bluuebunny/crossref_metadata_2025 huggingface dataset:
Locus of Control, Safety Attitudes and Involvement in Hazardous Events in Indian Army Aviators
Authors: Joseph Catherine , Reddy Suhasini , Kashore Sharma Kanwal
Published: June 2013

Locus of control (LOC), safety attitudes, and involvement in hazardous events were studied in 205 Indian Army aviators using a questionnaire-based method. A positive correlation was found between external LOC and involvement in hazardous events. Higher impulsivity and anxiety, and decreased self-confidence, safety orientation, and denial were associated with a greater number of hazardous events. Higher external LOC was associated with higher impulsivity, anxiety, and weather anxiety and with lower self-confidence, safety orientation, and denial. Internal LOC was associated with increased self-confidence, safety orientation, and denial. Hazardous events and self-confidence were higher in those involved in accidents than those not involved in accidents. Future research needs to address whether training can effectively modify LOC and negative attitudes, and whether this would cause a reduction in, and better management of, human errors.
Standard Cognitive Psychological Tests Predict Military Pilot Training Outcomes
Authors: King Raymond E. , Carretta Thomas R. , Retzlaff Paul , Barto Erica , James Ree Malcolm , Teachout Mark S.
Published: June 2013

The predictive validity of scores from two cognitive functioning tests, the Multidimensional Aptitude Battery (MAB) and the MicroCog, was examined for initial pilot training performance. In addition to training completion, several training performance criteria were available for graduates: academic grades, daily flying grades, check ride grades, and class rank. Mean score comparisons and correlations in samples of between 5,582 and 12,924 trainees across the two tests showed small but statistically significant relationships with training performance. For example, after correction for range restriction and dichotomization of the criterion, the MAB full-scale IQ score and the MicroCog General Cognitive Functioning score were correlated .29 and .26 respectively with initial pilot training completion. The results pointed to general cognitive ability as the main predictor of training performance. Comparisons with results from studies involving US Air Force pilot aptitude tests showed lower validities for these cognitive functioning tests. This finding likely occurred because the pilot aptitude tests measure additional factors (e.g., aviation knowledge/experience and psychomotor skills) that are predictive of training success and that are not covered by the cognitive functioning tests.
A metabolomic view of how the human gut microbiota impacts the host metabolome using humanized and gnotobiotic mice
Authors: Marcobal A , Kashyap P C , Nelson T A , Aronov P A , Donia M S , Spormann A , Fischbach M A , Sonnenburg J L
Published: June 2013

Defining the functional status of host-associated microbial ecosystems has proven challenging owing to the vast number of predicted genes within the microbiome and relatively poor understanding of community dynamics and community–host interaction. Metabolomic approaches, in which a large number of small molecule metabolites can be defined in a biological sample, offer a promising avenue to ‘fingerprint’ microbiota functional status. Here, we examined the effects of the human gut microbiota on the fecal and urinary metabolome of a humanized (HUM) mouse using an optimized ultra performance liquid chromatography–mass spectrometry-based method. Differences between HUM and conventional mouse urine and fecal metabolomic profiles support host-specific aspects of the microbiota’s metabolomic contribution, consistent with distinct microbial compositions. Comparison of microbiota composition and metabolome of mice humanized with different human donors revealed that the vast majority of metabolomic features observed in donor samples are produced in the corresponding HUM mice, and individual-specific features suggest ‘personalized’ aspects of functionality can be reconstituted in mice. Feeding the mice a defined, custom diet resulted in modification of the metabolite signatures, illustrating that host diet provides an avenue for altering gut microbiota functionality, which in turn can be monitored via metabolomics. Using a defined model microbiota consisting of one or two species, we show that simplified communities can drive major changes in the host metabolomic profile. Our results demonstrate that metabolomics constitutes a powerful avenue for functional characterization of the intestinal microbiota and its interaction with the host.
Engineering three-dimensional topological insulators in Rashba-type spin-orbit coupled heterostructures
Authors: Das Tanmoy , Balatsky A. V.
Published: June 2013

Topological insulators represent a new class of quantum phase defined by invariant symmetries and spin-orbit coupling that guarantees metallic Dirac excitations at its surface. The discoveries of these states have sparked the hope of realizing non-trivial excitations and novel effects such as a magnetoelectric effect and topological Majorana excitations. Here we develop a theoretical formalism to show that a three-dimensional topological insulator can be designed artificially via stacking bilayers of two-dimensional Fermi gases with opposite Rashba-type spin-orbit coupling on adjacent layers, and with interlayer quantum tunneling. We demonstrate that in the stack of bilayers grown along a (001)-direction, a non-trivial topological phase transition occurs above a critical number of Rashba bilayers. In the topological phase, we find the formation of a single spin-polarized Dirac cone at the "Equation missing"-point. This approach offers an accessible way to design artificial topological insulators in a set up that takes full advantage of the atomic layer deposition approach. This design principle is tunable and also allows us to bypass limitations imposed by bulk crystal geometry.
Estimation of glucose concentration using adaptive calibration curve in different hematocrit levels
Authors: Shin J.‐Y. , Nam H.‐H. , Lee K.‐J.
Published: June 2013

