhaohui
Published: July 2014

The RGO-based aerogels with varied and controllable surface wettability can be fabricated using different amino acids and used as adsorbents for various adsorbates in water.
Mesityllithium and p-(dimethylamino)phenyllithium for the selective alternate trilithiation of the hexaphenylbenzene framework
Authors: Kojima Tatsuo , Hiraoka Shuichi
Published: July 2014

Mesityllithium and p-(dimethylamino)phenyllithium are new valuable lithiating reagents for the selective alternate trilithiation of the hexaphenylbenzene framework.
Nanoscale metal–organic frameworks as highly sensitive luminescent sensors for Fe2+ in aqueous solution and living cells
Authors: Lu Ye , Yan Bing , Liu Jin-Liang
Published: July 2014

We report the exploration of fluorescent nanoscale metal–organic frameworks (nMOF-253s) for highly selective and sensitive detection of Fe2+ ions in aqueous solution. Moreover, nMOF-253 of 50 nm is successfully applied in fluorescent bioimaging and intracellular Fe2+ sensing in HeLa cells.
The precursor manipulation of La2Zr2O7 epi-layers annealed by rapid thermal annealing
Authors: Cheng Yanling , Suo Hongli , Ma Lin , Zhang Zili , Xu Yan , Liu Min
Published: July 2014

This paper reports on the epitaxial growth of a La2Zr2O7 (LZO) buffer layer on the cube-textured Ni-5 at.%W substrate with nitrates as the precursor salts.
Computational and ion mobility MS study of (all-S)-cyclohexylhemicucurbit[6]uril structure and complexes
Authors: Öeren Mario , Shmatova Elena , Tamm Toomas , Aav Riina
Published: July 2014

Binding properties of chiral cyclohexylhemicucurbit[6]uril and geometries of its complexes with anions, proton and non-dissociated acids.
Facile synthesis of CuCr2O4 spinel nanoparticles: a recyclable heterogeneous catalyst for the one pot hydroxylation of benzene
Authors: Acharyya Shankha S. , Ghosh Shilpi , Adak Shubhadeep , Sasaki Takehiko , Bal Rajaram
Published: July 2014

A facile hydrothermal synthesis method is developed to prepare CuCr2O4 spinel nanoparticle catalysts with sizes between 25–50 nm for selective hydroxylation of benzene.
Supramolecular immobilization of bio-entities for bioelectrochemical applications
Authors: Holzinger Michael , Le Goff Alan , Cosnier Serge
Published: July 2014

Supramolecular systems based on host-guest, electrostatic, or metal-ligand interaction and their use in bioelectrochemical applications are reviewed.
Tunable thermopower and thermal conductivity in Lu doped In2O3
Authors: Zhu BeiBei , Tian Ruoming , Zhang Tianshu , Donelson Richard , Tan Thiam Teck , Wang Yu , Li Sean
Published: July 2014

Lu doped polycrystalline In2O3 compounds (x = 0, 0.025, 0.05, 0.10, 0.15) were synthesized by a co-precipitation method followed by the spark plasma sintering processing. Hall Effect measurement indicates that the carrier concentration was drastically decreased with doping, although Lu and In have the same valence state.
Assembled nano-structures from micron-sized precursors
Authors: Qian Bin , Xiao Changhong , Zou Ji , Zhong Yuan , Shen Zhijian
Published: July 2014

Oriented assembly of small crystals to form larger structures are common in nature and full understanding and control of such process would be beneficial for the forthcoming nano-technologies.
Gold nanoparticles embedded in Ta2O5/Ta3N5 as active visible-light plasmonic photocatalysts for solar hydrogen evolution
Authors: Luo Yujing , Liu Xiaoming , Tang Xinghua , Luo Yan , Zeng Qianyao , Deng Xiaolei , Ding Shaolei , Sun Yiqun
Published: July 2014

A Nano Au/Ta2O5 composite shows a new recreating photocatalytic activity for hydrogen evolution from water in response to visible light irradiation.
Wrapping DNA-gated mesoporous silica nanoparticles for quantitative monitoring of telomerase activity with glucometer readout
Authors: Wang Youmei , Lu Minghua , Zhu Jinhua , Tian Shufang
Published: July 2014

This work reports a simple and sensitive sensing protocol for the quantitative monitoring of telomerase activity based on target-responsive release of cargo from wrapping DNA-capped mesoporous silica nanoparticles (MSNs) by coupling with a portable personal glucometer (PGM).
Wideband hook‐shaped circularly polarised antenna
Authors: Samsuzzaman M. , Islam M.T.
Published: July 2014

A circularly polarised (CP) wideband hook‐shaped microstrip fed patch antenna is presented. The wideband CP property for the proposed antenna is achieved by the hook‐shaped branch in the ground plane and inverted asymmetric arm L‐shaped microstrip fed. With an optimised dimension of the proposed antenna parameter, the experimental results show that the antenna has a 10 dB impedance bandwidth of 1.41 GHz (1.84–3.25 GHz) and 3 dB axial ratio bandwidth of 1.67 GHz (1.86–3.53 GHz).
Optimal load sharing strategy for a wind/diesel/battery hybrid power system based on imperialist competitive neural network algorithm
Authors: Safari Masoud , Sarvi Mohammad
Published: July 2014

