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Zheng Zheng, Xianli Su, Rigui Deng, Constantinos C Stoumpos, Hongyao Xie, Wei Liu, Yonggao Yan, Shiqiang Hao, Ctirad Uher, Chris Wolverton, Mercouri G Kanatzidis, Xinfeng Tang
In this study, a series of Ge1-xMnxTe (x=0-0.21) compounds were prepared by melting-quenching-annealing process combined with Spark Plasma Sintering (SPS). The effect of alloying MnTe into GeTe on the structure and thermoelectric properties of Ge1-xMnxTe is profound. With increasing content of MnTe, the structure of the Ge1-xMnxTe compounds gradually changes from rhombohedral to cubic, and the known R3m to Fm-3m phase transition temperature of GeTe moves from 700 K closer to room temperature. First-principles density functional theory calculations show that alloying MnTe into GeTe decreases the energy difference between the light and heavy valence bands in both the R3m and the Fm-3m structures, enhancing a multi-band character of the valence band edge that increases the hole carrier effective mass...
January 19, 2018: Journal of the American Chemical Society
Rinku Saran, Richard J Curry
Visible spectrum photodetector devices fabricated using molecular crystals of carbon C60 are reported. The devices operate efficiently, extending over and beyond the full visible light spectrum (300-710 nm) with a bias voltage tunable responsivity of 4 mA-0.5 mA W-1 . Across this range of wavelengths, the noise equivalent power of these devices remains below 102 nW Hz-1/2 , providing a detectivity of 107 Jones. The noise current in these devices is found to have a strong dependence on both bias voltage and frequency, varying by 4 orders of magnitude from 1 nA Hz-1/2 to 0...
January 19, 2018: Small
A H Jay Burr, Aaron Vidaver, Ulrich Schreiber, Doug Bruce, Danielle J Donnelly
William (Bill) E. Vidaver (February 2, 1921-August 31, 2017), who did his Ph.D. with Laurence (Larry) R. Blinks at Stanford (1964) and a postdoc with C. Stacy French (1965), taught and did research at Simon Fraser University (SFU) for almost 30 years. Here he published over 80 papers in photosynthesis-related areas co-authored by his graduate students, postdocs, visiting professors and SFU colleagues. He developed a unique high-pressure cuvette for the study of oxygen exchange and studied high-pressure effects in photosynthesis...
January 19, 2018: Photosynthesis Research
Mang Lin, Mark H Thiemens
An ultra-low-level liquid scintillation counting (LSC) technique has been used in measuring radiosulfur (cosmogenic 35S) in natural samples. The ideal half-life of 35S (~87 d) renders it a new way to examine various biogeochemical problems. A major limit of the technique is that complex chemical compositions in atmospheric samples may lead to color quenching of LSC cocktails, a serious problem prolonging the pretreatment time (>1 week) and hampering the accurate determination of 35S. For application of the technique where many of the most important atmospheric chemical processes are examined, significant interferences arise and accurate analysis in small samples is not possible...
January 19, 2018: Analytical Chemistry
Song-Yi Kim, Gwang-Yeob Lee, Gyu-Hyeon Park, Hyeon-Ah Kim, A-Young Lee, Sergio Scudino, Konda Gokuldoss Prashanth, Do-Hyang Kim, Jürgen Eckert, Min-Ha Lee
We report the methods increasing both strength and ductility of aluminum alloys transformed from amorphous precursor. The mechanical properties of bulk samples produced by spark-plasma sintering (SPS) of amorphous Al-Ni-Co-Dy powders at temperatures above 673 K are significantly enhanced by in-situ crystallization of nano-scale intermetallic compounds during the SPS process. The spark plasma sintered Al84Ni7Co3Dy6 bulk specimens exhibit 1433 MPa compressive yield strength and 1773 MPa maximum strength together with 5...
January 18, 2018: Scientific Reports
July Fong, Chaodong Zhang, Renliang Yang, Zhao Zhi Boo, Soon Keat Tan, Thomas E Nielsen, Michael Givskov, Xue-Wei Liu, Wu Bin, Haibin Su, Liang Yang
The threat of antibiotic resistant bacteria has called for alternative antimicrobial strategies that would mitigate the increase of classical resistance mechanism. Many bacteria employ quorum sensing (QS) to govern the production of virulence factors and formation of drug-resistant biofilms. Targeting the mechanism of QS has proven to be a functional alternative to conventional antibiotic control of infections. However, the presence of multiple QS systems in individual bacterial species poses a challenge to this approach...