When using a glucose meter for point‐of‐care testing, the hematocrit (HCT) estimation is important to reduce errors associated with the measurement of blood glucose concentration. A high HCT results in lowered blood glucose levels while for a low HCT it is increased from the actual values. Proposed is an HCT estimation method using amperometry and indirectly measuring blood viscosity in a small volume capillary cell of a disposable sensor strip. Depending on the estimated HCT, the glucose concentration is calculated using the adaptive calibration curve. The proposed method shows a glucose value with improved accuracy compared to the single calibration curve method.
Ultimate noise isolation in high‐speed digital systems on packages and printed circuit boards
Authors: Choi J.
Published: June 2013

A novel idea for ultimate noise isolation in high‐speed digital systems on packages and printed circuit boards (PCBs) is presented. Ultimate noise isolation in high‐speed digital systems on packages and PCBs can be achieved using the following concept: ‘a power island surrounded by a plurality of mixed alternating impedance electromagnetic bandgap (AI‐EBG) structures‐based power distribution network’. In this idea, the gap around the power island provides excellent isolation from DC to the first resonant frequency of the parallel plates in packages or in PCBs and mixed AI‐EBG structures provide excellent isolation from around the first resonant frequency to a substantially infinite frequency. This novel structure is designed, fabricated, and measured, which demonstrates ultimate noise isolation capability in high‐speed digital systems on packages and PCBs.
Descendent clipping and filtering for cubic metric reduction in OFDM systems
Authors: Zhu Xiaodong , Hu Haichao , Tang Youxi
Published: June 2013

The cubic metric (CM) is being regarded as a more accurate metric for envelope fluctuations of orthogonal frequency division multiplexing (OFDM) signals than peak‐to‐average power ratio (PAPR). Iterative clipping and filtering (ICF) is a simple and efficient technique for PAPR reduction. However, analysis shows that it cannot achieve sufficient CM reduction due to the difference between the two metrics. Proposed is a new technique called descendent clipping and filtering (DCF) for CM reduction. Unlike ICF, DCF introduces a new parameter termed descent factor to improve its performance. Simulation results show that DCF can achieve better performance with only one iteration than ICF with multiple iterations
Absolute wavelength calibration technique for multiplexing interferometric fibre Bragg grating sensor interrogation systems
Authors: Orr P. , Niewczas P.
Published: June 2013

The advent of multiplexing interferometric schemes for fibre Bragg grating sensor interrogation has enabled the combination of large‐scale multiplexing and high‐resolution measurement. Described is a simple technique to add absolute wavelength measurement capabilities to any passive‐interferometric multiplexer. Through simulation a wavelength accuracy of < 10 pm using common system specifications is demonstrated. The technique allows high‐resolution interferometric interrogation to be applied to many key industrial applications requiring precise knowledge of absolute values, such as static temperature or strain, without trading‐off high interrogation rate or resolution.
Shifting stable operating points of bifurcated IPT systems by time delay perturbation
Authors: Tang C. , Sun Y. , Dai X. , Su Y. , Nguang S.K. , Hu A.P.
Published: June 2013

A time‐delay perturbation (TDP) method is proposed to achieve the shifting of the stable resonant operating points of bifurcated inductive power transfer (IPT) systems. Theoretical analysis and experimental results have shown that the TDP method provides an effective way to shift the system operating point to any targeted stable point by simply specifying the corresponding control parameters.
Ultra‐selective lowpass linear‐phase FIR filter function
Authors: Perić S. Lj. , Antić D.S. , Pavlović V.D. , Nikolić S.S. , Milojković M.T.
Published: June 2013

A new ultra‐selective lowpass finite impulse response (FIR) filter function is proposed. First, a new difference equation with all coefficients equals one, and the general structure of the corresponding linear‐phase lowpass digital filter is given. Then, the high economical realisation with only four adders and without multipliers, for any filter order is presented. The concrete example of the proposed filter, compared to the already existing filters, demonstrates a higher selectivity, lower passband and circuit of lower complexity.
Wide tuning range LC VCO with parallel coupled negative gm cells
Authors: Jung J. , Upadyaya P. , Heo D. , Kim J.‐H. , Kim B.‐S.
Published: June 2013

To minimise phase noise degradation with a wide tuning range, the proposed LC voltage controlled oscillator incorporates parallel coupled negative transconductance (gm) cells. Phase noise for wide tuning range VCOs suffers from degradation of quality factor of tank inductors or tank capacitors due to their parasitic resistance. The proposed parallel coupled negative gm cells provide additional current to compensate for the loss of phase noise. The measured results show a tuning range of 25.4% and a phase noise of − 116.7 dBc/Hz at 1 MHz offset frequency at 5.87 GHz with power consumption of 1.4 mW. The figure‐of‐merit with the fractional tuning range of the VCO was − 199.9 dBc/Hz, which is the best among the latest state‐of‐the‐art wide tuning range CMOS LC VCOs.
Multilayer independently controllable dual‐band bandpass filter using dual‐mode slotted‐patch resonator
Authors: Chen J.‐X. , Shao C. , Shi J. , Bao Z.‐H.
Published: June 2013

