Corrigan-Ramond Extension of QCD at Nonzero Baryon Density

DEFF Research Database (Denmark)

T. Frandsen, M.; Kouvaris, Christoforos; Sannino, F.

2006-01-01

We investigate the Corrigan-Ramond extension of one massless flavor Quantum Chromo Dynamics at nonzero quark chemical potential. Since the extension requires the fermions to transform in the two index antisymmetric representation of the gauge group, one finds that the number of possible channels ......-Grigoriev-Rubakov chiral waves. We discover, differently from the 't Hooft limit, the possibility of a colored chiral wave breaking the color symmetry as well as translation invariance....... is richer than in the 't Hooft limit. We first discuss the diquark channels and show that for a number of colors larger than three a new diquark channel appears. We then study the infinite number of color limit and show that the Fermi surface is unstable to the formation of the Deryagin...

The quenched limit of lattice QCD at non-zero baryon number

International Nuclear Information System (INIS)

Engels, J.; Kaczmarek, O.; Karsch, F.; Laermann, E.

1999-01-01

We discuss the thermodynamics of gluons in the background of static quark sources. In order to do so we formulate the quenched limit of QCD at non-zero baryon number. A first numerical analysis of this system shows that it undergoes a smooth deconfining transition. We find evidence for a region of coexisting phases that becomes broader with increasing baryon number density. Although the action is in our formulation explicitly Z(3) symmetric the Polyakov loop expectation value becomes non-zero already in the low temperature phase. It indicates that the heavy quark potential stays finite at large distances, i.e. the string between static quarks breaks at non-zero baryon number density already in the hadronic phase

Scattering phases for particles with nonzero orbital momenta and resonance regimes in the Pais approximation

International Nuclear Information System (INIS)

Bruk, Yulii M; Voloshchuk, Aleksandr N

2012-01-01

The functional Pais equation for scattering phases with nonzero orbital momenta is solved in the case of low-energy particles. For short-range screened potentials, in particular, Yukawa or Thomas-Fermi potentials, the Pais equation is shown to reduce to transcendental equations. For the potentials varying ∼r - n , n > 0, simple algebraic equations are obtained for determining the phases δ l , l≠0. Possible applications of the Pais approximation to the problem of finding resonance regimes in the scattering of low-energy particles with nonzero orbital momenta are discussed. (methodological notes)

Exact effective action for (1+1)-dimensional fermions in an Abelian background at finite temperature and chemical potential

International Nuclear Information System (INIS)

Maciel, Soraya G.; Perez, Silvana

2008-01-01

In this paper we study the effects of a nonzero chemical potential in (1+1)-dimensional quantum field models at finite temperature. We particularly consider massless fermions in an Abelian gauge field background and calculate the effective action by evaluating the n-point functions. We find that the structure of the amplitudes corresponds to a generalization of the structure noted earlier in a calculation without a chemical potential (the associated integrals carry the dependence on the chemical potential). Our calculation shows that the chiral anomaly is unaffected by the presence of a chemical potential at finite temperature. However, unlike in the absence of a chemical potential, odd point functions do not vanish. We trace this to the fact that in the presence of a chemical potential the generalized charge conjugation symmetry of the theory allows for such amplitudes. In fact, we find that all the even point functions are even functions of μ, while the odd point functions are odd functions of μ which is consistent with this generalized charge conjugation symmetry. We show that the origin of the structure of the amplitudes is best seen from a formulation of the theory in terms of left- and right-handed spinors. The calculations are also much simpler in this formulation and it clarifies many other aspects of the theory.

Density profiles of small Dirac operator eigenvalues for two color QCD at nonzero chemical potential compared to matrix models

OpenAIRE

Akemann, G; Bittner, E; Lombardo, M; Markum, H; Pullirsch, R

2004-01-01

We investigate the eigenvalue spectrum of the staggered Dirac matrix in two color QCD at finite chemical potential. The profiles of complex eigenvalues close to the origin are compared to a complex generalization of the chiral Gaussian Symplectic Ensemble, confirming its predictions for weak and strong non-Hermiticity. They differ from the QCD symmetry class with three colors by a level repulsion from both the real and imaginary axis.

Density profiles of small Dirac operator eigenvalues for two color QCD at nonzero chemical potential compared to matrix models

International Nuclear Information System (INIS)

Akemann, Gernot; Bittner, Elmar; Lombardo, Maria-Paola; Markum, Harald; Pullirsch, Rainer

2005-01-01

We investigate the eigenvalue spectrum of the staggered Dirac matrix in two color QCD at finite chemical potential. The profiles of complex eigenvalues close to the origin are compared to a complex generalization of the chiral Gaussian Symplectic Ensemble, confirming its predictions for weak and strong non-Hermiticity. They differ from the QCD symmetry class with three colors by a level repulsion from both the real and imaginary axis

Non-zero total correlation means non-zero quantum correlation

International Nuclear Information System (INIS)

Li, Bo; Chen, Lin; Fan, Heng

2014-01-01

We investigated the super quantum discord based on weak measurements. The super quantum discord is an extension of the standard quantum discord defined by projective measurements and also describes the quantumness of correlations. We provide some equivalent conditions for zero super quantum discord by using quantum discord, classical correlation and mutual information. In particular, we find that the super quantum discord is zero only for product states, which have zero mutual information. This result suggests that non-zero correlations can always be detected using the quantum correlation with weak measurements. As an example, we present the assisted state-discrimination method.

Calculation of baryon chemical potential and strangeness chemical potential in resonance matter

International Nuclear Information System (INIS)

Fu Yuanyong; Hu Shouyang; Lu Zhongdao

2006-01-01

Based on the high energy heavy-ion collisions statistical model, the baryon chemical potential and strangeness chemical potential are calculated for resonance matter with net baryon density and net strangeness density under given temperature. Furthermore, the relationship between net baryon density, net strangeness density and baryon chemical potential, strangeness chemical potential are analyzed. The results show that baryon chemical potential and strangeness chemical potential increase with net baryon density and net strangeness density increasing, the change of net baryon density affects baryon chemical potential and strangeness chemical potential more strongly than the change of net strangeness density. (authors)

The multi-flavor Schwinger model with chemical potential. Overcoming the sign problem with matrix product states

International Nuclear Information System (INIS)

Banuls, Mari Carmen; Cirac, J. Ignacio; Kuehn, Stefan; Cichy, Krzysztof

2016-11-01

During recent years there has been an increasing interest in the application of matrix product states, and more generally tensor networks, to lattice gauge theories. This non-perturbative method is sign problem free and has already been successfully used to compute mass spectra, thermal states and phase diagrams, as well as real-time dynamics for Abelian and non-Abelian gauge models. In previous work we showed the suitability of the method to explore the zero-temperature phase structure of the multi-flavor Schwinger model at non-zero chemical potential, a regime where the conventional Monte Carlo approach suffers from the sign problem. Here we extend our numerical study by looking at the spatially resolved chiral condensate in the massless case. We recover spatial oscillations, similar to the theoretical predictions for the single-flavor case, with a chemical potential dependent frequency and an amplitude approximately given by the homogeneous zero density condensate value.

The multi-flavor Schwinger model with chemical potential. Overcoming the sign problem with matrix product states

Energy Technology Data Exchange (ETDEWEB)

Banuls, Mari Carmen; Cirac, J. Ignacio; Kuehn, Stefan [Max-Planck-Institut fuer Quantenoptik (MPQ), Garching (Germany); Cichy, Krzysztof [Frankfurt Univ. (Germany). Inst. fuer Theoretische Physik; Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Saito, Hana [AISIN AW Co., Ltd., Aichi (Japan)

2016-11-15

During recent years there has been an increasing interest in the application of matrix product states, and more generally tensor networks, to lattice gauge theories. This non-perturbative method is sign problem free and has already been successfully used to compute mass spectra, thermal states and phase diagrams, as well as real-time dynamics for Abelian and non-Abelian gauge models. In previous work we showed the suitability of the method to explore the zero-temperature phase structure of the multi-flavor Schwinger model at non-zero chemical potential, a regime where the conventional Monte Carlo approach suffers from the sign problem. Here we extend our numerical study by looking at the spatially resolved chiral condensate in the massless case. We recover spatial oscillations, similar to the theoretical predictions for the single-flavor case, with a chemical potential dependent frequency and an amplitude approximately given by the homogeneous zero density condensate value.

Phase transitions in the hard-core Bose-Fermi-Hubbard model at non-zero temperatures in the heavy-fermion limit

Energy Technology Data Exchange (ETDEWEB)

Stasyuk, I.V.; Krasnov, V.O., E-mail: krasnoff@icmp.lviv.ua

2017-04-15

Phase transitions at non-zero temperatures in ultracold Bose- and Fermi-particles mixture in optical lattices using the Bose-Fermi-Hubbard model in the mean field and hard-core boson approximations are investigated. The case of infinitely small fermion transfer and the repulsive on-site boson-fermion interaction is considered. The possibility of change of order (from the 2nd to the 1st one) of the phase transition to the superfluid phase in the regime of fixed values of the chemical potentials of Bose- and Fermi-particles is established. The relevant phase diagrams determining the conditions at which such a change takes place, are built.

Conserved charge fluctuations at vanishing and non-vanishing chemical potential

Science.gov (United States)

Karsch, Frithjof

2017-11-01

Up to 6th order cumulants of fluctuations of net baryon-number, net electric charge and net strangeness as well as correlations among these conserved charge fluctuations are now being calculated in lattice QCD. These cumulants provide a wealth of information on the properties of strong-interaction matter in the transition region from the low temperature hadronic phase to the quark-gluon plasma phase. They can be used to quantify deviations from hadron resonance gas (HRG) model calculations which frequently are used to determine thermal conditions realized in heavy ion collision experiments. Already some second order cumulants like the correlations between net baryon-number and net strangeness or net electric charge differ significantly at temperatures above 155 MeV in QCD and HRG model calculations. We show that these differences increase at non-zero baryon chemical potential constraining the applicability range of HRG model calculations to even smaller values of the temperature.

Local and linear chemical reactivity response functions at finite temperature in density functional theory

International Nuclear Information System (INIS)

Franco-Pérez, Marco; Ayers, Paul W.; Gázquez, José L.; Vela, Alberto

2015-01-01

We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dual descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model

Siegert pseudostate formulation of scattering theory: Nonzero angular momenta in the one-channel case

International Nuclear Information System (INIS)

Batishchev, Pavel A.; Tolstikhin, Oleg I.

2007-01-01

The Siegert pseudostate (SPS) formulation of scattering theory, originally developed by Tolstikhin, Ostrovsky, and Nakamura [Phys. Rev. A, 58, 2077 (1998)] for s-wave scattering in a spherically symmetric finite-range potential, is generalized to nonzero angular momenta. The orthogonality and completeness properties of SPSs are established and SPS expansions for the outgoing-wave Green's function, physical states, and scattering matrix are obtained. The present formulation completes the theory of SPSs in the one-channel case, making its application to three-dimensional problems possible. The results are illustrated by calculations for several model potentials

Lr-Lp Stability of the Incompressible Flows with Nonzero Far-Field Velocity

Directory of Open Access Journals (Sweden)

Jaiok Roh

2011-01-01

Full Text Available We consider the stability of stationary solutions w for the exterior Navier-Stokes flows with a nonzero constant velocity u∞ at infinity. For u∞=0 with nonzero stationary solution w, Chen (1993, Kozono and Ogawa (1994, and Borchers and Miyakawa (1995 have studied the temporal stability in Lp spaces for 11 and obtain Lr-Lp stability as Kozono and Ogawa and Borchers and Miyakawa obtained for u∞=0.

Apparent tunneling in chemical reactions

DEFF Research Database (Denmark)

Henriksen, Niels Engholm; Hansen, Flemming Yssing; Billing, G. D.

2000-01-01

A necessary condition for tunneling in a chemical reaction is that the probability of crossing a barrier is non-zero, when the energy of the reactants is below the potential energy of the barrier. Due to the non-classical nature (i.e, momentum uncertainty) of vibrational states this is, however......, not a sufficient condition in order to establish genuine tunneling as a result of quantum dynamics. This proposition is illustrated for a two-dimensional model potential describing dissociative sticking of N-2 on Ru(s). It is suggested that the remarkable heavy atom tunneling, found in this system, is related...

A Model-Independent Discussion of Quark Number Density and Quark Condensate at Zero Temperature and Finite Quark Chemical Potential

International Nuclear Information System (INIS)

Xu Shu-Sheng; Shi Chao; Cui Zhu-Fang; Zong Hong-Shi; Jiang Yu

2015-01-01

Generally speaking, the quark propagator is dependent on the quark chemical potential in the dense quantum chromodynamics (QCD). By means of the generating functional method, we prove that the quark propagator actually depends on p_4 + iμ from the first principle of QCD. The relation between quark number density and quark condensate is discussed by analyzing their singularities. It is concluded that the quark number density has some singularities at certain μ when T = 0, and the variations of the quark number density as well as the quark condensate are located at the same point. In other words, at a certain μ the quark number density turns to nonzero, while the quark condensate begins to decrease from its vacuum value. (paper)

Design of a New Concentration Series for the Orthogonal Sample Design Approach and Estimation of the Number of Reactions in Chemical Systems.

Science.gov (United States)

Shi, Jiajia; Liu, Yuhai; Guo, Ran; Li, Xiaopei; He, Anqi; Gao, Yunlong; Wei, Yongju; Liu, Cuige; Zhao, Ying; Xu, Yizhuang; Noda, Isao; Wu, Jinguang

2015-11-01

A new concentration series is proposed for the construction of a two-dimensional (2D) synchronous spectrum for orthogonal sample design analysis to probe intermolecular interaction between solutes dissolved in the same solutions. The obtained 2D synchronous spectrum possesses the following two properties: (1) cross peaks in the 2D synchronous spectra can be used to reflect intermolecular interaction reliably, since interference portions that have nothing to do with intermolecular interaction are completely removed, and (2) the two-dimensional synchronous spectrum produced can effectively avoid accidental collinearity. Hence, the correct number of nonzero eigenvalues can be obtained so that the number of chemical reactions can be estimated. In a real chemical system, noise present in one-dimensional spectra may also produce nonzero eigenvalues. To get the correct number of chemical reactions, we classified nonzero eigenvalues into significant nonzero eigenvalues and insignificant nonzero eigenvalues. Significant nonzero eigenvalues can be identified by inspecting the pattern of the corresponding eigenvector with help of the Durbin-Watson statistic. As a result, the correct number of chemical reactions can be obtained from significant nonzero eigenvalues. This approach provides a solid basis to obtain insight into subtle spectral variations caused by intermolecular interaction.

On Reggeon field theories and nonzero vacuum expectation values

International Nuclear Information System (INIS)

Venturi, G.

1976-01-01

In this note it is obtained a satisfactory ''nonrelativistic'' reggeon theory by starting from a ''relativistic'' one, examining its ''nonrelativistic'' limit and allowing a nonzero vacuum expectation value for the pomeron field. In such a context the introduction of secondary trajectories is also studied

Neutron transport assembly calculation with non-zero net current boundary condition

International Nuclear Information System (INIS)

Jo, Chang Keun

1993-02-01

Fuel assembly calculation for the homogenized group constants is one of the most important parts in the reactor core analysis. The homogenized group constants of one a quarter assembly are usually generated for the nodal calculation of the reactor core. In the current nodal calculation, one or a quarter of the fuel assembly corresponds to a unit node. The homogenized group constant calculation for a fuel assembly proceeds through cell spectrum calculations, group condensation and cell homogenization calculations, two dimensional fuel assembly calculation, and then depletion calculations of fuel rods. To obtain the assembly wise homogenized group constants, the two dimensional transport calculation is usually performed. Most codes for the assembly wise homogenized group constants employ a zero net current boundary condition. CASMO-3 is such a code that is in wide use. The zero net current boundary condition is plausible and valid in an infinite reactor composed of the same kind of assemblies. However, the reactor is finite and the core is constructed by different kinds of assemblies. Hence, the assumption of the zero net current boundary condition is not valid in the actual reactor. The objective of this study is to develop a homogenization methodology that can treat any actual boundary condition, i.e. non-zero net current boundary condition. In order to treat the non-zero net current boundary condition, we modify CASMO-3. For the two-dimensional treatment in CASMO-3, a multigroup integral transport routine based on the method of transmission probability is used. The code performs assembly calculation with zero net current boundary condition. CASMO-3 is modified to consider the inhomogeneous source at the assembly boundary surface due to the non-zero net current. The modified version of CASMO-3 is called CASMO-3M. CASMO-3M is applied to several benchmark problems. In order to obtain the inhomogeneous source, the global calculation is performed. The local calculation

The chiral critical line of $N_{f}=2+1$ QCD at ero and non-zero baryon density

CERN Document Server

De Forcrand, Philippe; Forcrand, Philippe de; Philipsen, Owe

2007-01-01

We present numerical results for the location of the chiral critical line at finite temperature and zero and non-zero baryon density for QCD with N_f=2+1 flavours of staggered fermions on lattices with temporal extent N_t=4. For degenerate quark masses, we compare our results obtained with the exact RHMC algorithm with earlier, inexact R-algorithm results and find a reduction of 25% in the critical quark mass, for which the first order phase transition changes to a smooth crossover. Extending our analysis to non-degenerate quark masses, we map out the chiral critical line up to the neighbourhood of the physical point, which we confirm to be in the crossover region. Our data are consistent with a tricritical point at a strange quark mass of ~500 MeV. Finally, we investigate the shift of the critical line with finite baryon density, by simulating with an imaginary chemical potential for which there is no sign problem. We observe this shift to be very small or, conversely, the critical endpoint \\mu^c(m_{u,d},m_s...

Neutrino Mass Models: impact of non-zero reactor angle

International Nuclear Information System (INIS)

King, Stephen F.

2011-01-01

In this talk neutrino mass models are reviewed and the impact of a non-zero reactor angle and other deviations from tri-bi maximal mixing are discussed. We propose some benchmark models, where the only way to discriminate between them is by high precision neutrino oscillation experiments.

Generalized quantization scheme for two-person non-zero sum games

International Nuclear Information System (INIS)

Nawaz, Ahmad; Toor, A H

2004-01-01

We proposed a generalized quantization scheme for non-zero sum games which can be reduced to the two existing quantization schemes under an appropriate set of parameters. Some other important situations are identified which are not apparent in the two existing quantization schemes

Nonzero-Sum Relationships in Mitigating Urban Carbon Emissions: A Dynamic Network Simulation.

Science.gov (United States)

Chen, Shaoqing; Chen, Bin; Su, Meirong

2015-10-06

The "stove-pipe" way of thinking has been mostly used in mitigating carbon emissions and managing socioeconomics because of its convenience of implementation. However, systems-oriented approaches become imperative in pursuit of an efficient regulation of carbon emissions from systems as complicated as urban systems. The aim of this paper is to establish a dynamic network approach that is capable of assessing the effectiveness of carbon emissions mitigation in a more holistic way. A carbon metabolic network is constructed by modeling the carbon flows between economic sectors and environment. With the network shocked by interventions to the sectoral carbon flows, indirect emissions from the city are accounted for under certain carbon mitigation strategies. The nonzero-sum relationships between sectors and environmental components are identified based on utility analysis, which synthesize the nature of direct and indirect network interactions. The results of the case study of Beijing suggest that the stove-pipe mitigation strategies targeted the economic sectors might be not as efficient as they were expected. A direct cutting in material or energy import to the sectors may result in a rebound in indirect emissions and thus fails to achieve the carbon mitigation goal of the city as a whole. A promising way of foreseeing the dynamic mechanism of emissions is to analyze the nonzero-sum relationships between important urban components. Thinking cities as systems of interactions, the network approach is potentially a strong tool for appraising and filtering mitigation strategies of carbon emissions.

Motion of particles of non-zero rest masses exterior to ...

African Journals Online (AJOL)

In this article, we extend the metric tensor exterior to astrophysically real or imaginary spherical distributions of mass whose tensor field varies with polar angle only; to derive equations of motion for test particles in this field. The time, radial, polar and azimuthal equations of motion for particles of non-zero rest masses moving ...

Helicity-dependent generalized parton distributions for nonzero skewness

Energy Technology Data Exchange (ETDEWEB)

Mondal, Chandan [Chinese Academy of Sciences, Institute of Modern Physics, Lanzhou (China)

2017-09-15

We investigate the helicity-dependent generalized parton distributions (GPDs) in momentum as well as transverse position (impact) spaces for the u and d quarks in a proton when the momentum transfer in both the transverse and the longitudinal directions are nonzero. The GPDs are evaluated using the light-front wave functions of a quark-diquark model for nucleon where the wave functions are constructed by the soft-wall AdS/QCD correspondence. We also express the GPDs in the boost-invariant longitudinal position space. (orig.)

Design objectives with non-zero prescribed support displacements

DEFF Research Database (Denmark)

Pedersen, Pauli; Pedersen, Niels Leergaard

2011-01-01

When non-zero prescribed support displacements are involved in addition to design independent loads for a continuum/structure, then the objectives of minimum compliance (total elastic energy) and of maximum strength lead to different designs. This is verified by the presented sensitivities. Designs...... minimization as well as that of direct strength maximization; we choose the objective of obtaining uniform energy density and show by examples that the obtained solutions are close to fulfilling also strength maximization, with the price of increased compliance. Optimal design examples are presented...

Gauge invariance and the effective potential: the Abelian Higgs model

International Nuclear Information System (INIS)

Ramaswamy, S.

1995-01-01

The gauge invariance of the effective potential in the Abelian Higgs model is examined. The Nielsen identities, which ensure gauge independence of the effective potential and other physical quantities, are shown to hold at finite temperature and in the presence of the chemical potential. It is also shown that, as a consequence of the Nielsen identities, the standard order parameter for symmetry breaking, namely the scalar field vacuum expectation value, has a non-zero parametric dependence on the gauge choice employed. These are then verified to one loop at finite temperature. High-temperature symmetry breaking is considered. In the leading high-temperature limit, the potential agrees with the previous calculations. (orig.)

Homogenization via the strong-permittivity-fluctuation theory with nonzero depolarization volume

Science.gov (United States)

Mackay, Tom G.

2004-08-01

The depolarization dyadic provides the scattering response of a single inclusion particle embedded within a homogenous background medium. These dyadics play a central role in formalisms used to estimate the effective constitutive parameters of homogenized composite mediums (HCMs). Conventionally, the inclusion particle is taken to be vanishingly small; this allows the pointwise singularity of the dyadic Green function associated with the background medium to be employed as the depolarization dyadic. A more accurate approach is pursued in this communication by taking into account the nonzero spatial extent of inclusion particles. Depolarization dyadics corresponding to inclusion particles of nonzero volume are incorporated within the strong-permittivity-fluctuation theory (SPFT). The linear dimensions of inclusion particles are assumed to be small relative to the electromagnetic wavelength(s) and the SPFT correlation length. The influence of the size of inclusion particles upon SPFT estimates of the HCM constitutive parameters is investigated for anisotropic dielectric HCMs.In particular, the interplay between correlation length and inclusion size is explored.

Analytic two-loop results for self-energy- and vertex-type diagrams with one non-zero mass

International Nuclear Information System (INIS)

Fleischer, J.; Kotikov, A.V.; Veretin, O.L.

1999-01-01

For a large class of two-loop self-energy- and vertex-type diagrams with only one non-zero mass (m) and the vertices also with only one non-zero external momentum squared (q 2 ) the first few expansion coefficients are calculated by the large mass expansion. This allows us to 'guess' the general structure of these coefficients and to verify them in terms of certain classes of 'basis elements', which are essentially harmonic sums. Since for this case with only one non-zero mass the large mass expansion and the Taylor series in terms of q 2 are identical, this approach yields analytic expressions of the Taylor coefficients, from which the diagram can be easily evaluated numerically in a large domain of the complex q 2 -plane by well known methods. It is also possible to sum the Taylor series and present the results in terms of polylogarithms

Ergodic Capacity Analysis of Free-Space Optical Links with Nonzero Boresight Pointing Errors

KAUST Repository

Ansari, Imran Shafique; Alouini, Mohamed-Slim; Cheng, Julian

2015-01-01

A unified capacity analysis of a free-space optical (FSO) link that accounts for nonzero boresight pointing errors and both types of detection techniques (i.e. intensity modulation/ direct detection as well as heterodyne detection) is addressed

Implications of nonzero θ13 for the neutrino mass hierarchy

International Nuclear Information System (INIS)

Ernst, D J; Cogswell, B K; Burroughs, H R; Escamilla-Roa, J; Latimer, D C

2012-01-01

The Daya Bay, RENO, and Double Chooz experiments have discovered a large non-zero value for θ 13 . We present a global analysis that includes these three experiments, Chooz, the Super-K atmospheric data, and the ν μ → ν e T2K and MINOS experiments that are sensitive to the hierarchy and the sign of θ 13 . We report preliminary results in which we fix the mixing parameters other than θ 13 to those from a recent global analysis. Given there is no evidence for a non-zero CP violation, we assume δ = 0. T2K and MINOS lie in a region of L/E where there is a hierarchy degeneracy in the limit of θ 13 → 0 and no matter interaction. For nonzero θ 13 , the symmetry is partially broken, but a degeneracy under the simultaneous exchange of both hierarchy and the sign of θ 13 remains. Matter effects break this symmetry such that the positions of the peaks in the oscillation probabilities maintain the two-fold symmetry, while the magnitude of the oscillations is sensitive to the hierarchy. This renders T2K and NOvA, with different baselines and different matter effects, better able in combination to distinguish the hierarchy and the sign of θ 13 . The present T2K and MINOS data do not distinguish between hierarchies or the sign of θ 13 , but the large value of θ 13 yields effects from atmospheric data that do. We find for normal hierarchy, positive θ 13 , sin 2 2θ 13 = 0.090 ± 0.020 and is 0.2% probable it is the correct combination; for normal hierarchy, negative θ 13 , sin 2 2θ 13 = 0.108 ± 0.023 and is 2.2% probable; for inverse hierarchy, positive θ 13 , sin 2 2θ 13 = 0.110±0.022 and is 7.1% probable; for inverse hierarchy, negative θ 13 , sin 2 2θ 13 = 0.113 ± 0.022 and is 90.5% probable, results that are inconsistent with two similar analyses.

Flavor origin of dark matter and its relation with leptonic nonzero θ{sub 13} and Dirac CP phase δ

Energy Technology Data Exchange (ETDEWEB)

Bhattacharya, Subhaditya; Karmakar, Biswajit [Department of Physics, Indian Institute of Technology Guwahati,781039 Assam (India); Sahu, Narendra [Department of Physics, Indian Institute of Technology,Hyderabad, Kandi, Sangareddy 502285, Medak, Telengana (India); Sil, Arunansu [Department of Physics, Indian Institute of Technology Guwahati,781039 Assam (India)

2017-05-12

We propose a minimal extension of the standard model by including a U(1) flavor symmetry to establish a correlation between the relic abundance of dark matter, measured by WMAP and PLANCK satellite experiments and non-zero value of sin θ{sub 13} observed at DOUBLE CHOOZ, Daya Bay, RENO and T2K. The flavour symmetry is allowed to be broken at a high scale to a remnant Z{sub 2} symmetry, which not only ensures the stability to the dark matter, but also gives rise to a modification to the existing A{sub 4}-based tri-bimaximal neutrino mixing. This deviation in turn suggests the required non-zero value of sin θ{sub 13}. We assume the dark matter to be neutral under the existing A{sub 4} symmetry while charged under the U(1) flavor symmetry. Hence in this set-up, the non-zero value of sin θ{sub 13} predicts the dark matter charge under U(1), which can be tested at various ongoing and future direct and collider dark matter search experiments. We also point out the involvement of nonzero leptonic CP phase δ, which plays an important role in the analysis.

The Chemical Potential of Plasma Membrane Cholesterol: Implications for Cell Biology.

Science.gov (United States)

Ayuyan, Artem G; Cohen, Fredric S

2018-02-27

Cholesterol is abundant in plasma membranes and exhibits a variety of interactions throughout the membrane. Chemical potential accounts for thermodynamic consequences of molecular interactions, and quantifies the effective concentration (i.e., activity) of any substance participating in a process. We have developed, to our knowledge, the first method to measure cholesterol chemical potential in plasma membranes. This was accomplished by complexing methyl-β-cyclodextrin with cholesterol in an aqueous solution and equilibrating it with an organic solvent containing dissolved cholesterol. The chemical potential of cholesterol was thereby equalized in the two phases. Because cholesterol is dilute in the organic phase, here activity and concentration were equivalent. This equivalence allowed the amount of cholesterol bound to methyl-β-cyclodextrin to be converted to cholesterol chemical potential. Our method was used to determine the chemical potential of cholesterol in erythrocytes and in plasma membranes of nucleated cells in culture. For erythrocytes, the chemical potential did not vary when the concentration was below a critical value. Above this value, the chemical potential progressively increased with concentration. We used standard cancer lines to characterize cholesterol chemical potential in plasma membranes of nucleated cells. This chemical potential was significantly greater for highly metastatic breast cancer cells than for nonmetastatic breast cancer cells. Chemical potential depended on density of the cancer cells. A method to alter and fix the cholesterol chemical potential to any value (i.e., a cholesterol chemical potential clamp) was also developed. Cholesterol content did not change when cells were clamped for 24-48 h. It was found that the level of activation of the transcription factor STAT3 increased with increasing cholesterol chemical potential. The cholesterol chemical potential may regulate signaling pathways. Copyright © 2018. Published by

Gravitational radiation in relativistic theory of gravity with a nonzero graviton mass

International Nuclear Information System (INIS)

Vlasov, A.A.; Chugreev, Yu.V.

1987-01-01

Radiation of gravitation waves have been analysed in the linear approximation of the relative theory of gravity, with the mass of graviton being nonzero. It is shown that the main contribution to the energy loss due to gravitational radiation has been described by the well-known quadrupole formula. Linear approximation applicability conditions have been analysed

Nonzero-Sum Stochastic Differential Portfolio Games under a Markovian Regime Switching Model

Directory of Open Access Journals (Sweden)

Chaoqun Ma

2015-01-01

Full Text Available We consider a nonzero-sum stochastic differential portfolio game problem in a continuous-time Markov regime switching environment when the price dynamics of the risky assets are governed by a Markov-modulated geometric Brownian motion (GBM. The market parameters, including the bank interest rate and the appreciation and volatility rates of the risky assets, switch over time according to a continuous-time Markov chain. We formulate the nonzero-sum stochastic differential portfolio game problem as two utility maximization problems of the sum process between two investors’ terminal wealth. We derive a pair of regime switching Hamilton-Jacobi-Bellman (HJB equations and two systems of coupled HJB equations at different regimes. We obtain explicit optimal portfolio strategies and Feynman-Kac representations of the two value functions. Furthermore, we solve the system of coupled HJB equations explicitly in a special case where there are only two states in the Markov chain. Finally we provide comparative statics and numerical simulation analysis of optimal portfolio strategies and investigate the impact of regime switching on optimal portfolio strategies.

Calculation of nonzero-temperature Casimir forces in the time domain

International Nuclear Information System (INIS)

Pan, Kai; Reid, M. T. Homer; McCauley, Alexander P.; Rodriguez, Alejandro W.; White, Jacob K.; Johnson, Steven G.

2011-01-01

We show how to compute Casimir forces at nonzero temperatures with time-domain electromagnetic simulations, for example, using a finite-difference time-domain (FDTD) method. Compared to our previous zero-temperature time-domain method, only a small modification is required, but we explain that some care is required to properly capture the zero-frequency contribution. We validate the method against analytical and numerical frequency-domain calculations, and show a surprising high-temperature disappearance of a nonmonotonic behavior previously demonstrated in a pistonlike geometry.

Chemical potentials in gauge theories

International Nuclear Information System (INIS)

Actor, A.; Pennsylvania State Univ., Fogelsville

1985-01-01

One-loop calculations of the thermodynamic potential Ω are presented for temperature gauge and non-gauge theories. Prototypical formulae are derived which give Ω as a function of both (i) boson and/or fermion chemical potential, and in the case of gauge theories (ii) the thermal vacuum parameter Asub(O)=const (Asub(μ) is the euclidean gauge potential). From these basic abelian gauge theory formulae, the one-loop contribution to Ω can readily be constructed for Yang-Mills theories, and also for non-gauge theories. (orig.)

On chemical potential

International Nuclear Information System (INIS)

Araki, H.

1981-01-01

In the framework of the C*-algebra formalism of quantum statistical mechanics, the concept of chemical potential or its vector generalization in the case of an arbitrary (not necessarily abelian) separable compact gauge group (of the first kind) is described as an algebraic label of equilibrium states at a given inverse temperature β. It is mathematically attained by extending a (clustering) KMS state of the gauge-invariant part of a C*-algebra F to a state of F and by examining the KMS property of the extension. (Auth.)

Revisiting the definition of the electronic chemical potential, chemical hardness, and softness at finite temperatures

International Nuclear Information System (INIS)

Franco-Pérez, Marco; Gázquez, José L.; Ayers, Paul W.; Vela, Alberto

2015-01-01

We extend the definition of the electronic chemical potential (μ e ) and chemical hardness (η e ) to finite temperatures by considering a reactive chemical species as a true open system to the exchange of electrons, working exclusively within the framework of the grand canonical ensemble. As in the zero temperature derivation of these descriptors, the response of a chemical reagent to electron-transfer is determined by the response of the (average) electronic energy of the system, and not by intrinsic thermodynamic properties like the chemical potential of the electron-reservoir which is, in general, different from the electronic chemical potential, μ e . Although the dependence of the electronic energy on electron number qualitatively resembles the piecewise-continuous straight-line profile for low electronic temperatures (up to ca. 5000 K), the introduction of the temperature as a free variable smoothens this profile, so that derivatives (of all orders) of the average electronic energy with respect to the average electron number exist and can be evaluated analytically. Assuming a three-state ensemble, well-known results for the electronic chemical potential at negative (−I), positive (−A), and zero values of the fractional charge (−(I + A)/2) are recovered. Similarly, in the zero temperature limit, the chemical hardness is formally expressed as a Dirac delta function in the particle number and satisfies the well-known reciprocity relation with the global softness

Quantum Quench Dynamics in the Transverse Field Ising Model at Non-zero Temperatures

Science.gov (United States)

Abeling, Nils; Kehrein, Stefan

The recently discovered Dynamical Phase Transition denotes non-analytic behavior in the real time evolution of quantum systems in the thermodynamic limit and has been shown to occur in different systems at zero temperature [Heyl et al., Phys. Rev. Lett. 110, 135704 (2013)]. In this talk we present the extension of the analysis to non-zero temperature by studying a generalized form of the Loschmidt echo, the work distribution function, of a quantum quench in the transverse field Ising model. Although the quantitative behavior at non-zero temperatures still displays features derived from the zero temperature non-analyticities, it is shown that in this model dynamical phase transitions do not exist if T > 0 . This is a consequence of the system being initialized in a thermal state. Moreover, we elucidate how the Tasaki-Crooks-Jarzynski relation can be exploited as a symmetry relation for a global quench or to obtain the change of the equilibrium free energy density. This work was supported through CRC SFB 1073 (Project B03) of the Deutsche Forschungsgemeinschaft (DFG).

The long-term stability of self-esteem: its time-dependent decay and nonzero asymptote.

Science.gov (United States)

Kuster, Farah; Orth, Ulrich

2013-05-01

How stable are individual differences in self-esteem? We examined the time-dependent decay of rank-order stability of self-esteem and tested whether stability asymptotically approaches zero or a nonzero value across long test-retest intervals. Analyses were based on 6 assessments across a 29-year period of a sample of 3,180 individuals aged 14 to 102 years. The results indicated that, as test-retest intervals increased, stability exponentially decayed and asymptotically approached a nonzero value (estimated as .43). The exponential decay function explained a large proportion of variance in observed stability coefficients, provided a better fit than alternative functions, and held across gender and for all age groups from adolescence to old age. Moreover, structural equation modeling of the individual-level data suggested that a perfectly stable trait component underlies stability of self-esteem. The findings suggest that the stability of self-esteem is relatively large, even across very long periods, and that self-esteem is a trait-like characteristic.

Revisiting the definition of the electronic chemical potential, chemical hardness, and softness at finite temperatures

Energy Technology Data Exchange (ETDEWEB)

Franco-Pérez, Marco, E-mail: qimfranco@hotmail.com, E-mail: jlgm@xanum.uam.mx [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, México D. F. 09340 (Mexico); Department of Chemistry, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Gázquez, José L., E-mail: qimfranco@hotmail.com, E-mail: jlgm@xanum.uam.mx [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, México D. F. 09340 (Mexico); Ayers, Paul W. [Department of Chemistry, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Vela, Alberto [Departamento de Química, Centro de Investigación y de Estudios Avanzados (Cinvestav), Av. Instituto Politécnico Nacional 2508, México D. F. 07360 (Mexico)

2015-10-21

We extend the definition of the electronic chemical potential (μ{sub e}) and chemical hardness (η{sub e}) to finite temperatures by considering a reactive chemical species as a true open system to the exchange of electrons, working exclusively within the framework of the grand canonical ensemble. As in the zero temperature derivation of these descriptors, the response of a chemical reagent to electron-transfer is determined by the response of the (average) electronic energy of the system, and not by intrinsic thermodynamic properties like the chemical potential of the electron-reservoir which is, in general, different from the electronic chemical potential, μ{sub e}. Although the dependence of the electronic energy on electron number qualitatively resembles the piecewise-continuous straight-line profile for low electronic temperatures (up to ca. 5000 K), the introduction of the temperature as a free variable smoothens this profile, so that derivatives (of all orders) of the average electronic energy with respect to the average electron number exist and can be evaluated analytically. Assuming a three-state ensemble, well-known results for the electronic chemical potential at negative (−I), positive (−A), and zero values of the fractional charge (−(I + A)/2) are recovered. Similarly, in the zero temperature limit, the chemical hardness is formally expressed as a Dirac delta function in the particle number and satisfies the well-known reciprocity relation with the global softness.

Local chemical potential, local hardness, and dual descriptors in temperature dependent chemical reactivity theory.

Science.gov (United States)

Franco-Pérez, Marco; Ayers, Paul W; Gázquez, José L; Vela, Alberto

2017-05-31

In this work we establish a new temperature dependent procedure within the grand canonical ensemble, to avoid the Dirac delta function exhibited by some of the second order chemical reactivity descriptors based on density functional theory, at a temperature of 0 K. Through the definition of a local chemical potential designed to integrate to the global temperature dependent electronic chemical potential, the local chemical hardness is expressed in terms of the derivative of this local chemical potential with respect to the average number of electrons. For the three-ground-states ensemble model, this local hardness contains a term that is equal to the one intuitively proposed by Meneses, Tiznado, Contreras and Fuentealba, which integrates to the global hardness given by the difference in the first ionization potential, I, and the electron affinity, A, at any temperature. However, in the present approach one finds an additional temperature-dependent term that introduces changes at the local level and integrates to zero. Additionally, a τ-hard dual descriptor and a τ-soft dual descriptor given in terms of the product of the global hardness and the global softness multiplied by the dual descriptor, respectively, are derived. Since all these reactivity indices are given by expressions composed of terms that correspond to products of the global properties multiplied by the electrophilic or nucleophilic Fukui functions, they may be useful for studying and comparing equivalent sites in different chemical environments.

Discrete-Time Nonzero-Sum Games for Multiplayer Using Policy-Iteration-Based Adaptive Dynamic Programming Algorithms.

Science.gov (United States)

Zhang, Huaguang; Jiang, He; Luo, Chaomin; Xiao, Geyang

2017-10-01

In this paper, we investigate the nonzero-sum games for a class of discrete-time (DT) nonlinear systems by using a novel policy iteration (PI) adaptive dynamic programming (ADP) method. The main idea of our proposed PI scheme is to utilize the iterative ADP algorithm to obtain the iterative control policies, which not only ensure the system to achieve stability but also minimize the performance index function for each player. This paper integrates game theory, optimal control theory, and reinforcement learning technique to formulate and handle the DT nonzero-sum games for multiplayer. First, we design three actor-critic algorithms, an offline one and two online ones, for the PI scheme. Subsequently, neural networks are employed to implement these algorithms and the corresponding stability analysis is also provided via the Lyapunov theory. Finally, a numerical simulation example is presented to demonstrate the effectiveness of our proposed approach.

Golay Complementary Waveforms in Reed–Müller Sequences for Radar Detection of Nonzero Doppler Targets

Science.gov (United States)

Wang, Xuezhi; Huang, Xiaotao; Suvorova, Sofia; Moran, Bill

2018-01-01

Golay complementary waveforms can, in theory, yield radar returns of high range resolution with essentially zero sidelobes. In practice, when deployed conventionally, while high signal-to-noise ratios can be achieved for static target detection, significant range sidelobes are generated by target returns of nonzero Doppler causing unreliable detection. We consider signal processing techniques using Golay complementary waveforms to improve radar detection performance in scenarios involving multiple nonzero Doppler targets. A signal processing procedure based on an existing, so called, Binomial Design algorithm that alters the transmission order of Golay complementary waveforms and weights the returns is proposed in an attempt to achieve an enhanced illumination performance. The procedure applies one of three proposed waveform transmission ordering algorithms, followed by a pointwise nonlinear processor combining the outputs of the Binomial Design algorithm and one of the ordering algorithms. The computational complexity of the Binomial Design algorithm and the three ordering algorithms are compared, and a statistical analysis of the performance of the pointwise nonlinear processing is given. Estimation of the areas in the Delay–Doppler map occupied by significant range sidelobes for given targets are also discussed. Numerical simulations for the comparison of the performances of the Binomial Design algorithm and the three ordering algorithms are presented for both fixed and randomized target locations. The simulation results demonstrate that the proposed signal processing procedure has a better detection performance in terms of lower sidelobes and higher Doppler resolution in the presence of multiple nonzero Doppler targets compared to existing methods. PMID:29324708

Chemical potential and reaction electronic flux in symmetry controlled reactions.

Science.gov (United States)

Vogt-Geisse, Stefan; Toro-Labbé, Alejandro

2016-07-15

In symmetry controlled reactions, orbital degeneracies among orbitals of different symmetries can occur along a reaction coordinate. In such case Koopmans' theorem and the finite difference approximation provide a chemical potential profile with nondifferentiable points. This results in an ill-defined reaction electronic flux (REF) profile, since it is defined as the derivative of the chemical potential with respect to the reaction coordinate. To overcome this deficiency, we propose a new way for the calculation of the chemical potential based on a many orbital approach, suitable for reactions in which symmetry is preserved. This new approach gives rise to a new descriptor: symmetry adapted chemical potential (SA-CP), which is the chemical potential corresponding to a given irreducible representation of a symmetry group. A corresponding symmetry adapted reaction electronic flux (SA-REF) is also obtained. Using this approach smooth chemical potential profiles and well defined REFs are achieved. An application of SA-CP and SA-REF is presented by studying the Cs enol-keto tautomerization of thioformic acid. Two SA-REFs are obtained, JA'(ξ) and JA'' (ξ). It is found that the tautomerization proceeds via an in-plane delocalized 3-center 4-electron O-H-S hypervalent bond which is predicted to exist only in the transition state (TS) region. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Chiral properties of two-flavour QCD at zero and non-zero temperature

Energy Technology Data Exchange (ETDEWEB)

Brandt, Bastian Benjamin

2012-11-22

radius are used to test chiral perturbation theory (χPT) and are thereby extrapolated to the physical point and the continuum. The final result in units of the hadronic radius r{sub 0} is left angle r{sup 2}{sub π} right angle {sup phys}/r{sub 0}{sup 2}=1.87({sup +12}{sub -10})({sup +4}{sub -15}) or left angle r{sub π}{sup 2} right angle {sup phys}=0.473({sup +30}{sub -26})({sup +10}{sub -38})(10) fm, which agrees well with the results from other measurements in LQCD and experiment. Note, that this is the first continuum extrapolated result for the charge radius from LQCD which has been extracted from measurements of the form factor in the region of small q{sup 2}. The order of the phase transition in the chiral limit of two-flavour QCD and the associated transition temperature are the last unknown features of the phase diagram at zero chemical potential. The two possible scenarios are a second order transition in the O(4)-universality class or a first order transition. Since direct simulations in the chiral limit are not possible the transition can only be investigated by simulating at non-zero quark mass with a subsequent chiral extrapolation, guided by the universal scaling in the vicinity of the critical point. The thesis presents the setup and first results from a study on this topic. The study provides the ideal platform to test the potential and limits of todays simulation algorithms at finite temperature. The results from a first scan at a constant zero-temperature pion mass of about 290 MeV are promising, and it appears that simulations down to physical quark masses are feasible. Of particular relevance for the order of the chiral transition is the strength of the anomalous breaking of the U{sub A}(1) symmetry at the transition point. It can be studied by looking at the degeneracies of the correlation functions in scalar and pseudoscalar channels. For the temperature scan reported in this thesis the breaking is still pronounced in the transition region and

Chiral properties of two-flavour QCD at zero and non-zero temperature

International Nuclear Information System (INIS)

Brandt, Bastian Benjamin

2012-01-01

test chiral perturbation theory (χPT) and are thereby extrapolated to the physical point and the continuum. The final result in units of the hadronic radius r 0 is left angle r 2 π right angle phys /r 0 2 =1.87( +12 -10 )( +4 -15 ) or left angle r π 2 right angle phys =0.473( +30 -26 )( +10 -38 )(10) fm, which agrees well with the results from other measurements in LQCD and experiment. Note, that this is the first continuum extrapolated result for the charge radius from LQCD which has been extracted from measurements of the form factor in the region of small q 2 . The order of the phase transition in the chiral limit of two-flavour QCD and the associated transition temperature are the last unknown features of the phase diagram at zero chemical potential. The two possible scenarios are a second order transition in the O(4)-universality class or a first order transition. Since direct simulations in the chiral limit are not possible the transition can only be investigated by simulating at non-zero quark mass with a subsequent chiral extrapolation, guided by the universal scaling in the vicinity of the critical point. The thesis presents the setup and first results from a study on this topic. The study provides the ideal platform to test the potential and limits of todays simulation algorithms at finite temperature. The results from a first scan at a constant zero-temperature pion mass of about 290 MeV are promising, and it appears that simulations down to physical quark masses are feasible. Of particular relevance for the order of the chiral transition is the strength of the anomalous breaking of the U A (1) symmetry at the transition point. It can be studied by looking at the degeneracies of the correlation functions in scalar and pseudoscalar channels. For the temperature scan reported in this thesis the breaking is still pronounced in the transition region and the symmetry becomes effectively restored only above 1.16 T C . The thesis also provides an extensive

Chemical potential of one-dimensional simple harmonic oscillators

International Nuclear Information System (INIS)

Mungan, Carl E

2009-01-01

Expressions for the chemical potential of an Einstein solid, and of ideal Fermi and Bose gases in an external one-dimensional oscillatory trap, are calculated by two different methods and are all found to share the same functional form. These derivations are easier than traditional textbook calculations for an ideal gas in an infinite three-dimensional square well. Furthermore, the results indicate some important features of chemical potential that could promote student learning in an introductory course in statistical mechanics at the undergraduate level.

Two observable features of the staggered-flux phase at nonzero doping

International Nuclear Information System (INIS)

Hsu, T.C.; Marston, J.B.; Affleck, I.

1991-01-01

We investigate whether the staggered-flux phase (SFP) is realized in slightly doped phases of the Cu-O high-T c superconductors. Using a mean-field solution of the t-J model, we calculate the size of circulating currents in the CuO 2 planes. For realistic parameters we find nonzero currents when the doping δ 2-x Sr x CuO 4 samples but additional structure along the (Q x ,0) and (0,Q y ) directions has not been seen. The absence of magnetic fields when δ>0.12 is consistent with the limits set by the muon experiments on superconducting samples

Quasi-particles at finite chemical potential

International Nuclear Information System (INIS)

Gardim, F. G.; Steffens, F. M.

2010-01-01

We present in this work the thermodynamic consistent quasi-particle model at finite chemical potential, to describe the Quark Gluon Plasma composed of two light quarks and gluons. The quasi-particle general solution will be discussed, and comparison with perturbative QCD and lattice data will be shown.

Holography for Heavy Ions Collisions at LHC and NICA

Directory of Open Access Journals (Sweden)

Aref’eva Irina

2017-01-01

Our conjecture is that this Lifshitz-type background with non-zero chemical potential can be used to describe future data expected from NICA. In particular, we present the results of calculations the holographic confinement/deconfinement phase transition in the (µ, T (chemical potential, temperature plane in this anizotropic background and show the dependence of the transition line on the orientation of the quark pair. This dependence leads to a non-sharp character of physical confinement/deconfinement phase in the (µ, T-plane. We use the bottom-up soft wall approach incorporating quark confinement deforming factor and vector field providing the non-zero chemical potential. In this model we also estimate the holographic photon production.

Generalization of the Child-Langmuir law for nonzero injection velocities in a planar diode

International Nuclear Information System (INIS)

Puri, R.R.; Biswas, Debabrata; Kumar, Raghwendra

2004-01-01

The Child-Langmuir law relates the voltage applied across a planar diode to the saturation value J CL of current density that can be transmitted through it in case the injection velocity of electrons is zero. The Child-Langmuir current density J CL is, at the same time: (i) the maximum current density that can be transmitted through a planar diode, (ii) the current density below which the flow is steady and unidirectional in the long time limit, and (iii) the average transmitted current density for any value of injected current density above J CL . Existing generalizations of Child-Langmuir law to nonzero velocities of injection are based on the characteristics (i) and (ii) of J CL . This paper generalizes the law to nonzero velocities of injection based on the characteristic (iii) by deriving an analytical expression for the saturation value of current density. The analytical expression for the saturation current density is found to be well supported by numerical computations. A reason behind preferring the saturation property of the Child-Langmuir current density as the basis for its generalization is the importance of that property in numerical simulations of high current diode devices

Temperature expansions for magnetic systems

International Nuclear Information System (INIS)

Cangemi, D.; Dunne, G.

1996-01-01

We derive finite temperature expansions for relativistic fermion systems in the presence of background magnetic fields, and with nonzero chemical potential. We use the imaginary-time formalism for the finite temperature effects, the proper-time method for the background field effects, and zeta function regularization for developing the expansions. We emphasize the essential difference between even and odd dimensions, focusing on 2+1 and 3+1 dimensions. We concentrate on the high temperature limit, but we also discuss the T=0 limit with nonzero chemical potential. Copyright copyright 1996 Academic Press, Inc

Chemical potential calculations in dense liquids using metadynamics

Science.gov (United States)

Perego, C.; Giberti, F.; Parrinello, M.

2016-10-01

The calculation of chemical potential has traditionally been a challenge in atomistic simulations. One of the most used approaches is Widom's insertion method in which the chemical potential is calculated by periodically attempting to insert an extra particle in the system. In dense systems this method fails since the insertion probability is very low. In this paper we show that in a homogeneous fluid the insertion probability can be increased using metadynamics. We test our method on a supercooled high density binary Lennard-Jones fluid. We find that we can obtain efficiently converged results even when Widom's method fails.

Baryon-charge chemical potential in AdS/CFT

International Nuclear Information System (INIS)

Nakamura, Shin; Seo, Yunseok; Sin, Sang-Jin; Yogendran, K.P.

2008-01-01

We investigate the D3-D7 model at finite U(1) B -charge chemical potential. We point out that the D3-D7 model with only the black-hole embeddings does not have the low-temperature and low-chemical-potential region in the grand-canonical ensemble, hence it is incomplete. The incomplete-ness is also seen as the thermodynamic instability in the canonical ensemble. We propose to solve the incomplete-ness problem by introducing the Minkowski embeddings at the finite U(1) B -charge. A possible physical interpretation of our model is given. (author)

Nonzero θ13 and neutrino masses from the modified tri-bi-maximal neutrino mixing matrix

International Nuclear Information System (INIS)

Damanik, A.

2014-01-01

There are 3 types of neutrino mixing matrices: tri-bi-maximal, bi-maximal and democratic. These 3 types of neutrino mixing matrices predict that the mixing angle θ 13 should be null. Motivated by the recent experimental evidence of nonzero and relatively large θ 13 , we modified the tribimaximal mixing matrix by introducing a simple perturbation matrix into tribimaximal neutrino mixing matrix. In this scenario, we obtained nonzero mixing angle θ 13 =7.9 degrees which is in agreement with the present experimental results. By imposing 2 zeros texture into the obtained neutrino mass matrix from modified tribimaximal mixing matrix, we then have the neutrino mass spectrum in normal hierarchy. Some phenomenological implications are also discussed. It appears that if we use the solar neutrino squared-mass difference to determine the values of neutrino masses, then we cannot have the correct value for the atmospheric squared-mass difference. Conversely, if we use the experimental value of the squared-mass difference to determine the neutrino masses, then we cannot have the correct value for the solar neutrino squared-mass difference

Does the QCD vacuum build up a colour chemical potential dynamically?

International Nuclear Information System (INIS)

Sailer, K.; Greiner, W.

1998-01-01

The one-loop effective theory is found for QCD assuming an overcritical homogeneous gluon vector potential background that corresponds to a non-vanishing colour chemical potential. It is found that the vacuum is unstable against building up a non-vanishing colour chemical potential for sufficiently large number of flavours. (author)

Neutrino mass models and the implications of a non-zero reactor angle

International Nuclear Information System (INIS)

King, S.F.

2009-01-01

In this talk we survey some of the recent promising developments in the search for the theory behind neutrino mass and mixing, and indeed all fermion masses and mixing. The talk is organized in terms of a neutrino mass models decision tree according to which the answers to experimental questions provide sign posts to guide through the maze of theoretical models eventually towards a complete theory of flavour and unification. It is also discussed the theoretical implications of the measurement of non-zero reactor angle, as hinted at by recent experimental measurements.

Chemical-potential flow equations for graphene with Coulomb interactions

Science.gov (United States)

Fräßdorf, Christian; Mosig, Johannes E. M.

2018-06-01

We calculate the chemical potential dependence of the renormalized Fermi velocity and static dielectric function for Dirac quasiparticles in graphene nonperturbatively at finite temperature. By reinterpreting the chemical potential as a flow parameter in the spirit of the functional renormalization group (fRG) we obtain a set of flow equations, which describe the change of these functions upon varying the chemical potential. In contrast to the fRG the initial condition of the flow is nontrivial and has to be calculated separately. Our results are consistent with a charge carrier-independent Fermi velocity v (k ) for small densities n ≲k2/π , supporting the comparison of the zero-density fRG calculation of Bauer et al. [Phys. Rev. B 92, 121409 (2015), 10.1103/PhysRevB.92.121409], with the experiment of Elias et al. [Nat. Phys. 7, 701 (2011), 10.1038/nphys2049].

Estimation of Radiative Efficiency of Chemicals with Potentially Significant Global Warming Potential

Data.gov (United States)

U.S. Environmental Protection Agency — The set of commercially available chemical substances in commerce that may have significant global warming potential (GWP) is not well defined. Although there are...

Bayesian evidence for non-zero θ 13 and CP-violation in neutrino oscillations

Science.gov (United States)

Bergström, Johannes

2012-08-01

We present the Bayesian method for evaluating the evidence for a non-zero value of the leptonic mixing angle θ 13 and CP-violation in neutrino oscillation experiments. This is an application of the well-established method of Bayesian model selection, of which we give a concise and pedagogical overview. When comparing the hypothesis θ 13 = 0 with hypotheses where θ 13 > 0 using global data but excluding the recent reactor measurements, we obtain only a weak preference for a non-zero θ 13, even though the significance is over 3 σ. We then add the reactor measurements one by one and show how the evidence for θ 13 > 0 quickly increases. When including the D ouble C hooz, D aya B ay, and RENO data, the evidence becomes overwhelming with a posterior probability of the hypothesis θ 13 = 0 below 10-11. Owing to the small amount of information on the CP-phase δ, very similar evidences are obtained for the CP-conserving and CP-violating hypotheses. Hence, there is, not unexpectedly, neither evidence for nor against leptonic CP-violation. However, when future experiments aiming to search for CP-violation have started taking data, this question will be of great importance and the method described here can be used as an important complement to standard analyses.

Chlorine isotopes potential as geo-chemical tracers

Digital Repository Service at National Institute of Oceanography (India)

Shirodkar, P.V.; Pradhan, U.K.; Banerjee, R.

The potential of chlorine isotopes as tracers of geo-chemical processes of earth and the oceans is highlighted based on systematic studies carried out in understanding the chlorine isotope fractionation mechanism, its constancy in seawater and its...

QCD phase transition at real chemical potential with canonical approach

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Atsushi [RCNP, Osaka University,Osaka, 567-0047 (Japan); Nishina Center, RIKEN,Wako, Saitama 351-0198 (Japan); School of Biomedicine, Far Eastern Federal University,Vladivostok, 690950 (Russian Federation); Oka, Shotaro [Institute of Theoretical Physics, Department of Physics, Rikkyo University,Toshima-ku, Tokyo 171-8501 (Japan); Taniguchi, Yusuke [Graduate School of Pure and Applied Sciences, University of Tsukuba,Tsukuba, Ibaraki 305-8571 (Japan)

2016-02-08

We study the finite density phase transition in the lattice QCD at real chemical potential. We adopt a canonical approach and the canonical partition function is constructed for N{sub f}=2 QCD. After derivation of the canonical partition function we calculate observables like the pressure, the quark number density, its second cumulant and the chiral condensate as a function of the real chemical potential. We covered a wide range of temperature region starting from the confining low to the deconfining high temperature; 0.65T{sub c}≤T≤3.62T{sub c}. We observe a possible signal of the deconfinement and the chiral restoration phase transition at real chemical potential below T{sub c} starting from the confining phase. We give also the convergence range of the fugacity expansion.

Molecular dynamics simulations of solutions at constant chemical potential

Science.gov (United States)

Perego, C.; Salvalaglio, M.; Parrinello, M.

2015-04-01

Molecular dynamics studies of chemical processes in solution are of great value in a wide spectrum of applications, which range from nano-technology to pharmaceutical chemistry. However, these calculations are affected by severe finite-size effects, such as the solution being depleted as the chemical process proceeds, which influence the outcome of the simulations. To overcome these limitations, one must allow the system to exchange molecules with a macroscopic reservoir, thus sampling a grand-canonical ensemble. Despite the fact that different remedies have been proposed, this still represents a key challenge in molecular simulations. In the present work, we propose the Constant Chemical Potential Molecular Dynamics (CμMD) method, which introduces an external force that controls the environment of the chemical process of interest. This external force, drawing molecules from a finite reservoir, maintains the chemical potential constant in the region where the process takes place. We have applied the CμMD method to the paradigmatic case of urea crystallization in aqueous solution. As a result, we have been able to study crystal growth dynamics under constant supersaturation conditions and to extract growth rates and free-energy barriers.

Temperature, chemical potential and the ρ meson

International Nuclear Information System (INIS)

Roberts, C. D.; Schmidt, S. M.

