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Sample records for isospin chemical potentials

  1. Dual condensates at finite isospin chemical potential

    NASA Astrophysics Data System (ADS)

    Zhang, Zhao; Miao, Qing

    2016-02-01

    The dual observables as order parameters for center symmetry are tested at finite isospin chemical potential μI in a Polyakov-loop enhanced chiral model of QCD with physical quark masses. As a counterpart of the dressed Polyakov-loop, the first Fourier moment of pion condensate is introduced for μI >mπ / 2 under the temporal twisted boundary conditions for quarks. We demonstrate that this dual condensate exhibits the similar temperature dependence as the conventional Polyakov-loop. We confirm that its rapid increase with T is driven by the evaporating of pion condensation. On the other hand, the dressed Polyakov-loop shows abnormal thermal behavior, which even decreases with T at low temperatures due to the influence of pion condensate. We also find that the dressed Polyakov-loop always rises most steeply at the chiral transition temperature, which is consistent with the previous results in Nambu-Jona-Lasinio (NJL) model and its variants without considering the center symmetry. Since both quantities are strongly affected by the chiral symmetry and pion condensation, we conclude that it is difficult to clarify the deconfinement transition from the dual condensates in this situation within this model.

  2. Deconfinement transition at high isospin chemical potential and low temperature

    NASA Astrophysics Data System (ADS)

    Cohen, Thomas D.; Sen, Srimoyee

    2015-10-01

    We consider QCD with two degenerate flavors of light quarks (up and down) at asymptotically high isospin (μI) with zero baryon chemical potential (μB) and calculate for the first time a quantitative expression for the critical temperature of the deconfinement transition in this regime. At high isospin chemical potential and sufficiently low temperatures this theory becomes equivalent to a pure Yang-Mills theory and accordingly has a first order deconfinement phase transition. Although this was conjectured in a seminal paper by Son and Stephanov in the year 2001, the critical temperature of this deconfinement phase transition was not computed. This paper computes the energy scale associated with this transition as a function of the chemical potential μI by relating the parameters of the equivalent Yang-Mills theory to those of the underlying theory. We also relate the equation of state in one strongly interacting regime of QCD namely at finite isospin density to that in pure Yang-Mills, with the latter being amenable to straightforward numerical calculation. Our results for the critical temperature of deconfinement transition can be compared with future lattice calculations.

  3. QCD Phase Diagram at Finite Baryon and Isospin Chemical Potentials

    SciTech Connect

    Sasaki, T.; Sakai, Y.; Yahiro, M.; Kouno, H.

    2011-10-21

    The phase structure of two-flavor QCD is explored for finite temperature T and finite baryon- and isospin-chemical potentials, {mu}{sub B} and {mu}{sub I}, by using the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model. The PNJL model with the scalar-type eight-quark interaction can reproduce lattice QCD data in the {mu}{sub I}-T plane at {mu}{sub B} = 0. In the {mu}{sub I}-{mu}{sub B}-T space, the critical endpoint of the chiral phase transition in the {mu}{sub B}-T plane at {mu}{sub I} = 0 moves to the tricritical point of the pion-superfluidity phase transition in the {mu}{sub I}-T plane at {mu}{sub B} = 0 as {mu}{sub I} increases.

  4. QCD phase diagram at finite baryon and isospin chemical potentials

    SciTech Connect

    Sasaki, Takahiro; Sakai, Yuji; Yahiro, Masanobu; Kouno, Hiroaki

    2010-12-01

    The phase structure of two-flavor QCD is explored for thermal systems with finite baryon- and isospin-chemical potentials, {mu}{sub B} and {mu}{sub iso}, by using the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model. The PNJL model with the scalar-type eight-quark interaction can reproduce lattice QCD data at not only {mu}{sub iso}={mu}{sub B}=0, but also {mu}{sub iso}>0 and {mu}{sub B}=0. In the {mu}{sub iso}-{mu}{sub B}-T space, where T is temperature, the critical endpoint of the chiral phase transition in the {mu}{sub B}-T plane at {mu}{sub iso}=0 moves to the tricritical point of the pion-superfluidity phase transition in the {mu}{sub iso}-T plane at {mu}{sub B}=0 as {mu}{sub iso} increases. The thermodynamics at small T is controlled by {radical}({sigma}{sup 2}+{pi}{sup 2}) defined by the chiral and pion condensates, {sigma} and {pi}.

  5. Skyrmion semiclassical quantization in the presence of an isospin chemical potential

    SciTech Connect

    Cohen, Thomas D.; Ponciano, Juan A.; Scoccola, Norberto N.

    2008-08-01

    The semiclassical description of Skyrmions at small isospin chemical potential {mu}{sub I} is carefully analyzed. We show that when the calculation of the energy of a nucleon is performed using the straightforward generalization of the vacuum sector techniques ({mu}{sub I}=0), together with the 'natural' assumption {mu}{sub I}=O(N{sub c}{sup 0}), the proton and neutron masses are nonlinear in {mu}{sub I} in the regime |{mu}{sub I}|isospin, I{approx}N{sub c}.

  6. Three-loop hard-thermal-loop perturbation theory thermodynamics at finite temperature and finite baryonic and isospin chemical potential

    NASA Astrophysics Data System (ADS)

    Andersen, Jens O.; Haque, Najmul; Mustafa, Munshi G.; Strickland, Michael

    2016-03-01

    In a previous paper [N. Haque et al., J. High Energy Phys. 05 (2014) 27], we calculated the three-loop thermodynamic potential of QCD at finite temperature T and quark chemical potentials μq using the hard-thermal-loop perturbation theory (HTLpt) reorganization of finite temperature and density QCD. The result allows us to study the thermodynamics of QCD at finite temperature and finite baryon, strangeness, and isospin chemical potentials μB, μS, and μI. We calculate the pressure at nonzero μB and μI with μS=0 , and the energy density, the entropy density, the trace anomaly, and the speed of sound at nonzero μI with μB=μS=0 . The second- and fourth-order isospin susceptibilities are calculated at μB=μS=μI=0 . Our results can be directly compared to lattice QCD without Taylor expansions around μq=0 since QCD has no sign problem at μB=μS=0 and finite isospin chemical potential μI.

  7. Enhancement of chiral symmetry breaking from the pion condensation at finite isospin chemical potential in a holographic QCD model

    NASA Astrophysics Data System (ADS)

    Nishihara, Hiroki; Harada, Masayasu

    2014-04-01

    We study the pion condensation at the finite isospin chemical potential using a holographic QCD model. By solving the equations of motion for the pion fields together with those for the isosinglet scalar and iso-triplet vector meson fields, we show that the phase transition from the normal phase to the pion condensation phase is second order with the mean-field exponent, and that the critical value of the isospin chemical potential μI is equal to the pion mass, consistently with the result obtained by the chiral effective Lagrangian at O(p2). For a higher chemical potential, we find a deviation, which can be understood as a higher order effect in the chiral effective Lagrangian. We investigate the μI dependence of the chiral condensate defined by σ ˜≡√⟨σ⟩2+⟨πa⟩2 . We find that σ ˜ is almost constant in the small μI region, while it grows with μI in the large μI region. This implies that the strength of the chiral symmetry breaking is not changed for small μI: The isospin chemical potential plays a role to rotate the "vacuum angle" of the chiral circle tan-1√⟨πa⟩2/⟨σ⟩2 with keeping the "radius" σ ˜ unchanged for small μI. For the large μI region, on the other hand, the chiral symmetry breaking is enhanced by the existence of μI.

  8. Equation of State for Isospin Asymmetric Nuclear Matter Using Lane Potential

    NASA Astrophysics Data System (ADS)

    Basu, D. N.; Chowdhury, P. Roy; Samanta, C.

    2006-10-01

    A mean field calculation for obtaining the equation of state (EOS) for symmetric nuclear matter from a density dependent M3Y interaction supplemented by a zero-range potential is described. The energy per nucleon is minimized to obtain the ground state of symmetric nuclear matter. The saturation energy per nucleon used for nuclear matter calculations is determined from the co-efficient of the volume term of Bethe--Weizsäcker mass formula which is evaluated by fitting the recent experimental and estimated atomic mass excesses from Audi--Wapstra--Thibault atomic mass table by minimizing the mean square deviation. The constants of density dependence of the effective interaction are obtained by reproducing the saturation energy per nucleon and the saturation density of spin and isospin symmetric cold infinite nuclear matter. The EOS of symmetric nuclear matter, thus obtained, provide reasonably good estimate of nuclear incompressibility. Once the constants of density dependence are determined, EOS for asymmetric nuclear matter is calculated by adding to the isoscalar part, the isovector component of the M3Y interaction that do not contribute to the EOS of symmetric nuclear matter. These EOS are then used to calculate the pressure, the energy density and the velocity of sound in symmetric as well as isospin asymmetric nuclear matter.

  9. Isospin diffusion in thermal AdS/CFT correspondence with flavor

    SciTech Connect

    Erdmenger, Johanna; Kaminski, Matthias; Rust, Felix

    2007-08-15

    We study the gauge/gravity dual of a finite temperature field theory at finite isospin chemical potential by considering a probe of two coincident D7-branes embedded in the AdS-Schwarzschild black hole background. The isospin chemical potential is obtained by giving a vacuum expectation value to the time component of the non-Abelian gauge field on the brane. The fluctuations of the non-Abelian gauge field on the brane are dual to the SU(2) flavor current in the field theory. For the embedding corresponding to vanishing quark mass, we calculate all Green functions corresponding to the components of the flavor current correlator. We discuss the physical properties of these Green functions, which go beyond linear response theory. In particular, we show that the isospin chemical potential leads to a frequency-dependent isospin diffusion coefficient.

  10. Global analysis of isospin dependent microscopic nucleon-nucleus optical potentials in a Dirac-Brueckner-Hartree-Fock approach

    NASA Astrophysics Data System (ADS)

    Xu, Ruirui; Ma, Zhongyu; Zhang, Yue; Tian, Yuan; van Dalen, E. N. E.; Müther, H.

    2016-09-01

    Background: For the study of exotic nuclei it is important to have an optical model potential that is reliable not only for stable nuclei but can also be extrapolated to nuclear systems with exotic numbers of protons and neutrons. An efficient way to obtain such a potential is to develop a microscopic optical potential (MOP) based on a fundamental theory with a minimal number of free parameters, which are adjusted to describe stable nuclei all over the nuclide chart. Purpose: The choice adopted in the present work is to develop the MOP within a relativistic scheme which provides a natural and consistent relation between the spin-orbit part and the central part of the potential. The Dirac-Brueckner-Hartree-Fock (DBHF) approach provides such a microscopic relativistic scheme, which is based on a realistic nucleon-nucleon interaction and reproduces the saturation properties of symmetric nuclear matter without any adjustable parameter. Its solution using the projection technique within the subtracted T -matrix representation provides a reliable extension to asymmetric nuclear matter, which is important to describe the features of isospin asymmetric nuclei. The present work performs a global analysis of the isospin dependent nucleon-nucleus MOP based on the DBHF calculation in symmetric and asymmetric nuclear matter. Methods: The DBHF approach is used to evaluate the relativistic structure of the nucleon self-energies in nuclear matter at various densities and asymmetries. The Schrödinger equivalent potentials of finite nuclei are derived from these Dirac components by a local density approximation (LDA). The density distributions of finite nuclei are taken from the Hartree-Fock-Bogoliubov approach with Gogny D1S force. An improved LDA approach (ILDA) is employed to get a better prediction of the scattering observables. A χ2 assessment system based on the global simulated annealing algorithm is developed to optimize the very few free components in this study. Results

  11. The elusive chemical potential

    NASA Astrophysics Data System (ADS)

    Baierlein, Ralph

    2001-04-01

    This paper offers some qualitative understanding of the chemical potential, a topic that students invariably find difficult. Three "meanings" for the chemical potential are stated and then supported by analytical development. Two substantial applications—depression of the melting point and batteries—illustrate the chemical potential in action. The origin of the term "chemical potential" has its surprises, and a sketch of the history concludes the paper.

  12. Thermodynamics of (2+1)-flavor strongly interacting matter at nonzero isospin

    NASA Astrophysics Data System (ADS)

    Stiele, Rainer; Fraga, Eduardo S.; Schaffner-Bielich, Jürgen

    2014-02-01

    We investigate the phase structure of strongly interacting matter at non-vanishing isospin before the onset of pion condensation in the framework of the unquenched Polyakov-Quark-Meson model with 2+1 quark flavors. We show results for the order parameters and all relevant thermodynamic quantities. In particular, we obtain a moderate change of the pressure with isospin at vanishing baryon chemical potential, whereas the chiral condensate decreases more appreciably. We compare the effective model to recent lattice data for the decrease of the pseudo-critical temperature with the isospin chemical potential. We also demonstrate the major role played by the value of the pion mass in the curvature of the transition line, and the need for lattice results with a physical pion mass. Limitations of the model at nonzero chemical potential are also discussed.

  13. Isospin breaking from diquark clustering

    NASA Astrophysics Data System (ADS)

    Gibbs, W. R.; Dedonder, Jean-Pierre

    2017-09-01

    Background: Although SU(2) isospin symmetry is generally assumed in the basic theory of the strong interaction, a number of significant violations have been observed in scattering and bound states of nucleons. Many of these violations can be attributed to the electromagnetic interaction but the question of how much of the violation is due to it remains open. Purpose: To establish the connection between diquark clustering in the two-nucleon system and isospin breaking from the Coulomb interaction between the members of diquark pairs. Method: A schematic model based on clustering of quarks in the interior of the confinement region of the two-nucleon system is introduced and evaluated. In this model the Coulomb interaction is the source of all isospin breaking. It draws on a picture of the quark density based on the diquark-quark model of hadron structure which has been investigated by a number of groups. Results: The model produces three isospin breaking potentials connecting the unbroken value of the low-energy scattering amplitude to those of the p p , n n , and n p singlet channels. A simple test of the potentials in the three-nucleon energy difference problem yields results in agreement with the known binding energy difference. Conclusion: The illustrative model suggests that the breaking seen in the low-energy nucleon-nucleon (NN) interaction may be understood in terms of the Coulomb force between members of diquark clusters. It allows the prediction of the charge symmetry breaking interaction and the n n scattering length from the well measured n p singlet scattering length. Values of the n n scattering length around -18 fm are favored. Since the model is based on the quark picture, it can be easily extended, in the SU(3) limit, to calculate isospin breaking in the strange sector in the corresponding channels. A natural consequence of isospin breaking from diquark clustering is that the breaking in the strange sector, as measured by the separation energy

  14. Ginocchio model with isospin

    NASA Astrophysics Data System (ADS)

    Okai, Tadashi; Otsuka, Takaharu; Arima, Akito

    1992-02-01

    We study the sp(8) subgroup of the isospin-invariant Ginnocchio model. The allowed quantum numbers are determined in terms of Young's diagrams. Using this result, we discuss the excitation energy of a model hamiltonian.

  15. Isospinning baby Skyrmion solutions

    NASA Astrophysics Data System (ADS)

    Battye, Richard A.; Haberichter, Mareike

    2013-12-01

    We perform full two-dimensional (2D) numerical relaxations of isospinning soliton solutions in the baby Skyrme model in which the global O(3) symmetry is broken by the 2D analogue of the pion mass term in the Skyrme model. In our calculations we explicitly allow the isospinning solitons to deform and to break the symmetries of the static configurations. We find that stable isospinning baby Skyrme solutions can be constructed numerically for all angular frequencies ω≤min⁡(μ,1), where μ is the mass parameter of the model. Stable, rotationally symmetric baby Skyrmion solutions for higher angular velocities are simply an artefact of the hedgehog approximation. Isospinning multisoliton solutions of topological charge B turn out to be unstable to break up into their B charge-1 constituents at some critical breakup frequency value. Furthermore, we find that for μ sufficiently large the rotational symmetry of charge-2 baby Skyrmions becomes broken at a critical angular frequency ω.

  16. Integrability and chemical potential in the (3 + 1)-dimensional Skyrme model

    NASA Astrophysics Data System (ADS)

    Alvarez, P. D.; Canfora, F.; Dimakis, N.; Paliathanasis, A.

    2017-10-01

    Using a remarkable mapping from the original (3 + 1)dimensional Skyrme model to the Sine-Gordon model, we construct the first analytic examples of Skyrmions as well as of Skyrmions-anti-Skyrmions bound states within a finite box in 3 + 1 dimensional flat space-time. An analytic upper bound on the number of these Skyrmions-anti-Skyrmions bound states is derived. We compute the critical isospin chemical potential beyond which these Skyrmions cease to exist. With these tools, we also construct topologically protected time-crystals: time-periodic configurations whose time-dependence is protected by their non-trivial winding number. These are striking realizations of the ideas of Shapere and Wilczek. The critical isospin chemical potential for these time-crystals is determined.

  17. Isospin effect of Coulomb interaction on the dissipation and fragmentation in intermediate energy heavy ion collisions

    SciTech Connect

    Liu Jianye; Guo Wenjun; Gao Yuanyi; Xing Yongzhong; Li Xiguo

    2004-09-01

    We investigate separately the isospin effects of Coulomb interaction and symmetry potential on the dissipation and fragmentation in the intermediate energy heavy ion collisions by using isospin-dependent quantum molecular dynamics model. The calculated results show that the Coulomb interaction induces the reductions of both isospin fractionation ratio and nuclear stopping (momentum dissipation). However, the Coulomb interaction not only does not change obviously the strong isospin effect of the symmetry potential on the isospin fractionation ratio but also does not change obviously that of in-medium two-body collision on the nuclear stopping. On the contrary, the symmetry potential induces the enhancement of the isospin fractionation ratio but it is insensitive to the nuclear stopping. Finally, the competition between the Coulomb interaction and symmetry potential induces the reductions of both isospin fractionation ratio and nuclear stopping for two forms of symmetry potentials in this paper.

  18. Stressed Cooper pairing in QCD at high isospin density: effective Lagrangian and random matrix theory

    NASA Astrophysics Data System (ADS)

    Kanazawa, Takuya; Wettig, Tilo

    2014-10-01

    We generalize QCD at asymptotically large isospin chemical potential to an arbitrary even number of flavors. We also allow for small quark chemical potentials, which stress the coincident Fermi surfaces of the paired quarks and lead to a sign problem in Monte Carlo simulations. We derive the corresponding low-energy effective theory in both p- and ɛ-expansion and quantify the severity of the sign problem. We construct the random matrix theory describing our physical situation and show that it can be mapped to a known random matrix theory at low baryon density so that new insights can be gained without additional calculations. In particular, we explain the Silver Blaze phenomenon at high isospin density. We also introduce stressed singular values of the Dirac operator and relate them to the pionic condensate. Finally we comment on extensions of our work to two-color QCD.

  19. Functional integrals for QCD at nonzero chemical potential and zero density.

    PubMed

    Cohen, Thomas D

    2003-11-28

    In a Euclidean space functional integral treatment of the free energy of QCD, a chemical potential enters only through the functional determinant of the Dirac operator which for any flavor is /D+m-mu(f)gamma(0) (where mu(f) is the chemical potential for the given flavor). Any nonzero mu alters all of the eigenvalues of the Dirac operator relative to the mu=0 value, leading to a naive expectation that the determinant is altered and which thereby alters the free energy. Phenomenologically, this does not occur at T=0 for sufficiently small mu, in contradiction to this naive expectation. The problem of how to understand this phenomenological behavior in terms of functional integrals is solved for the case of an isospin chemical through the study of the spectrum of the operator gamma(0)(/D+m). The case of the baryon chemical potential is briefly discussed.

  20. Chemical corrosion potential in boilers

    SciTech Connect

    Bairr, D.L.; McDonough, C.J.

    1998-12-31

    Misuse or abuse of chelants has long been recognized as a potential corrosion problem in boilers. In recent years all polymer chemical treatment programs have been introduced and although they are much more benign even all polymer programs must be properly designed and controlled. Under extreme conditions a similar corrosion potential exists. This paper discusses the potential for chelant or polymer corrosion in boilers and the proper safeguards. Case histories are presented.

  1. Nuclear isospin asymmetry in α decay of heavy nuclei

    NASA Astrophysics Data System (ADS)

    Shin, Eunkyoung; Lim, Yeunhwan; Hyun, Chang Ho; Oh, Yongseok

    2016-08-01

    The effects of nuclear isospin asymmetry on α -decay lifetimes of heavy nuclei are investigated within various phenomenological models of the nuclear potential for the α particle. We consider the widely used simple square-well potential and Woods-Saxon potential and modify them by including an isospin asymmetry term. We then suggest a model for the potential of the α particle motivated by a microscopic phenomenological approach of the Skyrme force model, which naturally introduces the isospin-dependent form of the nuclear potential for the α particle. The empirical α -decay lifetime formula of Viola and Seaborg [J. Inorg. Nucl. Chem. 28, 741 (1966), 10.1016/0022-1902(66)80412-8] is also modified to include isospin asymmetry effects. The obtained α -decay half-lives are in good agreement with the experimental data, and we find that including the nuclear isospin effects somehow improves the theoretical results for α -decay half-lives. The implications of these results are discussed, and the predictions on the α -decay lifetimes of superheavy elements are also presented.

  2. Dependence on Spin and Isospin of Short-Range Nuclear Forces in Modified OPEG

    NASA Astrophysics Data System (ADS)

    Tamagaki, R.; Takatsuka, T.

    2001-06-01

    Dependence on spin and isospin of nucleon-nucleon potentials at small inernucleon distances is studied by observing the operator forms deduced from two modified versions of OPEG potentials with the OPEP-tail and Gaussian core terms. A significant difference between their spin- and isospin-dependent features in the core region is noted.

  3. Investigations of QCD at non-zero isospin density

    SciTech Connect

    Zhifeng Shi, William Detmold

    2011-12-01

    We investigate the QCD phase diagram as a function of isospin chemical potential at a fixed temperature by directly putting large numbers of {pi}{sup +}s into the system. Correlation functions of N {pi}{sup +}s systems involves N!N! contractions, and become extremely expensive when N is large. In order to alleviate this problem, a recursion relation of correlation functions has been derived in Ref. [1] that substantially reduces the number of independent contractions needed and makes the study of many pions systems be possible. In this proceeding this method is investigated numerically. We have also constructed a new method that is even more efficient, enabling us to study systems of up to 72 {pi}{sup +}s.

  4. Probing the hadron-quark mixed phase at high isospin and baryon density. Sensitive observables

    NASA Astrophysics Data System (ADS)

    Di Toro, Massimo; Colonna, Maria; Greco, Vincenzo; Shao, Guo-Yun

    2016-08-01

    We discuss the isospin effect on the possible phase transition from hadronic to quark matter at high baryon density and finite temperatures. The two-Equation of State (Two-EoS) model is adopted to describe the hadron-quark phase transition in dense matter formed in heavy-ion collisions. For the hadron sector we use Relativistic Mean-Field (RMF) effective models, already tested on heavy-ion collision (HIC). For the quark phase we consider various effective models, the MIT-Bag static picture, the Nambu-Jona-Lasinio (NJL) approach with chiral dynamics and finally the NJL coupled to the Polyakov-loop field (PNJL), which includes both chiral and (de)confinement dynamics. The idea is to extract mixed phase properties which appear robust with respect to the model differences. In particular we focus on the phase transitions of isospin asymmetric matter, with two main results: i) an earlier transition to a mixed hadron-quark phase, at lower baryon density/chemical potential with respect to symmetric matter; ii) an "Isospin Distillation" to the quark component of the mixed phase, with predicted effects on the final hadron production. Possible observation signals are suggested to probe in heavy-ion collision experiments at intermediate energies, in the range of the NICA program.

  5. Transverse isospin response function of asymmetric nuclear matter from a local isospin density functional

    NASA Astrophysics Data System (ADS)

    Lipparini, Enrico; Pederiva, Francesco

    2016-08-01

    The time dependent local isospin density approximation (TDLIDA) has been extended to the study of the transverse isospin response function in nuclear matter with an arbitrary neutron-proton asymmetry parameter ξ . The energy density functional has been chosen in order to fit existing accurate quantum Monte Carlo calculations with a density dependent potential. The evolution of the response with ξ in the Δ Tz=±1 channels is quite different. While the strength of the Δ Tz=+1 channel disappears rather quickly by increasing the asymmetry, the Δ Tz=-1 channel develops a stronger and stronger collective mode that in the regime typical of neutron star matter at β equilibrium almost completely exhausts the excitation spectrum of the system. The neutrino mean free paths obtained from the TDLIDA responses are strongly dependent on ξ and on the presence of collective modes, leading to a sizable difference with respect to the prediction of the Fermi gas model.

  6. Topological deconfinement transition in QCD at finite isospin density

    NASA Astrophysics Data System (ADS)

    Kashiwa, Kouji; Ohnishi, Akira

    2017-09-01

    The confinement-deconfinement transition is discussed from topological viewpoints. The topological change of the system is achieved by introducing the dimensionless imaginary chemical potential (θ). Then, the non-trivial free-energy degeneracy becomes the signal of the deconfinement transition and it can be visualized by using the map of the thermodynamic quantities to the circle S1 along θ. To understand this "topological" deconfinement transition at finite real quark chemical potential (μR), we consider the isospin chemical potential (μiso) in the effective model of QCD. The phase diagram at finite μiso is identical with that at finite μR outside of the pion-condensed phase at least in the large-Nc limit via the well-known orbifold equivalence. In the present effective model, the topological deconfinement transition does not show a significant dependence on μiso and then we can expect that this tendency also appears at small μR. Also, the chiral transition and the topological deconfinement transition seems to be weakly correlated. If we will access lattice QCD data for the temperature dependence of the quark number density at finite μiso with θ = π / 3, our surmise can be judged.

  7. Potential Functions in Chemical Thermodynamics

    NASA Astrophysics Data System (ADS)

    Araujo, Roger J.

    1998-11-01

    The first and second laws of thermodynamics are stated in equation form. The equation containing the combined laws is used to identify potential functions appropriate to various sets of constraints. An ion-exchange reaction and a redox reaction in a melt are considered as illustrations of the importance of using the potential function appropriate to the constraints.

  8. Chemical Potentials and Activities: An Electrochemical Introduction.

    ERIC Educational Resources Information Center

    Wetzel, T. L.; And Others

    1986-01-01

    Describes a laboratory experiment which explores the effects of adding inert salts to electrolytic cells and demonstrates the difference between concentration and chemical activity. Examines chemical potentials as the driving force of reactions. Provides five examples of cell potential and concentration change. (JM)

  9. QCD sign problem for small chemical potential

    SciTech Connect

    Splittorff, K.; Verbaarschot, J. J. M.

    2007-06-01

    The expectation value of the complex phase factor of the fermion determinant is computed in the microscopic domain of QCD at nonzero chemical potential. We find that the average phase factor is nonvanishing below a critical value of the chemical potential equal to half the pion mass and vanishes exponentially in the volume for larger values of the chemical potential. This holds for QCD with dynamical quarks as well as for quenched and phase quenched QCD. The average phase factor has an essential singularity for zero chemical potential and cannot be obtained by analytic continuation from imaginary chemical potential or by means of a Taylor expansion. The leading order correction in the p-expansion of the chiral Lagrangian is calculated as well.

  10. Classically spinning and isospinning solitons

    NASA Astrophysics Data System (ADS)

    Battye, Richard A.; Haberichter, Mareike

    2012-09-01

    We investigate classically spinning topological solitons in (2+1)- and (3+1)-dimensional models; more explicitely spinning sigma model solitons in 2+1 dimensions and Skyrme solitons in 2+1 and 3+1 dimensions. For example, such types of solitons can be used to describe quasiparticle excitations in ferromagnetic quantum Hall systems or to model spin and isospin states of nuclei. The standard way to obtain solitons with quantised spin and isospin is the semiclassical quantization procedure: One parametrizes the zero-mode space - the space of energy-degenerate soliton configurations generated from a single soliton by spatial translations and rotations in space and isospace - by collective coordinates which are then taken to be time-dependent. This gives rise to additional dynamical terms in the Hamiltonian which can then be quantized following semiclassical quantization rules. A simplification which is often made in the literature is to apply a simple adiabatic approximation to the (iso)rotational zero modes of the soliton by assuming that the soliton's shape is rotational frequency independent. Our numerical results on classically spinning arbitrarily deforming soliton solutions clearly show that soliton deformation cannot be ignored.

  11. The potential for chemical evolution on Titan

    NASA Technical Reports Server (NTRS)

    Beauchamp, P. M.; Lunine, J. I.; Welch, C.

    2002-01-01

    Sampling of organics to determine oxygen content, extent of acetylene polymerization, existence of chiral molecules and enantiomeric excesses, and searches for specific polymer products, would be of interest in assessing how organic chemistry evolves toward biochemistry. Such efforts would require fairly sophisticated chemical analyses from landed missions. This paper examines this chemistry and the potential instruments that could distinguish chemical evolution.

  12. Chemical-potential route for multicomponent fluids

    NASA Astrophysics Data System (ADS)

    Santos, Andrés; Rohrmann, René D.

    2013-05-01

    The chemical potentials of multicomponent fluids are derived in terms of the pair correlation functions for arbitrary number of components, interaction potentials, and dimensionality. The formally exact result is particularized to hard-sphere mixtures with zero or positive nonadditivity. As a simple application, the chemical potentials of three-dimensional additive hard-sphere mixtures are derived from the Percus-Yevick theory and the associated equation of state is obtained. This Percus-Yevick chemical-route equation of state is shown to be more accurate than the virial equation of state. An interpolation between the chemical-potential and compressibility routes exhibits a better performance than the well-known Boublík-Mansoori-Carnahan-Starling-Leland equation of state.

  13. Models of isospin violating ADM

    SciTech Connect

    Okada, Nobuchika; Seto, Osamu

    2014-06-24

    The isospin violating dark matter (IVDM) scenario offers an interesting possibility to reconcile conflicting results among direct dark matter search experiments for a mass range around 10 GeV. We consider two simple renormalizable IVDM models with a complex scalar dark matter and a Dirac fermion dark matter, respectively, whose stability is ensured by the conservation of “dark matter number.” Although both models successfully work as the IVDM scenario with destructive interference between effective couplings to proton and neutron, the dark matter annihilation cross section is found to exceed the cosmological/astrophysical upper bounds. Then, we propose a simple scenario to reconcile the IVDM scenario with the cosmological/astrophysical bounds, namely, the IVDM being asymmetric. We also discuss collider experimental constraints on the models and an implication to Higgs boson physics.

  14. Spin-isospin dependent effective interaction in nuclei

    NASA Astrophysics Data System (ADS)

    Cha, D.; Speth, J.

    1984-08-01

    The spin and isospin dependent part of the nuclear effective interaction is studied using the experimentally known Gamow-Teller states in 48Ca, 90Zr and 208Pb. About half of the strength of the residual interaction in the nucleon-nucleon channel can be expounded by the correlated π + ϱ exchange potential. Also, the corresponding interaction in the delta-nucleon channel is investigated and a reasonable agreement with the observed qunchiing of the Gamow-Teller strength is obtained.

  15. Isobaric Multiplet Yrast Energies and Isospin Nonconserving Forces

    NASA Astrophysics Data System (ADS)

    Zuker, A. P.; Lenzi, S. M.; Martínez-Pinedo, G.; Poves, A.

    2002-09-01

    The isovector and isotensor energy differences between yrast states of isobaric multiplets in the lower half of the pf region are quantitatively reproduced in a shell model context. The isospin nonconserving nuclear interactions are found to be at least as important as the Coulomb potential. Their isovector and isotensor channels are dominated by J=2 and J=0 pairing terms, respectively. The results are sensitive to the radii of the states, whose evolution along the yrast band can be accurately followed.

  16. Holographic vector mesons from spectral functions at finite baryon or isospin density

    SciTech Connect

    Erdmenger, Johanna; Kaminski, Matthias; Rust, Felix

    2008-02-15

    We consider gauge/gravity duality with flavor for the finite-temperature field theory dual of the AdS-Schwarzschild black hole background with embedded D7-brane probes. In particular, we investigate spectral functions at finite baryon density in the black hole phase. We determine the resonance frequencies corresponding to meson-mass peaks as function of the quark mass over temperature ratio. We find that these frequencies have a minimum for a finite value of the quark mass. If the quotient of quark mass and temperature is increased further, the peaks move to larger frequencies. At the same time the peaks narrow, in agreement with the formation of nearly stable vector meson states which exactly reproduce the meson-mass spectrum found at zero temperature. We also calculate the diffusion coefficient, which has finite value for all quark mass to temperature ratios, and exhibits a first-order phase transition. Finally we consider an isospin chemical potential and find that the spectral functions display a resonance peak splitting, similar to the isospin meson-mass splitting observed in effective QCD models.

  17. The Encyclopedia of Chemical Electrode Potentials

    SciTech Connect

    Antelman, M.S.

    1982-01-01

    Designed for industrial chemists concerned with chemical potential data in their day-to-day performance of experiments, The Encyclopedia of Chemical Electrode Potentials is the most comprehensive listing of chemical electrode potentials available today, including dat derived from many different reports, articles, and tabulations, and also previously unpublished complex formation EMF data. Thermodynamic calculations based on data reflecting varying conditions have made it possible to integrate results obtained at different pressures and electrolyte concentrations into a useful electromotive series. The electrochemical series which constitutes the core of the Encyclopedia embodies a novel arrangement which differentiates between anions, cations, complexes, and compounds. For the convenience of the practicing chemist, the data are made accessible in a number of different ways: all the information in the electrochemical series is reorganized into a listing of electrode potentials by element.

  18. Potentiation of Chemical Ototoxicity by Noise

    PubMed Central

    Steyger, Peter S.

    2010-01-01

    High-intensity and/or prolonged exposure to noise causes temporary or permanent threshold shifts in auditory perception. Occupational exposure to solvents or administration of clinically important drugs, such as aminoglycoside antibiotics and cisplatin, also can induce permanent hearing loss. The mechanisms by which these ototoxic insults cause auditory dysfunction are still being unraveled, yet they share common sequelae, particularly generation of reactive oxygen species, that ultimately lead to hearing loss and deafness. Individuals are frequently exposed to ototoxic chemical contaminants (e.g., fuel) and noise simultaneously in a variety of work and recreational environments. Does simultaneous exposure to chemical ototoxins and noise potentiate auditory dysfunction? Exposure to solvent vapor in noisy environments potentiates the permanent threshold shifts induced by noise alone. Moderate noise levels potentiate both aminoglycoside- and cisplatin-induced ototoxicity in both rate of onset and in severity of auditory dysfunction. Thus, simultaneous exposure to chemical ototoxins and moderate levels of noise can potentiate auditory dysfunction. Preventing the ototoxic synergy of noise and chemical ototoxins requires removing exposure to ototoxins and/or attenuating noise exposure levels when chemical ototoxins are present. PMID:20523755

  19. Chemical reactivity measurements: potential for characterization of respiratory chemical allergens.

    PubMed

    Lalko, Jon F; Kimber, Ian; Dearman, Rebecca J; Gerberick, G Frank; Sarlo, Katherine; Api, Anne Marie

    2011-03-01

    Allergic diseases of the skin and respiratory tract resulting from exposure to low molecular weight chemicals remain important issues for consumer product development and occupational/environmental health. Widespread opportunities for exposure to chemical allergens require that there are available effective methods for hazard identification and risk assessment. In the search for new tools for hazard identification/characterization there has been interest in developing alternative methods that will reduce, refine or replace the need for animals. One approach that shows promise is based on the measurement of the peptide reactivity of chemicals; the potential to form stable associations with protein/peptide being a key requirement for the induction of sensitization. Recent investigations using these systems have focused primarily on skin sensitizing chemicals. However, there is interest in the possibility of exploiting these same experimental approaches to distinguish between different forms of chemical allergens - as individual materials are primarily associated with one or the other form of sensitization in humans. These investigations may also provide insight into why chemical sensitizers can differ in the form of allergic disease they will preferentially induce. These opportunities are surveyed here against a background of the immunobiology of allergic sensitization and current state-of-the-art approaches to measurement of peptide/protein reactivity. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Antinucleon as a probe of nuclear spin and isospin excitations

    NASA Astrophysics Data System (ADS)

    Dover, C. B.; Sainio, M. E.; Walker, G. E.

    1983-12-01

    Using two models for the antinucleon-nucleon (N¯N) interaction, we obtain complex, energy dependent N¯N transition operators t appropriate for (N¯, N¯') inelastic scattering studies on complex nuclei. It is shown that the spin-isospin dependence of the N¯N annihilation potential plays an important role in determining the dominant spin-isospin modes in the nuclear response. In particular, for the most realistic of our N¯N models, a large spin dependent component tσ is obtained, leading to the strong excitation of isoscalar spin-flip states; this term is suppressed in the corresponding NN t matrix. The central spin and isospin independent term, tc0, is large for N¯N, at all relevant momentum transfers q. At high q the isoscalar spin-orbit (tLS0) and isovector tensor (tTτ) components are important. Cross section and analyzing power predictions for N¯ inelastic scattering as well as corrections due to energy and density dependence are discussed.

  1. Chemical-Sensing Cables Detect Potential Threats

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Intelligent Optical Systems Inc. (IOS) completed Phase I and II Small Business Innovation Research (SBIR) contracts with NASA's Langley Research Center to develop moisture- and pH-sensitive sensors to detect corrosion or pre-corrosive conditions, warning of potentially dangerous conditions before significant structural damage occurs. This new type of sensor uses a specially manufactured optical fiber whose entire length is chemically sensitive, changing color in response to contact with its target, and demonstrated to detect potentially corrosive moisture incursions to within 2 cm. After completing the work with NASA, the company received a Defense Advanced Research Projects Agency (DARPA) Phase III SBIR to develop the sensors further for detecting chemical warfare agents, for which they proved just as successful. The company then worked with the U.S. Department of Defense (DoD) to fine tune the sensors for detecting potential threats, such as toxic industrial compounds and nerve agents. In addition to the work with government agencies, Intelligent Optical Systems has sold the chemically sensitive fiber optic cables to major automotive and aerospace companies, who are finding a variety of uses for the devices. Marketed under the brand name Distributed Intrinsic Chemical Agent Sensing and Transmission (DICAST), these unique continuous-cable fiber optic chemical sensors can serve in a variety of applications: Corrosive-condition monitoring, aiding experimentation with nontraditional power sources, as an economical means of detecting chemical release in large facilities, as an inexpensive "alarm" systems to alert the user to a change in the chemical environment anywhere along the cable, or in distance-resolved optical time domain reflectometry systems to provide detailed profiles of chemical concentration versus length.

  2. Thermal inflation with flaton chemical potential

    NASA Astrophysics Data System (ADS)

    Arai, Masato; Kobayashi, Yoshishige; Okada, Nobuchika; Sasaki, Shin

    2017-04-01

    Thermal inflation driven by a scalar field called a "flaton" is a possible scenario to solve the cosmological moduli problem. We study a model of thermal inflation with a flaton chemical potential. In the presence of the chemical potential, a negative mass squared of the flaton—which is necessary to terminate thermal inflation—is naturally induced. We identify the allowed parameter region for the chemical potential (μ ) and the flaton self-coupling constant to solve the cosmological moduli problem and satisfy theoretical consistencies. In general, the chemical potential is a free parameter and it can be taken to be much larger than the typical scale of soft supersymmetry-breaking parameters of O (1 ) TeV . For μ ≳1 08 GeV , we find that the reheating temperature after thermal inflation can be high enough for the thermal leptogenesis scenario to be operative. This is in sharp contrast to the standard thermal inflation scenario, in which the reheating temperature is quite low and a special mechanism is necessary for generating a sufficient amount of baryon asymmetry in the Universe after thermal inflation.

  3. Quasi-particles at finite chemical potential

    SciTech Connect

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

    2010-07-27

    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.

  4. Isospin dependence of cluster recognition and multifragment production

    SciTech Connect

    Rajni, Vermani, Yogesh K.

    2016-05-06

    The isospin dependent quantum molecular dynamics (IQMD) model is used to study the role of isospin dependent clustering mechanism in Au+Au collisions at 100 and 600 MeV/A. A significant influence of clustering mechanism via isospin dependent spatial constraints was clearly seen on the fragment observables such as persistence, binding energy and the mean multiplicity of intermediate mass fragments. The model calculations using isospin dependent clusterization approach are able to describe the ALADiN multifragmentation data.

  5. Luminescence and chemical potential of solar cells

    NASA Astrophysics Data System (ADS)

    Smestad, Greg P.; Ries, Harald

    1991-12-01

    The transduction and conversion of radiant energy into work in a quantum process are dependant on the luminescent properties of the materials involved. Materials with photoluminescent efficiencies greater than 0.1% are likely candidates for solar cells and solar converters. The luminescent optical properties of a material are directly related to the output device parameters. The chemical potential of the incoming light is a function of the photon energy and incident radiance. The amount of work per particle, or voltage, that can be extracted by a solar converter is related to chemical potential of the excitation, which can be inferred from the photoluminescence efficiency at ambient temperature. A discussion is made as to the use and optical properties of materials such as Si and GaAs, FeS2, and biological and organic dyes as efficient solar quantum converter materials. Proper choice of absorber thickness as to maximize the luminescent output observed is shown to optimize solar converter performance.

  6. Random matrix triality at nonzero chemical potential

    SciTech Connect

    Halasz, M.A.; Osborn, J.C.; Verbaarschot, J.J.

    1997-12-01

    We introduce three universality classes of chiral random matrix ensembles with a nonzero chemical potential and real, complex or quaternion real matrix elements. In the thermodynamic limit we find that the distribution of the eigenvalues in the complex plane does not depend on the Dyson index, and is given by the solution proposed by Stephanov. For a finite number of degrees of freedom, N, we find an accumulation of eigenvalues on the imaginary axis for real matrices, whereas for quaternion real matrices we find a depletion of eigenvalues in this domain. This effect is of order 1/{radical} (N) . In particular for the real case the resolvent shows a discontinuity of order 1/{radical} (N) . These results are in agreement with lattice QCD simulations with staggered fermions and recent instanton liquid simulations both for two colors and a nonzero chemical potential. {copyright} {ital 1997} {ital The American Physical Society}

  7. Isospin dependence of the three-nucleon force

    SciTech Connect

    Evgeny Epelbaum; Ulf-G. Meissner; Juan Palomar

    2004-07-01

    We classify A--nucleon forces according to their isospin dependence and discuss the most general isospin structure of the three--nucleon force. We derive the leading and subleading isospin--breaking corrections to the three--nucleon force using the framework of chiral effective field theory.

  8. Isospin-violating nucleon-nucleon forces using the method of unitary transformation

    SciTech Connect

    Evgeny Epelbaum; Ulf-G. Meissner

    2005-02-01

    Recently, we have derived the leading and subleading isospin-breaking three-nucleon forces using the method of unitary transformation. In the present work we extend this analysis and consider the corresponding two-nucleon forces using the same approach. Certain contributions to the isospin-violating one- and two-pion exchange potential have already been discussed by various groups within the effective field theory framework. Our findings agree with the previously obtained results. In addition, we present the expressions for the subleading charge-symmetry-breaking two-pion exchange potential which were not considered before. These corrections turn out to be numerically important. Together with the three-nucleon force results presented in our previous work, the results of the present study specify completely isospin-violating nuclear force up to the order {Lambda}{sup 5}.

  9. Meson spectral functions at finite temperature and isospin density with the functional renormalization group

    NASA Astrophysics Data System (ADS)

    Wang, Ziyue; Zhuang, Pengfei

    2017-07-01

    The pion superfluid and the corresponding Goldstone and soft modes are investigated in a two-flavor quark-meson model with a functional renormalization group. By solving the flow equations for the effective potential and the meson two-point functions at finite temperature and isospin density, the critical temperature for the superfluid increases sizeably in comparison with solving the flow equation for the potential only. The spectral function for the soft mode shows clearly a transition from meson gas to quark gas with increasing temperature and a crossover from Bose-Einstein condensation to Bardeen-Cooper-Schrieffer pairing of quarks with increasing isospin density.

  10. Isospin Splittings of Doubly Heavy Baryons

    SciTech Connect

    Brodsky, Stanley J.; Guo, Feng-Kun; Hanhart, Christoph; Meissner, Ulf-G.; /Julich, Forschungszentrum /JCHP, Julich /IAS, Julich /Bonn U., HISKP /Bonn U.

    2011-08-18

    The SELEX Collaboration has reported a very large isospin splitting of doubly charmed baryons. We show that this effect would imply that the doubly charmed baryons are very compact. One intriguing possibility is that such baryons have a linear geometry Q-q-Q where the light quark q oscillates between the two heavy quarks Q, analogous to a linear molecule such as carbon dioxide. However, using conventional arguments, the size of a heavy-light hadron is expected to be around 0.5 fm, much larger than the size needed to explain the observed large isospin splitting. Assuming the distance between two heavy quarks is much smaller than that between the light quark and a heavy one, the doubly heavy baryons are related to the heavy mesons via heavy quark-diquark symmetry. Based on this symmetry, we predict the isospin splittings for doubly heavy baryons including {Xi}{sub cc}, {Xi}{sub bb} and {Xi}{sub bc}. The prediction for the {Xi}{sub cc} is much smaller than the SELEX value. On the other hand, the {Xi}{sub bb} baryons are predicted to have an isospin splitting as large as (6.3 {+-} 1.7) MeV. An experimental study of doubly bottomed baryons is therefore very important to better understand the structure of baryons with heavy quarks.

  11. Isospin-symmetry breaking in superallowed Fermi β-decay due to isospin-nonconserving forces

    NASA Astrophysics Data System (ADS)

    Kaneko, K.; Sun, Y.; Mizusaki, T.; Tazaki, S.; Ghorui, S. K.

    2017-10-01

    We investigate isospin-symmetry breaking effects in the sd-shell region with large-scale shell-model calculations, aiming to understand the recent anomalies observed in superallowed Fermi β-decay. We begin with calculations of Coulomb displacement energies (CDE's) and triplet displacement energies (TDE's) by adding the T = 1 , J = 0 isospin nonconserving (INC) interaction into the usual isospin-invariant Hamiltonian. It is found that CDE's and TDE's can be systematically described with high accuracy. A total number of 122 one- and two-proton separation energies are predicted accordingly, and locations of the proton drip-line and candidates for proton-emitters are thereby suggested. However, attempt to explain the anomalies in the superallowed Fermi β-decay fails because these well-fitted T = 1 , J = 0 INC interactions are found no effects on the nuclear matrix elements. It is demonstrated that the observed large isospin-breaking correction in the 32Cl β-decay, the large isospin-mixing in the 31Cl β-decay, and the small isospin-mixing in the 23Al β-decay can be consistently understood by introducing additional T = 1 , J = 2 INC interactions related to the s1/2 orbit.

  12. Isospin breaking and chiral symmetry restoration

    SciTech Connect

    Gomez Nicola, A.; Torres Andres, R.

    2011-04-01

    We analyze quark condensates and chiral (scalar) susceptibilities including isospin-breaking effects at finite temperature T. These include m{sub u{ne}}m{sub d} contributions as well as electromagnetic (e{ne}0) corrections, both treated in a consistent chiral Lagrangian framework to leading order in SU(2) and SU(3) chiral perturbation theory, so that our predictions are model-independent. The chiral restoration temperature extracted from = is almost unaffected, while the isospin-breaking order parameter grows with T for the three-flavor case SU(3). We derive a sum rule relating the condensate ratio (e{ne}0)/(e=0) with the scalar susceptibility difference {chi}(T)-{chi}(0), directly measurable on the lattice. This sum rule is useful also for estimating condensate errors in staggered lattice analysis. Keeping m{sub u{ne}}m{sub d} allows one to obtain the connected and disconnected contributions to the susceptibility, even in the isospin limit, whose temperature, mass, and isospin-breaking dependence we analyze in detail. The disconnected part grows linearly, diverging in the chiral (infrared) limit as T/M{sub {pi}}, while the connected part shows a quadratic behavior, infrared regular as T{sup 2}/M{sub {eta}}{sup 2}, and coming from {pi}{sup 0{eta}} mixing terms. This smooth connected behavior suggests that isospin-breaking correlations are weaker than critical chiral ones near the transition temperature. We explore some consequences in connection with lattice data and their scaling properties, for which our present analysis for physical masses, i.e. beyond the chiral limit, provides a useful model-independent description for low and moderate temperatures.

  13. Computed potential energy surfaces for chemical reactions

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.

    1994-01-01

    Quantum mechanical methods have been used to compute potential energy surfaces for chemical reactions. The reactions studied were among those believed to be important to the NASP and HSR programs and included the recombination of two H atoms with several different third bodies; the reactions in the thermal Zeldovich mechanism; the reactions of H atom with O2, N2, and NO; reactions involved in the thermal De-NO(x) process; and the reaction of CH(squared Pi) with N2 (leading to 'prompt NO'). These potential energy surfaces have been used to compute reaction rate constants and rates of unimolecular decomposition. An additional application was the calculation of transport properties of gases using a semiclassical approximation (and in the case of interactions involving hydrogen inclusion of quantum mechanical effects).

  14. Dynamical isospin effects in nucleon-induced reactions

    SciTech Connect

    Ou Li; Li Zhuxia; Wu Xizhen

    2008-10-15

    The isospin effects in proton-induced reactions on isotopes of {sup 112-132}Sn and the corresponding {beta}-stable isobars are studied by means of the improved quantum molecular dynamics model and some sensitive probes for the density dependence of the symmetry energy at subnormal densities are proposed. The beam energy range is chosen to be 100-300 MeV. Our study shows that the system size dependence of the reaction cross sections for p+{sup 112-132}Sn deviates from the Carlson's empirical expression obtained by fitting the reaction cross sections for proton on nuclei along the {beta}-stability line and sensitively depends on the stiffness of the symmetry energy. We also find that the angular distribution of elastic scattering for p+{sup 132}Sn at large impact parameters is very sensitive to the density dependence of the symmetry energy, which is uniquely due to the effect of the symmetry potential with no mixture of the effect from the isospin dependence of the nucleon-nucleon cross sections. The isospin effects in neutron-induced reactions are also studied and it is found that the effects are just opposite to that in proton-induced reactions. We find that the difference between the peaks of the angular distributions of elastic scattering for p+{sup 132}Sn and n+{sup 132}Sn at E{sub p,n}=100 MeV and b=7.5 fm is positive for soft symmetry energy U{sub sym}{sup sf} and negative for super-stiff symmetry energy U{sub sym}{sup nlin} and close to zero for linear density dependent symmetry energy U{sub sym}{sup lin}, which seems very useful for constraining the density dependence of the symmetry energy at subnormal densities.

  15. Quark number fluctuations at finite temperature and finite chemical potential via the Dyson-Schwinger equation approach

    NASA Astrophysics Data System (ADS)

    Xin, Xian-yin; Qin, Si-xue; Liu, Yu-xin

    2014-10-01

    We investigate the quark number fluctuations up to the fourth order in the matter composed of two light flavor quarks with isospin symmetry and at finite temperature and finite chemical potential using the Dyson-Schwinger equation approach of QCD. In order to solve the quark gap equation, we approximate the dressed quark-gluon vertex with the bare one and adopt both the Maris-Tandy model and the infrared constant (Qin-Chang) model for the dressed gluon propagator. Our results indicate that the second, third, and fourth order fluctuations of net quark number all diverge at the critical endpoint (CEP). Around the CEP, the second order fluctuation possesses obvious pump while the third and fourth order ones exhibit distinct wiggles between positive and negative. For the Maris-Tandy model and the Qin-Chang model, we give the pseudocritical temperature at zero quark chemical potential as Tc=146 MeV and 150 MeV, and locate the CEP at (μEq,TE)=(120,124) MeV and (124,129) MeV, respectively. In addition, our results manifest that the fluctuations are insensitive to the details of the model, but the location of the CEP shifts to low chemical potential and high temperature as the confinement length scale increases.

  16. Nuclear spin isospin responses for low-energy neutrinos

    NASA Astrophysics Data System (ADS)

    Ejiri, H.

    2000-11-01

    Nuclear spin isospin responses for low-energy neutrinos of current astroparticle physics interests are briefly reviewed. Neutrinos are key particles for new particle physics beyond the standard electro-weak theory, and sensitive probes for studying stellar evolution and astronuclear processes. Low-energy neutrinos with energies of Eν~=0.1-50MeV have been studied extensively by using nuclei as micro-laboratories. Nuclear weak processes involved are vector and axial-vector weak interactions. Accordingly, nuclear isospin and spin isospin responses for neutrinos are crucial for studying neutrinos through nuclear weak processes. Nuclei show spin isospin responses characteristic of nuclear spin isospin structures. Nuclear spin isospin responses are investigated by relevant electromagnetic and hadronic processes. Subjects discussed include nuclear spin isospin responses for neutrinos and spin isospin giant resonances, hadronic charge-exchange spin-flip and non spin-flip reactions used for studying nuclear spin isospin responses, nuclear responses for neutrinos associated with double beta decays, nuclear spin isospin responses for solar neutrinos, and nuclear responses for supernova and accelerator-based neutrinos.

  17. Chemical Potential of a Lennard Jones Fluid

    NASA Astrophysics Data System (ADS)

    Celebonovic, V.

    2010-12-01

    The aim of this paper is to present results of analytical calculation of chemical potential of a Lennard Jones (LJ) fluid performed in two ways: by using the thermodynamical formalism and the formalism of statistical mechanics. The integration range is divided into two regions. In the small distance region, which is r≤σ in the usual notation, the integration range had to be cut off in order to avoid the occurence of divergences. In the large distance region, the calculation is technically simpler. The calculation reported here will be useful in all kinds of studies concerning phase equilibrium in a LJ fluid. Interesting kinds of such systems are the giant planets and the icy satellites in various planetary systems, but also the (so far) hypothetical quark stars.

  18. Holographic phase transitions at finite chemical potential

    NASA Astrophysics Data System (ADS)

    Mateos, David; Matsuura, Shunji; Myers, Robert C.; Thomson, Rowan M.

    2007-11-01

    Recently, holographic techniques have been used to study the thermal properties of Script N = 2 super-Yang-Mills theory, with gauge group SU(Nc) and coupled to Nf << Nc flavours of fundamental matter, at large Nc and large 't Hooft coupling. Here we consider the phase diagram as a function of temperature and baryon chemical potential μb. For fixed μb < NcMq there is a line of first order thermal phase transitions separating a region with vanishing baryon density and one with nonzero density. For fixed μb>Nc Mq there is no phase transition as a function of the temperature and the baryon density is always nonzero. We also compare the present results for the grand canonical ensemble with those for canonical ensemble in which the baryon density is held fixed [1].

  19. Isospin mixing from β -delayed proton emission

    NASA Astrophysics Data System (ADS)

    Smirnova, N. A.; Blank, B.; Brown, B. A.; Richter, W. A.; Benouaret, N.; Lam, Y. H.

    2017-05-01

    We present a general scheme of a shell-model analysis of a β -delayed proton emission. We show that the experimental proton to γ -ray branching ratio for the isobaric analog state (IAS) populated in β decay of a precursor, supplemented by theoretical proton and γ -ray widths, can be used to extract spectroscopic factors for isospin-forbidden proton emission. In the case of a well-justified two-level mixing approximation and a relatively well known spectroscopic factor of the admixed state, the proposed scheme provides a new way to determine the amount of the isospin mixing in the IAS. This conjecture is illustrated by the theoretical analysis of 44Cr and 48Fe decay.

  20. Light scalar susceptibilities and isospin breaking

    SciTech Connect

    Andres, R. Torres; Nicola, A. Gomez

    2010-12-28

    Making a thermal analysis in the context of NLO SU(3) Chiral Perturbation Theory we see that isospin breaking (IB) corrections (both electromagnetic and QCD ones) to quark condensates are of order O(e{sup 2}) and O({epsilon}), with {epsilon} the {pi}{sup 0}-{eta} mixing angle. However the combination {chi}{sub uu}-{chi}{sub ud} of flavour breaking susceptibilities, which vanishes in the isospin limit and can be identified essentially with the connected susceptibility, has an order O(1) contribution enhanced with T because of the {pi}{sup 0}-{eta}) mixing. Finally we present a thermal sum rule that relates quark condensate ratios and the light scalar susceptibility without IB, {chi}(T)-{chi}(0).

  1. Isospin purity in the A=42 isobars

    SciTech Connect

    Orce, J.N.; McKay, C.J.; Choudry, S.N.; Lesher, S.L.; Mynk, M.; Bandyopadhyay, D.; Yates, S.W.; McEllistrem, M.T.; Petkov, P.

    2004-09-13

    The lifetime of the first 2{sub T=1}{sup +} state in 42Sc has been measured as 74(16) fs. This result gives a value for the isoscalar matrix element of M0=6.63(76). From the mirror nuclei, 42Ca and 42Ti, the isoscalar matrix element is given as 7.15(48) W.u., confirming isospin purity in the A=42 isobars.

  2. Variation after Spin-Isospin Projection in the Skyrme Model

    NASA Astrophysics Data System (ADS)

    Shiino, E.; Hosaka, A.; Toki, H.

    1987-07-01

    We calculate nucleon, delta and higher spin-isospin baryons by making variation of the hedgehog function after the spin-isospin projection. The nucleon and delta masses are lowered only a small amount as compared to the case of variation before spin-isospin projection. The axial coupling g_{A} of the nucleon is, however, changed from 1.33 to 1.20.

  3. Crystallization: A phase transition process driving by chemical potential decrease

    NASA Astrophysics Data System (ADS)

    Sun, Congting; Xue, Dongfeng

    2017-07-01

    A chemical bonding model is established to describe the chemical potential decrease during crystallization. In the nucleation stage, in situ molecular vibration spectroscopy shows the increased vibration energy of constituent groups, indicating the shortened chemical bonding and the decreased chemical potential towards the formation of nuclei. Starting from the Gibbs free energy formula, the chemical potential decrease during crystallization is scaled, which depends on the released chemical bonding energy per unit phase transition zone. In the crystal growth, the direction-dependent growth rate of inorganic single crystals can be quantitatively determined, their anisotropic thermodynamic morphology can thus be constructed on the basis of relative growth rates.

