bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction and coulodynamic characterization of PPy-DBS-MWCNT/tape bilayer artificial muscles
Authors: Otero Toribio F. , Schumacher Johanna , Pascual Victor H.
Published: June 2016

A bilayer full polymeric artificial muscle comprised of electrogenerated PPy-DBS-MWCNT composite and tape was constructed and electrochemical and electrodynamical characterized.
Electrochemical biosensor with graphene oxide nanoparticles and polypyrrole interface for the detection of bilirubin
Authors: Chauhan N. , Rawal R. , Hooda V. , Jain U.
Published: June 2016

A bilirubin biosensor was fabricated by immobilization of bilirubin oxidase (BOx) on a graphene oxide nanoparticle (GONP) decorated polypyrrole (Ppy) layer electrochemically deposited onto a fluorine doped tin oxide (FTO) glass plate.
Manganous oxide nanoparticles encapsulated in few-layer carbon as an efficient electrocatalyst for oxygen reduction in alkaline media
Authors: Cheng Han , Xu Kun , Xing Lili , Liu Si , Gong Yue , Gu Lin , Zhang Lidong , Wu Changzheng
Published: June 2016

Manganous oxide nanoparticles encapsulated in few-layer carbon were reported as an efficient electrocatalyst for oxygen reduction in alkaline media.
Surface passivation effect by fluorine plasma treatment on ZnO for efficiency and lifetime improvement of inverted polymer solar cells
Authors: Polydorou Ermioni , Zeniou Angelos , Tsikritzis Dimitris , Soultati Anastasia , Sakellis Ilias , Gardelis Spyros , Papadopoulos Theodoros A. , Briscoe Joe , Palilis Leonidas C. , Kennou Stella , Gogolides Evangelos , Argitis Panagiotis , Davazoglou Dimitris , Vasilopoulou Maria
Published: June 2016

The surface passivation effect of SF6 plasma on ZnO films for application in polymer solar cells is demonstrated.
Morphological characterization of a new low-bandgap thermocleavable polymer showing stable photovoltaic properties
Authors: Vahdani Pierayeh , Li Xianzhen , Zhang Chi , Holdcroft Steven , Frisken Barbara J.
Published: June 2016

Optical microscopy, TEM and SAXS reveal stable morphology at micro and nanoscopic length scales.
Proteasome regulates turnover of toxic human amylin in pancreatic cells
Authors: Singh Sanghamitra , Trikha Saurabh , Sarkar Anjali , Jeremic Aleksandar M.
Published: June 2016

Toxic human amylin (hA) oligomers and aggregates are implicated in the pathogenesis of type 2 diabetes mellitus (T2DM). Although recent studies demonstrated a causal connection between hA uptake and toxicity in pancreatic cells, the mechanism of amylin's clearance following its internalization and its relationship to toxicity is yet to be determined, and hence was investigated here. Using pancreatic rat insulinoma β-cells and human islets as model systems, we show that hA, following its internalization, first accumulates in the cytosol followed by its translocation into nucleus, and to a lesser extent lysosomes, keeping the net cytosolic amylin content low. An increase in hA accumulation in the nucleus of pancreatic cells correlated with its cytotoxicity, suggesting that its excessive accumulation in the nucleus is detrimental. hA interacted with 20S core and 19S lid subunits of the β-cell proteasomal complex, as suggested by immunoprecipitation and confocal microscopy studies, which subsequently resulted in a decrease in the proteasome's proteolytic activity in these cells. In vitro binding and activity assays confirmed an intrinsic and potent ability of amylin to interact with the 20S core complex thereby modulating its proteolytic activity. Interestingly, less toxic and aggregation incapable rat amylin (rA) showed a comparable inhibitory effect on proteasome activity and protein ubiquitination, decoupling amylin aggregation/ toxicity and amylin-induced protein stress. In agreement with these studies, inhibition of proteasomal proteolytic activity significantly increased intracellular amylin content and toxicity. Taken together, our results suggest a pivotal role of proteasomes in amylin's turnover and detoxification in pancreatic cells.
Polydatin post-treatment alleviates myocardial ischaemia/reperfusion injury by promoting autophagic flux
Authors: Ling Yuanna , Chen Guiming , Deng Yi , Tang Huixiong , Ling Long , Zhou Xiaoming , Song Xudong , Yang Pingzhen , Liu Yingfeng , Li Zhiliang , Zhao Cong , Yang Yufei , Wang Xianbao , Kitakaze Masafumi , Liao Yulin , Chen Aihua
Published: June 2016