In this study, optimal load sharing strategy for a stand‐alone hybrid power generation system that consists of wind turbine, diesel generator and battery banks is presented. The diesel generator is used to complement the intermittent output of the wind source whereas the battery is used to compensate for part of the temporary peak demand, which the wind and diesel generator cannot meet thus avoiding oversizing of the diesel generator. To optimise the performance of the system, imperialist competitive algorithm (ICA), ant colony optimisation (ACO) and particle swarm optimisation (PSO) are used to optimal load sharing. These algorithms are used to select the best available energy source so that the system has the best performance.To verify the system performance simulation studies have been carried out using forecasted data (load demand and wind speed). Accordingly, ICA, ACO and PSO are used to train a three‐layer feed forward neural network. This trained artificial neural network is applied to short‐term wind speed and load demand forecasting on a specific day in the Qazvin. The results show that the proposed control methods can reduce fuel consumption and increase the battery lifetime and battery ability to respond to real‐time load turbulences simultaneously.
High frequency microfluidic performance of LiNbO3 and ZnO surface acoustic wave devices
Authors: Guo Y. J. , Lv H. B. , Li Y. F. , He X. L. , Zhou J. , Luo J. K. , Zu X. T. , Walton A. J. , Fu Y. Q.
Published: July 2014

Rayleigh surface acoustic wave (SAW) devices based on 128° YX LiNbO3 and ZnO/Si substrates with different resonant frequencies from ∼62 MHz to ∼275 MHz were fabricated and characterized. Effects of SAW frequency and power on microfluidic performance (including streaming, pumping, and jetting) were investigated. SAW excitation frequency influenced the SAW attenuation length and hence the acoustic energy absorbed by the liquid. At higher frequencies (e.g., above 100 MHz), the SAW dissipated into liquid decays more rapidly with much shorter decay lengths. Increasing the radio frequency (RF) frequencies of the devices resulted in an increased power threshold for streaming, pumping, and especially jetting, which is attributed to an increased absorption rate of acoustic wave energy. ZnO SAW devices could achieve similar streaming, pumping, and jetting effects as well as frequency effect, although the SAW signals are relatively weaker.
Preliminary design of laser-induced breakdown spectroscopy for proto-Material Plasma Exposure eXperiment
Authors: Shaw G. , Martin M. Z. , Martin R. , Biewer T. M.
Published: July 2014

Laser-induced breakdown spectroscopy (LIBS) is a technique for measuring surface matter composition. LIBS is performed by focusing laser radiation onto a target surface, ablating the surface, forming a plasma, and analyzing the light produced. LIBS surface analysis is a possible diagnostic for characterizing plasma-facing materials in ITER. Oak Ridge National Laboratory has enabled the initial installation of a laser-induced breakdown spectroscopy diagnostic on the prototype Material-Plasma Exposure eXperiment (Proto-MPEX), which strives to mimic the conditions found at the surface of the ITER divertor. This paper will discuss the LIBS implementation on Proto-MPEX, preliminary design of the fiber optic LIBS collection probe, and the expected results.
Solution-processed single-walled carbon nanotube field effect transistors and bootstrapped inverters for disintegratable, transient electronics
Authors: Jin Sung Hun , Shin Jongmin , Cho In-Tak , Han Sang Youn , Lee Dong Joon , Lee Chi Hwan , Lee Jong-Ho , Rogers John A.
Published: July 2014

This paper presents materials, device designs, and physical/electrical characteristics of a form of nanotube electronics that is physically transient, in the sense that all constituent elements dissolve and/or disperse upon immersion into water. Studies of contact effects illustrate the ability to use water soluble metals such as magnesium for source/drain contacts in nanotube based field effect transistors. High mobilities and on/off ratios in transistors that use molybdenum, silicon nitride, and silicon oxide enable full swing characteristics for inverters at low voltages (∼5 V) and with high gains (∼30). Dissolution/disintegration tests of such systems on water soluble sheets of polyvinyl alcohol demonstrate physical transience within 30 min.
Embedded-cluster calculations in a numeric atomic orbital density-functional theory framework
Authors: Berger Daniel , Logsdail Andrew J. , Oberhofer Harald , Farrow Matthew R. , Catlow C. Richard A. , Sherwood Paul , Sokol Alexey A. , Blum Volker , Reuter Karsten
Published: July 2014

We integrate the all-electron electronic structure code FHI-aims into the general ChemShell package for solid-state embedding quantum and molecular mechanical (QM/MM) calculations. A major undertaking in this integration is the implementation of pseudopotential functionality into FHI-aims to describe cations at the QM/MM boundary through effective core potentials and therewith prevent spurious overpolarization of the electronic density. Based on numeric atomic orbital basis sets, FHI-aims offers particularly efficient access to exact exchange and second order perturbation theory, rendering the established QM/MM setup an ideal tool for hybrid and double-hybrid level density functional theory calculations of solid systems. We illustrate this capability by calculating the reduction potential of Fe in the Fe-substituted ZSM-5 zeolitic framework and the reaction energy profile for (photo-)catalytic water oxidation at TiO2(110).
New tools for the systematic analysis and visualization of electronic excitations. II. Applications
Authors: Plasser Felix , Bäppler Stefanie A. , Wormit Michael , Dreuw Andreas
Published: July 2014