  4. Chemical-potential-based lattice Boltzmann method for nonideal fluids

    NASA Astrophysics Data System (ADS)

    Wen, Binghai; Zhou, Xuan; He, Bing; Zhang, Chaoying; Fang, Haiping

    2017-06-01

    Chemical potential, as an important thermodynamic quantity, has been popularly used in thermodynamic modeling for complex systems, especially for those involving the phase transitions and chemical reactions. Here we present a chemical-potential-based multiphase lattice Boltzmann model, in which the nonideal force is directly evaluated by a chemical potential. The numerical computation is more efficient than the pressure-tensor-based model [Wen et al. Europhys. Lett. 112, 44002 (2015), 10.1209/0295-5075/112/44002] because the calculations of the pressure tensor and its divergence are avoided. We have derived several chemical potentials of the popular equations of state from the free-energy density function. The theoretical analyses and numerical results support that the present model satisfies thermodynamics and Galilean invariance. An effective chemical-potential boundary condition is also implemented to investigate the wettability of a solid surface, and the contact angle can be linearly tuned by the surface chemical potential.

  5. Dependence of fusion on isospin dynamics

    NASA Astrophysics Data System (ADS)

    Godbey, K.; Umar, A. S.; Simenel, C.

    2017-01-01

    We introduce a new microscopic approach to calculate the dependence of fusion barriers and cross sections on isospin dynamics. The method is based on the time-dependent Hartree-Fock theory and the isoscalar and isovector properties of the energy density functional (EDF). The contribution to the fusion barriers originating from the isoscalar and isovector parts of the EDF is calculated. It is shown that, for nonsymmetric systems, the isovector dynamics influence the subbarrier fusion cross sections. For most systems this results in an enhancement of the subbarrier cross sections, while for others we observe differing degrees of hindrance. We use this approach to provide an explanation of recently measured fusion cross sections which show a enhancement at low Ec .m . energies for the system 40Ca+132Sn as compared with the more neutron-rich system 48Ca+132Sn and discuss the dependence of subbarrier fusion cross sections on transfer.

  6. Quarksonic matter at high isospin density

    NASA Astrophysics Data System (ADS)

    Cao, Gaoqing; He, Lianyi; Huang, Xu-Guang

    2017-05-01

    Analogous to the quarkyonic matter at high baryon density in which the quark Fermi seas and the baryonic excitations coexist, it is argued that a “quarksonic matter” phase appears at high isospin density where the quark (antiquark) Fermi seas and the mesonic excitations coexist. We explore this phase in detail in both large N c and asymptotically free limits. In the large N c limit, we sketch a phase diagram for the quarksonic matter. In the asymptotically free limit, we study the pion superfluidity and thermodynamics of the quarksonic matter by using both perturbative calculations and an effective model. Supported by Thousand Young Talents Program of China, Shanghai Natural Science Foundation, (14ZR1403000) and NSFC (11535012), China Postdoctoral Science Foundation (KLH1512072)

  7. Computed potential energy surfaces for chemical reactions

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.

    1990-01-01

    The objective was to obtain accurate potential energy surfaces (PES's) for a number of reactions which are important in the H/N/O combustion process. The interest in this is centered around the design of the SCRAM jet engine for the National Aerospace Plane (NASP), which was envisioned as an air-breathing hydrogen-burning vehicle capable of reaching velocities as large as Mach 25. Preliminary studies indicated that the supersonic flow in the combustor region of the scram jet engine required accurate reaction rate data for reactions in the H/N/O system, some of which was not readily available from experiment. The most important class of combustion reactions from the standpoint of the NASP project are radical recombinaton reactions, since these reactions result in most of the heat release in the combustion process. Theoretical characterizations of the potential energy surfaces for these reactions are presented and discussed.

  8. Computed potential energy surfaces for chemical reactions

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.; Levin, Eugene

    1993-01-01

    A new global potential energy surface (PES) is being generated for O(P-3) + H2 yields OH + H. This surface is being fit using the rotated Morse oscillator method, which was used to fit the previous POL-CI surface. The new surface is expected to be more accurate and also includes a much more complete sampling of bent geometries. A new study has been undertaken of the reaction N + O2 yields NO + O. The new studies have focused on the region of the surface near a possible minimum corresponding to the peroxy form of NOO. A large portion of the PES for this second reaction has been mapped out. Since state to state cross sections for the reaction are important in the chemistry of high temperature air, these studies will probably be extended to permit generation of a new global potential for reaction.

  9. Flat space (higher spin) gravity with chemical potentials

    NASA Astrophysics Data System (ADS)

    Gary, Michael; Grumiller, Daniel; Riegler, Max; Rosseel, Jan

    2015-01-01

    We introduce flat space spin-3 gravity in the presence of chemical potentials and discuss some applications to flat space cosmology solutions, their entropy, free energy and flat space orbifold singularity resolution. Our results include flat space Einstein gravity with chemical potentials as special case. We discover novel types of phase transitions between flat space cosmologies with spin-3 hair and show that the branch that continuously connects to spin-2 gravity becomes thermodynamically unstable for sufficiently large temperature or spin-3 chemical potential.

  10. Perturbative thermodynamics at nonzero isospin density for cold QCD

    NASA Astrophysics Data System (ADS)

    Graf, Thorben; Schaffner-Bielich, Juergen; Fraga, Eduardo S.

    2016-04-01

    We use next-to-leading order in perturbation theory to investigate the effects of a finite isospin density on the thermodynamics of cold strongly interacting matter. Our results include nonzero quark masses and are compared to lattice data.

  11. Isospin Mixing in 80Zr: From Finite to Zero Temperature

    NASA Astrophysics Data System (ADS)

    Ceruti, S.; Camera, F.; Bracco, A.; Avigo, R.; Benzoni, G.; Blasi, N.; Bocchi, G.; Bottoni, S.; Brambilla, S.; Crespi, F. C. L.; Giaz, A.; Leoni, S.; Mentana, A.; Million, B.; Morales, A. I.; Nicolini, R.; Pellegri, L.; Pullia, A.; Riboldi, S.; Wieland, O.; Birkenbach, B.; Bazzacco, D.; Ciemala, M.; Désesquelles, P.; Eberth, J.; Farnea, E.; Görgen, A.; Gottardo, A.; Hess, H.; Judson, D. S.; Jungclaus, A.; Kmiecik, M.; Korten, W.; Maj, A.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Modamio, V.; Montanari, D.; Myalski, S.; Napoli, D.; Quintana, B.; Reiter, P.; Recchia, F.; Rosso, D.; Sahin, E.; Salsac, M. D.; Söderström, P.-A.; Stezowski, O.; Theisen, Ch.; Ur, C.; Valiente-Dobón, J. J.; Zieblinski, M.

    2015-11-01

    The isospin mixing was deduced in the compound nucleus 80Zr at an excitation energy of E*=54 MeV from the γ decay of the giant dipole resonance. The reaction 40Ca + 40Ca at Ebeam=136 MeV was used to form the compound nucleus in the isospin I =0 channel, while the reaction 37Cl + 44Ca at Ebeam=95 MeV was used as the reference reaction. The γ rays were detected with the AGATA demonstrator array coupled with LaBr3 :Ce detectors. The temperature dependence of the isospin mixing was obtained and the zero-temperature value deduced. The isospin-symmetry-breaking correction δC used for the Fermi superallowed transitions was extracted and found to be consistent with β -decay data.

  12. Isospin Breaking in the Goldberger-Treiman Discrepancies

    SciTech Connect

    Jose Goity; Jordi Saez

    2002-09-01

    Effects of isospin breaking at the level of the Goldberger-Treiman discrepancies involving the neutral isotriplet axial and pion-nucleon couplings are analyzed to leading non-trivial order in chiral perturbation theory.

  13. Valley-isospin dependence of the quantum Hall effect in a graphene p-n junction

    NASA Astrophysics Data System (ADS)

    Tworzydło, J.; Snyman, I.; Akhmerov, A. R.; Beenakker, C. W. J.

    2007-07-01

    We calculate the conductance G of a bipolar junction in a graphene nanoribbon, in the high-magnetic-field regime where the Hall conductance in the p -doped and n -doped regions is 2e2/h . In the absence of intervalley scattering, the result G=(e2/h)(1-cosΦ) depends only on the angle Φ between the valley isospins ( =Bloch vectors representing the spinor of the valley polarization) at the two opposite edges. This plateau in the conductance versus Fermi energy is insensitive to electrostatic disorder, while it is destabilized by the dispersionless edge state which may exist at a zigzag boundary. A strain-induced vector potential shifts the conductance plateau up or down by rotating the valley isospin.

  14. Efficiency at maximum power for an isothermal chemical engine with particle exchange at varying chemical potential

    NASA Astrophysics Data System (ADS)

    Koning, Jesper; Koga, Kenichiro; Indekeu, Joseph. O.

    2017-02-01

    We calculate the efficiency at maximum power (EMP) of an isothermal chemical cycle in which particle uptake occurs at a fixed chemical potential but particle release takes place at varying chemical potential. We obtain the EMP as a function of Δμ/ kT, where Δμ is the difference between the highest and lowest reservoir chemical potentials and T is the absolute temperature. In the linear response limit, Δμ ≪ kT, the EMP tends to the expected universal value 1/2.

  15. Shell Model Depiction of Isospin Mixing in sd Shell

    SciTech Connect

    Lam, Yi Hua; Smirnova, Nadya A.; Caurier, Etienne

    2011-11-30

    We constructed a new empirical isospin-symmetry breaking (ISB) Hamiltonian in the sd(1s{sub 1/2}, 0d{sub 5/2} and 0d{sub 3/2}) shell-model space. In this contribution, we present its application to two important case studies: (i){beta}-delayed proton emission from {sup 22}Al and (ii) isospin-mixing correction to superallowed 0{sup +}{yields}0{sup +}{beta}-decay ft-values.

  16. Computed potential energy surfaces for chemical reactions

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.

    1988-01-01

    The minimum energy path for the addition of a hydrogen atom to N2 is characterized in CASSCF/CCI calculations using the (4s3p2d1f/3s2p1d) basis set, with additional single point calculations at the stationary points of the potential energy surface using the (5s4p3d2f/4s3p2d) basis set. These calculations represent the most extensive set of ab initio calculations completed to date, yielding a zero point corrected barrier for HN2 dissociation of approx. 8.5 kcal mol/1. The lifetime of the HN2 species is estimated from the calculated geometries and energetics using both conventional Transition State Theory and a method which utilizes an Eckart barrier to compute one dimensional quantum mechanical tunneling effects. It is concluded that the lifetime of the HN2 species is very short, greatly limiting its role in both termolecular recombination reactions and combustion processes.

  17. EVALUATION OF TRICLOSAN AS A POTENTIAL ENDOCRINE DISRUPTING CHEMICAL

    EPA Science Inventory

    Triclosan is an industrial antibacterial agent commonly used in soaps, toothpaste and cleaners. The present investigation was designed to examine the endocrine modulating potential of Triclosan because its chemical structure closely resembles known non-steroidial estrogens (e.g. ...

  18. EVALUATION OF TRICLOSAN AS A POTENTIAL ENDOCRINE DISRUPTING CHEMICAL

    EPA Science Inventory

    Triclosan is an industrial antibacterial agent commonly used in soaps, toothpaste and cleaners. The present investigation was designed to examine the endocrine modulating potential of Triclosan because its chemical structure closely resembles known non-steroidial estrogens (e.g. ...

  19. Charmed mesons at finite temperature and chemical potential

    NASA Astrophysics Data System (ADS)

    Serna, Fernando E.; Krein, Gastão

    2017-03-01

    We compute the masses of the pseudoscalar mesons π+, K0 and D+ at finite temperature and baryon chemical potential. The computations are based on a symmetry-preserving Dyson-Schwinger equation treatment of a vector-vector four quark contact interaction. The results found for the temperature dependence of the meson masses are in qualitative agreement with lattice QCD data and QCD sum rules calculations. The chemical potential dependence of the masses provide a novel prediction of the present computation.

  20. Chemical potential, Gibbs-Duhem equation and quantum gases

    NASA Astrophysics Data System (ADS)

    Lee, M. Howard

    2017-05-01

    Thermodynamic relations like the Gibbs-Duhem are valid from the lowest to the highest temperatures. But they cannot by themselves provide any specific temperature behavior of thermodynamic functions like the chemical potential. In this work, we show that if some general conditions are attached to the Gibbs-Duhem equation, it is possible to obtain the low temperature form of the chemical potential for the ideal Fermi and Bose gases very directly.

  1. Chemical potential and reaction electronic flux in symmetry controlled reactions.

    PubMed

    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.

  2. Persistence and transport potential of chemicals in a multimedia environment

    SciTech Connect

    van de Meent, D.; McKone, T.E.; Parkerton, T.; Matthies, M.; Scheringer, M.; Wania, F.; Purdy, R.; Bennett, D.H.

    2000-02-01

    Persistence in the environment and potential for long-range transport are related since time in the environment is required for transport. A persistent chemical will travel longer distances than a reactive chemical that shares similar chemical properties. Scheringer (1997) has demonstrated the correlation between persistence and transport distance for different organic chemicals. However, this correlation is not sufficiently robust to predict one property from the other. Specific chemicals that are persistent mayor may not exhibit long-range transport potential. Persistence and long-range transport also present different societal concerns. Persistence concerns relate to the undesired possibility that chemicals produced and used now may somehow negatively affect future generations. Long-range transport concerns relate to the undesired presence of chemicals in areas where these compounds have not been used. Environmental policy decisions can be based on either or both considerations depending on the aim of the regulatory program. In this chapter, definitions and methods for quantifying persistence and transport potential of organic chemicals are proposed which will assist in the development of sound regulatory frameworks.

  3. Unusual isospin-breaking and isospin-mixing effects in the A=35 mirror nuclei.

    PubMed

    Ekman, J; Rudolph, D; Fahlander, C; Zuker, A P; Bentley, M A; Lenzi, S M; Andreoiu, C; Axiotis, M; de Angelis, G; Farnea, E; Gadea, A; Kröll, Th; Mărginean, N; Martinez, T; Mineva, M N; Rossi-Alvarez, C; Ur, C A

    2004-04-02

    Excited states have been studied in 35Ar following the 16O(24Mg,1alpha1n)35Ar fusion-evaporation reaction at 60 MeV using the Ge-detector array GASP. A comparison with the mirror nucleus 35Cl shows two remarkable features: (i) A surprisingly large energy difference for the 13/2(-) states, in which the hitherto overlooked electromagnetic spin-orbit term is shown to play a major role, and (ii) a very different decay pattern for the 7/2(-) states, which provides direct evidence of isospin mixing.

  4. Unusual Isospin-Breaking and Isospin-Mixing Effects in the A=35 Mirror Nuclei

    NASA Astrophysics Data System (ADS)

    Ekman, J.; Rudolph, D.; Fahlander, C.; Zuker, A. P.; Bentley, M. A.; Lenzi, S. M.; Andreoiu, C.; Axiotis, M.; de Angelis, G.; Farnea, E.; Gadea, A.; Kröll, Th.; Mărginean, N.; Martinez, T.; Mineva, M. N.; Rossi-Alvarez, C.; Ur, C. A.

    2004-04-01

    Excited states have been studied in 35Ar following the 16O(24Mg,1α1n)35Ar fusion-evaporation reaction at 60MeV using the Ge-detector array GASP. A comparison with the mirror nucleus 35Cl shows two remarkable features: (i)A surprisingly large energy difference for the 13/2- states, in which the hitherto overlooked electromagnetic spin-orbit term is shown to play a major role, and (ii)a very different decay pattern for the 7/2- states, which provides direct evidence of isospin mixing.

  5. Isospin asymmetry dependence of the α spectroscopic factor for heavy nuclei

    NASA Astrophysics Data System (ADS)

    Seif, W. M.; Shalaby, M.; Alrakshy, M. F.

    2011-12-01

    Both the valence nucleons (holes) and the isospin asymmetry dependencies of the preformation probability of an α-cluster inside parents radioactive nuclei are investigated. The calculations are employed in the framework of the density-dependent cluster model of an α-decay process for the even-even spherical parents nuclei with protons number around the closed shell Z0 = 82 and neutrons number around the closed shells Z0 = 82 and Z0 = 126. The microscopic α-daughter nuclear interaction potential is calculated in the framework of the Hamiltonian energy density approach based on the SLy4 Skyrme-like effective interaction. Also, the calculations based on the realistic effective M3Y-Paris nucleon-nucleon force have been used to confirm the results. The calculations then proceed to find the assault frequency and the α penetration probability within the WKB approximation. The half-lives of the different mentioned α decays are then determined and have been used in turn to find the α spectroscopic factor. We found that the spectroscopic factor increases with increasing the isospin asymmetry of the parent nuclei if they have valence protons and neutrons. When the parent nuclei have neutron or proton holes in addition to the valence protons or neutrons, then the spectroscopic factor is found to decrease with increasing isospin asymmetry. The obtained results show also that the deduced spectroscopic factors follow individual linear behaviors as a function of the multiplication of the valence proton (Np) and neutron (Nn) numbers. These linear dependencies are correlated with the closed shells core (Z0,N0). The same individual linear behaviors are obtained as a function of the multiplication of NpNn and the isospin asymmetry parameter, NpNnI. Moreover, the whole deduced spectroscopic factors are found to exhibit a nearly general linear trend with the function NpNn/(Z0+N0).

  6. Isospin and particle representations for quasi-bound state of kaonic clusters

    NASA Astrophysics Data System (ADS)

    Filikhin, Igor; Kezerashvili, Roman; Vlahovic, Branislav

    2017-01-01

    In the framework of the method of the Faddeev equations in configuration space, the NNK (I = 0) (and KK) kaonic cluster system including two identical particles is considered. We use the formalism of isospin and particle representations to describe the systems. The treatment of I = 1 and I = 0 isospin KN channels is discussed. The presence of the Coulomb force in ppK- channel violates the isospin symmetry of the NNK (I = 0) system. According to the particle representation, NNK is a two-level system of coupled ppK- and ppnl channels with and without the Coulomb energy, respectively. The results of calculations for the bound states with the phenomenological and chiral motivated KN potentials are given for different representations. In particular, new single channel calculations for the ppK- (and K-K- p) cluster are presented. It is shown that the exchange of identical particles plays an important role in the formation of a bound state of the systems. The relation of the exchange and the three-body mass rearrangement effects is discussed. This work is supported by the National Science Foundation grant Supplement to the NSF grant HRD-1345219 and NASA (NNX09AV07A).

  7. Isospin of topological defects in Dirac systems

    NASA Astrophysics Data System (ADS)

    Herbut, Igor F.

    2012-02-01

    We study the Dirac quasiparticles in d-dimensional lattice systems of electrons in the presence of domain walls (d=1), vortices (d=2), or hedgehogs (d=3) of superconducting and/or insulating, order parameters, which appear as mass terms in the Dirac equation. Such topological defects have been known to carry nontrivial quantum numbers, such as charge and spin. Here we discuss their additional internal degree of freedom: irrespective of the dimensionality of space and the nature of orders that support the defect, an extra mass order parameter is found to emerge in their core. Six linearly independent local orders, which close two mutually commuting three-dimensional Clifford algebras, are proven to be in general possible. We show how the particle-hole symmetry restricts the defects to always carry the quantum numbers of a single effective isospin 1/2, quite independently of the values of their electric charge or true spin. Examples of this new degree of freedom in graphene and on surfaces of topological insulators are discussed.

  8. In vitro screening for potential chemical inhibitors of ...

    EPA Pesticide Factsheets

    Control of thyroid hormone (TH) signaling in vertebrates is dependent upon multiple key events including iodide uptake, hormone synthesis, metabolism and elimination, to maintain proper homeostasis of the hormones. Deiodinase enzymes interconvert THs between less active and more active forms via release of iodide from the substrate hormones. The activity of deiodinases has been identified as an important endpoint to include in the context of screening chemicals for thyroid hormone disruption. To address the lack of data regarding the potential for chemicals to inhibit these enzymes a research effort was initially focused on human deiodinase type 1 (D1). We utilized an adenovirus expression system for production of D1 enzyme, established robust assay parameters for non-radioactive determination of iodide release by the Sandell-Kolthoff method, and employed a 96-well plate format for screening chemical libraries. An initial set of 19 chemicals was used to establish the assay. Included in this set was the known D1 inhibitor 6-propylthiouracil (used as a positive control). Over 1800 unique chemicals primarily from the EPA’s ToxCast phase 1_v2, phase 2, and e1K chemical libraries were tested in the screening assay. Chemicals were initially screened at a single high concentration of 200 µM to identify potential D1 inhibitors. The majority of the chemicals did not inhibit D1 activity in this initial screen as defined as a response of less than 20% inhibition c

  9. In vitro screening for potential chemical inhibitors of ...

    EPA Pesticide Factsheets

    Control of thyroid hormone (TH) signaling in vertebrates is dependent upon multiple key events including iodide uptake, hormone synthesis, metabolism and elimination, to maintain proper homeostasis of the hormones. Deiodinase enzymes interconvert THs between less active and more active forms via release of iodide from the substrate hormones. The activity of deiodinases has been identified as an important endpoint to include in the context of screening chemicals for thyroid hormone disruption. To address the lack of data regarding the potential for chemicals to inhibit these enzymes a research effort was initially focused on human deiodinase type 1 (D1). We utilized an adenovirus expression system for production of D1 enzyme, established robust assay parameters for non-radioactive determination of iodide release by the Sandell-Kolthoff method, and employed a 96-well plate format for screening chemical libraries. An initial set of 19 chemicals was used to establish the assay. Included in this set was the known D1 inhibitor 6-propylthiouracil (used as a positive control). Over 1800 unique chemicals primarily from the EPA’s ToxCast phase 1_v2, phase 2, and e1K chemical libraries were tested in the screening assay. Chemicals were initially screened at a single high concentration of 200 µM to identify potential D1 inhibitors. The majority of the chemicals did not inhibit D1 activity in this initial screen as defined as a response of less than 20% inhibition c

  10. Potential Impacts of Spilled Hydraulic Fracturing Fluid Chemicals on Water Resources: Types, Volumes, and Physical-chemical Properties of Chemicals

    NASA Astrophysics Data System (ADS)

    Knightes, C. D.; Daiss, R.; Williams, L.; Singer, A.

    2015-12-01

    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 fluid, proppant, and additives. Additives, comprised of one or more chemicals, are serve a specific engineering purpose (e.g., friction reducer, scale inhibitor, biocide). As part of the USEPA's Draft Assessment of the Potential Impacts of Hydraulic Fracturing for Oil and Gas on Drinking Water Resources, we investigated the different types, volumes injected, and physical-chemical properties of HF fluid chemicals. The USEPA identified 1,076 chemicals used in HF fluids, based on 10 sources covering chemical use from 2005 to 2013. These chemicals fall into different classes: acids, alcohols, aromatic hydrocarbons, bases, hydrocarbon mixtures, polysaccharides, and surfactants. The physical-chemical properties of these chemicals vary, which affects their movement through the environment if spilled. Properties range from fully miscible to insoluble, from highly hydrophobic to highly hydrophilic. Most of these chemicals are not volatile. HF fluid composition varies from site to site depending on a range of factors. No single chemical or set of chemicals are used at every site. A median of 14 chemicals are used per well, with a range of four to 28 (5th and 95th percentiles). Methanol was the chemical most commonly reported in FracFocus 1.0 (72% of disclosures), and hydrotreated light petroleum distillates and hydrochloric acid were both reported in over half the disclosures. Operators store chemicals on-site, often in multiple containers (typically in 760 to 1,500 L totes). We estimated that the total volume of all chemicals used per well ranges from approximately 10,000 to 110,000 L. The views expressed here are those of the authors and do not necessarily represent the views or policies of the USEPA.

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

    PubMed

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

    2015-10-21

    We extend the definition of the electronic chemical potential (μe) and chemical hardness (ηe) 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, μe. 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.

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

    SciTech Connect

    Franco-Pérez, Marco E-mail: jlgm@xanum.uam.mx; Gázquez, José L. E-mail: jlgm@xanum.uam.mx; Ayers, Paul W.; Vela, Alberto

    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.

  13. Isospin symmetry breaking in the chiral quark model

    NASA Astrophysics Data System (ADS)

    Song, Huiying; Zhang, Xinyu; Ma, Bo-Qiang

    2010-12-01

    We discuss the isospin symmetry breaking (ISB) of the valence- and sea-quark distributions between the proton and the neutron in the framework of the chiral quark model. We assume that isospin symmetry breaking is the result of mass differences between isospin multiplets and then analyze the effects of isospin symmetry breaking on the Gottfried sum rule and the NuTeV anomaly. We show that, although both flavor asymmetry in the nucleon sea and the ISB between the proton and the neutron can lead to the violation of the Gottfried sum rule, the main contribution is from the flavor asymmetry in the framework of the chiral quark model. We also find that the correction to the NuTeV anomaly is in an opposite direction, so the NuTeV anomaly cannot be removed by isospin symmetry breaking in the chiral quark model. It is remarkable that our results of ISB for both valence- and sea-quark distributions are consistent with the Martin-Roberts-Stirling-Thorne parametrization of quark distributions.

  14. Catalysis of dynamical chiral symmetry breaking by chiral chemical potential

    NASA Astrophysics Data System (ADS)

    Braguta, V. V.; Kotov, A. Yu.

    2016-05-01

    In this paper, we study the properties of media with chiral imbalance parametrized by chiral chemical potential. It is shown that depending on the strength of interaction between constituents in the media the chiral chemical potential either creates or enhances dynamical chiral symmetry breaking. Thus, the chiral chemical potential plays the role of the catalyst of dynamical chiral symmetry breaking. Physically, this effect results from the appearance of the Fermi surface and additional fermion states on this surface, which take part in dynamical chiral symmetry breaking. An interesting conclusion which can be drawn is that at sufficiently small temperature chiral plasma is unstable with respect to condensation of Cooper pairs and dynamical chiral symmetry breaking even for vanishingly small interactions between constituents.

  15. QCD in one dimension at nonzero chemical potential

    SciTech Connect

    Ravagli, L.; Verbaarschot, J. J. M.

    2007-09-01

    Using an integration formula recently derived by Conrey, Farmer, and Zirnbauer, we calculate the expectation value of the phase factor of the fermion determinant for the staggered lattice QCD action in one dimension. We show that the chemical potential can be absorbed into the quark masses; the theory is in the same chiral symmetry class as QCD in three dimensions at zero chemical potential. In the limit of a large number of colors and fixed number of lattice points, chiral symmetry is broken spontaneously, and our results are in agreement with expressions based on a chiral Lagrangian. In this limit, the eigenvalues of the Dirac operator are correlated according to random matrix theory for QCD in three dimensions. The discontinuity of the chiral condensate is due to an alternative to the Banks-Casher formula recently discovered for QCD in four dimensions at nonzero chemical potential. The effect of temperature on the average phase factor is discussed in a schematic random matrix model.

  16. Phase of the fermion determinant at nonzero chemical potential.

    PubMed

    Splittorff, K; Verbaarschot, J J M

    2007-01-19

    We show that in the microscopic domain of QCD (also known as the domain) at nonzero chemical potential the average phase factor of the fermion determinant is nonzero for microchemical potential. This follows from the chiral Lagrangian that describes the low-energy limit of the expectation value of the phase factor. Explicit expressions for the average phase factor are derived using a random matrix formulation of the zero momentum limit of this chiral Lagrangian.

  17. Responses of quark condensates to the chemical potential

    NASA Astrophysics Data System (ADS)

    Miyamura, O.; Choe, S.; Liu, Y.; Takaishi, T.; Nakamura, A.

    2002-10-01

    The responses of quark condensates to the chemical potential, as a function of temperature T and chemical potential μ, are calculated within the Nambu-Jona-Lasinio (NJL) model. We compare our results with those from the recent lattice QCD simulations [QCD-TARO Collaboration, S. Choe et al., Nucl. Phys. B (Proc. Suppl.) 106, 462 (2002)]. The NJL model and lattice calculations show qualitatively similar behavior, and they will be complimentary ways to study hadrons at finite density. The behavior above Tc requires more elaborated analyses.

  18. Chemical potential calculations in dense liquids using metadynamics

    NASA Astrophysics Data System (ADS)

    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.

  19. The CP(2) Model at Nonzero Chemical Potential

    NASA Astrophysics Data System (ADS)

    Evans, W.; Gerber, U.; Wiese, U. J.

    Recently the simulation of quantum field theories using man-made physical systems has become realistic. In this publication we present numerical results which support the use of quantum simulation experiments to study quantum field theories at non-zero chemical potential. We have numerically simulated the (1+1)-d $\\mathbb{C}$P(2) model, which shares several interesting features with QCD, namely asymptotic freedom, a dynamically generated mass gap and topological sectors, via dimensional reduction of a (2+1)-d microscopic theory of SU(3) quantum spins. Numerical results for the particle number density as a function of chemical potential are presented.

  20. Modulation of mechanical resonance by chemical potential oscillation in graphene

    NASA Astrophysics Data System (ADS)

    Chen, Changyao; Deshpande, Vikram V.; Koshino, Mikito; Lee, Sunwoo; Gondarenko, Alexander; MacDonald, Allan H.; Kim, Philip; Hone, James

    2016-03-01

    The classical picture of the force on a capacitor assumes a large density of electronic states, such that the electrochemical potential of charges added to the capacitor is given by the external electrostatic potential and the capacitance is determined purely by geometry. Here we consider capacitively driven motion of a nano-mechanical resonator with a low density of states, in which these assumptions can break down. We find three leading-order corrections to the classical picture: the first of which is a modulation in the static force due to variation in the internal chemical potential; the second and third are changes in the static force and dynamic spring constant due to the rate of change of chemical potential, expressed as the quantum (density of states) capacitance. As a demonstration, we study capacitively driven graphene mechanical resonators, where the chemical potential is modulated independently of the gate voltage using an applied magnetic field to manipulate the energy of electrons residing in discrete Landau levels. In these devices, we observe large periodic frequency shifts consistent with the three corrections to the classical picture. In devices with extremely low strain and disorder, the first correction term dominates and the resonant frequency closely follows the chemical potential. The theoretical model fits the data with only one adjustable parameter representing disorder-broadening of the Landau levels. The underlying electromechanical coupling mechanism is not limited by the particular choice of material, geometry, or mechanism for variation in the chemical potential, and can thus be extended to other low-dimensional systems.

  1. Estimates of isospin breaking contributions to baryon masses

    SciTech Connect

    Ha, Phuoc

    2007-10-01

    We estimate the isospin breaking contributions to the baryon masses which we analyzed recently using a loop expansion in the heavy-baryon chiral effective field theory. To one loop, the isospin breaking corrections come from the effects of the d, u quark mass difference, the Coulomb and magnetic moment interactions, and effective point interactions attributable to color-magnetic effects. The addition of the first meson loop corrections introduces new structure. We estimate the resulting low-energy, long-range contributions to the mass splittings by regularizing the loop integrals using connections to dynamical models for finite-size baryons. We find that the resulting contributions to the isospin breaking corrections are of the right general size, have the correct sign pattern, and agree with the experimental values within the margin of error.

  2. Conservation of Isospin in Neutron-rich Fission Fragments

    SciTech Connect

    Jain, A.K.; Choudhury, D.; Maheshwari, B.

    2014-06-15

    On the occasion of the 75{sup th} anniversary of the fission phenomenon, we present a surprisingly simple result which highlights the important role of isospin and its conservation in neutron rich fission fragments. We have analysed the fission fragment mass distribution from two recent heavyion reactions {sup 238}U({sup 18}O,f) and {sup 208}Pb({sup 18}O,f) as well as a thermal neutron fission reaction {sup 245}Cm(n{sup th},f). We find that the conservation of the total isospin explains the overall trend in the observed relative yields of fragment masses in each fission pair partition. The isospin values involved are very large making the effect dramatic. The findings open the way for more precise calculations of fission fragment distributions in heavy nuclei and may have far reaching consequences for the drip line nuclei, HI fusion reactions, and calculation of decay heat in the fission phenomenon.

  3. Scenario projections for future market potentials of biobased bulk chemicals.

    PubMed

    Dornburg, Veronika; Hermann, Barbara G; Patel, Martin K

    2008-04-01

    Three scenario projections for future market potentials of biobased bulk chemicals produced by means of white biotechnology are developed for Europe (EU-25) until the year 2050, and potential nonrenewable energy savings, greenhouse gas emission reduction, and land use consequences are analyzed. These scenarios assume benign, moderate, and disadvantageous conditions for biobased chemicals. The scenario analysis yields a broad range of values for the possible market development of white biotechnology chemicals, that is, resulting in a share of white biotechnology chemicals relative to all organic chemicals of about 7 (or 5 million tonnes), 17.5 (or 26 million tonnes), or 38% (or 113 million tonnes) in 2050. We conclude that under favorable conditions, white biotechnology enables substantial savings of nonrenewable energy use (NREU) and greenhouse gas (GHG) emissions compared to the energy use of the future production of all organic chemicals from fossil resources. Savings of NREU reach up to 17% for starch crops and up to 31% for lignocellulosic feedstock by 2050, and saving percentages for GHG emissions are in a similar range. Parallel to these environmental benefits, economic advantages of up to 75 billion Euro production cost savings arise.

  4. Toxicological procedures for assessing the carcinogenic potential of agricultural chemicals.

    PubMed

    Krewski, D; Clayson, D; Collins, B; Munro, I C

    1982-01-01

    Pesticides and other agricultural chemicals are now widely used throughout the world as a means of improving crop yields in order to meet the increasing demands being placed upon the global food supply. In Canada, the use of such chemicals is controlled through government regulations established jointly by the Department of Agriculture and the Department of National Health & Welfare. Such regulations require a detailed evaluation of the toxicological characteristics of the chemical prior to its being cleared for use. In this paper, procedures for assessing the carcinogenic potential of agricultural and other chemicals are discussed. Consideration is given to both the classical long-term in vivo carcinogen bioassay in rodent or other species and the more recently developed short-term in vitro tests based on genetic alterations in bacterial and other test systems.

  5. A multivariate chemical map of industrial chemicals--assessment of various protocols for identification of chemicals of potential concern.

    PubMed

    Stenberg, Mia; Linusson, Anna; Tysklind, Mats; Andersson, Patrik L

    2009-08-01

    In present study the Industrial chemical map was created, and investigated. Molecular descriptors were calculated for 56072 organic substances from the European inventory of existing commercial chemical substances (EINECS). The resulting multivariate dataset was subjected to principal component analysis (PCA), giving five principal components, mainly reflecting size, hydrophobicity, flexibility, halogenation and electronical properties. It is these five PCs that form the basis of the map of organic, industrial chemicals, the Industrial chemical map. The similarities and diversity in chemical characteristics of the substances in relation to their persistence (P), bioaccumulation (B) and long-range transport potential were then examined, by superimposing five sets of entries obtained from other relevant databases onto the Industrial chemical map. These sets displayed very similar diversity patterns in the map, although with a spread in all five PC vectors. Substances listed by the United Nations Environment Program as persistent organic pollutants (UNEP POPs) were on the other hand clearly grouped with respect to each of the five PCs. Illustrating similarities and differences in chemical properties are one of the strengths of the multivariate data analysis method, and to be able to make predictions of, and investigate new chemicals. Further, the results demonstrate that non-testing methods as read-across, based on molecular similarities, can reduce the requirements to test industrial chemicals, provided that they are applied carefully, in combination with sound chemical knowledge.

  6. Synthetic Chemicals with Potential for Natural Attenuation (Postprint)

    DTIC Science & Technology

    2012-07-01

    1273. Synthetic Chemicals with Potential for Natural Attenuation (_ Suflita, J. M. and G. T. Townsend. 1995. "The microbial ecology and physiology...of the microbial community. Therefore, the process can be self- sustaining and is limited only by the presence of electron acceptors or inorganic...Hydrocarbons Figure 1. Contaminant-microbe interactions . When microorganisms encounter organic contaminants, several responses are possible. Both

  7. Response of quark condensate to the chemical potential

    SciTech Connect

    Jiang Yu; Zhang Yanbin; Sun Weimin; Zong Hongshi

    2008-07-01

    In this paper we propose a new method for calculating the response of the quark condensate to the chemical potential. Based on the method of calculating the dressed-quark propagator at finite chemical potential in the framework of the rainbow-ladder approximation of the Dyson-Schwinger approach proposed in [H. S. Zong, L. Chang, F. Y. Hou, W. M. Sun, and Y. X. Liu, Phys. Rev. C 71, 015205 (2005).] and adopting the meromorphic form of the quark propagator given in [R. Alkofer, W. Detmold, C. S. Fischer, and P. Maris, Phys. Rev. D 70, 014014 (2004).][M. S. Bhagwat, M. A. Pichowsky, and P. C. Tandy, Phys. Rev. D 67, 054019 (2003).], the quark condensate at finite chemical potential [{mu}] is calculated analytically. The obtained expression for [{mu}] is real, which is different from the results in the previous literature. In addition, it is found that when the chemical potential {mu} is less than a critical one [{mu}] is kept unchanged from its vacuum value. A comparison is made between this behavior of the quark condensate and those reported in the previous literatures.

  8. Response of quark condensate to the chemical potential

    NASA Astrophysics Data System (ADS)

    Jiang, Yu; Zhang, Yan-Bin; Sun, Wei-Min; Zong, Hong-Shi

    2008-07-01

    In this paper we propose a new method for calculating the response of the quark condensate to the chemical potential. Based on the method of calculating the dressed-quark propagator at finite chemical potential in the framework of the rainbow-ladder approximation of the Dyson-Schwinger approach proposed in [H. S. Zong, L. Chang, F. Y. Hou, W. M. Sun, and Y. X. Liu, Phys. Rev. C 71, 015205 (2005).PRVCAN0556-281310.1103/PhysRevC.71.015205] and adopting the meromorphic form of the quark propagator given in [R. Alkofer, W. Detmold, C. S. Fischer, and P. Maris, Phys. Rev. D 70, 014014 (2004).PRVDAQ0556-282110.1103/PhysRevD.70.014014][M. S. Bhagwat, M. A. Pichowsky, and P. C. Tandy, Phys. Rev. D 67, 054019 (2003).PRVDAQ0556-282110.1103/PhysRevD.67.054019], the quark condensate at finite chemical potential ⟨ qmacr q⟩[μ] is calculated analytically. The obtained expression for ⟨ qmacr q⟩[μ] is real, which is different from the results in the previous literature. In addition, it is found that when the chemical potential μ is less than a critical one ⟨ qmacr q⟩[μ] is kept unchanged from its vacuum value. A comparison is made between this behavior of the quark condensate and those reported in the previous literatures.

  9. Chemical potential and dimensions of chain molecules in athermal environments

    NASA Astrophysics Data System (ADS)

    Escobedo, Fernando A.

    A recently developed method for the simulation of chemical potentials of chain molecules (EVALENCH) is applied here to obtain the chemical potential, the mean square end-to-end distance (R2n) and the mean square radius of gyration (R2g) of dilute chains in different athermal media. The environments considered in this work are a frozen network structure, a deformable network matrix and a monomeric solvent at various densities. The properties of all chain lengths smaller than a preset maximum are calculated in a single simulation. A novel method is also presented for locating and computing the fraction of sampling space available to append one segment of an existing chain. This method enhances the range of densities where simulations of chemical potential are feasible. Simulated chemical potentials are compared with the predictions of two theories; good agreement is found in both cases. We find that R2n and R2g are reduced as the density of the medium is increased (network or solvent), while they are increased when the network is frozen and as the monomeric solvent size is made larger than that of the chain sites. At the conditions studied here, no direct evidence of chain collapse is observed.

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

    PubMed

    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.

  11. Potential Health Effects Associated with Dermal Exposure to Occupational Chemicals

    PubMed Central

    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. PMID:25574139

  12. Molecular dynamics simulations of solutions at constant chemical potential

    NASA Astrophysics Data System (ADS)

    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.

  13. On the splitting of nucleon effective masses at high isospin density: reaction observables

    SciTech Connect

    Di Toro, M.; Colonna, M.; Rizzo, J.

    2005-10-14

    We review the present status of the nucleon effective mass splitting puzzle in asymmetric matter, with controversial predictions within both non-relativistic and relativistic approaches to the effective in medium interactions. Based on microscopic transport rimulations we suggest some rather sensitive observables in collisions of asymmetric (unstable) ions at intermediate (RIA) energies: i) Energy systematics of Lane Potentials; ii) Isospin content of fast emitted nucleons; iii) Differential Collective Flows. Similar measurements for light isobars (like 3H-3He) could be also important.

  14. Microscopy of chemical-potential variations on an atomic scale

    NASA Astrophysics Data System (ADS)

    Williams, C. C.; Wickramasinghe, H. K.

    1990-03-01

    THE invention of the scanning tunnelling microscope1 (STM) has stimulated the development of several new forms of probe microscopy2-10. Here we demonstrate the use of a microscope that is capable of measuring chemical-potential variations on an atomic scale-the scanning chemical potential microscope (SCPM). The system is based on a recently developed tunnelling thermometer11, which allows the spatial mapping, on an atomic scale, of thermoelectric potential variations resulting from absorption of light, by scanning a conducting tip within tunnelling range of a conducting (or semiconducting) sample. In the SCPM, we replace the optical pump with an electrical sample heater, to generate a temperature gradient between the sample and the tunnel-current-measuring device. We measure the spatial variations in the thermoelectric voltage across the tip-sample system as the tip is scanned across the sample surface with no external bias. This signal can be shown to be equal to the product of the local gradient of chemical potential with respect to temperature and the temperature differential normal to the surface being imaged. The images obtained in this way show features that are not present in the conventional STM images.

  15. Chemical potential in the first law for holographic entanglement entropy

    NASA Astrophysics Data System (ADS)

    Kastor, David; Ray, Sourya; Traschen, Jennie

    2014-11-01

    Entanglement entropy in conformal field theories is known to satisfy a first law. For spherical entangling surfaces, this has been shown to follow via the AdS/CFT correspondence and the holographic prescription for entanglement entropy from the bulk first law for Killing horizons. The bulk first law can be extended to include variations in the cosmological constant Λ, which we established in earlier work. Here we show that this implies an extension of the boundary first law to include varying the number of degrees of freedom of the boundary CFT. The thermodynamic potential conjugate to Λ in the bulk is called the thermodynamic volume and has a simple geometric formula. In the boundary first law it plays the role of a chemical potential. For the bulk minimal surface Σ corresponding to a boundary sphere, the thermodynamic volume is found to be proportional to the area of Σ, in agreement with the variation of the known result for entanglement entropy of spheres. The dependence of the CFT chemical potential on the entanglement entropy and number of degrees of freedom is similar to how the thermodynamic chemical potential of an ideal gas depends on entropy and particle number.

  16. Spin-isospin and pairing properties of modified Skyrme interactions

    NASA Astrophysics Data System (ADS)

    Van Giai, Nguyen; Sagawa, H.

    1981-11-01

    New sets of parameters for Skyrme interactions have been determined. In addition to the ground-state properties, they give satisfactory values for the compression modulus, spin and spin-isospin Landau parameters, and pairing matrix elements. Gamow-Teller states are calculated and compared with experimental data.

  17. POTLIB 2001: A potential energy surface library for chemical systems

    NASA Astrophysics Data System (ADS)

    Duchovic, Ronald J.; Volobuev, Yuri L.; Lynch, Gillian C.; Truhlar, Donald G.; Allison, Thomas C.; Wagner, Albert F.; Garrett, Bruce C.; Corchado, Jose C.

    2002-04-01

    POTLIB 2001 is a computer program library of global chemical potential energy surface (PES) functions (91 functions in version 1.0) along with test data, a suite of utility programs, and a convenient user interface. The PES programs are written in ANSI standard FORTRAN77 and can be used to determine the Born-Oppenheimer potential energy of chemical systems as a function of the internal coordinates. The accompanying test data allow users to verify local implementations of this library. Finally, the utility programs permit use of this library in conjunction with a variety of chemical dynamics and chemical kinetics computer codes. Interface routines are provided for the POLYRATE and ABCRATE program packages of Truhlar and co-workers, the VENUS96 program package of Hase and co-workers, and the VARIFLEX program package of Klippenstein and co-workers; the routines in this library can also be used in conjunction with the DYNASOL program package of Zhang and co-workers. This article describes the library and the utility programs and outlines the systematic conventions used for interfaces in the computer programs contained in the library. Adherence to these conventions will allow future PESs to be compatible with this library.

  18. Lubricant base stock potential of chemically modified vegetable oils.

    PubMed

    Erhan, Sevim Z; Sharma, Brajendra K; Liu, Zengshe; Adhvaryu, Atanu

    2008-10-08

    The environment must be protected against pollution caused by lubricants based on petroleum oils. The pollution problem is so severe that approximately 50% of all lubricants sold worldwide end up in the environment via volatility, spills, or total loss applications. This threat to the environment can be avoided by either preventing undesirable losses, reclaiming and recycling mineral oil lubricants, or using environmentally friendly lubricants. Vegetable oils are recognized as rapidly biodegradable and are thus promising candidates as base fluids in environment friendly lubricants. Lubricants based on vegetable oils display excellent tribological properties, high viscosity indices, and flash points. To compete with mineral-oil-based lubricants, some of their inherent disadvantages, such as poor oxidation and low-temperature stability, must be corrected. One way to address these problems is chemical modification of vegetable oils at the sites of unsaturation. After a one-step chemical modification, the chemically modified soybean oil derivatives were studied for thermo-oxidative stability using pressurized differential scanning calorimetry and a thin-film micro-oxidation test, low-temperature fluid properties using pour-point measurements, and friction-wear properties using four-ball and ball-on-disk configurations. The lubricants formulated with chemically modified soybean oil derivatives exhibit superior low-temperature flow properties, improved thermo-oxidative stability, and better friction and wear properties. The chemically modified soybean oil derivatives having diester substitution at the sites of unsaturation have potential in the formulation of industrial lubricants.

  19. QCD phase diagram with a chiral chemical potential

    NASA Astrophysics Data System (ADS)

    Lu, Ya; Cui, Zhu-Fang; Pan, Zan; Chang, Chao-Hsi; Zong, Hong-Shi

    2016-04-01

    The effect of chirality imbalance on the QCD phase diagram is studied within the two flavors Nambu-Jona-Lasinio model. We focus especially on the issues related to how the chiral chemical potential (μ5 ) affects the phase diagram, and find the "chiral catalysis" as well as "inverse chiral catalysis" effects, which are analogous to the magnetic catalysis and inverse magnetic catalysis effects. Furthermore, our results are different from the existing chiral model calculations, namely, there is no CEP5 on the T -μ5 plane, since the whole phase transition is a crossover. In addition, with the introduction of the chiral chemical potential, various QCD susceptibilities and the corresponding critical exponents are also studied.

  20. Role of chemical potential in relaxation of faceted crystal structure

    NASA Astrophysics Data System (ADS)

    Schneider, Joshua P.; Nakamura, Kanna; Margetis, Dionisios

    2014-06-01

    Below the roughening transition, crystal surfaces have macroscopic plateaus, facets, whose evolution is driven by the microscale dynamics of steps. A long-standing puzzle was how to reconcile discrete effects in facet motion with fully continuum approaches. We propose a resolution of this issue via connecting, through a jump condition, the continuum-scale surface chemical potential away from the facet, characterized by variations of the continuum surface free energy, with a chemical potential originating from the decay of atomic steps on top of the facet. The proposed condition accounts for step flow inside a discrete boundary layer near the facet. To validate this approach, we implement in a radial geometry a hybrid discrete-continuum scheme in which the continuum theory is coupled with only a few, minimally three, steps in diffusion-limited kinetics with conical initial data.

  1. Relativistic second-order dissipative hydrodynamics at finite chemical potential

    NASA Astrophysics Data System (ADS)

    Jaiswal, Amaresh; Friman, Bengt; Redlich, Krzysztof

    2015-12-01

    Starting from the Boltzmann equation in the relaxation time approximation and employing a Chapman-Enskog like expansion for the distribution function close to equilibrium, we derive second-order evolution equations for the shear stress tensor and the dissipative charge current for a system of massless quarks and gluons. The transport coefficients are obtained exactly using quantum statistics for the phase space distribution functions at non-zero chemical potential. We show that, within the relaxation time approximation, the second-order evolution equations for the shear stress tensor and the dissipative charge current can be decoupled. We find that, for large values of the ratio of chemical potential to temperature, the charge conductivity is small compared to the coefficient of shear viscosity. Moreover, we show that in the relaxation-time approximation, the limiting behaviour of the ratio of heat conductivity to shear viscosity is qualitatively similar to that obtained for a strongly coupled conformal plasma.

  2. Shielding, the bulk chemical potential, and cohesion in alloys

    NASA Technical Reports Server (NTRS)

    Stern, E. A.

    1976-01-01

    It is shown that the bulk chemical potential in alloys is intimately related to the spatial dependence of the shielding cloud that results when the electronic charge rearranges itself as one atom type is replaced by another at a given site. Such a relationship fixes the relative energy scale between the alloy and its pure constituents, important in determining the stability of alloys. A correct treatment of shielding is thus essential to quantitative calculations of alloy stability. A model calculation of the bulk chemical potential and cohesion of alloys in the tight-binding approximation is presented as a numerical example. In the course of this investigation a general invariant of an integral over the shielding cloud is derived.

  3. Mapping the chemical potential landscape of a triple quantum dot

    NASA Astrophysics Data System (ADS)

    Broome, M. A.; Gorman, S. K.; Keizer, J. G.; Watson, T. F.; Hile, S. J.; Baker, W. J.; Simmons, M. Y.

    2016-08-01

    We investigate the nonequilibrium charge dynamics of a triple quantum dot and demonstrate how electron transport through these systems can give rise to nontrivial tunneling paths. Using a real-time charge sensing method, we establish tunneling pathways taken by particular electrons under well-defined electrostatic configurations. We show how these measurements map to the chemical potentials for different charge states across the system. We use a modified Hubbard Hamiltonian to describes the system dynamics and show is reproduces all experimental observations.

  4. Regenerative Chemical Biology: Current Challenges and Future Potential

    PubMed Central

    Ao, Ada; Hao, Jijun; Hong, Charles C.

    2011-01-01

    The enthusiasm surrounding the clinical potential of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) is tempered by the fact that key issues regarding their safety, efficacy, and long-term benefits have thus far been suboptimal. Small molecules can potentially relieve these problems at major junctions of stem cell biology and regenerative therapy. In this review, we will introduce recent advances in these important areas and the first-generation of small molecules used in the regenerative context. Current chemical biology studies will provide the archetype for future interdisciplinary collaborations, and improve clinical benefits of cell-based therapies. PMID:21513877

  5. Assessment of the extended Koopmans' theorem for the chemical reactivity: Accurate computations of chemical potentials, chemical hardnesses, and electrophilicity indices.

    PubMed

    Yildiz, Dilan; Bozkaya, Uğur

    2016-01-30

    The extended Koopmans' theorem (EKT) provides a straightforward way to compute ionization potentials and electron affinities from any level of theory. Although it is widely applied to ionization potentials, the EKT approach has not been applied to evaluation of the chemical reactivity. We present the first benchmarking study to investigate the performance of the EKT methods for predictions of chemical potentials (μ) (hence electronegativities), chemical hardnesses (η), and electrophilicity indices (ω). We assess the performance of the EKT approaches for post-Hartree-Fock methods, such as Møller-Plesset perturbation theory, the coupled-electron pair theory, and their orbital-optimized counterparts for the evaluation of the chemical reactivity. Especially, results of the orbital-optimized coupled-electron pair theory method (with the aug-cc-pVQZ basis set) for predictions of the chemical reactivity are very promising; the corresponding mean absolute errors are 0.16, 0.28, and 0.09 eV for μ, η, and ω, respectively.

  6. Prebiotic Potential and Chemical Composition of Seven Culinary Spice Extracts.

    PubMed

    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

  7. Isospin diffusion and equilibration for Sn+Sn collisions at E/A=35 MeV

    SciTech Connect

    Sun, Z. Y.; Tsang, M. B.; Lynch, W. G.; Danielewicz, P.; Verde, G.; Cardella, G.; De Filippo, E.; Pagano, A.; Papa, M.; Pirrone, S.; Amorini, F.; Porto, F.; Rizzo, F.; Russotto, P.; Andronenko, L.; Andronenko, M.; Chatterje, M.; Galichet, E.; Maiolino, C.; Santonocito, D.

    2010-11-15

    Equilibration and equilibration rates have been measured by colliding Sn nuclei with different isospin asymmetries at beam energies of E/A=35 MeV. Using the yields of mirror nuclei of {sup 7}Li and {sup 7}Be, we have studied the diffusion of isospin asymmetry by combining data from asymmetric {sup 112}Sn+{sup 124}Sn and {sup 124}Sn+{sup 112}Sn collisions with those from symmetric {sup 112}Sn+{sup 112}Sn and {sup 124}Sn+{sup 124}Sn collisions. We use these measurements to probe isospin equilibration in central collisions where nucleon-nucleon collisions are strongly blocked by the Pauli exclusion principle. The results are consistent with transport theoretical calculations that predict a degree of transparency in these collisions, but inconsistent with the emission of intermediate mass fragments by a single chemically equilibrated source. Comparisons with quantum molecular dynamics calculations are consistent with results obtained at higher incident energies that provide constraints on the density dependence of the symmetry energy.

  8. Mustard: a potential agent of chemical warfare and terrorism.

    PubMed

    Saladi, R N; Smith, E; Persaud, A N

    2006-01-01

    As one of the most important vesicant agents, the destructive properties of mustards on the skin, eyes and respiratory system, combined with a lack of antidote, makes them effective weapons. Such weapons are inexpensive, easily obtainable and frequently stockpiled. Sulphur mustard (mustard gas) has been used as a chemical warfare agent in at least 10 conflicts. In this article, the use of mustard as a potential agent of chemical warfare and terrorism is outlined. The dose-dependent effects of acute sulphur mustard exposure on the skin, eyes, and respiratory system are described, as well as the possible extents of injuries, the mechanisms of action and the long-term complications. Prevention and management of mustard exposure are briefly discussed. The need for awareness and preparedness in the dermatological community regarding mustard exposure is emphasized.

  9. Urinary screening for potentially genotoxic exposures in a chemical industry.

    PubMed Central

    Ahlborg, G; Bergström, B; Hogstedt, C; Einistö, P; Sorsa, M

    1985-01-01

    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. PMID:3899158

  10. Comparing Chemical Mechanisms using Tagged Ozone Production Potentials

    NASA Astrophysics Data System (ADS)

    Coates, J.; Butler, T. M.

    2013-12-01

    Tropospheric ozone (O3) is a short-lived climate forcing pollutant that is detrimental to human health and crop growth. It is produced by reactions of volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of sunlight [Atkinson,2000]. The chemistry of intermediate species formed during VOC degradation show a time dependence and impacts the amount of O3 produced by the VOC [Butler et al., 2011]. Representing the intricacies of these reactions is not viable for chemical mechanisms used in global and regional models due to the computational resources available. Thus, chemical mechanisms reduce the amount of reactions either by lumping chemical species together as a model species, reducing the number of reaction pathways or both. As different chemical mechanisms use varying reduction techniques and assumptions especially with respect to the intermediate degradation species, it is important to compare the temporal evolution of ozone production obtained from differing chemical mechanisms. In this study, chemical mechanisms are compared using Tagged Ozone Production Potentials (TOPP) [Butler et al.,2011]. TOPPs measure the effect of a VOC on the odd oxygen family (Ox), which includes O3, nitrogen dioxide (NO2) and other species whose cycling effect O3 and NO2 production. TOPP values are obtained via a boxmodel run lasting seven diurnal cycles and tagging all species produced during VOC degradation; this enables the Ox production to be attributed to the VOC. This technique enables the temporal evolution of a VOCs' Ox production to be compared between the mechanisms. Comparing the TOPP profiles of the VOCs obtained using different mechanisms shows the effect of reduction techniques implemented by the mechanism and also allows a comparison of the tropospheric chemistry represented in the mechanisms. [Atkinson,2000] Atkinson, R. (2000). Atmospheric chemistry of VOCs and NOx. Atmospheric Environment, 34:2063-2101 [Butler et al., 2011] Butler, T. M

  11. Chemical genetics and its potential in cardiac stem cell therapy.

    PubMed

    Vieira, Joaquim M; Riley, Paul R

    2013-05-01

    Over the last decade or so, intensive research in cardiac stem cell biology has led to significant discoveries towards a potential therapy for cardiovascular disease; the main cause of morbidity and mortality in humans. The major goal within the field of cardiovascular regenerative medicine is to replace lost or damaged cardiac muscle and coronaries following ischaemic disease. At present, de novo cardiomyocytes can be generated either in vitro, for cell transplantation or disease modelling using directed differentiation of embryonic stem cells or induced pluripotent stem cells, or in vivo via direct reprogramming of resident adult cardiac fibroblast or ectopic stimulation of resident cardiac stem or progenitor cells. A major bottleneck with all of these approaches is the low efficiency of cardiomyocyte differentiation alongside their relative functional immaturity. Chemical genetics, and the application of phenotypic screening with small molecule libraries, represent a means to enhance understanding of the molecular pathways controlling cardiovascular cell differentiation and, moreover, offer the potential for discovery of new drugs to invoke heart repair and regeneration. Here, we review the potential of chemical genetics in cardiac stem cell therapy, highlighting not only the major contributions to the field so far, but also the future challenges.