Presented is a novel multilayer dual‐mode dual‐band bandpass filter (BPF) using two identical microstrip cross‐slotted patch resonators placed back‐to‐back. The lengths of the slots on the patch resonator are designed to be different, which can be used to control the two degenerate modes individually so as to build two passbands of the proposed BPF. Two separated coupling paths for the two modes can be realised by the etched slits on the common ground plane of the two microstrip resonators. As a result, the coupling coefficients between the two resonators in each passband can be controlled independently. Furthermore, a new source‐load coupling scheme is incorporated in this design to enhance the stopband rejection and then improve the band‐to‐band isolation significantly.
Deterministic construction of girth‐eight (3,L) QC‐LDPC codes from quadratic function
Authors: Zhang Guohua , Sun Rong , Wang Xinmei
Published: June 2013

For any row weight L and any circulant permutation matrix size P > (L − 1)2 + b0(L − 1) (b0 = L − 2 + mod(L,2)), a class of (3,L) quasi‐cyclic (QC) low‐density parity‐check (LDPC) codes is explicitly constructed with girth eight, based on the quadratic function f(x) = x2 + bx and its derivative, where b is either of the two integers {b0, − b0 − 2(L − 2)}. Compared with a similar construction from the so‐called difference sequence, the proposed construction is not only much more simple in concept, but also completely deterministic in the sense that no computer search or computing is required. Simulation results show that the new codes significantly outperform the girth‐eight codes constructed by the earliest‐sequence‐based method.
Broadband Ka‐band rectangular waveguide to substrate integrated waveguide transition
Authors: Głogowski R. , Zürcher J.‐F. , Peixeiro C. , Mosig J.R.
Published: June 2013

A simple right‐angle transition between a rectangular waveguide (RWG) and a substrate integrated waveguide (SIW) is proposed. Two slots etched on the broad wall of the SIW are used to couple the waveguides. To obtain a wide bandwidth of operation the slots have different lengths to create a double resonance behaviour. The proposed component has a simple mechanical configuration with the flange of the standard RWG flush‐mounted to the substrate of the SIW. A sample transition is designed to work in the lower part of the Ka‐band. The experimental results agree well with numerical predictions. The proposed component has 6.6% bandwidth and insertion loss below 0.5 dB.
Observation of spontaneous Raman scattering in hydrogenated amorphous silicon wire waveguide at 1.55 µm
Authors: Tanizawa K. , Suda S. , Sakakibara Y. , Kamei T. , Takei R. , Kawashima H. , Namiki S. , Mori M. , Ishikawa H.
Published: June 2013

Reported is the measurement of spontaneous Raman scattering in a 13 mm‐long hydrogenated amorphous silicon wire waveguide with ultrafast carrier decay time. Broad Raman emission with a peak wavelength of 1.55 µm was observed for a pump wavelength of 1.44 µm. The Raman frequency shift is 14.3 THz, and Raman gain coefficient is estimated to be 0.15 W− 1cm− 1.
On‐chip wavelet denoising system implemented with analogue circuits
Authors: Gurrola‐Navarro M.A. , Carrasco‐Alvarez R. , Medina‐Vazquez A.S. , Espinosa‐Flores‐Verdad G.
Published: June 2013

An adaptation of the hard‐thresholding denoising method for analogue circuits is presented. The proposed approach has been proved with a chip fabricated in 0.5 µm CMOS technology. The system works for signals contaminated with white Gaussian noise in the range 100 kHz to 1.6 MHz. On‐chip measurements demonstrate a noise reduction up to 7 dB.
UWB meshed solar monopole antenna
Authors: Yurduseven O. , Smith D. , Elsdon M.
Published: June 2013

A novel combination of a parametrically optimised UWB meshed circular disc monopole antenna with a polycrystalline silicon (poly‐Si) solar cell is presented and discussed. The results indicate that the fabricated meshed solar monopole antenna operates across the frequency band 2.33–10.8 GHz with an average broadband gain of 4.1 dBi. It is demonstrated that by meshing the monopole pattern an adequate solar efficiency of 13.1% can be achieved.
40 MHz‐BW continuous‐time ΔΣ modulator with capacitive local feedback and current‐sharing OTA
Authors: Xing X. , Gielen G.
Published: June 2013

A 40 MHz‐bandwidth (BW) 12‐bit delta‐sigma modulator (DSM) fabricated in 90 nm CMOS is presented. A noise‐free capacitive local feedback scheme is proposed for noise transfer function complex zeros generation. Moreover, the operational transconductance amplifiers (OTAs) are implemented with a current‐sharing feedforward technique to largely reduce the power and to boost the gain. With a 960 MHz clock frequency and 1.2 V supply, the modulator achieves 74.4 dB dynamic range and 69.7 dB peak signal‐to‐noise and distortion ratio (SNDR). The DSM FoM is 0.22 pJ/conv, which is among the lowest of the published moderate resolution DSMs in this high‐bandwidth range.
Small aperture evanescent‐mode waveguide antenna matched using distributed coupled resonators
Authors: Ludlow P. , Fusco V. , Goussetis G. , Zelenchuk D.E.
Published: June 2013

Presented is a design methodology which permits the application of distributed coupled resonator bandpass filter principles to form wideband small‐aperture evanescent‐mode waveguide antenna designs. This approach permits matching of the complex antenna aperture admittance of an evanescent‐mode open‐ended waveguide to a real impedance generator, and thereby to a coaxial feed probe. A simulated reflection coefficient of < − 10 dB was obtained over a bandwidth of 20%, from 2.0–2.45 GHz, in a 2.58 GHz cutoff waveguide. Dielectric‐filled propagating waveguide and air‐filled evanescent‐mode waveguide sections are used to form the resonators/coupling elements of the antenna's coupled resonator matching sections. Simulated realised gain variation from 3.4–5.0 dBi is observed across the bandwidth. The antenna's maximum aperture dimension is < 0.47 λ0 at the upper operating frequency and so it is suitable for use in a wide angle scanning phased array.
Saturated control of boost DC‐to‐DC power converter
Authors: Guzmán‐Guemez J. , Moreno‐Valenzuela J.
Published: June 2013

