bluuebunny/crossref_metadata_2025 huggingface dataset:
A self-assembled π-conjugated system as an anti-proliferative agent in prostate cancer cells and a probe for intra-cellular imaging
Authors: Lalitha Krishnamoorthy , Jenifer Preethi , Prasad Y. Siva , Muthusamy Kumarasamy , John George , Nagarajan Subbiah
Published: September 2014

Herein, self-assembled π-conjugated systems derived from renewable resource are reported as a probe for intra-cellular imaging and an anti-proliferative agent for PC3 cells.
Porous ZnO and ZnO–NiO composite nano/microspheres: synthesis, catalytic and biosensor properties
Authors: Yang Ji-Min , Zhang Wei , Liu Qing , Sun Wei-Yin
Published: September 2014

Porous ZnO and ZnO–NiO nanostructures were found to catalyze the decomposition of ammonium perchlorate and ZnO to biosense DNA hybridization.
Immobilization of palladium catalyst on magnetically separable polyurea nanosupport
Authors: Natour Suzana , Abu-Reziq Raed
Published: September 2014

Polyurea nanoparticles doped with magnetic nanoparticles were readily prepared via oil-in-oil nanoemulsification technique and utilized for supporting palladium catalyst.
Molecular mechanism of action of K(D)PT as an IL-1RI antagonist for the treatment of rhinitis
Authors: Li Chanjuan , Ge Hu , Cui Lujia , Li Yali , Cheng Bao , Zhang Guodong , Zhang Ziying , Qi Hao , Ruan Yan , Gu Qiong , Xu Jun
Published: September 2014

K(D)PT curing allergic rhinitis through keeping IL-1RI in close status.
Membrane-free electroextraction using an aqueous two-phase system
Authors: Campos C. D. M. , Park J. K. , Neužil P. , da Silva J. A. F. , Manz A.
Published: September 2014

We present a method of continuous electroextraction of amino acids using aqueous two phase system in a microchip. The separations occur due to differences in electrophoretic mobility and solvent affinity. The results suggest the possibility of high levels of purification by controlling the electric field across the liquid barrier.
1D nanofiber composites of perylene diimides for visible-light-driven hydrogen evolution from water
Authors: Chen Shuai , Jacobs Daniel L. , Xu Jingkun , Li Yingxuan , Wang Chuanyi , Zang Ling
Published: September 2014

Self-assembled 1D nanofibers of donor–accepter type perylene diimides have been used for photocatalytic H2production from water-splitting under visible-light irradiation.
Bottom-up approach to engineer a molybdenum-doped covalent-organic framework catalyst for selective oxidation reaction
Authors: Zhang Weijie , Jiang Pingping , Wang Ying , Zhang Jian , Gao Yongxue , Zhang Pingbo
Published: September 2014

We synthesized a readily accessible molybdenum-doped covalent-organic framework catalyst (Mo-COF) linked by a hydrazine linkage via a facile two-step bottom-up approach. This Mo-COF catalyst as an open nanochannel-reactor showed promising catalytic properties for the selective oxidation reaction.
Tuning nanoscale morphology using mixed solvents and solvent vapor treatment for high performance polymer solar cells
Authors: Wang Dun , Zhang Fujun , Li Lingliang , Yu Jiangsheng , Wang Jian , An Qiaoshi , Tang Weihua
Published: September 2014

A series of high performance polymer solar cells (PSCs) were fabricated with poly[(4,8-bis-(2-ethylhexyloxy)-benzo[1,2-b:4,5-b′](dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno [3,4-b]thiophene)-2,6-diyl] (PBDTTT-EFT) as the donor and with [6,6]phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor.
Delivery of mirror image polypeptides into cells
Authors: Rabideau Amy E. , Liao Xiaoli , Pentelute Bradley L.
Published: September 2014

Mirror image peptides have unique stability and immunogenic properties in mammals, making them attractive agents to investigate.
A sialic acid-targeted near-infrared theranostic for signal activation based intraoperative tumor ablation
Authors: Wu Xuanjun , Yu Mingzhu , Lin Bijuan , Xing Hongjie , Han Jiahuai , Han Shoufa
Published: September 2014

A sialic acid-targeted near-infrared profluorophore with pH-responsive fluorescence and photothermal properties was developed for fluorescence-guided staging and photothermal therapy of viable tumors exposed during surgery.
Controlled gelation of poly(3-alkylthiophene)s in bulk and in thin-films using low volatility solvent/poor-solvent mixtures
Authors: Newbloom Gregory M. , de la Iglesia Pablo , Pozzo Lilo D.
Published: September 2014

Low volatility solvent/non-solvent mixtures were utilized to engineer the structure of poly(3-alkylthiophene) (P3AT) organogels.
Controllable synthesis of porous TiO2with a hierarchical nanostructure for efficient photocatalytic hydrogen evolution
Authors: Wang Lin , Nie Zhongyuan , Cao Chuanbao , Ji Muwei , Zhou Li , Feng Xiao
Published: September 2014

A one-pot hydrothermal method was used to fabricate porous TiO2hierarchical microspheres with controllable size of nanorods building units, based on controlling the hydrolysis rate of the precursor and the aggregation of surfactant.
Carbon embedded α-MnO2@graphene nanosheet composite: a bifunctional catalyst for high performance lithium oxygen batteries
Authors: Cao Yong , Zheng Ming-sen , Cai Senrong , Lin Xiaodong , Yang Cheng , Hu Weiqiang , Dong Quan-feng
Published: September 2014