  12. The role of the chemical potential in the BCS theory

    NASA Astrophysics Data System (ADS)

    Anghel, Dragoş-Victor; Nemnes, George Alexandru

    2016-12-01

    We study the effect of the chemical potential on the results of the BCS theory of superconductivity. We assume that the pairing interaction is manifested between electrons of single-particle energies in an interval [ μ - ħωc , μ + ħωc ] , where μ and ωc are parameters of the model- μ need not be equal to the chemical potential of the system, denoted here by μR. The BCS results are recovered if μ =μR. If μ ≠μR the physical properties change significantly: the energy gap Δ is smaller than the BCS gap, a population imbalance appears, and the superconductor-normal metal phase transition is of the first order. The quasiparticle imbalance is an equilibrium property that appears due to the asymmetry with respect to μR of the single-particle energy interval in which the pairing potential is manifested. For μR - μ taking values in some ranges, the equation for Δ may have more than one solution at the same temperature, forming branches of solutions when Δ is plotted vs. μR - μ at fixed T. The solution with the highest energy gap, which corresponds to the BCS solution when μ =μR, ceases to exist if | μ -μR | ≥ 2Δ0 (Δ0 is the BCS gap at zero temperature). Therefore the superconductivity is conditioned by the existence of the pairing interaction and also by the value of μR - μ.

  13. Chemical genetics and its potential in cardiac stem cell therapy

    PubMed Central

    Vieira, Joaquim M; Riley, Paul R

    2013-01-01

    Over the last decade or so, intensive research in cardiac stem cell biology has led to significant discoveries towards a potential therapy for cardiovascular disease; the main cause of morbidity and mortality in humans. The major goal within the field of cardiovascular regenerative medicine is to replace lost or damaged cardiac muscle and coronaries following ischaemic disease. At present, de novo cardiomyocytes can be generated either in vitro, for cell transplantation or disease modelling using directed differentiation of embryonic stem cells or induced pluripotent stem cells, or in vivo via direct reprogramming of resident adult cardiac fibroblast or ectopic stimulation of resident cardiac stem or progenitor cells. A major bottleneck with all of these approaches is the low efficiency of cardiomyocyte differentiation alongside their relative functional immaturity. Chemical genetics, and the application of phenotypic screening with small molecule libraries, represent a means to enhance understanding of the molecular pathways controlling cardiovascular cell differentiation and, moreover, offer the potential for discovery of new drugs to invoke heart repair and regeneration. Here, we review the potential of chemical genetics in cardiac stem cell therapy, highlighting not only the major contributions to the field so far, but also the future challenges. LINKED ARTICLES This article is part of a themed section on Regenerative Medicine and Pharmacology: A Look to the Future. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.169.issue-2 PMID:22385148

  14. Chemicals from biomass: an assessment of the potential for production of chemical feedstocks from renewable resources

    SciTech Connect

    Donaldson, T.L.; Culberson, O.L.

    1983-06-01

    This assessment of the potential for production of commodity chemicals from renewable biomass resources is based on (1) a Delphi study with 50 recognized authorities to identify key technical issues relevant to production of chemicals from biomass, and (2) a systems model based on linear programming for a commodity chemicals industry using renewable resources and coal as well as gas and petroleum-derived resources. Results from both parts of the assessment indicate that, in the absence of gas and petroleum, coal undoubtedly would be a major source of chemicals first, followed by biomass. The most attractive biomass resources are wood, agricultural residues, and sugar and starch crops. A reasonable approximation to the current product slate for the petrochemical industry could be manufactured using only renewable resources for feedstocks. Approximately 2.5 quads (10/sup 15/ Btu (1.055 x 10/sup 18/ joules)) per year of oil and gas would be released. Further use of biomass fuels in the industry could release up to an additional 1.5 quads. however, such an industry would be unprofitable under current economic conditions with existing or near-commercial technology. As fossil resources become more expensive and biotechnology becomes more efficient, the economics will be more favorable. Use of the chemicals industry model to evaluate process technologies is demonstrated. Processes are identified which have potential for significant added value to the system if process improvements can be made to improve the economics. Guidelines and recommendations for research and development programs to improve the attractiveness of chemicals from biomass are discussed.

  15. CHEMICAL HAZARD EVALUATION FOR MANAGEMENT STRATEGIES: A METHOD FOR RANKING AND SCORING CHEMICALS BY POTENTIAL HUMAN HEALTH AND ENVIRONMENTAL IMPACTS

    EPA Science Inventory

    Between 60,000 and 100,000 of the over than 8,000,000 chemicals listed by the Chemical Abstracts Services Registry are commercially produced and are potential environmental pollutants. Risk-based evaluation for these chemicals is often required to evaluate the potential impacts...

  16. CHEMICAL HAZARD EVALUATION FOR MANAGEMENT STRATEGIES: A METHOD FOR RANKING AND SCORING CHEMICALS BY POTENTIAL HUMAN HEALTH AND ENVIRONMENTAL IMPACTS

    EPA Science Inventory

    Between 60,000 and 100,000 of the over than 8,000,000 chemicals listed by the Chemical Abstracts Services Registry are commercially produced and are potential environmental pollutants. Risk-based evaluation for these chemicals is often required to evaluate the potential impacts...

  17. Harmonic expansion of the effective potential in a functional renormalization group at finite chemical potential

    NASA Astrophysics Data System (ADS)

    Barnaföldi, G. G.; Jakovác, A.; Pósfay, P.

    2017-01-01

    In this paper we propose a method to study the functional renormalization group (FRG) at finite chemical potential. The method consists of mapping the FRG equations within the Fermi surface into a differential equation defined on a rectangle with zero boundary conditions. To solve this equation we use an expansion of the potential in a harmonic basis. With this method we determined the phase diagram of a simple Yukawa-type model; as expected, the bosonic fluctuations decrease the strength of the transition.

  18. Holographic black hole engineering at finite baryon chemical potential

    NASA Astrophysics Data System (ADS)

    Rougemont, Romulo

    2017-04-01

    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.

  19. Lattice fermions at non-zero temperature and chemical potential

    NASA Astrophysics Data System (ADS)

    Bender, I.; Rothe, H. J.; Stamatescu, I. O.; Wetzel, W.

    1993-06-01

    We study the free fermion gas at finite temperature and chemical potential in the lattice regularized version proposed by Hasenfratz and Karsch and by Kogut et al. Special emphasis is placed on the identification of the particle and antiparticle contributions to the partition function. In the case of naive fermions we show that the partition function no longer separates into particle-antiparticle contributions in the way familiar from the continuum formulation. The use of Wilson fermions, on the other hand, eliminates this unpleasant feature, and leads, after subtracting the vacuum contributions, to the familiar expressions for the average energy and charge densities.

  20. Instanton-dyon liquid model. III. Finite chemical potential

    NASA Astrophysics Data System (ADS)

    Liu, Yizhuang; Shuryak, Edward; Zahed, Ismail

    2016-11-01

    We discuss an extension of the instanton-dyon liquid model that includes light quarks at finite chemical potential in the center symmetric phase. We develop the model in details for the case of S Uc(2 )×S Uf(2 ) by mapping the theory on a three-dimensional quantum effective theory. We analyze the different phases in the mean-field approximation. We extend this analysis to the general case of S Uc(Nc)×S Uf(Nf) and note that the chiral and diquark pairings are always comparable.

  1. Isospin effects on neutrons as a probe of nuclear dissipation

    SciTech Connect

    Ye, W.

    2009-03-15

    Based on a dynamical Langevin equation coupled with a statistical decay model, we calculate the excess of the precision neutron multiplicity of the heavy nuclei {sup 240}Cf, {sup 246}Cf, {sup 252}Cf, and {sup 240}U over that predicted by the standard statistical model as a function of the postsaddle dissipation strength. We find that with increasing isospin of the system, the sensitivity of the excess to the dissipation strength decreases substantially. Moreover, for {sup 240}U, this excess is no longer sensitive to the nuclear dissipation. These results suggest that, on the experimental side, to accurately obtain information of the postsaddle dissipation strength by measuring the neutron multiplicity evaporated during the fission process of heavy nuclei, it is best to populate those compound systems with low isospin.

  2. The interplay between nucleonic and nuclear spin-isospin excitations

    NASA Astrophysics Data System (ADS)

    Weise, W.

    Following a brief review of pion-nucleon coupling in relativistic quark models and the introduction of the Δ(1232) at the quark level, we develop the nuclear spin-isospin response function in a framework of nucleons and Δ‧s interacting through exchange of mesons. The spin-isospin dependent particle-hole interaction will be elaborated and various different aspects of the Landau-Migdal parameter g‧ for nucleons and Δ‧s will be discussed. We summarize the evidence for broad Δ-hole states at high excitation energies (200-400 MeV). Then the impact of the existence of such Δ-hole excitations on the quenching of Gamow-Teller and magnetic isovector spin transitions at low energy is discussed in combination with conventional nuclear mechanisms like core polarization and ground state correlations.

  3. Isospin-violating dark matter from a double portal

    SciTech Connect

    Bélanger, Geneviève; Goudelis, Andreas; Park, Jong-Chul; Pukhov, Alexander E-mail: andreas.goudelis@lapth.cnrs.fr E-mail: pukhov@lapth.cnrs.fr

    2014-02-01

    We study a simple model that can give rise to isospin-violating interactions of Dirac fermion asymmetric dark matter to protons and neutrons through the interference of a scalar and U(1)' gauge boson contribution. The model can yield a large suppression of the elastic scattering cross section off Xenon relative to Silicon thus reconciling CDMS-Si and LUX results while being compatible with LHC findings on the 126 GeV Higgs, electroweak precision tests and flavour constraints.

  4. Isospin effects in elastic proton-nucleus scattering

    NASA Astrophysics Data System (ADS)

    Chinn, C. R.; Elster, Ch.; Thaler, R. M.

    1993-05-01

    Isovector effects in proton-nucleus elastic scattering at medium energies are studied. The accuracy of the Kerman-McManus-Thaler isospin averaging procedure is found to be very good for nuclei larger than 4He. Studies of 40Ca and 208Pb suggest that the surface neutrons may be pulled in somewhat relative to the protons, although uncertainties in the detailed applicability of the present truncation of the multiple scattering treatment render firm conclusions premature.

  5. Further study of α-decay in heavy isotopic chains considering the isospin effect

    NASA Astrophysics Data System (ADS)

    Qian, Yibin; Ren, Zhongzhou

    2016-06-01

    We have enhanced the deformed density-dependent cluster model to improve the quantitative description of α-decay in heavy even-even nuclei with 84≤slant Z≤slant 92. To preliminarily introduce the isospin effect into α-decay, the neutron excess term is added in the establishment of the crucial α-core potential. The proton and neutron density distributions are respectively considered in different parameterized formulas by combining them with available experimental data of both the charge radius and the neutron skin thickness. The calculated α-decay half-lives are found to be in somewhat better agreement with the experimental data as compared with our previous results. Strikingly, it is noted that the relatively large deviation between theory and experiment, along the tail of the isotopic chain, is obviously reduced and smoother. This may indicate the necessity of considering the isospin effect in α-decay, especially for extremely neutron-rich nuclei, which appears to be essential for the extended study of heaviest nuclei as well.

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

    PubMed

    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.

  7. Strongly Interacting Matter at Finite Chemical Potential: Hybrid Model Approach

    NASA Astrophysics Data System (ADS)

    Srivastava, P. K.; Singh, C. P.

    2013-06-01

    Search for a proper and realistic equation of state (EOS) for strongly interacting matter used in the study of the QCD phase diagram still appears as a challenging problem. Recently, we constructed a hybrid model description for the quark-gluon plasma (QGP) as well as hadron gas (HG) phases where we used an excluded volume model for HG and a thermodynamically consistent quasiparticle model for the QGP phase. The hybrid model suitably describes the recent lattice results of various thermodynamical as well as transport properties of the QCD matter at zero baryon chemical potential (μB). In this paper, we extend our investigations further in obtaining the properties of QCD matter at finite value of μB and compare our results with the most recent results of lattice QCD calculation.

  8. Nonequilibrium Casimir Force with a Nonzero Chemical Potential for Photons

    NASA Astrophysics Data System (ADS)

    Chen, Kaifeng; Fan, Shanhui

    2016-12-01

    We introduce a new class of nonequilibrium Casimir forces, where the deviation from equilibrium is achieved through the use of a nonzero chemical potential of photons. Such a force can be observed when two semiconductors are brought in close proximity to each other, and when at least one of the semiconductors is subject to an external voltage. By exact numerical calculations of a sphere-plate configuration, we show that in the total force the non-equilibrium component can dominate over its equilibrium counterpart with a relatively modest external voltage, even when the sphere-plate separation is in the nanoscale. As a result, repulsion can be achieved at the nanoscale even with a relatively modest applied voltage. The results here point to a pathway that can significantly advance the quest for observing and harnessing nonequilibrium Casimir forces in solid-state systems.

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

    NASA Astrophysics Data System (ADS)

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

    2017-06-01

    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.

  10. Nonequilibrium Casimir Force with a Nonzero Chemical Potential for Photons.

    PubMed

    Chen, Kaifeng; Fan, Shanhui

    2016-12-23

    We introduce a new class of nonequilibrium Casimir forces, where the deviation from equilibrium is achieved through the use of a nonzero chemical potential of photons. Such a force can be observed when two semiconductors are brought in close proximity to each other, and when at least one of the semiconductors is subject to an external voltage. By exact numerical calculations of a sphere-plate configuration, we show that in the total force the non-equilibrium component can dominate over its equilibrium counterpart with a relatively modest external voltage, even when the sphere-plate separation is in the nanoscale. As a result, repulsion can be achieved at the nanoscale even with a relatively modest applied voltage. The results here point to a pathway that can significantly advance the quest for observing and harnessing nonequilibrium Casimir forces in solid-state systems.

  11. Isospin symmetry breaking in 93Tc and statistical properties

    NASA Astrophysics Data System (ADS)

    Åberg, S.; Heine, A.; Mitchell, G. E.; Richter, A.

    2004-09-01

    We present a statistical analysis of proton resonances in the compound nucleus 93Tc in terms of random matrix theory (RMT). The fluctuation properties of energy levels and reduced widths from data measured by Bilpuch et al. [Phys. Rev. C 9 (1974) 1589] are studied. We conclude that one T> = 9 / 2 isobaric analog state does not affect the spectral correlations of a sequence of 124 T< = 7 / 2 states, and that the observed deviations from RMT are due to unobserved levels. For the reduced widths, however, certain deviations from Porter-Thomas statistics are attributed to the effect of isospin mixing.

  12. Unified Understanding of Spin Isospin Response Functions of Nuclei

    NASA Astrophysics Data System (ADS)

    Ichimura, M.; Wakasa, T.; Sakai, H.

    2005-08-01

    Recent (p, n) and (n, p) experiments at intermediate energies provided reliable data on nuclear spin-isospin responses. We investigated them with emphasis on the contrasting phenomena of the quenching of the total strength of the Gamow-Teller transition, and the enhancement of the pionic response in the quasielasic region, in a unified theoretical framework, that is the continuum RPA with the π + ρ + g' model, incorporated with DWIA and two-step calculations. We extracted a common set of the Landau-Migdal parameters, g'NN=0.6-0.7 and g'NΔ=0.2-0.4 for both low and high momentum transfers.

  13. Isospin odd @pK scattering length [rapid communication

    NASA Astrophysics Data System (ADS)

    Schweizer, J.

    2005-10-01

    We make use of the chiral two-loop representation of the πK scattering amplitude [J. Bijnens, P. Dhonte, P. Talavera, JHEP 0405 (2004) 036] to investigate the isospin odd scattering length at next-to-next-to-leading order in the SU (3) expansion. This scattering length is protected against contributions of ms in the chiral expansion, in the sense that the corrections to the current algebra result are of order Mπ2. In view of the planned lifetime measurement on πK atoms at CERN it is important to understand the size of these corrections.

  14. Crataegus pinnatifida: chemical constituents, pharmacology, and potential applications.

    PubMed

    Wu, Jiaqi; Peng, Wei; Qin, Rongxin; Zhou, Hong

    2014-01-30

    Crataegus pinnatifida (Hawthorn) is widely distributed in China and has a long history of use as a traditional medicine. The fruit of C. pinnatifida has been used for the treatment of cardiodynia, hernia, dyspepsia, postpartum blood stasis, and hemafecia and thus increasing interest in this plant has emerged in recent years. Between 1966 and 2013, numerous articles have been published on the chemical constituents, pharmacology or pharmacologic effects and toxicology of C. pinnatifida. To review the pharmacologic advances and to discuss the potential perspective for future investigation, we have summarized the main literature findings of these publications. So far, over 150 compounds including flavonoids, triterpenoids, steroids, monoterpenoids, sesquiterpenoids, lignans, hydroxycinnamic acids, organic acids and nitrogen-containing compounds have been isolated and identified from C. pinnatifida. It has been found that these constituents and extracts of C. pinnatifida have broad pharmacological effects with low toxicity on, for example, the cardiovascular, digestive, and endocrine systems, and pathogenic microorganisms, supporting the view that C. pinnatifida has favorable therapeutic effects. Thus, although C. pinnatifida has already been widely used as pharmacological therapy, due to its various active compounds, further research is warranted to develop new drugs.

  15. Black hole phase transitions and the chemical potential

    NASA Astrophysics Data System (ADS)

    Maity, Reevu; Roy, Pratim; Sarkar, Tapobrata

    2017-02-01

    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.

  16. Molecular Spectrum Capture by Tuning the Chemical Potential of Graphene

    PubMed Central

    Cheng, Yue; Yang, Jingjing; Lu, Qiannan; Tang, Hao; Huang, Ming

    2016-01-01

    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. PMID:27240372

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

    PubMed

    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.

  18. Exposure to Chemical and Non-Chemical Stressors in Vulnerable Groups and Potential Health Impacts

    EPA Science Inventory

    Exposures to chemical stressors Understanding of the myriad non-chemical stressorsLinkages between chemical and non-chemical stressors and health and well-beingPriority research in children’s environmental health, Tribal research needs, and disproportionately impacted comm...

  19. Isospin constraints from/on B to ππ

    NASA Astrophysics Data System (ADS)

    Pivk, M.; Le Diberder, F. R.

    2005-02-01

    The Standard Model constraints on α which can be derived from the Brightarrowππ decays are revisited in some depth. As experimental inputs, the B^0rightarrowπ^ + π^-, B^ + rightarrowπ^ + π^0 decays complemented by the B^0rightarrowπ^0π^0 decays, the CP parameters S_{ππ} and C_{ππ}, and/or the value of α as determined by the global CKM fit are used. The constraints discussed here are model independent in the sense that they rely only on Isospin symmetry, following the Gronau-London proposal. A new bound on mathcal{B}^{00} and the function C_{00}(mathcal{B}^{00}) are introduced. While another bound applied to BABAR results is shown to imply that \\cos(2α_eff) is negative. The Grossman-Quinn bound is rediscussed. A close form expression is given for α as a function of the measurements. Various scenarios for the future of the isospin analysis are explored. To probe the Standard Model the (mathcal{B}^{00},C_{00}) plane is introduced.

  20. Giant Valley-Isospin Conductance Oscillations in Ballistic Graphene

    NASA Astrophysics Data System (ADS)

    Handschin, Clevin; Makk, Péter; Rickhaus, Peter; Maurand, Romain; Watanabe, Kenji; Taniguchi, Takashi; Richter, Klaus; Liu, Ming-Hao; Schönenberger, Christian

    2017-09-01

    At high magnetic fields the conductance of graphene is governed by the half-integer quantum Hall effect. By local electrostatic gating a \\textit{p-n} junction perpendicular to the graphene edges can be formed, along which quantum Hall channels co-propagate. It has been predicted by Tworzid\\l{}o and co-workers that if only the lowest Landau level is filled on both sides of the junction, the conductance is determined by the valley (isospin) polarization at the edges and by the width of the flake. This effect remained hidden so far due to scattering between the channels co-propagating along the \\textit{p-n} interface (equilibration). Here we investigate \\textit{p-n} junctions in encapsulated graphene with a movable \\textit{p-n} interface with which we are able to probe the edge-configuration of graphene flakes. We observe large quantum conductance oscillations on the order of \\si{e^2/h} which solely depend on the \\textit{p-n} junction position providing the first signature of isospin-defined conductance. Our experiments are underlined by quantum transport calculations.

  1. Chemically treated carbon black waste and its potential applications.

    PubMed

    Dong, Pengwei; Maneerung, Thawatchai; Ng, Wei Cheng; Zhen, Xu; Dai, Yanjun; Tong, Yen Wah; Ting, Yen-Peng; Koh, Shin Nuo; Wang, Chi-Hwa; Neoh, Koon Gee

    2017-01-05

    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 2M nitric acid for 1h 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 HNO3 as an absorbent for dye removal was investigated. This treated carbon black waste has high adsorption capacity (∼361.2mg dye/g carbonblack), which can be attributed to its high specific surface area (∼559m(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. 10S/cm), making it a potentially valuable source of conductive material.

  2. Neutron–proton effective mass splitting in neutron-rich matter at normal density from analyzing nucleon–nucleus scattering data within an isospin dependent optical model

    DOE PAGES

    Li, Xiao -Hua; Guo, Wen -Jun; Li, Bao -An; ...

    2015-04-01

    The neutron–proton effective mass splitting in asymmetric nucleonic matter of isospin asymmetry δ and normal density is found to be m*n-p≡(m*n – m*p)/m = (0.41 ± 0.15)δ from analyzing globally 1088 sets of reaction and angular differential cross sections of proton elastic scattering on 130 targets with beam energies from 0.783 MeV to 200 MeV, and 1161 sets of data of neutron elastic scattering on 104 targets with beam energies from 0.05 MeV to 200 MeV within an isospin dependent non-relativistic optical potential model. It sets a useful reference for testing model predictions on the momentum dependence of the nucleonmore » isovector potential necessary for understanding novel structures and reactions of rare isotopes.« less

  3. Neutron-proton effective mass splitting in neutron-rich matter at normal density from analyzing nucleon-nucleus scattering data within an isospin dependent optical model

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Hua; Guo, Wen-Jun; Li, Bao-An; Chen, Lie-Wen; Fattoyev, Farrukh J.; Newton, William G.

    2015-04-01

    The neutron-proton effective mass splitting in asymmetric nucleonic matter of isospin asymmetry δ and normal density is found to be mn-p* ≡ (mn* - mp*) / m = (0.41 ± 0.15) δ from analyzing globally 1088 sets of reaction and angular differential cross sections of proton elastic scattering on 130 targets with beam energies from 0.783 MeV to 200 MeV, and 1161 sets of data of neutron elastic scattering on 104 targets with beam energies from 0.05 MeV to 200 MeV within an isospin dependent non-relativistic optical potential model. It sets a useful reference for testing model predictions on the momentum dependence of the nucleon isovector potential necessary for understanding novel structures and reactions of rare isotopes.

  4. Hubbard pair cluster in the external fields. Studies of the chemical potential

    NASA Astrophysics Data System (ADS)

    Balcerzak, T.; Szałowski, K.

    2017-02-01

    The chemical potential of the two-site Hubbard cluster (pair) embedded in the external electric and magnetic fields is studied by exact diagonalization of the Hamiltonian. The formalism of the grand canonical ensemble is adopted. The influence of temperature, Hubbard on-site Coulombic energy U and electron concentration on the chemical potential is investigated and illustrated in figures. In particular, a discontinuous behaviour of the chemical potential (or electron concentration) in the ground state is discussed.

  5. Effect of isospin dependence of radius on transverse flow and fragmentation in isobaric pairs

    NASA Astrophysics Data System (ADS)

    Gautam, Sakshi

    2013-11-01

    We study the role of nuclear structure effects through radius in reaction dynamics via transverse flow and multifragmentation of isobaric colliding pairs. Our study reveals that isospin-dependent radius [proposed by Royer and Rousseau [Eur. Phys. J. A10.1140/epja/i2008-10745-8 42, 541 (2009)] has significant effect towards isospin effects. The collective flow behavior and fragmentation pattern of neutron-rich system with respect to neutron-deficient system is found to get reversed with isospin-dependent radius compared to that with liquid drop radius.

  6. BRIEF REPORT: Deformation effects on the isospin dependence of particle emission

    NASA Astrophysics Data System (ADS)

    Ye, W.

    2006-05-01

    The effect of deformation on the isospin dependence of particle emission for a rather neutron-deficient 178Pb system was investigated via a diffusion model. The calculated results show that deformation significantly increases neutron multiplicity and hence weakens the dependence of neutron emission on the isospin of the system. It is also shown that deformation enhances the sensitivity of neutron emission to the nuclear viscosity coefficient, and that this sensitivity is further increased with increasing deformation. This conclusion implies that due to deformation, even for the present low-isospin system, neutrons are still a good observable for the viscosity coefficient.

  7. Study of isospin nonconservation in the framework of spectral distribution theory

    NASA Astrophysics Data System (ADS)

    Kar, Kamales; Sarkar, Sukhendusekhar

    2015-05-01

    The observed isospin-symmetry breaking in light nuclei are caused not only by the Coulomb interaction but also by the isovector one- and two-body plus isotensor two- body nuclear interactions. Spectral distribution theory, which treats nuclear spectroscopy and other structural properties in a statistical framework, has been applied mostly to isospin conserving Hamiltonians. In this paper we extend that to include the nuclear interactions non-scalar in isospin and work out examples in the sd shell to calculate the linear term in the isobaric mass-multiplet equation originating from these non-isoscalar parts.

  8. Trojan Penguins and Isospin Violation in Hadronic B Decays

    SciTech Connect

    Grossman, yuval

    1999-09-10

    Some rare hadronic decays of B mesons, such as B {yields} {pi}K, are sensitive to isospin-violating contributions from physics beyond the Standard Model. Although commonly referred to as electroweak penguins, such contributions can often arise through tree-level exchanges of heavy particles, or through strong-interaction loop diagrams. The Wilson coefficients of the corresponding electroweak penguin operators are calculated in a large class of New Physics models, and in many cases are found not to be suppressed with respect to the QCD penguin coefficients. Several tests for these effects using observables in B{sup {+-}} {yields} {pi}K decays are discussed, and nontrivial bounds on the couplings of the various New Physics models are derived.

  9. Isospin properties of electric dipole excitations in 48Ca

    NASA Astrophysics Data System (ADS)

    Derya, V.; Savran, D.; Endres, J.; Harakeh, M. N.; Hergert, H.; Kelley, J. H.; Papakonstantinou, P.; Pietralla, N.; Ponomarev, V. Yu.; Roth, R.; Rusev, G.; Tonchev, A. P.; Tornow, W.; Wörtche, H. J.; Zilges, A.

    2014-03-01

    Two different experimental approaches were combined to study the electric dipole strength in the doubly-magic nucleus 48Ca below the neutron threshold. Real-photon scattering experiments using bremsstrahlung up to 9.9 MeV and nearly mono-energetic linearly polarized photons with energies between 6.6 and 9.51 MeV provided strength distribution and parities, and an (α,α‧γ) experiment at Eα=136 MeV gave cross sections for an isoscalar probe. The unexpected difference observed in the dipole response is compared to calculations using the first-order random-phase approximation and points to an energy-dependent isospin character. A strong isoscalar state at 7.6 MeV was identified for the first time supporting a recent theoretical prediction.

  10. Isospin-mixing correction for fp-shell Fermi transitions

    SciTech Connect

    Ormand, W.E.; Brown, B.A.

    1995-10-01

    Isospin-mixing corrections for superallowed Fermi transitions in fp-shell nuclei are computed within the framework of the shelf model. The study includes a re-evaluation of three nuclei that are part of the set of nine accurately measured transitions and five new cases that are expected to be measured in the future at radioactive-beam facilities. For the heavier fp-shell nuclei, both the configuration mixing term, {delta}{sub IM}, and the radial-overlap mis-match correction, {delta}{sub RO}, are much larger than in the case of the previous nine transitions. For the nine accurately measured transitions, excellent agreement with the CVC hypothesis is found. but the CKM matrix is found to violate the unitarity condition at the level of 3 {sigma}.

  11. Isospin splittings in baryons with two heavy quarks

    NASA Astrophysics Data System (ADS)

    Karliner, Marek; Rosner, Jonathan L.

    2017-08-01

    Isospin splittings in baryons with two heavy quarks and a u or d quark are calculated using simple methods proposed previously by the authors. The results are M (Ξcc ++)-M (Ξcc +)=1.41 ±0.1 2+0.76 MeV , M (Ξbb 0)-M (Ξbb -)=-4.78 ±0.0 6+0.03 MeV , and M (Ξbc +)-M (Ξbc 0)=-1.69 ±0.0 7+0.39 MeV , where the statistical errors reflect uncertainties in input mass splittings, and the systematic errors are associated with the choice of constituent-quark masses.

  12. Post-accelerator issues at the IsoSpin Laboratory

    SciTech Connect

    Chattopadhyay, S.; Nitschke, J.M.

    1994-05-01

    The workshop on ``Post-Accelerator Issues at the Isospin Laboratory`` was held at the Lawrence Berkeley Laboratory from October 27--29, 1993. It was sponsored by the Center for Beam Physics in the Accelerator and Fusion Research Division and the ISL Studies Group in the Nuclear Science Division. About forty scientists from around the world participated vigorously in this two and a half day workshop, (c.f. Agenda, Appendix D). Following various invited review talks from leading practitioners in the field on the first day, the workshop focussed around two working groups: (1) the Ion Source and Separators working group and (2) the Radio Frequency Quadrupoles and Linacs working group. The workshop closed with the two working groups summarizing and outlining the tasks for the future. This report documents the proceedings of the workshop and includes the invited review talks, the two summary talks from the working groups and individual contributions from the participants. It is a complete assemblage of state-of-the-art thinking on ion sources, low-{beta}, low(q/A) accelerating structures, e.g. linacs and RFQS, isobar separators, phase-space matching, cyclotrons, etc., as relevant to radioactive beam facilities and the IsoSpin Laboratory. We regret to say that while the fascinating topic of superconducting low-velocity accelerator structure was covered by Dr. K. Shepard during the workshop, we can only reproduce the copies of the transparencies of his talk in the Appendix, since no written manuscript was available at the time of publication of this report. The individual report have been catologed separately elsewhere.

  13. STICK INSECT CHEMICAL DEFENSES: POTENTIAL FOR USEFUL CHEMISTRY (ORDER PHASMATODEA)

    USDA-ARS?s Scientific Manuscript database

    Insects make up the most numerous and diverse group of organisms on the planet, yet make up one of the least explored groups of organisms in natural products research (Dossey, A. T., Nat. Prod Rep. 2010, 27, 1737–1757). For about five years our stick insect chemical defense research has led to sever...

  14. OPTIMIZING POTENTIAL GREEN REPLACEMENT CHEMICALS – BALANCING FUNCTION AND RISK

    EPA Science Inventory

    An important focus of green chemistry is the design of new chemicals that are inherently less toxic than the ones they might replace, but still retain required functional properties. A variety of methods exist to measure or model both functional and toxicity surrogates that could...

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

    EPA Science Inventory

    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...

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

    EPA Science Inventory

    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...

  17. Nonperturbative charming penguin contributions to isospin asymmetries in radiative B decays

    SciTech Connect

    Kim, Chul; Mehen, Thomas; Leibovich, Adam K.

    2008-09-01

    Recent experimental data on the radiative decays B{yields}V{gamma}, where V is a light vector meson, find small isospin violation in B{yields}K*{gamma} while isospin asymmetries in B{yields}{rho}{gamma} are of order 20%, with large uncertainties. Using soft-collinear effective theory, we calculate isospin asymmetries in these radiative B decays up to O(1/m{sub b}), also including O(v{alpha}{sub s}) contributions from nonperturbative charming penguins (NPCP). In the absence of NPCP contributions, the theoretical predictions for the asymmetries are a few percent or less. Including the NPCP can significantly increase the isospin asymmetries for both B{yields}V{gamma} modes. We also consider the effect of the NPCP on the branching ratio and CP asymmetries in B{sup {+-}}{yields}V{sup {+-}}{gamma}.

  18. Gamow-Teller strength and the spin-isospin coupling constants of the Skyrme energy functional

    NASA Astrophysics Data System (ADS)

    Bender, M.; Dobaczewski, J.; Engel, J.; Nazarewicz, W.

    2002-05-01

    We investigate the effects of the spin-isospin channel of the Skyrme energy functional on predictions for Gamow-Teller distributions and superdeformed rotational bands. We use the generalized Skyrme interaction SkO' to describe even-even ground states and then analyze the effects of time-odd spin-isospin couplings, first term by term and then together via linear regression. Some terms affect the strength and energy of the Gamow-Teller resonance in finite nuclei without altering the Landau parameter g'0 that to leading order determines spin-isospin properties of nuclear matter. Though the existing data are not sufficient to uniquely determine all the spin-isospin couplings, we are able to fit them locally. Altering these coupling constants does not change the quality with which the Skyrme functional describes rotational bands.

  19. Goodness of isospin in neutron rich systems from the fission fragment distribution

    NASA Astrophysics Data System (ADS)

    Garg, Swati; Jain, Ashok Kumar

    2017-09-01

    We present the results of our calculations for the relative yields of neutron-rich fission fragments emitted in 208Pb (18O, fission) reaction by using the concept of the conservation of isospin and compare with the experimental data. We take into account a range of isospin values allowed by the isospin algebra and assume that the fission fragments are formed in isobaric analog states. We also take into account the neutron multiplicity data for various neutron-emission channels in each partition, and use them to obtain the weight factors in calculating the yields. We then calculate the relative yields of the fission fragments. Our calculated results are able to reproduce the experimental trends reasonably well. This is the first direct evidence of the isospin conservation in neutron-rich systems and may prove a very useful tool in their studies.

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

    SciTech Connect

    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.

  1. Landau parameters of nuclear matter in the spin and spin-isospin channels

    NASA Astrophysics Data System (ADS)

    Zuo, W.; Shen, Caiwan; Lombardo, U.

    2003-03-01

    The equation of state of spin and isospin polarized nuclear matter is determined in the framework of the Brueckner theory including three-body forces. The Landau parameters in the spin and spin-isospin sectors are derived as a function of the baryonic density. The results are compared with the Gamow-Teller collective modes. The relevance of G0 and G'0 for neutron stars is shortly discussed, including the magnetic susceptibility and the neutron star cooling.

  2. Chemical potentials in three-dimensional higher spin anti-de Sitter gravity

    NASA Astrophysics Data System (ADS)

    Henneaux, Marc; Pérez, Alfredo; Tempo, David; Troncoso, Ricardo

    2013-12-01

    We indicate how to introduce chemical potentials for higher spin charges in higher spin anti-de Sitter gravity in a manner that manifestly preserves the original asymptotic W-symmetry. This is done by switching on a non-vanishing component of the connection along the temporal (thermal) circles. We first recall the procedure in the pure gravity case (no higher spin) where the only "chemical potentials" are the temperature and the chemical potential associated with the angular momentum. We then generalize to the higher spin case. We find that there is no tension with the W N or W ∞ asymptotic algebra, which is obviously unchanged by the introduction of the chemical potentials. Our argument is not perturbative in the chemical potentials.

  3. Potential for portal detection of human chemical and biological contamination

    NASA Astrophysics Data System (ADS)

    Settles, Gary S.; McGann, William J.

    2001-08-01

    The walk-through metal-detection portal is a paradigm of non-intrusive passenger screening in aviation security. Modern explosive detection portals based on this paradigm will soon appear in airports. This paper suggests that the airborne trace detection technology developed for that purpose can also be adapted to human chemical and biological contamination. The waste heat of the human body produces a rising warm-air sheath of 50-80 liters/sec known as the human thermal plume. Contained within this plume are hundreds of bioeffluents from perspiration and breath, and millions of skin flakes. Since early medicine, the airborne human scent was used in the diagnosis of disease. Recent examples also include toxicity and substance abuse, but this approach has never been quantified. The appearance of new bioeffluents or subtle changes in the steady-state may signal the onset of a chemical/biological attack. Portal sampling of the human thermal plume is suggested, followed by a pre-concentration step and the detection of the attacking agent or the early human response. The ability to detect nanogram levels of explosive trace contamination this way was already demonstrated. Key advantages of the portal approach are its rapidity and non-intrusiveness, and the advantage that it does not require the traditional bodily fluid or tissue sampling.

  4. Chemical diversity and antiviral potential in the pantropical Diospyros genus.

    PubMed

    Peyrat, Laure-Anne; Eparvier, Véronique; Eydoux, Cécilia; Guillemot, Jean-Claude; Stien, Didier; Litaudon, Marc

    2016-07-01

    A screening using a dengue replicon virus-cell-based assay was performed on 3563 ethyl acetate (EtOAc) extracts from different parts of 1500 plants. The screening led to the selection of species from the genus Diospyros (Ebenaceae), among which 25 species distributed in tropical areas showed significant inhibitory activity on dengue virus replication. A metabolic analysis was conducted from the UPLC-HRMS profiles of 33 biologically active and inactive plant extracts, and their metabolic proximity is presented in the form of a dendrogram. The results of the study showed that chemical similarity is not related to plant species or organ. Overall, metabolomic profiling allowed us to define large groups of extracts, comprising both active and inactive ones. Closely related profiles from active extracts might indicate that the common major components of these extracts were responsible for the antiviral activity, while the comparison of chemically similar active and inactive extracts, will permit to find compounds of interest. Eventually, the phytochemical investigation of Diospyros glans bark EtOAc extract afforded usnic acid and 7 known ursane- and lupane-type triterpenoids, among which 5 were found significantly active against dengue virus replication. The inhibitory potency of these compounds was also evaluated on a DENV-NS5 RNA-dependant RNA polymerase assay.

  5. Use of the bioaccumulation factor to screen chemicals for bioaccumulation potential.

    PubMed

    Costanza, Jed; Lynch, David G; Boethling, Robert S; Arnot, Jon A

    2012-10-01

    The fish bioconcentration factor (BCF), as calculated from controlled laboratory tests, is commonly used in chemical management programs to screen chemicals for bioaccumulation potential. The bioaccumulation factor (BAF), as calculated from field-caught fish, is more ecologically relevant because it accounts for dietary, respiratory, and dermal exposures. The BCFBAF™ program in the U.S. Environmental Protection Agency's Estimation Programs Interface Suite (EPI Suite™ Ver 4.10) screening-level tool includes the Arnot-Gobas quantitative structure-activity relationship model to estimate BAFs for organic chemicals in fish. Bioaccumulation factors can be greater than BCFs, suggesting that using the BAF rather than the BCF for screening bioaccumulation potential could have regulatory and resource implications for chemical assessment programs. To evaluate these potential implications, BCFBAF was used to calculate BAFs and BCFs for 6,034 U.S. high- and medium-production volume chemicals. The results indicate no change in the bioaccumulation rating for 86% of these chemicals, with 3% receiving lower and 11% receiving higher bioaccumulation ratings when using the BAF rather than the BCF. All chemicals that received higher bioaccumulation ratings had log K(OW ) values greater than 4.02, in which a chemical's BAF was more representative of field-based bioaccumulation than its BCF. Similar results were obtained for 374 new chemicals. Screening based on BAFs provides ecologically relevant results without a substantial increase in resources needed for assessments or the number of chemicals screened as being of concern for bioaccumulation potential.

  6. Chemical analysis and potential health risks of hookah charcoal.

    PubMed

    Elsayed, Yehya; Dalibalta, Sarah; 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.

  7. Molecular simulation of aqueous electrolytes: water chemical potential results and Gibbs-Duhem equation consistency tests.

    PubMed

    Moučka, Filip; Nezbeda, Ivo; Smith, William R

    2013-09-28

    This paper deals with molecular simulation of the chemical potentials in aqueous electrolyte solutions for the water solvent and its relationship to chemical potential simulation results for the electrolyte solute. We use the Gibbs-Duhem equation linking the concentration dependence of these quantities to test the thermodynamic consistency of separate calculations of each quantity. We consider aqueous NaCl solutions at ambient conditions, using the standard SPC/E force field for water and the Joung-Cheatham force field for the electrolyte. We calculate the water chemical potential using the osmotic ensemble Monte Carlo algorithm by varying the number of water molecules at a constant amount of solute. We demonstrate numerical consistency of these results in terms of the Gibbs-Duhem equation in conjunction with our previous calculations of the electrolyte chemical potential. We present the chemical potential vs molality curves for both solvent and solute in the form of appropriately chosen analytical equations fitted to the simulation data. As a byproduct, in the context of the force fields considered, we also obtain values for the Henry convention standard molar chemical potential for aqueous NaCl using molality as the concentration variable and for the chemical potential of pure SPC/E water. These values are in reasonable agreement with the experimental values.

  8. Potential use of ultrasound in chemical monitoring. Project report

    SciTech Connect

    Orzechowska, G.E.; Poziomek, E.J.

    1994-07-01

    The U.S. Environmental Protection Agency has been examining the potential of combining sonication with existing measurement technologies for monitoring specific classes of organic pollutants in water. The research specifically addressed using ultrasound (ultrasonic) processors to decompose aqueous organochlorine compounds into ions as a screening method for organochlorine pollutants in water. Anions specific to the inorganic components would be produced in sonication. Changes in ion concentrations before and after sonication would be used in monitoring for the pollutants. The success with compounds served as proof-of-principle and forms a rationale for expanding the research to other pollutant classes.

  9. Options for modeling ground water pollution potential by dissolved chemicals

    NASA Astrophysics Data System (ADS)

    Jury, William A.; Tseng, Peng-Hsiang

    A common characteristic of virtually all forms of non-point source pollutants is that they move downward through the soil under the influence of erratic and generally unsaturated water flow. As a consequence, both soil-water flow and solute-transport properties must be known to model the event on a field or larger scale. The extensive spatial variability of these properties make deterministic modeling unfeasible at this scale, necessitating some form of approximate stochastic approach that extrapolates from limited samples of properties and input parameters. There are a number of options for exercising this strategy, but most of them involve using a local-model representation that is averaged over the spatial domain in a statistical sense, by using a number of discrete one-dimensional simulations in parallel. With this strategy, the important question becomes what type of local model to use, and how complex to make it. This paper explores options for local representation in modeling the water flow regime, ranging from full simulation using the Richards flow equation, to steady flow using only the field-capacity estimate of water content. Simulations of flow and transport to ground water are run on a hypothetical field with variable climatic data and properties generated by geometric scaling theory, using data from 20 sites averaged in parallel to represent field-scale movement to ground water for a conservative and reactive chemical pulse. Although the transient-flow model is necessary to achieve accurate representation of the position of the pulse within the profile, mass loading of ground water was represented quite accurately with a simple flow regime assuming steady-state flow and uniform, water content. The field-capacity estimate was greatly out of agreement with the other methods, however.

  10. Isospin analysis of charmless B-meson decays

    NASA Astrophysics Data System (ADS)

    Charles, J.; Deschamps, O.; Descotes-Genon, S.; Niess, V.

    2017-08-01

    We discuss the determination of the CKM angle α using the non-leptonic two-body decays B→ π π , B→ ρ ρ and B→ ρ π using the latest data available. We illustrate the methods used in each case and extract the corresponding value of α . Combining all these elements, we obtain the determination α _dir={({86.2}_{-4.0}^{+4.4} \\cup {178.4}_{-5.1}^{+3.9})}°. We assess the uncertainties associated to the breakdown of the isospin hypothesis and the choice of the statistical framework in detail. We also determine the hadronic amplitudes (tree and penguin) describing the QCD dynamics involved in these decays, briefly comparing our results with theoretical expectations. For each observable of interest in the B→ π π , B→ ρ ρ and B→ ρ π systems, we perform an indirect determination based on the constraints from all the other observables available and we discuss the compatibility between indirect and direct determinations. Finally, we review the impact of future improved measurements on the determination of α.

  11. Spin-isospin responses in Nuclei via polarization measurements

    NASA Astrophysics Data System (ADS)

    Sakai, Hide

    2001-06-01

    High quality (p, n) data obtained by NTOF+NPOL2 facility at RCNP were presented. From the measurement of 90Zr(p,n) reaction at 295 MeV, the quenching value for the Gamow-Teller transition in terms of the Ikeda's sum rule of Sβ--Sβ+=3(N-Z) is derived as 0.90+/-0.05. By using this quenching value, the Landau-Migdal parameters representing short-range correlation in isospin-spin interactions are deduced as (gNN',gNΔ')=(0.6,0.2). This small gNΔ' value favors the pion condensation. The complete set of the polarization transfer coefficients, DLL', DSS', DNN', DLS' and DSL', for the (p, n) quasi-elastic scattering has been measured at 350 MeV. The spin-longitudinal cross section IDq(~RL) and the spin-transverse cross section IDp(~RT) are deduced. IDq is found to be consistent with the DWIA+RPA calculation with (gNN',gNΔ')=(0.6,0.3). This result supports strongly the existence of the pionic enhancement in nuclei. .

  12. Origins of the isospin violation of dark matter interactions

    SciTech Connect

    Gao, Xin; Kang, Zhaofeng; Li, Tianjun E-mail: zhaofengkang@gmail.com

    2013-01-01

    Light dark matter (DM) with a large DM-nucleon spin-independent scattering cross section and moreover proper isospin violation (ISV) f{sub n}/f{sub p} ≈ −0.7 may provide a way to understand the confusing DM direct detection results. Further using the stringent astrophysical and collider constraints, we systematically investigate the origin of ISV first via general operator analyses and further via specifying three types of mediators: a light Z' from chiral U(1){sub X}, an approximate spectator Higgs doublet (It can explain the W+jj anomaly simultaneously) and color triplets. In addition, although Z' from an exotic U(1){sub X} mixing with U(1){sub Y} generates only f{sub n} = 0, we can combine it with the conventional Higgs to achieve the proper ISV. As a concrete example, we propose the U(1){sub X} model where the U(1){sub X} charged light sneutrino is an inelastic DM, which dominantly annihilates to light dark states such as Z' with sub-GeV mass. The model can consistently (with other DM direct detection results) and safely interpret the recent GoGeNT annual modulation result.

  13. Fungal phytotoxins with potential herbicidal activity: chemical and biological characterization.

    PubMed

    Cimmino, Alessio; Masi, Marco; Evidente, Marco; Superchi, Stefano; Evidente, Antonio

    2015-12-19

    Covering: 2007 to 2015 Fungal phytotoxins are secondary metabolites playing an important role in the induction of disease symptoms interfering with host plant physiological processes. Although fungal pathogens represent a heavy constraint for agrarian production and for forest and environmental heritage, they can also represent an ecofriendly alternative to manage weeds. Indeed, the phytotoxins produced by weed pathogenic fungi are an efficient tool to design natural, safe bioherbicides. Their use could avoid that of synthetic pesticides causing resistance in the host plants and the long term impact of residues in agricultural products with a risk to human and animal health. The isolation and structural and biological characterization of phytotoxins produced by pathogenic fungi for weeds, including parasitic plants, are described. Structure activity relationships and mode of action studies for some phytotoxins are also reported to elucidate the herbicide potential of these promising fungal metabolites.

  14. Differentiation of chemical reaction activity of various carbon nanotubes using redox potential: Classification by physical and chemical structures

    PubMed Central

    Castranova, Vincent; Porter, Dale W.; Yanagisawa, Takashi; Saito, Naoto; Kobayashi, Shinsuke; Endo, Morinobu

    2016-01-01

    The present study systematically examined the kinetics of a hydroxyl radical scavenging reaction of various carbon nanotubes (CNTs) including double-walled and multi-walled carbon nanotubes (DWCNTs and MWCNTs), and carbon nano peapods (AuCl3@DWCNT). The theoretical model that we recently proposed based on the redox potential of CNTs was used to analyze the experimental results. The reaction kinetics for DWCNTs and thin MWCNTs agreed well with the theoretical model and was consistent with each other. On the other hand, thin and thick MWCNTs behaved differently, which was consistent with the theory. Additionally, surface morphology of CNTs substantially influenced the reaction kinetics, while the doped particles in the center hollow parts of CNTs (AuCl3@DWCNT) shifted the redox potential in a different direction. These findings make it possible to predict the chemical and biological reactivity of CNTs based on the structural and chemical nature and their influence on the redox potential. PMID:26783369

  15. Differentiation of chemical reaction activity of various carbon nanotubes using redox potential: Classification by physical and chemical structures.

    PubMed

    Tsuruoka, Shuji; Matsumoto, Hidetoshi; Castranova, Vincent; Porter, Dale W; Yanagisawa, Takashi; Saito, Naoto; Kobayashi, Shinsuke; Endo, Morinobu

    2015-12-01

    The present study systematically examined the kinetics of a hydroxyl radical scavenging reaction of various carbon nanotubes (CNTs) including double-walled and multi-walled carbon nanotubes (DWCNTs and MWCNTs), and carbon nano peapods (AuCl3@DWCNT). The theoretical model that we recently proposed based on the redox potential of CNTs was used to analyze the experimental results. The reaction kinetics for DWCNTs and thin MWCNTs agreed well with the theoretical model and was consistent with each other. On the other hand, thin and thick MWCNTs behaved differently, which was consistent with the theory. Additionally, surface morphology of CNTs substantially influenced the reaction kinetics, while the doped particles in the center hollow parts of CNTs (AuCl3@DWCNT) shifted the redox potential in a different direction. These findings make it possible to predict the chemical and biological reactivity of CNTs based on the structural and chemical nature and their influence on the redox potential.

  16. Chemical composition and methane potential of commercial food wastes.

    PubMed

    Lopez, Victoria M; De la Cruz, Florentino B; Barlaz, Morton A

    2016-10-01

    There is increasing interest in anaerobic digestion in the U.S. However, there is little information on the characterization of commercial food waste sources as well as the effect of waste particle size on methane yield. The objective of this research was to characterize four commercial food waste sources: (1) university dining hall waste, (2) waste resulting from prepared foods and leftover produce at a grocery store, (3) food waste from a hotel and convention center, and (4) food preparation waste from a restaurant. Each sample was tested in triplicate 8L batch anaerobic digesters after shredding and after shredding plus grinding. Average methane yields for the university dining, grocery store, hotel, and restaurant wastes were 363, 427, 492, and 403mL/dry g, respectively. Starch exhibited the most complete consumption and particle size did not significantly affect methane yields for any of the tested substrates. Lipids represented 59-70% of the methane potential of the fresh substrates. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. An Event-Related Potentials Study of Mental Rotation in Identifying Chemical Structural Formulas

    ERIC Educational Resources Information Center

    Huang, Chin-Fei; Liu, Chia-Ju

    2012-01-01

    The purpose of this study was to investigate how mental rotation strategies affect the identification of chemical structural formulas. This study conducted event-related potentials (ERPs) experiments. In addition to the data collected in the ERPs, a Chemical Structure Conceptual Questionnaire and interviews were also admin-istered for data…

  18. POTENTIAL INHALATION EXPOSURE TO VOLATILE CHEMICALS IN WATER-BASED HARD-SURFACE CLEANERS

    EPA Science Inventory

    Potential inhalation exposure of building occupants to volatile chemicals in water-based hard-surface cleaners was evaluated by analyzing 267 material safety data sheets (MSDSs). Among the 154 chemicals reported, 44 are volatile or semi-volatile. Hazardous air pollutants (HAPs) r...

  19. CURRENT STATE OF PREDICTING THE RESPIRATORY ALLERGY POTENTIAL OF CHEMICALS: WHAT ARE THE ISSUES?

    EPA Science Inventory

    Current State of Predicting the Respiratory Allergy Potential of Chemicals: What Are the Issues? M I. Gilmour1 and S. E. Loveless2, 1USEPA, Research Triangle Park, NC and 2DuPont Haskell Laboratory, Newark, DE.

    Many chemicals are clearly capable of eliciting immune respon...

  20. POTENTIAL INHALATION EXPOSURE TO VOLATILE CHEMICALS IN WATER-BASED HARD-SURFACE CLEANERS

    EPA Science Inventory

    Potential inhalation exposure of building occupants to volatile chemicals in water-based hard-surface cleaners was evaluated by analyzing 267 material safety data sheets (MSDSs). Among the 154 chemicals reported, 44 are volatile or semi-volatile. Hazardous air pollutants (HAPs) r...

  1. CURRENT STATE OF PREDICTING THE RESPIRATORY ALLERGY POTENTIAL OF CHEMICALS: WHAT ARE THE ISSUES?

    EPA Science Inventory

    Current State of Predicting the Respiratory Allergy Potential of Chemicals: What Are the Issues? M I. Gilmour1 and S. E. Loveless2, 1USEPA, Research Triangle Park, NC and 2DuPont Haskell Laboratory, Newark, DE.

    Many chemicals are clearly capable of eliciting immune respon...

  2. EVALUATION OF TRICLOSAN AS A POTENTIAL ENDOCRINE DISRUPTING CHEMICAL (POSTER SESSION)

    EPA Science Inventory

    Triclosan is an industrial antibacterial agent commonly used in soaps, toothpaste and cleaners. The present investigation was designed to examine the endocrine modulating potential of Triclosan because its chemical structure closely resembles known non-steroidial estrogens (e.g. ...

  3. EVALUATION OF TRICLOSAN AS A POTENTIAL ENDOCRINE DISRUPTING CHEMICAL (POSTER SESSION)

    EPA Science Inventory

    Triclosan is an industrial antibacterial agent commonly used in soaps, toothpaste and cleaners. The present investigation was designed to examine the endocrine modulating potential of Triclosan because its chemical structure closely resembles known non-steroidial estrogens (e.g. ...

  4. Potential Applicability of Assembled Chemical Weapons Assessment Technologies to RCRA Waste Streams and Contaminated Media (PDF)

    EPA Pesticide Factsheets

    This report provides an evaluation of the potential applicability of Assembled Chemical Weapons Assessment (ACWA) technologies to RCRA waste streams and contaminated media found at RCRA and Superfund sites.

  5. A Review of the Disruptive Potential of Botulinum Neurotoxins as Chemical Warfare Agents

    DTIC Science & Technology

    2011-10-01

    SUBJECT TERMS Botulinum neurotoxin, national security, chemical agents, chemical warfare, force health protection 16. SECURITY CLASSIFICATION OF: 17...the local health -care infrastructure. For anybody trained in epidemiology and crisis management, this presents a “devil’s brew” of potential...mortality rates, the potential for major public health impact, the ability to cause public panic and social disruption, and the requirement for special

  6. Prioritizing chemicals for environmental management in China based on screening of potential risks

    NASA Astrophysics Data System (ADS)

    Yu, Xiangyi; Mao, Yan; Sun, Jinye; Shen, Yingwa

    2014-03-01

    The rapid development of China's chemical industry has created increasing pressure to improve the environmental management of chemicals. To bridge the large gap between the use and safe management of chemicals, we performed a comprehensive review of the international methods used to prioritize chemicals for environmental management. By comparing domestic and foreign methods, we confirmed the presence of this gap and identified potential solutions. Based on our literature review, we developed an appropriate screening method that accounts for the unique characteristics of chemical use within China. The proposed method is based on an evaluation using nine indices of the potential hazard posed by a chemical: three environmental hazard indices (persistence, bioaccumulation, and eco-toxicity), four health hazard indices (acute toxicity, carcinogenicity, mutagenicity, and reproductive and developmental toxicity), and two environmental exposure hazard indices (chemical amount and utilization pattern). The results of our screening agree with results of previous efforts from around the world, confirming the validity of the new system. The classification method will help decisionmakers to prioritize and identify the chemicals with the highest environmental risk, thereby providing a basis for improving chemical management in China.

  7. Effective Field Theory and Isospin Violation in Few-Nucleon Systems

    SciTech Connect

    Evgeny Epelbaum

    2004-08-01

    I discuss the leading and subleading isospin--breaking three--nucleon forces in the chiral effective field theory framework. I have discussed the leading and subleading isospin-violating 3NFs. The leading contributions are generated by one- and two-pion exchange diagrams with their strength given by the strong neutron-proton mass difference. The subleading corrections are again given by one- and two-pion exchange diagrams, driven largely by the charged-to-neutral pion mass difference and also by the electromagnetic neutron-proton mass difference and the dimension two electromagnetic LEC f{sub 1}. In the future, these isospin-breaking forces should be used to analyze few-nucleon systems based on chiral EFT.

  8. Study of isospin violating phi excitation in e+e- → ωπ0

    NASA Astrophysics Data System (ADS)

    Li, Gang; Zhang, Yuan-Jiang; Zhao, Qiang

    2009-08-01

    We study the reaction e+e- → ωπ0 in the vicinity of the phi mass region. The isospin-violating phi excitation is accounted for by two major mechanisms. One is electromagnetic transition and the other is strong isospin violations. For the latter, we consider contributions from the intermediate hadronic meson loops and phi-ρ0 mixing as the major mechanisms via the t- and s-channel transitions, respectively. By fitting the recent KLOE data, we succeed in constraining the model parameters and extracting the phi → ωπ0 branching ratio. It shows that the branching ratio is sensitive to the phi excitation line shape and background contributions. Some crucial insights into the correlation between isospin violation and Okubo-Zweig-Iizuka rule evading transitions are also learned.

  9. Split Isobaric Analog State in Ni55: Case of Strong Isospin Mixing

    NASA Astrophysics Data System (ADS)

    Tripathi, Vandana; Tabor, S. L.; Volya, A.; Liddick, S. N.; Bender, P. C.; Larson, N.; Prokop, C.; Suchyta, S.; Tai, P.-L.; VonMoss, J. M.