Polydatin (PD), a resveratrol (RES) glycoside, has a stronger antioxidative effect than RES. It is known that RES is an autophagic enhancer and exerts a cardioprotective effect against ischaemia/reperfusion (I/R) injury. However, the effect of PD post-treatment on myocardial I/R injury remains unclear. In the present study, we investigated the influences of PD post-treatment on myocardial I/R injury and autophagy. C57BL/6 mice underwent left coronary artery (LCA) occlusion and cultured neonatal rat cardiomyocytes (NRCs) subjected to hypoxia were treated with vehicle or PD during reperfusion or re-oxygenation. We noted that PD enhanced autophagy and decreased apoptosis during I/R or hypoxia/reoxygenation (H/R), and this effect was antagonized by co-treatment with adenovirus carrying short hairpin RNA for Beclin 1 and 3-methyladenine (3-MA), an autophagic inhibitor. Compared with vehicle-treated mice, PD-treated mice had a significantly smaller myocardial infarct size (IS) and a higher left ventricular fractional shortening (LVFS) and ejection fraction (EF), whereas these effects were partly reversed by 3-MA. Furthermore, in the PD-treated NRCs, tandem fluorescent mRFP-GFP-LC3 assay showed abundant clearance of autophagosomes with an enhanced autophagic flux, and co-treatment with Bafilomycin A1 (Baf), a lysosomal inhibitor, indicated that PD promoted the degradation of autolysosome. In addition, PD post-treatment reduced mitochondrial membrane potential and cellular reactive oxygen species (ROS) production in NRCs, and these effects were partially blocked by Baf. These findings indicate that PD post-treatment limits myocardial I/R injury by promoting autophagic flux to clear damaged mitochondria to reduce ROS and cell death.
Cross‐Gramian based frequency‐weighted model order reduction technique
Authors: Zulfiqar U. , Imran M. , Ghafoor A.
Published: June 2016

A cross‐gramian‐based frequency‐weighted model/controller‐order reduction technique is proposed for single‐input single‐output and symmetric MIMO stable systems. The proposed algorithm does not require the original system to be minimal. Numerical examples are presented to show the effectiveness of the proposed technique.
Multi‐band joint local sparse tracking via wavelet transforms
Authors: Han Guang , Luo Heng , Liu Jixin , Sun Ning , Du Kun , Li Xiaofei
Published: June 2016

A novel multi‐band joint local sparse tracking algorithm via wavelet transforms is proposed in this study. The object image may contain rich information of different types; the authors use wavelet transforms to decompose the object image into some sub‐band images first. This will help extract the information in different frequency ranges for the object. Then same block operation is executed on all the sub‐band images. The l2, 1 mixed‐norm is used to describe the multi‐band joint local sparse representation on each patch; it can effectively extract the structural information in different frequency ranges. Thus, more accurate object appearance model can be established. Second, the coefficients on the diagonal of coefficient matrix are extracted for the confidence degrees of the candidate objects in this band, and then the confidence degree results in all the bands are fused to determine the best candidate object in the current frame. This can effectively alleviate the object drifting. Finally, both qualitative and quantitative evaluation results on 15 challenging video sequences demonstrate that the proposed tracking algorithm in this study can achieve better tracking effects compared with the other state‐of‐the‐art algorithms.
Modelling of the modified‐LLCL‐filter‐based single‐phase grid‐tied Aalborg inverter
Authors: Liu Zifa , Wu Huiyun , Liu Yuan , Ji Junhao , Wu Weimin , Blaabjerg Frede
Published: June 2016

Owing to less conduction and switching power losses, the recently proposed Aalborg inverter has high efficiency within a wide range of input DC voltage for single‐phase DC/AC power conversion. In theory, the conduction power losses can be further decreased, if an LLCL‐filter is adopted instead of an LCL‐filter for a voltage source inverter, mainly due to the reduced inductance. The Aalborg inverter shows the characteristic of a current source inverter, when working in the ‘boost’ state. Whether the LLCL‐filter can meet the control requirement of this type inverter needs to be further explored. In this study, the small signal analysis for the modified‐LLCL‐filter‐based Aalborg inverter is addressed. Through the modelling, it can be proven that compared with the LCL‐filter, the modified‐LLCL‐filter causes no extra control challenge for the Aalborg inverter, and therefore more inductance in the power loop can be safely saved as well as a complete smaller filter size. A 220 V/50 Hz, 2000 W prototype is used to demonstrate the theoretical analysis.
Second-order asymptotics for quantum hypothesis testing in settings beyond i.i.d.—quantum lattice systems and more
Authors: Datta Nilanjana , Pautrat Yan , Rouzé Cambyse
Published: June 2016

Quantum Stein’s lemma is a cornerstone of quantum statistics and concerns the problem of correctly identifying a quantum state, given the knowledge that it is one of two specific states (ρ or σ). It was originally derived in the asymptotic i.i.d. setting, in which arbitrarily many (say, n) identical copies of the state (ρ⊗n or σ⊗n) are considered to be available. In this setting, the lemma states that, for any given upper bound on the probability αn of erroneously inferring the state to be σ, the probability βn of erroneously inferring the state to be ρ decays exponentially in n, with the rate of decay converging to the relative entropy of the two states. The second order asymptotics for quantum hypothesis testing, which establishes the speed of convergence of this rate of decay to its limiting value, was derived in the i.i.d. setting independently by Tomamichel and Hayashi, and Li. We extend this result to settings beyond i.i.d. Examples of these include Gibbs states of quantum spin systems (with finite-range, translation-invariant interactions) at high temperatures, and quasi-free states of fermionic lattice gases.
Tensor representation techniques for full configuration interaction: A Fock space approach using the canonical product format
Authors: Böhm Karl-Heinz , Auer Alexander A. , Espig Mike
Published: June 2016