Carbon is essential for the oxygen electrode in non-aqueous lithium–oxygen (Li–O2) batteries for improving the electron conductivity of the electrode.
A highly efficient (>6%) Cd1−xMnxSe quantum dot sensitized solar cell
Authors: Tian Jianjun , Lv Lili , Fei Chengbin , Wang Yajie , Liu Xiaoguang , Cao Guozhong
Published: September 2014

The power conversion efficiency of CdS/CdSe sensitized solar cells is increased to 6.33% by doping Mn2+ into the CdSe quantum dot.
Luminescence switch of Mn-Doped ZnAl2O4 powder with temperature
Authors: Cornu L. , Duttine M. , Gaudon M. , Jubera V.
Published: September 2014

Mn-doped ZnAl2O4 can show a red to green luminescence switch with thermal treatment and is a potential candidate for thermal sensing pigments.
Triple CoII, III, IV charge ordering and spin states in modular cobaltites: a systematization through experimental and virtual compounds
Authors: David R. , Kabbour H. , Bordet P. , Pelloquin D. , Leynaud O. , Trentesaux M. , Mentré O.
Published: September 2014

In the series of modular compounds [BanCo2+nO3n+2][BaCo6O9], charge segregation and rare triple charge ordering occur.
A systematic study of the structure–property relationship of a series of nonlinear optical (NLO) julolidinyl-based chromophores with a thieno[3,2-b]thiophene moiety
Authors: Zhang Airui , Xiao Hongyan , Cong Shengyu , Zhang Maolin , Zhang Hua , Bo Shuhui , Wang Qi , Zhen Zhen , Liu Xinhou
Published: September 2014

A series of NLO chromophores a–d bearing thieno[3,2-b]thiophene (TT) as the conjugated bridge or the lateral moiety have been synthesized and investigated.
Memory‐efficient quasi‐cyclic spatially coupled low‐density parity‐check and repeat‐accumulate codes
Authors: Chandrasetty Vikram A. , Johnson Sarah J. , Lechner Gottfried
Published: September 2014

The authors propose the construction of spatially coupled low‐density parity‐check (SC‐LDPC) codes using a periodic time‐variant quasi‐cyclic (QC) algorithm. The QC‐based approach is optimised to obtain memory efficiency in storing the parity‐check matrix in the decoders. A hardware model of the parity‐check storage units has been designed for a Xilinx field‐programmable gate array (FPGA), to compare the logic and memory requirements for various approaches. It is shown that the proposed QC SC‐LDPC code (with optimisation) can be stored with reasonable logic resources and without the need of block memory in the FPGA. In addition, a significant improvement in the processing speed is also achieved. This study also proposes a new QC algorithm for constructing spatially coupled repeat‐accumulate (SC‐RA) codes. The proposed construction reduces the implementation complexity of the encoder and subsequently saves significant computational resources required for storing and accessing the circulants in the decoder. The performance of the proposed code is also compared with the standard RA codes through simulations.
Robust adaptive attitude synchronisation of rigid body networks on SO (3)
Authors: Fadakar Iman , Fidan Barış , Huissoon Jan
Published: September 2014

In this study, the authors consider the robust adaptive attitude synchronisation problem for a network of rigid body agents using a modified version of the error function, which is recently introduced for constructing the attitude errors on SO (3). These attitude error vectors are particularly useful for networks with large initial attitude difference. They focus on devising an adaptive geometric approach to cope with situations where the inertia matrices are not available for measurement. The Frobenious norm is used as a measure for the difference between the actual values of moments of inertias and their estimated values, to construct the individual adaptive laws of agents. Compared to the previous methods for synchronisation on SO (3) such as those using quaternions, the authors' approach based on the introduced modified error function enables us to avoid any ambiguity for attitude representation. Finally, they study the robustness of the synchronisation task in the presence of external disturbances and unmodelled dynamics and propose a method to attenuate such effects. Simulation results illustrate the effectiveness of the proposed approach.
Tuning of reset proportional integral compensators with a variable reset ratio and reset band
Authors: Baños Alfonso , Davó Miguel A.
Published: September 2014

The PI+CI compensator, given by the parallel connection of a proportional integral (PI) compensator and a Clegg integrator (CI), has been shown to be effective in a number of practical applications, overcoming fundamental limitations of PI compensation. Two key design aspects of PI+CI compensation is the use of the resetting law (zero crossing/reset band) and a (constant/variable) reset ratio; these two design factors have been previously used in control practice, but using heuristic design methods. This work develops a systematic design method for the tuning of reset PI compensators, specifically for first‐ and second‐order plants, obtaining in both cases simple tuning rules. In addition, several detailed examples are developed; therefore, a detailed analysis of cost of feedback and robustness again parametric uncertainty is also given. Finally, an experiment of pH In‐Line control is made to show the advantages of the proposed tuning rule.
Adaptive control for cooperative linear output regulation of heterogeneous multi‐agent systems with periodic switching topology
Authors: Li Shaobao , Feng Gang , Wang Juan , Luo Xiaoyuan , Guan Xinping
Published: September 2014

