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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. 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.

  3. 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}.

  4. Spontaneous parity and charge-conjugation violations at real isospin and imaginary baryon chemical potentials

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    The phase structure of two-flavor QCD is investigated at real isospin and imaginary quark chemical potentials by using the Polyakov-loop extended Nambu-Jona-Lasinio model. In the region, parity symmetry is spontaneously broken by the pion-superfluidity phase transition, whereas charge-conjugation symmetry is spontaneously violated by the Roberge-Weiss transition. The chiral (deconfinement) crossover at zero isospin and quark chemical potentials is a remnant of the parity (charge-conjugation) violation. The interplay between the parity and charge-conjugation violations are analyzed, and it is investigated how the interplay is related to the correlation between the chiral and deconfinement crossovers at zero isospin and quark chemical potentials.

  5. Phase diagram of dynamical twisted-mass Wilson fermions at finite isospin chemical potential

    NASA Astrophysics Data System (ADS)

    Janssen, Oliver; Kieburg, Mario; Splittorff, K.; Verbaarschot, Jacobus J. M.; Zafeiropoulos, Savvas

    2016-05-01

    We consider the phase diagram of twisted-mass Wilson fermions of two-flavor QCD in the parameter space of the quark mass, the isospin chemical potential, the twist angle and the lattice spacing. This work extends earlier studies in the continuum and those at zero chemical potential. We evaluate the phase diagram as well as the spectrum of the (pseudo-)Goldstone bosons using the chiral Lagrangian for twisted-mass Wilson fermions at nonzero isospin chemical potential. The phases are obtained from a mean field analysis. At zero twist angle we find that already an infinitesimal isospin chemical potential destroys the Aoki phase. The reason is that in this phase we have massless Goldstone bosons with a nonzero isospin charge. At finite twist angle, only two different phases are present—one phase which is continuously connected to the Bose condensed phase at nonzero chemical potential, and another phase which is continuously connected to the normal phase. For either zero or maximal twist, the phase diagram is more complicated, as the saddle-point equations allow for more solutions.

  6. Evaluating the phase diagram at finite isospin and baryon chemical potentials in the Nambu-Jona-Lasinio model

    SciTech Connect

    Mu Chengfu; He Lianyi; Liu Yuxin

    2010-09-01

    We study the phase diagram of two-flavor dense QCD at finite isospin and baryon chemical potentials in the framework of the Nambu-Jona-Lasinio model. We focus on the case with arbitrary isospin chemical potential {mu}{sub I} and small baryon chemical potential {mu}{sub B{<=}{mu}B}{sup {chi}}where {mu}{sub B}{sup {chi}}is the critical chemical potential for the first-order chiral phase transition to happen at {mu}{sub I}=0. The {mu}{sub I}-{mu}{sub B} phase diagram shows a rich phase structure since the system undergoes a crossover from a Bose-Einstein condensate of charged pions to a BCS superfluid with condensed quark-antiquark Cooper pairs when {mu}{sub I} increases at {mu}{sub B}=0, and a nonzero baryon chemical potential serves as a mismatch between the pairing species. We observe a gapless pion condensation phase near the quadruple point ({mu}{sub I},{mu}{sub B})=(m{sub {pi}},M{sub N}-1.5m{sub {pi}}) where m{sub {pi}}, M{sub N} are the vacuum masses of pions and nucleons, respectively. The first-order chiral phase transition becomes a smooth crossover when {mu}{sub I}>0.82m{sub {pi}}. At very large isospin chemical potential, {mu}{sub I}>6.36m{sub {pi}}, an inhomogeneous Larkin-Ovchinnikov-Fulde-Ferrell superfluid phase, appears in a window of {mu}{sub B}, which should in principle exist for arbitrary large {mu}{sub I}. Between the gapless and the Larkin-Ovchinnikov-Fulde-Ferrell phases, the pion superfluid phase and the normal quark matter phase are connected by a first-order phase transition. In the normal phase above the superfluid domain, we find that charged pions are still bound states even though {mu}{sub I} becomes very large, which is quite different from that at finite temperature. Our phase diagram is in good agreement with that found in imbalanced cold atom systems.

  7. Influence of in-medium NN cross sections, symmetry potential, and impact parameter on isospin observables

    NASA Astrophysics Data System (ADS)

    Zhang, Yingxun; Coupland, D. D. S.; Danielewicz, P.; Li, Zhuxia; Liu, Hang; Lu, Fei; Lynch, W. G.; Tsang, M. B.

    2012-02-01

    We explore the influence of the in-medium nucleon-nucleon cross section, symmetry potential, and impact parameter on isospin sensitive observables in intermediate-energy heavy-ion collisions with the ImQMD05 code, a modified version of the quantum molecular dynamics model. At incident velocities above the Fermi velocity, we find that the density dependence of the symmetry potential plays a more important role on the double neutron-to-proton ratio DR(n/p) and the isospin transport ratio Ri than the in-medium nucleon-nucleon cross sections, provided that the latter are constrained to a fixed total NN collision rate. We also explore both DR(n/p) and Ri as a function of the impact parameter. Since the copious production of intermediate mass fragments is a distinguishing feature of intermediate-energy heavy-ion collisions, we examine the isospin transport ratios constructed from different groups of fragments. We find that the values of the isospin transport ratios for projectile rapidity fragments with Z⩾20 are greater than those constructed from the entire projectile rapidity source. We believe experimental investigations of this phenomenon can be performed. These may provide significant tests of fragmentation time scales predicted by ImQMD calculations.

  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 dependence of {sup 6}He+p optical potential and the symmetry energy

    SciTech Connect

    Khoa, Dao T.; Hoang Sy Than

    2005-04-01

    A consistent folding analysis of the elastic p({sup 6}He,{sup 6}He)p scattering and charge exchange p({sup 6}He,{sup 6}Li{sup *})n reaction data measured at E{sub lab}=41.6A MeV has been performed within the coupled channels formalism. We have used the isovector coupling to link the isospin dependence of {sup 6}He+p optical potential to the cross section of p({sup 6}He,{sup 6}Li{sup *})n reaction exciting the 0{sup +} isobaric analog state (IAS) at 3.563 MeV in {sup 6}Li. Based on these results and the Hartree-Fock calculation of asymmetric nuclear matter using the same isospin-dependent effective nucleon-nucleon interaction, we were able to confirm that the most realistic value of the symmetry energy E{sub sym} is around 31 MeV. Our analysis has also shown that the measured charge exchange p({sup 6}He,{sup 6}Li{sup *})n data are quite sensitive to the halo tail of the {sup 6}He density used in the folding calculation and the IAS of {sup 6}Li is likely to have a halo structure similar to that established for the ground state of {sup 6}He.

  10. 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.

  11. 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.

  12. Phase transition of strongly interacting matter with a chemical potential dependent Polyakov loop potential

    NASA Astrophysics Data System (ADS)

    Shao, Guo-yun; Tang, Zhan-duo; Di Toro, Massimo; Colonna, Maria; Gao, Xue-yan; Gao, Ning

    2016-07-01

    We construct a hadron-quark two-phase model based on the Walecka-quantum hadrodynamics and the improved Polyakov-Nambu-Jona-Lasinio (PNJL) model with an explicit chemical potential dependence of Polyakov loop potential (μ PNJL model). With respect to the original PNJL model, the confined-deconfined phase transition is largely affected at low temperature and large chemical potential. Using the two-phase model, we investigate the equilibrium transition between hadronic and quark matter at finite chemical potentials and temperatures. The numerical results show that the transition boundaries from nuclear to quark matter move towards smaller chemical potential (lower density) when the μ -dependent Polyakov loop potential is taken. In particular, for charge asymmetric matter, we compute the local asymmetry of u , d quarks in the hadron-quark coexisting phase, and analyze the isospin-relevant observables possibly measurable in heavy-ion collision (HIC) experiments. In general new HIC data on the location and properties of the mixed phase would bring relevant information on the expected chemical potential dependence of the Polyakov loop contribution.

  13. 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.

  14. Non-Abelian twisted kinks in chiral Gross-Neveu model with isospin

    NASA Astrophysics Data System (ADS)

    Thies, Michael

    2016-04-01

    The two-dimensional, massless Gross-Neveu model with Nc colors and SU(2) isospin is studied analytically in the large Nc limit. The chiral SU (2 )L×SU (2 )R symmetry is broken spontaneously in the vacuum. Twisted kinks connecting two arbitrary points on the vacuum manifold S3 are constructed, and their properties are explored. The phase diagram as a function of temperature and baryon and isospin chemical potential is discussed, with special emphasis on inhomogeneous phases. The preferred form of the condensate is a product of the real kink crystal and the chiral spiral. Kink-kink scattering is solved, using the general solution of the multicomponent Bogoliubov-de Gennes equation recently presented by Takahashi.

  15. 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.

  16. Precision Measurement of Isospin Diffusion

    NASA Astrophysics Data System (ADS)

    Winkelbauer, Jack; Hodges, R.; Tsang, M. B.; Lynch, W. G.; Chajecki, Z.; Coupland, D.; Youngs, M.; Lu, F.; Sanetullaev, A.; Shane, R.; Tangwancharoen, S.; Famiano, M.; George, S.; Ghosh, T.; Dunn, J.; Dye, S.; Nielsen, S.; Ramos, A.; Charity, R.; Sobotka, L.; Elson, J.; Rana, T.; El Houssieny, M.

    2011-10-01

    In heavy-ion collisions, the tendency for isospin to drift from a neutron (proton) rich region to a neutron (proton) deficient region is sensitive to the density dependence of the symmetry energy. Until recently, most of the isospin diffusion results have been obtained with mid central to central collisions and different isospin observables have been used in experiment and in model simulations. To provide more accurate understanding of the dependence of isospin diffusion on impact parameters and different isospin observables, we have measured isotopic fragment and residue yields for 112 , 118 , 124Sn + 112 , 118 , 124Sn collisions at E/A = 70 MeV. The measurements were carried out at the Coupled Cyclotron Facility at Michigan State University. Fragment yields were measured using the Large Area Silicon Strip Array (LASSA) and heavy residue yields emitted at the forward angles were measured using the S800 Spectrograph. Impact parameter was selected using the MSU Miniball-WU Miniwall phoswich array. Preliminary results will be presented. Work supported by the National Science Foundation under Grant PHY-0606007.

  17. 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)

  18. 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.

  19. 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.

  20. 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.

  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. Chemical potential beyond the quasiparticle mean field

    SciTech Connect

    Dinh Dang, N.; Hung, N. Quang

    2010-03-15

    The effects of quantal and thermal fluctuations beyond the BCS quasiparticle mean field on the chemical potential are studied within a model, which consists of N particles distributed amongst {Omega} doubly folded equidistant levels interacting via a pairing force with parameter G. The results obtained at zero and finite temperatures T within several approaches, which include the fluctuations beyond the BCS theory, are compared with the exact results. The chemical potential, defined as the Lagrangian multiplier to preserve the average number of particles, is compared with the corresponding quantity, which includes the effect from fluctuations of particle and quasiparticle numbers beyond the BCS quasiparticle mean field. The analysis of the results shows that the latter differs significantly from the former as functions of G and T. The chemical potential loses its physical meaning in the system with a fixed number of particles or after eliminating quantal fluctuations of particle (quasiparticle) numbers by means of particle number projection. The validity of the criterion for the signature of the transition to Bose-Einstein condensation, which occurs in infinite systems when the chemical potential hits the bottom of the energy spectrum, is reexamined for the finite multilevel model.

  3. Normal or abnormal isospin-fractionation as a qualitative probe of nuclear symmetry energy at supradensities

    NASA Astrophysics Data System (ADS)

    Guo, Wenmei; Yong, Gaochan; Wang, Yongjia; Li, Qingfeng; Zhang, Hongfei; Zuo, Wei

    2014-11-01

    Within two different frameworks of isospin-dependent transport model, effect of nuclear symmetry energy at supradensities on the isospin-fractionation (IsoF) was investigated. With positive/negative symmetry potential at supradensities (i.e., values of symmetry energy increase/decrease with density above saturation density), for energetic nucleons, the value of neutron to proton ratio of free nucleons is larger/smaller than that of bound nucleon fragments. Compared with extensively studied quantitative observables of nuclear symmetry energy, the normal or abnormal isospin-fractionation of energetic nucleons can be a qualitative probe of nuclear symmetry energy at supradensities.

  4. Classically spinning and isospinning solitons

    SciTech Connect

    Battye, Richard A.; Haberichter, Mareike

    2012-09-26

    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.

  5. Ultrasoft fermionic excitation at finite chemical potential

    NASA Astrophysics Data System (ADS)

    Blaizot, Jean-Paul; Satow, Daisuke

    2014-05-01

    It has been suggested previously that an ultrasoft fermionic excitation develops, albeit with a small spectral weight, in a system of massless fermions and scalar bosons with Yukawa interaction at high temperature T. In this paper we study how this excitation is modified at finite chemical potential μ. We relate the existence of the ultrasoft mode to symmetries, in particular charge conjugation, and a supersymmetry of the free system which is spontaneously broken by finite temperature and finite density effects, as argued earlier by Lebedev and Smilga. A nonvanishing chemical potential breaks both symmetries explicitly and maximally at zero temperature where the mode ceases to exist. A detailed calculation indicates that the ultrasoft excitation persists as long as T≥0.71μ.

  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. 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.

  8. 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.

  9. Weakly bound states with spin-isospin symmetry

    NASA Astrophysics Data System (ADS)

    Kievsky, A.; Gattobigio, M.

    2016-03-01

    We discuss weakly bound states of a few-fermion system having spin-isospin symmetry. This corresponds to the nuclear physics case in which the singlet, a0, and triplet, a1, n - p scattering lengths are large with respect to the range of the nuclear interaction. The ratio of the two is about a0/a1 ≈ -4.31. This value defines a plane in which a0 and a1 can be varied up to the unitary limit, 1/a0 = 0 and 1/a1 = 0, maintaining its ratio fixed. Using a spin dependant potential model we estimate the three-nucleon binding energy along that plane. This analysis can be considered an extension of the Efimov plot for three bosons to the case of three 1/2-spin-isospin fermions.

  10. 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).

  11. Isospin symmetry in mirror α decays

    NASA Astrophysics Data System (ADS)

    Timofeyuk, N. K.; Descouvemont, P.; Johnson, R. C.

    2007-03-01

    We show that a consequence of isospin symmetry, recently discovered in mirror conjugated one-nucleon decays, can be extended to mirror-conjugated α-particle decays, both virtual and real. For virtual α decays of bound mirror pairs this symmetry manifests itself as a relation between the asymptotic normalization coefficients (ANCs) of α-particle overlap integrals. This relation is given by a simple analytical formula that involves α-particle separation energies and charges of residual nuclei. For bound-unbound mirror pairs, the ANC of a bound nucleus is related to the α width of the mirror unbound level. For unbound mirror pairs we get a new analytical formula that relates the widths of mirror resonances. We test the validity of these analytical formulas against the predictions of a two-body potential and of a many-body microscopic cluster model for several mirror states in Li7-Be7, B11-C11, and F19-Ne19 isotopes. We show that these analytical formulas are valid in many cases but that some deviations can be expected for isotopes with strongly deformed and easily excited cores. In general, the results from microscopic model are not very sensitive to model assumptions and can be used to predict unknown astrophysically relevant cross sections using known information about mirror systems.

  12. 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.

  13. Isospin dependence of cluster recognition and multifragment production

    NASA Astrophysics Data System (ADS)

    Rajni, Vermani, Yogesh K.

    2016-05-01

    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.

  14. Quark and gluon condensates in isospin matter

    SciTech Connect

    He Lianyi; Jiang Yin; Zhuang Pengfei

    2009-04-15

    By applying the Hellmann-Feynman theorem to a charged pion gas, the quark and gluon condensates at low isospin density are determined by precise pion properties. At intermediate density around f{sub {pi}}{sup 2}m{sub {pi}}, from both the estimation for the dilute pion gas and the calculation with the Nambu-Jona-Lasinio model, the quark condensate is strongly and monotonously suppressed, while the gluon condensate is enhanced and can be larger than its vacuum value. This unusual behavior of the gluon condensate is universal for Bose condensed matter of mesons. Our results can be tested by lattice calculations at finite isospin density.

  15. 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}.

  16. Isospin-breaking two-nucleon force with explicit {delta} excitations

    SciTech Connect

    Epelbaum, E.; Meissner, Ulf-G.; Krebs, H.

    2008-03-15

    We study the leading isospin-breaking contributions to the two-nucleon two-pion exchange potential due to explicit {delta} degrees of freedom in chiral effective field theory. In particular, we find important contributions due to the delta mass splittings to the charge symmetry breaking potential that act opposite to the effects induced by the nucleon mass splitting.

  17. Isospin violation and tensor-glueball decay

    SciTech Connect

    Lahiri, A.; Bagchi, B.

    1983-02-01

    We consider the possibility of an isospin-violating decay theta(1640)..-->..E(1440)..pi../sup 0/. We estimate its branching ratio and find GAMMA(theta..-->..E..pi../sup 0/)roughly-equal0.1 keV corresponding to B(theta..-->..etaeta) = 0.5

  18. 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.

  19. Impact of Fock terms on the isospin properties of nuclear matter

    NASA Astrophysics Data System (ADS)

    Sun, Bao Yuan; Zhao, Qian; Long, Wen Hui

    2016-05-01

    Several topics on the isospin properties of nuclear matter studied within the density-dependent relativistic Hartree-Fock theory are summarized. In detail, the effects of the Fock terms on the nuclear symmetry energy are listed, including the extra enhancement from the Fock terms of the isoscalar meson-nucleon coupling channels, the extra hyperon-induced suppression effect originating from the Fock channel, self-consistent tensor effects embedded automatically in the Fock diagrams, the enhanced density-dependent isospin-triplet potential part of the symmetry energy at high densities, a reduced kinetic symmetry energy at supranuclear density and so on. The results demonstrate the importance of the Fork diagram, especially from the isoscalar mesonnucleon coupling channels, on the isospin properties of the in-medium nuclear force.

  20. The Isospin Diffusion in 58Ni-INDUCED Reactions at Intermediate Energies

    NASA Astrophysics Data System (ADS)

    Galichet, E.; Rivet, M. F.; Borderie, B.; Colonna, M.; Bougault, R.; Durand, D.; Le Neindre, N.; Lopez, O.; Manduci, L.; Vient, E.; Chbihi, A.; Frankland, J. D.; Wieleczko, J. P.; Dayras, R.; Volant, C.; Guinet, D. C. R.; Lautesse, P.; Parlog, M.; Rosato, E.; Vigilante, M.

    Isospin diffusion is probed as a function of the dissipated energy by studying two systems 58Ni+58Ni and 58Ni+197Au, over the incident energy range 52-74A MeV. Experimental data are compared with the results of a microscopic transport model with two different parameterizations of the symmetry energy term. A better overall agreement between data and simulations is obtained when using a symmetry term with a potential part linearly increasing with nuclear density. The isospin equilibration time at 52 A MeV is estimated to 130 ± 10 fm/c.

  1. Dermal absorption potential of industrial chemicals: Criteria for skin notation

    SciTech Connect

    Fiserova-Bergerova, V.; Pierce, J.T.; Droz, P.O. )

    1990-01-01

    A dermal penetration rate (flux), predicted from physical properties of 132 chemicals, is suggested as an index of the dermal absorption potential of industrial chemicals. The prediction is designed for organic nonelectrolytes. Two reference values are recommended as criteria for skin notation: (1) dermal absorption potential, which relates to dermal absorption raising the dose of nonvolatile chemicals or biological levels of volatile chemicals 30% above those observed during inhalation exposure to TLV-TWA only--dermal absorption of chemicals belonging to this category should be considered when data obtained by biological monitoring are interpreted; and (2) dermal toxicity potential, which relates to dermal absorption that triples biological levels as compared with levels observed during inhalation exposure to TLV-TWA only. Chemicals belonging in this category should carry a skin notation. The toxicity criteria may not be valid for chemicals whose TLVs are based on preventing irritation and discomfort.