    2013-12-01

    Study of β+ decay of the exotic Tz=-3/2 nucleus Cu55, via delayed γ rays, has revealed a strongly isospin mixed doublet (4599-4579 keV) in Ni55, which represents the fragmented and previously unknown isobaric analog of the ground state of Cu55. The observed small log ft values to both states in the doublet confirm the superallowed Fermi β decay. The near degeneracy of a pair of 3/2- levels in Ni55 results in the strong isospin mixing. The isospin mixing matrix element between the T =3/2 and T=1/2 levels is inferred from the experiment to be 9(1) keV, which agrees well with the matrix element of the charge symmetry breaking shell model Hamiltonian of Ormand and Brown. A precise value of the half-life of Cu55 at 57(3) ms was also obtained.

  10. Isospin effects on fragmentation in the asymmetric reactions induced by neutron-rich targets

    SciTech Connect

    Sharma, Arun

    2016-05-06

    To understand the isospin effects in terms of fragment’s yield in the asymmetric reactions induced by neutron-rich targets, we perform a theoretical study using isospin-dependent quantum molecular dynamics (IQMD) model. Simulations are carried out for reactions of {sup 16}O+Br{sup 80,84,92} and {sup 16}O+Ag{sup 108,113,122}. We envision that fragments’s yield in the asymmetric collisions induced by neutron-rich targets is better candidate to study isospin effects via symmetry energy and nucleon-nucleon (nn) cross-sections. Also, pronounced effects of symmetry energy and cross-sections can be found at lower and higher beam energies, respectively.

  11. Isospin transport effects in nuclear reactions at 25 MeV/nucleon

    SciTech Connect

    Lombardo, I.; Cavallaro, S.; Porto, F.; Rizzo, F.; Russotto, P.; Agodi, C.; Alba, R.; Amorini, F.; Anzalone, A.; Di Pietro, A.; Figuera, P.; Han, J.; Maiolino, C.; Santonocito, D.; Berceanu, I.; Pop, A.; Cardella, G.; De Filippo, E.; Pagano, A.; Papa, M.

    2010-07-15

    Isotopic effects are studied in reactions induced by {sup 40}Ca projectiles at 25 MeV/nucleon on {sup 40}Ca, {sup 48}Ca , and {sup 46}Ti targets. The N/Z contents of projectilelike and midvelocity (MV) sources are probed by means of isotopic ({sup 7}Li/{sup 6}Li and {sup 9}Be/{sup 7}Be) and isobaric ({sup 7}Li/{sup 7}Be) yield ratios, for semiperipheral events. In particular, information about isospin transport phenomena will be discussed. Isospin diffusion processes involving nuclei, which have noticeable differences in N/Z have been investigated. Signals of isospin drift, which are related to the gradient of density in the participant region, have also been observed for fragments emitted at MV.

  12. Towards the improvement of spin-isospin properties in nuclear energy density functionals

    NASA Astrophysics Data System (ADS)

    Roca-Maza, X.; Colò, G.; Liang, H. Z.; Meng, J.; Ring, P.; Sagawa, H.; Zhao, P. W.

    2016-06-01

    We address the problem of improving existing nuclear Energy Density Functionals (EDFs) in the spin-isospin channel. For that, we propose two different ways. The first one is to carefully take into account in the fitting protocol some of the key ground state properties for an accurate description of the most studied spin-isospin resonances: the Gamow-Teller Resonance (GTR) [1]. The second consists in providing a strategy to build local covariant EDF keeping the main features from their non-local counterparts [2]. The RHF model based on a Lagrangian where heavy mesons carry the nuclear effective interaction have been shown to be successful in the description of spin-isospin resonances [3].

  13. Benchmark values of chemical potential and chemical hardness for atoms and atomic ions (including unstable anions) from the energies of isoelectronic series.

    PubMed

    Cárdenas, Carlos; Heidar-Zadeh, Farnaz; Ayers, Paul W

    2016-09-14

    We present benchmark values for the electronic chemical potential and chemical hardness from reference data for ionization potentials and electron affinities. In cases where the energies needed to compute these quantities are not available, we estimate the ionization potential of the metastable (di)anions by extrapolation along the isoelectronic series, taking care to ensure that the extrapolated data satisfy reasonable intuitive rules to the maximum possible extent. We also propose suitable values for the chemical potential and chemical hardness of zero-electron species. Because the values we report are faithful to the trends in accurate data on atomic energies, we believe that our proposed values for the chemical potential and chemical hardness are ideally suited to conceptual studies of chemical trends across the periodic table. The critical nuclear charge (Z critical) of the isoelectronic series with 2 < N < 96 has also been reported for the first time.

  14. Comparison of Modeling Approaches to Prioritize Chemicals Based on Estimates of Exposure and Exposure Potential

    EPA Science Inventory

    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 ecologic...

  15. Comparison of Modeling Approaches to Prioritize Chemicals Based on Estimates of Exposure and Exposure Potential

    EPA Science Inventory

    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 ecologic...

  16. Isospin distillation with radial flow: A test of the nuclear symmetry energy

    SciTech Connect

    Colonna, M.; Baran, V.; Toro, M. Di; Wolter, H. H.

    2008-12-15

    We discuss mechanisms related to isospin transport in central collisions between neutron-rich systems at Fermi energies to gain information on the nuclear symmetry energy at and below saturation. A fully consistent study of the isospin distillation and expansion dynamics in two-component systems is presented in the framework of a stochastic transport theory. We analyze correlations between fragment observables, focusing on the study of the fragment asymmetry N/Z as a function of their kinetic energy. We find that the relation between these observables allows us to better characterize the fragmentation path and to access new information on the low-density behavior of the symmetry energy.

  17. Experimental validation of the largest calculated isospin-symmetry-breaking effect in a superallowed Fermi decay.

    PubMed

    Melconian, D; Triambak, S; Bordeanu, C; García, A; Hardy, J C; Iacob, V E; Nica, N; Park, H I; Tabacaru, G; Trache, L; Towner, I S; Tribble, R E; Zhai, Y

    2011-10-28

    A precision measurement of the γ yields following the β decay of (32)Cl has determined its isobaric-analogue branch to be (22.47(-0.18)(+0.21))%. Since it is an almost pure-Fermi decay, we can also determine the amount of isospin-symmetry breaking in this superallowed transition. We find a very large value, δ(C) = 5.3(9)%, in agreement with a shell-model calculation. This result sets a benchmark for isospin-symmetry-breaking calculations and lends support for similarly calculated, yet smaller, corrections that are currently applied to 0+ → 0 + transitions for tests of the standard model.

  18. Isospin-mixing corrections for {ital fp}-shell Fermi transitions

    SciTech Connect

    Ormand, W.E. |; Brown, B.A.

    1995-11-01

    Isospin-mixing corrections for superallowed Fermi transitions in {ital fp}-shell nuclei are computed within the framework of the shell model. The study includes three nuclei that are part of the set of nine accurately measured transitions as well as five cases that are expected to be measured in the future at radioactive-beam facilities. We also include some new calculations for {sup 10}C. With the isospin-mixing corrections applied to the nine accurately measured {ital ft} values, the conserved-vector-current hypothesis and the unitarity condition of the Cabbibo-Kobayashi-Maskawa matrix are tested.

  19. The influence of pairing correlations on the isospin symmetry breaking corrections of superallowed Fermi beta decays

    SciTech Connect

    Cal Latin-Small-Letter-Dotless-I k, A. E.; Gerceklioglu, M.; Selam, C.

    2013-05-15

    Within the framework of quasi-particle random phase approximation, the isospin breaking correction of superallowed 0{sup +} {yields} 0{sup +} beta decay and unitarity of Cabibbo-Kobayashi-Maskawa mixing matrix have been investigated. The broken isotopic symmetry of nuclear part of Hamiltonian has been restored by Pyatov's method. The isospin symmetry breaking correction with pairing correlations has been compared with the previous results without pairing. The effect of pairing interactions has been examined for nine superallowed Fermi beta decays; their parent nuclei are {sup 26}Al, {sup 34}Cl, {sup 38}K, {sup 42}Sc, {sup 46}V, {sup 50}Mn, {sup 54}Co, {sup 62}Ga, {sup 74}Rb.

  20. Mirror energy differences at large isospin studied through direct two-nucleon knockout.

    PubMed

    Davies, P J; Bentley, M A; Henry, T W; Simpson, E C; Gade, A; Lenzi, S M; Baugher, T; Bazin, D; Berryman, J S; Bruce, A M; Diget, C Aa; Iwasaki, H; Lemasson, A; McDaniel, S; Napoli, D R; Ratkiewicz, A; Scruton, L; Shore, A; Stroberg, R; Tostevin, J A; Weisshaar, D; Wimmer, K; Winkler, R

    2013-08-16

    The first spectroscopy of excited states in 52Ni (T(z)=-2) and 51Co (T(z)=-3/2) has been obtained using the highly selective two-neutron knockout reaction. Mirror energy differences between isobaric analogue states in these nuclei and their mirror partners are interpreted in terms of isospin nonconserving effects. A comparison between large-scale shell-model calculations and data provides the most compelling evidence to date that both electromagnetic and an additional isospin nonconserving interactions for J=2 couplings, of unknown origin, are required to obtain good agreement.

  1. Evaluation of the potential of benchmarking to facilitate the measurement of chemical persistence in lakes.

    PubMed

    Zou, Hongyan; MacLeod, Matthew; McLachlan, Michael S

    2014-01-01

    The persistence of chemicals in the environment is rarely measured in the field due to a paucity of suitable methods. Here we explore the potential of chemical benchmarking to facilitate the measurement of persistence in lake systems using a multimedia chemical fate model. The model results show that persistence in a lake can be assessed by quantifying the ratio of test chemical and benchmark chemical at as few as two locations: the point of emission and the outlet of the lake. Appropriate selection of benchmark chemicals also allows pseudo-first-order rate constants for physical removal processes such as volatilization and sediment burial to be quantified. We use the model to explore how the maximum persistence that can be measured in a particular lake depends on the partitioning properties of the test chemical of interest and the characteristics of the lake. Our model experiments demonstrate that combining benchmarking techniques with good experimental design and sensitive environmental analytical chemistry may open new opportunities for quantifying chemical persistence, particularly for relatively slowly degradable chemicals for which current methods do not perform well.

  2. Screening of chemicals for human bioaccumulative potential with a physiologically based toxicokinetic model.

    PubMed

    Tonnelier, Arnaud; Coecke, Sandra; Zaldívar, José-Manuel

    2012-03-01

    Human bioaccumulative potential is an important element in the risk assessment of chemicals. Due to the high number of synthetic chemicals, there exists the need to develop prioritisation strategies. The purpose of this study was to develop a predictive tool for human bioaccumulation risk assessment that incorporates not only the chemical properties of the compounds, but also the processes that tend to decrease the concentration of the compound such as metabolisation. We used a generic physiologically based toxicokinetic model that based on in vitro human liver metabolism data, minimal renal excretion and a constant exposure was able to assess the bioaccumulative potential of a chemical. The approach has been analysed using literature data on well-known bioaccumulative compounds and liver metabolism data from the ECVAM database and a subset of the ToxCast phase I chemical library-in total 94 compounds covering pharmaceuticals, plant protection products and industrial chemicals. Our results provide further evidence that partitioning properties do not allow for a reliable screening criteria for human chemical hazard. Our model, based on a 100% intestinal absorption assumption, suggests that metabolic clearance, plasma protein-binding properties and renal excretion are the main factors in determining whether bioaccumulation will occur and its amount. It is essential that in vitro metabolic clearance tests with metabolic competent cell lines as well as plasma protein-binding assays be performed for suspected bioaccumulative compounds.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    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 lengths. Proceeding from a linearized Boltzmann equation, we derive expressions for length scales and transport coefficients. For yttrium iron garnet (YIG) at room temperature we find that long-range transport is dominated by the magnon chemical potential. We compare the model's results with recent experiments on YIG with Pt contacts [L. J. Cornelissen et al., Nat. Phys. 11, 1022 (2015), 10.1038/nphys3465] and extract a magnon spin conductivity of σm=5 ×105 S/m. Our results for the spin Seebeck coefficient in YIG agree with published experiments. We conclude that the magnon chemical potential is an essential ingredient for energy and spin transport in magnetic insulators.

  4. The QCD deconfinement transition for heavy quarks and all baryon chemical potentials

    NASA Astrophysics Data System (ADS)

    Fromm, Michael; Langelage, Jens; Lottini, Stefano; Philipsen, Owe

    2012-01-01

    Using combined strong coupling and hopping parameter expansions, we derive an effective three-dimensional theory from thermal lattice QCD with heavy Wilson quarks. The theory depends on traced Polyakov loops only and correctly reflects the centre symmetry of the pure gauge sector as well as its breaking by finite mass quarks. It is valid up to certain orders in the lattice gauge coupling and hopping parameter, which can be systematically improved. To its current order it is controlled for lattices up to N τ ~ 6 at finite temperature. For nonzero quark chemical potentials, the effective theory has a fermionic sign problem which is mild enough to carry out simulations up to large chemical potentials. Moreover, by going to a flux representation of the partition function, the sign problem can be solved. As an application, we determine the deconfinement transition and its critical end point as a function of quark mass and all chemical potentials.

  5. Control and local measurement of the spin chemical potential in a magnetic insulator

    NASA Astrophysics Data System (ADS)

    Du, Chunhui; van der Sar, Toeno; Zhou, Tony X.; Upadhyaya, Pramey; Casola, Francesco; Zhang, Huiliang; Onbasli, Mehmet C.; Ross, Caroline A.; Walsworth, Ronald L.; Tserkovnyak, Yaroslav; Yacoby, Amir

    2017-07-01

    The spin chemical potential characterizes the tendency of spins to diffuse. Probing this quantity could provide insight into materials such as magnetic insulators and spin liquids and aid optimization of spintronic devices. Here we introduce single-spin magnetometry as a generic platform for nonperturbative, nanoscale characterization of spin chemical potentials. We experimentally realize this platform using diamond nitrogen-vacancy centers and use it to investigate magnons in a magnetic insulator, finding that the magnon chemical potential can be controlled by driving the system’s ferromagnetic resonance. We introduce a symmetry-based two-fluid theory describing the underlying magnon processes, measure the local thermomagnonic torque, and illustrate the detection sensitivity using electrically controlled spin injection. Our results pave the way for nanoscale control and imaging of spin transport in mesoscopic systems.

  6. Equation of state for five-dimensional hyperspheres from the chemical-potential route.

    PubMed

    Rohrmann, René D; Santos, Andrés

    2015-08-01

    We use the Percus-Yevick approach in the chemical-potential route to evaluate the equation of state of hard hyperspheres in five dimensions. The evaluation requires the derivation of an analytical expression for the contact value of the pair distribution function between particles of the bulk fluid and a solute particle with arbitrary size. The equation of state is compared with those obtained from the conventional virial and compressibility thermodynamic routes and the associated virial coefficients are computed. The pressure calculated from all routes is exact up to third density order, but it deviates with respect to simulation data as density increases, the compressibility and the chemical-potential routes exhibiting smaller deviations than the virial route. Accurate linear interpolations between the compressibility route and either the chemical-potential route or the virial one are constructed.

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

    PubMed Central

    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

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

    PubMed

    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.

  9. Thermodynamical vibronic coupling constant and density: Chemical potential and vibronic coupling in reactions

    NASA Astrophysics Data System (ADS)

    Sato, Tohru; Haruta, Naoki; Tanaka, Kazuyoshi

    2016-05-01

    Vibronic coupling constant (VCC) and density (VCD) defined for a pure state, which have been successfully applied for reactions of fullerenes and nanographenes as reactivity indices, are extended for a mixed state. The extended VCC and VCD, thermodynamical vibronic coupling constant (ThVCC) and density (ThVCD), are formulated in the finite-temperature grand-canonical ensemble. ThVCD can be applied for charge transfer of a fractional number of electron. Based on the total differential of chemical potential, the relationship between chemical potential, absolute hardness, and vibronic coupling in a bimolecular reaction is discussed.

  10. Effects of the Chemical Potential in two-dimensional Quantum Field Theories

    NASA Astrophysics Data System (ADS)

    Maciel, Soraya G.; Perez, Silvana; Rocha, C.

    2010-02-01

    In this talk we study the effects of a nonzero chemical potential in (1+1) dimensions quantum field models at finite temperature. We start by considering massless fermions in an abelian gauge field background and calculate the n-point amplitudes using the real time formalism. Our calculation shows that the chiral anomaly is unaffected by the presence of a chemical potential at finite temperature. We also find that retarded amplitudes vanish. We then consider the imaginary time formalism and find that the two- and three-point functions vanish, this result being consistent with the real time calculations.

  11. Overlap Dirac operator at nonzero chemical potential and random matrix theory.

    PubMed

    Bloch, Jacques; Wettig, Tilo

    2006-07-07

    We show how to introduce a quark chemical potential in the overlap Dirac operator. The resulting operator satisfies a Ginsparg-Wilson relation and has exact zero modes. It is no longer gamma5 Hermitian, but its nonreal eigenvalues still occur in pairs. We compute the spectral density of the operator on the lattice and show that, for small eigenvalues, the data agree with analytical predictions of non-Hermitian chiral random matrix theory for both trivial and nontrivial topology. We also explain an observed change in the number of zero modes as a function of chemical potential.

  12. Overlap Dirac Operator at Nonzero Chemical Potential and Random Matrix Theory

    SciTech Connect

    Bloch, Jacques; Wettig, Tilo

    2006-07-07

    We show how to introduce a quark chemical potential in the overlap Dirac operator. The resulting operator satisfies a Ginsparg-Wilson relation and has exact zero modes. It is no longer {gamma}{sub 5} Hermitian, but its nonreal eigenvalues still occur in pairs. We compute the spectral density of the operator on the lattice and show that, for small eigenvalues, the data agree with analytical predictions of non-Hermitian chiral random matrix theory for both trivial and nontrivial topology. We also explain an observed change in the number of zero modes as a function of chemical potential.

  13. Topology and chiral random matrix theory at nonzero imaginary chemical potential

    SciTech Connect

    Lehner, C.; Wettig, T.; Ohtani, M.; Verbaarschot, J. J. M.

    2009-04-01

    We study the effect of topology for a random matrix model of QCD at nonzero imaginary chemical potential or nonzero temperature. Nonuniversal fluctuations of Dirac eigenvalues lead to normalization factors that contribute to the {theta} dependence of the partition function. These normalization factors have to be canceled in order to reproduce the {theta} dependence of the QCD partition function. The reason for this behavior is that the topological domain of the Dirac spectrum (the region of the Dirac spectrum that is sensitive to the topological charge) extends beyond the microscopic domain at nonzero imaginary chemical potential or temperature. Such behavior could persist in certain lattice formulations of QCD.

  14. Using quantitative structural property relationships, chemical fate models, and the chemical partitioning space to investigate the potential for long range transport and bioaccumulation of complex halogenated chemical mixtures.

    PubMed

    Gawor, Anya; Wania, Frank

    2013-09-01

    Some substances are mixtures of very large number of constituents which vary widely in their properties, and thus also in terms of their environmental fate and the hazard that they may pose to humans and the environment. Examples of such substances include industrial chemicals such as the chlorinated paraffins, technical pesticides such as toxaphene, and unintended combustion side products, such as mixed halogenated dibenzo-p-dioxins and dibenzofurans. Here we describe a simple graphical superposition method that could precede a more detailed hazard assessment for such substances. First, partitioning and degradation properties for each individual constituent of a mixture are estimated with high-throughput quantitative structure-property relationships. Placed in a chemical partitioning space, i.e. a coordinate system defined by two partitioning coefficients, the mixtures appear as 'clouds'. When model-derived hazard assessment metrics, such as the potential for bioaccumulation and long range transport, are superimposed on these clouds, the resulting maps identify the constituents with the highest value for a particular parameter and thus potentially the greatest hazard. The maps also indicate transparently how the potential for long range transport and bioaccumulation is dependent on structural attributes, such as chain length, and the degree and type of halogenation. In contrast to previous approaches, in which the mixture is represented by a single set of properties or those of a few selected constituents, the whole range of environmental fate behaviors displayed by the constituents of a mixture are being considered. The approach is illustrated with three sets of chemical substances.

  15. Constraining the Symmetry Energy:. a Journey in the Isospin Physics from Coulomb Barrier to Deconfinement

    NASA Astrophysics Data System (ADS)

    di Toro, M.; Colonna, M.; Greco, V.; Ferini, G.; Rizzo, C.; Rizzo, J.; Baran, V.; Gaitanos, T.; Prassa, V.; Wolter, H. H.; Zielinska-Pfabe, M.

    Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. In this work we present a selection of reaction observables in dissipative collisions particularly sensitive to the isovector part of the interaction, i.e.to the symmetry term of the nuclear Equation of State (EoS). At low energies the behavior of the symmetry energy around saturation influences dissipation and fragment production mechanisms. We will first discuss the recently observed Dynamical Dipole Radiation, due to a collective neutron-proton oscillation during the charge equilibration in fusion and deep-inelastic collisions. Important Iso - EOS are stressed. Reactions induced by unstable 132Sn beams appear to be very promising tools to test the sub-saturation Isovector EoS. New Isospin sensitive observables are also presented for deep-inelastic, fragmentation collisions and Isospin equilibration measurements (Imbalance Ratios). The high density symmetry term can be derived from isospin effects on heavy ion reactions at relativistic energies (few AGeV range), that can even allow a "direct" study of the covariant structure of the isovector interaction in the hadron medium. Rather sensitive observables are proposed from collective flows and from pion/kaon production. The possibility of the transition to a mixed hadron-quark phase, at high baryon and isospin density, is finally suggested. Some signatures could come from an expected "neutron trapping" effect. The importance of studying violent collisions with radioactive beams from low to relativistic energies is finally stressed.

  16. An in silico algal toxicity model with a wide applicability potential for industrial chemicals and pharmaceuticals.

    PubMed

    Önlü, Serli; Saçan, Melek Türker

    2017-04-01

    The authors modeled the 72-h algal toxicity data of hundreds of chemicals with different modes of action as a function of chemical structures. They developed mode of action-based local quantitative structure-toxicity relationship (QSTR) models for nonpolar and polar narcotics as well as a global QSTR model with a wide applicability potential for industrial chemicals and pharmaceuticals. The present study rigorously evaluated the generated models, meeting the Organisation for Economic Co-operation and Development principles of robustness, validity, and transparency. The proposed global model had a broad structural coverage for the toxicity prediction of diverse chemicals (some of which are high-production volume chemicals) with no experimental toxicity data. The global model is potentially useful for endpoint predictions, the evaluation of algal toxicity screening, and the prioritization of chemicals, as well as for the decision of further testing and the development of risk-management measures in a scientific and regulatory frame. Environ Toxicol Chem 2017;36:1012-1019. © 2016 SETAC. © 2016 SETAC.

  17. [Irritant contact dermatitis. Part II. Evaluation evaluation of skin irritation potential of chemicals].

    PubMed

    Chomiczewska, Dorota; Kieć-Swierczyńska, Marta; Krecisz, Beata

    2009-01-01

    The evaluation of skin irritation potential of chemicals is essential to secure the safety of individuals exposed to several substances designed for industrial, pharmaceutical or cosmetic use. Until recently, preclinical safety assessment of chemicals was largely based on animal experiments. Ethical concerns and the limited value of animal models in evaluating human skin irritation potential resulted in the development of alternative in vitro methods, such as EpiDerm, EPISKIN or SkinEthic, to assess irritation, i.e. cell cultures and human epidermis models. International organizations like the European Centre for the Validation of Alternative Methods (ECVAM) promotes and monitors the development of nonanimal tests. Human patch tests and use tests also provide an opportunity to identify substances with significant skin irritation potential without recourse to the use of animals. These tests are useful to assess skin irritation potential of cosmetics and detergents.

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

    SciTech Connect

    Biddy, Mary J.; Scarlata, Christopher; Kinchin, Christopher

    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.

  19. Chemical potential dependence of particle ratios within a unified thermal approach

    SciTech Connect

    Bashir, I. Nanda, H.; Uddin, S.

    2016-06-15

    A unified statistical thermal freeze-out model (USTFM) is used to study the chemical potential dependence of identified particle ratios at mid-rapidity in heavy-ion collisions. We successfully reproduce the experimental data ranging from SPS energies to LHC energies, suggesting the statistical nature of the particle production in these collisions and hence the validity of our approach. The behavior of the freeze-out temperature is studied with respect to chemical potential. The freeze-out temperature is found to be universal at the RHIC and LHC and is close to the QCD predicted phase transition temperature, suggesting that the chemical freeze-out occurs soon after the hadronization takes place.

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

    PubMed Central

    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

  1. Field Characterization of Potential Reference Sediments in the Gulf of Mexico: Chemical and Biological Quality

    EPA Science Inventory

    Lewis, Michael A., Jed G. Campbell, Peggy S. Harris, Darrin D. Dantin, Steve S. Foss, Robert L. Quarles, James C. Moore and Cynthia A. Chancy. Submitted. Characterization of Potential Reference Areas in the Gulf of Mexico: Near-Coastal Sediment Chemical and Biological Quality. En...

  2. Field Characterization of Potential Reference Sediments in the Gulf of Mexico: Chemical and Biological Quality

    EPA Science Inventory

    Lewis, Michael A., Jed G. Campbell, Peggy S. Harris, Darrin D. Dantin, Steve S. Foss, Robert L. Quarles, James C. Moore and Cynthia A. Chancy. Submitted. Characterization of Potential Reference Areas in the Gulf of Mexico: Near-Coastal Sediment Chemical and Biological Quality. En...

  3. MAMMALIAN SCREENING ASSAYS FOR THE DETECTION OF POTENTIAL ENDOCRINE DISRUPTING CHEMICALS WITH AN EMPHASIS ON MALES

    EPA Science Inventory

    MAMMALIAN SCREENING ASSAYS FOR THE DETECTION OF POTENTIAL
    ENDOCRINE DISRUPTING CHEMICALS WITH AN EMPHASIS ON MALES.
    Authors: L E Gray 1 , J Furr 1 , M G Price 2 , C J Wolf 3 and J S Ostby 1
    Institutions: 1. Endocrinology Branch, Reproductive Toxicology Division, NH...

  4. Dopant gas effect on silicon chemical vapor depositions: A surface potential model

    NASA Technical Reports Server (NTRS)

    Chang, C. A.

    1975-01-01

    A surface potential model is proposed to consistently explain the known dopant gas effects on silicon chemical vapor deposition. This model predicts that the effects of the same dopant gases on the diamond deposition rate using methane and carbon tetrachloride should be opposite and similar to those of silane, respectively. Available data are in agreement with this prediction.

  5. MAMMALIAN SCREENING ASSAYS FOR THE DETECTION OF POTENTIAL ENDOCRINE DISRUPTING CHEMICALS WITH AN EMPHASIS ON MALES

    EPA Science Inventory

    MAMMALIAN SCREENING ASSAYS FOR THE DETECTION OF POTENTIAL
    ENDOCRINE DISRUPTING CHEMICALS WITH AN EMPHASIS ON MALES.
    Authors: L E Gray 1 , J Furr 1 , M G Price 2 , C J Wolf 3 and J S Ostby 1
    Institutions: 1. Endocrinology Branch, Reproductive Toxicology Division, NH...

  6. Susceptibility based upon Chemical Interaction with Disease Processes: Potential Implications for Risk Assessment

    EPA Science Inventory

    One of the challenges facing toxicology and risk assessment is that numerous host and environmental factors may modulate vulnerability and risk. An area of increasing interest is the potential for chemicals to interact with background aging and disease processes, an interaction...

  7. Iso-chemical potential trajectories in the P-T plane for He II

    NASA Technical Reports Server (NTRS)

    Maytal, B.; Nissen, J. A.; Van Sciver, S. W.

    1990-01-01

    Trajectories of constant chemical potential in the P-T plane serve as an integral formulation of London's equation. The trajectories are useful for analysis and synthesis of fountain effect pump performance. A family of trajectories is generated from available numerical codes.

  8. DEVELOPMENT OF A DIETARY EXPOSURE POTENTIAL MODEL FOR EVALUATING DIETARY EXPOSURE TO CHEMICAL RESIDUES IN FOOD

    EPA Science Inventory

    The Dietary Exposure Potential Model (DEPM) is a computer-based model developed for estimating dietary exposure to chemical residues in food. The DEPM is based on food consumption data from the 1987-1988 Nationwide Food Consumption Survey (NFCS) administered by the United States ...

  9. DEVELOPMENT OF A DIETARY EXPOSURE POTENTIAL MODEL FOR EVALUATING DIETARY EXPOSURE TO CHEMICAL RESIDUES IN FOOD

    EPA Science Inventory

    The Dietary Exposure Potential Model (DEPM) is a computer-based model developed for estimating dietary exposure to chemical residues in food. The DEPM is based on food consumption data from the 1987-1988 Nationwide Food Consumption Survey (NFCS) administered by the United States ...

  10. Susceptibility based upon Chemical Interaction with Disease Processes: Potential Implications for Risk Assessment

    EPA Science Inventory

    One of the challenges facing toxicology and risk assessment is that numerous host and environmental factors may modulate vulnerability and risk. An area of increasing interest is the potential for chemicals to interact with background aging and disease processes, an interaction...

  11. Iso-chemical potential trajectories in the P-T plane for He II

    NASA Technical Reports Server (NTRS)

    Maytal, B.; Nissen, J. A.; Van Sciver, S. W.

    1990-01-01

    Trajectories of constant chemical potential in the P-T plane serve as an integral formulation of London's equation. The trajectories are useful for analysis and synthesis of fountain effect pump performance. A family of trajectories is generated from available numerical codes.

  12. Estimating the Potential Toxicity of Chemicals Associated with Hydraulic Fracturing Operations Using Quantitative Structure-Activity Relationship Modeling

    EPA Pesticide Factsheets

    Researchers facilitated evaluation of chemicals that lack chronic oral toxicity values using a QSAR model to develop estimates of potential toxicity for chemicals used in HF fluids or found in flowback or produced water

  13. Excess chemical potential of small solutes across water--membrane and water--hexane interfaces

    NASA Technical Reports Server (NTRS)

    Pohorille, A.; Wilson, M. A.

    1996-01-01

    The excess chemical potentials of five small, structurally related solutes, CH4, CH3F, CH2F2, CHF3, and CF4, across the water-glycerol 1-monooleate bilayer and water-hexane interfaces were calculated at 300, 310, and 340 K using the particle insertion method. The excess chemical potentials of nonpolar molecules (CH4 and CF4) decrease monotonically or nearly monotonically from water to a nonpolar phase. In contrast, for molecules that possess permanent dipole moments (CH3F, CH2F, and CHF3), the excess chemical potentials exhibit an interfacial minimum that arises from superposition of two monotonically and oppositely changing contributions: electrostatic and nonelectrostatic. The nonelectrostatic term, dominated by the reversible work of creating a cavity that accommodates the solute, decreases, whereas the electrostatic term increases across the interface from water to the membrane interior. In water, the dependence of this term on the dipole moment is accurately described by second order perturbation theory. To achieve the same accuracy at the interface, third order terms must also be included. In the interfacial region, the molecular structure of the solvent influences both the excess chemical potential and solute orientations. The excess chemical potential across the interface increases with temperature, but this effect is rather small. Our analysis indicates that a broad range of small, moderately polar molecules should be surface active at the water-membrane and water-oil interfaces. The biological and medical significance of this result, especially in relation to the mechanism of anesthetic action, is discussed.

  14. Excess chemical potential of small solutes across water--membrane and water--hexane interfaces

    NASA Technical Reports Server (NTRS)

    Pohorille, A.; Wilson, M. A.

    1996-01-01

    The excess chemical potentials of five small, structurally related solutes, CH4, CH3F, CH2F2, CHF3, and CF4, across the water-glycerol 1-monooleate bilayer and water-hexane interfaces were calculated at 300, 310, and 340 K using the particle insertion method. The excess chemical potentials of nonpolar molecules (CH4 and CF4) decrease monotonically or nearly monotonically from water to a nonpolar phase. In contrast, for molecules that possess permanent dipole moments (CH3F, CH2F, and CHF3), the excess chemical potentials exhibit an interfacial minimum that arises from superposition of two monotonically and oppositely changing contributions: electrostatic and nonelectrostatic. The nonelectrostatic term, dominated by the reversible work of creating a cavity that accommodates the solute, decreases, whereas the electrostatic term increases across the interface from water to the membrane interior. In water, the dependence of this term on the dipole moment is accurately described by second order perturbation theory. To achieve the same accuracy at the interface, third order terms must also be included. In the interfacial region, the molecular structure of the solvent influences both the excess chemical potential and solute orientations. The excess chemical potential across the interface increases with temperature, but this effect is rather small. Our analysis indicates that a broad range of small, moderately polar molecules should be surface active at the water-membrane and water-oil interfaces. The biological and medical significance of this result, especially in relation to the mechanism of anesthetic action, is discussed.

  15. Exchange repulsive potential adaptable for electronic structure changes during chemical reactions

    SciTech Connect

    Yokogawa, D.

    2015-04-28

    Hybrid methods combining quantum mechanical (QM) and classical calculations are becoming important tools in chemistry. The popular approach to calculate the interaction between QM and classical calculations employs interatomic potentials. In most cases, the interatomic potential is constructed of an electrostatic (ES) potential and a non-ES potential. Because QM treatment is employed in the calculation of the ES potential, the electronic change can be considered in this ES potential. However, QM treatment of the non-ES potential is difficult because of high computational cost. To overcome this difficulty of evaluating the non-ES potential, we proposed an exchange repulsive potential as the main part of the non-ES potential on the basis of a QM approach. This potential is independent of empirical parameters and adaptable for electronic structure. We combined this potential with the reference interaction site model self-consistent field explicitly including spatial electron density distribution and successfully applied it to the chemical reactions in aqueous phase.

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

    PubMed Central

    Kanchiswamy, Chidananda Nagamangala; Malnoy, Mickael; Maffei, Massimo E.

    2015-01-01

    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 by describing microbial–plants and microbial–microbial interactions. Furthermore, we discuss MVOCs role in inducing phenotypic plant responses and their potential physiological effects on crops. Finally, we analyze potential and actual limitations for MVOC use and deployment in field conditions as a sustainable strategy for improving productivity and reducing pesticide use. PMID:25821453

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

    PubMed

    Kanchiswamy, Chidananda Nagamangala; Malnoy, Mickael; Maffei, Massimo E

    2015-01-01

    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 by describing microbial-plants and microbial-microbial interactions. Furthermore, we discuss MVOCs role in inducing phenotypic plant responses and their potential physiological effects on crops. Finally, we analyze potential and actual limitations for MVOC use and deployment in field conditions as a sustainable strategy for improving productivity and reducing pesticide use.

  18. Intrinsic Clearance of Xenobiotic Chemicals by Liver Microsomes: Assessment of Trophic Magnification Potentials.

    PubMed

    Guomao, Zheng; Yi, Wan; Jianying, Hu

    2016-06-21

    The use of trophic magnification factors (TMFs) to characterize the bioaccumulation potentials of chemicals was encouraged; however, the method for the assessment of trophic magnification potentials is still lacking. We optimized the in vitro assays used for the measurement of intrinsic clearance in liver microsomes by incorporating benzo[a]pyrene (B(a)P) as a benchmark compound. The intrinsic clearance of 40 compounds was then measured in microsomes from fish (weevers) and birds (quail); the characteristics of the trophic transfer of these 40 compounds were previously investigated in an aquatic food web in Bohai in northern China. Chemicals that are biotransformed at a rate similar to or higher than that of B[a]P in the microsomes of both weevers and quail (in vitro intrinsic clearance values, CL; CL/CLB[a]P: 0.1 to 2.4) generally exhibited no significant trophic magnification or dilution in the food web (TMF ≈ 1 or < 1), whereas chemicals that are biotransformed at extremely slow rates compared with B[a]P (CL/CLB[a]P: 0 to 0.2) showed significant trophic magnification in the food web (TMF > 1). The in vitro intrinsic clearance values of the target chemicals were found to be consistent with their respective trophic transfer behavior in the aquatic food web. Significant negative correlations were also found between the TMFs and the intrinsic clearance values of all target chemicals obtained in microsomes from both weevers and quail. Multiple linear regression analysis showed that biotransformation rates (CL/CLB[a]P) are a more important factor compared with the lipophilicity of the chemicals (log Kow) in the assessment of the trophic magnification of chemicals in the aquatic food web.

  19. Screening chemicals for the potential to be persistent organic pollutants: a case study of Arctic contaminants.

    PubMed

    Brown, Trevor N; Wania, Frank

    2008-07-15

    A large and ever-increasing number of chemicals are used in commerce, and researchers and regulators have struggled to ascertain that these chemicals do not threaten human health or cause environmental or ecological damage. The presence of persistent organic pollutants (POPs) in remote environments such as the Arctic is of special concern and has international regulatory implications. Responding to the need for a way to identify chemicals of high concern, a methodology has been developed which compares experimentally measured properties, or values predicted from chemical structure alone, to a set of screening criteria. These criteria include partitioning properties that allow for accumulation in the physical Arctic environment and in the Arctic human food chain, and resistance to atmospheric oxidation. Atthe same time we quantify the extent of structural resemblance to a group of known Arctic contaminants. Comparison of the substances that are identified by a mechanistic description of the processes that lead to Arctic contamination with those substances that are structurally similar to known Arctic contaminants reveals the strengths and limitations of either approach. Within a data set of more than 100,000 distinct industrial chemicals, the methodology identifies 120 high production volume chemicals which are structurally similarto known Arctic contaminants and/or have partitioning properties that suggest they are potential Arctic contaminants.

  20. Sonochemistry: what potential for conversion of lignocellulosic biomass into platform chemicals?

    PubMed

    Chatel, Gregory; De Oliveira Vigier, Karine; Jérôme, François

    2014-10-01

    This Review focuses on the use of ultrasound to produce chemicals from lignocellulosic biomass. However, the question about the potential of sonochemistry for valorization/conversion of lignocellulosic biomass into added-value chemicals is rather conceptual. Until now, this technology has been mainly used for the production of low-value chemicals such as biodiesel or as simple method for pretreatment or extraction. According to preliminary studies reported in literature, access to added-value chemicals can be easily and sometimes solely obtained by the use of ultrasound. The design of sonochemical parameters offers many opportunities to develop new eco-friendly and efficient processes. The goal of this Review is to understand why the use of ultrasound is focused rather on pretreatment or extraction of lignocellulosic biomass rather than on the production of chemicals and to understand, through the reported examples, which directions need to be followed to favor strategies based on ultrasound-assisted production of chemicals from lignocellulosic biomass. We believe that ultrasound-assisted processes represent an innovative approach and will create a growing interest in academia but also in the industry in the near future. Based on the examples reported in the literature, we critically discuss how sonochemistry could offer new strategies and give rise to new results in lignocellulosic biomass valorization. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Chemical characteristics and biofuels potentials of various plant biomasses: influence of the harvesting date.

    PubMed

    Godin, Bruno; Lamaudière, Stéphane; Agneessens, Richard; Schmit, Thomas; Goffart, Jean-Pierre; Stilmant, Didier; Gerin, Patrick A; Delcarte, Jérôme

    2013-10-01

    An optimal valorization of plant biomasses to produce biofuels requires a good knowledge of the available contents and molecular composition of the main chemical components, which changes with the harvesting date. Therefore, we assessed the influence of harvesting date on the chemical characteristics of various energy crops in the context of their conversion to biofuels. We showed that the biomass chemical composition, enzymatic digestible organic matter, bioethanol and thermal energy production potential for each species are impacted by the harvesting date. The proportion of enzymatically digestible organic matter decreases as the harvesting date is delayed. This is related to the increase in cellulose and lignin contents. The suitability of the biomasses for bioethanol production increases with harvest stage, as the total carbohydrates content increases. The suitability of the biomasses as a source of thermal energy increases according to the harvesting date as the proportion of organic matter increases and the content of mineral compounds decreases. For all investigated energy conversions, the best harvesting period is autumn, because the significantly higher crop dry matter yield largely compensates for the sometimes slightly less favorable chemical characteristics. While the biomass composition of energy crops changes with harvest stage, the dry biomass yield per unit area is the main factor that controls the total amount of chemical components, digestible organic matter, bioethanol and thermal energy that can be expected to be harvested per unit area. The biomass compositions presented in this paper are essential to investigate their suitability for bioenergy conversion. © 2013 Society of Chemical Industry.

  2. Determination of physical and chemical stability in pressurised metered dose inhalers: potential new techniques.

    PubMed

    Ooi, Jesslynn; Traini, Daniela; Boyd, Ben J; Gaisford, Simon; Young, Paul M

    2015-01-01

    Pressurised metered dose inhalers (pMDIs) are subject to rigorous physical and chemical stability tests during formulation. Due to the time and cost associated with product development studies, there is a need for online techniques to fast screen new formulations in terms of physical and chemical (physico-chemical) stability. The problem with achieving this is that pMDIs are by their definition, pressurised, making the direct observation of physico-chemical properties in situ difficult. This review highlights the characterisation tools that can enhance the product development process for pMDIs. Techniques investigated include: laser diffraction, Raman spectroscopy, isothermal ampoule calorimetry, titration calorimetry and gas perfusion calorimetry. The operational principles behind each technique are discussed and complemented with examples from the literature. Laser diffraction is well placed to analyse real-time physical stability as a function of particle size; however, its use is restricted to suspension pMDIs. Raman spectroscopy can be potentially used to attain both suspension and solution pMDI spectra in real time; however, the majority of experiments are ex-valve chemical composition mapping. Calorimetry is an effective technique in capturing both chemical and physical degradations of APIs in real time but requires redevelopment to withstand pressure for the purposes of pMDI screening.

  3. Evaluation of liposome-water partitioning for predicting bioaccumulation potential of hydrophobic organic chemicals.

    PubMed

    van der Heijden, Stephan A; Jonker, Michiel T O

    2009-12-01

    Considering the importance of bioaccumulation factors (BAFs) in risk assessment of chemicals and the ethical issues and complexity of the determination of these factors in standard tests with living organisms, there is a need for alternative approaches for predicting bioaccumulation. In this study, liposome-water partitioning coefficients as determined by using solid-phase microextraction (SPME) were evaluated for the cause of assessing bioaccumulation potential of hydrophobic organic chemicals (HOCs). To this end, the SPME method was mapped (in terms of mass balance, mode of spiking, kinetics, and reproducibility) and validated against literature data. Furthermore, the robustness of liposomes as partitioning phase was investigated (in terms of chemical loading, and pH and ionic strength of the medium), and finally liposome-water partition coefficients (K(lipw)) determined for polycyclic aromatic hydrocarbons (PAHs; 4.5 < logK(ow) < 7.2) were compared with literature BAF values for several aquatic species. The results indicated that (i) SPME is a valid, fast, and reproducible method for measuring K(lipw) values; (ii) liposomes provide a very robust partitioning phase; and (iii) K(lipw) values agreed very well with literature PAH BAF values. SPME-derived K(lipw) values therefore seem a very promising predictor of bioaccumulation potential of HOCs. By including model- or in vitro-derived biotransformation rates, bioaccumulation potential estimates might be converted into surrogate BAFs, thereby extending the applicability of K(lipw) values to metabolizable chemicals and species with more advanced biotransformation capacity.

  4. A simulation method for the calculation of chemical potentials in small, inhomogeneous, and dense systems.

    PubMed

    Neimark, Alexander V; Vishnyakov, Aleksey

    2005-06-15

    We present a modification of the gauge cell Monte Carlo simulation method [A. V. Neimark and A. Vishnyakov, Phys. Rev. E 62, 4611 (2000)] designed for chemical potential calculations in small confined inhomogeneous systems. To measure the chemical potential, the system under study is set in chemical equilibrium with the gauge cell, which represents a finite volume reservoir of ideal particles. The system and the gauge cell are immersed into the thermal bath of a given temperature. The size of the gauge cell controls the level of density fluctuations in the system. The chemical potential is rigorously calculated from the equilibrium distribution of particles between the system cell and the gauge cell and does not depend on the gauge cell size. This scheme, which we call a mesoscopic canonical ensemble, bridges the gap between the canonical and the grand canonical ensembles, which are known to be inconsistent for small systems. The ideal gas gauge cell method is illustrated with Monte Carlo simulations of Lennard-Jones fluid confined to spherical pores of different sizes. Special attention is paid to the case of extreme confinement of several molecular diameters in cross section where the inconsistency between the canonical ensemble and the grand canonical ensemble is most pronounced. For sufficiently large systems, the chemical potential can be reliably determined from the mean density in the gauge cell as it was implied in the original gauge cell method. The method is applied to study the transition from supercritical adsorption to subcritical capillary condensation, which is observed in nanoporous materials as the pore size increases.

  5. Calculation of chemical potentials of chain molecules by the incremental gauge cell method.

    PubMed

    Rasmussen, Christopher J; Vishnyakov, Aleksey; Neimark, Alexander V

    2011-12-07

    The gauge cell Monte Carlo method is extended to calculations of the incremental chemical potentials and free energies of linear chain molecules. The method was applied to chains of Lennard-Jones beads with stiff harmonic bonds up to 500 monomers in length. We show that the suggested method quantitatively reproduces the modified Widom particle insertion method of Kumar et al. [S. K. Kumar, I. Szleifer, and A. Z. Panagiotopoulos, Phys. Rev. Lett. 66(22), 2935 (1991)], and is by an order of magnitude more efficient for long chains in terms of the computational time required for the same accuracy of chemical potential calculations. The chain increment ansatz, which suggests that the incremental chemical potential is independent of the chain length, was tested at different temperatures. We confirmed that the ansatz holds only for coils above the θ temperature. Special attention is paid to the effects of the magnitude of adsorption potential and temperature on the behavior of single chains in confinements that are comparable in size with the free chain radius of gyration. At sufficiently low temperatures, the dependence of the incremental chemical potential on the chain length in wetting pores is superficially similar to a capillary condensation isotherm, reflecting monolayer formation following by pore volume filling, as the chain length increases. We find that the incremental gauge cell method is an accurate and efficient technique for calculations of the free energies of chain molecules in bulk systems and nanoconfinements alike. The suggested method may find practical applications, such as modeling polymer partitioning on porous substrates and dynamics of chain translocation into nanopores.

  6. Calculation of chemical potentials of chain molecules by the incremental gauge cell method

    NASA Astrophysics Data System (ADS)

    Rasmussen, Christopher J.; Vishnyakov, Aleksey; Neimark, Alexander V.

    2011-12-01

    The gauge cell Monte Carlo method is extended to calculations of the incremental chemical potentials and free energies of linear chain molecules. The method was applied to chains of Lennard-Jones beads with stiff harmonic bonds up to 500 monomers in length. We show that the suggested method quantitatively reproduces the modified Widom particle insertion method of Kumar et al. [S. K. Kumar, I. Szleifer, and A. Z. Panagiotopoulos, Phys. Rev. Lett. 66(22), 2935 (1991)], 10.1103/PhysRevLett.66.2935, and is by an order of magnitude more efficient for long chains in terms of the computational time required for the same accuracy of chemical potential calculations. The chain increment ansatz, which suggests that the incremental chemical potential is independent of the chain length, was tested at different temperatures. We confirmed that the ansatz holds only for coils above the θ temperature. Special attention is paid to the effects of the magnitude of adsorption potential and temperature on the behavior of single chains in confinements that are comparable in size with the free chain radius of gyration. At sufficiently low temperatures, the dependence of the incremental chemical potential on the chain length in wetting pores is superficially similar to a capillary condensation isotherm, reflecting monolayer formation following by pore volume filling, as the chain length increases. We find that the incremental gauge cell method is an accurate and efficient technique for calculations of the free energies of chain molecules in bulk systems and nanoconfinements alike. The suggested method may find practical applications, such as modeling polymer partitioning on porous substrates and dynamics of chain translocation into nanopores.

  7. Chemical Composition of Ethanolic Extracts of Some Wild Mushrooms from Tanzania and Their Medicinal Potentials.

    PubMed

    Chelela, Baraka Luca; Chacha, Musa; Matemu, Athanasia

    2016-01-01

    The ethanolic extracts of 5 edible and inedible wild mushrooms collected from the Southern Highlands of Tanzania were characterized by gas chromatography-mass spectrometry. A total of 75 chemical compounds were obtained, mainly fatty acids, carotenoids, alkaloids, phenols, terpernes, steroids, pyranoside, saccharides, and amino acids. Chemical compounds were identified from the ethanolic extract of Russula cellulata, R. kivuensis, Lactarius densifolius, L. gymnocarpoides, and Lactarius sp. In addition, mass spectra of 4 major groups of compounds were also determined. This study confirms the presence of some important bioactive compounds, such as essential fatty acids (oleic and linoleic), amino acids, and carotenoids. The reported chemical profiles give an insight into the use of wild mushrooms as a potential source of bioactive compounds for nutraceuticals and pharmaceuticals.

  8. Recently disclosed chemical entities as potential candidates for management of tuberculosis.

    PubMed

    Stec, Jozef; Abourashed, Ehab A

    2015-01-01

    Tuberculosis (TB) is one of the deadliest infectious diseases worldwide. The drug discovery process of novel, safe and effective agents to combat TB involves identification of new molecular targets and novel chemical scaffolds. The current anti-TB drug pipeline includes several small molecules with more to follow as new candidates are disclosed. This review highlights the most significant findings described in 78 international, European and US patents for chemically diverse compounds as prospective anti-TB medications. Main points of emphasis include chemical classification, in vitro and in vivo activity, ADME/Tox profile and mycobacterial target as described in each patent. The collective mass of compounds disclosed in the reviewed patents introduces new candidates as potential therapeutic agents for TB infections.

  9. The protoelectric potential map (PPM): an absolute two-dimensional chemical potential scale for a global understanding of chemistry.

    PubMed

    Radtke, Valentin; Himmel, Daniel; Pütz, Katharina; Goll, Sascha K; Krossing, Ingo

    2014-04-07

    We introduce the protoelectric potential map (PPM) as a novel, two-dimensional plot of the absolute reduction potential (peabs scale) combined with the absolute protochemical potential (Brønsted acidity: pHabs scale). The validity of this thermodynamically derived PPM is solvent-independent due to the scale zero points, which were chosen as the ideal electron gas and the ideal proton gas at standard conditions. To tie a chemical environment to these reference states, the standard Gibbs energies for the transfer of the gaseous electrons/protons to the medium are needed as anchor points. Thereby, the thermodynamics of any redox, acid-base or combined system in any medium can be related to any other, resulting in a predictability of reactions even over different media or phase boundaries. Instruction is given on how to construct the PPM from the anchor points derived and tabulated with this work. Since efforts to establish "absolute" reduction potential scales and also "absolute" pH scales already exist, a short review in this field is given and brought into relation to the PPM. Some comments on the electrochemical validation and realization conclude this concept article.

  10. Risk of hypospadias in relation to maternal occupational exposure to potential endocrine disrupting chemicals

    PubMed Central

    Vrijheid, M; Armstrong, B; Dolk, H; van Tongeren, M; Botting, B

    2003-01-01

    Background: Reported rises in the prevalence of hypospadias and other abnormalities of the male reproductive system may be a result of exposure to endocrine disrupting chemicals. Aims: To analyse the relation between risk of hypospadias and maternal occupation, particularly with regard to exposure to potential endocrine disrupting chemicals (EDCs). Methods: Data (1980–96) from the National Congenital Anomaly System (NCAS) were used to analyse the proportion of all congenital anomaly cases (n = 35 962) which were notified with hypospadias (n = 3471) by occupational codes (348 individual job titles) and by categories of exposure to potential EDCs from a job exposure matrix. Results: Five individual occupations (of 348) showed nominally statistically significant excesses, none of which had possible or probable exposure to potential EDCs. Odds ratios for "possible" or "probable" compared to "unlikely" exposure to potential EDCs did not show statistically significant increases in any of the EDC categories after adjustment for social class of the mother and father, nor was there evidence of an upward trend in risk with likelihood of exposure. In the 1992–96 time period odds ratios were increased for hairdressers (the largest group exposed to potential EDCs) and for probable exposure to phthalates (of which hairdressers form the largest group) before social class adjustment. Conclusions: There was little evidence for a relation between risk of hypospadias and maternal occupation or occupational exposure to potential EDCs, but as the exposure classification was necessarily crude, these findings should be interpreted with caution. PMID:12883014

  11. Average chemical properties and potential formation pathways of highly oxidized organic aerosol.

    PubMed

    Daumit, Kelly E; Kessler, Sean H; Kroll, Jesse H

    2013-01-01

    Measurements of ambient organic aerosol indicate that a substantial fraction is highly oxidized and low in volatility, but this fraction is generally not reproduced well in either laboratory studies or models. Here we describe a new approach for constraining the viable precursors and formation pathways of highly oxidized organic aerosol, by starting with the oxidized product and considering the possible reverse reactions, using a set of simple chemical rules. The focus of this work is low-volatility oxidized organic aerosol (LV-OOA), determined from factor analysis of aerosol mass spectrometer data. The elemental composition and volatility of the aerosol enable the determination of its position in a three-dimensional chemical space (defined by H/C, O/C, and carbon number) and thus its average chemical formula. Consideration of possible back-reactions then defines the movement taken through this chemical space, constraining potential reaction pathways and precursors. This approach is taken for two highly oxidized aerosol types, an average of LV-OOA factors from ten field campaigns (average formula C10.5H13.4O7.3), and extremely oxidized LV-OOA (from Mexico City, average formula C10H12.1O8.4). Results suggest that potential formation pathways include functionalization reactions that add multiple functional groups per oxidation step, oligomerization of highly oxidized precursors, and, in some cases, fragmentation reactions that involve the loss of small, reduced fragments.

  12. Use of genotoxicity tests in a TIE to identify chemicals potentially affecting human health

    SciTech Connect

    Goudey, J.S.; Shaw, R.D.; Swanson, S.M.; Nadeau, S.

    1995-12-31

    Imperial Oil operates a sour gas processing plant in southern Alberta that has, for the past several years, been the focus of considerable public and regulatory concern over perceived contamination of soils and groundwater on a nearby ranch. Elevated concentrations of DOC ({approximately}140 mg/L) have been received in groundwater underlying the plant site. Two process-related chemicals, sulfolane and diisopropanolamine (DIPA), had been previously identified as the primary components of the DOC plume, although the chemicals associated with 30% of the DOC could not be identified. A risk assessment was initiated in 1994 to determine whether off-site migration of sulfolane and DIPA or of other unidentified contaminants poses a risks to human health and/or ecological receptors. One component of the risk assessment included conducting a TIE to help identify the chemical(s) in contaminated groundwater underlying the gas plant that might adversely affect human health. Three endpoints were utilized in the TIE: MicroTox, SOS-Chromotest and the Ames test. MicroTox was used since it exhibited a response to whole groundwater from the site, while the genotoxicity tests were used because DIPA reportedly causes a response in the Ames test and because of the concern over potential human health affects arising from other unidentified contaminants. Results of the TIE indicated that the chemicals causing the toxicity in the groundwater sample were water soluble compounds, with similar characteristics to the process chemicals used at the gas plant and detected at high concentrations in groundwater from the plant site. These results provided additional evidence to help focus the risk assessment on the chemicals sulfolane and diisopropanolamine.

  13. Stream geochemistry, chemical weathering and CO 2 consumption potential of andesitic terrains, Dominica, Lesser Antilles

    NASA Astrophysics Data System (ADS)

    Goldsmith, Steven T.; Carey, Anne E.; Johnson, Brent M.; Welch, Susan A.; Lyons, W. Berry; McDowell, William H.; Pigott, Jeffrey S.

    2010-01-01

    Recent studies of chemical weathering of andesitic-dacitic material on high-standing islands (HSIs) have shown these terrains have some of the highest observed rates of chemical weathering and associated CO 2 consumption yet reported. However, the paucity of stream gauge data in many of these terrains has limited determination of chemical weathering product fluxes. In July 2006 and March 2008, stream water samples were collected and manual stream gauging was performed in watersheds throughout the volcanic island of Dominica in the Lesser Antilles. Distinct wet and dry season solute concentrations reveal the importance of seasonal variations on the weathering signal. A cluster analysis of the stream geochemical data shows the importance of parent material age on the overall delivery of solutes. Observed Ca:Na, HCO 3:Na and Mg:Na ratios suggest crystallinity of the parent material may also play an important role in determining weathering fluxes. From total dissolved solids concentrations and mean annual discharge calculations we calculate chemical weathering yields of (6-106 t km -2 a -1), which are similar to those previously determined for basalt terrains. Silicate fluxes (3.1-55.4 t km -2 a -1) and associated CO 2 consumption (190-1575 × 10 3 mol km -2 a -1) determined from our study are among the highest determined to date. The calculated chemical fluxes from our study confirm the weathering potential of andesitic-dacitic terrains and that additional studies of these terrains are warranted.

  14. JAHN—A program for representing atomic and nuclear states within an isospin basis

    NASA Astrophysics Data System (ADS)

    Gaigalas, G.; Fritzsche, S.; Gaidamauskas, E.; Kiršanskas, G.; Žalandauskas, T.

    2006-07-01

    A computer program is presented to deal with atomic and nuclear state functions within an isospin-coupled basis. Apart from the classification of the isospin bases states, the program JAHN supports the computation of the corresponding coefficients of fractional parentage as well as of the transformation matrices going from a LS-coupled to an isospin-coupled basis. In the future, these features may facilitate the treatment of atomic systems in order to obtain a deeper insight into the coupling of open-shell atoms and ions. The JAHN program has been designed for interactive work and is distributed as a MAPLE module. Program summaryTitle of program:JAHN Catalogue identifier:ADXA_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADXA_v1_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions:None Computers for which the program is designed: All computers with a valid license of the computer algebra package MAPLE which is a registered trademark of Waterloo Maple Inc. Installations: University of Kassel (Germany) Operating systems under which the program has been tested: Linux 8.1+ Program language used:MAPLE, Release 8 and 9 Memory required to execute with typical data: 30 MB Number of lines in distributed program, including test data, etc.: 38 158 Number of bytes in distributed program, including test data, etc.: 743 689 Distribution format: tar.gz Nature of the physical problem: The accurate computation of atomic (nuclear) properties and level structures requires a good understanding and implementation of the atomic (nuclear) shell model and, hence, a fast and reliable access to its classification, the coefficients of fractional parentage and the coefficients of fractional grandparentage. For open-shell atoms and ions, moreover, a reliable classification of the level structure often requires the knowledge of some transformation matrices in order to find the main components of the wave functions as well as

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

    PubMed Central

    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

  16. Chemical compounds toxic to invertebrates isolated from marine cyanobacteria of potential relevance to the agricultural industry.

