bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasma polymerization of 1,1,1-trichloroethane yields a coating with robust antibacterial surface properties
Authors: Michl Thomas D. , Coad Bryan R. , Doran Michael , Hüsler Amanda , Valentin Jules D. P. , Vasilev Krasimir , Griesser Hans J.
Published: June 2014

Novel, highly chlorinated surface coatings were produced via a one-step plasma polymerization (pp) of 1,1,1-trichloroethane (TCE), exhibiting excellent antimicrobial properties against the vigorously biofilm-forming bacterium Staphylococcus epidermidis.
Facile method for preparation of superfine copper nanoparticles with high concentration of copper chloride through photoreduction
Authors: Wang Bowen , Chen Shuxi , Nie Jun , Zhu Xiaoqun
Published: June 2014

Through photoreduction, superfine copper nanoparticles were prepared form a high concentration of copper chloride at room temperature in the presence of the capping agent PEI.
TfOH catalyzed synthesis of 9-arylfluorenes via tandem reaction under warm and efficient conditions
Authors: Li Qingcui , Xu Wengang , Hu Jiaxing , Chen Xiaoqing , Zhang Fanglin , Zheng Hua
Published: June 2014

A tandem ring-closing reaction was developed for the synthesis of 9-arylfluorenes and their derivatives. The reaction is metal-free, straightforward and efficient under warm conditions and more than 99% yield is obtained.
Four component domino reaction for the synthesis of highly functionalized dimeric tetracyclic dilactam fluorophores: H-bond aided self-assembly
Authors: Ramachandran G. , Raman A. , Easwaramoorthi S. , Rathore R. S. , Sathiyanarayanan K.
Published: June 2014

A series of new dimeric tetracyclic dilactam fluorophores (DTDF) consisting of diazabicyclooctane-dione (DBOD) fused to tetrahydronaphthalene (THP) was designed and synthesized from a simple precursor.
Adsorption of metal ions by clays and inorganic solids
Authors: Sen Gupta Susmita , Bhattacharyya Krishna G.
Published: June 2014

This review deals with adsorption of metal ions, particularly those considered as hazardous, on clays and some inorganic solids and covers the publication years 2000–2013 describing and quantifying the use of isotherms to obtain the adsorption capacities of the solids.
Simultaneous dehydration of biomass-derived sugars to 5-hydroxymethyl furfural (HMF) and reduction of graphene oxide in ethyl lactate: one pot dual chemistry
Authors: Mondal Dibyendu , Chaudhary Jai Prakash , Sharma Mukesh , Prasad Kamalesh
Published: June 2014

Biomass-based sugars were dehydrated in ethyl lactate in the presence of graphene oxide, choline chloride and betaine hydrochloride resulting in the formation of HMF and rGO.
Simulation of the tensile properties of silica aerogels: the effects of cluster structure and primary particle size
Authors: Liu Qiang , Lu Zixing , Zhu Man , Yuan Zeshuai , Yang Zhenyu , Hu Zijun , Li Junning
Published: June 2014

A new two-level model is proposed to investigate the relationship between the mechanical properties and microstructure of silica aerogels.
Selective removal of metallic single-walled carbon nanotubes by microwave-assisted treatment of SWCNTs with nitronium ions
Authors: Shen Xiao , Qiu Hanxun , Li Jing , Zhang Huijuan , Zhao Bin , Yang Junhe
Published: June 2014

The synergistic effect of microwave irradiation and nitronium ions allows a more efficient separation of S-SWCNTs from M-SWCNTs.
Gas uptake, molecular sensing and organocatalytic performances of a multifunctional carbazole-based conjugated microporous polymer
Authors: Zhang Yuwei , A Sigen , Zou Yongcun , Luo Xiaolong , Li Zhongping , Xia Hong , Liu Xiaoming , Mu Ying
Published: June 2014

A multifunctional conjugated microporous polymer exhibits a combination of functionalities such as selective CO2uptake, sensing hazardous and explosive molecules and highly efficient heterogeneous catalysis.
NiCo2O4-based materials for electrochemical supercapacitors
Authors: Wu Zhibin , Zhu Yirong , Ji Xiaobo
Published: June 2014

NiCo2O4-based materials have become a new class of energy storage materials for electrochemical supercapacitors, which manifest remarkable electrochemical performances.
Doped h-BN monolayer as efficient noble metal-free catalysts for CO oxidation: the role of dopant and water in activity and catalytic de-poisoning
Authors: Sinthika S. , Kumar E. Mathan , Thapa Ranjit
Published: June 2014

Metal free catalyst for CO oxidation: competition between two mechanisms.
Development of a redox/pH dual stimuli-responsive MSP@P(MAA-Cy) drug delivery system for programmed release of anticancer drugs in tumour cells
Authors: Li Dian , Zhang Yuting , Jin Sha , Guo Jia , Gao Haifeng , Wang Changchun
Published: June 2014

A redox/pH dual-stimuli-responsive drug delivery system for programmed release of anticancer drugs has been developed for enhancing the therapeutic effect.
Self-assembly-induced near-infrared fluorescent nanoprobes for effective tumor molecular imaging
Authors: Wu Hao , Zhao Haidong , Song Xiaojie , Li Shen , Ma Xiaojun , Tan Mingqian
Published: June 2014