The excited states of a diverse set of molecules are examined using a collection of newly implemented analysis methods. These examples expose the particular power of three of these tools: (i) natural difference orbitals (the eigenvectors of the difference density matrix) for the description of orbital relaxation effects, (ii) analysis of the one-electron transition density matrix in terms of an electron-hole picture to identify charge resonance and excitonic correlation effects, and (iii) state-averaged natural transition orbitals for a compact simultaneous representation of several states. Furthermore, the utility of a wide array of additional analysis methods is highlighted. Five molecules with diverse excited state characteristics are chosen for these tasks: pyridine as a prototypical small heteroaromatic molecule, a model system of six neon atoms to study charge resonance effects, hexatriene in its neutral and radical cation forms to exemplify the cases of double excitations and spin-polarization, respectively, and a model iridium complex as a representative metal organic compound. Using these examples a number of phenomena, which are at first sight unexpected, are highlighted and their physical significance is discussed. Moreover, the generality of the conclusions of this paper is verified by a comparison of single- and multireference ab initio methods.
Aris-Taylor dispersion in tubes with dead ends
Authors: Dagdug Leonardo , Berezhkovskii Alexander M. , Skvortsov Alexei T.
Published: July 2014

This paper deals with transport of point Brownian particles in a cylindrical tube with dead ends in the presence of laminar flow of viscous fluid in the cylindrical part of the tube (Poiseuille flow). It is assumed that the dead ends are identical and are formed by spherical cavities connected to the cylindrical part of the tube by narrow necks. The focus is on the effective velocity and diffusivity of the particles as functions of the mean flow velocity and geometric parameter of the tube. Entering a dead end, the particle interrupts its propagation along the tube axis. Later it returns, and the axial motion continues. From the axial propagation point of view, the particle entry into a dead end and its successive return to the flow is equivalent to the particle reversible binding to the tube wall. The effect of reversible binding on the transport parameters has been previously studied assuming that the particle survival probability in the bound state decays as a single exponential. However, this is not the case when the particle enters a dead end, since escape from the dead end is a non-Markovian process. Our analysis of the problem consists of two steps: First, we derive expressions for the effective transport parameters in the general case of non-Markovian binding. Second, we find the effective velocity and diffusivity by substituting into these expressions known results for the moments of the particle lifetime in the dead end [L. Dagdug, A. M. Berezhkovskii, Yu. A. Makhnovskii, and V. Yu. Zitserman, J. Chem. Phys. 127, 224712 (2007)]. To check the accuracy of our theory, we compare its predictions with the values of the effective velocity and diffusivity obtained from Brownian dynamics simulations. The comparison shows excellent agreement between the theoretical predictions and numerical results.
Design and calibration of high-frequency magnetic probes for the SUNIST spherical tokamak
Authors: Liu Yangqing , Tan Yi , Pan Ou , Ke Rui , Wang Wenhao , Gao Zhe
Published: July 2014

A new high-frequency magnetic diagnostic system is designed, installed, and calibrated in the Sino-United Spherical Tokamak (SUNIST) to investigate Alfvén waves (AWs). The system consists of a fixed toroidal array and a movable radial array of high-frequency magnetic probes (HFMPs) with 21 and 60 probes, respectively. Based on the method of vacuum enameled wire wound on ceramic bobbins, the fixed toroidal array is located as near as possible to the plasma and carefully shielded to reduce the attenuation of high-frequency magnetic field. Meanwhile, by using the technology of commercial chip inductors mounted on printed circuit boards, the movable radial array is inserted into a thin quartz tube that allows positioning along radial direction. A Helmholtz coil is utilized to calibrate the effective areas as well as the frequency response of each HFMP. The calibration results are consistent with the calculated results of an equivalent probe-and-cable circuit model. High-frequency magnetic signals related to AW are detected with these HFMPs. These HFMPs are expected to play a key role in analyzing Alfvén eigenmodes excited by AW antenna in the SUNIST.
Ultrafast pump-probe and 2DIR anisotropy and temperature-dependent dynamics of liquid water within the E3B model
Authors: Ni Yicun , Skinner J. L.
Published: July 2014