    PubMed

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

    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.

  17. Chemical-potential route: a hidden Percus-Yevick equation of state for hard spheres.

    PubMed

    Santos, Andrés

    2012-09-21

    The chemical potential of a hard-sphere fluid can be expressed in terms of the contact value of the radial distribution function of a solute particle with a diameter varying from zero to that of the solvent particles. Exploiting the explicit knowledge of such a contact value within the Percus-Yevick theory, and using standard thermodynamic relations, a hitherto unknown Percus-Yevick equation of state, p/ρk(B)T = -(9/η) ln(1-η)-(16-31η)/2(1-η)(2), is unveiled. This equation of state turns out to be better than the one obtained from the conventional virial route. Interpolations between the chemical-potential and compressibility routes are shown to be more accurate than the widely used Carnahan-Starling equation of state. The extension to polydisperse hard-sphere systems is also presented.

  18. Strongly enhanced temperature dependence of the chemical potential in FeSe

    NASA Astrophysics Data System (ADS)

    Rhodes, L. C.; Watson, M. D.; Haghighirad, A. A.; Eschrig, M.; Kim, T. K.

    2017-05-01

    Employing a 10-orbital tight-binding model, we present a set of hopping parameters fitted directly to our latest high-resolution angle-resolved photoemission spectroscopy (ARPES) data for the high-temperature tetragonal phase of FeSe. Using these parameters, we predict a large 10 meV shift of the chemical potential as a function of temperature. To confirm this large temperature dependence, we performed ARPES experiments on FeSe and observed a ˜25 meV rigid shift to the chemical potential between 100 and 300 K. This strong shift has important implications for theoretical models of superconductivity and of nematic order in FeSe materials.

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

    PubMed

    de las Heras, Daniel; Schmidt, Matthias

    2015-05-20

    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.

  20. Modeling Vapor Transport Through Partially Saturated Porous Media at the Pore Scale Using Chemical Potential

    NASA Astrophysics Data System (ADS)

    Schreyer, L. G.; Addassi, M.; Johannesson, B.; Lin, H.

    2016-12-01

    Vapor transport in variably saturated soils is traditionally modeled using a system of equations including the conservation of mass, multiphase Darcy equation, and a version of the Philip and deVries equation for heat transfer. Typically the continuity equations and multiphase Darcy equation are combined to form one equation with one unknown, usually moisture content or capillary pressure. Here we introduce chemical potential as an alternate dependent variable and show that it simplifies conceptually and mathematically the modeling of vapor transport. Here we revisit the fundamentals of chemical potential, provide a simple one-dimensional pore-scale model, and compare the model with experimental results. In the process we explain simply the physics of enhanced diffusion due to liquid bridges.

  1. Surface tension, surface energy, and chemical potential due to their difference.

    PubMed

    Hui, C-Y; Jagota, A

    2013-09-10

    It is well-known that surface tension and surface energy are distinct quantities for solids. Each can be regarded as a thermodynamic property related first by Shuttleworth. Mullins and others have suggested that the difference between surface tension and surface energy cannot be sustained and that the two will approach each other over time. In this work we show that in a single-component system where changes in elastic energy can be neglected, the chemical potential difference between the surface and bulk is proportional to the difference between surface tension and surface energy. By further assuming that mass transfer is driven by this chemical potential difference, we establish a model for the kinetics by which mass transfer removes the difference between surface tension and surface energy.

  2. Electrodynamics at non-zero temperature, chemical potential and Bose condensate

    SciTech Connect

    Dolgov, Alexander D.; Lepidi, Angela; Piccinelli, Gabriella E-mail: lepidi@fe.infn.it

    2009-02-15

    Electrodynamics of charged scalar bosons and spin 1/2 fermions is studied at non-zero temperature, chemical potentials, and possible Bose condensate of the charged scalars. Debye screening length, plasma frequency, and the photon dispersion relation are calculated. It is found that in presence of the condensate the time-time component of the photon polarization operator in the first order in electric charge squared acquires infrared singular parts proportional to inverse powers of the spatial photon momentum k.

  3. Chemical potential of water from measurements of optic axial angle of zeolites

    USGS Publications Warehouse

    Donald, Eberlein G.; Christ, C.L.

    1968-01-01

    Values of the uncorrected optic axial angle (2H??) of a crystal of the calcium zeolite stellerite (CaAl2Si7O 18 ?? 7H2O) immersed in calcium chloride solutions of known activity of water (aw) are directly proportional to log aw. A general relationship between the chemical potential of water in the crystal and the optic axial angle is obeyed.

  4. Properties of 2 +1 -flavor QCD in the imaginary chemical potential region: A model approach

    NASA Astrophysics Data System (ADS)

    Sugano, Junpei; Kouno, Hiroaki; Yahiro, Masanobu

    2017-07-01

    We study properties of 2 +1 -flavor QCD in the imaginary chemical potential region by using two approaches. One is a theoretical approach based on the QCD partition function, and the other is a qualitative one based on the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model. In the theoretical approach, we clarify conditions imposed on the imaginary chemical potentials μf=i θfT to realize the Roberge-Weiss (RW) periodicity. Here, T is the temperature, the index f denotes the flavor, and θf are dimensionless chemical potentials. We also show that the RW periodicity is broken if any one of θf is fixed to a constant value. In order to visualize the condition, we use the PNJL model as a model possessing the RW periodicity and draw the phase diagram as a function of θu=θd≡θl for two conditions of θs=θl and θs=0 . We also consider two cases, (μu,μd,μs)=(i θuT ,i C1T ,0 ) and (μu,μd,μs)=(i C2T ,i C2T ,i θsT ); here, C1 and C2 are dimensionless constants, whereas θu and θs are treated as variables. For some choice of C1 (C2), the number density of the up (strange) quark becomes smooth in the entire region of θu (θs) even in the high T region. This property may be important for lattice QCD simulations in the imaginary chemical potential region, since it makes the analytic continuation more feasible.

  5. Quantum origins of the Iczkowski-Margrave model of chemical potential

    SciTech Connect

    Valone, Steven M

    2010-01-01

    Charge flow in materials is controlled at the atomistic level through some model of the chemical potential, such as the Iczkowski-Margrave (IM) model. This model is built largely on heuristic arguments. Here a model Hamiltonian is constructed at the atomistic level commensurate with the IM model. Essential properties of the model Hamiltonian are presented, including a possible revision of the charge dependence in the IM model. Transitional properties of the model are shown to be central to regulating charge flow.

  6. Use of terrestrial field studies in the derivation of bioaccumulation potential of chemicals.

    PubMed

    van den Brink, Nico W; Arblaster, Jennifer A; Bowman, Sarah R; Conder, Jason M; Elliott, John E; Johnson, Mark S; Muir, Derek C G; Natal-da-Luz, Tiago; Rattner, Barnett A; Sample, Bradley E; Shore, Richard F

    2016-01-01

    Field-based studies are an essential component of research addressing the behavior of organic chemicals, and a unique line of evidence that can be used to assess bioaccumulation potential in chemical registration programs and aid in development of associated laboratory and modeling efforts. To aid scientific and regulatory discourse on the application of terrestrial field data in this manner, this article provides practical recommendations regarding the generation and interpretation of terrestrial field data. Currently, biota-to-soil-accumulation factors (BSAFs), biomagnification factors (BMFs), and bioaccumulation factors (BAFs) are the most suitable bioaccumulation metrics that are applicable to bioaccumulation assessment evaluations and able to be generated from terrestrial field studies with relatively low uncertainty. Biomagnification factors calculated from field-collected samples of terrestrial carnivores and their prey appear to be particularly robust indicators of bioaccumulation potential. The use of stable isotope ratios for quantification of trophic relationships in terrestrial ecosystems needs to be further developed to resolve uncertainties associated with the calculation of terrestrial trophic magnification factors (TMFs). Sampling efforts for terrestrial field studies should strive for efficiency, and advice on optimization of study sample sizes, practical considerations for obtaining samples, selection of tissues for analysis, and data interpretation is provided. Although there is still much to be learned regarding terrestrial bioaccumulation, these recommendations provide some initial guidance to the present application of terrestrial field data as a line of evidence in the assessment of chemical bioaccumulation potential and a resource to inform laboratory and modeling efforts. © 2015 SETAC.

  7. Fast Method for Computing Chemical Potentials and Liquid-Liquid Phase Equilibria of Macromolecular Solutions.

    PubMed

    Qin, Sanbo; Zhou, Huan-Xiang

    2016-08-25

    Chemical potential is a fundamental property for determining thermodynamic equilibria involving exchange of molecules, such as between two phases of molecular systems. Previously, we developed the fast Fourier transform (FFT)-based method for Modeling Atomistic Protein-crowder interactions (FMAP) to calculate excess chemical potentials according to the Widom insertion. Intermolecular interaction energies were expressed as correlation functions and evaluated via FFT. Here, we extend this method to calculate liquid-liquid phase equilibria of macromolecular solutions. Chemical potentials are calculated by FMAP over a wide range of molecular densities, and the condition for coexistence of low- and high-density phases is determined by the Maxwell equal-area rule. When benchmarked on Lennard-Jones fluids, our method produces an accurate phase diagram at 18% of the computational cost of the current best method. Importantly, the gain in computational speed increases dramatically as the molecules become more complex, leading to many orders of magnitude in speed up for atomistically represented proteins. We demonstrate the power of FMAP by reporting the first results for the liquid-liquid coexistence curve of γII-crystallin represented at the all-atom level. Our method may thus open the door to accurate determination of phase equilibria for macromolecular mixtures such as protein-protein mixtures and protein-RNA mixtures, that are known to undergo liquid-liquid phase separation, both in vitro and in vivo.

  8. The chemical potential of hydrogen in Mg-films and metal-doped carbon nanostructures

    NASA Astrophysics Data System (ADS)

    Yoon, Mina; Weitering, Hanno; Zhang, Zhenyu

    2011-03-01

    We use first-principles density functional theory to study the binding mechanism of hydrogen to nanoscale systems. We investigate the performance of the exchange-correlation functional in describing the interaction between hydrogen and metal systems and the importance of the vibrational contribution in the formation enthalpy. In ultrathin Mg films the stability of hydrides is much lower than in the corresponding bulk systems and it can be modified by metal alloying. We calculate the chemical potential of hydrogen in Mg films for different dopant species and film thicknesses while including all vibrational degrees of freedom. By comparing the chemical potential with that of free hydrogen gas at finite temperature and pressure, we construct a hydrogenation phase diagram and identify the conditions for hydrogen absorption/desorption. The vibrational contribution to the chemical potential of hydrogen becomes more prominent for dihydrogen adsorption to metals, where its significance dramatically changes depending on the binding characteristics. This feature is illustrated by the example of metal-doped nanocarbon systems. Supported by the US DOE, Office of Basic Energy Sciences, Materials Sciences and Engineering Division and the Max Planck Society.

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

    PubMed Central

    Rhyee, Jong-Soo; Kim, Jin Hee

    2015-01-01

    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. PMID:28788002

  10. Higher order quark number fluctuations via imaginary chemical potentials in Nf=2 +1 QCD

    NASA Astrophysics Data System (ADS)

    D'Elia, Massimo; Gagliardi, Giuseppe; Sanfilippo, Francesco

    2017-05-01

    We discuss analytic continuation as a tool to extract the cumulants of the quark number fluctuations in the strongly interacting medium from lattice QCD simulations at imaginary chemical potentials. The method is applied to Nf=2 +1 QCD, discretized with stout improved staggered fermions, physical quark masses and the tree level Symanzik gauge action, exploring temperatures ranging from 135 up to 350 MeV and adopting mostly lattices with Nt=8 sites in the temporal direction. The method is based on a global fit of various cumulants as a function of the imaginary chemical potentials. We show that it is particularly convenient to consider cumulants up to order two, and that below Tc the method can be advantageous, with respect to a direct Montecarlo sampling at μ =0 , for the determination of generalized susceptibilities of order four or higher, and especially for mixed susceptibilities, for which the gain is well above one order of magnitude. We provide cumulants up to order eight, which are then used to discuss the radius of convergence of the Taylor expansion and the possible location of the second-order critical point at real μ : no evidence for such a point is found in the explored range of T and for chemical potentials within present determinations of the pseudocritical line.

  11. Higgs mechanism with type-II Nambu-Goldstone bosons at finite chemical potential

    SciTech Connect

    Hama, Yusuke; Hatsuda, Tetsuo; Uchino, Shun

    2011-06-15

    When the spontaneous symmetry breaking occurs for systems without Lorentz covariance, there arises possible mismatch, N{sub NG}chemical potential and by enforcing ''charge'' neutrality. To separate the physical spectra from unphysical ones, the R{sub {xi}} gauge is adopted. Not only massless NG bosons but also massive scalar bosons generated by the chemical potential are absorbed into spatial components of the gauge bosons. Although the chemical potential induces a nontrivial mixings among the scalar bosons and temporal components of the gauge bosons, it does not affect the structure of the physical spectra, so that the total number of physical modes is not modified even for N{sub NG}

  12. Finding the effective Polyakov line action for SU(3) gauge theories at finite chemical potential

    NASA Astrophysics Data System (ADS)

    Greensite, Jeff; Langfeld, Kurt

    2014-07-01

    Motivated by the sign problem, we calculate the effective Polyakov line action corresponding to certain SU(3) lattice gauge theories on a 163×6 lattice via the "relative weights" method introduced in our previous papers. The calculation is carried out at β =5.6, 5.7 for the pure gauge theory and at β=5.6 for the gauge field coupled to a relatively light scalar particle. In the latter example we determine the effective theory also at finite chemical potential and show how observables relevant to phase structure can be computed in the effective theory via mean field methods. In all cases a comparison of Polyakov line correlators in the effective theory and the underlying lattice gauge theory, computed numerically at zero chemical potential, shows accurate agreement down to correlator magnitudes of order 10-5. We also derive the effective Polyakov line action corresponding to a gauge theory with heavy quarks and large chemical potential and apply mean field methods to extract observables.

  13. Use of terrestrial field studies in the derivation of bioaccumulation potential of chemicals

    USGS Publications Warehouse

    van den Brink, Nico W.; Arblaster, Jennifer A.; Bowman, Sarah R.; Conder, Jason M.; Elliott, John E.; Johnson, Mark S.; Muir, Derek C.G.; Natal-da-Luz, Tiago; Rattner, Barnett A.; Sample, Bradley E.; Shore, Richard F.

    2016-01-01

    Field-based studies are an essential component of research addressing the behavior of organic chemicals, and a unique line of evidence that can be used to assess bioaccumulation potential in chemical registration programs and aid in development of associated laboratory and modeling efforts. To aid scientific and regulatory discourse on the application of terrestrial field data in this manner, this article provides practical recommendations regarding the generation and interpretation of terrestrial field data. Currently, biota-to-soil-accumulation factors (BSAFs), biomagnification factors (BMFs), and bioaccumulation factors (BAFs) are the most suitable bioaccumulation metrics that are applicable to bioaccumulation assessment evaluations and able to be generated from terrestrial field studies with relatively low uncertainty. Biomagnification factors calculated from field-collected samples of terrestrial carnivores and their prey appear to be particularly robust indicators of bioaccumulation potential. The use of stable isotope ratios for quantification of trophic relationships in terrestrial ecosystems needs to be further developed to resolve uncertainties associated with the calculation of terrestrial trophic magnification factors (TMFs). Sampling efforts for terrestrial field studies should strive for efficiency, and advice on optimization of study sample sizes, practical considerations for obtaining samples, selection of tissues for analysis, and data interpretation is provided. Although there is still much to be learned regarding terrestrial bioaccumulation, these recommendations provide some initial guidance to the present application of terrestrial field data as a line of evidence in the assessment of chemical bioaccumulation potential and a resource to inform laboratory and modeling efforts.

  14. Isospin aspects in nuclear reactions involving Ca beams at 25 MeV/nucleon

    SciTech Connect

    Lombardo, I. Agodi, C.; Alba, R.; Amorini, F.; Anzalone, A.; Auditore, L.; Berceanu, I.; Cardella, G.; Cavallaro, S.; Chatterjee, M. B.; Filippo, E. De; Di Pietro, A.; Figuera, P.; Giuliani, G.; Geraci, E.; Grassi, L.; Grzeszczuk, A.; Han, J.; La Guidara, E.; Lanzalone, G.; and others

    2011-11-15

    Isospin dependence of dynamical and thermodynamical properties observed in reactions {sup 40}Ca+ {sup 40,48}Ca and {sup 40}Ca + {sup 46}Ti at 25 MeV/nucleon has been studied. We used the CHIMERA multi-detector array. Strong isospin effects are seen in the isotopic distributions of light nuclei and in the competition between different reaction mechanisms in semi-central collisions. We will show also preliminary results obtained in nuclear collision {sup 48}Ca + {sup 48}Ca at 25MeV/nucleon, having very high N/Z value in the entrance channel (N/Z = 1.4). The enhancement of evaporation residue production confirms the strong role played by the N/Z degree of freedom in nuclear dynamics.

  15. Isospin decomposition of γN→N* transitions within a dynamical coupled-channels model

    DOE PAGES

    Kamano, Hiroyuki; Nakamura, S. X.; Lee, T. -S. H.; ...

    2016-07-07

    Here, by extending the dynamical coupled-channels analysis performed in our previous work to include the available data of photoproduction of pi mesons off neutrons, the transition amplitudes for the photoexcitation of the neutron-to-nucleon resonances, γn → N*, at the resonance pole positions are determined. The combined fits to the data for both the proton- and neutron-target reactions also revise our results for the resonance pole positions and the γp → N* transition amplitudes. Our results allow an isospin decomposition of the γN → N* transition amplitudes for the isospin I = 1/2 N* resonances, which is necessary for testing hadronmore » structure models and gives crucial inputs for constructing models of neutrino-induced reactions in the nucleon resonance region.« less

  16. Isospin effects on light charged particles as probes of nuclear dissipation

    SciTech Connect

    Ye, W.

    2009-07-15

    The multiplicities of postsaddle protons and {alpha} particles of the heavy systems {sup 234}Cf, {sup 240}Cf, {sup 246}Cf, and {sup 240}U as functions of the postsaddle dissipation strength are calculated in the framework of a dynamical Langevin model coupled with a statistical decay model. It is found that with increasing isospin of the Cf system, the sensitivity of the postsaddle proton and {alpha}-particle multiplicity to the dissipation strength decreases substantially, and it disappears for the {sup 240}U system. We suggest that on the experimental side, to accurately probe the postsaddle dissipation strength by measuring the prescission proton and {alpha}-particle multiplicity, it is best to populate heavy compound systems with low isospin.

  17. Isospin-symmetry-breaking effects in A˜70 nuclei within beyond-mean-field approach

    NASA Astrophysics Data System (ADS)

    Petrovici, A.; Andrei, O.

    2015-02-01

    Particular isospin-symmetry-breaking probes including Coulomb energy differences (CED), mirror energy differences (MED), and triplet energy differences (TED) manifest anomalies in the A˜70 isovector triplets of nuclei. The structure of proton-rich nuclei in the A˜70 mass region suggests shape coexistence and competition between pairing correlations in different channels. Recent results concerning the interplay between isospin-mixing and shape-coexistence effects on exotic phenomena in A˜70 nuclei obtained within the beyond-mean-field complex Excited Vampir variational model with symmetry projection before variation using a realistic effective interaction in a relatively large model space are presented. Excited Vampir predictions concerning the Gamow-Teller β decay to the odd-odd N=Z 66As and 70Br nuclei correlated with the pair structure analysis in the T=1 and T=0 channel of the involved wave functions are discussed.

  18. Isospin-symmetry-breaking effects in A∼70 nuclei within beyond-mean-field approach

    SciTech Connect

    Petrovici, A.; Andrei, O.

    2015-02-24

    Particular isospin-symmetry-breaking probes including Coulomb energy differences (CED), mirror energy differences (MED), and triplet energy differences (TED) manifest anomalies in the A∼70 isovector triplets of nuclei. The structure of proton-rich nuclei in the A∼70 mass region suggests shape coexistence and competition between pairing correlations in different channels. Recent results concerning the interplay between isospin-mixing and shape-coexistence effects on exotic phenomena in A∼70 nuclei obtained within the beyond-mean-field complex Excited Vampir variational model with symmetry projection before variation using a realistic effective interaction in a relatively large model space are presented. Excited Vampir predictions concerning the Gamow-Teller β decay to the odd-odd N=Z {sup 66}As and {sup 70}Br nuclei correlated with the pair structure analysis in the T=1 and T=0 channel of the involved wave functions are discussed.

  19. NUCLEAR PHYSICS: Equation of State for Isospin Asymmetric Matter of Nucleons and Deltas

    NASA Astrophysics Data System (ADS)

    Lu, Xiao-Hua; Zhang, Ying-Xun; Li, Zhu-Xia; Zhao, Zhi-Xiang

    2008-11-01

    An investigation on the equation of state of the isospin asymmetric, hot, dense matter of nucleons and deltas is performed based on the relativistic mean Geld theory. The QHD-II-type effective Lagrangian extending to the delta degree of freedom is adopted. Our results show that the equation of state is softened due to the inclusion of the delta degree of freedom. The baryon resonance isomer may occur depending on the delta-meson coupling. The results show that the densities for appearing the baryon resonance isomer, the densities for starting softening the equation of state and the extent of the softening depend not only on the temperature, the coupling strengths but also the isospin asymmetry of the baryon matter.

  20. The response of the polarized Fermi mixture to an artificial vector potential: The interaction strength and imbalance chemical potential effects

    NASA Astrophysics Data System (ADS)

    Ebrahimian, N.; Safiee, Z.

    2017-03-01

    We consider a polarized Fermi mixture (with normal-superfluid phase separation), subjected to artificial vector potential. We concentrate on the BCS regime with various interaction strengths and numerically obtain the polarisability of the system. We obtain the functional dependence of the polarisability of the system on frequency and the relevant physical parameters, namely the interaction strength, the mass ratio, the average and imbalance chemical potentials. Also, we find the special frequency (ωs), for which the rate of the response of system to the potential is changed and the cut-off frequency (ωcutoff), for which the response starts to become infinity. We investigate the behavior of the curves of polarisability versus proper physical parameters for ω <ωs and ωs < ω <ωcutoff at a nonzero temperature and interpret the existence of special and cut-off frequencies via the propagator concept (of particles or holes). Also, we offer the explanation of the minimum energy required for the occurrence of the pair-breaking process and the existence of the cut-off frequency, which is different with respect to the conventional superfluid Fermi gas, and is related to the relevant physical parameters. Finally, the system's response can be controlled by relevant physical parameters, such as interaction strength.

  1. Precise Determination of 40Ti Mass by Measuring the 40Sc Isospin Analogue State

    NASA Astrophysics Data System (ADS)

    Liu, Wei-Ping; Hellström, M.; Collatz, R.; Benlliure, J.; Chulkov, L.; Cortina Gil, D.; Farget, F.; Grawe, H.; Z., Hu; Iwasa, N.; Pfützner, M.; Piechaczek, A.; Raabe, R.; Reusen, I.; Roeckl, E.; Vancraeynest, G.; Wöhr, A.

    2001-11-01

    The mass of 40Ti has been determined by using the isobaric multiplet mass equation method. The experimental data of the 40Ti β-decay were used to determine the level of the isospin analogue state of 40Sc. The ground-state mass excess and the QEC value for 40Ti were determined to be -9060+/-12 keV and 11 466 +/- 13 keV, respectively.

  2. Potential Inhibitory Influence of miRNA 210 on Regulatory T Cells during Epicutaneous Chemical Sensitization

    PubMed Central

    Long, Carrie Mae; Lukomska, Ewa; Marshall, Nikki B.; Nayak, Ajay; Anderson, Stacey E.

    2016-01-01

    Toluene diisocyanate (TDI) is a potent low molecular weight chemical sensitizer and a leading cause of chemical-induced occupational asthma. The regulatory potential of microRNAs (miRNAs) has been recognized in a variety of disease states, including allergic disease; however, the roles of miRNAs in chemical sensitization are largely unknown. In a previous work, increased expression of multiple miRNAs during TDI sensitization was observed and several putative mRNA targets identified for these miRNAs were directly related to regulatory T-cell (Treg) differentiation and function including Foxp3 and Runx3. In this work, we show that miR-210 expression is increased in the mouse draining lymph node (dLN) and Treg subsets following dermal TDI sensitization. Alterations in dLN mRNA and protein expression of Treg related genes/putative miR-210 targets (foxp3, runx3, ctla4, and cd25) were observed at multiple time points following TDI exposure and in ex vivo systems. A Treg suppression assay, including a miR-210 mimic, was utilized to investigate the suppressive ability of Tregs. Cells derived from TDI sensitized mice treated with miR-210 mimic had less expression of miR-210 compared to the acetone control suggesting other factors, such as additional miRNAs, might be involved in the regulation of the functional capabilities of these cells. These novel findings indicate that miR-210 may have an inhibitory role in Treg function during TDI sensitization. Because the functional roles of miRNAs have not been previously elucidated in a model of chemical sensitization, these data contribute to the understanding of the potential immunologic mechanisms of chemical induced allergic disease. PMID:28035981

  3. Use of trophic magnification factors and related measures to characterize bioaccumulation potential of chemicals.

    PubMed

    Conder, Jason M; Gobas, Frank A P C; Borgå, Katrine; Muir, Derek C G; Powell, David E

    2012-01-01

    Recent technical workgroups have concluded that trophic magnification factors (TMFs) are useful in characterizing the bioaccumulation potential of a chemical, because TMFs provide a holistic measure of biomagnification in food webs. The objectives of this article are to provide a critical analysis of the application of TMFs for regulatory screening for bioaccumulation potential, and to discuss alternative methods for supplementing TMFs and assessing biomagnification in cases where insufficient data are available to determine TMFs. The general scientific consensus is that chemicals are considered bioaccumulative if they exhibit a TMF > 1. However, comparison of study-derived TMF estimates to this threshold value should be based on statistical analyses such that variability is quantified and false positive and false negative errors in classification of bioaccumulation potential are minimized. An example regulatory decision-making framework is presented to illustrate the use of statistical power analyses to minimize assessment errors. Suggestions for considering TMF study designs and TMFs obtained from multiple studies are also provided. Alternative bioaccumulation metrics are reviewed for augmenting TMFs and for substituting in situations in which field data for deriving TMFs are unavailable. Field-derived, trophic level-normalized biomagnification factors (BMF(TL) s), biota-sediment accumulation factors (BSAF(TL) s), and bioaccumulation factors (BAF(TL) s) are recommended if data are available, because these measures are most closely related to the biomagnification processes characterized by TMFs. Field- and laboratory-derived BAFs and bioconcentration factors are generally less accurate in predicting biomagnification. However, bioconcentration factors and BAFs remain useful for characterizing bioaccumulation as a result of the transfer of chemicals from abiotic environmental compartments to lower trophic levels. Modeling that incorporates available laboratory

  4. The potential of asteroseismology for probing the core chemical stratification in white dwarf stars

    NASA Astrophysics Data System (ADS)

    Giammichele, N.; Charpinet, S.; Brassard, P.; Fontaine, G.

    2017-02-01

    Context. The details of the C/O core structure in white dwarf stars has mostly remained inaccessible to the technique of asteroseismology, despite several attempts carried out in the past. Aims: We aim to re-assess the potential of asteroseismology for probing the chemical stratification in white dwarf cores, in light of new highly efficient tools recently developed for that purpose. Methods: Using the forward modeling approach and a new parameterization for the core chemical stratification in ZZ Ceti stars, we tested several situations typical of the usually limited constraints available, such as small numbers of observed independent modes, to carry out asteroseismology of these stars. Results: We find that, even with a limited number of modes, the core chemical stratification (in particular, the location of the steep chemical transitions expected in the oxygen profile) can be determined quite precisely due to the significant sensitivity of some confined modes to partial reflexion (trapping) effects. These effects are similar to the well known trapping induced by the shallower chemical transitions at the edge of the core and at the bottom of the H-rich envelope. We also find that success to unravel the core structure depends on the information content of the available seismic data. In some cases, it may not be possible to isolate a unique, well-defined seismic solution and the problem remains degenerate. Conclusions: Our results establish that constraining the core chemical stratification in white dwarf stars based solely on asteroseismology is possible, an opportunity that we have begun to exploit.

  5. Maternal Chemical and Drug Intolerances: Potential Risk Factors for Autism and Attention Deficit Hyperactivity Disorder (ADHD).

    PubMed

    Heilbrun, Lynne P; Palmer, Raymond F; Jaen, Carlos R; Svoboda, Melissa D; Perkins, Jimmy; Miller, Claudia S

    2015-01-01

    The aim of this study was to assess whether chemically intolerant women are at greater risk for having a child with autism spectrum disorders (ASD) or attention deficit hyperactivity disorder (ADHD). We conducted a case-control study of chemical intolerance among mothers of children with ASD (n = 282) or ADHD (n = 258) and children without these disorders (n = 154). Mothers participated in an online survey consisting of a validated chemical intolerance screening instrument, the Quick Environmental Exposure and Sensitivity Inventory (QEESI). Cases and controls were characterized by parental report of a professional diagnosis. We used a one-way, unbalanced analysis of variance to compare means across the 3 groups. Both mothers of children with ASD or ADHD had significantly higher mean chemical intolerance scores than did mothers of controls, and they were more likely to report adverse reactions to drugs. Chemically intolerant mothers were 3 times more likely (odds ratio, 3.01; 95% confidence interval, 1.50-6.02) to report having a child with autism or 2.3 times more likely (odds ratio, 2.3; 95% confidence interval, 1.12-5.04) to report a child with ADHD. Relative to controls, these mothers report their children are more prone to allergies (P < .02), have strong food preferences or cravings (P < .003), and have greater sensitivity to noxious odors (P < .04). These findings suggest a potential association between maternal chemical intolerance and a diagnosis of ADHD or ASD in their offspring. © Copyright 2015 by the American Board of Family Medicine.

  6. Most Plastic Products Release Estrogenic Chemicals: A Potential Health Problem That Can Be Solved

    PubMed Central

    Yang, Chun Z.; Yaniger, Stuart I.; Jordan, V. Craig; Klein, Daniel J.

    2011-01-01

    Background: Chemicals having estrogenic activity (EA) reportedly cause many adverse health effects, especially at low (picomolar to nanomolar) doses in fetal and juvenile mammals. Objectives: We sought to determine whether commercially available plastic resins and products, including baby bottles and other products advertised as bisphenol A (BPA) free, release chemicals having EA. Methods: We used a roboticized MCF-7 cell proliferation assay, which is very sensitive, accurate, and repeatable, to quantify the EA of chemicals leached into saline or ethanol extracts of many types of commercially available plastic materials, some exposed to common-use stresses (microwaving, ultraviolet radiation, and/or autoclaving). Results: Almost all commercially available plastic products we sampled—independent of the type of resin, product, or retail source—leached chemicals having reliably detectable EA, including those advertised as BPA free. In some cases, BPA-free products released chemicals having more EA than did BPA-containing products. Conclusions: Many plastic products are mischaracterized as being EA free if extracted with only one solvent and not exposed to common-use stresses. However, we can identify existing compounds, or have developed, monomers, additives, or processing agents that have no detectable EA and have similar costs. Hence, our data suggest that EA-free plastic products exposed to common-use stresses and extracted by saline and ethanol solvents could be cost-effectively made on a commercial scale and thereby eliminate a potential health risk posed by most currently available plastic products that leach chemicals having EA into food products. PMID:21367689

  7. Survey of the Anaerobic Biodegradation Potential of Organic Chemicals in Digesting Sludge

    PubMed Central

    Battersby, Nigel S.; Wilson, Valerie

    1989-01-01

    The degradation potential of 77 organic chemicals under methanogenic conditions was examined with an anaerobic digesting sludge from the United Kingdom. Degradation was assessed in terms of net total gas (CH4 plus CO2) produced, expressed as a percentage of the theoretical production (ThGP). The compounds tested were selected from various chemical groups and included substituted phenols and benzoates, pesticides, phthalic acid esters, homocyclic and heterocyclic ring compounds, glycols, and monosubstituted benzenes. The results obtained were in good agreement with published surveys of biodegradability in U.S. digesting sludges and other methanogenic environments. In general, the presence of chloro or nitro groups inhibited anaerobic gas production, while carboxyl and hydroxyl groups facilitated biodegradation. The relationship between substituent position and susceptibility to methanogenic degradation was compound dependent. The following chemicals were completely degraded (≥80% ThGP) at a concentration of 50 mg of carbon per liter: phenol, 2-aminophenol, 4-cresol, catechol, sodium benzoate, 4-aminobenzoic acid, 3-chlorobenzoic acid, phthalic acid, ethylene glycol, diethylene glycol, triethylene glycol, sodium stearate, and quinoline. 3-Cresol, 4-chlorobenzoic acid, dimethyl phthalate, and pyridine were partially degraded. Although the remaining chemicals tested were either persistent or toxic, their behavior may differ at more environmentally realistic chemical-to-biomass ratios. Our findings suggest that biodegradability assessments made with sludge from one source can be extrapolated to sludge from another source with a reasonable degree of confidence and should help in predicting the fate of an organic chemical during the anaerobic digestion of sewage sludge. PMID:16347851

  8. A new Skyrme energy density functional for a better description of spin-isospin resonances

    NASA Astrophysics Data System (ADS)

    Roca-Maza, X.; Colò, G.; Cao, Li-Gang; Sagawa, H.

    2015-10-01

    A correct determination of the isospin and spin-isospin properties of the nuclear effective interaction should lead to an accurate description of the Gamow-Teller resonance (GT), the Spin Dipole Resonance (SDR), the Giant Dipole Resonance (GDR) or the Antianalog Giant Dipole Resonance (AGDR), among others. A new Skyrme energy density functional named SAMi is introduced with the aim of going a step forward in setting the bases for a more precise description of spin-isospin resonances [1, 2]. In addition, we will discuss some new features of our analysis on the AGDR in 208Pb [3] as compared with available experimental data on this resonance [4, 5, 6], and on the GDR [7]. Such study, guided by a simple yet physical pocket formula, has been developed by employing the so called SAMi-J family of systematically varied interactions. This set of interactions is compatible with experimental data for values of the symmetry energy at saturation J and slope parameter L falling in the ranges 31-33 MeV and 75-95 MeV, respectively.

  9. A new Skyrme energy density functional for a better description of spin-isospin resonances

    SciTech Connect

    Roca-Maza, X.; Colò, G.; Cao, Li-Gang; Sagawa, H.

    2015-10-15

    A correct determination of the isospin and spin-isospin properties of the nuclear effective interaction should lead to an accurate description of the Gamow-Teller resonance (GT), the Spin Dipole Resonance (SDR), the Giant Dipole Resonance (GDR) or the Antianalog Giant Dipole Resonance (AGDR), among others. A new Skyrme energy density functional named SAMi is introduced with the aim of going a step forward in setting the bases for a more precise description of spin-isospin resonances [1, 2]. In addition, we will discuss some new features of our analysis on the AGDR in {sup 208}Pb [3] as compared with available experimental data on this resonance [4, 5, 6], and on the GDR [7]. Such study, guided by a simple yet physical pocket formula, has been developed by employing the so called SAMi-J family of systematically varied interactions. This set of interactions is compatible with experimental data for values of the symmetry energy at saturation J and slope parameter L falling in the ranges 31−33 MeV and 75−95 MeV, respectively.

  10. Isospin Symmetry Breaking within the HLS Model: A Full (rho, omega, phi) Mixing Scheme

    SciTech Connect

    O'Connell, Heath B

    2001-07-16

    We study the way isospin symmetry violation can be generated within the Hidden Local Symmetry (HLS) Model. We show that isospin symmetry breaking effects on pseudoscalar mesons naturally induces correspondingly effects within the physics of vector mesons, through kaon loops. In this way, one recovers all features traditionally expected from {rho}-{omega} mixing and one finds support for the Orsay phase modeling of the e{sup +}e{sup -} {yields} {pi}{sup +}{pi}{sup -} amplitude. We then examine an effective procedure which generates mixing in the whole {rho}, {omega}, {phi} sector of the HLS Model. The corresponding model allows us to account for all two body decays of light mesons accessible to the HLS model in modulus and phase, leaving aside the {rho} {yields} {pi}{pi} and K* {yields} K{pi} modes only, which raise a specific problem. Comparison with experimental data is performed and covers modulus and phase information; this represents 26 physics quantities successfully described with very good fit quality within a constrained model which accounts for SU(3) breaking, nonet symmetry breaking in the pseudoscalar sector and, now, isospin symmetry breaking.

  11. Isospin violation in ϕ, J/ψ, ψ'→ωπ0 via hadronic loops

    NASA Astrophysics Data System (ADS)

    Li, Gang; Zhao, Qiang; Zou, Bing-Song

    2008-01-01

    In this work, we study the isospin-violating decay of ϕ→ωπ0 and quantify the electromagnetic (EM) transitions and intermediate meson exchanges as two major sources of the decay mechanisms. In the EM decays, the present datum status allows a good constraint on the EM decay form factor in the vector meson dominance model, and it turns out that the EM transition can only account for about 1/4˜1/3 of the branching ratio for ϕ→ωπ0. The intermediate meson exchanges, KK¯(K*) (intermediate KK¯ interaction via K* exchanges), KK¯*(K) (intermediate KK¯* rescattering via kaon exchanges), and KK¯*(K*) (intermediate KK¯* rescattering via K* exchanges), which evade the naive Okubo-Zweig-Iizuka rule, serve as another important contribution to the isospin violations. They are evaluated with effective Lagrangians where explicit constraints from experiment can be applied. Combining these three contributions, we obtain results in good agreement with the experimental data. This approach is also extended to J/ψ(ψ')→ωπ0, where we find contributions from the KK¯(K*), KK¯*(K), and KK¯*(K*) loops are negligibly small, and the isospin violation is likely to be dominated by the EM transition.

  12. Structural and isospin effects on balance energy and transition energy via different nuclear charge radii parameterizations

    NASA Astrophysics Data System (ADS)

    Sangeeta; Kaur, Varinderjit

    2017-10-01

    The structural and isospin effects have been studied through isospin dependent and independent nuclear charge radii parameterizations on the collective flow within the framework of Isospin-dependent Quantum Molecular Dynamics (IQMD) model. The calculations have been carried out by using two approaches: (i) for the reaction series having fixed N / Z ratio and (ii) for the isobaric reaction series with different N / Z ratio. Our results indicate that there is a considerable effect of radii parameterizations on the excitation function of reduced flow (∂v1/∂Yred) and elliptical flow (v2). Both balance energy (Ebal) and transition energy (Etrans) are enhanced with increase in radii of reacting nuclei and found to follow a power law with nuclear charge radii. The exponent τ values show that the elliptical flow is more sensitive towards different nuclear charge radii as compared to reduced flow. Moreover, we observe that our theoretical calculation of Ebal and Etrans are in agreement with the experimental data provided by GSI, INDRA and FOPI collaborations.

  13. The isospin dependent nucleon-nucleon inelastic cross section in the nuclear medium

    NASA Astrophysics Data System (ADS)

    Li, Qingfeng; Li, Zhuxia

    2017-10-01

    The calculation of the energy-, density-, and isospin-dependent Δ production cross sections in nucleon-nucleon (NN) scattering σNN→ NΔ * has been performed within the framework of the relativistic BUU approach. The NΔ cross sections are calculated in Born approximation taking into account the effective mass splitting of the nucleons and Δs in asymmetric matter. Due to the different mass splitting for neutron, proton and differently charged Δs, it is shown that, similar to the NN elastic ones, the reductions of NΔ inelastic cross sections in isospin-asymmetric nuclear medium are different from each other for all the individual channels and the effect is largest and of opposite sign for the Δ++ and Δ- states. This approach is also compared to calculations without effective mass splitting and with splitting derived from Dirac-Brueckerner (DB) calculations. The isospin dependence of the NΔ cross sections is expected to influence the production of π+ and π- mesons as well as their yield ratio, and thus affect the use of the latter quantity as a probe of the stiffness of the symmetry energy at supranormal densities.

  14. Methods of analysis for chemicals that disrupt cellular signaling pathways: risk assessment for potential endocrine disruptors.

    PubMed

    Umezawa, Yoshio; Ozawa, Takeaki; Sato, Moritoshi; Inadera, Hidekuni; Kaneko, Shuichi; Kunimoto, Manabu; Hashimoto, Shin-ichi

    2005-01-01

    Here we present a basic concept and several examples of methods of analysis for chemicals that disrupt cellular signaling pathways, in view of risk assessment for potential endocrine disrupting chemicals (EDCs). The key cellular signaling pathways include 1) ER/coactivator interaction, 2) AR translocation into the nucleus, 3) ER/NO/sGC/cGMP, 4) ER/Akt, 5) ER/Src, 6)ER/Src/Grb2, and 7) ER/Ca2+/CaM/CaMK pathways. These were visualized in relevant live cells using newly developed fluorescent and bioluminescent probes. Changes in cellular signals were thereby observed in nongenomic pathways of steroid hormones upon treatment of the target cells with steroid hormones and related chemicals. This method of analysis appears to be a rational approach to high-throughput prescreening (HTPS) of biohazardous chemicals, EDCs, in particular. Also described was the screening of gene expression by serial analysis of gene expression and gene chips upon applying EDCs to breast cancer cells, mouse livers, and human neuroblastoma NB-1 cells.

  15. Development of structure-activity relationship rules for predicting carcinogenic potential of chemicals.

    PubMed

    Woo, Y T; Lai, D Y; Argus, M F; Arcos, J C

    1995-09-01

    Since the inception of Section 5 (Premanufacturing/Premarketing Notification, PMN) of the Toxic Substances Control Act (TSCA), structure-activity relationship (SAR) analysis has been effectively used by U.S. Environmental Protection Agency's (EPA) Structure Activity Team (SAT) in the assessment of potential carcinogenic hazard of new chemicals for which test data are not available. To capture, systematize and codify the Agency's predictive expertise in order to make it more widely available to assessors outside the TSCA program, a cooperative project was initiated to develop a knowledge rule-based expert system to mimic the thinking and reasoning of the SAT. In this communication, we describe the overall structure of this expert system, discuss the scientific bases and principles of SAR analysis of chemical carcinogens used in the development of SAR knowledge rules, and delineate the major factors/rules useful for assessing the carcinogenic potential of fibers, polymers, metals/metalloids and several major classes of organic chemicals. An integrative approach using available short-term predictive tests and non-cancer toxicological data to supplement SAR analysis has also been described.

  16. A Comprehensive Review on Chemical Profiling of Nelumbo Nucifera: Potential for Drug Development.

    PubMed

    Sharma, Bhesh Raj; Gautam, Lekh Nath S; Adhikari, Deepak; Karki, Rajendra

    2017-01-01

    Nelumbo nucifera, also known as sacred lotus, has primarily been used as food throughout the Asian continent, and its medicinal values have been described in Ayurvedic and Traditional Chinese Medicine. The purpose of this study is to systematically characterize the chemical profiling and pharmacological activities of N. nucifera. Herein, we critically reviewed and analysed the phytochemical and pharmacological reports of N. nucifera. Our search for the keyword 'Nelumbo nucifera pharmacology' in all databases reported in Web of Science yielded 373 results excluding reviews and abstracts in document types. Two hundred and forty-three spectrum natural compounds from different parts of N. nucifera belonging to diverse chemical groups, including alkaloids, flavonoids, glycosides, terpenoids, steroids, fatty acids, proteins, minerals, and vitamins have been reported. In addition, distinct pharmacological activities, mainly against cancer, microbial infection, diabetes, inflammation, atherosclerosis, and obesity, have been associated with crude extracts, fractions, and isolated compounds. This review highlights potential use of neferine, liensinine, isoliensinine, and nuciferine in clinical trials. In depth, mechanism of the potential chemical entities from N. nucifera via structure activity relationship needs to be explored to guarantee the stability and safety for the clinical use. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  17. Adsorption-desorption kinetics and chemical potential of adsorbed and gas-phase particles

    NASA Astrophysics Data System (ADS)

    Zhdanov, V. P.

    2001-03-01

    In the literature, one can find two alternative ways of using the chemical potential of adsorbed and gas-phase particles, μa and μg, for describing the adsorption-desorption kinetics. According to the first approach, the desorption rate depends only on μa. The second approach, proposed by Ward et al. in a series of papers published in the Journal of Chemical Physics, predicts that the desorption rate is proportional to exp[(μa-μg)/kBT]. Scrutinizing the formalism used by Ward et al., we show that the latter dependence makes no sense because it contradicts the basic principles of the general theory of activated rate processes.

  18. Measuring the Chemical Potential of the Martian Regolith to Generate and Sustain Life

    NASA Astrophysics Data System (ADS)

    Kounaves, S. P.; Buehler, M. G.; Kuhlman, K. R.

    1999-01-01

    A critical component for identifying chemical biosignatures is the ability to assess in-situ the potential of an aqueous geochemical environment to generate and sustain life. On Mars or other solar bodies, in-situ chemical characterization could provide evidence as to whether the chemical composition of the regolith or evaporites in suspected ancient water bodies have been biologically influenced or possess the chemical parameters within which life may have existed, or may still exist. A variety of analytical techniques have been proposed for use in detecting and identify signatures of past or present life. These techniques fall into two groups; visual observation with instruments such as cameras or optical/atomic-force microscopes; or elemental chemical analysis with such instruments as X-ray fluorescence (XRF) and diffraction (XRD), a-proton backscatter (APX), y-ray, Mossbauer, Raman, IR, UV/VIS spectroscopies, gas chromatography (GC), or mass spectrometry (MS). Direct observation of an identifiable lifeform by the first set of instruments in a single sample is highly unlikely, especially for extinct organisms or on the surface. The later instruments can provide vital data as to the elemental mineralogy and geological history of the planet, but are highly inadequate for understanding the chemistry of the planet in terms of indigenous life or interactions with human explorers. Techniques such as XRD, XRF, and APX, provide elemental composition at high limits of detection. Some of this data can be extrapolated or interpolated to provide chemical parameters such as oxidation state or composition. Gas chromatography (GC) without standards and non-specific detectors, has little chance of identifying a mixture of unknown components. Combined with GC or by itself, mass spectrometry (MS) can provide identification of compounds, but in both cases the sample must be appropriately prepared for accurate and reliable analysis. Life as we know it, and probably identify it as

  19. Measuring the Chemical Potential of the Martian Regolith to Generate and Sustain Life

    NASA Technical Reports Server (NTRS)

    Kounaves, S. P.; Buehler, M. G.; Kuhlman, K. R.

    1999-01-01

    A critical component for identifying chemical biosignatures is the ability to assess in-situ the potential of an aqueous geochemical environment to generate and sustain life. On Mars or other solar bodies, in-situ chemical characterization could provide evidence as to whether the chemical composition of the regolith or evaporites in suspected ancient water bodies have been biologically influenced or possess the chemical parameters within which life may have existed, or may still exist. A variety of analytical techniques have been proposed for use in detecting and identify signatures of past or present life. These techniques fall into two groups; visual observation with instruments such as cameras or optical/atomic-force microscopes; or elemental chemical analysis with such instruments as X-ray fluorescence (XRF) and diffraction (XRD), a-proton backscatter (APX), y-ray, Mossbauer, Raman, IR, UV/VIS spectroscopies, gas chromatography (GC), or mass spectrometry (MS). Direct observation of an identifiable lifeform by the first set of instruments in a single sample is highly unlikely, especially for extinct organisms or on the surface. The later instruments can provide vital data as to the elemental mineralogy and geological history of the planet, but are highly inadequate for understanding the chemistry of the planet in terms of indigenous life or interactions with human explorers. Techniques such as XRD, XRF, and APX, provide elemental composition at high limits of detection. Some of this data can be extrapolated or interpolated to provide chemical parameters such as oxidation state or composition. Gas chromatography (GC) without standards and non-specific detectors, has little chance of identifying a mixture of unknown components. Combined with GC or by itself, mass spectrometry (MS) can provide identification of compounds, but in both cases the sample must be appropriately prepared for accurate and reliable analysis. Life as we know it, and probably identify it as

  20. Structure and stability of pyrophyllite edge surfaces: Effect of temperature and water chemical potential

    NASA Astrophysics Data System (ADS)

    Kwon, Kideok D.; Newton, Aric G.

    2016-10-01

    The surfaces of clay minerals, which are abundant in atmospheric mineral dust, serve as an important medium to catalyze ice nucleation. The lateral edge surface of 2:1 clay minerals is postulated to be a potential site for ice nucleation. However, experimental investigations of the edge surface structure itself have been limited compared to the basal planes of clay minerals. Density functional theory (DFT) computational studies have provided insights into the pyrophyllite edge surface. Pyrophyllite is an ideal surrogate mineral for the edge surfaces of 2:1 clay minerals as it possesses no or little structural charge. Of the two most-common hydrated edge surfaces, the AC edge, (1 1 0) surface in the monoclinic polytype notation, is predicted to be more stable than the B edge, (0 1 0) surface. These stabilities, however, were determined based on the total energies calculated at 0 K and did not consider environmental effects such as temperature and humidity. In this study, atomistic thermodynamics based on periodic DFT electronic calculations was applied to examine the effects of environmental variables on the structure and thermodynamic stability of the common edge surfaces in equilibrium with bulk pyrophyllite and water vapor. We demonstrate that the temperature-dependent vibrational energy of sorbed water molecules at the edge surface is a significant component of the surface free energy and cannot be neglected when determining the surface stability of pyrophyllite. The surface free energies were calculated as a function of temperature from 240 to 600 K and water chemical potential corresponding to conditions from ultrahigh vacuum to the saturation vapor pressure of water. We show that at lower water chemical potentials (dry conditions), the AC and B edge surfaces possessed similar stabilities; at higher chemical potentials (humid conditions) the AC edge surface was more stable than the B edge surface. At high temperatures, both surfaces showed similar stabilities

  1. Expanding the test set: Chemicals with potential to disrupt mammalian brain development.

    PubMed

    Mundy, William R; Padilla, Stephanie; Breier, Joseph M; Crofton, Kevin M; Gilbert, Mary E; Herr, David W; Jensen, Karl F; Radio, Nicholas M; Raffaele, Kathleen C; Schumacher, Kelly; Shafer, Timothy J; Cowden, John

    2015-01-01

    High-throughput test methods including molecular, cellular, and alternative species-based assays that examine critical events of normal brain development are being developed for detection of developmental neurotoxicants. As new assays are developed, a "training set" of chemicals is used to evaluate the relevance of individual assays for specific endpoints. Different training sets are necessary for each assay that would comprise a developmental neurotoxicity test battery. In contrast, evaluation of the predictive ability of a comprehensive test battery requires a set of chemicals that have been shown to alter brain development after in vivo exposure ("test set"). Because only a small number of substances have been well documented to alter human neurodevelopment, we have proposed an expanded test set that includes chemicals demonstrated to adversely affect neurodevelopment in animals. To compile a list of potential developmental neurotoxicants, a literature review of compounds that have been examined for effects on the developing nervous system was conducted. The search was limited to mammalian studies published in the peer-reviewed literature and regulatory studies submitted to the U.S. EPA. The definition of developmental neurotoxicity encompassed changes in behavior, brain morphology, and neurochemistry after gestational or lactational exposure. Reports that indicated developmental neurotoxicity was observed only at doses that resulted in significant maternal toxicity or were lethal to the fetus or offspring were not considered. As a basic indication of reproducibility, we only included a chemical if data on its developmental neurotoxicity were available from more than one laboratory (defined as studies originating from laboratories with a different senior investigator). Evidence from human studies was included when available. Approximately 100 developmental neurotoxicity test set chemicals were identified, with 22% having evidence in humans. Published by Elsevier

  2. Critical end point in the presence of a chiral chemical potential

    NASA Astrophysics Data System (ADS)

    Cui, Z.-F.; Cloët, I. C.; Lu, Y.; Roberts, C. D.; Schmidt, S. M.; Xu, S.-S.; Zong, H.-S.

    2016-10-01

    A class of Polyakov-loop-modified Nambu-Jona-Lasinio models has been used to support a conjecture that numerical simulations of lattice-regularized QCD defined with a chiral chemical potential can provide information about the existence and location of a critical end point in the QCD phase diagram drawn in the plane spanned by baryon chemical potential and temperature. That conjecture is challenged by conflicts between the model results and analyses of the same problem using simulations of lattice-regularized QCD (lQCD) and well-constrained Dyson-Schwinger equation (DSE) studies. We find the conflict is resolved in favor of the lQCD and DSE predictions when both a physically motivated regularization is employed to suppress the contribution of high-momentum quark modes in the definition of the effective potential connected with the Polyakov-loop-modified Nambu-Jona-Lasinio models and the four-fermion coupling in those models does not react strongly to changes in the mean field that is assumed to mock-up Polyakov-loop dynamics. With the lQCD and DSE predictions thus confirmed, it seems unlikely that simulations of lQCD with μ5>0 can shed any light on a critical end point in the regular QCD phase diagram.

  3. Chemical Analyses of Wasp-Associated Streptomyces Bacteria Reveal a Prolific Potential for Natural Products Discovery

    PubMed Central

    Clardy, Jon; Currie, Cameron R.

    2011-01-01

    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. PMID:21364940

  4. TANK VAPOR CHEMICALS OF POTENTIAL CONCERN & EXISTING DIRECT READING INSTRUMENTION & PERSONAL PROTECTIVE EQUIPMENT CONSIDERATIONS

    SciTech Connect

    BUTLER, N.K.

    2004-11-01

    This document takes the newly released Industrial Hygiene Chemical Vapor Technical Basis (RPP-22491) and evaluates the chemicals of potential concern (COPC) identified for selected implementation actions by the industrial hygiene organization. This document is not intended as a hazard analysis with recommended controls for all tank farm activities. Not all of the chemicals listed are present in all tanks; therefore, hazard analyses can and should be tailored as appropriate. Detection of each chemical by current industrial hygiene non-specific instrumentation in use at the tank farms is evaluated. Information gaps are identified and recommendations are made to resolve these needs. Of the 52 COPC, 34 can be detected with existing instrumentation. Three additional chemicals could be detected with a photoionization detector (PID) equipped with a different lamp. Discussion with specific instrument manufacturers is warranted. Consideration should be given to having the SapphIRe XL customized for tank farm applications. Other instruments, sampling or modeling techniques should be evaluated to estimate concentrations of chemicals not detected by direct reading instruments. In addition, relative instrument response needs to be factored in to action levels used for direct reading instruments. These action levels should be correlated to exposures to the COPC and corresponding occupational exposure limits (OELs). The minimum respiratory protection for each of the COPC is evaluated against current options. Recommendations are made for respiratory protection based on each chemical. Until exposures are sufficiently quantified and analyzed, the current use of supplied air respiratory protection is appropriate and protective for the COPC. Use of supplied air respiratory protection should be evaluated once a detailed exposure assessment for the COPC is completed. The established tank farm OELs should be documented in the TFC-PLN-34. For chemicals without an established tank farm OEL

  5. Diquarks in the nilpotency expansion of QCD and their role at finite chemical potential

    NASA Astrophysics Data System (ADS)

    Caracciolo, Sergio; Palumbo, Fabrizio

    2012-05-01

    We assume that the most important quark correlations are pairwise at all baryon densities. We introduce correlated pairs by means of Bogoliubov transformations which are functions of time and spatial gauge fields, in the formalism of the transfer matrix with lattice regularization. The dependence on time and gauge fields allows us to enforce gauge invariance and other symmetries in the transformed quantities in the same way as in the original ones. We derive the quark contribution to the free energy at finite chemical potential in a certain approximation. Its expression cannot be evaluated analytically, but it has a definite sign.

  6. Correlation Between the Atomic and Bulk Chemical Potentials of Low work Function Metals

    SciTech Connect

    Drummond, T.J.

    1998-12-22

    An attempt is made to identify preferred values for the work functions of the rare earth elements by correlating the atomic chemical potential with the work function of the bulk elements. Trends in the alkali and alkali earth metal are evaluated in the same context. Strong linear correlation between the two quantities is observed within the IA, 11A, and IIIB (Se, Y, La) groups. Within the lanthanide series the nature of the correlation between the metallic radius and the work function suggests a dependence on the total angular momentum.

  7. Chemical constituents and potential cytotoxic activity of n-hexane fraction from Myristica fatua Houtt leaves

    NASA Astrophysics Data System (ADS)

    Fajriah, S.; Megawati, Hudiyono, S.; Kosela, S.; Hanafi, M.

    2017-07-01

    The aims of this research were to determine the chemical constituents of n- hexane fraction from Myristica fatua Houtt leaves by Gas Chromatograpy/Mass Spectrometry (GC/MS) and their cytotoxic activities against MCF-7 cell lines. The results indicated that sesquiterpenes and fatty acids were major compounds of this fraction, there were trans-calamenene (17.75 %), hexadecanoic acid (11.14 %), caryophyllene (7.49 %), α-muurolene (6.99 %), and γ-muurolene (6.60 %). In vitro anticancer activity test against breast cancer MCF-7 cell lines showed potential cytotoxic at IC50 2.19 μg/mL.