In this proof-of-principle study, we apply tensor decomposition techniques to the Full Configuration Interaction (FCI) wavefunction in order to approximate the wavefunction parameters efficiently and to reduce the overall computational effort. For this purpose, the wavefunction ansatz is formulated in an occupation number vector representation that ensures antisymmetry. If the canonical product format tensor decomposition is then applied, the Hamiltonian and the wavefunction can be cast into a multilinear product form. As a consequence, the number of wavefunction parameters does not scale to the power of the number of particles (or orbitals) but depends on the rank of the approximation and linearly on the number of particles. The degree of approximation can be controlled by a single threshold for the rank reduction procedure required in the algorithm. We demonstrate that using this approximation, the FCI Hamiltonian matrix can be stored with N5 scaling. The error of the approximation that is introduced is below Millihartree for a threshold of ϵ = 10−4 and no convergence problems are observed solving the FCI equations iteratively in the new format. While promising conceptually, all effort of the algorithm is shifted to the required rank reduction procedure after the contraction of the Hamiltonian with the coefficient tensor. At the current state, this crucial step is the bottleneck of our approach and even for an optimistic estimate, the algorithm scales beyond N10 and future work has to be directed towards reduction-free algorithms.
Fano response induced by the interference between localized plasmons and interface reflections in metal-insulator-metal waveguide structure
Authors: Li Hong-Ju , Wang Ling-Ling , Zhai Xiang
Published: June 2016

The original Fano response induced by the interference between the localized plasmons and interface-reflected surface plasmon polaritons in a single metal-insulator-metal waveguide with two parallel separated metal strips is predicted theoretically through the coupled mode theory combined with the Fano function. The prominent asymmetric line shape resulting from the coupling between the discrete dipole resonance formed between metal strips and an interface-reflected-induced continuum is confirmed by the performed numerical simulations. The novel Fano spectrum is tuned easily by varying the length and coupling distance of metal strips. By introducing another separated metal strip, the outstanding double Fano behavior is obtained, and the corresponding underlying physics is illustrated. In particular, based on the performed refractive index sensing spectra, the high sensitivity of 855 nm/RIU and figure of merit up to 30 are achieved via the double Fano resonance. Undoubtedly, such ingenious structure may benefit the fabrications of nano-integrated plasmonic devices for optical switching and sensing.
Controlling resonant tunneling in graphene via Fermi velocity engineering
Authors: Lima Jonas R. F. , Pereira Luiz Felipe C. , Bezerra C. G.
Published: June 2016

We investigate the resonant tunneling in a single layer graphene superlattice with modulated energy gap and Fermi velocity via an effective Dirac-like Hamiltonian. We calculate the transmission coefficient with the transfer matrix method and analyze the effect of a Fermi velocity modulation on the electronic transmission, in the case of normal and oblique incidence. We find it is possible to manipulate the electronic transmission in graphene by Fermi velocity engineering, and show that it is possible to tune the transmitivity from 0 to 1. We also analyze how a Fermi velocity modulation influences the total conductance and the Fano factor. Our results are relevant for the development of novel graphene-based electronic devices.
The onset of plasma potential locking
Authors: Hopkins Matthew M. , Yee Benjamin T. , Baalrud Scott D. , Barnat Edward V.
Published: June 2016

In this paper, we provide insight into the role and impact that a positively biased electrode (anode) has on bulk plasma potential. Using two-dimensional Particle-in-Cell simulations, we investigate the plasma potential as an anode transitions from very small (“probe” mode) to large (“locking” mode). Prior theory provides some guidance on when and how this transition takes place. Initial experimental results are also compared. The simulations demonstrate that as the surface area of the anode is increased transitions in plasma potential and sheath polarity occur, consistent with experimental observations and theoretical predictions. It is expected that understanding this basic plasma behavior will be of interest to basic plasma physics communities, diagnostic developers, and plasma processing devices where control of bulk plasma potential is important.
Phase diagram of ammonium perchlorate: Raman spectroscopic constrains at high pressures and temperatures
Authors: Dunuwille Mihindra , Yoo Choong-Shik
Published: June 2016

We present the pressure-temperature (PT) induced physical and chemical transformations in ammonium perchlorates (APs) up to 50 GPa and 450 °C, using diamond anvil cells and confocal micro-Raman spectroscopy, which provide new constraints for the phase diagram of AP. The results show spectral evidences for three new polymorphs (III, IV, and VI) of AP, in addition to two previously known phases (I and II), at various PT conditions with varying degrees of hydrogen bonding and lack of strong spectral evidence for previously known high-temperature cubic phase (phase V). Upon further heating, AP chemically decomposes to N2, N2O, and H2O. The present phase diagram is, therefore, in sharp contrast to the previous one, underscoring a rich polymorphism, a large stability field for solids, and a replacement of the melt with a decomposition line.
Application of classical thermodynamics to the conductivity in non-polar media
Authors: Gourdin-Bertin S. , Chassagne C.
Published: June 2016