A new controller for boost DC‐to‐DC power converters is proposed. The new scheme takes into account that the duty cycle is constrained to physically admissible values. The analysis of the closed‐loop trajectories provides the conclusion that output voltage regulation is achieved in asymptotic form. Theoretical results are supported by using real‐time experiments.
Wideband radar absorbing structure with low density material and load‐bearing MWCNT added composite material
Authors: Choi W.H. , Jang H.K. , Shin J.H. , Song T.H. , Kim J.B. , Lee W.J. , Joo Y.S. , Kim C.‐G.
Published: June 2013

A new design concept of a wideband radar absorbing structure consisting of load‐bearing glass/MWCNT added epoxy composite and having low density/lightweight characteristics for C‐ to X‐band and X‐ to Ku‐band radar is presented. The proposed radar absorbing structures have triple layers which are the low density and light weight layer to reduce the total weight, covering layers to protect the foam layer from humidity absorption, and a load‐bearing layer as the actual structural layer. The proposed designs satisfied −10 dB absorption in the C‐band to X‐band and X‐band to Ku‐band using only two different materials. Moreover, from a practical point of view, since thickness control of absorbing structures is an important factor for the absorbing performance, the proposed structures could minimise fabrication errors (precise thickness controls) by employing multiple layers for wideband absorbing performance.
Discretely tunable optical delay lines using serial and step‐chirped sidewall Bragg gratings in SOI
Authors: Spasojevic M. , Chen L.R.
Published: June 2013

Discretely tunable optical delay lines using serial and step‐chirped sidewall Bragg gratings in SOI are demonstrated. Delays of up to 60 ps (28 ps) in steps of 20 ps (14 ps) spanning bandwidths of 53 nm (33 nm) are obtained for serial (step‐chirped) gratings.
Statistical quality‐of‐service analysis in multiuser diversity system enhanced with queue information
Authors: Kim Taejoon , Lim Jong‐Tae
Published: June 2013

In recent years, the scheduling scheme of exploiting multiuser diversity gain has attracted much attention for the purpose of efficient spectrum utilisation. The authors consider the problem of analysing the quality of service in the scheduler extracting multiuser diversity gain. The authors use not only the channel state information but also the queue information in determining the optimal user to be scheduled. Through queuing analysis, the guaranteed rate, the average delay and the delay‐bound violation probability can be calculated.
Fast codeword selection for limited feedback beamforming multiple‐input–multiple‐output systems using breadth‐first tree search
Authors: Liu Tsung‐Hsien , Chiu Chun‐Ning , Lin Che‐Yu
Published: June 2013

Codebooks with constant modulus entries are being considered for the limited feedback beamforming multiple‐input–multiple‐output (MIMO) system to improve the power amplifier efficiency at the transmitter. Assume that one such codebook is known to both the transmitter and receiver. The receiver must determine a target codeword from this codebook and send its index back to the transmitter. A receiver can be implemented with low cost if fast codeword selection algorithm is executed. In this study, the authors utilise the properties possessed by three such codebooks and propose a novel tree search algorithm for fast codeword selection. Compared with two previously reported codeword selection algorithms, our algorithm is of fixed complexity and does find the target codeword. Furthermore, our algorithm for codeword selection is similar to the tree search for MIMO detection. These two similar tree search algorithms for both codeword selection and MIMO detection can be implemented by the same hardware architecture. A baseband receiver with small chip area for the dual‐mode (the spatial multiplexing and beamforming transmission modes) MIMO system is possible.
Adaptive decision feedback detection with parallel interference cancellation and constellation constraints for multiuser multi‐input–multi‐output systems
Authors: Li Peng , de Lamare Rodrigo C. , Liu Jingjing
Published: June 2013

In this study, a novel low‐complexity adaptive decision feedback (DF) detection with parallel DF (P‐DF) and P‐DF constellation constraints (P‐DFCC) is proposed for multiuser multi‐input–multi‐output (MIMO) systems. The authors propose a constrained constellation map which introduces a number of selected points served as the feedback candidates for interference cancellation. By introducing a reliability checking, a higher degree of freedom is introduced to refine the unreliable estimates. The P‐DFCC is followed by an adaptive receive filter to estimate the transmitted symbol. To reduce the complexity of computing the filters with time‐varying MIMO channels, an adaptive recursive least squares algorithm is employed in the proposed P‐DFCC scheme. An iterative detection and decoding (Turbo) scheme is considered with the proposed P‐DFCC algorithm. Simulations show that the proposed technique has a complexity comparable to the conventional P‐DF detector while it obtains a performance close to the maximum‐likelihood detector at a low to medium signal‐to‐noise ratio range.

