bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of photocurrent and capacitance of TiO2 nanotube–polyaniline hybrid composites synthesized through electroreduction of an aryldiazonium salt
Authors: Palmas Simonetta , Mascia Michele , Vacca Annalisa , Llanos Javier , Mena Esperanza
Published: April 2014

TiO2 nanotube–polyaniline hybrid composites were synthesized using an aminophenyl under-layer electrochemically grafted on TiO2 obtaining improvements in photocurrent and capacitance.
A capillary electrophoresis/tandem mass spectrometry approach for the determination of monoalkyl carbonates
Authors: Lucio do Lago Claudimir , Mendonça Francisco Kelliton José , Daniel Daniela , Rajh Vidal Denis Tadeu , Bezerra dos Santos Vagner
Published: April 2014

Despite monoalkyl carbonates being species prone to hydrolysis, they may be separated by capillary electrophoresis and detected in a mass spectrometer upon ionization by electrospray.
Synthesis of an acid-cleavable and fluorescent amphiphilic block copolymer as a combined delivery vector of DNA and doxorubicin
Authors: Hao Ying , He Jinlin , Li Sen , Liu Jian , Zhang Mingzu , Ni Peihong
Published: April 2014

An acid-cleavable and fluorescent block copolymer with good biocompatibility has been prepared and applied as a co-delivery carrier of DNA and doxorubicin.
No‐reference image quality assessment algorithm based on Weibull statistics of log‐derivatives of natural scenes
Authors: Abdalmajeed Saifeldeen , Shuhong Jiao
Published: April 2014

A blind/no‐reference (NR) image quality assessment (IQA) algorithm based on natural scenes is developed. The proposed algorithm does not need training on databases of human judgments of distorted images or even prior knowledge about expected distortions (as is the case in most general NR IQA algorithms). To measure the image quality, the introduced approach uses a set of novel features in a spatial domain. The devised features are formed using the Weibull statistics of log‐derivatives. When testing the proposed algorithm on the LIVE database, experiments showed that it correlates well with subjective opinion scores. In addition, they indicated that the new method has a good performance when compared with the state‐of‐the‐art methods.
Experimental realisation of micromachined terahertz waveguide‐fed antipodal tapered slot antenna
Authors: Lu Hongda , Lv Xin , Zhou Kai , Liu Yong
Published: April 2014

A terahertz (THz) waveguide‐fed antipodal tapered slot antenna (ATSA) based on silicon micromachined technology is proposed. The ATSA is composed of an antipodal tapered slots structure and a WR2.2 feeding waveguide, monolithically fabricated by deep reactive‐ion etching, and sputtering gold and gold–gold thermo‐compression bonding. The input return loss is tested and shows a level below −15 dB within 480 to 500 GHz. The gaussicity of radiation patterns at the working band is calculated to be 90%. Through further experiment, at 492 GHz, the ATSA exhibits asymmetric beamwidths of 25.5° and 25° in the E‐ and H‐ planes, respectively, and sidelobes below −8 dB, along with a 14.6 dB gain, which agree well with the simulated results. The proposed THz waveguide‐fed ATSA is suitable for use as a feeder of THz imaging and detection systems.
Single‐layer reflectarray with combination of element types
Authors: Yoon Ji Hwan , Kim Jae‐sik , Yoon Young Joong , Lee Woo‐sang , So Joon‐ho
Published: April 2014

A single‐layer reflectarray with a combination of element types is proposed. Three element types—square patch, square ring and ring‐loaded patch (RLP)—are used together to design the reflectarray by compensating for the drawbacks of one type by the others. The gain of the proposed reflectarray is 29.1 dBi, which is 1.9 dB higher than that of the reference reflectarray that was designed with only the RLP.
Four‐channel self‐compensating single‐slope ADC for space environments
Authors: Sordo‐Ibáñez S. , Espejo‐Meana S. , Piñero‐García B. , Ragel‐Morales A. , Ceballos‐Cáceres J. , Muñoz‐Díaz M. , Carranza‐González L. , Arias‐Drake A. , Mora‐Gutiérrez J.M. , Lagos‐Florido M.A. , Ramos‐Martos J.
Published: April 2014

A multichannel high‐resolution single‐slope analogue‐to‐digital converter (SS ADC) is presented that automatically compensates for process, voltage and temperature variations, as well as for radiation effects, in order to be used in extreme environmental conditions. The design combines an efficient implementation by using a feedback loop that ensures an inherently monotonic and very accurate ramp generation, with high levels of configurability in terms of resolution and conversion rate, as well as input voltage range. The SS ADC was designed in a standard 0.35 µm CMOS technology. Experimental measurements of the performance and stability against radiation and temperature are presented to verify the proposed approach.
Despread‐ahead cyclic‐prefix code division multiple access receiver with compressive sensing channel impulse response estimation
Authors: Chang Dah‐Chung , Wu Ruo‐Yu
Published: April 2014