Self-assembly-induced near-infrared fluorescent nanoprobes exhibiting spontaneous lattices were prepared and evaluated for in vitro and in vivo tumor molecular imaging.
Synthesis of hexagonal ZnO nanodrums, nanosheets and nanowires by the ionic effect during the growth of hexagonal ZnO crystals
Authors: Jung Mi-Hee , Chu Moo-Jung
Published: June 2014

Hexagonal ZnO nanodrums, nanosheets and nanowires were synthesized by simply adding the ions into the hexagonal ZnO crystalline precursor solution.
Use of Shapley value for selecting centres in RBF neural regressors
Authors: Coelho A.L.V. , Maia J.E.B. , Sandes N.C.
Published: June 2014

The problem of centre selection in radial basis function neural networks (RBFNNs) is re‐examined and tackled through a cooperative game theoretic perspective. By resorting to the notion of Shapley value, the approach ranks candidate centres (modelled as game players) for the RBFNN's hidden layer based on a sampled estimation of their marginal contribution to the cross‐validation training error. Results achieved on benchmark regression problems are reported, whereby it has been shown that the proposed approach improves on the results delivered by the two well‐known algorithms.
Metallic short backfire antenna with halved size and wideband characteristics
Authors: Liu Longsheng , Wang Han , Li Yue , Zhang Zhijun , Feng Zhenghe
Published: June 2014

A short backfire antenna is proposed for 5.2/5.8 GHz wireless local area network (WLAN) applications. Wideband impedance matching is achieved by employing a truncated monopole as the exciter. Moreover, power‐handling capability could be enhanced by the all‐metallic configuration. The proposed antenna with halved size has two configurations when placed on a ground plane to meet the demands for different applications.
Improving signal to noise of current mode circuits by a cross‐coupled current mirror topology
Authors: Ghanad M.A. , Green M.M. , Dehollain C.
Published: June 2014

A cross‐coupled current mirror topology is presented. This topology increases the gain of a circuit that amplifies a pair of differential currents without increasing its power dissipation. An example circuit employing this current mirroring technique is presented. Gain and noise analyses are provided to show the effectiveness of the proposed topology in decreasing the input‐referred noise. The analysis also shows that this configuration increases the input resistance and settling time of the circuit.
Orthogonal projection based asymmetric multi‐way relaying with antenna subset selection
Authors: Li Wei , Li Guobing , Zhu Shihua , Hua Kun
Published: June 2014

An asymmetric multi‐way relay communication scheme using orthogonal projection and analogue network coding is proposed. The scheme is designed for the wireless sensor network, where one sink node (SN) exchanges information with multiple user nodes via a relay station and both the SN and user nodes have low complexity structures. It has been observed that the minimal number of the relay antennas can be smaller than that of the total data streams. Moreover, when the number of the relay antennas is larger than the minimum, a paired throughput based max–min criterion with low computational complexity is developed to select the optimal relay antenna subset and guarantee full diversity gain. The numerical results demonstrate the high performance of the proposed communication scheme and antenna subset selection criterion.
Impact of pilot pattern on carrier frequency recovery for TETRA‐like multitone modulations
Authors: Marchetti L. , Reggiannini R.
Published: June 2014

A study of maximum‐likelihood pilot‐aided frequency offset recovery for filtered multitone modulations such as that employed in the TETRA Release 2 Enhanced Data Service is presented. An approach is proposed to improve on previously published algorithms. When pilot symbols are arranged on a rectangular time–frequency grid, as envisaged by the cited standard, the acquisition range of a pilot‐based frequency synchroniser may seem to be very narrow as it cannot exceed the inverse of pilot spacing in the time‐domain. It is shown that the above drawback can be relieved by resorting to a pilot pattern where the pilot symbols are simply shifted in time along the subcarriers with respect to the rectangular arrangement.
Digital linear pre‐compensation technique to enhance predistortion performance in multicarrier DVB‐S2 satellite communication systems
Authors: Allegue‐Martínez M. , Kelly N. , Zhu A.
Published: June 2014

Nonlinearity in communication satellite payloads often severely degrades the downlink signal quality in such systems. A digital pre‐compensation technique to enhance digital predistortion performance in multicarrier satellite communication systems is presented. The proposed technique has been validated by simulations with an appropriate platform where excellent performance improvements have been measured. In addition, the implementation feasibility of this technique has been briefly demonstrated by means of a real‐time FPGA implementation.
Super‐lift boost converters
Authors: Luo Fang Lin , Ye Hong
Published: June 2014

Voltage lift technique has been successfully employed in design of DC/DC converters, for example, four series Luo‐converters. However, the voltage transfer gain increases stage‐by‐stage in arithmetic progression. Super‐lift converters largely enhance the voltage transfer gain, which increases stage‐by‐stage in geometric progression. It effectively enhances the voltage transfer gain in power series. This study introduces a novel approach – modified super‐lift converters that implements the super‐lift operation as well, its voltage transfer gain increases stage‐by‐stage also in geometric progression.
Rapid prototyping of power electronics converters for photovoltaic system application using Xilinx System Generator
Authors: Selvamuthukumaran Rajasekar , Gupta Rajesh
Published: June 2014

