bluuebunny/crossref_metadata_2025 huggingface dataset:
Maximizing the benefits of ART and PrEP in resource-limited settings
Authors: AKUDIBILLAH G. , PANDEY A. , MEDLOCK J.
Published: December 2016

Antiretroviral therapy (ART) is increasingly being used as an HIV-prevention tool, administered to uninfected people with ongoing HIV exposure as pre-exposure prophylaxis (PrEP) and to infected people to reduce their infectiousness. We used a modelling approach to determine the optimal population-level combination of ART and PrEP allocations required in South Africa to maximize programme effectiveness for four outcome measures: new infections, infection-years, death and cost. We considered two different strategies for allocating treatment, one that selectively allocates drugs to sex workers and one that does not. We found that for low treatment availability, prevention through PrEP to the general population or PrEP and ART to sex workers is key to maximizing effectiveness, while for higher drug availability, ART to the general population is optimal. At South Africa's current level of treatment availability, using prevention is most effective at reducing new infections, infection-years, and cost, while using the treatment as ART to the general population best reduces deaths. At treatment levels that meet the UNAIDS's ambitious new 90–90–90 target, using all or almost all treatment as ART to the general population best reduces all four outcome measures considered.
Affective startle potentiation differentiates primary and secondary variants of juvenile psychopathy
Authors: Kimonis Eva R. , Fanti Kostas A. , Goulter Natalie , Hall Jason
Published: December 2016

Individuals with psychopathic traits show an attenuated emotional response to aversive stimuli. However, recent evidence suggests heterogeneity in emotional reactivity among individuals with psychopathic or callous–unemotional (CU) traits in the identification of primary and secondary subtypes, or variants. We hypothesized that primary CU variants will respond with blunted affect to negatively valenced stimuli, whereas individuals with a history of childhood maltreatment, fitting with theoretical conceptualizations of secondary psychopathy, will display heightened emotional reactivity. To test this hypothesis, we examined fear-potentiated startle between CU variants while viewing aversive, pleasant, and neutral scenes. Two hundred thirty-eight incarcerated adolescent (M age = 16.8 years, SD = 1.11 years) boys completed a picture-startle paradigm and self-report questionnaires assessing CU traits, aggressive behavior, and maltreatment. Latent profile analysis of CU trait, aggression, and maltreatment scores identified four classes: primary psychopathy variants (high CU traits, high aggression, low maltreatment; n = 46), secondary psychopathy variants (high CU traits, high aggression, high maltreatment; n = 42), and two nonpsychopathic groups differentiated on maltreatment experience (n = 148). Primary CU variants displayed reduced startle potentiation to aversive images relative to control, maltreated, and also secondary variants that exhibited greater startle modulation. Findings add to a rapidly growing body of literature supporting the possibility of multiple developmental pathways to psychopathic traits (i.e., equifinality), and extend it by finding support for divergent potential biomarkers between primary and secondary CU variants.
Phenotypic and genetic associations between reading and attention-deficit/hyperactivity disorder dimensions in adolescence
Authors: Plourde Vickie , Boivin Michel , Brendgen Mara , Vitaro Frank , Dionne Ginette
Published: December 2016

Multiple studies have shown that reading abilities and attention-deficit/hyperactivity disorder symptoms, mainly inattention symptoms, are phenotypically and genetically associated during childhood. However, few studies have looked at these associations during adolescence to investigate possible developmental changes. The aim of the study is to examine the genetic and environmental etiology of the associations between inattention and hyperactivity reported by parents, and reading accuracy, reading speed, and word reading in a population-based twin sample (Quebec Newborn Twin Study). Participants were between 14 and 15 years of age at the time of testing (N= 668–837). Phenotypic results showed that when nonverbal and verbal abilities were controlled, inattention, but not hyperactivity/impulsivity, was a modest and significant predictor of reading accuracy, reading speed, and word reading. The associations between inattention and all reading abilities were partly explained by genetic and unique environmental factors. However, the genetic correlations were no longer significant after controlling for verbal abilities. In midadolescence, inattention is the attention-deficit/hyperactivity disorder dimension associated with reading abilities, but they could also share genetic factors with general verbal skills.
INTRODUCTION TO MACROECONOMIC DYNAMICS SPECIAL ISSUE ON DYNAMICS OF OIL AND COMMODITIES PRICES
Authors: Manera Matteo , Serletis Apostolos
Published: December 2016

This special issue of Macroeconomic Dynamics presents a timely and fresh body of high-quality research on the complexity and evolution of the international oil markets, the dynamics of the price of oil, and the financialization and the interconnections of oil, energy, and nonenergy commodity markets.
Autism spectrum traits and visual processing in young adults with very low birth weight: the Helsinki Study of Very Low Birth Weight adults
Authors: Wolford E. , Pesonen A.-K. , Heinonen K. , Lahti M. , Pyhälä R. , Lahti J. , Hovi P. , Strang-Karlsson S. , Eriksson J. G. , Andersson S. , Järvenpää A.-L. , Kajantie E. , Räikkönen K.
Published: December 2016