The conventional cyclic‐prefix code division multiple access (CP‐CDMA) system usually requires a chip‐rate frequency‐domain equaliser (FDE) at the cost of a tremendous discrete Fourier transform (DFT) size. To reduce the required DFT size in the CP‐CDMA uplink receiver, this work studies a new symbol‐rate equaliser moving the code despreader ahead of the FDE. The authors formulate the composite effect of the chip‐rate channel impulse response (CIR) and code despreading as an equivalent symbol‐rate channel model together with a small additive noise. Then, an iterative two‐stage multiuser interference (MUI) cancellation algorithm can be employed with the decision feedback equalisation method. In addition, a novel compressive sensing (CS)‐based interpolation method is proposed for compressible CIR estimation to be used in the MUI cancellation algorithm. With the CS method, the DFT size is dramatically reduced for channel estimation and no high‐resolution interpolation kernels are required. The numerical results show that the new receiver is effective on MUI cancellation and only a couple of iterations are required to achieve a performance similar to the chip‐rate equaliser.
Optimal deactivated sub‐carriers guard bands for spectrum pooling systems based on wavelet‐based orthogonal frequency division multiplexing
Authors: Miao Liu , Na Li , Sun Zhen‐Xing
Published: April 2014

Cognitive radio (CR) is an advanced technology for efficient use of radio resources. In the CR system, the spectrum pooling technique is used to enhance spectrum utilisation, which enables public access to the spectral ranges of the licenced frequency bands which are seldom used by overlaying an unlicenced user (unLU) on an existing licenced user (LU). The spectrum pooling system constructed by implementing wavelet‐based orthogonal frequency division multiplexing (WOFDM) owns better flexibility and bandwidth efficiency. However, the interference between the LU and the unLU is severe in the multipath wireless channel. In the study, the intercarrier interference (ICI) interference energy of the spectrum pooling‐based WOFDM is analysed and an optimal deactivated subcarriers algorithm for the guard bands is proposed to mitigate the ICI between the unLU and the LU by intelligently deactivating one or more of the optimal deactivated subchannels which generates the maximum ICI interference in the LU. The numerical and the simulation results show that the data transmission rate of the unLU is ensured, the ICI of the LU is reduced and the bit error rate performance of the LU is, respectively, improved by implementing the algorithm.
Multimodal random forest based tensor regression
Authors: Kaymak Sertan , Patras Ioannis
Published: April 2014

This study presents a method, called random forest based tensor regression, for real‐time head pose estimation using both depth and intensity data. The method builds on random forests and proposes to train and use tensor regressors at each leaf node of the trees of the forest. The tensor regressors are trained using both intensity and depth data and their votes are fused. The proposed method is shown to outperform current state of the art approaches in terms of accuracy when applied to the publicly available Biwi Kinect head pose dataset.
Wide linear range orthogonal micro‐fluxgate with multi‐segmented core
Authors: Guo Bo , Liu Shibin , Nan Qinbo , Yang Shanglin , Hou Xiaowei , Feng Wenguang
Published: April 2014

A method to increase the linear operating range and improve the sensitivity of orthogonal micro‐fluxgates through multi‐segmented core was introduced in this study. The multi‐segmented core consisted of several rows, and each row consisted of many segments. The simulated results showed that segmented cores had the same effect on increasing demagnetisation of axial direction compared with shortened cores. Moreover, metameric cores produced longer core length and more turns of detection coils, which was beneficial for sensitivity. Longer excitation wire corresponding to the multi‐segmented core produced higher input impedance, which reduced the useless power consumption in driving circuit. The test results showed that: the linear operating range increased as the number of segments; the sensitivity increased as the number of the rows; the spectrum characteristic did not disturb by increasing the number of the rows or segments; the magnetic noise increases with increasing the number of segments and decreases with increasing the number of rows; and finally the additive range of ±800 μT, sensitivity of 43.4 V/T and magnetic noise of 28.4 nT/rtHz at 1 Hz were achieved with ten rows five segments core structure in an orthogonal micro‐fluxgate.
Direct adaptive general type‐2 fuzzy control for a class of uncertain non‐linear systems
Authors: Ghaemi Mostafa , Hosseini‐Sani Seyyed Kamal , Khooban Mohammad Hassan
Published: April 2014

In this study, a stable direct adaptive general type‐2 fuzzy logic controller (DAG2FLC) is introduced for a class of non‐linear systems. The proposed controller uses advantages of general type‐2 fuzzy logic systems (GT2FLSs) in handling dynamic uncertainties to approximate unknown non‐linear actions. Implementing general type‐2 fuzzy systems is computationally costly; however, by using a recently introduced α‐plane representation, a GT2FLS can be seen as composition of several interval type‐2 fuzzy logic systems with a corresponding level of α for each. Linguistic rules are directly incorporated into the DAG2FLC controller and a H∞ compensator is added to attenuate external disturbance and fuzzy approximation error. Also general type‐2 fuzzy adaptation laws are derived using Lyapunov approach, and the stability of the closed‐loop system has been proven by mathematical analysis. In order to evaluate the performance of the proposed controller, the results are compared with those obtained by direct adaptive type‐1 fuzzy logic controller and a direct adaptive interval type‐2 fuzzy logic controller, which are the latest researches in the problem in hand. The proposed controller is applied to a chaotic Gyro system as a case study. Simulation reveals the effectiveness of the proposed controller in presence of dynamic uncertainties and external disturbances.
Fabrication of filtering artificial‐compound eye for multi‐spectral imaging
Authors: Di Si , Jin Jian , Chen Xianshuai , Du Ruxu
Published: April 2014