The aim of this study is to develop a research platform for rapid prototyping of the power electronics converters for solar photovoltaic (PV) system applications. This study describes the field‐programmable gate array (FPGA)‐based hardware‐in‐the‐loop (HIL) simulation of voltage source inverter (VSI) used for PV system power conversion. The PV system and inverter models are realised in simulation as part of the HIL to test the real‐time functionality of the FPGA controller. The generation of switching control signals for the VSI and its interface with the PV system is developed through the Xilinx System Generator (XSG) domain. The XSG automatically generates the VHSIC hardware description language (VHDL) code using hardware description language co‐simulation for generation of gating signal for modulation of the VSI. To validate the proposed approach, the sinusoidal pulse‐width modulation using bipolar and unipolar switching schemes and current control method have been tested for the PV supported VSI. The proposed approach of the rapid prototype model has been designed and implemented in the laboratory through XSG and MATLAB/SIMULINK interface. Performance comparison between the software simulation and real‐time HIL simulation has been demonstrated.
Management of the Temporomandibular Joint after Ablative Surgery
Authors: Bredell Marius , Grätz Klaus , Obwegeser Joachim , Gujer AstridKruse
Published: June 2014

Management of the temporomandibular joint in ablative head and neck surgery is controversial with no standardized approach. The aim of the study was to establish risk-based guidelines for the management of the temporomandibular joint after ablative surgery.

Analysis of all patients’ records receiving ablative surgery involving the temporomandibular joint in the Department of Cranio-Maxillofacial and Oral Surgery, University Hospital of Zϼrich, from 2001 to 2012, was performed, identifying 15 patients and 14 reconstructive procedures. A literature search was done identifying all relevant literature on current approaches. Applicable cohorts were constructed, and relevant risks were extrapolated. Evaluated studies are not uniform in their reporting with nonhomogeneous patient groups. A diverse approach is used in the management of these patients with complications such as infection, ankylosis, limited mouth opening, plate penetration in the skull base, and plate loosening. Risk factors for complications appear to be radiation, costochondral graft, disk loss, and plate use alone. Clinical data suggest use of a plate with metal condyle reconstructions and previous radiation therapy as potential risks factors. Employing literature evidence and cumulated clinical data, a risk-based flowchart was developed to assist surgical decision making. Risk factors such as radiation, disk preservation, and soft tissue conditions are important complication-associated factors when planning surgery. Free vascularized fibula grafts appear to have the least complications that must be weighed against donor site morbidity.
The structural diversity of ABS3 compounds with d electronic configuration for the B-cation
Authors: Brehm John A. , Bennett Joseph W. , Schoenberg Michael Rutenberg , Grinberg Ilya , Rappe Andrew M.
Published: June 2014

We use first-principles density functional theory within the local density approximation to ascertain the ground state structure of real and theoretical compounds with the formula ABS3 (A = K, Rb, Cs, Ca, Sr, Ba, Tl, Sn, Pb, and Bi; and B = Sc, Y, Ti, Zr, V, and Nb) under the constraint that B must have a d0 electronic configuration. Our findings indicate that none of these AB combinations prefer a perovskite ground state with corner-sharing BS6 octahedra, but that they prefer phases with either edge- or face-sharing motifs. Further, a simple two-dimensional structure field map created from A and B ionic radii provides a neat demarcation between combinations preferring face-sharing versus edge-sharing phases for most of these combinations. We then show that by modifying the common Goldschmidt tolerance factor with a multiplicative term based on the electronegativity difference between A and S, the demarcation between predicted edge-sharing and face-sharing ground state phases is enhanced. We also demonstrate that, by calculating the free energy contribution of phonons, some of these compounds may assume multiple phases as synthesis temperatures are altered, or as ambient temperatures rise or fall.
Derivation of coarse-grained potentials via multistate iterative Boltzmann inversion
Authors: Moore Timothy C. , Iacovella Christopher R. , McCabe Clare
Published: June 2014

In this work, an extension is proposed to the standard iterative Boltzmann inversion (IBI) method used to derive coarse-grained potentials. It is shown that the inclusion of target data from multiple states yields a less state-dependent potential, and is thus better suited to simulate systems over a range of thermodynamic states than the standard IBI method. The inclusion of target data from multiple states forces the algorithm to sample regions of potential phase space that match the radial distribution function at multiple state points, thus producing a derived potential that is more representative of the underlying interactions. It is shown that the algorithm is able to converge to the true potential for a system where the underlying potential is known. It is also shown that potentials derived via the proposed method better predict the behavior of n-alkane chains than those derived via the standard IBI method. Additionally, through the examination of alkane monolayers, it is shown that the relative weight given to each state in the fitting procedure can impact bulk system properties, allowing the potentials to be further tuned in order to match the properties of reference atomistic and/or experimental systems.
High-resolution photoelectron imaging of cold ${\rm C}_{60}^ -$C60− anions and accurate determination of the electron affinity of C60
Authors: Huang Dao-Ling , Dau Phuong Diem , Liu Hong-Tao , Wang Lai-Sheng
Published: June 2014