  2. POTENTIAL USE OF ULTRASOUND IN CHEMICAL MONITORING

    EPA Science Inventory

    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. he research specifically addressed using ultrasound (ultrasonic) processors to ...

  3. RS1, custodial isospin and precision tests

    NASA Astrophysics Data System (ADS)

    Agashe, Kaustubh; Delgado, Antonio; May, Michael J.; Sundrum, Raman

    2003-08-01

    We study precision electroweak constraints within a RS1 model with gauge fields and fermions in the bulk. The electroweak gauge symmetry is enhanced to SU(2)L × SU(2)R × U(1)B-L, thereby providing a custodial isospin symmetry sufficient to suppress excessive contributions to the T parameter. We then construct complete models, complying with all electroweak constraints, for solving the hierarchy problem, without supersymmetry or large hierarchies in the fundamental couplings. Using the AdS/CFT correspondence our models can be interpreted as dual to a strongly coupled conformal Higgs sector with global custodial isospin symmetry, gauge and fermionic matter being fundamental fields external to the CFT. This scenario has interesting collider signals, distinct from other RS models in the literature.

  4. Isospin violation in pion-kaon scattering

    NASA Astrophysics Data System (ADS)

    Kubis, Bastian; Meißner, Ulf-G.

    2002-03-01

    We consider strong and electromagnetic isospin violation in near-threshold pion-kaon scattering. At tree level, such effects are small for all physical channels. We work out the complete one-loop corrections to the process π-K +→ π0K 0. They come out rather small. We also show that the corresponding radiative cross section is highly suppressed at threshold.

  5. 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.

  6. Interference and isospin of disoriented chiral condensates

    SciTech Connect

    Suzuki, M.

    1995-09-01

    If coherent states describe the disoriented chiral condensates (DCC`s), many states of different chiral orientations should equally contribute to a given hadronic process. However, in the classical field description, we ignore the interference between the different DCC amplitudes. It results in a disregard of isospin invariance. We examine quantitatively how good this approximation is for the DCC`s of a typical size.

  7. 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.

  8. 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.

  9. 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.

  10. Two-color QCD at imaginary chemical potential and its impact on real chemical potential

    NASA Astrophysics Data System (ADS)

    Kashiwa, Kouji; Sasaki, Takahiro; Kouno, Hiroaki; Yahiro, Masanobu

    2013-01-01

    We study properties of two-color QCD at imaginary chemical potential (μ) from the viewpoint of the Roberge-Weiss periodicity, the charge conjugation, and the pseudoreality. At μ=±iπT/2, where T is temperature, the system is symmetric under the combination of the charge conjugation C and the Z2 transformation. The symmetry, called CZ2 symmetry, is preserved at lower T but spontaneously broken at higher T. The Polyakov-loop extended Nambu-Jona-Lasinio model has the same properties as two-color QCD for CZ2 symmetry and the pseudoreality. The nontrivial correlation between the chiral restoration and the deconfinement are investigated by introducing the entanglement vertex in the Polyakov-loop extended Nambu-Jona-Lasinio model. The order of CZ2 symmetry breaking at the Roberge-Weiss end point is second order when the correlation is weak, but becomes first order when the correlation is strong. We also investigate the impact of the correlation on the phase diagram at real μ.

  11. Effects of mode-mode and isospin-isospin correlations on domain formation of disoriented chiral condensates

    SciTech Connect

    Ikezi, N.; Asakawa, M.; Tsue, Y.

    2006-04-15

    The effects of mode-mode and isospin-isospin correlations on nonequilibrium chiral dynamics are investigated by using the method of the time-dependent variational approach with squeezed states as trial states. Our numerical simulations show that large domains of the disoriented chiral condensate (DCC) are formed because of the combined effect of the mode-mode and isospin-isospin correlations. Moreover, it is found that, when the mode-mode correlation is included, the DCC domain formation is accompanied by the amplification of the quantum fluctuation, which implies the squeezing of the state. However, neither the DCC domain formation nor the amplification of the quantum fluctuation is observed if only the isospin-isospin correlation is included. This suggests that the mode-mode coupling plays a key role in the DCC domain formation.

  12. 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. ...

  13. Two-color QCD with chiral chemical potential

    NASA Astrophysics Data System (ADS)

    Braguta, V. V.; Goy, V. A.; Ilgenfritz, E.-M.; Kotov, A. Yu.; Molochkov, A. V.; Müller-Preussker, M.; Petersson, B.; Schreiber, A.

    2016-01-01

    The phase diagram of two-color QCD with a chiral chemical potential is studied on the lattice. The focus is on the confinement/deconfinement phase transition and the breaking/restoration of chiral symmetry. The simulations are carried out with dynamical staggered fermions without rooting. The dependence of the Polyakov loop, the chiral condensate and the corresponding susceptibilities on the chiral chemical potential and the temperature are presented.

  14. 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. PMID:27237470

  15. 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.

  16. Fermi matrix element with isospin breaking

    NASA Astrophysics Data System (ADS)

    Guichon, P. A. M.; Thomas, A. W.; Saito, K.

    2011-02-01

    Prompted by the level of accuracy now being achieved in tests of the unitarity of the CKM matrix, we consider the possible modification of the Fermi matrix element for the β-decay of a neutron, including possible in-medium and isospin violating corrections. While the nuclear modifications lead to very small corrections once the Behrends-Sirlin-Ademollo-Gatto theorem is respected, the effect of the u-d mass difference on the conclusion concerning Vud is no longer insignificant. Indeed, we suggest that the correction to the value of |+|+| is at the level of 10.

  17. Determination of QCD phase diagram from the imaginary chemical potential

    NASA Astrophysics Data System (ADS)

    Yuji, Sakai; Kouji, Kashiwa; Hiroaki, Kouno; Masanobu, Yahiro

    2009-10-01

    Lattice QCD has the well-known sign problem at real chemical potential. An approach to circumvent the problem is the analytic continuation to real chemical potential from imaginary one. We propose a new analytic continuation by using the Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model. This work is published in our papers of Phys. Rev. D77, 051901 (2008), Phys. Rev. D78, 036001 (2008), Phys. Rev. D78 076007 (2008), Phys. Rev. D 79, 076008 (2009), Phys. Rev. D 79, 096001 (2009). This talk presents the latest result of these studies. The partition function of QCD has the Roberge-Weiss (RW) periodicity in the imaginary chemical potential region. We revealed that the PNJL model has the RW periodicity. Strength parameters of the vector-type four-quark and scalar-type eight- quark interactions are determined so as to reproduce lattice data on pseudocritical temperatures of the deconfinement and chiral phase transitions in the imaginary chemical potential region. The QCD phase diagram in the real chemical potential region is predicted by the PNJL model. The critical endpoint survives, even if the vector-type four-quark interaction is taken into account.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  20. Chemical potential effects on neutrino diffusion in supernovae

    NASA Technical Reports Server (NTRS)

    Mazurek, T. J.

    1975-01-01

    The validity of imposing a zero chemical potential for neutrinos in hydrodynamic calculations of collapsing supernovae is investigated in the diffusion approximation of neutrino transport. A coupled system of equations is solved for neutrino and energy diffusion fluxes as well as lepton diffusion in a collapsing supernovae ambient medium, and the results indicate a substantial growth in the neutrino chemical potential for densities greater than 10 to the 12th power gm/cu cm. The rate of energy transport is shown to be significantly affected by increases in Fermi integrals and chemical-potential gradients accompanied by decreases in temperature, and the extent of neutrino particle/antiparticle reactions is found also to affect energy diffusion rates. It is concluded that the photon-like behavior usually assumed for neutrinos may be incorrect and that an extension of the Sn transport approximation to include lepton characteristics is necessary for a definitive answer to the question of neutrino transport in supernovae.

  1. 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.

  2. 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.

  3. Phase of the Fermion Determinant at Nonzero Chemical Potential

    SciTech Connect

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

    2007-01-19

    We show that in the microscopic domain of QCD (also known as the {epsilon} domain) at nonzero chemical potential the average phase factor of the fermion determinant is nonzero for {mu}chemical 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.

  4. 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.

  5. 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.

  6. Simulation of the 3-state Potts model with chemical potential

    SciTech Connect

    Mercado, Ydalia Delgado; Gattringer, Christof; Evertz, Hans Gerd

    2011-05-23

    The 3-state Potts model with chemical potential is mapped to a flux representation where the complex action problem is resolved. We perform a Monte Carlo simulation based on a worm algorithm to study the phase diagram of the model. Our results shed light on the role which center symmetry and its breaking play for the QCD phase diagram.

  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. 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. PMID:19515399

  9. 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

  10. 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.

  11. Isospin effects in N ≈ Z nuclei in extended density functional theory

    NASA Astrophysics Data System (ADS)

    Satuła, Wojciech; Nazarewicz, Witold

    2016-02-01

    This paper overviews various phenomena related to the concept of isospin symmetry. The focus is on N ≈ Z nuclei, which are excellent laboratories of isospin physics. The theoretical framework applied is nuclear density functional theory and its isospin- and angular-momentum projected extensions, as well as symmetry-projected multi-reference models. The topics covered include: isospin impurities, superallowed beta decays, beta-transitions in mirror nuclei, isospin breaking hadronic interactions, mirror and triplet binding energy differences, and isoscalar pairing.

  12. Chemical and preclinical studies on Hedyotis diffusa with anticancer potential.

    PubMed

    Niu, Yu; Meng, Qiu-Xia

    2013-01-01

    This paper presents the chemical and preclinical anticancer research on Hedyotis diffusa Willd. in detail, one of the most renowned herbs often prescribed in the polyherbal formulas for cancer treatment in traditional Chinese medicine. Anthraquinones, flavonoids, and terpenoids constitute the majority of the 69 compounds that have been isolated and identified from H. diffusa. The anticancer effects of the methanolic, ethanolic, and aqueous extracts in various preclinical cancer models have been described. This review also summarized the anticancer activity of constituents of the herb and the mechanisms of action. All the studies suggest that H. diffusa has enormous potential in the therapy of cancer and warrants further chemical and pharmacological investigation. PMID:23600735

  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. 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.

  15. 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.

  16. 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.

  17. Isospin mixing at finite temperature in 80Zr

    NASA Astrophysics Data System (ADS)

    Ceruti, Simone; Giaz, A.; Camera, F.; Avigo, R.; Benzoni, G.; Blasi, N.; Bracco, A.; Brambilla, S.; Coelli, S.; Corsi, A.; Crespi, F.; Leoni, S.; Million, B.; Morales-Lopez, A. I.; Pellegri, L.; Nicolini, R.; Riboldi, S.; Vandone, V.; Wieland, O.; Bortolato, D.; Fanin, C.; Gottardo, A.; Valiente-Dobon, J. J.; Bellato, M.; Bazzacco, D.; Mengoni, D.; Michelagnoli, C.; Montanari, D.; Recchia, F.; Farnea, E.; Ur, C.; Zieblinski, M.; Ciemala, M.; Kmiecik, M.; Maj, A.; Myalski, S.; Styczen, J.

    2014-03-01

    Isospin mixing induced by the Coulomb interaction has been studied in the compound nucleus 80Zr at T~2 MeV produced in the fusion-evaporation reaction 40Ca+40Ca at Ebeam = 136 MeV. The isospin impurity was measured using the first step of the Giant Dipole Resonance γ decay. The preliminary value of the Coulomb spreading width has been extracted via statistical model analysis of the measured γ spectrum.

  18. Isospin breaking in low-energy pion-nucleon scattering

    SciTech Connect

    Gibbs, W.R.; Ai, L.; Kaufmann, W.B.

    1995-05-08

    We have analyzed low-energy pion-nucleon data for isospin invariance by comparing charge-exchange amplitudes derived from charge-exchange data with those predicted from recent {pi}{sup {plus_minus}}{ital p} elastic data through the application of isospin invariance. A discrepancy of the order of 7% is observed beyond the contributions of the {pi}{sup {plus_minus}}{ital p} Coulomb interaction and the hadronic mass differences.

  19. Meson mass at real and imaginary chemical potentials

    NASA Astrophysics Data System (ADS)

    Kashiwa, Kouji; Matsuzaki, Masayuki; Kouno, Hiroaki; Sakai, Yuji; Yahiro, Masanobu

    2009-04-01

    Chemical-potential dependence of pi and sigma meson masses is analyzed at both real and imaginary chemical potentials, μR and μI, by using the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model that possesses both the extended Z3 symmetry and chiral symmetry. In the μI region, the meson masses have the Roberge-Weiss periodicity. The μI dependence of the meson masses becomes stronger as temperature increases. We argue that meson masses and physical quantities in the μR region will be determined from lattice QCD data on meson masses in the μI region by using the PNJL model, if the data are measured in the future.

  20. Meson mass at real and imaginary chemical potentials

    SciTech Connect

    Kashiwa, Kouji; Sakai, Yuji; Yahiro, Masanobu; Matsuzaki, Masayuki; Kouno, Hiroaki

    2009-04-01

    Chemical-potential dependence of pi and sigma meson masses is analyzed at both real and imaginary chemical potentials, {mu}{sub R} and {mu}{sub I}, by using the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model that possesses both the extended Z{sub 3} symmetry and chiral symmetry. In the {mu}{sub I} region, the meson masses have the Roberge-Weiss periodicity. The {mu}{sub I} dependence of the meson masses becomes stronger as temperature increases. We argue that meson masses and physical quantities in the {mu}{sub R} region will be determined from lattice QCD data on meson masses in the {mu}{sub I} region by using the PNJL model, if the data are measured in the future.

  1. Higher spin entanglement entropy at finite temperature with chemical potential

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Wu, Jie-qiang

    2016-07-01

    It is generally believed that the semiclassical AdS3 higher spin gravity could be described by a two dimensional conformal field theory with W -algebra symmetry in the large central charge limit. In this paper, we study the single interval entanglement entropy on the torus in the CFT with a W_{3} deformation. More generally we develop the monodromy analysis to compute the two-point function of the light operators under a thermal density matrix with a W_{3} chemical potential to the leading order. Holographically we compute the probe action of the Wilson line in the background of the spin-3 black hole with a chemical potential. We find exact agreement.

  2. 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.

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

    PubMed

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

    2008-10-01

    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. PMID:18783238

  4. Influence of transport variables on isospin transport ratios

    NASA Astrophysics Data System (ADS)

    Coupland, D. D. S.; Lynch, W. G.; Tsang, M. B.; Danielewicz, P.; Zhang, Yingxun

    2011-11-01

    The symmetry energy in the nuclear equation of state affects many aspects of nuclear astrophysics, nuclear structure, and nuclear reactions. Recent constraints from heavy-ion collisions, including isospin diffusion observables, have started to put constraints on the symmetry energy below nuclear saturation density, but these constraints depend on the employed transport model and input physics other than the symmetry energy. To understand these dependencies, we study the influence of the symmetry energy, isoscalar mean-field compressibility and momentum dependence, in-medium nucleon-nucleon cross sections, and light cluster production on isospin diffusion within the pBUU transport code. In addition to the symmetry energy, several uncertain issues strongly affect isospin diffusion, most notably the cross sections and cluster production. In addition, there is a difference in the calculated isospin transport ratios, depending on whether they are computed using the isospin asymmetry either of the residue or of all forward-moving fragments. Measurements that compare the isospin transport ratios of these two quantities would help place constraints on the input physics, such as the density dependence of the symmetry energy.

  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. PMID:26458329

  6. Mass and Isospin Effects in Multifragmentation

    NASA Astrophysics Data System (ADS)

    Sfienti, C.; Adrich, P.; Aumann, T.; Bacri, C. O.; Barczyk, T.; Bassini, R.; Boiano, C.; Botvina, A. S.; Boudard, A.; Brzychczyk, J.; Chbihi, A.; Cibor, J.; Czech, B.; De Napoli, M.; Ducret, J.-E.; Emling, H.; Frankland, J.; Hellström, M.; Henzlova, D.; Kezzar, K.; Immé, G.; Iori, I.; Johansson, H.; Lafriakh, A.; Le Fèvre, A.; Le Gentil, E.; Leifels, Y.; Lynch, W. G.; Lühning, J.; Łukasik, J.; Lynen, U.; Majka, Z.; Mocko, M.; Müller, W. F. J.; Mykulyak, A.; Orth, H.; Otte, A. N.; Palit, R.; Pullia, A.; Raciti, G.; Rapisarda, E.; Sann, H.; Schwarz, C.; Simon, H.; Sokolov, A.; Sümmerer, K.; Trautmann, W.; Tsang, M. B.; Verde, G.; Volant, C.; Wallace, M.; Weick, H.; Wiechula, J.; Wieloch, A.; Zwieglinski, B.

    2005-03-01

    A systematic study of isospin effects in the breakup of projectile spectators at relativistic energies has been performed with the ALADiN spectrometer at the GSI laboratory (Darmstadt). Four different projectiles 197Au, 124La, 124Sn and 107Sn, all with an incident energy of 600 AMeV, have been used, thus allowing a study of various combinations of masses and N/Z ratios in the entrance channel. The measurement of the momentum vector and of the charge of all projectile fragments with Z > 1 entering the acceptance of the ALADiN magnet has been performed with the high efficiency and resolution achieved with the TP-MUSIC IV detector. The Rise and Fall behavior of the mean multiplicity of IMFs as a function of Zbound and its dependence on the isotopic composition has been determined for the studied systems. Other observables investigated so far include mean N/Z values of the emitted light fragments and neutron multiplicities. Qualitative agreement has been obtained between the observed gross properties and the predictions of the Statistical Multifragmentation Model.

  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. 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

  9. 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.

  10. 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...

  11. Computational prediction of the chromosome-damaging potential of chemicals.

    PubMed

    Rothfuss, Andreas; Steger-Hartmann, Thomas; Heinrich, Nikolaus; Wichard, Jörg

    2006-10-01

    We report on the generation of computer-based models for the prediction of the chromosome-damaging potential of chemicals as assessed in the in vitro chromosome aberration (CA) test. On the basis of publicly available CA-test results of more than 650 chemical substances, half of which are drug-like compounds, we generated two different computational models. The first model was realized using the (Q)SAR tool MCASE. Results obtained with this model indicate a limited performance (53%) for the assessment of a chromosome-damaging potential (sensitivity), whereas CA-test negative compounds were correctly predicted with a specificity of 75%. The low sensitivity of this model might be explained by the fact that the underlying 2D-structural descriptors only describe part of the molecular mechanism leading to the induction of chromosome aberrations, that is, direct drug-DNA interactions. The second model was constructed with a more sophisticated machine learning approach and generated a classification model based on 14 molecular descriptors, which were obtained after feature selection. The performance of this model was superior to the MCASE model, primarily because of an improved sensitivity, suggesting that the more complex molecular descriptors in combination with statistical learning approaches are better suited to model the complex nature of mechanisms leading to a positive effect in the CA-test. An analysis of misclassified pharmaceuticals by this model showed that a large part of the false-negative predicted compounds were uniquely positive in the CA-test but lacked a genotoxic potential in other mutagenicity tests of the regulatory testing battery, suggesting that biologically nonsignificant mechanisms could be responsible for the observed positive CA-test result. Since such mechanisms are not amenable to modeling approaches it is suggested that a positive prediction made by the model reflects a biologically significant genotoxic potential. An integration of the

  12. Semi-infinite jellium: Thermodynamic potential, chemical potential, and surface energy

    NASA Astrophysics Data System (ADS)

    Kostrobij, P. P.; Markovych, B. M.