Visual processing problems may be one underlying factor for cognitive impairments related to autism spectrum disorders (ASDs). We examined associations between ASD-traits (Autism-Spectrum Quotient) and visual processing performance (Rey–Osterrieth Complex Figure Test; Block Design task of the Wechsler Adult Intelligence Scale-III) in young adults (mean age=25.0,s.d.=2.1 years) born preterm at very low birth weight (VLBW; <1500 g) (n=101) or at term (n=104). A higher level of ASD-traits was associated with slower global visual processing speed among the preterm VLBW, but not among the term-born group (P<0.04 for interaction). Our findings suggest that the associations between ASD-traits and visual processing may be restricted to individuals born preterm, and related specifically to global, not local visual processing. Our findings point to cumulative social and neurocognitive problems in those born preterm at VLBW.
Oil Residues Accelerate Coastal Wetland Losses
Authors: Jacobsen Elizabeth
Published: December 2016

Coastal wetland loss after an oil spill can be more extensive than after a hurricane.
Regulation of ER stress-induced autophagy by GSK3β-TIP60-ULK1 pathway
Authors: Nie Tiejian , Yang Shaosong , Ma Hongwei , Zhang Lei , Lu Fangfang , Tao Kai , Wang Ronglin , Yang Ruixin , Huang Lu , Mao Zixu , Yang Qian
Published: December 2016

Endoplasmic reticulum (ER) stress is involved in many cellular processes. Emerging evidence suggests that ER stress can trigger autophagy; however, the mechanisms by which ER stress regulates autophagy and its role in this condition are not fully understood. HIV Tat-interactive protein, 60 kDa (TIP60) is a newly discovered acetyltransferase that can modulate autophagy flux by activating ULK1 upon growth factor deprivation. In this study, we investigated the mechanisms by which ER stress induces autophagy. We showed that ER stress activates glycogen synthase kinase-3β (GSK3β). This led to a GSK3β-dependent phosphorylation of TIP60, triggering a TIP60-mediated acetylation of ULK1 and activation of autophagy. Inhibition of either GSK3β or TIP60 acetylation activities significantly attenuated ER stress-induced autophagy. Moreover, enhancing the level of TIP60 attenuated the level of CHOP after ER stress, and reduced the ER stress-induced cell death. In contrast, expression of TIP60 mutant that could not be phosphorylated by GSK3β exacerbated the generation of CHOP and increased the ER stress-induced cell death. These findings reveal that ER stress engages the GSK3β-TIP60-ULK1 pathway to increase autophagy. Attenuation of this pathway renders cells more sensitive to and increases the toxicity of ER stress.
The excellence of La(Sr)Fe(Ni)O3 as an active and efficient cathode for direct CO2 electrochemical reduction at elevated temperatures
Authors: Liu Subiao , Liu Qingxia , Luo Jing-Li
Published: December 2016

To effectively reduce and utilize the atmospheric CO2, electrochemical conversion of CO2 into CO using an efficient and stable cathode in a high temperature solid oxide electrolyzer has attracted extensive interest.
Bio-inspired synthesis of PEGylated polypyrrole@polydopamine nanocomposites as theranostic agents for T1-weighted MR imaging guided photothermal therapy
Authors: Yang Zhe , Ren Jinghua , Ye Zhilan , Zhu Wei , Xiao Liji , Zhang Li , He Qianyuan , Xu Zushun , Xu Haibo
Published: December 2016

Polypyrrole nanoparticle (PPy) based theranostic agents for magnetic resonance imaging (MRI) guided photothermal therapy (PTT) have received increasing attention in recent years.
Highly flexible organometal halide perovskite quantum dot based light-emitting diodes on a silver nanowire–polymer composite electrode
Authors: Zhao Fangchao , Chen Dustin , Chang Shuai , Huang Hailong , Tong Kwing , Xiao Changtao , Chou Shuyu , Zhong Haizheng , Pei Qibing
Published: December 2016

Highly flexible and efficient CH3NH3PbBr3 quantum dot based light-emitting diodes were developed on a silver nanowire–polymer composite electrode.
Hybrid simulations of Alfvén modes driven by energetic particles
Authors: Zhu J. , Ma Z. W. , Wang S.
Published: December 2016

A hybrid kinetic-magnetohydrodynamic code (CLT-K) is developed to study nonlinear dynamics of Alfvén modes driven by energetic particles (EP). A n = 2 toroidicity-induced discrete shear Alfvén eigenmode (TAE)-type energetic particle mode (EPM) with two dominant poloidal harmonics (m = 2 and 3) is first excited and its frequency remains unchanged in the early phase. Later, a new branch of the n = 2 frequency with a single dominant poloidal mode (m = 3) splits from the original TAE-type EPM. The new single m EPM (m = 3) slowly moves radially outward with the downward chirping of the frequency and the mode amplitude remains at a higher level. The original EPM remains at its original position without the frequency chirping, but its amplitude decays with time. Finally, the m = 3 EPM becomes dominant and the frequency falls into the β-induced gap of the Alfvén continuum. The redistribution of the δf in the phase space is consistent with the mode frequency downward chirping and the drifting direction of the resonance region is mainly due to the biased free energy profile. The transition from a TAE-type EPM to a single m EPM is mainly caused by extension of the p = 0 trapped particle resonance in the phase space.
Theoretical study on the charge transfer mechanism at donor/acceptor interface: Why TTF/TCNQ is inadaptable to photovoltaics?
Authors: Li Shuang-Bao , Geng Yun , Duan Yu-Ai , Sun Guang-Yan , Zhang Min , Qiu Yong-Qing , Su Zhong-Min
Published: December 2016