High-resolution photoelectron imaging and spectroscopy of cold ${\rm C}_{60}^ -$C60− anions are reported using a newly built photoelectron imaging apparatus coupled with an electrospray ionization source and a temperature-controlled cryogenic ion trap. Vibrationally resolved photoelectron spectra are obtained for the detachment transition from the ground state of ${\rm C}_{60}^ -$C60− to that of C60 at various detachment wavelengths from 354.84 nm to 461.35 nm. The electron affinity of C60 is accurately measured to be 2.6835 ± 0.0006 eV. Numerous unexpected vibrational excitations are observed in the photoelectron spectra due to the Jahn-Teller effect in ${\rm C}_{60}^ -$C60− and Hertzberg-Teller vibronic coupling in both ${\rm C}_{60}^ -$C60− and C60. Both the relative intensities of vibrational peaks and their photoelectron angular distributions provide evidence for the vibronic couplings. The observed p-wave-like behavior in the angular distribution of the $0_0^0$000 transition suggests that the electron is detached from an s-type orbital.
Hylleraas-configuration-interaction nonrelativistic energies for the 1S ground states of the beryllium isoelectronic sequence
Authors: Sims James S. , Hagstrom Stanley A.
Published: June 2014

In a previous work, Sims and Hagstrom [“Hylleraas-configuration-interaction study of the 1 1S ground state of neutral beryllium,” Phys. Rev. A 83, 032518 (2011)] reported Hylleraas-configuration-interaction (Hy-CI) method variational calculations for the 1S ground state of neutral beryllium with an estimated accuracy of a tenth of a microhartree. In this work, the calculations have been extended to higher accuracy and, by simple scaling of the orbital exponents, to the entire Be 2 1S isoelectronic sequence. The best nonrelativistic energies for Be, B+, and C++ obtained are −14.6673 5649 269, −24.3488 8446 36, and −36.5348 5236 25 hartree, respectively. Except for Be, all computed nonrelativistic energies are superior to the known reference energies for these states.
Short-time asymptotics of a rigorous path integral for N = 1 supersymmetric quantum mechanics on a Riemannian manifold
Authors: Fine Dana S. , Sawin Stephen
Published: June 2014

Following Feynman's prescription for constructing a path integral representation of the propagator of a quantum theory, a short-time approximation to the propagator for imaginary-time, N = 1 supersymmetric quantum mechanics on a compact, even-dimensional Riemannian manifold is constructed. The path integral is interpreted as the limit of products, determined by a partition of a finite time interval, of this approximate propagator. The limit under refinements of the partition is shown to converge uniformly to the heat kernel for the Laplace-de Rham operator on forms. A version of the steepest descent approximation to the path integral is obtained, and shown to give the expected short-time behavior of the supertrace of the heat kernel.
High Curie temperature BiInO3-PbTiO3 films
Authors: Lee Sun Young , Wang Wei , Trolier-McKinstry Susan
Published: June 2014

High Curie temperature piezoelectric thin films of xBiInO3-(1-x)PbTiO3 (x = 0.10, 0.15, 0.20, and 0.25) were prepared by pulsed laser deposition. It was found that the tetragonality of films decreased with increasing BI content. The dielectric constant and transverse piezoelectric coefficient (e31,f) exhibit the highest values of 665 and −13.6 C/m2 at x = 0.20. Rayleigh analyses were performed to identify the extrinsic contributions to dielectric nonlinearity with different x. The composition with x = 0.20 also exhibits the largest extrinsic contributions to dielectric nonlinearity. The Curie temperature (TC) is increased with increasing x content from 558 to 633 °C; TC at x = 0.20 is about 584 °C.
Flow control of an oblique shock wave reflection with micro-ramp vortex generators: Effects of location and size
Authors: Giepman R. H. M. , Schrijer F. F. J. , van Oudheusden B. W.
Published: June 2014

This study investigates the influences of micro-ramp size and location on its effectiveness as a flow control device for oblique shock wave reflections. The effectiveness is measured in terms of the size of the shock-induced separation bubble and the reflected shock unsteadiness. Particle image velocimetry measurements were carried out on the interaction region and the mixing region between micro-ramp and interaction. The separation bubble is shown to be most sensitive to the momentum flux contained in the lower 43% of the incoming boundary layer. The momentum flux added to this region scales linearly with micro-ramp height and larger micro-ramps are shown to be more effective in stabilizing the interaction. Full boundary layer mixing is attained 5.7δ downstream of the micro-ramp and this forms a lower limit on the required distance between micro-ramp and the start of the interaction region. Typical reductions in the average separated area and the shock unsteadiness of 87% and 51%, respectively, were recorded. Results, however, depend strongly upon the spanwise location, with the micro-ramp being most effective along its centerline.
Relationship between β-relaxation and structural stability of lysozyme: Microscopic insight on thermostabilization mechanism by trehalose from Raman spectroscopy experiments
Authors: Hédoux Alain , Paccou Laurent , Guinet Yannick
Published: June 2014

Raman investigations were carried out in the low-frequency and amide I regions on lysozyme aqueous solutions in absence and presence of trehalose. Raman spectroscopy gives the unique opportunity to analyze the protein and solvent dynamics in the low-frequency range while monitoring the unfolding process by capturing the spectrum of the amide I band. From the analysis of the quasielastic intensity, a dynamic change is firstly observed in a highly hydrated protein, around 70 °C, and interpreted in relation with the denaturation mechanism of the protein. The use of heavy water and partly deuterated trehalose gives clear information on protein–trehalose interactions in the native state of lysozyme (at room temperature) and during the thermal denaturation process of lysozyme. At room temperature, it was found that trehalose is preferentially excluded from the protein surface, and has a main effect on the tetrahedral local order of water molecules corresponding to a stiffening of the H-bond network in the solvent. The consequence is a significant reduction of the amplitude of fast relaxational motions, inducing a less marked dynamic transition shifted toward the high temperatures. Upon heating, interaction between trehalose and lysozyme is detected during the solvent penetration within the protein, i.e., while the native globular state softens into a molten globule (MG) state. Addition of trehalose reduces the protein flexibility in the MG state, improving the structural stability of the protein, and inhibiting the protein aggregation.
Low valency in lanthanides: A theoretical study of NdF and LuF
Authors: Schoendorff George , Wilson Angela K.
Published: June 2014