    2015-08-01

    A general expression for the thermodynamic potential of the model of semi-infinite jellium is obtained. By using this expression, the surface energy for the infinite barrier model is calculated. The behavior of the surface energy and of the chemical potential as functions of the Wigner-Seitz radius and the influence of the Coulomb interaction between electrons on the calculated values is studied. It is shown that taking into account the Coulomb interaction between electrons leads to growth of the surface energy. The surface energy is positive in the entire area of the Wigner-Seitz radius. It is shown that taking into account the Coulomb interaction between electrons leads to a decrease of the chemical potential.

  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. Potential effects of environmental chemical contamination in congenital heart disease.

    PubMed

    Gorini, Francesca; Chiappa, Enrico; Gargani, Luna; Picano, Eugenio

    2014-04-01

    There is compelling evidence that prenatal exposures to environmental xenobiotics adversely affect human development and childhood. Among all birth defects, congenital heart disease (CHD) is the most prevalent of all congenital malformations and remains the leading cause of death. It has been estimated that in most cases the causes of heart defects remain unknown, while a growing number of studies have indicated the potential role of environmental agents as risk factors in CHD occurrence. In particular, maternal exposure to chemicals during the first trimester of pregnancy represents the most critical window of exposure for CHD. Specific classes of xenobiotics (e.g. organochlorine pesticides, organic solvents, air pollutants) have been identified as potential risk factors for CHD. Nonetheless, the knowledge gained is currently still incomplete as a consequence of the frequent heterogeneity of the methods applied and the difficulty in estimating the net effect of environmental pollution on the pregnant mother. The presence of multiple sources of pollution, both indoor and outdoor, together with individual lifestyle factors, may represent a further confounding element for association with the disease. A future new approach for research should probably focus on individual measurements of professional, domestic, and urban exposure to physical and chemical pollutants in order to accurately retrace the environmental exposure of parents of affected offspring during the pre-conceptional and pregnancy periods. PMID:24452958

  15. Estimation of Biodegradation Potential of Xenobiotic Organic Chemicals

    PubMed Central

    Larson, Robert J.

    1979-01-01

    A method is described to estimate the biodegradation potential of soluble, insoluble, and unknown organic chemicals. The method consists of two stages: (i) generation of a microbial inoculum in a bench scale semicontinuous activated sludge system during which microorganisms are acclimated to test material and the removal of dissolved organic carbon is monitored and (ii) biodegradability testing (CO2 evolution) in a defined minimal medium containing the test material as the sole carbon and energy source and a dilute bacterial inoculum obtained from the supernatant of homogenized activated sludge generated in the semicontinuous activated sludge system. Removal and biodegradation are measured using nonspecific methods, at initial concentrations of 5 to 10 mg of dissolved organic carbon per liter. Biodegradability data are accurately described by a nonlinear computer model which allows the rate and extent of biodegradation for different compounds to be compared and statistically examined. The evaluation of data generated in the combined removability-biodegradability system allows the biodegradation potential of a variety of xenobiotic organic chemicals to be estimated. PMID:16345479

  16. Rod-shaped Nuclei at Extreme Spin and Isospin.

    PubMed

    Zhao, P W; Itagaki, N; Meng, J

    2015-07-10

    The anomalous rod shape in carbon isotopes has been investigated in the framework of the cranking covariant density functional theory, and two mechanisms to stabilize such a novel shape with respect to the bending motion, extreme spin, and isospin are simultaneously discussed for the first time in a self-consistent and microscopic way. By adding valence neutrons and rotating the system, we have found the mechanism stabilizing the rod shape; i.e., the σ orbitals (parallel to the symmetry axis) of the valence neutrons, important for the rod shape, are lowered by the rotation due to the Coriolis term. The spin and isospin effects enhance the stability of the rod-shaped configuration. This provides a strong hint that a rod shape could be realized in nuclei towards extreme spin and isospin. PMID:26207464

  17. The influence of transport variables on isospin transport ratios

    NASA Astrophysics Data System (ADS)

    Coupland, Daniel; Lynch, William; Danielewicz, Pawel; Tsang, Betty; Zhang, Yingxun

    2008-04-01

    The influence of transport quantities on isospin equilibration in peripheral ^112Sn+^112Sn, ^112Sn+^124Sn, ^124Sn+^112Sn, and ^124Sn+^124Sn collisions is studied in the Boltzmann-Uehling-Uhlenbeck model. The isospin transport ratio constructed from the asymmetry of the projectile residue has been shown to contain information about the density dependence of the symmetry energy. However, the ratio also depends on the momentum dependence of the mean field, in-medium isospin nucleon-nucleon cross-sections, and the stiffness of the symmetry part of the equation of state (EOS). Our simulations will try to untangle the various effects and their influence on the extraction of the symmetry energy terms in the EOS. First results from the simulations and comparisons to other transport model calculations will be presented. This work is supported by the National Science Foundation under Grant PHY-0606007.

  18. 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.

  19. Conservation of Isospin in Neutron-rich Fission Fragments

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    On the occasion of the 75th 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 238U(18O,f) and 208Pb(18O,f) as well as a thermal neutron fission reaction 245Cm(nth,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.

  20. Test of isospin purity in the A=42 isobaric analogs

    SciTech Connect

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

    2004-07-01

    A careful measurement of the lifetime of the first 2{sub T=1}{sup +} state in {sup 42}Sc has allowed an accurate experimental test of isospin purity in the A=42 isobaric analogs by using the isospin formalism. A lifetime of 69 (18) fs has been determined, giving an isoscalar matrix element of 6.8 (8) W.u. Previous measurements of the lifetimes in the mirror nuclei {sup 42}Ca and {sup 42}Ti provided an isoscalar matrix element of 7.1 (5) W.u. which is very close to the presently measured value for {sup 42}Sc.

  1. Proper time regularization at finite quark chemical potential

    NASA Astrophysics Data System (ADS)

    Zhang, Jin-Li; Shi, Yuan-Mei; Xu, Shu-Sheng; Zong, Hong-Shi

    2016-04-01

    In this paper, we use the two-flavor Nambu-Jona-Lasinio (NJL) model to study the quantum chromodynamics (QCD) chiral phase transition. To deal with the ultraviolet (UV) issue, we adopt the popular proper time regularization (PTR), which is commonly used not only for hadron physics but also for the studies with magnetic fields. This regularization scheme can introduce the infrared (IR) cutoff to include quark confinement. We generalize the PTR to zero temperature and finite chemical potential case use a completely new method, and then study the chiral susceptibility, both in the chiral limit case and with finite current quark mass. The chiral phase transition is second-order in μ = 0 and T = 0 and crossover at μ≠0 and T = 0. Three sets of parameters are used to make sure that the results do not depend on the parameter choice.

  2. Isospin in Nuclei: Isospin has been reborn as an important and useful quantum number for all nuclei.

    PubMed

    Robson, D

    1973-01-12

    The major feature of isospin in nuclei that I have discussed here is its application to all nuclei. The rebirth of this quantum number in nuclear physics occurred in the early 1960's and was initiated almost entirely by the important work of Anderson et al. (4) and Fox et al. (5). There is still great interest in the use of isospin in its fullest sense as predicted by Wigner (3), and indeed isospin concepts have been largely responsible for demonstrating that nuclei in the doubly "magic number" region of (208)Pb are remarkably in agreement with shell model theory. The early experiments have also initiated a whole new set of more sophisticated experiments (some of which I have briefly alluded to above) which promise to keep many physicists busy for a long time to come. A particularly interesting series of experiments are those being performed (15) at Duke University with high-resolution proton beams. This work shows the highly detailed nature of analogue resonances, that is, as coherent superpositions of many complicated compound states yielding a beautifully modulated wave train, the modulation being observed only in conventional experiments with poor-resolution proton beams. Similarly, nuclear theorists have been led to vastly improve their interpretation of, and computational techniques for, both nuclear reactions and nuclear structure in order to meet the more stringent tests provided by such experiments. Perhaps a lesson can be learned from the historical development of the isospin concept. In the past the belief that T . T would not significantly commute with the dynamical Hamiltonian so that isospin would not be conserved sufficiently well enough certainly delayed the nuclear travels of isospin into the realm of heavy nuclei. Hopefully the same mistake will not occur in the future for other approximate symmetries of nature. PMID:17842982

  3. Importance of imaginary chemical potential for determination of QCD phase diagram

    NASA Astrophysics Data System (ADS)

    Kashiwa, Kouji; Kouno, Hiroaki; Sakai, Yuji; Yahiro, Masanobu

    2009-10-01

    Lattice QCD (LQCD) calculations have the well-known sign problem at finite real chemical potential. One approach to circumvent the problem is the analytic continuation of LQCD data to real chemical potential from imaginary one. This approach, however, has some problems in moderate real chemical potential region. Therefore, we propose the new approach, Imaginary chemical potential matching approach, to quantitatively determine the QCD phase diagram by using a phenomenological model that reproduce LQCD data at imaginary chemical potential. In this approach, we fit the model parameter by LQCD data at imaginary chemical potential. At the imaginary chemical potential, the QCD partition function has the special periodicity called Roberge-Weiss (RW) periodicity. Therefore, an adopted model must have the RW periodicity. We reveal the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model has the RW periodicity. Moreover, we investigate the meson mass behavior and show that meson mass is useful for fitting the model parameters at imaginary chemical potential.

  4. 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.

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

    PubMed

    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

  6. 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

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

    PubMed

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

    2014-01-01

    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. PMID:24487567

  8. Global calculations of microscopic energies and nuclear deformations: Isospin dependence of the spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Wu, Zhe-Ying; Qi, Chong; Wyss, Ramon; Liu, Hong-Liang

    2015-08-01

    Background: The deviation between different model calculations that may occur when one goes toward regions where the masses are unknown is getting increased attention. This is related to the uncertainties of the different models which may have not been fully understood. Purpose: To explore in detail the effect of the isospin dependence of the spin-orbital force in the Woods-Saxon potential on global binding energy and deformation calculations. Method: The microscopic energies and nuclear deformations of about 1850 even-even nuclei are calculated systematically within the macroscopic-microscopic framework using three Woods-Saxon parametrizations, with different isospin dependencies, which were constructed mainly for nuclear spectroscopy calculations. Calculations are performed in the deformation space (β2,γ ,β4) . Both the monopole and doubly stretched quadrupole interactions are considered for the pairing channel. Results: The ground-state deformations obtained by the three calculations are quite similar to each other. Large differences are seen mainly in neutron-rich nuclei and in superheavy nuclei. Systematic calculations on the shape-coexisting second minima are also presented. As for the microscopic energies of the ground states, the results are also very close to each other. Only in a few cases the difference is larger than 2 MeV. The total binding energy is estimated by adding the macroscopic energy provided by the usual liquid drop model with its parameters fitted through the least square root and minimax criteria. Calculations are also compared with the results of other macroscopic-microscopic mass models. Conclusions: All the three calculations give similar values for the deformations, microscopic energies, and binding energies of most nuclei. One may expect to have a better understanding of the isospin dependence of the spin-orbital force with more data on proton- and neutron-rich nuclei.

  9. 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. PMID:26476351

  10. Production of organic chemicals via bioconversion: A review of the potential

    SciTech Connect

    Leeper, S.A.; Ward, T.E.; Andrews, G.F.

    1991-07-01

    The United States should develop alternative feedstocks for production of organic chemicals as a step in reducing dependence on foreign oil and to protect the US economy from oil supply disruptions. Potential alternative feedstocks include lignocellulose, polysaccharides, and sugars. These feedstocks can be converted to organic chemicals via bioconversion; sources include feedstock crops (lignocellulosic, polysac-charide, and sugar crops grown specifically for use as feedstocks in organic chemicals production) and industrial, municipal, and agricultural wastes. A wide range of chemicals can be produced via bioconversion, including existing commodity chemicals and entirely new chemicals and polymers. In this review, potential feedstocks are described and are shown to be sufficient to support a bioconversion -- based organic chemicals industry. In addition, the current US organic chemicals industry is briefly described. The potential of bioconversion for production of existing commodity chemicals and entirely new chemicals and polymers is discussed. 228 refs., 21 tabs.

  11. 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...

  12. Characterization of Indian beers: chemical composition and antioxidant potential.

    PubMed

    Pai, Tapasya V; Sawant, Siddhi Y; Ghatak, Arindam A; Chaturvedi, Palak A; Gupte, Arpita M; Desai, Neetin S

    2015-03-01

    Chemical composition, antioxidant potential and corresponding lipid preoxidation of Indian commercial beers were evaluated. The presence of polyphenolic compounds such as tannic acid, gallic acid, catechol, vanillin, caffeic acid, quercetin, p-coumaric acid and rutin was quantified using LC-MS while the organic acids including tartaric, malic, acetic, citric and succinic acids were analysed using HPLC. Beer sample B8 had the greatest concentration of phenolic and flavonoid components (0.620 ± 0.084 mg/mL and 0.379 ± 0.020 mg/mL respectively) among the beer samples studied. The DPPH radical scavenging activity was observed in the range of 68.34 ± 0.85 % to 89.90 ± 0.71 % and ABTS radical cation scavenging activity was in the range of 59.75 ± 0.20 % to 76.22 ± 0.50 %. Percent protection in lipid peroxidation was quantified to be maximum (54.45 ± 3.39 %) in sample B5. Total phenolic content positively correlates with antioxidant assays, DPPH and ABTS (r = 0.35 and r = 0.58 respectively) with p < 0.001 and also with lipid peroxidation (r = 0.04) with p < 0.001. Negative correlation was observed between total flavonoid content with ABTS and lipid peroxidation (r = -0.1 and r = -0.05) respectively. The process of brewing warrants additional research to determine how the concentration of selected phenolic compounds can be increased. PMID:25745209

  13. 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.

  14. Isospin-violating dark matter with colored mediators

    NASA Astrophysics Data System (ADS)

    Hamaguchi, Koichi; Liew, Seng Pei; Moroi, Takeo; Yamamoto, Yasuhiro

    2014-05-01

    In light of positive signals reported by the CDMS-II Si experiment and the recent results of the LUX and SuperCDMS experiments, we study isospin-violating dark matter scenarios assuming that the interaction of the dark matter is mediated by colored particles. We investigate the phenomenology of the model, including collider searches, flavor and CP phenomenology. A minimal possible scenario includes scalar dark matter and new vector-like colored fermions with masses of O(1) TeV as mediators. Such a scenario may be probed at the 14 TeV LHC, while flavor and CP constraints are stringent and severe tuning in the couplings is unavoidable. We also found that, as an explanation of the CDMS-II Si signal, isospin-violating fermionic dark matter models with colored scalar mediators are disfavored by the LHC constraints.

  15. 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.

  16. Isospin effect on probing nuclear dissipation with fission cross sections

    NASA Astrophysics Data System (ADS)

    Tian, J.; Ye, W.

    2016-08-01

    Nuclear dissipation retards fission. Using the stochastic Langevin model, we calculate the drop of fission cross section caused by friction over its standard statistical-model value, σfdrop, as a function of the presaddle friction strength for fissioning nuclei 195Bi, 202Bi, and 209Bi as well as for different angular momenta. We find that friction effects on σfdrop are substantially enhanced with increasing isospin of the Bi system and become greater with decreasing angular momentum. Our findings suggest that in experiments, to better constrain the strength of presaddle dissipation through the measurement of fission excitation functions, it is optimal to yield those compound systems with a high isospin and a low spin. Furthermore, we analyze the data of fission excitation functions of 210Po and 209Bi systems, which are populated in p +209Bi and p +208Pb reactions and which have a high isospin and a low spin, and find that Langevin calculations with a presaddle friction strength of (3-5) ×10-21 s-1 describe these experimental fission data very well.

  17. Topological feature and phase structure of QCD at complex chemical potential

    NASA Astrophysics Data System (ADS)

    Kashiwa, Kouji; Ohnishi, Akira

    2015-11-01

    The pseudo-critical temperature of the confinement-deconfinement transition and the phase transition surface are investigated by using the complex chemical potential. We can interpret the imaginary chemical potential as the Aharonov-Bohm phase, then the analogy of the topological order suggests that the Roberge-Weiss endpoint would define the pseudo-critical temperature. The behavior of the Roberge-Weiss endpoint at small real quark chemical potential is investigated with the perturbative expansion. The expected QCD phase diagram at complex chemical potential is presented.

  18. Two-color QCD with non-zero chiral chemical potential

    NASA Astrophysics Data System (ADS)

    Braguta, V. V.; Goy, V. A.; Ilgenfritz, E. M.; Kotov, A. Yu.; Molochkov, A. V.; Müller-Preussker, M.; Petersson, B.

    2015-06-01

    The phase diagram of two-color QCD with non-zero chiral chemical potential is studied by means of lattice simulation. We focus on the influence of a chiral chemical potential on the confinement/deconfinement phase transition and the breaking/restoration of chiral symmetry. The simulation is carried out with dynamical staggered fermions without rooting. The dependences of the Polyakov loop, the chiral condensate and the corresponding susceptibilities on the chiral chemical potential and the temperature are presented. The critical temperature is observed to increase with increasing chiral chemical potential.

  19. Tracing isospin with the {pi}{sup -}/{pi}{sup +} ratio in central heavy ion collisions

    SciTech Connect

    Zhang Ming; Xiao Zhigang; Zhu Shengjiang

    2010-10-15

    Within an isospin- and momentum-dependent hadronic transport model, we have investigated the isospin mixing with the probe of the {pi}{sup -}/{pi}{sup +} ratio in central isospin asymmetric {sup 96}Ru+{sup 96}Zr collision at an incident energy of 400 MeV/u. The isospin equilibrium is not reached according to the asymmetrical distribution of the {pi}{sup -}/{pi}{sup +} ratio with rapidity. In comparison with the nucleon observable, it suggests that the pion ratio {pi}{sup -}/{pi}{sup +} is a promising observable to probe the relaxation of isospin degree of freedom in central heavy ion collisions without being strongly affected by the surface effect. Because of the small system size and rather strong effect of rescattering on pions, the isospin mixing shows insignificant dependence on the stiffness of the symmetry energy in the relevant colliding system.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  1. 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...

  2. Potential animal model of multiple chemical sensitivity with cholinergic supersensitivity.

    PubMed

    Overstreet, D H; Miller, C S; Janowsky, D S; Russell, R W

    1996-07-17

    Multiple Chemical Sensitivity (MCS) is a clinical phenomenon in which individuals, after acute or intermittent exposure to one or more chemicals, commonly organophosphate pesticides (OPs), become overly sensitive to a wide variety of chemically-unrelated compounds, which can include ethanol, caffeine and other psychotropic drugs. The Flinders Sensitive Line (FSL) rats were selectively bred to be more sensitive to the OP diisopropylfluorophosphate (DFP) compared to their control counterparts, the Flinders Resistant Line (FRL) rats. The present paper will summarize evidence which indicates that the FSL rats exhibit certain similarities to individuals with MCS. In addition to their greater sensitivity to DFP, the FSL rats are more sensitive to nicotine and the muscarinic agonists arecoline and oxotremorine, suggesting that the number of cholinergic receptors may be increased, a conclusion now supported by biochemical evidence. The FSL rats have also been found to exhibit enhanced responses to a variety of other drugs, including the serotonin agonists m-chlorophenylpiperazine and 8-OH-DPAT, the dopamine antagonist raclopride, the benzodiazepine diazepam, and ethanol. MCS patients report enhanced responses to many of these drugs, indicating some parallels between FSL rats and MCS patients. The FSL rats also exhibit reduced activity and appetite and increased REM sleep relative to their FRL controls. Because these behavioral features and the enhanced cholinergic responses are also observed in human depressives, the FSL rats have been proposed as a genetic animal model of depression. It has also been reported that MCS patients have a greater incidence of depression, both before and after onset of their chemical sensitivities, so cholinergic supersensitivity may be a state predisposing individuals to depressive disorders and/or MCS. Further exploration of the commonalities and differences between MCS patients, human depressives, and FSL rats will help to elucidate the

  3. Bioconcentration potential of organic environmental chemicals in humans

    SciTech Connect

    Geyer, H.; Scheunert, I.; Korte, F.