Recently, Tainter et al. [J. Chem. Phys. 134, 184501 (2011)] reparameterized a new rigid water model (E3B) that explicitly includes three-body interactions in its Hamiltonian. Compared to commonly used water models such as SPC/E and TIP4P, the new model shows better agreement with experiment for many physical properties including liquid density, melting temperature, virial coefficients, etc. However, the dynamics of the E3B model, especially as a function of temperature, has not been systematically evaluated. Experimental nonlinear vibrational spectroscopy is an ideal tool to study the dynamics of matter in condensed phases. In the present study, we calculate linear and nonlinear vibrational spectroscopy observables for liquid water using the E3B model at five temperatures: 10, 30, 50, 70 and 90 °C. Specifically, we calculate absorption and Raman spectra and pump-probe anisotropy for HOD in H2O at all temperatures, frequency-resolved pump-probe anisotropy for HOD in both H2O and D2O at 30 °C, and 2DIR anisotropy for HOD in D2O at 30 °C. In all cases, we find reasonable agreement with experiment, and for the ultrafast spectroscopy our results are a significant improvement over those of the SPC/E model. A likely reason for this improvement is that the three-body interaction terms in the E3B model are able to model cooperative hydrogen bonding. We also calculate rotational and frequency relaxation times at all temperatures, and fit the results to the Arrhenius equation. We find that the activation energy for hydrogen-bond switching in liquid water is 3.8 kcal/mol, which agrees well with the experimental value of 3.7 kcal/mol obtained from anisotropy decay experiments.
Invariant tori with prescribed frequency for nearly integrable hamiltonian systems
Authors: Lu Xuezhu , Xu Junxiang
Published: July 2014

In this paper, we consider real analytic nearly integrable hamiltonian systems under Bruno non-degeneracy condition, and prove that if the rank of the Jacobian of the n-dimensional frequency vectors with respect to action variables is n − 1, then there exists a one-parameter analytic family of invariant tori, whose frequencies are the small dilation of a prescribed Diophantine frequency vector.
Air-water centrifugal convection
Authors: Herrada Miguel , Shtern Vladimir
Published: July 2014

A sealed cylindrical container is filled with air and water. The container rotation and the axial gradient of temperature induce the steady axisymmetric meridional circulation of both fluids due to the thermal buoyancy and surface-tension (Marangoni) effects. If the temperature gradient is small, the water circulation is one-cellular while the air circulation can be one- or two-cellular depending on water fraction Wf. The numerical simulations are performed for the cylinder length-to-radius ratio l = 1 and l = 4. The l = 4 results and the analytical solution for l → ∞ agree in the cylinder's middle part. As the temperature gradient increases, the water circulation becomes one-, two-, or three-cellular depending on Wf. The results are of fundamental interest and can be applied for bioreactors.
Diffusion affected magnetic field effect in exciplex fluorescence
Authors: Burshtein Anatoly I. , Ivanov Anatoly I.
Published: July 2014

The fluorescence of the exciplex, 1[D+δA−δ], formed at contact of photoexcited acceptor 1A* with an electron donor 1D, is known to be very sensitive to an external magnetic field, reducing the spin conversion efficiency in the resulting geminate radical ion pair, 1, 3[D+…A−]. The relative increase of the exciplex fluorescence in the highest magnetic field compared to the lowest one, known as the magnetic field effect, crucially depends on the viscosity of the solvent. This phenomenon first studied experimentally is at first reproduced here theoretically. The magnetic field effect is shown to vanish in both limits of high and low solvent diffusivity reaching a maximum in between. It is also very sensitive to the solvent dielectric constant and to the exciplex and radical-ion pair conversion rates.
Modeling of ns and ps laser-induced soft X-ray sources using nitrogen gas puff target
Authors: Vrba P. , Vrbova M. , Zakharov S. V. , Zakharov V. S.
Published: July 2014

Gas puff laser plasma is studied as a source of water window radiation with 2.88 nm wavelength, corresponding to quantum transition 1s2 → 1s2p of helium-like nitrogen ions. Spatial development of plasma induced by Nd:YAG laser beam is simulated by 2D Radiation-Magneto-Hydro-Dynamic code Z*. The results for nitrogen gas layer (0.72 mm thickness, 1 bar pressure) and two different laser pulses (600 mJ/7 ns and 525 mJ/170 ps), corresponding to the experiments done in Laser Laboratory Gottingen are presented.
Highly efficient terahertz wave modulators by photo-excitation of organics/silicon bilayers
Authors: Yoo Hyung Keun , Yoon Youngwoon , Lee Kiejin , Kang Chul , Kee Chul-Sik , Hwang In-Wook , Lee Joong Wook
Published: July 2014

Using hybrid bilayer systems comprising a molecular organic semiconductor and silicon, we achieve optically controllable active terahertz (THz) modulators that exhibit extremely high modulation efficiencies. A modulation efficiency of 98% is achieved from thermally annealed C60/silicon bilayers, due to the rapid photo-induced electron transfer from the excited states of the silicon onto the C60 layer. Furthermore, we demonstrate the broadband modulation of THz waves. The cut-off condition of the system that is determined by the formation of efficient charge separation by the photo-excitation is highly variable, changing the system from insulating to metallic. The phenomenon enables an extremely high modulation bandwidth and rates of electromagnetic waves of interest. The realization of near-perfect modulation efficiency in THz frequencies opens up the possibilities of utilizing active modulators for THz spectroscopy and communications.
Superscattering of light optimized by a genetic algorithm
Authors: Mirzaei Ali , Miroshnichenko Andrey E. , Shadrivov Ilya V. , Kivshar Yuri S.
Published: July 2014