The ground and low-lying excited state potential energy curves of neodymium monofluoride were calculated using multireference (CASSCF) and single reference (EOM-CR-CCSD(T)) methods. Optimized bond lengths were obtained and accurate bond dissociation energies were computed. The EOM-CR-CCSD(T) method was used to determine the bond dissociation energy of lutetium monofluoride, and it is shown that core correlation is required to produce bond dissociation energies in agreement with experiment.
Global structure of regular tori in a generic 4D symplectic map
Authors: Lange S. , Richter M. , Onken F. , Bäcker A. , Ketzmerick R.
Published: June 2014

For the case of generic 4d symplectic maps with a mixed phase space, we investigate the global organization of regular tori. For this, we compute elliptic 1-tori of two coupled standard maps and display them in a 3d phase-space slice. This visualizes how all regular 2-tori are organized around a skeleton of elliptic 1-tori in the 4d phase space. The 1-tori occur in two types of one-parameter families: (α) Lyapunov families emanating from elliptic-elliptic periodic orbits, which are observed to exist even far away from them and beyond major resonance gaps, and (β) families originating from rank-1 resonances. At resonance gaps of both types of families either (i) periodic orbits exist, similar to the Poincaré-Birkhoff theorem for 2d maps, or (ii) the family may form large bends. In combination, these results allow for describing the hierarchical structure of regular tori in the 4d phase space analogously to the islands-around-islands hierarchy in 2d maps.
Efficient out-coupling and beaming of Tamm optical states via surface plasmon polariton excitation
Authors: Lopez-Garcia M. , Ho Y.-L. D. , Taverne M. P. C. , Chen L.-F. , Murshidy M. M. , Edwards A. P. , Serry M. Y. , Adawi A. M. , Rarity J. G. , Oulton R.
Published: June 2014

We present evidence of optical Tamm states to surface plasmon polariton (SPP) coupling. We experimentally demonstrate that for a Bragg stack with a thin metal layer on the surface, hybrid Tamm-SPP modes may be excited when a grating on the air-metal interface is introduced. Out-coupling via the grating to free space propagation is shown to enhance the transmission as well as the directionality and polarization selection for the transmitted beam. We suggest that this system will be useful on those devices, where a metallic electrical contact as well as beaming and polarization control is needed.
Quantum molecular dynamics simulation of shock-wave experiments in aluminum
Authors: Minakov D. V. , Levashov P. R. , Khishchenko K. V. , Fortov V. E.
Published: June 2014

We present quantum molecular dynamics calculations of principal, porous, and double shock Hugoniots, release isentropes, and sound velocity behind the shock front for aluminum. A comprehensive analysis of available shock-wave data is performed; the agreement and discrepancies of simulation results with measurements are discussed. Special attention is paid to the melting region of aluminum along the principal Hugoniot; the boundaries of the melting zone are estimated using the self-diffusion coefficient. Also, we make a comparison with a high-quality multiphase equation of state for aluminum. Independent semiempirical and first-principle models are very close to each other in caloric variables (pressure, density, particle velocity, etc.) but the equation of state gives higher temperature on the principal Hugoniot and release isentropes than ab initio calculations. Thus, the quantum molecular dynamics method can be used for calibration of semiempirical equations of state in case of lack of experimental data.
Electronic transport properties of inner and outer shells in near ohmic-contacted double-walled carbon nanotube transistors
Authors: Zhang Yuchun , Zhou Liyan , Zhao Shangqian , Wang Wenlong , Wang Enge , Liang Wenjie
Published: June 2014

We investigate electronic transport properties of field-effect transistors based on double-walled carbon nanotubes, of which inner shells are metallic and outer shells are semiconducting. When both shells are turned on, electron-phonon scattering is found to be the dominant phenomenon. On the other hand, when outer semiconducting shells are turned off, a zero-bias anomaly emerges in the dependence of differential conductance on the bias voltage, which is characterized according to the Tomonaga-Luttinger liquid model describing tunneling into one-dimensional materials. We attribute these behaviors to different contact conditions for outer and inner shells of the double-walled carbon nanotubes. A simple model combining Luttinger liquid model for inner metallic shells and electron-phonon scattering in outer semiconducting shells is given here to explain our transport data at different temperatures.
Diffusion and impurity segregation in hydrogen-implanted silicon carbide
Authors: Barcz A. , Kozubal M. , Jakieła R. , Ratajczak J. , Dyczewski J. , Gołaszewska K. , Wojciechowski T. , Celler G. K.
Published: June 2014