2000-01-01

Models of QCD must confront nonperturbative phenomena such as confinement, dynamical chiral symmetry breaking (DCSB) and the formation of bound states. In addition, a unified approach should describe the deconfinement and chiral symmetry restoring phase transition exhibited by strongly-interacting matter under extreme conditions of temperature and density. Nonperturbative Dyson-Schwinger equation (DSE) models provide insight into a wide range of zero temperature hadronic phenomena; e.g., non-hadronic electroweak interactions of light- and heavy-mesons, and diverse meson-meson and meson-nucleon form factors. This is the foundation for their application at nonzero-(T, μ). Herein the authors describe the calculation of the reconfinement and chiral symmetry restoring phase boundary, and the medium dependence of ρ-meson properties. They also introduce an extension to describe the time-evolution in the plasma of the quark's scalar and vector self energies based on a Vlasov equation

Hopping magnetotransport via nonzero orbital momentum states and organic magnetoresistance.

Science.gov (United States)

Alexandrov, Alexandre S; Dediu, Valentin A; Kabanov, Victor V

2012-05-04

In hopping magnetoresistance of doped insulators, an applied magnetic field shrinks the electron (hole) s-wave function of a donor or an acceptor and this reduces the overlap between hopping sites resulting in the positive magnetoresistance quadratic in a weak magnetic field, B. We extend the theory of hopping magnetoresistance to states with nonzero orbital momenta. Different from s states, a weak magnetic field expands the electron (hole) wave functions with positive magnetic quantum numbers, m>0, and shrinks the states with negative m in a wide region outside the point defect. This together with a magnetic-field dependence of injection/ionization rates results in a negative weak-field magnetoresistance, which is linear in B when the orbital degeneracy is lifted. The theory provides a possible explanation of a large low-field magnetoresistance in disordered π-conjugated organic materials.

Chemical potentials of π- and π+ in heavy-ion collisions

International Nuclear Information System (INIS)

Gorenstejn, M.I.; Shin Nan Yang.

1991-01-01

We consider a chemical nonequilibrium model to describe the pion production in Ar+KCl and La+La collisions at initial energies E lab /A=(0.5-1.8) GeV/nucl. The excess of low energy π - is interpreted as the manifestation of positive chemical potential of π - at the thermal freeze out. We find that in collisions between nuclei with large atomic numbers the chemical potential of π + is smaller than that of π - . This leads to the prediction of a much less excess of low-energy π + , than as measured in the π - case, in heavy-ion collisions at bombarding energies in the region of 1 GeV/nucl. 17 refs.; 2 figs. (author)

Estimation of Radiative Efficiency of Chemicals with Potentially Significant Global Warming Potential.

Science.gov (United States)

Betowski, Don; Bevington, Charles; Allison, Thomas C

2016-01-19

Halogenated chemical substances are used in a broad array of applications, and new chemical substances are continually being developed and introduced into commerce. While recent research has considerably increased our understanding of the global warming potentials (GWPs) of multiple individual chemical substances, this research inevitably lags behind the development of new chemical substances. There are currently over 200 substances known to have high GWP. Evaluation of schemes to estimate radiative efficiency (RE) based on computational chemistry are useful where no measured IR spectrum is available. This study assesses the reliability of values of RE calculated using computational chemistry techniques for 235 chemical substances against the best available values. Computed vibrational frequency data is used to estimate RE values using several Pinnock-type models, and reasonable agreement with reported values is found. Significant improvement is obtained through scaling of both vibrational frequencies and intensities. The effect of varying the computational method and basis set used to calculate the frequency data is discussed. It is found that the vibrational intensities have a strong dependence on basis set and are largely responsible for differences in computed RE values.

Thermalization with chemical potentials, and higher spin black holes

International Nuclear Information System (INIS)

Mandal, Gautam; Sinha, Ritam; Sorokhaibam, Nilakash

2015-01-01

We study the long time behaviour of local observables following a quantum quench in 1+1 dimensional conformal field theories possessing additional conserved charges besides the energy. We show that the expectation value of an arbitrary string of local observables supported on a finite interval exponentially approaches an equilibrium value. The equilibrium is characterized by a temperature and chemical potentials defined in terms of the quenched state. For an infinite number of commuting conserved charges, the equilibrium ensemble is a generalized Gibbs ensemble (GGE). We compute the thermalization rate in a systematic perturbation in the chemical potentials, using a new technique to sum over an infinite number of Feynman diagrams. The above technique also allows us to compute relaxation times for thermal Green’s functions in the presence of an arbitrary number of chemical potentials. In the context of a higher spin (hs[λ]) holography, the partition function of the final equilibrium GGE is known to agree with that of a higher spin black hole. The thermalization rate from the CFT computed in our paper agrees with the quasinormal frequency of a scalar field in this black hole.

Analysis of Probability of Non-zero Secrecy Capacity for Multi-hop Networks in Presence of Hardware Impairments over Nakagami-m Fading Channels

Directory of Open Access Journals (Sweden)

T.-T. Phu

2016-12-01

Full Text Available In this paper, we evaluate probability of non-zero secrecy capacity of multi-hop relay networks over Nakagami-m fading channels in presence of hardware impairments. In the considered protocol, a source attempts to transmit its data to a destination by using multi-hop randomize-and-forward (RF strategy. The data transmitted by the source and relays are overheard by an eavesdropper. For performance evaluation, we derive exact expressions of probability of non-zero secrecy capacity (PoNSC, which are expressed by sums of infinite series of exponential functions and exponential integral functions. We then perform Monte Carlo simulations to verify the theoretical analysis.

BCS gap equations in the quantum limit

International Nuclear Information System (INIS)

Norman, M.R.

1991-01-01

It was shown that in the quantum limit where only one Landau level is occupied,Tc diverges with increasing H.It was also indcated that Tc is unaffected impurities or by a nonzero g factor, in contrast to what was indicated in Ref. 2.The authors result is due to an assumption that the DOS about a Debye width of the chemical potential is constant. This approximation is questionable sice chemical potential decrease rapidly as H increases.Here Tc is calculated as a function of H in the quantum limit for an appropriate set of parameters to understand how impurities and nonzero g factor affect the result

Interferometry with particles of non-zero rest mass: topological experiments

International Nuclear Information System (INIS)

Opat, G.I.

1994-01-01

Interferometry as a space-time process is described, together with its topology. Starting from this viewpoint, a convenient unified formalism for the phase shifts which arise in particle interferometry is developed. This formalism is based on a covariant form of Hamilton's action principle and Lagrange's equations of motion. It will be shown that this Lorentz invariant formalism yields a simple perturbation theoretic expression for the general phase shift that arises in matter-wave interferometry. The Lagrangian formalism is compared with the more usual formalism based on the wave propagation vector and frequency. The resulting formalism will be used to analyse the Sagnac effect, gravitational field measurements, and several Aharonov-Bohm-like topological phase shifts. Several topological interferometric experiments using particles of non-zero rest mass are discussed. These experiments involve the use of electrons, neutrons and neutral atoms. Neutron experiments will be emphasised. 45 refs., 15 figs

Constraining the QCD phase diagram by tricritical lines at imaginary chemical potential

CERN Document Server

de Forcrand, Philippe

2010-01-01

We present unambiguous evidence from lattice simulations of QCD with three degenerate quark species for two tricritical points in the (T,m) phase diagram at fixed imaginary \\mu/T=i\\pi/3 mod 2\\pi/3, one in the light and one in the heavy mass regime. These represent the boundaries of the chiral and deconfinement critical lines continued to imaginary chemical potential, respectively. It is demonstrated that the shape of the deconfinement critical line for real chemical potentials is dictated by tricritical scaling and implies the weakening of the deconfinement transition with real chemical potential. The generalization to non-degenerate and light quark masses is discussed.

Chemical compounds from anthropogenic environment and immune evasion mechanisms: potential interactions

Science.gov (United States)

Kravchenko, Julia; Corsini, Emanuela; Williams, Marc A.; Decker, William; Manjili, Masoud H.; Otsuki, Takemi; Singh, Neetu; Al-Mulla, Faha; Al-Temaimi, Rabeah; Amedei, Amedeo; Colacci, Anna Maria; Vaccari, Monica; Mondello, Chiara; Scovassi, A. Ivana; Raju, Jayadev; Hamid, Roslida A.; Memeo, Lorenzo; Forte, Stefano; Roy, Rabindra; Woodrick, Jordan; Salem, Hosni K.; Ryan, Elizabeth P.; Brown, Dustin G.; Lowe, Leroy; Lyerly, H.Kim

2015-01-01

An increasing number of studies suggest an important role of host immunity as a barrier to tumor formation and progression. Complex mechanisms and multiple pathways are involved in evading innate and adaptive immune responses, with a broad spectrum of chemicals displaying the potential to adversely influence immunosurveillance. The evaluation of the cumulative effects of low-dose exposures from the occupational and natural environment, especially if multiple chemicals target the same gene(s) or pathway(s), is a challenge. We reviewed common environmental chemicals and discussed their potential effects on immunosurveillance. Our overarching objective was to review related signaling pathways influencing immune surveillance such as the pathways involving PI3K/Akt, chemokines, TGF-β, FAK, IGF-1, HIF-1α, IL-6, IL-1α, CTLA-4 and PD-1/PDL-1 could individually or collectively impact immunosurveillance. A number of chemicals that are common in the anthropogenic environment such as fungicides (maneb, fluoxastrobin and pyroclostrobin), herbicides (atrazine), insecticides (pyridaben and azamethiphos), the components of personal care products (triclosan and bisphenol A) and diethylhexylphthalate with pathways critical to tumor immunosurveillance. At this time, these chemicals are not recognized as human carcinogens; however, it is known that they these chemicalscan simultaneously persist in the environment and appear to have some potential interfere with the host immune response, therefore potentially contributing to promotion interacting with of immune evasion mechanisms, and promoting subsequent tumor growth and progression. PMID:26002081

Chemical structure-based predictive model for methanogenic anaerobic biodegradation potential.

Science.gov (United States)

Meylan, William; Boethling, Robert; Aronson, Dallas; Howard, Philip; Tunkel, Jay

2007-09-01

Many screening-level models exist for predicting aerobic biodegradation potential from chemical structure, but anaerobic biodegradation generally has been ignored by modelers. We used a fragment contribution approach to develop a model for predicting biodegradation potential under methanogenic anaerobic conditions. The new model has 37 fragments (substructures) and classifies a substance as either fast or slow, relative to the potential to be biodegraded in the "serum bottle" anaerobic biodegradation screening test (Organization for Economic Cooperation and Development Guideline 311). The model correctly classified 90, 77, and 91% of the chemicals in the training set (n = 169) and two independent validation sets (n = 35 and 23), respectively. Accuracy of predictions of fast and slow degradation was equal for training-set chemicals, but fast-degradation predictions were less accurate than slow-degradation predictions for the validation sets. Analysis of the signs of the fragment coefficients for this and the other (aerobic) Biowin models suggests that in the context of simple group contribution models, the majority of positive and negative structural influences on ultimate degradation are the same for aerobic and methanogenic anaerobic biodegradation.

Potential health effects associated with dermal exposure to occupational chemicals.

Science.gov (United States)

Anderson, Stacey E; Meade, B Jean

2014-01-01

There are a large number of workers in the United States, spanning a variety of occupational industries and sectors, who are potentially exposed to chemicals that can be absorbed through the skin. Occupational skin exposures can result in numerous diseases that can adversely affect an individual's health and capacity to perform at work. In general, there are three types of chemical-skin interactions of concern: direct skin effects, immune-mediated skin effects, and systemic effects. While hundreds of chemicals (metals, epoxy and acrylic resins, rubber additives, and chemical intermediates) present in virtually every industry have been identified to cause direct and immune-mediated effects such as contact dermatitis or urticaria, less is known about the number and types of chemicals contributing to systemic effects. In an attempt to raise awareness, skin notation assignments communicate the potential for dermal absorption; however, there is a need for standardization among agencies to communicate an accurate description of occupational hazards. Studies have suggested that exposure to complex mixtures, excessive hand washing, use of hand sanitizers, high frequency of wet work, and environmental or other factors may enhance penetration and stimulate other biological responses altering the outcomes of dermal chemical exposure. Understanding the hazards of dermal exposure is essential for the proper implementation of protective measures to ensure worker safety and health.

Responses of hadrons to the chemical potential at finite temperature

International Nuclear Information System (INIS)

Choe, S.; Liu, Y.; Miyamura, O.; Forcrand, Ph. de; Garcia Perez, M.; Hioki, S.; Matsufuru, H.; Nakamura, A.; Stamatescu, I.-O.; Takaishi, T.; Umeda, T.

2002-01-01

We present a framework to compute the responses of hadron masses to the chemical potential in lattice QCD simulations. As a first trial, the screening mass of the pseudoscalar meson and its first and second responses are evaluated. We present results on a 16x8 2 x4 lattice with two flavors of staggered quarks below and above T c . The responses to both the isoscalar and isovector chemical potentials are obtained. They show different behavior in the low and the high temperature phases, which may be explained as a consequence of chiral symmetry breaking and restoration, respectively

Chemical compounds from anthropogenic environment and immune evasion mechanisms: potential interactions.

Science.gov (United States)

Kravchenko, Julia; Corsini, Emanuela; Williams, Marc A; Decker, William; Manjili, Masoud H; Otsuki, Takemi; Singh, Neetu; Al-Mulla, Faha; Al-Temaimi, Rabeah; Amedei, Amedeo; Colacci, Anna Maria; Vaccari, Monica; Mondello, Chiara; Scovassi, A Ivana; Raju, Jayadev; Hamid, Roslida A; Memeo, Lorenzo; Forte, Stefano; Roy, Rabindra; Woodrick, Jordan; Salem, Hosni K; Ryan, Elizabeth P; Brown, Dustin G; Bisson, William H; Lowe, Leroy; Lyerly, H Kim

2015-06-01

An increasing number of studies suggest an important role of host immunity as a barrier to tumor formation and progression. Complex mechanisms and multiple pathways are involved in evading innate and adaptive immune responses, with a broad spectrum of chemicals displaying the potential to adversely influence immunosurveillance. The evaluation of the cumulative effects of low-dose exposures from the occupational and natural environment, especially if multiple chemicals target the same gene(s) or pathway(s), is a challenge. We reviewed common environmental chemicals and discussed their potential effects on immunosurveillance. Our overarching objective was to review related signaling pathways influencing immune surveillance such as the pathways involving PI3K/Akt, chemokines, TGF-β, FAK, IGF-1, HIF-1α, IL-6, IL-1α, CTLA-4 and PD-1/PDL-1 could individually or collectively impact immunosurveillance. A number of chemicals that are common in the anthropogenic environment such as fungicides (maneb, fluoxastrobin and pyroclostrobin), herbicides (atrazine), insecticides (pyridaben and azamethiphos), the components of personal care products (triclosan and bisphenol A) and diethylhexylphthalate with pathways critical to tumor immunosurveillance. At this time, these chemicals are not recognized as human carcinogens; however, it is known that they these chemicalscan simultaneously persist in the environment and appear to have some potential interfere with the host immune response, therefore potentially contributing to promotion interacting with of immune evasion mechanisms, and promoting subsequent tumor growth and progression. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Monte Carlo simulations of the NJL model near the nonzero temperature phase transition

International Nuclear Information System (INIS)

Strouthos, Costas; Christofi, Stavros

2005-01-01

We present results from numerical simulations of the Nambu-Jona-Lasinio model with an SU(2)xSU(2) chiral symmetry and N c = 4,8, and 16 quark colors at nonzero temperature. We performed the simulations by utilizing the hybrid Monte Carlo and hybrid Molecular Dynamics algorithms. We show that the model undergoes a second order phase transition. The critical exponents measured are consistent with the classical 3d O(4) universality class and hence in accordance with the dimensional reduction scenario. We also show that the Ginzburg region is suppressed by a factor of 1/N c in accordance with previous analytical predictions. (author)

Ergodic Capacity Analysis of Free-Space Optical Links with Nonzero Boresight Pointing Errors

KAUST Repository

Ansari, Imran Shafique

2015-04-01

A unified capacity analysis of a free-space optical (FSO) link that accounts for nonzero boresight pointing errors and both types of detection techniques (i.e. intensity modulation/ direct detection as well as heterodyne detection) is addressed in this work. More specifically, an exact closed-form expression for the moments of the end-to-end signal-to-noise ratio (SNR) of a single link FSO transmission system is presented in terms of well-known elementary functions. Capitalizing on these new moments expressions, we present approximate and simple closedform results for the ergodic capacity at high and low SNR regimes. All the presented results are verified via computer-based Monte-Carlo simulations.

Condensation phenomena in two-flavor scalar QED at finite chemical potential

CERN Document Server

Schmidt, Alexander; Gattringer, Christof

2014-01-01

We study condensation in two-flavored, scalar QED with non-degenerate masses at finite chemical potential. The conventional formulation of the theory has a sign problem at finite density which can be solved using an exact reformulation of the theory in terms of dual variables. We perform a Monte Carlo simulation in the dual representation and observe a condensation at a critical chemical potential $\\mu_c$. After determining the low-energy spectrum of the theory we try to establish a connection between $\\mu_c$ and the mass of the lightest excitation of the system, which are naively expected to be equal. It turns out, however, that the relation of the critical chemical potential to the mass spectrum in this case is non-trivial: Taking into account the form of the condensate and making some simplifying assumptions we suggest an adequate explanation which is supported by numerical results.

Chaotic amplification of neutrino chemical potentials by neutrino oscillations in big bang nucleosynthesis

International Nuclear Information System (INIS)

Shi, X.

1996-01-01

We investigate in detail the parameter space of active-sterile neutrino oscillations that amplifies neutrino chemical potentials at the epoch of big bang nucleosynthesis. We calculate the magnitude of the amplification and show evidence of chaos in the amplification process. We also discuss the implications of the neutrino chemical potential amplification in big bang nucleosynthesis. It is shown that with a ∼1 eV ν e , the amplification of its chemical potential by active-sterile neutrino oscillations can lower the effective number of neutrino species at big bang nucleosynthesis to significantly below three. copyright 1996 The American Physical Society

Chaotic amplification of neutrino chemical potentials by neutrino oscillations in big bang nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Shi, X. [Department of Physics, Queen`s University, Kingston, Ontario, K7L 3N6 (CANADA)

1996-08-01

We investigate in detail the parameter space of active-sterile neutrino oscillations that amplifies neutrino chemical potentials at the epoch of big bang nucleosynthesis. We calculate the magnitude of the amplification and show evidence of chaos in the amplification process. We also discuss the implications of the neutrino chemical potential amplification in big bang nucleosynthesis. It is shown that with a {approximately}1 eV {nu}{sub {ital e}}, the amplification of its chemical potential by active-sterile neutrino oscillations can lower the effective number of neutrino species at big bang nucleosynthesis to significantly below three. {copyright} {ital 1996 The American Physical Society.}

A density functional theory-based chemical potential equalisation

Indian Academy of Sciences (India)

A chemical potential equalisation scheme is proposed for the calculation of these quantities and hence the dipole polarizability within the framework of density functional theory based linear response theory. The resulting polarizability is expressed in terms of the contributions from individual atoms in the molecule. A few ...

Heavy-quark potential at finite temperature using the holographic correspondence

International Nuclear Information System (INIS)

Albacete, Javier L.; Kovchegov, Yuri V.; Taliotis, Anastasios

2008-01-01

We revisit the calculation of a heavy-quark potential in N=4 supersymmetric Yang-Mills theory at finite temperature using the AdS/CFT correspondence. As is widely known, the potential calculated in the pioneering works of Rey et al.[Nucl. Phys. B527, 171 (1998)] and Brandhuber et al.[Phys. Lett. B 434, 36 (1998)] is zero for separation distances r between the quark and the antiquark above a certain critical separation, at which the potential has a kink. We point out that by analytically continuing the string configurations into the complex plane, and using a slightly different renormalization subtraction, one obtains a smooth nonzero (negative definite) potential without a kink. The obtained potential also has a nonzero imaginary (absorptive) part for separations r>r c =0.870/πT. Most importantly, at large separations r the real part of the potential does not exhibit the exponential Debye falloff expected from perturbation theory and instead falls off as a power law, proportional to 1/r 4 for r>r 0 =2.702/πT.

Economic potential of natural gas-fired cogeneration--analysis of Brazil's chemical industry

International Nuclear Information System (INIS)

Szklo, A.S.; Soares, J.B.; Tolmasquim, M.T.

2004-01-01

This paper attempts to estimate the technical and economic potential for natural gas-fired cogeneration (NGCHP) in Brazil's chemical industry as well as also analyses the impacts of specific incentive policies on the economic feasibility of this potential. Currently, the NGCHP installed capacity at Brazil's chemical industry is still quite a low figure, although the chemical plants are under heavy pressures to: (1) cut costs; and (2) show a rising awareness of the importance of power service quality, underscored even more heavily by Brazil's recent power crisis. According this study, a natural gas-fired remaining technical potential of 1.4 GW is noted in the Brazilian chemical industry. Financing policies showed to be the stand-alone policy that would be most successful for ensuring the economic feasibility of this technical potential. Nevertheless, this policy proved to be affected by the economic scenario under consideration, which includes world oil prices, electricity tariff and foreign exchange ratio possible paths. Consequently, the key issue is related to the ability to assess which economic scenario is rated as more probable by possible future investors in NGCHP, and then selecting the most appropriate incentive policy

Vector tomography for reconstructing electric fields with non-zero divergence in bounded domains

Science.gov (United States)

Koulouri, Alexandra; Brookes, Mike; Rimpiläinen, Ville

2017-01-01

In vector tomography (VT), the aim is to reconstruct an unknown multi-dimensional vector field using line integral data. In the case of a 2-dimensional VT, two types of line integral data are usually required. These data correspond to integration of the parallel and perpendicular projection of the vector field along the integration lines and are called the longitudinal and transverse measurements, respectively. In most cases, however, the transverse measurements cannot be physically acquired. Therefore, the VT methods are typically used to reconstruct divergence-free (or source-free) velocity and flow fields that can be reconstructed solely from the longitudinal measurements. In this paper, we show how vector fields with non-zero divergence in a bounded domain can also be reconstructed from the longitudinal measurements without the need of explicitly evaluating the transverse measurements. To the best of our knowledge, VT has not previously been used for this purpose. In particular, we study low-frequency, time-harmonic electric fields generated by dipole sources in convex bounded domains which arise, for example, in electroencephalography (EEG) source imaging. We explain in detail the theoretical background, the derivation of the electric field inverse problem and the numerical approximation of the line integrals. We show that fields with non-zero divergence can be reconstructed from the longitudinal measurements with the help of two sparsity constraints that are constructed from the transverse measurements and the vector Laplace operator. As a comparison to EEG source imaging, we note that VT does not require mathematical modeling of the sources. By numerical simulations, we show that the pattern of the electric field can be correctly estimated using VT and the location of the source activity can be determined accurately from the reconstructed magnitudes of the field.

Prebiotic Potential and Chemical Composition of Seven Culinary Spice Extracts

OpenAIRE

Lu, Qing‐Yi; Summanen, Paula H.; Lee, Ru‐Po; Huang, Jianjun; Henning, Susanne M.; Heber, David; Finegold, Sydney M.; Li, Zhaoping

2017-01-01

Abstract The objective of this study was to investigate prebiotic potential, chemical composition, and antioxidant capacity of spice extracts. Seven culinary spices including black pepper, cayenne pepper, cinnamon, ginger, Mediterranean oregano, rosemary, and turmeric were extracted with boiling water. Major chemical constituents were characterized by RP‐HPLC‐DAD method and antioxidant capacity was determined by measuring colorimetrically the extent to scavenge ABTS radical cations. Effects o...

Higher spin entanglement entropy at finite temperature with chemical potential

Energy Technology Data Exchange (ETDEWEB)

Chen, Bin [Department of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University,Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter,5 Yiheyuan Rd, Beijing 100871 (China); Center for High Energy Physics, Peking University,5 Yiheyuan Rd, Beijing 100871 (China); Beijing Center for Mathematics and Information Interdisciplinary Sciences, Beijing 100048 (China); Wu, Jie-qiang [Department of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University,Beijing 100871 (China)

2016-07-11

It is generally believed that the semiclassical AdS{sub 3} higher spin gravity could be described by a two dimensional conformal field theory with W-algebra symmetry in the large central charge limit. In this paper, we study the single interval entanglement entropy on the torus in the CFT with a W{sub 3} deformation. More generally we develop the monodromy analysis to compute the two-point function of the light operators under a thermal density matrix with a W{sub 3} chemical potential to the leading order. Holographically we compute the probe action of the Wilson line in the background of the spin-3 black hole with a chemical potential. We find exact agreement.

Repulsive baryonic interactions and lattice QCD observables at imaginary chemical potential

Directory of Open Access Journals (Sweden)

Volodymyr Vovchenko

2017-12-01

Full Text Available The first principle lattice QCD methods allow to calculate the thermodynamic observables at finite temperature and imaginary chemical potential. These can be compared to the predictions of various phenomenological models. We argue that Fourier coefficients with respect to imaginary baryochemical potential are sensitive to modeling of baryonic interactions. As a first application of this sensitivity, we consider the hadron resonance gas (HRG model with repulsive baryonic interactions, which are modeled by means of the excluded volume correction. The Fourier coefficients of the imaginary part of the net-baryon density at imaginary baryochemical potential – corresponding to the fugacity or virial expansion at real chemical potential – are calculated within this model, and compared with the Nt=12 lattice data. The lattice QCD behavior of the first four Fourier coefficients up to T≃185 MeV is described fairly well by an interacting HRG with a single baryon–baryon eigenvolume interaction parameter b≃1 fm3, while the available lattice data on the difference χ2B−χ4B of baryon number susceptibilities is reproduced up to T≃175 MeV. Keywords: Hadron resonance gas, Excluded volume, Imaginary chemical potential

Metastability of the (φiφi)32 model at finite temperature and density

International Nuclear Information System (INIS)

Ananos, G.N.J.; Malbouisson, A.P.C.; Svaiter, N.F.

1996-11-01

Using concurrently the dimensional and analytic regularization methods we applied the Gross-Neveu model at finite temperature and density (chemical potential) in a D-dimensional spacetime. The renormalized effective potential is presented at the one-loop approximation. In the case of non-zero chemical potential we show that the effective potential acquires an imaginary part, which means that the system becomes metastable, indicating the possibility of a first phase transition. (author)

The Potential Of Cultural And Chemical Control Practices For ...

African Journals Online (AJOL)

The Potential Of Cultural And Chemical Control Practices For Enhancing ... and a significant (P < 0.05) increase in yield components of hands per bunch and finger ... Une étude de l\\'effet de la population de plantes, l\\'application des engrais, ...

Bandwidth Study on Energy Use and Potential Energy Saving Opportunities in U.S. Chemical Manufacturing

Energy Technology Data Exchange (ETDEWEB)

Sabine Brueske, Caroline Kramer, Aaron Fisher

2015-06-01

Energy bandwidth studies of U.S. manufacturing sectors can serve as foundational references in framing the range (or bandwidth) of potential energy savings opportunities. This bandwidth study examines energy consumption and potential energy savings opportunities in U.S. chemical manufacturing. The study relies on multiple sources to estimate the energy used in the production of 74 individual chemicals, representing 57% of sector-wide energy consumption. Energy savings opportunities for individual chemicals and for 15 subsectors of chemicals manufacturing are based on technologies currently in use or under development; these potential savings are then extrapolated to estimate sector-wide energy savings opportunity.

Shear Viscosity of Hot QED at Finite Chemical Potential from Kubo Formula

International Nuclear Information System (INIS)

Liu Hui; Hou Defu; Li Jiarong

2008-01-01

Within the framework of finite temperature feld theory this paper discusses the shear viscosity of hot QED plasma through Kubo formula at one-loop skeleton diagram level with a finite chemical potential. The effective widths (damping rates) are introduced to regulate the pinch singularities and then gives a reliable estimation of the shear viscous coefficient. The finite chemical potential contributes positively compared to the pure temperature case. The result agrees with that from the kinetics theory qualitatively

Correlation Decay in Fermionic Lattice Systems with Power-Law Interactions at Nonzero Temperature

Science.gov (United States)

Hernández-Santana, Senaida; Gogolin, Christian; Cirac, J. Ignacio; Acín, Antonio

2017-09-01

We study correlations in fermionic lattice systems with long-range interactions in thermal equilibrium. We prove a bound on the correlation decay between anticommuting operators and generalize a long-range Lieb-Robinson-type bound. Our results show that in these systems of spatial dimension D with, not necessarily translation invariant, two-site interactions decaying algebraically with the distance with an exponent α ≥2 D , correlations between such operators decay at least algebraically to 0 with an exponent arbitrarily close to α at any nonzero temperature. Our bound is asymptotically tight, which we demonstrate by a high temperature expansion and by numerically analyzing density-density correlations in the one-dimensional quadratic (free, exactly solvable) Kitaev chain with long-range pairing.

Double beta decay and majorana neutrinos. Right-handed currents or nonzero masses

International Nuclear Information System (INIS)

Rosen, S.P.; Perlmutter, A.

1981-01-01

This chapter describes some new developments concerning the mechanism for lepton number nonconservation in no-neutrino double beta decay. Explains that lepton number nonconservation in no-neutrino double beta decay comes about either because both left- and right-handed components of a Majorano neutrino are coupled to the electron in the weak leptonic current, or because the neutrino has nonzero mass. Shows that while nuclear ground-state to ground-state transitions arise from right-handed currents and from neutrino mass terms, transitions to low-lying excited states with J /SUP P/ =2 + can arise only from right-handed currents. Emphasizes that the possibilities of detecting small admixtures of right-handed currents, and of setting limits on neutrino masses that are either very small or very large, make double beta decay a most rewarding phenomenon to study

Quantum Effects for a Proton in a Low-Barrier, Double-Well Potential: Core Level Photoemission Spectroscopy of Acetylacetone.

Science.gov (United States)

Feyer, Vitaliy; Prince, Kevin C; Coreno, Marcello; Melandri, Sonia; Maris, Assimo; Evangelisti, Luca; Caminati, Walther; Giuliano, Barbara M; Kjaergaard, Henrik G; Carravetta, Vincenzo

2018-02-01

We have performed core level photoemission spectroscopy of gaseous acetylacetone, its fully deuterated form, and two derivatives, benzoylacetone and dibenzoylmethane. These molecules show intramolecular hydrogen bonds, with a proton located in a double-well potential, whose barrier height is different for the three compounds. This has allowed us to examine the effect of the double-well potential on photoemission spectra. Two distinct O 1s core hole peaks are observed, previously assigned to two chemical states of oxygen. We provide an alternative assignment of the double-peak structure of O 1s spectra by taking full account of the extended nature of the wave function associated with the nuclear motion of the proton, the shape of the ground and final state potentials in which the proton is located, and the nonzero temperature of the samples. The peaks are explained in terms of an unusual Franck-Condon factor distribution.

Detailed balance method for chemical potential determination in Monte Carlo and molecular dynamics simulations

International Nuclear Information System (INIS)

Fay, P.J.; Ray, J.R.; Wolf, R.J.

1994-01-01

We present a new, nondestructive, method for determining chemical potentials in Monte Carlo and molecular dynamics simulations. The method estimates a value for the chemical potential such that one has a balance between fictitious successful creation and destruction trials in which the Monte Carlo method is used to determine success or failure of the creation/destruction attempts; we thus call the method a detailed balance method. The method allows one to obtain estimates of the chemical potential for a given species in any closed ensemble simulation; the closed ensemble is paired with a ''natural'' open ensemble for the purpose of obtaining creation and destruction probabilities. We present results for the Lennard-Jones system and also for an embedded atom model of liquid palladium, and compare to previous results in the literature for these two systems. We are able to obtain an accurate estimate of the chemical potential for the Lennard-Jones system at higher densities than reported in the literature

Prebiotic Potential and Chemical Composition of Seven Culinary Spice Extracts.

Science.gov (United States)

Lu, Qing-Yi; Summanen, Paula H; Lee, Ru-Po; Huang, Jianjun; Henning, Susanne M; Heber, David; Finegold, Sydney M; Li, Zhaoping

2017-08-01

The objective of this study was to investigate prebiotic potential, chemical composition, and antioxidant capacity of spice extracts. Seven culinary spices including black pepper, cayenne pepper, cinnamon, ginger, Mediterranean oregano, rosemary, and turmeric were extracted with boiling water. Major chemical constituents were characterized by RP-HPLC-DAD method and antioxidant capacity was determined by measuring colorimetrically the extent to scavenge ABTS radical cations. Effects of spice extracts on the viability of 88 anaerobic and facultative isolates from intestinal microbiota were determined by using Brucella agar plates containing serial dilutions of extracts. A total of 14 phenolic compounds, a piperine, cinnamic acid, and cinnamaldehyde were identified and quantitated. Spice extracts exhibited high antioxidant capacity that correlated with the total amount of major chemicals. All spice extracts, with the exception of turmeric, enhanced the growth of Bifidobacterium spp. and Lactobacillus spp. All spices exhibited inhibitory activity against selected Ruminococcus species. Cinnamon, oregano, and rosemary were active against selected Fusobacterium strains and cinnamon, rosemary, and turmeric were active against selected Clostridium spp. Some spices displayed prebiotic-like activity by promoting the growth of beneficial bacteria and suppressing the growth of pathogenic bacteria, suggesting their potential role in the regulation of intestinal microbiota and the enhancement of gastrointestinal health. The identification and quantification of spice-specific phytochemicals provided insight into the potential influence of these chemicals on the gut microbial communities and activities. Future research on the connections between spice-induced changes in gut microbiota and host metabolism and disease preventive effect in animal models and humans is needed. © 2017 The Authors. Journal of Food Science published by Wiley Periodicals, Inc. on behalf of Institute of

Chemical potential and internal energy of the noninteracting Fermi ...

Indian Academy of Sciences (India)

entropy by T, dV is the change in volume by p and µ is the chemical potential. When S .... thin films are actually not 2D objects, but fractals with Hausdorff dimensionalities between 2D ..... sharpness of the edge of the Fermi surface is lost. In the ...

Steady bound electromagnetic eigenstate arises in a homogeneous isotropic linear metamaterial with zero-real-part-of-impedance and nonzero-imaginary-part-of-wave-vector

Science.gov (United States)

Chen, Jiangwei; Dai, Yuyao; Yan, Lin; Zhao, Huimin

2018-04-01

In this paper, we shall demonstrate theoretically that steady bound electromagnetic eigenstate can arise in an infinite homogeneous isotropic linear metamaterial with zero-real-part-of-impedance and nonzero-imaginary-part-of-wave-vector, which is partly attributed to that, here, nonzero-imaginary-part-of-wave-vector is not involved with energy losses or gain. Altering value of real-part-of-impedance of the metamaterial, the bound electromagnetic eigenstate may become to be a progressive wave. Our work may be useful to further understand energy conversion and conservation properties of electromagnetic wave in the dispersive and absorptive medium and provides a feasible route to stop, store and release electromagnetic wave (light) conveniently by using metamaterial with near-zero-real-part-of-impedance.

An efficient iterative grand canonical Monte Carlo algorithm to determine individual ionic chemical potentials in electrolytes.

Science.gov (United States)

Malasics, Attila; Boda, Dezso

2010-06-28

Two iterative procedures have been proposed recently to calculate the chemical potentials corresponding to prescribed concentrations from grand canonical Monte Carlo (GCMC) simulations. Both are based on repeated GCMC simulations with updated excess chemical potentials until the desired concentrations are established. In this paper, we propose combining our robust and fast converging iteration algorithm [Malasics, Gillespie, and Boda, J. Chem. Phys. 128, 124102 (2008)] with the suggestion of Lamperski [Mol. Simul. 33, 1193 (2007)] to average the chemical potentials in the iterations (instead of just using the chemical potentials obtained in the last iteration). We apply the unified method for various electrolyte solutions and show that our algorithm is more efficient if we use the averaging procedure. We discuss the convergence problems arising from violation of charge neutrality when inserting/deleting individual ions instead of neutral groups of ions (salts). We suggest a correction term to the iteration procedure that makes the algorithm efficient to determine the chemical potentials of individual ions too.

Novel scheme to compute chemical potentials of chain molecules on a lattice

Science.gov (United States)

Mooij, G. C. A. M.; Frenkel, D.

We present a novel method that allows efficient computation of the total number of allowed conformations of a chain molecule in a dense phase. Using this method, it is possible to estimate the chemical potential of such a chain molecule. We have tested the present method in simulations of a two-dimensional monolayer of chain molecules on a lattice (Whittington-Chapman model) and compared it with existing schemes to compute the chemical potential. We find that the present approach is two to three orders of magnitude faster than the most efficient of the existing methods.

Maximum run-up behavior of tsunamis under non-zero initial velocity condition

Directory of Open Access Journals (Sweden)

Baran AYDIN

2018-03-01

Full Text Available The tsunami run-up problem is solved non-linearly under the most general initial conditions, that is, for realistic initial waveforms such as N-waves, as well as standard initial waveforms such as solitary waves, in the presence of initial velocity. An initial-boundary value problem governed by the non-linear shallow-water wave equations is solved analytically utilizing the classical separation of variables technique, which proved to be not only fast but also accurate analytical approach for this type of problems. The results provide important information on maximum tsunami run-up qualitatively. We observed that, although the calculated maximum run-ups increase significantly, going as high as double that of the zero-velocity case, initial waves having non-zero fluid velocity exhibit the same run-up behavior as waves without initial velocity, for all wave types considered in this study.

Approximate analytical solutions of Klein-Gordon equation with Hulthen potentials for nonzero angular momentum

International Nuclear Information System (INIS)

Chen Changyuan; Sun Dongsheng; Lu Falin

2007-01-01

Using the exponential function transformation approach along with an approximation for the centrifugal potential, the radial Klein-Gordon equation with the vector and scalar Hulthen potential is transformed to a hypergeometric differential equation. The approximate analytical solutions of bound states are attained for different l. The analytical energy equation and the unnormalized radial wave functions expressed in terms of hypergeometric polynomials are given

Chemical Potential Dependence of the Dressed-Quark Propagator from an Effective Quark-Quark Interaction

Institute of Scientific and Technical Information of China (English)

ZONG Hong-Shi; PING Jia-Lun; SUN Wei-Min; CHANG Chao-Hsi; WANG Fan

2002-01-01

We exhibit a method for obtaining the low chemical potential dependence of the dressed quark propagatorfrom an effective quark-quark interaction model. Within this approach we explore the chemical potential dependenceof the dressed-quark propagator, which provides a means of determining the behavior of the chiral and deconfinementorder parameters. A comparison with the results of previous researches is given.

Survey of knowledge of hazards of chemicals potentially associated with the advanced isotope separation processes

International Nuclear Information System (INIS)

Chester, R.O.; Kirkscey, K.A.; Randolph, M.L.

1979-09-01

Hazards of chemical potentially associated with the advanced isotope separation processes are estimated based on open literature references. The tentative quantity of each chemical associated with the processes and the toxicity of the chemical are used to estimate this hazard. The chemicals thus estimated to be the most potentially hazardous to health are fluorine, nitric acid, uranium metal, uranium hexafluoride, and uranium dust. The estimated next most hazardous chemicals are bromine, hydrobromic acid, hydrochloric acid, and hydrofluoric acid. For each of these chemicals and for a number of other process-associated chemicals the following information is presented: (1) any applicable standards, recommended standards and their basis; (2) a brief discussion to toxic effects including short exposure tolerance, atmospheric concentration immediately hazardous to life, evaluation of exposures, recommended control procedures, chemical properties, and a list of any toxicology reviews; and (3) recommendations for future research

Survey of knowledge of hazards of chemicals potentially associated with the advanced isotope separation processes

Energy Technology Data Exchange (ETDEWEB)

Chester, R.O.; Kirkscey, K.A.; Randolph, M.L.

1979-09-01

Hazards of chemical potentially associated with the advanced isotope separation processes are estimated based on open literature references. The tentative quantity of each chemical associated with the processes and the toxicity of the chemical are used to estimate this hazard. The chemicals thus estimated to be the most potentially hazardous to health are fluorine, nitric acid, uranium metal, uranium hexafluoride, and uranium dust. The estimated next most hazardous chemicals are bromine, hydrobromic acid, hydrochloric acid, and hydrofluoric acid. For each of these chemicals and for a number of other process-associated chemicals the following information is presented: (1) any applicable standards, recommended standards and their basis; (2) a brief discussion to toxic effects including short exposure tolerance, atmospheric concentration immediately hazardous to life, evaluation of exposures, recommended control procedures, chemical properties, and a list of any toxicology reviews; and (3) recommendations for future research.

Nonthreshold D-brane bound states and black holes with nonzero entropy

International Nuclear Information System (INIS)

Costa, M.S.; Cvetic, M.

1997-01-01

We start with Bogomol close-quote nyi-Prasad-Sommerfield- (BPS) saturated configurations of two (orthogonally) intersecting M-branes and use the electromagnetic duality or dimensional reduction along a boost, in order to obtain new p-brane bound states. In the first case the resulting configurations are interpreted as BPS-saturated nonthreshold bound states of intersecting p-branes, and in the second case as p-branes intersecting at angles and their duals. As a by-product we deduce the enhancement of supersymmetry as the angle approaches zero. We also comment on the D-brane theory describing these new bound states, and a connection between the angle and the world-volume gauge fields of the D-brane system. We use these configurations to find new embeddings of the four- and five-dimensional black holes with nonzero entropy, whose entropy now also depends on the angle and world-volume gauge fields. The corresponding D-brane configuration sheds light on the microscopic entropy of such black holes. copyright 1997 The American Physical Society

Gravitational instabilities of the cosmic neutrino background with non-zero lepton number

Directory of Open Access Journals (Sweden)

Neil D. Barrie

2017-09-01

Full Text Available We argue that a cosmic neutrino background that carries non-zero lepton charge develops gravitational instabilities. Fundamentally, these instabilities are related to the mixed gravity-lepton number anomaly. We have explicitly computed the gravitational Chern–Simons term which is generated quantum-mechanically in the effective action in the presence of a lepton number asymmetric neutrino background. The induced Chern–Simons term has a twofold effect: (i gravitational waves propagating in such a neutrino background exhibit birefringent behaviour leading to an enhancement/suppression of the gravitational wave amplitudes depending on the polarisation, where the magnitude of this effect is related to the size of the lepton asymmetry; (ii Negative energy graviton modes are induced in the high frequency regime, which leads to very fast vacuum decay producing, e.g., positive energy photons and negative energy gravitons. From the constraint on the present radiation energy density, we obtain an interesting bound on the lepton asymmetry of the universe.

Bianchi type I universe in brane world scenario with non-zero Weyl tensor of the bulk

Energy Technology Data Exchange (ETDEWEB)

Chaudhuri, S. [University of Burdwan, Department of Physics, Burdwan (India)

2017-09-15

In the paper, we present exact solutions of gravitational field equations for an anisotropic brane with a Bianchi type I universe with perfect fluid having non-vanishing Weyl tensor of the bulk. It is assumed that the thermodynamic pressure bears a linear relation with the energy density. For a particular non-zero value of the pressure the solutions are obtained in an exact analytic form with and without the cosmological constant for a Bianchi type I universe. The relevant physical quantities associated with the evolution of the universe are also derived in the two cases. (orig.)

CO2 emissions and reduction potential in China's chemical industry

International Nuclear Information System (INIS)

Zhu, Bing; Zhou, Wenji; Hu, Shanying; Li, Qiang; Griffy-Brown, Charla; Jin, Yong

2010-01-01

GHG (Increasing greenhouse gas) emissions in China imposes enormous pressure on China's government and society. The increasing GHG trend is primarily driven by the fast expansion of high energy-intensive sectors including the chemical industry. This study investigates energy consumption and CO 2 emissions in the processes of chemical production in China through calculating the amounts of CO 2 emissions and estimating the reduction potential in the near future. The research is based on a two-level perspective which treats the entire industry as Level one and six key sub-sectors as Level two, including coal-based ammonia, calcium carbide, caustic soda, coal-based methanol, sodium carbonate, and yellow phosphorus. These two levels are used in order to address the complexity caused by the fact that there are more than 40 thousand chemical products in this industry and the performance levels of the technologies employed are extremely uneven. Three scenarios with different technological improvements are defined to estimate the emissions of the six sub-sectors and analyze the implied reduction potential in the near future. The results highlight the pivotal role that regulation and policy administration could play in controlling the CO 2 emissions by promoting average technology performances in this industry.

The local temperature and chemical potential inside a mesoscopic device driven out of equilibrium

International Nuclear Information System (INIS)

Wang, Pei

2011-01-01

In this paper we introduce a method for calculating the local temperature and chemical potential inside a mesoscopic device out of equilibrium. We show how to check the conditions of local thermal equilibrium when the whole system is out of equilibrium. In particular, we study the on-site chemical potentials inside a chain coupled to two reservoirs at a finite voltage bias. We observe in the presence of disorder a large fluctuation in on-site chemical potentials, which can be suppressed by the electron–electron interaction. By taking the average with respect to the configurations of the disorder, we recover the classical picture where the voltage drops monotonically through the resistance wire. We prove the existence of local intensive variables in a mesoscopic device which is in equilibrium or not far from equilibrium

Chemical Potential Tuning and Enhancement of Thermoelectric Properties in Indium Selenides.

Science.gov (United States)

Rhyee, Jong-Soo; Kim, Jin Hee

2015-03-20

Researchers have long been searching for the materials to enhance thermoelectric performance in terms of nano scale approach in order to realize phonon-glass-electron-crystal and quantum confinement effects. Peierls distortion can be a pathway to enhance thermoelectric figure-of-merit ZT by employing natural nano-wire-like electronic and thermal transport. The phonon-softening known as Kohn anomaly, and Peierls lattice distortion decrease phonon energy and increase phonon scattering, respectively, and, as a result, they lower thermal conductivity. The quasi-one-dimensional electrical transport from anisotropic band structure ensures high Seebeck coefficient in Indium Selenide. The routes for high ZT materials development of In₄Se₃ - δ are discussed from quasi-one-dimensional property and electronic band structure calculation to materials synthesis, crystal growth, and their thermoelectric properties investigations. The thermoelectric properties of In₄Se₃ - δ can be enhanced by electron doping, as suggested from the Boltzmann transport calculation. Regarding the enhancement of chemical potential, the chlorine doped In₄Se₃ - δ Cl 0.03 compound exhibits high ZT over a wide temperature range and shows state-of-the-art thermoelectric performance of ZT = 1.53 at 450 °C as an n -type material. It was proven that multiple elements doping can enhance chemical potential further. Here, we discuss the recent progress on the enhancement of thermoelectric properties in Indium Selenides by increasing chemical potential.

Metastability of the ({phi}{sub i}{phi}{sub i}){sub 3}{sup 2} model at finite temperature and density

Energy Technology Data Exchange (ETDEWEB)

Ananos, G.N.J.; Malbouisson, A.P.C.; Svaiter, N.F.

1996-11-01

Using concurrently the dimensional and analytic regularization methods we applied the Gross-Neveu model at finite temperature and density (chemical potential) in a D-dimensional spacetime. The renormalized effective potential is presented at the one-loop approximation. In the case of non-zero chemical potential we show that the effective potential acquires an imaginary part, which means that the system becomes metastable, indicating the possibility of a first phase transition. (author). 13 refs.; e-mail: nfuxsvai at lca1.drp.cbpf.br.

Chemicals from Biomass: A Market Assessment of Bioproducts with Near-Term Potential

Energy Technology Data Exchange (ETDEWEB)

Biddy, Mary J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Scarlata, Christopher [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kinchin, Christopher [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2016-03-23

Production of chemicals from biomass offers a promising opportunity to reduce U.S. dependence on imported oil, as well as to improve the overall economics and sustainability of an integrated biorefinery. Given the increasing momentum toward the deployment and scale-up of bioproducts, this report strives to: (1) summarize near-term potential opportunities for growth in biomass-derived products; (2) identify the production leaders who are actively scaling up these chemical production routes; (3) review the consumers and market champions who are supporting these efforts; (4) understand the key drivers and challenges to move biomass-derived chemicals to market; and (5) evaluate the impact that scale-up of chemical strategies will have on accelerating the production of biofuels.

The potential role of life cycle assessment in regulation of chemicals in the European Union

DEFF Research Database (Denmark)

Christensen, Frans Møller; Olsen, Stig Irving

2004-01-01

Scope and Background. This paper presents the preliminary results from an ongoing feasibility study, investigating potential application of elements from the life cycle assessment (LCA) framework in European chemicals' policy. Many policy areas affect manufacturing, marketing and use of chemicals...... dialogues with various stakeholders. Results and Discussion. LCAs are comparative and more holistic in view as compared to chemical risk assessments for regulatory purposes1. LCAs may therefore potentially improve the basis for decisions between alternatives in cases where a risk assessment calls for risk...

Vector tomography for reconstructing electric fields with non-zero divergence in bounded domains

Energy Technology Data Exchange (ETDEWEB)

Koulouri, Alexandra, E-mail: koulouri@uni-muenster.de [Institute for Computational and Applied Mathematics, University of Münster, Einsteinstrasse 62, D-48149 Münster (Germany); Department of Electrical and Electronic Engineering, Imperial College London, Exhibition Road, London SW7 2BT (United Kingdom); Brookes, Mike [Department of Electrical and Electronic Engineering, Imperial College London, Exhibition Road, London SW7 2BT (United Kingdom); Rimpiläinen, Ville [Institute for Biomagnetism and Biosignalanalysis, University of Münster, Malmedyweg 15, D-48149 Münster (Germany); Department of Mathematics, University of Auckland, Private bag 92019, Auckland 1142 (New Zealand)

2017-01-15

In vector tomography (VT), the aim is to reconstruct an unknown multi-dimensional vector field using line integral data. In the case of a 2-dimensional VT, two types of line integral data are usually required. These data correspond to integration of the parallel and perpendicular projection of the vector field along the integration lines and are called the longitudinal and transverse measurements, respectively. In most cases, however, the transverse measurements cannot be physically acquired. Therefore, the VT methods are typically used to reconstruct divergence-free (or source-free) velocity and flow fields that can be reconstructed solely from the longitudinal measurements. In this paper, we show how vector fields with non-zero divergence in a bounded domain can also be reconstructed from the longitudinal measurements without the need of explicitly evaluating the transverse measurements. To the best of our knowledge, VT has not previously been used for this purpose. In particular, we study low-frequency, time-harmonic electric fields generated by dipole sources in convex bounded domains which arise, for example, in electroencephalography (EEG) source imaging. We explain in detail the theoretical background, the derivation of the electric field inverse problem and the numerical approximation of the line integrals. We show that fields with non-zero divergence can be reconstructed from the longitudinal measurements with the help of two sparsity constraints that are constructed from the transverse measurements and the vector Laplace operator. As a comparison to EEG source imaging, we note that VT does not require mathematical modeling of the sources. By numerical simulations, we show that the pattern of the electric field can be correctly estimated using VT and the location of the source activity can be determined accurately from the reconstructed magnitudes of the field. - Highlights: • Vector tomography is used to reconstruct electric fields generated by dipole

Three loop HTL perturbation theory at finite temperature and chemical potential

Energy Technology Data Exchange (ETDEWEB)

Strickland, Michael [Department of Physics, Kent State University, Kent, OH 44242 (United States); Andersen, Jens O. [Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim (Norway); Bandyopadhyay, Aritra; Haque, Najmul; Mustafa, Munshi G. [Theory Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Su, Nan [Faculty of Physics, University of Bielefeld, D-33615 Bielefeld (Germany)

2014-11-15

In this proceedings contribution we present a recent three-loop hard-thermal-loop perturbation theory (HTLpt) calculation of the thermodynamic potential for a finite temperature and chemical potential system of quarks and gluons. We compare the resulting pressure, trace anomaly, and diagonal/off-diagonal quark susceptibilities with lattice data. We show that there is good agreement between the three-loop HTLpt analytic result and available lattice data.

Computational Methods to Assess the Production Potential of Bio-Based Chemicals.

Science.gov (United States)

Campodonico, Miguel A; Sukumara, Sumesh; Feist, Adam M; Herrgård, Markus J

2018-01-01

Elevated costs and long implementation times of bio-based processes for producing chemicals represent a bottleneck for moving to a bio-based economy. A prospective analysis able to elucidate economically and technically feasible product targets at early research phases is mandatory. Computational tools can be implemented to explore the biological and technical spectrum of feasibility, while constraining the operational space for desired chemicals. In this chapter, two different computational tools for assessing potential for bio-based production of chemicals from different perspectives are described in detail. The first tool is GEM-Path: an algorithm to compute all structurally possible pathways from one target molecule to the host metabolome. The second tool is a framework for Modeling Sustainable Industrial Chemicals production (MuSIC), which integrates modeling approaches for cellular metabolism, bioreactor design, upstream/downstream processes, and economic impact assessment. Integrating GEM-Path and MuSIC will play a vital role in supporting early phases of research efforts and guide the policy makers with decisions, as we progress toward planning a sustainable chemical industry.

Chemical Potential Tuning and Enhancement of Thermoelectric Properties in Indium Selenides

Directory of Open Access Journals (Sweden)

Jong-Soo Rhyee

2015-03-01

Full Text Available Researchers have long been searching for the materials to enhance thermoelectric performance in terms of nano scale approach in order to realize phonon-glass-electron-crystal and quantum confinement effects. Peierls distortion can be a pathway to enhance thermoelectric figure-of-merit ZT by employing natural nano-wire-like electronic and thermal transport. The phonon-softening known as Kohn anomaly, and Peierls lattice distortion decrease phonon energy and increase phonon scattering, respectively, and, as a result, they lower thermal conductivity. The quasi-one-dimensional electrical transport from anisotropic band structure ensures high Seebeck coefficient in Indium Selenide. The routes for high ZT materials development of In4Se3−δ are discussed from quasi-one-dimensional property and electronic band structure calculation to materials synthesis, crystal growth, and their thermoelectric properties investigations. The thermoelectric properties of In4Se3−δ can be enhanced by electron doping, as suggested from the Boltzmann transport calculation. Regarding the enhancement of chemical potential, the chlorine doped In4Se3−δCl0.03 compound exhibits high ZT over a wide temperature range and shows state-of-the-art thermoelectric performance of ZT = 1.53 at 450 °C as an n-type material. It was proven that multiple elements doping can enhance chemical potential further. Here, we discuss the recent progress on the enhancement of thermoelectric properties in Indium Selenides by increasing chemical potential.

Dual lattice representations for O(N and CP(N−1 models with a chemical potential

Directory of Open Access Journals (Sweden)

Falk Bruckmann

2015-10-01

Full Text Available We derive dual representations for O(N and CP(N−1 models on the lattice. In terms of the dual variables the partition sums have only real and positive contributions also at finite chemical potential. Thus the complex action problem of the conventional formulation is overcome and using the dual variables Monte Carlo simulations are possible at arbitrary chemical potential.

Pion properties at finite isospin chemical potential with isospin symmetry breaking

Science.gov (United States)

Wu, Zuqing; Ping, Jialun; Zong, Hongshi

2017-12-01

Pion properties at finite temperature, finite isospin and baryon chemical potentials are investigated within the SU(2) NJL model. In the mean field approximation for quarks and random phase approximation fpr mesons, we calculate the pion mass, the decay constant and the phase diagram with different quark masses for the u quark and d quark, related to QCD corrections, for the first time. Our results show an asymmetry between μI 0 in the phase diagram, and different values for the charged pion mass (or decay constant) and neutral pion mass (or decay constant) at finite temperature and finite isospin chemical potential. This is caused by the effect of isospin symmetry breaking, which is from different quark masses. Supported by National Natural Science Foundation of China (11175088, 11475085, 11535005, 11690030) and the Fundamental Research Funds for the Central Universities (020414380074)

Lattice QCD with chemical potential: Evading the fermion-sign problem

Indian Academy of Sciences (India)

Department of Theoretical Physics, Tata Institute of Fundamental Research, .... baryon and electric charge remain conserved, and only these two chemical potentials ..... of the equation of state also shows a power law behaviour for small n/T 3. In QCD with .... talk of C Schmidt in SEWM 2004 (Helsinki) for more on this topic.

Mobility and Attenuation Dynamics of Potentially Toxic Chemical Species at an Abandoned Copper Mine Tailings Dump

Directory of Open Access Journals (Sweden)

Wilson Mugera Gitari

2018-02-01

Full Text Available Large volumes of disposed mine tailings abound in several regions of South Africa, as a consequence of unregulated, unsustainable long years of mining activities. Tailings dumps occupy a large volume of valuable land, and present a potential risk for aquatic systems, through leaching of potentially toxic chemical species. This paper reports on the evaluation of the geochemical processes controlling the mobility of potentially toxic chemical species within the tailings profile, and their potential risk with regard to surface and groundwater systems. Combination of X-ray fluorescence (XRF, X-ray diffraction (XRD, and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS techniques, show that the tailing profiles are uniform, weakly altered, and vary slightly with depth in both physical and geochemical properties, as well as mineralogical composition. Mineralogical analysis showed the following order of abundance: quartz > epidote > chlorite > muscovite > calcite > hematite within the tailings profiles. The neutralization of the dominant alumino-silicate minerals and the absence of sulfidic minerals, have produced medium alkaline pH conditions (7.97–8.37 at all depths and low concentrations of dissolved Cu (20.21–47.9 µg/L, Zn (0.88–1.80 µg/L, Pb (0.27–0.34 µg/L, and SO42− (15.71–55.94 mg/L in the tailings profile leachates. The relative percentage leach for the potentially toxic chemical species was low in the aqueous phase (Ni 0.081%, Cu 0.006%, and Zn 0.05%. This indicates that the transport load of potentially toxic chemical species from tailings to the aqueous phase is very low. The precipitation of secondary hematite has an important known ability to trap and attenuate the mobility of potentially toxic chemical species (Cu, Zn, and Pb by adsorption on the surface area. Geochemical modelling MINTEQA2 showed that the tailings leachates were below saturation regarding oxyhydroxide minerals, but oversaturated with Cu

Parity doubling structure of nucleon at non-zero density in the holographic mean field theory

Directory of Open Access Journals (Sweden)

He Bing-Ran

2014-06-01

Full Text Available We summarize our recent work in which we develope the holographic mean field approach to study the dense baryonic matter in a bottom-up holographic QCD model including baryons and scalar mesons in addition to vector mesons. We first show that, at zero density, the rate of the chiral invariant mass of nucleon is controlled by the ratio of the infrared boundary values of two baryon fields included in the model. Then, at non-zero density, we find that the chiral condensate decreases with the increasing density indicating the partial restoration of the chiral symmetry. Our result shows that the more amount of the proton mass comes from the chiral symmetry breaking, the faster the effective nucleon mass decrease with density.

Note on the chemical potential of decoupled matter in the Universe

NARCIS (Netherlands)

Nieuwenhuizen, T.M.; Pombo, C.