A combined molecular dynamics (MD) and quantum chemical (QC) simulation method is utilized to investigate charge generation mechanism at TTF/TCNQ (tetrathiafulvalene/tetracyanoquinodimethane) heterojunction, which is a controversial donor/acceptor (D/A) interface for organic photovoltaic (OPV) devices. The TTF/TCNQ complexes extracted from MD simulation are classified into parallel and herringbone packings. And then, the amounts of charge transferred from ground states to different excited states and the corresponding energies of charge transfer (CT) state are compared and analyzed using QC simulation. Moreover, the electron transfer/recombination rates for these interfacial configurations are also studied. From these data, we have elucidated the underlying reason why TTF/TCNQ heterojunction is inadaptable to OPV application. One main reason is that large |ΔGCT| (the absolute value of Gibbs free energy change of CT) forms a large energy barrier, limiting exciton dissociation at the TTF/TCNQ heterojunction, and small |ΔGCR| (the absolute value of Gibbs free energy change of charge recombination) performs the easy recombination to the ground state.
Constricted variational density functional theory for spatially clearly separated charge-transfer excitations
Authors: Senn Florian , Park Young Choon
Published: December 2016

Constricted Variational Density Functional Theory (CV-DFT) is known to be one of the successful methods in predicting charge-transfer excitation energies. In this paper, we apply the CV-DFT method to the well-known model systems ethylene-tetrafluoroethylene (C2H4 × C2F4) and the zincbacteriochlorin-bacteriochlorin complex (ZnBC−BC). The analysis of the CV-DFT energies enables us to understand the −1/R charge-transfer behaviour in CV-DFT for large separation distances R. With this we discuss the importance of orbital relaxations using the relaxed version of CV(∞)-DFT, the R-CV(∞)-DFT method. Possible effects of the optimization of the transition matrix for the relaxed self-consistent field version of CV(∞)-DFT, RSCF-CV(∞)-DFT in the case of large fragment separations are shown and we introduce two possible gradient restrictions to avoid the unwanted admixing of other transitions.
Reynolds number and geometry effects in laminar axisymmetric isothermal counterflows
Authors: Scribano Gianfranco , Bisetti Fabrizio
Published: December 2016

The counterflow configuration is a canonical stagnation flow, featuring two opposed impinging round jets and a mixing layer across the stagnation plane. Although counterflows are used extensively in the study of reactive mixtures and other applications where mixing of two streams is required, quantitative data on the scaling properties of the flow field are lacking. The aim of this work is to characterize the velocity and mixing fields in isothermal counterflows over a wide range of conditions. The study features both experimental data from particle image velocimetry and results from detailed axisymmetric simulations. The scaling laws for the nondimensional velocity and mixture fraction are obtained as a function of an appropriate Reynolds number and the ratio of the separation distance of the nozzles to their diameter. In the range of flow configurations investigated, the nondimensional fields are found to depend primarily on the separation ratio and, to a lesser extent, the Reynolds number. The marked dependence of the velocity field with respect to the separation ratio is linked to a high pressure region at the stagnation point. On the other hand, Reynolds number effects highlight the role played by the wall boundary layer on the interior of the nozzles, which becomes less important as the separation ratio decreases. The normalized strain rate and scalar dissipation rate at the stagnation plane are found to attain limiting values only for high values of the Reynolds number. These asymptotic values depend markedly on the separation ratio and differ significantly from the values produced by analytical models. The scaling of the mixing field does not show a limiting behavior as the separation ratio decreases to the smallest practical value considered.
Electromagnetism in terms of quantum measurements
Authors: Andersson Andreas
Published: December 2016

We consider the question whether electromagnetism can be derived from the theory of quantum measurements. It turns out that this is possible, both for quantum and classical electromagnetism, if we use more recent innovations such as smearing of observables and simultaneous measurability. In this way, we justify the use of von Neumann-type measurement models for physical processes. We apply the operational quantum measurement theory to gain insight into fundamental aspects of quantum physics. Interactions of von Neumann type make the Heisenberg evolution of observables describable using explicit operator deformations. In this way, one can obtain quantized electromagnetism as a measurement of a system by another. The relevant deformations (Rieffel deformations) have a mathematically well-defined “classical” limit which is indeed classical electromagnetism for our choice of interaction.
A sub-ms pressure jump setup for time-resolved X-ray scattering
Authors: Möller Johannes , Léonardon Joachim , Gorini Jacques , Dattani Rajeev , Narayanan Theyencheri
Published: December 2016

We present a new experimental setup for time-resolved solution small-angle X-ray scattering (SAXS) studies of kinetic processes induced by sub-ms hydrostatic pressure jumps. It is based on a high-force piezo-stack actuator, with which the volume of the sample can be dynamically compressed. The presented setup has been designed and optimized for SAXS experiments with absolute pressures of up to 1000 bars, using transparent diamond windows and an easy-to-change sample capillary. The pressure in the cell can be changed in less than 1 ms, which is about an order of magnitude faster jump than previously obtained by dynamic pressure setups for SAXS. An additional temperature control offers the possibility for automated mapping of p-T phase diagrams. Here we present the technical specifications and first experimental data taken together with a preview of new research opportunities enabled by this setup.
Magnetic proximity effect and shell-ferromagnetism in metastable Ni50Mn45Ga5
Authors: Krenke Thorsten , Çakır Aslı , Scheibel Franziska , Acet Mehmet , Farle Michael
Published: December 2016