Electrical conductivity in non-polar media is a subject which recently regained interest. If most of experiments and theoretical developments were done more than 50 years ago, new experiments and theories have been recently published. As the electrical conductivity describes, at low field, the equilibrium state of a system, it is natural to apply theories based on equilibrium thermodynamics. In this article, well-established classical thermodynamics and solvations models are applied to recently published data. This enables to get a new insight in intriguing phenomena, such as the linear dependence of the conductivity on the concentration of ionic surfactant and the evaluation of conductivity for the mixture of two miscible fluids, such as alcohol and alcane, which have very different conductivities.
Gyrokinetic simulations of electrostatic microinstabilities with bounce-averaged kinetic electrons for shaped tokamak plasmas
Authors: Qi Lei , Kwon Jaemin , Hahm T. S. , Jo Gahyung
Published: June 2016

Nonlinear bounce-averaged kinetic theory [B. H. Fong and T. S. Hahm, Phys. Plasmas 6, 188 (1999)] is used for magnetically trapped electron dynamics for the purpose of achieving efficient gyrokinetic simulations of Trapped Electron Mode (TEM) and Ion Temperature Gradient mode with trapped electrons (ITG-TEM) in shaped tokamak plasmas. The bounce-averaged kinetic equations are explicitly extended to shaped plasma equilibria from the previous ones for concentric circular plasmas, and implemented to a global nonlinear gyrokinetic code, Gyro-Kinetic Plasma Simulation Program (gKPSP) [J. M. Kwon et al., Nucl. Fusion 52, 013004 (2012)]. Verification of gKPSP with the bounce-averaged kinetic trapped electrons in shaped plasmas is successfully carried out for linear properties of the ITG-TEM mode and Rosenbluth-Hinton residual zonal flow [M. N. Rosenbluth and F. L. Hinton, Phys. Rev. Lett. 80, 724 (1998)]. Physics responsible for stabilizing effects of elongation on both ITG mode and TEM is identified using global gKPSP simulations. These can be understood in terms of magnetic flux expansion, leading to the effective temperature gradient R/LT(1−E′) [P. Angelino et al., Phys. Rev. Lett. 102, 195002 (2009)] and poloidal wave length contraction at low field side, resulting in the effective poloidal wave number kθρi/κ.
Dissipative entanglement of quantum spin fluctuations
Authors: Benatti F. , Carollo F. , Floreanini R.
Published: June 2016

We consider two non-interacting infinite quantum spin chains immersed in a common thermal environment and undergoing a local dissipative dynamics of Lindblad type. We study the time evolution of collective mesoscopic quantum spin fluctuations that, unlike macroscopic mean-field observables, retain a quantum character in the thermodynamical limit. We show that the microscopic dissipative dynamics is able to entangle these mesoscopic degrees of freedom, through a purely mixing mechanism. Further, the behaviour of the dissipatively generated quantum correlations between the two chains is studied as a function of temperature and dissipation strength.
Validation metrics for turbulent plasma transport
Authors: Holland C.
Published: June 2016

Developing accurate models of plasma dynamics is essential for confident predictive modeling of current and future fusion devices. In modern computer science and engineering, formal verification and validation processes are used to assess model accuracy and establish confidence in the predictive capabilities of a given model. This paper provides an overview of the key guiding principles and best practices for the development of validation metrics, illustrated using examples from investigations of turbulent transport in magnetically confined plasmas. Particular emphasis is given to the importance of uncertainty quantification and its inclusion within the metrics, and the need for utilizing synthetic diagnostics to enable quantitatively meaningful comparisons between simulation and experiment. As a starting point, the structure of commonly used global transport model metrics and their limitations is reviewed. An alternate approach is then presented, which focuses upon comparisons of predicted local fluxes, fluctuations, and equilibrium gradients against observation. The utility of metrics based upon these comparisons is demonstrated by applying them to gyrokinetic predictions of turbulent transport in a variety of discharges performed on the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)], as part of a multi-year transport model validation activity.
Theoretical and experimental study of the dynamic response of absorber-based, micro-scale, oscillatory probes for contact sensing applications
Authors: Kafashi Sajad , Strayhorn Ralph , Eldredge Jeff D. , Kelly Scott D. , Woody Shane C. , Smith Stuart T.
Published: June 2016

This paper presents two models for predicting the frequency response of micro-scale oscillatory probes. These probes are manufactured by attaching a thin fiber to the free end of one tine of a quartz tuning fork oscillator. In these studies, the attached fibers were either 75 μm diameter tungsten or 7 μm diameter carbon with lengths ranging from around 1 to 15 mm. The oscillators used in these studies were commercial 32.7 kHz quartz tuning forks. The first theoretical model considers lateral vibration of two beams serially connected and provides a characteristic equation from which the roots (eigenvalues) are extracted to determine the natural frequencies of the probe. A second, lumped model approximation is used to derive an approximate frequency response function for prediction of tine displacements as a function of a modal force excitation corresponding to the first mode of the tine in the absence of a fiber. These models are used to evaluate the effect of changes in both length and diameter of the attached fibers. Theoretical values of the natural frequencies of different modes show an asymptotic relationship with the length and a linear relationship with the diameter of the attached fiber. Similar results are observed from experiment, one with a tungsten probe having an initial fiber length of 14.11 mm incrementally etched down to 0.83 mm, and another tungsten probe of length 8.16 mm incrementally etched in diameter, in both cases using chronocoulometry to determine incremental volumetric material removal. The lumped model is used to provide a frequency response again reveals poles and zeros that are consistent with experimental measurements. Finite element analysis shows mode shapes similar to experimental microscope observations of the resonating carbon probes. This model provides a means of interpreting measured responses in terms of the relative motion of the tine and attached fibers. Of particular relevance is that, when a “zero” is observed in the response of the tine, one mode of the fiber is matched to the tine frequency and is acting as an absorber. This represents an optimal condition for contact sensing and for transferring energy to the fiber for fluid mixing, touch sensing, and surface modification applications.
The influence of society's mesoscopic structure on the rate of epidemic spreading
Authors: Kashisaz Hadi , Darooneh Amir H.
Published: June 2016