2011-01-01

Textbooks on cosmology exhibit a thermodynamic inconsistency for free streaming, decoupled matter. It is connected here to the chemical potential, which deviates from its equilibrium value μ = @kBT , where @ is the usual parameter of the Fermi-Dirac or Bose-Einstein distribution function.

The chiral phase transition for two-flavour QCD at imaginary and zero chemical potential

CERN Document Server

Bonati, Claudio; de Forcrand, Philippe; Philipsen, Owe; Sanfillippo, Francesco

2013-01-01

The chiral symmetry of QCD with two massless quark flavours gets restored in a non-analytic chiral phase transition at finite temperature and zero density. Whether this is a first-order or a second-order transition has not yet been determined unambiguously, due to the difficulties of simulating light quarks. We investigate the nature of the chiral transition as a function of quark mass and imaginary chemical potential, using staggered fermions on N_t=4 lattices. At sufficiently large imaginary chemical potential, a clear signal for a first-order transition is obtained for small masses, which weakens with decreasing imaginary chemical potential. The second-order critical line m_c(mu_i), which marks the boundary between first-order and crossover behaviour, extrapolates to a finite m_c(mu_i=0) with known critical exponents. This implies a definitely first-order transition in the chiral limit on relatively coarse, N_t=4 lattices.

Potential of Biofilters for Treatment of De-Icing Chemicals

OpenAIRE

Raspati, Gema Sakti; Lindseth, Hanna Kristine; Muthanna, Tone Merete; Azrague, Kamal

2018-01-01

Organic de-icing chemicals, such as propylene glycol and potassium formate, cause environmental degradation in receiving water if left untreated, due to the high organic load resulting in oxygen depletion. Biofilters are commonly used for the treatment of biodegradable organic carbon in water treatment. This study investigated the potential for using biofilters for treating organic de-icing compounds. Lab-scale adsorption tests using filter media made of crushed clay (Filtralite) and granular...

Urinary screening for potentially genotoxic exposures in a chemical industry

Energy Technology Data Exchange (ETDEWEB)

Ahlborg, G. Jr.; Bergstroem, B.H.; Hogstedt, C.; Einistoe, P.S.; Sorsa, M.

1985-10-01

Mutagenic activity, measured by the bacterial fluctuation assay and thioether concentration in urine from workers at a chemical plant producing pharmaceuticals and explosives, was determined before and after exposure. Of 12 groups only those exposed to trinitrotoluene (n = 14) showed a significant increase in mutagenic activity using Salmonella typhimurium TA 98 without any exogenous metabolic system. The same strain responded only weakly when the S-9 mix was used; with Escherichia coli WP2 uvrA no effect of exposure was observed. Urinary thioether concentration was higher among smokers than among non-smokers, but occupational exposure had no effect. Urinary mutagenicity testing may be a useful tool for screening potentially genotoxic exposures in complex chemical environments.

Chemical diversity of microbial volatiles and their potential for plant growth and productivity

Directory of Open Access Journals (Sweden)

CHIDANANDA NAGAMANGALA KANCHISWAMY

2015-03-01

Full Text Available Microbial volatile organic compounds (MVOCs are produced by a wide array of microorganisms ranging from bacteria to fungi. A growing body of evidence indicates that MVOCs are ecofriendly and can be exploited as a cost-effective sustainable strategy for use in agricultural practice as agents that enhance plant growth, productivity and disease resistance. As naturally occurring chemicals, MVOCs have potential as possible alternatives to harmful pesticides, fungicides and bactericides as well as genetic modification. Recent studies performed under open field conditions demonstrate that efficiently adopting MVOCs may contribute to sustainable crop protection and production. We review here the chemical diversity of MVOCs and their potential physiological effects on crops and analyze potential and actual limitations for MVOC use as a sustainable strategy for improving productivity and reducing pesticide use.

Chemical production from waste carbon monoxide: its potential for energy conservation

Energy Technology Data Exchange (ETDEWEB)

Rohrmann, C.A.; Schiefelbein, G.F.; Molton, P.M.; Li, C.T.; Elliott, D.C.; Baker, E.G.

1977-11-01

Results of a study of the potential for energy conservation by producing chemicals from by-product or waste carbon monoxide (CO) from industrial sources are summarized. Extensive compilations of both industrial sources and uses for carbon monoxide were developed and included. Reviews of carbon monoxide purification and concentration technology and preliminary economic evaluations of carbon monoxide concentration, pipeline transportation and utilization of CO in the synthesis of ammonia and methanol are included. Preliminary technical and economic feasibility studies were made of producing ammonia and methanol from the by-product CO produced by a typical elemental phosphorus plant. Methanol synthesis appears to be more attractive than ammonia synthesis when using CO feedstock because of reduced water gas shift and carbon dioxide removal requirements. The economic studies indicate that methanol synthesis from CO appears to be competitive with conventional technology when the price of natural gas exceeds $0.82/million Btu, while ammonia synthesis from CO is probably not competitive until the price of natural gas exceeds $1.90/million Btu. It is concluded that there appears to be considerable potential for energy conservation in the chemical industry, by collecting CO rather than flaring it, and using it to make major chemicals such as ammonia and methanol.

In silico prediction of potential chemical reactions mediated by human enzymes.

Science.gov (United States)

Yu, Myeong-Sang; Lee, Hyang-Mi; Park, Aaron; Park, Chungoo; Ceong, Hyithaek; Rhee, Ki-Hyeong; Na, Dokyun

2018-06-13

Administered drugs are often converted into an ineffective or activated form by enzymes in our body. Conventional in silico prediction approaches focused on therapeutically important enzymes such as CYP450. However, there are more than thousands of different cellular enzymes that potentially convert administered drug into other forms. We developed an in silico model to predict which of human enzymes including metabolic enzymes as well as CYP450 family can catalyze a given chemical compound. The prediction is based on the chemical and physical similarity between known enzyme substrates and a query chemical compound. Our in silico model was developed using multiple linear regression and the model showed high performance (AUC = 0.896) despite of the large number of enzymes. When evaluated on a test dataset, it also showed significantly high performance (AUC = 0.746). Interestingly, evaluation with literature data showed that our model can be used to predict not only enzymatic reactions but also drug conversion and enzyme inhibition. Our model was able to predict enzymatic reactions of a query molecule with a high accuracy. This may foster to discover new metabolic routes and to accelerate the computational development of drug candidates by enabling the prediction of the potential conversion of administered drugs into active or inactive forms.

The overlapping distribution method to compute chemical potentials of chain molecules

NARCIS (Netherlands)

Mooij, G.C.A.M.; Frenkel, D.

1994-01-01

The chemical potential of continuously deformable chain molecules can be estimated by measuring the average Rosenbluth weight associated with the virtual insertion of a molecule. We show how to generalize the overlapping-distribution method of Bennett to histograms of Rosenbluth weights. In this way

Potential exposure to endocrine disrupting chemicals and selected adverse pregnancy outcomes

DEFF Research Database (Denmark)

Bengtsson, Jessica; Thygesen, Pernille Søgaard; Kaerlev, Linda

2017-01-01

potential occupational exposure to endocrine disrupting chemicals (EDC) of the mother during pregnancy is associated with preterm birth and low birth weight. Methods: Pregnant women referred to an Occupational Health Clinic (OHC) in two Danish regions (Copenhagen or Aarhus) between 1984 and 2010, suspected...

Potential Applications of Peroxidases in the Fine Chemical Industries

Science.gov (United States)

Casella, Luigi; Monzani, Enrico; Nicolis, Stefania

A description of selected types of reactions catalyzed by heme peroxidases is given. In particular, the discussion is focused mainly on those of potential interest for fine chemical synthesis. The division into subsections has been done fromthe point of view of the enzyme action, i.e., giving emphasis to themechanismof the enzymatic reaction, and from that of the substrate, i.e., analyzing the type of transformation promoted by the enzyme. These two approaches have several points in common.

Effect of finite chemical potential on QGP-hadron phase transition in a statistical model of fireball formation

International Nuclear Information System (INIS)

Ramanathan, R.; Singh, S.S.; Jha, A.K.; Gupta, K.K.

2011-01-01

We study the effect of finite chemical potential for the QGP constituents in the Ramanathan et al. statistical model. While the earlier computations using this model with vanishing chemical potentials indicated a weakly first order phase transition for the system in the vicinity of 170 MeV, the introduction of finite values for the chemical potentials of the constituents makes the transition a smooth roll over of the phases, while allowing fireball formation with radius of a few 'fermi' to take place. This seems to be in conformity with the latest consensus on the nature of the QGP-Hadron phase transition. (author)

On finitely generated modules whose first nonzero Fitting ideals are regular

Directory of Open Access Journals (Sweden)

Somayeh Hadjirezaei

2018-01-01

Full Text Available A finitely generated $R$-module is said to be a module of type ($F_r$ if its $(r-1$-th Fitting ideal is the zero ideal and its $r$-th Fitting ideal is a regular ideal. Let $R$ be a commutative ring and $N$ be a submodule of  $R^n$ which is generated by columns of  a matrix $A=(a_{ij}$ with $a_{ij}in R$ for all $1leq ileq n$, $jin Lambda$, where $Lambda $ is a (possibly infinite index set.  Let  $M=R^n/N$ be  a module of type ($F_{n-1}$ and ${rm T}(M$ be the submodule of $M$ consisting of all elements of $M$ that are annihilated by a regular element of $R$. For $ lambdain Lambda $, put $M_lambda=R^n/$. The main result of this paper asserts that if $M_lambda $ is a regular $R$-module, for some $lambdainLambda$, then $M/{rm T}(Mcong M_lambda/{rm T}(M_lambda$. Also it is shown that if $M_lambda$ is a regular torsionfree $R$-module, for some $lambdain Lambda$, then $ Mcong M_lambda. $ As a consequence we characterize all  non-torsionfree modules over a regular ring, whose first nonzero Fitting ideals are maximal.

Investigation of the potential influence of production treatment chemicals on produced water toxicity

International Nuclear Information System (INIS)

Stine, E.R.; Gala, W.R.; Henry, L.R.

1993-01-01

Production treatment chemicals represent a diverse collection of chemical classes, added at various points from the wellhead to the final flotation cell, to prevent operational upsets and enhance the separation of oil from water. Information in the literature indicates that while many treatment chemicals are thought to partition into oil and not into the produced water, there are cases where a sufficiently water soluble treatment chemical is added at high enough concentrations to suggest that the treatment chemical may add to the aquatic toxicity of the produced water. A study was conducted to evaluate the potential effect of production treatment chemicals on the toxicity of produced waters using the US EPA Seven-day Mysidopsis bahia Survival, Growth and Fecundity Test. Samples of produced water were collected and tested for toxicity from three platforms under normal operating conditions, followed by repeated sampling and testing after a 72-hour period in which treatment chemical usage was discontinued, to the degree possible. Significant reductions in produced water toxicity were observed for two of the three platforms tested following either cessation of treatment chemical usage, or by comparing the toxicity of samples collected upstream and downstream of the point of treatment chemical addition

Antioxidants as potential medical countermeasures for chemical warfare agents and toxic industrial chemicals.

Science.gov (United States)

McElroy, Cameron S; Day, Brian J

2016-01-15

The continuing horrors of military conflicts and terrorism often involve the use of chemical warfare agents (CWAs) and toxic industrial chemicals (TICs). Many CWA and TIC exposures are difficult to treat due to the danger they pose to first responders and their rapid onset that can produce death shortly after exposure. While the specific mechanism(s) of toxicity of these agents are diverse, many are associated either directly or indirectly with increased oxidative stress in affected tissues. This has led to the exploration of various antioxidants as potential medical countermeasures for CWA/TIC exposures. Studies have been performed across a wide array of agents, model organisms, exposure systems, and antioxidants, looking at an almost equally diverse set of endpoints. Attempts at treating CWAs/TICs with antioxidants have met with mixed results, ranging from no effect to nearly complete protection. The aim of this commentary is to summarize the literature in each category for evidence of oxidative stress and antioxidant efficacy against CWAs and TICs. While there is great disparity in the data concerning methods, models, and remedies, the outlook on antioxidants as medical countermeasures for CWA/TIC management appears promising. Copyright © 2015 Elsevier Inc. All rights reserved.

Chemical mixtures in untreated water from public-supply wells in the U.S. - Occurrence, composition, and potential toxicity

Energy Technology Data Exchange (ETDEWEB)

Toccalino, Patricia L., E-mail: ptocca@usgs.gov [U.S. Geological Survey (USGS), 6000 J Street, Placer Hall, Sacramento, California 95819 (United States); Norman, Julia E., E-mail: jnorman@usgs.gov [USGS, 2130 SW 5th Avenue, Portland, Oregon 97201 (United States); Scott, Jonathon C., E-mail: jon@usgs.gov [USGS, 202 NW 66th Street, Oklahoma City, Oklahoma 73116 (United States)

2012-08-01

Chemical mixtures are prevalent in groundwater used for public water supply, but little is known about their potential health effects. As part of a large-scale ambient groundwater study, we evaluated chemical mixtures across multiple chemical classes, and included more chemical contaminants than in previous studies of mixtures in public-supply wells. We (1) assessed the occurrence of chemical mixtures in untreated source-water samples from public-supply wells, (2) determined the composition of the most frequently occurring mixtures, and (3) characterized the potential toxicity of mixtures using a new screening approach. The U.S. Geological Survey collected one untreated water sample from each of 383 public wells distributed across 35 states, and analyzed the samples for as many as 91 chemical contaminants. Concentrations of mixture components were compared to individual human-health benchmarks; the potential toxicity of mixtures was characterized by addition of benchmark-normalized component concentrations. Most samples (84%) contained mixtures of two or more contaminants, each at concentrations greater than one-tenth of individual benchmarks. The chemical mixtures that most frequently occurred and had the greatest potential toxicity primarily were composed of trace elements (including arsenic, strontium, or uranium), radon, or nitrate. Herbicides, disinfection by-products, and solvents were the most common organic contaminants in mixtures. The sum of benchmark-normalized concentrations was greater than 1 for 58% of samples, suggesting that there could be potential for mixtures toxicity in more than half of the public-well samples. Our findings can be used to help set priorities for groundwater monitoring and suggest future research directions for drinking-water treatment studies and for toxicity assessments of chemical mixtures in water resources. - Highlights: Black-Right-Pointing-Pointer We assessed mixtures in untreated groundwater samples from public

Directed transport by surface chemical potential gradients for enhancing analyte collection in nanoscale sensors.

Science.gov (United States)

Sitt, Amit; Hess, Henry

2015-05-13

Nanoscale detectors hold great promise for single molecule detection and the analysis of small volumes of dilute samples. However, the probability of an analyte reaching the nanosensor in a dilute solution is extremely low due to the sensor's small size. Here, we examine the use of a chemical potential gradient along a surface to accelerate analyte capture by nanoscale sensors. Utilizing a simple model for transport induced by surface binding energy gradients, we study the effect of the gradient on the efficiency of collecting nanoparticles and single and double stranded DNA. The results indicate that chemical potential gradients along a surface can lead to an acceleration of analyte capture by several orders of magnitude compared to direct collection from the solution. The improvement in collection is limited to a relatively narrow window of gradient slopes, and its extent strongly depends on the size of the gradient patch. Our model allows the optimization of gradient layouts and sheds light on the fundamental characteristics of chemical potential gradient induced transport.

Temperature and baryon-chemical-potential-dependent bag pressure for a deconfining phase transition

International Nuclear Information System (INIS)

Patra, B.K.; Singh, C.P.

1996-01-01

We explore the consequences of a bag model developed by Leonidov et al. for the deconfining phase transition in which the bag pressure is made to depend on the temperature and baryon chemical potential in order to ensure the entropy and baryon number conservation at the phase boundary together with the Gibbs construction for an equilibrium phase transition. We show that the bag pressure thus obtained yields an anomalous increasing behavior with the increasing baryon chemical potential at a fixed temperature which defies a physical interpretation. We demonstrate that the inclusion of the perturbative interactions in the QGP phase removes this difficulty. Further consequences of the modified bag pressure are discussed. copyright 1996 The American Physical Society

Comparison of modeling approaches to prioritize chemicals based on estimates of exposure and exposure potential.

Science.gov (United States)

Mitchell, Jade; Arnot, Jon A; Jolliet, Olivier; Georgopoulos, Panos G; Isukapalli, Sastry; Dasgupta, Surajit; Pandian, Muhilan; Wambaugh, John; Egeghy, Peter; Cohen Hubal, Elaine A; Vallero, Daniel A

2013-08-01

While only limited data are available to characterize the potential toxicity of over 8 million commercially available chemical substances, there is even less information available on the exposure and use-scenarios that are required to link potential toxicity to human and ecological health outcomes. Recent improvements and advances such as high throughput data gathering, high performance computational capabilities, and predictive chemical inherency methodology make this an opportune time to develop an exposure-based prioritization approach that can systematically utilize and link the asymmetrical bodies of knowledge for hazard and exposure. In response to the US EPA's need to develop novel approaches and tools for rapidly prioritizing chemicals, a "Challenge" was issued to several exposure model developers to aid the understanding of current systems in a broader sense and to assist the US EPA's effort to develop an approach comparable to other international efforts. A common set of chemicals were prioritized under each current approach. The results are presented herein along with a comparative analysis of the rankings of the chemicals based on metrics of exposure potential or actual exposure estimates. The analysis illustrates the similarities and differences across the domains of information incorporated in each modeling approach. The overall findings indicate a need to reconcile exposures from diffuse, indirect sources (far-field) with exposures from directly, applied chemicals in consumer products or resulting from the presence of a chemical in a microenvironment like a home or vehicle. Additionally, the exposure scenario, including the mode of entry into the environment (i.e. through air, water or sediment) appears to be an important determinant of the level of agreement between modeling approaches. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparison of modeling approaches to prioritize chemicals based on estimates of exposure and exposure potential

Science.gov (United States)

Mitchell, Jade; Arnot, Jon A.; Jolliet, Olivier; Georgopoulos, Panos G.; Isukapalli, Sastry; Dasgupta, Surajit; Pandian, Muhilan; Wambaugh, John; Egeghy, Peter; Cohen Hubal, Elaine A.; Vallero, Daniel A.

2014-01-01

While only limited data are available to characterize the potential toxicity of over 8 million commercially available chemical substances, there is even less information available on the exposure and use-scenarios that are required to link potential toxicity to human and ecological health outcomes. Recent improvements and advances such as high throughput data gathering, high performance computational capabilities, and predictive chemical inherency methodology make this an opportune time to develop an exposure-based prioritization approach that can systematically utilize and link the asymmetrical bodies of knowledge for hazard and exposure. In response to the US EPA’s need to develop novel approaches and tools for rapidly prioritizing chemicals, a “Challenge” was issued to several exposure model developers to aid the understanding of current systems in a broader sense and to assist the US EPA’s effort to develop an approach comparable to other international efforts. A common set of chemicals were prioritized under each current approach. The results are presented herein along with a comparative analysis of the rankings of the chemicals based on metrics of exposure potential or actual exposure estimates. The analysis illustrates the similarities and differences across the domains of information incorporated in each modeling approach. The overall findings indicate a need to reconcile exposures from diffuse, indirect sources (far-field) with exposures from directly, applied chemicals in consumer products or resulting from the presence of a chemical in a microenvironment like a home or vehicle. Additionally, the exposure scenario, including the mode of entry into the environment (i.e. through air, water or sediment) appears to be an important determinant of the level of agreement between modeling approaches. PMID:23707726

Key study on the potential of hydrazine bisborane for solid- and liquid-state chemical hydrogen storage.

Science.gov (United States)

Pylypko, Sergii; Petit, Eddy; Yot, Pascal G; Salles, Fabrice; Cretin, Marc; Miele, Philippe; Demirci, Umit B

2015-05-04

Hydrazine bisborane N2H4(BH3)2 (HBB; 16.8 wt %) recently re-emerged as a potential hydrogen storage material. However, such potential is controversial: HBB was seen as a hazardous compound up to 2010, but now it would be suitable for hydrogen storage. In this context, we focused on fundamentals of HBB because they are missing in the literature and should help to shed light on its effective potential while taking into consideration any risk. Experimental/computational methods were used to get a complete characterization data sheet, including, e.g., XRD, NMR, FTIR, Raman, TGA, and DSC. From the reported results and discussion, it is concluded that HBB has potential in the field of chemical hydrogen storage given that both thermolytic and hydrolytic dehydrogenations were analyzed. In solid-state chemical hydrogen storage, it cannot be used in the pristine state (risk of explosion during dehydrogenation) but can be used for the synthesis of derivatives with improved dehydrogenation properties. In liquid-state chemical hydrogen storage, it can be studied for room-temperature dehydrogenation, but this requires the development of an active and selective metal-based catalyst. HBB is a thus a candidate for chemical hydrogen storage.

Lepidopteran defence droplets - A composite physical and chemical weapon against potential predators

DEFF Research Database (Denmark)

Pentzold, S.; Zagrobelny, Mika; Khakimov, Bekzod

2016-01-01

Insects often release noxious substances for their defence. Larvae of Zygaena filipendulae (Lepidoptera) secrete viscous and cyanogenic glucoside-containing droplets, whose effectiveness was associated with their physical and chemical properties. The droplets glued mandibles and legs of potential...

Chemical mixtures in untreated water from public-supply wells in the U.S. — Occurrence, composition, and potential toxicity

International Nuclear Information System (INIS)

Toccalino, Patricia L.; Norman, Julia E.; Scott, Jonathon C.

2012-01-01

Chemical mixtures are prevalent in groundwater used for public water supply, but little is known about their potential health effects. As part of a large-scale ambient groundwater study, we evaluated chemical mixtures across multiple chemical classes, and included more chemical contaminants than in previous studies of mixtures in public-supply wells. We (1) assessed the occurrence of chemical mixtures in untreated source-water samples from public-supply wells, (2) determined the composition of the most frequently occurring mixtures, and (3) characterized the potential toxicity of mixtures using a new screening approach. The U.S. Geological Survey collected one untreated water sample from each of 383 public wells distributed across 35 states, and analyzed the samples for as many as 91 chemical contaminants. Concentrations of mixture components were compared to individual human-health benchmarks; the potential toxicity of mixtures was characterized by addition of benchmark-normalized component concentrations. Most samples (84%) contained mixtures of two or more contaminants, each at concentrations greater than one-tenth of individual benchmarks. The chemical mixtures that most frequently occurred and had the greatest potential toxicity primarily were composed of trace elements (including arsenic, strontium, or uranium), radon, or nitrate. Herbicides, disinfection by-products, and solvents were the most common organic contaminants in mixtures. The sum of benchmark-normalized concentrations was greater than 1 for 58% of samples, suggesting that there could be potential for mixtures toxicity in more than half of the public-well samples. Our findings can be used to help set priorities for groundwater monitoring and suggest future research directions for drinking-water treatment studies and for toxicity assessments of chemical mixtures in water resources. - Highlights: ► We assessed mixtures in untreated groundwater samples from public-supply wells. ► A screening

Chemical mixtures in untreated water from public-supply wells in the U.S.--occurrence, composition, and potential toxicity.

Science.gov (United States)

Toccalino, Patricia L; Norman, Julia E; Scott, Jonathon C

2012-08-01

Chemical mixtures are prevalent in groundwater used for public water supply, but little is known about their potential health effects. As part of a large-scale ambient groundwater study, we evaluated chemical mixtures across multiple chemical classes, and included more chemical contaminants than in previous studies of mixtures in public-supply wells. We (1) assessed the occurrence of chemical mixtures in untreated source-water samples from public-supply wells, (2) determined the composition of the most frequently occurring mixtures, and (3) characterized the potential toxicity of mixtures using a new screening approach. The U.S. Geological Survey collected one untreated water sample from each of 383 public wells distributed across 35 states, and analyzed the samples for as many as 91 chemical contaminants. Concentrations of mixture components were compared to individual human-health benchmarks; the potential toxicity of mixtures was characterized by addition of benchmark-normalized component concentrations. Most samples (84%) contained mixtures of two or more contaminants, each at concentrations greater than one-tenth of individual benchmarks. The chemical mixtures that most frequently occurred and had the greatest potential toxicity primarily were composed of trace elements (including arsenic, strontium, or uranium), radon, or nitrate. Herbicides, disinfection by-products, and solvents were the most common organic contaminants in mixtures. The sum of benchmark-normalized concentrations was greater than 1 for 58% of samples, suggesting that there could be potential for mixtures toxicity in more than half of the public-well samples. Our findings can be used to help set priorities for groundwater monitoring and suggest future research directions for drinking-water treatment studies and for toxicity assessments of chemical mixtures in water resources. Published by Elsevier B.V.

Combined effects of changing-sign potential and critical nonlinearities in Kirchhoff type problems

Directory of Open Access Journals (Sweden)

Gao-Sheng Liu

2016-08-01

Full Text Available In this article, we study the existence and multiplicity of positive solutions for a class of Kirchhoff type problems involving changing-sign potential and critical growth terms. Using the concentration compactness principle and Nehari manifold, we obtain the existence and multiplicity of nonzero non-negative solutions.

Approximate N-Player Nonzero-Sum Game Solution for an Uncertain Continuous Nonlinear System.

Science.gov (United States)

Johnson, Marcus; Kamalapurkar, Rushikesh; Bhasin, Shubhendu; Dixon, Warren E

2015-08-01

An approximate online equilibrium solution is developed for an N -player nonzero-sum game subject to continuous-time nonlinear unknown dynamics and an infinite horizon quadratic cost. A novel actor-critic-identifier structure is used, wherein a robust dynamic neural network is used to asymptotically identify the uncertain system with additive disturbances, and a set of critic and actor NNs are used to approximate the value functions and equilibrium policies, respectively. The weight update laws for the actor neural networks (NNs) are generated using a gradient-descent method, and the critic NNs are generated by least square regression, which are both based on the modified Bellman error that is independent of the system dynamics. A Lyapunov-based stability analysis shows that uniformly ultimately bounded tracking is achieved, and a convergence analysis demonstrates that the approximate control policies converge to a neighborhood of the optimal solutions. The actor, critic, and identifier structures are implemented in real time continuously and simultaneously. Simulations on two and three player games illustrate the performance of the developed method.

Chemicals - potential substances for WMD creation, explosives and rocket fuel

International Nuclear Information System (INIS)

Vorozhtsova, M.D.; Khakimova, N.U.; Barotov, M.A.

2010-01-01

fluoropolymer (teflon) production, in metallurgy, during glass reprocessing and others. Chlorine trifluoride - ClF_3 - has wide range. It is applied for nuclear materials conversion, rocket fuel additive as well as for semiconductors production in military field. ClF_3 is colorless gas and has sweetish smell, toxic and strong oxidizer. In this article just some chemicals of CHW production are presented. Chemicals are also potential components of strong explosives. Explosives are known as: cyclonite, octogen, triamino trinitrobenzol, solid oxidant (for example, ammonium perchlorate) and others. Chemicals are widely used in rocket fuel production: combustible chemicals; solid and liquid oxidants; binding polymers; other additives. Solid fuel - admixture of many chemicals and connecting components and usually consist from oxidant and de oxidizer. Liquid fuel - also admixture of different liquid chemicals. Usually for rocket fuel NH_4ClO_4 is widely used, hydrazine, hydrides monomethyl, aluminium powder, AlH_3, nitrogen oxide, nitric acids. Some words about heavy water - D_2O, which is moderator in nuclear reactors, ensures continuous nuclear chain reaction with use of natural uranium. D_2O - colorless liquid, external view doesn't differ from H_2O and not radioactive. Its density is 10% more than H_2O. Thus, in this article the chemical substances are presented which are used for WMD, explosives and rocket fuel production. That's why control and exact identification of these substances is guarantee of weapons of mass destruction (WMD) non-proliferation.

Inverse scattering transform and soliton solutions for square matrix nonlinear Schrödinger equations with non-zero boundary conditions

Science.gov (United States)

Prinari, Barbara; Demontis, Francesco; Li, Sitai; Horikis, Theodoros P.

2018-04-01

The inverse scattering transform (IST) with non-zero boundary conditions at infinity is developed for an m × m matrix nonlinear Schrödinger-type equation which, in the case m = 2, has been proposed as a model to describe hyperfine spin F = 1 spinor Bose-Einstein condensates with either repulsive interatomic interactions and anti-ferromagnetic spin-exchange interactions (self-defocusing case), or attractive interatomic interactions and ferromagnetic spin-exchange interactions (self-focusing case). The IST for this system was first presented by Ieda et al. (2007) , using a different approach. In our formulation, both the direct and the inverse problems are posed in terms of a suitable uniformization variable which allows to develop the IST on the standard complex plane, instead of a two-sheeted Riemann surface or the cut plane with discontinuities along the cuts. Analyticity of the scattering eigenfunctions and scattering data, symmetries, properties of the discrete spectrum, and asymptotics are derived. The inverse problem is posed as a Riemann-Hilbert problem for the eigenfunctions, and the reconstruction formula of the potential in terms of eigenfunctions and scattering data is provided. In addition, the general behavior of the soliton solutions is analyzed in detail in the 2 × 2 self-focusing case, including some special solutions not previously discussed in the literature.

Chemical potential of quasi-equilibrium magnon gas driven by pure spin current.

Science.gov (United States)

Demidov, V E; Urazhdin, S; Divinskiy, B; Bessonov, V D; Rinkevich, A B; Ustinov, V V; Demokritov, S O

2017-11-17

Pure spin currents provide the possibility to control the magnetization state of conducting and insulating magnetic materials. They allow one to increase or reduce the density of magnons, and achieve coherent dynamic states of magnetization reminiscent of the Bose-Einstein condensation. However, until now there was no direct evidence that the state of the magnon gas subjected to spin current can be treated thermodynamically. Here, we show experimentally that the spin current generated by the spin-Hall effect drives the magnon gas into a quasi-equilibrium state that can be described by the Bose-Einstein statistics. The magnon population function is characterized either by an increased effective chemical potential or by a reduced effective temperature, depending on the spin current polarization. In the former case, the chemical potential can closely approach, at large driving currents, the lowest-energy magnon state, indicating the possibility of spin current-driven Bose-Einstein condensation.

Should tsunami simulations include a nonzero initial horizontal velocity?

Science.gov (United States)

Lotto, Gabriel C.; Nava, Gabriel; Dunham, Eric M.

2017-08-01

Tsunami propagation in the open ocean is most commonly modeled by solving the shallow water wave equations. These equations require initial conditions on sea surface height and depth-averaged horizontal particle velocity or, equivalently, horizontal momentum. While most modelers assume that initial velocity is zero, Y.T. Song and collaborators have argued for nonzero initial velocity, claiming that horizontal displacement of a sloping seafloor imparts significant horizontal momentum to the ocean. They show examples in which this effect increases the resulting tsunami height by a factor of two or more relative to models in which initial velocity is zero. We test this claim with a "full-physics" integrated dynamic rupture and tsunami model that couples the elastic response of the Earth to the linearized acoustic-gravitational response of a compressible ocean with gravity; the model self-consistently accounts for seismic waves in the solid Earth, acoustic waves in the ocean, and tsunamis (with dispersion at short wavelengths). Full-physics simulations of subduction zone megathrust ruptures and tsunamis in geometries with a sloping seafloor confirm that substantial horizontal momentum is imparted to the ocean. However, almost all of that initial momentum is carried away by ocean acoustic waves, with negligible momentum imparted to the tsunami. We also compare tsunami propagation in each simulation to that predicted by an equivalent shallow water wave simulation with varying assumptions regarding initial velocity. We find that the initial horizontal velocity conditions proposed by Song and collaborators consistently overestimate the tsunami amplitude and predict an inconsistent wave profile. Finally, we determine tsunami initial conditions that are rigorously consistent with our full-physics simulations by isolating the tsunami waves from ocean acoustic and seismic waves at some final time, and backpropagating the tsunami waves to their initial state by solving the

Performance of heat engines with non-zero heat capacity

International Nuclear Information System (INIS)

Odes, Ron; Kribus, Abraham

2013-01-01

Highlights: ► Finite heat capacity is a second irreversibility mechanism in addition to thermal resistance. ► Heat capacity introduces thermal transients and reverse heat flow. ► Engine maximum power and efficiency are lower for finite heat capacity. ► Implementing the optimal engine cycle requires active control. - Abstract: The performance of a heat engine is analyzed subject to two types of irreversibility: a non-zero heat capacity, together with the more common finite heat transfer rate between the engine and the external heat reservoirs. The heat capacity represents an engine body that undergoes significant temperature variations during the engine cycle. An option to cut off the heat exchange between the engine and the external surrounding for part of the engine cycle is also explored. A variational approach was taken to find the engine’s internal temperature profile (which defines the internal thermodynamic cycle) that would produce maximum power. The maximum power is shown to be lower than the case of zero heat capacity, due to a loss of heat that is stored in the engine body and then lost, bypassing the thermodynamic cycle. The maximum efficiency and the efficiency at maximum power are also lower than the zero heat capacity case. Similar to the Curzon–Ahlborn analysis, power can be traded for increased efficiency, but for high heat capacity, the range of efficiency that is available for such a trade is diminished. Isolating the engine during part of the cycle reduces maximum power, but the efficiency at maximum power and the maximum efficiency are improved, due to better exploitation of heat stored in the engine body. This might be useful for real engines that are limited by the internal energy change during a single engine cycle or by the operating frequency, leading to a broader power–efficiency curve.

Chiral phase transition at finite chemical potential in 2 +1 -flavor soft-wall anti-de Sitter space QCD

Science.gov (United States)

Bartz, Sean P.; Jacobson, Theodore

2018-04-01

The phase transition from hadronic matter to chirally symmetric quark-gluon plasma is expected to be a rapid crossover at zero quark chemical potential (μ ), becoming first order at some finite value of μ , indicating the presence of a critical point. Using a three-flavor soft-wall model of anti-de Sitter/QCD, we investigate the effect of varying the light and strange quark masses on the order of the chiral phase transition. At zero quark chemical potential, we reproduce the Columbia Plot, which summarizes the results of lattice QCD and other holographic models. We then extend this holographic model to examine the effects of finite quark chemical potential. We find that the the chemical potential does not affect the critical line that separates first-order from rapid crossover transitions. This excludes the possibility of a critical point in this model, suggesting that a different setup is necessary to reproduce all the features of the QCD phase diagram.

Random matrix analysis of the QCD sign problem for general topology

International Nuclear Information System (INIS)

Bloch, Jacques; Wettig, Tilo

2009-01-01

Motivated by the important role played by the phase of the fermion determinant in the investigation of the sign problem in lattice QCD at nonzero baryon density, we derive an analytical formula for the average phase factor of the fermion determinant for general topology in the microscopic limit of chiral random matrix theory at nonzero chemical potential, for both the quenched and the unquenched case. The formula is a nontrivial extension of the expression for zero topology derived earlier by Splittorff and Verbaarschot. Our analytical predictions are verified by detailed numerical random matrix simulations of the quenched theory.

The chiral phase transition in two-flavor QCD from imaginary chemical potential

CERN Document Server

Bonati, Claudio; D'Elia, Massimo; Philipsen, Owe; Sanfilippo, Francesco

2014-01-01

We investigate the order of the finite temperature chiral symmetry restoration transition for QCD with two massless fermions, by using a novel method, based on simulating imaginary values of the quark chemical potential $\\mu=i\\mu_i,\\mu_i\\in\\mathbb{R}$. Our method exploits the fact that, for low enough quark mass $m$ and large enough chemical potential $\\mu_i$, the chiral transition is decidedly first order, then turning into crossover at a critical mass $m_c(\\mu)$. It is thus possible to determine the critical line in the $m - \\mu^2$ plane, which can be safely extrapolated to the chiral limit by taking advantage of the known tricritical indices governing its shape. We test this method with standard staggered fermions and the result of our simulations is that $m_c(\\mu=0)$ is positive, so that the phase transition at zero density is definitely first order in the chiral limit, on our coarse $N_t=4$ lattices with $a\\simeq 0.3\\,\\mathrm{fm}$.

Mathematical model for the contribution of individual organs to non-zero y-intercepts in single and multi-compartment linear models of whole-body energy expenditure.

Science.gov (United States)

Kaiyala, Karl J

2014-01-01

Mathematical models for the dependence of energy expenditure (EE) on body mass and composition are essential tools in metabolic phenotyping. EE scales over broad ranges of body mass as a non-linear allometric function. When considered within restricted ranges of body mass, however, allometric EE curves exhibit 'local linearity.' Indeed, modern EE analysis makes extensive use of linear models. Such models typically involve one or two body mass compartments (e.g., fat free mass and fat mass). Importantly, linear EE models typically involve a non-zero (usually positive) y-intercept term of uncertain origin, a recurring theme in discussions of EE analysis and a source of confounding in traditional ratio-based EE normalization. Emerging linear model approaches quantify whole-body resting EE (REE) in terms of individual organ masses (e.g., liver, kidneys, heart, brain). Proponents of individual organ REE modeling hypothesize that multi-organ linear models may eliminate non-zero y-intercepts. This could have advantages in adjusting REE for body mass and composition. Studies reveal that individual organ REE is an allometric function of total body mass. I exploit first-order Taylor linearization of individual organ REEs to model the manner in which individual organs contribute to whole-body REE and to the non-zero y-intercept in linear REE models. The model predicts that REE analysis at the individual organ-tissue level will not eliminate intercept terms. I demonstrate that the parameters of a linear EE equation can be transformed into the parameters of the underlying 'latent' allometric equation. This permits estimates of the allometric scaling of EE in a diverse variety of physiological states that are not represented in the allometric EE literature but are well represented by published linear EE analyses.

Organization A Comprehensive System Of Insurance Coverage In The Potential Chemical And Biological Contamination Zone In Regions

Directory of Open Access Journals (Sweden)

Nina Vladimirovna Zaytseva

2014-12-01

Full Text Available The article provides a scientific rationale for an integrated approach to the provision of insurance coverage in the potential chemical and biological contamination zone. The following modern forms of chemical safety in the Russian Federation were considered: state reserve’s system, target program financing, state social insurance. The separate issue tackles the obligatory civil liability insurance for owners of dangerous objects. For improvement of the existing insurance protection system against emergency situations, risks were analyzed (shared on exogenous and endogenous. Among the exogenous risks including natural and climatic conditions of a region, its geographical arrangement, economic specialization, the seismic and terrorist risks were chosen and approaches to its solution were suggested. In endogenous risks’ group, the special focus is on wear and tear and obsolescence of hazardous chemical and biological object’s fixed assets. In case of high risk of an incident, it is suggested to increase in extent of insurance protection through self-insurance, a mutual insurance in the form of the organization of societies of a mutual insurance or the self-regulating organizations, and also development of voluntary insurance of a civil liability, both the owner of hazardous object, and regions of the Russian Federation and municipalities. The model of insurance coverage in the potential chemical and biological contamination zone is based on a differentiated approach to the danger level of the area. A matrix of adequate forms and types of insurance (required for insurance coverage of the population in the potential chemical and biological contamination zone was constructed. Proposed health risk management toolkit in the potential chemical and biological contamination zone will allow to use financial resources for chemical and biological safety in the regions more efficiently.

Density induced phase transitions in the Schwinger model. A study with matrix product states

Energy Technology Data Exchange (ETDEWEB)

Banuls, Mari Carmen; Cirac, J. Ignacio; Kuehn, Stefan [Max-Planck-Institut fuer Quantenoptik (MPQ), Garching (Germany); Cichy, Krzysztof [Frankfurt Univ. (Germany). Inst. fuer Theoretische Physik; Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

2017-02-15

We numerically study the zero temperature phase structure of the multiflavor Schwinger model at nonzero chemical potential. Using matrix product states, we reproduce analytical results for the phase structure for two flavors in the massless case and extend the computation to the massive case, where no analytical predictions are available. Our calculations allow us to locate phase transitions in the mass-chemical potential plane with great precision and provide a concrete example of tensor networks overcoming the sign problem in a lattice gauge theory calculation.

Simulation of uranium transport with variable temperature and oxidation potential: The computer program THCC [Thermo-Hydro-Chemical Coupling

International Nuclear Information System (INIS)

Carnahan, C.L.

1986-12-01

A simulator of reactive chemical transport has been constructed with the capabilities of treating variable temperatures and variable oxidation potentials within a single simulation. Homogeneous and heterogeneous chemical reactions are simulated at temperature-dependent equilibrium, and changes of oxidation states of multivalent elements can be simulated during transport. Chemical mass action relations for formation of complexes in the fluid phase are included explicitly within the partial differential equations of transport, and a special algorithm greatly simplifies treatment of reversible precipitation of solid phases. This approach allows direct solution of the complete set of governing equations for concentrations of all aqueous species and solids affected simultaneously by chemical and physical processes. Results of example simulations of transport, along a temperature gradient, of uranium solution species under conditions of varying pH and oxidation potential and with reversible precipitation of uraninite and coffinite are presented. The examples illustrate how inclusion of variable temperature and oxidation potential in numerical simulators can enhance understanding of the chemical mechanisms affecting migration of multivalent waste elements

Potential exposure to endocrine disrupting chemicals and selected adverse pregnancy outcomes

DEFF Research Database (Denmark)

Bengtsson, Jessica; Thygesen, Pernille Søgaard; Kaerlev, Linda

2017-01-01

potential occupational exposure to endocrine disrupting chemicals (EDC) of the mother during pregnancy is associated with preterm birth and low birth weight. Methods: Pregnant women referred to an Occupational Health Clinic (OHC) in two Danish regions (Copenhagen or Aarhus) between 1984 and 2010, suspected...... on the suspicion of other exposures than EDC (n = 620), and to a sample of births by all occupationally active women in the same geographical regions (n = 346,544), including 1,077 births of the referred women’s non-referred pregnancies. Results: No indications of reduced birth weight or increased risk of preterm...... birth were found among women potentially exposed to EDC. Women potentially exposed to EDC had children with a higher birth weight compared to the sample of occupationally active women but not compared to other women referred to an OHC. Conclusions: Potential maternal exposure to EDC at Danish workplaces...

On the thermal phase structure of QCD at vanishing chemical potentials

CERN Document Server

Kabana, S

2011-01-01

The hypothesis is investigated, that the thermal structure of QCD phases at and near zero chemical potentials is determined by long range coherence, inducing the gauge boson pair condensate. The latter reflects the dynamical nature of gauge boson Bogoliubov transformations at the origin of localization of all color fields inside hadrons at low temperature in contrast to loss of such localization above a unique critical temperature.

Properties of baryonic, electric and strangeness chemical potentials and some of their consequences in relativistic heavy ion collisions

Energy Technology Data Exchange (ETDEWEB)

Mekjian, Aram Z. [Rutgers University, Department of Physics and Astronomy, Piscataway, NJ 08854 (United States) and California Institute of Technology, Kellogg Radiation Laboratory 106-38, Pasadena, CA 91125 (United States)]. E-mail: mekjian@physics.rutgers.edu

2007-07-19

Analytic expressions are given for the baryonic, electric and strangeness chemical potentials which explicitly show the importance of various terms. Simple scaling relations connecting these chemical potentials are found. Applications to particle ratios and to fluctuations and related thermal properties such as the isothermal compressibility {kappa}{sub T} are illustrated. A possible divergence of {kappa}{sub T} is discussed.

Experience Replay for Optimal Control of Nonzero-Sum Game Systems With Unknown Dynamics.

Science.gov (United States)

Zhao, Dongbin; Zhang, Qichao; Wang, Ding; Zhu, Yuanheng

2016-03-01

In this paper, an approximate online equilibrium solution is developed for an N -player nonzero-sum (NZS) game systems with completely unknown dynamics. First, a model identifier based on a three-layer neural network (NN) is established to reconstruct the unknown NZS games systems. Moreover, the identifier weight vector is updated based on experience replay technique which can relax the traditional persistence of excitation condition to a simplified condition on recorded data. Then, the single-network adaptive dynamic programming (ADP) with experience replay algorithm is proposed for each player to solve the coupled nonlinear Hamilton- (HJ) equations, where only the critic NN weight vectors are required to tune for each player. The feedback Nash equilibrium is provided by the solution of the coupled HJ equations. Based on the experience replay technique, a novel critic NN weights tuning law is proposed to guarantee the stability of the closed-loop system and the convergence of the value functions. Furthermore, a Lyapunov-based stability analysis shows that the uniform ultimate boundedness of the closed-loop system is achieved. Finally, two simulation examples are given to verify the effectiveness of the proposed control scheme.

Phonon Self-Energy Corrections to Nonzero Wave-Vector Phonon Modes in Single-Layer Graphene

Science.gov (United States)

Araujo, P. T.; Mafra, D. L.; Sato, K.; Saito, R.; Kong, J.; Dresselhaus, M. S.

2012-07-01

Phonon self-energy corrections have mostly been studied theoretically and experimentally for phonon modes with zone-center (q=0) wave vectors. Here, gate-modulated Raman scattering is used to study phonons of a single layer of graphene originating from a double-resonant Raman process with q≠0. The observed phonon renormalization effects are different from what is observed for the zone-center q=0 case. To explain our experimental findings, we explored the phonon self-energy for the phonons with nonzero wave vectors (q≠0) in single-layer graphene in which the frequencies and decay widths are expected to behave oppositely to the behavior observed in the corresponding zone-center q=0 processes. Within this framework, we resolve the identification of the phonon modes contributing to the G⋆ Raman feature at 2450cm-1 to include the iTO+LA combination modes with q≠0 and also the 2iTO overtone modes with q=0, showing both to be associated with wave vectors near the high symmetry point K in the Brillouin zone.

Chemical potential pinning due to equilibrium electron transfer at metal/C60-doped polymer interfaces

Science.gov (United States)

Heller, C. M.; Campbell, I. H.; Smith, D. L.; Barashkov, N. N.; Ferraris, J. P.

1997-04-01

We report electroabsorption measurements of the built-in electrostatic potential in metal/C60-doped polymer/metal structures to investigate chemical potential pinning due to equilibrium electron transfer from a metal contact to the electron acceptor energy level of C60 molecules in the polymer film. The built-in potentials of a series of structures employing thin films of both undoped and C60-doped poly[2-methoxy, 5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) were measured. For undoped MEH-PPV, which has an energy gap of about 2.4 eV, the maximum built-in potential is about 2.1 eV, whereas for C60-doped MEH-PPV the maximum built-in potential decreases to 1.5 eV. Electron transfer to the C60 molecules close to the metal interface pins the chemical potential of the metal contact near the electron acceptor energy level of C60 and decreases the built-in potential of the structure. From the systematic dependence of the built-in potential on the metal work function we find that the electron acceptor energy level of C60 in MEH-PPV is about 1.7 eV above the hole polaron energy level of MEH-PPV.

Chemical analyses of wasp-associated streptomyces bacteria reveal a prolific potential for natural products discovery

DEFF Research Database (Denmark)

Poulsen, Michael; Oh, Dong-Chan; Clardy, Jon

2011-01-01

and solitary Hymenoptera. Here we test this possibility by examining two species of solitary mud dauber wasps, Sceliphron caementarium and Chalybion californicum. We performed enrichment isolations from 33 wasps and obtained more than 200 isolates of Streptomyces Actinobacteria. Chemical analyses of 15...... and antibacterial activity. The prevalence and anti-microbial properties of Actinobacteria associated with these two solitary wasp species suggest the potential role of these Streptomyces as antibiotic-producing symbionts, potentially helping defend their wasp hosts from pathogenic microbes. Finding...... phylogenetically diverse and chemically prolific Actinobacteria from solitary wasps suggests that insect-associated Actinobacteria can provide a valuable source of novel natural products of pharmaceutical interest....

Magnon spin transport driven by the magnon chemical potential in a magnetic insulator

NARCIS (Netherlands)

Cornelissen, L J; Peters, K J H; Bauer, G. E. W.; Duine, R A; van Wees, B J

2016-01-01

We develop a linear-response transport theory of diffusive spin and heat transport by magnons in magnetic insulators with metallic contacts. The magnons are described by a position-dependent temperature and chemical potential that are governed by diffusion equations with characteristic relaxation

Magnon spin transport driven by the magnon chemical potential in a magnetic insulator

NARCIS (Netherlands)

Cornelissen, L.J.; Peters, K. J H; Bauer, G.E.; Duine, R. A.; Van Wees, B. J.

2016-01-01

We develop a linear-response transport theory of diffusive spin and heat transport by magnons in magnetic insulators with metallic contacts. The magnons are described by a position-dependent temperature and chemical potential that are governed by diffusion equations with characteristic relaxation

Magnon spin transport driven by the magnon chemical potential in a magnetic insulator

NARCIS (Netherlands)

Cornelissen, Ludo J.; Peters, Kevin J. H.; Duine, Rembert A.|info:eu-repo/dai/nl/304830127; Bauer, Gerrit E. W.; Wees, Bart J. van

2016-01-01

We develop a linear-response transport theory of diffusive spin and heat transport by magnons in magnetic insulators with metallic contacts. The magnons are described by a position dependent temperature and chemical potential that are governed by diffusion equations with characteristic relaxation

Chemical, Bioactive, and Antioxidant Potential of Twenty Wild Culinary Mushroom Species

OpenAIRE

Sharma, S. K.; Gautam, N.

2015-01-01

The chemical, bioactive, and antioxidant potential of twenty wild culinary mushroom species being consumed by the people of northern Himalayan regions has been evaluated for the first time in the present study. Nutrients analyzed include protein, crude fat, fibres, carbohydrates, and monosaccharides. Besides, preliminary study on the detection of toxic compounds was done on these species. Bioactive compounds evaluated are fatty acids, amino acids, tocopherol content, carotenoids (β-carotene, ...

Phyto chemical and biological studies of certain plants with potential radioprotective activity

International Nuclear Information System (INIS)

Sherif, N.H.M.I

2008-01-01

One of the promising directions of radiation protection development is the search for natural radioprotective agents.The present work includes: I- Screening of certain edible and medicinal plants growing in Egypt for their radioprotective activities. II- Detailed phyto chemical and biolo-activity studies of the dried leaves of brassaia actinophylla endl. comprising: A-Phyto chemical screening and proximate analysis. B-Investigation of lipoidal matter. C- Isolation, characterization and structure elucidation of phenolic constituents. D- Isolation, characterization and structure elucidation of saponin constituents. E- Evaluation of radioprotective and antitumor activities. I- Evaluation of potential radioprotective activities of certain herbs: In vivo biological screening designed to investigate the radioprotective role of 70% ethanol extract of 11 different herbals was carried out by measuring the lipid peroxide content, as well as the activities of two antioxidant enzymes; viz glutathione, and superoxide dismutase in blood and liver tissues 1 and 7 days after radiation exposure. II : Phyto chemical and biolo-activity studies of the dried leaves of brassaia actinophylla Endl A : preliminary phyto chemical screening, determination and TLC examination of successive extractives. B : Investigation of lipoidal matter. GLC of unsaponifiable matter (USM)

Supersymmetric Solution of the Schroedinger Equation for Woods-Saxon Potential by Using the Pekeris Approximation

International Nuclear Information System (INIS)

Feizi, H.; Rajabi, A.A.; Shojaei, M.R.

2011-01-01

In this work, the three dimensional Woods-Saxon potential is studied within the context of Supersymmetry Quantum Mechanics. We have applied the SUSY method by using the Pekeris approximation to the centrifugal potential l ≠ 0 states. By application of this method, it is possible to solve the Schroedinger equation for this potential. We obtain exactly bound state spectrum and wave function of Woods-Saxon potential for nonzero angular momentum. Hamiltonian hierarchy method and the shape invariance property are used in the calculations. (authors)

Holographic black hole engineering at finite baryon chemical potential

International Nuclear Information System (INIS)

Rougemont, Romulo

2017-01-01

This is a contribution for the Proceedings of the Conference Hot Quarks 2016, held at South Padre Island, Texas, USA, 12-17 September 2016. I briefly review some thermodynamic and baryon transport results obtained from a bottom-up Einstein-Maxwell-Dilaton holographic model engineered to describe the physics of the quark-gluon plasma at finite temperature and baryon density. The results for the equation of state, baryon susceptibilities, and the curvature of the crossover band are in quantitative agreement with the corresponding lattice QCD results with 2 + 1 flavors and physical quark masses. Baryon diffusion is predicted to be suppressed by increasing the baryon chemical potential. (paper)

Physico-chemical characteristics and market potential of sawdust charcoal briquette

Energy Technology Data Exchange (ETDEWEB)

Akowuah, Joseph O.; Kemausuor, Francis [Kwame Nkrumah Univ. of Science and Technology, Kumasi (Ghana). Dept. of Agricultural Engineering; Mitchual, Stephen J. [Univ. of Education, Winneba, Kumasi (Ghana). Dept. of Design and Technology Education

2012-11-01

In the absence of the widespread distribution of modern cooking fuels in developing countries, efforts are being made to utilise biomass residues which abound in most of these countries. This is intended to replace portions of firewood and charcoal and thereby reduce the cutting down of forests for fuel purposes. Briquettes from agro-residues have therefore been promoted as a better replacement to firewood and charcoals for heating, cooking and other industrial applications in both urban and rural communities. This study sought to assess the physico-chemical properties of charcoal briquettes produced in Ghana and also establish demand for and willingness of potential users to substitute charcoal and firewood with a charcoal briquette. A laboratory experiment was conducted to determine the physicochemical characteristics of the briquettes. This was done prior to the distribution of the briquette to potential users to collaborate their views or otherwise on the handling and burning characteristics of the charcoal briquette. A survey was undertaken a week later using questionnaires to access the willingness of the potential users to use the briquettes. Sixty respondents were purposively selected from households and the hospitality industry for the survey. Results of the physico-chemical assessment of the briquettes were as follows: length (75 to 120 mm), moisture content (5.7% dry basis), density (1.1 g/cm{sup 3}), ash content (2.6%), fixed carbon (20.7%), volatile matter (71%) and calorific value (4,820 kcal/kg). Responses from the survey indicated that the briquette is easy to ignite, has a long burning time and has good heat output. Respondents also observed that the briquettes did not give off sparks and had less smoke and ash content as compared to the regular charcoal they often used. Finally, 93% of the respondents indicated their willingness to use the briquettes if the price was comparable to charcoal. (orig.)

Magnetic properties of confined holographic QCD

Science.gov (United States)

Bergman, Oren; Lifschytz, Gilad; Lippert, Matthew

2013-12-01

We investigate the Sakai-Sugimoto model at nonzero baryon chemical potential in a background magnetic field in the confined phase where chiral symmetry is broken. The D8-brane Chern-Simons term holographically encodes the axial anomaly and generates a gradient of the η' meson, which carries a non-vanishing baryon charge. Above a critical value of the chemical potential, there is a second-order phase transition to a mixed phase which includes also ordinary baryonic matter. However, at fixed baryon charge density, the matter is purely η'-gradient above a critical magnetic field.

Positivity, discontinuity, finite resources, and nonzero error for arbitrarily varying quantum channels

International Nuclear Information System (INIS)

Boche, H.; Nötzel, J.

2014-01-01

This work is motivated by a quite general question: Under which circumstances are the capacities of information transmission systems continuous? The research is explicitly carried out on finite arbitrarily varying quantum channels (AVQCs). We give an explicit example that answers the recent question whether the transmission of messages over AVQCs can benefit from assistance by distribution of randomness between the legitimate sender and receiver in the affirmative. The specific class of channels introduced in that example is then extended to show that the unassisted capacity does have discontinuity points, while it is known that the randomness-assisted capacity is always continuous in the channel. We characterize the discontinuity points and prove that the unassisted capacity is always continuous around its positivity points. After having established shared randomness as an important resource, we quantify the interplay between the distribution of finite amounts of randomness between the legitimate sender and receiver, the (nonzero) probability of a decoding error with respect to the average error criterion and the number of messages that can be sent over a finite number of channel uses. We relate our results to the entanglement transmission capacities of finite AVQCs, where the role of shared randomness is not yet well understood, and give a new sufficient criterion for the entanglement transmission capacity with randomness assistance to vanish

Possible Long Term Effects of Chemical Warfare Using Visual Evoked Potentials

Directory of Open Access Journals (Sweden)

Abbas Riazi

2014-09-01

Full Text Available Some studies have already addressed the effects of occupational organic solvent exposure on the visually evoked potentials (VEPs. Visual system is an important target for Sulphur Mustard (SM toxicity. A number of Iranian victims of Sulphur Mustard (SM agent were apprehensive about the delay effect of SM on their vision and a possible delay effect of SM on their visual cortex. This investigation was performed on 34 individuals with a history of chemical exposure and a control group of 15 normal people. The Toennies electro-diagnosis device was used and its signals were saved as the latencies. The mean of N75, N140 and P100 of victims of chemical warfare (VCWs and control group indicated no significant results (P>0.05. The VCWs did not show any visual symptoms and there was no clear deficit in their VEPs.

Semileptonic B to D Decays at Nonzero Recoil with 2+1 Flavors of Improved Staggered Quarks

International Nuclear Information System (INIS)

Qiu, Si-Wei; DeTar, Carleton; Du, Daping; Kronfeld, Andreas S.; Laiho, Jack; Van de Water, Ruth S.

2011-01-01

The Fermilab Lattice-MILC collaboration is completing a comprehensive program of heavy-light physics on the MILC (2+1)-flavor asqtad ensembles with lattice spacings as small as 0.045 fm and light-to-strange-quark mass ratios as low as 1/20. We use the Fermilab interpretation of the clover action for heavy valence quarks and the asqtad action for light valence quarks. The central goal of the program is to provide ever more exacting tests of the unitarity of the CKM matrix. We give a progress report on one part of the program, namely the analysis of the semileptonic decay B to D at both zero and nonzero recoil. Although final results are not presented, we discuss improvements in the analysis methods, the statistical errors, and the parameter coverage that we expect will lead to a significant reduction in the final error for |V cb | from this decay channel.

Chemical characteristics and methane potentials of source-separated and pre-treated organic municipal solid waste

DEFF Research Database (Denmark)

Hansen, Trine Lund; Svärd, Å; Angelidaki, Irini

2003-01-01

A research project has investigated the biogas potential of pre-screened source-separated organic waste. Wastes from five Danish cities have been pre-treated by three methods: screw press; disc screen; and shredder and magnet. This paper outlines the sampling procedure used, the chemical...... composition of the wastes and the estimated methane potentials....

Potential Challenges Faced by the U.S. Chemicals Industry under a Carbon Policy

Directory of Open Access Journals (Sweden)

Andrea Bassi

2009-09-01

Full Text Available Chemicals have become the backbone of manufacturing within industrialized economies. Being energy-intensive materials to produce, this sector is threatened by policies aimed at combating and adapting to climate change. This study examines the worst-case scenario for the U.S. chemicals industry when a medium CO2 price policy is employed. After examining possible industry responses, the study goes on to identify and provide a preliminary evaluation of potential opportunities to mitigate these impacts. If climate regulations are applied only in the United States, and no action is taken to invest in advanced low- and no-carbon technologies to mitigate the impacts of rising energy costs, the examination shows that climate policies that put a price on carbon could have substantial impacts on the competiveness of the U.S. chemicals industry over the next two decades. In the long run, there exist technologies that are available to enable the chemicals sector to achieve sufficient efficiency gains to offset and manage the additional energy costs arising from a climate policy.