The present study on magnetic and structural properties of Ni50Mn45Ga5 confirms that structural metastability is an inherent property of Ni50Mn50–xXx Heusler alloys with X as In, Ga, and Sn. The ternary alloy transforms during temper-annealing into a dual-phase composite alloy. The two phases are identified to be cubic L21, Ni50Mn25Ga25, and tetragonal L10 Ni50Mn50. Depending on the annealing temperature, the magnetic-proximity effect giving rise to shell-ferromagnetism has been observed when annealing is carried out under an external magnetic field. The upper and lower remanence values MR+ and MR− have the same sign even at high temperatures. Such alloys can be promising candidates for heat- and magnetic-field-resistant magnetic recording media.
Experimental room temperature hohlraum performance study on the National Ignition Facility
Authors: Ralph J. E. , Strozzi D. , Ma T. , Moody J. D. , Hinkel D. E. , Callahan D. A. , MacGowan B. J. , Michel P. , Kline J. L. , Glenzer S. H. , Albert F. , Benedetti L. R. , Divol L. , MacKinnon A. J. , Pak A. , Rygg J. R. , Schneider M. B. , Town R. P. J. , Widmann K. , Hsing W. , Edwards M. J.
Published: December 2016

Room temperature or “warm” (273 K) indirect drive hohlraum experiments have been conducted on the National Ignition Facility with laser energies up to 1.26 MJ and compared to similar cryogenic or “cryo” (∼20 K) experiments. Warm experiments use neopentane (C5H12) as the low pressure hohlraum fill gas instead of helium, and propane (C3H8) to replace the cryogenic DT or DHe3 capsule fill. The increased average Z of the hohlraum fill leads to increased inverse bremsstrahlung absorption and an overall hotter hohlraum plasma in simulations. The cross beam energy transfer (CBET) from outer laser beams (pointed toward the laser entrance hole) to inner beams (pointed at the equator) was inferred indirectly from measurements of Stimulated Raman Scattering (SRS). These experiments show that a similar hot spot self-emission shape can be produced with less CBET in warm hohlraums. The measured inner cone SRS reflectivity (as a fraction of incident power neglecting CBET) is ∼2.5× less in warm than cryo shots with similar hot spot shapes, due to a less need for CBET. The measured outer-beam stimulated the Brillouin scattering power that was higher in the warm shots, leading to a ceiling on power to avoid the optics damage. These measurements also show that the CBET induced by the flow where the beams cross can be effectively mitigated by a 1.5 Å wavelength shift between the inner and outer beams. A smaller scale direct comparison indicates that warm shots give a more prolate implosion than cryo shots with the same wavelength shift and pulse shape. Finally, the peak radiation temperature was found to be between 5 and 7 eV higher in the warm than the corresponding cryo experiments after accounting for differences in backscatter.
Spectral assignment and orientational analysis in a vibrational sum frequency generation study of DPPC monolayers at the air/water interface
Authors: Feng Rong-Juan , Li Xia , Zhang Zhen , Lu Zhou , Guo Yuan
Published: December 2016

The interfacial behavior of the benchmark zwitterionic phospholipid molecule dipalmitoylphosphatidylcholine (DPPC) has been extensively investigated by surface-selective vibrational sum frequency generation spectroscopy (VSFG). However, there is still a lack of agreement between various orientational measurements of phospholipid monolayers at the air/water interface, mainly because of the difficulty in assigning congested VSFG features. In this study, polarization-dependent VSFG measurements reveal a frequency shift between the in-plane and out-of-plane antisymmetric stretching modes of the terminal methyl groups in the DPPC alkyl tails, favoring the model of Cs local symmetry rather than the previously assumed C3v symmetry. Further VSFG experiments of isotopically labeled DPPC successfully capture the vibrational signatures of the glycerol backbone. With the newly derived VSFG polarization selection rules for Cs symmetry and the refreshed spectral assignments, the average tilt angles of the alkyl tail groups, choline headgroup, and glycerol backbone of DPPC molecules can all be determined, showing the powerful capability of VSFG spectroscopy in revealing the structural details at interfaces. The VSFG polarization dependence rules and the orientational analysis procedures developed for Cs symmetry in this work are applicable to other bulky molecules in which the methyl group cannot freely rotate, and they therefore have general applications in future VSFG studies.
Nonlinear effects associated with fast magnetosonic waves and turbulent magnetic amplification in laboratory and astrophysical plasmas
Authors: Tiwary PremPyari , Sharma Swati , Sharma Prachi , Singh Ram Kishor , Uma R. , Sharma R. P.
Published: December 2016

This paper presents the spatio-temporal evolution of magnetic field due to the nonlinear coupling between fast magnetosonic wave (FMSW) and low frequency slow Alfvén wave (SAW). The dynamical equations of finite frequency FMSW and SAW in the presence of ponderomotive force of FMSW (pump wave) has been presented. Numerical simulation has been carried out for the nonlinear coupled equations of finite frequency FMSW and SAW. A systematic scan of the nonlinear behavior/evolution of the pump FMSW has been done for one of the set of parameters chosen in this paper, using the coupled dynamical equations. Filamentation of fast magnetosonic wave has been considered to be responsible for the magnetic turbulence during the laser plasma interaction. The results show that the formation and growth of localized structures depend on the background magnetic field but the order of amplification does not get affected by the magnitude of the background magnetic field. In this paper, we have shown the relevance of our model for two different parameters used in laboratory and astrophysical phenomenon. We have used one set of parameters pertaining to experimental observations in the study of fast ignition of laser fusion and hence studied the turbulent structures in stellar environment. The other set corresponds to the study of magnetic field amplification in the clumpy medium surrounding the supernova remnant Cassiopeia A. The results indicate considerable randomness in the spatial structure of the magnetic field profile in both the cases and gives a sufficient indication of turbulence. The turbulent spectra have been studied and the break point has been found around k which is consistent with the observations in both the cases. The nonlinear wave-wave interaction presented in this paper may be important in understanding the turbulence in the laboratory as well as the astrophysical phenomenon.
The motion of a 3D toroidal bubble and its interaction with a free surface near an inclined boundary
Authors: Liu Y. L. , Wang Q. X. , Wang S. P. , Zhang A. M.
Published: December 2016