  8. Computed Potential Energy Surfaces and Minimum Energy Pathway for Chemical Reactions

    NASA Technical Reports Server (NTRS)

    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.

  9. Nexus between quantum criticality and the chemical potential pinning in high- Tc cuprates

    NASA Astrophysics Data System (ADS)

    Kopeć, T. K.

    2005-08-01

    For strongly correlated electrons the relation between total number of charge carriers ne and the chemical potential μ reveals for large Coulomb energy the apparently paradoxical pinning of μ within the Mott gap, as observed in high- Tc cuprates. By unraveling consequences of the nontrivial topology of the charge gauge U(1) group and the associated ground state degeneracy we found a close kinship between the pinning of μ and the zero-temperature divergence of the charge compressibility κ˜∂ne/∂μ , which marks a novel quantum criticality governed by topological charges rather than Landau principle of the symmetry breaking.

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

    PubMed

    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, N2, CH4, SF6, H2, H2O) 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.

  11. Full simulation of chiral random matrix theory at nonzero chemical potential by complex Langevin

    NASA Astrophysics Data System (ADS)

    Mollgaard, A.; Splittorff, K.

    2015-02-01

    It is demonstrated that the complex Langevin method can simulate chiral random matrix theory at nonzero chemical potential. The successful match with the analytic prediction for the chiral condensate is established through a shift of matrix integration variables and choosing a polar representation for the new matrix elements before complexification. Furthermore, we test the proposal to work with a Langevin-time-dependent quark mass and find that it allows us to control the fluctuations of the phase of the fermion determinant throughout the Langevin trajectory.

  12. Critical line from imaginary to real baryonic chemical potentials in two-color QCD

    SciTech Connect

    Cea, Paolo; Cosmai, Leonardo; D'Elia, Massimo; Papa, Alessandro

    2008-03-01

    The method of analytic continuation from imaginary to real chemical potentials {mu} is one of the few available techniques to study QCD at finite temperature and baryon density. One of its most appealing applications is the determination of the critical line for small {mu}: we perform a direct test of the validity of the method in this case by studying two-color QCD, where the sign problem is absent. The (pseudo)critical line is found to be analytic around {mu}{sup 2}=0, but a very large precision would be needed at imaginary {mu} to correctly predict the location of the critical line at real {mu}.

  13. Computed Potential Energy Surfaces and Minimum Energy Pathway for Chemical Reactions

    NASA Technical Reports Server (NTRS)

    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.

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

    PubMed Central

    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

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

    NASA Astrophysics Data System (ADS)

    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.

  16. A decision analysis framework for estimating the potential hazards for drinking water resources of chemicals used in hydraulic fracturing fluids.

    PubMed

    Yost, Erin E; Stanek, John; Burgoon, Lyle D

    2017-01-01

    Despite growing concerns over the potential for hydraulic fracturing to impact drinking water resources, there are limited data available to identify chemicals used in hydraulic fracturing fluids that may pose public health concerns. In an effort to explore these potential hazards, a multi-criteria decision analysis (MCDA) framework was employed to analyze and rank selected subsets of these chemicals by integrating data on toxicity, frequency of use, and physicochemical properties that describe transport in water. Data used in this analysis were obtained from publicly available databases compiled by the United States Environmental Protection Agency (EPA) as part of a larger study on the potential impacts of hydraulic fracturing on drinking water. Starting with nationwide hydraulic fracturing chemical usage data from EPA's analysis of the FracFocus Chemical Disclosure Registry 1.0, MCDAs were performed on chemicals that had either noncancer toxicity values (n=37) or cancer-specific toxicity values (n=10). The noncancer MCDA was then repeated for subsets of chemicals reported in three representative states (Texas, n=31; Pennsylvania, n=18; and North Dakota, n=20). Within each MCDA, chemicals received scores based on relative toxicity, relative frequency of use, and physicochemical properties (mobility in water, volatility, persistence). Results show a relative ranking of these chemicals based on hazard potential, and provide preliminary insight into chemicals that may be more likely than others to impact drinking water resources. Comparison of nationwide versus state-specific analyses indicates regional differences in the chemicals that may be of more concern to drinking water resources, although many chemicals were commonly used and received similar overall hazard rankings. Several chemicals highlighted by these MCDAs have been reported in groundwater near areas of hydraulic fracturing activity. This approach is intended as a preliminary analysis, and represents one

  17. Predictive performance of the Short Time Exposure test for identifying eye irritation potential of chemical mixtures.

    PubMed

    Saito, Kazutoshi; Miyazawa, Masaaki; Nukada, Yuko; Ei, Kyo; Abo, Takayuki; Sakaguchi, Hitoshi

    2015-04-01

    The Short Time Exposure (STE) test is an in vitro eye irritation test based on the cytotoxicity in SIRC cells (rabbit corneal cell line) following a 5 min treatment of chemicals. This study evaluated the predictive performance of the STE test to identify the globally harmonized system (GHS) Not Classified category and other irritant categories (i.e., GHS Category 1 or 2) when used to test 40 chemical mixtures that included irritants. The STE test correctly identified 30 tested mixtures classified as GHS irritant categories and 5 out of 10 tested mixtures classified as GHS Not Classified. The sensitivity, specificity, positive predictivity, negative predictivity, and overall accuracy of the STE test were 100% (30/30), 50% (5/10), 86% (25/30), 100% (5/5), and 88% (35/40), respectively. These predictive performances were comparative to or greater than those in other in vitro eye irritation tests that have been accepted as test guideline by the Organisation for Economic Co-operation and Development. This suggests that the STE test has sufficient predictivity for identifying the eye irritation potential of chemical mixtures. Since no false negatives in this study were found, this indicates that the STE test is applicable as a part of the bottom-up approach. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. The international register of potentially toxic chemicals : Challenges of data collection in the field of toxicology.

    PubMed

    Caroli, S; Menditto, A; Chiodo, F

    1996-06-01

    The benefits and drawbacks consequent to the widespread use of chemicals are inextricably interwoven. According to recent estimates, more than 8 million substances are presently known, 70,000 of which are in common use as industrial compounds, pesticides, Pharmaceuticals, food additives, cosmetics and the like. It is estimated that substances used as such will increase annually by 1000 in number. The deleterious consequences deriving from their exploitation pose tremendous challenges to the scientific community for the protection of human health and the environment. Therefore it is of utmost priority to appropriately select valid information generated in this investigation area and to convey it correctly to users. Here, the adoption of the principles of good laboratory practice in experimental activities is essential, as well as the creation of global networks for data exchange on the safe use of chemicals. The structure and goals of the International Register of Potentially Toxic Chemicals (IRPTC, the database of the United Nations Environment Programme) are detailed to give an example of such an undertaking. Seventeen fields are covered,i.e. identifiers, properties and classification, production/trade, production processes, use, pathways into the environment, concentrations, environmental fate tests, environmental fate, chemobiokinetics, mammalian toxicity, special toxicity studies, effects on organisms in the environment, sampling/preparation/analysis, spills, treatment of poisoning, waste management and recommendations/legal mechanisms.

  19. Investigation of the potential uses of plasma processing in the United States chemical industry

    SciTech Connect

    Estey, P.N.

    1985-01-01

    This thesis describes a systematic approach to determine the potential for high pressure (thermal) plasma processing in the United States chemical industry. A model was developed that describes the physical inputs and outputs of a plasma-based processing system. This model consists of an empirical model of an electric arc heater and an analytical model of the reaction chamber into which the arc heater gas flows. The reaction chamber model comprises the conservation equations of one-dimensional fluid flow including the effects of chemical kinetics, particle and gas injection, and convective and radiative heat transfer. These complex equations were solved numerically. An engineering economic analysis of the plasma process was performed when favorable results existed for the mass and energy flows to and from the plasma arc heater/reaction chamber model. This analysis was used to determine if the plasma process is or can be competitive with conventional technology. Five cases were studied as examples of plasma-based chemical processing: nitric acid production, hydrogen cyanide synthesis, silicon refining, titanium dioxide production, and reductant gas synthesis from residual fuel oil.

  20. An Investigation of the Potential Uses of Plasma Processing in the United States Chemical Industry

    NASA Astrophysics Data System (ADS)

    Estey, Paul Norman

    This thesis describes a systematic approach to determine the potential for high pressure (thermal) plasma processing in the United States chemical industry. A model was developed that describes the physical inputs and outputs of a plasma-based processing system. This model consists of an empirical model of an electric arc heater and an analytical model of the reaction chamber into which the arc heater gas flows. The reaction chamber model comprises the conservation equations of one-dimensional fluid flow including the effects of chemical kinetics, particle and gas injection, and convective and radiative heat transfer. These complex equations were solved numerically. An engineering economic analysis of the plasma process was performed when favorable results existed for the mass and energy flows to and from the plasma arc heater/reaction chamber model. This analysis was used to determine if the plasma process is or can be competitive with conventional technology. Five cases were studied as examples of plasma -based chemical processing: nitric acid production, hydrogen cyanide synthesis, silicon refining, titanium dioxide production, and reductant gas synthesis from residual fuel oil.

  1. Chemical validation of trypanothione synthetase: a potential drug target for human trypanosomiasis.

    PubMed

    Torrie, Leah S; Wyllie, Susan; Spinks, Daniel; Oza, Sandra L; Thompson, Stephen; Harrison, Justin R; Gilbert, Ian H; Wyatt, Paul G; Fairlamb, Alan H; Frearson, Julie A

    2009-12-25

    In the search for new therapeutics for the treatment of human African trypanosomiasis, many potential drug targets in Trypanosoma brucei have been validated by genetic means, but very few have been chemically validated. Trypanothione synthetase (TryS; EC 6.3.1.9; spermidine/glutathionylspermidine:glutathione ligase (ADP-forming)) is one such target. To identify novel inhibitors of T. brucei TryS, we developed an in vitro enzyme assay, which was amenable to high throughput screening. The subsequent screen of a diverse compound library resulted in the identification of three novel series of TryS inhibitors. Further chemical exploration resulted in leads with nanomolar potency, which displayed mixed, uncompetitive, and allosteric-type inhibition with respect to spermidine, ATP, and glutathione, respectively. Representatives of all three series inhibited growth of bloodstream T. brucei in vitro. Exposure to one of our lead compounds (DDD86243; 2 x EC(50) for 72 h) decreased intracellular trypanothione levels to <10% of wild type. In addition, there was a corresponding 5-fold increase in the precursor metabolite, glutathione, providing strong evidence that DDD86243 was acting on target to inhibit TryS. This was confirmed with wild-type, TryS single knock-out, and TryS-overexpressing cell lines showing expected changes in potency to DDD86243. Taken together, these data provide initial chemical validation of TryS as a drug target in T. brucei.

  2. Efficacy of potential chemical control compounds for removing invasive American bullfrogs (Rana catesbeiana).

    PubMed

    Witmer, Gary W; Snow, Nathan P; Moulton, Rachael S

    2015-01-01

    Invasive American bullfrogs [Rana catesbeiana (Lithobates catesbeianus)] are outcompeting and predating on native biota and contributing to reductions in biodiversity worldwide. Current methods for controlling American bullfrogs are incapable of stopping their expansion, thus more cost-effective and broadly applicable methods are needed. Although chemical control compounds have been identified as effective for removing other invasive amphibians, none have been tested for American bullfrogs. Our objective was to expand on previous research and test the efficacy of 10 potential chemical control compounds for removing invasive American bullfrogs. After a dermal spray-application of 4 ml, we found 3 compounds (i.e., chloroxylenol, rotenone with permethrin, and caffeine) at 5-10 % concentrations in water were 100 % lethal for adult American bullfrogs. Chloroxylenol and rotenone with permethrin were fast acting with time-to-death <2 h. This research presents a first-step toward incorporating chemical control as part of integrated pest management strategy for controlling invasive American bullfrogs. Follow-up studies on delivery systems and reducing non-target hazards should ensue with these compounds to confirm their effectiveness and safety for removing invasive American bullfrogs.

  3. Predicting the Absorption Potential of Chemical Compounds through a Deep Learning Approach.

    PubMed

    Shin, Moonshik; Jang, Dongjin; Nam, Hojung; Lee, Kwang Hyung; Lee, Doheon

    2016-02-26

    The human colorectal carcinoma cell line (Caco-2) is a commonly used in-vitro test that predicts the absorption potential of orally administered drugs. In-silico prediction methods, based on the Caco-2 assay data, may increase the effectiveness of the high-throughput screening of new drug candidates. However, previously developed in-silico models that predict the Caco-2 cellular permeability of chemical compounds use handcrafted features that may be dataset-specific and induce over-fitting problems. Deep Neural Network (DNN) generates high-level features based on non-linear transformations for raw features, which provides high discriminant power and, therefore, creates a good generalized model. We present a DNNbased binary Caco-2 permeability classifier. Our model was constructed based on 663 chemical compounds with in-vitro Caco-2 apparent permeability data. 209 molecular descriptors are used for generating the high-level features during DNN model generation. Dropout regularization is applied to solve the over-fitting problem and the non-linear activation. The Rectified Linear Unit (ReLU) is adopted to reduce the vanishing gradient problem. The results demonstrate that the high-level features generated by the DNN are more robust than handcrafted features for predicting the cellular permeability of structurally diverse chemical compounds in Caco-2 cell lines.

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

    PubMed

    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.

  5. Chemical and physical characteristics of cellulose insulation particulates, and evaluation of potential acute pulmonary toxicity.

    PubMed

    Morgan, Daniel L; Su, Yin-Fong; Dill, Jeffrey A; Turnier, John C; Westerberg, R Bruce; Smith, Cynthia S

    2004-12-01

    During installation of cellulose insulation (CI) in new and older houses, significant quantities of airborne material are generated. This study characterized the chemical and physical properties, and potential acute pulmonary toxicity of CI. CI from four manufacturers was analyzed for inorganic additives and trace element impurities. Aerosols were generated and size fractionated. The number and size of fibrous and nonfibrous particles in the respirable fractions were determined. Respirable CI particulates were intratracheally instilled in rats (5 mg/kg) to evaluate potential pulmonary toxicity. CI samples were similar in composition with small differences due primarily to fire retardants. Less than 0.1% of CI was respirable and contained few fibers. Acute exposure to CI caused transient inflammation in the lungs and increased 4-hydroxyproline. Microscopic evaluation revealed a minimal to mild, non-progressing granulomatous pneumonitis. Low concentrations of respirable particles were found in CI aerosols. Particles consisted primarily of fire retardants with few fibers, and caused mild pulmonary toxicity in rats.

  6. Equation of state of sticky-hard-sphere fluids in the chemical-potential route

    NASA Astrophysics Data System (ADS)

    Rohrmann, René D.; Santos, Andrés

    2014-04-01

    The coupling-parameter method, whereby an extra particle is progressively coupled to the rest of the particles, is applied to the sticky-hard-sphere fluid to obtain its equation of state in the so-called chemical-potential route (μ route). As a consistency test, the results for one-dimensional sticky particles are shown to be exact. Results corresponding to the three-dimensional case (Baxter's model) are derived within the Percus-Yevick approximation by using different prescriptions for the dependence of the interaction potential of the extra particle on the coupling parameter. The critical point and the coexistence curve of the gas-liquid phase transition are obtained in the μ route and compared with predictions from other thermodynamics routes and from computer simulations. The results show that the μ route yields a general better description than the virial, energy, compressibility, and zero-separation routes.

  7. Analysis of food packaging UV inks for chemicals with potential to migrate into food simulants.

    PubMed

    Papilloud, S; Baudraz, D

    2002-02-01

    Ultraviolet (UV) inks are an alternative formulation system to the more usual paste or liquid inks (oils or solvents based) that dry mainly by evaporation or penetration into the printed substrate. Based on acrylic acid chemistry, UV inks dry (the exact term is 'curing') by the chemical process of photopolymerization. Their composition (acrylate monomers and oligomers together with photo-initiators) exposed to UV emission lamps on the printing press units enable the transformation of the freshly printed ink layer into a tack-free film. For UV inks intendedfor primary food packaging, special care has to be paid to potential migrating species like small photo-initiator molecules and acrylate monomers not cross-linked in the formed network. The paper presents chromatographic methods to ascertain the level of ink ingredients potentially available to migrate into food simulants (migration tests). GC/MS was employed to quantify the levels of photo-initiators or acrylic esters (acrylates).

  8. Equation of state of sticky-hard-sphere fluids in the chemical-potential route.

    PubMed

    Rohrmann, René D; Santos, Andrés

    2014-04-01

    The coupling-parameter method, whereby an extra particle is progressively coupled to the rest of the particles, is applied to the sticky-hard-sphere fluid to obtain its equation of state in the so-called chemical-potential route (μ route). As a consistency test, the results for one-dimensional sticky particles are shown to be exact. Results corresponding to the three-dimensional case (Baxter's model) are derived within the Percus-Yevick approximation by using different prescriptions for the dependence of the interaction potential of the extra particle on the coupling parameter. The critical point and the coexistence curve of the gas-liquid phase transition are obtained in the μ route and compared with predictions from other thermodynamics routes and from computer simulations. The results show that the μ route yields a general better description than the virial, energy, compressibility, and zero-separation routes.

  9. Dissociative electron transfer in polychlorinated aromatics. Reduction potentials from convolution analysis and quantum chemical calculations.

    PubMed

    Romańczyk, Piotr P; Rotko, Grzegorz; Kurek, Stefan S

    2016-08-10

    Formal potentials of the first reduction leading to dechlorination in dimethylformamide were obtained from convolution analysis of voltammetric data and confirmed by quantum chemical calculations for a series of polychlorinated benzenes: hexachlorobenzene (-2.02 V vs. Fc(+)/Fc), pentachloroanisole (-2.14 V), and 2,4-dichlorophenoxy- and 2,4,5-trichlorophenoxyacetic acids (-2.35 V and -2.34 V, respectively). The key parameters required to calculate the reduction potential, electron affinity and/or C-Cl bond dissociation energy, were computed at both DFT-D and CCSD(T)-F12 levels. Comparison of the obtained gas-phase energies and redox potentials with experiment enabled us to verify the relative energetics and the performance of various implicit solvent models. Good agreement with the experiment was achieved for redox potentials computed at the DFT-D level, but only for the stepwise mechanism owing to the error compensation. For the concerted electron transfer/C-Cl bond cleavage process, the application of a high level coupled cluster method is required. Quantum chemical calculations have also demonstrated the significant role of the π*ring and σ*C-Cl orbital mixing. It brings about the stabilisation of the non-planar, C2v-symmetric C6Cl6˙(-) radical anion, explains the experimentally observed low energy barrier and the transfer coefficient close to 0.5 for C6Cl5OCH3 in an electron transfer process followed by immediate C-Cl bond cleavage in solution, and an increase in the probability of dechlorination of di- and trichlorophenoxyacetic acids due to substantial population of the vibrational excited states corresponding to the out-of-plane C-Cl bending at ambient temperatures.

  10. Spatial Distribution of Oxygen Chemical Potential under Potential Gradients and Theoretical Maximum Power Density with 8YSZ Electrolyte

    PubMed Central

    Lim, Dae-Kwang; Im, Ha-Ni; Song, Sun-Ju

    2016-01-01

    The maximum power density of SOFC with 8YSZ electrolyte as the function of thickness was calculated by integrating partial conductivities of charge carriers under various DC bias conditions at a fixed oxygen chemical potential gradient at both sides of the electrolyte. The partial conductivities were successfully taken using the Hebb-Wagner polarization method as a function of temperature and oxygen partial pressure, and the spatial distribution of oxygen partial pressure across the electrolyte was calculated based on Choudhury and Patterson’s model by considering zero electrode polarization. At positive voltage conditions corresponding to SOFC and SOEC, the high conductivity region was expanded, but at negative cell voltage condition, the low conductivity region near n-type to p-type transition was expanded. In addition, the maximum power density calculated from the current-voltage characteristic showed approximately 5.76 W/cm2 at 700 oC with 10 μm thick-8YSZ, while the oxygen partial pressure of the cathode and anode sides maintained ≈0.21 and 10−22 atm. PMID:26725369

  11. Spatial Distribution of Oxygen Chemical Potential under Potential Gradients and Theoretical Maximum Power Density with 8YSZ Electrolyte.

    PubMed

    Lim, Dae-Kwang; Im, Ha-Ni; Song, Sun-Ju

    2016-01-04

    The maximum power density of SOFC with 8YSZ electrolyte as the function of thickness was calculated by integrating partial conductivities of charge carriers under various DC bias conditions at a fixed oxygen chemical potential gradient at both sides of the electrolyte. The partial conductivities were successfully taken using the Hebb-Wagner polarization method as a function of temperature and oxygen partial pressure, and the spatial distribution of oxygen partial pressure across the electrolyte was calculated based on Choudhury and Patterson's model by considering zero electrode polarization. At positive voltage conditions corresponding to SOFC and SOEC, the high conductivity region was expanded, but at negative cell voltage condition, the low conductivity region near n-type to p-type transition was expanded. In addition, the maximum power density calculated from the current-voltage characteristic showed approximately 5.76 W/cm(2) at 700 (o)C with 10 μm thick-8YSZ, while the oxygen partial pressure of the cathode and anode sides maintained ≈0.21 and 10(-22) atm.

  12. EU alerting and reporting systems for potential chemical public health threats and hazards.

    PubMed

    Orford, R; Crabbe, H; Hague, C; Schaper, A; Duarte-Davidson, R

    2014-11-01

    A number of European and international IT platforms are used to notify competent authorities of new potential chemical exposures. Recently the European Parliament and the Council of European Union adopted new legislation that aims to improve the co-ordinated response to cross border health threats (Decision 1082/2013/EU). The Decision, inter alia, sets provisions on notification, ad hoc monitoring and coordination of public health measures following serious cross border threats to health from biological, chemical and environmental events as well as events that have an unknown origin. The legal instrument applies to all European Union Member States and is comparable to the International Health Regulations in its content, requirements and adoption of a multiple hazards approach. An inter-sectoral and multidisciplinary response to events with potentially dangerous cross border exposure pathways is often required. For example, European Poisons Centres may be aware of cases of toxic exposure to a product and, in parallel, trading standards may be aware of the same product due to a breach of consumer product standards. Whilst both cases would have been recorded for separate purposes in different alerting systems, they relate to the same exposure pathway; therefore a process for linking these records would allow a more robust approach to risk assessment and risk mitigation. The Decision seeks to reconcile this issue for serious threats by linking relevant platforms into one overarching higher level risk management IT platform called the Early Warning Response System (EWRS). This system will serve to link other sectors within the European Commission (EC) to public health (e.g. medicines), as well as other EU agencies and international bodies via co-notification features. Other European alert systems will be linked to EWRS to facilitate information sharing at both the assessment and management levels. This paper provides a timely overview of the main systems run by the EC

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

    PubMed

    Lübbert, Matthias; Kyereme, Jessica; Schöbel, Nicole; Beltrán, Leopoldo; Wetzel, Christian Horst; Hatt, Hanns

    2013-01-01

    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.

  14. Transient Receptor Potential Channels Encode Volatile Chemicals Sensed by Rat Trigeminal Ganglion Neurons

    PubMed Central

    Schöbel, Nicole; Beltrán, Leopoldo; Wetzel, Christian Horst; Hatt, Hanns

    2013-01-01

    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. PMID:24205061

  15. Potential for the increased efficiency in motors in the chemical and processing industries. Final report

    SciTech Connect

    Pillay, P.

    1996-08-01

    Refineries and chemical plants make up a large portion of the process industry in Louisiana. Detailed surveys of motors and motor loads were done for 2 refineries and 5 chemical plants. In addition, surveys of motor failures were done for 1 refinery and 4 chemical plants. Categories of < 20hp, 20hp--250hp, 250hp--500hp and > 500hp were used to reflect the horsepower ranges sued by utilities nationwide in DSM rebate programs. The 20hp--250hp range being a target for replacement or retrofit scenarios; this is also the horsepower range where users have a choice of energy efficient or standard efficient motors. The data are presented in different graphs to emphasize different characteristics. A raw motor count is given that is an actual count in every hp; this is then organized in the hp ranges listed above. The total horsepower in each category is also given to show the concentration of the plant`s installed hp. the loads are divided into pumps, fans, compressors and others in the case of refineries. in the case of chemical plants, additional categories had to be used, depending on the plant, like agitators, centrifuges etc. A realistic tariff structure is then used to determine the potential for efficiency improvements with the resultant energy, demand and cost savings. The results of metering of motors are then presented. Results of a 50hp motor driving a pump, a 200 hp motor driving a pump, a 100 hp motor driving a fan, and a 30hp motor driving an agitator are included. An examination of variable speed drive efficiency is included, using detailed models of the power electronic devices. 20 refs., 180 figs., 82 tabs.

  16. Quark-meson vertices and pion properties at finite chemical potential

    NASA Astrophysics Data System (ADS)

    Jiang, Yu; Shi, Yuan-Mei; Feng, Hong-Tao; Sun, Wei-Min; Zong, Hong-Shi

    2008-08-01

    Based on the rainbow-ladder approximation of the Dyson-Schwinger equations and the assumption of the analyticity of the quark-meson vertex in the neighborhood of zero chemical potential (μ=0) and neglecting the μ-dependence of the dressed gluon propagator, we use the method of studying the dressed quark propagator at finite chemical potential given in [H. S. Zong, L. Chang, F.Y. Hou, W. M. Sun, and Y. X. Liu, Phys. Rev. C 71, 015205 (2005)] to show that the axial-vector quark-meson vertex at finite μ can be obtained from the corresponding one at μ=0 by a shift of variable: Γ5νj[μ](k,p)=Γ5νj(k~,p), where k and p are the relative and total momentum of the quark-antiquark pair, respectively, and k~=(k→,k4+iμ). Similar relations hold for any other type of quark-meson vertex. This feature would facilitate the numerical calculations of the quark-meson vertex function at finite μ considerably. Based on these results and using the dressed quark propagator at μ=0 proposed in [R. Alkofer, W. Detmold, C. S. Fischer, and P. Maris, Phys. Rev. D 70, 014014 (2004)], we calculate the pion decay constant fπ and the pion mass mπ at finite μ and a comparison of our results with those in the literature is made.

  17. Color path integral equation of state of the quark-gluon plasma at nonzero chemical potential

    NASA Astrophysics Data System (ADS)

    Filinov, V. S.; Bonitz, M.; Ivanov, Yu B.; Ilgenfritz, E.-M.; Fortov, V. E.

    2015-04-01

    Based on the constituent quasiparticle model of the quark-gluon plasma (QGP), a color quantum path-integral Monte-Carlo (PIMC) method for calculation of the thermodynamic properties of the QGP is developed. We show that the PIMC method can be used for calculations of the equation of state at zero and non-zero baryon chemical potential not only above but also below the QCD critical temperature. Our results agree with lattice QCD calculations based on a Taylor expansion around zero baryon chemical potential. In our approach the QGP partition function is presented in the form of a color path integral with a relativistic measure replacing the Gaussian one traditionally used in the Feynman-Wiener path integrals. A procedure of sampling color variables according to the SU(3) group Haar measure is used for integration over the color variables. We expect that this approach will be useful to predict additional properties of the QGP that are still unaccesible in lattice QCD.

  18. Polar/apolar chemical inducers of differentiation of transformed cells: strategies to improve therapeutic potential.

    PubMed Central

    Marks, P A; Breslow, R; Rifkind, R A; Ngo, L; Singh, R

    1989-01-01

    N,N'-Hexamethylenebisacetamide (HMBA) induces transformed cells to differentiate, accompanied by suppression of oncogenicity. Clinical trials have shown that HMBA can cause positive therapeutic responses in some cancer patients, but clinical efficacy may be limited, in part, by dose-related toxicity. Potential improvements in efficacy may be accomplished by changes in the chemical structure of inducing agents and by increasing the sensitivity of tumor cells to inducers of differentiation. We have previously described an approach to improving tumor cell responsiveness to inducing agents. Transformed cell lines that have acquired low levels of resistance to vincristine display a markedly increased sensitivity to HMBA. We now report on a series of hybrid polar/apolar compounds--some of which are as active as HMBA and several of which are significantly more active than HMBA in vitro--whose chemical structures make it likely that they have different pharmacokinetics. Vincristine-resistant murine erythroleukemia cells also are shown to have marked increased sensitivity to these hybrid polar/apolar compounds. Thus these findings suggest potentially useful strategies for the application of polar/apolar inducers of differentiation to the treatment of cancers. These studies also provide approaches to further understanding of the biological process of terminal differentiation. PMID:2762329

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

    PubMed

    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 < 0.05) reduced the ulcer index (55.33% and 72.14% inhibition). Histopathological examination of rat stomachs demonstrated that 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.

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

    PubMed

    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.

  1. The antimicrobial potential of ionic liquids: A source of chemical diversity for infection and biofilm control.

    PubMed

    Pendleton, Jack Norman; Gilmore, Brendan F

    2015-08-01

    Although described almost a century ago, interest in ionic liquids has flourished in the last two decades, with significant advances in the understanding of their chemical, physical and biological property sets driving their widespread application across multiple and diverse research areas. Significant progress has been made through the contributions of numerous research groups detailing novel libraries of ionic liquids, often 'task-specific' designer solvents for application in areas as diverse as separation technology, catalysis and bioremediation. Basic antimicrobial screening has often been included as a surrogate indication of the environmental impact of these compounds widely regarded as 'green' solvents. Obviating the biological properties, specifically toxicity, of these compounds has obstructed their potential application as sophisticated designer biocides. A recent tangent in ionic liquids research now aims to harness tuneable biological properties of these compounds in the design of novel potent antimicrobials, recognising their unparalleled flexibility for chemical diversity in a severely depleted antimicrobial arsenal. This review concentrates primarily on the antimicrobial potential of ionic liquids and aims to consolidate contemporary microbiological background information, assessment protocols and future considerations necessary to advance the field in light of the urgent need for antimicrobial innovation.

  2. Nonlocal Ployakov-Nambu-Jona-Lasinio model and imaginary chemical potential

    SciTech Connect

    Kashiwa K.; Hell, T.; Weise, W.

    2011-09-21

    With the aim of setting constraints for the modeling of the QCD phase diagram, the phase structure of the two-flavor Polyakov-loop-extended Nambu and Jona-Lasinio (PNJL) model is investigated in the range of imaginary chemical potentials ({mu}{sub I}) and compared with available N{sub f} = 2 lattice QCD results. The calculations are performed using the advanced nonlocal version of the PNJL model with the inclusion of vector-type quasiparticle interactions between quarks, and with wave-function-renormalization corrections. It is demonstrated that the nonlocal PNJL model reproduces important features of QCD at finite {mu}{sub I}, such as the Roberge-Weiss (RW) periodicity and the RW transition. Chiral and deconfinement transition temperatures for N{sub f} = 2 turn out to coincide both at zero chemical potential and at finite {mu}{sub I}. Detailed studies are performed concerning the RW endpoint and its neighborhood where a first-order transition occurs.

  3. Chemical potential and tunneling in bilayer graphene using double bilayer graphene heterostructures

    NASA Astrophysics Data System (ADS)

    Tutuc, Emanuel

    2015-03-01

    Vertical heterostructures consisting of atomic layers separated by insulators can open a window to explore the role of electron interaction in these materials, otherwise not accessible in single layer devices. We describe here one such heterostructure, consisting of two bilayer graphene flakes separated by a hexagonal boron-nitride dielectric. Using the top layer as a resistively detected Kelvin probe we map the chemical potential of the bottom bilayer graphene as a function of electron density, perpendicular magnetic field, and transverse electric field. At zero magnetic field the chemical potential reveals a strongly non-linear dependence on density, with an electric field induced energy gap at charge neutrality. The data allow a direct measurement of the electric field-induced bandgap at zero magnetic field, the orbital Landau level energies, and the broken symmetry quantum Hall state gaps in high magnetic fields. In samples where the two layers are rotationally aligned the interlayer tunneling current measured as a function of interlayer bias reveals a gate-tunable negative differential resistance thanks to momentum conserving tunneling. Remarkably, the resonance width has a weak temperature dependence in the range 1.5 K to 300 K. Work done in collaboration with K. Lee, B. Fallahazad, S. Kang, J. Xue, D. C. Dillen, K. Kim, L. F. Register, S. K. Banerjee, T. Taniguchi, and K. Watanabe. This work supported by the Office of Naval Research, the Nanoelectronics Research Initiative SWAN center, and Intel Corp.

  4. Characterization of homoionic Fe{sup 2+}-type montmorillonite: Potential chemical species of iron contaminant

    SciTech Connect

    Kozai, Naofumi Inada, Koichi; Adachi, Yoshifusa; Kawamura, Sachi; Kashimoto, Yusuke; Kozaki, Tamotsu; Sato, Seichi; Ohnuki, Toshihiko; Sakai, Takuro; Sato, Takahiro; Oikawa, Masakazu; Esaka, Fumitaka; Mitamura, Hisayoshi

    2007-08-15

    Fe{sup 2+}-montmorillonite with Fe{sup 2+} ions occupying cation exchange sites is an ideal transformation product in bentonite buffer material. In our previous study on preparation and characterization of Fe{sup 2+}-montmorillonite, the montmorillonite sample that adsorbed Fe{sup 2+} ions on almost all of the cation exchange sites was prepared using a FeCl{sub 2} solution under an inert gas condition [N. Kozai, Y. Adachi, S. Kawamura, K. Inada, T. Kozaki, S. Sato, H. Ohashi, T. Ohnuki, T. Banba, J. Nucl. Sci. Technol. 38 (2001) 1141]. In view of the unstable nature of iron(II) chemical species, this study attempted to determine the potential contaminant iron chemical species in the sample. Nondestructive elemental analysis revealed that a small amount of chloride ions remained dispersed throughout the clay particles. The chloride ion retention may be due to the adsorption of FeCl{sup +} ion pairs in the initial FeCl{sub 2} solution and the subsequent containment of the Cl{sup -} ions that are dissociated from the FeCl{sup +} ion pairs during excess salt removal treatment. Two explanations are advanced for the second process: the slow release of the remaining Cl{sup -} ions from the collapsed interlayer of the montmorillonite, and the transformation of a minor fraction of the remaining FeCl{sup +} ion pairs to iron(III) hydroxide chloride complexes having low solubility. - Graphical abstract: The distribution of Si (left) and Cl (right) in homoionic Fe{sup 2+}-type montmorillonite prepared under an inert gas atmosphere by a conventional method using a FeCl{sub 2} solution. A small fraction of chloride ions remained dispersed throughout the clay. This paper mainly discusses the potential contaminant iron chemical species in this sample other than Fe{sup 2+} ions.

  5. Chemical dispersant potentiates crude oil impacts on growth, reproduction, and gene expression in Caenorhabditis elegans.

    PubMed

    Zhang, Yanqiong; Chen, Dongliang; Ennis, Adrien C; Polli, Joseph R; Xiao, Peng; Zhang, Baohong; Stellwag, Edmund J; Overton, Anthony; Pan, Xiaoping

    2013-02-01

    The economic, environmental, and human health impacts of the deepwater horizon (DWH) oil spill have been of significant concern in the general public and among scientists. This study employs parallel experiments to test the effects of crude oil from the DWH oil well, chemical dispersant Corexit 9500A, and dispersant-oil mixture on growth and reproduction in the model organism Caenorhabditis elegans. Both the crude oil and the dispersant significantly inhibited the reproduction of C. elegans. Dose-dependent inhibitions of hatched larvae production were observed in worms exposed to both crude oil and dispersant. Importantly, the chemical dispersant Corexit 9500A potentiated crude oil effects; dispersant-oil mixture induced more significant effects than oil or dispersant-alone exposures. While oil-alone exposure and dispersant-alone exposure have none to moderate inhibitory effects on hatched larvae production, respectively, the mixture of dispersant and oil induced much more significant inhibition of offspring production. The production of hatched larvae was almost completely inhibited by several high concentrations of the dispersant-oil mixture. This suggests a sensitive bioassay for future investigation of oil/dispersant impacts on organisms. We also investigated the effects of crude oil/dispersant exposure at the molecular level by measuring the expressions of 31 functional genes. Results showed that the dispersant and the dispersant-oil mixture induced aberrant expressions of 12 protein-coding genes (cat-4, trxr-2, sdhb-1, lev-8, lin-39, unc-115, prdx-3, sod-1, acr-16, ric-3, unc-68, and acr-8). These 12 genes are associated with a variety of biological processes, including egg-laying, oxidative stress, muscle contraction, and neurological functions. In summary, the toxicity potentiating effect of chemical dispersant must be taken into consideration in future crude oil cleanup applications.

  6. An Informatics Approach to Evaluating Combined Chemical Exposures from Consumer Products: A Case Study of Asthma-Associated Chemicals and Potential Endocrine Disruptors

    PubMed Central

    Gabb, Henry A.; Blake, Catherine

    2016-01-01

    exposures from consumer products: a case study of asthma-associated chemicals and potential endocrine disruptors. Environ Health Perspect 124:1155–1165; http://dx.doi.org/10.1289/ehp.1510529 PMID:26955064

  7. Evaluation of in silico tools to predict the skin sensitization potential of chemicals.

    PubMed

    Verheyen, G R; Braeken, E; Van Deun, K; Van Miert, S

    2017-01-01

    Public domain and commercial in silico tools were compared for their performance in predicting the skin sensitization potential of chemicals. The packages were either statistical based (Vega, CASE Ultra) or rule based (OECD Toolbox, Toxtree, Derek Nexus). In practice, several of these in silico tools are used in gap filling and read-across, but here their use was limited to make predictions based on presence/absence of structural features associated to sensitization. The top 400 ranking substances of the ATSDR 2011 Priority List of Hazardous Substances were selected as a starting point. Experimental information was identified for 160 chemically diverse substances (82 positive and 78 negative). The prediction for skin sensitization potential was compared with the experimental data. Rule-based tools perform slightly better, with accuracies ranging from 0.6 (OECD Toolbox) to 0.78 (Derek Nexus), compared with statistical tools that had accuracies ranging from 0.48 (Vega) to 0.73 (CASE Ultra - LLNA weak model). Combining models increased the performance, with positive and negative predictive values up to 80% and 84%, respectively. However, the number of substances that were predicted positive or negative for skin sensitization in both models was low. Adding more substances to the dataset will increase the confidence in the conclusions reached. The insights obtained in this evaluation are incorporated in a web database www.asopus.weebly.com that provides a potential end user context for the scope and performance of different in silico tools with respect to a common dataset of curated skin sensitization data.

  8. Chemical reactivity and skin sensitization potential for benzaldehydes: can Schiff base formation explain everything?

    PubMed

    Natsch, Andreas; Gfeller, Hans; Haupt, Tina; Brunner, Gerhard

    2012-10-15

    Skin sensitizers chemically modify skin proteins rendering them immunogenic. Sensitizing chemicals have been divided into applicability domains according to their suspected reaction mechanism. The widely accepted Schiff base applicability domain covers aldehydes and ketones, and detailed structure-activity-modeling for this chemical group was presented. While Schiff base formation is the obvious reaction pathway for these chemicals, the in silico work was followed up by limited experimental work. It remains unclear whether hydrolytically labile Schiff bases can form sufficiently stable epitopes to trigger an immune response in the living organism with an excess of water being present. Here, we performed experimental studies on benzaldehydes of highly differing skin sensitization potential. Schiff base formation toward butylamine was evaluated in acetonitrile, and a detailed SAR study is presented. o-Hydroxybenzaldehydes such as salicylaldehyde and the oakmoss allergens atranol and chloratranol have a high propensity to form Schiff bases. The reactivity is highly reduced in p-hydroxy benzaldehydes such as the nonsensitizing vanillin with an intermediate reactivity for p-alkyl and p-methoxy-benzaldehydes. The work was followed up under more physiological conditions in the peptide reactivity assay with a lysine-containing heptapeptide. Under these conditions, Schiff base formation was only observable for the strong sensitizers atranol and chloratranol and for salicylaldehyde. Trapping experiments with NaBH₃CN showed that Schiff base formation occurred under these conditions also for some less sensitizing aldehydes, but the reaction is not favored in the absence of in situ reduction. Surprisingly, the Schiff bases of some weaker sensitizers apparently may react further to form stable peptide adducts. These were identified as the amides between the lysine residues and the corresponding acids. Adduct formation was paralleled by oxidative deamination of the parent

  9. Old Neutron Stars as Probes of Isospin-Violating Dark Matter

    NASA Astrophysics Data System (ADS)

    Zheng, Hao; Sun, Kai-Jia; Chen, Lie-Wen

    2015-02-01

    Isospin-violating dark matter (IVDM), which couples differently with protons and neutrons, provides a promising mechanism to ameliorate the tension among recent direct detection experiments. Assuming dark matter (DM) is non-interacting bosonic asymmetric IVDM, we investigate how the existence of old neutron stars limits the DM-proton scattering cross-section {{σ }p}, especially the effects of the isospin-violating DM-nucleon interactions and the symmetry energy in the equation of state (EOS) of isospin asymmetric nuclear matter. Our calculations are completely based on general relativity and the structure of neutron stars is obtained by solving the Tolman-Oppenheimer-Volkoff equations with nuclear matter EOS constrained by terrestrial experiments. We find that, by considering the more realistic neutron star model rather than a simple uniform neutron sphere as usual, the {{σ }p} bounds from old neutron stars can be varied by more than an order of magnitude depending on the specific values of the DM neutron-to-proton coupling ratio {{f}n}/{{f}p}, and they can be further varied by more than a factor of two depending on the density dependence of the symmetry energy. In particular, we demonstrate that the observed nearby isolated old neutron star PSR B1257+12 can set a very strong limit on {{σ }p} for low-mass DM particles (≤slant 20 GeV) that reaches a sensitivity beyond the current best limits from direct detection experiments and disfavors the DM interpretation of previously reported positive experimental results, including the IVDM.

  10. No-core configuration-interaction model for the isospin- and angular-momentum-projected states

    NASA Astrophysics Data System (ADS)

    Satuła, W.; Båczyk, P.; Dobaczewski, J.; Konieczka, M.

    2016-08-01

    Background: Single-reference density functional theory is very successful in reproducing bulk nuclear properties like binding energies, radii, or quadrupole moments throughout the entire periodic table. Its extension to the multireference level allows for restoring symmetries and, in turn, for calculating transition rates. Purpose: We propose a new variant of the no-core-configuration-interaction (NCCI) model treating properly isospin and rotational symmetries. The model is applicable to any nucleus irrespective of its mass and neutron- and proton-number parity. It properly includes polarization effects caused by an interplay between the long- and short-range forces acting in the atomic nucleus. Methods: The method is based on solving the Hill-Wheeler-Griffin equation within a model space built of linearly dependent states having good angular momentum and properly treated isobaric spin. The states are generated by means of the isospin and angular-momentum projection applied to a set of low-lying (multi)particle-(multi)hole deformed Slater determinants calculated using the self-consistent Skyrme-Hartree-Fock approach. Results: The theory is applied to calculate energy spectra in N ≈Z nuclei that are relevant from the point of view of a study of superallowed Fermi β decays. In particular, a new set of the isospin-symmetry-breaking corrections to these decays is given. Conclusions: It is demonstrated that the NCCI model is capable of capturing main features of low-lying energy spectra in light and medium-mass nuclei using relatively small model space and without any local readjustment of its low-energy coupling constants. Its flexibility and a range of applicability makes it an interesting alternative to the conventional nuclear shell model.

  11. Neutrinos by double beta decays from 100Mo and nuclear spin-isospin responses

    NASA Astrophysics Data System (ADS)

    Kudomi, N.; Ejiri, H.; Fushimi, K.; Hayashi, K.; Kishimoto, T.; Komori, M.; Kume, K.; Kuramoto, H.; Matsuoka, K.; Ohsumi, H.; Takahisa, K.; Umehara, S.; Yoshida, S.

    2001-06-01

    Spectroscopic studies of neutrino-less double beta decays (0νββ) of 100Mo were made by means of ELEGANT V. The data at Oto lab., being combined with the data at Kamioka, gives stringent limits on the half-life of T1/2 for the 0νββ and the effective Majorana neutrino mass of <2.1 eV(90%C.L.). Spin-isospin responses for neutrinos associated with ββ of 100Mo are discussed. A perspective of double beta decay of 100Mo and a possible proposal of MOON are discussed. .

  12. Comparative tests of isospin-symmetry-breaking corrections to superallowed 0+→0+ nuclear β decay

    NASA Astrophysics Data System (ADS)

    Towner, I. S.; Hardy, J. C.

    2010-12-01

    We present a test with which to evaluate the calculated isospin-symmetry-breaking corrections to superallowed 0+→0+ nuclear β decay. The test is based on the corrected experimental Ft values being required to satisfy conservation of the vector current (CVC). When applied to six sets of published calculations, the test demonstrates quantitatively that only one set, the one based on the shell model with Saxon-Woods radial wave functions, provides satisfactory agreement with CVC. This test can easily be applied to any sets of calculated correction terms that are produced in future.

  13. Covariant Density Functional Theory For Isospin Properties In Nuclei Far From Stability

    SciTech Connect

    Ring, P.; Lalazissis, G.A.; Niksic, T.; Vretenar, D.

    2005-04-05

    In recent years Covariant Density Functional Theory (CDFT) has been very successful for the description of ground state properties of nuclei all over the periodic table. Isospin properties of nuclei far from the valley of stability are used to improve the existing functionals. Modern parameter sets of the corresponding Lagrangian density are adjusted carefully to characteristic nuclei with explicit density dependence of the meson-nucleon couplings. They are tested in relativistic Hartree-Bogoliubov calculations of nuclear ground-states, in particular for the calculation of masses, and they are applied to the analysis of very recent data on super-heavy nuclei.

  14. Electron spin polarization by isospin ordering in correlated two-layer quantum Hall systems.

    PubMed

    Tiemann, L; Wegscheider, W; Hauser, M

    2015-05-01

    Enhancement of the electron spin polarization in a correlated two-layer, two-dimensional electron system at a total Landau level filling factor of 1 is reported. Using resistively detected nuclear magnetic resonance, we demonstrate that the electron spin polarization of two closely spaced two-dimensional electron systems becomes maximized when interlayer Coulomb correlations establish spontaneous isospin ferromagnetic order. This correlation-driven polarization dominates over the spin polarizations of competing single-layer fractional quantum Hall states under electron density imbalances.

  15. Isospin Dependence of Pion Absorption on Nucleon Pairs at Tπ=65 MeV

    NASA Astrophysics Data System (ADS)

    Moinester, M. A.; Gill, D. R.; Vincent, J.; Ashery, D.; Levenson, S.; Alster, J.; Altman, A.; Lichtenstadt, J.; Piasetzky, E.; Aniol, K. A.; Johnson, R. R.; Roser, H. W.; Tacik, R.; Gyles, W.; Barnett, B.; Sobie, R. J.; Gubler, H. P.

    1984-04-01

    Angular distributions of differential cross sections were measured for the first time for pion absorption on a T=1, S=0 nucleon pair and for absorption on a T=0, S=1 pair in the 3He nucleus. A large isospin dependence is observed in the differential cross sections. The ratio of cross sections σ(3He(π+,2p))σ(3He(π-,pn)) is 15.2+/-1.2. The results show evidence of an isoscalar component of the final state in the reaction 3He(π-,pn)n, which cannot be mediated by Δ resonance formation.

  16. Isospin dependence of fragment spectra in heavy/super-heavy colliding nuclei at intermediate energies

    SciTech Connect

    Chugh, Rajiv Kumar, Rohit; Vinayak, Karan Singh

    2016-05-06

    Using isospin-dependent quantum molecular dynamics (IQMD) approach, we performed a theoretical investigation of the evolution of various kinds of fragments in heavy and superheavy-ion reactions in the intermediate/medium energy domain. We demonstrated direct impact of symmetry energy and Coulomb interactions on the evolution of fragments. Final fragment spectra (yields) obtained from the analysis of various heavy/super-heavy ion reactions at different reaction conditions show high sensitivity towards Coulomb interactions and less significant sensitivity to symmetry energy forms. No inconsistent pattern of fragment structure is obtained in case of super-heavy ion involved reactions for all the parameterizations of density dependence of symmetry energy.

  17. Effects of the high-momentum tail of nucleon momentum distribution on the isospin-sensitive observables

    NASA Astrophysics Data System (ADS)

    Zhang, Fang; Yong, Gao-Chan

    2016-11-01

    Based on the Isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, effects of the high-momentum tail (HMT) of nucleon momentum distribution in colliding nuclei on some isospin-sensitive observables are studied in the semi-central 197Au + 197Au reactions at incident beam energy of 400 MeV/nucleon. It is found that the nucleon transverse flow, the difference of neutron and proton transverse flows, the nucleon elliptic flow and the free neutron to proton ratio are all less sensitive to the HMT, while the isospin-sensitive nucleon elliptic flow difference is clearly affected by the HMT. Except at very high kinetic energies, the kinetic energy distributions of π-, π+ and charged pion ratio π- / π+ are all sensitive to the HMT.

  18. Chemical coagulation-based processes for trace organic contaminant removal: current state and future potential.

    PubMed

    Alexander, Jonathan T; Hai, Faisal I; Al-Aboud, Turki M

    2012-11-30

    Trace organic contaminants have become an increasing cause of concern for governments and water authorities as they attempt to respond to the potential challenges posed by climate change by implementing sustainable water cycle management practices. The augmentation of potable water supplies through indirect potable water reuse is one such method currently being employed. Given the uncertainty surrounding the potential human health impacts of prolonged ingestion of trace organic contaminants, it is vital that effective and sustainable treatment methods are utilized. The purpose of this article is to provide a comprehensive literature review of the performance of the chemical coagulation process in removing trace organic contaminants from water. This study evaluated the removal data collated from recent research relating to various trace organic contaminants during the coagulation process. It was observed that there is limited research data relating to the removal of trace organic contaminants using coagulation. The findings of this study suggest that there is a gap in the current research investigating the potential of new types of coagulants and exploring coagulation-based hybrid processes to remove trace organic contaminants from water. The data analysed in this study regarding removal efficiency suggests that, even for the significantly hydrophobic compounds, hydrophobicity is not the sole factor governing removal of trace organic contaminants by coagulation. This has important implications in that the usual practice of screening coagulants based on turbidity (suspended solid) removal proves inadequate in the case of trace organic contaminant removal. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Measurement of oxygen chemical potential in thin electrolyte film, anode-supported solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Lim, Hyung-Tae; Virkar, Anil V.

    Thin (∼30-45 μm) gadolinia-doped ceria (GDC) electrolyte, Ni + yttria-stabilized zirconia (YSZ) anode-supported cells were fabricated with platinum reference electrodes (probes) embedded within the electrolyte layer. The exposed parts of the probes were sealed off from the atmosphere using an oxygen impermeable glass. Thus, no oxygen exchange could occur and voltage measurements at the probes correspond to the reduced negative electrochemical potential of electrons (φ = - μ˜e / e , where μ˜e is the electrochemical potential of electrons and e is the electronic charge). The φ was measured at 650 °C under open circuit conditions with air circulated past the cathode and hydrogen circulated past the anode. The open circuit voltage was ∼0.84 V. The voltages between the anode and reference electrodes were very small-less than 30 mV. This was attributed to significant electronic conduction throughout the electrolyte from anode/electrolyte interface to cathode/electrolyte interface. Thus, voltage drop mainly occurs across the cathode/electrolyte interface. The variation of chemical potential of oxygen, μO2 , within the GDC electrolyte was estimated, which showed a large drop in μO2 across the cathode/electrolyte interface. The oxygen partial pressure in GDC just inside the cathode was estimated to be ∼10 -22 atm. Thus, in GDC-based anode-supported cells the effective electrolyte thickness is very small.

  20. Computed Potential Energy Surfaces and Minimum Energy Pathways for Chemical Reactions

    NASA Technical Reports Server (NTRS)

    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.

  1. Generalization of classical mechanics for nuclear motions on nonadiabatically coupled potential energy surfaces in chemical reactions.

    PubMed

    Takatsuka, Kazuo

    2007-10-18

    Classical trajectory study of nuclear motion on the Born-Oppenheimer potential energy surfaces is now one of the standard methods of chemical dynamics. In particular, this approach is inevitable in the studies of large molecular systems. However, as soon as more than a single potential energy surface is involved due to nonadiabatic coupling, such a naive application of classical mechanics loses its theoretical foundation. This is a classic and fundamental issue in the foundation of chemistry. To cope with this problem, we propose a generalization of classical mechanics that provides a path even in cases where multiple potential energy surfaces are involved in a single event and the Born-Oppenheimer approximation breaks down. This generalization is made by diagonalization of the matrix representation of nuclear forces in nonadiabatic dynamics, which is derived from a mixed quantum-classical representation of the electron-nucleus entangled Hamiltonian [Takatsuka, K. J. Chem. Phys. 2006, 124, 064111]. A manifestation of quantum fluctuation on a classical subsystem that directly contacts with a quantum subsystem is discussed. We also show that the Hamiltonian thus represented gives a theoretical foundation to examine the validity of the so-called semiclassical Ehrenfest theory (or mean-field theory) for electron quantum wavepacket dynamics, and indeed, it is pointed out that the electronic Hamiltonian to be used in this theory should be slightly modified.

  2. Exploring remnants of invariants buried in a deep potential well in chemical reactions.

    PubMed

    Teramoto, Hiroshi; Komatsuzaki, Tamiki

    2008-09-07

    We revisit the concept of "remnant of invariant manifolds" originally discussed by Shirts and Reinhardt in a two degrees of freedom Henon-Heiles system [J. Chem. Phys. 77, 5204 (1982)]. This is regarded as the remnants of a destroyed invariant manifold that can dominate the transport in phase space even at high energy regions where most of all tori vanish. We present a novel technique to extract such remnants of invariants from a sea of chaos in highly nonlinear coupled molecular systems in terms of the canonical perturbation theory based on Lie transforms. As an illustrative example we demonstrate in HCN isomerization reaction that the conventional procedure based on a finite order truncation of the coordinate transformation prevent us from detecting remnants of invariants. However, our technique correctly captures the underlying remnants of invariants that shed light on the energetics of chemical reaction, that is, how the reactive mode acquires (releases) energy from (to) the other vibrational mode in order to overcome the potential barrier (to be trapped in the potential well). We also found the qualitative difference between the two potential wells, HCN and CNH, which coincides with the nearest neighbor level spacing distribution of the vibrational quantum states within the wells.

  3. Computed Potential Energy Surfaces and Minimum Energy Pathways for Chemical Reactions

    NASA Technical Reports Server (NTRS)

    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.

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

    SciTech Connect

    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.

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

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

    Coates, J.; Butler, T. M.

    2015-08-01

    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.

  7. Chemical attractants in horseshoe crab, Limulus polyphemus, eggs: the potential for an artificial bait.

    PubMed

    Ferrari, Kirstin M; Targett, Nancy M

    2003-02-01

    Horseshoe crabs, Limulus polyphemus, are the preferred bait in the eel and conch fisheries along the east coast of the United States. However, recent management measures have restricted the availability of horseshoe crabs to commercial fisheries, creating the need for sustainable, alternative bait sources. In this study, we examined the chemistry underlying the predator-prey attraction to determine if specific, isolable attractant metabolites from the horseshoe crab could be identified and characterized for incorporation into an artifical bait. Initial assays with the mud snail, Hyanassa obsoleta, suggested that the chemoattractants were concentrated in L. polyphemus eggs. Chemical analyses and biological assays of the egg extract indicated the primary cue was a heat-stable, proteinaceous compound (>10 kDa). A carbohydrate-rich fraction of low molecular mass (< 10 kDa) also enhanced mud snail chemotaxis. Analysis of egg digests with SDS-PAGE confirmed the presence of glycoproteins or carbohydrate-binding proteins in the horseshoe crab egg extract. Because the attractant appears to be a complex protein or glycoprotein, conventional chemical synthesis is unlikely. However, the tools of modem biotechnology offer the potential to produce this attractant in a system independent of the horseshoe crab. Such an attractant could be incorporated into an artificial bait, providing an ecologically sound alternative for commercial eel and whelk fisheries.

  8. [Chemical Potentials of Hydrothermal Systems and Formation of Coupled Modular Metabolic Pathways].

    PubMed

    Marakushev, S A; Belonogova, O V

    2015-01-01

    According to Gibbs J.W. the number of independent components is the least number of those chemical constituents, by combining which the compositions of all possible phases in the system can be obtained, and at the first stages of development of the primary metabolism of the three-component system C-H-O different hydrocarbons and molecular hydrogen were used as an energy source for, it. In the Archean hydrothermal conditions under the action of the phosphorus chemical potential the C-H-O system was transformed into a four-component system C-H-O-P setting up a gluconeogenic system, which became the basis of power supply for a protometabolism, and formation of a new cycle of CO2 fixation (reductive pentose phosphate pathway). It is shown that parageneses (association) of certain substances permitted the modular constructions of the central metabolism of the system C-H-O-P and the formed modules appear in association with each other in certain physicochemical hydrothermal conditions. Malate, oxaloacetate, pyruvate and phosphoenolpyruvate exhibit a turnstile-like mechanism of switching reaction directions.

  9. Can phylogeny predict chemical diversity and potential medicinal activity of plants? A case study of amaryllidaceae

    PubMed Central

    2012-01-01

    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. PMID:22978363

  10. Chemical composition of core samples from Newark Basin, a potential carbon sequestration site

    NASA Astrophysics Data System (ADS)

    Seltzer, A. M.; Yang, Q.; Goldberg, D.