Phase Diagram of the ν=5/2 Fractional Quantum Hall Effect: Effects of Landau-Level Mixing and Nonzero Width

Directory of Open Access Journals (Sweden)

Kiryl Pakrouski

2015-04-01

Full Text Available Interesting non-Abelian states, e.g., the Moore-Read Pfaffian and the anti-Pfaffian, offer candidate descriptions of the ν=5/2 fractional quantum Hall state. But, the significant controversy surrounding the nature of the ν=5/2 state has been hampered by the fact that the competition between these and other states is affected by small parameter changes. To study the phase diagram of the ν=5/2 state, we numerically diagonalize a comprehensive effective Hamiltonian describing the fractional quantum Hall effect of electrons under realistic conditions in GaAs semiconductors. The effective Hamiltonian takes Landau-level mixing into account to lowest order perturbatively in κ, the ratio of the Coulomb energy scale to the cyclotron gap. We also incorporate the nonzero width w of the quantum-well and subband mixing. We find the ground state in both the torus and spherical geometries as a function of κ and w. To sort out the nontrivial competition between candidate ground states, we analyze the following four criteria: its overlap with trial wave functions, the magnitude of energy gaps, the sign of the expectation value of an order parameter for particle-hole symmetry breaking, and the entanglement spectrum. We conclude that the ground state is in the universality class of the Moore-Read Pfaffian state, rather than the anti-Pfaffian, for κ<κ_{c}(w, where κ_{c}(w is a w-dependent critical value 0.6≲κ_{c}(w≲1. We observe that both Landau-level mixing and nonzero width suppress the excitation gap, but Landau-level mixing has a larger effect in this regard. Our findings have important implications for the identification of non-Abelian fractional quantum Hall states.

Nonextensive thermodynamics with finite chemical potentials and protoneutron starss⋆,⋆⋆

Directory of Open Access Journals (Sweden)

Megías Eugenio

2014-01-01

Full Text Available We derive the nonextensive thermodynamics of an ideal quantum gas composed by bosons and/or fermions with finite chemical potentials. We find agreement with previous works when μ ≤ m, and some inconsistencies are corrected for fermions when μ > m. This formalism is then used to study the thermodynamical properties of hadronic systems based on a Hadron Resonance Gas approach. We apply this result to study the protoneutron star stability under several conditions.

Towards overcoming the Monte Carlo sign problem with tensor networks

Directory of Open Access Journals (Sweden)

Bañuls Mari Carmen

2017-01-01

Full Text Available The study of lattice gauge theories with Monte Carlo simulations is hindered by the infamous sign problem that appears under certain circumstances, in particular at non-zero chemical potential. So far, there is no universal method to overcome this problem. However, recent years brought a new class of non-perturbative Hamiltonian techniques named tensor networks, where the sign problem is absent. In previous work, we have demonstrated that this approach, in particular matrix product states in 1+1 dimensions, can be used to perform precise calculations in a lattice gauge theory, the massless and massive Schwinger model. We have computed the mass spectrum of this theory, its thermal properties and real-time dynamics. In this work, we review these results and we extend our calculations to the case of two flavours and non-zero chemical potential. We are able to reliably reproduce known analytical results for this model, thus demonstrating that tensor networks can tackle the sign problem of a lattice gauge theory at finite density.

Potential application of population models in the European ecological risk assessment of chemicals. II. Review of models and their potential to address environmental protection aims.

Science.gov (United States)

Galic, Nika; Hommen, Udo; Baveco, J M Hans; van den Brink, Paul J

2010-07-01

Whereas current chemical risk assessment (RA) schemes within the European Union (EU) focus mainly on toxicity and bioaccumulation of chemicals in individual organisms, most protection goals aim at preserving populations of nontarget organisms rather than individuals. Ecological models are tools rarely recommended in official technical documents on RA of chemicals, but are widely used by researchers to assess risks to populations, communities and ecosystems. Their great advantage is the relatively straightforward integration of the sensitivity of species to chemicals, the mode of action and fate in the environment of toxicants, life-history traits of the species of concern, and landscape features. To promote the usage of ecological models in regulatory risk assessment, this study tries to establish whether existing, published ecological modeling studies have addressed or have the potential to address the protection aims and requirements of the chemical directives of the EU. We reviewed 148 publications, and evaluated and analyzed them in a database according to defined criteria. Published models were also classified in terms of 5 areas where their application would be most useful for chemical RA. All potential application areas are well represented in the published literature. Most models were developed to estimate population-level responses on the basis of individual effects, followed by recovery process assessment, both in individuals and at the level of metapopulations. We provide case studies for each of the proposed areas of ecological model application. The lack of clarity about protection goals in legislative documents made it impossible to establish a direct link between modeling studies and protection goals. Because most of the models reviewed here were not developed for regulatory risk assessment, there is great potential and a variety of ecological models in the published literature. (c) 2010 SETAC.

Asymptotic Performance Analysis of Two-Way Relaying FSO Networks with Nonzero Boresight Pointing Errors Over Double-Generalized Gamma Fading Channels

KAUST Repository

Yang, Liang; Alouini, Mohamed-Slim; Ansari, Imran Shafique

2018-01-01

In this correspondence, an asymptotic performance analysis for two-way relaying free-space optical (FSO) communication systems with nonzero boresight pointing errors over double-generalized gamma fading channels is presented. Assuming amplify-and-forward (AF) relaying, two nodes having the FSO ability can communicate with each other through the optical links. With this setup, an approximate cumulative distribution function (CDF) expression for the overall signal-to-noise ratio (SNR) is presented. With this statistic distribution, we derive the asymptotic analytical results for the outage probability and average bit error rate. Furthermore, we provide the asymptotic average capacity analysis for high SNR by using the momentsbased method.

Asymptotic Performance Analysis of Two-Way Relaying FSO Networks with Nonzero Boresight Pointing Errors Over Double-Generalized Gamma Fading Channels

KAUST Repository

Yang, Liang

2018-05-07

In this correspondence, an asymptotic performance analysis for two-way relaying free-space optical (FSO) communication systems with nonzero boresight pointing errors over double-generalized gamma fading channels is presented. Assuming amplify-and-forward (AF) relaying, two nodes having the FSO ability can communicate with each other through the optical links. With this setup, an approximate cumulative distribution function (CDF) expression for the overall signal-to-noise ratio (SNR) is presented. With this statistic distribution, we derive the asymptotic analytical results for the outage probability and average bit error rate. Furthermore, we provide the asymptotic average capacity analysis for high SNR by using the momentsbased method.

Chemical Characterization and Antioxidant Potential of Wild Ganoderma Species from Ghana.

Science.gov (United States)

Obodai, Mary; Mensah, Deborah L Narh; Fernandes, Ângela; Kortei, Nii Korley; Dzomeku, Matilda; Teegarden, Matthew; Schwartz, Steven J; Barros, Lillian; Prempeh, Juanita; Takli, Richard K; Ferreira, Isabel C F R

2017-01-25

The chemical characterization and antioxidant potential of twelve wild strains of Ganoderma sp. from Ghana, nine (LS1-LS9) of which were found growing wild simultaneously on the same dying Delonix regia tree, were evaluated. Parameters evaluated included the nutritional value, composition in sugars, fatty acids, phenolic and other organic compounds and some vitamins and vitamin precursors. Antioxidant potential was evaluated by investigating reducing power, radical scavenging activity and lipid peroxidation inhibition using five in vitro assays. Protein, carbohydrate, fat, ash and energy contents ranged between 15.7-24.5 g/100 g·dw, 73.31-81.90 g/100 g, 0.48-1.40 g/100 g, 0.68-2.12 g/100 g ash and 396.1-402.02 kcal/100 g, respectively. Fatty acids such as linoleic, oleic and palmitic acids were relatively abundant. Free sugars included rhamnose, fructose, mannitol, sucrose and trehalose. Total tocopherols, organic acids and phenolic compounds' content ranged between 741-3191 µg/100 g, 77-1003 mg/100 g and 7.6-489 µg/100 g, respectively. There were variations in the β-glucans, ergosterol and vitamin D₂ contents. The three major minerals in decreasing order were K > P > S. Ganoderma sp. strain AM1 showed the highest antioxidant activity. This study reveals, for the first time, chemical characteristics of Ganoderma spp. which grew simultaneously on the same tree.

On the spectrum of the staggered Dirac operator at finite chemical potential

International Nuclear Information System (INIS)

Vink, J.C.; Nationaal Inst. voor Kernfysica en Hoge-Energiefysica

1988-12-01

The spectrum of the staggered Dirac operator in two-dimensional QEDF is investigated at finite chemical potential. In the quenced model, it is shown that lattice artefacts cause a spurious scattering of eigenvalues. This scattering disappears when lattice distance is taken to zero. In the unquenced model, a new approach is used to show that similar effects are absent. (author). 17 refs.; 6 figs

Finite-size, chemical-potential and magnetic effects on the phase transition in a four-fermion interacting model

Energy Technology Data Exchange (ETDEWEB)

Correa, E.B.S. [Universidade Federal do Sul e Sudeste do Para, Instituto de Ciencias Exatas, Maraba (Brazil); Centro Brasileiro de Pesquisas Fisicas-CBPF/MCTI, Rio de Janeiro (Brazil); Linhares, C.A. [Universidade do Estado do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro (Brazil); Malbouisson, A.P.C. [Centro Brasileiro de Pesquisas Fisicas-CBPF/MCTI, Rio de Janeiro (Brazil); Malbouisson, J.M.C. [Universidade Federal da Bahia, Instituto de Fisica, Salvador (Brazil); Santana, A.E. [Universidade de Brasilia, Instituto de Fisica, Brasilia, DF (Brazil)

2017-04-15

We study effects coming from finite size, chemical potential and from a magnetic background on a massive version of a four-fermion interacting model. This is performed in four dimensions as an application of recent developments for dealing with field theories defined on toroidal spaces. We study effects of the magnetic field and chemical potential on the size-dependent phase structure of the model, in particular, how the applied magnetic field affects the size-dependent critical temperature. A connection with some aspects of the hadronic phase transition is established. (orig.)

Phonon self-energy corrections to non-zero wavevector phonon modes in single-layer graphene

Science.gov (United States)

Araujo, Paulo; Mafra, Daniela; Sato, Kentaro; Saito, Richiiro; Kong, Jing; Dresselhaus, Mildred

2012-02-01

Phonon self-energy corrections have mostly been studied theoretically and experimentally for phonon modes with zone-center (q = 0) wave-vectors. Here, gate-modulated Raman scattering is used to study phonons of a single layer of graphene (1LG) in the frequency range from 2350 to 2750 cm-1, which shows the G* and the G'-band features originating from a double-resonant Raman process with q 0. The observed phonon renormalization effects are different from what is observed for the zone-center q = 0 case. To explain our experimental findings, we explored the phonon self-energy for the phonons with non-zero wave-vectors (q 0) in 1LG in which the frequencies and decay widths are expected to behave oppositely to the behavior observed in the corresponding zone-center q = 0 processes. Within this framework, we resolve the identification of the phonon modes contributing to the G* Raman feature at 2450 cm-1 to include the iTO+LA combination modes with q 0 and the 2iTO overtone modes with q = 0, showing both to be associated with wave-vectors near the high symmetry point K in the Brillouin zone.

Chemical potential of molecules contrasted to averaged atomic electronegativities: alarming differences and their theoretical rationalization.

Science.gov (United States)

Datta, Dipankar; Shee, Nirmal K; von Szentpály, László

2013-01-10

We present the first large-scale empirical examination of the relation of molecular chemical potentials, μ(0)(mol) = -½(I(0) + A(0))(mol), to the geometric mean (GM) of atomic electronegativities, (GM) = (GM), and demonstrate that μ(0)(mol) ≠ -(GM). Out of 210 molecular μ(0)(mol)values considered more than 150 are not even in the range min{μ(0)(at)} (GM). For this equation the root-mean-square of relative errors amounts to SE = 71%. Our results are at strong variance with Sanderson's electronegativity equalization principle and present a challenge to some popular practice in conceptual density functional theory (DFT). The influences of the "external" potential and charge dependent covalent and ionic binding contributions are discussed and provide the theoretical rationalization for the empirical facts. Support is given to the warnings by Hinze, Bader et al., Allen, and Politzer et al. that equating the chemical potential to the negative of electronegativity may lead to misconceptions.

Pion multiplicity as a probe of the deconfinement transition in heavy-ion collisions

International Nuclear Information System (INIS)

Gorenstejn, M.I.; Shin Nan Yang; Che Ming Ko.

1991-01-01

The hydrochemical model is used to calculate the pion multiplicity in relativistic heavy-ion collisions. Chemical reactions are explicitly taken into account in the expansion stage of the hadronic phase. It leads to the absence of chemical equilibrium among hadronic particles and a nonzero value of the pion chemical potential at thermal freeze out. We find a specific structure in the incident energy dependence of the pion multiplicity as a result of the formation of the quark-hadron mixed phase in the initial stage of the collision. 13 refs.; 3 figs

Identifying potential surface water sampling sites for emerging chemical pollutants in Gauteng Province, South Africa

OpenAIRE

Petersen, F; Dabrowski, JM; Forbes, PBC

2017-01-01

Emerging chemical pollutants (ECPs) are defined as new chemicals which do not have a regulatory status, but which may have an adverse effect on human health and the environment. The occurrence and concentrations of ECPs in South African water bodies are largely unknown, so monitoring is required in order to determine the potential threat that these ECPs may pose. Relevant surface water sampling sites in the Gauteng Province of South Africa were identified utilising a geographic information sy...

Chemical potentials and thermodynamic characteristics of ideal Bose- and Fermi-gases in the region of quantum degeneracy

Science.gov (United States)

Sotnikov, A. G.; Sereda, K. V.; Slyusarenko, Yu. V.

2017-01-01

Calculations of chemical potentials for ideal monatomic gases with Bose-Einstein and Fermi-Dirac statistics as functions of temperature, across the temperature region that is typical for the collective quantum degeneracy effect, are presented. Numerical calculations are performed without any additional approximations, and explicit dependences of the chemical potentials on temperature are constructed at a fixed density of gas particles. Approximate polynomial dependences of chemical potentials on temperature are obtained that allow for the results to be used in further studies without re-applying the involved numerical methods. The ease of using the obtained representations is demonstrated on examples of deformation of distribution for a population of energy states at low temperatures, and on the impact of quantum statistics (exchange interaction) on the equations of state for ideal gases and some of the thermodynamic properties thereof. The results of this study essentially unify two opposite limiting cases in an intermediate region that are used to describe the equilibrium states of ideal gases, which are well known from university courses on statistical physics, thus adding value from an educational point of view.

Chemical Ecology of the Colorado Potato Beetle, Leptinotarsa decemlineata (Say (Coleoptera: Chrysomelidae, and Potential for Alternative Control Methods

Directory of Open Access Journals (Sweden)

François J. Verheggen

2012-12-01

Full Text Available The Colorado potato beetle (CPB has been a major insect pest to potato farming for over 150 years and various control methods have been established to reduce its impact on potato fields. Crop rotation and pesticide use are currently the most widely used approaches, although alternative methods are being developed. Here we review the role of various volatile and nonvolatile chemicals involved in behavior changes of CPB that may have potential for their control. First, we describe all volatile and nonvolatile chemicals involved in host plant localization and acceptance by CPB beetles, including glycoalcaloids and host plant volatiles used as kairomones. In the second section, we present the chemical signals used by CPB in intraspecific communication, including sex and aggregation pheromones. Some of these chemicals are used by natural enemies of CPBs to locate their prey and are presented in the third section. The last section of this review is devoted a discussion of the potential of some natural chemicals in biological control of CPB and to approaches that already reached efficient field applications.

Computed Potential Energy Surfaces and Minimum Energy Pathway for Chemical Reactions

Science.gov (United States)

Walch, Stephen P.; Langhoff, S. R. (Technical Monitor)

1994-01-01

Computed potential energy surfaces are often required for computation of such observables as rate constants as a function of temperature, product branching ratios, and other detailed properties. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method with the Dunning correlation consistent basis sets to obtain accurate energetics, gives useful results for a number of chemically important systems. Applications to complex reactions leading to NO and soot formation in hydrocarbon combustion are discussed.

Drag force in strongly coupled, anisotropic plasma at finite chemical potential

Energy Technology Data Exchange (ETDEWEB)

Chakraborty, Somdeb; Haque, Najmul [Theory Division, Saha Institute of Nuclear Physics,1/AF Bidhannagar, Kolkata-700 064 (India)

2014-12-30

We employ methods of gauge/string duality to analyze the drag force on a heavy quark moving through a strongly coupled, anisotropic N=4,SU(N) super Yang-Mills plasma in the presence of a finite U(1) chemical potential. We present numerical results valid for any value of the anisotropy parameter and the U(1) charge density and arbitrary direction of the quark velocity with respect to the direction of anisotropy. In the small anisotropy limit we are also able to furnish analytical results.

Potential of Biofilters for Treatment of De-Icing Chemicals

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Gema Sakti Raspati

2018-05-01

Full Text Available Organic de-icing chemicals, such as propylene glycol and potassium formate, cause environmental degradation in receiving water if left untreated, due to the high organic load resulting in oxygen depletion. Biofilters are commonly used for the treatment of biodegradable organic carbon in water treatment. This study investigated the potential for using biofilters for treating organic de-icing compounds. Lab-scale adsorption tests using filter media made of crushed clay (Filtralite and granular activated carbon were conducted. Further, a column filtration experiment testing two different crushed clay size ranges was carried out investigating the effect of filter media depth, nutrient addition, and filtration rate. The surrogate parameter used to monitor the removal of de-icing chemicals was dissolved organic carbon (DOC. The adsorption test showed no significant adsorption of DOC was observed. The column test showed that the most active separation occurred in the first ~20 cm of the filter depth. This was confirmed by results from (1 water quality analysis (i.e., DOC removal and adenosine tri-phosphate (ATP measurement; and (2 calculations based on a filtration performance analysis (Iwasaki model and filter hydraulic evaluation (Lindquist diagram. The results showed that, for the highest C:N:P ratio tested (molar ratio of 24:7:1, 50–60% DOC removal was achieved. The addition of nutrients was found to be important for determining the biofilter performance.

A Core-Offset Mach Zehnder Interferometer Based on A Non-Zero Dispersion-Shifted Fiber and Its Torsion Sensing Application

Directory of Open Access Journals (Sweden)

Eduardo Huerta-Mascotte

2016-06-01

Full Text Available In this paper, an all-fiber Mach-Zehnder interferometer (MZI based on a non-zero dispersion-shifted fiber (NZ-DSF is presented. The MZI was implemented by core-offset fusion splicing one section of a NZ-DSF fiber between two pieces of single mode fibers (SMFs. Here, the NZ-DSF core and cladding were used as the arms of the MZI, while the core-offset sections acted as optical fiber couplers. Thus, a MZI interference spectrum with a fringe contrast (FC of about 20 dB was observed. Moreover, its response spectrum was experimentally characterized to the torsion parameter and a sensitivity of 0.070 nm/° was achieved. Finally, these MZIs can be implemented in a compact size and low cost.

Chemical Compounds Toxic to Invertebrates Isolated from Marine Cyanobacteria of Potential Relevance to the Agricultural Industry

KAUST Repository

Essack, Magbubah

2014-10-29

In spite of advances in invertebrate pest management, the agricultural industry is suffering from impeded pest control exacerbated by global climate changes that have altered rain patterns to favour opportunistic breeding. Thus, novel naturally derived chemical compounds toxic to both terrestrial and aquatic invertebrates are of interest, as potential pesticides. In this regard, marine cyanobacterium-derived metabolites that are toxic to both terrestrial and aquatic invertebrates continue to be a promising, but neglected, source of potential pesticides. A PubMed query combined with hand-curation of the information from retrieved articles allowed for the identification of 36 cyanobacteria-derived chemical compounds experimentally confirmed as being toxic to invertebrates. These compounds are discussed in this review.

Chemical Compounds Toxic to Invertebrates Isolated from Marine Cyanobacteria of Potential Relevance to the Agricultural Industry

KAUST Repository

Essack, Magbubah; Alzubaidy, Hanin S.; Bajic, Vladimir B.; Archer, John A.C.

2014-01-01

In spite of advances in invertebrate pest management, the agricultural industry is suffering from impeded pest control exacerbated by global climate changes that have altered rain patterns to favour opportunistic breeding. Thus, novel naturally derived chemical compounds toxic to both terrestrial and aquatic invertebrates are of interest, as potential pesticides. In this regard, marine cyanobacterium-derived metabolites that are toxic to both terrestrial and aquatic invertebrates continue to be a promising, but neglected, source of potential pesticides. A PubMed query combined with hand-curation of the information from retrieved articles allowed for the identification of 36 cyanobacteria-derived chemical compounds experimentally confirmed as being toxic to invertebrates. These compounds are discussed in this review.

Chemical Compounds Toxic to Invertebrates Isolated from Marine Cyanobacteria of Potential Relevance to the Agricultural Industry

Science.gov (United States)

Essack, Magbubah; Alzubaidy, Hanin S.; Bajic, Vladimir B.; Archer, John A. C.

2014-01-01

In spite of advances in invertebrate pest management, the agricultural industry is suffering from impeded pest control exacerbated by global climate changes that have altered rain patterns to favour opportunistic breeding. Thus, novel naturally derived chemical compounds toxic to both terrestrial and aquatic invertebrates are of interest, as potential pesticides. In this regard, marine cyanobacterium-derived metabolites that are toxic to both terrestrial and aquatic invertebrates continue to be a promising, but neglected, source of potential pesticides. A PubMed query combined with hand-curation of the information from retrieved articles allowed for the identification of 36 cyanobacteria-derived chemical compounds experimentally confirmed as being toxic to invertebrates. These compounds are discussed in this review. PMID:25356733

Chemical potential pinning due to equilibrium electron transfer at metal/C{sub 60}-doped polymer interfaces

Energy Technology Data Exchange (ETDEWEB)

Heller, C.M.; Campbell, I.H.; Smith, D.L. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Barashkov, N.N.; Ferraris, J.P. [The University of Texas at Dallas, Richardson, Texas 75080 (United States)

1997-04-01

We report electroabsorption measurements of the built-in electrostatic potential in metal/C{sub 60}-doped polymer/metal structures to investigate chemical potential pinning due to equilibrium electron transfer from a metal contact to the electron acceptor energy level of C{sub 60} molecules in the polymer film. The built-in potentials of a series of structures employing thin films of both undoped and C{sub 60}-doped poly[2-methoxy, 5-(2{sup {prime}}-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) were measured. For undoped MEH-PPV, which has an energy gap of about 2.4 eV, the maximum built-in potential is about 2.1 eV, whereas for C{sub 60}-doped MEH-PPV the maximum built-in potential decreases to 1.5 eV. Electron transfer to the C{sub 60} molecules close to the metal interface pins the chemical potential of the metal contact near the electron acceptor energy level of C{sub 60} and decreases the built-in potential of the structure. From the systematic dependence of the built-in potential on the metal work function we find that the electron acceptor energy level of C{sub 60} in MEH-PPV is about 1.7 eV above the hole polaron energy level of MEH-PPV. {copyright} {ital 1997 American Institute of Physics.}

Prediction of the contact sensitizing potential of chemicals using analysis of gene expression changes in human THP-1 monocytes.

Science.gov (United States)

Arkusz, Joanna; Stępnik, Maciej; Sobala, Wojciech; Dastych, Jarosław

2010-11-10

The aim of this study was to find differentially regulated genes in THP-1 monocytic cells exposed to sensitizers and nonsensitizers and to investigate if such genes could be reliable markers for an in vitro predictive method for the identification of skin sensitizing chemicals. Changes in expression of 35 genes in the THP-1 cell line following treatment with chemicals of different sensitizing potential (from nonsensitizers to extreme sensitizers) were assessed using real-time PCR. Verification of 13 candidate genes by testing a large number of chemicals (an additional 22 sensitizers and 8 nonsensitizers) revealed that prediction of contact sensitization potential was possible based on evaluation of changes in three genes: IL8, HMOX1 and PAIMP1. In total, changes in expression of these genes allowed correct detection of sensitization potential of 21 out of 27 (78%) test sensitizers. The gene expression levels inside potency groups varied and did not allow estimation of sensitization potency of test chemicals. Results of this study indicate that evaluation of changes in expression of proposed biomarkers in THP-1 cells could be a valuable model for preliminary screening of chemicals to discriminate an appreciable majority of sensitizers from nonsensitizers. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

CHEMICAL COMPOSITION OF CAATINGA POTENTIAL FORAGES SPECIES

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Dynara Layza de Souza da Silva

2015-12-01

Full Text Available Chemical composition of some potential forages species, natives from Caatinga region, were evaluated. Samples of Macroptilium heterophyllum, Stylosanthes humilis, Rhynchosia mínima, Desmodium tortuosum Sw. Dc, Merremia aegyptia, Mimosa tenuiflora Wild, Bauhinia cheilantha and as well Macroptilium lathyroides, Caesalpinia pyramidalis and Mimosa tenuiflora hays were collected in Rio Grande do Norte Stated, during 2011 rainy season. The analyses: dry matter (DM, crude protein (CP mineral matter (MM ether extract  (EE neutral detergent fiber (NDF, acid detergent fiber (ADF, lignin (LIG, insoluble neutral detergent nitrogen, (INDN insoluble acid detergent nitrogen, (ADIN, total phenol (TF and total tannin (TT were done at Embrapa Caprinos e Ovinos in Ceará State. Plants analyzed, as expected, for tropical species, exhibited high level of cell wall constituents, high lignifications rate and revealed substantial presence of anti nutritional compounds. However, regardless of this data, the main problem, for grazing animals, is due to its xerophytes characteristics. Most of the shrubs and trees are deciduous, losing its leaves during the dry season. In addition, herbaceous presents a very rapid lifetime cycle, germinating and senescing during the brief wet season.

Black hole phase transitions and the chemical potential

Energy Technology Data Exchange (ETDEWEB)

Maity, Reevu, E-mail: reevum@iitk.ac.in; Roy, Pratim, E-mail: proy@iitk.ac.in; Sarkar, Tapobrata, E-mail: tapo@iitk.ac.in

2017-02-10

In the context of black hole thermodynamics and the AdS–CFT correspondence, we consider the chemical potential (μ) dual to the number of colours (N) of the boundary gauge theory, in the grand canonical ensemble. By appropriately defining μ via densities of thermodynamic quantities, we show that it changes sign precisely at the Hawking–Page transition for AdS–Schwarzschild and RN–AdS black holes in five dimensions, signalling the onset of quantum effects at the transition point. Such behaviour is absent for non-rotating black holes in four dimensions. For Kerr–AdS black holes in four and five dimensions, our analysis points to the fact that μ can change sign in the stable black hole region, i.e. above the Hawking–Page transition temperature, for a range of angular frequencies. We also analyse AdS black holes in five dimensional Gauss–Bonnet gravity, and find similar features for μ as in the Kerr–AdS case.

Black hole phase transitions and the chemical potential

Directory of Open Access Journals (Sweden)

Reevu Maity

2017-02-01

Full Text Available In the context of black hole thermodynamics and the AdS–CFT correspondence, we consider the chemical potential (μ dual to the number of colours (N of the boundary gauge theory, in the grand canonical ensemble. By appropriately defining μ via densities of thermodynamic quantities, we show that it changes sign precisely at the Hawking–Page transition for AdS–Schwarzschild and RN–AdS black holes in five dimensions, signalling the onset of quantum effects at the transition point. Such behaviour is absent for non-rotating black holes in four dimensions. For Kerr–AdS black holes in four and five dimensions, our analysis points to the fact that μ can change sign in the stable black hole region, i.e. above the Hawking–Page transition temperature, for a range of angular frequencies. We also analyse AdS black holes in five dimensional Gauss–Bonnet gravity, and find similar features for μ as in the Kerr–AdS case.

Robust determination of the chemical potential in the pole expansion and selected inversion method for solving Kohn-Sham density functional theory

Science.gov (United States)

Jia, Weile; Lin, Lin

2017-10-01

Fermi operator expansion (FOE) methods are powerful alternatives to diagonalization type methods for solving Kohn-Sham density functional theory (KSDFT). One example is the pole expansion and selected inversion (PEXSI) method, which approximates the Fermi operator by rational matrix functions and reduces the computational complexity to at most quadratic scaling for solving KSDFT. Unlike diagonalization type methods, the chemical potential often cannot be directly read off from the result of a single step of evaluation of the Fermi operator. Hence multiple evaluations are needed to be sequentially performed to compute the chemical potential to ensure the correct number of electrons within a given tolerance. This hinders the performance of FOE methods in practice. In this paper, we develop an efficient and robust strategy to determine the chemical potential in the context of the PEXSI method. The main idea of the new method is not to find the exact chemical potential at each self-consistent-field (SCF) iteration but to dynamically and rigorously update the upper and lower bounds for the true chemical potential, so that the chemical potential reaches its convergence along the SCF iteration. Instead of evaluating the Fermi operator for multiple times sequentially, our method uses a two-level strategy that evaluates the Fermi operators in parallel. In the regime of full parallelization, the wall clock time of each SCF iteration is always close to the time for one single evaluation of the Fermi operator, even when the initial guess is far away from the converged solution. We demonstrate the effectiveness of the new method using examples with metallic and insulating characters, as well as results from ab initio molecular dynamics.

Bulk and shear viscosities of hot and dense hadron gas

International Nuclear Information System (INIS)

Kadam, Guru Prakash; Mishra, Hiranmaya

2015-01-01

We estimate the bulk and the shear viscosity at finite temperature and baryon densities of hadronic matter within a hadron resonance gas model which includes a Hagedorn spectrum. The parameters of the Hagedorn spectrum are adjusted to fit recent lattice QCD simulations at finite chemical potential. For the estimation of the bulk viscosity we use low energy theorems of QCD for the energy momentum tensor correlators. For the shear viscosity coefficient, we estimate the same using molecular kinetic theory to relate the shear viscosity coefficient to average momentum of the hadrons in the hot and dense hadron gas. The bulk viscosity to entropy ratio increases with chemical potential and is related to the reduction of velocity of sound at nonzero chemical potential. The shear viscosity to entropy ratio on the other hand, shows a nontrivial behavior with the ratio decreasing with chemical potential for small temperatures but increasing with chemical potential at high temperatures and is related to decrease of entropy density with chemical potential at high temperature due to finite volume of the hadrons

Integrability of Hamiltonian systems with homogeneous potentials of degree zero

Energy Technology Data Exchange (ETDEWEB)

Casale, Guy, E-mail: guy.casale@univ-rennes1.f [IRMAR UMR 6625, Universite de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex (France); Duval, Guillaume, E-mail: dduuvvaall@wanadoo.f [1 Chemin du Chateau, 76 430 Les Trois Pierres (France); Maciejewski, Andrzej J., E-mail: maciejka@astro.ia.uz.zgora.p [Institute of Astronomy, University of Zielona Gora, Licealna 9, PL-65-417 Zielona Gora (Poland); Przybylska, Maria, E-mail: Maria.Przybylska@astri.uni.torun.p [Torun Centre for Astronomy, N. Copernicus University, Gagarina 11, PL-87-100 Torun (Poland)

2010-01-04

We derive necessary conditions for integrability in the Liouville sense of classical Hamiltonian systems with homogeneous potentials of degree zero. We obtain these conditions through an analysis of the differential Galois group of variational equations along a particular solution generated by a non-zero solution d element of C{sup n} of nonlinear equation gradV(d)=d. We prove that when the system is integrable the Hessian matrix V{sup ''}(d) has only integer eigenvalues and is diagonalizable.

Computed Potential Energy Surfaces and Minimum Energy Pathways for Chemical Reactions

Science.gov (United States)

Walch, Stephen P.; Langhoff, S. R. (Technical Monitor)

1994-01-01

Computed potential energy surfaces are often required for computation of such parameters as rate constants as a function of temperature, product branching ratios, and other detailed properties. For some dynamics methods, global potential energy surfaces are required. In this case, it is necessary to obtain the energy at a complete sampling of all the possible arrangements of the nuclei, which are energetically accessible, and then a fitting function must be obtained to interpolate between the computed points. In other cases, characterization of the stationary points and the reaction pathway connecting them is sufficient. These properties may be readily obtained using analytical derivative methods. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method to obtain accurate energetics, gives usefull results for a number of chemically important systems. The talk will focus on a number of applications including global potential energy surfaces, H + O2, H + N2, O(3p) + H2, and reaction pathways for complex reactions, including reactions leading to NO and soot formation in hydrocarbon combustion.

Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

Science.gov (United States)

Wedege, Kristina; Dražević, Emil; Konya, Denes; Bentien, Anders

2016-01-01

Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined with single cell battery RFB tests on selected redox pairs. Data shows that both the solubility and redox potential are determined by the position of the side groups and only to a small extent by the number of side groups. Additionally, the chemical stability and possible degradation mechanisms leading to capacity loss over time are discussed. The main challenge for the development of all-organic RFBs is to identify a redox pair for the positive side with sufficiently high stability and redox potential that enables battery cell potentials above 1 V. PMID:27966605

Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

Science.gov (United States)

Wedege, Kristina; Dražević, Emil; Konya, Denes; Bentien, Anders

2016-12-01

Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined with single cell battery RFB tests on selected redox pairs. Data shows that both the solubility and redox potential are determined by the position of the side groups and only to a small extent by the number of side groups. Additionally, the chemical stability and possible degradation mechanisms leading to capacity loss over time are discussed. The main challenge for the development of all-organic RFBs is to identify a redox pair for the positive side with sufficiently high stability and redox potential that enables battery cell potentials above 1 V.

Classical orbits in power-law potentials

International Nuclear Information System (INIS)

Grant, A.K.; Rosner, J.L.

1994-01-01

The motion of bodies in power-law potentials of the form V(r)=λr α has been of interest ever since the time of Newton and Hooke. Aspects of the relation between powers α and bar α, where (α+2)(bar α+2)=4, are derived for classical motion and the relation to the quantum-mechanical problem is given. An improvement on a previous expression for the WKB quantization condition for nonzero orbital angular momenta is obtained. Relations with previous treatments, such as those of Newton, Bertrand, Bohlin, Faure, and Arnold, are noted, and a brief survey of the literature on the problem over more than three centuries is given

The calculation of electron chemical potential and ion charge state and their influence on plasma conductivity in electrical explosion of metal wire

International Nuclear Information System (INIS)

Shi, Zongqian; Wang, Kun; Li, Yao; Shi, Yuanjie; Wu, Jian; Jia, Shenli

2014-01-01

The electron chemical potential and ion charge state (average ion charge and ion distribution) are important parameters in calculating plasma conductivity in electrical explosion of metal wire. In this paper, the calculating method of electron chemical potential and ion charge state is discussed at first. For the calculation of electron chemical potential, the ideal free electron gas model and Thomas-Fermi model are compared and analyzed in terms of the coupling constant of plasma. The Thomas-Fermi ionization model, which is used to calculate ion charge state, is compared with the method based on Saha equation. Furthermore, the influence of electron degenerated energy levels and ion excited states in Saha equation on the ion charge state is also analyzed. Then the influence of different calculating methods of electron chemical potential and ion charge state on plasma conductivity is discussed by applying them in the Lee-More conductivity model

Recent Progress in Molecular Simulation of Aqueous Electrolytes: Force Fields, Chemical Potentials and Solubility.

Czech Academy of Sciences Publication Activity Database

Nezbeda, Ivo; Moučka, F.; Smith, W.R.

2016-01-01

Roč. 114, č. 11 (2016), s. 1665-1690 ISSN 0026-8976 R&D Projects: GA ČR GA15-19542S Grant - others:NSERC(CA) OGP1041 Institutional support: RVO:67985858 Keywords : force fields * chemical potentials * aqueous electrolytes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.870, year: 2016

Magnetic properties of four dimensional fermions

Science.gov (United States)

Bergman, Oren; Lifschytz, Gilad; Lippert, Matthew

2013-12-01

We investigate the Sakai-Sugimoto model at nonzero baryon chemical potential in a background magnetic field in the chiral symmetric phase. We find that a new form of baryonic matter shows up, and we investigate its properties. We find a generated axial current, a reduction in the amount of charge participating in dissipative interactions and a metamagnetic like phase transition at low temperature.

Relativistic total energy and chemical potential of heavy atoms and positive ions

International Nuclear Information System (INIS)

Hill, S.H.; Grout, P.J.; March, N.H.

1984-01-01

The relativistic Thomas-Fermi theory, with a finite nucleus, is used to study the variation of the chemical potential μ with atomic number Z and number of electrons N (N <= Z). The difference between the total energy of positive ions and that of the corresponding neutral atom has been obtained. The scaling predictions are confirmed by numerical calculations. The first principles calculation of the relativistic Thomas-Fermi total energy of neutral atoms is also studied. (author)

Poisoning following exposure to chemicals stored in mislabelled or unlabelled containers: a recipe for potential disaster.

Science.gov (United States)

Millard, Yvette C; Slaughter, Robin J; Shieffelbien, Lucy M; Schep, Leo J

2014-09-26

To investigate poisoning exposures to chemicals that were unlabelled, mislabelled or not in their original containers in New Zealand over the last 10 years, based on calls to the New Zealand National Poisons Centre (NZNPC). Call data from the NZNPC between 2003 and 2012 were analysed retrospectively. Parameters reviewed included patient age, route and site of exposure, product classification and recommended intervention. Of the 324,411 calls received between 2003 and 2012, 100,465 calls were associated with acute human exposure to chemicals. There were 757 inquiries related to human exposure to mislabelled or unlabelled chemicals consisting of 0.75% of chemical exposures. Adults were involved in 51% of incidents, children, containers is a problem for all age groups. Although it represents a small proportion of total calls to the NZNPC it remains a potential risk for serious poisoning. It is important that chemicals are stored securely, in their original containers, and never stored in drinking vessels.

Massive Gross-Neveu model in the leading order of the 1/N expansion. Allowance for the temperature and the chemical potential

International Nuclear Information System (INIS)

Klimenko, K.G.

1988-01-01

The massive Gross-Neveu model is treated self-consistently in the leading order of the 1/N expansion. The properties of the model when the temperature and the chemical potential are included are studied. It is shown that there exists a critical value of the chemical potential at which the effective mass of the fermion abruptly changes its value

Chemical composition of the thermomineral waters of Josanicka Banja spa as an origin indicator, balneological valorization and geothermal potential

Directory of Open Access Journals (Sweden)

Milenić Dejan R.

2015-01-01

Full Text Available The chemical composition of the groundwater is directly dependent on the geological structure, hydrogeological and hydrochemical characteristics and as such it represents an output result of all the factors and processes which take place in the environment within which they were formed. The chemical composition of thermomineral waters often represents a crucial factor in determining the origin, balneological valorization and geothermal potential of the resources. This work presents the analysis of origin, belneological valorization and geothermal potential of Josanicka Banja spa, on the basis of the results gained through making the analyisis of chemical contents of the thermomineral waters which occur in the area. The ratio of concentrations of specific chemical components in the thermomineral waters of Josanicka Banja has served as the basic tool for ascertaining the origin of these waters. On the basis of the analysis of the main anion-cation and gas compositions as well as the contents of specific micro-components, a balneological valorization of these resources has been carried out. Apart from that this work also presents the calculation of the expected temperatures in the primary geothermal reservoir, which was carried out on the basis of the results of chemical analysis of thermomineral waters that occur in the area. Geothermal potential of about 4 MWt and significant contents of balneologically active components of the chemical composition of these waters, open up a possibility for their multi-purpose use, which is also presented in the work. [Projekat Ministarstva nauke Republike Srbije, br. TR 33053

Gauge-invariant screening masses and static quark free energies in Nf=2 +1 QCD at nonzero baryon density

Science.gov (United States)

Andreoli, Michele; Bonati, Claudio; D'Elia, Massimo; Mesiti, Michele; Negro, Francesco; Rucci, Andrea; Sanfilippo, Francesco

2018-03-01

We discuss the extension of gauge-invariant electric and magnetic screening masses in the quark-gluon plasma to the case of a finite baryon density, defining them in terms of a matrix of Polyakov loop correlators. We present lattice results for Nf=2 +1 QCD with physical quark masses, obtained using the imaginary chemical potential approach, which indicate that the screening masses increase as a function of μB. A separate analysis is carried out for the theoretically interesting case μB/T =3 i π , where charge conjugation is not explicitly broken and the usual definition of the screening masses can be used for temperatures below the Roberge-Weiss transition. Finally, we investigate the dependence of the static quark free energy on the baryon chemical potential, showing that it is a decreasing function of μB, which displays a peculiar behavior as the pseudocritical transition temperature at μB=0 is approached.

Finite temperature and chemical potential in lattice QCD and its critical point

International Nuclear Information System (INIS)

Fodor, Z.

2002-01-01

We propose a method to study lattice QCD at finite temperature (T) and chemical potential (μ). We compare the method with direct results and with the Glasgow method by using n f =4 QCD at Im(μ)≠0. We locate the critical endpoint (E) of QCD on the Re(μ)-T plane. We use n f =2+1 dynamical staggered quarks with semi-realistic masses on L t =4 lattices. Our results are based on O(10 3 - 10 4 ) configurations. (orig.)

Complete orthonormal sets on the past light cone - II: Functions belonging to spin 1/2 and non-zero rest mass

International Nuclear Information System (INIS)

Derrick, G.H.

1987-12-01

This is the second of a series of papers preparing the mathematical framework for a past light cone formulation for the quantum mechanics of particles of arbitrary mass and spin. The aim of past light cone quantum theory is to define quantum states solely in terms of data accessible to an observer, i.e. information from within his current past light cone. In order to set up such a theory one needs to define on the past light cone complete orthonormal sets of functions which belong to the appropriate representation of the Poincare group. Such functions are interpreted as energy-momentum eigenfunctions. The present paper treats the case of spin 1/2 and non-zero rest mass. (author). 7 refs

A QCD chiral critical point at small chemical potential: is it there or not?

CERN Document Server

de Forcrand, Philippe; Philipsen, Owe

2007-01-01

For a QCD chiral critical point to exist, the parameter region of small quark masses for which the finite temperature transition is first-order must expand when the chemical potential is turned on. This can be tested by a Taylor expansion of the critical surface (m_{u,d},m_s)_c(mu). We present a new method to perform this Taylor expansion numerically, which we first test on an effective model of QCD with static, dense quarks. We then present the results for QCD with 3 degenerate flavors. For a lattice with N_t=4 time-slices, the first-order region shrinks as the chemical potential is turned on. This implies that, for physical quark masses, the analytic crossover which occurs at mu=0 between the hadronic and the plasma regimes remains crossover in the mu-region where a Taylor expansion is reliable, i.e. mu less than or similar to T. We present preliminary results from finer lattices indicating that this situation persists, as does the discrepancy between the curvature of T_c(mu) and the experimentally observed...

Chemical analyses of wasp-associated streptomyces bacteria reveal a prolific potential for natural products discovery.

Directory of Open Access Journals (Sweden)

Michael Poulsen

2011-02-01

Full Text Available Identifying new sources for small molecule discovery is necessary to help mitigate the continuous emergence of antibiotic-resistance in pathogenic microbes. Recent studies indicate that one potentially rich source of novel natural products is Actinobacterial symbionts associated with social and solitary Hymenoptera. Here we test this possibility by examining two species of solitary mud dauber wasps, Sceliphron caementarium and Chalybion californicum. We performed enrichment isolations from 33 wasps and obtained more than 200 isolates of Streptomyces Actinobacteria. Chemical analyses of 15 of these isolates identified 11 distinct and structurally diverse secondary metabolites, including a novel polyunsaturated and polyoxygenated macrocyclic lactam, which we name sceliphrolactam. By pairing the 15 Streptomyces strains against a collection of fungi and bacteria, we document their antifungal and antibacterial activity. The prevalence and anti-microbial properties of Actinobacteria associated with these two solitary wasp species suggest the potential role of these Streptomyces as antibiotic-producing symbionts, potentially helping defend their wasp hosts from pathogenic microbes. Finding phylogenetically diverse and chemically prolific Actinobacteria from solitary wasps suggests that insect-associated Actinobacteria can provide a valuable source of novel natural products of pharmaceutical interest.

BULK THERMODYNAMICS AND CHARGE FLUCTUATIONS AT NON-VANISHING BARYON DENSITY

International Nuclear Information System (INIS)

MIAO, C.; SCHMIDT, C.

2007-01-01

We present results on bulk thermodynamic quantities as well as net baryon number, strangeness and electric charge fluctuations in QCD at non-zero density and temperature obtained from lattice calculations with almost physical quark masses for two values of the lattice cut-off aT = 1/4 and 1/6. We show that with our improved p4fa3-action the cut-off effects are under control when using lattices with a temporal extent of 6 or larger and that the contribution to the equation of state, which is due to a finite chemical potential is small for μ q /T < 1. Moreover, at vanishing chemical potential, i.e. under conditions almost realized at RHIC and the LHC, quartic fluctuations of net baryon number and strangeness are large in a narrow temperature interval characterizing the transition region from the low to high temperature phase. At non-zero baryon number density, strangeness fluctuations are enhanced and correlated to fluctuations of the net baryon number. If strangeness is furthermore forced to vanish, as it may be the case in systems created in heavy ion collisions, strangeness fluctuations are significantly smaller than baryon number fluctuations

Potential for MERLIN-Expo, an advanced tool for higher tier exposure assessment, within the EU chemical legislative frameworks

International Nuclear Information System (INIS)

Suciu, Nicoleta; Tediosi, Alice; Ciffroy, Philippe; Altenpohl, Annette; Brochot, Céline; Verdonck, Frederik; Ferrari, Federico; Giubilato, Elisa; Capri, Ettore; Fait, Gabriella

2016-01-01

MERLIN-Expo merges and integrates advanced exposure assessment methodologies, allowing the building of complex scenarios involving several pollution sources and targets. The assessment of exposure and risks to human health from chemicals is of major concern for policy and ultimately benefits all citizens. The development and operational fusion of the advanced exposure assessment methodologies envisaged in the MERLIN-Expo tool will have a significant impact in the long term on several policies dealing with chemical safety management. There are more than 30 agencies in Europe related to exposure and risk evaluation of chemicals, which have an important role in implementing EU policies, having especially tasks of technical, scientific, operational and/or regulatory nature. The main purpose of the present paper is to introduce MERLIN-Expo and to highlight its potential for being effectively integrated within the group of tools available to assess the risk and exposure of chemicals for EU policy. The main results show that the tool is highly suitable for use in site-specific or local impact assessment, with minor modifications it can also be used for Plant Protection Products (PPPs), biocides and REACH, while major additions would be required for a comprehensive application in the field of consumer and worker exposure assessment. - Highlights: • Exposure and risk evaluation of chemicals • Coupling environmental exposure and pharmacokinetic models • MERLIN-expo as a higher tier exposure tool • MERLIN-expo potential application in EU chemical regulations • EU legislations and policies related to risk assessment and management of chemicals

Potential for MERLIN-Expo, an advanced tool for higher tier exposure assessment, within the EU chemical legislative frameworks

Energy Technology Data Exchange (ETDEWEB)

Suciu, Nicoleta, E-mail: nicoleta.suciu@unicatt.it [Università Cattolica del Sacro Cuore, 29122 Piacenza (Italy); Tediosi, Alice [Aeiforia Srl, 29027 Gariga di Podenzano (PC) (Italy); Ciffroy, Philippe [Electricité de France (EDF) R& D, National Hydraulic and Environment Laboratory, 6 quai Watier, 78400 Chatou (France); Altenpohl, Annette [Österreichisches Normungsinstitut/Austrian Standards Institute, Heinestraße 38, 1020 Wien (Austria); Brochot, Céline [INERIS, Parc ALATA, BP2, 60550 Verneuil en Halatte (France); Verdonck, Frederik [ARCHE cvba, Liefkensstraat 35d, 9032 Gent-Wondelgem (Belgium); Ferrari, Federico [Aeiforia Srl, 29027 Gariga di Podenzano (PC) (Italy); Giubilato, Elisa [University Ca Foscari Venice, Department of Environmental Sciences, Informatics and Statistics, via Torino 155, 30172 Mestre-Venice (Italy); Capri, Ettore [Università Cattolica del Sacro Cuore, 29122 Piacenza (Italy); Fait, Gabriella [EFSA, via Carlo Magno 1/a, 43126 Parma (Italy)

2016-08-15

MERLIN-Expo merges and integrates advanced exposure assessment methodologies, allowing the building of complex scenarios involving several pollution sources and targets. The assessment of exposure and risks to human health from chemicals is of major concern for policy and ultimately benefits all citizens. The development and operational fusion of the advanced exposure assessment methodologies envisaged in the MERLIN-Expo tool will have a significant impact in the long term on several policies dealing with chemical safety management. There are more than 30 agencies in Europe related to exposure and risk evaluation of chemicals, which have an important role in implementing EU policies, having especially tasks of technical, scientific, operational and/or regulatory nature. The main purpose of the present paper is to introduce MERLIN-Expo and to highlight its potential for being effectively integrated within the group of tools available to assess the risk and exposure of chemicals for EU policy. The main results show that the tool is highly suitable for use in site-specific or local impact assessment, with minor modifications it can also be used for Plant Protection Products (PPPs), biocides and REACH, while major additions would be required for a comprehensive application in the field of consumer and worker exposure assessment. - Highlights: • Exposure and risk evaluation of chemicals • Coupling environmental exposure and pharmacokinetic models • MERLIN-expo as a higher tier exposure tool • MERLIN-expo potential application in EU chemical regulations • EU legislations and policies related to risk assessment and management of chemicals.

A study of the potential of plasma processing in the chemical industry

International Nuclear Information System (INIS)

Estey, P.N.; Connolly, T.J.

1984-01-01

This work describes a systematic approach to determine the potential for plasma processing in the United States chemical industry. A model was developed that describes the physical inputs and outputs from a plasma based processing system. Based on these mass flows and the energy flows to the processor an economic assessment of the plasma processing system is made. This economic assessment which also includes the capital costs of the processor, can be used to determine if the plasma system is competitive with the conventional system

Therapeutic Potential of Foldamers: From Chemical Biology Tools To Drug Candidates?

Science.gov (United States)

Gopalakrishnan, Ranganath; Frolov, Andrey I; Knerr, Laurent; Drury, William J; Valeur, Eric

2016-11-10

Over the past decade, foldamers have progressively emerged as useful architectures to mimic secondary structures of proteins. Peptidic foldamers, consisting of various amino acid based backbones, have been the most studied from a therapeutic perspective, while polyaromatic foldamers have barely evolved from their nascency and remain perplexing for medicinal chemists due to their poor drug-like nature. Despite these limitations, this compound class may still offer opportunities to study challenging targets or provide chemical biology tools. The potential of foldamer drug candidates reaching the clinic is still a stretch. Nevertheless, advances in the field have demonstrated their potential for the discovery of next generation therapeutics. In this perspective, the current knowledge of foldamers is reviewed in a drug discovery context. Recent advances in the early phases of drug discovery including hit finding, target validation, and optimization and molecular modeling are discussed. In addition, challenges and focus areas are debated and gaps highlighted.

Generalization of Penrose's helicity theorem for space-times with nonzero dual mass

International Nuclear Information System (INIS)

Magnon, A.

1986-01-01

An algebraic definition of the helicity operator H is proposed for vacuum stationary and asymptotically flat wormholes (i.e., space-times where the manifold of orbits of the stationary Killing field has S 2 x R topology). The definition avoids the use of momentum space or Fourier decomposition of the gravitational degrees of freedom into positive and negative frequency parts, and is essentially geared to emphasize the role of nontrivial topology. It is obtained via the introduction of a total spin vector S/sup α/ derived from the dual Bondi four-momentum *P/sup α/, both vectors originating in the presence of nontrivial homotopy groups. (Space-times with nonzero dual mass can be characterized by a conformal null boundary I having the topology of an S 1 fiber bundle over S 2 with possible identifications along the fiber: lens space: or equivalently vanishing Bondi--News.) It is shown that S/sup α/ is a constant multiple of P/sup α/, the total Bondi four-momentum, and if in addition the space-time admits a point at spacelike infinity, there is strong support for the past limit of S/sup α/ to be a null vector. This can be viewed as a generalization of Penrose's result on the Pauli--Lubanski vector for classical zero rest-mass particles. The helicity operator at null infinity is rooted in the topology and turns out to be essentially the Hodge duality operator(*). The notion of duality appears as a global concept. Under such conditions, self- and anti-self-dual modes of the Weyl curvature could be viewed as states originating in the nontrivial topology

Chemical compositions and antimicrobial potential of Actinodaphne macrophylla leaves oils from East Kalimantan

Science.gov (United States)

Putri, A. S.; Purba, F. F.; Kusuma, I. W.; Kuspradini, H.

2018-04-01

Essential oils producing plants comprises about 160-200 species, one of which belongs to Lauraceae family. Actinodaphne macrophylla is a plant of the Lauraceae family and widely spread on Kalimantan island. For humans, essential oils are used in cosmetics industry, food industry, and pharmaceutical industry. This research aimed to analyze the characteristics of essential oil and potential of antimicrobial activity from A. macrophylla leaves oils. Essential oils were obtained by steam distillation method. Antimicrobial activity was assayed using agar diffusion method which compared with two synthetic standards including chlorhexidine and chloramphenicol. Four microorganisms were used in this study were Candida albicans, Staphylococcus aureus, Streptococcus mutans, and Streptococcus sobrinus. The obtained oil was determined for its characteristics including the yield, refractive index, and chemical components. The attained components were analyzed using GC-MS. The results of this study showed that essential oils of A. macrophylla leaves contained 0.1051% of yield, clearless, and refractive index was 1.425. Based on GC-MS analysis result, it showed chemical components including spathulenol, 2-monopalmitin, (+)-sabinene, copaen, camphene, and β-pinene. This plant potentially can inhibit the growth of S. aureus, C. albicans, S. sobrinus, and S. mutans with inhibition zones of 17.22, 20.89, 22.34 and 22.89 mm, respectively.

Understanding chemical-potential-related transient pore-pressure response to improve real-time borehole (in)stability predictions

Energy Technology Data Exchange (ETDEWEB)

Tare, U. A.; Mody, F. K.; Mese, A. I. [Haliburton Energy Services, TX (United States)

2002-07-01

In order to develop a real-time wellbore (in)stability modelling capability, experimental work was carried out to investigate the role of the chemical potential of drilling fluids on transient pore pressure and time-dependent rock property alterations of shale formations. Time-dependent alterations in the pore pressure, acoustic and rock properties of formations subjected to compressive tri-axial test were recorded during the experiments involving the Pore Pressure Transmission (PPT) test. Based on the transient pore pressure of shale exposed to the test fluid presented here, the 20 per cent calcium chloride showed a very low membrane efficiency of 4.45 per cent. The need for a thorough understanding of the drilling fluid/shale interaction prior to applying any chemical potential wellbore (in)stability model to real-time drilling operations was emphasized. 9 refs., 5 figs.

Plant cell tissue culture: A potential source of chemicals

Energy Technology Data Exchange (ETDEWEB)

Scott, C.D.; Dougall, D.K.

1987-08-01

Higher plants produce many industrially important products. Among these are drugs and medicinal chemicals, essential oils and flavors, vegetable oils and fats, fine and specialty chemicals, and even some commodity chemicals. Although, currently, whole-plant extraction is the primary means of harvesting these materials, the advent of plant cell tissue culture could be a much more effective method of producing many types of phytochemicals. The use of immobilized plant cells in an advanced bioreactor configuration with excretion of the product into the reactor medium may represent the most straightforward way of commercializing such techniques for lower-value chemicals. Important research and development opportunities in this area include screening for plant cultures for nonmedical, lower-value chemicals; understanding and controlling plant cell physiology and biochemistry; optimizing effective immobilization methods; developing more efficient bioreactor concepts; and perfecting product extraction and purification techniques. 62 refs., 2 figs.

Current-current correlation function in presence of chemical potential and external magnetic field

International Nuclear Information System (INIS)

Apresyan, E.A.

2017-01-01

The (2+1)-dimensional electron system was observed, where relation between the Green functions and conductivity was used. The current-current correlation function Π_μ_ν(B) for the fermion system was calculated in presence of non-quantizing magnetic field B, chemical potential η and gap m. From this function it is possible to obtain the equation for polarization operator calculated without the magnetic field. The result is also applicable for graphene

SIMO optical wireless links with nonzero boresight pointing errors over M modeled turbulence channels

Science.gov (United States)

Varotsos, G. K.; Nistazakis, H. E.; Petkovic, M. I.; Djordjevic, G. T.; Tombras, G. S.

2017-11-01

Over the last years terrestrial free-space optical (FSO) communication systems have demonstrated an increasing scientific and commercial interest in response to the growing demands for ultra high bandwidth, cost-effective and secure wireless data transmissions. However, due the signal propagation through the atmosphere, the performance of such links depends strongly on the atmospheric conditions such as weather phenomena and turbulence effect. Additionally, their operation is affected significantly by the pointing errors effect which is caused by the misalignment of the optical beam between the transmitter and the receiver. In order to address this significant performance degradation, several statistical models have been proposed, while particular attention has been also given to diversity methods. Here, the turbulence-induced fading of the received optical signal irradiance is studied through the M (alaga) distribution, which is an accurate model suitable for weak to strong turbulence conditions and unifies most of the well-known, previously emerged models. Thus, taking into account the atmospheric turbulence conditions along with the pointing errors effect with nonzero boresight and the modulation technique that is used, we derive mathematical expressions for the estimation of the average bit error rate performance for SIMO FSO links. Finally, proper numerical results are given to verify our derived expressions and Monte Carlo simulations are also provided to further validate the accuracy of the analysis proposed and the obtained mathematical expressions.

Pore-scale modeling of vapor transport in partially saturated capillary tube with variable area using chemical potential

DEFF Research Database (Denmark)

Addassi, Mouadh; Schreyer, Lynn; Johannesson, Björn

2016-01-01

Here we illustrate the usefulness of using the chemical potential as the primary unknown by modeling isothermal vapor transport through a partially saturated cylindrically symmetric capillary tube of variable cross-sectional area using a single equation. There are no fitting parameters and the nu......Here we illustrate the usefulness of using the chemical potential as the primary unknown by modeling isothermal vapor transport through a partially saturated cylindrically symmetric capillary tube of variable cross-sectional area using a single equation. There are no fitting parameters...... and the numerical solutions to the equation are compared with experimental results with excellent agreement. We demonstrate that isothermal vapor transport can be accurately modeled without modeling the details of the contact angle, microscale temperature fluctuations, or pressure fluctuations using a modification...

Top Value Added Chemicals From Biomass: I. Results of Screening for Potential Candidates from Sugars and Synthesis Gas

Energy Technology Data Exchange (ETDEWEB)

Werpy, Todd A.; Holladay, John E.; White, James F.