January 18, 2018: Scientific Reports
Jason K Gurchiek, Han Bao, Maria Agustina Domínguez-Martín, Sarah E McGovern, Claire E Marquardt, Jerome D Roscioli, Soumen Ghosh, Cheryl A Kerfeld, Warren F Beck
The Orange Carotenoid Protein (OCP) mediates nonphotochemical quenching (NPQ) mechanisms in cyanobacteria. A bound ketocarotenoid serves as a sensor of mid-visible light intensity and as a quencher of phycocyanobilin excitons in the phycobilisome. The photochemical mechanism that triggers conversion of the protein from a resting, orange state (OCPO) to an active, red state (OCPR) after optical preparation of the S2 state of the carotenoid remains an open question. We report here that the fluorescence spectrum and quantum yield of the bound carotenoids in OCPO report important details of the motions that follow optical preparation of the S2 state...
January 18, 2018: Journal of Physical Chemistry. B
Nikolai V Priezjev, Maxim A Makeev
Molecular dynamics simulations are carried out to investigate mechanical properties and porous structure of binary glasses subjected to steady shear. The model vitreous systems were prepared via thermal quench at constant volume to a temperature well below the glass transition. The quiescent samples are characterized by a relatively narrow pore size distribution whose mean size is larger at lower glass densities. We find that in the linear regime of deformation, the shear modulus is a strong function of porosity, and the individual pores become slightly stretched while their structural topology remains unaffected...
November 2017: Physical Review. E
Stanislav Burov
This work focuses on quantitative representation of transport in systems with quenched disorder. Explicit mapping of the quenched trap model to continuous time random walk is presented. Linear temporal transformation, t→t/Λ^{1/α}, for a transient process in the subdiffusive regime is sufficient for asymptotic mapping. An exact form of the constant Λ^{1/α} is established. A disorder averaged position probability density function for a quenched trap model is obtained, and analytic expressions for the diffusion coefficient and drift are provided...
November 2017: Physical Review. E
Valerio Volpati, Urna Basu, Sergio Caracciolo, Andrea Gambassi
The dynamic and static critical behaviors of driven and equilibrium lattice gas models are studied in two spatial dimensions. We show that in the short-time regime immediately following a critical quench, the dynamics of the transverse anisotropic order parameter, its autocorrelation, and Binder cumulant are consistent with the prediction of a Gaussian, i.e., noninteracting, effective theory, both for the nonequilibrium lattice gases and, to some extent, their equilibrium counterpart. Such a superuniversal behavior is observed only at short times after a critical quench, while the various models display their distinct behaviors in the stationary states, described by the corresponding, known universality classes...
November 2017: Physical Review. E
M Kumar, S Chatterjee, R Paul, S Puri
We present a comprehensive Monte Carlo study of domain growth in the random-bond XY model with nonconserved kinetics. The presence of quenched disorder slows down domain growth in d=2,3. In d=2, we observe power-law growth with a disorder-dependent exponent on the time scales of our simulation. In d=3, we see the signature of an asymptotically logarithmic growth regime. The scaling functions for the real-space correlation function are seen to be independent of the disorder. However, the same does not apply for the two-time autocorrelation function, demonstrating the breakdown of superuniversality...
October 2017: Physical Review. E
Ranjan Modak, Lev Vidmar, Marcos Rigol
We present two applications of emergent local Hamiltonians to speed up quantum adiabatic protocols for isolated noninteracting and weakly interacting fermionic systems in one-dimensional lattices. We demonstrate how to extract maximal work from initial band-insulating states, and how to adiabatically transfer systems from linear and harmonic traps into box traps. Our protocols consist of two stages. The first one involves a free expansion followed by a quench to an emergent local Hamiltonian. In the second stage, the emergent local Hamiltonian is "turned off" quasistatically...
October 2017: Physical Review. E
Jinfu Liang, Yu An
We perform a computational fluid dynamics simulation of trivalent terbium [Tb(III)] ion line emissions from single-bubble sonoluminescence (SBSL). Our simulation includes dynamic boundary conditions as well as the effects of gas properties and quenching by species, such as nitrite ion (NO_{2}^{-}). Simulation results demonstrate that when the maximum temperature inside a dimly luminescing bubble is relatively low, emission peaks from excited Tb(III) ions are prominent within the emission spectra. As the maximum temperature of the bubble increases, emission peaks of Tb(III) ions fade away relative to the continuum background emission...