We analyse scattering of light from multi-layer plasmonic nanowires and employ a genetic algorithm for optimizing the scattering cross section. We apply the mode-expansion method using experimental data for material parameters to demonstrate that our genetic algorithm allows designing realistic core-shell nanostructures with the superscattering effect achieved at any desired wavelength. This approach can be employed for optimizing both superscattering and cloaking at different wavelengths in the visible spectral range.
Communication: Separable potential energy surfaces from multiplicative artificial neural networks
Authors: Koch Werner , Zhang Dong H.
Published: July 2014

We present a potential energy surface fitting scheme based on multiplicative artificial neural networks. It has the sum of products form required for efficient computation of the dynamics of multidimensional quantum systems with the multi configuration time dependent Hartree method. Moreover, it results in analytic potential energy matrix elements when combined with quantum dynamics methods using Gaussian basis functions, eliminating the need for a local harmonic approximation. Scaling behavior with respect to the complexity of the potential as well as the requested accuracy is discussed.
Near surface silicide formation after off-normal Fe-implantation of Si(001) surfaces
Authors: Khanbabaee B. , Lützenkirchen-Hecht D. , Hübner R. , Grenzer J. , Facsko S. , Pietsch U.
Published: July 2014

We report on formation of non-crystalline Fe-silicides of various stoichiometries below the amorphized surface of crystalline Si(001) after irradiation with 5 keV Fe+ ions under off-normal incidence. We examined samples prepared with ion fluences of 0.1 × 1017 and 5 × 1017 ions cm−2 exhibiting a flat and patterned surface morphology, respectively. Whereas the iron silicides are found across the whole surface of the flat sample, they are concentrated at the top of ridges at the rippled surface. A depth resolved analysis of the chemical states of Si and Fe atoms in the near surface region was performed by combining X-ray photoelectron spectroscopy and X-ray absorption spectroscopy (XAS) using synchrotron radiation. The chemical shift and the line shape of the Si 2p core levels and valence bands were measured and associated with the formation of silicide bonds of different stoichiometric composition changing from an Fe-rich silicides (Fe3Si) close to the surface into a Si-rich silicide (FeSi2) towards the inner interface to the Si(001) substrate. This finding is supported by XAS analysis at the Fe K-edge which shows changes of the chemical environment and the near order atomic coordination of the Fe atoms in the region close to surface. Because a similar Fe depth profile has been found for samples co-sputtered with Fe during Kr+ ion irradiation, our results suggest the importance of chemically bonded Fe in the surface region for the process of ripple formation.
A combined capacitance-voltage and hard x-ray photoelectron spectroscopy characterisation of metal/Al2O3/In0.53Ga0.47As capacitor structures
Authors: Lin Jun , Walsh Lee , Hughes Greg , Woicik Joseph C. , Povey Ian M. , O'Regan Terrance P. , Hurley Paul K.
Published: July 2014

Capacitance-Voltage (C-V) characterization and hard x-ray photoelectron spectroscopy (HAXPES) measurements have been used to study metal/Al2O3/In0.53Ga0.47As capacitor structures with high (Ni) and low (Al) work function metals. The HAXPES measurements observe a band bending occurring prior to metal deposition, which is attributed to a combination of fixed oxide charges and interface states of donor-type. Following metal deposition, the Fermi level positions at the Al2O3/In0.53Ga0.47As interface move towards the expected direction as observed from HAXPES measurements. The In0.53Ga0.47As surface Fermi level positions determined from both the C-V analysis at zero gate bias and HAXPES measurements are in reasonable agreement. The results are consistent with the presence of electrically active interface states at the Al2O3/In0.53Ga0.47As interface and suggest an interface state density increasing towards the In0.53Ga0.47As valence band edge.
Terahertz generation by two cross focused laser beams in collisional plasmas
Authors: Sharma R. P. , Singh Ram Kishor
Published: July 2014

The role of two cross-focused spatial-Gaussian laser beams has been studied for the high power and efficient terahertz (THz) radiation generation in the collisional plasma. The nonlinear current at THz frequency arises on account of temperature dependent collision frequency of electrons with ions in the plasma and the presence of a static electric field (applied externally in the plasma) and density ripple. Optimisation of laser-plasma parameters gives the radiated THz power of the order of 0.23  MW.
Current-driven domain wall motion enhanced by the microwave field
Authors: Wang Xi-guang , Guo Guang-hua , Nie Yao-zhuang , Wang Dao-wei , Zeng Zhong-ming , Li Zhi-xiong , Tang Wei
Published: July 2014

The magnetic domain wall (DW) motion driven by a spin-polarized current opens a new concept for memory and logic devices. However, the critical current density required to overcome the intrinsic and/or extrinsic pinning of DW remains too large for practical applications. Here, we show, by using micromagnetic simulations and analytical approaches, that the application of a microwave field offers an effective solution to this problem. When a transverse microwave field is applied, the adiabatic spin-transfer torque (STT) alone can sustain a steady-state DW motion without the sign of Walker breakdown, meaning that the intrinsic pinning disappears. The extrinsic pinning can also be effectively reduced. Moreover, the DW velocity is increased greatly for the microwave-assisted DW motion. This provides a new way to manipulate the DW motion at low current densities.
Electron spin relaxation time in (110) InGaAs/InAlAs quantum wells
Authors: Yokota Nobuhide , Yasuda Yusuke , Ikeda Kazuhiro , Kawaguchi Hitoshi
Published: July 2014