    1986-12-01

    A list of environmental chemicals detectable in adipose tissue and/or milk of non-occupationally exposed humans is presented. Besides their physiochemical properties (n-octanol/water partition coefficient and water solubility), their acceptable daily intake (ADI) values, production figures, fate in the environment, concentrations in human adipose tissue, and data from total diet studies from market basket investigations are given. Average bioconcentration factors (BCF) of polychlorinated biphenyls (PCBs), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), DDT, hexachlorobenzene (HCB), dieldrin, hexachlorocyclohexane isomers (alpha-HCH, beta-HCH, gamma-HCH, delta-HCH), pentachlorophenol (PCP), and 3,5-di-tert-butyl-4-hydroxytoluene (BHT) in human adipose tissue are calculated. The bioconcentration factors (wet wt basis) of these compounds are between 3 and 47 times higher in humans than in rats. The environmental chemicals are divided into three groups in respect to their bioconcentration factors in human adipose tissue: group I, high BCF (greater than 100); group II, medium BCF (10-100); and group III, low BCF (less than 10). The bioconcentration factors are useful for hazard assessment of chemicals to humans.

  4. 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.

  5. 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...

  6. Electronic Chemical Potentials of Porous Metal–Organic Frameworks

    PubMed Central

    2014-01-01

    The binding energy of an electron in a material is a fundamental characteristic, which determines a wealth of important chemical and physical properties. For metal–organic frameworks this quantity is hitherto unknown. We present a general approach for determining the vacuum level of porous metal–organic frameworks and apply it to obtain the first ionization energy for six prototype materials including zeolitic, covalent, and ionic frameworks. This approach for valence band alignment can explain observations relating to the electrochemical, optical, and electrical properties of porous frameworks. PMID:24447027

  7. 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.

  8. 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. PMID:27126897

  9. Isospin effects in the exclusive dp 3He reaction

    NASA Astrophysics Data System (ADS)

    Mielke, M.; Burmeister, I.; Chiladze, D.; Dymov, S.; Fritzsch, C.; Gebel, R.; Goslawski, P.; Hartmann, M.; Kacharava, A.; Khoukaz, A.; Kulessa, P.; Lorentz, B.; Mersmann, T.; Mikirtychiants, S.; Ohm, H.; Papenbrock, M.; Rausmann, T.; Serdyuk, V.; Ströher, H.; Täschner, A.; Valdau, Yu.; Wilkin, C.

    2014-06-01

    The differential cross section for the exclusive reaction has been measured with high resolution and large statistics over a large fraction of the backward 3He hemisphere at the excess energy 265 MeV using the COSY-ANKE magnetic spectrometer. Though the well-known ABC enhancement is observed in the spectrum, the differences detected between the and invariant-mass distributions show that there must be some isospin-one production even at relatively low excess energies. The invariant-mass differences are modeled in terms of the sequential decay.

  10. Modification of nuclear mass formula by considering isospin effects

    SciTech Connect

    Wang Ning; Liu Min; Wu Xizhen

    2010-04-15

    We propose a semiempirical nuclear mass formula based on the macroscopic-microscopic method in which the isospin and mass dependence of model parameters are investigated with the Skyrme energy density functional. The number of model parameters is considerably reduced compared with the finite range droplet model. The rms deviation with respect to 2149 measured nuclear masses is reduced by 21%, falling to 0.516 MeV. The new magic number N=16 in light neutron-rich nuclei and the shape coexistence phenomena for some nuclei have been examined with the model. The shell corrections of superheavy nuclei are also predicted.

  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. Isospin effects on the mass dependence of the balance energy

    SciTech Connect

    Gautam, Sakshi; Sood, Aman D.

    2010-07-15

    We study the effect of isospin degree of freedom on balance energy throughout the mass range between 50 and 350 for two sets of isotopic systems with N/A= 0.54 and 0.57 as well as isobaric systems with N/A= 0.5 and 0.58. Our findings indicate that different values of balance energy for two isobaric systems may be mainly due to the Coulomb repulsion. We also demonstrate clearly the dominance of Coulomb repulsion over symmetry energy.

  13. In-medium and isospin effects on particle production near threshold energies in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Feng, Zhao-Qing; Xie, Wen-Jie; Chen, Peng-Hui; Chen, Jie; Jin, Gen-Ming

    2015-10-01

    Dynamics of pseudoscalar mesons (π ,η ,K , and K ¯) and hyperons (Λ and Σ ) produced in heavy-ion collisions near threshold energies has been investigated within the Lanzhou quantum molecular dynamics transport model. The in-medium modifications on particle production in dense nuclear matter are implemented in the model through corrections on the elementary cross sections and by inclusion of the meson-nucleon (or hyperon-nucleon) potentials, in which the isospin effects are considered. It is found that the transportation of particles are influenced with the in-medium corrections. The total number of pions is reduced with an isospin-, density-, and momentum-dependent pion-nucleon potential. However, the ratios of charged pions is enhanced with inclusion of the potential. The production of eta in the domain of midrapidities and high momenta is sensitive to the η -nucleon potential but weakly depends on symmetry energy. The attractive antikaon-nucleon potential enhances the subthreshold K ¯ production and also influences the structure of phase-space distributions. The dynamics of etas, kaons, antikaons, and hyperons is also influenced by the pion potential because of collisions between pions and nucleons (resonances). The impacts of mean-field potentials on particle dynamics are investigated, such as the phase-space distributions from rapidity and transverse momentum spectra, inclusive invariant spectra, collective flows, etc.

  14. 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. PMID:27343945

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

  16. CHEMICAL REMOVAL OF BIOMASS FROM WASTE AIR BIOTRICKLING FILTERS: SCREENING CHEMICALS OF POTENTIAL INTEREST. (R825392)

    EPA Science Inventory

    A protocol was developed to rapidly assess the efficiency of chemical washing for the removal of excess biomass from biotrickling filters for waste air treatment. Although the experiment was performed on a small scale, conditions were chosen to simulate application in full-scale ...

  17. 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. PMID:26443032

  18. 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. PMID:27506286

  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. WORKSHOP ON STATUS OF TEST METHODS FOR ASSESSING POTENTIAL OF CHEMICALS TO INDUCE RESPIRATORY ALLERGIC REACTIONS

    EPA Science Inventory

    Because of the association between allergy and asthma and the increasing incidence of morbidity and mortality due to asthma, there is growing concern over the potential of industrial chemicals to produce allergic reactions in the respiratory tract. Two classes of chemicals have b...

  2. 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…

  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. a Direct Probe for Chemical Potentials Difference Between Neutron and Protons in Heavy-Ion Collisions

    NASA Astrophysics Data System (ADS)

    Ma, Chun-Wang; Zhang, Yan-Li; Wang, Shan-Shan

    We briefly introduce the newly proposed probe to the neutron and proton chemical potential (and density) difference, which is called as the isobaric yield ratio difference (IBD). The IBD probe is related to the chemical potential difference of neutrons and protons between two reactions, at the same time, the nuclear density difference between two reactions. The relationship between the IBD probe and the isoscaling method has also been discussed.

  5. Drag force of Anisotropic plasma at finite U(1) chemical potential

    NASA Astrophysics Data System (ADS)

    Cheng, Long; Ge, Xian-Hui; Wu, Shang-Yu

    2016-05-01

    We perform the calculation of the drag force acting on a massive quark moving through an anisotropic N=4 SU(N) Super Yang-Mills plasma in the presence of a U(1) chemical potential. We present the numerical results for any value of the anisotropy and arbitrary direction of the quark velocity with respect to the direction of the anisotropy. We find the effect of the chemical potential or charge density will enhance the drag force for our charged solution.

  6. 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.

  7. 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.

  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. New Skyrme interaction with improved spin-isospin properties

    NASA Astrophysics Data System (ADS)

    Roca-Maza, X.; Colò, G.; Sagawa, H.

    2012-09-01

    A correct determination of the spin-isospin properties of the nuclear effective interaction should lead to, among other improvements, an accurate description of the Gamow-Teller resonance (GTR). These nuclear excitations impact on a variety of physical processes: from the response in charge-exchange reactions of nuclei naturally present in the Earth, to the description of the stellar nucleosynthesis and of the pre-supernova explosion core-collapse evolution of massive stars in the Universe. A reliable description of the GTR provides also stringent tests for neutrinoless double-β decay calculations. We present a new Skyrme interaction as accurate as previous forces in the description of finite nuclei and of uniform matter properties around saturation density, and that accounts well for the GTR in 48Ca, 90Zr, and 208Pb, and the isobaric analog resonance and spin dipole resonance in 90Zr and 208Pb.

  10. 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.

  11. 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.

  12. POTENTIALLY TOXIC AND HAZARDOUS SUBSTANCES IN THE INDUSTRIAL ORGANIC CHEMICALS AND ORGANIC DYES AND PIGMENTS INDUSTRIES

    EPA Science Inventory

    The objective of this program were identification of the potential hazards associated with the production and use of industrial organic chemicals (IOC) and organic dyes and pigments (ODP) and determination of the state of the art of the control and treatment of potentially hazard...

  13. 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...

  14. Isospin effects in 40,48Ca+40,48Ca collisions

    NASA Astrophysics Data System (ADS)

    Henzl, V.; Henzlova, D.; Kilburn, M.; Verde, G.; Brown, D.; Chbihi, A.; Coupland, D.; Elson, J.; Famiano, M.; Herlitzius, C.; Hudan, S.; Lee, J.; Lukyanov, S.; Lynch, W.; Rogers, A.; Sanetullaev, A.; Sobotka, L.; de Souza, R. T.; Sun, Z. Y.; Tsang, B.; Wallace, M.; Xu, K.; Youngs, M.

    2010-03-01

    The isospin dependence of two proton correlations is studied in 40Ca+40Ca and 48Ca+48Ca collisions at E/A=80MeV. Measurements were performed with the HiRA detector array complemented by the 4π Ball at NSCL. We observe a strong isospin dependence of the pp-correlation functions; however the emitting source radius extracted using the imaging technique yields no sensitivity to the isospin of the reaction system. We interpret this result as a consequence of smaller fraction of fast proton emission in the neutron rich 48Ca system.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

    Sharma, Arun

    2016-05-01

    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 16O+Br80,84,92 and 16O+Ag108,113,122. 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.

  17. Isospin diffusion in {sup 58}Ni-induced reactions at intermediate energies. I. Experimental results

    SciTech Connect

    Galichet, E.; Rivet, M. F.; Borderie, B.; Bougault, R.; Durand, D.; Lopez, O.; Manduci, L.; Tamain, B.; Vient, E.; Dayras, R.; Volant, C.; Rosato, E.

    2009-06-15

    Isospin diffusion in semiperipheral collisions is probed as a function of the dissipated energy by studying two systems {sup 58}Ni+{sup 58}Ni and {sup 58}Ni+{sup 197}Au, over the incident energy range 52A-74A MeV. A close examination of the multiplicities of light products in the forward part of the phase space clearly shows an influence of the isospin of the target on the neutron richness of these products. A progressive isospin diffusion is observed when collisions become more central, in connection with the interaction time.

  18. Chemical potential, Helmholtz free energy and entropy of argon with kinetic Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Fan, C.; Do, D. D.; Nicholson, D.; Ustinov, E.

    2014-01-01

    We present a method based on kinetic Monte Carlo (kMC) to determine the chemical potential, Helmholtz free energy and entropy of a fluid within the course of a simulation. The procedure requires no recourse to auxiliary methods to determine the chemical potential, such as the implementation of a Widom scheme in Metropolis Monte Carlo simulations, as it is determined within the course of the simulation. The equation for chemical potential is proved, for the first time in the literature, to have a direct connection with inverse Widom potential theory in using real molecules rather than ghost molecules. We illustrate this new procedure by several examples, including fluid argon and adsorption of argon as a non-uniform fluid on a graphite surface and in slit pores.

  19. Heavy quark scattering and quenching in a QCD medium at finite temperature and chemical potential

    NASA Astrophysics Data System (ADS)

    Berrehrah, H.; Bratkovskaya, E.; Cassing, W.; Gossiaux, P. B.; Aichelin, J.

    2015-05-01

    The heavy quark collisional scattering on partons of the quark gluon plasma (QGP) is studied in a quantum chromodynamics medium at finite temperature and chemical potential. We evaluate the effects of finite parton masses and widths, finite temperature T , and quark chemical potential μq on the different elastic cross sections for dynamical quasiparticles (on- and off-shell particles in the QGP medium as described by the dynamical quasiparticle model "DQPM") using the leading order Born diagrams. Our results show clearly the decrease of the q Q and g Q total elastic cross sections when the temperature and the quark chemical potential increase. These effects are amplified for finite μq at temperatures lower than the corresponding critical temperature Tc(μq) . Using these cross sections we, furthermore, estimate the energy loss and longitudinal and transverse momentum transfers of a heavy quark propagating in a finite temperature and chemical potential medium. Accordingly, we have shown that the transport properties of heavy quarks are sensitive to the temperature and chemical potential variations. Our results provide some basic ingredients for the study of charm physics in heavy-ion collisions at Beam Energy Scan at RHIC and CBM experiment at FAIR.

  20. Isospin and deformation studies in the odd-odd N=Z nucleus {sup 54}Co

    SciTech Connect

    Rudolph, D.; Andersson, L.-L.; Ekman, J.; Erten, O.; Fahlander, C.; Johansson, E. K.; Andreoiu, C.; Bengtsson, R.; Ragnarsson, I.; Bentley, M. A.; Williams, S. J.; Carpenter, M. P.; Seweryniak, D.; Charity, R. J.; Reviol, W.; Sarantites, D. G.; Clark, R. M.; Fallon, P.; Macchiavelli, A. O.; Svensson, C. E.

    2010-11-15

    High-spin states in the odd-odd N=Z nucleus {sup 54}Co have been investigated by the fusion-evaporation reaction {sup 28}Si({sup 32}S,1{alpha}1p1n){sup 54}Co. Gamma-ray information gathered with the Ge detector array Gammasphere was correlated with evaporated particles detected in the charged particle detector system Microball and a 1{pi} neutron detector array. A significantly extended excitation scheme of {sup 54}Co is presented, which includes a candidate for the isospin T=1, 6{sup +} state of the 1f{sub 7/2}{sup -2} multiplet. The results are compared to large-scale shell-model calculations in the fp shell. Effective interactions with and without isospin-breaking terms have been used to probe isospin symmetry and isospin mixing. A quest for deformed high-spin rotational cascades proved negative. This feature is discussed by means of cranking calculations.

  1. 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}.

  2. Chemically transferable coarse-grained potentials from conditional reversible work calculations.

    PubMed

    Brini, E; van der Vegt, N F A

    2012-10-21

    The representability and transferability of effective pair potentials used in multiscale simulations of soft matter systems is ill understood. In this paper, we study liquid state systems composed of n-alkanes, the coarse-grained (CG) potential of which may be assumed pairwise additive and has been obtained using the conditional reversible work (CRW) method. The CRW method is a free-energy-based coarse-graining procedure, which, by means of performing the coarse graining at pair level, rigorously provides a pair potential that describes the interaction free energy between two mapped atom groups (beads) embedded in their respective chemical environments. The pairwise nature of the interactions combined with their dependence on the chemically bonded environment makes CRW potentials ideally suited in studies of chemical transferability. We report CRW potentials for hexane using a mapping scheme that merges two heavy atoms in one CG bead. It is shown that the model is chemically and thermodynamically transferable to alkanes of different chain lengths in the liquid phase at temperatures between the melting and the boiling point under atmospheric (1 atm) pressure conditions. It is further shown that CRW-CG potentials may be readily obtained from a single simulation of the liquid state using the free energy perturbation method, thereby providing a fast and versatile molecular coarse graining method for aliphatic molecules. PMID:23083154

  3. 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. PMID:26382402

  4. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. 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. PMID:22089525

  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. Isospin effects on the energy of vanishing flow in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Gautam, Sakshi; Chugh, Rajiv; Sood, Aman D.; Puri, Rajeev K.; Hartnack, Ch; Aichelin, J.

    2010-08-01

    Using the isospin-dependent quantum molecular dynamics model we study the isospin effects on the disappearance of flow for the reactions of 58Ni + 58Ni and 58Fe + 58Fe as a function of the impact parameter. We found good agreement between our calculations and experimentally measured energy of vanishing flow at all colliding geometries. Our calculations reproduce the experimental data within 5% (10%) at central (peripheral) geometries.

  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. Chiral symmetry restoration at large chemical potential in strongly coupled SU(N) gauge theories

    SciTech Connect

    Tomboulis, E. T.

    2013-12-15

    We show that at sufficiently large chemical potential SU(N) lattice gauge theories in the strong coupling limit with staggered fermions are in a chirally symmetric phase. The proof employs a polymer cluster expansion which exploits the anisotropy between timelike and spacelike directions in the presence of a quark chemical potential μ. The expansion is shown to converge in the infinite volume limit at any temperature for sufficiently large μ. All expectations of chirally non-invariant local fermion operators vanish identically, or, equivalently, their correlations cluster exponentially, within the expansion. The expansion itself may serve as a computational tool at large μ and strong coupling.

  11. Chemical potential derivatives and preferential interaction parameters in biological systems from Kirkwood-Buff theory.

    PubMed

    Smith, Paul E

    2006-08-01

    New expressions for chemical potential derivatives and preferential interaction parameters for ternary mixtures are derived for open, semiopen, and closed ensembles in terms of Kirkwood-Buff integrals, where all three components are present at finite concentrations. This is achieved using a simple approach that avoids the use of the general matrix formulation of Kirkwood-Buff theory. The resulting expressions provide a rigorous foundation for the analysis of experimental and simulation data. Using the results, a simple model is developed and used to investigate the possible effects of finite protein concentrations on the corresponding cosolvent dependent chemical potential and denaturation thermodynamics. PMID:16679363

  12. Determination of QCD phase diagram from the imaginary chemical potential region

    SciTech Connect

    Sakai, Yuji; Kashiwa, Kouji; Yahiro, Masanobu; Kouno, Hiroaki; Matsuzaki, Masayuki

    2009-05-01

    We test the reliability of the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model, comparing the model result with the lattice data at nonzero imaginary chemical potential. The PNJL model with the vector-type four-quark and scalar-type eight-quark interactions reproduces the lattice data on the pseudocritical temperatures of the deconfinement and chiral phase transitions. The QCD phase diagram in the real chemical potential region is predicted by the PNJL model. The critical end point survives, even if the vector-type four-quark interaction is taken into account.

  13. Shot noise in superconducting wires with a periodic modulation of the chemical potential

    NASA Astrophysics Data System (ADS)

    Chen, Qiao; Zhao, Hong-Kang; Xu, H. Q.

    2015-04-01

    We investigate the shot noise in superconducting wires under the periodic modulation of the chemical potential. The nonequilibrium Green's function technique is employed, and the formula for current and shot noise is obtained. The coupling between the Majorana bound states at ends of wire can be tuned by the periodic modulation of chemical potential. It is related with the strength A and the phase δ intimately. The current, shot noise and the corresponding Fano factor display oscillation behavior as the strength A increases. In addition, the coupling between Majorana bound states can be suppressed by strong coupling between leads and superconducting wire.