In this study, we investigate the role of the mesoscopic structural properties of a scale-free social network on the contagion spreading. We focus on both the exponent of power-law community size distribution function (β) and the mixing parameter (μ). Findings show that increasing β reduces the rate of epidemic spreading. On the other hand, increasing μ increases the rate of epidemic spreading. Two innovating parameters, Temperature and cos θ, are introduced here to analyze these effects.
Electromechanical characterization of individual micron-sized metal coated polymer particles
Authors: Bazilchuk Molly , Pettersen Sigurd Rolland , Kristiansen Helge , Zhang Zhiliang , He Jianying
Published: June 2016

Micron-sized polymer particles with nanoscale metal coatings are essential in conductive adhesives for electronics assembly. The particles function in a compressed state in the adhesives. The link between mechanical properties and electrical conductivity is thus of the utmost importance in the formation of good electrical contact. A custom flat punch set-up based on nanoindentation has been developed to simultaneously deform and electrically probe individual particles. The set-up has a sufficiently low internal resistance to allow the measurement of sub-Ohm contact resistances. Additionally, the set-up can capture mechanical failure of the particles. Combining this data yields a fundamental understanding of contact behavior. We demonstrate that this method can clearly distinguish between particles of different sizes, with different thicknesses of metal coating, and different metallization schemes. The technique provides good repeatability and physical insight into the behavior of these particles that can guide adhesive design and the optimization of bonding processes.
On the existence of the optimal order for wavefunction extrapolation in Born-Oppenheimer molecular dynamics
Authors: Fang Jun , Gao Xingyu , Song Haifeng , Wang Han
Published: June 2016

Wavefunction extrapolation greatly reduces the number of self-consistent field (SCF) iterations and thus the overall computational cost of Born-Oppenheimer molecular dynamics (BOMD) that is based on the Kohn–Sham density functional theory. Going against the intuition that the higher order of extrapolation possesses a better accuracy, we demonstrate, from both theoretical and numerical perspectives, that the extrapolation accuracy firstly increases and then decreases with respect to the order, and an optimal extrapolation order in terms of minimal number of SCF iterations always exists. We also prove that the optimal order tends to be larger when using larger MD time steps or more strict SCF convergence criteria. By example BOMD simulations of a solid copper system, we show that the optimal extrapolation order covers a broad range when varying the MD time step or the SCF convergence criterion. Therefore, we suggest the necessity for BOMD simulation packages to open the user interface and to provide more choices on the extrapolation order. Another factor that may influence the extrapolation accuracy is the alignment scheme that eliminates the discontinuity in the wavefunctions with respect to the atomic or cell variables. We prove the equivalence between the two existing schemes, thus the implementation of either of them does not lead to essential difference in the extrapolation accuracy.
Thermal gravitational separation of ternary mixture n-dodecane/isobutylbenzene/tetralin components in a porous medium
Authors: Larabi Mohamed Aziz , Mutschler Dimitri , Mojtabi Abdelkader
Published: June 2016

Our present work focuses on the coupling between thermal diffusion and convection in order to improve the thermal gravitational separation of mixture components. The separation phenomenon was studied in a porous medium contained in vertical columns. We performed analytical and numerical simulations to corroborate the experimental measurements of the thermal diffusion coefficients of ternary mixture n-dodecane, isobutylbenzene, and tetralin obtained in microgravity in the international space station. Our approach corroborates the existing data published in the literature. The authors show that it is possible to quantify and to optimize the species separation for ternary mixtures. The authors checked, for ternary mixtures, the validity of the “forgotten effect hypothesis” established for binary mixtures by Furry, Jones, and Onsager. Two complete and different analytical resolution methods were used in order to describe the separation in terms of Lewis numbers, the separation ratios, the cross-diffusion coefficients, and the Rayleigh number. The analytical model is based on the parallel flow approximation. In order to validate this model, a numerical simulation was performed using the finite element method. From our new approach to vertical separation columns, new relations for mass fraction gradients and the optimal Rayleigh number for each component of the ternary mixture were obtained.
Ionization equilibrium at the transition from valence-band to acceptor-band migration of holes in boron-doped diamond
Authors: Poklonski N. A. , Vyrko S. A. , Poklonskaya O. N. , Kovalev A. I. , Zabrodskii A. G.
Published: June 2016