The numerical modelling of 3D toroidal bubble dynamics is a challenging problem due to the complex topological transition of the flow domain, and physical and numerical instabilities, associated with jet penetration through the bubble. In this paper, this phenomenon is modelled using the boundary integral method (BIM) coupled with a vortex ring model. We implement a new impact model consisting of the refined local mesh near the impact location immediately before and after impact, and a surgical cut at a high resolution forming a smooth hole for the transition from a singly connected to doubly connected form. This enables a smooth transition from a singly connected bubble to a toroidal bubble. The potential due to a vortex ring is reduced to the line integral along the vortex ring. A new mesh density control technique is described to update the bubble and free surfaces, which provides a high mesh quality of the surfaces with the mesh density in terms of the curvature distribution of the surface. The pressure distribution in the flow field is calculated by using the Bernoulli equation, where the partial derivative of the velocity potential in time is calculated using the BIM model to avoid numerical instabilities. Experiments are carried out for the interaction of a spark generated bubble with a free surface near a boundary, which is captured by using a high speed camera. Our numerical results agree well with the experimental images, for the bubble and free surface shapes for both before and after jet impact. New results are analyzed for the interaction of a toroidal bubble with a free surface near a vertical boundary and a sloping boundary, at both negative and positive angles to the vertical, without and with buoyancy, respectively. After jet impact, the bubble becomes a bubble ring, whose cross section is much thinner at the distal side from the boundary. It subsequently breaks into a crescent shaped bubble. The free surface displays singular features at its intersection with an inclined boundary.
Geometric quantization of Dirac manifolds
Authors: Hirota Yuji
Published: December 2016

We extend a prequantization procedure to Dirac manifolds by using singular distributions obtained from 2-cocycles associated with Dirac structures. Given a Dirac manifold (M, D), we describe a prequantization formula in terms of a Lie algebroid connection and show that it is a representation of a Poisson algebra consisting of admissible functions on (M, D) on the space of global sections of a hermitian line bundle over M if and only if the curvature derived from the Lie algebroid connection is represented by a skew-symmetric operation which is naturally defined for (M, D). Moreover, we describe a necessary and sufficient condition for the prequantization formula to be the representation in terms of a Lie algebroid cohomology. We introduce the notion of a polarization for (M, D) and construct a representation of a subalgebra of admissible functions. Lastly, we discuss procedures for quantization in two cases: where M is compact and where M is not compact.
Temperature field driven polar nanoregions in KTa1−xNbxO3
Authors: Tan Peng , Tian Hao , Hu Chengpeng , Meng Xiangda , Mao Chenyang , Huang Fei , Shi Guang , Zhou Zhongxiang
Published: December 2016

Correlated disorder, which exists more widely in materials than crystalline phases, is beneficial for the improvement of material properties. KTa1−xNbxO3 (KTN), a type of perovskite crystal, is recognized as a correlated disorder system in the vicinity of the Curie temperature, Tc, because of the existence of polar nanoregions (PNRs), which yield scale-free optics, reprogrammable soliton nonlinearity, and giant electro-optic effects. In this letter, we propose the mechanisms for induced PNR reorientation under a specific temperature field and manipulate PNRs using a temperature gradient in KTN to modulate light polarization, reduce light scattering, and enhance the electro-optic effect. A designed temperature gradient provides an effective way to drive correlated disordered PNRs, which could guide the exploitation of PNRs and is significant for correlated disorder applications.
Transport, geometrical, and topological properties of stealthy disordered hyperuniform two-phase systems
Authors: Zhang G. , Stillinger F. H. , Torquato S.
Published: December 2016