Presented is a novel method for integrating the artificial‐compound eye (ACE) structure with the multichannel filter on one substrate based on the microfabrication technique. By this method, a compact multi‐spectral imaging lens was developed. From the point of view of the structure, it is a microlens array with the function of a filter, hence, it is called a filtering ACE. The lens has several optical units, and each unit can capture the information for a certain band which corresponds to the red, green, blue and near‐infrared bands. The fabrication process and key steps are discussed in detail. Based on this filtering ACE lens, a multi‐spectral imaging system was set up. The imaging results prove that the system can realise colour separation and multi‐units imaging as expected. The work band of the system covers the whole visible band and a part of near‐infrared band. In addition, a light blocking layer and a light separation layer were added in the filtering ACE and the image quality was improved. The novel filtering ACE structure is suitable to be applied in smart multi‐spectral imaging system because of its high integration level and the ability of capturing the multi‐band images.
Vector spin modeling for magnetic tunnel junctions with voltage dependent effects
Authors: Manipatruni Sasikanth , Nikonov Dmitri E. , Young Ian A.
Published: April 2014

Integration and co-design of CMOS and spin transfer devices requires accurate vector spin conduction modeling of magnetic tunnel junction (MTJ) devices. A physically realistic model of the MTJ should comprehend the spin torque dynamics of nanomagnet interacting with an injected vector spin current and the voltage dependent spin torque. Vector spin modeling allows for calculation of 3 component spin currents and potentials along with the charge currents/potentials in non-collinear magnetic systems. Here, we show 4-component vector spin conduction modeling of magnetic tunnel junction devices coupled with spin transfer torque in the nanomagnet. Nanomagnet dynamics, voltage dependent spin transport, and thermal noise are comprehended in a self-consistent fashion. We show comparison of the model with experimental magnetoresistance (MR) of MTJs and voltage degradation of MR with voltage. Proposed model enables MTJ circuit design that comprehends voltage dependent spin torque effects, switching error rates, spin degradation, and back hopping effects.
Molecular dynamics study of salt–solution interface: Solubility and surface charge of salt in water
Authors: Kobayashi Kazuya , Liang Yunfeng , Sakka Tetsuo , Matsuoka Toshifumi
Published: April 2014

The NaCl salt–solution interface often serves as an example of an uncharged surface. However, recent laser-Doppler electrophoresis has shown some evidence that the NaCl crystal is positively charged in its saturated solution. Using molecular dynamics (MD) simulations, we have investigated the NaCl salt–solution interface system, and calculated the solubility of the salt using the direct method and free energy calculations, which are kinetic and thermodynamic approaches, respectively. The direct method calculation uses a salt–solution combined system. When the system is equilibrated, the concentration in the solution area is the solubility. In the free energy calculation, we separately calculate the chemical potential of NaCl in two systems, the solid and the solution, using thermodynamic integration with MD simulations. When the chemical potential of NaCl in the solution phase is equal to the chemical potential of the solid phase, the concentration of the solution system is the solubility. The advantage of using two different methods is that the computational methods can be mutually verified. We found that a relatively good estimate of the solubility of the system can be obtained through comparison of the two methods. Furthermore, we found using microsecond time-scale MD simulations that the positively charged NaCl surface was induced by a combination of a sodium-rich surface and the orientation of the interfacial water molecules.
A numerical study of the phase behaviors of drug particle/star triblock copolymer mixtures in dilute solutions for drug carrier application
Authors: Wang Shanhui , Tong Chaohui , Zhu Yuejin
Published: April 2014

The complex microstructures of drug particle/ABA star triblock copolymer in dilute solutions have been investigated by a theoretical approach which combines the self-consistent field theory and the hybrid particle-field theory. Simulation results reveal that, when the volume fraction of drug particles is smaller than the saturation concentration, the drug particle encapsulation efficiency is 100%, and micelle loading capacity increases with increasing particle volume fraction. When the volume fraction of drug particles is equal to the saturation concentration, the micelles attain the biggest size, and micelle loading capacity reaches a maximum value which is independent of the copolymer volume fraction. When the volume fraction of drug particles is more than the saturation concentration, drug particle encapsulation efficiency decreases with increasing volume fraction of drug particles. Furthermore, it is found that the saturation concentration scales linearly with the copolymer volume fraction. The above simulation results are in good agreement with experimental results.
Assembly of diblock copolymer functionalized spherical nanoparticles as a function of copolymer composition
Authors: Estridge Carla E. , Jayaraman Arthi
Published: April 2014