A quasi-classical model of ionization equilibrium in the p-type diamond between hydrogen-like acceptors (boron atoms which substitute carbon atoms in the crystal lattice) and holes in the valence band (v-band) is proposed. The model is applicable on the insulator side of the insulator–metal concentration phase transition (Mott transition) in p-Dia:B crystals. The densities of the spatial distributions of impurity atoms (acceptors and donors) and of holes in the crystal are considered to be Poissonian, and the fluctuations of their electrostatic potential energy are considered to be Gaussian. The model accounts for the decrease in thermal ionization energy of boron atoms with increasing concentration, as well as for electrostatic fluctuations due to the Coulomb interaction limited to two nearest point charges (impurity ions and holes). The mobility edge of holes in the v-band is assumed to be equal to the sum of the threshold energy for diffusion percolation and the exchange energy of the holes. On the basis of the virial theorem, the temperature Tj is determined, in the vicinity of which the dc band-like conductivity of holes in the v-band is approximately equal to the hopping conductivity of holes via the boron atoms. For compensation ratio (hydrogen-like donor to acceptor concentration ratio) K ≈ 0.15 and temperature Tj, the concentration of “free” holes in the v-band and their jumping (turbulent) drift mobility are calculated. Dependence of the differential energy of thermal ionization of boron atoms (at the temperature 3Tj/2) as a function of their concentration N is calculated. The estimates of the extrapolated into the temperature region close to Tj hopping drift mobility of holes hopping from the boron atoms in the charge states (0) to the boron atoms in the charge states (−1) are given. Calculations based on the model show good agreement with electrical conductivity and Hall effect measurements for p-type diamond with boron atom concentrations in the range from 3 × 1017 to 3 × 1020 cm−3, i.e., up to the Mott transition. The model uses no fitting parameters.
On the induction of homogeneous bulk crystallization in Eu-doped calcium aluminosilicate glass by applying simultaneous high pressure and temperature
Authors: Muniz R. F. , de Ligny D. , Le Floch S. , Martinet C. , Rohling J. H. , Medina A. N. , Sandrini M. , Andrade L. H. C. , Lima S. M. , Baesso M. L. , Guyot Y.
Published: June 2016

From initial calcium aluminosilicate glass, transparent glass-ceramics have been successfully synthesized under simultaneous high pressure and temperature (SHPT). Possible homogeneous volumetric crystallization of this glassy system, which was not achieved previously by means of conventional heat treatment, has been put in evidence with a SHPT procedure. Structural, mechanical, and optical properties of glass and glass-ceramic obtained were investigated. Raman spectroscopy and X-ray diffraction allowed to identify two main crystalline phases: merwinite [Ca3Mg(SiO4)2] and diopside [CaMgSi2O6]. A Raman scanning profile showed that the formation of merwinite is quite homogeneous over the bulk sample. However, the sample surface also contains significant diopside crystals. Instrumented Berkovich nanoindentation was applied to determine the effect of SHPT on hardness from glass to glass-ceramic. For Eu-doped samples, the broadband emission due to 4f65d1 → 4f7 transition of Eu2+ was studied in both host systems. Additionally, the 5D0 → 7FJ transition of Eu3+ was used as an environment probe in the pristine glass and the glass-ceramic.
Examination of the temperature dependent electronic behavior of GeTe for switching applications
Authors: Champlain James G. , Ruppalt Laura B. , Guyette Andrew C. , El-Hinnawy Nabil , Borodulin Pavel , Jones Evan , Young Robert M. , Nichols Doyle
Published: June 2016

The DC and RF electronic behaviors of GeTe-based phase change material switches as a function of temperature, from 25 K to 375 K, have been examined. In its polycrystalline (ON) state, GeTe behaved as a degenerate p-type semiconductor, exhibiting metal-like temperature dependence in the DC regime. This was consistent with the polycrystalline (ON) state RF performance of the switch, which exhibited low resistance S-parameter characteristics. In its amorphous (OFF) state, the GeTe presented significantly greater DC resistance that varied considerably with bias and temperature. At low biases (<1 V) and temperatures (<200 K), the amorphous GeTe low-field resistance dramatically increased, resulting in exceptionally high amorphous-polycrystalline (OFF-ON) resistance ratios, exceeding 109 at cryogenic temperatures. At higher biases and temperatures, the amorphous GeTe exhibited nonlinear current-voltage characteristics that were best fit by a space-charge limited conduction model that incorporates the effect of a defect band. The observed conduction behavior suggests the presence of two regions of localized traps within the bandgap of the amorphous GeTe, located at approximately 0.26–0.27 eV and 0.56–0.57 eV from the valence band. Unlike the polycrystalline state, the high resistance DC behavior of amorphous GeTe does not translate to the RF switch performance; instead, a parasitic capacitance associated with the RF switch geometry dominates OFF state RF transmission.
On the geometry of mixed states and the Fisher information tensor
Authors: Contreras I. , Ercolessi E. , Schiavina M.
Published: June 2016

In this paper, we will review the co-adjoint orbit formulation of finite dimensional quantum mechanics, and in this framework, we will interpret the notion of quantum Fisher information index (and metric). Following previous work of part of the authors, who introduced the definition of Fisher information tensor, we will show how its antisymmetric part is the pullback of the natural Kostant–Kirillov–Souriau symplectic form along some natural diffeomorphism. In order to do this, we will need to understand the symmetric logarithmic derivative as a proper 1-form, settling the issues about its very definition and explicit computation. Moreover, the fibration of co-adjoint orbits, seen as spaces of mixed states, is also discussed.
A new set of potential energy surfaces for HCO: Influence of Renner-Teller coupling on the bound and resonance vibrational states
Authors: Ndengué Steve Alexandre , Dawes Richard , Guo Hua
Published: June 2016