Disordered hyperuniform many-particle systems have attracted considerable recent attention, since they behave like crystals in the manner in which they suppress large-scale density fluctuations, and yet also resemble statistically isotropic liquids and glasses with no Bragg peaks. One important class of such systems is the classical ground states of “stealthy potentials.” The degree of order of such ground states depends on a tuning parameter χ. Previous studies have shown that these ground-state point configurations can be counterintuitively disordered, infinitely degenerate, and endowed with novel physical properties (e.g., negative thermal expansion behavior). In this paper, we focus on the disordered regime (0 < χ < 1/2) in which there is no long-range order and control the degree of short-range order. We map these stealthy disordered hyperuniform point configurations to two-phase media by circumscribing each point with a possibly overlapping sphere of a common radius a: the “particle” and “void” phases are taken to be the space interior and exterior to the spheres, respectively. The hyperuniformity of such two-phase media depends on the sphere sizes: While it was previously analytically proven that the resulting two-phase media maintain hyperuniformity if spheres do not overlap, here we show numerically that they lose hyperuniformity whenever the spheres overlap. We study certain transport properties of these systems, including the effective diffusion coefficient of point particles diffusing in the void phase as well as static and time-dependent characteristics associated with diffusion-controlled reactions. Besides these effective transport properties, we also investigate several related structural properties, including pore-size functions, quantizer error, an order metric, and percolation thresholds. We show that these transport, geometrical, and topological properties of our two-phase media derived from decorated stealthy ground states are distinctly different from those of equilibrium hard-sphere systems and spatially uncorrelated overlapping spheres. As the extent of short-range order increases, stealthy disordered two-phase media can attain nearly maximal effective diffusion coefficients over a broad range of volume fractions while also maintaining isotropy, and therefore may have practical applications in situations where ease of transport is desirable. We also show that the percolation threshold and the order metric are positively correlated with each other, while both of them are negatively correlated with the quantizer error. In the highly disordered regime (χ → 0), stealthy point-particle configurations are weakly perturbed ideal gases. Nevertheless, reactants of diffusion-controlled reactions decay much faster in our two-phase media than in equilibrium hard-sphere systems of similar degrees of order, and hence indicate that the formation of large holes is strongly suppressed in the former systems.
Time-resolved temperature and number density measurements in a repetitively pulsed nanosecond-duration discharge
Authors: Manoharan Rounak , Boyson Toby K. , O'Byrne Sean
Published: December 2016

This paper presents a fast detection technique using diode laser absorption spectroscopy as an optical diagnostic tool to measure time-resolved temperature and number density in a repetitively pulsed nanosecond-duration discharge. Argon atoms in the 1s3 metastable state were optically probed by current scanning a vertical cavity surface emitting laser diode over the 1s3→2p4 transition at 794 nm. Temperature and number density measurements are presented at pulse energies from 20 μJ to 300 μJ, at a constant pressure of 2.67 kPa and 10 kHz repetition frequency. A time resolution of 2 ns was achieved for the measurements during and after the discharge pulse. We demonstrate the method used to make nanosecond resolution measurements, the precision of this technique and the effect of pulse energy on the translational temperature and number density of the metastable atoms. Our measurements show that, for small input pulse energies, the peak temperature of the argon atoms in the 1s3 state can exceed ambient room temperature by up to an order of magnitude.
Effects of a Xe dopant on an Ar gas-puff implosion on Z
Authors: Apruzese J. P. , Giuliani J. L. , Ouart N. D. , Tangri V. , Harvey-Thompson A. J. , Jones B. , Jennings C. A. , Hansen S. B. , Ampleford D. J. , Rochau G. A. , Coverdale C. A.
Published: December 2016

Two Ar gas-puff experiments, each using loads consisting of two annuli and a center jet, were recently performed on Sandia National Laboratories' Z machine. These shots had the same load except that one of them (Z2603) employed a Xe dopant of 0.8% by number in the jet, which was not present in the otherwise identical Z2605. The extensive diagnostics deployed in these experiments reveal that the presence of this small fraction of Xe had a significant effect on the emitted K-shell radiation. Use of the Xe dramatically reduced the Ar K-shell yield from 373 ± 9% to 129 ± 9% kJ. However, the total yield increased, from 1.02 ± 17% to 1.14 ± 17% MJ. Also, the K-shell power pulse for Z2603 exhibited two nearly equal peaks separated by ∼5 ns, but that of Z2605 consisted of a more conventional single peak. Analysis of time- and space resolved K-shell spectra using a detailed atomic model for Ar ions indicates that a much greater fraction of the load mass was heated to the K-shell in the non-Xe shot Z2605. Previous average-ion atomic calculations of Xe cooling rates [Post et al., At. Data Nucl. Data Tables 20, 397 (1977)] show that the radiative cooling of the small 0.8% Xe fraction is nonetheless significant compared to that of the Ar and is therefore likely responsible for the differences in the shots.
Design of experimental setup for supercritical CO2 jet under high ambient pressure conditions
Authors: Shi Huaizhong , Li Gensheng , He Zhenguo , Wang Haizhu , Zhang Shikun
Published: December 2016

With the commercial extraction of hydrocarbons in shale and tight reservoirs, efficient methods are needed to accelerate developing process. Supercritical CO2 (SC-CO2) jet has been considered as a potential way due to its unique fluid properties. In this article, a new setup is designed for laboratory experiment to research the SC-CO2 jet’s characteristics in different jet temperatures, pressures, standoff distances, ambient pressures, etc. The setup is composed of five modules, including SC-CO2 generation system, pure SC-CO2 jet system, abrasive SC-CO2 jet system, CO2 recovery system, and data acquisition system. Now, a series of rock perforating (or case cutting) experiments have been successfully conducted using the setup about pure and abrasive SC-CO2 jet, and the results have proven the great perforating efficiency of SC-CO2 jet and the applications of this setup.
Current induced magnetization dynamics and magnetization switching in superconducting ferromagnetic hybrid (F|S|F) structures
Authors: Acharjee Saumen , Goswami Umananda Dev
Published: December 2016