  14. The influence of isospin on both statistical and dynamical aspects of HI reactions

    NASA Astrophysics Data System (ADS)

    Sobotka, Lee

    2003-04-01

    Several aspects of how isospin can influence reactions will be discussed. From the statistical side, I will review how isospin influences the level density and, for example, residue production in fusion reactions. The most interesting aspect here is how the continuum, many-body effects and isospin conspire to make the general question of nuclear level densities at the limits of stability interesting. What is already known about the isospin dependence of nuclear level densities, what can be experimentally considered with the facilities presently available and those on the drawing board will be discussed. The status of our knowledge of how isospin influences heavy-ion reaction dynamics at intermediate energy will be presented. The theoretical argument for isospin fractionation will be reviewed as well as the some of the pit-falls in searching for this effect experimentally. The present ambiguous status of this search is reviewed. Finally, I will address the largest issue in this subfield, the possibility that flow (and other) measurements might contribute to our knowledge of the isopin dependence of the EoS. Our present uncertainty and significance of this aspect of the EoS as well as what specific measurements can be done to address this issue will be presented.

  15. Deconfinement and chiral restoration in non-local PNJL models at zero and imaginary chemical potential

    NASA Astrophysics Data System (ADS)

    Pagura, V.; Gómez Dumm, D.; Scoccola, N. N.

    2012-01-01

    We study the deconfinement and chiral restoration transitions in the context of non-local PNJL models, considering the impact of the presence of dynamical quarks on the scale parameter appearing in the Polyakov potential. We show that the corresponding critical temperatures are naturally entangled for both zero and imaginary chemical potential, in good agreement with lattice QCD results. We also analyze the Roberge-Weiss transition, which is found to be first order at the associated endpoint.

  16. 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...

  17. 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.

  18. Draft Genome Sequence of Acetobacterium bakii DSM 8239, a Potential Psychrophilic Chemical Producer through Syngas Fermentation

    PubMed Central

    Hwang, Soonkyu; Song, Yoseb

    2015-01-01

    Acetobacterium bakii DSM 8239 is an anaerobic, psychrophilic, and chemolithoautotrophic bacterium that is a potential platform for producing commodity chemicals from syngas fermentation. We report here the draft genome sequence of A. bakii DSM 8239 (4.14 Mb) to elucidate its physiological and metabolic properties related to syngas fermentation. PMID:26404601

  19. 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...

  20. 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...

  1. Calculation of equation of state of QCD at zero temperature and finite chemical potential

    NASA Astrophysics Data System (ADS)

    Jiang, Yu; Li, Ning; Sun, Wei-Min; Zong, Hong-Shi

    2010-09-01

    In this paper we calculate the equation of state (EOS) of QCD at zero temperature and finite chemical potential by using several models of quark propagators including the Dyson-Schwinger equations (DSEs) model, the hard-dense-loop (HDL) approximation and the quasi-particle model. The results are analyzed and compared with the known results in the literature.

  2. 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.

  3. An alternative approach to the Boltzmann distribution through the chemical potential

    NASA Astrophysics Data System (ADS)

    D'Anna, Michele; Job, Georg

    2016-05-01

    The Boltzmann distribution is one of the most significant results of classical physics. Despite its importance and its wide range of application, at high school level it is mostly presented without any derivation or link to some basic ideas. In this contribution we present an approach based on the chemical potential that allows to derive it directly from the basic idea of thermodynamical equilibrium.

  4. Effect of the chiral chemical potential on the position of the critical endpoint

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Wang, Yong-Long; Cui, Zhu-Fang; Zong, Hong-Shi

    2015-02-01

    The effect of chiral imbalance on the QCD phase structure is studied in a framework of Dyson-Schwinger equations. It is found that the chiral phase transition is always a crossover in the T -μ5 plane when μ is 0 MeV or small values. The trail of the critical endpoints (CEPs) along with the variation of the chiral chemical potential is given. We find that the effect of μ5 is somewhat different from the existing chiral model calculations; namely, the CEP first moves roughly along the phase boundary of T -μ plane in a smaller μ direction, as in the chiral model calculations, but turns in the opposite direction to move away from the small chemical potential region, which has never been observed before. In addition, we also discuss the possibility of whether the study at finite temperature and chiral chemical potential can provide some useful information for the detection of the CEP at finite temperature and baryon chemical potential, since the former can be calculated in lattice QCD without the sign problem.

  5. 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 ...

  6. Isospin effects in two-particle correlation functions

    NASA Astrophysics Data System (ADS)

    Henzl, Vladimir; Henzlova, D.; Famiano, M.; Kilburn, M.; Lynch, W.; Coupland, D.; Elson, J.; Herlitzius, C.; Hudan, S.; Lee, J.; Lukyanov, S.; Rogers, A.; Sanetullaev, A.; de Souza, R.; Sobotka, L.; Sun, Z.; Tsang, B.; Vander Molen, A.; Verde, G.; Wallace, M.; Youngs, M.

    2008-04-01

    Dynamical and thermal properties of excited nuclear system produced during heavy ion collisions at intermediate incident energies can be studied by means of the intensity interferometry, which when applied to both charged particles (light charged particles and intermediate mass fragments) provide information about space-time properties of nuclear reactions. The shape of 2-particle correlation functions reflects the nature of the final state interaction and possible presence of a collective motion driven by the nuclear EoS. BUU simulations predict that the symmetry term of the EoS will affect the 2-proton correlation function, reflecting a more pronounced pre-equilibrium emission and shorter emission times when stiffer density dependence of the symmetry term is assumed. We will present preliminary results on the isospin effect on the 2-proton correlations measured in reactions ^40,48Ca+^40,48Ca at 80A MeV. The experiment was performed at the NSCL/MSU using High Resolution Array (HiRA) in coincidence with the 4pi array. This work is supported by the National Science Foundation under Grant Nos. PHY-0606007 and PHY-9977707.

  7. 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.

  8. Light stops, blind spots, and isospin violation in the MSSM

    NASA Astrophysics Data System (ADS)

    Crivellin, Andreas; Hoferichter, Martin; Procura, Massimiliano; Tunstall, Lewis C.

    2015-07-01

    In the framework of the MSSM, we examine several simplified models where only a few superpartners are light. This allows us to study WIMP-nucleus scattering in terms of a handful of MSSM parameters and thereby scrutinize their impact on dark matter direct-detection experiments. Focusing on spin-independent WIMP-nucleon scattering, we derive simplified, analytic expressions for the Wilson coefficients associated with Higgs and squark exchange. We utilize these results to study the complementarity of constraints due to direct-detection, flavor, and collider experiments. We also identify parameter configurations that produce (almost) vanishing cross sections. In the proximity of these so-called blind spots, we find that the amount of isospin violation may be much larger than typically expected in the MSSM. This feature is a generic property of parameter regions where cross sections are suppressed, and highlights the importance of a careful analysis of the nucleon matrix elements and the associated hadronic uncertainties. This becomes especially relevant once the increased sensitivity of future direct-detection experiments corners the MSSM into these regions of parameter space.

  9. 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.

  10. 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.

  11. 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

  12. 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. PMID:27152959

  13. Single-proton resonant states and the isospin dependence investigated by Green’s function relativistic mean field theory

    NASA Astrophysics Data System (ADS)

    Sun, T. T.; Niu, Z. M.; Zhang, S. Q.

    2016-08-01

    The relativistic mean field theory formulated with Green’s function method (RMF-GF) is applied to investigate single-proton resonant states and isospin dependence. The calculated energies and widths for the single-proton resonant states in {}120{{Sn}} are in good agreement with previous investigations. The single-proton resonant states of the Sn isotopes and the N = 82 isotones are systematically studied and it is shown that the calculated energies and widths decrease monotonically with the increase of neutron number while increase monotonically with the increase of proton number. To further examine the evolutions of the single-proton resonant states, their dependence on the depth, radius and diffuseness of nuclear potential is investigated with the help of an analytic Woods-Saxon potential, and it is found that the increase of radius plays the most important role in the cross phenomenon appearing in the single-proton resonant states of the Sn isotopes.

  14. Screening of potential cancer preventing chemicals for induction of glutathione in rat liver cells.

    PubMed

    White, E L; Ross, L J; Schmid, S M; Kelloff, G J; Steele, V E; Hill, D L

    1998-01-01

    With BRL 3A hepatocytes, a series of selected, potentially chemopreventive chemicals was evaluated for their capacity to elevate glutathione (GSH) levels. Since sodium selenite consistently increased GSH levels by approximately 70%, it was selected as a positive control. Of 62 test chemicals, eighteen stimulated GSH levels by >30%, but eleven of these had only a modest effect or displayed considerable toxicity. At non-toxic concentrations, seven compounds had substantial activity: black tea extract (decaffeinated), trans-chalcone, N-ethyl-9-cis-retinamide, indole-3-carbinol, dehydroepiandrosterone (DHEA) curcumin and N-(4-carboxyphenyl)retinamide. These should be considered for further development as cancer preventive agents. PMID:9468590

  15. Quark-mass dependence of the three-flavor QCD phase diagram at zero and imaginary chemical potential: Model prediction

    SciTech Connect

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

    2011-11-01

    We draw the three-flavor phase diagram as a function of light- and strange-quark masses for both zero and imaginary quark-number chemical potential, using the Polyakov-loop extended Nambu-Jona-Lasinio model with an effective four-quark vertex depending on the Polyakov loop. The model prediction is qualitatively consistent with 2+1 flavor lattice QCD prediction at zero chemical potential and with degenerate three-flavor lattice QCD prediction at imaginary chemical potential.

  16. 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

    2014-04-01

    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. PMID:24615801

  17. Calculating excess chemical potentials using dynamic simulations in the fourth dimension

    SciTech Connect

    Pomes, R.; Eisenmesser, E.; Post, C.B.; Roux, B.

    1999-08-01

    A general method for computing excess chemical potentials is presented. The excess chemical potential of a solute or ligand molecule is estimated from the potential of mean-force (PMF) calculated along a nonphysical fourth spatial dimension, {ital w}, into which the molecule is gradually inserted or from which it is gradually abstracted. According to this {open_quotes}4D-PMF{close_quotes} (four dimensional) scheme, the free energy difference between two limiting states defines the excess chemical potential: At w={plus_minus}{infinity}, the molecule is not interacting with the rest of the system, whereas at w=0, it is fully interacting. Use of a fourth dimension avoids the numerical instability in the equations of motion encountered upon growing or shrinking solute atoms in conventional free energy perturbation simulations performed in three dimensions, while benefiting from the efficient sampling of configurational space afforded by PMF calculations. The applicability and usefulness of the method are illustrated with calculations of the hydration free energy of simple Lennard-Jones (LJ) solutes, a water molecule, and camphor, using molecular dynamics simulations and umbrella sampling. Physical insight into the nature of the PMF profiles is gained from a continuum treatment of short- and long-range interactions. The short-range barrier for dissolution of a LJ solute in the added dimension provides an apparent surface tension of the solute. An approximation to the long-range behavior of the PMF profiles is made in terms of a continuum treatment of LJ dispersion and electrostatic interactions. Such an analysis saves the need for configurational sampling in the long-range limit of the fourth dimension. The 4D-PMF method of calculating excess chemical potentials should be useful for neutral solute and ligand molecules with a wide range of sizes, shapes, and polarities. {copyright} {ital 1999 American Institute of Physics.}

  18. 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. PMID:26174569

  19. Self-Consistent Green Function Calculations for Isospin Asymmetric Nuclear Matter

    NASA Astrophysics Data System (ADS)

    Mansour, H.; Gad, K.; Hassaneen, K. S. A.

    2010-04-01

    The one-body potentials for protons and neutrons are obtained from the self-consistent Green-function calculations of asymmetric nuclear matter, in particular their dependence on the degree of proton/neutron asymmetry. Results of the binding energy per nucleon as a function of the density and asymmetry parameter are presented for the self-consistent Green function approach using the CD-Bonn potential. For the sake of comparison, the same calculations are performed using the Brueckner-Hartree-Fock approximation. The contribution of the hole-hole terms leads to a repulsive contribution to the energy per nucleon which increases with the nuclear density. The incompressibility for asymmetric nuclear matter has been also investigated in the framework of the self-consistent Green-function approach using the CD-Bonn potential. The behavior of the incompressibility is studied for different values of the nuclear density and the neutron excess parameter. The nuclear symmetry potentia l at fixed nuclear density is also calculated and its value decreases with increasing the nucleon energy. In particular, the nuclear symmetry potential at saturation density changes from positive to negative values at nucleon kinetic energy of about 200 MeV. For the sake of comparison, the same calculations are performed using the Brueckner-Hartree-Fock approximation. The proton/neutron effective mass splitting in neutron-rich matter has been studied. The predicted isospin splitting of the proton/neutron effective mass splitting in neutron-rich matter is such that m(*_n) ≥ m(*_p) .

  20. 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

  1. Nonlocal Polyakov-Nambu-Jona-Lasinio model and imaginary chemical potential

    NASA Astrophysics Data System (ADS)

    Kashiwa, Kouji; Hell, Thomas; Weise, Wolfram

    2011-09-01

    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 (μI) and compared with available Nf=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 μI, such as the Roberge-Weiss (RW) periodicity and the RW transition. Chiral and deconfinement transition temperatures for Nf=2 turn out to coincide both at zero chemical potential and at finite μI. Detailed studies are performed concerning the RW endpoint and its neighborhood where a first-order transition occurs.

  2. Distortion of surface plasmon polariton propagation on graphene due to chemical potential variation

    NASA Astrophysics Data System (ADS)

    Amanatiadis, Stamatios; Kantartzis, Nikolaos

    2016-04-01

    The variation of graphene chemical potential owing to surface plasmon polariton excitation and its influence on the propagation properties of the latter is systematically examined in this paper. Although the chemical potential is controlled via a constant electric field bias, the excitation of the highly confined surface wave can considerably affect it, thus disrupting the wave natural propagation. To this aim, the propagation properties of the surface wave are extracted to reliably estimate the aforesaid distortion effect with regard to frequency. Numerical results, obtained in terms of an accurate finite-difference time-domain scheme, certify this interesting convention. Furthermore, the electrodynamic forces on the free electrons of the graphene layer are calculated to justify the electrostatic assumption.

  3. Chiral random matrix model at finite chemical potential: Characteristic determinant and edge universality

    NASA Astrophysics Data System (ADS)

    Liu, Yizhuang; Nowak, Maciej A.; Zahed, Ismail

    2016-08-01

    We derive an exact formula for the stochastic evolution of the characteristic determinant of a class of deformed Wishart matrices following from a chiral random matrix model of QCD at finite chemical potential. In the WKB approximation, the characteristic determinant describes a sharp droplet of eigenvalues that deforms and expands at large stochastic times. Beyond the WKB limit, the edges of the droplet are fuzzy and described by universal edge functions. At the chiral point, the characteristic determinant in the microscopic limit is universal. Remarkably, the physical chiral condensate at finite chemical potential may be extracted from current and quenched lattice Dirac spectra using the universal edge scaling laws, without having to solve the QCD sign problem.

  4. 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

    2014-11-01

    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

  5. A consistent calculation of the chemical potential for dense simple fluids.

    PubMed

    Bomont, Jean-Marc

    2006-05-28

    A general method to calculate the excess chemical potential betamuex, that is based on the Kirkwood coupling parameter's dependence of the correlation functions, is presented. The expression for the one particle bridge function B(1)r is derived for simple fluids with spherical interactions. Only the knowledge of the bridge function B(2)r is required. The accuracy of our approach is illustrated for a dense hard sphere fluid. As far as B(2)r is considered as exact, B(1)r is found to be, at high densities, the normalized bridge function -B(2)rB(2)(r=0). This expression ensures a consistent calculation of the excess chemical potential by satisfying implicitly the Gibbs-Duhem constraint. Only the pressure-consistency condition is necessary to calculate the structural and thermodynamic properties of the fluid. PMID:16774388

  6. 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.

  7. The hapten-atopy hypothesis III: the potential role of airborne chemicals.

    PubMed

    McFadden, J P; Basketter, D A; Dearman, R J; Puangpet, P; Kimber, I

    2014-01-01

    One explanation for the large increase in the prevalence of atopic disease in developed countries during the last 50 years is the 'hygiene hypothesis'. This proposes that a reduced exposure to pathogenic microorganisms at a key period(s) during development results in the maintenance or acquisition of an atopic phenotype. Alternatively, or additionally, we have postulated that increased exposure to chemicals generally, and to irritant/haptenic chemicals in particular, during critical windows of maternal pregnancy/early life have also contributed to changes in the prevalence of atopic disease. Having previously reviewed the potential roles of oral and cutaneous exposure to chemicals on the subsequent diagnosis of atopic disease, we here consider possible evidence of a role for exposure to airborne chemicals as a contributory factor in acquired susceptibility to atopic allergy. After controlling for known confounders, five specific maternal occupations during pregnancy have been implicated as being associated with subsequent atopic disease in the offspring. Each of these occupations is characterized by high and persistent exposure to airborne chemicals. High-level exposure to volatile organic compounds in the domestic environment, either during pregnancy or in early life, is also associated with development of childhood atopic disease. Similarly, sustained exposure to airborne chlorinated chemicals from swimming pools during childhood has been associated with the development of atopic allergy. A possible immunological basis for these associations is that exposure to certain airborne chemicals, even at low levels, can result in the delivery of 'danger' signals that, in turn, bias the immune response towards the selective induction or maintenance of preferential T helper 2-type immune responses consistent with the acquisition of allergic sensitization. PMID:23980877

  8. 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.

  9. 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.

  10. Typology of exogenous organic matters based on chemical and biochemical composition to predict potential nitrogen mineralization.

    PubMed

    Lashermes, G; Nicolardot, B; Parnaudeau, V; Thuriès, L; Chaussod, R; Guillotin, M L; Linères, M; Mary, B; Metzger, L; Morvan, T; Tricaud, A; Villette, C; Houot, S

    2010-01-01

    Our aim was to develop a typology predicting potential N availability of exogenous organic matters (EOMs) in soil based on their chemical characteristics. A database of 273 EOMs was constructed including analytical data of biochemical fractionation, organic C and N, and results of N mineralization during incubation of soil-EOM mixtures in controlled conditions. Multiple factor analysis and hierarchical classification were performed to gather EOMs with similar composition and N mineralization behavior. A typology was then defined using composition criteria to predict potential N mineralization. Six classes of EOM potential N mineralization in soil were defined, from high potential N mineralization to risk of inducing N immobilization in soil after application. These classes were defined on the basis of EOM organic N content and soluble, cellulose-, and lignin-like fractions. A decision tree based on these variables was constructed in order to easily attribute any EOM to 1 of the 6 classes. PMID:19726180

  11. 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. PMID:27327881

  12. Direct detection of spin chemical potential shift through spin filtering effect

    NASA Astrophysics Data System (ADS)

    Miao, Guoxing; Moodera, Jagadeesh

    2010-03-01

    Spin filtering (SF) effect is a unique way to generate highly spin-polarized tunnel currents from nonmagnetic electrodes. Magnetic tunnel junctions based on pure SF effect have been realized recently [1] as a clear demonstration of principle for the spin manipulation through SF effect. The next challenge is the readout of spin information. In this work, we present the direct detection of the spin chemical potential shift in an Al nano cluster sandwiched between two SF EuS tunnel barriers. The spin channels are split by depositing Al directly onto EuS, and the indirect exchange interaction between the Al conduction electrons and the localized Eu 4f electrons gives rise to an effective Zeeman splitting with the strength of a few mV. EuS on the readout side is isolated from the Al clusters with a natural Al2O3 barrier. In a vertical measurement geometry with no transport current, we directly detected the spin dependent voltage levels by aligning the detection SF barrier parallel or antiparallel to the first SF barrier, corresponding to the equilibrium up- and down-spin chemical potentials. A simple analysis treating the barriers as a set of resistors revealed that the observed voltage difference is the actual chemical potential shift modulated by the SF efficiency.[4pt] [1] G.X. Miao, M. Muller, J.S. Moodera,PRL102,076601(2009)

  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. 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. PMID:26436822

  15. 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.