December 2017: Physical Review. E
D Sharma, A Erriguible, S Amiroudine
Supercritical fluids when subjected to simultaneous quench and vibration have been known to cause various intriguing flow phenomena and instabilities depending on the relative direction of temperature gradient and vibration. Here we describe a surprising and interesting phenomenon wherein temperature in the fluid falls below the imposed boundary value when the walls are quenched and the direction of vibration is normal to the temperature gradient. We define these regions in the fluid as sink zones, because they act like sink for heat within the fluid domain...
December 2017: Physical Review. E
Valentin Zauner-Stauber, Jad C Halimeh
Using the framework of infinite matrix product states, the existence of an anomalous dynamical phase for the transverse-field Ising chain with sufficiently long-range interactions was first reported in J. C. Halimeh and V. Zauner-Stauber [Phys. Rev. B 96, 134427 (2017)10.1103/PhysRevB.96.134427], where it was shown that anomalous cusps arise in the Loschmidt-echo return rate for sufficiently small quenches within the ferromagnetic phase. In this work we further probe the nature of the anomalous phase through calculating the corresponding Fisher-zero lines in the complex time plane...
December 2017: Physical Review. E
Sebastian Leitmann, Felix Höfling, Thomas Franosch
We study the dynamics of solutions of infinitely thin needles up to densities deep in the semidilute regime by Brownian dynamics simulations. For high densities, these solutions become strongly entangled and the motion of a needle is essentially restricted to a one-dimensional sliding in a confining tube composed of neighboring needles. From the density-dependent behavior of the orientational and translational diffusion, we extract the long-time transport coefficients and the geometry of the confining tube...
July 2017: Physical Review. E
Arkadiusz Jędrzejewski, Anna Chmiel, Katarzyna Sznajd-Weron
We investigate a kinetic Ising model with several single-spin-flip dynamics (including Metropolis and heat bath) on quenched and annealed random regular graphs. As expected, on the quenched structures all proposed algorithms reproduce the same results since the conditions for the detailed balance and the Boltzmann distribution in an equilibrium are satisfied. However, on the annealed graphs the situation is far less clear-the network annealing disturbs the equilibrium moving the system away from it. Consequently, distinct dynamics lead to different steady states...
July 2017: Physical Review. E
S Wüster, J F Corney, J M Rost, P Deuar
We provide the necessary framework for carrying out stochastic positive-P and gauge-P simulations of bosonic systems with long-range interactions. In these approaches, the quantum evolution is sampled by trajectories in phase space, allowing calculation of correlations without truncation of the Hilbert space or other approximations to the quantum state. The main drawback is that the simulation time is limited by noise arising from interactions. We show that the long-range character of these interactions does not further increase the limitations of these methods, in contrast to the situation for alternatives such as the density matrix renormalization group...
July 2017: Physical Review. E
Hanshuang Chen, Guofeng Li, Haifeng Zhang, Zhonghuai Hou
Efficient allocation of limited medical resources is crucial for controlling epidemic spreading on networks. Based on the susceptible-infected-susceptible model, we solve the optimization problem of how best to allocate the limited resources so as to minimize prevalence, providing that the curing rate of each node is positively correlated to its medical resource. By quenched mean-field theory and heterogeneous mean-field (HMF) theory, we prove that an epidemic outbreak will be suppressed to the greatest extent if the curing rate of each node is directly proportional to its degree, under which the effective infection rate λ has a maximal threshold λ_{c}^{opt}=1/〈k〉, where 〈k〉 is the average degree of the underlying network...
July 2017: Physical Review. E
C M Silva da Conceição, R N P Maia
The exact finite-size partition function for the nonhomogeneous one-dimensional (1D) Ising model is found through an approach using algebra operators. Specifically, in this paper we show that the partition function can be computed through a trace from a linear second-order recurrence relation with nonconstant coefficients in matrix form. A relation between the finite-size partition function and the generalized Lucas polynomials is found for the simple homogeneous model, thus establishing a recursive formula for the partition function...
September 2017: Physical Review. E
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