In this work, we use coarse-grained molecular dynamics simulations to study spherical nanoparticles functionalized with AB diblock copolymer chains at low grafting density, to obtain a design library linking copolymer composition, monomer-monomer interaction strengths, graft lengths, particle sizes, and monomer solvent-philicity to the two stages of nanoparticle assembly: the initial formation of patches within the copolymer-grafted particles from attractive monomers aggregating, and then the (equilibrium) assembled cluster formation. With regards to patch formation, as the fraction of the solvent-phobic (A or B) block decreases along the graft and the interaction strength decreases, the propensity to form patches on the particles decreases. As the fraction of the solvent-phobic block increases, the time for patch formation decreases, in particular if the inner A block is solvent-phobic. As the ratio of graft length to particle size increases the propensity to form fewer patches increases due to inter-graft monomer aggregation. For all compositions, the assembled clusters formed in B-selective solvents (solvent-phobic A block) have a higher fraction of particles at smaller inter-particle distances than in A-selective solvents (solvent-phobic B block). In an A-selective solvent at low interaction strengths, as the graft length to particle diameter ratio is increased, the tendency to form isotropic clusters at equilibrium is increased, and intermediate anisotropic chain-like assembly is observed. When these anisotropic intermediate states are observed, they accelerate the formation of equilibrium isotropic clusters. With increasing strength of interaction between solvent-phobic B monomers, the intermediate states disappear from the assembly pathway. At low and intermediate interaction strengths, as fraction of A block increases, the clusters’ outer shell of solvent-philic A monomers which surrounds the patch of solvent-phobic B monomers becomes dense, hindering addition of more particles to the cluster leading to smaller overall clusters. In a B-selective solvent, predominantly anisotropic clusters form, and show an increase in shape anisotropy with increasing monomer interaction strength. In both cases of monomer solvent-philicity, with an increase in the graft length to particle diameter ratio we see a decrease in anisotropic cluster formation. And, in both cases of monomer solvent philicity, with increasing monomer interaction strength the average cluster size and tendency to form anisotropic clusters is increased.
Spectra of random operators with absolutely continuous integrated density of states
Authors: del Rio Rafael
Published: April 2014

The structure of the spectrum of random operators is studied. It is shown that if the density of states measure of some subsets of the spectrum is zero, then these subsets are empty. In particular follows that absolute continuity of the integrated density of states implies singular spectra of ergodic operators is either empty or of positive measure. Our results apply to Anderson and alloy type models, perturbed Landau Hamiltonians, almost periodic potentials, and models which are not ergodic.
Dynamical and structural properties of monohydroxy alcohols exhibiting a Debye process
Authors: Wieth P. , Vogel M.
Published: April 2014

We perform molecular dynamics simulations to study dynamical and structural properties of various primary monohydroxy alcohols. Comparing rotational correlation functions for the individual dipole moment of the molecules and the total dipole moment of the system, it is shown that the studied models exhibit a Debye process, which is slower than the α process, in harmony with experimental results. Performing cluster analysis, it is found that hydroxyl groups tend to form hydrogen-bonded aggregates, in particular, chain structures, which are transient in nature. To ascertain a possible relation between the Debye process and aggregate fluctuations, we devise an algorithm allowing us to follow the time evolution of transient chains. It is observed that the life times of transient chains are substantially shorter than the correlation times of the Debye process, indicating that the latter relaxation is not a direct consequence of the chain reorganization in the studied models. We assure that this conclusion is not affected when hydrogen-bond cooperativity is mimicked in the simulations or when the polarity of the molecules and the size of the systems are varied. On the other hand, we find that orientational correlations of molecular dipole moments are not limited to hydrogen-bonded chains, but they also exist in more globular regions around these objects, implying that the neighboring molecules are polarized in the dipole field exerted by the hydrogen-bonded chains. Further evidence for a relevance of dipole fields comes from the observation that some correlation between the initial orientation of the total dipole moment and the instantaneous orientations of the molecular dipole moments is retained up to the time scale of the Debye process. The simulation results are discussed in terms of a La-Ola wave model with diffusive propagation.
Influence of longitudinal isotope substitution on the thermal conductivity of carbon nanotubes: Results of nonequilibrium molecular dynamics and local density functional calculations
Authors: Leroy Frédéric , Schulte Joachim , Balasubramanian Ganesh , Böhm Michael C.
Published: April 2014

We report reverse nonequilibrium molecular dynamics calculations of the thermal conductivity of isotope substituted (10,10) carbon nanotubes (CNTs) at 300 K. 12C and 14C isotopes both at 50% content were arranged either randomly, in bands running parallel to the main axis of the CNTs or in bands perpendicular to this axis. It is found that the systems with randomly distributed isotopes yield significantly reduced thermal conductivity. In contrast, the systems where the isotopes are organized in patterns parallel to the CNTs axis feature no reduction in thermal conductivity when compared with the pure 14C system. Moreover, a reduction of approximately 30% is observed in the system with the bands of isotopes running perpendicular to the CNT axis. The computation of phonon dispersion curves in the local density approximation and classical densities of vibrational states reveal that the phonon structure of carbon nanotubes is conserved in the isotope substituted systems with the ordered patterns, yielding high thermal conductivities in spite of the mass heterogeneity. In order to complement our conclusions on the 12C-14C mixtures, we computed the thermal conductivity of systems where the 14C isotope was turned into pseudo-atoms of 20 and 40 atomic mass units.
Empirical assessment of the detection efficiency of CR-39 at high proton fluence and a compact, proton detector for high-fluence applications
Authors: Rosenberg M. J. , Séguin F. H. , Waugh C. J. , Rinderknecht H. G. , Orozco D. , Frenje J. A. , Johnson M. Gatu , Sio H. , Zylstra A. B. , Sinenian N. , Li C. K. , Petrasso R. D. , Glebov V. Yu. , Stoeckl C. , Hohenberger M. , Sangster T. C. , LePape S. , Mackinnon A. J. , Bionta R. M. , Landen O. L. , Zacharias R. A. , Kim Y. , Herrmann H. W. , Kilkenny J. D.
Published: April 2014