Electron spin relaxation time τs in InGaAs/InAlAs quantum wells (QWs) grown on (110) and (100) InP substrates was investigated by pump-probe transmission measurements. Similar τs of 0.83–1.0 ns were measured at room temperature for all the measured (110) and (100) QWs, indicating suppression of the D'yakonov-Perel' spin relaxation mechanism in (110) QWs is not effective in InGaAs/InAlAs QWs as opposed to GaAs/AlGaAs QWs. Contribution of the Bir-Aronov-Pikus mechanism dominant in (110) GaAs/AlGaAs QWs was found to be small in both the (110) and (100) InGaAs/InAlAs QWs from the weak dependences of τs on pump intensity at room temperature. These results suggest that the spin relaxation mechanism dominant in InGaAs/InAlAs QWs at a temperature higher than 200 K is the Elliott-Yafet mechanism independent of the crystal orientation among the above three major mechanisms.
Inhibition of light emission in a 2.5D photonic structure
Authors: Peretti Romain , Seassal Christian , Viktorovich Pierre , Letartre Xavier
Published: July 2014

We analyse inhibition of emission in a 2.5D photonic structures made up of a photonic crystal (PhC) and Bragg mirrors using Finite Differences Time Domaine (FDTD) simulations. A comparison is made between an isolated PhC membrane and the same PhC suspended onto a Bragg mirror or sandwiched between 2 Bragg mirrors. Strong inhibition of the Purcell factor is observed in a broad spectral range, whatever the in-plane orientation and location of the emitting dipole. We analysed these results numerically and theoretically by simulating the experimentally observed lifetime of a collection of randomly distributed emitters, showing that their average emission rate is decreased by more than one decade, both for coupled or isolated emitters.
Acoustic confinement and waveguiding in two-dimensional phononic crystals with material defect states
Authors: Li Yinggang , Chen Tianning , Wang Xiaopeng , Ma Ting , Jiang Ping
Published: July 2014

In this paper, we present the theoretical investigation of acoustic confinement and waveguiding in two-dimensional phononic crystals with material defect states. In contrast to the typical formation pattern of defect states, the proposed material defect states are created by replacing single cylinder in the core center or one row of cylinders in the perfect phononic crystal with different material cylinders. The dispersion relations and the power transmission spectra are studied by using the finite element method in combination with a supercell technique. With the introduction of material defects into perfect phononic crystals, defect states and bands appear, elastic waves of specific frequencies are localized in the point defects or along the line defects, respectively. The displacement fields of the eigenmodes are carried out to further intuitively illustrate the acoustic confinement and waveguiding in the material defect states phononic crystals. Furthermore, the effects of the material parameters of defects on the point defect states and waveguiding are further explored numerically. Numerical results show that, the location and number of defect states can be efficiently modulated by the material parameters of defects. The material defect states are more sensitive to the density parameters than the elastic constants when the elastic modulus of the defects is far higher than that of matrix.
The influence of the AlN barrier thickness on the polarization Coulomb field scattering in AlN/GaN heterostructure field-effect transistors
Authors: Lv Yuanjie , Feng Zhihong , Lin Zhaojun , Ji Ziwu , Zhao Jingtao , Gu Guodong , Han Tingting , Yin Jiayun , Liu Bo , Cai Shujun
Published: July 2014

The electron mobility scattering mechanisms in AlN/GaN heterostuctures with 3 nm and 6 nm AlN barrier thicknesses were investigated by temperature-dependent Hall measurements. The effect of interface roughness (IFR) scattering on the electron mobility was found to be enhanced by increasing AlN barrier thickness. Moreover, using the measured capacitance-voltage and current-voltage characteristics of the fabricated heterostructure field-effect transistors (HFETs) with different Schottky areas on the two heterostuctures, the variations of electron mobility with different gate biases were investigated. Due to enhanced IFR scattering, the influence of polarization Coulomb field (PCF) scattering on electron mobility was found to decrease with increasing AlN barrier layer thickness. However, the PCF scattering remained an important scattering mechanism in the AlN/GaN HFETs.
Effects of polycrystallinity in nano patterning by ion-beam sputtering
Authors: Yoon Sun Mi , Kim J.-S. , Yoon D. , Cheong H. , Kim Y. , Lee H. H.
Published: July 2014

Employing graphites with distinctly different mean grain sizes, we study the effects of polycrystallinity on the pattern formation by ion-beam sputtering. The grains influence the growth of the ripples in a highly anisotropic fashion; both the mean uninterrupted ripple length along the ridges and the surface width depend on the mean size of the grains, which is attributed to the large sputter yield at the grain boundary compared with that on the terrace. In contrast, the ripple wavelength does not depend on the mean size of the grains, indicating that the mass transport across the grain boundaries should efficiently proceed by both thermal diffusion and ion-induced processes.
Observations on size confinement effect in B-C-N nanoparticles embedded in mesoporous silica channels
Authors: Tripathi Neeti , Yamashita Masaru , Uchida Takeyuki , Akai Tomoko
Published: July 2014