It is commonly understood that the Renner-Teller effect can strongly influence the spectroscopy of molecules through coupling of electronic states. Here we investigate the vibrational bound states and low-lying resonances of the formyl radical treating the Renner-Teller coupled X̃2A′ and Ã2A″ states using the MultiConfiguration Time Dependent Hartree (MCTDH) method. The calculations were performed using the improved relaxation method for the bound states and a recently published extension to compute resonances. A new set of accurate global potential energy surfaces were computed at the explicitly correlated multireference configuration interaction (MRCI-F12) level and yielded remarkably close agreement with experiment in this application and thus enable future studies including photodissociation and collisional dynamics. The results show the necessity of including the large contribution from a Davidson correction in the electronic structure calculations in order to appreciate the relatively small effect of the Renner-Teller coupling on the states considered here.
Frequency mismatch in stimulated scattering processes: An important factor for the transverse distribution of scattered light
Authors: Gong Tao , Zheng Jian , Li Zhichao , Yang Dong , Hu Guangyue , Zhao Bin , Ding Yongkun
Published: June 2016

A 2D cylindrically symmetric model with inclusion of both diffraction and self-focus effects is developed to deal with the stimulated scattering processes of a single hotspot. The calculated results show that the transverse distribution of the scattered light is sensitive to the longitudinal profiles of the plasma parameters. The analysis of the evolution of the scattered light indicates that it is the frequency mismatch of coupling due to the inhomogeneity of plasmas that determines the transverse distribution of the scattered light.
Electrically controlled band gap and topological phase transition in two-dimensional multilayer germanane
Authors: Qi Jingshan , Li Xiao , Qian Xiaofeng
Published: June 2016

Electrically controlled band gap and topological electronic states are important for the next-generation topological quantum devices. In this letter, we study the electric field control of band gap and topological phase transitions in multilayer germanane. We find that although the monolayer and multilayer germananes are normal insulators, a vertical electric field can significantly reduce the band gap of multilayer germananes owing to the giant Stark effect. The decrease of band gap eventually leads to band inversion, transforming them into topological insulators with nontrivial Z2 invariant. The electrically controlled topological phase transition in multilayer germananes provides a potential route to manipulate topologically protected edge states and design topological quantum devices. This strategy should be generally applicable to a broad range of materials, including other two-dimensional materials and ultrathin films with controlled growth.
Communication: Proton NMR dipolar-correlation effect as a method for investigating segmental diffusion in polymer melts
Authors: Lozovoi A. , Mattea C. , Herrmann A. , Rössler E. A. , Stapf S. , Fatkullin N.
Published: June 2016

A simple and fast method for the investigation of segmental diffusion in high molar mass polymer melts is presented. The method is based on a special function, called proton dipolar-correlation build-up function, which is constructed from Hahn Echo signals measured at times t and t/2. The initial rise of this function contains additive contributions from both inter- and intramolecular magnetic dipole-dipole interactions. The intermolecular contribution depends on the relative mean squared displacements (MSDs) of polymer segments from different macromolecules, while the intramolecular part reflects segmental reorientations. Separation of both contributions via isotope dilution provides access to segmental displacements in polymer melts at millisecond range, which is hardly accessible by other methods. The feasibility of the method is illustrated by investigating protonated and deuterated polybutadiene melts with molecular mass 196 000 g/mol at different temperatures. The observed exponent of the power law of the segmental MSD is close to 0.32 ± 0.03 at times when the root MSD is in between 45 Å and 75 Å, and the intermolecular proton dipole-dipole contribution to the total proton Hahn Echo NMR signal is larger than 50% and increases with time.
Comparison of low frequency charge noise in identically patterned Si/SiO2 and Si/SiGe quantum dots
Authors: Freeman Blake M. , Schoenfield Joshua S. , Jiang HongWen
Published: June 2016

We investigate and compare the charge noise in Si/SiO2 and Si/SiGe gate defined quantum dots with identically patterned gates by measuring the low frequency 1/f current noise through the biased quantum dots in the coulomb blockade regime. The current noise is normalized and used to extract a measurement of the potential energy noise in the system. Additionally, the temperature dependence of this noise is investigated. The measured charge noise in Si/SiO2 compares favorably with that of the SiGe device as well as previous measurements made on other substrates suggesting Si/SiO2 is a potential candidate for spin based quantum computing.
Merging the retrieval of the protection coordination of distribution networks equipped with DGs in the process of their siting and sizing
Authors: Hosseini S. A. , Askarian Abyaneh H. , Sadeghi S. H. H. , Razavi F.
Published: June 2016