CR-39 solid-state nuclear track detectors are widely used in physics and in many inertial confinement fusion (ICF) experiments, and under ideal conditions these detectors have 100% detection efficiency for ∼0.5–8 MeV protons. When the fluence of incident particles becomes too high, overlap of particle tracks leads to under-counting at typical processing conditions (5 h etch in 6N NaOH at 80 °C). Short etch times required to avoid overlap can cause under-counting as well, as tracks are not fully developed. Experiments have determined the minimum etch times for 100% detection of 1.7–4.3-MeV protons and established that for 2.4-MeV protons, relevant for detection of DD protons, the maximum fluence that can be detected using normal processing techniques is ≲3 × 106 cm−2. A CR-39-based proton detector has been developed to mitigate issues related to high particle fluences on ICF facilities. Using a pinhole and scattering foil several mm in front of the CR-39, proton fluences at the CR-39 are reduced by more than a factor of ∼50, increasing the operating yield upper limit by a comparable amount.
Thermal desorption mass spectrometer for mass metrology
Authors: Silvestri Z. , Azouigui S. , Bouhtiyya S. , Macé S. , Plimmer M. D. , Pinot P. , Tayeb-Chandoul F. , Hannachi R.
Published: April 2014

This article presents a device for the study of physisorbed elements on polished surfaces (diameter ⩽56 mm) of the kind used in mass metrology. The technique is based on mass spectrometry of molecules desorbed after heating under vacuum of the analyzed surface. We describe a first application of the device to study current and future mass standards in order to understand how their surface reactivity depends on storage conditions, cleaning processes, and polishing methods. Surface contamination analysis by thermal desorption mass spectrometry to examine the effect of cleaning on pure iridium is given as an example.
Effects of excluded volume and correlated molecular orientations on Förster resonance energy transfer in liquid water
Authors: Yang Mino
Published: April 2014

Förster theory for the survival probability of excited chromophores is generalized to include the effects of excluded volume and orientation correlation in the molecular distribution. An analytical expression for survival probability was derived and written in terms of a few simple elementary functions. Because of the excluded volume, the survival probability exhibits exponential decay at early times and stretched exponential decay at later times. Experimental schemes to determine the size of the molecular excluded volume are suggested. With the present generalization of theory, we analyzed vibrational resonance energy transfer kinetics in neat water. Excluded volume effects prove to be important and slow down the kinetics at early times. The majority of intermolecular resonance energy transfer was found to occur with exponential kinetics, as opposed to the stretched exponential behavior predicted by Förster theory. Quantum yields of intra-molecular vibrational relaxation, intra-, and intermolecular energy transfer were calculated to be 0.413, 0.167, and 0.420, respectively.
Phonon dispersion and thermal conductivity of nanocrystal superlattices using three-dimensional atomistic models
Authors: Zanjani Mehdi B. , Lukes Jennifer R.
Published: April 2014

A computational study of thermal conductivity and phonon dispersion of gold nanocrystal superlattices is presented. Phonon dispersion curves, reported here for the first time from combined molecular dynamics and lattice dynamics calculations, show multiple phononic band gaps and consist of many more dispersion branches than simple atomic crystals. Fully atomistic three dimensional molecular dynamics calculations of thermal conductivity using the Green Kubo method are also performed for the first time on these materials. Thermal conductivity is observed to increase for increasing nanocrystal core size and decrease for increasing surface ligand density. Our calculations predict values in the range 0.1–1 W/m K that are consistent with reported experimental results.
Filtered pulsed cathodic arc deposition of fullerene-like carbon and carbon nitride films
Authors: Tucker Mark D. , Czigány Zsolt , Broitman Esteban , Näslund Lars-Åke , Hultman Lars , Rosen Johanna
Published: April 2014

Carbon and carbon nitride films (CNx, 0 ≤ x ≤ 0.26) were deposited by filtered pulsed cathodic arc and were investigated using transmission electron microscopy and X-ray photoelectron spectroscopy. A “fullerene-like” (FL) structure of ordered graphitic planes, similar to that of magnetron sputtered FL-CNx films, was observed in films deposited at 175 °C and above, with N2 pressures of 0 and 0.5 mTorr. Higher substrate temperatures and significant nitrogen incorporation are required to produce similar FL structure by sputtering, which may, at least in part, be explained by the high ion charge states and ion energies characteristic of arc deposition. A gradual transition from majority sp3-hybridized films to sp2 films was observed with increasing substrate temperature. High elastic recovery, an attractive characteristic mechanical property of FL-CNx films, is evident in arc-deposited films both with and without nitrogen content, and both with and without FL structure.
Low-frequency 1/f noise in MoS2 transistors: Relative contributions of the channel and contacts
Authors: Renteria J. , Samnakay R. , Rumyantsev S. L. , Jiang C. , Goli P. , Shur M. S. , Balandin A. A.
Published: April 2014