Fluorescent B-C-N/silica nanoparticles were synthesized by solution impregnation method. Effect of B-C-N particle size on the optical properties was investigated by varying the silica pore sizes. Formation of B-C-N nanoparticles within the mesoporous matrix is confirmed by x-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. Furthermore, a remarkable blue-shift in emission peak centres with decreasing pore size in conjugation with band gap modification, ascribed to the size confinement effect. A detailed analysis of experimental results by theoretically defined confinement models demonstrates that the B-C-N nanoparticles in the size range of 3–13 nm falls within the confinement regime. This work demonstrated the experimental evidence of the size confinement effect in smaller size B-C-N nanoparticles.
Influence of grain boundary modification on limited performance of wide bandgap Cu(In,Ga)Se2 solar cells
Authors: Raghuwanshi M. , Cadel E. , Pareige P. , Duguay S. , Couzinie-Devy F. , Arzel L. , Barreau N.
Published: July 2014

The reason why so-called wide-bandgap CuIn1−xGaxSe2 (CIGSe with x > 0.4) based solar cells show hindered performance compared with theoretical expectations is still a matter of debate. In the present Letter, atom probe tomography studies of CuIn1−xGaxSe2 polycrystalline thin films with x varying from 0 to 1 are reported. These investigations confirm that the grain boundaries (GBs) of low gallium containing (x < 0.4) CIGSe layers are Cu-depleted compared with grains interior (GI). In contrast, it is observed that the GBs of widest band gap CIGSe films (x > 0.8) are Cu-enriched compared with GI. For intermediate gallium contents (0.4 < x < 0.8), both types of GBs are detected. This threshold value of 0.4 surprisingly coincides with solar cells output voltage deviation from theoretical expectations, which suggests modifications of GBs properties could participate in the loss of photovoltaic performance.
Strength, stiffness, and microstructure of Cu(In,Ga)Se2 thin films deposited via sputtering and co-evaporation
Authors: Luo Shi , Lee Jiun-Haw , Liu Chee-Wee , Shieh Jia-Min , Shen Chang-Hong , Wu Tsung-Ta , Jang Dongchan , Greer Julia R.
Published: July 2014

This work examines Cu(In,Ga)Se2 thin films fabricated by (1) selenization of pre-sputtered Cu-In-Ga and (2) co-evaporation of each constituent. The efficiency disparity between films deposited via these two methods is linked to differences in morphology and microstructure. Atomic force microscopy and scanning electron microscopy show that selenized films have rougher surfaces and poor adhesion to molybdenum back contact. Transmission electron microscopy and electron energy loss spectroscopy revealed multiple voids near the Mo layer in selenized films and a depletion of Na and Se around the voids. Residual stresses in co-evaporated films were found to be ∼1.23 GPa using wafer curvature measurements. Uniaxial compression experiments on 500 nm-diameter nanopillars carved out from co-evaporated films revealed the elastic modulus of 70.4 ± 6.5 GPa. Hertzian contact model applied to nanoindentation data on selenized films revealed the indentation modulus of 68.9 ± 12.4 GPa, which is in agreement with previous reports. This equivalence of the elastic moduli suggests that microstructural differences manifest themselves after the yield point. Typical plastic behavior with two distinct failure modes is observed in the extracted stress-strain results, with the yield strength of 640.9 ± 13.7 MPa for pillars that failed by shearing and 1100.8 ± 77.8 MPa for pillars that failed by shattering.
Frequency-stabilized limit-cycle dynamics of an optically injected semiconductor laser
Authors: AlMulla Mohammad , Liu Jia-Ming
Published: July 2014

Limit-cycle dynamics are self-sustained oscillations that arise in man-made nonlinear systems and in nature. In an optically injected semiconductor laser, limit-cycle oscillations can reach a frequency ten times the relaxation resonance frequency of the solitary semiconductor laser. To stabilize such oscillations, complicated circuitry is often used. Here, we demonstrate limit-cycle oscillations of inherently stable frequencies. By properly choosing the operating conditions, three distinct types of stable-frequency oscillation points are defined.
Phosphorescence quenching by mechanical stimulus in CaZnOS:Cu
Authors: Tu Dong , Xu Chao-Nan , Fujio Yuki , Kamimura Sunao , Sakata Yoshitaro , Ueno Naohiro
Published: July 2014

We have found that phosphorescence intensity of CaZnOS:Cu decreased visibly under an applied load. This mechanical quenching (MQ) of phosphorescence in CaZnOS:Cu corresponded to the mechanical stimuli. We have thus demonstrated that the MQ of CaZnOS:Cu could be used for visualizing stress distributions in practical applications. We propose that MQ arises from non-radiative recombination due to electron-transfer from trap levels to non-radiative centers as a result of the mechanical load.
Formation and photoluminescence of GaAs1−xNx dilute nitride achieved by N-implantation and flash lamp annealing
Authors: Gao Kun , Prucnal S. , Skorupa W. , Helm M. , Zhou Shengqiang
Published: July 2014