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Adaptive and autonomous power‐saving scheme for beyond 3G user equipment
Authors: Liu Enjie , Zhang Jie , Ren Weili
Published: June 2013

Beyond 3G mobile networks will be data service centric. User equipment (UE) stays in the Connected State relatively long while supporting data services, so efficient power‐saving mechanisms for the Connected State are becoming more significant in order to prolong battery life of a handset. Discontinuous reception (DRX) has been a dominant approach for power saving in the Idle State and Connected State. In this study, a novel counter‐driven adaptive DRX (CDA‐DRX) scheme is proposed and analysed. The CDA‐DRX scheme is intended to present a generic and easy‐to‐implement algorithm to adaptively and autonomously adjust DRX cycle to keep up with changing user activity level. The scheme distinguishes itself from all other researches by minimising signalling overhead and easily balancing packet delivery latency and power consumption. Numerical analysis and system simulation showed that this scheme produces a better tuned DRX operation than the ones proposed in literature or suggested in the standards.
Impact and compensation of I/Q imbalance on channel reciprocity of time‐division‐duplexing multiple‐input multiple‐output systems
Authors: Liu Zu‐Jun , Sun De‐Chun , Wang Jie‐Ling , Yi Ke‐Chu
Published: June 2013

Direct‐conversion‐based wireless communication systems suffer from I/Q imbalances in the front‐end analog processing. In this study, the authors investigate the impact of frequency‐independent (FI) I/Q imbalance on the channel reciprocity of time‐division‐duplexing (TDD) multiple‐input multiple‐output (MIMO) systems over frequency flat‐fading channels. Moreover, in order to compensate the channel non‐reciprocity caused by FI I/Q imbalance, the authors propose two pre‐compensation algorithms with and without I/Q imbalance parameters. The performance of the TDD MIMO system under study is evaluated in terms of downlink capacity and bit‐error rate. Simulation results show that the proposed algorithms can effectively mitigate the negative effect of FI I/Q imbalance on the channel reciprocity.
Two‐step interference cancellation scheme in doubly selective channel estimation using superimposed training
Authors: Dou Gaoqi , Liu Hongbo , He Chunquan , Gao Jun
Published: June 2013

Channel estimation for single‐input–multiple‐output systems over doubly selective channel using superimposed training and discrete prolate spheroidal basis expansion model is considered. To remove the interference from unknown data, a two‐step interference cancellation scheme is proposed, where in the first step, a first‐order statistics‐based estimator with cyclic mean removal before transmission is proposed. In this step, only interference components corresponding to cyclic mean of data sequence are removed, which avoids the conflict between total interference elimination and symbol recovery. In the second step, a low complexity iterative interference cancellation scheme is proposed to further improve estimation performance with detected symbols at the receiver's end. Simulation results show that the proposed iterative scheme has the symbol error rate (SER) performance slightly inferior to that of the partially‐data‐dependent approach but with less computational complexity and outperforms the data‐dependent scheme in terms of SER as well as mean‐square error over doubly selective channels.
Effect of nickel doping on the optical property and photocatalytic activity of titanium dioxide nanoparticles
Authors: Paul Susmita , Choudhury Amarjyoti , Bojja Shreedhar
Published: June 2013

Titanium dioxide (TiO2) nanoparticles doped with various amounts of nickel were synthesised via a sol–gel method using titanium isopropoxide and nickel nitrate hexahydrate as precursors. The structural characterisation of the nanoparticles were performed by X‐ray diffraction and transmission electron microscopy. Energy dispersive X‐ray and X‐ray photoelectron spectroscopy analyses confirmed the incorporation of nickel ions into the TiO2 lattice. A remarkable red shift of the absorption edge was achieved by increasing the nickel content. Photoluminescence spectra indicated the quenching of emission intensity on doping. The feasibility of the photocatalytic degradation of bromophenol blue under visible light illumination was studied. The results showed that the catalytic activity is markedly increased by doping nickel ions.
Variable contact surface gripping technique for microsized objects
Authors: Lukman David , Šafarič Riko
Published: June 2013

A special approach is presented regarding an ice‐gripping technique for microsized objects, from the initial idea to the test result. This approach uses water vapour under its triple point for ice forming when gripping or releasing the object. These conditions eliminate liquid water and cause deposition and sublimation to occur. The cooling of sharp apex tips is made possible in this way and eliminates great surface tension of liquid water that makes releasing difficult. The experimental setup and its components are described. It has been shown that this principle is capable of gripping, moving and releasing objects of 40 μm in size, requires no external intervention (such as electron beam‐induced deposition) for releasing the object, is very simple and cost‐effective and is shape and orientation insensitive.
Large‐scale synthesis and characterisation of Ag/Bi2Te3 superlattice nanowires via pulse electrodeposition
Authors: Fu Junli , Shi Jinan , Zhu Min , Liang Yujie , Zhang Guling , Shi Honglong , Li Hua , Zou Bin , Qu Zhen , Jia Ying , Wang Wenzhong
Published: June 2013

Ag/Bi2Te3 superlattice nanowire arrays have been fabricated by pulse electrodeposition using porous anodic aluminium oxide as the template at large‐scale quantity. The nanowire arrays were characterised by X‐ray diffraction, a scanning electron microscope, a transmission electron microscope and high‐resolution transmission electron microscopy (HRTEM). The results indicate that the nanowires are composed of the Bi2Te3 rhombohedral lattice phase and the Ag cubic lattice phase with alternately ordered multi‐segment characters. The feature of dark segments alternated with bright segments can be easily distinguished because of the obvious heterogeneous contrast. The length of each segment varies from 25 to 45 nm. The HRTEM result shows that the composition of one segment is Ag and the neighbouring segment is Bi2Te3.
Fine YAG:Ce3+ nanoparticles synthesised by supercritical hydrothermal reaction
Authors: Qian Shibing , Ma Yongqing , Zan Fenlian , Zou Dan , Dai Zhenxiang , Zheng Ganhong , Li Guang
Published: June 2013