Diffusion and segregation behavior of hydrogen and oxygen in silicon carbide subjected to H implantation and subsequent annealing were studied with a number of analytical techniques including Secondary Ion Mass Spectrometry (SIMS), Rutherford backscattering spectrometry in channeling geometry, field emission scanning electron microscopy, optical microscopy, cross-sectional transmission electron microscopy, and atomic force microscopy. H+ implantation was carried out with energies of 200 keV, 500 keV, or 1 MeV to doses of 1 × 1016, 1 × 1017, or 2 × 1017 ion/cm2, and thermal treatment was conducted in flowing argon for 1 to 2 h at temperatures of 740, 780, 1000, or 1100 °C. The process of migration and eventual loss of hydrogen in a point defect regime is postulated to proceed to a large extent through ionized vacancies. This conclusion was derived from the observed substantial difference in H mobilities in n- vs. p-type SiC as the population of ionized vacancies is governed by the Fermi-Dirac statistics, i.e., the position of the Fermi level. For higher doses, a well defined buried planar zone forms in SiC at the maximum of deposited energy, comprising numerous microvoids and platelets that are trapping sites for hydrogen atoms. At a certain temperature, a more or less complete exfoliation of the implanted layer is observed. For a 1 MeV implant heated to 1100 °C in nominally pure argon, SIMS profiling reveals a considerable oxygen peak of 1016 O atoms/cm2 situated at a depth close to that of the peak of the implanted H+. Similarly, 1100 °C annealing of a 200 keV implant induces the formation of a thin oxide (4 nm), located at the interface between the implanted layer and the substrate as evidenced by both SIMS and HRTEM. The measurements were taken on the part of the sample that remained un-exfoliated. In view of a lack of convincing evidence that a hexagonal SiC might contain substantial amounts of oxygen, further investigation is under way to elucidate its presence in the irradiation-damaged films.
A kinematic study of energy barriers for crack formation in graphene tilt boundaries
Authors: Daly Matthew , Veer Singh Chandra
Published: June 2014

Recent experimental studies have observed a surprisingly wide range of strengths in polycrystalline graphene. Previous computational investigations of graphene tilt boundaries have highlighted the role of interfacial topology in determining mechanical properties. However, a rigorous characterization of deformation energy barriers is lacking, which precludes direct comparison to the available experimental data. In the current study, molecular dynamics tensile simulations are performed to quantify kinematic effects on failure initiation in a wide range of graphene tilt boundaries. Specifically, the process of crack formation is investigated to provide a conservative estimate of strength at experimental loading rates. Contrary to previous studies, significant strain rate sensitivity is observed, resulting in reductions of crack formation stresses on the order of 7% to 33%. Energy barriers for crack formation are calculated in the range of 0.58 to 2.07 eV based on an Arrhenius relation that is fit to the collected simulation data. Physically, the magnitude of energy barriers in graphene tilt boundaries is found to be linearly correlated to the pre-stress in the critical bonds. Predictions reported in the present study provide a possible explanation for the wide range of strengths experimentally observed in polycrystalline graphene and greatly improve upon current theoretical estimates.
The importance of spinning speed in fabrication of spin-coated organic thin film transistors: Film morphology and field effect mobility
Authors: Kotsuki Kenji , Tanaka Hiroshige , Obata Seiji , Stauss Sven , Terashima Kazuo , Saiki Koichiro
Published: June 2014

We have investigated the film morphology and the field effect mobility of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) thin films which were formed by spin coating on the SiO2 substrate with solution-processed graphene electrodes. The domain size and the density of aggregates in the C8-BTBT film showed the same dependence on the spinning speed. These competitive two factors (domain size and density of aggregates) give an optimum spinning speed, at which the field effect mobility of C8-BTBT transistor showed a maximum (2.6 cm2/V s). This result indicates the importance of spinning speed in the fabrication of solution processed organic thin film transistors by spin coating.
Direct detection of a transport-blocking trap in a nanoscaled silicon single-electron transistor by radio-frequency reflectometry
Authors: Villis B. J. , Orlov A. O. , Barraud S. , Vinet M. , Sanquer M. , Fay P. , Snider G. , Jehl X.
Published: June 2014

The continuous downscaling of transistors results in nanoscale devices which require fewer and fewer charged carriers for their operation. The ultimate charge controlled device, the single-electron transistor (SET), controls the transfer of individual electrons. It is also the most sensitive electrometer, and as a result the electron transport through it can be dramatically affected by nearby charges. Standard direct-current characterization techniques, however, are often unable to unambiguously detect and resolve the origin of the observed changes in SET behavior arising from changes in the charge state of a capacitively coupled trap. Using a radio-frequency (RF) reflectometry technique, we are able to unequivocally detect this process, in very close agreement with modeling of the trap's occupation probability.
“Long leg” magnetoelectric memory
Authors: Morosov A. I. , Sigov A. S.
Published: June 2014

We propose a concept of magnetoresistive memory with recording function carried by the electric field. The concept stems from the idea of elastic interaction between the layer of ferroelectric-ferroelastic and the ferromagnetic layer with a considerable internal magnetoelastic interaction. In this paper, we consider such features as the arrangement of electrodes, the shape of electric-field-sensitive layer, and limitations on the bit size imposed due to a necessity of being in access of a superparamagnetic limit.
Origin of deep subgap states in amorphous indium gallium zinc oxide: Chemically disordered coordination of oxygen
Authors: Sallis S. , Butler K. T. , Quackenbush N. F. , Williams D. S. , Junda M. , Fischer D. A. , Woicik J. C. , Podraza N. J. , White B. E. , Walsh A. , Piper L. F. J.
Published: June 2014