  16. Branching ratio measurements and isospin violation in B-meson decays

    NASA Astrophysics Data System (ADS)

    Jung, Martin

    2016-02-01

    The approximate symmetry of the strong interactions under isospin transformations is among the most precise tools available to control hadronic matrix elements. It is crucial in extracting fundamental parameters, but also provides avenues for the search of phenomena beyond the Standard Model. The precision of the resulting predictions requires special care when determining the quantities they are to be tested with. Specifically, in the extraction of branching ratios often isospin symmetry is assumed at one point or another implicitly, implying a significant bias for precision analyses. We extract a bias-free value for the production asymmetry between charged and neutral B meson pairs at B factories and discuss its consequences for the determination of branching fractions generally, and isospin-violating observables like the rate asymmetries in B → J / ψK or B →K* γ decays specifically.

  17. Isospin splitting of nucleon effective mass and shear viscosity of nuclear matter

    NASA Astrophysics Data System (ADS)

    Xu, Jun

    2015-03-01

    Based on an improved isospin- and momentum-dependent interaction, I have studied the qualitative effect of isospin splitting of nucleon effective mass on the specific shear viscosity of neutron-rich nuclear matter from a relaxation time approach. It is seen that for mn>mp , the relaxation time of neutrons is smaller, and the neutron flux between flow layers is weaker, leading to a smaller specific shear viscosity of neutron-rich matter compared to the case for mnisospin asymmetries, but it does not affect the behavior of the specific shear viscosity much near nuclear liquid-gas phase transition.

  18. 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

  19. 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

  20. Benefit of heat acclimation is limited by the evaporative potential when wearing chemical protective clothing.

    PubMed

    Chang, S K; Gonzalez, R R

    1999-08-01

    Heat acclimation-induced sweating responses have the potential of reducing heat strain for chemical protective garment wearers. However, this potential benefit is strongly affected by the properties of the garment. If the clothing ensemble permits sufficient evaporative heat dissipation, then heat acclimation becomes helpful in reducing heat strain. On the other hand, if the garment creates an impenetrable barrier to moisture, no benefit can be gained from heat acclimation as the additional sweating cannot be evaporated. Ten subjects were studied exercising on a treadmill while wearing two different chemical protective ensembles. Skin heat flux, skin temperature, core temperature, metabolic heat production and heart rate were measured. It was found that the benefit of heat acclimation is strongly dependent on the ability of the body to dissipate an adequate amount of heat evaporatively. The evaporative potential (EP), a measure of thermal insulation modified by moisture permeability, of the clothing ensemble offers a quantitative index useful to determine, a priori, whether heat acclimation would be helpful when wearing protective clothing system. The data show that when EP is < 15%, heat acclimation affords no benefit. An evaporative potential graph is created to aid in this determination. PMID:10504888

  1. 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.

  2. 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. PMID:7570659

  3. 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

  4. Direct computation of general chemical energy differences: Application to ionization potentials, excitation, and bond energies

    SciTech Connect

    Beste, Ariana; Harrison, Robert J; Yanai, Takeshi

    2006-01-01

    Chemists are mainly interested in energy differences. In contrast, most quantum chemical methods yield the total energy which is a large number compared to the difference and has therefore to be computed to a higher relative precision than would be necessary for the difference alone. Hence, it is desirable to compute energy differences directly, thereby avoiding the precision problem. Whenever it is possible to find a parameter which transforms smoothly from an initial to a final state, the energy difference can be obtained by integrating the energy derivative with respect to that parameter (c.f., thermodynamic integration or adiabatic connection methods). If the dependence on the parameter is predominantly linear, accurate results can be obtained by single-point integration. In density functional theory (DFT) and Hartree-Fock, we applied the formalism to ionization potentials, excitation energies, and chemical bond breaking. Example calculations for ionization potentials and excitation energies showed that accurate results could be obtained with a linear estimate. For breaking bonds, we introduce a non-geometrical parameter which gradually turns the interaction between two fragments of a molecule on. The interaction changes the potentials used to determine the orbitals as well as constraining the orbitals to be orthogonal.

  5. Local chemical potentials and pressures in heterogeneous systems: Adsorptive, absorptive, interfaces

    NASA Astrophysics Data System (ADS)

    Tovbin, Yu. K.

    2016-07-01

    Equations self-consistently describing chemical and mechanical equilibria in heterogeneous systems are derived. The equations are based on the lattice gas model using discrete distributions of molecules in space (on a scale comparable to molecular size) and continuum distributions of molecules (at short distances inside the cells) during their translational and vibrational motions. It is shown that the theory provides a unified description of the equilibrium distributions of molecules in three aggregate states and at their interfaces. Potential functions of intermolecular interactions (such as Mie pair potentials) in several coordination spheres that determine the compressibility of the lattice structure are considered. For simplicity, it is assumed that differences between the sizes of mixture components are small. Expressions for the local components of the pressure tensor inside multicomponent solid phases and heterogeneous systems (adsorptive, absorptive, and interfaces) are obtained. It is established that they can be used to calculate the lattice parameters of deforming phases and the thermodynamic characteristics of interfaces, including surface tension. The tensor nature of the chemical potential in heterogeneous systems is discussed.

  6. Direct computation of general chemical energy differences: Application to ionization potentials, excitation, and bond energies

    NASA Astrophysics Data System (ADS)

    Beste, A.; Harrison, R. J.; Yanai, T.

    2006-08-01

    Chemists are mainly interested in energy differences. In contrast, most quantum chemical methods yield the total energy which is a large number compared to the difference and has therefore to be computed to a higher relative precision than would be necessary for the difference alone. Hence, it is desirable to compute energy differences directly, thereby avoiding the precision problem. Whenever it is possible to find a parameter which transforms smoothly from an initial to a final state, the energy difference can be obtained by integrating the energy derivative with respect to that parameter (cf. thermodynamic integration or adiabatic connection methods). If the dependence on the parameter is predominantly linear, accurate results can be obtained by single-point integration. In density functional theory and Hartree-Fock, we applied the formalism to ionization potentials, excitation energies, and chemical bond breaking. Example calculations for ionization potentials and excitation energies showed that accurate results could be obtained with a linear estimate. For breaking bonds, we introduce a nongeometrical parameter which gradually turns the interaction between two fragments of a molecule on. The interaction changes the potentials used to determine the orbitals as well as the constraint on the orbitals to be orthogonal.

  7. 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. PMID:26476195

  8. Antioxidant Potential of Fagonia arabica against the Chemical Ischemia-Induced in PC12 Cells.

    PubMed

    Satpute, Ravindra; Bhattacharya, Rahul; S Kashyap, Rajpal; J Purohit, Hemant; Y Deopujari, Jayant; M Taori, Girdhar; F Daginawala, Hatim

    2012-01-01

    The imbalance between pro-oxidants and anti-oxidants leads to generation of oxygen/nitrogen free radicals which are implicated in several neurodegenerative diseases. Fagonia arabica is an ethno-pharmacologically important Ayurvedic herb known to have many medicinal properties like anti-inflammatory, analgesic and antipyretic effects. However, its antioxidant potential has not been investigated so far. The present study was designed to investigate the antioxidant potential of F. arabica and its neuroprotective effect on chemical ischemia induced in PC12 cells. Chemical ischemia was induced through exposing the cells to uncoupler of oxidative phosphorylation sodium azide (5.0 mM) and competitive inhibitor of glycolysis 2-deoxy-glucose (2.0 mM) for 2 h followed by 24 h reperfusion with normal culture medium. Total polyphenolic content (TPC) and antioxidant potential of the herb was measured using DPPH and ABTS•+ scavenging and ferric ion reducing antioxidant potential (FRAP) assays; its effect on neuroprotection and energy metabolism was also studied. The ischemic injury was characterized by impaired energy status as indicated by decreased ATP levels in the cells, accompanied by increased lactic acid content. Both the changes favourably responded to F. arabica and offered considerable neuroprotection from ischemia and helped to maintain the cellular viability and mitochondrial integrity of the cells. F. arabica showed considerable amount of TPC and antioxidant activity. This study reveals the antioxidant potential of F. arabica and its protective efficacy against ischemia/reperfusion mediated cell death. F. arabica thus can be considered for further studies for the development of the prophylactic or therapeutic agent for the treatment of ischemic stroke. PMID:24250453

  9. Antioxidant Potential of Fagonia arabica against the Chemical Ischemia-Induced in PC12 Cells

    PubMed Central

    Satpute, Ravindra; Bhattacharya, Rahul; S Kashyap, Rajpal; J Purohit, Hemant; Y Deopujari, Jayant; M Taori, Girdhar; F. Daginawala, Hatim

    2012-01-01

    The imbalance between pro-oxidants and anti-oxidants leads to generation of oxygen/nitrogen free radicals which are implicated in several neurodegenerative diseases. Fagonia arabica is an ethno-pharmacologically important Ayurvedic herb known to have many medicinal properties like anti-inflammatory, analgesic and antipyretic effects. However, its antioxidant potential has not been investigated so far. The present study was designed to investigate the antioxidant potential of F. arabica and its neuroprotective effect on chemical ischemia induced in PC12 cells. Chemical ischemia was induced through exposing the cells to uncoupler of oxidative phosphorylation sodium azide (5.0 mM) and competitive inhibitor of glycolysis 2-deoxy-glucose (2.0 mM) for 2 h followed by 24 h reperfusion with normal culture medium. Total polyphenolic content (TPC) and antioxidant potential of the herb was measured using DPPH and ABTS•+ scavenging and ferric ion reducing antioxidant potential (FRAP) assays; its effect on neuroprotection and energy metabolism was also studied. The ischemic injury was characterized by impaired energy status as indicated by decreased ATP levels in the cells, accompanied by increased lactic acid content. Both the changes favourably responded to F. arabica and offered considerable neuroprotection from ischemia and helped to maintain the cellular viability and mitochondrial integrity of the cells. F. arabica showed considerable amount of TPC and antioxidant activity. This study reveals the antioxidant potential of F. arabica and its protective efficacy against ischemia/reperfusion mediated cell death. F. arabica thus can be considered for further studies for the development of the prophylactic or therapeutic agent for the treatment of ischemic stroke. PMID:24250453

  10. 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

  11. Polyakov loop extended Nambu Jona-Lasinio model with imaginary chemical potential

    NASA Astrophysics Data System (ADS)

    Sakai, Yuji; Kashiwa, Kouji; Kouno, Hiroaki; Yahiro, Masanobu

    2008-03-01

    The Polyakov loop extended Nambu Jona-Lasinio (PNJL) model with imaginary chemical potential is studied. The model possesses the extended Z3 symmetry that QCD does. Quantities invariant under the extended Z3 symmetry, such as the partition function, the chiral condensate, and the modified Polyakov loop, have Roberge-Weiss periodicity. The phase diagram of confinement/deconfinement transition derived with the PNJL model is consistent with the Roberge-Weiss prediction on it and the results of lattice QCD. The phase diagram of chiral transition is also presented by the PNJL model.

  12. On criticality and the equation of state of QCD at finite chemical potential

    NASA Astrophysics Data System (ADS)

    Gupta, Sourendu; Karthik, Nikhil; Majumdar, Pushan

    2014-08-01

    We obtain the baryon number density, n, and the excess contribution to the pressure, ΔP, at finite chemical potential, μB, and temperature, T, by resumming the Taylor series expansion in a lattice computation with lattice spacing of 1/(4T) and two flavors of quarks at three different quark masses. The method proceeds by giving a critical μB and limits on the critical exponent, and permits reliable estimations of the errors in resummed quantities. We find that n and ΔP are insensitive to the quark mass. We also report the bulk isothermal compressibility, κ, over a range of T and μB.

  13. Polyakov loop extended Nambu-Jona-Lasinio model with imaginary chemical potential

    SciTech Connect

    Sakai, Yuji; Kashiwa, Kouji; Yahiro, Masanobu; Kouno, Hiroaki

    2008-03-01

    The Polyakov loop extended Nambu-Jona-Lasinio (PNJL) model with imaginary chemical potential is studied. The model possesses the extended Z{sub 3} symmetry that QCD does. Quantities invariant under the extended Z{sub 3} symmetry, such as the partition function, the chiral condensate, and the modified Polyakov loop, have Roberge-Weiss periodicity. The phase diagram of confinement/deconfinement transition derived with the PNJL model is consistent with the Roberge-Weiss prediction on it and the results of lattice QCD. The phase diagram of chiral transition is also presented by the PNJL model.

  14. 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.

  15. Chiral phase transition with a chiral chemical potential in the framework of Dyson-Schwinger equations

    NASA Astrophysics Data System (ADS)

    Xu, Shu-Sheng; Cui, Zhu-Fang; Wang, Bin; Shi, Yuan-Mei; Yang, You-Chang; Zong, Hong-Shi

    2015-03-01

    Within the framework of Dyson-Schwinger equations , we discuss the chiral phase transition of QCD with a chiral chemical potential μ5 as an additional scale. We focus especially on the issues related to the widely accepted as well as interesting critical end point (CEP). With the help of a scalar susceptibility, we find that there might be no CEP5 in the T -μ5 plane, and the phase transition in the T -μ5 plane might be totally crossover when μ <50 MeV , which has apparent consistency with the lattice QCD calculation. Our study may also provide some useful hints to some other studies related to μ5.

  16. Phase structure of two-flavor QCD at finite chemical potential.

    PubMed

    Braun, Jens; Haas, Lisa M; Marhauser, Florian; Pawlowski, Jan M

    2011-01-14

    We study the phase diagram of two-flavor QCD at imaginary chemical potentials in the chiral limit. To this end we compute order parameters for chiral symmetry breaking and quark confinement. The interrelation of quark confinement and chiral symmetry breaking is analyzed with a new order parameter for the confinement phase transition. We show that it is directly related to both the quark density as well as the Polyakov loop expectation value. Our analytical and numerical results suggest a close relation between the chiral and the confinement phase transition. PMID:21405221

  17. 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

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

    NASA Astrophysics Data System (ADS)

    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.

  19. 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

    2016-01-01

    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/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. PMID:26725369

  20. 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. PMID:24827207

  1. 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.

  2. Mechanism of Isospin Equilibration in Semi-Peripheral Heavy Ion Reactions

    NASA Astrophysics Data System (ADS)

    Zielinska-Pfabe, Malgorzata

    2006-04-01

    The BUU formalism with the inclusion of fluctuations was used to study a mechanism of isospin equilibration in semi-peripheral collisions of heavy ions close to the Fermi energy. In order to investigate the density dependence of the asymmetry term in the nuclear equation of state (i.e. the asy-stiffness of the equation of state) the calculations with different parametrization of this term were performed. It has been found that the low density interface between the interacting nuclei which develops in semi-peripheral collisions plays an important role in controlling the currents of neutrons and protons. The isospin transport is affected by an interplay between drift and diffusion being driven by differences in N/Z ratio and by density gradients. Both, the drift and the diffusion are sensitive to the asy-stiffness of the nuclear equation of state. A study of the isospin transport ratio shows that the experiment seems to favor a more asy-stiff equation of state and that a more asy-soft equation leads to a larger isospin equilibration. We may conclude that the charge equilibration measurements for semi-peripheral collisions provide an effective tool to investigate the properties of asymmetric nuclear matter. In collaboration with Massimo Di Toro, Maria Colonna, and Virgil Baran, LNS, Catania, Italy; and Hermann Wolter, University of Munich, Munich, Germany.

  3. Effects of isospin dynamics on neck fragmentation in isotopic nuclear reactions

    NASA Astrophysics Data System (ADS)

    Feng, Zhao-Qing

    2016-07-01

    The neck dynamics in Fermi-energy heavy-ion collisions, to probe the nuclear symmetry energy in the domain of subsaturation densities, is investigated within an isospin-dependent transport model. The single and double ratios of neutrons to protons from free nucleons and light clusters (complex particles) in the isotopic reactions are analyzed systematically. Isospin effects of particles produced from the neck fragmentations are explored. It is found that the ratios of the energetic isospin particles strongly depend on the stiffness of the nuclear symmetry energy and the effects increase with softening of the symmetry energy, which would be a nice probe for extracting the symmetry energy below the normal density in experiments. A flat structure appears at the tail spectra from the double ratio distributions. The neutron to proton ratio of light intermediate-mass fragments with charge number Z ≤8 is related to the density dependence of the symmetry energy with less sensitivity in comparison to the isospin ratios of nucleons and light particles.

  4. Chemical Self-Doping of Organic Nanoribbons for High Conductivity and Potential Application as Chemiresistive Sensor.

    PubMed

    Wu, Na; Wang, Chen; Bunes, Benjamin R; Zhang, Yaqiong; Slattum, Paul M; Yang, Xiaomei; Zang, Ling

    2016-05-18

    Intrinsically low electrical conductivity of organic semiconductors hinders their further development into practical electronic devices. Herein, we report on an efficient chemical self-doping to increase the conductivity through one-dimensional stacking arrangement of electron donor-acceptor (D-A) molecules. The D-A molecule employed was a 1-methylpiperidine-substituted perylene tetracarboxylic diimide (MP-PTCDI), of which the methylpiperidine moiety is a strong electron donor, and can form a charge transfer complex with PTCDI (acting as the acceptor), generating anionic radical of PTCDI as evidenced in molecular solutions. Upon self-assembling into nanoribbons through columnar π-π stacking, the intermolecular charge transfer interaction between methylpiperidine and PTCDI would be enhanced, and the electrons generated are delocalized along the π-π stacking of PTCDIs, leading to enhancement in conductivity. The conductive fiber materials thus produced can potentially be used as chemiresistive sensor for vapor detection of electron deficient chemicals such as hydrogen peroxide, taking advantage of the large surface area of nanofibers. As a major component of improvised explosives, hydrogen peroxide remains a critical signature chemical for public safety screening and monitoring. PMID:27136452

  5. The limits of local correlation theory: electronic delocalization and chemically smooth potential energy surfaces.

    PubMed

    Subotnik, Joseph E; Sodt, Alex; Head-Gordon, Martin

    2008-01-21

    Local coupled-cluster theory provides an algorithm for measuring electronic correlation quickly, using only the spatial locality of localized electronic orbitals. Previously, we showed [J. Subotnik et al., J. Chem. Phys. 125, 074116 (2006)] that one may construct a local coupled-cluster singles-doubles theory which (i) yields smooth potential energy surfaces and (ii) achieves near linear scaling. That theory selected which orbitals to correlate based only on the distances between the centers of different, localized orbitals, and the approximate potential energy surfaces were characterized as smooth using only visual identification. This paper now extends our previous algorithm in three important ways. First, locality is now based on both the distances between the centers of orbitals as well as the spatial extent of the orbitals. We find that, by accounting for the spatial extent of a delocalized orbital, one can account for electronic correlation in systems with some electronic delocalization using fast correlation methods designed around orbital locality. Second, we now enforce locality on not just the amplitudes (which measure the exact electron-electron correlation), but also on the two-electron integrals themselves (which measure the bare electron-electron interaction). Our conclusion is that we can bump integrals as well as amplitudes, thereby gaining a tremendous increase in speed and paradoxically increasing the accuracy of our LCCSD approach. Third and finally, we now make a rigorous definition of chemical smoothness as requiring that potential energy surfaces not support artificial maxima, minima, or inflection points. By looking at first and second derivatives from finite difference techniques, we demonstrate complete chemical smoothness of our potential energy surfaces (bumping both amplitudes and integrals). These results are significant both from a theoretical and from a computationally practical point of view. PMID:18205484

  6. 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

  7. 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. PMID:25907139

  8. Pressure and Chemical Potential: Effects Hydrophilic Soils Have on Adsorption and Transport

    NASA Astrophysics Data System (ADS)

    Bennethum, L. S.; Weinstein, T.