In this paper, we present the fabrication of dilute nitride semiconductor GaAs1−xNx by nitrogen-ion-implantation and flash lamp annealing (FLA). N was implanted into the GaAs wafers with atomic concentration of about ximp1 = 0.38% and ximp2 = 0.76%. The GaAs1−xNx layer is regrown on GaAs during FLA treatment in a solid phase epitaxy process. Room temperature near band-edge photoluminescence (PL) has been observed from the FLA treated GaAs1−xNx samples. According to the redshift of the near band-edge PL peak, up to 80% and 44% of the implanted N atoms have been incorporated into the lattice by FLA for ximp1 = 0.38% and ximp2 = 0.76%, respectively. Our investigation shows that ion implantation followed by ultrashort flash lamp treatment, which allows for large scale production, exhibits a promising prospect on bandgap engineering of GaAs based semiconductors.
Climate projections for 2050.
Authors: Rummukainen M.
Published: July 2014

This chapter provides the background for the subsequent chapters in this book, and discusses climate projections for the next few decades. While the focus is on the period until 2050, it should be noted that climate change will very likely continue well beyond the middle of the 21st century. Indeed, the long-term prospects are about not only a changed climate but also a climate that is changing over time, i.e. it is about continuous change over a long time. The same is thus also true for knowledge requirements regarding climate change impacts, as well as the motivation and need for climate change adaptation; however, these may take form.
Climate change challenges for low-input cropping and grazing systems - Australia.
Authors: Crimp S. , Howden M. , Stokes C. , Schroeter S. , Keating B.
Published: July 2014

This chapter discusses the mechanisms by which climate change will influence broad-acre rainfed farming systems (cropping and grazing) in Australia and critically evaluates possible on-farm adaptation options. These results will be aggregated to national scales to examine the benefits derived from adaptation to climate change. The main projected challenges for the grazing industry under climate change are declines in pasture productivity, reduced forage quality, livestock heat stress, greater problems with some pests and weeds, more frequent droughts, more intense rainfall events and greater risks of soil degradation. The chapter establishes that the scale of climate change adaptation will need to respond to the extent of projected climate change, with tactical adaptation suitable for modest climate change, systemic adaptation suitable for more extensive climate change and transformative adaptation suitable for significant project change in temperature and rainfall.
Adaptation of mixed crop-livestock systems in Asia.
Authors: Hou FuJiang Hou FuJiang
Published: July 2014

This chapter focuses on the the current situation of mixed crop-livestock systems in Asia. The impacts of climate change and adaptation of crop-livestock systems are discussed and approaches to mitigating greenhouse gases through managing integrated farming systems are highlighted.
The impact of tax concessions on extraction of non-renewable resources: an application to gold mining in Tanzania
Authors: Ibrahim Shwilima Amos James , Konishi Hideki
Published: July 2014

Gold mining firms in Tanzania pay royalty and corporate taxes, but also receive many tax concessions. Such tax incentives may cause to reschedule their extraction plans and thereby change the expected life of a gold mine. We model a representative mining firm's extraction decision using optimal control theory, into which various tax incentives are introduced to determine their theoretical impact. Our results suggest that in the race to take advantage of tax incentives, a firm may end up making excessive investments, which in turn increases extraction rate. Actual extraction patterns of several gold mining companies in Tanzania are also reviewed.
Active inclusion as an organisational challenge: integrated anti-poverty policies in three European countries
Authors: Heidenreich Martin , Petzold Norbert , Natili Marcello , Panican Alexandru
Published: July 2014

Active inclusion aims at the reduction of poverty by strengthening the agency of excluded persons by the provision of a minimum income, activation and social services. The contribution to poverty alleviation is determined by expenditure levels and the organisation of these three policy fields. This can be shown by three examples: The comprehensive Swedish regime is characterised by high expenditures; the redistributive German regime is characterised by lower service levels and in Italy, all three dimensions are least developed. In addition, the organisation of services differs: Decentralised and discretionary system for the provision of services in Sweden, “creaming and parking” effects in Germany and fragmented providers in Italy. As a result of different expenditure levels and organisational patterns, the selectivity of active inclusion strategies is low in Sweden, medium in Germany and high in Italy. Both the financial and organisational dimensions of active inclusion therefore are decisive for poverty alleviation.
Patterns of institutional change in minimum income protection in Sweden and Germany
Authors: Angelin Anna , Johansson Håkan , Koch Max
Published: July 2014

Germany is generally regarded as a case of qualitative “change” in minimum income protection (MIP) schemes, while Sweden is perceived as one of institutional “inertia”. This paper seeks to qualify this view by embedding developments in MIP in wider policy and governance trends. Empirically, it is based on document analysis and qualitative expert interviews in the two countries. Theoretically, the paper applies recent institutional approaches that address patterns of change in more complex ways. In Sweden, an exclusive focus on formal continuity regarding social assistance would disguise its change in function from temporary security system of last resort into one that permanently provides income protection when neighboring policy fields, unemployment and sickness insurance, are downsized. Conversely, in Germany a merger of social assistance and unemployment assistance took place. Yet an exclusive focus on the Hartz reforms would downplay the degree of continuity that nevertheless exists in the unemployment insurance.