2004-11-01

This report identifies twelve building block chemicals that can be produced from sugars via biological or chemical conversions. The twelve building blocks can be subsequently converted to a number of high-value bio-based chemicals or materials. Building block chemicals, as considered for this analysis, are molecules with multiple functional groups that possess the potential to be transformed into new families of useful molecules. The twelve sugar-based building blocks are 1,4-diacids (succinic, fumaric and malic), 2,5-furan dicarboxylic acid, 3-hydroxy propionic acid, aspartic acid, glucaric acid, glutamic acid, itaconic acid, levulinic acid, 3-hydroxybutyrolactone, glycerol, sorbitol, and xylitol/arabinitol. In addition to building blocks, the report outlines the central technical barriers that are preventing the widespread use of biomass for products and chemicals.

Potentiostatic current and galvanostatic potential oscillations during electrodeposition of cadmium.

Science.gov (United States)

López-Sauri, D A; Veleva, L; Pérez-Ángel, G

2015-09-14

Cathodic current and potential oscillations were observed during electrodeposition of cadmium from a cyanide electrolyte on a vertical platinum electrode, in potentiostatic and galvanostatic experiments. Electrochemical impedance spectroscopy experiments revealed a region of negative real impedance in a range of non-zero frequencies, in the second descending branch with a positive slope of the N-shape current-potential curve. This kind of dynamical behaviour is characteristic of the HN-NDR oscillators (oscillators with the N-Shape current-potential curve and hidden negative differential resistance). The oscillations could be mainly attributed to the changes in the real active cathodic area, due to the adsorption of hydrogen molecules and their detachment from the surface. The instabilities of the electrochemical processes were characterized by time series, Fast Fourier Transforms and 2-D phase portraits showing quasi-periodic oscillations.

Osmotic Pressure of Aqueous Electrolyte Solutions via Molecular Simulations of Chemical Potentials: Application to NaCl.

Czech Academy of Sciences Publication Activity Database

Smith, W.R.; Moučka, F.; Nezbeda, Ivo

2016-01-01

Roč. 407, Sl (2016), s. 76-83 ISSN 0378-3812 Grant - others:NSERC(CA) OGP1041 Institutional support: RVO:67985858 Keywords : osmotic pressure * chemical potential * molecular simulation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.473, year: 2016

The O(N) model at nonzero temperature: renormalization of the gap equations in Hartree and large-N approximations

International Nuclear Information System (INIS)

Lenaghan, J.T.; Rischke, D.H.

2000-01-01

The temperature dependence of the sigma meson and pion masses is studied in the framework of the O(N ) model. The Cornwall-Jackiw-Tomboulis formalism is applied to derive gap equations for the masses in the Hartree and large-N approximations. Renormalization of the gap equations is carried out within the cut-off and counter-term renormalization schemes. A consistent renormalization of the gap equations within the cut-off scheme is found to be possible only in the large-N approximation and for a finite value of the cut-off. On the other hand, the counter-term scheme allows for a consistent renormalization of both the large-N and Hartree approximations. In these approximations, the meson masses at a given nonzero temperature depend in general on the choice of the cut-off or renormalization scale. As an application, we also discuss the in-medium on-shell decay widths for sigma mesons and pions at rest. (author)

Biochemical methane potential, biodegradability, alkali treatment and influence of chemical composition on methane yield of yard wastes.

Science.gov (United States)

Gunaseelan, Victor Nallathambi

2016-03-01

In this study, the biochemical CH4 potential, rate, biodegradability, NaOH treatment and the influence of chemical composition on CH4 yield of yard wastes generated from seven trees were examined. All the plant parts were sampled for their chemical composition and subjected to the biochemical CH4 potential assay. The component parts exhibited significant variation in biochemical CH4 potential, which was reflected in their ultimate CH4 yields that ranged from 109 to 382 ml g(-1) volatile solids added and their rate constants that ranged from 0.042 to 0.173 d(-1). The biodegradability of the yard wastes ranged from 0.26 to 0.86. Variation in the biochemical CH4 potential of the yard wastes could be attributed to variation in the chemical composition of the different fractions. In the Thespesia yellow withered leaf, Tamarindus fruit pericarp and Albizia pod husk, NaOH treatment enhanced the ultimate CH4 yields by 17%, 77% and 63%, respectively, and biodegradability by 15%, 77% and 61%, respectively, compared with the untreated samples. The effectiveness of NaOH treatment varied for different yard wastes, depending on the amounts of acid detergent fibre content. Gliricidia petals, Prosopis leaf, inflorescence and immature pod, Tamarindus seeds, Albizia seeds, Cassia seeds and Delonix seeds exhibited CH4 yields higher than 300 ml g(-1) volatile solids added. Multiple linear regression models for predicting the ultimate CH4 yield and biodegradability of yard wastes were designed from the results of this work. © The Author(s) 2016.

Fluids in porous media. IV. Quench effect on chemical potential.

Science.gov (United States)

Qiao, C Z; Zhao, S L; Liu, H L; Dong, W

2017-06-21

It appears to be a common sense to measure the crowdedness of a fluid system by the densities of the species constituting it. In the present work, we show that this ceases to be valid for confined fluids under some conditions. A quite thorough investigation is made for a hard sphere (HS) fluid adsorbed in a hard sphere matrix (a quench-annealed system) and its corresponding equilibrium binary mixture. When fluid particles are larger than matrix particles, the quench-annealed system can appear much more crowded than its corresponding equilibrium binary mixture, i.e., having a much higher fluid chemical potential, even when the density of each species is strictly the same in both systems, respectively. We believe that the insight gained from this study should be useful for the design of functionalized porous materials.

On the chiral perturbation theory for two-flavor two-color QCD at finite chemical potential

Czech Academy of Sciences Publication Activity Database

Brauner, Tomáš

2006-01-01

Roč. 21, č. 7 (2006), s. 559-569 ISSN 0217-7323 R&D Projects: GA ČR(CZ) GD202/05/H003 Institutional research plan: CEZ:AV0Z10480505 Keywords : two-color QCD * chiral perturbation theory * chemical potential Subject RIV: BE - Theoretical Physics Impact factor: 1.564, year: 2006

A two-component wave equation for particles of spin 1/2 and non-zero rest mass

International Nuclear Information System (INIS)

Srivastava, T.

1981-11-01

We have discussed here the qualifications of the equation (delta 0 +sigmasup(k)deltasub(k))psi = -kappaTpsi, where deltasub(μ) is identical to delta/deltaxsup(μ), sigmasup(k) are the Pauli spin matrices, T is the linear operator which changes the sign of t, kappa=m 0 c/(h/2π) and psi a function with two components, as a suitable wave equation for a spin 1/2 particle with non-zero rest mass. We have established that both components of all its solutions satisfy the Klein-Gordon equation and that a 1-1 correspondence can be set up between its solutions and the positive energy solutions of the Dirac equation which preserves inner products (suitably defined for our case). We have then gone on to show covariance under transformations of the proper Lorentz group as also under space and time inversions and translations. Eigenfunctions of energy-momentum and spin have been explicitly found and it is shown that causality is preserved and a Green's function exists. A list appears, at the end, of points to be discussed in Part II of this paper, points which, it is hoped, will complete the acceptability of the theory. (author)

Endocrine-Disrupting Chemicals and Oil and Natural Gas Operations: Potential Environmental Contamination and Recommendations to Assess Complex Environmental Mixtures.

Science.gov (United States)

Kassotis, Christopher D; Tillitt, Donald E; Lin, Chung-Ho; McElroy, Jane A; Nagel, Susan C

2016-03-01

Hydraulic fracturing technologies, developed over the last 65 years, have only recently been combined with horizontal drilling to unlock oil and gas reserves previously deemed inaccessible. Although these technologies have dramatically increased domestic oil and natural gas production, they have also raised concerns for the potential contamination of local water supplies with the approximately 1,000 chemicals that are used throughout the process, including many known or suspected endocrine-disrupting chemicals. We discuss the need for an endocrine component to health assessments for drilling-dense regions in the context of hormonal and antihormonal activities for chemicals used. We discuss the literature on a) surface and groundwater contamination by oil and gas extraction operations, and b) potential human exposure, particularly in the context of the total hormonal and antihormonal activities present in surface and groundwater from natural and anthropogenic sources; we also discuss initial analytical results and critical knowledge gaps. In light of the potential for environmental release of oil and gas chemicals that can disrupt hormone receptor systems, we recommend methods for assessing complex hormonally active environmental mixtures. We describe a need for an endocrine-centric component for overall health assessments and provide information supporting the idea that using such a component will help explain reported adverse health trends as well as help develop recommendations for environmental impact assessments and monitoring programs.

A new cell-based method for assessing the eye irritation potential of chemicals: an alternative to the Draize test.

Science.gov (United States)

Cho, Sun-A; An, Susun; Lee, Eunyoung; Shin, Kyeho; Cho, Jun-Cheol; Lee, Tae Ryong

2012-07-20

Using a human corneal cell line (HCE-T cells) and 2 evaluation criteria, we developed a new alternative method to assess the eye irritation potential of chemicals. We exposed HCE-T cells to different concentrations of 38 chemicals for 1h and measured relative cell viability (RCV) as an endpoint at each concentration. Using the RCV values, we calculated the RCV50. We also exposed HCE-T cells to 3 fixed concentrations of the 38 chemicals (5%, 0.5%, and 0.05%) for 1h and measured the RCV at each concentration. Using the RCV values at 5%, 0.5%, and 0.05%, we developed a new criterion for eye irritation potential (total eye irritation score, TEIS) and estimated the ocular irritancy. We then assessed the correlation of the results of RCV50 and TEIS with those of the Draize rabbit eye irritation. Both the RCV50 and TEIS results exhibited good positive correlations (sensitivity: 80.77%, specificity: 83.33%, and accuracy: 81.58% for TEIS; sensitivity: 73.08-76.92%, specificity: 75.00%, and accuracy: 73.68-76.32% for RCV50). We conclude that the new in vitro model using HCE-T cells is a good alternative evaluation model for the prediction of the eye irritation potential of chemicals. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Endocrine-disrupting chemicals and oil and natural gas operations: Potential environmental contamination and recommendations to assess complex environmental mixtures

Science.gov (United States)

Kassotis, Christopher D.; Tillitt, Donald E.; Lin, Chung-Ho; McElroy, Jane A.; Nagel, Susan C.

2016-01-01

Background: Hydraulic fracturing technologies, developed over the last 65 years, have only recently been combined with horizontal drilling to unlock oil and gas reserves previously deemed inaccessible. While these technologies have dramatically increased domestic oil and natural gas production, they have also raised concerns for the potential contamination of local water supplies with the approximately 1,000 chemicals used throughout the process, including many known or suspected endocrine-disrupting chemicals.Objectives: We discuss the need for an endocrine component to health assessments for drilling-dense regions in the context of hormonal and anti-hormonal activities for chemicals used.Methods: We discuss the literature on 1) surface and ground water contamination by oil and gas extraction operations, and 2) potential human exposure, particularly in context of the total hormonal and anti-hormonal activities present in surface and ground water from natural and anthropogenic sources, with initial analytical results and critical knowledge gaps discussed.Discussion: In light of the potential for environmental release of oil and gas chemicals that can disrupt hormone receptor systems, we recommend methods for assessing complex hormonally active environmental mixtures.Conclusions: We describe a need for an endocrine-centric component for overall health assessments and provide supporting information that using this may help explain reported adverse health trends as well as help develop recommendations for environmental impact assessments and monitoring programs.

Chemical analysis and potential health risks of hookah charcoal

Energy Technology Data Exchange (ETDEWEB)

Elsayed, Yehya, E-mail: yelsayed@aus.edu; Dalibalta, Sarah, E-mail: sdalibalta@aus.edu; Abu-Farha, Nedal

2016-11-01

Hookah (waterpipe) smoking is a very common practice that has spread globally. There is growing evidence on the hazardous consequences of smoking hookah, with studies indicating that its harmful effects are comparable to cigarette smoking if not worse. Charcoal is commonly used as a heating source for hookah smoke. Although charcoal briquettes are thought to be one of the major contributors to toxicity, their composition and impact on the smoke generated remains largely unidentified. This study aims to analyze the elemental composition of five different raw synthetic and natural charcoals by using Carbon-Hydrogen-Nitrogen (CHN) analysis, inductively coupled plasma (ICP), and scanning electron microscopy coupled with energy dispersive X-Ray spectrometry (SEM-EDS). Elemental analysis showed that the raw charcoals contain heavy metals such as zinc, iron, cadmium, vanadium, aluminum, lead, chromium, manganese and cobalt at concentrations similar, if not higher than, cigarettes. In addition, thermal desorption-gas chromatography–mass spectrometry (TD-GC–MS) was used to analyze the chemical composition of the smoke produced from burning the charcoal samples. The smoke emitted from charcoal was found to be the source of numerous compounds which could be hazardous to health. A total of seven carcinogens, 39 central nervous system depressants and 31 respiratory irritants were identified. - Highlights: • Hookah charcoals, mainly synthetic brands, contains trace/heavy metals in concentrations exceeding those in cigarettes. • The concentration of lead in synthetic charcoal briquettes may impose adverse effects on human health. • The amount of nitrogen in synthetic charcoal is comparable to that reported in cigarettes. • Chemical profiling of smoke emitted from hookah charcoal reveals many compounds associated with potential health risks.

Chemical analysis and potential health risks of hookah charcoal

International Nuclear Information System (INIS)

Elsayed, Yehya; Dalibalta, Sarah; Abu-Farha, Nedal

2016-01-01

Hookah (waterpipe) smoking is a very common practice that has spread globally. There is growing evidence on the hazardous consequences of smoking hookah, with studies indicating that its harmful effects are comparable to cigarette smoking if not worse. Charcoal is commonly used as a heating source for hookah smoke. Although charcoal briquettes are thought to be one of the major contributors to toxicity, their composition and impact on the smoke generated remains largely unidentified. This study aims to analyze the elemental composition of five different raw synthetic and natural charcoals by using Carbon-Hydrogen-Nitrogen (CHN) analysis, inductively coupled plasma (ICP), and scanning electron microscopy coupled with energy dispersive X-Ray spectrometry (SEM-EDS). Elemental analysis showed that the raw charcoals contain heavy metals such as zinc, iron, cadmium, vanadium, aluminum, lead, chromium, manganese and cobalt at concentrations similar, if not higher than, cigarettes. In addition, thermal desorption-gas chromatography–mass spectrometry (TD-GC–MS) was used to analyze the chemical composition of the smoke produced from burning the charcoal samples. The smoke emitted from charcoal was found to be the source of numerous compounds which could be hazardous to health. A total of seven carcinogens, 39 central nervous system depressants and 31 respiratory irritants were identified. - Highlights: • Hookah charcoals, mainly synthetic brands, contains trace/heavy metals in concentrations exceeding those in cigarettes. • The concentration of lead in synthetic charcoal briquettes may impose adverse effects on human health. • The amount of nitrogen in synthetic charcoal is comparable to that reported in cigarettes. • Chemical profiling of smoke emitted from hookah charcoal reveals many compounds associated with potential health risks.

Should tsunami models use a nonzero initial condition for horizontal velocity?

Science.gov (United States)

Nava, G.; Lotto, G. C.; Dunham, E. M.

2017-12-01

Tsunami propagation in the open ocean is most commonly modeled by solving the shallow water wave equations. These equations require two initial conditions: one on sea surface height and another on depth-averaged horizontal particle velocity or, equivalently, horizontal momentum. While most modelers assume that initial velocity is zero, Y.T. Song and collaborators have argued for nonzero initial velocity, claiming that horizontal displacement of a sloping seafloor imparts significant horizontal momentum to the ocean. They show examples in which this effect increases the resulting tsunami height by a factor of two or more relative to models in which initial velocity is zero. We test this claim with a "full-physics" integrated dynamic rupture and tsunami model that couples the elastic response of the Earth to the linearized acoustic-gravitational response of a compressible ocean with gravity; the model self-consistently accounts for seismic waves in the solid Earth, acoustic waves in the ocean, and tsunamis (with dispersion at short wavelengths). We run several full-physics simulations of subduction zone megathrust ruptures and tsunamis in geometries with a sloping seafloor, using both idealized structures and a more realistic Tohoku structure. Substantial horizontal momentum is imparted to the ocean, but almost all momentum is carried away in the form of ocean acoustic waves. We compare tsunami propagation in each full-physics simulation to that predicted by an equivalent shallow water wave simulation with varying assumptions regarding initial conditions. We find that the initial horizontal velocity conditions proposed by Song and collaborators consistently overestimate the tsunami amplitude and predict an inconsistent wave profile. Finally, we determine tsunami initial conditions that are rigorously consistent with our full-physics simulations by isolating the tsunami waves (from ocean acoustic and seismic waves) at some final time, and backpropagating the tsunami

Chemical Potentials of Quarks Extracted from Particle Transverse Momentum Distributions in Heavy Ion Collisions at RHIC Energies

International Nuclear Information System (INIS)

Zhao, Hong; Liu, Fu-Hu

2014-01-01

In the framework of a multisource thermal model, the transverse momentum distributions of charged particles produced in nucleus-nucleus (A-A) and deuteron-nucleus (d-A) collisions at relativistic heavy ion collider (RHIC) energies are investigated by a two-component revised Boltzmann distribution. The calculated results are in agreement with the PHENIX experimental data. It is found that the source temperature increases obviously with increase of the particle mass and incident energy, but it does not show an obvious change with the collision centrality. Then, the values of chemical potentials for up, down, and strange quarks can be obtained from the antiparticle to particle yield ratios in a wide transverse momentum range. The relationship between the chemical potentials of quarks and the transverse momentum with different centralities is investigated, too

Heat conduction in a chain of colliding particles with a stiff repulsive potential

Science.gov (United States)

Gendelman, Oleg V.; Savin, Alexander V.

2016-11-01

One-dimensional billiards, i.e., a chain of colliding particles with equal masses, is a well-known example of a completely integrable system. Billiards with different particle masses is generically not integrable, but it still exhibits divergence of a heat conduction coefficient (HCC) in the thermodynamic limit. Traditional billiards models imply instantaneous (zero-time) collisions between the particles. We relax this condition of instantaneous impact and consider heat transport in a chain of stiff colliding particles with the power-law potential of the nearest-neighbor interaction. The instantaneous collisions correspond to the limit of infinite power in the interaction potential; for finite powers, the interactions take nonzero time. This modification of the model leads to a profound physical consequence—the probability of multiple (in particular triple) -particle collisions becomes nonzero. Contrary to the integrable billiards of equal particles, the modified model exhibits saturation of the heat conduction coefficient for a large system size. Moreover, the identification of scattering events with triple-particle collisions leads to a simple definition of the characteristic mean free path and a kinetic description of heat transport. This approach allows us to predict both the temperature and density dependencies for the HCC limit values. The latter dependence is quite counterintuitive—the HCC is inversely proportional to the particle density in the chain. Both predictions are confirmed by direct numerical simulations.

Are electrostatic potentials between regions of different chemical composition measurable? The Gibbs-Guggenheim Principle reconsidered, extended and its consequences revisited.

Science.gov (United States)

Pethica, Brian A

2007-12-21

As indicated by Gibbs and made explicit by Guggenheim, the electrical potential difference between two regions of different chemical composition cannot be measured. The Gibbs-Guggenheim Principle restricts the use of classical electrostatics in electrochemical theories as thermodynamically unsound with some few approximate exceptions, notably for dilute electrolyte solutions and concomitant low potentials where the linear limit for the exponential of the relevant Boltzmann distribution applies. The Principle invalidates the widespread use of forms of the Poisson-Boltzmann equation which do not include the non-electrostatic components of the chemical potentials of the ions. From a thermodynamic analysis of the parallel plate electrical condenser, employing only measurable electrical quantities and taking into account the chemical potentials of the components of the dielectric and their adsorption at the surfaces of the condenser plates, an experimental procedure to provide exceptions to the Principle has been proposed. This procedure is now reconsidered and rejected. No other related experimental procedures circumvent the Principle. Widely-used theoretical descriptions of electrolyte solutions, charged surfaces and colloid dispersions which neglect the Principle are briefly discussed. MD methods avoid the limitations of the Poisson-Bolzmann equation. Theoretical models which include the non-electrostatic components of the inter-ion and ion-surface interactions in solutions and colloid systems assume the additivity of dispersion and electrostatic forces. An experimental procedure to test this assumption is identified from the thermodynamics of condensers at microscopic plate separations. The available experimental data from Kelvin probe studies are preliminary, but tend against additivity. A corollary to the Gibbs-Guggenheim Principle is enunciated, and the Principle is restated that for any charged species, neither the difference in electrostatic potential nor the

Top Value Added Chemicals from Biomass: Volume I -- Results of Screening for Potential Candidates from Sugars and Synthesis Gas

Energy Technology Data Exchange (ETDEWEB)

Werpy, T.; Petersen, G.

2004-08-01

This report identifies twelve building block chemicals that can be produced from sugars via biological or chemical conversions. The twelve building blocks can be subsequently converted to a number of high-value bio-based chemicals or materials. Building block chemicals, as considered for this analysis, are molecules with multiple functional groups that possess the potential to be transformed into new families of useful molecules. The twelve sugar-based building blocks are 1,4-diacids (succinic, fumaric and malic), 2,5-furan dicarboxylic acid, 3-hydroxy propionic acid, aspartic acid, glucaric acid, glutamic acid, itaconic acid, levulinic acid, 3-hydroxybutyrolactone, glycerol, sorbitol, and xylitol/arabinitol.

Top Value Added Chemicals from Biomass - Volume I, Results of Screening for Potential Candidates from Sugars and Synthesis Gas

Energy Technology Data Exchange (ETDEWEB)

None

2004-08-01

This report identifies twelve building block chemicals that can be produced from sugars via biological or chemical conversions. The twelve building blocks can be subsequently converted to a number of high-value bio-based chemicals or materials. Building block chemicals, as considered for this analysis, are molecules with multiple functional groups that possess the potential to be transformed into new families of useful molecules. The twelve sugar-based building blocks are 1,4-diacids (succinic, fumaric and malic), 2,5-furan dicarboxylic acid, 3-hydroxy propionic acid, aspartic acid, glucaric acid, glutamic acid, itaconic acid, levulinic acid, 3-hydroxybutyrolactone, glycerol, sorbitol, and xylitol/arabinitol.

Critical phenomena and chemical potential of a charged AdS black hole

Science.gov (United States)

Wei, Shao-Wen; Liang, Bin; Liu, Yu-Xiao

2017-12-01

Inspired by the interpretation of the cosmological constant from the boundary gauge theory, we here treat it as the number of colors N and its conjugate quantity as the associated chemical potential μ in the black hole side. Then the thermodynamics and the chemical potential for a five-dimensional charged AdS black hole are studied. It is found that there exists a small-large black hole phase transition of van der Waals type. The critical phenomena are investigated in the N2-μ chart. The result implies that the phase transition can occur for large number of colors N , while is forbidden for small number. This to some extent implies that the interaction of the system increases with the number. In particular, in the reduced parameter space, all the thermodynamic quantities can be rescaled with the black hole charge such that these reduced quantities are charge-independent. Then we obtain the coexistence curve and the phase diagram. The latent heat is also numerically calculated. Moreover, the heat capacity and the thermodynamic scalar are studied. The result indicates that the information of the first-order black hole phase transition is encoded in the heat capacity and scalar. However, the phase transition point cannot be directly calculated with them. Nevertheless, the critical point linked to a second-order phase transition can be determined by either the heat capacity or the scalar. In addition, we calculate the critical exponents of the heat capacity and the scalar for the saturated small and large black holes near the critical point.

Kaempferitrin from Uncaria guianensis (Rubiaceae) and its potential as a chemical marker for the species

Energy Technology Data Exchange (ETDEWEB)

Valente, Ligia M.M.; Liechocki, Sally; Barboza, Rodolfo S.; Paixao, Djavan da [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica], e-mail: valente@iq.ufrj.br; Bizarri, Carlos H.B.; Almeida, M. Beatriz S.; Benevides, Paulo J.C.; Siani, Antonio C. [Fundacao Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, RJ (Brazil). Inst. de Tecnologia em Farmacos; Magalhaes, Alvicler [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Quimica

2009-07-01

Uncaria tomentosa (Willd.) DC. and U. guianensis (Aubl.) Gmel., known as cat's claw, are large woody vines native to the Amazonian and Central American rain forests. The species contain, in different proportions, indole and oxindole alkaloids, triterpenoid glycosides, sterols and proanthocyanidins. U. tomentosa can be chemically identified by its oxindole alkaloid profile and content, whereas U. guianensis has no satisfactorily established chemical markers. This work describes, for the first time, the isolation of kaempferol-3,7-O-(a)-dirhamnoside (kaempferitrin) in Uncaria species. Screening for this compound in leaves, stems or bark of both species through TLC and HPLC-DAD-MS showed the presence of kaempferitrin only in the leaves and stems of U. guianensis, at a ratio almost thirty six times greater in the leaves than in the stems. These results reveal the selectivity of U. guianensis to produce this bioactive flavonoid glycoside, and suggest this compound as a potential chemical marker for the species.(author)

Kaempferitrin from Uncaria guianensis (Rubiaceae) and its potential as a chemical marker for the species

International Nuclear Information System (INIS)

Valente, Ligia M.M.; Liechocki, Sally; Barboza, Rodolfo S.; Paixao, Djavan da; Bizarri, Carlos H.B.; Almeida, M. Beatriz S.; Benevides, Paulo J.C.; Siani, Antonio C.; Magalhaes, Alvicler

2009-01-01

Uncaria tomentosa (Willd.) DC. and U. guianensis (Aubl.) Gmel., known as cat's claw, are large woody vines native to the Amazonian and Central American rain forests. The species contain, in different proportions, indole and oxindole alkaloids, triterpenoid glycosides, sterols and proanthocyanidins. U. tomentosa can be chemically identified by its oxindole alkaloid profile and content, whereas U. guianensis has no satisfactorily established chemical markers. This work describes, for the first time, the isolation of kaempferol-3,7-O-(a)-dirhamnoside (kaempferitrin) in Uncaria species. Screening for this compound in leaves, stems or bark of both species through TLC and HPLC-DAD-MS showed the presence of kaempferitrin only in the leaves and stems of U. guianensis, at a ratio almost thirty six times greater in the leaves than in the stems. These results reveal the selectivity of U. guianensis to produce this bioactive flavonoid glycoside, and suggest this compound as a potential chemical marker for the species.(author)

Potential Impacts of Spilled Hydraulic Fracturing Fluid Chemicals on Water Resources: Types, volumes, and physical-chemical properties of chemicals

Science.gov (United States)

Hydraulic fracturing (HF) fluid chemicals spilled on-site may impact drinking water resources. While chemicals generally make up <2% of the total injected fluid composition by mass, spills may have undiluted concentrations. HF fluids typically consist of a mixture of base flui...

Human Pluripotent Stem Cell-Based Assay Predicts Developmental Toxicity Potential of ToxCast Chemicals (ACT meeting)

Science.gov (United States)

Worldwide initiatives to screen for toxicity potential among the thousands of chemicals currently in use require inexpensive and high-throughput in vitro models to meet their goals. The devTOX quickPredict platform is an in vitro human pluripotent stem cell-based assay used to as...

Sedimentation stacking diagram of binary colloidal mixtures and bulk phases in the plane of chemical potentials

International Nuclear Information System (INIS)

Heras, Daniel de las; Schmidt, Matthias

2015-01-01

We give a full account of a recently proposed theory that explicitly relates the bulk phase diagram of a binary colloidal mixture to its phase stacking phenomenology under gravity (de las Heras and Schmidt 2013 Soft Matter 9 8636). As we demonstrate, the full set of possible phase stacking sequences in sedimentation-diffusion equilibrium originates from straight lines (sedimentation paths) in the chemical potential representation of the bulk phase diagram. From the analysis of various standard topologies of bulk phase diagrams, we conclude that the corresponding sedimentation stacking diagrams can be very rich, even more so when finite sample height is taken into account. We apply the theory to obtain the stacking diagram of a mixture of nonadsorbing polymers and colloids. We also present a catalog of generic phase diagrams in the plane of chemical potentials in order to facilitate the practical application of our concept, which also generalizes to multi-component mixtures. (paper)

A simple in chemico method for testing skin sensitizing potential of chemicals using small endogenous molecules.

Science.gov (United States)

Nepal, Mahesh Raj; Shakya, Rajina; Kang, Mi Jeong; Jeong, Tae Cheon

2018-06-01

Among many of the validated methods for testing skin sensitization, direct peptide reactivity assay (DPRA) employs no cells or animals. Although no immune cells are involved in this assay, it reliably predicts the skin sensitization potential of a chemical in chemico. Herein, a new method was developed using endogenous small-molecular-weight compounds, cysteamine and glutathione, rather than synthetic peptides, to differentiate skin sensitizers from non-sensitizers with an accuracy as high as DPRA. The percent depletion of cysteamine and glutathione by test chemicals was measured by an HPLC equipped with a PDA detector. To detect small-size molecules, such as cysteamine and glutathione, a derivatization by 4-(4-dimethylaminophenylazo) benzenesulfonyl chloride (DABS-Cl) was employed prior to the HPLC analysis. Following test method optimization, a cut-off criterion of 7.14% depletion was applied to differentiate skin sensitizers from non-sensitizers in combination of the ratio of 1:25 for cysteamine:test chemical with 1:50 for glutathione:test chemical for the best predictivity among various single or combination conditions. Although overlapping HPLC peaks could not be fully resolved for some test chemicals, high levels of sensitivity (100.0%), specificity (81.8%), and accuracy (93.3%) were obtained for 30 chemicals tested, which were comparable or better than those achieved with DPRA. Copyright © 2018 Elsevier B.V. All rights reserved.

Proper energy of an electron in a topologically massive (2 + 1) quantum electrodynamics system at finite temperature and density

International Nuclear Information System (INIS)

Zhukovskii, K.V.; Eminov, P.A.

1995-01-01

The one-loop approximation is used to calculate the effects of finite temperature and nonzero chemical potential on the electron energy shift in a (2 + 1)-quantum electrodynamic system containing a Churn-Simon term. The induced electron mass is derived with a massless (2 + 1)-quantum electrodynamic system together with the exchange correction to the thermodynamic potential for a completely degenerate electron gas. It is shown that in the last case, incorporating the Churn-Simon term leads to loss of the gap in the direction law

Chemical constituents and anti-ulcerogenic potential of the scales of Cynara scolymus (artichoke) heads.

Science.gov (United States)

Nassar, Mahmoud I; Mohamed, Tahia K; Elshamy, Abdelsamed I; El-Toumy, Sayed A; Abdel Lateef, Azza M; Farrag, Abdel-Razik H

2013-08-15

Cynara scolymus L. (Asteraseae) (artichoke) is commonly eaten as a vegetable; its leaves are frequently used in folk medicine in the treatment of hepatitis, hyperlipidaemia, obesity and dyspeptic disorders. The purpose of this study is to determine the chemical composition of the volatile oil and alcoholic extract of artichoke head scales. In addition, the role of the methanol extract as an anti-ulcer agent against ethanol-induced gastric ulcer in rats was evaluated. Six flavonoids and one phenolic acid were obtained from the methanol extract. Also, 37 compounds were identified in the volatile oil, the majority including mono- and sesquiterpenes. The artichoke extracts (200 and 400 mg kg(-1)) significantly (P artichoke induced an increase in gastric mucus production, and a reduction of the depth and severity of mucosal lesions. Artichoke dose-dependently reduced the elevated ethanol gastric malonylaldehyde, and reduced glutathione levels and catalase activity. These results suggest that the head scales of artichoke possess potential anti-ulcer activity. The present paper describes the identification of volatile oil for the first time along with the isolation and identification of the constituents of the methanol extract. Moreover, the high anti-ulcerogenic potential of scales of C. scolymus heads was established here for the first time. © 2013 Society of Chemical Industry.

The effect of non-zero radial velocity on the impulse and circulation of starting jets

Science.gov (United States)

Krieg, Michael; Mohseni, Kamran

2011-11-01

Vortex ring formation dynamics are generally studied using two basic types of vortex generators. Piston cylinder vortex generators eject fluid through a long tube which ensures a purely axial jet; whereas, vortex ring generators which expel fluid through a flat plate with a circular orifice produce 2-D jets (non-zero radial velocity). At the nozzle exit plane of the orifice type vortex generator the radial component of velocity is linearly proportional to the radial distance from the axis of symmetry, reaching a maximum at the edge of the orifice with a magnitude around 10 % of the piston velocity (the ratio of the volume flux and the nozzle area). As the jet advances downstream the radial velocity quickly dissipates, and becomes purely axial less than a diameter away from the nozzle exit plane. The radial velocity gradient in the axial direction plays a key role in the rate at which circulation and impulse are ejected from the vortex generator. Though the radial component of velocity is small compared to the axial velocity, it has a significant effect on both the circulation and impulse of the starting jet because of this gradient. The extent of circulation and impulse enhancement is investigated through experimental DPIV data showing that the orifice device produces nearly double both circulation and energy (with identical piston velocity and stroke ratios).

Limitations in Using Chemical Oxidative Potential to Understand Oxidative Stress from Particulate Matter

Science.gov (United States)

Chan, A. W. H.; Wang, S.; Wang, X.; Kohl, L.; Chow, C. W.

2017-12-01

Particulate matter (PM) in the atmosphere is known to cause adverse cardiorespiratory health effects. It has been suggested that the ability of PM to generate oxidative stress leads to a proinflammatory response. In this work, we study the biological relevance of using a chemical oxidative potential (OP) assay to evaluate proinflammatory response in airway epithelial cells. Here we study the OPs of laboratory secondary organic aerosol (SOA) and metal mixtures, ambient PM from India, ash from the 2016 Alberta wildfires, and diesel exhaust particles. We use SOA derived from naphthalene and from monoterpenes as model systems for SOA. We measure OP using the dithiothreitol (DTT) assay, and cytosolic reactive oxygen species (ROS) production in BEAS-2B cell culture was measured using CellROX assay. We found that both SOA and copper show high OPs individually, but the OP of the combined SOA/copper mixture, which is more atmospherically relevant, was lower than either of the individual OPs. The reduced activity is attributed to chelation between metals and organic compounds using proton nuclear magnetic resonance. There is reasonable association between DTT activity and cellular ROS production within each particle type, but weak association across different particle types, suggesting that particle composition plays an important role in distinguishing between antioxidant consumption and ROS production. Our results highlight that while oxidative potential is a useful metric of PM's ability to generate oxidative stress, the chemical composition and cellular environment should be considered in understanding health impacts of PM.

New approach to predict photoallergic potentials of chemicals based on murine local lymph node assay.

Science.gov (United States)

Maeda, Yosuke; Hirosaki, Haruka; Yamanaka, Hidenori; Takeyoshi, Masahiro

2018-05-23

Photoallergic dermatitis, caused by pharmaceuticals and other consumer products, is a very important issue in human health. However, S10 guidelines of the International Conference on Harmonization do not recommend the existing prediction methods for photoallergy because of their low predictability in human cases. We applied local lymph node assay (LLNA), a reliable, quantitative skin sensitization prediction test, to develop a new photoallergy prediction method. This method involves a three-step approach: (1) ultraviolet (UV) absorption analysis; (2) determination of no observed adverse effect level for skin phototoxicity based on LLNA; and (3) photoallergy evaluation based on LLNA. Photoallergic potential of chemicals was evaluated by comparing lymph node cell proliferation among groups treated with chemicals with minimal effect levels of skin sensitization and skin phototoxicity under UV irradiation (UV+) or non-UV irradiation (UV-). A case showing significant difference (P < .05) in lymph node cell proliferation rates between UV- and UV+ groups was considered positive for photoallergic reaction. After testing 13 chemicals, seven human photoallergens tested positive and the other six, with no evidence of causing photoallergic dermatitis or UV absorption, tested negative. Among these chemicals, both doxycycline hydrochloride and minocycline hydrochloride were tetracycline antibiotics with different photoallergic properties, and the new method clearly distinguished between the photoallergic properties of these chemicals. These findings suggested high predictability of our method; therefore, it is promising and effective in predicting human photoallergens. Copyright © 2018 John Wiley & Sons, Ltd.

A comparison of measured radionuclide release rates from Three Mile Island Unit-2 core debris for different oxygen chemical potentials

International Nuclear Information System (INIS)

Baston, V.F.; Hofstetter, K.J.; Ryan, R.F.

1987-01-01

Chemical and radiochemical analyses of reactor coolant samples taken during defueling of the Three Mile Island Unit-2 (TMI-2) reactor provide relevant data to assist in understanding the solution chemistry of the radionuclides retained within the TMI-2 reactor coolant system. Hydrogen peroxide was added to various plant systems to provide disinfection for microbial contamination and has provided the opportunity to observe radionuclide release under different oxygen chemical potentials. A comparison of the radionuclide release rates with and without hydrogen peroxide has been made for these separate but related cases, i.e., the fuel transfer canal and connecting spent-fuel pool A with the TMI-2 reactor plenum in the fuel transfer canal, core debris grab sample laboratory experiments, and the reactor vessel fluid and associated core debris. Correlation and comparison of these data indicate a physical parameter dependence (surface-to-volume ratio) affecting all radionuclide release; however, selected radionuclides also demonstrate a chemical dependence release under the different oxygen chemical potentials. Chemical and radiochemical analyses of reactor coolant samples taken during defueling of the Three Mile Island Unit-2 (TMI-2) reactor provide relevant data to assist in understanding the solution chemistry of the radionuclides retained within the TMI-2 reactor coolant system

Overview of a workshop on screening methods for detecting potential (anti-) estrogenic/androgenic chemicals in wildlife

Science.gov (United States)

Ankley, Gerald T.; Mihaich, Ellen; Stahl, Ralph G.; Tillitt, Donald E.; Colborn, Theo; McMaster, Suzzanne; Miller, Ron; Bantle, John; Campbell, Pamela; Denslow, Nancy; Dickerson, Richard L.; Folmar, Leroy C.; Fry, Michael; Giesy, John P.; Gray, L. Earl; Guiney, Patrick; Hutchinson, Thomas; Kennedy, Sean W.; Kramer, Vincent; LeBlanc, Gerald A.; Mayes, Monte; Nimrod, Alison; Patino, Reynaldo; Peterson, Richard; Purdy, Richard; Ringer, Robert; Thomas, Peter C.; Touart, Les; Van Der Kraak, Glen; Zacharewski, Tim

1998-01-01

The U.S. Congress has passed legislation requiring the U.S. Environmental Protection Agency (U.S. EPA) to develop, validate, and implement screening tests for identifying potential endocrine-disrupting chemicals within 3 years. To aid in the identification of methods suitable for this purpose, the U.S. EPA, the Chemical Manufacturers Association, and the World Wildlife Fund sponsored several workshops, including the present one, which dealt with wildlife species. This workshop was convened with 30 international scientists representing multiple disciplines in March 1997 in Kansas City, Missouri, USA. Participants at the meeting identified methods in terms of their ability to indicate (anti-) estrogenic/androgenic effects, particularly in the context of developmental and reproductive processes. Data derived from structure-activity relationship models and in vitro test systems, although useful in certain contexts, cannot at present replace in vivo tests as the sole basis for screening. A consensus was reached that existing mammalian test methods (e.g., with rats or mice) generally are suitable as screens for assessing potential (anti-) estrogenic/ androgenic effects in mammalian wildlife. However, due to factors such as among-class variation in receptor structure and endocrine function, it is uncertain if these mammalian assays would be of broad utility as screens for other classes of vertebrate wildlife. Existing full and partial life-cycle tests with some avian and fish species could successfully identify chemicals causing endocrine disruption; however, these long-term tests are not suitable for routine screening. However, a number of short-term tests with species from these two classes exist that could serve as effective screening tools for chemicals inducing (anti-) estrogenic/androgenic effects. Existing methods suitable for identifying chemicals with these mechanisms of action in reptiles and amphibians are limited, but in the future, tests with species from

Evaluation of a high-throughput peptide reactivity format assay for assessment of the skin sensitization potential of chemicals

Directory of Open Access Journals (Sweden)

Chin Lin eWong

2016-03-01

Full Text Available The direct peptide reactivity assay (DPRA is a validated method for in vitro assessment of the skin sensitization potential of chemicals. In the present work, we describe a peptide reactivity assay using 96-well plate format and systematically identified the optimal assay conditions for accurate and reproducible classification of chemicals with known sensitizing capacity. The aim of the research is to ensure that the analytical component of the peptide reactivity assay is robust, accurate and reproducible in accordance with criteria that are used for the validation of bioanalytical methods. Analytical performance was evaluated using quality control samples (QCs; heptapeptides at low, medium and high concentrations and incubation of control chemicals (chemicals with known sensitization capacity, weak, moderate, strong, extreme and non-sensitizers with each of three synthetic heptapeptides, viz Cor1-C420 (Ac-NKKCDLF, cysteine- (Ac-RFAACAA and lysine- (Ac-RFAAKAA containing heptapeptides. The optimal incubation temperature for all three heptapeptides was 25°C. Apparent heptapeptide depletion was affected by vial material composition. Incubation of test chemicals with Cor1-C420, showed that peptide depletion was unchanged in polypropylene vials over 3-days storage in an autosampler but this was not the case for borosilicate glass vials. For cysteine-containing heptapeptide, the concentration was not stable by day 3 post-incubation in borosilicate glass vials. Although the lysine-containing heptapeptide concentration was unchanged in both polypropylene and borosilicate glass vials, the apparent extent of lysine-containing heptapeptide depletion by ethyl acrylate, differed between polypropylene (24.7% and glass (47.3% vials. Additionally, the peptide-chemical complexes for Cor1-C420-cinnamaldehyde and cysteine-containing heptapeptide-2,4-dinitrochlorobenzene were partially reversible during 3-days of autosampler storage. These observations further

Comet assay evaluation of six chemicals of known genotoxic potential in rats.

Science.gov (United States)

Hobbs, Cheryl A; Recio, Leslie; Streicker, Michael; Boyle, Molly H; Tanaka, Jin; Shiga, Atsushi; Witt, Kristine L

2015-07-01

As a part of an international validation of the in vivo rat alkaline comet assay (comet assay) initiated by the Japanese Center for the Validation of Alternative Methods (JaCVAM) we examined six chemicals for potential to induce DNA damage: 2-acetylaminofluorene (2-AAF), N-nitrosodimethylamine (DMN), o-anisidine, 1,2-dimethylhydrazine dihydrochloride (1,2-DMH), sodium chloride, and sodium arsenite. DNA damage was evaluated in the liver and stomach of 7- to 9-week-old male Sprague Dawley rats. Of the five genotoxic carcinogens tested in our laboratory, DMN and 1,2-DMH were positive in the liver and negative in the stomach, 2-AAF and o-anisidine produced an equivocal result in liver and negative results in stomach, and sodium arsenite was negative in both liver and stomach. 1,2-DMH and DMN induced dose-related increases in hedgehogs in the same tissue (liver) that exhibited increased DNA migration. However, no cytotoxicity was indicated by the neutral diffusion assay (assessment of highly fragmented DNA) or histopathology in response to treatment with any of the tested chemicals. Therefore, the increased DNA damage resulting from exposure to DMN and 1,2-DMH was considered to represent a genotoxic response. Sodium chloride, a non-genotoxic non-carcinogen, was negative in both tissues as would be predicted. Although only two (1,2-DMH and DMN) out of five genotoxic carcinogens produced clearly positive results in the comet assay, the results obtained for o-anisidine and sodium arsenite in liver and stomach cells are consistent with the known mode of genotoxicity and tissue specificity exhibited by these carcinogens. In contrast, given the known genotoxic mode-of-action and target organ carcinogenicity of 2-AAF, it is unclear why this chemical failed to convincingly increase DNA migration in the liver. Thus, the results of the comet assay validation studies conducted in our laboratory were considered appropriate for five out of the six test chemicals. Copyright © 2015

Thermodynamic chemical energy transfer mechanisms of non-equilibrium, quasi-equilibrium, and equilibrium chemical reactions

International Nuclear Information System (INIS)

Roh, Heui-Seol

2015-01-01

Chemical energy transfer mechanisms at finite temperature are explored by a chemical energy transfer theory which is capable of investigating various chemical mechanisms of non-equilibrium, quasi-equilibrium, and equilibrium. Gibbs energy fluxes are obtained as a function of chemical potential, time, and displacement. Diffusion, convection, internal convection, and internal equilibrium chemical energy fluxes are demonstrated. The theory reveals that there are chemical energy flux gaps and broken discrete symmetries at the activation chemical potential, time, and displacement. The statistical, thermodynamic theory is the unification of diffusion and internal convection chemical reactions which reduces to the non-equilibrium generalization beyond the quasi-equilibrium theories of migration and diffusion processes. The relationship between kinetic theories of chemical and electrochemical reactions is also explored. The theory is applied to explore non-equilibrium chemical reactions as an illustration. Three variable separation constants indicate particle number constants and play key roles in describing the distinct chemical reaction mechanisms. The kinetics of chemical energy transfer accounts for the four control mechanisms of chemical reactions such as activation, concentration, transition, and film chemical reactions. - Highlights: • Chemical energy transfer theory is proposed for non-, quasi-, and equilibrium. • Gibbs energy fluxes are expressed by chemical potential, time, and displacement. • Relationship between chemical and electrochemical reactions is discussed. • Theory is applied to explore nonequilibrium energy transfer in chemical reactions. • Kinetics of non-equilibrium chemical reactions shows the four control mechanisms

Diquark condensate and quark interaction with instanton liquid

International Nuclear Information System (INIS)

Zinov'ev, G.M.; Molodtsov, S.V.

2003-01-01

The interaction of light quarks and instanton liquid is analyzed at finite density of quark/baryon matter and in the phase of nonzero values of diquark (color) condensate. It is shown that instanton liquid perturbation produced by such an interaction results in an essential increase of the critical value of quark chemical potential μ c which provokes the perceptible increase of quark matter density around the expected onset of the color superconductivity phase [ru

Profiling of the Tox21 Chemical Collection for Mitochondrial Function to Identify Compounds that Acutely Decrease Mitochondrial Membrane Potential

Science.gov (United States)

Attene-Ramos, Matias S.; Huang, Ruili; Michael, Sam; Witt, Kristine L.; Richard, Ann; Tice, Raymond R.; Simeonov, Anton; Austin, Christopher P.

2014-01-01

Background: Mitochondrial dysfunction has been implicated in the pathogenesis of a variety of disorders including cancer, diabetes, and neurodegenerative and cardiovascular diseases. Understanding whether different environmental chemicals and druglike molecules impact mitochondrial function represents an initial step in predicting exposure-related toxicity and defining a possible role for such compounds in the onset of various diseases. Objectives: We sought to identify individual chemicals and general structural features associated with changes in mitochondrial membrane potential (MMP). Methods: We used a multiplexed [two end points in one screen; MMP and adenosine triphosphate (ATP) content] quantitative high throughput screening (qHTS) approach combined with informatics tools to screen the Tox21 library of 10,000 compounds (~ 8,300 unique chemicals) at 15 concentrations each in triplicate to identify chemicals and structural features that are associated with changes in MMP in HepG2 cells. Results: Approximately 11% of the compounds (913 unique compounds) decreased MMP after 1 hr of treatment without affecting cell viability (ATP content). In addition, 309 compounds decreased MMP over a concentration range that also produced measurable cytotoxicity [half maximal inhibitory concentration (IC50) in MMP assay/IC50 in viability assay ≤ 3; p Tice RR, Simeonov A, Austin CP, Xia M. 2015. Profiling of the Tox21 chemical collection for mitochondrial function to identify compounds that acutely decrease mitochondrial membrane potential. Environ Health Perspect 123:49–56; http://dx.doi.org/10.1289/ehp.1408642 PMID:25302578

Energy saving analysis and management modeling based on index decomposition analysis integrated energy saving potential method: Application to complex chemical processes

International Nuclear Information System (INIS)

Geng, Zhiqiang; Gao, Huachao; Wang, Yanqing; Han, Yongming; Zhu, Qunxiong

2017-01-01

Highlights: • The integrated framework that combines IDA with energy-saving potential method is proposed. • Energy saving analysis and management framework of complex chemical processes is obtained. • This proposed method is efficient in energy optimization and carbon emissions of complex chemical processes. - Abstract: Energy saving and management of complex chemical processes play a crucial role in the sustainable development procedure. In order to analyze the effect of the technology, management level, and production structure having on energy efficiency and energy saving potential, this paper proposed a novel integrated framework that combines index decomposition analysis (IDA) with energy saving potential method. The IDA method can obtain the level of energy activity, energy hierarchy and energy intensity effectively based on data-drive to reflect the impact of energy usage. The energy saving potential method can verify the correctness of the improvement direction proposed by the IDA method. Meanwhile, energy efficiency improvement, energy consumption reduction and energy savings can be visually discovered by the proposed framework. The demonstration analysis of ethylene production has verified the practicality of the proposed method. Moreover, we can obtain the corresponding improvement for the ethylene production based on the demonstration analysis. The energy efficiency index and the energy saving potential of these worst months can be increased by 6.7% and 7.4%, respectively. And the carbon emissions can be reduced by 7.4–8.2%.

Molecular Spectrum Capture by Tuning the Chemical Potential of Graphene

Directory of Open Access Journals (Sweden)

Yue Cheng

2016-05-01

Full Text Available Due to its adjustable electronic properties and effective excitation of surface plasmons in the infrared and terahertz frequency range, research on graphene has attracted a great deal of attention. Here, we demonstrate that plasmon modes in graphene-coated dielectric nanowire (GNW waveguides can be excited by a monolayer graphene ribbon. What is more the transverse resonant frequency spectrum of the GNW can be flexibly tuned by adjusting the chemical potential of graphene, and amplitude of the resonance peak varies linearly with the imaginary part of the analyte permittivity. As a consequence, the GNW works as a probe for capturing the molecular spectrum. Broadband sensing of toluene, ethanol and sulfurous anhydride thin layers is demonstrated by calculating the changes in spectral intensity of the propagating mode and the results show that the intensity spectra correspond exactly to the infrared spectra of these molecules. This may open an effective avenue to design sensors for detecting nanometric-size molecules in the terahertz and infrared regimes.

Transient receptor potential channels encode volatile chemicals sensed by rat trigeminal ganglion neurons.

Directory of Open Access Journals (Sweden)

Matthias Lübbert

Full Text Available Primary sensory afferents of the dorsal root and trigeminal ganglia constantly transmit sensory information depicting the individual's physical and chemical environment to higher brain regions. Beyond the typical trigeminal stimuli (e.g. irritants, environmental stimuli comprise a plethora of volatile chemicals with olfactory components (odorants. In spite of a complete loss of their sense of smell, anosmic patients may retain the ability to roughly discriminate between different volatile compounds. While the detailed mechanisms remain elusive, sensory structures belonging to the trigeminal system seem to be responsible for this phenomenon. In order to gain a better understanding of the mechanisms underlying the activation of the trigeminal system by volatile chemicals, we investigated odorant-induced membrane potential changes in cultured rat trigeminal neurons induced by the odorants vanillin, heliotropyl acetone, helional, and geraniol. We observed the dose-dependent depolarization of trigeminal neurons upon application of these substances occurring in a stimulus-specific manner and could show that distinct neuronal populations respond to different odorants. Using specific antagonists, we found evidence that TRPA1, TRPM8, and/or TRPV1 contribute to the activation. In order to further test this hypothesis, we used recombinantly expressed rat and human variants of these channels to investigate whether they are indeed activated by the odorants tested. We additionally found that the odorants dose-dependently inhibit two-pore potassium channels TASK1 and TASK3 heterologously expressed In Xenopus laevis oocytes. We suggest that the capability of various odorants to activate different TRP channels and to inhibit potassium channels causes neuronal depolarization and activation of distinct subpopulations of trigeminal sensory neurons, forming the basis for a specific representation of volatile chemicals in the trigeminal ganglia.

Assessing Uncertainties in Boundary Layer Transition Predictions for HIFiRE-1 at Non-zero Angles of Attack

Science.gov (United States)

Marek, Lindsay C.

2011-01-01

Boundary layer stability was analyzed for the HIFiRE-1 flight vehicle geometry for ground tests conducted at the CUBRC LENS I hypersonic shock test facility and the Langley Research Center (LaRC) 20- inch Mach 6 Tunnel. Boundary layer stability results were compared to transition onset location obtained from discrete heat transfer measurements from thin film gauges during the CUBRC test and spatially continuous heat transfer measurements from thermal phosphor paint data during the LaRC test. The focus of this analysis was on conditions at non-zero angles of attack as stability analysis has already been performed at zero degrees angle of attack. Also, the transition onset data obtained during flight testing was at nonzero angles of attack, so this analysis could be expanded in the future to include the results of the flight test data. Stability analysis was performed using the 2D parabolized stability software suite STABL (Stability and Transition Analysis for Hypersonic Boundary Layers) developed at the University of Minnesota and the mean flow solutions were computed using the DPLR finite volume Navier-Stokes computational fluid dynamics (CFD) solver. A center line slice of the 3D mean flow solution was used for the stability analysis to incorporate the angle of attack effects while still taking advantage of the 2D STABL software suite. The N-factors at transition onset and the value of Re(sub theta)/M(sub e), commonly used to predict boundary layer transition onset, were compared for all conditions analyzed. Ground test data was analyzed at Mach 7.2 and Mach 6.0 and angles of attack of 1deg, 3deg and 5deg. At these conditions, the flow was found to be second mode dominant for the HIFiRE-1 slender cone geometry. On the leeward side of the vehicle, a strong trend of transition onset location with angle of attack was observed as the boundary layer on the leeward side of the vehicle developed inflection points at streamwise positions on the vehicle that correlated to

A note on the uniqueness of 2D elastostatic problems formulated by different types of potential functions

Science.gov (United States)

Guerrero, José Luis Morales; Vidal, Manuel Cánovas; Nicolás, José Andrés Moreno; López, Francisco Alhama

2018-05-01

New additional conditions required for the uniqueness of the 2D elastostatic problems formulated in terms of potential functions for the derived Papkovich-Neuber representations, are studied. Two cases are considered, each of them formulated by the scalar potential function plus one of the rectangular non-zero components of the vector potential function. For these formulations, in addition to the original (physical) boundary conditions, two new additional conditions are required. In addition, for the complete Papkovich-Neuber formulation, expressed by the scalar potential plus two components of the vector potential, the additional conditions established previously for the three-dimensional case in z-convex domain can be applied. To show the usefulness of these new conditions in a numerical scheme two applications are numerically solved by the network method for the three cases of potential formulations.

Unusually large chemical potential shift in a degenerate semiconductor: Angle-resolved photoemission study of SnSe and Na-doped SnSe

Science.gov (United States)

Maeda, M.; Yamamoto, K.; Mizokawa, T.; Saini, N. L.; Arita, M.; Namatame, H.; Taniguchi, M.; Tan, G.; Zhao, L. D.; Kanatzidis, M. G.

2018-03-01

We have studied the electronic structure of SnSe and Na-doped SnSe by means of angle-resolved photoemission spectroscopy. The valence-band top reaches the Fermi level by the Na doping, indicating that Na-doped SnSe can be viewed as a degenerate semiconductor. However, in the Na-doped system, the chemical potential shift with temperature is unexpectedly large and is apparently inconsistent with the degenerate semiconductor picture. The large chemical potential shift and anomalous spectral shape are key ingredients for an understanding of the novel metallic state with the large thermoelectric performance in Na-doped SnSe.

Wigner functions for fermions in strong magnetic fields

Science.gov (United States)

Sheng, Xin-li; Rischke, Dirk H.; Vasak, David; Wang, Qun

2018-02-01

We compute the covariant Wigner function for spin-(1/2) fermions in an arbitrarily strong magnetic field by exactly solving the Dirac equation at non-zero fermion-number and chiral-charge densities. The Landau energy levels as well as a set of orthonormal eigenfunctions are found as solutions of the Dirac equation. With these orthonormal eigenfunctions we construct the fermion field operators and the corresponding Wigner-function operator. The Wigner function is obtained by taking the ensemble average of the Wigner-function operator in global thermodynamical equilibrium, i.e., at constant temperature T and non-zero fermion-number and chiral-charge chemical potentials μ and μ_5, respectively. Extracting the vector and axial-vector components of the Wigner function, we reproduce the currents of the chiral magnetic and separation effect in an arbitrarily strong magnetic field.

CORRELATION OF POTENTIAL Z AND PHYSICO-CHEMICAL PARAMETERS IN EXTRACTS OF GROUND SATURATION OF THE DR03, VALLEY OF THE MEZQUITAL, HIDALGO, MEXICO

Directory of Open Access Journals (Sweden)

Francisco Prieto Garcia

2009-01-01

Full Text Available The study of physico-chemical characterization of soils sustaining crops (8912 ha of the Actopan-Ixmiquilpan zone is realised, which are irrigated with black waters. The physico-chemical characterization was realised by means of established determinations in NOM-021- RECNAT-2000 from the saturation extracts. The potential Z was moderate in these extracts and were correlated with physico-chemical parameters. From the calculated correlations it was possible to be determined that a correlation between physico-chemical properties of grounds like the pH and the potential Z exists (pZ. Also other correspondences between the values of pZ settle down, with the years of applications of the irrigation with black waters in these grounds. These studies provide the bases for later evaluations of probable affectations to the quality of grounds by the extensive use of irrigation with black waters.

Physico-chemical, mineralogical and chemical considerations in ...

African Journals Online (AJOL)

... pH (5.17 – 6.90) and EC (16.53 – 149.20ìS/cm). Values from physico-chemical analyses, secondary minerals abundance index (SMAI) and chemical index of alteration (CIA) of the soils were reflective of particles with high potential for sliding. With major contributions from favourable slope, seismic and hydrologic forces, ...

Search for a nonzero triple-correlation coefficient and new experimental limit on T invariance in polarized-neutron beta decay

International Nuclear Information System (INIS)

Steinberg, R.I.; Liaud, P.; Vignon, B.; Hughes, V.W.