This study investigates the cooperative linear output regulation problem of heterogeneous multi‐agent systems with periodic switching topologies. A novel distributed adaptive control law is presented based on dynamic state feedback with the feedback gain independent of the Laplacian matrix of the underlying system communication topology. It is shown that the cooperative output regulation problem can be solved under a necessary and sufficient condition. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed control law.
Distributed aperiodic model predictive control for multi‐agent systems
Authors: Hashimoto Kazumune , Adachi Shuichi , Dimarogonas Dimos V.
Published: September 2014

In this study, the authors propose an aperiodic formulation of model predictive control for distributed agents with additive bounded disturbances. In the proposed method, each agent solves an optimal control problem only when certain control performances cannot be guaranteed according to certain triggering rules. This could lead to the reduction of energy consumption and the alleviation of over usage of communication resources. The triggering rules are derived for both event‐triggered and self‐triggered formulation. The authors proposed method is also verified through a simulation example.
Robust model predictive control of uncertain fractional systems: a thermal application
Authors: Rhouma Aymen , Bouani Faouzi
Published: September 2014

In this study, a robust model predictive control of fractional‐order systems with real uncertain parameters is presented. The Grünwald–Letnikov's method is used as an internal model to predict the plant future dynamic behaviour. This method consists in replacing the non‐integer derivation operator of the adopted system representation by a discrete approximation. Therefore a robust fractional model predictive control is developed based on an uncertain fractional model. Moreover, the output deviation approach is adopted to design the j ‐step ahead output predictor, and the corresponding control law is obtained by the resolution of a min–max optimisation problem that takes into account the uncertainties of the fractional‐order model parameters and under input constraints. The efficiency and the performances of the proposed predictive controller are illustrated with practical results of a thermal system.
Synthesis of linearly polarised patterns of conical arrays by the method of least square
Authors: Orazi Homayoon , Soleimani Hadi , Azadkhah Reza
Published: September 2014

Method of least squares is employed for pattern synthesis of non‐uniform conical arrays using Euler rotation of coordinate axes. Design specifications involve beam‐width of main‐lobe, side‐lobe and cross‐polarisation levels. This method is effective for conformal arrays, because pattern multiplication is not applicable for them. Constructed error function depends on element spacing and current excitations (amplitudes and phases of input currents). Combination of conjugate gradient and genetic algorithms is used for its miniaturisation to determine element spacing and excitations. Recent literature on non‐uniform arrays mostly deals with non‐uniform excitations with complicated input networks. The non‐uniformly spaced arrays will realise any specification obtained by non‐uniform excitations. Two examples of non‐uniform current excitations are presented. First example leads to reduction of side‐lobe level (SLL) from 12 to 20 dB. Second example deals with different upper and lower SLLs. Third example treats non‐uniform spacing, which results in the reduction of SLL from 12 to 18 dB. Fourth example synthesises both non‐uniform spacing and unequal excitations, which provides the SLL reduction from 12 to 25 dB, besides the reduction of cross‐polarisation level from 12 to 25 dB, compared with Qing‐ Qjang et al. 2011, which decreased SLL by only 8 dB.
Polylactic acid/polyethylene glycol blend fibres prepared via melt electrospinning: effect of polyethylene glycol content
Authors: Nazari Tayebe , Garmabi Hamid
Published: September 2014

Polylactic acid (PLA) was blended with polyethylene glycol (PEG) and spun via a melt‐electrospinning system. The effect of PEG content on the PLA melt and the thermal behaviour of the blend was studied using dynamic rheometry and differential scanning calorimetry, respectively. By fitting a rheological model, parameters such as zero‐shear viscosity and the relaxation time of polymer chains were obtained. A substantial reduction of zero‐shear viscosity and relaxation time by increasing the PEG content from 0 to 30 wt% was observed. Crystallisation peaks shifted to lower temperatures and the crystallinity level increased in PLA/PEG blends against PEG concentration. The results revealed enhanced polymer chain mobility because of the plasticising effect of PEG. Continuous microfibres were obtained by electrospinning of PLA/PEG blends. While neat PLA was not spinnable at the spinning temperature of 200°C, PLA/PEG blends were easily spun and the lowest fibre diameters of 3–6 μm were achieved with 30% PEG loading, at an applied voltage of 70 kV.
Dynamical glucometry: Use of multiscale entropy analysis in diabetes
Authors: Costa Madalena D. , Henriques Teresa , Munshi Medha N. , Segal Alissa R. , Goldberger Ary L.
Published: September 2014

Diabetes mellitus (DM) is one of the world's most prevalent medical conditions. Contemporary management focuses on lowering mean blood glucose values toward a normal range, but largely ignores the dynamics of glucose fluctuations. We probed analyte time series obtained from continuous glucose monitor (CGM) sensors. We show that the fluctuations in CGM values sampled every 5 min are not uncorrelated noise. Next, using multiscale entropy analysis, we quantified the complexity of the temporal structure of the CGM time series from a group of elderly subjects with type 2 DM and age-matched controls. We further probed the structure of these CGM time series using detrended fluctuation analysis. Our findings indicate that the dynamics of glucose fluctuations from control subjects are more complex than those of subjects with type 2 DM over time scales ranging from about 5 min to 5 h. These findings support consideration of a new framework, dynamical glucometry, to guide mechanistic research and to help assess and compare therapeutic interventions, which should enhance complexity of glucose fluctuations and not just lower mean and variance of blood glucose levels.
Multi-objective optimization of airfoil shape for efficiency improvement and noise reduction in small wind turbines
Authors: Sanaye Sepehr , Hassanzadeh Arash
Published: September 2014