    2003-12-01

    Using the assumption that thermodynamic properties of fluid is affected by its proximity to the solid phase, a theoretical model has been developed based on upscaling and fundamental thermodynamic principles (termed Hybrid Mixture Theory). The theory indicates that Darcy's law and the Darcy-scale chemical potential (which determines the rate of adsorption and diffusion) need to be modified in order to apply to soils containing hydrophilic soils. In this talk we examine the Darcy-scale definition of pressure and chemical potential, especially as it applies to hydrophilic soils. To arrive at our model, we used hybrid mixture theory - first pioneered by Hassanizadeh and Gray in 1979. The technique involves averaging the field equations (i.e. conservation of mass, momentum balance, energy balance, etc.) to obtain macroscopic field equations, where each field variable is defined precisely in terms of its microscale counterpart. To close the system consistently with classical thermodynamics, the entropy inequality is exploited in the sense of Coleman and Noll. With the exceptions that the macroscale field variables are defined precisely in terms of their microscale counterparts and that microscopic interfacial equations can also be treated in a similar manner, the resulting system of equations is consistent with those derived using classical mixture theory. Hence the terminology, Hybrid Mixture Theory.

  9. Two-photon absorption in gapped bilayer graphene with a tunable chemical potential.

    PubMed

    Brinkley, M K; Abergel, D S L; Clader, B D

    2016-09-14

    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. PMID:27392275

  10. Nf=2 QCD chiral phase transition with Wilson fermions at zero and imaginary chemical potential

    NASA Astrophysics Data System (ADS)

    Philipsen, Owe; Pinke, Christopher

    2016-06-01

    The order of the thermal phase transition in the chiral limit of quantum chromodynamics (QCD) with two dynamical flavors of quarks is a long-standing issue and still not known in the continuum limit. Whether the transition is first or second order has important implications for the QCD phase diagram and the existence of a critical end point at finite densities. We follow a recently proposed approach to explicitly determine the region of first order chiral transitions at imaginary chemical potential, where it is large enough to be simulated, and extrapolate it to zero chemical potential with known critical exponents. Using unimproved Wilson fermions on coarse Nt=4 lattices, the first order region turns out to be so large that no extrapolation is necessary. The critical pion mass mπc≈560 MeV is by nearly a factor 10 larger than the corresponding one using staggered fermions. Our results are in line with investigations of three-flavor QCD using improved Wilson fermions and indicate that the systematic error on the two-flavor chiral transition is still of order 100%.

  11. Calculation of free energies and chemical potentials for gas hydrates using Monte Carlo simulations.

    PubMed

    Wierzchowski, S J; Monson, P A

    2007-06-28

    We describe a method for calculating free energies and chemical potentials for molecular models of gas hydrate systems using Monte Carlo simulations. The method has two components: (i) thermodynamic integration to obtain the water and guest molecule chemical potentials as functions of the hydrate occupancy; (ii) calculation of the free energy of the zero-occupancy hydrate system using thermodynamic integration from an Einstein crystal reference state. The approach is applicable to any classical molecular model of a hydrate. We illustrate the methodology with an application to the structure-I methane hydrate using two molecular models. Results from the method are also used to assess approximations in the van der Waals-Platteeuw theory and some of its extensions. It is shown that the success of the van der Waals-Platteeuw theory is in part due to a cancellation of the error arising from the assumption of a fixed configuration of water molecules in the hydrate framework with that arising from the neglect of methane-methane interactions. PMID:17530795

  12. Baryon chemical potential and in-medium properties of BPS skyrmions

    NASA Astrophysics Data System (ADS)

    Adam, C.; Klähn, T.; Naya, C.; Sanchez-Guillen, J.; Vazquez, R.; Wereszczynski, A.

    2015-06-01

    We continue the investigation of thermodynamical properties of the Bogomol'nyi-Prasad-Sommerfield (BPS) Skyrme model. In particular, we analytically compute the baryon chemical potential both in the full field theory and in a mean-field approximation. In the full field theory case, we find that the baryon chemical potential is always exactly proportional to the baryon density, for arbitrary solutions. We further find that, in the MF approximation, the BPS Skyrme model approaches the Walecka model in the limit of high density—their thermodynamical functions as well as the equation of state agree in this limit. This fact allows one to read off some properties of the ω meson from the BPS Skyrme action, even though the latter model is entirely based on the (pionic) S U (2 ) Skyrme field. On the other hand, at low densities, at the order of the usual nuclear matter density, the equations of state of the two models are no longer universal, such that a comparison depends on some model details. Still, also the BPS Skyrme model gives rise to nuclear saturation in this regime, leading, in fact, to an exact balance between repulsive and attractive forces. The perfect fluid aspects of the BPS Skyrme model, which, together with its BPS properties, form the base of our results, are shown to be in close formal analogy with the Eulerian formulation of relativistic fluid dynamics. Within this analogy, the BPS Skyrme model, in general, corresponds to a nonbarotropic perfect fluid.

  13. 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.

  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. Predicting physico-chemical properties of polychlorinated diphenyl ethers (PCDEs): potential persistent organic pollutants (POPs).

    PubMed

    Huang, Jun; Yu, Gang; Yang, Xi; Zhang, Zu-lin

    2004-01-01

    Polychlorinated diphenyl ethers (PCDEs) have received more and more concerns as a category of potential persistent organic pollutants (POPs). Modeling its environmental fate and exposure assessment require a number of fundamental physico-chemical properties. However, the experimental data are currently limited due to the difficulty in analysis caused by the complexity of PCDE congeners. As an alternative, the quantitative structure property relationship (QSPR) approach could be used. In this paper, twelve kinds of molecular connectivity indices (MCIs) of all 209 possible molecular structure patterns of PCDEs were calculated. Based on 106 PCDEs with three observed physico-chemical properties-vapour pressure (P0L), aqueous solubility (Sw) and n-octanol/water (Kow) and their MCIs data, a series of QSPR equations were established using multiple linear regression (MLR) method. As a result, three equations with best performance were selected mainly from the view of high regression coefficient (R) and low standard error(SE). All of them showed significant relationship and high accuracy. With these equations the properties of other 103 patterns of PCDEs without the reported observed values were predicted. Furthermore, three partition properties for PCDE congeners-Henry' s Law constants (H), partition coefficients between gas/water (Kgw) and gas/n-octanol (Kgo) were calculated according to the internal relationship among these six properties. These observed and predicted values, in contrast with the criteria listed in the Stockholm treaty about POPs which has been signed by more than ninety countries in May 2001, illustrated that most of PCDEs congeners are potential persistent organic pollutants. As all descriptors/predictors are derived just from the molecular structure itself and without the import of any empirical parameters, this method is impersonal and promising for the estimation of physico-chemical properties of PCDEs. PMID:15137639

  16. 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. PMID:22990136

  17. Divergence of the isospin-asymmetry expansion of the nuclear equation of state in many-body perturbation theory

    NASA Astrophysics Data System (ADS)

    Wellenhofer, Corbinian; Holt, Jeremy W.; Kaiser, Norbert

    2016-05-01

    The isospin-asymmetry dependence of the nuclear-matter equation of state obtained from microscopic chiral two- and three-body interactions in second-order many-body perturbation theory is examined in detail. The quadratic, quartic, and sextic coefficients in the Maclaurin expansion of the free energy per particle of infinite homogeneous nuclear matter with respect to the isospin asymmetry are extracted numerically using finite differences, and the resulting polynomial isospin-asymmetry parametrizations are compared to the full isospin-asymmetry dependence of the free energy. It is found that in the low-temperature and high-density regime where the radius of convergence of the expansion is generically zero, the inclusion of higher-order terms beyond the leading quadratic approximation leads overall to a significantly poorer description of the isospin-asymmetry dependence. In contrast, at high temperatures and densities well below nuclear saturation density, the interaction contributions to the higher-order coefficients are negligible and the deviations from the quadratic approximation are predominantly from the noninteracting term in the many-body perturbation series. Furthermore, we extract the leading logarithmic term in the isospin-asymmetry expansion of the equation of state at zero temperature from the analysis of linear combinations of finite differences. It is shown that the logarithmic term leads to a considerably improved description of the isospin-asymmetry dependence at zero temperature.

  18. Halo structure of 11Li in proton scattering: A folding model description with isospin, density and momentum dependent effective interaction

    NASA Astrophysics Data System (ADS)

    Kanungo, Rituparna; Samanta, C.

    1997-02-01

    Recent 11Li+p elastic scattering data at 62, 68.4, and 75 MeV and inelastic scattering data at 68.4 MeV, taken at RIKEN, are analysed with an isospin, density and momentum dependent finite range effective interaction (SBM) and M3Y interaction in a single folding model. The M3Y folded 11Li+p potentials are found to be almost similar to the folded 9Li+p potentials. But the SBM folded 11Li+p potentials are distinctly different, causing small but significant change in the angular distribution. Folded potentials need appreciable reduction factors indicating possible effects of strong breakup channel coupling. No significant change in results is found if 9Li core + Gaussian two-neutron halo density is used instead of the COSM density of 11Li although the radial extent of the latter is much larger. The angular distribution of the recently discovered excited state at 1.3 MeV, well reproduced by the SBM folded potential, is found to be predominantly dipole in nature.

  19. 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

  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. Endocrine disrupting chemicals as potential risk factor for estrogen-dependent cancers.

    PubMed

    Rutkowska, Aleksandra Z; Szybiak, Aleksandra; Serkies, Krystyna; Rachoń, Dominik

    2016-08-01

    Civilization, industrialization, and urbanization create an environment where humans are continuously exposed to endocrine disrupting chemicals (EDCs). Some of breast cancers and endometrial cancer, which are the most common female malignant neoplasms, are estrogen-dependent tumors. Prolonged exposure to estrogens or substances with estrogenic properties may be a risk factor for their development. This paper aimed to discuss the potential adverse effect of EDCs on human health, including the role of EDCs in hormone-dependent carcinogenesis. A review of literature regarding the sources of environmental exposure to EDCs and molecular mechanisms of their action was performed. We analyzed the possible mechanisms of how these substances alter the function of the endocrine system, resulting in adverse health effects. Hundreds of substances with endocrine disrupting potential have been identified in our environment. There is accumulating evidence linking exposure to EDCs with the development of mammary and endometrial cancer. By interacting with steroid receptors, EDCs can impact the cellular processes potentially leading to carcinogenesis. There are also data showing the effect of EDCs on immune dysfunction. During lifespan, people are usually exposed to a mixture of various EDCs, which complicates the assessment of individual substances or compounds implicated in cancer development. As the prevalence of hormone-dependent tumors among women continues to increase, their successful prevention is of human benefit. Institutions representing medicine, science, industry, and governments should develop joint strategies to decrease exposure to EDC, and thus to reduce the risk of hormonedependent tumors in women. PMID:27509913

  2. [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. PMID:26394465

  3. 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. PMID:12737271

  4. 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.

  5. 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

  6. 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. PMID:26199938

  7. Phase diagram in the imaginary chemical potential region and extended Z3 symmetry

    NASA Astrophysics Data System (ADS)

    Sakai, Yuji; Kashiwa, Kouji; Kouno, Hiroaki; Yahiro, Masanobu

    2008-08-01

    Phase transitions in the imaginary chemical potential region are studied by the Polyakov-loop extended Nambu Jona-Lasinio model that possesses the extended Z3 symmetry. The extended-Z3 invariant quantities such as the partition function, the chiral condensate, and the modified Polyakov loop have the Roberge-Weiss (RW) periodicity. There appear four types of phase transitions: deconfinement, chiral, Polyakov-loop RW, and chiral RW transitions. The orders of the chiral and deconfinement transitions depend on the presence or absence of current quark mass, but those of the Polyakov-loop RW and chiral RW transitions do not. The scalar-type, eight-quark interaction newly added in the model makes the chiral transition line shift to the vicinity of the deconfinement transition line.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Violations of parity and charge conjugation in the {theta} vacuum with imaginary chemical potential

    SciTech Connect

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

    2011-04-01

    Charge conjugation (C) and parity (P) are exact symmetries at {theta}={pi} and {Theta}{identical_to}{mu}/(iT)={pi}, where {theta} is the parameter of the so-called {theta} vacuum, {mu} is the imaginary quark-number chemical potential and T is the temperature. Spontaneous breakings of these discrete symmetries are investigated by the Polyakov-loop extended Nambu-Jona-Lasinio model. At zero T, P symmetry is spontaneously broken while C symmetry is conserved. As T increases, P symmetry is restored just after C symmetry is spontaneously broken, so that either P or C symmetry or both the symmetries are spontaneously broken for any T. The chiral-symmetry restoration and the deconfinement transition at {theta}={Theta}=0 are remnants of the P restoration and the C breaking at {theta}={Theta}={pi}, respectively.

  13. Phase diagram in the imaginary chemical potential region and extended Z{sub 3} symmetry

    SciTech Connect

    Sakai, Yuji; Kashiwa, Kouji; Yahiro, Masanobu; Kouno, Hiroaki

    2008-08-01

    Phase transitions in the imaginary chemical potential region are studied by the Polyakov-loop extended Nambu-Jona-Lasinio model that possesses the extended Z{sub 3} symmetry. The extended-Z{sub 3} invariant quantities such as the partition function, the chiral condensate, and the modified Polyakov loop have the Roberge-Weiss (RW) periodicity. There appear four types of phase transitions: deconfinement, chiral, Polyakov-loop RW, and chiral RW transitions. The orders of the chiral and deconfinement transitions depend on the presence or absence of current quark mass, but those of the Polyakov-loop RW and chiral RW transitions do not. The scalar-type, eight-quark interaction newly added in the model makes the chiral transition line shift to the vicinity of the deconfinement transition line.

  14. Limits and potentials of quantum chemical methods in modelling photosynthetic antennae.

    PubMed

    Jurinovich, Sandro; Viani, Lucas; Curutchet, Carles; Mennucci, Benedetta

    2015-12-14

    Advances in electronic spectroscopies with femtosecond time resolution have provided new information on the excitonic processes taking place during the energy conversion in natural photosynthetic antennae. This has promoted the development of new theoretical protocols aiming at accurately describing the properties and mechanisms of exciton formation and relaxation. In this perspective, we provide an overview of the quantum chemical based approaches, trying to underline both the potentials of the methods and their weaknesses. In particular three main aspects will be analysed, the quantum mechanical description of excitonic parameters (site energies and couplings), the incorporation of environmental effects on these parameters through hybrid quantum/classical approaches, and the modelling of the dynamical coupling among such parameters and the vibrations of the pigment-protein complex. PMID:25865958

  15. Potential for geothermal direct use in the greenhouse, lumber, chemical, and potato and onion processing industries

    SciTech Connect

    Bressler, S.E.

    1980-09-01

    It has generally been assumed that rising energy costs in industries with high energy needs for low-temperature process heat will induce increasingly widespread geothermal direct use, so long as technical feasibility and cost advantage can be demonstrated. However, few systematic attempts have been made to determine how industry management and technical personnel within these industries view this possibility in light of factors they deem important to their own firms' energy supply choices. This paper discusses that subject in relation to potential commercial geothermal use in the greenhouse, lumber, chemical, and potato and onion processing industries. It is based upon extensive interviews with decision-makers in over 50 firms representing various segments of these industries and is a selected synthesis of material compiled into reports on each industry.

  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. Noncommutativity of the zero chemical potential limit and the thermodynamic limit in finite density systems

    NASA Astrophysics Data System (ADS)

    Ambjørn, J.; Anagnostopoulos, K. N.; Nishimura, J.; Verbaarschot, J. J.

    2004-08-01

    Monte Carlo simulations of finite density systems are often plagued by the complex action problem. We point out that there exists certain noncommutativity in the zero chemical potential limit and the thermodynamic limit when one tries to study such systems by reweighting techniques. This is demonstrated by explicit calculations in a Random Matrix Theory, which is thought to be a simple qualitative model for finite density QCD. The factorization method allows us to understand how the noncommutativity, which appears at the intermediate steps, cancels in the end results for physical observables. In the recent reweighting type of approaches to QCD in the small μ regime, we expect a transition when the volume reaches Vtr≃const./μ2, which however may not be in the range of current lattice calculations.

  18. 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.

  19. Thermal equation of state of polarized fermions in one dimension via complex chemical potentials

    NASA Astrophysics Data System (ADS)

    Loheac, Andrew C.; Braun, Jens; Drut, Joaquín E.; Roscher, Dietrich

    2015-12-01

    We present a nonperturbative computation of the equation of state of polarized, attractively interacting, nonrelativistic fermions in one spatial dimension at finite temperature. We show results for the density, spin magnetization, magnetic susceptibility, and Tan's contact. We compare with the second-order virial expansion, a next-to-leading-order lattice perturbation theory calculation, and interpret our results in terms of pairing correlations. Our lattice Monte Carlo calculations implement an imaginary chemical potential difference to avoid the sign problem. The thermodynamic results on the imaginary side are analytically continued to obtain results on the real axis. We focus on an intermediate- to strong-coupling regime, and cover a wide range of temperatures and spin imbalances.

  20. Hydrodynamics of a quark droplet II: Implications of a non-zero baryon chemical potential

    NASA Astrophysics Data System (ADS)

    Bjerrum-Bohr, Johan J.; Mishustin, Igor N.; Døssing, Thomas

    2014-03-01

    We present an extended version of the dynamical model for a multi-quark droplet evolution described in our proceeding paper. The model includes collective expansion of the droplet, effects of the vacuum pressure and surface tension, and now a non-zero baryon number. The hadron emission from the droplet is described following Weisskopf's statistical model. We consider evolutions of droplets with different initial temperatures and net baryon number. It is found that the introduction of a non-zero net baryon number does not change the lifetime of the droplets significantly. Only when we consider an initially very baryon-rich, low-temperature droplets is the lifetime is decreased significantly. We have, furthermore, found a convergence of both baryon chemical potential and temperature toward the values μB≈450 MeV and T≈150 MeV. This convergence is linked to the competing emission of baryons versus mesons.

  1. 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.

  2. 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.

  3. 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. PMID:25240602

  4. 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

  5. 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. PMID:26212309

  6. 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

  7. Chemical warfare among scleractinians: bioactive natural products from Tubastraea faulkneri Wells kill larvae of potential competitors.

    PubMed

    Koh; Sweatman

    2000-08-30

    Competition for space among scleractinians by overgrowth, overtopping, extracoelenteric digestion and the use of sweeper tentacles is well recognized, but another potential mode of competitive interaction, allelopathy, is largely uninvestigated. In this study, chemical extracts from Tubastraea faulkneri Wells were tested for deleterious effects on competent larvae of 11 other species of coral belonging to seven genera of four scleractinian families. Larvae exposed to extract concentrations from 10 to 500 µg ml(-1) consistently suffered higher mortality than larvae in solvent controls. Larvae of Platygyra daedalea (Ellis and Solander) and Oxypora lacera (Verrill) were the most sensitive, experiencing high mortality even at the lowest extract concentration. The toxic compounds from T. faulkneri did not kill any conspecific larvae. The estimated concentrations of active compounds within T. faulkneri tissues were 100-5000 times higher than the experimental concentrations. Pure compounds isolated from bioactive fractions of the extract were indole alkaloids identified as aplysinopsin, 6-bromoaplysinopsin, 6-bromo-2'-de-N-methylaplysinopsin and its dimer. The first three occur in other non-zooxanthellate corals in the same family as T. faulkneri, whereas the dimer is novel. These compounds could act as allelochemicals that prevent potential competitors from recruiting in the vicinity of T. faulkneri colonies and help to pre-empt interactions with competitively dominant species. PMID:10960612

  8. Application of the integral equation theory of polymers: Distribution function, chemical potential, and mean expansion coefficient

    NASA Astrophysics Data System (ADS)

    Gan, Hin Hark; Eu, Byung Chan

    1993-09-01

    A recursive integral equation for the intramolecular correlation function of an isolated linear polymer of N bonds is derived from the integral equations presented in the preceding paper. The derivation basically involves limiting the density of the polymer to zero so that polymers do not interact with each other, and thus taking into account the intramolecular part only. The integral equation still has the form of a generalized Percus-Yevick integral equation. The intramolecular correlation function of a polymer of N bonds is recursively generated by means of it from those of polymers of 2, 3,..., (N-1) bonds. The end-to-end distance distribution functions are computed by using the integral equation for various chain lengths, temperatures, and bond lengths in the case of a repulsive soft-sphere potential. Numerical solutions of the recursive integral equation yield universal exponents for the mean square end-to-end distance in two and three dimensions with values which are close to the Flory results: 0.77 and 0.64 vs Flory's values 0.75 and 0.6 for two and three dimensions, respectively. The intramolecular correlation functions computed can be fitted with displaced Gaussian forms. The N dependence of the internal chemical potential is found to saturate after some value of N depending on the ratio of the bond length to the bead radius.