Changes in the topology of distribution networks which is due to connecting or disconnecting of distributed generations (DGs) is a critical challenge in maintaining protection coordination in these networks. Protection coordination is generally retrieved after deciding optimal capacity and location of installing DGs. Nevertheless, in this paper, a new method is presented which merges the protection coordination of distribution networks in the process of sizing and siting DGs. The presented approach of this paper, in addition to identifying the optimal location and capacity of DGs with the purpose of increasing the benefits and reducing cost of installing these resources, is to also create a robust protection coordination. In order to provide a robust protection coordination, the capacity and location of fault current limiters are identified parallel with sizing and siting DGs. The protection coordination considered in this paper results in grouping different topologies of the network according to allowable memory of protective relays. On this basis, the protection coordination of all operational topologies of the network is guaranteed. In order to coordinate each group interval linear programming is suggested. This method reduces the number of protection coordination constraints of each group and simplifies appropriate protection coordination for the group. The proposed method is tested on Zanjan Regional Electric Board, Iran. Simulation results are reported and discussed.
Hafnium carbide formation in oxygen deficient hafnium oxide thin films
Authors: Rodenbücher C. , Hildebrandt E. , Szot K. , Sharath S. U. , Kurian J. , Komissinskiy P. , Breuer U. , Waser R. , Alff L.
Published: June 2016

On highly oxygen deficient thin films of hafnium oxide (hafnia, HfO2−x) contaminated with adsorbates of carbon oxides, the formation of hafnium carbide (HfCx) at the surface during vacuum annealing at temperatures as low as 600 °C is reported. Using X-ray photoelectron spectroscopy the evolution of the HfCx surface layer related to a transformation from insulating into metallic state is monitored in situ. In contrast, for fully stoichiometric HfO2 thin films prepared and measured under identical conditions, the formation of HfCx was not detectable suggesting that the enhanced adsorption of carbon oxides on oxygen deficient films provides a carbon source for the carbide formation. This shows that a high concentration of oxygen vacancies in carbon contaminated hafnia lowers considerably the formation energy of hafnium carbide. Thus, the presence of a sufficient amount of residual carbon in resistive random access memory devices might lead to a similar carbide formation within the conducting filaments due to Joule heating.
Nonlinear optical enhancement induced by synergistic effect of graphene nanosheets and CdS nanocrystals
Authors: Zhu Baohua , Wang Fangfang , Cao Yawan , Wang Chong , Wang Ji , Gu Yuzong
Published: June 2016

CdS nanocrystals are attached on graphene nanosheets and their nonlinear optical properties are investigated by picosecond Z-scan technique at 532 nm. We found that synergistic effect between the graphene and CdS makes a major enhancement on the nonlinear optical absorption of graphene/CdS nanohybrid in comparison with cooperative effect, and the synergistic improvement is restricted by nonradiative defects in hybrid. The synergistic mechanism involving the local field theory and charge transfer evolution is proposed.
Influence of the anions on the N-cationic benzethonium salts in the solid state and solution: Chloride, bromide, hydroxide and citrate hydrates
Authors: Paradies Henrich H. , Reichelt Hendrik
Published: June 2016

The crystal structures of the hydrated cationic surfactant benzethonium (Bzth) chloride, bromide, hydroxide, and citrate have been determined by X-ray diffraction analysis and compared with their structures in solution well above their critical micelle concentration. The differences in the nature of the various anions of the four Bzth-X materials lead to unique anion environments and 3-D molecular arrangements. The water molecule in the monoclinic Bzth-Cl or Bzth-Br forms is hydrogen bonded to the halides and particularly to the hydrogens of the methoxy groups of the Bzth moiety notwithstanding the weak Brønsted acidity of the methoxy hydrogens. The citrate strongly interacts with the hydrogens of the methoxy group forming an embedded anionic spherical cluster of a radius of 2.6 Å. The Bzth-OH crystallizes in a hexagonal lattice with two water molecules and reveals free water molecules forming hydrogen bonded channels through the Bzth-OH crystal along the c-axis. The distances between the cationic nitrogen and the halides are 4.04 Å and 4.20 Å, significantly longer than expected for typical van der Waals distances of 3.30 Å. The structures show weakly interacting, alternating apolar and polar layers, which run parallel to the crystallographic a-b planes or a-c planes. The Bzth-X salts were also examined in aqueous solution containing 20% (v/v) ethanol and 1.0 % (v/v) glycerol well above their critical micelle concentration by small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). The [1,1,1] planes for the Bzth Cl or Br, the [0,0,2] and [1,1,0] planes for the Bzth-citrate, the [2,-1,0] planes and the [0,0,1] planes for the Bzth-OH found in the crystalline phase were also present in the solution phase, accordingly, the preservation of these phases are a strong indication of periodicity in the solution phase.
Effects of dense code-switching on executive control
Authors: Hofweber Julia , Marinis Theodoros , Treffers-Daller Jeanine
Published: June 2016

Bilingualism is reported to re-structure executive control networks, but it remains unknown which aspects of the bilingual experience cause this modulation. This study explores the impact of three code-switching types on executive functions: (1) alternation, (2) insertion, and (3) dense code-switching or congruent lexicalisation. Current models hypothesise that different code-switching types challenge different aspects of the executive system because they vary in the extent and scope of language separation. Two groups of German-English bilinguals differing in dense code-switching frequency participated in a flanker task under conditions varying in degree of trial-mixing and resulting demands to conflict-monitoring. Bilinguals engaging in more dense code-switching showed inhibitory advantages in the condition requiring most conflict-monitoring. Moreover, dense code-switching frequency correlated positively with monitoring skills. This suggests that dense code-switching is a key experience shaping bilinguals’ executive functioning and highlights the importance of controlling for participants’ code-switching habits in bilingualism research.