The power output of a wind turbine depends on the aerodynamic and geometrical characteristic of its airfoils, and therefore, the proper airfoil design for wind turbine blades is highly important. Furthermore, due to the usage of small wind turbines within city limits, the emitted noise is also a major issue. In the present work, “XFoil” and “NAFNoise” programs were used for flow analysis around blade cross sections (airfoils) and predicting the corresponding noise emission, respectively. Multi-objective optimization was carried out for maximizing the airfoil lift-to-drag ratio (CL/CD) and minimizing the sound pressure level. With two above objective functions and by defining decision variables along with introducing physical and engineering constraints, genetic algorithm method was applied for optimization process. Moreover, ‘Fuzzy Bellman-Zadeh’ decision-making method was applied for selecting final optimal point from Pareto front. The results of this new method of airfoil shape analysis at various wind velocities showed about 26% average increase in CL/CD and 1.11% average decrease in noise emission in comparison with that for typical highly used S822 airfoil in small wind turbines.
The jet in crossflow
Authors: Karagozian Ann R.
Published: September 2014

The jet in crossflow, or transverse jet, is a flowfield that has relevance to a wide range of energy and propulsion systems. Over the years, our group's studies on this canonical flowfield have focused on the dynamics of the vorticity associated with equidensity and variable density jets in crossflow, including the stability characteristics of the jet's upstream shear layer, as a means of explaining jet response to altered types of excitation. The jet's upstream shear layer is demonstrated to exhibit convectively unstable behavior at high jet-to-crossflow momentum flux ratios, transitioning to absolutely unstable behavior at low momentum flux and/or density ratios, with attendant differences in shear layer vorticity evolution and rollup. These differences in stability characteristics are shown to have a significant effect on how one optimally employs external excitation to control jet penetration and spread, depending on the flow regime and specific engineering application. Yet recent unexpected observations on altered transverse jet structure under different flow conditions introduce a host of unanswered questions, primarily but not exclusively associated with the nature of molecular mixing, that make this canonical flowfield one that is of great interest for more extensive exploration.
Light-driven electron transport through a molecular junction based on cross-conjugated systems
Authors: Hsu Liang-Yan , Xie Dan , Rabitz Herschel
Published: September 2014

This work explores light-driven electron transport through cross-conjugated molecules with different numbers of alkenyl groups. In the framework of coherent quantum transport, the analysis uses single-particle Green's functions together with non-Hermitian Floquet theory. With realistic parameters stemming from spectroscopy, the simulations show that measurable current (∼10−11 A) caused by photon-assisted tunneling should be observed in a weak driving field (∼2 × 105 V/cm). Current-field intensity characteristics give one-photon and two-photon field amplitude power laws. The gap between the molecular orbital and the Fermi level of the electrodes is revealed by current-field frequency characteristics. Due to generalized parity symmetry, the cross-conjugated molecules with odd and even numbers of alkenyl groups exhibit completely different current-polarization characteristics, which may provide an advantageous feature in nanoelectronic applications.
Simulation of resonance hyper-Rayleigh scattering of molecules and metal clusters using a time-dependent density functional theory approach
Authors: Hu Zhongwei , Autschbach Jochen , Jensen Lasse
Published: September 2014

Resonance hyper-Rayleigh scattering (HRS) of molecules and metal clusters have been simulated based on a time-dependent density functional theory approach. The resonance first-order hyperpolarizability (β) is obtained by implementing damped quadratic response theory using the (2n + 1) rule. To test this implementation, the prototypical dipolar molecule para-nitroaniline (p-NA) and the octupolar molecule crystal violet are used as benchmark systems. Moreover, small silver clusters \documentclass[12pt]{minimal}\begin{document}$\rm {Ag_8}$\end{document} Ag 8 and \documentclass[12pt]{minimal}\begin{document}$\rm {Ag_{20}}$\end{document} Ag 20 are tested with a focus on determining the two-photon resonant enhancement arising from the strong metal transition. Our results show that, on a per atom basis, the small silver clusters possess two-photon enhanced HRS comparable to that of larger nanoparticles. This finding indicates the potential interest of using small metal clusters for designing new nonlinear optical materials.
Geometry optimization for micro-pressure sensor considering dynamic interference
Authors: Yu Zhongliang , Zhao Yulong , Li Lili , Tian Bian , Li Cun
Published: September 2014

Presented is the geometry optimization for piezoresistive absolute micro-pressure sensor. A figure of merit called the performance factor (PF) is defined as a quantitative index to describe the comprehensive performances of a sensor including sensitivity, resonant frequency, and acceleration interference. Three geometries are proposed through introducing islands and sensitive beams into typical flat diaphragm. The stress distributions of sensitive elements are analyzed by finite element method. Multivariate fittings based on ANSYS simulation results are performed to establish the equations about surface stress, deflection, and resonant frequency. Optimization by MATLAB is carried out to determine the dimensions of the geometries. Convex corner undercutting is evaluated. Each PF of the three geometries with the determined dimensions is calculated and compared. Silicon bulk micromachining is utilized to fabricate the prototypes of the sensors. The outputs of the sensors under both static and dynamic conditions are tested. Experimental results demonstrate the rationality of the defined performance factor and reveal that the geometry with quad islands presents the highest PF of 210.947 Hz1/4. The favorable overall performances enable the sensor more suitable for altimetry.
Dissociation and recombination of D2 on Cu(111): Ab initio molecular dynamics calculations and improved analysis of desorption experiments
Authors: Nattino Francesco , Genova Alessandro , Guijt Marieke , Muzas Alberto S. , Díaz Cristina , Auerbach Daniel J. , Kroes Geert-Jan
Published: September 2014