1976-01-01

A detailed description of an experimental test of time-reversal invariance in the β decay of the polarized free neutron is presented. The experiment consists of a measurement of the triple-correlation coefficient D between the neutron polarization vector and the electron and antineutrino momentum vectors. A nonzero value for this coefficient would imply T violation, since final-state interactions and other corrections may be neglected at the present level of precision. The experiment was performed using a cold-neutron beam at the High Flux Reactor of the Institut Laue-Langevin, Grenoble. A polarizing neutron guide tube yielded a beam intensity of 10 9 neutrons/sec with a polarization of 70%. Our result, based upon observation of approximately 6 x 10 6 decays, is D = (-1.1 +- 1.7) x 10 -3 , consistent with time-reversal invariance in the ΔS = 0 weak interaction. In terms of the relative phase angle between axial-vector and vector coupling constants, the result may be expressed as phi = 180.14 +- 0.22 0

On the problem of non-zero word error rates for fixed-rate error correction codes in continuous variable quantum key distribution

International Nuclear Information System (INIS)

Johnson, Sarah J; Ong, Lawrence; Shirvanimoghaddam, Mahyar; Lance, Andrew M; Symul, Thomas; Ralph, T C

2017-01-01

The maximum operational range of continuous variable quantum key distribution protocols has shown to be improved by employing high-efficiency forward error correction codes. Typically, the secret key rate model for such protocols is modified to account for the non-zero word error rate of such codes. In this paper, we demonstrate that this model is incorrect: firstly, we show by example that fixed-rate error correction codes, as currently defined, can exhibit efficiencies greater than unity. Secondly, we show that using this secret key model combined with greater than unity efficiency codes, implies that it is possible to achieve a positive secret key over an entanglement breaking channel—an impossible scenario. We then consider the secret key model from a post-selection perspective, and examine the implications for key rate if we constrain the forward error correction codes to operate at low word error rates. (paper)

Ab Initio Thermodynamic Modeling of Electrified Metal–Oxide Interfaces: Consistent Treatment of Electronic and Ionic Chemical Potentials

DEFF Research Database (Denmark)

Zeng, Zhenhua; Hansen, Martin Hangaard; Greeley, Jeffrey Philip

2014-01-01

. In this paper we present a scheme to determine the metal–oxide interface structure at a given set of these environmental parameters based on quantum chemical calculations. As an illustration we determine the structure of a Ni-YSZ anode as a function of electrode potential at 0 and 1000 K. We further describe...

Flavour equilibration studies of quark-gluon plasma with non-zero ...

Indian Academy of Sciences (India)

Abstract. Flavour equilibration for a thermally equilibrated but chemically non- equilibrated quark-gluon plasma is presented. Flavour equilibration is studied enforcing baryon number conservation. In addition to the usual processes like single additional gluon production gg ⇌ ggg and its reverse and quark–antiquark pair ...

Theory for disordered phase in Heisenberg and non-Heisenberg two-dimensional S=1 ferromagnets

International Nuclear Information System (INIS)

Spirin, D.V.; Fridman, Yu.A.

2003-01-01

We apply a modification of self-consistent spin-wave theory to investigation of two-dimensional S=1 isotropic Heisenberg and non-Heisenberg ferromagnets at nonzero temperatures. We use Hubbard operators method and bosonization technique. We calculated chemical potential and found dependence of correlation length on temperature. Specific heat has Schottky-type peak and decreases at high temperatures. Disordered phase in non-Heisenberg ferromagnet is also studied. The results for such a model differ from those of Heisenberg one

The Effect of Nonzero Autocorrelation Coefficients on the Distributions of Durbin-Watson Test Estimator: Three Autoregressive Models

Directory of Open Access Journals (Sweden)

Mei-Yu LEE

2014-11-01

Full Text Available This paper investigates the effect of the nonzero autocorrelation coefficients on the sampling distributions of the Durbin-Watson test estimator in three time-series models that have different variance-covariance matrix assumption, separately. We show that the expected values and variances of the Durbin-Watson test estimator are slightly different, but the skewed and kurtosis coefficients are considerably different among three models. The shapes of four coefficients are similar between the Durbin-Watson model and our benchmark model, but are not the same with the autoregressive model cut by one-lagged period. Second, the large sample case shows that the three models have the same expected values, however, the autoregressive model cut by one-lagged period explores different shapes of variance, skewed and kurtosis coefficients from the other two models. This implies that the large samples lead to the same expected values, 2(1 – ρ0, whatever the variance-covariance matrix of the errors is assumed. Finally, comparing with the two sample cases, the shape of each coefficient is almost the same, moreover, the autocorrelation coefficients are negatively related with expected values, are inverted-U related with variances, are cubic related with skewed coefficients, and are U related with kurtosis coefficients.

Non-Chemical Stressors and Cumulative Risk Assessment: An Overview of Current Initiatives and Potential Air Pollutant Interactions

Science.gov (United States)

Lewis, Ari S.; Sax, Sonja N.; Wason, Susan C.; Campleman, Sharan L.

2011-01-01

Regulatory agencies are under increased pressure to consider broader public health concerns that extend to multiple pollutant exposures, multiple exposure pathways, and vulnerable populations. Specifically, cumulative risk assessment initiatives have stressed the importance of considering both chemical and non-chemical stressors, such as socioeconomic status (SES) and related psychosocial stress, in evaluating health risks. The integration of non-chemical stressors into a cumulative risk assessment framework has been largely driven by evidence of health disparities across different segments of society that may also bear a disproportionate risk from chemical exposures. This review will discuss current efforts to advance the field of cumulative risk assessment, highlighting some of the major challenges, discussed within the construct of the traditional risk assessment paradigm. Additionally, we present a summary of studies of potential interactions between social stressors and air pollutants on health as an example of current research that supports the incorporation of non-chemical stressors into risk assessment. The results from these studies, while suggestive of possible interactions, are mixed and hindered by inconsistent application of social stress indicators. Overall, while there have been significant advances, further developments across all of the risk assessment stages (i.e., hazard identification, exposure assessment, dose-response, and risk characterization) are necessary to provide a scientific basis for regulatory actions and effective community interventions, particularly when considering non-chemical stressors. A better understanding of the biological underpinnings of social stress on disease and implications for chemical-based dose-response relationships is needed. Furthermore, when considering non-chemical stressors, an appropriate metric, or series of metrics, for risk characterization is also needed. Cumulative risk assessment research will benefit

Fluctuations and correlations of conserved charges near the QCD critical point

International Nuclear Information System (INIS)

Fu Weijie; Wu Yueliang

2010-01-01

We study the fluctuations and correlations of conserved charges, such as the baryon number, the electric charge and the strangeness, at the finite temperature and the nonzero baryon chemical potential in an effective model. The fluctuations are calculated up to the fourth-order and the correlations to the third-order. We find that the second-order fluctuations and correlations have a peak or valley structure when the chiral phase transition takes place with the increase of the baryon chemical potential; the third-order fluctuations and correlations change their signs during the chiral phase transition; and the fourth-order fluctuations have two maxima and one minimum. We also depict contour plots of various fluctuations and correlations of conserved charges in the plane of temperature and the baryon chemical potential. It is found that higher-order fluctuations and correlations of conserved charges are superior to the second-order ones to be used to search for the critical point in heavy ion collision experiments.

Chemical Potential for the Interacting Classical Gas and the Ideal Quantum Gas Obeying a Generalized Exclusion Principle

Science.gov (United States)

Sevilla, F. J.; Olivares-Quiroz, L.

2012-01-01

In this work, we address the concept of the chemical potential [mu] in classical and quantum gases towards the calculation of the equation of state [mu] = [mu](n, T) where n is the particle density and "T" the absolute temperature using the methods of equilibrium statistical mechanics. Two cases seldom discussed in elementary textbooks are…

Landfill mining: Resource potential of Austrian landfills--Evaluation and quality assessment of recovered municipal solid waste by chemical analyses.

Science.gov (United States)

Wolfsberger, Tanja; Aldrian, Alexia; Sarc, Renato; Hermann, Robert; Höllen, Daniel; Budischowsky, Andreas; Zöscher, Andreas; Ragoßnig, Arne; Pomberger, Roland

2015-11-01

Since the need for raw materials in countries undergoing industrialisation (like China) is rising, the availability of metal and fossil fuel energy resources (like ores or coal) has changed in recent years. Landfill sites can contain considerable amounts of recyclables and energy-recoverable materials, therefore, landfill mining is an option for exploiting dumped secondary raw materials, saving primary sources. For the purposes of this article, two sanitary landfill sites have been chosen for obtaining actual data to determine the resource potential of Austrian landfills. To evaluate how pretreating waste before disposal affects the resource potential of landfills, the first landfill site has been selected because it has received untreated waste, whereas mechanically-biologically treated waste was dumped in the second. The scope of this investigation comprised: (1) waste characterisation by sorting analyses of recovered waste; and (2) chemical analyses of specific waste fractions for quality assessment regarding potential energy recovery by using it as solid recovered fuels. The content of eight heavy metals and the net calorific values were determined for the chemical characterisation tests. © The Author(s) 2015.

Assessment of the technical and economic potentials of biomass use for the production of steam, chemicals and polymers

NARCIS (Netherlands)

Saygin, D.; Gielen, D. J.; Draeck, M.; Worrell, E.; Patel, M. K.

2014-01-01

Fossil fuel substitution with biomass is one of the measures to reduce carbon dioxide (CO2) emissions. This paper estimates the cost-effectiveness of raising industrial steam and producing materials (i.e. chemicals, polymers) from biomass. We quantify their long-term global potentials in terms of

A comparison of chemical mechanisms using tagged ozone production potential (TOPP analysis

Directory of Open Access Journals (Sweden)

J. Coates

2015-08-01

Full Text Available Ground-level ozone is a secondary pollutant produced photochemically from reactions of NOx with peroxy radicals produced during volatile organic compound (VOC degradation. Chemical transport models use simplified representations of this complex gas-phase chemistry to predict O3 levels and inform emission control strategies. Accurate representation of O3 production chemistry is vital for effective prediction. In this study, VOC degradation chemistry in simplified mechanisms is compared to that in the near-explicit Master Chemical Mechanism (MCM using a box model and by "tagging" all organic degradation products over multi-day runs, thus calculating the tagged ozone production potential (TOPP for a selection of VOCs representative of urban air masses. Simplified mechanisms that aggregate VOC degradation products instead of aggregating emitted VOCs produce comparable amounts of O3 from VOC degradation to the MCM. First-day TOPP values are similar across mechanisms for most VOCs, with larger discrepancies arising over the course of the model run. Aromatic and unsaturated aliphatic VOCs have the largest inter-mechanism differences on the first day, while alkanes show largest differences on the second day. Simplified mechanisms break VOCs down into smaller-sized degradation products on the first day faster than the MCM, impacting the total amount of O3 produced on subsequent days due to secondary chemistry.

A density functional theory-based chemical potential equalisation ...

Indian Academy of Sciences (India)

Unknown

ties both of which can be calculated through the evaluation of ... used widely for the understanding of chemical binding, reactivity ... lent binding. There have ..... where ε represents a measure of the dielectric con- stant of the ..... field strength.

A Rat α-Fetoprotein Binding Activity Prediction Model to Facilitate Assessment of the Endocrine Disruption Potential of Environmental Chemicals.

Science.gov (United States)

Hong, Huixiao; Shen, Jie; Ng, Hui Wen; Sakkiah, Sugunadevi; Ye, Hao; Ge, Weigong; Gong, Ping; Xiao, Wenming; Tong, Weida

2016-03-25

Endocrine disruptors such as polychlorinated biphenyls (PCBs), diethylstilbestrol (DES) and dichlorodiphenyltrichloroethane (DDT) are agents that interfere with the endocrine system and cause adverse health effects. Huge public health concern about endocrine disruptors has arisen. One of the mechanisms of endocrine disruption is through binding of endocrine disruptors with the hormone receptors in the target cells. Entrance of endocrine disruptors into target cells is the precondition of endocrine disruption. The binding capability of a chemical with proteins in the blood affects its entrance into the target cells and, thus, is very informative for the assessment of potential endocrine disruption of chemicals. α-fetoprotein is one of the major serum proteins that binds to a variety of chemicals such as estrogens. To better facilitate assessment of endocrine disruption of environmental chemicals, we developed a model for α-fetoprotein binding activity prediction using the novel pattern recognition method (Decision Forest) and the molecular descriptors calculated from two-dimensional structures by Mold² software. The predictive capability of the model has been evaluated through internal validation using 125 training chemicals (average balanced accuracy of 69%) and external validations using 22 chemicals (balanced accuracy of 71%). Prediction confidence analysis revealed the model performed much better at high prediction confidence. Our results indicate that the model is useful (when predictions are in high confidence) in endocrine disruption risk assessment of environmental chemicals though improvement by increasing number of training chemicals is needed.

Variations in amounts and potential sources of volatile organic chemicals in new cars

International Nuclear Information System (INIS)

Chien, Y.-C.

2007-01-01

This study examines inter-brand, intra-brand and intra-model variations in volatile organic chemical (VOC) levels inside new cars. The effect of temperature on interior VOC levels was examined using model automobiles with and without the air-conditioning running. Potential sources of VOC were assessed by comparing VOC levels with two interior trims (leather and fabric) and by analyzing VOC emissions from various interior components. Five brands of new car, both domestic and imported, were tested. Twelve targeted VOCs were collected on solid sorbents and analyzed using thermal desorption and GC/FID. VOCs from interior parts and adhesives were identified using solid phase micro-extraction (SPME) coupled with GC/MS. The VOC concentrations varied markedly among brands and within models, and individual VOC levels ranged from below the detection limit (a few μg per cubic meter) to thousands of μg per cubic meter. The intra-model variability (mean, 47%) in the VOC levels was approximately 50% that within each brand (mean, 95%). Although interior trim levels affected VOC levels, the effects differed among brands. Reduction of the cabin temperature reduced most VOC levels, but the impact was not statistically significant. Screening tests for VOCs from interior parts revealed that butylated hydroxytoluene (BHT), a common anti-oxidant, was the most common chemical. Long-chain aliphatic hydrocarbons, particularly C14-C17, were identified in most grease (lubricant) samples, and toluene and xylenes were ubiquitously present in adhesive samples. Process-related compounds, such as plasticizer, were also identified in interior parts. In-cabin VOC levels varied significantly among makes/models and interior trims. Concerned consumers should purchase older new cars from manufacturers since VOC levels inside car cabins normally declines over time. Improved processes or materials with lower VOC emission potential should be used to minimize in-cabin VOC sources for new cars

Constraints on continental crustal mass loss via chemical weathering using lithium and its isotopes

Science.gov (United States)

Rudnick, R. L.; Liu, X. M.

2012-04-01

The continental crust has an "intermediate" bulk composition that is distinct from primary melts of peridotitic mantle (basalt or picrite). This mismatch between the "building blocks" and the "edifice" that is the continental crust points to the operation of processes that preferentially remove mafic to ultramafic material from the continents. Such processes include lower crustal recycling (via density foundering or lower crustal subduction - e.g., relamination, Hacker et al., 2011, EPSL), generation of evolved melts via slab melting, and/or chemical weathering. Stable isotope systems point to the influence of chemical weathering on the bulk crust composition: the oxygen isotope composition of the bulk crust is distinctly heavier than that of primary, mantle-derived melts (Simon and Lecuyer, 2005, G-cubed) and the Li isotopic composition of the bulk crust is distinctly lighter than that of mantle-derive melts (Teng et al., 2004, GCA; 2008, Chem. Geol.). Both signatures mark the imprint of chemical weathering on the bulk crust composition. Here, we use a simple mass balance model for lithium inputs and outputs from the continental crust to quantify the mass lost due to chemical weathering. We find that a minimum of 15%, a maximum of 60%, and a best estimate of ~40% of the original juvenile rock mass may have been lost via chemical weathering. The accumulated percentage of mass loss due to chemical weathering leads to an average global chemical weathering rate (CWR) of ~ 1×10^10 to 2×10^10 t/yr since 3.5 Ga, which is about an order of magnitude higher than the minimum estimates based on modern rivers (Gaillardet et al., 1999, Chem. Geol.). While we cannot constrain the exact portion of crustal mass loss via chemical weathering, given the uncertainties of the calculation, we can demonstrate that the weathering flux is non-zero. Therefore, chemical weathering must play a role in the evolution of the composition and mass of the continental crust.

Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: focus on the cancer hallmark of tumor angiogenesis.

Science.gov (United States)

Hu, Zhiwei; Brooks, Samira A; Dormoy, Valérian; Hsu, Chia-Wen; Hsu, Hsue-Yin; Lin, Liang-Tzung; Massfelder, Thierry; Rathmell, W Kimryn; Xia, Menghang; Al-Mulla, Fahd; Al-Temaimi, Rabeah; Amedei, Amedeo; Brown, Dustin G; Prudhomme, Kalan R; Colacci, Annamaria; Hamid, Roslida A; Mondello, Chiara; Raju, Jayadev; Ryan, Elizabeth P; Woodrick, Jordan; Scovassi, A Ivana; Singh, Neetu; Vaccari, Monica; Roy, Rabindra; Forte, Stefano; Memeo, Lorenzo; Salem, Hosni K; Lowe, Leroy; Jensen, Lasse; Bisson, William H; Kleinstreuer, Nicole

2015-06-01

One of the important 'hallmarks' of cancer is angiogenesis, which is the process of formation of new blood vessels that are necessary for tumor expansion, invasion and metastasis. Under normal physiological conditions, angiogenesis is well balanced and controlled by endogenous proangiogenic factors and antiangiogenic factors. However, factors produced by cancer cells, cancer stem cells and other cell types in the tumor stroma can disrupt the balance so that the tumor microenvironment favors tumor angiogenesis. These factors include vascular endothelial growth factor, endothelial tissue factor and other membrane bound receptors that mediate multiple intracellular signaling pathways that contribute to tumor angiogenesis. Though environmental exposures to certain chemicals have been found to initiate and promote tumor development, the role of these exposures (particularly to low doses of multiple substances), is largely unknown in relation to tumor angiogenesis. This review summarizes the evidence of the role of environmental chemical bioactivity and exposure in tumor angiogenesis and carcinogenesis. We identify a number of ubiquitous (prototypical) chemicals with disruptive potential that may warrant further investigation given their selectivity for high-throughput screening assay targets associated with proangiogenic pathways. We also consider the cross-hallmark relationships of a number of important angiogenic pathway targets with other cancer hallmarks and we make recommendations for future research. Understanding of the role of low-dose exposure of chemicals with disruptive potential could help us refine our approach to cancer risk assessment, and may ultimately aid in preventing cancer by reducing or eliminating exposures to synergistic mixtures of chemicals with carcinogenic potential. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Chemical, Bioactive, and Antioxidant Potential of Twenty Wild Culinary Mushroom Species

Science.gov (United States)

Sharma, S. K.; Gautam, N.

2015-01-01

The chemical, bioactive, and antioxidant potential of twenty wild culinary mushroom species being consumed by the people of northern Himalayan regions has been evaluated for the first time in the present study. Nutrients analyzed include protein, crude fat, fibres, carbohydrates, and monosaccharides. Besides, preliminary study on the detection of toxic compounds was done on these species. Bioactive compounds evaluated are fatty acids, amino acids, tocopherol content, carotenoids (β-carotene, lycopene), flavonoids, ascorbic acid, and anthocyanidins. Fruitbodies extract of all the species was tested for different types of antioxidant assays. Although differences were observed in the net values of individual species all the species were found to be rich in protein, and carbohydrates and low in fat. Glucose was found to be the major monosaccharide. Predominance of UFA (65–70%) over SFA (30–35%) was observed in all the species with considerable amounts of other bioactive compounds. All the species showed higher effectiveness for antioxidant capacities. PMID:26199938

Chemical, Bioactive, and Antioxidant Potential of Twenty Wild Culinary Mushroom Species

Directory of Open Access Journals (Sweden)

S. K. Sharma

2015-01-01

Full Text Available The chemical, bioactive, and antioxidant potential of twenty wild culinary mushroom species being consumed by the people of northern Himalayan regions has been evaluated for the first time in the present study. Nutrients analyzed include protein, crude fat, fibres, carbohydrates, and monosaccharides. Besides, preliminary study on the detection of toxic compounds was done on these species. Bioactive compounds evaluated are fatty acids, amino acids, tocopherol content, carotenoids (β-carotene, lycopene, flavonoids, ascorbic acid, and anthocyanidins. Fruitbodies extract of all the species was tested for different types of antioxidant assays. Although differences were observed in the net values of individual species all the species were found to be rich in protein, and carbohydrates and low in fat. Glucose was found to be the major monosaccharide. Predominance of UFA (65–70% over SFA (30–35% was observed in all the species with considerable amounts of other bioactive compounds. All the species showed higher effectiveness for antioxidant capacities.

Chemical, Bioactive, and Antioxidant Potential of Twenty Wild Culinary Mushroom Species.

Science.gov (United States)

Sharma, S K; Gautam, N

2015-01-01

The chemical, bioactive, and antioxidant potential of twenty wild culinary mushroom species being consumed by the people of northern Himalayan regions has been evaluated for the first time in the present study. Nutrients analyzed include protein, crude fat, fibres, carbohydrates, and monosaccharides. Besides, preliminary study on the detection of toxic compounds was done on these species. Bioactive compounds evaluated are fatty acids, amino acids, tocopherol content, carotenoids (β-carotene, lycopene), flavonoids, ascorbic acid, and anthocyanidins. Fruitbodies extract of all the species was tested for different types of antioxidant assays. Although differences were observed in the net values of individual species all the species were found to be rich in protein, and carbohydrates and low in fat. Glucose was found to be the major monosaccharide. Predominance of UFA (65-70%) over SFA (30-35%) was observed in all the species with considerable amounts of other bioactive compounds. All the species showed higher effectiveness for antioxidant capacities.

Nonlinear image encryption using a fully phase nonzero-order joint transform correlator in the Gyrator domain

Science.gov (United States)

Vilardy, Juan M.; Millán, María S.; Pérez-Cabré, Elisabet

2017-02-01

A novel nonlinear image encryption scheme based on a fully phase nonzero-order joint transform correlator architecture (JTC) in the Gyrator domain (GD) is proposed. In this encryption scheme, the two non-overlapping data distributions of the input plane of the JTC are fully encoded in phase and this input plane is transformed using the Gyrator transform (GT); the intensity distribution captured in the GD represents a new definition of the joint Gyrator power distribution (JGPD). The JGPD is modified by two nonlinear operations with the purpose of retrieving the encrypted image, with enhancement of the decrypted signal quality and improvement of the overall security. There are three keys used in the encryption scheme, two random phase masks and the rotation angle of the GT, which are all necessary for a proper decryption. Decryption is highly sensitivity to changes of the rotation angle of the GT as well as to little changes in other parameters or keys. The proposed encryption scheme in the GD still preserves the shift-invariance properties originated in the JTC-based encryption in the Fourier domain. The proposed encryption scheme is more resistant to brute force attacks, chosen-plaintext attacks, known-plaintext attacks, and ciphertext-only attacks, as they have been introduced in the cryptanalysis of the JTC-based encryption system. Numerical results are presented and discussed in order to verify and analyze the feasibility and validity of the novel encryption-decryption scheme.

National prevalence of asthma and chemical hypersensitivity: an examination of potential overlap.

Science.gov (United States)

Caress, Stanley M; Steinemann, Anne C

2005-05-01

The objective of this study was to investigate the linkage between asthma and chemical hypersensitivity. The authors conducted a population study with a random sample of 1057 geographically weighted cases to determine the prevalence of both asthma and chemical hypersensitivity in the American population and to explore their co-occurrence. A total of 14.1% of the respondents reported being diagnosed with asthma and 11.2% reported a hypersensitivity to chemicals. Of those with asthma, 27.2% also reported being hypersensitive to chemicals and 7.4% reported also being diagnosed with multiple chemical sensitivities (MCS). Of those diagnosed with MCS, 42% reported also being diagnosed with asthma. Additionally, 29.7% of those with asthma said air fresheners caused breathing difficulties, and 37.2% found scented products irritating. The results indicate that there is significant overlap between some forms of asthma and chemical hypersensitivity.

Chemical Analysis of Extracts from Newfoundland Berries and Potential Neuroprotective Effects

Directory of Open Access Journals (Sweden)

Mohammad Z. Hossain

2016-10-01

Full Text Available Various species of berries have been reported to contain several polyphenolic compounds, such as anthocyanins and flavonols, which are known to possess high antioxidant activity and may be beneficial for human health. To our knowledge, a thorough chemical analysis of polyphenolics in species of these plants native to Newfoundland, Canada has not been conducted. The primary objective of this study was to determine the polyphenolic compounds present in commercial extracts from Newfoundland berries, which included blueberries (V. angustifolium, lingonberries (V. vitis-idaea and black currant (Ribes lacustre. Anthocyanin and flavonol glycosides in powdered extracts from Ribes lacustre and the Vaccinium species were identified using the high performance liquid chromatographic (HPLC separation method with mass spectrometric (MS detection. The identified compounds were extracted from dried berries by various solvents via ultrasonication followed by centrifugation. A reverse-phase analytical column was employed to identify the retention time of each chemical component before submission for LC–MS analysis. A total of 21 phenolic compounds were tentatively identified in the three species. Further, we tested the effects of the lingonberry extract for its ability to protect neurons and glia from trauma utilizing an in vitro model of cell injury. Surprisingly, these extracts provided complete protection from cell death in this model. These findings indicate the presence of a wide variety of anthocyanins and flavonols in berries that grow natively in Newfoundland. These powdered extracts maintain these compounds intact despite being processed from berry fruit, indicating their potential use as dietary supplements. In addition, these recent findings and previous data from our lab demonstrate the ability of compounds in berries to protect the nervous system from traumatic insults.

Potentialities of Revised Quantum Electrodynamics

Directory of Open Access Journals (Sweden)

Lehnert B.

2013-10-01

Full Text Available The potentialities of a revised quantum electrodynamic theory (RQED earlier established by the author are reconsidered, also in respect to other fundamental theories such as those by Dirac and Higgs. The RQED theory is characterized by intrinsic linear symmetry breaking due to a nonzero divergence of the electric field strength in the vacuum state, as supported by the Zero Point Energy and the experimentally confirmed Casimir force. It includes the results of electron spin and antimatter by Dirac, as well as the rest mass of elementary particles predicted by Higgs in terms of spontaneous nonlinear symmetry breaking. It will here be put into doubt whether the approach by Higgs is the only theory which becomes necessary for explaining the particle rest masses. In addition, RQED theory leads to new results beyond those being available from the theories by Dirac, Higgs and the Standard Model, such as in applications to leptons and the photon.

Intrinsic potential of cell membranes: opposite effects of lipid transmembrane asymmetry and asymmetric salt ion distribution

DEFF Research Database (Denmark)

Gurtovenko, Andrey A; Vattulainen, Ilpo

2009-01-01

Using atomic-scale molecular dynamics simulations, we consider the intrinsic cell membrane potential that is found to originate from a subtle interplay between lipid transmembrane asymmetry and the asymmetric distribution of monovalent salt ions on the two sides of the cell membrane. It turns out......Cl saline solution and the PE leaflet is exposed to KCl, the outcome is that the effects of asymmetric lipid and salt ion distributions essentially cancel one another almost completely. Overall, our study highlights the complex nature of the intrinsic potential of cell membranes under physiological...... that both the asymmetric distribution of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) lipids across a membrane and the asymmetric distribution of NaCl and KCl induce nonzero drops in the transmembrane potential. However, these potential drops are opposite in sign. As the PC leaflet faces a Na...

Lattice studies of quark spectra and supersymmetric quantum mechanics

International Nuclear Information System (INIS)

Schierenberg, Sebastian

2012-01-01

In the first part of this work, we study quark spectra at either non-zero temperature or chemical potential. In the first case, we find a possible explanation for the Anderson localization that is observed in the spectrum. We introduce a random matrix model that has the same localization and shares other important properties of the QCD Dirac operator, too. In the case of a non-vanishing chemical potential, we show that the eigenvalue spacing distributions of the Dirac operator are described by simple random matrix models. In the second part of this work, we study supersymmetry on the lattice. We summarize our progress with the blocking approach and show possible problems. Furthermore, we construct a lattice action which is improved with respect to supersymmetry and study this action numerically.

Lattice studies of quark spectra and supersymmetric quantum mechanics

Energy Technology Data Exchange (ETDEWEB)

Schierenberg, Sebastian

2012-06-24

In the first part of this work, we study quark spectra at either non-zero temperature or chemical potential. In the first case, we find a possible explanation for the Anderson localization that is observed in the spectrum. We introduce a random matrix model that has the same localization and shares other important properties of the QCD Dirac operator, too. In the case of a non-vanishing chemical potential, we show that the eigenvalue spacing distributions of the Dirac operator are described by simple random matrix models. In the second part of this work, we study supersymmetry on the lattice. We summarize our progress with the blocking approach and show possible problems. Furthermore, we construct a lattice action which is improved with respect to supersymmetry and study this action numerically.

Prediction of rodent carcinogenic potential of naturally occurring chemicals in the human diet using high-throughput QSAR predictive modeling

International Nuclear Information System (INIS)

Valerio, Luis G.; Arvidson, Kirk B.; Chanderbhan, Ronald F.; Contrera, Joseph F.

2007-01-01

Consistent with the U.S. Food and Drug Administration (FDA) Critical Path Initiative, predictive toxicology software programs employing quantitative structure-activity relationship (QSAR) models are currently under evaluation for regulatory risk assessment and scientific decision support for highly sensitive endpoints such as carcinogenicity, mutagenicity and reproductive toxicity. At the FDA's Center for Food Safety and Applied Nutrition's Office of Food Additive Safety and the Center for Drug Evaluation and Research's Informatics and Computational Safety Analysis Staff (ICSAS), the use of computational SAR tools for both qualitative and quantitative risk assessment applications are being developed and evaluated. One tool of current interest is MDL-QSAR predictive discriminant analysis modeling of rodent carcinogenicity, which has been previously evaluated for pharmaceutical applications by the FDA ICSAS. The study described in this paper aims to evaluate the utility of this software to estimate the carcinogenic potential of small, organic, naturally occurring chemicals found in the human diet. In addition, a group of 19 known synthetic dietary constituents that were positive in rodent carcinogenicity studies served as a control group. In the test group of naturally occurring chemicals, 101 were found to be suitable for predictive modeling using this software's discriminant analysis modeling approach. Predictions performed on these compounds were compared to published experimental evidence of each compound's carcinogenic potential. Experimental evidence included relevant toxicological studies such as rodent cancer bioassays, rodent anti-carcinogenicity studies, genotoxic studies, and the presence of chemical structural alerts. Statistical indices of predictive performance were calculated to assess the utility of the predictive modeling method. Results revealed good predictive performance using this software's rodent carcinogenicity module of over 1200 chemicals

NMR analysis of male fathead minnow urinary metabolites: A potential approach for studying impacts of chemical exposures

Energy Technology Data Exchange (ETDEWEB)

Ekman, D.R. [Ecosystems Research Division, U.S. EPA, 960 College Station Road, Athens, GA 30605 (United States)], E-mail: ekman.drew@epa.gov; Teng, Q. [Ecosystems Research Division, U.S. EPA, 960 College Station Road, Athens, GA 30605 (United States); Jensen, K.M.; Martinovic, D.; Villeneuve, D.L.; Ankley, G.T. [Mid-Continent Ecology Division, U.S. EPA, 6201 Congdon Boulevard, Duluth, MN 55804 (United States); Collette, T.W. [Ecosystems Research Division, U.S. EPA, 960 College Station Road, Athens, GA 30605 (United States)

2007-11-30

The potential for profiling metabolites in urine from male fathead minnows (Pimephales promelas) to assess chemical exposures was explored using nuclear magnetic resonance (NMR) spectroscopy. Both one-dimensional (1D) and two-dimensional (2D) NMR spectroscopy was used for the assignment of metabolites in urine from unexposed fish. Because fathead minnow urine is dilute, we lyophilized these samples prior to analysis. Furthermore, 1D {sup 1}H NMR spectra of unlyophilized urine from unexposed male fathead minnow and Sprague-Dawley rat were acquired to qualitatively compare rat and fish metabolite profiles and to provide an estimate of the total urinary metabolite pool concentration difference. As a small proof-of-concept study, lyophilized urine samples from male fathead minnows exposed to three different concentrations of the antiandrogen vinclozolin were analyzed by 1D {sup 1}H NMR to assess exposure-induced changes. Through a combination of principal components analysis (PCA) and measurements of {sup 1}H NMR peak intensities, several metabolites were identified as changing with statistical significance in response to exposure. Among those changes occurring in response to exposure to the highest concentration (450 {mu}g/L) of vinclozolin were large increases in taurine, lactate, acetate, and formate. These increases coincided with a marked decrease in hippurate, a combination potentially indicative of hepatotoxicity. The results of these investigations clearly demonstrate the potential utility of an NMR-based approach for assessing chemical exposures in male fathead minnow, using urine collected from individual fish.

NMR analysis of male fathead minnow urinary metabolites: A potential approach for studying impacts of chemical exposures

International Nuclear Information System (INIS)

Ekman, D.R.; Teng, Q.; Jensen, K.M.; Martinovic, D.; Villeneuve, D.L.; Ankley, G.T.; Collette, T.W.

2007-01-01

The potential for profiling metabolites in urine from male fathead minnows (Pimephales promelas) to assess chemical exposures was explored using nuclear magnetic resonance (NMR) spectroscopy. Both one-dimensional (1D) and two-dimensional (2D) NMR spectroscopy was used for the assignment of metabolites in urine from unexposed fish. Because fathead minnow urine is dilute, we lyophilized these samples prior to analysis. Furthermore, 1D 1 H NMR spectra of unlyophilized urine from unexposed male fathead minnow and Sprague-Dawley rat were acquired to qualitatively compare rat and fish metabolite profiles and to provide an estimate of the total urinary metabolite pool concentration difference. As a small proof-of-concept study, lyophilized urine samples from male fathead minnows exposed to three different concentrations of the antiandrogen vinclozolin were analyzed by 1D 1 H NMR to assess exposure-induced changes. Through a combination of principal components analysis (PCA) and measurements of 1 H NMR peak intensities, several metabolites were identified as changing with statistical significance in response to exposure. Among those changes occurring in response to exposure to the highest concentration (450 μg/L) of vinclozolin were large increases in taurine, lactate, acetate, and formate. These increases coincided with a marked decrease in hippurate, a combination potentially indicative of hepatotoxicity. The results of these investigations clearly demonstrate the potential utility of an NMR-based approach for assessing chemical exposures in male fathead minnow, using urine collected from individual fish

Marine chemical technology and sensors for marine waters: potentials and limits.

Science.gov (United States)

Moore, Tommy S; Mullaugh, Katherine M; Holyoke, Rebecca R; Madison, Andrew S; Yücel, Mustafa; Luther, George W

2009-01-01

A significant need exists for in situ sensors that can measure chemical species involved in the major processes of primary production (photosynthesis and chemosynthesis) and respiration. Some key chemical species are O2, nutrients (N and P), micronutrients (metals), pCO2, dissolved inorganic carbon (DIC), pH, and sulfide. Sensors need to have excellent detection limits, precision, selectivity, response time, a large dynamic concentration range, low power consumption, robustness, and less variation of instrument response with temperature and pressure, as well as be free from fouling problems (biological, physical, and chemical). Here we review the principles of operation of most sensors used in marine waters. We also show that some sensors can be used in several different oceanic environments to detect the target chemical species, whereas others are useful in only one environment because of various limitations. Several sensors can be used truly in situ, whereas many others involve water brought into a flow cell via tubing to the analyzer in the environment or aboard ship. Multi-element sensors that measure many chemical species in the same water mass should be targeted for further development.

Chemical composition and evaluation of allelopathic potentials of Adiantum tetraphyllum Humb.and Bonpl. Ex. Willd (Pteridaceae)

International Nuclear Information System (INIS)

Melos, Jorge L.R.; Silva, Luciana B.; Peres, Marize T. L. P.; Mapeli, Ana M.; Faccenda, Odival; Anjos, Hatino H.; Torres, Thais G.; Tiviroli, Soraia C.; Batista, Ana L.; Almeida, Felipe G. N.; Flauzino, Natasha S.; Tibana, Leticia A.; Hess, Sonia C.; Honda, Neli K.

2007-01-01

Chemical studies of green leaves of A. tetraphyllum afforded β-sitosterol, a mixture containing the ethyl esters of long chain carboxylic acids, 30-normethyl-lupan-20-one, hopan-22-ol, phytol, phyten-3(20)-1,2-diol, quercetin and quercetin-3-O-β-D-glucoside. The structures of the compounds were elucidated by spectroscopic and GC analysis. The allelopathic potentials of the crude ethanolic extract and fractions were evaluated against Lactuca sativa (letuce) and Allium cepa (onion) seeds. (author)

Evolutionary potential of root chemical defense: genetic correlations with shoot chemistry and plant growth.

Science.gov (United States)

Parker, J D; Salminen, J-P; Agrawal, Anurag A

2012-08-01

Root herbivores can affect plant fitness, and roots often contain the same secondary metabolites that act as defenses in shoots, but the ecology and evolution of root chemical defense have been little investigated. Here, we investigated genetic variance, heritability, and correlations among defensive phenolic compounds in shoot vs. root tissues of common evening primrose, Oenothera biennis. Across 20 genotypes, there were roughly similar concentrations of total phenolics in shoots vs. roots, but the allocation of particular phenolics to shoots vs. roots varied along a continuum of genotype growth rate. Slow-growing genotypes allocated 2-fold more of the potential pro-oxidant oenothein B to shoots than roots, whereas fast-growing genotypes had roughly equivalent above and belowground concentrations. Phenolic concentrations in both roots and shoots were strongly heritable, with mostly positive patterns of genetic covariation. Nonetheless, there was genotype-specific variation in the presence/absence of two major ellagitannins (oenothein A and its precursor oenothein B), indicating two different chemotypes based on alterations in this chemical pathway. Overall, the presence of strong genetic variation in root defenses suggests ample scope for the evolution of these compounds as defenses against root herbivores.

Characterization and pyrolysis of Chlorella vulgaris and Arthrospira platensis: potential of bio-oil and chemical production by Py-GC/MS analysis.

Science.gov (United States)

Almeida, Hanna N; Calixto, Guilherme Q; Chagas, Bruna M E; Melo, Dulce M A; Resende, Fabio M; Melo, Marcus A F; Braga, Renata Martins

2017-06-01

Biofuels have been seen as potential sources to meet future energy demand as a renewable and sustainable energy source. Despite the fact that the production technology of first-generation biofuels is consolidated, these biofuels are produced from foods crops such as grains, sugar cane, and vegetable oils competing with food for crop use and agricultural land. In recent years, it was found that microalgae have the potential to provide a viable alternative to fossil fuels as source of biofuels without compromising food supplies or arable land. On this scenario, this paper aims to demonstrate the energetic potential to produce bio-oil and chemicals from microalgae Chlorella vulgaris and Arthrospira platensis. The potential of these biomasses was evaluated in terms of physical-chemical characterization, thermogravimetric analysis, and analytical pyrolysis interfaced with gas chromatograph (Py-GC/MS). The results show that C. vulgaris and A. platensis are biomasses with a high heating value (24.60 and 22.43 MJ/kg) and low ash content, showing a high percentage of volatile matter (72.49 and 79.42%). These characteristics confirm their energetic potential for conversion process through pyrolysis, whereby some important aromatic compounds such as toluene, styrene, and phenol were identified as pyrolysis products, which could turn these microalgae a potential for biofuels and bioproduct production through the pyrolysis.

Xenognosin methylation is critical in defining the chemical potential gradient that regulates the potential distribution in Striga pathogenesis

Energy Technology Data Exchange (ETDEWEB)

Fate, G.D.; Lynn, D.G. [Univ. of Chicago, IL (United States)

1996-11-20

Striga asiatica (Scrophulariaceae) is a parasitic plant requiring a host-derived signal, xenognosin, to initiate a cascade of events necessary for the establishment of host contact. By attempting to model the distribution of the xenognosin around the host, the activity of the signal is shown to be strongly dependent on the presence of another component in the host exudate. Surprisingly this component, characterized as 4,6-dimethoxy-2-[(8`Z.11`Z)-8`,11`, -14`-pentadecatriene]resorcinol, is structurally related and shares the same biosynthetic pathway as the xenognosin. This compound is shown to function as an antioxidant and its ability to enhance the activity of the xenognosin is consistent with its ability to extend its lifetime in the exudate. This endogenous antioxidant activity is required to explain the spatial sensing in the establishment of the host-parasite interface and its characterization provides insight into how chemical potential may be regulated within and around plant tissues. 23 refs., 7 figs., 1 tab.

Chemical Industry Bandwidth Study

Energy Technology Data Exchange (ETDEWEB)

none,

2006-12-01

The Chemical Bandwidth Study provides a snapshot of potentially recoverable energy losses during chemical manufacturing. The advantage of this study is the use of "exergy" analysis as a tool for pinpointing inefficiencies.

Chemical contaminants in water and sediment near fish nesting sites in the Potomac River basin: determining potential exposures to smallmouth bass (Micropterus dolomieu).

Science.gov (United States)

Kolpin, Dana W; Blazer, Vicki S; Gray, James L; Focazio, Michael J; Young, John A; Alvarez, David A; Iwanowicz, Luke R; Foreman, William T; Furlong, Edward T; Speiran, Gary K; Zaugg, Steven D; Hubbard, Laura E; Meyer, Michael T; Sandstrom, Mark W; Barber, Larry B

2013-01-15

The Potomac River basin is an area where a high prevalence of abnormalities such as testicular oocytes (TO), skin lesions, and mortality has been observed in smallmouth bass (SMB, Micropterus dolomieu). Previous research documented a variety of chemicals in regional streams, implicating chemical exposure as one plausible explanation for these biological effects. Six stream sites in the Potomac basin (and one out-of-basin reference site) were sampled to provide an assessment of chemicals in these streams. Potential early life-stage exposure to chemicals detected was assessed by collecting samples in and around SMB nesting areas. Target chemicals included those known to be associated with important agricultural and municipal wastewater sources in the Potomac basin. The prevalence and severity of TO in SMB were also measured to determine potential relations between chemistry and biological effects. A total of 39 chemicals were detected at least once in the discrete-water samples, with atrazine, caffeine, deethylatrazine, simazine, and iso-chlorotetracycline being most frequently detected. Of the most frequently detected chemicals, only caffeine was detected in water from the reference site. No biogenic hormones/sterols were detected in the discrete-water samples. In contrast, 100 chemicals (including six biogenic hormones/sterols) were found in a least one passive-water sample, with 25 being detected at all such samples. In addition, 46 chemicals (including seven biogenic hormones/sterols) were found in the bed-sediment samples, with caffeine, cholesterol, indole, para-cresol, and sitosterol detected in all such samples. The number of herbicides detected in discrete-water samples per site had a significant positive relation to TO(rank) (a nonparametric indicator of TO), with significant positive relations between TO(rank) and atrazine concentrations in discrete-water samples and to total hormone/sterol concentration in bed-sediment samples. Such significant

Kinetics of spontaneous baryogenesis in non-stationary background

Directory of Open Access Journals (Sweden)

Arbuzova Elena

2016-01-01

Full Text Available Generation of the cosmological baryon asymmetry in frameworks of spontaneous baryogenesis is studied in detail. It is shown that the relation between baryonic chemical potential and the time derivative of the (pseudoGoldstone field essentially depends upon the representation chosen for the fermionic fields with non-zero baryonic number (quarks. Kinetic equation is modified and numerically solved in equilibrium for the case of time dependent external background or finite integration time to be applicable to the case when energy conservation law is formally violated.

Gravity dual of spin and charge density waves

Science.gov (United States)

Jokela, Niko; Järvinen, Matti; Lippert, Matthew

2014-12-01

At high enough charge density, the homogeneous state of the D3-D7' model is unstable to fluctuations at nonzero momentum. We investigate the end point of this instability, finding a spatially modulated ground state, which is a charge and spin density wave. We analyze the phase structure of the model as a function of chemical potential and magnetic field and find the phase transition from the homogeneous state to be first order, with a second-order critical point at zero magnetic field.

VirtualToxLab — A platform for estimating the toxic potential of drugs, chemicals and natural products

International Nuclear Information System (INIS)

Vedani, Angelo; Dobler, Max; Smieško, Martin

2012-01-01

The VirtualToxLab is an in silico technology for estimating the toxic potential (endocrine and metabolic disruption, some aspects of carcinogenicity and cardiotoxicity) of drugs, chemicals and natural products. The technology is based on an automated protocol that simulates and quantifies the binding of small molecules towards a series of proteins, known or suspected to trigger adverse effects. The toxic potential, a non-linear function ranging from 0.0 (none) to 1.0 (extreme), is derived from the individual binding affinities of a compound towards currently 16 target proteins: 10 nuclear receptors (androgen, estrogen α, estrogen β, glucocorticoid, liver X, mineralocorticoid, peroxisome proliferator-activated receptor γ, progesterone, thyroid α, and thyroid β), four members of the cytochrome P450 enzyme family (1A2, 2C9, 2D6, and 3A4), a cytosolic transcription factor (aryl hydrocarbon receptor) and a potassium ion channel (hERG). The interface to the technology allows building and uploading molecular structures, viewing and downloading results and, most importantly, rationalizing any prediction at the atomic level by interactively analyzing the binding mode of a compound with its target protein(s) in real-time 3D. The VirtualToxLab has been used to predict the toxic potential for over 2500 compounds: the results are posted on (http://www.virtualtoxlab.org). The free platform — the OpenVirtualToxLab — is accessible (in client–server mode) over the Internet. It is free of charge for universities, governmental agencies, regulatory bodies and non-profit organizations. -- Highlights: ► In silico technology for estimating the toxic potential of drugs and chemicals. ► Simulation of binding towards 16 proteins suspected to trigger adverse effects. ► Mechanistic interpretation and real-time 3D visualization. ► Accessible over the Internet. ► Free of charge for universities, governmental agencies, regulatory bodies and NPOs.

VirtualToxLab — A platform for estimating the toxic potential of drugs, chemicals and natural products

Energy Technology Data Exchange (ETDEWEB)

Vedani, Angelo, E-mail: angelo.vedani@unibas.ch [Biographics Laboratory 3R, Klingelbergstrasse 50, 4056 Basel (Switzerland); Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, 4056 Basel (Switzerland); Dobler, Max [Biographics Laboratory 3R, Klingelbergstrasse 50, 4056 Basel (Switzerland); Smieško, Martin [Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, 4056 Basel (Switzerland)

2012-06-01

The VirtualToxLab is an in silico technology for estimating the toxic potential (endocrine and metabolic disruption, some aspects of carcinogenicity and cardiotoxicity) of drugs, chemicals and natural products. The technology is based on an automated protocol that simulates and quantifies the binding of small molecules towards a series of proteins, known or suspected to trigger adverse effects. The toxic potential, a non-linear function ranging from 0.0 (none) to 1.0 (extreme), is derived from the individual binding affinities of a compound towards currently 16 target proteins: 10 nuclear receptors (androgen, estrogen α, estrogen β, glucocorticoid, liver X, mineralocorticoid, peroxisome proliferator-activated receptor γ, progesterone, thyroid α, and thyroid β), four members of the cytochrome P450 enzyme family (1A2, 2C9, 2D6, and 3A4), a cytosolic transcription factor (aryl hydrocarbon receptor) and a potassium ion channel (hERG). The interface to the technology allows building and uploading molecular structures, viewing and downloading results and, most importantly, rationalizing any prediction at the atomic level by interactively analyzing the binding mode of a compound with its target protein(s) in real-time 3D. The VirtualToxLab has been used to predict the toxic potential for over 2500 compounds: the results are posted on (http://www.virtualtoxlab.org). The free platform — the OpenVirtualToxLab — is accessible (in client–server mode) over the Internet. It is free of charge for universities, governmental agencies, regulatory bodies and non-profit organizations. -- Highlights: ► In silico technology for estimating the toxic potential of drugs and chemicals. ► Simulation of binding towards 16 proteins suspected to trigger adverse effects. ► Mechanistic interpretation and real-time 3D visualization. ► Accessible over the Internet. ► Free of charge for universities, governmental agencies, regulatory bodies and NPOs.

QCD at Zero Baryon Density and the Polyakov Loop Paradox

CERN Document Server

Kratochvila, S; Forcrand, Ph. de

2006-01-01

We compare the grand canonical partition function at fixed chemical potential mu with the canonical partition function at fixed baryon number B, formally and by numerical simulations at mu=0 and B=0 with four flavours of staggered quarks. We verify that the free energy densities are equal in the thermodynamic limit, and show that they can be well described by the hadron resonance gas at T T_c. Small differences between the two ensembles, for thermodynamic observables characterising the deconfinement phase transition, vanish with increasing lattice size. These differences are solely caused by contributions of non-zero baryon density sectors, which are exponentially suppressed with increasing volume. The Polyakov loop shows a different behaviour: for all temperatures and volumes, its expectation value is exactly zero in the canonical formulation, whereas it is always non-zero in the commonly used grand-canonical formulation. We clarify this paradoxical difference, and show that the non-vanishing Polyakov loop e...

Similarity Laws for the Lines of Ideal Free Energy and Chemical Potential in Supercritical Fluids.

Science.gov (United States)

Apfelbaum, E M; Vorob'ev, V S

2017-09-21

We have found the curves on the density-temperature plane, along which the values of free energy and chemical potential correspond to ideal gas quantities. At first, we have applied the van der Waals equation to construct them and to derive their equations. Then we have shown that the same lines for real substances (Ar, N 2 , CH 4 , SF 6 , H 2 , H 2 O) and for the model Lennard-Jones system constructed on the basis of the measurements data and calculations are well matched with the derived equations. The validity and deviations from the obtained similarity laws are discussed.

Modeling ambipolar potential formation due to ICRF heating effects on electrons

International Nuclear Information System (INIS)

Johnson, J.W.; Callen, J.D.; Hershkowitz, N.

1985-08-01

A mechanism for the potential bump observed near the region of ICRF heating in the endplugs of the Phaedrus tandem mirror experiment is investigated by numerical simulation of electron orbits in a simple mirror geometry. Given initial magnetic and ambipolar potential wells that trap the electrons, the ''near field'' parallel electric field E-tilde/sub z/e/sup -iωt/, which is localized near and due to the ICRF heating, tends to eject electrons from the region where E-tilde/sub z/ is nonzero. This depletion of the local electron population causes a local increase in the ambipolar potential. The rate at which the electrons are ejected, (dn/dt), is calculated from the electron orbit computation for a given potential well depth. The rate at which passing particles ''fill in'' the potential well can also be calculated. An estimate of how large the bump in the ambipolar potential becomes is obtained by finding the well depth at which (dn/dt) approximately equals the ''filling'' rate. For Phaedrus parameters (n 0 approx. = 4.0 x 10 12 cm -3 , T/sub e/ = 20 eV, E-tilde/sub z/ approx. = 1.0 V/cm) the electron pumping rate balances the ''filling'' rate at a potential well depth of approximately 40 V, consistent with experimental results

Revisiting the chemical reactivity indices as the state function derivatives. The role of classical chemical hardness

Energy Technology Data Exchange (ETDEWEB)

Malek, Ali; Balawender, Robert, E-mail: rbalawender@ichf.edu.pl [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, PL-01-224 Warsaw (Poland)

2015-02-07

The chemical reactivity indices as the equilibrium state-function derivatives are revisited. They are obtained in terms of the central moments (fluctuation formulas). To analyze the role of the chemical hardness introduced by Pearson [J. Am. Chem. Soc. 105, 7512 (1983)], the relations between the derivatives up to the third-order and the central moments are obtained. As shown, the chemical hardness and the chemical potential are really the principal indices of the chemical reactivity theory. It is clear from the results presented here that the chemical hardness is not the derivative of the Mulliken chemical potential (this means also not the second derivative of the energy at zero-temperature limit). The conventional quadratic dependence of energy, observed at finite temperature, reduces to linear dependence on the electron number at zero-temperature limit. The chemical hardness plays a double role in the admixture of ionic states to the reference neutral state energy: it determines the amplitude of the admixture and regulates the damping of its thermal factor.

Revisiting the chemical reactivity indices as the state function derivatives. The role of classical chemical hardness

International Nuclear Information System (INIS)

Malek, Ali; Balawender, Robert

2015-01-01

The chemical reactivity indices as the equilibrium state-function derivatives are revisited. They are obtained in terms of the central moments (fluctuation formulas). To analyze the role of the chemical hardness introduced by Pearson [J. Am. Chem. Soc. 105, 7512 (1983)], the relations between the derivatives up to the third-order and the central moments are obtained. As shown, the chemical hardness and the chemical potential are really the principal indices of the chemical reactivity theory. It is clear from the results presented here that the chemical hardness is not the derivative of the Mulliken chemical potential (this means also not the second derivative of the energy at zero-temperature limit). The conventional quadratic dependence of energy, observed at finite temperature, reduces to linear dependence on the electron number at zero-temperature limit. The chemical hardness plays a double role in the admixture of ionic states to the reference neutral state energy: it determines the amplitude of the admixture and regulates the damping of its thermal factor

On the unlikeliness of multi-field inflation: bounded random potentials and our vacuum

International Nuclear Information System (INIS)

Battefeld, Diana; Battefeld, Thorsten; Schulz, Sebastian

2012-01-01

Based on random matrix theory, we compute the likelihood of saddles and minima in a class of random potentials that are softly bounded from above and below, as required for the validity of low energy effective theories. Imposing this bound leads to a random mass matrix with non-zero mean of its entries. If the dimensionality of field-space is large, inflation is rare, taking place near a saddle point (if at all), since saddles are more likely than minima or maxima for common values of the potential. Due to the boundedness of the potential, the latter become more ubiquitous for rare low/large values respectively. Based on the observation of a positive cosmological constant, we conclude that the dimensionality of field-space after (and most likely during) inflation has to be low if no anthropic arguments are invoked, since the alternative, encountering a metastable deSitter vacuum by chance, is extremely unlikely

Experimental terrestrial soil-core microcosm test protocol. A method for measuring the potential ecological effects, fate, and transport of chemicals in terrestrial ecosystems

Energy Technology Data Exchange (ETDEWEB)

Van Voris, P.; Tolle, D.A.; Arthur, M.F.

1985-06-01

In order to protect the environment properly and have a realistic appraisal of how a chemical will act in the environment, tests of ecological effects and chemical fate must be performed on complex assemblages of biotic and abiotic components (i.e., microcosms) as well as single species. This protocol is one which could be added to a series of tests recently developed as guidelines for Section 4 of the Toxic Substances Control Act (P.L. 94-469; U.S.C., Section 2601-2629). The terrestrial soil-core microcosm is designed to supply site-specific and possibly regional information on the probable chemical fate and ecological effects resulting from release of a chemical substance to a terrestrial ecosystem. The EPA will use the data resulting from this test system to compare the potential hazards of a chemical with others that have been previously evaluated.

Chemical Contaminants Associated with Palm Wine from Nigeria Are Potential Food Safety Hazards

Directory of Open Access Journals (Sweden)

Ogueri Nwaiwu

2017-03-01

Full Text Available Recent analysis of palm wine, a traditional drink fermented mainly by yeasts, revealed the presence of several chemicals that were not products of yeast fermentation. The chemicals included styrene, benzene, trimethyldioxolane, dichloromethane, methylene fluoride, dichloroethanol, benzylisoquinoline and tetraacetyl-d-xylonic nitrile. A review of the concentrations of these compounds in palm wine found that the benzene concentrations in all samples reviewed ranged from 56–343 ppm and were within permissible limits, whereas the styrene values (1505–5614 ppm in all the palm wine samples evaluated were well over the recommended concentration that is immediately dangerous to life or health. Other chemical compounds evaluated varied according to location or sample source. The concentrations obtained are estimates only and a quantitative study needs to be carried out before the impact of these chemicals on health is evaluated. A search on The PubChem Project, the open chemical database, showed the description, properties and uses of these chemicals. Further searches carried out within other databases like PubMed, Scopus and Google Scholar, using each chemical’s name as a search term, showed possible hazards and adverse health conditions caused by these chemicals, especially styrene, benzene and dichloromethane. The point at which the chemicals are introduced into the drink is still not clear and requires further investigation. The chemicals can be hazardous to humans and there is need to establish and maintain a system that can guarantee permissible levels in the drink. This can be carried out using concentrations of the chemicals that are already known to be immediately dangerous to life or health as a reference point.

Physico-chemical analysis and antimicrobial potential of A pis dorsata, A pis mellifera and Z iziphus jujube honey samples from Pakistan

Directory of Open Access Journals (Sweden)

Hira Fahim

2014-08-01

Conclusion: Physico-chemical analysis of honey samples confirmed good quality of honey according to the standards set by European Union Commission and Codex Alimentarius Commission. Evaluation of these honey samples confirms antimicrobial potential of particular types of honeys indigenous to Pakistan.

Chemical warfare agent and biological toxin-induced pulmonary toxicity: could stem cells provide potential therapies?

Science.gov (United States)

Angelini, Daniel J; Dorsey, Russell M; Willis, Kristen L; Hong, Charles; Moyer, Robert A; Oyler, Jonathan; Jensen, Neil S; Salem, Harry

2013-01-01

Chemical warfare agents (CWAs) as well as biological toxins present a significant inhalation injury risk to both deployed warfighters and civilian targets of terrorist attacks. Inhalation of many CWAs and biological toxins can induce severe pulmonary toxicity leading to the development of acute lung injury (ALI) as well as acute respiratory distress syndrome (ARDS). The therapeutic options currently used to treat these conditions are very limited and mortality rates remain high. Recent evidence suggests that human stem cells may provide significant therapeutic options for ALI and ARDS in the near future. The threat posed by CWAs and biological toxins for both civilian populations and military personnel is growing, thus understanding the mechanisms of toxicity and potential therapies is critical. This review will outline the pulmonary toxic effects of some of the most common CWAs and biological toxins as well as the potential role of stem cells in treating these types of toxic lung injuries.

Relationship between physico-chemical characteristics and potential toxicity of PM10.

Science.gov (United States)

Megido, Laura; Suárez-Peña, Beatriz; Negral, Luis; Castrillón, Leonor; Suárez, Susana; Fernández-Nava, Yolanda; Marañón, Elena

2016-11-01

PM10 was sampled at a suburban location affected by traffic and industry in the north of Spain. The samples were analysed to determine the chemical components of PM10 (organic and elemental carbon, soluble chemical species and metals). The aim of this study was to assess the toxicity of PM10 in terms of the bulk analysis and the physico-chemical properties of the particles. Total carbon, sulphates, ammonium, chlorides and nitrates were found to be the major constituents of PM10. The contribution of the last of these was found to increase significantly with PM10 concentration (Pearson coefficient correlation of 0.7, p-value major risk to human health. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chemical variability of zeolites at a potential nuclear waste repository, Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Broxton, D.E.

1985-01-01

The compositions of clinoptilolites and their host tuffs have been examined by electron microprobe and x-ray fluorescence, respectively, to determine their variability at a potential nuclear waste repository, Yucca Mountain, Nevada. Because of their sorptive properties, these zeolites could provide important geologic barriers to radionuclide migration. Variations in clinoptilolite composition can strongly affect the mineral's thermal and ion-exchange properties, thus influencing its behavior in the repository environment. Clinoptilolites and heulandites closest to the proposed repository have calcium-rich compositions (60 to 90 mol. % Ca) and silica-to-aluminum ratios that concentrate between 4.0 and 4.6. In contrast, clinoptilolites and their host tuffs deeper in the volcanic sequence have highly variable compositions that vary vertically and laterally. Deeper-occurring clinoptilolites in the eastern part of Yucca Mountain are characterized by calcic-potassic compositions and tend to become more calcium-rich with depth. Clinoptilolites at equivalent stratigraphic levels on the western side of Yucca Mountain have sodic-potassic compositions and tend to become more sodium-rich with depth. Despite their differences in exchangeable cation compositions these two deeper-occurring compositional suites have similar silica-to-aluminum ratios, concentrating between 4.4 and 5.0. The chemical variability of clinoptilolites and their host tuffs at Yucca Mountain suggest that their physical and chemical properties will also vary. Compositionally-dependent clinoptilolite properties important for repository performance assessment include expansion/contraction behavior, hydration/dehydration behavior, and ion-exchange properties

An improvement of LLNA:DA to assess the skin sensitization potential of chemicals.