    2012-12-01

    Injection of carbon dioxide into deep saline aquifers has been identified as a promising mitigation option of greenhouse gases, the successful management of which is considered to be one of the most urgent and important challenges. Given the high energy production in the New York metropolitan area, the Newark Basin region is considered to be a potential future sequestration site. However, the risk of an upward leak of sequestered CO2, especially to a shallow drinking water aquifer, is a key concern facing geological sequestration as a safe and viable mitigation option. In this study, we measured the chemical composition of 25 cores from various depths throughout Newark Basin as a precursor for an ex situ incubation experiment using these rock samples and aquifer water to simulate a leak event. Inductively coupled plasma mass spectrometry analysis of microwave-assisted digested rock powders and X-ray fluorescence analysis of the rock powders were conducted to obtain the concentrations of major and trace elements. Most of the major and trace elements show wide concentration ranges at one to two orders of magnitude. Understanding the chemical composition of these Newark Basin core samples is important not only for characterizing materials used for the later lab incubation, but also for gaining a broader understanding of the chemistry of the Newark Basin and profiling the region according to the varying risks associated with a leak of sequestered CO2 to a drinking water aquifer.

  11. Use of biosensors to screen urine samples for potentially toxic chemicals.

    PubMed

    Horswell, Jacqui; Dickson, Stuart

    2003-09-01

    Forensic toxicology laboratories are often required to implicate or exclude poisoning as a factor in a death or unexplained illness. An analytical tool which enables toxicologists to screen a wide variety of common poisons would be extremely useful. In this paper, we describe the use of a bacterial biosensor for detecting the presence of commonly encountered potentially toxic chemicals in urine. The biosensor responds to any chemical that causes metabolic stress to the bacterial cell and the response is in direct proportion to the concentration of the stressor. This allows a measure of the concentration of a toxicant in urine, without knowing exactly what the toxic compound(s) may be. This affords a distinct advantage over conventional analytical techniques, which require an extensive screening program before it is even known that a toxic compound is present. This preliminary investigation has shown that this biosensor can indicate the presence, in urine, of herbicides such as glyphosate, 2,4-dichlorophenoxyacetic acid, and 2,4,5-trichlorophenoxyacetic acid; the biocide pentachlorophenol; or inorganic poisons such as arsenic, mercury, and cyanide. The biosensor was also shown to be sensitive to a concentration range of these toxicants likely to be found in samples submitted for toxicological analysis.

  12. Two-photon absorption in gapped bilayer graphene with a tunable chemical potential

    NASA Astrophysics Data System (ADS)

    Brinkley, M. K.; Abergel, D. S. L.; Clader, B. D.

    2016-09-01

    Despite the now vast body of two-dimensional materials under study, bilayer graphene remains unique in two ways: it hosts a simultaneously tunable band gap and electron density; and stems from simple fabrication methods. These two advantages underscore why bilayer graphene is critical as a material for optoelectronic applications. In the work that follows, we calculate the one- and two-photon absorption coefficients for degenerate interband absorption in a graphene bilayer hosting an asymmetry gap and adjustable chemical potential—all at finite temperature. Our analysis is comprehensive, characterizing one- and two-photon absorptive behavior over wide ranges of photon energy, gap, chemical potential, and thermal broadening. The two-photon absorption coefficient for bilayer graphene displays a rich structure as a function of photon energy and band gap due to the existence of multiple absorption pathways and the nontrivial dispersion of the low energy bands. This systematic work will prove integral to the design of bilayer-graphene-based nonlinear optical devices.

  13. Critical temperature of chiral symmetry restoration for quark matter with a chiral chemical potential

    NASA Astrophysics Data System (ADS)

    Ruggieri, M.; Peng, G. X.

    2016-12-01

    In this article we study the restoration of chiral symmetry at a finite temperature for quark matter with a chiral chemical potential, {μ }5, by means of a nonlocal Nambu-Jona-Lasinio model. This model allows the introduction of, in the simplest way possible, a Euclidean momentum, p E , dependent quark mass function which decays (neglecting logarithms) as 1/{p}{E}2 for large p E , in agreement with the asymptotic behaviour expected in quantum chromodynamics in the presence of a nonperturbative quark condensate. We focus on the critical temperature for chiral symmetry restoration in the chiral limit, T c, versus {μ }5, as well as on the order of the phase transition. We find that T c increases with {μ }5, and that the transition remains of the second order for the whole range of {μ }5 considered.

  14. Nutraceutical potential of Byrsonima cydoniifolia fruits based on chemical composition, anti-inflammatory, and antihyperalgesic activities.

    PubMed

    Santos, Vanessa Samúdio Dos; Nascimento, Thalita Vieira; Felipe, Josyelen Lousada; Boaretto, Amanda Galdi; Damasceno-Junior, Geraldo Alves; Silva, Denise Brentan; Toffoli-Kadri, Mônica Cristina; Carollo, Carlos Alexandre

    2017-12-15

    In recent years, the fruits of native Brazilian plant species with anti-inflammatory property have gained prominence due to their properties comparable to traditional medicines. This study aimed to chemically characterize and evaluate the anti-inflammatory and antihyperalgesic activity of Byrsonima cydoniifolia fruit, which is widely used to manufacture ice cream and jellies. Our results revealed that the fruit exhibits flavonoid derivatives and stilbenes, as trans-piceatannol and resveratrol, as main secondary metabolites. In mice, the hydroethanolic extract of fruit reduced the edema, migration of polymorphonuclear leukocytes into the peritoneal cavity, as well as abdominal writhings. The results demonstrated, for the first time, the presence of stilbenoids in the Byrsonima genus and the anti-inflammatory and antihyperalgesic effect of Byrsonima cydoniifolia fruits, supporting its potential as a nutraceutical food. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    PubMed

    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.

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

    PubMed Central

    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

  17. Relativistic second-order dissipative fluid dynamics at finite chemical potential

    NASA Astrophysics Data System (ADS)

    Jaiswal, Amaresh; Friman, Bengt; Redlich, Krzysztof

    2016-07-01

    We employ a Chapman-Enskog like expansion for the distribution function close to equilibrium to solve the Boltzmann equation in the relaxation time approximation and subsequently derive second-order evolution equations for dissipative charge currentand shear stress tensor for a system of massless quarks and gluons. We use quantum statistics for the phase space distribution functions to calculate the transport coefficients. We show that, the second-order evolution equations for the dissipative charge current and the shear stress tensor can be decoupled. We find that, for large chemical potential, the charge conductivity is small compared to the shear viscosity. Moreover, we demonstrate that the limiting behaviour of the ratio of heat conductivity to shear viscosity is identicalto that obtained for a strongly coupled conformal plasma.

  18. Relaxation of the Chiral Chemical Potential in the Dense Matter of a Neutron Star

    NASA Astrophysics Data System (ADS)

    Dvornikov, M. S.

    2017-03-01

    A model of the generation of a magnetic field in a neutron star is developed, based on an instability of the magnetic field caused by the electroweak interaction between electrons and nucleons in nuclear matter. The rate of change of the helicity of electrons as they scatter on protons in the dense matter of a neutron star is calculated with the help of methods of quantum field theory. The influence of the electroweak interaction between electrons and background nucleons on the process of change of the helicity is examined. A kinetic equation is derived for the evolution of the chiral chemical potential. The results obtained are used to describe the evolution of the magnetic field in magnetars.

  19. Unfolding the Therapeutic Potential of Chemical Chaperones for Age-related Macular Degeneration

    PubMed Central

    Sauer, Theodor; Patel, Mrinali; Chan, Chi-Chao; Tuo, Jingsheng

    2008-01-01

    SUMMARY Recent studies suggest that pathological processes involved in age-related macular degeneration (AMD) might induce endoplasmic reticulum (ER) stress. Growing evidence demonstrates the ability of chemical chaperones to decrease ER stress and ameliorate ER stress-related disease phenotypes, suggesting that the field of chaperone therapy might hold novel treatments for AMD. In this review, we examine the evidence suggesting a role for ER stress in AMD. Furthermore, we discuss the use of chaperone therapy for the treatment of ER stress-associated diseases, including other neurodegenerative diseases and retinopathies. Finally, we examine strategies for identifying potential chaperone compounds and for experimentally demonstrating chaperone activity in in vitro and in vivo models of human disease. PMID:18528533

  20. Multicomponent diffusion under general chemical potential gradients. Final report, July 1, 1981-June 30, 1984

    SciTech Connect

    Sato, H.; Kikuchi, R.

    1984-06-01

    Theoretical basis for identifying the origin of deterioration of high temperature materials by diffusion has been sought. The need for an appropriate form of irreversible statistical mechanics, rather than commonly utilized irreversible thermodynamics, to this problem was identified. The Path Probability method of irreversible statistical mechanics was thus adapted to diffusion problems and necessary modifications of the method suitable for transport problems in multicomponent systems were made. Thermal diffusion (diffusion which occurs under temperature gradient) was then formulated by the Path Probability method for the first time, and so far elusive concepts such as the heat of transport were thus microscopically identified. An example of demixing of originally homogeneous solid solutions under general chemical potential gradients was thus worked out.

  1. The OSHA and EPA programs on preventing chemical accidents and potential applications in the photovoltaic industry

    SciTech Connect

    Fthenakis, V.M.

    1996-08-01

    OSHA issued in 1992, the Process Safety Management (PSM) of Highly Hazardous Substances. This rule requires owners/operators of facilities that handle hazardous chemicals in quantities greater than the listed thresholds to establish all the elements of a PSM. EPA has issued in June 1996, the rules for a Risk Management Program which also refers to specific substances and threshold quantities. These rules are applicable to all the facilities that use or store any of 139 regulated substances at quantities ranging from 100 lb to 10,000 lb. The RMP rule covers off-site hazards, while the OSHA Process Safety Management (PSM) rule covers worker safety issues within the plant boundary. Some of the listed substances may be found in photovoltaic manufacturing facilities. This brief report presents the basic elements of these two rules and discusses their potential applicability in the photovoltaic industry.

  2. Cohort mortality study of chemical workers with potential exposure to the higher chlorinated dioxins

    SciTech Connect

    Ott, M.G.; Olson, R.A.; Cook, R.R.; Bond, G.G.

    1987-05-01

    This cohort study evaluated mortality patterns, 1940 through 1982, of 2,192 chemical workers who, having engaged in the manufacture of higher chlorinated phenols and derivative products, had potential occupational exposures to chlorinated dioxins. Relative to United States white male mortality experience, there were no statistically significant deviations from expected for the following categories: all causes, total malignant neoplasms, or specific malignancies of particular interest: stomach cancer, liver cancer, connective and other soft-tissue cancer, the lymphomas, or nasal and nasopharyngeal cancer. For the cirrhosis of the liver category, internal comparisons demonstrated increasing trends associated with duration of employment in the Chlorophenol Production and Finishing areas; but available evidence suggests this finding was related to alcohol abuse. The study does not support a causal association between chronic human disease as measured by mortality and exposures to the higher chlorinated phenols, derivative products, or their unwanted contaminants, the chlorinated dioxins.

  3. Formation of a two-component Bose condensate during the chemical-potential curve crossing

    SciTech Connect

    Kayali, M.A.; Sinitsyn, N.A.

    2003-04-01

    In this paper, we study the coherent dissociation of a molecular condensate into a multiple-mode atomic condensate during the chemical-potential curve crossing beyond the mean-field approximation. We show that the problem can be reduced to the dissociation of a molecular condensate into a two-mode atomic one. We employ the time-dependent Landau-Zener theory and derive analytical expression for the transition amplitudes. We calculate the number of produced atoms and show that they exist in squeezed state. We also study the formation of multiple-mode atomic condensate by inelastic scatterings of atoms in a single-mode atomic condensate. We show that the problem is also a Landau-Zener-like and exact solution can be found by imposing an additional symmetry.

  4. Changes in the Chemical Barrier Composition of Tears in Alzheimer's Disease Reveal Potential Tear Diagnostic Biomarkers.

    PubMed

    Kalló, Gergő; Emri, Miklós; Varga, Zsófia; Ujhelyi, Bernadett; Tőzsér, József; Csutak, Adrienne; Csősz, Éva

    2016-01-01

    Alzheimer's disease (AD) is one of the most common neurodegenerative diseases, with increasing prevalence affecting millions of people worldwide. Currently, only autopsy is able to confirm the diagnosis with a 100% certainty, therefore, biomarkers from body fluids obtained by non-invasive means provide an attractive alternative for the diagnosis of Alzheimer`s disease. Global changes of the protein profile were examined by quantitative proteomics; firstly, electrophoresis and LC-MS/MS were used, thereafter, SRM-based targeted proteomics method was developed and applied to examine quantitative changes of tear proteins. Alterations in the tear flow rate, total tear protein concentration and composition of the chemical barrier specific to AD were demonstrated, and the combination of lipocalin-1, dermcidin, lysozyme-C and lacritin was shown to be a potential biomarker, with an 81% sensitivity and 77% specificity.

  5. Potential for ultrafast dynamic chemical imaging with few-cycle infrared lasers

    NASA Astrophysics Data System (ADS)

    Morishita, Toru; Le, Anh-Thu; Chen, Zhangjin; Lin, C. D.

    2008-02-01

    We studied the photoelectron spectra generated by an intense few-cycle infrared laser pulse. By focusing on the angular distributions of the back rescattered high energy photoelectrons, we show that accurate differential elastic scattering cross-sections of the target ion by free electrons can be extracted. Since the incident direction and the energy of the free electrons can be easily changed by manipulating the laser's polarization, intensity and wavelength, these extracted elastic scattering cross-sections, in combination with more advanced inversion algorithms, may be used to reconstruct the effective single-scattering potential of the molecule, thus opening up the possibility of using few-cycle infrared lasers as powerful table-top tools for imaging chemical and biological transformations, with the desired unprecedented temporal and spatial resolutions.

  6. The strong isospin-breaking correction for the gluonic penguin contribution to {epsilon}{prime}/{epsilon} at next-to-leading order in the chiral expansion

    SciTech Connect

    Wolfe, Carl E.; Maltman, Kim

    2001-01-01

    The strong isospin-breaking correction {Omega}{sub st}, which appears in estimates of the standard model value for the direct CP-violating ratio {epsilon}{prime}/{epsilon}, is evaluated to next-to-leading order (NLO) in the chiral expansion using chiral perturbation theory. The relevant linear combinations of the unknown NLO CP-odd weak low-energy constants (LEC's) which, in combination with one-loop and strong LEC contributions, are required for a complete determination at this order, are estimated using two different models. It is found that, to NLO, {Omega}{sub st}=0.08{+-}0.05, significantly reduced from the ''standard'' value, 0.25{+-}0.08, employed in recent analyses. The potentially significant numerical impact of this decrease on standard model predictions for {epsilon}{prime}/{epsilon}, associated with the decreased cancellation between gluonic penguin and electroweak penguin contributions, is also discussed.

  7. The Isospin Admixture of The Ground State and The Properties of The Isobar Analog Resonances In Deformed Nuclei

    SciTech Connect

    Aygor, H. Ali; Maras, Ismail; Cakmak, Necla; Selam, Cevad

    2008-11-11

    Within quasiparticle random phase approximation (QRPA), Pyatov-Salamov method for the self-consistent determination of the isovector effective interaction strength parameter, restoring a broken isotopic symmetry for the nuclear part of the Hamiltonian, is used. The isospin admixtures in the ground state of the parent nucleus, and the isospin structure of the isobar analog resonance (IAR) state are investigated by including the pairing correlations between nucleons for {sup 72-80}Kr isotopes. Our results are compared with the spherical case and with other theoretical results.

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

    PubMed

    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.

  9. Time difference of arrival to blast localization of potential chemical/biological event on the move

    NASA Astrophysics Data System (ADS)

    Morcos, Amir; Desai, Sachi; Peltzer, Brian; Hohil, Myron E.

    2007-10-01

    Integrating a sensor suite with ability to discriminate potential Chemical/Biological (CB) events from high-explosive (HE) events employing a standalone acoustic sensor with a Time Difference of Arrival (TDOA) algorithm we developed a cueing mechanism for more power intensive and range limited sensing techniques. Enabling the event detection algorithm to locate to a blast event using TDOA we then provide further information of the event as either Launch/Impact and if CB/HE. The added information is provided to a range limited chemical sensing system that exploits spectroscopy to determine the contents of the chemical event. The main innovation within this sensor suite is the system will provide this information on the move while the chemical sensor will have adequate time to determine the contents of the event from a safe stand-off distance. The CB/HE discrimination algorithm exploits acoustic sensors to provide early detection and identification of CB attacks. Distinct characteristics arise within the different airburst signatures because HE warheads emphasize concussive and shrapnel effects, while CB warheads are designed to disperse their contents over large areas, therefore employing a slower burning, less intense explosive to mix and spread their contents. Differences characterized by variations in the corresponding peak pressure and rise time of the blast, differences in the ratio of positive pressure amplitude to the negative amplitude, and variations in the overall duration of the resulting waveform. The discrete wavelet transform (DWT) is used to extract the predominant components of these characteristics from air burst signatures at ranges exceeding 3km. Highly reliable discrimination is achieved with a feed-forward neural network classifier trained on a feature space derived from the distribution of wavelet coefficients and higher frequency details found within different levels of the multiresolution decomposition. The development of an adaptive noise

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

    PubMed Central

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

    2015-01-01

    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. PMID:26212309

  11. Foundations of modeling in cryobiology-I: concentration, Gibbs energy, and chemical potential relationships.

    PubMed

    Anderson, Daniel M; Benson, James D; Kearsley, Anthony J

    2014-12-01

    Mathematical modeling plays an enormously important role in understanding the behavior of cells, tissues, and organs undergoing cryopreservation. Uses of these models range from explanation of phenomena, exploration of potential theories of damage or success, development of equipment, and refinement of optimal cryopreservation/cryoablation strategies. Over the last half century there has been a considerable amount of work in bio-heat and mass-transport, and these models and theories have been readily and repeatedly applied to cryobiology with much success. However, there are significant gaps between experimental and theoretical results that suggest missing links in models. One source for these potential gaps is that cryobiology is at the intersection of several very challenging aspects of transport theory: it couples multi-component, moving boundary, multiphase solutions that interact through a semipermeable elastic membrane with multicomponent solutions in a second time-varying domain, during a two-hundred Kelvin temperature change with multi-molar concentration gradients and multi-atmosphere pressure changes. In order to better identify potential sources of error, and to point to future directions in modeling and experimental research, we present a three part series to build from first principles a theory of coupled heat and mass transport in cryobiological systems accounting for all of these effects. The hope of this series is that by presenting and justifying all steps, conclusions may be made about the importance of key assumptions, perhaps pointing to areas of future research or model development, but importantly, lending weight to standard simplification arguments that are often made in heat and mass transport. In this first part, we review concentration variable relationships, their impact on choices for Gibbs energy models, and their impact on chemical potentials.

  12. Giant Peak Voltage of Thermopower Waves Driven by the Chemical Potential Gradient of Single-Crystalline Bi2 Te3.

    PubMed

    Singh, Swati; Mun, Hyeona; Lee, Sanghoon; Kim, Sung Wng; Baik, Seunghyun

    2017-09-01

    The self-propagating exothermic chemical reaction with transient thermovoltage, known as the thermopower wave, has received considerable attention recently. A greater peak voltage and specific power are still demanded, and materials with greater Seebeck coefficients have been previously investigated. However, this study employs an alternative mechanism of transient chemical potential gradient providing an unprecedentedly high peak voltage (maximum: 8 V; average: 2.3 V) and volume-specific power (maximum: 0.11 W mm(-3) ; average: 0.04 W mm(-3) ) using n-type single-crystalline Bi2 Te3 substrates. A mixture of nitrocellulose and sodium azide is used as a fuel, and ultraviolet photoelectron spectroscopy reveals a significant downshift in Fermi energy (≈5.09 eV) of the substrate by p-doping of the fuel. The induced electrical potential by thermopower waves has two distinct sources: the Seebeck effect and the transient chemical potential gradient. Surprisingly, the Seebeck effect contribution is less than 2.5% (≈201 mV) of the maximum peak voltage. The right combination of substrate, fuel doping, and anisotropic substrate geometry results in an order of magnitude greater transient chemical potential gradient (≈5.09 eV) upon rapid removal of fuel by exothermic chemical reaction propagation. The role of fuel doping and chemical potential gradient can be viewed as a key mechanism for enhanced heat to electric conversion performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Isospin quartic term in the kinetic energy of neutron-rich nucleonic matter

    NASA Astrophysics Data System (ADS)

    Cai, Bao-Jun; Li, Bao-An

    2015-07-01

    The energy of a free gas of neutrons and protons is well known to be approximately isospin parabolic with a negligibly small quartic term of only 0.45 MeV at the saturation density of nuclear matter ρ0=0.16 fm-3 . Using an isospin-dependent single-nucleon momentum distribution including a high (low) momentum tail (depletion) with its shape parameters constrained by recent high-energy electron scattering and medium-energy nuclear photodisintegration experiments as well as the state-of-the-art calculations of the deuteron wave function and the equation of state of pure neutron matter near the unitary limit within several modern microscopic many-body theories, we show for the first time that the kinetic energy of interacting nucleons in neutron-rich nucleonic matter has a significant quartic term of 7.18 ±2.52 MeV. Such a large quartic term has broad ramifications in determining the equation of state of neutron-rich nucleonic matter using observables of nuclear reactions and neutron stars.

  14. Isospin-violating dark matter in the light of recent data

    NASA Astrophysics Data System (ADS)

    Yaguna, Carlos E.

    2017-03-01

    In scenarios where dark matter interacts differently with protons and neutrons (isospin-violating dark matter), the interpretation of the experimental limits on the dark matter spin-independent cross section may be significantly modified. On the one hand, the direct detection constraints are shifted depending on the target nucleus, possibly changing the hierarchy among different experiments. On the other hand, the relative strength between the bounds from neutrino detectors and those from direct detection experiments is altered, allowing the former to be more competitive. In this paper, the status of isospin-violating dark matter is assessed in the light of recent data, and the prospects for its detection in the near future are analyzed. We find, for example, that there are regions in the parameter space where IceCube currently provides the most stringent limits on the spin-independent cross section, or others where the expected sensitivity of DEAP-3600 is well above the LUX exclusion limit. Our results highlight the complementarity among different targets in direct detection experiments, and between direct detection and neutrino searches in the quest for a dark matter signal.

  15. Isospin susceptibility in the O( n) sigma-model in the delta-regime

    NASA Astrophysics Data System (ADS)

    Niedermayer, F.; Weisz, P.

    2017-06-01

    We compute the isospin susceptibility in an effective O( n) scalar field theory (in d = 4 dimensions), to third order in chiral perturbation theory ( χPT) in the delta-regime using the quantum mechanical rotator picture. This is done in the presence of an additional coupling, involving a parameter η, describing the effect of a small explicit symmetry breaking term (quark mass). For the chiral limit η = 0 we demonstrate consistency with our previous χPT computations of the finite-volume mass gap and isospin susceptibility. For the massive case by computing the leading mass effect in the susceptibility using χPT with dimensional regularization, we determine the χPT expansion for η to third order. The behavior of the shape coefficients for long tube geometry obtained here might be of broader interest. The susceptibility calculated from the rotator approximation differs from the χPT result in terms vanishing like 1 /ℓ for ℓ = L t /L s → ∞. We show that this deviation can be described by a correction to the rotator spectrum proportional to the square of the quadratic Casimir invariant.

  16. Change of Electroweak Nuclear Reaction Rates by CP- and Isospin Symmetry Breaking - A Model Calculation

    NASA Astrophysics Data System (ADS)

    Stumpf, Harald

    2006-09-01

    Based on the assumption that electroweak bosons, leptons and quarks possess a substructure of elementary fermionic constituents, in previous papers the effect of CP-symmetry breaking on the effective dynamics of these particles was calculated. Motivated by the phenomenological procedure in this paper, isospin symmetry breaking will be added and the physical consequences of these calculations will be discussed. The dynamical law of the fermionic constituents is given by a relativistically invariant nonlinear spinor field equation with local interaction, canonical quantization, selfregularization and probability interpretation. The corresponding effective dynamics is derived by algebraic weak mapping theorems. In contrast to the commonly applied modifications of the quark mass matrices, CP-symmetry breaking is introduced into this algebraic formalism by an inequivalent vacuum with respect to the CP-invariant case, represented by a modified spinor field propagator. This leads to an extension of the standard model as effective theory which contains besides the "electric" electroweak bosons additional "magnetic" electroweak bosons and corresponding interactions. If furthermore the isospin invariance of the propagator is broken too, it will be demonstrated in detail that in combination with CP-symmetry breaking this induces a considerable modification of electroweak nuclear reaction rates.

  17. Nuclear response theory for spin-isospin excitations in a relativistic quasiparticle-phonon coupling framework

    NASA Astrophysics Data System (ADS)

    Robin, Caroline; Litvinova, Elena

    2016-07-01

    A new theoretical approach to spin-isospin excitations in open-shell nuclei is presented. The developed method is based on the relativistic meson-exchange nuclear Lagrangian of Quantum Hadrodynamics and extends the response theory for superfluid nuclear systems beyond relativistic quasiparticle random phase approximation in the proton-neutron channel (pn-RQRPA). The coupling between quasiparticle degrees of freedom and collective vibrations (phonons) introduces a time-dependent effective interaction, in addition to the exchange of pion and ρ -meson taken into account without retardation. The time-dependent contributions are treated in the resonant time-blocking approximation, in analogy to the previously developed relativistic quasiparticle time-blocking approximation (RQTBA) in the neutral (non-isospin-flip) channel. The new method is called proton-neutron RQTBA (pn-RQTBA) and is applied to the Gamow-Teller resonance in a chain of neutron-rich nickel isotopes 68-78Ni . A strong fragmentation of the resonance along with quenching of the strength, as compared to pn-RQRPA, is obtained. Based on the calculated strength distribution, beta-decay half-lives of the considered isotopes are computed and compared to pn-RQRPA half-lives and to experimental data. It is shown that a considerable improvement of the half-life description is obtained in pn-RQTBA because of the spreading effects, which bring the lifetimes to a very good quantitative agreement with data.

  18. Isospin symmetry violating effects and scattering length extraction from kaon decays

    SciTech Connect

    Gevorkyan, S. R.

    2013-08-15

    The isospin symmetry breaking effects in the charged kaons decays to two or three pions are considered. In semileptonic decay K{sup {+-}} {yields} {pi}{sup +}{pi}{sup -}e{sup {+-}}{nu} (called K{sub e4}) these effects turn out to be crucial for correct extraction of {pi}{pi} scattering lengths. Taking in account electromagnetic interaction between the pions in the final state and isospin symmetry breaking due to different masses of charged and neutral pions allows to adjust the values of scattering lengths obtained from experimental data on K{sub e4} decay and predictions of Chiral Perturbation Theory (ChPT). Final state interactions of pions in the decay K{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup 0}{pi}{sup 0} leading to the anomaly (cusp) in the {pi}{sup 0}{pi}{sup 0} invariant mass distribution in the vicinity of charged pions' threshold are discussed and recent results of accounting of the electromagnetic interaction among charged pions leading to {pi}{sup +}{pi}{sup -} bound states (pioniumatom) just under the charged pions' threshold are presented.

  19. A DNA minor groove electronegative potential genome map based on photo-chemical probing.

    PubMed

    Lindemose, Søren; Nielsen, Peter Eigil; Hansen, Morten; Møllegaard, Niels Erik

    2011-08-01

    The double-stranded DNA of the genome contains both sequence information directly relating to the protein and RNA coding as well as functional and structural information relating to protein recognition. Only recently is the importance of DNA shape in this recognition process being fully appreciated, and it also appears that minor groove electronegative potential may contribute significantly in guiding proteins to their cognate binding sites in the genome. Based on the photo-chemical probing results, we have derived an algorithm that predicts the minor groove electronegative potential in a DNA helix of any given sequence. We have validated this model on a series of protein-DNA binding sites known to involve minor groove electrostatic recognition as well as on stable nucleosome core complexes. The algorithm allows for the first time a full minor groove electrostatic description at the nucleotide resolution of any genome, and it is illustrated how such detailed studies of this sequence dependent, inherent property of the DNA may reflect on genome organization, gene expression and chromosomal condensation.

  20. Chemical composition, antimicrobial and antioxidant potential of the essential oil of Guarea kunthiana A. Juss.

    PubMed

    Pandini, J A; Pinto, F G S; Scur, M C; Santana, C B; Costa, W F; Temponi, L G

    2017-07-27

    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.

  1. The potential of synthetic indolylquinoline derivatives for Aβ aggregation reduction by chemical chaperone activity.

    PubMed

    Chang, Kuo-Hsuan; Chiu, Ya-Jen; Chen, Shu-Ling; Huang, Chen-Hsiang; Lin, Chih-Hsin; Lin, Te-Hsien; Lee, Chi-Mei; Ramesh, Chintakunta; Wu, Chung-Hsin; Huang, Chin-Chang; Fung, Hon-Chung; Chen, Yi-Chun; Lin, Jung-Yaw; Yao, Ching-Fa; Huang, Hei-Jen; Lee-Chen, Guey-Jen; Lee, Ming-Chung; Hsieh-Li, Hsiu Mei

    2016-02-01

    Alzheimer's disease (AD) is the most prevalent form of dementia associated with progressive cognitive decline and memory loss. Extracellular β-amyloid (Aβ) is a major constituent of senile plaques, one of the pathological hallmarks of AD. Aβ deposition causes neuronal death via a number of possible mechanisms such as increasing oxidative stress. Therefore therapeutic approaches to identify novel Aβ aggregate reducers could be effective for AD treatment. Using a Trx-His-Aβ biochemical assay, we screened 11 synthetic indolylquinoline compounds, and found NC009-1, -2, -6 and -7 displaying potential to reduce Aβ aggregation. Treating Tet-On Aβ-GFP 293 cells with these compounds reduced Aβ aggregation and reactive oxygen species. These compounds also promoted neurite outgrowth in Tet-On Aβ-GFP SH-SY5Y cells. Furthermore, treatment with above compounds improved neuronal cell viability, neurite outgrowth, and synaptophysin expression level in mouse hippocampal primary culture under oligomeric Aβ-induced cytotoxicity. Moreover, the tested NC009-1 significantly ameliorated Aβ-induced inhibition of hippocampal long-term potentiation in mouse hippocampal slices. Our results demonstrate how synthetic indolylquinoline compounds are likely to work as chemical chaperones in Aβ-aggregation reduction and neuroprotection, providing insight into the possible applications of indolylquinoline compounds in AD treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Multidirectional characterisation of chemical composition and health-promoting potential of Rosa rugosa hips.

    PubMed

    Olech, Marta; Nowak, Renata; Pecio, Łukasz; Łoś, Renata; Malm, Anna; Rzymowska, Jolanta; Oleszek, Wiesław

    2017-03-01

    Rugosa rose provides one of the largest hips frequently used in the preparation of pharmaceutical and food products. The aim of work was to conduct multidirectional study of biological activity and chemical composition of Rosa rugosa hips. Antiradical, cytotoxic (against cervical and breast cancer cell lines), antibacterial (against eight bacterial strains) and antifungal potential of the species in question was evaluated. Total contents of phenolics, phenolic acids, flavonoids, tannins, carotenoids and ascorbic acid were determined. LC-ESI-MS/MS analysis was performed in order to investigate closely phenolic acids and flavonoid glycosides. As a result, interesting selective cytotoxic effects on cervical (HeLa) and breast cancer (T47D) cell lines, significant antiradical activity (EC50 2.45 mg mg(-1) DPPH(•)) and moderate antimicrobial potential (MIC 0.625-1.25 mg mL(-1)) were observed. Nine phenolic acids and 11 flavonoid glycosides were qualitatively and quantitatively determined, including 7 compounds previously not reported in R. rugosa hips.

  3. Adhesion Potential of Intestinal Microbes Predicted by Physico-Chemical Characterization Methods

    PubMed Central

    Niederberger, Tobias; Fischer, Peter; Rühs, Patrick Alberto

    2015-01-01

    Bacterial adhesion to epithelial surfaces affects retention time in the human gastro-intestinal tract and therefore significantly contributes to interactions between bacteria and their hosts. Bacterial adhesion among other factors is strongly influenced by physico-chemical factors. The accurate quantification of these physico-chemical factors in adhesion is however limited by the available measuring techniques. We evaluated surface charge, interfacial rheology and tensiometry (interfacial tension) as novel approaches to quantify these interactions and evaluated their biological significance via an adhesion assay using intestinal epithelial surface molecules (IESM) for a set of model organisms present in the human gastrointestinal tract. Strain pairs of Lactobacillus plantarum WCFS1 with its sortase knockout mutant Lb. plantarum NZ7114 and Lb. rhamnosus GG with Lb. rhamnosus DSM 20021T were used with Enterococcus faecalis JH2-2 as control organism. Intra-species comparison revealed significantly higher abilities for Lb. plantarum WCSF1 and Lb. rhamnosus GG vs. Lb. plantarum NZ7114 and Lb. rhamnosus DSM 20021T to dynamically increase interfacial elasticity (10−2 vs. 10−3 Pa*m) and reduce interfacial tension (32 vs. 38 mN/m). This further correlated for Lb. plantarum WCSF1 and Lb. rhamnosus GG vs. Lb. plantarum NZ7114 and Lb. rhamnosus DSM 20021T with the decrease of relative hydrophobicity (80–85% vs. 57–63%), Zeta potential (-2.9 to -4.5 mV vs. -8.0 to -13.8 mV) and higher relative adhesion capacity to IESM (3.0–5.0 vs 1.5–2.2). Highest adhesion to the IESM collagen I and fibronectin was found for Lb. plantarum WCFS1 (5.0) and E. faecalis JH2-2 (4.2) whereas Lb. rhamnosus GG showed highest adhesion to type II mucus (3.8). Significantly reduced adhesion (2 fold) to the tested IESM was observed for Lb. plantarum NZ7114 and Lb. rhamnosus DSM 20021T corresponding with lower relative hydrophobicity, Zeta potential and abilities to modify interfacial

  4. Chemical Potential of Triethylene Glycol Adsorbed on Surfaces Relevant to Gas Transport and Processing - Studies Using Molecular Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Kvamme, B.; Olsen, R.; Sjöblom, S.; Leirvik, K. N.; Kuznetsova, T.

    2014-12-01

    Natural gas will inevitably contain trace amounts of water and other impurities during different stages of processing and transport. Glycols, such as triethylene glycol (TEG), will in many cases follow the water. The glycol contents of the gas can originate from preceding glycol-drying units or it can be a residue from the direct injection of glycols used to prevent hydrate formation. Thus, it is important to know how glycol contents will affect the different paths leading to hydrate formation. Glycols may in some cases dominate the condensed water phase. If this occurs, it will lead to the well-documented shift in the hydrate stability curve, due to the altered activity of the water. A great deal of information on the molecular path of a glycol through the system can be obtained from calculating the chemical potential. Due to difficulties in measuring interfacial chemical potentials, these often need to be estimated using theoretical tools. We used molecular dynamics (MD) to study how TEG behaves in the vicinity of mineral surfaces such as calcite and hematite. Many methods exist for estimating chemical potentials based on MD trajectories. These include techniques such as free energy perturbation theory (FEP) and thermodynamic integration (TI). Such methods require sufficient sampling of configurations where free energy is to be estimated. Thus, it can be difficult to estimate chemical potentials on surfaces. There are several methods to circumvent this problem, such as blue moon sampling and umbrella sampling. These have been considered and the most important have been used to estimate chemical potentials of TEG adsorbed on the mineral surfaces. The resulting chemical potentials were compared to the chemical potential of TEG in bulk water, which was estimated using temperature thermodynamic integration.

  5. Estimating the One-Electron Reduction Potential for Vanadium (V) by Chemical Techniques: An Experiment for General Chemistry.

    ERIC Educational Resources Information Center

    Wentworth, R. A. D.

    1985-01-01

    Describes an experiment which requires only qualitative observations, is suitable for general chemistry students, prompts an understanding of thermodynamic spontaneity, gives chemical meaning to electrode potentials, requires non-electrochemical equipment, and allows estimates of the standard potential for the reduction of Vanadium (V) to V (IV).…

  6. Estimating the One-Electron Reduction Potential for Vanadium (V) by Chemical Techniques: An Experiment for General Chemistry.

    ERIC Educational Resources Information Center

    Wentworth, R. A. D.

    1985-01-01

    Describes an experiment which requires only qualitative observations, is suitable for general chemistry students, prompts an understanding of thermodynamic spontaneity, gives chemical meaning to electrode potentials, requires non-electrochemical equipment, and allows estimates of the standard potential for the reduction of Vanadium (V) to V (IV).…

  7. Biodegradability and denitrification potential of settleable chemical oxygen demand in domestic wastewater.

    PubMed

    Tas, Didem Okutman; Karahan, Ozlem; Insel, Güçlü; Ovez, Süleyman; Orhon, Derin; Spanjers, Henri

    2009-07-01

    The effect of settling on mass balance and biodegradation characteristics of domestic wastewater and on denitrification potential was studied primarily using model calibration and evaluation of oxygen uptake rate profiles. Raw domestic wastewater was settled for a period of 30 minutes and a period of 2 hours to assess the effect of primary settling on wastewater characterization and composition. Mass balances in the system were made to evaluate the effect of primary settling on major parameters. Primary settling of the selected raw wastewater for 2 hours resulted in the removal of 32% chemical oxygen demand (COD), 9% total Kjeldahl nitrogen, 9% total phosphorus, and 47% total suspended solids. Respirometric analysis identified COD removed by settling as a new COD fraction, namely settleable slowly biodegradable COD (X(ss)), characterized by a hydrolysis rate of 1.0 day(-1) and a hydrolysis half-saturation coefficient of 0.08. A model simulation to test the fate and availability of suspended (X(s)) and settleable (X(ss)) COD fractions as carbon sources for denitrification showed that both particulate COD components were effectively removed aerobically at sludge ages higher than 1.5 to 2.0 days. Under anoxic conditions, the biodegradation of both COD fractions was reduced, especially below an anoxic sludge retention time of 3.0 days. Consequently, modeling results revealed that the settleable COD removed by primary settling could represent up to approximately 40% of the total denitrification potential of the system, depending on the specific configuration selected for the nitrogen removal process. This way, the results showed the significant effect of primary settling on denitrification, indicating that the settleable COD fraction could contribute an additional carbon source in systems where the denitrification potential associated with the influent becomes rate-limiting for the denitrification efficiency.

  8. TSCA Work Plan: 2012 Scoring of Potential Candidate Chemicals Entering Step 2

    EPA Pesticide Factsheets

    In 2012, EPA scored these chemicals based on hazard, exposure and persistence/bioaccumulation criteria as part of Step 2 in the Work Plan methodology in order to identify candidate chemicals for near-term review and assessment under TSCA.

  9. Improving intermolecular interactions in DFTB3 using extended polarization from chemical-potential equalization.

    PubMed

    Christensen, Anders S; Elstner, Marcus; Cui, Qiang

    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.

  10. Chemical Potential of the Solvent: A Crucial Player for Rationalizing Host-Guest Affinities.

    PubMed

    Baudet, Karine; Guerra, Sebastiano; Piguet, Claude

    2017-08-08

    Access to reliable values of the thermodynamic constants β1,1H,G , which control simple host-guest ([HG]) association, is crucial in medicine, biology, pharmacy, and chemistry, since the optimum concentration of an effector (i.e., a drug) acting on a receptor is set to 1β1,1H,G . Intermolecular association between charged species in polar solvents, for which water is the archetype, largely obeys this principle. Any deviation from ideality, which alters the speciation in solution, is mastered by the Debye-Hückel theory of ionic atmosphere. Much less is known for related association reactions involving neutral species in non-polar (lipophilic) media such as membranes, bilayers, or organic polymers. Taking the intermolecular association between [La(hfa)3 dig] guest (hfa=hexafluoroacetylacetonate, dig=2-{2-methoxyethoxy}ethane) and tridentate polyaromatic host receptors L1-L3 in dichloromethane as a proof-of-concept, we show that the progress of the association reactions, as measured by the increase in the mole fraction of occupied sites of the receptors, disrupt the chemical potential of the solvent to such an extent that β1,1H,G may seemingly be shifted by two orders of magnitude, thus leading to erroneous dose-response prescriptions. A simple chemical model, which considers a subset of solvent molecules in surface contact with the partners of the association reaction, restores reliable access to true and interpretable thermodynamic constants. The concomitant emergence of a concentration-dependent corrective parameter reestablishes satisfying dose-dependent response under real conditions. This "complement" to the law of mass action offers a simple method for safely taking care of the non-predictable variations of the activity coefficients of the various partners when host-guest reactions are conducted in non-polar media. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Chemical Analysis of Extracts from Newfoundland Berries and Potential Neuroprotective Effects.

    PubMed

    Hossain, Mohammad Z; Shea, Emily; Daneshtalab, Mohsen; Weber, John T

    2016-10-19

    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.

  12. Chemical Analysis of Extracts from Newfoundland Berries and Potential Neuroprotective Effects

    PubMed Central

    Hossain, Mohammad Z.; Shea, Emily; Daneshtalab, Mohsen; Weber, John T.

    2016-01-01

    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. PMID:27775557

  13. Improving intermolecular interactions in DFTB3 using extended polarization from chemical-potential equalization

    SciTech Connect

    Christensen, Anders S. E-mail: cui@chem.wisc.edu; Cui, Qiang E-mail: cui@chem.wisc.edu; Elstner, Marcus

    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.

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

    PubMed

    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.

  15. Development of human cell models for assessing the carcinogenic potential of chemicals

    SciTech Connect

    Pang Yaqin; Li Wenxue; Ma Rulin; Ji Weidong; Wang Qing; Li Daochuan; Xiao Yongmei; Wei Qing; Lai Yandong; Yang Ping; Chen Liping; Tang Shifu; Lin Yuchun; Zhuang Zhixiong; Zheng Yuxin; Chen Wen

    2008-11-01

    To develop human cell models for assessing the carcinogenic potential of chemicals, we established transgenic human cell lines and tested the sensitivity of known carcinogens using a cell transformation assay. A retroviral vector encoding an oncogenic allele of H-Ras (HBER) or c-Myc (HBEM) was introduced into human bronchial epithelial cells (HBE) immortalized by SV40 large T (LT) antigen, leading to increased cell proliferation but failing to confer a transformed phenotype characterized by anchorage-independent cell growth and tumor formation of immunodeficient mice. When these pre-transformed cells were treated with nickel sulfate (NiSO{sub 4}), we found that it shortened the latency of malignant transformation at least by 19 wk in HBER cells or 16 wk in HBEM cells compared to vector control cells. Similarly, the latency of cell transformation was shorter by 15 wk in HBER cells or 9 wk in HBEM cells when cells were treated with benzo(a)pyrenediol epoxide (BPDE). HBER cells appeared to be more sensitive to TPA, NiSO{sub 4} or BPDE-induced cell transformation compared to human embryonic kidney cells expressing H-Ras (HEKR), implying that cell-type specificity is one of important factors determining the effectiveness of the assay. Using AFB{sub 1} and BaP as the representative pro-carcinogens, we also compared the efficiency of three different metabolic conditions in mediating cell transformation. Low dose chemical induction seems to be a prospective system used for metabolic activation of pro-carcinogens. Our findings provided direct evidence that a genetically modified human cell transformation model can be applied to the assessment of potent carcinogens.

  16. Chemical form of metals in traditional medicines underlines potential toxicity in cell cultures.

    PubMed

    Wu, Qin; Lu, Yuan-Fu; Shi, Jing-Zhen; Liang, Shi-Xia; Shi, Jin-Shan; Liu, Jie

    2011-04-12

    Mercury (Hg) and arsenic (As) are frequently found in traditional medicines as sulfides, such as cinnabar (HgS) and realgar (As(4)S(4)). There is a general perception that any medicinal use of such metal-containing remedies is unacceptable. An opposing opinion is that different chemical forms of arsenic and mercury have different toxic potentials. To clarify this question, cinnabar, realgar, and cinnabar- and realgar-containing traditional medicine An-Gong-Niu-HuangWan (AGNH), were compared to well-known mercurials (HgS, HgCl(2) and MeHg) and arsenicals (As(2)S(2), As(2)O(3), NaAsO(2), and Na(2)HAsO(4)) for their cytotoxicity in human and rodent cell lines. Cultured cells derived from target organs such as brain (HAPI) and liver (Hep3B, HepG2 and TRL1215) were treated with chemicals for 48 h and cytotoxicity was determined by the MTS assay. MeHg was most toxic with LC(50) of 4-20μM, followed by NaAsO(2) (LC(50), 25-250 μM) and HgCl(2) (LC(50,) 50-100 μM), Na(2)HAsO(4)(LC(50), 60-400μM), As(2)O(3)(LC(50), 30-900 μM), and As(2)S(2) (LC(50), 100-500 μM). In comparison, the LC(50) of realgar ranged from 250 to1500 μM; whereas cinnabar or HgS were approximately 20,000 μM and the toxicity of AGNH was in the range of 1500-8000 μM. Approximately 5000-fold differences exist between MeHg and HgS, and over 10-fold differences exist between NaAsO(2) and As(4)S(4). Chemical forms of metals are important factor in determining their toxicity in traditional medicines, both cinnabar and realgar are much less toxic than well-known mercurial and arsenicals. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  17. Localization and visualization of excess chemical potential in statistical mechanical integral equation theory 3D-HNC-RISM.

    PubMed

    Du, Qi-Shi; Liu, Peng-Jun; Huang, Ri-Bo

    2008-02-01

    In this study the excess chemical potential of the integral equation theory, 3D-RISM-HNC [Q. Du, Q. Wei, J. Phys. Chem. B 107 (2003) 13463-13470], is visualized in three-dimensional form and localized at interaction sites of solute molecule. Taking the advantage of reference interaction site model (RISM), the calculation equations of chemical excess potential are reformulized according to the solute interaction sites s in molecular space. Consequently the solvation free energy is localized at every interaction site of solute molecule. For visualization of the 3D-RISM-HNC calculation results, the excess chemical potentials are described using radial and three-dimensional diagrams. It is found that the radial diagrams of the excess chemical potentials are more sensitive to the bridge functions than the radial diagrams of solvent site density distributions. The diagrams of average excess chemical potential provide useful information of solute-solvent electrostatic and van der Waals interactions. The local description of solvation free energy at active sites of solute in 3D-RISM-HNC may broaden the application scope of statistical mechanical integral equation theory in solution chemistry and life science.

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

    SciTech Connect

    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.

  19. Adsorption and capillary condensation in porous media as a function of the chemical potential of water in carbon dioxide

    NASA Astrophysics Data System (ADS)

    Heath, Jason E.; Bryan, Charles R.; Matteo, Edward N.; Dewers, Thomas A.; Wang, Yifeng; Sallaberry, Cédric J.

    2014-03-01

    The chemical potential of water may play an important role in adsorption and capillary condensation of water under multiphase conditions at geologic CO2 storage sites. Injection of large volumes of anhydrous CO2 will result in changing values of the chemical potential of water in the supercritical CO2 phase. We hypothesize that the chemical potential will at first reflect the low concentration of dissolved water in the dry CO2. As formation water dissolves into and is transported by the CO2 phase, the chemical potential of water will increase. We present a pore-scale model of the CO2-water interface or menisci configuration based on the augmented Young-Laplace equation, which combines adsorption on flat surfaces and capillary condensation in wedge-shaped pores as a function of chemical potential of water. The results suggest that, at a given chemical potential for triangular and square pores, liquid water saturation will be less in the CO2-water system under potential CO2 sequestration conditions relative to the air-water vadose zone system. The difference derives from lower surface tension of the CO2-water system and thinner liquid water films, important at pore sizes <1 × 10-6 m, relative to the air-water system. Water movement due to capillary effects will likely be minimal in reservoir rocks, but still may be important in finer grained, clayey caprocks, where very small pores may retain water and draw water back into the system via adsorption and capillary condensation, if dry-out and then rewetting were to occur.

  20. Effect of entrance-channel asymmetry on the isospin dependence of nucleon emission in heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Zhang, Fang; Zuo, Wei; Chen, Ji-Yan; Zhou, Zhen-Xiao

    2008-07-01

    Using the isospin- and momentum-dependent hadronic transport model IBUU04, we have investigated the influence of the entrance-channel isospin asymmetry on the sensitivity of the pre-equilibrium neutron/proton ratio to symmetry energy in central heavy-ion collisions induced by high-energy radioactive beams. Our analysis and discussion are based on the dynamical simulations of the three isotopic reaction systems 132Sn+124Sn, 124Sn+112Sn and 112Sn+112Sn which are of the same total proton number but different isospin asymmetry. We find that the kinetic-energy distributions of the pre-equilibrium neutron/proton ratio are quite sensitive to the density-dependence of symmetry energy at incident beam energy E/A = 400 MeV, and the sensitivity increases as the isospin asymmetry of the reaction system increases. Supported by National Natural Science Foundation of China (10575119, 10775061), Knowledge Innovation Project of Chinese Academy of Sciences (KJCX3-SYW-N2), Major State Basic Research Developing Program of China (2007CB815004), CAS/SAFEA International Partnership Program for Creative Research Teams (CXTD-J2005-1), and the Asia-Link Project of the European Commission (CN/ASIA-LINK/008(94791))

  1. Bioanalytical and chemical assessment of the disinfection by-product formation potential: role of organic matter.

    PubMed

    Farré, Maria José; Day, Sophie; Neale, Peta A; Stalter, Daniel; Tang, Janet Y M; Escher, Beate I

    2013-09-15

    Disinfection by-products (DBP) formed from natural organic matter and disinfectants like chlorine and chloramine may cause adverse health effects. Here, we evaluate how the quantity and quality of natural organic matter and other precursors influence the formation of DBPs during chlorination and chloramination using a comprehensive approach including chemical analysis of regulated and emerging DBPs, total organic halogen quantification, organic matter characterisation and bioanalytical tools. In vitro bioassays allow us to assess the hazard potential of DBPs early in the chain of cellular events, when the DBPs react with their molecular target(s) and activate stress response and defence mechanisms. Given the reactive properties of known DBPs, a suite of bioassays targeting reactive modes of toxic action including genotoxicity and sensitive early warning endpoints such as protein damage and oxidative stress were evaluated in addition to cytotoxicity. Coagulated surface water was collected from three different drinking water treatment plants, along with reverse osmosis permeate from a desalination plant, and DBP formation potential was assessed after chlorination and chloramination. While effects were low or below the limit of detection before disinfection, the observed effects and DBP levels increased after disinfection and were generally higher after chlorination than after chloramination, indicating that chlorination forms higher concentrations of DBPs or more potent DBPs in the studied waters. Bacterial cytotoxicity, assessed using the bioluminescence inhibition assay, and induction of the oxidative stress response were the most sensitive endpoints, followed by genotoxicity. Source waters with higher dissolved organic carbon levels induced increased DBP formation and caused greater effects in the endpoints related to DNA damage repair, glutathione conjugation/protein damage and the Nrf2 oxidative stress response pathway after disinfection. Fractionation studies

  2. UV-visible spectroscopy method for screening the chemical stability of potential antioxidants for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Banham, Dustin; Ye, Siyu; Knights, Shanna; Stewart, S. Michael; Wilson, Mahlon; Garzon, Fernando

    2015-05-01

    A novel method based on UV-visible spectroscopy is reported for screening the chemical stability of potential antioxidant additives for proton exchange membrane fuel cells, and the chemical stabilities of three CeOx samples of varying crystallite sizes (6, 13, or 25 nm) are examined. The chemical stabilities predicted by this new screening method are compared to in-situ membrane electrode assembly (MEA) accelerated stress testing, with the results confirming that this rapid and inexpensive method can be used to accurately predict performance impacts of antioxidants.

  3. Antimicrobial Potential and Chemical Characterization of Serbian Liverwort (Porella arboris-vitae): SEM and TEM Observations.

    PubMed

    Kumar Tyagi, Amit; Bukvicki, Danka; Gottardi, Davide; Veljic, Milan; Guerzoni, Maria Elisabetta; Malik, Anushree; Marin, Petar D

    2013-01-01

    The chemical composition of Porella arboris-vitae extracts was determined by solid phase microextraction, gas chromatography-mass spectrometry (SPME GC-MS), and 66 constituents were identified. The dominant compounds in methanol extract of P. arboris-vitae were β-caryophyllene (14.7%), α-gurjunene (10.9%), α-selinene (10.8%), β-elemene (5.6%), γ-muurolene (4.6%), and allo-aromadendrene (4.3%) and in ethanol extract, β-caryophyllene (11.8%), α-selinene (9.6%), α-gurjunene (9.4%), isopentyl alcohol (8.8%), 2-hexanol (3.7%), β-elemene (3.7%), allo-aromadendrene (3.7%), and γ-muurolene (3.3%) were the major components. In ethyl acetate extract of P. arboris-vitae, undecane (11.3%), β-caryophyllene (8.4%), dodecane (6.4%), α-gurjunene (6%), 2-methyldecane (5.1%), hemimellitene (4.9%), and D-limonene (3.9%) were major components. The antimicrobial activity of different P. arboris-vitae extracts was evaluated against selected food spoilage microorganisms using microbroth dilution method. The Minimal Inhibitory Concentration (MIC) varied from 0.5 to 1.5 mg/mL and 1.25 to 2 mg/mL for yeast and bacterial strains, respectively. Significant morphological and ultrastructural alterations due to the effect of methanolic and ethanolic P. arboris-vitae extracts on S. Enteritidis have also been observed by scanning electron microscope and transmission electron microscope, respectively. The results provide the evidence of antimicrobial potential of P. arboris-vitae extracts and suggest its potential as natural antimicrobial agents for food preservation.

  4. Mapping the chemical potential dependence of current-induced spin polarization in a topological insulator

    NASA Astrophysics Data System (ADS)

    Lee, Joon Sue; Richardella, Anthony; Hickey, Danielle Reifsnyder; Mkhoyan, K. Andre; Samarth, Nitin

    2015-10-01

    We report electrical measurements of the current-induced spin polarization of the surface current in topological insulator devices where contributions from bulk and surface conduction can be disentangled by electrical gating. The devices use a ferromagnetic tunnel junction (permalloy/Al 2O3 ) as a spin detector on a back-gated (Bi,Sb ) 2Te3 channel. We observe hysteretic voltage signals as the magnetization of the detector ferromagnet is switched parallel or antiparallel to the spin polarization of the surface current. The amplitude of the detected voltage change is linearly proportional to the applied dc bias current in the (Bi,Sb ) 2Te3 channel. As the chemical potential is tuned from the bulk bands into the surface state band, we observe an enhancement of the spin-dependent voltages up to 300% within the range of the electrostatic gating. Using a simple model, we extract the spin polarization near charge neutrality (i.e., the Dirac point).

  5. A comparison of chemical mechanisms using Tagged Ozone Production Potential (TOPP) analysis

    NASA Astrophysics Data System (ADS)

    Coates, J.; Butler, T. M.

    2015-04-01

    Ground-level ozone is a secondary pollutant produced photochemically from reactions of NOx with peroxy radicals produced during 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 predictions. In this study, VOC degradation chemistry in simplified mechanisms is compared to that in the near-explicit MCM mechanism using a boxmodel and by "tagging" all organic degradation products over multi-day runs, thus calculating the Tagged Ozone Production Potential (TOPP) for a selection of VOC representative of urban airmasses. Simplified mechanisms that aggregate VOC degradation products instead of aggregating emitted VOC produce comparable amounts of O3 from VOC degradation to the MCM. First day TOPP values are similar across mechanisms for most VOC, with larger discrepancies arising over the course of the model run. Aromatic and unsaturated aliphatic VOC have largest inter-mechanisms differences on the first day, while alkanes show largest differences on the second day. Simplified mechanisms break down VOC 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.

  6. Subcellular distribution and chemical forms of cadmium in Impatiens walleriana in relation to its phytoextraction potential.

    PubMed

    Lai, Hung-Yu

    2015-11-01

    Impatiens (Impatiens walleriana) has been shown to be a potential cadmium (Cd) hyperaccumulator, but its mechanisms in accumulation and detoxification have not been reported. Rooted cuttings of Impatiens were planted in artificially Cd-contaminated soils for 50 days with total target concentrations of 0, 10, 20, 40, 80, and 120 mg/kg. The subcellular distribution and chemical forms of Cd in the different organs were analyzed after the pot experiment. Compared with the control group, various Cd treatments affected the growth exhibitions of Impatiens, but most of them were not statistically significant. The Cd accumulation of different organs increased with an increase in the soil Cd concentrations for most of the treatments, and it was in the decreasing order of root>stem>leaf. In the roots of Impatiens, Cd was mainly compartmentalized in the soluble fraction (Fs), which has a high migration capacity and will further translocate to the shoot. The Cd was mainly compartmentalized in the cell wall fraction (Fcw) in the shoots as a mechanism of tolerance. Most of the Cd in the various organs of Impatiens was mainly in the forms of pectate and protein-integrated (FNaCl), whereas a minor portion was a water soluble fraction (FW). The experimental results show that the Cd in the Fs, FW, and FNaCl in the roots of Impatiens had a high mobility and will further translocate to the shoot. They could be used to estimate the Cd accumulated in the shoots of Impatiens.

  7. Lepidopteran defence droplets - a composite physical and chemical weapon against potential predators.

    PubMed

    Pentzold, Stefan; Zagrobelny, Mika; Khakimov, Bekzod; Engelsen, Søren Balling; Clausen, Henrik; Petersen, Bent Larsen; Borch, Jonas; Møller, Birger Lindberg; Bak, Søren

    2016-03-04

    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 predators together and immobilised them. Droplets were characterised by a matrix of an aqueous solution of glycine-rich peptides (H-WG11-NH2) with significant amounts of proteins and glucose. Among the proteins, defensive proteins such as protease inhibitors, proteases and oxidases were abundant. The neurotoxin β-cyanoalanine was also found in the droplets. Despite the presence of cyanogenic glucosides, which release toxic hydrogen cyanide after hydrolysis by a specific β-glucosidase, the only β-glucosidase identified in the droplets (ZfBGD1) was inactive against cyanogenic glucosides. Accordingly, droplets did not release hydrogen cyanide, unless they were mixed with specific β-glucosidases present in the Zygaena haemolymph. Droplets secreted onto the cuticle hardened and formed sharp crystalline-like precipitates that may act as mandible abrasives to chewing predators. Hardening followed water evaporation and formation of antiparallel β-sheets of the peptide oligomers. Consequently, after mild irritation, Zygaena larvae deter predators by viscous and hardening droplets that contain defence proteins and β-cyanoalanine. After severe injury, droplets may mix with exuding haemolymph to release hydrogen cyanide.