Obtaining quantitative agreement between theory and experiment for dissociative adsorption of hydrogen on and associative desorption of hydrogen from Cu(111) remains challenging. Particularly troubling is the fact that theory gives values for the high energy limit to the dissociative adsorption probability that is as much as two times larger than experiment. In the present work we approach this discrepancy in three ways. First, we carry out a new analysis of the raw experimental data for D2 associatively desorbing from Cu(111). We also perform new ab initio molecular dynamics (AIMD) calculations that include effects of surface atom motion. Finally, we simulate time-of-flight (TOF) spectra from the theoretical reaction probability curves and we directly compare them to the raw experimental data. The results show that the use of more flexible functional forms for fitting the raw TOF spectra gives fits that are in slightly better agreement with the raw data and in considerably better agreement with theory, even though the theoretical reaction probabilities still achieve higher values at high energies. The mean absolute error (MAE) for the energy E0 at which the reaction probability equals half the experimental saturation value is now lower than 1 kcal/mol, the limit that defines chemical accuracy, while a MAE of 1.5 kcal/mol was previously obtained. The new AIMD results are only slightly different from the previous static surface results and in slightly better agreement with experiment.
Triply differential (e,2e) studies of phenol
Authors: da Silva G. B. , Neves R. F. C. , Chiari L. , Jones D. B. , Ali E. , Madison D. H. , Ning C. G. , Nixon K. L. , Lopes M. C. A. , Brunger M. J.
Published: September 2014

We have measured (e,2e) triple differential cross sections (TDCS) for the electron-impact ionisation of phenol with coplanar asymmetrical kinematics for an incident electron energy of 250 eV. Experimental measurements of the angular distribution of the slow outgoing electrons at 20 eV are obtained when the incident electron scatters through angles of −5°, −10°, and −15°, respectively. The TDCS data are compared with calculations performed within the molecular 3-body distorted wave model. In this case, a mixed level of agreement, that was dependent on the kinematical condition being probed, was observed between the theoretical and experimental results in the binary peak region. The experimental intensity of the recoil features under all kinematical conditions was relatively small, but was still largely underestimated by the theoretical calculations.
Real-time magnetic nanothermometry: The use of magnetization of magnetic nanoparticles assessed under low frequency triangle-wave magnetic fields
Authors: Zhong Jing , Liu Wenzhong , Jiang Ling , Yang Ming , Morais Paulo Cesar
Published: September 2014

In this study, we propose and demonstrate the usefulness of employing time-varying magnetization of a magnetic nanoparticle (MNP) based sample, induced by low frequency (f = 25 Hz) triangular-wave magnetic field, to achieve the approach of real-time recording of magnetization curve, which allows precise and noninvasive temperature probing with real-time performance. Moreover, the present report introduces the design and performed the test of a detection system for accurate and real-time recording of the magnetization curve of MNP-based samples. We found that by employing the magnetization curve of a magnetic fluid sample containing magnetite nanoparticles of about 30 nm in diameter the accuracy of the temperature probing is about 0.32 K (0.1% relative accuracy), with response time of 1 s. Furthermore, an increase in response time from 1 to 8 s improves the accuracy of temperature probing from 0.32 to 0.20 K. Finally, we envisage that breakthroughs in clinical hyperthermia, targeted drug delivery and basic cell research can be accomplished while using the approach reported in this study.
A spatial sampling based 13.3 Gs/s sample-and-hold circuit
Authors: Sun Jiwei , Wang Haibo , Wang Pingshan
Published: September 2014

This paper presents a high-speed sample-and-hold circuit (SHC) for very fast signal analysis. Spatial sampling techniques are exploited with CMOS transmission lines in a 0.13 μm standard CMOS process. The SHC includes on chip coplanar waveguides for signal and clock pulse transmission, a clock pulse generator, and three elementary samplers periodically (L = 7.2 mm) placed along the signal propagation line. The SHC samples at 13.3 Gs/s. The circuit occupies an area of 1660 μm × 820 μm and consumes ∼6 mW at a supply voltage of 1.2 V. The obtained input bandwidth is ∼11.5 GHz.
Interlayer exchange coupling in [Pt/Co]n/MgO/[Co/Pt]2 perpendicular magnetic tunnel junctions
Authors: Li Lei , Han Dong , Lei Wenguang , Liu Zhongyuan , Zhang Fang , Mao Xiaonan , Wang Pengwei , Hou Hongmiao
Published: September 2014

In this paper, we present further study on the interlayer exchange coupling of [Pt/Co]n/MgO/[Co/Pt]2 perpendicular magnetic tunnel junctions. Antiferromagnetic interlayer couplings in [Pt/Co]n/MgO/[Co/Pt]2 are observed. The strength of antiferromagnetic coupling oscillates irregularly with the repetition number n, that may be related to the Ruderman-Kittel-Kasuya-Yosida (RKKY)-type ferromagnetic interlayer coupling existing in the [Pt/Co]n hard layer. The interlayer coupling of [Pt/Co]9/MgO(22 Å)/[Co/Pt]2 magnetic tunnel junction reaches a maximum at 200 K, and decreases gradually with increasing temperature. This thermal behavior of interlayer coupling may be related to the enhanced perpendicular magnetic anisotropy of hard layer with decreasing temperature.
A mirror for lab-based quasi-monochromatic parallel x-rays
Authors: Nguyen Thanhhai , Lu Xun , Lee Chang Jun , Jung Jin-Ho , Jin Gye-Hwan , Kim Sung Youb , Jeon Insu
Published: September 2014