Science.gov (United States)

Zhang, Hongwei; Shi, Ying; Wang, Chao; Zhao, Kangfeng; Zhang, Shaoping; Wei, Lan; Dong, Li; Gu, Wen; Xu, Yongjun; Ruan, Hongjie; Zhi, Hong; Yang, Xiaoyan

2017-01-01

We developed a modified local lymph node assay based on ATP (LLNA:DA), termed the Two-Stage LLNA:DA, to further reduce the animal numbers in the identification of sensitizers. In the Two-Stage LLNA:DA procedure, 13 chemicals ranging from non-sensitizers to extreme sensitizers were selected. The first stage used reduced LLNA:DA (rLLNA:DA) to screen out sensitive chemicals. The second stage used LLNA:DA based on OECD 442 (A) to classify those potential sensitizers screened out in the first stage. In the first stage, the SIs of the methyl methacrylate, salicylic acid, methyl salicylate, ethyl salicylate, isopropanol and propanediol were below 1.8 and need not to be tested in the second step. Others continued to be tested by LLNA:DA. In the second stage, sodium lauryl sulphate and xylene were classified as weak sensitizers. a-hexyl cinnamic aldehyde and eugenol were moderate sensitizers. Benzalkonium chloride and glyoxal were strong sensitizers, and phthalic anhydride was an extreme sensitizer. The 9/9, 11/12, 10/11, and 8/13 (positive or negative only) categories of the Two-Stage LLNA:DA were consistent with those from the other methods (LLNA, LLNA:DA, GPMT/BT and HMT/HPTA), suggesting that Two-Stage LLNA:DA have a high coincidence rate with reported data. In conclusion, The Two-Stage LLNA:DA is in line with the "3R" rules, and can be a modification of LLNA:DA but needs more study.

Phenolic profiles of nectar and honey of Quillaja saponaria Mol. (Quillajaceae as potential chemical markers

Directory of Open Access Journals (Sweden)

Gloria Montenegro

2013-01-01

Full Text Available Quillaja saponaria Mol. (Quillajaceae is one of the most important melliferous species in Chile, mainly as a source of monofloral honey. Honey made by A. mellifera presents biological activity against pathogens and antioxidant capacity associated with the presence of phenolic compounds deriving from the nectar, as a result of bee honey foraging. The aim of this study was to identify and quantify the phenolic compounds from the floral nectar of Q. saponaria and the honey made in apiaries in the central zone, and compare the composition of the chromatographic profiles of nectar and honey to known phenolic compounds. The results obtained by HPLC-DAD (high-performance liquid chromatography with diode-array detection showed a similar profile of phenolic compounds, in which gallic acid, myricetin, rutin, quercetin and naringenin were identified. The phenolic compounds detected could be used as a reference for future studies for determining potential chemical markers of this honey, complementing the present identification of honeys by determining their botanical origin. The identification of bioindicators of the floral origins for honey of this species could provide added value to honey commercialization by certifying the botanical origin of their chemical features and biological attributes.

ToxAlerts: a Web server of structural alerts for toxic chemicals and compounds with potential adverse reactions.

Science.gov (United States)

Sushko, Iurii; Salmina, Elena; Potemkin, Vladimir A; Poda, Gennadiy; Tetko, Igor V

2012-08-27

The article presents a Web-based platform for collecting and storing toxicological structural alerts from literature and for virtual screening of chemical libraries to flag potentially toxic chemicals and compounds that can cause adverse side effects. An alert is uniquely identified by a SMARTS template, a toxicological endpoint, and a publication where the alert was described. Additionally, the system allows storing complementary information such as name, comments, and mechanism of action, as well as other data. Most importantly, the platform can be easily used for fast virtual screening of large chemical datasets, focused libraries, or newly designed compounds against the toxicological alerts, providing a detailed profile of the chemicals grouped by structural alerts and endpoints. Such a facility can be used for decision making regarding whether a compound should be tested experimentally, validated with available QSAR models, or eliminated from consideration altogether. The alert-based screening can also be helpful for an easier interpretation of more complex QSAR models. The system is publicly accessible and tightly integrated with the Online Chemical Modeling Environment (OCHEM, http://ochem.eu). The system is open and expandable: any registered OCHEM user can introduce new alerts, browse, edit alerts introduced by other users, and virtually screen his/her data sets against all or selected alerts. The user sets being passed through the structural alerts can be used at OCHEM for other typical tasks: exporting in a wide variety of formats, development of QSAR models, additional filtering by other criteria, etc. The database already contains almost 600 structural alerts for such endpoints as mutagenicity, carcinogenicity, skin sensitization, compounds that undergo metabolic activation, and compounds that form reactive metabolites and, thus, can cause adverse reactions. The ToxAlerts platform is accessible on the Web at http://ochem.eu/alerts, and it is constantly

Chiral soliton lattice and charged pion condensation in strong magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Brauner, Tomáš [Faculty of Science and Technology, University of Stavanger,N-4036 Stavanger (Norway); Yamamoto, Naoki [Department of Physics, Keio University,Yokohama 223-8522 (Japan)

2017-04-21

The Chiral Soliton Lattice (CSL) is a state with a periodic array of topological solitons that spontaneously breaks parity and translational symmetries. Such a state is known to appear in chiral magnets. We show that CSL also appears as a ground state of quantum chromodynamics at nonzero chemical potential in a magnetic field. By analyzing the fluctuations of the CSL, we furthermore demonstrate that in strong but achievable magnetic fields, charged pions undergo Bose-Einstein condensation. Our results, based on a systematic low-energy effective theory, are model-independent and fully analytic.

Spontaneous baryogenesis from asymmetric inflaton

International Nuclear Information System (INIS)

Takahashi, Fuminobu

2015-10-01

We propose a variant scenario of spontaneous baryogenesis from asymmetric inflaton based on current-current interactions between the inflaton and matter fields with a non-zero B-L charge. When the inflaton starts to oscillate around the minimum after inflation, it may lead to excitation of a CP-odd component, which induces an effective chemical potential for the B-L number through the current-current interactions. We study concrete inflation models and show that the spontaneous baryogenesis scenario can be naturally implemented in the chaotic inflation in supergravity.

Magnesium carbide synthesis from methane and magnesium oxide - a potential methodology for natural gas conversion to premium fuels and chemicals

Energy Technology Data Exchange (ETDEWEB)

Diaz, A.F.; Modestino, A.J.; Howard, J.B. [Massachusetts Institute of Technology, Cambridge, MA (United States)] [and others

1995-12-31

Diversification of the raw materials base for manufacturing premium fuels and chemicals offers U.S. and international consumers economic and strategic benefits. Extensive reserves of natural gas in the world provide a valuable source of clean gaseous fuel and chemical feedstock. Assuming the availability of suitable conversion processes, natural gas offers the prospect of improving flexibility in liquid fuels and chemicals manufacture, and thus, the opportunity to complement, supplement, or displace petroleum-based production as economic and strategic considerations require. The composition of natural gas varies from reservoir to reservoir but the principal hydrocarbon constituent is always methane (CH{sub 4}). With its high hydrogen-to-carbon ratio, methane has the potential to produce hydrogen or hydrogen-rich products. However, methane is a very chemically stable molecule and, thus, is not readily transformed to other molecules or easily reformed to its elements (H{sub 2} and carbon). In many cases, further research is needed to augment selectivity to desired product(s), increase single-pass conversions, or improve economics (e.g. there have been estimates of $50/bbl or more for liquid products) before the full potential of these methodologies can be realized on a commercial scale. With the trade-off between gas conversion and product selectivity, a major challenge common to many of these technologies is to simultaneously achieve high methane single-pass conversions and high selectivity to desired products. Based on the results of the scoping runs, there appears to be strong indications that a breakthrough has finally been achieved in that synthesis of magnesium carbides from MgO and methane in the arc discharge reactor has been demonstrated.

The η/s of hadrons out of chemical equilibrium

International Nuclear Information System (INIS)

Wiranata, A; Wang, X N; Prakash, M; Huovinen, P; Koch, V

2014-01-01

We study how the shear viscosity, η, entropy density, s, and η/s depend on growing hadron chemical potentials resulting from the loss of chemical equilibrium during the evolution of a relativistic heavy-ion collision. Our calculations here are for an interacting pion gas in a system of net baryon number zero. Time evolution of the temperature and pion chemical potential are taken from ideal fluid hydrodynamic calculations of RHIC and LHC collisions. We find that the shear viscosity decreases whereas the entropy density increases with increasing pion chemical potential resulting in values of η/s that are slightly reduced from the case of chemical potentials being zero when chemical equilibrium prevails. Our results indicate that the inclusion of additional mesons and baryons will likely lead to further reduction in the value of η/s.

Solvated electron: criticism of a suggested correlation of chemical potential with optical absorption energy

International Nuclear Information System (INIS)

Farhataziz, M.

1984-01-01

A recent theoretical treatment of the absorption spectrum of the solvated electron, e - sub(s), maintains that rigorously μ 0 >= -0.75 Esub(av), which gives empirical relationship, μ 0 >= -(0.93 +- 0.02)Esub(max). For e - sub(s) in a particular solvent at a temperature and pressure, μ 0 , Esub(av) and Esub(max) are standard chemical potential, average energy of the absorption spectrum and the energy at the absorption maximum respectively. The temperature and pressure effects on the absorption spectrum of e - sub(s) in water and liquid ammonia do not support the equality sign in the above cited relationships. The implications of inequality expressed above are discussed for e - sub(s) in water and liquid ammonia. (author)

Open Innovation Drug Discovery (OIDD): a potential path to novel therapeutic chemical space.

Science.gov (United States)

Alvim-Gaston, Maria; Grese, Timothy; Mahoui, Abdelaziz; Palkowitz, Alan D; Pineiro-Nunez, Marta; Watson, Ian

2014-01-01

The continued development of computational and synthetic methods has enabled the enumeration or preparation of a nearly endless universe of chemical structures. Nevertheless, the ability of this chemical universe to deliver small molecules that can both modulate biological targets and have drug-like physicochemical properties continues to be a topic of interest to the pharmaceutical industry and academic researchers alike. The chemical space described by public, commercial, in-house and virtual compound collections has been interrogated by multiple approaches including biochemical, cellular and virtual screening, diversity analysis, and in-silico profiling. However, current drugs and known chemical probes derived from these efforts are contained within a remarkably small volume of the predicted chemical space. Access to more diverse classes of chemical scaffolds that maintain the properties relevant for drug discovery is certainly needed to meet the increasing demands for pharmaceutical innovation. The Lilly Open Innovation Drug Discovery platform (OIDD) was designed to tackle barriers to innovation through the identification of novel molecules active in relevant disease biology models. In this article we will discuss several computational approaches towards describing novel, biologically active, drug-like chemical space and illustrate how the OIDD program may facilitate access to previously untapped molecules that may aid in the search for innovative pharmaceuticals.

Biogenic methane potential of marine sediments. Application of chemical thermodynamics

Energy Technology Data Exchange (ETDEWEB)

Arning, E.T.; Schulz, H.M. [Helmholtz Centre Potsdam GFZ, Potsdam (Germany); Berk, W. van [Technical Univ. of Clausthal (Germany). Dept. of Hydrogeology

2013-08-01

Accumulations of biogenic methane-dominated gas are widespread and occur in a variety of depositional settings and rock types. However, the potential of biogenic methane remains underexplored. This is mainly due to the fact that quantitative assessments applying numerical modeling techniques for exploration purposes are generally lacking to date. Biogenic methane formation starts in relatively shallow marine sediments below the sulfate reduction zone. When sulfate is exhausted, methanogenesis via the CO{sub 2} reduction pathway is often the dominant biogenic methane formation process in marine sediments (Claypool and Kaplan, 1974). The process can be simplified by the reaction: 2CH{sub 2}O + Ca{sup 2+} + H{sub 2}O {yields} CH{sub 4} + CaCO{sub 3} + 2H{sup +}. The products of early diagenetic reactions initiate coupled equilibrium reactions that induce a new state of chemical equilibrium among minerals, pore water and gas. The driving force of the complex biogeochemical reactions in sedimentary environments during early diagenesis is the irreversible redox-conversion of organic matter. Early diagenetic formation of biogenic methane shortly after deposition ('early diagenesis') was retraced using PHREEQC computer code that is applied to calculate homogenous and heterogeneous mass-action equations in combination with one-dimensional diffusion driven transport (Parkhurst and Appelo, 1999). Our modeling approach incorporates interdependent diagenetic reactions evolving into a diffusive multi-component and multiphase system by means of thermodynamic equilibrium calculations of species distribution (Arning et al., 2011, 2012, 2013). Reaction kinetics of organic carbon conversion is integrated into the set of equilibrium reactions by defining type and amount of converted organic matter in a certain time step. It is the aim (1) to calculate quantitatively thermodynamic equilibrium conditions (composition of pore water, mineral phase and gas phase assemblage) in

Inflationary predictions of double-well, Coleman-Weinberg, and hilltop potentials with non-minimal coupling

Science.gov (United States)

Bostan, Nilay; Güleryüz, Ömer; Nefer Şenoğuz, Vedat

2018-05-01

We discuss how the non-minimal coupling ξphi2R between the inflaton and the Ricci scalar affects the predictions of single field inflation models where the inflaton has a non-zero vacuum expectation value (VEV) v after inflation. We show that, for inflaton values both above the VEV and below the VEV during inflation, under certain conditions the inflationary predictions become approximately the same as the predictions of the Starobinsky model. We then analyze inflation with double-well and Coleman-Weinberg potentials in detail, displaying the regions in the v-ξ plane for which the spectral index ns and the tensor-to-scalar ratio r values are compatible with the current observations. r is always larger than 0.002 in these regions. Finally, we consider the effect of ξ on small field inflation (hilltop) potentials.

Generation of membrane potential beyond the conceptual range of Donnan theory and Goldman-Hodgkin-Katz equation.

Science.gov (United States)

Tamagawa, Hirohisa; Ikeda, Kota

2017-09-01

Donnan theory and Goldman-Hodgkin-Katz equation (GHK eq.) state that the nonzero membrane potential is generated by the asymmetric ion distribution between two solutions separated by a semipermeable membrane and/or by the continuous ion transport across the semipermeable membrane. However, there have been a number of reports of the membrane potential generation behaviors in conflict with those theories. The authors of this paper performed the experimental and theoretical investigation of membrane potential and found that (1) Donnan theory is valid only when the macroscopic electroneutrality is sufficed and (2) Potential behavior across a certain type of membrane appears to be inexplicable on the concept of GHK eq. Consequently, the authors derived a conclusion that the existing theories have some limitations for predicting the membrane potential behavior and we need to find a theory to overcome those limitations. The authors suggest that the ion adsorption theory named Ling's adsorption theory, which attributes the membrane potential generation to the mobile ion adsorption onto the adsorption sites, could overcome those problems.

Non-covalent interactions across organic and biological subsets of chemical space: Physics-based potentials parametrized from machine learning

Science.gov (United States)

Bereau, Tristan; DiStasio, Robert A.; Tkatchenko, Alexandre; von Lilienfeld, O. Anatole

2018-06-01

Classical intermolecular potentials typically require an extensive parametrization procedure for any new compound considered. To do away with prior parametrization, we propose a combination of physics-based potentials with machine learning (ML), coined IPML, which is transferable across small neutral organic and biologically relevant molecules. ML models provide on-the-fly predictions for environment-dependent local atomic properties: electrostatic multipole coefficients (significant error reduction compared to previously reported), the population and decay rate of valence atomic densities, and polarizabilities across conformations and chemical compositions of H, C, N, and O atoms. These parameters enable accurate calculations of intermolecular contributions—electrostatics, charge penetration, repulsion, induction/polarization, and many-body dispersion. Unlike other potentials, this model is transferable in its ability to handle new molecules and conformations without explicit prior parametrization: All local atomic properties are predicted from ML, leaving only eight global parameters—optimized once and for all across compounds. We validate IPML on various gas-phase dimers at and away from equilibrium separation, where we obtain mean absolute errors between 0.4 and 0.7 kcal/mol for several chemically and conformationally diverse datasets representative of non-covalent interactions in biologically relevant molecules. We further focus on hydrogen-bonded complexes—essential but challenging due to their directional nature—where datasets of DNA base pairs and amino acids yield an extremely encouraging 1.4 kcal/mol error. Finally, and as a first look, we consider IPML for denser systems: water clusters, supramolecular host-guest complexes, and the benzene crystal.

The potential for chemical mixtures from the environment to enable the cancer hallmark of sustained proliferative signalling.

Science.gov (United States)

Engström, Wilhelm; Darbre, Philippa; Eriksson, Staffan; Gulliver, Linda; Hultman, Tove; Karamouzis, Michalis V; Klaunig, James E; Mehta, Rekha; Moorwood, Kim; Sanderson, Thomas; Sone, Hideko; Vadgama, Pankaj; Wagemaker, Gerard; Ward, Andrew; Singh, Neetu; Al-Mulla, Fahd; Al-Temaimi, Rabeah; Amedei, Amedeo; Colacci, Anna Maria; Vaccari, Monica; Mondello, Chiara; Scovassi, A Ivana; Raju, Jayadev; Hamid, Roslida A; Memeo, Lorenzo; Forte, Stefano; Roy, Rabindra; Woodrick, Jordan; Salem, Hosni K; Ryan, Elizabeth P; Brown, Dustin G; Bisson, William H

2015-06-01

The aim of this work is to review current knowledge relating the established cancer hallmark, sustained cell proliferation to the existence of chemicals present as low dose mixtures in the environment. Normal cell proliferation is under tight control, i.e. cells respond to a signal to proliferate, and although most cells continue to proliferate into adult life, the multiplication ceases once the stimulatory signal disappears or if the cells are exposed to growth inhibitory signals. Under such circumstances, normal cells remain quiescent until they are stimulated to resume further proliferation. In contrast, tumour cells are unable to halt proliferation, either when subjected to growth inhibitory signals or in the absence of growth stimulatory signals. Environmental chemicals with carcinogenic potential may cause sustained cell proliferation by interfering with some cell proliferation control mechanisms committing cells to an indefinite proliferative span. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Chemically aged and mixed aerosols over the Central Atlantic Ocean - Potential impacts

NARCIS (Netherlands)

Astitha, M.; Kallos, G.; Spyrou, C.; O'Hirok, W.; Lelieveld, J.; Denier Gon, H.A.C. van der

2010-01-01

Detailed information on the chemical and physical properties of aerosols is important for assessing their role in air quality and climate. This work explores the origin and fate of continental aerosols transported over the Central Atlantic Ocean, in terms of chemical composition, number and size

Studies in Chemical Dynamics

International Nuclear Information System (INIS)

Rabitz, Herschel; Ho, Tak-San

2003-01-01

This final report draws together the research carried from February, 1986 through January, 2003 concerning a series of topics in chemical dynamics. The specific areas of study include molecular collisions, chemical kinetics, data inversion to extract potential energy surfaces, and model reduction of complex kinetic systems

Evaluating the influence of chemical weathering on the composition of the continental crust using lithium and its isotopes

Science.gov (United States)

Rudnick, R. L.; Liu, X.

2011-12-01

The continental crust has an "intermediate" bulk composition that is distinct from primary melts of peridotitic mantle (basalt or picrite). This mismatch between the "building blocks" and the "edifice" of the continental crust points to the operation of processes that preferentially remove mafic to ultramafic material from the continents. Such processes include lower crustal recycling (via density foundering or lower crustal subduction - e.g., relamination, Hacker et al., 2011, EPSL), generation of evolved melts via slab melting, and/or chemical weathering. Stable isotope systems document the influence of chemical weathering on the bulk crust composition: the oxygen isotope composition of the bulk crust is distinctly heavier than that of primary, mantle-derived melts (Simon and Lecuyer, 2005, G-cubed) and the Li isotopic composition of the bulk crust is distinctly lighter than that of mantle-derive melts (Teng et al., 2004, GCA; 2008, Chem. Geol.). Both signatures mark the imprint of chemical weathering on the bulk crust composition. Here, we use a simple mass balance model for lithium inputs and outputs from the continental crust to quantify the mass lost due to chemical weathering. We find that a minimum of 15%, a maximum of 60%, and a best estimate of ~40% of the original juvenile rock mass may have been lost via chemical weathering. The accumulated percentage of mass loss due to chemical weathering leads to an average global chemical weathering rate (CWR) of ~ 8×10^9 to 2×10^10 t/yr since 3.5 Ga, which is about an order of magnitude higher than the minimum estimates based on modern rivers (Gaillardet et al., 1999, Chem. Geol.). While we cannot constrain the exact portion of crustal mass loss via chemical weathering, given the uncertainties of the calculation, we can demonstrate that the weathering flux is non-zero. Therefore, chemical weathering must play a role in the evolution of the composition and mass of the continental crust.

Evidence of chemical-potential shift with hole doping in Bi2Sr2CaCu2O8+δ

International Nuclear Information System (INIS)

Shen, Z.; Dessau, D.S.; Wells, B.O.; Olson, C.G.; Mitzi, D.B.; Lombado, L.; List, R.S.; Arko, A.J.

1991-01-01

We have performed photoemission studies on high-quality Bi 2 Sr 2 CaCu 2 O 8+δ samples with various δ. Our results show a clear chemical-potential shift (0.15--0.2 eV) as a function of doping. This result and the existing angle-resolved-photoemission data give a rather standard doping behavior of this compound in its highly doped regime

Chemical Peel

Science.gov (United States)

... your expectations. Talk with your doctor about your motivations and expectations, as well as the potential risks. ... the sun permanently to prevent changes in skin color. Keep in mind that chemical peel results might ...

Chemical influences of the environment

Energy Technology Data Exchange (ETDEWEB)

Carr, D J

1961-01-01

It is possible to consider the chemical effects of the environment in various ways. A distinction can be made, for instance, between chemical and physicochemical effects. The latter would include such phenomena as osmotic pressure, pH, adsorption phenomena and redox potentials. Of these, pH is so universally involved in physiological experiments as to render any treatment of its effects almost superfluous. The measurement and interpretation of redox potentials is so fraught with difficulties that they are of real value only with systems which can be simplified to a few chemical components. In this study of the effects of chemicals on plant growth and development, only such chemicals as occur in natural environments where plants grow will be considered. The effects of synthetic hormones or of fertilizers will, therefore, be neglected, but some attention must be given to certain gases which, as pollutants, must be considered as part of the atmosphere of any industrialized country. They are O/sub 3/, CO, and ethylene.

Non-Chemical Distant Cellular Interactions as a potential confounder of Cell Biology Experiments

Directory of Open Access Journals (Sweden)

Ashkan eFarhadi

2014-10-01

Full Text Available Distant cells can communicate with each other through a variety of methods. Two such methods involve electrical and/or chemical mechanisms. Non-chemical, distant cellular interactions may be another method of communication that cells can use to modify the behavior of other cells that are mechanically separated. Moreover, non-chemical, distant cellular interactions may explain some cases of confounding effects in Cell Biology experiments. In this article, we review non-chemical, distant cellular interactions studies to try to shed light on the mechanisms in this highly unconventional field of cell biology. Despite the existence of several theories that try to explain the mechanism of non-chemical, distant cellular interactions, this phenomenon is still speculative. Among candidate mechanisms, electromagnetic waves appear to have the most experimental support. In this brief article, we try to answer a few key questions that may further clarify this mechanism.

Amorphization induced by chemical disorder in crystalline NiZr2: A molecular-dynamics study based on an n-body potential

International Nuclear Information System (INIS)

Massobrio, C.; Pontikis, V.; Martin, G.

1989-01-01

We present the first molecular-dynamics study of the amorphization of a crystalline alloy (NiZr 2 ) induced by chemical disorder. We used a n-body potential in conjunction with isobaric-isothermal molecular dynamics. The behavior of the pair distribution function suggests that the instability leading to the amorphous state is a first-order phase transformation

Chemical warfare agents.

Science.gov (United States)

Kuca, Kamil; Pohanka, Miroslav

2010-01-01

Chemical warfare agents are compounds of different chemical structures. Simple molecules such as chlorine as well as complex structures such as ricin belong to this group. Nerve agents, vesicants, incapacitating agents, blood agents, lung-damaging agents, riot-control agents and several toxins are among chemical warfare agents. Although the use of these compounds is strictly prohibited, the possible misuse by terrorist groups is a reality nowadays. Owing to this fact, knowledge of the basic properties of these substances is of a high importance. This chapter briefly introduces the separate groups of chemical warfare agents together with their members and the potential therapy that should be applied in case someone is intoxicated by these agents.

Chemical characterization of 21 species of marine macroalgae common in Norwegian waters: benefits of and limitations to their potential use in food and feed.

Science.gov (United States)

Biancarosa, Irene; Belghit, Ikram; Bruckner, Christian G; Liland, Nina S; Waagbø, Rune; Amlund, Heidi; Heesch, Svenja; Lock, Erik-Jan

2018-03-01

In the past few years, much effort has been invested into developing a new blue economy based on harvesting, cultivating and processing marine macroalgae in Norway. Macroalgae have high potential for a wide range of applications, e.g. as source of pharmaceuticals, production of biofuels or as food and feed. However, data on the chemical composition of macroalgae from Norwegian waters are scant. This study was designed to characterize the chemical composition of 21 algal species. Both macro- and micronutrients were analysed. Concentrations of heavy metals and the metalloid arsenic in the algae were also quantified. The results confirm that marine macroalgae contain nutrients which are relevant for both human and animal nutrition, the concentrations whereof are highly dependent on species. Although heavy metals and arsenic were detected in the algae studied, concentrations were mostly below maximum allowed levels set by food and feed legislation in the EU. This study provides chemical data on a wide range of algal species covering the three taxonomic groups (brown, red and green algae) and discusses both benefits of and potential limitations to their use for food and feed purposes. © 2017 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. © 2017 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Mortality of workers potentially exposed to organic and inorganic brominated chemicals, DBCP, TRIS, PBB, and DDT

Energy Technology Data Exchange (ETDEWEB)

Wong, O; Brocker, W; Davis, H V; Nagle, G S

1984-02-01

A historical prospective mortality study was conducted on 3579 white male workers employed between 1935 and 1976 with potential exposures to brominated compounds including 1,2-dibromo-3-chloropropane (DBCP), Tris (2,3-dibromopropyl) phosphate, polybrominated biphenyls (PBB), various organic and inorganic bromides, and DDT. Death certificates were obtained for 541 deaths (94% of all deaths). The mortality experience of the entire cohort and several subcohorts was compared with that of United States white men adjusted for age and calendar time. The comparison statistic was the commonly used standardised mortality ratio (SMR). Historical industrial hygiene data were not available, and the workers were classified by their work areas or departments in order to estimate their potential exposures. Overall mortality for the entire cohort and several subgroups was significantly lower than expected. For the entire cohort, significant mortality deficits were observed in diseases of the circulatory system, non-malignant respiratory disease, and diseases of the digestive system. On the other hand, mortality from diabetes mellitus was significantly raised for the cohort. No significant overall or cause-specific mortality excess was detected among employees potentially exposed to either TRIS or DDT. A significant mortality excess due to diseases of the circulatory system was observed among workers potentially exposed to DBCP. Mortality from testicular cancer was significantly higher than expected among those potentially exposed to other organic bromides. The common potential exposure of those who had died of testicular cancer was methyl bromide. Owing to the lack of accurate historical exposure information and the fact that many workers were potentially exposed to a multitude of chemicals, it is difficult to draw definitive statements on the causations of the observed mortality excesses.

High-throughput screening of chemicals as functional ...

Science.gov (United States)

Identifying chemicals that provide a specific function within a product, yet have minimal impact on the human body or environment, is the goal of most formulation chemists and engineers practicing green chemistry. We present a methodology to identify potential chemical functional substitutes from large libraries of chemicals using machine learning based models. We collect and analyze publicly available information on the function of chemicals in consumer products or industrial processes to identify a suite of harmonized function categories suitable for modeling. We use structural and physicochemical descriptors for these chemicals to build 41 quantitative structure–use relationship (QSUR) models for harmonized function categories using random forest classification. We apply these models to screen a library of nearly 6400 chemicals with available structure information for potential functional substitutes. Using our Functional Use database (FUse), we could identify uses for 3121 chemicals; 4412 predicted functional uses had a probability of 80% or greater. We demonstrate the potential application of the models to high-throughput (HT) screening for “candidate alternatives” by merging the valid functional substitute classifications with hazard metrics developed from HT screening assays for bioactivity. A descriptor set could be obtained for 6356 Tox21 chemicals that have undergone a battery of HT in vitro bioactivity screening assays. By applying QSURs, we wer

Probing nanomechanical interaction at the interface between biological membrane and potentially toxic chemical.

Science.gov (United States)

Lim, Chanoong; Park, Sohee; Park, Jinwoo; Ko, Jina; Lee, Dong Woog; Hwang, Dong Soo

2018-04-12

Various xenobiotics interact with biological membranes, and precise evaluations of the molecular interactions between them are essential to foresee the toxicity and bioavailability of existing or newly synthesized molecules. In this study, surface forces apparatus (SFA) measurement and Langmuir trough based tensiometry are performed to reveal nanomechanical interaction mechanisms between potential toxicants and biological membranes for ex vivo toxicity evaluation. As a toxicant, polyhexamethylene guanidine (PHMG) was selected because PHMG containing humidifier disinfectant and Vodka caused lots of victims in both S. Korea and Russia, respectively, due to the lack of holistic toxicity evaluation of PHMG. Here, we measured strong attraction (Wad ∼4.2 mJ/m 2 ) between PHMG and head group of biological membranes while no detectable adhesion force between the head group and control molecules was measured. Moreover, significant changes in π-A isotherm of 1,2-Dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) monolayers were measured upon PHMG adsorption. These results indicate PHMG strongly binds to hydrophilic group of lipid membranes and alters the structural and phase behavior of them. More importantly, complementary utilization of SFA and Langmuir trough techniques are found to be useful to predict the potential toxicity of a chemical by evaluating the molecular interaction with biological membranes, the primary protective barrier for living organisms. Copyright © 2018 Elsevier B.V. All rights reserved.

ANATOMICAL CHARACTERISTICS AND CHEMICAL PROPERTIES OF THE BRANCH-WOOD OF Schizolobium amazonicum DUCKE SPECIES AND ITS POTENTIAL USES

Directory of Open Access Journals (Sweden)

Yusup Amin

2013-10-01

Full Text Available The scale of forest degradation and deforestation in Indonesia has inspired the use of lesser-known wood species, which are potentially abundant and so far has not much been utilized. Utilization of these woods should be imposed not only of the stem wood but also of the branch-wood portions. Schizolobiumamazonicum Ducke treeis one of those lesser-known species, and growing fast with an MAIof3.68 cm/year.In Indonesia this species is only found in the Purwodadi Botanical Garden. A research was conducted to study the basic characteristics (anatomical aspects and chemical properties of the branch-wood portion of this species. The branch-wood materials were obtained from the Purwodadi Botanical Garden situated in Pasuruan (East Java. The specimens used were the first branch of the trunk (stem of nine-year old S. amazonicum tree (= 29.46 cm. The branch-wood samples were then examined for the anatomical aspects (macroscopic and microscopic characteristics and chemical properties (chemical composition. Results revealed that the anatomical properties of S.amazonicum branch-wood exhibited close similarities to those of sengon wood; it was light in appearance and white in color. Its fiber averaged about 1500 μm, and based on the fiber dimension's derived values the branch- wood fiber of this species was categorized into first-class quality for pulp and paper manufacture. Further, the chemical composition of this branch-wood compared favorably with that of sengon and mangium wood. The composition of extractive content thatsoluble in alcohol-benzene; lignin; holocellulose; and α-cellulose of this branch-wood were 2.46; 28.71; 80.64; and 50.47%, respectively. The overall assessment implied that the branch-wood portion of S.amazonicum tree affords favorable potential to be developed as raw material for pulp and paper manufacture. Also, considering that both sengon and mangium woods were already used in the pulp and paper industries as well as the trees are

Potential hazards to embryo implantation: A human endometrial in vitro model to identify unwanted antigestagenic actions of chemicals

International Nuclear Information System (INIS)

Fischer, L.; Deppert, W.R.; Pfeifer, D.; Stanzel, S.; Weimer, M.; Hanjalic-Beck, A.; Stein, A.; Straßer, M.; Zahradnik, H.P.; Schaefer, W.R.

2012-01-01

Embryo implantation is a crucial step in human reproduction and depends on the timely development of a receptive endometrium. The human endometrium is unique among adult tissues due to its dynamic alterations during each menstrual cycle. It hosts the implantation process which is governed by progesterone, whereas 17β-estradiol regulates the preceding proliferation of the endometrium. The receptors for both steroids are targets for drugs and endocrine disrupting chemicals. Chemicals with unwanted antigestagenic actions are potentially hazardous to embryo implantation since many pharmaceutical antiprogestins adversely affect endometrial receptivity. This risk can be addressed by human tissue-specific in vitro assays. As working basis we compiled data on chemicals interacting with the PR. In our experimental work, we developed a flexible in vitro model based on human endometrial Ishikawa cells. Effects of antiprogestin compounds on pre-selected target genes were characterized by sigmoidal concentration–response curves obtained by RT-qPCR. The estrogen sulfotransferase (SULT1E1) was identified as the most responsive target gene by microarray analysis. The agonistic effect of progesterone on SULT1E1 mRNA was concentration-dependently antagonized by RU486 (mifepristone) and ZK137316 and, with lower potency, by 4-nonylphenol, bisphenol A and apigenin. The negative control methyl acetoacetate showed no effect. The effects of progesterone and RU486 were confirmed on the protein level by Western blotting. We demonstrated proof of principle that our Ishikawa model is suitable to study quantitatively effects of antiprogestin-like chemicals on endometrial target genes in comparison to pharmaceutical reference compounds. This test is useful for hazard identification and may contribute to reduce animal studies. -- Highlights: ► We compare progesterone receptor-mediated endometrial effects of chemicals and drugs. ► 4-Nonylphenol, bisphenol A and apigenin exert weak

Potential hazards to embryo implantation: A human endometrial in vitro model to identify unwanted antigestagenic actions of chemicals

Energy Technology Data Exchange (ETDEWEB)

Fischer, L.; Deppert, W.R. [Department of Obstetrics and Gynecology, University Hospital Freiburg (Germany); Pfeifer, D. [Department of Hematology and Oncology, University Hospital Freiburg (Germany); Stanzel, S.; Weimer, M. [Department of Biostatistics, German Cancer Research Center, Heidelberg (Germany); Hanjalic-Beck, A.; Stein, A.; Straßer, M.; Zahradnik, H.P. [Department of Obstetrics and Gynecology, University Hospital Freiburg (Germany); Schaefer, W.R., E-mail: wolfgang.schaefer@uniklinik-freiburg.de [Department of Obstetrics and Gynecology, University Hospital Freiburg (Germany)

2012-05-01

Embryo implantation is a crucial step in human reproduction and depends on the timely development of a receptive endometrium. The human endometrium is unique among adult tissues due to its dynamic alterations during each menstrual cycle. It hosts the implantation process which is governed by progesterone, whereas 17β-estradiol regulates the preceding proliferation of the endometrium. The receptors for both steroids are targets for drugs and endocrine disrupting chemicals. Chemicals with unwanted antigestagenic actions are potentially hazardous to embryo implantation since many pharmaceutical antiprogestins adversely affect endometrial receptivity. This risk can be addressed by human tissue-specific in vitro assays. As working basis we compiled data on chemicals interacting with the PR. In our experimental work, we developed a flexible in vitro model based on human endometrial Ishikawa cells. Effects of antiprogestin compounds on pre-selected target genes were characterized by sigmoidal concentration–response curves obtained by RT-qPCR. The estrogen sulfotransferase (SULT1E1) was identified as the most responsive target gene by microarray analysis. The agonistic effect of progesterone on SULT1E1 mRNA was concentration-dependently antagonized by RU486 (mifepristone) and ZK137316 and, with lower potency, by 4-nonylphenol, bisphenol A and apigenin. The negative control methyl acetoacetate showed no effect. The effects of progesterone and RU486 were confirmed on the protein level by Western blotting. We demonstrated proof of principle that our Ishikawa model is suitable to study quantitatively effects of antiprogestin-like chemicals on endometrial target genes in comparison to pharmaceutical reference compounds. This test is useful for hazard identification and may contribute to reduce animal studies. -- Highlights: ► We compare progesterone receptor-mediated endometrial effects of chemicals and drugs. ► 4-Nonylphenol, bisphenol A and apigenin exert weak

Potential external contamination with bisphenol A and other ubiquitous organic environmental chemicals during biomonitoring analysis: an elusive laboratory challenge.

Science.gov (United States)

Ye, Xiaoyun; Zhou, Xiaoliu; Hennings, Ryan; Kramer, Joshua; Calafat, Antonia M

2013-03-01

Biomonitoring studies are conducted to assess internal dose (i.e., body burden) to environmental chemicals. However, because of the ubiquitous presence in the environment of some of these chemicals, such as bisphenol A (BPA), external contamination during handling and analysis of the biospecimens collected for biomonitoring evaluations could compromise the reported concentrations of such chemicals. We examined the contamination with the target analytes during analysis of biological specimens in biomonitoring laboratories equipped with state-of-the-art analytical instrumentation. We present several case studies using the quantitative determination of BPA and other organic chemicals (i.e., benzophenone-3, triclosan, parabens) in human urine, milk, and serum to identify potential contamination sources when the biomarkers measured are ubiquitous environmental contaminants. Contamination with target analytes during biomonitoring analysis could result from solvents and reagents, the experimental apparatus used, the laboratory environment, and/or even the analyst. For biomonotoring data to be valid-even when obtained from high-quality analytical methods and good laboratory practices-the following practices must be followed to identify and track unintended contamination with the target analytes during analysis of the biological specimens: strict quality control measures including use of laboratory blanks; replicate analyses; engineering controls (e.g., clean rooms, biosafety cabinets) as needed; and homogeneous matrix-based quality control materials within the expected concentration ranges of the study samples.

Computational Methods to Assess the Production Potential of Bio-Based Chemicals

DEFF Research Database (Denmark)

Campodonico, Miguel A; Sukumara, Sumesh; Feist, Adam M.

2018-01-01

are described in detail. The first tool is GEM-Path: an algorithm to compute all structurally possible pathways from one target molecule to the host metabolome. The second tool is a framework for Modeling Sustainable Industrial Chemicals production (MuSIC), which integrates modeling approaches for cellular...... metabolism, bioreactor design, upstream/downstream processes, and economic impact assessment. Integrating GEM-Path and MuSIC will play a vital role in supporting early phases of research efforts and guide the policy makers with decisions, as we progress toward planning a sustainable chemical industry....

Particle creations in the pseudoparticle gravitational fields

International Nuclear Information System (INIS)

Tomimatsu, Akira.

1978-03-01

The origin of black hole radiation seems to be of a pseudoparticle nature with a non-vanishing Euler characteristic of the Schwarzshild metric. In order to develop this idea, the particle creation in another typical pseudoparticle space-time, which was derived by rewriting the Belavin-type vector potential into a metric form through the SL(2, C) gauge theory of general relativity, is analyzed. It is shown by the path-integral approach that the particle creation can indeed occur, with an incomplete thermal energy spectrum because of its non-uniform temperature and non-zero chemical potential. Some discussions on the results and the comparisons with the cases of black hole radiation and cosmological particle creation are also made. (auth.)

NUMERICAL AND ANALYTICAL SOLUTIONS OF NEUTRINO-DOMINATED ACCRETION FLOWS WITH A NON-ZERO TORQUE BOUNDARY CONDITION AND ITS APPLICATIONS IN GAMMA-RAY BURSTS

Energy Technology Data Exchange (ETDEWEB)

Xie, Wei; Lei, Wei-Hua; Wang, Ding-Xiong, E-mail: leiwh@hust.edu.cn [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China)

2016-12-20

A stellar-mass black hole (BH) surrounded by a neutrino-dominated accretion flow (NDAF) has been discussed in a number of works as the central engine of gamma-ray bursts (GRBs). It is widely believed that NDAF cannot liberate enough energy for bright GRBs. However, these works have been based on the assumption of a “no torque” boundary condition, which is invalid when the disk is magnetized. In this paper, we present both numerical and analytical solutions for NDAFs with non-zero boundary stresses and reexamine their properties. We find that an NDAF with such a boundary torque can be powerful enough to account for those bright short GRBs, energetic long GRBs, and ultra-long GRBs. The disk becomes viscously unstable, which makes it possible to interpret the variability of GRB prompt emission and the steep decay phase in the early X-ray afterglow. Finally, we study the gravitational waves radiated from a processing BH-NDAF. We find that the effects of the boundary torque on the strength of the gravitational waves can be ignored.

Role of structural relaxations and chemical substitutions on piezoelectric fields and potential lineup in GaN/Al junctions

Science.gov (United States)

Picozzi, S.; Profeta, G.; Continenza, A.; Massidda, S.; Freeman, A. J.

2002-04-01

First-principles full-potential linearized augmented plane wave calculations are performed to clarify the role of the interface geometry on piezoelectric fields and potential lineups in [0001] wurtzite and [111]-zincblende GaN/Al junctions. The electric field (polarity and magnitude) is found to be strongly affected by atomic relaxations in the interface region. A procedure is used to evaluate the Schottky-barrier height in the presence of electric fields, showing that their effect is relatively small (a few tenths of an eV). These calculations assess the rectifying behavior of the GaN/Al contact, in agreement with experimental values for the barrier. We disentangle chemical and structural effects on the relevant properties (such as the potential discontinuity and the electric field) by studying unrelaxed ideal nitride/metal systems. Using simple electronegativity arguments, we outline the leading mechanisms that define the values of the electric field and Schottky barrier in these ideal systems. Finally, the transitivity rule is proved to be well satisfied.

Improving intermolecular interactions in DFTB3 using extended polarization from chemical-potential equalization

Energy Technology Data Exchange (ETDEWEB)

Christensen, Anders S., E-mail: andersx@chem.wisc.edu, E-mail: cui@chem.wisc.edu; Cui, Qiang, E-mail: andersx@chem.wisc.edu, E-mail: cui@chem.wisc.edu [Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin 53706 (United States); Elstner, Marcus [Theoretische Chemische Biologie, Universität Karlsruhe, Kaiserstr. 12, 76131 Karlsruhe (Germany)

2015-08-28

Semi-empirical quantum mechanical methods traditionally expand the electron density in a minimal, valence-only electron basis set. The minimal-basis approximation causes molecular polarization to be underestimated, and hence intermolecular interaction energies are also underestimated, especially for intermolecular interactions involving charged species. In this work, the third-order self-consistent charge density functional tight-binding method (DFTB3) is augmented with an auxiliary response density using the chemical-potential equalization (CPE) method and an empirical dispersion correction (D3). The parameters in the CPE and D3 models are fitted to high-level CCSD(T) reference interaction energies for a broad range of chemical species, as well as dipole moments calculated at the DFT level; the impact of including polarizabilities of molecules in the parameterization is also considered. Parameters for the elements H, C, N, O, and S are presented. The Root Mean Square Deviation (RMSD) interaction energy is improved from 6.07 kcal/mol to 1.49 kcal/mol for interactions with one charged species, whereas the RMSD is improved from 5.60 kcal/mol to 1.73 for a set of 9 salt bridges, compared to uncorrected DFTB3. For large water clusters and complexes that are dominated by dispersion interactions, the already satisfactory performance of the DFTB3-D3 model is retained; polarizabilities of neutral molecules are also notably improved. Overall, the CPE extension of DFTB3-D3 provides a more balanced description of different types of non-covalent interactions than Neglect of Diatomic Differential Overlap type of semi-empirical methods (e.g., PM6-D3H4) and PBE-D3 with modest basis sets.

Consumer exposure to chemicals in indoor environment : A specific focus on chemicals from textile products

NARCIS (Netherlands)

Wijnhoven SWP; Kooi MW; te Biesebeek JD; SIR; vgc

2010-01-01

Textile products in indoor environment contain a variety of chemicals. Well-known examples are flame retardants, phthalates, formaldehyde and dimethylfumarate. Consumers are potentially exposed to these chemicals since a lot of textile products are present in indoor environment (clothing, curtains,

Prioritizing Environmental Chemicals for Obesity and Diabetes ...

Science.gov (United States)

Background: Diabetes and obesity are major threats to public health in the US and abroad. Understanding the role chemicals in our environment play in the development of these conditions is an emerging issue in environmental health, although identifying and prioritizing chemicals for testing beyond those already implicated in the literature is a challenge. This review is intended to help researchers generate hypotheses about chemicals potentially contributing to diabetes and obesity-related health outcomes by summarizing relevant findings from the US Environmental Protection Agency (EPA) ToxCast high-throughput screening (HTS) program. Objectives: To develop new hypotheses around environmental chemicals of potential interest for diabetes- or obesity-related outcomes using high throughput screening data. Methods: Identify ToxCast assay targets relevant to several biological processes related to diabetes and obesity (insulin sensitivity in peripheral tissue, pancreatic islet and beta cell function, adipocyte dierentiation, and feeding behavior) and present chemical screening data against those assay targets to identify chemicals of potential interest. Discussion: Results of this screening-level analysis suggest that the spectrum of environmental chemicals to consider in research related to diabetes and obesity is much broader than indicated from research papers and reviews published in the peer-reviewed literature. Testing of hypotheses based on ToxCast data will a

Composition and partition functions of partially ionized hydrogen plasma in Non-Local Thermal Equilibrium (Non-LThE) and Non-Local Chemical Equilibrium (Non-LChE)

International Nuclear Information System (INIS)

Chen Kuan; Eddy, T.L.

1993-01-01

A GTME (Generalized MultiThermodynamic Equilibrium) plasma model is developed for plasmas in both Non-LThE (Non-Local Thermal Equilibrium) and Non-LChE (Non-Local Chemical Equilibrium). The model uses multitemperatures for thermal nonequilibrium and non-zero chemical affinities as a measure of the deviation from chemical equilibrium. The plasma is treated as an ideal gas with the Debye-Hueckel approximation employed for pressure correction. The proration method is used when the cutoff energy level is between two discrete levels. The composition and internal partition functions of a hydrogen plasma are presented for electron temperatures ranging from 5000 to 35000 K and pressures from 0.1 to 1000 kPa. Number densities of 7 different species of hydrogen plasma and internal partition functions of different energy modes (rotational, vibrational, and electronic excitation) are computed for three affinity values. The results differ from other plasma properties in that they 1) are not based on equilibrium properties; and 2) are expressed as a function of different energy distribution parameters (temperatures) within each energy mode of each species as appropriate. The computed number densities and partition functions are applicable to calculating the thermodynamic, transport, and radiation properties of a hydrogen plasma not in thermal and chemical equilibria. The nonequilibrium plasma model and plasma compositions presented in this paper are very useful to the diagnosis of high-speed and/or low-pressure plasma flows in which the assumptions of local thermal and chemical equilibrium are invalid. (orig.)

Biobased chemicals from polyhydroxybutyrate

OpenAIRE

Spekreijse, Jurjen

2016-01-01

Currently, most chemicals and materials are obtained from fossil resources. After use, these chemicals and materials are converted to CO2. As discussed in chapter 1, this causes a build-up of CO2 in the atmosphere, the main driving force of global warming. In order to reach a sustainable system, biomass could be used as a resource for chemicals and materials instead. A biorefinery approach, where all parts of biomass are used to its full potential is essential. Taking this into consideration,...

Electrostatic potentials and energy loss due to a projectile propagating through a non-Maxwellian dusty plasma

International Nuclear Information System (INIS)

Deeba, F.; Ahmad, Zahoor; Murtaza, G.

2006-01-01

The electrostatic potentials (Debye and wake) and energy loss due to a charged projectile propagating through an unmagnetized collisionless dusty plasma are derived employing kappa and generalized (r,q) velocity distributions for the dust acoustic wave. It is found that these quantities in general differ from their Maxwellian counterparts and are sensitive to the values of spectral index, κ in the case of kappa distribution and to r, q in the case of generalized (r,q) distribution. The amplitudes of these quantities are less for small values of the spectral index (κ, r=0, q) but approach the Maxwellian in the limit κ→∞ (for kappa distribution) and for r=0, q→∞ [for generalized (r,q) distribution]. For any nonzero value of r, the potential and the energy loss grow beyond the Maxwellian results. The effect of kappa and generalized (r,q) distributions on potential and energy loss is also studied numerically and the results are compared with those of the Maxwellian distribution

Chemical potential for the interacting classical gas and the ideal quantum gas obeying a generalized exclusion principle

International Nuclear Information System (INIS)

Sevilla, F J; Olivares-Quiroz, L

2012-01-01

In this work, we address the concept of the chemical potential μ in classical and quantum gases towards the calculation of the equation of state μ = μ(n, T) where n is the particle density and T the absolute temperature using the methods of equilibrium statistical mechanics. Two cases seldom discussed in elementary textbooks are presented with detailed calculations. The first one refers to the explicit calculation of μ for the interacting classical gas exemplified by van der Waals gas. For this purpose, we used the method described by van Kampen (1961 Physica 27 783). The second one refers to the calculation of μ for ideal quantum gases that obey a generalized Pauli's exclusion principle that leads to statistics that go beyond the Bose-Einstein and Fermi-Dirac cases. The audience targeted in this work corresponds mainly to advanced undergraduates and graduate students in the physical-chemical sciences but it is not restricted to them. In regard of this, we have put a special emphasis on showing some additional details of calculations that usually do not appear explicitly in textbooks. (paper)

The potentiality of botanicals and their products as an alternative to chemical insecticides to sandflies (Diptera: Psychodidae): a review.

Science.gov (United States)

Dinesh, Diwakar Singh; Kumari, Seema; Kumar, Vijay; Das, Pradeep

2014-03-01

Use of chemical pesticides is the current method for controlling sandflies. However, resistance is being developed in sandflies against the insecticide of choice that is DDT (dichlorodiphenyl trichloroethane). Botanicals have potential to act as an alternative to chemical insecticides as the crude extracts and active molecules of some plants show insecticidal effect to sandflies. This will lead to safe, easy and environment friendly method for control of sandflies. Therefore, information regarding botanicals acting as alternative to chemical insecticide against sandflies assumes importance in the context of development of resistance to insecticides as well as to prevent environment from contamination. This review deals with some plants and their products having repellent and insecticidal effect to sandflies in India and abroad. Different methods of extraction and their bioassay on sandflies have been emphasized in the text. Various extracts of some plants like Ricinus communis (Euphorbiaceae), Solanum jasminoides (Solanaceae), Bougainvillea glabra (Nyctaginaceae), Capparis spinosa (Capparidaceae), Acalypha fruticosa (Euphorbiaceae) and Tagetes minuta (Asteraceae) had shown repellent/insecticidal effect on sandflies. This review will be useful in conducting the research work to find out botanicals of Indian context having insecticidal effect on sandflies.

Chemical bonding analysis for solid-state systems using intrinsic oriented quasiatomic minimal-basis-set orbitals

International Nuclear Information System (INIS)

Yao, Y.X.; Wang, C.Z.; Ho, K.M.

2010-01-01

A chemical bonding scheme is presented for the analysis of solid-state systems. The scheme is based on the intrinsic oriented quasiatomic minimal-basis-set orbitals (IO-QUAMBOs) previously developed by Ivanic and Ruedenberg for molecular systems. In the solid-state scheme, IO-QUAMBOs are generated by a unitary transformation of the quasiatomic orbitals located at each site of the system with the criteria of maximizing the sum of the fourth power of interatomic orbital bond order. Possible bonding and antibonding characters are indicated by the single particle matrix elements, and can be further examined by the projected density of states. We demonstrate the method by applications to graphene and (6,0) zigzag carbon nanotube. The oriented-orbital scheme automatically describes the system in terms of sp 2 hybridization. The effect of curvature on the electronic structure of the zigzag carbon nanotube is also manifested in the deformation of the intrinsic oriented orbitals as well as a breaking of symmetry leading to nonzero single particle density matrix elements. In an additional study, the analysis is performed on the Al 3 V compound. The main covalent bonding characters are identified in a straightforward way without resorting to the symmetry analysis. Our method provides a general way for chemical bonding analysis of ab initio electronic structure calculations with any type of basis sets.

Chemical characterization of 21 species of marine macroalgae common in Norwegian waters: benefits of and limitations to their potential use in food and feed

Science.gov (United States)

Biancarosa, Irene; Belghit, Ikram; Bruckner, Christian G; Liland, Nina S; Waagbø, Rune; Amlund, Heidi; Heesch, Svenja

2018-01-01

Abstract BACKGROUND In the past few years, much effort has been invested into developing a new blue economy based on harvesting, cultivating and processing marine macroalgae in Norway. Macroalgae have high potential for a wide range of applications, e.g. as source of pharmaceuticals, production of biofuels or as food and feed. However, data on the chemical composition of macroalgae from Norwegian waters are scant. This study was designed to characterize the chemical composition of 21 algal species. Both macro‐ and micronutrients were analysed. Concentrations of heavy metals and the metalloid arsenic in the algae were also quantified. RESULTS The results confirm that marine macroalgae contain nutrients which are relevant for both human and animal nutrition, the concentrations whereof are highly dependent on species. Although heavy metals and arsenic were detected in the algae studied, concentrations were mostly below maximum allowed levels set by food and feed legislation in the EU. CONCLUSION This study provides chemical data on a wide range of algal species covering the three taxonomic groups (brown, red and green algae) and discusses both benefits of and potential limitations to their use for food and feed purposes. © 2017 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:29193189

A Sinusoidal Applied Electric Potential can Induce a Long-Range, Steady Electrophoretic Force

Science.gov (United States)

Amrei, Seyyed Hashemi; Ristenpart, William D.; Miller, Greg R.

2017-11-01

We use the standard electrokinetic model to numerically investigate the electric field in aqueous solutions between parallel electrodes under AC polarization. In contrast to prior work, we invoke no simplifying assumptions regarding the applied voltage, frequency, or mismatch in ionic mobilities. We find that the nonlinear electromigration terms significantly contribute to the overall shape of the electric potential vs. time, which at sufficiently high applied potentials develops multi-modal peaks. More surprisingly, we find that electrolytes with non-equal mobilities yield an electric field with non-zero time average at large distances from the electrodes. Our calculations indicate this long-range electric field suffices to levitate colloidal particles many microns away from the electrode against the gravitational field, in accord with experimental observations of such behavior (Woehl et al., PRX, 2015). Moreover, the results indicate that particles will aggregate laterally near electrodes in some electrolytes but separate in others, helping explain a longstanding but not well understood phenomenon.

Chemical characterization by GC-MS and phytotoxic potential of non-polar and polar fractions of seeds of Dioteryx odorata (Aubl. Willd. from Venezuelan regions

Directory of Open Access Journals (Sweden)

Alberto de J. Oliveros-Bastidas

2013-01-01

Full Text Available Dipteryx odorata (Aubl. Willd. is a tall arboreal species native to Central and Northern South America. This paper describes the chemical characterization and phytotoxic potential of polar and non-polar extracts from D. odorata seeds. Structural determinations were accomplished by chemical derivatization and analyzed by GC/MS. The chemical composition of the non-polar fraction (hexane and dichloromethane presented fatty acids as major constituent. Medium polar and polar fractions (ethyl acetate and ethanol: water contained carboxylic acid and high 6,7-Dyhidroxycoumarin-β-D-glucopyranoside content, not previously reported for seeds of D. odorata. Extracts showed a significant level of phytotoxic activity, correlated to the content of coumarin derivatives, predominantly in the polar fraction.

Chemical and non-chemical stressors affecting childhood obesity: a systematic scoping review.

Science.gov (United States)

Lichtveld, Kim; Thomas, Kent; Tulve, Nicolle S

2018-01-01

Childhood obesity in the United States has doubled over the last three decades and currently affects 17% of children and adolescents. While much research has focused on individual behaviors impacting obesity, little research has emphasized the complex interactions of numerous chemical and non-chemical stressors found in a child's environment and how these interactions affect a child's health and well-being. The objectives of this systematic scoping review were to (1) identify potential chemical stressors in the context of non-chemical stressors that impact childhood obesity; and, (2) summarize our observations for chemical and non-chemical stressors in regards to child-specific environments within a community setting. A review was conducted to identify chemical and non-chemical stressors related to childhood obesity for the childhood life stages ranging from prenatal to adolescence. Stressors were identified and grouped into domains: individual behaviors, family/household behaviors, community stressors, and chemical exposures. Stressors were related to the child and the child's everyday environments and used to characterize child health and well-being. This review suggests that the interactions of chemical and non-chemical stressors are important for understanding a child's overall health and well-being. By considering these relationships, the exposure science research community can better design and implement strategies to reduce childhood obesity.

Phases of Holographic QCD

International Nuclear Information System (INIS)

Lippert, Matthew

2009-01-01

We investigated the Sakai-Sugimoto model of large N QCD at nonzero temperature and baryon chemical potential and in the presence of background electric and magnetic fields. We studied the holographic representation of baryons and the deconfinement, chiral-symmetry breaking, and nuclear matter phase transitions. In a background electric field, chiral-symmetry breaking corresponds to an insulator-conductor transition. A magnetic field both catalyzes chiral-symmetry breaking and generates, in the confined phase, a pseudo-scalar gradient or, in the deconfined phase, an axial current. The resulting phase diagram is in qualitative agreement with studies of hot, dense QCD.

Chemical composition, antimicrobial and antioxidant potential of the essential oil of Guarea kunthiana A. Juss.

Science.gov (United States)

Pandini, J A; Pinto, F G S; Scur, M C; Santana, C B; Costa, W F; Temponi, L G

2018-02-01

The essential oils are extracted from plant compounds and can present activities antimicrobial and antioxidant properties. The goals of the present study were: (a) to determine the chemical composition of the essential oil of Guarea kunthiana A. Juss using the method of gas chromatography coupled to mass spectrometry (GC-MS); (b) to evaluate the antimicrobial potential of this oil using the broth microdilution method against different microorganisms: five Gram-negative bacteria, four Gram-positive bacteria and a yeast and (c) to determine the antioxidant activity of the oil using the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical assay. The GC-MS analyses allowed identifying 13 constituents, representing 96.52% of the essencial oil composition. The main compounds identified were α-zingiberene (34.48%), β-sesquiphellandrene (22.90%), and α-curcumene (16.17%). With respect to the antimicrobial activity, the essential oil was effective against all the microorganisms tested, except for the bacteria E. coli and K. pneumoniae, which were resistant to the action of the oil. From a general point of view, Gram-positive bacteria were more susceptible to the action of the essential oil than Gram-negative bacteria. The essential oil exhibited antioxidant potential.