Yttrium aluminium garnet (YAG):Ce3+ nanoparticles have been synthesised by the supercritical hydrothermal method at 390 °C in a series of reaction times of 2, 4, 6, 8, 10 and 12 h, respectively, and characterised by X‐ray diffraction, a scanning electron microscope, (high resolution) transmission electron microscopy and several measurements of fluorescence properties. The single‐phase YAG:Ce3+ can be obtained at much lower temperature (390 °C) by means of the supercritical hydrothermal method with inexpensive raw materials and simple processing conditions than by the conventional solid‐state method and other wet‐chemical methods. The YAG:Ce3+ phosphors synthesised by the supercritical hydrothermal method exhibit more uniform size distribution and stronger emission, compared with those synthesised at the 360 °C below the supercritical point of water. The reaction time also influences the luminescent properties, and the related mechanism is discussed.
Al‐doped ZnS thin films for buffer layers of solar cells prepared by chemical bath deposition
Authors: Liao Jie , Cheng Shuying , Zhou Haifang , Long Bo
Published: June 2013

In this reported study, Al‐doped ZnS (ZnS:Al) thin films were fabricated by chemical bath deposition in alkaline condition along with a stable complexing agent of sodium citrate in ammonia/ammonium chloride buffer solution. Al concentrations were varied from 0 to 10 at.%. The structure and composition of the films were confirmed by X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectra and Raman spectroscopy. The XRD, FTIR and Raman spectra confirmed the existence of ZnS and Al–S bond, which had some effects on the properties of the films. The optical characteristics indicated the changes of the bandgap with the Al‐doping concentrations. The resistivity of the ZnS:Al films with different Al‐doping concentrations after annealing was analysed and the sample with 6 at.% Al concentration had the lowest resistivity of 9.9 × 104 Ω cm.
Rapid microwave‐assisted synthesis of Bi2O3 tubes and photocatalytic properties for antibiotics
Authors: Zhang Gehong , Zhang Xian , Wu Yafan , Shi Weidong , Guan Weisheng
Published: June 2013

Bismuth oxide (Bi2O3) nanotubes have been successfully synthesised via a rapid microwave‐assisted synthetic method for the first time. A wide range of techniques, such as X‐ray diffraction, field emission scanning electron microscopy, X‐ray photoelectron spectroscopy, UV–vis absorption spectroscopy and photoluminescence were applied to characterise the obtained Bi2O3 tubes. Moreover, the photocatalytic properties of Bi2O3 in the degeneration of antibiotics, especially tetracycline (TC) and ciprofloxacin (CIP), were studied. In addition, it was found that it has better photocatalytic effect in degeneration of TC compared with CIP. Therefore this study is necessary and significant for further study of Bi2O3.
Pressure-induced isosymmetric phase transition in sulfamic acid: A combined Raman and x-ray diffraction study
Authors: Li Qian , Li Shourui , Wang Kai , Li Xiaodong , Liu Jing , Liu Bingbing , Zou Guangtian , Zou Bo
Published: June 2013

High-pressure behaviors of hydrogen-bonded molecular crystal, sulfamic acid (NH3+SO3−, SA), have been investigated using Raman spectroscopy and synchrotron X-ray diffraction (XRD) techniques up to the pressure of ∼20 GPa. Under ambient conditions, molecules of SA are arranged in puckered layers and held together by hydrogen bonding and electrostatic interactions. It is proved by the Raman results that SA undergoes the molecular conformation changes in the pressure range 8.1–10.2 GPa. Then between 10.2 and 12.7 GPa, a phase transition is observed in both Raman and XRD patterns. Both the ambient and high-pressure phases of SA crystallize in Pbca symmetry with similar unit-cell dimensions. The mechanism of the phase transition involves relative movements of adjacent hydrogen-bonded molecules, accompanied by the rearrangement of hydrogen bonds and the enhancement of electrostatic interactions.
Instrumentation of broadband frequency domain thermoreflectance for measuring thermal conductivity accumulation functions
Authors: Regner K. T. , Majumdar S. , Malen J. A.
Published: June 2013

This paper describes the instrumentation for broadband frequency domain thermoreflectance (BB-FDTR), a novel, continuous wave laser technique for measuring the thermal conductivity accumulation function. The thermal conductivity accumulation function describes cumulative contributions to the bulk thermal conductivity of a material from energy carriers with different mean free paths. It can be used to map reductions in thermal conductivity in nano-devices, which arise when the dimensions of the device are commensurate to the mean free path of energy carriers. BB-FDTR uses high frequency surface temperature modulation to generate non-diffusive phonon transport realized through a reduction in the perceived thermal conductivity. By controlling the modulation frequency it is possible to reconstruct the thermal conductivity accumulation function. A unique heterodyning technique is used to down-convert the signal, therein improving our signal to noise ratio and enabling results over a broader range of modulation frequencies (200 kHz–200 MHz) and hence mean free paths.
Necessary symmetry conditions for the rotation of light
Authors: Fernandez-Corbaton Ivan , Vidal Xavier , Tischler Nora , Molina-Terriza Gabriel
Published: June 2013