A multilayered parabolic mirror with six W/Al bilayers was designed and fabricated to generate monochromatic parallel x-rays using a lab-based x-ray source. Using this mirror, curved bright bands were obtained in x-ray images as reflected x-rays. The parallelism of the reflected x-rays was investigated using the shape of the bands. The intensity and monochromatic characteristics of the reflected x-rays were evaluated through measurements of the x-ray spectra in the band. High intensity, nearly monochromatic, and parallel x-rays, which can be used for high resolution x-ray microscopes and local radiation therapy systems, were obtained.
Cylindrical Taylor states conserving total absolute magnetic helicity
Authors: Low B. C. , Fang F.
Published: September 2014

The Taylor state of a three-dimensional (3D) magnetic field in an upright cylindrical domain V is derived from first principles as an extremum of the total magnetic energy subject to a conserved, total absolute helicity Habs. This new helicity [Low, Phys. Plasmas 18, 052901 (2011)] is distinct from the well known classical total helicity and relative total helicity in common use to describe wholly-contained and anchored fields, respectively. A given field B, tangential along the cylindrical side of V, may be represented as a unique linear superposition of two flux systems, an axially extended system along V and a strictly transverse system carrying information on field-circulation. This specialized Chandrasekhar-Kendall representation defines Habs and permits a neat formulation of the boundary-value problem (BVP) for the Taylor state as a constant-α force-free field, treating 3D wholly-contained and anchored fields on the same conceptual basis. In this formulation, the governing equation is a scalar integro-partial differential equation (PDE). A family of series solutions for an anchored field is presented as an illustration of this class of BVPs. Past treatments of the constant-α field in 3D cylindrical geometry are based on a scalar Helmholtz PDE as the governing equation, with issues of inconsistency in the published field solutions discussed over time in the journal literature. The constant-α force-free equation reduces to a scalar Helmholtz PDE only as special cases of the 3D integro-PDE derived here. In contrast, the constant-α force-free equation and the scalar Helmholtz PDE are absolutely equivalent in the spherical domain as discussed in Appendix. This theoretical study is motivated by the investigation of the Sun's corona but the results are also relevant to laboratory plasmas.
The analysis and compensation of cortical thickness effect on ultrasonic backscatter signals in cancellous bone
Authors: Liu Chengcheng , Ta Dean , Hu Bo , Le Lawrence H. , Wang Weiqi
Published: September 2014

To determine the influence of the overlying cortical shell on ultrasonic backscatter signal in cancellous bone, ultrasonic backscatter simulations were carried out by a three dimensional finite difference time domain method. The simulated signals were obtained for various cortical thickness (CTh) and three central frequencies (1, 2.25, and 3.5 MHz). The integrated reflection coefficient (IRC), integrated transmission coefficient, and apparent integrated backscatter (AIB) were calculated from the signals. The results showed that the IRC oscillated with amplitudes decreasing with increasing CTh and the amplitudes diminished gradually when CTh was over 2.18 mm. The AIB fluctuated and decreased as the CTh increased (R = −0.72 ∼ −0.90, p < 0.05), and the amplitudes were much smaller when the CTh was over 2.18 mm. After removing the multiple reflections in the cortical shell, the corresponding AIB (referred as AIB−c) decreased and the fluctuations were smaller (R = −0.80 ∼ −0.96, p < 0.05). An explicit compensation method for the cortical effect was proposed. No significant correlations were observed between the CTh and the compensated AIB (CAIB: R = −0.19 ∼ 0.26, p > 0.05, and CAIB−c: R = −0.09 ∼ −0.00, p > 0.05, respectively), and the fluctuations in CAIB−c were also reduced. The results demonstrated that the effect of cortical thickness on backscatter signals was removed by the compensation method proposed in this study.
One-dimensional electromagnetic band gap structures formed by discharge plasmas in a waveguide
Authors: Arkhipenko V. I. , Callegari Th. , Simonchik L. V. , Sokoloff J. , Usachonak M. S.
Published: September 2014

We demonstrate the ability to develop one-dimensional electromagnetic band gap structure in X-band waveguide solely by using the positive columns of glow discharges in neon at the middle pressure. Plasma inhomogeneities are distributed uniformly along a typical X-band waveguide with cross section of 23 × 10 mm2. It is shown that electron densities larger than 1014 cm−3 are needed in order to create an effective one-dimensional electromagnetic band gap structure. Some applications for using the one-dimensional electromagnetic band gap structure in waveguide as a control of microwave (broadband filter and device for variation of pulse duration) are demonstrated.
Influence of rear located silver nanoparticle induced light losses on the light trapping of silicon wafer-based solar cells
Authors: Zhang Yinan , Jia Baohua , Ouyang Zi , Gu Min
Published: September 2014