The origin of the deep subgap states in amorphous indium gallium zinc oxide (a-IGZO), whether intrinsic to the amorphous structure or not, has serious implications for the development of p-type transparent amorphous oxide semiconductors. We report that the deep subgap feature in a-IGZO originates from local variations in the oxygen coordination and not from oxygen vacancies. This is shown by the positive correlation between oxygen composition and subgap intensity as observed with X-ray photoelectron spectroscopy. We also demonstrate that the subgap feature is not intrinsic to the amorphous phase because the deep subgap feature can be removed by low-temperature annealing in a reducing environment. Atomistic calculations of a-IGZO reveal that the subgap state originates from certain oxygen environments associated with the disorder. Specifically, the subgap states originate from oxygen environments with a lower coordination number and/or a larger metal-oxygen separation.
Magnetic property of transition metal-Si atomic line on silicon Σ3 grain boundary: A theoretical study
Authors: Li Yong-Hua , Guo Shu-Kuan , Ma Zhong-Quan , Qu Guo-Hui , Shi Ting-Ting , Gong Xin-Gao , Xia Qin , Wei Su-Huai
Published: June 2014

Using first-principles calculations within density functional theory, we investigate the electronic and magnetic properties of different 3d transition metal-Si atomic lines on silicon Σ3 (112) grain boundary, which can be formed through grain boundary segregation. We find that (i) Fe atoms occupy the substitutional sites at the grain boundary and form an Fe-Si atomic line, but the interaction between the Fe atoms is antiferromagnetic. (ii) The ferromagnetic stability increases with the atomic number of the transition metals and Co-Si atomic line is more stable in the ferromagnetic phase and shows a semimetallic behavior. We suggest that this special TM-Si atomic line formed by thermodynamically favorable transition metal segregation on Si grain boundary could be used in design of spin-dependent quantum devices.
Composition-dependent bonding and hardness of γ-aluminum oxynitride: A first-principles investigation
Authors: Tu Bingtian , Wang Hao , Liu Xiao , Khan Shahzad A. , Wang Weimin , Fu Zhengyi
Published: June 2014

Spinel phase aluminum oxynitride solid solution (γ-alon, with formula of Al(8+x)/3O4−xNx) exists in the narrow Al2O3-rich region of Al2O3-AlN systems. The first-principles calculations were developed to investigate the composition-dependent bonding and hardness of γ-alon. Six supercell model for Al(8+x)/3O4−xNx (x = 0, 0.25, 0.44, 0.63, 0.81, and 1) was constructed to perform our calculations with high accuracy. It was found that the lattice constant increases with increasing composition of nitrogen in γ-alon. The bond lengths of AlIV–O, AlVI–O, AlIV–N, and AlVI–N all increase with the expansion of crystal structure. The well-known Mulliken overlap populations were calculated to estimate the bonding and hardness. As the content of nitrogen substitute increases, the Al–N bonds present more covalent characteristic, while the Al–O bonds present more ionic characteristic. The AlIV–N is the hardest bond in γ-alon. The theoretical hardness of γ-alon could be slightly enhanced from 17.16 GPa to 17.97 GPa by increasing content of nitrogen in full solubility range. The contribution ratio, CHμ, was proposed to quantify the contribution of bonds to hardness of γ-alon. The Al–O bonds are found to contribute more to the hardness. The Al–N bonds are the main influencing factor to enhance the hardness of γ-alon. These calculated results provide the basis for understanding the composition-dependent bonding and hardness of γ-alon.
Biomimetic mechanics behaviors of the strider leg vertically pressing water
Authors: Liu Jianlin , Sun Jing , Mei Yue
Published: June 2014

Water striders capture the amazing feature to walk on water surface, and this phenomenon triggered extensive investigations in the past decades. We model the strider leg as a fiber vertically pressing into water surface and explore some striking mechanics behaviors in this process. First, the meniscus morphology is exactly solved by a numerical scheme. Based upon this solution, a non-dimensional parameter is defined in order to properly characterize the “capillary effect” of the objects with different volumes. The discussion of the buoyant force shows that the apparent contact angle has little impact on the variation of the water-supporting force. Besides this, there is no need for the strider leg to pierce into water, for the pinning of the triple contact line ensures a bigger buoyant force. In addition, the radius of the leg should be in an appropriate range to support the body weight. These analyses may cast light on how to design new-typed miniature aquatic devices.
Ultrathin metal-semiconductor-metal resonator for angle invariant visible band transmission filters
Authors: Lee Kyu-Tae , Seo Sungyong , Yong Lee Jae , Jay Guo L.
Published: June 2014

We present transmission visible wavelength filters based on strong interference behaviors in an ultrathin semiconductor material between two metal layers. The proposed devices were fabricated on 2 cm × 2 cm glass substrate, and the transmission characteristics show good agreement with the design. Due to a significantly reduced light propagation phase change associated with the ultrathin semiconductor layer and the compensation in phase shift of light reflecting from the metal surface, the filters show an angle insensitive performance up to ±70°, thus, addressing one of the key challenges facing the previously reported photonic and plasmonic color filters. This principle, described in this paper, can have potential for diverse applications ranging from color display devices to the image sensors.
Mathematical and numerical model to study two-dimensional free flow isoelectric focusing
Authors: Yoo Kisoo , Shim Jaesool , Liu Jin , Dutta Prashanta
Published: June 2014