We report on the results of the low-frequency (1/f, where f is frequency) noise measurements in MoS2 field-effect transistors revealing the relative contributions of the MoS2 channel and Ti/Au contacts to the overall noise level. The investigation of the 1/f noise was performed for both as fabricated and aged transistors. It was established that the McWhorter model of the carrier number fluctuations describes well the 1/f noise in MoS2 transistors, in contrast to what is observed in graphene devices. The trap densities extracted from the 1/f noise data for MoS2 transistors, are 2 × 1019 eV−1cm−3 and 2.5 × 1020 eV−1cm−3 for the as fabricated and aged devices, respectively. It was found that the increase in the noise level of the aged MoS2 transistors is due to the channel rather than the contact degradation. The obtained results are important for the proposed electronic applications of MoS2 and other van der Waals materials.
Optical temperature sensor based on upconversion emission in Er-doped ferroelectric 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramic
Authors: Du Peng , Luo Laihui , Li Weiping , Yue Qingying , Chen Hongbing
Published: April 2014

Optical temperature sensing properties based on upconversion emission of Er-doped 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ferroelectric ceramics are reported. The fluorescence intensity ratio of green upconversion emissions at 525 and 550 nm in the temperature range of 200–443 K was investigated. The maximum sensing sensitivity and temperature resolution were found to be 0.0044 K−1 and 0.4 K, respectively, suggesting that the Er-doped 0.5Ba(Zr0.2Ti0.8)O3- 0.5(Ba0.7Ca0.3)TiO3 ferroelectric ceramic possesses potential application in optical temperature sensing. Ferroelectric and piezoelectric properties were also investigated. These results reveal that the Er-doped 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ferroelectric ceramic is a promising multifunctional sensing material.
Time-resolved photoluminescence properties of semiconductor quantum dot superlattices of different microcrystal shapes
Authors: Chae Weon-Sik , Choi Eunjin , Ku Jung Yun , Jung Jin-Seung , Lee Jin-Kyu
Published: April 2014

We report time-resolved photoluminescence properties on semiconductor quantum dot (QD) superlattices (SLs) using PL lifetime imaging microscopy at a single particle level. PL lifetime imaging technique clearly reveals that different shaped QD SL microcrystals have different time-resolved PL characteristics. The faceted SL microcrystals consisted of well-organized QDs showed faster recombination rates than those of the spherical microparticles including randomly organized QDs, which can be explained by the different degree of energetic couplings among component QDs due to different packing fraction.
Effect of voltage polarity on oxidation-reduction potential by plasma in water
Authors: Miyahara Takashi , Oizumi Masanobu , Nakatani Tatsuyuki , Sato Takehiko
Published: April 2014

Use of plasma in water for water treatment and medical treatment is growing and raises expectations of finding advanced functions such as an increase of biological compatibility. In the present study with a focus on the variation of oxidation-reduction potential (ORP), relationships between the electrode polarities of plasma in water and the change of water quality such as conductivity, H2O2 concentration, dissolved hydrogen concentration, pH and ORP were revealed. Similar line spectra of radiation at the electrode tip were observed for each case of positive and negative electrode polarity. The emission intensities of OH (309 nm), Hα (656 nm), and OI (777 nm) for the positive discharge were significantly higher than those for the negative one, though the energy consumption during the discharge period of both cases was nearly the same. Positive electrode polarity was found to be more suitable than negative electrode polarity for increasing dissolved hydrogen gas and hydrogen peroxide. The ORP for the positive polarity decreased from 460 to 45 mV and that for the negative polarity decreased from 460 to 183 mV, although the pH and conductivity were not significantly changed.
Neighborhood Quality-of-Life Dynamics and the Great Recession: The Case of Charlotte, North Carolina
Authors: Delmelle Elizabeth C , Thill Jean-Claude
Published: April 2014

This paper examines neighborhood responses to the business cycle of the decade 1999–2009. Utilizing a quality-of-life (QoL) framework to profile neighborhoods in the city of Charlotte, North Carolina, we investigate with a Markov-chain methodology how the process of change was impacted by short-term economic fluxes including the greatest downturn since the Great Depression. Results indicate that neighborhoods falling within the lowest QoL category exhibited the greatest boost in relative upward mobility in the boom leading up to the recession. Many of these same neighborhoods reverted back to their previous conditions once the recession hit. Overall, neighborhood resilience is context dependent and so is neighborhood response to exogenous shocks. The same patterns did not hold true when the QoL index was decomposed into its four comprising dimensions.
Expressing ‘Nationhood’ under Conditions of Constrained Sovereignty: Postage Stamp Iconography of the Bantustans
Authors: Hammett Daniel
Published: April 2014

States utilise a range of everyday objects to transmit ideals of nationhood and statehood. Quotidian objects such as currency and postage stamps have provided a means through which to portray to domestic and international audiences the values, ideologies, aspirations, and ideals of the state. For newly established or newly independent states, the political importance of these practices is heightened as they can provide a material embodiment of the state's founding ideology. However, in situations where (sub)state entities have independence imposed upon them, rather than it being sought and claimed, the role and content of the expressions of nationhood expressed through these objects can be complicated by experiences of constrained sovereignty. This paper explores how South Africa's creation of the independent Bantustans resulted in the complex expression of nationalism through postage stamp iconography. The resultant narratives are identified as drawing upon territoriality, nationhood, political authority, and international citizenship in efforts to claim sovereignty that served to reinscribe and reinforce factors contributing to the Bantustans' experiences of constrained sovereignty.
Filtering and Gentrifying in Toronto: Neighbourhood Transitions in and out from the Lowest Income Decile between 1981 and 2006
Authors: Skaburskis Andrejs , Nelson Kristopher
Published: April 2014