We investigate the current induced magnetization dynamics and magnetization switching in an unconventional p-wave superconductor sandwiched between two misaligned ferromagnetic layers by numerically solving the Landau-Lifshitz-Gilbert equation modified with current induced Slonczewski's spin torque term. A modified form of the Ginzburg-Landau free energy functional has been used for this purpose. We demonstrated the possibility of current induced magnetization switching in the spin-triplet ferromagnetic superconducting hybrid structures with a strong easy axis anisotropy and the condition for magnetization reversal. The switching time for such arrangement is calculated and is found to be highly dependent on the magnetic configuration along with the biasing current. This study would be useful in designing the practical superconducting-spintronic devices.
Enhanced saturation magnetization in perpendicular L1–MnAl films upon low substitution of Mn by 3d transition metals
Authors: Sato T. , Ohsuna T. , Kaneko Y.
Published: December 2016

In order to enhance the saturation magnetization (Ms) of a L10−MnAl alloy, which is a promising candidate for use in rare-earth free permanent magnets, this work assesses perpendicular L10−MnAl films in which Mn is substituted by the 3d transition metals (TMs) Fe, Co, Ni, or Cu. In the films for which the TM is Fe or Ni, the lattice constant, a, of the L10−(Mn, TM)Al phase increases from 0.390 to 0.397 nm with a substitution amount, x, of 5 at. %. Simultaneously, the lattice constant, c, decreases from 0.355 to 0.350 nm, such that the lattice ratio, c/a, changes from 0.91 to 0.88. Upon increasing x to more than 5 at. %, an unknown phase (either Mn or another Mn−Al phase) forms together with the L10−(Mn, TM)Al phase. The Ms of the MnAl film increases from 360 to more than 400 emu/cm3 with an increasing x when substituting Fe or Ni for Mn. In addition, although a MnAl film without substitution shows a Ms of 360 emu/cm3 and a Hc of 4.1 kOe, a MnAl film substituted with Fe at x = 2.5 at. % exhibits a Ms of 400 emu/cm3 and a Hc of 3.8 kOe. These results suggest that the lattice changes induced in the L10−MnAl alloy upon substituting Fe or Ni for Mn, corresponding to an expansion of the interatomic distance between (Mn, TM) atoms, are an effective means of enhancing the Ms value of the alloy.
Hybrid complementary circuits based on p-channel organic and n-channel metal oxide transistors with balanced carrier mobilities of up to 10 cm2/Vs
Authors: Isakov Ivan , Paterson Alexandra F. , Solomeshch Olga , Tessler Nir , Zhang Qiang , Li Jun , Zhang Xixiang , Fei Zhuping , Heeney Martin , Anthopoulos Thomas D.
Published: December 2016

We report the development of hybrid complementary inverters based on p-channel organic and n-channel metal oxide thin-film transistors (TFTs) both processed from solution at <200 °C. For the organic TFTs, a ternary blend consisting of the small-molecule 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene, the polymer indacenodithiophene-benzothiadiazole (C16IDT-BT) and the p-type dopant C60F48 was employed, whereas the isotype In2O3/ZnO heterojunction was used for the n-channel TFTs. When integrated on the same substrate, p- and n-channel devices exhibited balanced carrier mobilities up to 10 cm2/Vs. Hybrid complementary inverters based on these devices show high signal gain (>30 V/V) and wide noise margins (70%). The moderate processing temperatures employed and the achieved level of device performance highlight the tremendous potential of the technology for application in the emerging sector of large-area microelectronics.
A versatile UHV transport and measurement chamber for neutron reflectometry under UHV conditions
Authors: Syed Mohd A. , Pütter S. , Mattauch S. , Koutsioubas A. , Schneider H. , Weber A. , Brückel T.
Published: December 2016

We report on a versatile mini ultra-high vacuum (UHV) chamber which is designed to be used on the MAgnetic Reflectometer with high Incident Angle of the Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum in Garching, Germany. Samples are prepared in the adjacent thin film laboratory by molecular beam epitaxy and moved into the compact chamber for transfer without exposure to ambient air. The chamber is based on DN 40 CF flanges and equipped with sapphire view ports, a small getter pump, and a wobble stick, which serves also as sample holder. Here, we present polarized neutron reflectivity measurements which have been performed on Co thin films at room temperature in UHV and in ambient air in a magnetic field of 200 mT and in the Q-range of 0.18 Å−1. The results confirm that the Co film is not contaminated during the polarized neutron reflectivity measurement. Herewith it is demonstrated that the mini UHV transport chamber also works as a measurement chamber which opens new possibilities for polarized neutron measurements under UHV conditions.
Ink-jet printed semiconducting carbon nanotube ambipolar transistors and inverters with chemical doping technique using polyethyleneimine
Authors: Lee Juhee , Yoon Jinsu , Choi Bongsik , Lee Dongil , Kim Dong Myong , Kim Dae Hwan , Choi Yang-Kyu , Choi Sung-Jin
Published: December 2016

We demonstrate an ink-jet printed ambipolar transistor and inverter based on a semiconducting carbon nanotube (CNT) network as a channel by employing a solution-based chemical doping technique with an amine-rich polyethyleneimine (PEI) polymer. The PEI polymer has been reported as an efficient electron dopant and thus contributes to enhancing n-type conduction in CNT transistors. However, because of the presence of ambient oxygen and moisture and the hygroscopicity of the PEI polymer, their p-type conduction did not seem to be effectively reduced, resulting in rather ambipolar conduction. Therefore, we utilize a simple solution-based doping technique to convert p-type semiconducting CNT transistors into ambipolar transistors and fabricate the ambipolar CNT transistor by combining a cost-effective ink-jet printing technique and a simple spin-coating method. Finally, the electrical performance of the logic inverter consisting of identical two ambipolar CNT transistors is also evaluated and optimized by adjusting the concentration of PEI polymer.
High recoverable energy density over a wide temperature range in Sr modified (Pb,La)(Zr,Sn,Ti)O3 antiferroelectric ceramics with an orthorhombic phase
Authors: Zhang Qingfeng , Tong Huifen , Chen Jian , Lu Yinmei , Yang Tongqing , Yao Xi , He Yunbin
Published: December 2016