  8. Chemical Speciation and Potential Mobility of Heavy Metals in the Soil of Former Tin Mining Catchment

    PubMed Central

    Ashraf, M. A.; Maah, M. J.; Yusoff, I.

    2012-01-01

    This study describes the chemical speciation of Pb, Zn, Cu, Cr, As, and Sn in soil of former tin mining catchment. Total five sites were selected for sampling and subsequent subsamples were collected from each site in order to create a composite sample for analysis. Samples were analysed by the sequential extraction procedure using optical emission spectrometry (ICP OES). Small amounts of Cu, Cr, and As retrieved from the exchangeable phase, the ready available for biogeochemical cycles in the ecosystem. Low quantities of Cu and As could be taken up by plants in these kind of acidic soils. Zn not detected in the bioavailable forms while Pb is only present in negligible amounts in very few samples. The absence of mobile forms of Pb eliminates the toxic risk both in the trophic chain and its migration downwards the soil profile. The results also indicate that most of the metals have high abundance in residual fraction indicating lithogenic origin and low bioavailability of the metals in the studied soil. The average potential mobility for the metals giving the following order: Sn > Cu > Zn > Pb > Cr > As. PMID:22566758

  9. Chemical speciation and potential mobility of heavy metals in the soil of former tin mining catchment.

    PubMed

    Ashraf, M A; Maah, M J; Yusoff, I

    2012-01-01

    This study describes the chemical speciation of Pb, Zn, Cu, Cr, As, and Sn in soil of former tin mining catchment. Total five sites were selected for sampling and subsequent subsamples were collected from each site in order to create a composite sample for analysis. Samples were analysed by the sequential extraction procedure using optical emission spectrometry (ICP OES). Small amounts of Cu, Cr, and As retrieved from the exchangeable phase, the ready available for biogeochemical cycles in the ecosystem. Low quantities of Cu and As could be taken up by plants in these kind of acidic soils. Zn not detected in the bioavailable forms while Pb is only present in negligible amounts in very few samples. The absence of mobile forms of Pb eliminates the toxic risk both in the trophic chain and its migration downwards the soil profile. The results also indicate that most of the metals have high abundance in residual fraction indicating lithogenic origin and low bioavailability of the metals in the studied soil. The average potential mobility for the metals giving the following order: Sn > Cu > Zn > Pb > Cr > As.

  10. Chemical reactivity trends of ergotamine and butenolide from electrostatic potentials and charge sensitivities

    SciTech Connect

    Mrozek, J.; Michalak, A.

    1995-12-05

    A set of reactivity indices, including maps of the electrostatic potential and local and condensed Fukui function (FF) indices in the atomic resolution, are reported for two vasoconstricting mycotoxins: butenolide and ergotamine; both the finite difference approach of Parr and Yan as well as charge sensitivity analysis, determining the charge responses via the inversion of the hardness tensor, have been used to generate the FF data. These two routes of arriving at the atomic FF indices provide an opportunity to evaluate the available parametrizations of the semiempirical NDDO-type of methods which have been used to determine the input charge distribution; namely, the best parametrization should generate consistent FF predictions resulting from both approaches. For butenolide, the MNDO parametrization was found to fulfill this consistency requirement. The chemical reactivity information has been used to trace possible similarities in reactivity trends of the butenolide molecule and the related fragment of ergotamine, toward hypothetical nucleophilic, electrophilic, and radical attacks. These predictions have been compared to experimental data available for other unsaturated lactones. 13 refs., 18 figs., 1 tab.

  11. Transport coefficients of heavy quarks around Tc at finite quark chemical potential

    NASA Astrophysics Data System (ADS)

    Berrehrah, H.; Gossiaux, P. B.; Aichelin, J.; Cassing, W.; Torres-Rincon, J. M.; Bratkovskaya, E.

    2014-11-01

    The interactions of heavy quarks with the partonic environment at finite temperature T and finite quark chemical potential μq are investigated in terms of transport coefficients within the dynamical quasiparticle model (DQPM) designed to reproduce the lattice-QCD (lQCD) results (including the partonic equation of state) in thermodynamic equilibrium. These results are confronted with those of nuclear many-body calculations close to the critical temperature Tc. The hadronic and partonic spatial diffusion coefficients join smoothly and show a pronounced minimum around Tc at μq=0 as well as at finite μq. Close to and above Tc its absolute value matches the lQCD calculations for μq=0 . The smooth transition of the heavy-quark transport coefficients from the hadronic to the partonic medium corresponds to a crossover in line with lattice calculations, and differs substantially from perturbative-QCD calculations which show a large discontinuity at Tc. This indicates that in the vicinity of Tc dynamically dressed massive partons should be the effective degrees of freedom in the quark-gluon plasma.

  12. Influence of High Hydrostatic Pressure Technology on Wine Chemical and Sensorial Characteristics: Potentialities and Drawbacks.

    PubMed

    Nunes, Cláudia; Santos, Mickael C; Saraiva, Jorge A; Rocha, Sílvia M; Coimbra, Manuel A

    During last years, scientific research on high hydrostatic pressure (HHP) as a nonthermal processing technology for preservation or aging of wine has increased substantially. HHP between 200 and 500MPa is able to inactivate bacteria and yeasts in red and white wines, suggesting that it may be used for wine preservation. However, these treatments have been shown to promote changes on sensorial and physicochemical characteristics in both red and white wines, not immediately in the first month, but along storage. The changes are observed in wine color, aroma, and taste due mainly to reactions of phenolic compounds, sugars, and proteins. These reactions have been associated with those observed during wine aging, leading to aged-like wine characteristics perceived by sensorial analysis. This chapter will present the influence of HHP technology on wine chemical and sensorial characteristics, criticaly discussing its potentialities and drawbacks. The appropriate use of HHP, based on the scientific knowledge of the reactions occuring in wine promoted by HHP, will allow to exploit this technology for wine production achieving distinct characteristics to address particular market and consumer demands. © 2017 Elsevier Inc. All rights reserved.

  13. Direct use of the chemical potential function in thermodynamic modeling of alloy phase diagrams

    NASA Astrophysics Data System (ADS)

    Kundrat, D. M.

    1986-08-01

    A modeling procedure for obtaining thermodynamic parameters from a limited knowledge of the phase diagram and a thermodynamic description of the participating phases is described. The procedure is to calculate compositions and parameters from specified compositions and parameters in a thermodynamic model employing the chemical potential function directly. Several calculations in the Fe-C and Fe-Cr-C systems are made for illustration. These results demonstrate for the two-phase equilibrium that only one phase boundary, or the partition ratio of each solute, and the thermodynamic parameter(s) for one of the phases need to be specified to calculate the other phase boundary and the thermodynamic parameter(s) for the other phase. The results for the Fe-C and Fe-Cr-C systems, for which the specified quantities were either the composition of the liquidus, or the partition ratios of the solute elements and temperature, and the parameter(s) for the liquid phase for the regular and quasi-regular solution models, are in good agreement with the results obtained by an error-minimization method.

  14. Lepidopteran defence droplets - a composite physical and chemical weapon against potential predators

    PubMed Central

    Pentzold, Stefan; Zagrobelny, Mika; Khakimov, Bekzod; Engelsen, Søren Balling; Clausen, Henrik; Petersen, Bent Larsen; Borch, Jonas; Møller, Birger Lindberg; Bak, Søren

    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 predators together and immobilised them. Droplets were characterised by a matrix of an aqueous solution of glycine-rich peptides (H-WG11-NH2) with significant amounts of proteins and glucose. Among the proteins, defensive proteins such as protease inhibitors, proteases and oxidases were abundant. The neurotoxin β-cyanoalanine was also found in the droplets. Despite the presence of cyanogenic glucosides, which release toxic hydrogen cyanide after hydrolysis by a specific β-glucosidase, the only β-glucosidase identified in the droplets (ZfBGD1) was inactive against cyanogenic glucosides. Accordingly, droplets did not release hydrogen cyanide, unless they were mixed with specific β-glucosidases present in the Zygaena haemolymph. Droplets secreted onto the cuticle hardened and formed sharp crystalline-like precipitates that may act as mandible abrasives to chewing predators. Hardening followed water evaporation and formation of antiparallel β-sheets of the peptide oligomers. Consequently, after mild irritation, Zygaena larvae deter predators by viscous and hardening droplets that contain defence proteins and β-cyanoalanine. After severe injury, droplets may mix with exuding haemolymph to release hydrogen cyanide. PMID:26940001

  15. Hydrazine bisalane is a potential compound for chemical hydrogen storage. A theoretical study.

    PubMed

    Nguyen, Vinh Son; Swinnen, Saartje; Leszczynski, Jerzy; Nguyen, Minh Tho

    2011-09-14

    Electronic structure calculations suggest that hydrazine bisalane (AlH(3)NH(2)NH(2)AlH(3), alhyzal) is a promising compound for chemical hydrogen storage (CHS). Calculations are carried out using the coupled-cluster theory CCSD(T) with the aug-cc-pVTZ basis set. Potential energy surfaces are constructed to probe the formation of, and hydrogen release from, hydrazine bisalane which is initially formed from the reaction of hydrazine with dialane. Molecular and electronic characteristics of both gauche and trans alhyzal are determined for the first time. The gauche hydrazine bisalane is formed from starting reactants hydrazine + dialane following a movement of an AlH(3) group from AlH(3)AlH(3)NH(2)NH(2) rather than by a direct attachment of a separate AlH(3) group, generated by predissociation of dialane, to AlH(3)NH(2)NH(2). The energy barriers for dehydrogenation processes from gauche and transalhyzal are in the range of 21-28 kcal mol(-1), which are substantially smaller than those of ca. 40 kcal mol(-1) previously determined for the isovalent hydrazine bisborane (bhyzb) system. H(2) release from hydrazine bisalane is thus more favored over that from hydrazine bisborane, making the Al derivative an alternative candidate for CHS.

  16. Potential of Stratum Corneum Lipid Liposomes for Screening of Chemical Skin Penetration Enhancers.

    PubMed

    Sakdiset, Pajaree; Todo, Hiroaki; Sugibayashi, Kenji

    2017-01-01

    The evaluation of effective skin chemical penetration enhancers (CPEs) is a crucial process in the development of transdermal and dermal formulations with the capacity to overcome the stratum corneum barrier. In the present study, we aimed to investigate the potential of stratum corneum lipid liposomes (SCLLs) as an alternative tool for the screening of various types and concentrations of CPEs. SCLLs were prepared using a thin-film hydration technique, and two types of fluorescent probes (sodium fluorescein [FL] or 1,6-diphenyl-1,3,5-hexatriene [DPH] were entrapped separately into SCLLs (FL-SCLL and DPH-SCLL, respectively). FL leakage from SCLLs as well as the fluidity of DPH-SCLLs were determined after incubating with various types of CPEs as a function of their concentrations. The obtained results showed a concentration-dependent relationship for most CPEs both for FL leakage and the fluidity of SCLLs. When observing these data in detail, however, the concentration profiles could be classified into five main categories depending on the mode of action of the CPEs. These results strongly suggest the usefulness of SCLLs for high-throughput screening of effective CPEs as well as the understanding of their possible mode of action, especially in the early stage of skin formulation development.

  17. Revisiting the boiling of primordial quark nuggets at nonzero chemical potential

    NASA Astrophysics Data System (ADS)

    Li, Ang; Liu, Tong; Gubler, Philipp; Xu, Ren-Xin

    2015-03-01

    The boiling of possible quark nuggets during the quark-hadron phase transition of the Universe at nonzero chemical potential is revisited within the microscopic Brueckner-Hartree-Fock approach employed for the hadron phase, using two kinds of baryon interactions as fundamental inputs. To describe the deconfined phase of quark matter, we use a recently developed quark mass density-dependent model with a fully self-consistent thermodynamic treatment of confinement. We study the baryon number limit Aboil (above which boiling may be important) with three typical values for the confinement parameter D. It is firstly found that the baryon interaction with a softer equation of state for the hadron phase would only lead to a small increase of Aboil . However, results depend sensitively on the confinement parameter in the quark model. Specifically, boiling might be important during the Universe cooling for a limited parameter range around D 1 / 2 = 170 MeV, a value satisfying recent lattice QCD calculations of the vacuum chiral condensate, while for other choices of this parameter, boiling might not happen and cosmological quark nuggets of 102 < A <1050 could survive.

  18. Chemical potential of a test hard sphere of variable size in a hard-sphere fluid

    NASA Astrophysics Data System (ADS)

    Heyes, David M.; Santos, Andrés

    2016-12-01

    The Labík and Smith Monte Carlo simulation technique to implement the Widom particle insertion method is applied using Molecular Dynamics (MD) instead to calculate numerically the insertion probability, P0(η ,σ0) , of tracer hard-sphere (HS) particles of different diameters, σ0, in a host HS fluid of diameter σ and packing fraction, η , up to 0.5. It is shown analytically that the only polynomial representation of -ln ⁡P0 (η ,σ0) consistent with the limits σ0→0 and σ0→∞ has necessarily a cubic form, c0(η ) +c1(η ) σ0 /σ +c2(η ) (σ0/σ ) 2 +c3(η ) (σ0/σ ) 3 . Our MD data for -ln ⁡P0 (η ,σ0) are fitted to such a cubic polynomial and the functions c0(η ) and c1(η ) are found to be statistically indistinguishable from their exact solution forms. Similarly, c2(η ) and c3(η ) agree very well with the Boublík-Mansoori-Carnahan-Starling-Leland and Boublík-Carnahan-Starling-Kolafa formulas. The cubic polynomial is extrapolated (high density) or interpolated (low density) to obtain the chemical potential of the host fluid, or σ0→σ , as β μex =c0+c1+c2+c3 . Excellent agreement between the Carnahan-Starling and Carnahan-Starling-Kolafa theories with our MD data is evident.

  19. The pDynamo Program for Molecular Simulations using Hybrid Quantum Chemical and Molecular Mechanical Potentials.

    PubMed

    Field, Martin J

    2008-07-01

    The pDynamo program has been developed for the simulation of molecular systems using hybrid quantum chemical (QC) and molecular mechanical (MM) potentials. pDynamo is written in a mixture of the computer languages Python and C and is a successor to the previous version of Dynamo, now denoted fDynamo, that was written in Fortran 90 (J. Comput. Chem. 2000, 21, 1088). The current version of Dynamo has a similar range of functionality to the older one but extends it in some significant ways, including the addition of a density functional theory QC capability. This paper gives a general description of pDynamo and outlines some of the advantages and disadvantages that have been encountered in switching computer languages. Some technical aspects of the implementation of pDynamo's algorithms are also discussed and illustrated with the results of example calculations. pDynamo is available on the Web at the address http://www.pdynamo.org and is released under the CeCILL license which is equivalent to the GNU general public license but conforms to the principles of French law.

  20. Chemical composition and allelopathic potential of essential oils obtained from Acacia cyanophylla Lindl. Cultivated in Tunisia.

    PubMed

    El Ayeb-Zakhama, Asma; Sakka-Rouis, Lamia; Bergaoui, Afifa; Flamini, Guido; Ben Jannet, Hichem; Harzallah-Skhiri, Fethia

    2015-04-01

    Acacia cyanophylla Lindl. (Fabaceae), synonym Acacia saligna (Labill.) H. L.Wendl., native to West Australia and naturalized in North Africa and South Europe, was introduced in Tunisia for rangeland rehabilitation, particularly in the semiarid zones. In addition, this evergreen tree represents a potential forage resource, particularly during periods of drought. A. cyanophylla is abundant in Tunisia and some other Mediterranean countries. The chemical composition of the essential oils obtained by hydrodistillation from different plant parts, viz., roots, stems, phyllodes, flowers, and pods (fully mature fruits without seeds), was characterized for the first time here. According to GC-FID and GC/MS analyses, the principal compound in the phyllode and flower oils was dodecanoic acid (4), representing 22.8 and 66.5% of the total oil, respectively. Phenylethyl salicylate (8; 34.9%), heptyl valerate (3; 17.3%), and nonadecane (36%) were the main compounds in the root, stem, and pod oils, respectively. The phyllode and flower oils were very similar, containing almost the same compounds. Nevertheless, the phyllode oil differed from the flower oil for its higher contents of hexahydrofarnesyl acetone (6), linalool (1), pentadecanal, α-terpineol, and benzyl benzoate (5) and its lower content of 4. Principal component and hierarchical cluster analyses separated the five essential oils into four groups, each characterized by its main constituents. Furthermore, the allelopathic activity of each oil was evaluated using lettuce (Lactuca sativa L.) as a plant model. The phyllode, flower, and pod oils exhibited a strong allelopathic activity against lettuce.

  1. A Molecular Dynamics Technique to Extract Forces in Soft Matter Systems Under Compression With Constant Solvent Chemical Potential.

    PubMed

    Elliott, Ian G; Kuhl, Tonya L; Faller, Roland

    2012-03-13

    Molecular dynamics simulations of opposing polymer brushes at varying surface separation distances were performed to develop a method for conducting a static compression of soft matter. As all separation distances were represented by independent simulations, the proper solvent density for every level of compression needed to be determined to acquire realistic data. This was accomplished by maintaining a constant solvent chemical potential for each separation distance. In doing so, each independent simulation is equilibrated with all others, reproducing conditions encountered experimentally in force spectroscopy measurements. Chemical potential was determined using the Widom test particle insertion method. Force information was extracted from pressure profiles, such that unphysical forces occurring within the surface layers were not accounted for in the calculation. Each individual simulation was a canonical ensemble molecular dynamics simulation, but taken together they approximate a grand canonical ensemble for the solvent particles by holding their chemical potential constant.

  2. The effect of finite temperature and chemical potential on nucleon properties in the logarithmic quark sigma model

    NASA Astrophysics Data System (ADS)

    Abu-Shady, M.; Abu-Nab, A.

    2015-12-01

    The logarithmic quark sigma model is applied to study the nucleon properties at finite temperature and chemical potential. The field equations have been solved numerically in the mean-field approximation by using the extended iteration method at finite temperature and baryon chemical potential. Baryon properties are investigated, such as the hedgehog mass, the magnetic moments of the proton and neutron, and the pion-nucleon coupling constant. We find that the hedgehog mass and the magnetic moments of the proton and neutron increase with increasing temperature and chemical potential, while the pion-nucleon coupling constant decreases. A comparison with the original sigma model and QCD sum rules is presented. We conclude that the logarithmic quark sigma model successfully describes baryon properties of a hot and dense medium.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27023588

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

    PubMed

    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.

  5. Dilepton production as a useful probe of quark gluon plasma with temperature dependent chemical potential quark mass

    NASA Astrophysics Data System (ADS)

    Kumar, Yogesh; Singh, S. Somorendro

    2016-07-01

    We extend the previous study of dilepton production using [S. Somorendro Singh and Y. Kumar, Can. J. Phys. 92 (2014) 31] based on a simple quasiparticle model of quark-gluon plasma (QGP). In this model, finite value of quark mass uses temperature dependent chemical potential the so-called Temperature Dependent Chemical Potential Quark Mass (TDCPQM). We calculate dilepton production in the relevant range of mass region. It is observed that the production rate is marginally enhanced from the earlier work. This is due to the effect of TDCPQM and its effect is highly significant in the production of dilepton.

  6. Individual complex Dirac eigenvalue distributions from random matrix theory and comparison to quenched lattice QCD with a quark chemical potential.

    PubMed

    Akemann, G; Bloch, J; Shifrin, L; Wettig, T

    2008-01-25

    We analyze how individual eigenvalues of the QCD Dirac operator at nonzero quark chemical potential are distributed in the complex plane. Exact and approximate analytical results for both quenched and unquenched distributions are derived from non-Hermitian random matrix theory. When comparing these to quenched lattice QCD spectra close to the origin, excellent agreement is found for zero and nonzero topology at several values of the quark chemical potential. Our analytical results are also applicable to other physical systems in the same symmetry class.

  7. Individual Complex Dirac Eigenvalue Distributions from Random Matrix Theory and Comparison to Quenched Lattice QCD with a Quark Chemical Potential

    SciTech Connect

    Akemann, G.; Shifrin, L.; Bloch, J.; Wettig, T.

    2008-01-25

    We analyze how individual eigenvalues of the QCD Dirac operator at nonzero quark chemical potential are distributed in the complex plane. Exact and approximate analytical results for both quenched and unquenched distributions are derived from non-Hermitian random matrix theory. When comparing these to quenched lattice QCD spectra close to the origin, excellent agreement is found for zero and nonzero topology at several values of the quark chemical potential. Our analytical results are also applicable to other physical systems in the same symmetry class.

  8. Deciphering potential chemical compounds of gaseous oxidized mercury in Florida, USA

    NASA Astrophysics Data System (ADS)

    Huang, Jiaoyan; Miller, Matthieu B.; Edgerton, Eric; Sexauer Gustin, Mae

    2017-02-01

    The highest mercury (Hg) wet deposition in the United States of America (USA) occurs along the Gulf of Mexico, and in the southern and central Mississippi River Valley. Gaseous oxidized Hg (GOM) is thought to be a major contributor due to high water solubility and reactivity. Therefore, it is critical to understand concentrations, potential for wet and dry deposition, and GOM compounds present in the air. Concentrations and dry-deposition fluxes of GOM were measured and calculated for Naval Air Station Pensacola Outlying Landing Field (OLF) in Florida using data collected by a Tekran® 2537/1130/1135, the University of Nevada Reno Reactive Mercury Active System (UNRRMAS) with cation exchange and nylon membranes, and the Aerohead samplers that use cation-exchange membranes to determine dry deposition. Relationships with Tekran®-derived data must be interpreted with caution, since the GOM concentrations measured are biased low depending on the chemical compounds in air and interferences with water vapor and ozone.Criteria air pollutants were concurrently measured. This allowed for comparison and better understanding of GOM.In addition to other methods previously applied at OLF, use of the UNRRMAS provided a platform for determination of the chemical compounds of GOM in the air. Results from nylon membranes with thermal desorption analyses indicated seven GOM compounds in this area, including HgBr2, HgCl2, HgO, Hg-nitrogen and sulfur compounds, and two unknown compounds. This indicates that the site is influenced by different gaseous phase reactions and sources. Using back-trajectory analysis during a high-GOM event related to high CO, but average SO2, indicated air parcels moved from the free troposphere and across Arkansas, Mississippi, and Alabama at low elevation (< 300 m). This event was initially characterized by HgBr2, followed by a mixture of GOM compounds. Overall, GOM chemistry indicates oxidation reactions with local mobile source pollutants and long

  9. 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.

    PubMed

    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.

  10. Surveillance of potentially hazardous chemicals in food in the United Kingdom.

    PubMed

    Knowles, M E; Bell, J R; Norman, J A; Watson, D H

    1991-01-01

    Surveillance of chemical contaminants in food plays an important role in helping to ensure a safe food supply in those countries that undertake it. This paper reviews the methods used in the UK as a means of highlighting the essential elements required by any food chemical surveillance programme. The following topics have been covered: quantifying food consumption, setting priorities in food surveillance, developing a common approach to the surveillance of different chemicals in the food supply (including the use of Total and Duplicate Diet Studies), estimating human intakes of chemicals from the diet, developing suitably sensitive and reliable methods of analysis, obtaining representative samples, and assessing and managing risk.

  11. Framework for identifying chemicals with structural features associated with the potential to act as developmental or reproductive toxicants.

    PubMed

    Wu, Shengde; Fisher, Joan; Naciff, Jorge; Laufersweiler, Michael; Lester, Cathy; Daston, George; Blackburn, Karen

    2013-12-16

    Developmental and reproductive toxicity (DART) end points are important hazard end points that need to be addressed in the risk assessment of chemicals to determine whether or not they are the critical effects in the overall risk assessment. These hazard end points are difficult to predict using current in silico tools because of the diversity of mechanisms of action that elicit DART effects and the potential for narrow windows of vulnerability. DART end points have been projected to consume the majority of animals used for compliance with REACH; thus, additional nonanimal predictive tools are urgently needed. This article presents an empirically based decision tree for determining whether or not a chemical has receptor-binding properties and structural features that are consistent with chemical structures known to have toxicity for DART end points. The decision tree is based on a detailed review of 716 chemicals (664 positive, 16 negative, and 36 with insufficient data) that have DART end-point data and are grouped into defined receptor binding and chemical domains. When tested against a group of chemicals not included in the training set, the decision tree is shown to identify a high percentage of chemicals with known DART effects. It is proposed that this decision tree could be used both as a component of a screening system to identify chemicals of potential concern and as a component of weight-of-evidence decisions based on structure-activity relationships (SAR) to fill data gaps without generating additional test data. In addition, the chemical groupings generated could be used as a starting point for the development of hypotheses for in vitro testing to elucidate mode of action and ultimately in the development of refined SAR principles for DART that incorporate mode of action (adverse outcome pathways).

  12. Direct CP, Lepton Flavor and Isospin Asymmetries in the Decays B->K(*)l+l-

    SciTech Connect

    Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Lopez, L.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Abrams, G.S.; Battaglia, M.; Brown, D.N.; Cahn, R.N.; Jacobsen, R.G.; /LBL, Berkeley /UC, Berkeley /Birmingham U. /Ruhr U., Bochum /Bristol U. /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UCLA /UC, Riverside /UC, San Diego /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /Frascati /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /Harvard U. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa U. /Iowa State U. /Johns Hopkins U. /Karlsruhe U., EKP /Orsay, LAL /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Louisville U. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT, LNS /McGill U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /Mississippi U. /Montreal U. /Mt. Holyoke Coll. /INFN, Naples /Naples U. /INFN, Naples /INFN, Naples /Naples U. /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /Padua U. /Paris U., VI-VII /Pennsylvania U. /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /Rostock U. /Rutherford /DSM, DAPNIA, Saclay /South Carolina U. /SLAC /Stanford U., Phys. Dept. /SUNY, Albany /Tennessee U. /Texas U. /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /Valencia U., IFIC /Victoria U. /Warwick U. /Wisconsin U., Madison

    2009-03-03

    We measure rate asymmetries for the rare decays B {yields} K{sup (*)}{ell}{sup +}{ell}{sup -}, where {ell}{sup +}{ell}{sup -} is either e{sup +}e{sup -} or {mu}{sup +}{mu}{sup -}, using a sample of 384 million B{bar B} events collected with the BABAR detector at the PEP-II e{sup +}e{sup -} collider. We find no evidence for direct CP or lepton-flavor asymmetries. For dilepton masses below the J/{psi} resonance, we find evidence for unexpectedly large isospin asymmetries in both B {yields} K{ell}{sup +}{ell}{sup -} and B {yields} K*{ell}{sup +}{ell}{sup -} which differ respectively by 3.2{sigma} and 2.7{sigma}, including systematic uncertainties, from the Standard Model expectations.

  13. Isospin Dependence of Incomplete Fusion Reactions at 25 MeV/Nucleon

    SciTech Connect

    Amorini, F.; Agodi, C.; Alba, R.; Anzalone, A.; Coniglione, R.; Di Pietro, A.; Figuera, P.; Maiolino, C.; Santonocito, D.; Sapienza, P.; Cardella, G.; Papa, M.; De Filippo, E.; Pagano, A.; Pirrone, S.; Verde, G.; Giuliani, G.; Berceanu, I.; Pop, A.; Cavallaro, S.

    2009-03-20

    {sup 40}Ca+{sup 40,48}Ca,{sup 46}Ti reactions at 25 MeV/nucleon have been studied using the 4{pi} CHIMERA detector. An isospin effect on the competition between fusionlike and binarylike reaction mechanisms has been observed. The probability of producing a heavy residue is lower in the case of N{approx_equal}Z colliding systems as compared to the case of reactions induced on the neutron rich {sup 48}Ca target. Predictions based on constrained molecular dynamics II calculations show that the competition between fusionlike and binary reactions in the selected centrality bins can constrain the parametrization of the symmetry energy and its density dependence in the nuclear equation of state.

  14. Direct CP, lepton flavor, and isospin asymmetries in the decays B-->K(*)l+l-.

    PubMed

    Aubert, B; Bona, M; Karyotakis, Y; Lees, J P; Poireau, V; Prencipe, E; Prudent, X; Tisserand, V; Garra Tico, J; Grauges, E; Lopez, L; Palano, A; Pappagallo, M; Eigen, G; Stugu, B; Sun, L; Abrams, G S; Battaglia, M; Brown, D N; Cahn, R N; Jacobsen, R G; Kerth, L T; Kolomensky, Yu G; Lynch, G; Osipenkov, I L; Ronan, M T; Tackmann, K; Tanabe, T; Hawkes, C M; Soni, N; Watson, A T; Koch, H; Schroeder, T; Walker, D; Asgeirsson, D J; Fulsom, B G; Hearty, C; Mattison, T S; McKenna, J A; Barrett, M; Khan, A; Blinov, V E; Bukin, A D; Buzykaev, A R; Druzhinin, V P; Golubev, V B; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Todyshev, K Yu; Bondioli, M; Curry, S; Eschrich, I; Kirkby, D; Lankford, A J; Lund, P; Mandelkern, M; Martin, E C; Stoker, D P; Abachi, S; Buchanan, C; Gary, J W; Liu, F; Long, O; Shen, B C; Vitug, G M; Yasin, Z; Zhang, L; Sharma, V; Campagnari, C; Hong, T M; Kovalskyi, D; Mazur, M A; Richman, J D; Beck, T W; Eisner, A M; Flacco, C J; Heusch, C A; Kroseberg, J; Lockman, W S; Schalk, T; Schumm, B A; Seiden, A; Wang, L; Wilson, M G; Winstrom, L O; Cheng, C H; Doll, D A; Echenard, B; Fang, F; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Andreassen, R; Mancinelli, G; Meadows, B T; Mishra, K; Sokoloff, M D; Bloom, P C; Ford, W T; Gaz, A; Hirschauer, J F; Nagel, M; Nauenberg, U; Smith, J G; Ulmer, K A; Wagner, S R; Ayad, R; Soffer, A; Toki, W H; Wilson, R J; Altenburg, D D; Feltresi, E; Hauke, A; Jasper, H; Karbach, M; Merkel, J; Petzold, A; Spaan, B; Wacker, K; Kobel, M J; Mader, W F; Nogowski, R; Schubert, K R; Schwierz, R; Sundermann, J E; Volk, A; Bernard, D; Bonneaud, G R; Latour, E; Thiebaux, Ch; Verderi, M; Clark, P J; Gradl, W; Playfer, S; Watson, J E; Andreotti, M; Bettoni, D; Bozzi, C; Calabrese, R; Cecchi, A; Cibinetto, G; Franchini, P; Luppi, E; Negrini, M; Petrella, A; Piemontese, L; Santoro, V; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Finocchiaro, G; Pacetti, S; Patteri, P; Peruzzi, I M; Piccolo, M; Rama, M; Zallo, A; Buzzo, A; Contri, R; Lo Vetere, M; Macri, M M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Chaisanguanthum, K S; Morii, M; Marks, J; Schenk, S; Uwer, U; Klose, V; Lacker, H M; Bard, D J; Dauncey, P D; Nash, J A; Panduro Vazquez, W; Tibbetts, M; Behera, P K; Chai, X; Charles, M J; Mallik, U; Cochran, J; Crawley, H B; Dong, L; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Gao, Y Y; Gritsan, A V; Guo, Z J; Lae, C K; Denig, A G; Fritsch, M; Schott, G; Arnaud, N; Béquilleux, J; D'Orazio, A; Davier, M; Firmino da Costa, J; Grosdidier, G; Höcker, A; Lepeltier, V; Le Diberder, F; Lutz, A M; Pruvot, S; Roudeau, P; Schune, M H; Serrano, J; Sordini, V; Stocchi, A; Wormser, G; Lange, D J; Wright, D M; Bingham, I; Burke, J P; Chavez, C A; Fry, J R; Gabathuler, E; Gamet, R; Hutchcroft, D E; Payne, D J; Touramanis, C; Bevan, A J; Clarke, C K; George, K A; Di Lodovico, F; Sacco, R; Sigamani, M; Cowan, G; Flaecher, H U; Hopkins, D A; Paramesvaran, S; Salvatore, F; Wren, A C; Brown, D N; Davis, C L; Alwyn, K E; Bailey, D; Barlow, R J; Chia, Y M; Edgar, C L; Jackson, G; Lafferty, G D; West, T J; Yi, J I; Anderson, J; Chen, C; Jawahery, A; Roberts, D A; Simi, G; Tuggle, J M; Dallapiccola, C; Li, X; Salvati, E; Saremi, S; Cowan, R; Dujmic, D; Fisher, P H; Koeneke, K; Sciolla, G; Spitznagel, M; Taylor, F; Yamamoto, R K; Zhao, M; Patel, P M; Robertson, S H; Lazzaro, A; Lombardo, V; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Sanders, D A; Summers, D J; Zhao, H W; Simard, M; Taras, P; Viaud, F B; Nicholson, H; De Nardo, G; Lista, L; Monorchio, D; Onorato, G; Sciacca, C; Raven, G; Snoek, H L; Jessop, C P; Knoepfel, K J; LoSecco, J M; Wang, W F; Benelli, G; Corwin, L A; Honscheid, K; Kagan, H; Kass, R; Morris, J P; Rahimi, A M; Regensburger, J J; Sekula, S J; Wong, Q K; Blount, N L; Brau, J; Frey, R; Igonkina, O; Kolb, J A; Lu, M; Rahmat, R; Sinev, N B; Strom, D; Strube, J; Torrence, E; Castelli, G; Gagliardi, N; Margoni, M; Morandin, M; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Voci, C; del Amo Sanchez, P; Ben-Haim, E; Briand, H; Calderini, G; Chauveau, J; David, P; Del Buono, L; Hamon, O; Leruste, Ph; Ocariz, J; Perez, A; Prendki, J; Sitt, S; Gladney, L; Biasini, M; Covarelli, R; Manoni, E; Angelini, C; Batignani, G; Bettarini, S; Carpinelli, M; Cervelli, A; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Morganti, M; Neri, N; Paoloni, E; Rizzo, G; Walsh, J J; Lopes Pegna, D; Lu, C; Olsen, J; Smith, A J S; Telnov, A V; Anulli, F; Baracchini, E; Cavoto, G; del Re, D; Di Marco, E; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Jackson, P D; Li Gioi, L; Mazzoni, M A; Morganti, S; Piredda, G; Polci, F; Renga, F; Voena, C; Ebert, M; Hartmann, T; Schröder, H; Waldi, R; Adye, T; Franek, B; Olaiya, E O; Wilson, F F; Emery, S; Escalier, M; Esteve, L; Ganzhur, S F; Hamel de Monchenault, G; Kozanecki, W; Vasseur, G; Yèche, Ch; Zito, M; Chen, X R; Liu, H; Park, W; Purohit, M V; White, R M; Wilson, J R; Allen, M T; Aston, D; Bartoldus, R; Bechtle, P; Benitez, J F; Cenci, R; Coleman, J P; Convery, M R; Dingfelder, J C; Dorfan, J; Dubois-Felsmann, G P; Dunwoodie, W; Field, R C; Gabareen, A M; Gowdy, S J; Graham, M T; Grenier, P; Hast, C; Innes, W R; Kaminski, J; Kelsey, M H; Kim, H; Kim, P; Kocian, M L; Leith, D W G S; Li, S; Lindquist, B; Luitz, S; Luth, V; Lynch, H L; Macfarlane, D B; Marsiske, H; Messner, R; Muller, D R; Neal, H; Nelson, S; O'Grady, C P; Ofte, I; Perazzo, A; Perl, M; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Snyder, A; Su, D; Sullivan, M K; Suzuki, K; Swain, S K; Thompson, J M; Va'vra, J; Wagner, A P; Weaver, M; West, C A; Wisniewski, W J; Wittgen, M; Wright, D H; Wulsin, H W; Yarritu, A K; Yi, K; Young, C C; Ziegler, V; Burchat, P R; Edwards, A J; Majewski, S A; Miyashita, T S; Petersen, B A; Wilden, L; Ahmed, S; Alam, M S; Ernst, J A; Pan, B; Saeed, M A; Zain, S B; Spanier, S M; Wogsland, B J; Eckmann, R; Ritchie, J L; Ruland, A M; Schilling, C J; Schwitters, R F; Drummond, B W; Izen, J M; Lou, X C; Bianchi, F; Gamba, D; Pelliccioni, M; Bomben, M; Bosisio, L; Cartaro, C; Della Ricca, G; Lanceri, L; Vitale, L; Azzolini, V; Lopez-March, N; Martinez-Vidal, F; Milanes, D A; Oyanguren, A; Albert, J; Banerjee, Sw; Bhuyan, B; Choi, H H F; Hamano, K; Kowalewski, R; Lewczuk, M J; Nugent, I M; Roney, J M; Sobie, R J; Gershon, T J; Harrison, P F; Ilic, J; Latham, T E; Mohanty, G B; Band, H R; Chen, X; Dasu, S; Flood, K T; Pan, Y; Pierini, M; Prepost, R; Vuosalo, C O; Wu, S L

    2009-03-06

    We measure branching fractions and integrated rate asymmetries for the rare decays B-->K(*)l+l-, where l+l- is either e+e- or micro+micro-, using a sample of 384x10(6) BB events collected with the BABAR detector at the PEP-II e+e- collider. We find no evidence for direct CP or lepton-flavor asymmetries. However, for dilepton masses below the J/psi resonance, we find evidence for unexpectedly large isospin asymmetries in both B-->Kl+l- and B-->K*l+l- which differ, respectively, by 3.2sigma and 2.7sigma, including systematic uncertainties, from the standard model expectations.

  15. Isospin-violating dark-matter-nucleon scattering via two-Higgs-doublet-model portals

    SciTech Connect

    Drozd, Aleksandra; Grzadkowski, Bohdan; Gunion, John F.; Jiang, Yun

    2016-10-24

    We show that in a multi-Higgs model in which one Higgs fits the LHC 125 GeV state, one or more of the other Higgs bosons can mediate DM-nucleon interactions with maximal DM isospin violation being possible for appropriate Higgs-quark couplings, independent of the nature of DM. We then consider the explicit example of a Type II two-Higgs-doublet model, identifying the h or H as the 125 GeV state while the H or h, respectively, mediates DM-nucleon interactions. Finally, we show that if a stable scalar, S, is added then it can be a viable light DM candidate with correct relic density while obeying all direct and indirect detection limits.

  16. Angular and Isospin Asymmetries in the Decays B->K(*)l l-

    SciTech Connect

    Flood, Kevin T.; /Wisconsin U., Madison

    2011-11-08

    We use a sample of 384 million B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric e{sup +}e{sup -} storage ring to study the flavor-changing neutral current decays B {yields} K{sup (*)}{ell}{sup +}{ell}{sup -}, where {ell}{sup +}{ell}{sup -} is either e{sup +}e{sup -} or {mu}{sup +}{mu}{sup -}. We present measurements in two dilepton mass bins, one below the J/{psi} resonance and the other above, of the lepton forward-backward asymmetry {Alpha}{sub FB} and the longitudinal K* polarization F{sub L} in B {yields} K* {ell}{sup +}{ell}{sup -}, along with isospin rate asymmetries in B {yields} K*{ell}{sup +}{ell}{sup -} and B {yields} K{ell}{sup +}{ell}{sup -} final states.

  17. GDR as a Probe of the Collective Motion in Nuclei at High Spins, Temperatures or Isospins

    SciTech Connect

    Maj, Adam

    2008-11-11

    The gamma-decay of the Giant Dipole Resonance (GDR), the high-frequency collective vibration of protons against neutrons, has been proven to be a basic probe for the shapes of hot nuclei, especially to study the effective shape evolution caused by the collective rotation of a nucleus. In this context an interesting question arises: what is the nuclear shape at extreme values of spin or temperatures, close to the limit impose by another collective motion--fission, and how evolves the giant dipole collective vibrations as a function of isospin. Short overview of the results from the experiments aimed to answer these questions are presented and possible perspectives of these type of studies for exotic nuclei to be obtained with the novel gamma-calorimeter PARIS and soon available intense radioactive beams are discussed.

  18. Unexpected neutron/proton ratio and isospin effect in low-energy antiproton-induced reactions

    NASA Astrophysics Data System (ADS)

    Feng, Zhao-Qing

    2017-09-01

    The inclusive spectra of pre-equilibrium nucleons produced in low-energy antiproton-nucleus collisions are thoroughly investigated within the the Lanzhou quantum molecular dynamics transport approach for the first time. The reaction channels of elastic scattering, annihilation, charge exchange, and inelastic processes in antibaryon-baryon, baryon-baryon, and meson-baryon collisions have been implemented in the model. The unexpected neutron to proton yield ratios are caused from the isospin effects of pion-nucleon collisions and the symmetry energy. It is found that the π--neutron collisions enhance the neutron emission in the antiproton annihilation in a nucleus. A soft symmetry energy with the stiffness of γs=0.5 at subsaturation densities is constrained from the available data of the neutron/proton spectra.

  19. Isospin Mixing of Quark Cluster Diybaryon Resonances in the Bag Model*

    NASA Astrophysics Data System (ADS)

    Ward, Thomas

    2000-10-01

    Calculations of isospin mixing of dibaryon resonaces composed of color magentic six quark states using the quark cluster bag model are shown to result in a low lying J=2 dibaryon at 1913 MeV. The 1913 MeV resonance can only transition into NN states and a low energy (29-35 MeV) isoscaler meson multiplet, the sigma mesons (J=0,1,2). The J=1 axial-vector meson may already have been discovered at the Rutherford ISIS Facility, detected as a neutrino time anomaly known as the KARMEN particle. The predicted J=0 meson has the long sought after properties of the sigma meson or Higgs particle required for the Chiral Symmetry Breaking partner of the pion and light mass hadron generation. The influence of this predicted isoscaler multiplet in QCD and QFD is interpreted using the effective low energy model of Chiral Perturbation Theory.

  20. Thermal and quantal isospin and spin fluctuations in heavy ion reactions

    SciTech Connect

    Moretto, L.G.

    1980-01-01

    The isobaric charge distributions are discussed in terms of quantal and classical isospin fluctuations. The roles of mass asymmetry and of the higher giant isovector modes are treated within the framework of a cylinder model that is worked out exactly. Spin fluctuations are considered first in terms of quantal fluctuations in a cylinder model and second in terms of thermal fluctuations in a two-sphere model. The results are applied to the calculation of in- and out-of-plane angular distributions for sequential fission, alpha and gamma decay. Analytical expressions are obtained for the angular distributions. The theoretical predictions are compared with experimental results for sequential fission, alpha, and gamma angular distributions. 23 figures.

  1. Experimental Guidance for Isospin Symmetry Breaking Calculations via Single Neutron Pickup Reactions

    NASA Astrophysics Data System (ADS)

    Leach, K. G.; Garrett, P. E.; Bangay, J. C.; Bianco, L.; Demand, G. A.; Finlay, P.; Green, K. L.; Phillips, A. A.; Rand, E. T.; Sumithrarachchi, C. S.; Svensson, C. E.; Triambak, S.; Wong, J.; Ball, G.; Faestermann, T.; Krücken, R.; Hertenberger, R.; Wirth, H.-F.; Towner, I. S.

    2013-03-01

    Recent activity in superallowed isospin-symmetry-breaking correction calculations has prompted interest in experimental confirmation of these calculation techniques. The shellmodel set of Towner and Hardy (2008) include the opening of specific core orbitals that were previously frozen. This has resulted in significant shifts in some of the δC values, and an improved agreement of the individual corrected {F}t values with the adopted world average of the 13 cases currently included in the high-precision evaluation of Vud. While the nucleus-to-nucleus variation of {F}t is consistent with the conserved-vector-current (CVC) hypothesis of the Standard Model, these new calculations must be thoroughly tested, and guidance must be given for their improvement. Presented here are details of a 64Zn(ěcd, t)63Zn experiment, undertaken to provide such guidance.

  2. Measurement of Branching Fractions and CP and Isospin Asymmetry in B->K*(892)gamma Decays

    SciTech Connect

    Aubert, B.

    2009-06-19

    We present an analysis of the decays B{sup 0} {yields} K*{sup 0}(892){gamma} and B{sup +} {yields} K*{sup +}(892){gamma} using a sample of about 383 million B{bar B} events collected with the BABAR detector at the PEP-II asymmetric energy B factory. We measure the branching fractions {Beta}(B{sup 0} {yields} K*{sup 0}{gamma}) = (4.47 {+-} 0.10 {+-} 0.16) x 10{sup -5} and {Beta}(B{sup +} {yields} K*{sup +}{gamma}) = (4.22 {+-} 0.14 {+-} 0.16) x 10{sup -5}. We constrain the direct CP asymmetry to be -0.033 < {Alpha}(B {yields} K*{gamma}) < 0.028 and the isospin asymmetry to be 0.017 < {Delta}{sub 0-} < 0.116, where the limits are determined by the 90% confidence interval and include both the statistical and systematic uncertainties.

  3. Isospin and a possible interpretation of the newly observed X(1576)

    SciTech Connect

    Guo Fengkun; Shen Pengnian

    2006-11-01

    Recently, the BES Collaboration observed a broad resonant structure X(1576) with a large width being around 800 MeV and assigned its J{sup PC} number to 1{sup --}. We show that the isospin of this resonant structure should be assigned to 1. This state might be a molecule state or a tetraquark state. We study the consequences of a possible K*(892)-{kappa} molecular interpretation. In this scenario, the broad width can easily be understood. Carefully searching this resonant structure in the J/{psi}{yields}{pi}{sup +}{pi}{sup -}{pi}{sup 0} and J/{psi}{yields}K{sup +}K{sup -}{pi}{sup +}{pi}{sup -}{pi}{sup 0} decays should be important for understanding the structure of X(1567)

  4. Isospin and a possible interpretation of the newly observed X(1576)

    NASA Astrophysics Data System (ADS)

    Guo, Feng-Kun; Shen, Peng-Nian

    2006-11-01

    Recently, the BES Collaboration observed a broad resonant structure X(1576) with a large width being around 800 MeV and assigned its JPC number to 1--. We show that the isospin of this resonant structure should be assigned to 1. This state might be a molecule state or a tetraquark state. We study the consequences of a possible K*(892)-κ¯ molecular interpretation. In this scenario, the broad width can easily be understood. Carefully searching this resonant structure in the J/ψ→π+π-π0 and J/ψ→K+K-π+π-π0 decays should be important for understanding the structure of X(1567).

  5. Isospin asymmetry of quark distributions and implications for single top-quark production at the LHC

    NASA Astrophysics Data System (ADS)

    Alekhin, S.; Blümlein, J.; Moch, S.; PlačakytÄ--, R.

    2016-12-01

    We present an improved determination of the up- and down-quark distributions in the proton using recent data on charged lepton asymmetries from W± gauge-boson production at the LHC and Tevatron. The analysis is performed in the framework of a global fit of parton distribution functions. The fit results are consistent with a nonzero isospin asymmetry of the sea, x (d ¯ -u ¯ ) , at small values of Bjorken x ˜10-4 indicating a delayed onset of the Regge asymptotics of a vanishing (d ¯ -u ¯ ) -asymmetry at small x . We compare with up- and down-quark distributions available in the literature and provide accurate predictions for the production of single top-quarks at the LHC, a process which can serve as a standard candle for the light quark flavor content of the proton.

  6. REDOX DISRUPTING POTENTIAL OF TOXCAST CHEMICALS RANKED BY ACTIVITY IN MOUSE EMBRYONIC STEM CELLS

    EPA Science Inventory

    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...

  7. COMPARISON OF CHEMICAL SCREENING AND RANKING APPROACHES: THE WASTE MINIMIZATION PRIORITIZATION TOOL VERSUS TOXIC EQUIVALENCY POTENTIALS

    EPA Science Inventory

    Chemical screening in the United States is often conducted using scoring and ranking methodologies. Linked models accounting for chemical fate, exposure, and toxicological effects are generally preferred in Europe and in product Life Cycle Assessment. For the first time, a compar...

  8. REDOX DISRUPTING POTENTIAL OF TOXCAST CHEMICALS RANKED BY ACTIVITY IN MOUSE EMBRYONIC STEM CELLS

    EPA Science Inventory

    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...

  9. Redox Disrupting Potential of ToxCast™Chemicals Ranked by Activity in Mouse Embryonic Stem Cells

    EPA Science Inventory

    Little is known regarding the adverse outcome pathways responsible for developmental toxicity following exposure to chemicals. An evaluation of Toxoast™ Phase I chemicals in an adherent mouse embryonic stem cell (mESC) assay revealed a redox sensitive pathway that correlated with...

  10. Redox Disrupting Potential of ToxCast™Chemicals Ranked by Activity in Mouse Embryonic Stem Cells

    EPA Science Inventory

    Little is known regarding the adverse outcome pathways responsible for developmental toxicity following exposure to chemicals. An evaluation of Toxoast™ Phase I chemicals in an adherent mouse embryonic stem cell (mESC) assay revealed a redox sensitive pathway that correlated with...

  11. Exploring the Potential for Using Inexpensive Natural Reagents Extracted from Plants to Teach Chemical Analysis

    ERIC Educational Resources Information Center

    Hartwell, Supaporn Kradtap

    2012-01-01

    A number of scientific articles report on the use of natural extracts from plants as chemical reagents, where the main objective is to present the scientific applications of those natural plant extracts. The author suggests that natural reagents extracted from plants can be used as alternative low cost tools in teaching chemical analysis,…

  12. Exploring the Potential for Using Inexpensive Natural Reagents Extracted from Plants to Teach Chemical Analysis

    ERIC Educational Resources Information Center

    Hartwell, Supaporn Kradtap

    2012-01-01

    A number of scientific articles report on the use of natural extracts from plants as chemical reagents, where the main objective is to present the scientific applications of those natural plant extracts. The author suggests that natural reagents extracted from plants can be used as alternative low cost tools in teaching chemical analysis,…

  13. Using in Vitro High Throughput Screening Assays to Identify Potential Endocrine-Disrupting Chemicals

    EPA Science Inventory

    Over the past 20 years, an increased focus on detecting environmental chemicals posing a risk of adverse effects due to endocrine disruption has driven the creation of the U.S. EPA Endocrine Disruptor Screening Program (EDSP). Thousands of chemicals are subject to the EDSP, whic...

  14. Using in Vitro High Throughput Screening Assays to Identify Potential Endocrine-Disrupting Chemicals

    EPA Science Inventory

    Over the past 20 years, an increased focus on detecting environmental chemicals posing a risk of adverse effects due to endocrine disruption has driven the creation of the U.S. EPA Endocrine Disruptor Screening Program (EDSP). Thousands of chemicals are subject to the EDSP, whic...

  15. Chemical potential of a test hard sphere of variable size in a hard-sphere fluid.

    PubMed

    Heyes, David M; Santos, Andrés

    2016-12-07

    The Labík and Smith Monte Carlo simulation technique to implement the Widom particle insertion method is applied using Molecular Dynamics (MD) instead to calculate numerically the insertion probability, P0(η,σ0), of tracer hard-sphere (HS) particles of different diameters, σ0, in a host HS fluid of diameter σ and packing fraction, η, up to 0.5. It is shown analytically that the only polynomial representation of -ln⁡P0(η,σ0) consistent with the limits σ0→0 and σ0→∞ has necessarily a cubic form, c0(η)+c1(η)σ0/σ+c2(η)(σ0/σ)(2)+c3(η)(σ0/σ)(3). Our MD data for -ln⁡P0(η,σ0) are fitted to such a cubic polynomial and the functions c0(η) and c1(η) are found to be statistically indistinguishable from their exact solution forms. Similarly, c2(η) and c3(η) agree very well with the Boublík-Mansoori-Carnahan-Starling-Leland and Boublík-Carnahan-Starling-Kolafa formulas. The cubic polynomial is extrapolated (high density) or interpolated (low density) to obtain the chemical potential of the host fluid, or σ0→σ, as βμ(ex)=c0+c1+c2+c3. Excellent agreement between the Carnahan-Starling and Carnahan-Starling-Kolafa theories with our MD data is evident.

  16. Potential of lattice Boltzmann to model droplets on chemically stripe-patterned substrates

    NASA Astrophysics Data System (ADS)

    Patrick Jansen, H.; Sotthewes, K.; Zandvliet, Harold J. W.; Kooij, E. Stefan

    2016-01-01

    Lattice Boltzmann modelling (LBM) has recently been applied to a range of different wetting situations. Here we demonstrate its potential in representing complex kinetic effects encountered in droplets on chemically stripe-patterned surfaces. An ultimate example of the power of LBM is provided by comparing simulations and experiments of impacting droplets with varying Weber numbers. Also, the shape evolution of droplets is discussed in relation to their final shape. The latter can then be compared to Surface Evolver (SE) results, since under the proper boundary conditions both approaches should yield the same configuration in a static state. During droplet growth in LBM simulations, achieved by increasing the density within the droplet, the contact line initially advances in the direction parallel to the stripes, therewith increasing its aspect ratio. Once the volume becomes too large the droplet starts wetting additional stripes, leading to a lower aspect ratio. The maximum aspect ratio is shown to be a function of the width ratio of the hydrophobic and hydrophilic stripes and also their absolute widths. In the limit of sufficiently large stripe widths the aspect ratio is solely dependent on the relative stripe widths. The maximum droplet aspect ratio in the LBM simulations is compared to SE simulations and results are shown to be in good agreement. Additionally, we also show the ability of LBM to investigate single stripe wetting, enabling determination of the maximum aspect ratio that can be achieved in the limit of negligible hydrophobic stripe width, under the constraint that the stripe widths are large enough such that they are not easily crossed.

  17. Inhibitory effects of opioids on compound action potentials in frog sciatic nerves and their chemical structures.

    PubMed

    Mizuta, Kotaro; Fujita, Tsugumi; Nakatsuka, Terumasa; Kumamoto, Eiichi

    2008-08-01

    An opioid tramadol more effectively inhibits compound action potentials (CAPs) than its metabolite mono-O-demethyl-tramadol (M1). To address further this issue, we examined the effects of opioids (morphine, codeine, ethylmorphine and dihydrocodeine) and cocaine on CAPs by applying the air-gap method to the frog sciatic nerve. All of the opioids at concentrations less than 10 mM reduced the peak amplitude of the CAP in a reversible and dose-dependent manner. The sequence of the CAP peak amplitude reductions was ethylmorphine>codeine>dihydrocodeine> or = morphine; the effective concentration for half-maximal inhibition (IC(50)) of ethylmorphine was 4.6 mM. All of the CAP inhibitions by opioids were resistant to a non-specific opioid-receptor antagonist naloxone. The CAP peak amplitude reductions produced by morphine, codeine and ethylmorphine were related to their chemical structures in such that this extent enhanced with an increase in the number of -CH(2) in a benzene ring, as seen in the inhibitory actions of tramadol and M1. Cocaine reduced CAP peak amplitudes with an IC(50) value of 0.80 mM. It is concluded that opioids reduce CAP peak amplitudes in a manner being independent of opioid-receptor activation and with an efficacy being much less than that of cocaine. It is suggested that the substituted groups of -OH bound to the benzene ring of morphine, codeine and ethylmorphine as well as of tramadol and M1, the structures of which are quite different from those of the opioids, may play an important role in producing nerve conduction block.

  18. Effective core potential modeling of Group IVA-Group IVB chemical vapor deposition

    SciTech Connect

    Cundari, T.R.; Li, Yueping

    1995-08-15

    An effective core potential study of a model chemical vapor deposition (CVD) reaction is reported. Compounds studied are those in which a Group IVA (E=C, Si, Ge, SN) main group element is directly bonded to a Group IVB (M=Ti, Zr, Hf) transition metal. Model reactants (H{sub 3}M-EH{sub 3}) possess Group IVA-Group IVB single bonds while products (H{sub 2}M = EH{sub 2}, formed by H{sub 2} elimination from reactants) have Group IVA-Group IVB multiple bonds. The main findings of this research are as follows: First, a single-determinant (RHF) description is appropriate for singly bonded Group IVA-Group IVB complexes. Agreement between experimental and calculated M-E single-bond lengths is very good at all levels studied. Second, electron correlation is of much greater importance for describing the ME {pi} bond than the ME {sigma} bond. Third, analysis of calculated double-to-single bond ratios (R{sub double}/R{sub single}) suggest that {pi}-bonding remains nearly constant over the entire series of compounds studied and is weaker than in the main group-main group analogs, suggesting a reason for the lack of reported examples with a Group IVA-Group IVB double bound. Fourth, barriers to elimination of H{sub 2} from H{sub 3}M-EH{sub 3} show two significant trends. We propose that the trends as a function of transition metal (Ti < Zr < Hf) and main group element (C > Si > Ge > Sn) are due to trends in M-H and E-H bond energies. 37 refs., 2 figs., 7 tabs.

  19. Non-Chemical Distant Cellular Interactions as a potential confounder of cell biology experiments

    PubMed Central

    Farhadi, Ashkan

    2014-01-01

    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. PMID:25368582

  20. Non-Chemical Distant Cellular Interactions as a potential confounder of cell biology experiments.

    PubMed

    Farhadi, Ashkan

    2014-01-01

    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.