This study examines the changes between 1981 and 2006 in Toronto's lowest income neighbourhoods. It shows the oldest buildings gentrifying while, contrary to filtering theory, the newer high-rise apartments in the inner suburbs built for a car-oriented middle class were filtering down to visible minorities, recent immigrants, ethnic minorities, single parents, and the unemployed or underemployed people in low-wage jobs. Nevertheless, the lowest income neighbourhoods display a considerable degree of income mix pointing to the importance of household-based rather than space-based housing policy. The high proportion of university graduates in the lowest income neighbourhoods raises questions about the role of education in helping people gain access to urban resources. While government transfers to households in the top nine income deciles increased, they decreased for the lowest income households. Although the average income in the CMA rose faster than rents, rents increased in the lowest decile neighbourhoods with declining incomes. Low-income households were moving to pedestrian-unfriendly neighborhoods with poor access to public transit and employment opportunities.
The Relationship between Spatial Planning and Economic Competitiveness: The ‘Path to Economic Nirvana’ or a ‘Dangerous Obsession’?
Authors: Boland Philip
Published: April 2014

This paper offers a contribution to contemporary studies of spatial planning. In particular, it problematises the relationship between neoliberal competitiveness and spatial planning. Neoliberal competitiveness is a hegemonic discourse in public policy as it (allegedly) provides the ‘path to economic nirvana’. However, commentators have critiqued its theoretical underpinnings and labelled it a ‘dangerous obsession’ for policy makers. Another set of literatures argues that spatial planning can be understood as a form of ‘neoliberal spatial governance’ and read in a ‘postpolitical’ framework that ‘privileges competitiveness’. Synthesising these debates this paper critically analyses the application and operationalisation of neoliberal competitiveness in Northern Ireland and Belfast. In focusing on this unique case study—a deeply divided society with a turbulent history—the paper takes the debate forward in arguing that rather than offering the ‘path to economic nirvana’ neoliberal competitiveness is a ‘postpolitical strategy’ and represents a ‘dangerous obsession’ for spatial planning.
Spatial Layout, Social Structure, and Innovation in Organizations
Authors: Wineman Jean , Hwang Yongha , Kabo Felichism , Owen-Smith Jason , Davis Gerald F
Published: April 2014

Research on the enabling factors of innovation has most often addressed either the social component of organizations or the spatial dimensions involved in the innovation process. Few studies have examined the link from spatial layout and social networks to innovation. Social networks play important roles in structuring communication, collaboration, access to knowledge, and knowledge transformation. These processes are both antecedent to and part of the innovation process. Spatial layout structures patterns of circulation, proximity, awareness of others, and encounter in an organization. These interrelationships become fundamental to the development of social networks, especially those networks critical to the innovation process. This research explored associations between innovation within three partner organizations and the organization's social and spatial structure. The organizations included: A nonprofit life sciences institute dedicated to translational research on cancer, the research laboratories of a multinational software corporation, and the quality control group of an automobile manufacturer. The study applied spatial analysis to map and characterize physical space in conjunction with survey data capturing social contacts among researchers at the three organizations. For one partner organization, we augmented these tools with location-tracking methods. It could be argued that sociometric surveys capture the ‘perceived’ social network. Social networks researchers have been very interested in assessing ‘real’ networks either as reliability checks on sociometric survey networks, or as stand-alone networks. Our use of an ultrawideband location system allowed us to assess networks in real time. In interpreting our results, we suggest that through exposure to moving others, locations with high metric choice may provide the opportunities for serendipitous encounters among individuals who may come from disparate parts of an organization. Whereas low mean distance to others may provide the enhanced connections necessary to mobilize the resources and attention to move innovative ideas forward. Results demonstrate the salience of both social and spatial dimensions in the processes of innovation. The research suggests two strong factors that appear to influence our results: the institutional context which characterizes or prioritizes certain innovation outcomes; the extent to which the physical facility design of organizations tends to concentrate or spatially distribute the research unit. Our findings indicate that relationships between salutary network positions and beneficial locales themselves derive from institutional contexts that shape the priorities, opportunities, goals and practices of discovery. We suggest that innovation is a process that occurs at the intersection of social and physical space, and moves toward a sociospatial science of design for innovation.
Recent Evidence on Perception and Esthetic Appreciation: The Role of Value and Expertise in Canon Formation
Authors: Consoli Gianluca
Published: April 2014

On the basis of current evidence derived from neurocognitive research, it is possible to mediate two alternative theories concerning the relationship between perception and esthetic appreciation, in particular by distinguishing between high-quality images and popular.
Humoral response to a viral glycan correlates with survival on PROSTVAC-VF
Authors: Campbell Christopher T. , Gulley James L. , Oyelaran Oyindasola , Hodge James W. , Schlom Jeffrey , Gildersleeve Jeffrey C.
Published: April 2014