Via incorporation of Sr2+ into (Pb,La)(Zr,Sn,Ti)O3, high recoverable energy density (Ure) is achieved in (Pb,Sr,La)(Zr,Sn,Ti)O3 (PSLZST) ceramics. All Sr2+ modified ceramics exhibit orthorhombic antiferroelectric (AFE) characteristics, and have higher ferroelectric-AFE phase switching electric field (EA, proportional to Ure) than the base composition with a tetragonal AFE phase. By properly adjusting the Sr2+ content, the Ure of PSLZST ceramics is greatly improved. This is attributed to the substitution of Pb2+ by Sr2+ with a smaller ion radius, which decreases the tolerance factor leading to enhanced AFE phase stability and thus increased EA. The best energy storage properties are achieved in the PSLZST ceramic with a Sr2+ content of 0.015. It exhibits a maximum room-temperature Ure of 5.56 J/cm3, the highest value achieved so far for dielectric ceramics prepared by a conventional sintering technique, and very small energy density variation (<12%) in the range of 30–90 °C. The high Ure (>4.9 J/cm3) over a wide temperature range implies attractive prospects of this material for developing high power capacitors usable under various conditions.
Spin galvanic effect at the conducting SrTiO3 surfaces
Authors: Zhang Wenxu , Wang Qiuru , Peng Bin , Zeng Huizhong , Soh Wee Tee , Ong Chong Kim , Zhang Wanli
Published: December 2016

The (001) surface of SrTiO3 were transformed from insulating to conducting after Ar+ irradiation, producing a quasi two-dimensional electron gas (2DEG). This conducting surface layer can introduce Rashba spin orbital coupling due to the broken inversion symmetry normal to the plane. The spin splitting of such a surface has recently been demonstrated by magneto-resistance and angular resolved photoemission spectra measurements. Here, we present experiments evidencing a large spin-charge conversion at the conducting surface. We use spin pumping to inject a spin current from NiFe film into the surface, and measure the resulting charge current. The results indicate that the Rashba effect at the surface can be used for efficient charge-spin conversion. The conversion efficiency measured by the ratio of the spin flow density to the charge flow density is about 0.23 nm. This value is on the same order as the interfaces in metallic multilayers and 2DEG of LaAlO3/SrTiO3. In this point of view, the conducting SrTiO3 surface provides another solution for oxide spintronics.
The role of TM’s (M’s) d valence electrons in TM@X12 and M@X12 clusters
Authors: Tan Zhiyun , Zhou Tingwei , Yang Youchang
Published: December 2016

Using the density functional theory method, the icosahedral TM@X12 (M@X12) clusters (TM=Mn, Tc, Re; M=Zn, Cd, Hg; and X=Sn, Ge), which are composed of Sn12 (Ge12) shell covering a single TM (M) atom, have been systematically examined to explore the role of TM’s (M’s) d valence electrons playing in the clusters. The results show that the magnetism originate from the contribution of TM’s d valence electrons to TM@X12 clusters, where TM’s (M’s) d valence electrons are not included in the superatomic electronic states to TM@X12 (M@X12) clusters. Taking into account the structural stability (imaginary frequency, binding energy, embedding energy, and core-shell interaction) as well as the chemical stability (HOMO-LUMO gap) after, we proposed that TM@X12 and M@X12 clusters can be assigned as the protyle superatoms. Furthermore, the results suggest that M@C60 clusters can not be superatoms, because their negative embedding energies and the distance from the center atom (M) to C atom is larger than the sum of their Van Waals radii. Interestingly enough, we may obtain a simple judging method: for a magnetic superatom, the smaller the energy gap between the highest occupied magnetic state (HOMS) and Fermi level or HOMO (MOgap, or MFgap), the easier on the change of its spin magnetic moment.
Stochastic domain wall depinning in permalloy nanowires with various types of notches
Authors: Gao Y. , You B. , Yang H. L. , Zhan Q. F. , Li Z. , Lei N. , Zhao W. S. , Wu J. , Tu H. Q. , Wang J. , Wei L. J. , Zhang W. , Xu Y. B. , Du J.
Published: December 2016

Stochastic phenomena in magnetic nanowires based on domain wall (DW) motion is scientifically important thus to understand and control such behaviors are very meaningful. Here we report on the investigation of pinning and depinning of DWs in permalloy nanowires with six types of longitudinally asymmetric notches using focused magneto-optic Kerr effect (FMOKE) magnetometer and magnetic force microscopy (MFM). The hysteresis loops obtained by FMOKE indicate the generation of one or two distinct depinning fields by creating one notch close to the edge of the nanowires, in comparison multiple depinning processes occur in the nanowires with two identical notches symmetrically placed along the transverse direction, indicating more remarkable stochastic DW depinning phenomena. The MFM images verify the existence of DW in each type of nanowires and the DW sizes in the latter kind of nanowires are generally larger than those in the former ones. These observations can be explained by considering the thermal perturbation and edge or surface roughness effects in nanowires.