Two conditions on symmetries are identified as necessary for a linear scattering system to be able to rotate the linear polarization of light: Lack of at least one mirror plane of symmetry and electromagnetic duality symmetry. Duality symmetry is equivalent to the conservation of the helicity of light in the same way that rotational symmetry is equivalent to the conservation of angular momentum. When the system is a solution of a single species of particles, the lack of at least one mirror plane of symmetry leads to the familiar requirement of chirality of the individual particle. With respect to helicity preservation, according to the analytical and numerical evidence presented in this paper, the solution preserves helicity if and only if the individual particle itself preserves helicity. However, only in the particular case of forward scattering the helicity preservation condition on the particle is relaxed: We show that the random orientation of the molecules endows the solution with an effective rotational symmetry; at its turn, this leads to helicity preservation in the forward scattering direction independently of any property of the particle. This is not the case for a general scattering direction. These results advance the current understanding of the phenomena of molecular optical activity and provide insight for the design of polarization control devices at the nanoscale.
Spatial mapping of exciton lifetimes in single ZnO nanowires
Authors: Reparaz J. S. , Callsen G. , Wagner M. R. , Güell F. , Morante J. R. , Sotomayor Torres C. M. , Hoffmann A.
Published: June 2013

We investigate the spatial dependence of the exciton lifetimes in single ZnO nanowires. We have found that the free exciton and bound exciton lifetimes exhibit a maximum at the center of nanowires, while they decrease by 30% towards the tips. This dependence is explained by considering the cavity-like properties of the nanowires in combination with the Purcell effect. We show that the lifetime of the bound-excitons scales with the localization energy to the power of 3/2, which validates the model of Rashba and Gurgenishvili at the nanoscale.
Spatially gradated segregation and recovery of circulating tumor cells from peripheral blood of cancer patients
Authors: Lv Peitao , Tang Zhewen , Liang Xingjie , Guo Mingzhou , Han Ray P. S.
Published: June 2013

For cancer patients, the enumeration of rare circulating tumor cells (CTCs) in peripheral blood is a strong prognostic indicator of the severity of the cancer; for the general population, the capture of CTCs is needed for use as a clinical tool for cancer screening, early detection, and treatment assessment. Here, we present a fast, high-purity (∼90%) and high-efficiency (>90%) method for the segregation and undamaged recovery of CTCs using a spatially gradated microfluidic chip. Further, by lysing the red blood cells we achieved not only a significant reduction in the overall processing time but also mitigated the blood clogging problem commonly encountered in microfluidic-based CTC isolation systems. To clinically validate the chip, we employed it to detect and capture CTCs from 10 liver cancer patients. Positive CTC enumeration was observed in all the blood samples, and the readings ranged from a low of 1–2 CTCs (1 patient) to a high of >20 CTCs (2 patients) with the balance having 3–20 CTCs per 3-ml blood sample. The work here indicates that our system can be developed for use in cancer screening, metastatic assessment, and chemotherapeutic response and for pharmacological and genetic evaluation of single CTCs.
Reduced leakage in epitaxial BiFeO3 films following oxygen radio frequency plasma treatment
Authors: Kothari Deepti , Upadhyay Sanjay K. , Jariwala C. , Raole P. M. , Raghavendra Reddy V.
Published: June 2013

Epitaxial BiFeO3 (BFO) films were deposited using pulsed laser deposition method. The prepared films were characterized using x-ray diffraction, x-ray reflectivity, ferroelectric loop tracer, and leakage current measurements before and after oxygen plasma treatment. The leakage current of the films, a crucial parameter in device applications, is observed to be reduced by two orders of magnitude with oxygen plasma treatment at room temperature. P-E hysteresis loops were observed in oxygen plasma treated BFO films. The observed results indicate the usefulness of oxygen radio frequency plasma treatment (RF 13.56 MHz), which is an effective and low temperature processing technique, in such lossy ferroelectric thin films.
Cell membrane thermal gradients induced by electromagnetic fields
Authors: Garner Allen L. , Deminsky Maxim , Bogdan Neculaes V. , Chashihin V. , Knizhnik Andrey , Potapkin Boris
Published: June 2013

While electromagnetic fields induce structural changes in cell membranes, particularly electroporation, much remains to be understood about membrane level temperature gradients. For instance, microwaves induce cell membrane temperature gradients (∇T) and bioeffects with little bulk temperature change. Recent calculations suggest that nanosecond pulsed electric fields (nsPEFs) may also induce such gradients that may additionally impact the electroporation threshold. Here, we analytically and numerically calculate the induced ∇T as a function of pulse duration and pulse repetition rate. We relate ∇T to the thermally induced cell membrane electric field (Em) by assuming the membrane behaves as a thermoelectric such that Em ∼ ∇T. Focusing initially on applying nsPEFs to a uniform membrane, we show that reducing pulse duration and increasing pulse repetition rate (or using higher frequency for alternating current (AC) fields) maximizes the magnitude and duration of ∇T and, concomitantly, Em. The maximum ∇T initially occurs at the interface between the cell membrane and extracellular fluid before becoming uniform across the membrane, potentially enabling initial molecular penetration and subsequent transport across the membrane. These results, which are equally applicable to AC fields, motivate further studies to elucidate thermoelectric behavior in a model membrane system and the coupling of the Em induced by ∇T with that created directly by the applied field.
Electrical endurance of Co/Ni wire for magnetic domain wall motion device
Authors: Fukami S. , Yamanouchi M. , Honjo H. , Kinoshita K. , Tokutome K. , Miura S. , Ikeda S. , Kasai N. , Ohno H.
Published: June 2013