Even though isoelectric focusing (IEF) is a very useful technique for sample concentration and separation, it is challenging to extract separated samples for further processing. Moreover, the continuous sample concentration and separation are not possible in the conventional IEF. To overcome these challenges, free flow IEF (FFIEF) is introduced in which a flow field is applied in the direction perpendicular to the applied electric field. In this study, a mathematical model is developed for FFIEF to understand the roles of flow and electric fields for efficient design of microfluidic chip for continuous separation of proteins from an initial well mixed solution. A finite volume based numerical scheme is implemented to simulate two dimensional FFIEF in a microfluidic chip. Simulation results indicate that a pH gradient forms as samples flow downstream and this pH profile agrees well with experimental results validating our model. In addition, our simulation results predict the experimental behavior of pI markers in a FFIEF microchip. This numerical model is used to predict the separation behavior of two proteins (serum albumin and cardiac troponin I) in a two-dimensional straight microchip. The effect of electric field is investigated for continuous separation of proteins. Moreover, a new channel design is presented to increase the separation resolution by introducing cross-stream flow velocity. Numerical results indicate that the separation resolution can be improved by three folds in this new design compare to the conventional straight channel design.
A semiconductor metasurface with multiple functionalities: A polarizing beam splitter with simultaneous focusing ability
Authors: Lee Jun Hyung , Woong Yoon Jae , Jin Jung Myoung , Kyun Hong Jong , Ho Song Seok , Magnusson Robert
Published: June 2014

We propose a semiconductor metasurface that simultaneously performs two independent functions: focusing and polarization filtering. The wavefronts of the reflected and transmitted light distributions are precisely manipulated by spatial parametric variation of a subwavelength thin-film Si grating, which inherently possesses polarization filtering properties. We design a 12-μm-wide metasurface containing only nineteen Si grating ridges. Under a 10-μm-wide unpolarized Gaussian beam incidence at wavelength of 1.55 μm, the resulting device shows promising theoretical performance with high power efficiency exceeding 80% and polarization extinction ratio of ∼10 dB with focal spot diameters near 1–2 μm.
Stabilization of Complexes of Redox-Active Guanidino-Functionalized Aromatic Compounds (GFAs) by Hydrogen-Bonding
Authors: Krämer Christoph , Wild Ute , Hübner Olaf , Neuhäuser Christiane , Kaifer Elisabeth , Himmel Hans-Jörg
Published: June 2014

The guanidino-functionalized 1,2,4,5-tetrakis(N,N′-diisopropylguanidino)benzene could act as a redox-active switch, and reversibly forms hydrogen-bond aggregates upon two-electron oxidation. Herein the influence of hydrogen bonding on the structure and electronic properties of the first transition metal complexes of the neutral and oxidized compound are studied. Reaction with CuCl2 leads by coupled redox- and coordination processes to a dinuclear CuII complex of the dicationic guanidine, in which CuCl2– counterions are locked through strong hydrogen-bonds in positions above and below the C6 ring plane. The electronic situation in the electronic ground and excited states of this complex were analysed by quantum chemical calculations.
Solvent-Free, Microwave-Assisted Conversion of Tosylates into Iodides
Authors: Cao Jia , Perlmutter Patrick
Published: June 2014

A highly efficient method for the conversion of primary tosylates into the corresponding iodides is outlined. The method involves heating a neat mixture of the tosylate and solid sodium iodide in a microwave cavity. Reaction times are short, usually about 60 minutes, delivering high yields. This procedure is especially useful for the in situ generation of volatile primary iodides, and for most of the primary iodides, the crude product is sufficiently pure.
Structure of an antibacterial peptide ATP-binding cassette transporter in a novel outward occluded state
Authors: Choudhury Hassanul G. , Tong Zhen , Mathavan Indran , Li Yanyan , Iwata So , Zirah Séverine , Rebuffat Sylvie , van Veen Hendrik W. , Beis Konstantinos
Published: June 2014

Significance

ATP-binding cassette (ABC) exporters transport substrates by an alternating access mechanism that is driven by ATP binding and hydrolysis. The general mechanism is a motion from an inward to an outward state, with a different intertwining of the half-transporters in both states. In this study we determined the function and crystal structure of the ABC exporter McjD that exports the antibacterial peptide microcin J25. Our structure represents a novel nucleotide-bound, outward-occluded state. It does not possess subunit intertwining and shows a well-defined binding cavity that is closed to all sides, consistent with it being an intermediate between the inward- and outward-facing state. Our structure provides valuable insights in a transition state of an ABC exporter.
The role of psychological detachment and empathy in the relationship between target and perpetrator in workplace bullying situations / El papel del distanciamiento psicológico y la empatía en la relación entre víctima y agresor en situaciones de acoso en el trabajo
Authors: García-Ayala Andrés , Rodríguez-Muñoz Alfredo , Moreno Ynomig , Antino Mirko , Ayllón Elena
Published: June 2014

Although previous research has shown a clear association between being a target and a perpetrator of bullying, there are no available studies exploring possible moderators of this relationship. The aim of this study is to examine the moderating role of psychological detachment and empathy on the relationship between target and perpetrator in workplace bullying situations. The sample was made up of 392 employees from a variety of organizations in the private security sector located in Madrid. Results revealed that psychological detachment and empathic concern moderated the relationship between the target and perpetrator of bullying, such that subjects with high levels of detachment and empathic concern reported lower rates of bullying as a perpetrator. These results are in line with the affect-regulation strategies model.