Management of the light losses associated with silver nanoparticle integrated plasmonic back reflectors in silicon wafer solar cells is critical to realize performance enhancement. The light losses, including the intrinsic absorption loss from silver nanoparticles and the additional absorption loss induced by the void plasmons in the aluminum reflectors, are quantitatively studied for cells with different front surface morphologies. The study reveals that silver nanoparticles are effective to enhance the photocurrent in cells with planar front surface, while the absorption enhancement can be significantly offset by the plasmonic losses in the textured cells, contributing to marginal or even decreased photocurrent.
Determination of the activation energy spectrum of structural relaxation in metallic glasses using calorimetric and shear modulus relaxation data
Authors: Tsyplakov A. N. , Mitrofanov Yu. P. , Makarov A. S. , Afonin G. V. , Khonik V. A.
Published: September 2014

We consider two methods for reconstruction of the activation energy spectra of structural relaxation from calorimetric and shear modulus relaxation data. The methods are based on the assumption that structural relaxation of metallic glasses can be understood as a relaxation change of the concentration of frozen-in defects similar to dumbbell interstitials (interstitialcies) in simple crystals. For three Pd- and Zr-based glasses taken as an example, it is shown that both methods give nearly the same results. We calculated a decrease of the defect concentration and showed that the heat of structural relaxation per defect for all three glasses practically coincides with the theoretical value of the interstitialcy formation enthalpy.
Size effect of Young's modulus in AlN thin layers
Authors: Hähnlein Bernd , Schaaf Peter , Pezoldt Jörg
Published: September 2014

In this work, the size effect of the aluminum nitride's Young's modulus is demonstrated. It manifests in a decreasing Young's modulus with decreasing layer thickness. The observed thickness dependence is significant for thickness below 300 nm. The results were demonstrated on AlN grown by metal organic chemical vapor deposition using microelectromechanical structures. Measuring and analyzing the resonator length dependence of the resonance frequency using a modified Euler-Bernoulli description allowed to extract the thickness dependence of the Young's modulus. The cantilever curvatures were determined using a newly developed model. It is also demonstrated that the current existing models do not reflect the observed thickness dependence of the Young′s modulus in a satisfactory way. A model is derived to describe the deviation in the thin film limit.
A Monte Carlo study of reflection electron energy loss spectroscopy spectrum of a carbon contaminated surface
Authors: Da B. , Li Z. Y. , Chang H. C. , Mao S. F. , Ding Z. J.
Published: September 2014

It has been experimentally found that the carbon surface contamination influences strongly the spectrum signals in reflection electron energy loss spectroscopy (REELS) especially at low primary electron energy. However, there is still little theoretical work dealing with the carbon contamination effect in REELS. Such a work is required to predict REELS spectrum for layered structural sample, providing an understanding of the experimental phenomena observed. In this study, we present a numerical calculation result on the spatially varying differential inelastic mean free path for a sample made of a carbon contamination layer of varied thickness on a SrTiO3 substrate. A Monte Carlo simulation model for electron interaction with a layered structural sample is built by combining this inelastic scattering cross-section with the Mott's cross-section for electron elastic scattering. The simulation results have clearly shown that the contribution of the electron energy loss from carbon surface contamination increases with decreasing primary energy due to increased individual scattering processes along trajectory parts carbon contamination layer. Comparison of the simulated spectra for different thicknesses of the carbon contamination layer and for different primary electron energies with experimental spectra clearly identifies that the carbon contamination in the measured sample was in the form of discontinuous islands other than the uniform film.
Geometric structure, electron-energy spectrum, and growth of anionic scandium-silicon clusters ScSin- (n = 6–20)
Authors: Borshch N. , Kurganskii S.
Published: September 2014

Results of the geometric structure optimization and calculated electron spectra of anion ScSin− clusters (n = 6–20) are presented. Calculations were carried out within the density functional theory framework. Real geometric structures of ScSin− clusters were established by the comparison of calculated and known experimental data. Formation of stable endohedral clusters is possible for n≥14, for clusters with smaller number of silicon atoms exohedral or longitudinal structures are preferable.
Uniformity of direct and converse magnetoelectric effects in magnetostrictive–piezoelectric composites
Authors: Liu Guoxi , Dong Shuxiang
Published: September 2014

In this paper, we theoretically and experimentally confirmed the uniformity of magnetoelectric (ME) coupling coefficients for the direct and converse ME (DME and CME) effects in longitudinal-transverse (L-T) mode magnetostrictive–piezoelectric two-phase composites, both at low frequencies and in the electromechanical resonance region. We also discussed the flaws in previous measurements of the ME coupling coefficients, which led to misunderstandings in the uniformity between the DME and CME effects. Our current work provided a correct method to correctly understand ME coupling in magnetostrictive-piezoelectric two-phase composites.
Switching between ground and excited states by optical feedback in a quantum dot laser diode
Authors: Virte Martin , Breuer Stefan , Sciamanna Marc , Panajotov Krassimir
Published: September 2014

We demonstrate switching between ground state and excited state emission in a quantum-dot laser subject to optical feedback. Even though the solitary laser emits only from the excited state, we can trigger the emission of the ground state by optical feedback. We observe recurrent but incomplete switching between the two emission states by variation of the external cavity length in the sub-micrometer scale. We obtain a good qualitative agreement of experimental results with simulation results obtained by a rate equation that accounts for the variations of the feedback phase.
A method of removing the valence band discontinuity in HgCdTe-based nBn detectors
Authors: Akhavan N. D. , Umana-Membreno G. A. , Jolley G. , Antoszewski J. , Faraone L.
Published: September 2014