We investigated electrical endurance of perpendicularly magnetized Co/Ni wires, which are a promising candidate material system for current-induced domain wall motion device. Monitoring the wire resistance while applying dc stress is shown to be a promising way to evaluate the electrical breakdown. An electromigration model describes well the observed time-to-failure as a function of temperature and current density. The dc stress current density which leads to 10-yr lifetime with 50% failure at 150 °C was twice as large as the threshold current density for domain wall motion, suggesting that the device with Co/Ni wire is highly durable against electrical stresses.
Study of viscoplastic deformation in porous organosilicate thin films for ultra low-k applications
Authors: Zin Emil H. , Bang W. H. , Todd Ryan E. , King Sean W. , Kim Choong-Un
Published: June 2013

This letter reports experimental observations evidencing the viscoplasticity of porous organosilicate glass thin films under conditions pertinent to their application in advanced low-k/Cu interconnect technology. Specifically, it is found that porous SiCOH thin films exhibit a significant level of viscoplasticity with a rate sensitive to the porosity, the degree of plasma damage, and hydration reaction when tested using a ball indenter at 150–400 °C. The activation energy of the viscosity (1.25–1.45 eV) is measured to be far lower than the bulk glass (>4 eV), suggesting that the viscous flow is affected by the presence of defective bond-network such as Si–OH or Si–H bonds.
Giant enhancement in the magnetostrictive effect of FeGa alloys doped with low levels of terbium
Authors: Jiang Liping , Yang Jiandong , Hao Hongbo , Zhang Guangrui , Wu Shuangxia , Chen Yajie , Obi Ogheneyunume , Fitchorov Trifon , Harris Vincent G.
Published: June 2013

We present the effects of terbium additives upon the microstructure and magnetic properties of Fe83Ga17Tbx alloys (x = 0, 0.2, 0.4, 0.6, and 0.8), prepared by vacuum electric arc-melting and directional solidification techniques. Experiments indicate that small amounts of terbium more than double the saturation magnetostriction of a [110] textured Fe83Ga17 alloy with λ = 72 × 10−6 and lower the magnetostriction saturation field. The pronounced increase in magnetostriction stems from the appearance of [100] texture in polycrystalline alloys. It is verified that [110] and [100] textures are enhanced by the introduction of terbium atoms preferentially residing in a Tb-rich intergranular phase.
Egg quality and age of laying hens: implications for product safety
Authors: Roberts J. R. , Chousalkar Kapil , Samiullah
Published: June 2013

Eggs were collected from commercial caged layer flocks in early, mid, late and very late lay. Eggs were candled and scored for translucency. Cuticle cover was estimated using MST Cuticle Stain and a Konica Minolta hand-held spectrophotometer. Traditional measures of egg quality were determined using specialised equipment. Shell ultrastructural features were scored following plasma ashing of shell samples and viewing under a benchtop scanning electron microscope. Translucency score was significantly higher in late lay than for all other age groups. Shell quality declined with increasing flock age. However, the extent of cuticle cover on the egg shell was not significantly different among flock age groups. The incidence of shell ultrastructural features associated with good quality shells was lower for older flocks and incidence of ultrastructural features associated with poorer quality shells was higher for older flocks. Translucency score had a low correlation with the ultrastructural features of the mammillary layer.
Integrated platform for genome-wide screening and construction of high-density genetic interaction maps in mammalian cells
Authors: Kampmann Martin , Bassik Michael C. , Weissman Jonathan S.
Published: June 2013

Significance

While genomes are being sequenced at an accelerating pace, the elucidation of the function of human genes and their interactions remains a formidable challenge. Genetic interaction maps, which report on how genes work together, provide a powerful tool for systematically defining gene function and pathways. Here we present the complete quantitative framework underlying our recently developed approach for systematic mapping of genetic interactions in mammalian cells and demonstrate its broad potential. Maps obtained in different cell types and treatment conditions dissect context-dependent pathways. Our approach can provide a rational basis for defining combination therapies by targeting genes with strong genetic interactions.
Orienting the reader
Authors: Perkins Marla
Published: June 2013

This study examines strategies that authors can use in texts to keep readers active and accurate participants in the literary conversation and sets forth a taxonomy of those strategies: initiating the literary conversation, anticipating, preventing and correcting possible misunderstandings, and keeping readers engaged as interlocutors. A case study on Burmese Days, by George Orwell, reveals a pattern of interactions between stated information and assumed knowledge. Orwell’s strategies indicate that he assumes that readers are competent, participatory readers (literary conversants), and he uses that assumption to convey locational information. Among these strategies are the following main categories: emphasizing closed-class semantics over open-class implicatures; providing more detail about more important information and less detail about less important information; reviewing the most important information from multiple perspectives; and perhaps most importantly, leaving some information for readers to infer. All of Orwell’s strategies assume the best about readers’ knowledge and willingness to participate and leave room for a pragmatically productive give-and-take that closely resembles conversation.