Significance

Because individual cancer patients differ considerably in their clinical benefits from immunotherapies, early indicators of response could help physicians personalize treatments. Unfortunately, conventional clinical response criteria can be misleading for cancer vaccines. Herein, we show that early humoral responses to xenogenic Forssman disaccharide displayed on PROSTVAC-VF’s viral vectors correlate with long-term survival of vaccinated prostate cancer patients. The survival correlation for anti-Forssman responses was observed consistently when PROSTVAC-VF was used either as monotherapy or combined with the radiopharmaceutical Quadramet. Monitoring postvaccination anti-Forssman humoral responses could offer a simple indicator of response many months before conventional clinical response criteria become reliable. Finally, this study suggests that modifying glycans may improve poxvirus-based vaccines even when not specifically designed to target glycans.
Tau mutants bind tubulin heterodimers with enhanced affinity
Authors: Elbaum-Garfinkle Shana , Cobb Garrett , Compton Jocelyn T. , Li Xiao-Han , Rhoades Elizabeth
Published: April 2014

Significance

The microtubule binding protein tau is implicated in the pathology of a number of devastating neurological disorders. Both loss of function arising from altered interactions with microtubules and gain of toxic function tied to tau aggregation are thought to have a role in disease etiology. Here, we demonstrate that point mutants of tau implicated in disease enhance the affinity between tau and tubulin dimers. Our results lend insight into the mechanism of tau-mediated microtubule polymerization. Importantly, our findings highlight the significance of the interaction between tau and free tubulin, introducing it as a new focus for research on the role of tau in neurodegeneration.
Fundamental differences between Arctic and Antarctic ozone depletion
Authors: Solomon Susan , Haskins Jessica , Ivy Diane J. , Min Flora
Published: April 2014

Significance

Fundamental differences in observed ozone depletion between the Arctic and the Antarctic are shown, clarifying distinctions between both average and extreme ozone decreases in the two hemispheres. Balloon-borne and satellite measurements in the heart of the ozone layer near 18−24 km altitude show that extreme ozone decreases often observed in the Antarctic ozone hole region have not yet been measured in the Arctic in any year, including the unusually cold Arctic spring of 2011. The data provide direct evidence that heavily depleted air contains reduced nitric acid abundances, and better quantify the roles of polar stratospheric cloud chemistry and temperatures below −80 °C to −85 °C in ozone destruction.
Light intensity modulates the regulatory network of the shade avoidance response in
Arabidopsis
Authors: Hersch Micha , Lorrain Séverine , de Wit Mieke , Trevisan Martine , Ljung Karin , Bergmann Sven , Fankhauser Christian
Published: April 2014

Significance

Plants sense foliar shade and neighbors who may become competitors for light. Shade-sensitive species elongate in response to both situations to enhance access to unfiltered sunlight, which is known as the shade avoidance response (SAR). During neighbor detection, plants have access to plenty of light (energy resources), whereas in true shade, light resources are scarce. Our analysis of the molecular mechanisms underlying SAR under these contrasting conditions shows that light intensity balances the production and sensitivity of the growth hormone auxin. In foliar shade, the production of auxin is reduced, whereas the downstream sensitivity to the auxin signal is enhanced. This hints at a resource-aware signaling where the strength of the hormonal signal is tuned to the available resources.
Regional cerebral metabolic patterns demonstrate the role of anterior forebrain mesocircuit dysfunction in the severely injured brain
Authors: Fridman Esteban A. , Beattie Bradley J. , Broft Allegra , Laureys Steven , Schiff Nicholas D.
Published: April 2014

Significance

Establishing consciousness in the human brain requires an ensemble activity of multiple cortical and subcortical structures. Following severe brain injuries, widespread deafferentation and neuronal death alter function across the corticothalamic system and its projections to the basal ganglia. In this paper, we test a theoretical model of a mesocircuit mechanism likely to arise in all severe brain injuries. Specifically, reduction of resting glucose metabolism within the central thalamus, striatum, and frontoparietal cortices and concomitant increases in metabolism within the globus pallidus as a result of disinhibition are proposed to arise across etiologies of injury. Here we verify this prediction and demonstrate a reversal of metabolic profile of central thalamus and globus pallidus that characterizes and indexes the patients’ behavioral level.
X-ray structure of human aquaporin 2 and its implications for nephrogenic diabetes insipidus and trafficking
Authors: Frick Anna , Eriksson Urszula Kosinska , de Mattia Fabrizio , Öberg Fredrik , Hedfalk Kristina , Neutze Richard , de Grip Willem J. , Deen Peter M. T. , Törnroth-Horsefield Susanna
Published: April 2014

Significance

Human aquaporin 2 (AQP2) is found in the kidney collecting duct, where it translocates water across the apical membrane and is crucial for urine concentration. AQP2 is regulated by trafficking between intracellular storage vesicles and the apical membrane, a process that is tightly controlled by the pituitary hormone arginine vasopressin. Defective AQP2 trafficking leads to nephrogenic diabetes insipidus (NDI), a water balance disorder characterized by large urine volumes, leading to dehydration. We have solved the X-ray structure of human AQP2 at 2.75 Å resolution. This structure deepens our molecular understanding of AQP2 trafficking, as well as serves as a structural scaffold for understanding why AQP2 mutations cause NDI.