Effects of chemical carcinogens of hemopoiesis, immunopoiesis and viral oncogenesis. Technical progress report, December 1, 1977--September 30, 1978. [Mechanisms of potentiation of viral leukemogenesis by MMS, benzopyrene, and DMBA

Energy Technology Data Exchange (ETDEWEB)

OKunewick, J.P.; Raikow, R.B.; Meredith, R.F.

1978-10-01

During the past year we have concentrated on defining the circumstances under which methyl methanesulfonate (MMS), benzo(a) pyrene (BP), and 7,12-dimethylbenz(a)anthracene (DMBA) interact with Friend virus (FLV) to produce leukemia. The optimum scheduling for each and also the effective dose levels of the chemicals have been partially determined. There are at least three critical factors which govern whether or not a leukemogenic interaction can be shown between the chemical agents and the virus. These are chemical dose, virus dose, and their relative time of administration. The most critical of these is virus dose. The optimum virus dose is that which results in between 25 and 40% incidence of leukemia within 40 days after virus infection when virus is given alone. The chemical carcinogens have a lower dose threshold, below which no significant potentiating effect can be observed. The only upper limit would appear to be acute drug toxicity. The third element, timing, is equally critical and varies according to the chemical. This variation may reflect different mechanisms of action by the chemical agents and/or different pharmacology. Data on the effects of MMS, BP, and DMBA on the immune system have indicated that the viral enhancement is probably not dependent on this function. Further enhancement of the potentiation of viral leukemogenesis was observed using benzo(a)pyrene and caffeine, indicating that the inhibition by caffeine of DNA repair may be an important factor in virus potentiation. (ERB)

Fuel and Chemicals from Renewable Alcohols

DEFF Research Database (Denmark)

Hansen, Jeppe Rass

2008-01-01

The present work entitled Fuel and Chemicals from Renewable Alcohols covers the idea of developing routes for producing sustainable fuel and chemicals from biomass resources. Some renewable alcohols are already readily available from biomass in significant amounts and thus the potential...... for these renewable alcohols, together with other primary renewable building blocks, has been highlighted in the introductory chapter. While the first chapter covers the general potential of a renewable chemical industry, the other chapters deal with particular possibilities. It is shown how ethanol and glycerol can...... be converted into hydrogen by steam reforming over nickel or ruthenium based catalysts. This process could be important in a future hydrogen society, where hydrogen can be utilized in high efficiency fuel cells. Hydrogen produced from biofeedstocks can also be used directly in the chemical industry, where...

Chemical substructure analysis in toxicology

Energy Technology Data Exchange (ETDEWEB)

Beauchamp, R.O. Jr. [Center for Information on Toxicology and Environment, Raleigh, NC (United States)

1990-12-31

A preliminary examination of chemical-substructure analysis (CSA) demonstrates the effective use of the Chemical Abstracts compound connectivity file in conjunction with the bibliographic file for relating chemical structures to biological activity. The importance of considering the role of metabolic intermediates under a variety of conditions is illustrated, suggesting structures that should be examined that may exhibit potential activity. This CSA technique, which utilizes existing large files accessible with online personal computers, is recommended for use as another tool in examining chemicals in drugs. 2 refs., 4 figs.

Few-Layer Nanoplates of Bi 2 Se 3 and Bi 2 Te 3 with Highly Tunable Chemical Potential

KAUST Repository

Kong, Desheng

2010-06-09

A topological insulator (TI) represents an unconventional quantum phase of matter with insulating bulk band gap and metallic surface states. Recent theoretical calculations and photoemission spectroscopy measurements show that group V-VI materials Bi2Se3, Bi2Te3, and Sb2Te3 are TIs with a single Dirac cone on the surface. These materials have anisotropic, layered structures, in which five atomic layers are covalently bonded to form a quintuple layer, and quintuple layers interact weakly through van der Waals interaction to form the crystal. A few quintuple layers of these materials are predicted to exhibit interesting surface properties. Different from our previous nanoribbon study, here we report the synthesis and characterizations of ultrathin Bi2Te3 and Bi2Se3 nanoplates with thickness down to 3 nm (3 quintuple layers), via catalyst-free vapor-solid (VS) growth mechanism. Optical images reveal thickness-dependent color and contrast for nanoplates grown on oxidized silicon (300 nm SiO2/Si). As a new member of TI nanomaterials, ultrathin TI nanoplates have an extremely large surface-to-volume ratio and can be electrically gated more effectively than the bulk form, potentially enhancing surface state effects in transport measurements. Low-temperature transport measurements of a single nanoplate device, with a high-k dielectric top gate, show decrease in carrier concentration by several times and large tuning of chemical potential. © 2010 American Chemical Society.

Improvement of Expansive Soils Using Chemical Stabilizers

Science.gov (United States)

Ikizler, S. B.; Senol, A.; Khosrowshahi, S. K.; Hatipoğlu, M.

2014-12-01

The aim of this study is to investigate the effect of two chemical stabilizers on the swelling potential of expansive soil. A high plasticity sodium bentonite was used as the expansive soil. The additive materials including fly ash (FA) and lime (L) were evaluated as potential stabilizers to decrease the swelling pressure of bentonite. Depending on the type of additive materials, they were blended with bentonite in different percentages to assess the optimum state and approch the maximum swell pressure reduction. According to the results of swell pressure test, both fly ash and lime reduce the swelling potential of bentonite but the maximum improvement occurs using bentonite-lime mixture while the swelling pressure reduction approaches to 49%. The results reveal a significant reduction of swelling potential of expansive soil using chemical stabilizers. Keywords: Expansive soil; swell pressure; chemical stabilization; fly ash; lime

Endocrine-disrupting chemicals and public health protection

DEFF Research Database (Denmark)

Zoeller, R Thomas; Brown, T R; Doan, L L

2012-01-01

An endocrine-disrupting chemical (EDC) is an exogenous chemical, or mixture of chemicals, that can interfere with any aspect of hormone action. The potential for deleterious effects of EDC must be considered relative to the regulation of hormone synthesis, secretion, and actions and the variabili...

Potential of plant growth promoting rhizobacteria and chemical fertilizers on soil enzymes and plant growth

International Nuclear Information System (INIS)

Nosheen, A.; Bano, A.

2014-01-01

The present investigation deals with the role of Plant Growth Promoting Rhizobacteria and chemical fertilizers alone or in combination on urease, invertase and phosphatase activities of rhizospheric soil and also on general impact on growth of safflower cvv. Thori and Saif-32. The PGPR (Azospirillum brasilense and Azotobacter vinelandii) were applied at 10/sup 6/ cells/mL as seed inoculation prior to sowing. Chemical fertilizers were applied at full (Urea 60 Kg ha/sup -1/ and Diammonium phosphate (DAP) 30 Kg ha/sup -1/), half (Urea 30 Kg ha/sup -1/ and DAP 15 Kg ha/sup -1/) and quarter doses (Urea 15 Kg ha-1 and DAP 7.5 Kg ha/sup -1/) during sowing. The chemical fertilizers and PGPR enhanced urease and invertase activities of soil. Presence of PGPR in combination with quarter and half doses of chemical fertilizers further augmented their effect on soil enzymes activities. The soil phosphatase activity was greater in Azospirillum and Azotobacter in combination with half dose of chemical fertilizers. Maximum increase in leaf melondialdehyde content was recorded in full dose of chemical fertilizers whereas coinoculation treatment exhibited significant reduction in cv. Thori. Half and quarter dose of chemical fertilizers increased the shoot length of safflower whereas maximum increase in leaf protein was recorded in Azotobacter in combination with full dose of chemical fertilizers. Root length was improved by Azospirillum and Azotobacter in combination with quarter dose of chemical fertilizers. Leaf area and chlorophyll contents were significantly improved by Azotobacter in combination with half dose of chemical fertilizers. It is inferred that PGPR can supplement 50 % chemical fertilizers for better plant growth and soil health. (author)

Objective, Quantitative, Data-Driven Assessment of Chemical Probes.

Science.gov (United States)

Antolin, Albert A; Tym, Joseph E; Komianou, Angeliki; Collins, Ian; Workman, Paul; Al-Lazikani, Bissan

2018-02-15

Chemical probes are essential tools for understanding biological systems and for target validation, yet selecting probes for biomedical research is rarely based on objective assessment of all potential compounds. Here, we describe the Probe Miner: Chemical Probes Objective Assessment resource, capitalizing on the plethora of public medicinal chemistry data to empower quantitative, objective, data-driven evaluation of chemical probes. We assess >1.8 million compounds for their suitability as chemical tools against 2,220 human targets and dissect the biases and limitations encountered. Probe Miner represents a valuable resource to aid the identification of potential chemical probes, particularly when used alongside expert curation. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Chemical analysis and biological potential of Valerian root as used ...

African Journals Online (AJOL)

The herb prepared from this plant was studied to determine the chemical composition of its essential oil, carried out phytochemical screening and biological activities on ... rat paw oedema model comparable to aspirin, indicating anti-inflammatory activity; but lacked analgesic activity on the acetic acid-induced writhing test.

Identification of new candidate drugs for lung cancer using chemical-chemical interactions, chemical-protein interactions and a K-means clustering algorithm.

Science.gov (United States)

Lu, Jing; Chen, Lei; Yin, Jun; Huang, Tao; Bi, Yi; Kong, Xiangyin; Zheng, Mingyue; Cai, Yu-Dong

2016-01-01

Lung cancer, characterized by uncontrolled cell growth in the lung tissue, is the leading cause of global cancer deaths. Until now, effective treatment of this disease is limited. Many synthetic compounds have emerged with the advancement of combinatorial chemistry. Identification of effective lung cancer candidate drug compounds among them is a great challenge. Thus, it is necessary to build effective computational methods that can assist us in selecting for potential lung cancer drug compounds. In this study, a computational method was proposed to tackle this problem. The chemical-chemical interactions and chemical-protein interactions were utilized to select candidate drug compounds that have close associations with approved lung cancer drugs and lung cancer-related genes. A permutation test and K-means clustering algorithm were employed to exclude candidate drugs with low possibilities to treat lung cancer. The final analysis suggests that the remaining drug compounds have potential anti-lung cancer activities and most of them have structural dissimilarity with approved drugs for lung cancer.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

DFT global chemical reactivity descriptors (chemical hardness, total energy, electronic chemical potential, and electrophilicity) are calculated for the isomers and used to predict their relative stability and reactivity. The chemical reactivity indices are found to be related to the bond angle defined by the cis carbonyls and the ...

Crystalline color superconductivity

International Nuclear Information System (INIS)

Alford, Mark; Bowers, Jeffrey A.; Rajagopal, Krishna

2001-01-01

In any context in which color superconductivity arises in nature, it is likely to involve pairing between species of quarks with differing chemical potentials. For suitable values of the differences between chemical potentials, Cooper pairs with nonzero total momentum are favored, as was first realized by Larkin, Ovchinnikov, Fulde, and Ferrell (LOFF). Condensates of this sort spontaneously break translational and rotational invariance, leading to gaps which vary periodically in a crystalline pattern. Unlike the original LOFF state, these crystalline quark matter condensates include both spin-zero and spin-one Cooper pairs. We explore the range of parameters for which crystalline color superconductivity arises in the QCD phase diagram. If in some shell within the quark matter core of a neutron star (or within a strange quark star) the quark number densities are such that crystalline color superconductivity arises, rotational vortices may be pinned in this shell, making it a locus for glitch phenomena

Charges in nonlinear higher-spin theory

Energy Technology Data Exchange (ETDEWEB)

Didenko, V.E. [I.E. Tamm Department of Theoretical Physics, Lebedev Physical Institute,Leninsky prospect 53, 119991, Moscow (Russian Federation); Misuna, N.G. [I.E. Tamm Department of Theoretical Physics, Lebedev Physical Institute,Leninsky prospect 53, 119991, Moscow (Russian Federation); Moscow Institute of Physics and Technology,Institutsky lane 9, 141700, Dolgoprudny, Moscow region (Russian Federation); Vasiliev, M.A. [I.E. Tamm Department of Theoretical Physics, Lebedev Physical Institute,Leninsky prospect 53, 119991, Moscow (Russian Federation)

2017-03-30

Nonlinear higher-spin equations in four dimensions admit a closed two-form that defines a gauge-invariant global charge as an integral over a two-dimensional cycle. In this paper we argue that this charge gives rise to partitions depending on various lower- and higher-spin chemical potentials identified with modules of topological fields in the theory. The vacuum contribution to the partition is calculated to the first nontrivial order for a solution to higher-spin equations that generalizes AdS{sub 4} Kerr black hole of General Relativity. The resulting partition is non-zero being in parametric agreement with the ADM-like behavior of a rotating source. The linear response of chemical potentials to the partition function is also extracted. The explicit unfolded form of 4d GR black holes is given. An explicit formula relating asymptotic higher-spin charges expressed in terms of the generalized higher-spin Weyl tensor with those expressed in terms of Fronsdal fields is obtained.

Charges in nonlinear higher-spin theory

International Nuclear Information System (INIS)

Didenko, V.E.; Misuna, N.G.; Vasiliev, M.A.

2017-01-01

Nonlinear higher-spin equations in four dimensions admit a closed two-form that defines a gauge-invariant global charge as an integral over a two-dimensional cycle. In this paper we argue that this charge gives rise to partitions depending on various lower- and higher-spin chemical potentials identified with modules of topological fields in the theory. The vacuum contribution to the partition is calculated to the first nontrivial order for a solution to higher-spin equations that generalizes AdS 4 Kerr black hole of General Relativity. The resulting partition is non-zero being in parametric agreement with the ADM-like behavior of a rotating source. The linear response of chemical potentials to the partition function is also extracted. The explicit unfolded form of 4d GR black holes is given. An explicit formula relating asymptotic higher-spin charges expressed in terms of the generalized higher-spin Weyl tensor with those expressed in terms of Fronsdal fields is obtained.

Potential for Intermodal Transport of Chemical Goods in Slovakia

Directory of Open Access Journals (Sweden)

Jagelčák Juraj

2017-01-01

Full Text Available This article deals with intermodal transport of chemical goods in Slovak republic. Analysis is based on information from interviews with companies and logistics service providers. The first part of the article describes importance of Intermodal transport and basic transport routes for intermodal transport. Respondents considered advantages and disadvantages of intermodal transport. Possible improvements inside companies and improvements of external framework conditions to promote modal shift are described in the second part of the paper.

Does chemical aposematic (warning) signaling occur between host plants and their potential parasitic plants?

Science.gov (United States)

Lev-Yadun, Simcha

2013-07-01

Aposematism (warning) signaling is a common defensive mechanism toward predatory or herbivorous animals, i.e., interactions between different trophic levels. I propose that it should be considered at least as a working hypothesis that chemical aposematism operates between certain host plants and their plant predators, parasitic plants, and that although they are also plants, they belong to a higher trophic level. Specific host plant genotypes emit known repelling chemical signals toward parasitic plants, which reduce the level of, slow the directional parasite growth (attack) toward the signaling hosts, or even cause parasitic plants to grow away from them in response to these chemicals. Chemical host aposematism toward parasitic plants may be a common but overlooked defense from parasitic plants.

Effect of thermal, chemical and thermo-chemical pre-treatments to enhance methane production

Energy Technology Data Exchange (ETDEWEB)

Rafique, Rashad; Nizami, Abdul-Sattar; Murphy, Jerry D.; Kiely, Gerard [Department of Civil and Environmental Engineering, University College Cork (Ireland); Poulsen, Tjalfe Gorm [Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University (Denmark); Asam, Zaki-ul-Zaman [Department of Civil Engineering, National University of Ireland Galway (Ireland)

2010-12-15

The rise in oil price triggered the exploration and enhancement of various renewable energy sources. Producing biogas from organic waste is not only providing a clean sustainable indigenous fuel to the number of on-farm digesters in Europe, but also reducing the ecological and environmental deterioration. The lignocellulosic substrates are not completely biodegraded in anaerobic digesters operating at commercial scale due to their complex physical and chemical structure, which result in meager energy recovery in terms of methane yield. The focus of this study is to investigate the effect of pre-treatments: thermal, thermo-chemical and chemical pre-treatments on the biogas and methane potential of dewatered pig manure. A laboratory scale batch digester is used for these pre-treatments at different temperature range (25 C-150 C). Results showed that thermo-chemical pretreatment has high effect on biogas and methane potential in the temperature range (25-100 C). Maximum enhancement is observed at 70 C with increase of 78% biogas and 60% methane production. Thermal pretreatment also showed enhancement in the temperature range (50-10 C), with maximum enhancement at 100 C having 28% biogas and 25% methane increase. (author)

Foundational aspects of the concept of chemical activity

DEFF Research Database (Denmark)

Mayer, Philipp

2015-01-01

The chemical activity of an organic chemical quantifies its potential for spontaneous physicochemical processes, such as diffusion, sorption, and partitioning. For instance, the chemical activity of a sediment contaminant determines its equilibrium partitioning concentration in sediment-dwelling ...

Chemical Structure, Property and Potential Applications of Biosurfactants Produced by Bacillus subtilis in Petroleum Recovery and Spill Mitigation

Science.gov (United States)

Liu, Jin-Feng; Mbadinga, Serge Maurice; Yang, Shi-Zhong; Gu, Ji-Dong; Mu, Bo-Zhong

2015-01-01

Lipopeptides produced by microorganisms are one of the five major classes of biosurfactants known and they have received much attention from scientific and industrial communities due to their powerful interfacial and biological activities as well as environmentally friendly characteristics. Microbially produced lipopeptides are a series of chemical structural analogues of different families and, among them, 26 families covering about 90 lipopeptide compounds have been reported in the last two decades. This paper reviews the chemical structural characteristics and molecular behaviors of surfactin, one of the representative lipopeptides of the 26 families. In particular, two novel surfactin molecules isolated from cell-free cultures of Bacillus subtilis HSO121 are presented. Surfactins exhibit strong self-assembly ability to form sphere-like micelles and larger aggregates at very low concentrations. The amphipathic and surface properties of surfactins are related to the existence of the minor polar and major hydrophobic domains in the three 3-D conformations. In addition, the application potential of surfactin in bioremediation of oil spills and oil contaminants, and microbial enhanced oil recovery are discussed. PMID:25741767

Chemical Structure, Property and Potential Applications of Biosurfactants Produced by Bacillus subtilis in Petroleum Recovery and Spill Mitigation

Directory of Open Access Journals (Sweden)

Jin-Feng Liu

2015-03-01

Full Text Available Lipopeptides produced by microorganisms are one of the five major classes of biosurfactants known and they have received much attention from scientific and industrial communities due to their powerful interfacial and biological activities as well as environmentally friendly characteristics. Microbially produced lipopeptides are a series of chemical structural analogues of different families and, among them, 26 families covering about 90 lipopeptide compounds have been reported in the last two decades. This paper reviews the chemical structural characteristics and molecular behaviors of surfactin, one of the representative lipopeptides of the 26 families. In particular, two novel surfactin molecules isolated from cell-free cultures of Bacillus subtilis HSO121 are presented. Surfactins exhibit strong self-assembly ability to form sphere-like micelles and larger aggregates at very low concentrations. The amphipathic and surface properties of surfactins are related to the existence of the minor polar and major hydrophobic domains in the three 3-D conformations. In addition, the application potential of surfactin in bioremediation of oil spills and oil contaminants, and microbial enhanced oil recovery are discussed.

Interactions of C+(2PJ) with rare gas atoms: incipient chemical interactions, potentials and transport coefficients

Science.gov (United States)

Tuttle, William D.; Thorington, Rebecca L.; Viehland, Larry A.; Breckenridge, W. H.; Wright, Timothy G.

2018-03-01

Accurate interatomic potentials were calculated for the interaction of a singly charged carbon cation, C+, with a single rare gas atom, RG (RG = Ne-Xe). The RCCSD(T) method and basis sets of quadruple-ζ and quintuple-ζ quality were employed; each interaction energy was counterpoise corrected and extrapolated to the basis set limit. The lowest C+(2P) electronic term of the carbon cation was considered, and the interatomic potentials calculated for the diatomic terms that arise from these: 2Π and 2Σ+. Additionally, the interatomic potentials for the respective spin-orbit levels were calculated, and the effect on the spectroscopic parameters was examined. In doing this, anomalously large spin-orbit splittings for RG = Ar-Xe were found, and this was investigated using multi-reference configuration interaction calculations. The latter indicated a small amount of RG → C+ electron transfer and this was used to rationalize the observations. This is taken as evidence of an incipient chemical interaction, which was also examined via contour plots, Birge-Sponer plots and various population analyses across the C+-RG series (RG = He-Xe), with the latter showing unexpected results. Trends in several spectroscopic parameters were examined as a function of the increasing atomic number of the RG atom. Finally, each set of RCCSD(T) potentials was employed, including spin-orbit coupling to calculate the transport coefficients for C+ in RG, and the results were compared with the limited available data. This article is part of the theme issue `Modern theoretical chemistry'.

Can phylogeny predict chemical diversity and potential medicinal activity of plants? A case study of Amaryllidaceae

DEFF Research Database (Denmark)

Rønsted, Nina; Symonds, Matthew R. E.; Birkholm, Trine

2012-01-01

a predictive approach enabling more efficient selection of plants for the development of traditional medicine and lead discovery. However, this relationship has rarely been rigorously tested and the potential predictive power is consequently unknown. Results: We produced a phylogenetic hypothesis......Background: During evolution, plants and other organisms have developed a diversity of chemical defences, leading to the evolution of various groups of specialized metabolites selected for their endogenous biological function. A correlation between phylogeny and biosynthetic pathways could offer...... for the medicinally important plant subfamily Amaryllidoideae (Amaryllidaceae) based on parsimony and Bayesian analysis of nuclear, plastid, and mitochondrial DNA sequences of over 100 species. We tested if alkaloid diversity and activity in bioassays related to the central nervous system are significantly correlated...

Nonequilibrium chemical potential in a two-dimensional electron gas in the quantum-Hall-effect regime

Energy Technology Data Exchange (ETDEWEB)

Pokhabov, D. A., E-mail: pokhabov@isp.nsc.ru; Pogosov, A. G.; Budantsev, M. V.; Zhdanov, E. Yu.; Bakarov, A. K. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

2016-08-15

The nonequilibrium state of a two-dimensional electron gas in the quantum-Hall-effect regime is studied in Hall bars equipped with additional inner contacts situated within the bar. The magnetic-field dependence of the voltage drop between different contact pairs are studied at various temperatures. It was found that the voltage between the inner and outer contacts exhibits peaks of significant amplitude in narrow magnetic-field intervals near integer filling factors. Furthermore, the magnetic-field dependence of the voltage in these intervals exhibits a hysteresis, whereas the voltage between the outer contacts remains zero in the entire magnetic-field range. The appearance of the observed voltage peaks and their hysteretic behavior can be explained by an imbalance between the chemical potentials of edge and bulk states, resulting from nonequilibrium charge redistribution between the edge and bulk states when the magnetic field sweeps under conditions of the quantum Hall effect. The results of the study significantly complement the conventional picture of the quantum Hall effect, explicitly indicating the existence of a significant imbalance at the edge of the two-dimensional electron gas: the experimentally observed difference between the electrochemical potentials of the edge and bulk exceeds the distance between Landau levels by tens of times.

Chemical composition, antimicrobial and antioxidant potential of the essential oil of Guarea kunthiana A. Juss

Directory of Open Access Journals (Sweden)

J. A. Pandini

2017-07-01

Full Text Available Abstract The essential oils are extracted from plant compounds and can present activities antimicrobial and antioxidant properties. The goals of the present study were: (a to determine the chemical composition of the essential oil of Guarea kunthiana A. Juss using the method of gas chromatography coupled to mass spectrometry (GC-MS; (b to evaluate the antimicrobial potential of this oil using the broth microdilution method against different microorganisms: five Gram-negative bacteria, four Gram-positive bacteria and a yeast and (c to determine the antioxidant activity of the oil using the DPPH (2,2-diphenyl-1-picrylhydrazyl free radical assay. The GC-MS analyses allowed identifying 13 constituents, representing 96.52% of the essencial oil composition. The main compounds identified were α-zingiberene (34.48%, β-sesquiphellandrene (22.90%, and α-curcumene (16.17%. With respect to the antimicrobial activity, the essential oil was effective against all the microorganisms tested, except for the bacteria E. coli and K. pneumoniae, which were resistant to the action of the oil. From a general point of view, Gram-positive bacteria were more susceptible to the action of the essential oil than Gram-negative bacteria. The essential oil exhibited antioxidant potential.

Potential of Palm Olein as Green Lubricant Source: Lubrication Analysis and Chemical Characterisation

International Nuclear Information System (INIS)

Darfizzi Derawi; Jumat Salimon

2014-01-01

Palm olein (PO o ) is widely used as edible oil in tropical countries. The lubrication properties and chemical compositions of PO o being considered to be used as renewable raw material for bio lubricant synthesis. PO o is suitable to be used directly as bio lubricant for medium temperature industrial applications. Palm olein has good viscosity index, oxidative stability, flash and fire point as a lubricant source. PO o contains unsaturated triacylglycerols (TAG): Palmitin-Olein-Olein, POO (33.3 %), Palmitin-Olein-Palmitin, POP (29.6 %), which are very important to produce good lubricant properties. This unsaturated bond is preferable in chemical modification to produce bio lubricant. The chemical compositions of PO o were tested by using high performance liquid chromatography (HPLC) and gas chromatography (GC) techniques. (author)

Can phylogeny predict chemical diversity and potential medicinal activity of plants? A case study of amaryllidaceae

Directory of Open Access Journals (Sweden)

Rønsted Nina

2012-09-01

Full Text Available Abstract Background During evolution, plants and other organisms have developed a diversity of chemical defences, leading to the evolution of various groups of specialized metabolites selected for their endogenous biological function. A correlation between phylogeny and biosynthetic pathways could offer a predictive approach enabling more efficient selection of plants for the development of traditional medicine and lead discovery. However, this relationship has rarely been rigorously tested and the potential predictive power is consequently unknown. Results We produced a phylogenetic hypothesis for the medicinally important plant subfamily Amaryllidoideae (Amaryllidaceae based on parsimony and Bayesian analysis of nuclear, plastid, and mitochondrial DNA sequences of over 100 species. We tested if alkaloid diversity and activity in bioassays related to the central nervous system are significantly correlated with phylogeny and found evidence for a significant phylogenetic signal in these traits, although the effect is not strong. Conclusions Several genera are non-monophyletic emphasizing the importance of using phylogeny for interpretation of character distribution. Alkaloid diversity and in vitro inhibition of acetylcholinesterase (AChE and binding to the serotonin reuptake transporter (SERT are significantly correlated with phylogeny. This has implications for the use of phylogenies to interpret chemical evolution and biosynthetic pathways, to select candidate taxa for lead discovery, and to make recommendations for policies regarding traditional use and conservation priorities.

Influence of external magnetic field, finite-size effects and chemical potential on the phase transition of a complex scalar field

Energy Technology Data Exchange (ETDEWEB)

Cavalcanti, E.; Castro, E.; Malbouisson, A.P.C. [Centro Brasileiro de Pesquisas Fisicas/MCTI, Rio de Janeiro, RJ (Brazil); Linhares, C.A. [Universidade do Estado do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro, RJ (Brazil)

2017-10-15

A scalar model is built, as a quantum field theory defined on a toroidal topology, to describe a phase transition in films subjected to periodic boundary conditions and influenced by an external and constant magnetic field. Criticality is studied and the relations between the critical temperature, the film thickness, the magnetic field strength and the chemical potential are investigated. Since the model describes a second-order phase transition a comparison with the Ginzburg-Landau theory is made. (orig.)

The potential role of Life Cycle Assessment in regulation of chemicals in the European Union

DEFF Research Database (Denmark)

Christensen, Frans Møller; Olsen, Stig Irving

2003-01-01

The regulation of chemicals in EU is undergoing substantial changes these years with implementation of the “REACH” system. Simultaneously, the concepts of LCA and Integrated Product Policy (IPP) are becoming increasingly integrated in European standardisation and regulatory activities. As a logical...... consequence, the European Chemicals Bureau (ECB) has enrolled in the OMNIITOX project with the clear aim of investigating possible applications of LCA in future EU regulation of chemicals. Implementation of REACH will expand and change the activities and services currently delivered by ECB as the focal point...... uses of LCA could be in overall priority setting (including non-chemical products) of environmental product policy and in standardisation work related to products/processes releasing chemicals to the environment. A number of methodological interactions between regulatory risk assessment and LCA as well...

The AOP framework and causality: Meeting chemical risk ...

Science.gov (United States)

Chemical safety assessments are expanding from a focus on a few chemicals (or chemical mixtures) to the broader “universe” of thousands, if not hundreds of thousands of substances that potentially could impact humans or the environment. This is exemplified in regulatory activities such as the REACH program in Europe, or the recent reauthorization of TSCA in the US, which require consideration of the potential impacts of a much greater number of chemicals than in the past. The data needed to address these types of legislated mandates cannot realistically be obtained solely through using the whole animal testing approaches historically employed for chemical risk assessment. Rather, there needs to be an increased emphasis on cost-effective tools that enable robust prediction of potential chemical impacts when empirical data are lacking. Concurrent with the realization that predictive methods will need to play an increasingly prominent role in regulatory toxicology has been the recent explosion in technology in the biological sciences enabling collection of large amounts of pathway-based molecular and biochemical data. For example, genomic techniques and high-throughput (robotic-based) in vitro testing enable the generation of knowledge concerning the effects of chemical perturbation on biological systems in an increasingly efficient and rapid manner. However, a pressing need stemming from these technological advances is the ability to actually apply th

Additive mixture effects of estrogenic chemicals in human cell-based assays can be influenced by inclusion of chemicals with differing effect profiles.

Directory of Open Access Journals (Sweden)

Richard Mark Evans

Full Text Available A growing body of experimental evidence indicates that the in vitro effects of mixtures of estrogenic chemicals can be well predicted from the estrogenicity of their components by the concentration addition (CA concept. However, some studies have observed small deviations from CA. Factors affecting the presence or observation of deviations could include: the type of chemical tested; number of mixture components; mixture design; and assay choice. We designed mixture experiments that address these factors, using mixtures with high numbers of components, chemicals from diverse chemical groups, assays with different in vitro endpoints and different mixture designs and ratios. Firstly, the effects of mixtures composed of up to 17 estrogenic chemicals were examined using estrogenicity assays with reporter-gene (ERLUX and cell proliferation (ESCREEN endpoints. Two mixture designs were used: 1 a 'balanced' design with components present in proportion to a common effect concentration (e.g. an EC(10 and 2 a 'non-balanced' design with components in proportion to potential human tissue concentrations. Secondly, the individual and simultaneous ability of 16 potential modulator chemicals (each with minimal estrogenicity to influence the assay outcome produced by a reference mixture of estrogenic chemicals was examined. Test chemicals included plasticizers, phthalates, metals, PCBs, phytoestrogens, PAHs, heterocyclic amines, antioxidants, UV filters, musks, PBDEs and parabens. In all the scenarios tested, the CA concept provided a good prediction of mixture effects. Modulation studies revealed that chemicals possessing minimal estrogenicity themselves could reduce (negatively modulate the effect of a mixture of estrogenic chemicals. Whether the type of modulation we observed occurs in practice most likely depends on the chemical concentrations involved, and better information is required on likely human tissue concentrations of estrogens and of potential

Additive mixture effects of estrogenic chemicals in human cell-based assays can be influenced by inclusion of chemicals with differing effect profiles.

Science.gov (United States)

Evans, Richard Mark; Scholze, Martin; Kortenkamp, Andreas

2012-01-01

A growing body of experimental evidence indicates that the in vitro effects of mixtures of estrogenic chemicals can be well predicted from the estrogenicity of their components by the concentration addition (CA) concept. However, some studies have observed small deviations from CA. Factors affecting the presence or observation of deviations could include: the type of chemical tested; number of mixture components; mixture design; and assay choice. We designed mixture experiments that address these factors, using mixtures with high numbers of components, chemicals from diverse chemical groups, assays with different in vitro endpoints and different mixture designs and ratios. Firstly, the effects of mixtures composed of up to 17 estrogenic chemicals were examined using estrogenicity assays with reporter-gene (ERLUX) and cell proliferation (ESCREEN) endpoints. Two mixture designs were used: 1) a 'balanced' design with components present in proportion to a common effect concentration (e.g. an EC(10)) and 2) a 'non-balanced' design with components in proportion to potential human tissue concentrations. Secondly, the individual and simultaneous ability of 16 potential modulator chemicals (each with minimal estrogenicity) to influence the assay outcome produced by a reference mixture of estrogenic chemicals was examined. Test chemicals included plasticizers, phthalates, metals, PCBs, phytoestrogens, PAHs, heterocyclic amines, antioxidants, UV filters, musks, PBDEs and parabens. In all the scenarios tested, the CA concept provided a good prediction of mixture effects. Modulation studies revealed that chemicals possessing minimal estrogenicity themselves could reduce (negatively modulate) the effect of a mixture of estrogenic chemicals. Whether the type of modulation we observed occurs in practice most likely depends on the chemical concentrations involved, and better information is required on likely human tissue concentrations of estrogens and of potential modulators

Holographic interaction effects on transport in Dirac semimetals

NARCIS (Netherlands)

Jacobs, V.P.J.; Vandoren, S.; Stoof, H.T.C.

2014-01-01

Strongly interacting Dirac semimetals are investigated using a holographic model especially geared to compute the single-particle correlation function for this case, including both interaction effects and non-zero temperature. We calculate the (homogeneous) optical conductivity at zero chemical

Embedded Fragments from U.S. Military Personnel—Chemical Analysis and Potential Health Implications

Directory of Open Access Journals (Sweden)

José A. Centeno

2014-01-01

Full Text Available Background: The majority of modern war wounds are characterized by high-energy blast injuries containing a wide range of retained foreign materials of a metallic or composite nature. Health effects of retained fragments range from local or systemic toxicities to foreign body reactions or malignancies, and dependent on the chemical composition and corrosiveness of the fragments in vivo. Information obtained by chemical analysis of excised fragments can be used to guide clinical decisions regarding the need for fragment removal, to develop therapeutic interventions, and to better anticipate future medical problems from retained fragment related injuries. In response to this need, a new U.S Department of Defense (DoD directive has been issued requiring characterization of all removed fragments to provide a database of fragment types occurring in combat injuries. Objectives: The objective of this study is to determine the chemical composition of retained embedded fragments removed from injured military personnel, and to relate results to histological findings in tissue adjacent to fragment material. Methods: We describe an approach for the chemical analysis and characterization of retained fragments and adjacent tissues, and include case examples describing fragments containing depleted uranium (DU, tungsten (W, lead (Pb, and non-metal foreign bodies composed of natural and composite materials. Fragments obtained from four patients with penetrating blast wounds to the limbs were studied employing a wide range of chemical and microscopy techniques. Available adjacent tissues from three of the cases were histologically, microscopically, and chemically examined. The physical and compositional properties of the removed foreign material surfaces were examined with energy dispersive x-ray fluorescence spectrometry (EDXRF, scanning electron microscopy (SEM, laser ablation inductively-coupled plasma mass-spectrometry (LA-ICP-MS, and confocal laser Raman

Physical-chemical characterization of bovine bone ash for evaluating its potential agricultural use

Directory of Open Access Journals (Sweden)

Eduardo Pacca Luna Mattar

2014-03-01

Full Text Available The manufacturing of bovine bone ash is a low cost and easy production process which can be adopted for making good use of animal residues, in locations without infrastructure, such as the family production units. This study aimed at describing the manufacturing process of bone ash and characterizing the physical and chemical parameters of the resulting material for organic fertilization. The experiment was performed with three replications, being evaluated the bovine bone ash manufacturing process yield, as well as its density, water retention capacity, pH of the resulting material after burning and contents of total calcium, calcium soluble in water, total phosphorus and phosphorus soluble in citric acid and in ammonium citrate. The process resulted in an average yield of 24.4% and the bovine bone ash presented 33.07% of total calcium, 15.6% of total phosphorus, 10.4% of phosphorus soluble in citric acid, pH of 9.94, density of 0.89 g cm-3 and water retention capacity of 73.3%. The bovine bone ash showed promising characteristics, with potential for being used as source of phosphorus and calcium in the organic fertilization process.

Functionalized polypyrrole film: synthesis, characterization, and potential applications in chemical and biological sensors.

Science.gov (United States)

Dong, Hua; Cao, Xiaodong; Li, Chang Ming

2009-07-01

In this paper, we report the synthesis of a carboxyl-functionalized polypyrrole derivative, a poly(pyrrole-N-propanoic acid) (PPPA) film, by electrochemical polymerization, and the investigation of its basic properties via traditional characterization techniques such as confocal-Raman, FTIR, SEM, AFM, UV-vis, fluorescence microscopy, and contact-angle measurements. The experimental data show that the as-prepared PPPA film exhibits a hydrophilic nanoporous structure, abundant -COOH functional groups in the polymer backbone, and high fluorescent emission under laser excitation. On the basis of these unique properties, further experiments were conducted to demonstrate three potential applications of the PPPA film in chemical and biological sensors: a permeable and permselective membrane, a membrane with specific recognition sites for biomolecule immobilization, and a fluorescent conjugated polymer for amplification of fluorescence quenching. Specifically, the permeability and permselectivity of ion species through the PPPA film are detected by means of rotating-disk-electrode voltammetry; the specific recognition sites on the film surface are confirmed with protein immobilization, and the amplification of fluorescence quenching is measured by the addition of a quenching agent with fluorescence microscopy. The results are in good agreement with our expectations.

Assessment of potential biological activities and distributions of endocrine-disrupting chemicals in sediments of the west coast of South Korea.

Science.gov (United States)

Jeon, Seungyeon; Hong, Seongjin; Kwon, Bong-Oh; Park, Jinsoon; Song, Sung Joon; Giesy, John P; Khim, Jong Seong

2017-02-01

The west coast of Korea has experienced environmental deterioration for more than half a century. In the present study, we specifically aimed to: i) evaluate potential toxicities of contaminants in sediments that cause effects mediated through the aryl hydrocarbon receptor (AhR) and estrogen receptor (ER); ii) determine spatio-temporal distributions of polycyclic aromatic hydrocarbons (PAHs) and alkylphenols (APs); and iii) identify causes of greater potencies of samples. From 2010 to 2014, sediments were collected from 12 major estuarine and coastal regions along the west coast of South Korea. In vitro cell bioassays were performed to determine AhR- and ER-mediated potencies using H4IIE-luc and MVLN cells, respectively. Fifteen PAHs and six APs in sediments were identified by GC/MSD. Results of bioassays generally showed a low-to-moderate degree of contamination, however, greater AhR- and ER-mediated potencies were measured at some locations. Concentrations of PAHs and APs varied among locations, which indicated that sources were independently affected by the surrounding environment (e.g., industrial complex and cities). Results of bioassays were generally well correlated with concentrations of putative causative chemicals. Benzo[k]fluoranthene, dibenz[a,h]anthracene, and benzo[b]fluoranthene were the major AhR agonists, explaining approximately 30% of the bioassay-derived benzo[a]pyrene equivalent concentration (BaP-EQ). Unknown AhR and ER agonists and potential mixture effects remain in question. Overall, the present study provides baseline information on chemical contaminations and potential toxicity of sediments in a fairly wide geographical region of the west coast of South Korea. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cellular uptake and cytotoxic potential of respirable bentonite particles with different quartz contents and chemical modifications in human lung fibroblasts

Energy Technology Data Exchange (ETDEWEB)

Geh, Stefan; Rettenmeier, Albert W.; Dopp, Elke [University Hospital, Institute of Hygiene and Occupational Medicine, Essen (Germany); Yuecel, Raif [University Hospital, Institute of Cell Biology (Cancer Research), Essen (Germany); Duffin, Rodger [Institute of Environmental Health Research (IUF), Duesseldorf (Germany); University of Edinburgh, ELEGI COLT Lab, Scotland (United Kingdom); Albrecht, Catrin; Borm, Paul J.A. [Institute of Environmental Health Research (IUF), Duesseldorf (Germany); Armbruster, Lorenz [Verein fuer Technische Sicherheit und Umweltschutz e.V., Gotha (Germany); Raulf-Heimsoth, Monika; Bruening, Thomas [Research Institute for Occupational Medicine of the Institutions for Statutory Accident Insurance and Prevention (BGFA), Bochum (Germany); Hoffmann, Eik [University of Rostock, Institute of Biology, Department of Cell Biology and Biosystems Technology, Rostock (Germany)

2006-02-01

Considering the biological reactivity of pure quartz in lung cells, there is a strong interest to clarify the cellular effects of respirable siliceous dusts, like bentonites. In the present study, we investigated the cellular uptake and the cytotoxic potential of bentonite particles (Oe< 10 {mu}m) with an {alpha}-quartz content of up to 6% and different chemical modifications (activation: alkaline, acidic, organic) in human lung fibroblasts (IMR90). Additionally, the ability of the particles to induce apoptosis in IMR90-cells and the hemolytic activity was tested. All bentonite samples were tested for endotoxins with the in vitro-Pyrogen test and were found to be negative. Cellular uptake of particles by IMR90-cells was studied by transmission electron microscopy (TEM). Cytotoxicity was analyzed in IMR90-cells by determination of viable cells using flow cytometry and by measuring of the cell respiratory activity. Induced apoptotic cells were detected by AnnexinV/Propidiumiodide-staining and gel electrophoresis. Our results demonstrate that activated bentonite particles are better taken up by IMR90-cells than untreated (native) bentonite particles. Also, activated bentonite particles with a quartz content of 5-6% were more cytotoxic than untreated bentonites or bentonites with a quartz content lower than 4%. The bentonite samples induced necrotic as well as apoptotic cell death. In general, bentonites showed a high membrane-damaging potential shown as hemolytic activity in human erythrocytes. We conclude that cellular effects of bentonite particles in human lung cells are enhanced after chemical treatment of the particles. The cytotoxic potential of the different bentonites is primarily characterized by a strong lysis of the cell membrane. (orig.)

Evaluation of liquid-phase oxidation for the destruction of potential chemical terrorism agents

Energy Technology Data Exchange (ETDEWEB)

Thouin, G.; Harrison, S.; Li, K.; Kuang, W.; Volchek, K.; Fingas, M. [Environment Canada, Ottawa, ON (Canada). Emergencies Science Div; Potaraju, S.; Velicogna, D.; Obenauf, A. [SAIC Canada, Ottawa, ON (Canada)

2005-07-01

Although pesticides are designed to protect crops and livestock against insects, fungi or nuisance plants, the toxicity of these compounds is not limited to target species. Organophosphorus, organochlorine and carbamate pesticides all target the nervous systems of insects. This paper assessed the effectiveness of an enhanced oxidation process using peroxycarboxylic acids for the liquid-phase destruction of toxic industrial chemicals, considered to be potential agents of chemical terrorism. Peroxyacetic acid (PAA) and peroxypropionic acid (PPA) were tested as decontamination agents on organophosphorus, organochlorine and carbamate pesticides. The processes were reviewed in relation to the terms of percent agent destruction over time, with a target of 90 per cent destruction within 30 minutes. Effectiveness was also assessed on the accumulation of toxic by-products. A background of the pesticides was presented, as well as details of their various applications. The molecular structures of the compounds were also provided. Oxidation extraction procedures, materials and methods were also presented, as well as analytical techniques, method detection limits and issues concerning reproducibility. The pH profile of PAA and PPA as a function of the concentration in acid was studied in order to determine which was more likely to be corrosive. It was concluded that peroxycarboxylic acids are effective decontamination agents for organophosphorous and carbamate pesticides. PAA and PPA are equally effective in degrading the examined pesticides, however, greater amounts of toxic by-products are found with PPA than with PAA. Neither PAA nor PPA were able to degrade lindane, and more lindane was found in the treated samples than in the controls. It was noted that time profiles for lower concentrations of peroxycarboxylic acids and pH profiles are currently being developed. It was suggested that further research in this area included degradation experiments on various types of

REDOX DISRUPTING POTENTIAL OF TOXCAST CHEMICALS RANKED BY ACTIVITY IN MOUSE EMBRYONIC STEM CELLS

Science.gov (United States)

To gain insight regarding the adverse outcome pathways leading to developmental toxicity following exposure to chemicals, we evaluated ToxCast™ Phase I chemicals in an adherent mouse embryonic stem cell (mESC) assay and identified a redox sensitive pathway that correlated with al...

Relationship between chemical composition and oxidative potential of secondary organic aerosol from polycyclic aromatic hydrocarbons

Science.gov (United States)

Wang, Shunyao; Ye, Jianhuai; Soong, Ronald; Wu, Bing; Yu, Legeng; Simpson, André J.; Chan, Arthur W. H.

2018-03-01

Owing to the complex nature and dynamic behaviors of secondary organic aerosol (SOA), its ability to cause oxidative stress (known as oxidative potential, or OP) and adverse health outcomes remains poorly understood. In this work, we probed the linkages between the chemical composition of SOA and its OP, and investigated impacts from various SOA evolution pathways, including atmospheric oligomerization, heterogeneous oxidation, and mixing with metal. SOA formed from photooxidation of the two most common polycyclic aromatic hydrocarbons (naphthalene and phenanthrene) were studied as model systems. OP was evaluated using the dithiothreitol (DTT) assay. The oligomer-rich fraction separated by liquid chromatography dominates DTT activity in both SOA systems (52 ± 10 % for naphthalene SOA (NSOA), and 56 ± 5 % for phenanthrene SOA (PSOA)). Heterogeneous ozonolysis of NSOA was found to enhance its OP, which is consistent with the trend observed in selected individual oxidation products. DTT activities from redox-active organic compounds and metals were found to be not additive. When mixing with highly redox-active metal (Cu), OP of the mixture decreased significantly for 1,2-naphthoquinone (42 ± 7 %), 2,3-dihydroxynaphthalene (35 ± 1 %), NSOA (50 ± 6 %), and PSOA (43 ± 4 %). Evidence from proton nuclear magnetic resonance (1H NMR) spectroscopy illustrates that such OP reduction upon mixing can be ascribed to metal-organic binding interactions. Our results highlight the role of aerosol chemical composition under atmospheric aging processes in determining the OP of SOA, which is needed for more accurate and explicit prediction of the toxicological impacts from particulate matter.

Chemical Absorption Materials

DEFF Research Database (Denmark)

Thomsen, Kaj

2011-01-01

Chemical absorption materials that potentially can be used for post combustion carbon dioxide capture are discussed. They fall into five groups, alkanolamines, alkali carbonates, ammonia, amino acid salts, and ionic liquids. The chemistry of the materials is discussed and advantages and drawbacks...

Chemical Safety Research Advances in Support of Lautenberg Act

Science.gov (United States)

EPA researchers are developing new ways to identify which chemicals to prioritize for further testing, to provide better access to information about chemicals, and to understand what potential risks chemicals may pose to humans and the environment.

Towards finite density QCD with Taylor expansions

International Nuclear Information System (INIS)

Karsch, F.; Schaefer, B.-J.; Wagner, M.; Wambach, J.

2011-01-01

Convergence properties of Taylor expansions of observables, which are also used in lattice QCD calculations at non-zero chemical potential, are analyzed in an effective N f =2+1 flavor Polyakov quark-meson model. A recently developed algorithmic technique allows the calculation of higher-order Taylor expansion coefficients in functional approaches. This novel technique is for the first time applied to an effective N f =2+1 flavor Polyakov quark-meson model and the findings are compared with the full model solution at finite densities. The results are used to discuss prospects for locating the QCD phase boundary and a possible critical endpoint in the phase diagram.

The impact of particle production on gravitational baryogenesis

Energy Technology Data Exchange (ETDEWEB)

Lima, J.A.S., E-mail: jas.lima@iag.usp.br [Departamento de Astronomia, Universidade de São Paulo, Rua do Matão 1226, 05508-900, São Paulo (Brazil); Singleton, D., E-mail: dougs@csufresno.edu [Department of Physics, California State University Fresno, Fresno, CA 93740-8031 (United States); ICTP South American Institute for Fundamental Research, UNESP – Univ. Estadual Paulista, Rua Dr. Bento T. Ferraz 271, 01140-070, São Paulo, SP (Brazil); Institute of Experimental and Theoretical Physics Al-Farabi KazNU, Almaty, 050040 (Kazakhstan)

2016-11-10

Baryogenesis driven by curvature effects is investigated by taking into account gravitationally induced particle production in the very early Universe. In our scenario, the baryon asymmetry is generated dynamically during an inflationary epoch powered by ultra-relativistic particles. The adiabatic particle production rate provides both the needed negative pressure to accelerate the radiation dominated Universe and a non-zero chemical potential which distinguishes baryons and anti-baryons thereby producing a baryon asymmetry in agreement with the observed value. Reciprocally, the present day asymmetry may be used to determine the inflationary scale at early times. Successful gravitational baryogenesis is dynamically generated for many different choices of the relevant model parameters.

Magneto-optical and magnetic properties in a Co/Pd multilayered thin film

Energy Technology Data Exchange (ETDEWEB)

Nwokoye, Chidubem A. [Institute for Magnetics Research, Department of Electrical and Computer Engineering, The George Washington University, DC 20052 (United States); Naval Air Systems Command, Avionics, Sensors and E*Warfare Department, Patuxent River, MD 20670 (United States); Bennett, Lawrence H., E-mail: lbennett@gwu.edu [Institute for Magnetics Research, Department of Electrical and Computer Engineering, The George Washington University, DC 20052 (United States); Della Torre, Edward, E-mail: edt@gwu.edu [Institute for Magnetics Research, Department of Electrical and Computer Engineering, The George Washington University, DC 20052 (United States); Ghahremani, Mohammadreza [Institute for Magnetics Research, Department of Electrical and Computer Engineering, The George Washington University, DC 20052 (United States); Narducci, Frank A. [Naval Air Systems Command, Avionics, Sensors and E*Warfare Department, Patuxent River, MD 20670 (United States)

2017-01-01

The paper describes investigation of ferromagnetism at low temperatures. We explored the magneto-optical properties, influenced by photon–magnon interactions, of a ferromagnetic Co/Pd multilayered thin film below and above the magnon Bose–Einstein Condensation (BEC) temperature. Analyses of SQUID and MOKE low temperature experimental results reveal a noticeable phase transition in both magnetic and magneto-optical properties of the material at the BEC temperature. - Highlights: • The results show the effect of a non-zero chemical potential on the magnetization. • The MOKE and SQUID results show a phase transition point at the same temperature. • Magnon BEC is a major influence of the observed phase transition temperature.

Dispersion forces in micromechanics: Casimir and Casimir-Polder forces affected by geometry and non-zero temperature

Energy Technology Data Exchange (ETDEWEB)

Ellingsen, Simen Andreas Aadnoey

2011-01-15

The present thesis focuses on several topics within three separate but related branches of the overall field of dispersion forces. The three branches are: temperature corrections to the Casimir force between real materials (Part 1), explicit calculation of Casimir energy in wedge geometries (Part 2), and Casimir-Polder forces on particles out of thermal equilibrium (Part 3). Part 1 deals primarily with analysis of a previously purported thermodynamic inconsistency in the Casimir-Lifshitz free energy of the interaction of two plane mirrors - violation of the third law of thermodynamics - when the latter's dielectric response is described with dissipative models. It is shown analytically and numerically that the Casimir entropy of the interaction between two metallic mirrors described by the Drude model does tend to zero at zero temperature, provided electronic relaxation does not vanish. The leading order terms at low temperature are found. A similar calculation is carried out for the interaction of semiconductors with small but non-zero DC conductivity. In a generalisation, it is shown that a violation of the third law can only occur for permittivities whose low-frequency behaviour is temperature dependent near zero temperature. A calculation using path integral methods shows that the low temperature behaviour of the interaction of fluctuating Foucault currents in two mirrors of Drude metal is identical to that of the full Casimir-Lifshitz free energy, reasserting a previous finding by Intravaia and Henkel that such fluctuating bulk currents are the physical reason for the anomalous entropy behaviour. In a related effort, an analysis of the frequency dependence of the Casimir force by Ford is generalised to imperfectly reflecting mirrors. A paradox is pointed out, in that the effects of a perturbation of the reflecting properties of the mirrors in a finite frequency window can be calculated in two ways giving different results. It is concluded that optimistic

Analysis of forward and inverse problems in chemical dynamics and spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Rabitz, H. [Princeton Univ., NJ (United States)

1993-12-01

The overall scope of this research concerns the development and application of forward and inverse analysis tools for problems in chemical dynamics and chemical kinetics. The chemical dynamics work is specifically associated with relating features in potential surfaces and resultant dynamical behavior. The analogous inverse research aims to provide stable algorithms for extracting potential surfaces from laboratory data. In the case of chemical kinetics, the focus is on the development of systematic means to reduce the complexity of chemical kinetic models. Recent progress in these directions is summarized below.

HANFORD CHEMICAL VAPORS WORKER CONCERNS and EXPOSURE EVALUATION

International Nuclear Information System (INIS)

ANDERSON, T.J.

2006-01-01

Chemical vapor emissions from underground hazardous waste storage tanks on the Hanford site in eastern Washington State are a potential concern because workers enter the tank farms on a regular basis for waste retrievals, equipment maintenance, and surveillance. Tank farm contractors are in the process of retrieving all remaining waste from aging single-shell tanks, some of which date to World War II, and transferring it to newer double-shell tanks. During the waste retrieval process, tank farm workers are potentially exposed to fugitive chemical vapors that can escape from tank headspaces and other emission points. The tanks are known to hold more than 1,500 different species of chemicals, in addition to radionuclides. Exposure assessments have fully characterized the hazards from chemical vapors in half of the tank farms. Extensive sampling and analysis has been done to characterize the chemical properties of hazardous waste and to evaluate potential health hazards of vapors at the ground surface, where workers perform maintenance and waste transfer activities. Worker concerns. risk communication, and exposure assessment are discussed, including evaluation of the potential hazards of complex mixtures of chemical vapors. Concentrations of vapors above occupational exposure limits-(OEL) were detected only at exhaust stacks and passive breather filter outlets. Beyond five feet from the sources, vapors disperse rapidly. No vapors have been measured above 50% of their OELs more than five feet from the source. Vapor controls are focused on limited hazard zones around sources. Further evaluations of vapors include analysis of routes of exposure and thorough analysis of nuisance odors

Interactive Chemical Safety for Sustainablity Toxicity Forecaster Dashboard

Science.gov (United States)

EPA researchers have been using advances in computational toxicology to address lack of data on the thousands of chemicals. EPA released chemical data on 1,800 chemicals. The 1,800 chemicals were screened in more than 800 rapid, automated tests (called high-throughput screening assays) to determine potential human health effects. The data is available through the interactive Chemical Safety for Sustainability Dashboards (iCSS dashboard) and the complete data sets are also available for download.

Chemically treated carbon black waste and its potential applications

Energy Technology Data Exchange (ETDEWEB)

Dong, Pengwei; Maneerung, Thawatchai; Ng, Wei Cheng; Zhen, Xu [NUS Environmental Research Institute, National University of Singapore, 1 Create Way, Create Tower #15-02, 138602 (Singapore); Dai, Yanjun [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Tong, Yen Wah [NUS Environmental Research Institute, National University of Singapore, 1 Create Way, Create Tower #15-02, 138602 (Singapore); Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585 (Singapore); Ting, Yen-Peng [Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585 (Singapore); Koh, Shin Nuo [Sembcorp Industries Ltd., 30 Hill Street #05-04, 179360 (Singapore); Wang, Chi-Hwa, E-mail: chewch@nus.edu.sg [Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585 (Singapore); Neoh, Koon Gee, E-mail: chenkg@nus.edu.sg [Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585 (Singapore)

2017-01-05

Highlights: • Hazardous impurities separated from carbon black waste with little damage to solid. • Heavy metals were effectively removed from carbon black waste by HNO{sub 3} leaching. • Treated carbon black waste has high adsorption capacity (∼356.4 mg{sub dye}/g). • Carbon black waste was also found to show high electrical conductivity (10 S/cm). - Abstract: In this work, carbon black waste – a hazardous solid residue generated from gasification of crude oil bottom in refineries – was successfully used for making an absorbent material. However, since the carbon black waste also contains significant amounts of heavy metals (especially nickel and vanadium), chemical leaching was first used to remove these hazardous impurities from the carbon black waste. Acid leaching with nitric acid was found to be a very effective method for removal of both nickel and vanadium from the carbon black waste (i.e. up to 95% nickel and 98% vanadium were removed via treatment with 2 M nitric acid for 1 h at 20 °C), whereas alkali leaching by using NaOH under the same condition was not effective for removal of nickel (less than 10% nickel was removed). Human lung cells (MRC-5) were then used to investigate the toxicity of the carbon black waste before and after leaching. Cell viability analysis showed that the leachate from the original carbon black waste has very high toxicity, whereas the leachate from the treated samples has no significant toxicity. Finally, the efficacy of the carbon black waste treated with HNO{sub 3} as an absorbent for dye removal was investigated. This treated carbon black waste has high adsorption capacity (∼361.2 mg {sub dye}/g {sub carbonblack}), which can be attributed to its high specific surface area (∼559 m{sup 2}/g). The treated carbon black waste with its high adsorption capacity and lack of cytotoxicity is a promising adsorbent material. Moreover, the carbon black waste was found to show high electrical conductivity (ca. 10 S

Effects of K3[Fe(CN)6] slurry's pH value and applied potential on tungsten removal rate for chemical-mechanical planarization application

Energy Technology Data Exchange (ETDEWEB)

Akonko, S.B.; Li, D.Y.; Ziomek-Moroz, M.; Hawk, J.A.; Miller, A.; Cadien, K.

2005-07-01

Chemical-mechanical planarization (CMP) is an important process for building multilevel interconnections for electronic devices. Directly planarizing tungsten, which is used as via or contact in microelectronic circuits, by wear is a difficult process because of its high hardness. Therefore, an effective approach has been developed to facilitate planarizing tungsten surface by removing a continuously growing passive film on tungsten when exposed to a low-pH potassium ferricyanide slurry. Since the passive film is softer than tungsten, this chemical mechanical planarization process is effective. In this work, in order to determine effects of corrosion and wear on tungsten removal rate, attempts were made to investigate corrosion, wear, and corrosive wear behavior of tungsten in K3[Fe(CN)6] slurries. Electrochemical and tribological experiments were carried out for different slurry pH values and potentials using a rotating pin-on-disc tribometer. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize surface films formed at the different pH levels and potentials. It was demonstrated that the tungsten removal rate increased with increasing slurry pH and potential. Mechanisms involved are discussed.

Carbon emissions reduction potential in the US chemicals and pulp and paper industries by applying CHP technologies

International Nuclear Information System (INIS)