A method is described where the valence band discontinuity in HgCdTe-based nBn detectors will be eliminated. The method relies on doping modulation technique, where grading the material composition and doping concentration of the barrier layer at the same time will lead to elimination of the valence band discontinuity in HgCdTe-based nBn detectors. The method is not limited to the nBn structure and can be applied to any barrier detector structure with xBx (with x = n, p) to eliminate the energy band discontinuity in the valence band or conduction band.
The electroluminescence mechanism of Er3+ in different silicon oxide and silicon nitride environments
Authors: Rebohle L. , Berencén Y. , Wutzler R. , Braun M. , Hiller D. , Ramírez J. M. , Garrido B. , Helm M. , Skorupa W.
Published: September 2014

Rare earth doped metal-oxide-semiconductor (MOS) structures are of great interest for Si-based light emission. However, several physical limitations make it difficult to achieve the performance of light emitters based on compound semiconductors. To address this point, in this work the electroluminescence (EL) excitation and quenching mechanism of Er-implanted MOS structures with different designs of the dielectric stack are investigated. The devices usually consist of an injection layer made of SiO2 and an Er-implanted layer made of SiO2, Si-rich SiO2, silicon nitride, or Si-rich silicon nitride. All structures implanted with Er show intense EL around 1540 nm with EL power efficiencies in the order of 2 × 10−3 (for SiO2:Er) or 2 × 10−4 (all other matrices) for lower current densities. The EL is excited by the impact of hot electrons with an excitation cross section in the range of 0.5–1.5 × 10−15 cm−2. Whereas the fraction of potentially excitable Er ions in SiO2 can reach values up to 50%, five times lower values were observed for other matrices. The decrease of the EL decay time for devices with Si-rich SiO2 or Si nitride compared to SiO2 as host matrix implies an increase of the number of defects adding additional non-radiative de-excitation paths for Er3+. For all investigated devices, EL quenching cross sections in the 10−20 cm2 range and charge-to-breakdown values in the range of 1–10 C cm−2 were measured. For the present design with a SiO2 acceleration layer, thickness reduction and the use of different host matrices did not improve the EL power efficiency or the operation lifetime, but strongly lowered the operation voltage needed to achieve intense EL.
Lithium fluoride injection layers can form quasi-Ohmic contacts for both holes and electrons
Authors: Bory Benjamin F. , Rocha Paulo R. F. , Janssen René A. J. , Gomes Henrique L. , De Leeuw Dago M. , Meskers Stefan C. J.
Published: September 2014

Thin LiF interlayers are typically used in organic light-emitting diodes to enhance the electron injection. Here, we show that the effective work function of a contact with a LiF interlayer can be either raised or lowered depending on the history of the applied bias. Formation of quasi-Ohmic contacts for both electrons and holes is demonstrated by electroluminescence from symmetric LiF/polymer/LiF diodes in both bias polarities. The origin of the dynamic switching is charging of electrically induced Frenkel defects. The current density–electroluminescence–voltage characteristics can qualitatively be explained. The interpretation is corroborated by unipolar memristive switching and by bias dependent reflection measurements.
Cities as Risk Managers: The Impact of Chicago's Parking Meter P3 on Municipal Governance and Transportation Planning
Authors: Farmer Stephanie
Published: September 2014

Although the benefits of infrastructure public–private partnerships are widely promoted, the public has little understanding of the new forms of risk and risk management obligations that city governments often absorb in infrastructure leasing concession agreements. This paper examines the City of Chicago's parking meter lease agreement with Morgan Stanley Infrastructure Partners. Risk reduction mechanisms embedded in the contract resulted in the city absorbing new costs and risks that negatively impacted city finances and remade the local state as a risk manager tasked with responsibilities that protect the rate of return of the global infrastructure investment fund. New planning and fiscal risks work as obstacles for transportation planners altering current street-level transportation configurations. Interviews with transportation planners revealed the new barriers put in place to safeguard financial investment that planners must navigate in order to realize environmentally sustainable and innovative street-level transportation planning.
Streetlighting in England and Wales: New Technologies and Uncertainty in the Assemblage of Streetlighting Infrastructure
Authors: Shaw Robert
Published: September 2014

To dim or not to dim? That is the choice that streetlighting engineers across the world are currently having to make. In the context of austerity politics, increased local-scale responsibility for climate-change mitigation and the emergence of technological developments, this choice of how to provide streetlighting has become newly politicised. In particular, new opportunities for streetlighting practice, including the use of efficient LED lighting and ‘computer management systems’ for controlling smart urban lighting, have emerged. This research paper draws from the concept of assemblage in order to argue that the practices of developing policy knowledge in this area of technological change need to be connected with understandings of lived experiences of infrastructure. Through interviews conducted with lighting engineers at local authorities in England, I explore the techniques and practices involved in generating the knowledge required to make choices with regards to new technologies and innovative practices. In particular, I argue that, while drawing on experiments and trials allows local authority lighting engineers to measure and understand certain features of an assemblage, it also leaves a significant gap with regards to the more tacit and experiential ways in which people engage with infrastructure on a day-to-day basis. This results in a number of uncertainties which local authority staff are aware of, but which they struggle to overcome. As such, this research comments on the difficulties inherent to understanding assemblages, and the ways in which choices are made at the intersection of energy policy, social governance, and technological innovation.