  9. Permethrin is a potential thyroid-disrupting chemical: In vivo and in silico envidence.

    PubMed

    Tu, Wenqing; Xu, Chao; Jin, Yuanxiang; Lu, Bin; Lin, Chunmian; Wu, Yongming; Liu, Weiping

    2016-06-01

    Permethrin (PM), one of the most heavily used synthetic pyrethroids, has the potential to interfere with thyroid hormones in mammals, however, the effect is poorly recognized in aquatic organisms. Herein, embryonic zebrafish were exposed to PM (0, 1, 3 and 10μg/L) until 72h post-fertilization. We demonstrated that PM readily accumulated in larvae with a preference for cis-PM, inhibited development and increased thyroxine and 3,5,3'-triiodothyronine levels accompanying increase in the transcription of most target genes, i.e., thyroid-stimulating hormone β, deiodinases, thyroid receptors, involved in the hypothalamic-pituitary-thyroid axis. Further Western blot analysis indicated that transthyretin (TTR) protein was significantly increased. Molecular docking analysis and molecular dynamics simulations revealed that PM fits into three hydrophobic binding pocket of TTR, one of the molecular targets of thyroid hormone disrupting chemicals (THDCs), and forms strong van der Waals interactions with six resides of TTR, including Leu8, Leu 101, Leu125, Thr214, Leu218 and Val229, thus altering TTR activity. Both in vivo and in silico studies clearly disclosed that PM potentially disrupts the thyroid endocrine system in fish. This study provides a rapid and cost-effective approach for identifying THDCs and the underlying mechanisms. PMID:26994367

  10. Early evaluation of potential environmental impacts of carbon nanotube synthesis by chemical vapor deposition.

    PubMed

    Plata, Desirée L; Hart, A John; Reddy, Christopher M; Gschwend, Philip M

    2009-11-01

    The carbon nanotube (CNT) industry is expanding rapidly, yet little is known about the potential environmental impacts of CNT manufacture. Here, we evaluate the effluent composition of a representative multiwalled CNT synthesis by catalytic chemical vapor deposition (CVD) in order to provide data needed to design strategies for mitigating any unacceptable emissions. During thermal pretreatment of the reactant gases (ethene and H(2)), we found over 45 side-products were formed, including methane, volatile organic compounds (VOCs), and polycyclic aromatic hydrocarbons (PAHs). This finding suggests several environmental concerns with the existing process, including potential discharges of the potent greenhouse gas, methane (up to 1.7%), and toxic compounds such as benzene and 1,3-butadiene (up to 36000 ppmv). Extrapolating these laboratory-scale data to future industrial CNT production, we estimate that (1) contributions of atmospheric methane will be negligible compared to other existing sources and (2) VOC and PAH emissions may become important on local scales but will be small when compared to national industrial sources. As a first step toward reducing such unwanted emissions, we used continuous in situ measures of CNT length during growth and sought to identify which thermally generated compounds correlated with CNT growth rate. The results suggested that, in future CNT production approaches, key reaction intermediates could be delivered to the catalyst without thermal treatment. This would eliminate the most energetically expensive component of CVD synthesis (heating reactant gases), while reducing the formation of unintended byproducts. PMID:19924971

  11. In search of the chemical basis of the hemolytic potential of silicas.

    PubMed

    Pavan, Cristina; Tomatis, Maura; Ghiazza, Mara; Rabolli, Virginie; Bolis, Vera; Lison, Dominique; Fubini, Bice

    2013-08-19

    The membranolytic activity of silica particles toward red blood cells (RBCs) has been known for a long time and is sometimes associated with silica pathogenicity. However, the molecular mechanism and the reasons why hemolysis differs according to the silica form are still obscure. A panel of 15 crystalline (pure and commercial) and amorphous (pyrogenic, precipitated from aqueous solutions, vitreous) silica samples differing in size, origin, morphology, and surface chemical composition were selected and specifically prepared. Silica particles were grouped into six groups to compare their potential in disrupting RBC membranes so that one single property differed in each group, while other features were constant. Free radical production and crystallinity were not strict determinants of hemolytic activity. Particle curvature and morphology modulated the hemolytic effect, but silanols and siloxane bridges at the surface were the main actors. Hemolysis was unrelated to the overall concentration of silanols as fully rehydrated surfaces (such as those obtained from aqueous solution) were inert, and one pyrogenic silica also lost its membranolytic potential upon progressive dehydration. Overall results are consistent with a model whereby hemolysis is determined by a defined surface distribution of dissociated/undissociated silanols and siloxane groups strongly interacting with specific epitopes on the RBC membrane. PMID:23819533

  12. 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

  13. 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).…

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

    PubMed

    Hansen, T L; Svärd, A; Angelidaki, I; Schmidt, J E; Jansen, J; Christensen, T H

    2003-01-01

    A research project has investigated the biogas potential of pre-screened source-separated organic waste. Wastes from five Danish cities have been pre-treated by three methods: screw press; disc screen; and shredder and magnet. This paper outlines the sampling procedure used, the chemical composition of the wastes and the estimated methane potentials. PMID:14531442

  15. 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.

  16. 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.

  17. Isospin effects via Coulomb forces on the onset of multifragmentation in light and heavily charged systems

    NASA Astrophysics Data System (ADS)

    Sharma, Arun; Bharti, Arun

    2016-03-01

    We concurrently study the isospin effects via Coulomb forces and the nuclear equation of state and its momentum dependence on the onset of multifragmentation, i.e., critical energy point, in the light and heavily charged reactions of 40Ar + 45Sc and 84Kr + 197Au , respectively, using the isospin-dependent quantum molecular dynamics model. We find that Coulomb forces influence the onset of multifragmentation and result in the shift of the critical energy point towards lower and higher incident energies with and without their presence, respectively. Also, we observe that the critical energy point is sharper for the heavily charged system of 84Kr + 197Au when compared with the light charged system of 40Ar + 45Sc , where a small dip is observed and thus leads to the dependence of onset of multifragmentation, i.e., the critical energy point, on the reaction asymmetry as well as on the Coulomb forces.

  18. Isospin excitation and electromagnetic transition properties of nuclei 88,90Mo

    NASA Astrophysics Data System (ADS)

    Zhang, J. F.; Li, X. W.; Li, Y. S.

    2016-07-01

    The band structure and electromagnetic transition properties of the low-lying states of 88,90Mo isotopes were investigated using the interacting boson model with isospin (IBM-3). The lowest isospin excitation states with T = 2 for 88Mo and T = 3 for 90Mo were identified, and compared with available data. The E2, M1 matrix elements and quadrupole moments for the low-lying states were investigated. Results showed that the lowest mixed-symmetry states were 23+ for 90Mo and 24+ for 88Mo. The excitation energy of the 11+ states in nuclei 88,90Mo were also determined. Good agreement was achieved between calculated results using the model and measured data.

  19. Isospin nonconserving interaction in the T =1 analogue states of the mass-70 region

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    Mirror energy differences (MEDs) and triplet energy differences (TEDs) in the T =1 analogue states are important probes of isospin-symmetry breaking. Inspired by the recent spectroscopic data of 66Se, we investigate these quantities for A =66-78 nuclei with large-scale shell-model calculations. For the first time, we find clear evidence suggesting that the isospin nonconserving (INC) nuclear force has a significant effect for the upper fp shell region. Detailed analysis shows that, in addition to the INC force, the electromagnetic spin-orbit interaction plays an important role for the large, negative MED in A =66 and 70 and the multipole Coulomb term contributes to the negative TED in all the T =1 triplet nuclei. The INC force and its strength needed to reproduce the experimental data are compared with those from the G-matrix calculation using the modern charge-dependent nucleon-nucleon forces.

  20. Isospin mixing in the nucleon and He-4 and the nucleon strange electric form-factor

    SciTech Connect

    M. Viviani; R. Schiavilla; B. Kubis; R. Lewis; L. Girlanda; A. Kievsky; L.E. Marcucci; S. Rosati

    2007-09-01

    In order to isolate the contribution of the nucleon strange electric form factor to the parity-violating asymmetry measured in 4He(\\vec e,e')4He experiments, it is crucial to have a reliable estimate of the magnitude of isospin-symmetry-breaking (ISB) corrections in both the nucleon and 4He. We examine this issue in the present letter. Isospin admixtures in the nucleon are determined in chiral perturbation theory, while those in 4He are derived from nuclear interactions, including explicit ISB terms. A careful analysis of the model dependence in the resulting predictions for the nucleon and nuclear ISB contributions to the asymmetry is carried out. We conclude that, at the low momentum transfers of interest in recent measurements reported by the HAPPEX collaboration at Jefferson Lab, these contributions are of comparable magnitude to those associated with strangeness components in the nucleon electric form factor.

  1. 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.

  2. Isospin decomposition of γ N →N* transitions within a dynamical coupled-channels model

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    By extending the dynamical coupled-channels analysis performed in our previous work [Phys. Rev. C 88, 035209 (2013)], 10.1103/PhysRevC.88.035209 to include the available data of photoproduction of π mesons off neutrons, the transition amplitudes for the photoexcitation of the neutron-to-nucleon resonances, γ n →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 γ p →N* transition amplitudes. Our results allow an isospin decomposition of the γ N →N* transition amplitudes for the isospin I =1/2 N* resonances, which is necessary for testing hadron structure models and gives crucial inputs for constructing models of neutrino-induced reactions in the nucleon resonance region.

  3. The development and application of the chemical mixture methodology in analysis of potential health impacts from airborne release in emergencies

    SciTech Connect

    Yu, Xiao-Ying; Petrocchi, Achille J.; Craig, Douglas K.; Glantz, Clifford S.; Trott, Donna M.; Ciolek, John T.; Lu, Po-Yung; Bond, Jayne-Anne; Tuccinardi, Thomas E.; Bouslaugh, Philip R.

    2010-07-15

    The Chemical Mixture Methodology (CMM) is used for emergency response and safety planning by the U.S. Department of Energy, its contractors, and other private and public sector organizations. The CMM estimates potential health impacts on individuals and their ability to take protective actions as a result of exposure to airborne chemical mixtures. They are based on the concentration of each chemical in the mixture at a designated receptor location, the protective action criteria (PAC) providing chemical-specific exposure limit values, and the health code numbers (HCNs) that identify the target organ groupings that may be impacted by exposure to each chemical in a mixture. The CMM has been significantly improved since its introduction more than 10 years ago. Major enhancements involve the expansion of the number of HCNs from 44 to 60 and inclusion of updated PAC values based on an improved development methodology and updates in the data used to derive the PAC values. Comparisons between the 1999 and 2009 versions of the CMM show potentially substantial changes in the assessment results for selected sets of chemical mixtures. In particular, the toxic mode hazard indices (HIs) and target organ HIs are based on more refined acute HCNs, thereby improving the quality of chemical consequence assessment, emergency planning, and emergency response decision making. Seven hypothetical chemical storage and processing scenarios are used to demonstrate how the CMM is applied in emergency planning and hazard assessment.

  4. 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.

  5. 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.

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

    SciTech Connect

    Broxton, D.E.

    1985-12-31

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

  7. Isospin breaking corrections to low-energy π-K scattering

    NASA Astrophysics Data System (ADS)

    Nehme, A.; Talavera, P.

    2002-03-01

    We evaluate the matrix elements for the processes π0K0-->π0K0 and π-K+-->π0K0 in the presence of isospin breaking terms at leading and next-to-leading order. As a direct application the relevant combination of the S-wave scattering lengths involved in the pion-kaon atom lifetime is determined. We discuss the sensitivity of the results with respect to the input parameters.

  8. Isospin-symmetry breaking effects on the strange electric and magnetic form factors of the nucleon

    SciTech Connect

    Xia Zhengtong; Zuo Wei

    2008-07-15

    We examine the electric and magnetic strange form factors of the nucleon in the pseudoscalar-vector SU(3) Skyrme model, with special emphasis on the effects of isospin symmetry breaking (ISB). It is found that ISB has a nontrivial effect on the strange vector form factors of the nucleon and its contribution to the nucleon strangeness is significantly larger than one might naively expect. Our calculations and discussions may be of some significance for the experimental extraction of the authentic strangeness.

  9. 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.

  10. 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.

  11. 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

  12. 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. PMID:23365607

  13. Antimicrobial Potential and Chemical Characterization of Serbian Liverwort (Porella arboris-vitae): SEM and TEM Observations

    PubMed Central

    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. PMID:23365607

  14. 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.

  15. 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

  16. 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.

  17. Chromophore-immobilized luminescent metal-organic frameworks as potential lighting phosphors and chemical sensors.

    PubMed

    Wang, Fangming; Liu, Wei; Teat, Simon J; Xu, Feng; Wang, Hao; Wang, Xinlong; An, Litao; Li, Jing

    2016-08-11

    An organic chromophore H4tcbpe-F was synthesized and immobilized into metal-organic frameworks along with two bipyridine derivatives as co-ligands to generate two strongly luminescent materials [Zn2(tcbpe-F)(4,4'-bpy)·xDMA] (1) and [Zn2(tcbpe-F)(bpee)·xDMA] (2) [4,4'-bpy = 4,4'-bipyridine, bpee = 4,4'-bipyridyl-ethylene, tcbpe-F = 4',4''',4''''',4'''''''-(ethene-1,1,2,2-tetrayl)tetrakis(3-fluoro-[1,1'-biphenyl]-4-carboxylic acid), DMA = N,N-dimethylacetamide]. Compounds 1 and 2 are isoreticular and feature a 2-fold interpenetrated three-dimensional porous structure. Both compounds give green-yellow emission under blue light excitation. Compound 1 has a high internal quantum yield of ∼51% when excited at 455 nm and shows selective luminescence signal change (e.g. emission energy and/or intensity) towards different solvents, including both aromatic and nonaromatic volatile organic species. These properties make it potentially useful as a lighting phosphor and a chemical sensor. PMID:27465685

  18. Evaluation of the skin sensitization potential of chemicals in THP-1/keratinocyte co-cultures.

    PubMed

    Cao, Yu-Ping; Ma, Peng-Cheng; Liu, Wei-Da; Zhou, Wu-Qing; Tao, Yue; Zhang, Meng-Li; Li, Ling-Jun; Chen, Zi-Yi

    2012-04-01

    Many attempts have been made to develop in vitro sensitization tests that employ dendritic cells (DCs), DC-like cell lines or keratinocytes. The aim of the present investigation was to establish a co-culture of THP-1 cells and keratinocytes for evaluation of skin sensitization potential of chemicals. Co-cultures were constructed by THP-1 cells cultured in lower compartments and keratinocytes cultured in upper compartments of cell culture inserts. After 24 h exposure to sensitizers (2, 4-dinitrochlorobenzene, p-phenylenediamine, formaldehyde, nickel sulfate, isoeugenol and eugenol) and non-sensitizers (sodium lauryl sulfate, benzalkonium chloride and lactic acid), the expression of CD86 and CD54 on THP-1 cells were evaluated by flow cytometry, and cell viabilities were determined. The sensitizers induced the augmentation of CD86 and CD54 expression, but the non-sensitizers had no significant effect. Compared with mono-cultures of THP-1 cells, the augmentation of CD86 and CD54 could be detected even at a non-toxic concentration of sensitizers in THP-1 cell/keratinocyte co-cultures. Moreover, isoeugenol was distinguished as a sensitizer in co-cultures, but failed to be identified in mono-cultures. These results revealed that the co-cultures of THP-1 cells and keratinocytes were successfully established and suitable for identifying sensitizers using CD86 and CD54 expression as identification markers. PMID:21721923

  19. 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. PMID:26133699

  20. 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

  1. 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. PMID:21776513

  2. 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

    2016-01-01

    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

  3. 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).

  4. 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.

  5. 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.

  6. Chemical Potentials, Activity Coefficients, and Solubility in Aqueous NaCl Solutions: Prediction by Polarizable Force Fields.

    PubMed

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

    2015-04-14

    We describe a computationally efficient molecular simulation methodology for calculating the concentration dependence of the chemical potentials of both solute and solvent in aqueous electrolyte solutions, based on simulations of the salt chemical potential alone. We use our approach to study the predictions for aqueous NaCl solutions at ambient conditions of these properties by the recently developed polarizable force fields (FFs) AH/BK3 of Kiss and Baranyai (J. Chem. Phys. 2013, 138, 204507) and AH/SWM4-DP of Lamoureux and Roux (J. Phys. Chem. B 2006, 110, 3308 - 3322) and by the nonpolarizable JC FF of Joung and Cheatham tailored to SPC/E water (J. Phys. Chem. B 2008, 112, 9020 - 9041). We also consider their predictions of the concentration dependence of the electrolyte activity coefficient, the crystalline solid chemical potential, the electrolyte solubility, and the solution specific volume. We first highlight the disagreement in the literature concerning calculations of solubility by means of molecular simulation in the case of the JC FF and provide strong evidence of the correctness of our methodology based on recent independently obtained results for this important test case. We then compare the predictions of the three FFs with each other and with experiment and draw conclusions concerning their relative merits, with particular emphasis on the salt chemical potential and activity coefficient vs concentration curves and their derivatives. The latter curves have only previously been available from Kirkwood-Buff integrals, which require approximate numerical integrations over system pair correlation functions at each concentration. Unlike the case of the other FFs, the AH/BK3 curves are nearly parallel to the corresponding experimental curves at moderate and higher concentrations. This leads to an excellent prediction of the water chemical potential via the Gibbs-Duhem equation and enables the activity coefficient curve to be brought into excellent agreement

  7. 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.

  8. 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

    2016-01-01

    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

  9. 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

  10. 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. PMID:25879505

  11. 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.

  12. 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...

  13. 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...

  14. 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,…

  15. 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...

  16. USE OF IN VITRO ASSAYS TO INTERPRET INDUSTRIAL CHEMICALS' POTENTIAL ESTROGENICITY

    EPA Science Inventory

    The goal of this project is to study estrogen receptor binding and gene expression in fish through the development of in vitro approaches and QSAR models applicable to untested chemicals on EPA inventories. This will facilitate prioritization of chemicals to undergo Tier 1 screen...

  17. 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...

  18. STRUCTURE-ACTIVITY RELATIONSHIPS FOR SCREENING ORGANIC CHEMICALS FOR POTENTIAL ECOTOXICITY EFFECTS

    EPA Science Inventory

    The paper presents structure-activity relationships (QSAR) for estimating the bioconcentration factor and acute toxicity of some classes of industrial chemicals using only the n-octanol/water partition coefficient (Log P) which is derived from chemical structure. The bioconcentra...

  19. Chemical potential shift in organic field-effect transistors identified by soft X-ray operando nano-spectroscopy

    SciTech Connect

    Nagamura, Naoka Kitada, Yuta; Honma, Itaru; Tsurumi, Junto; Matsui, Hiroyuki; Takeya, Jun; Horiba, Koji; Oshima, Masaharu

    2015-06-22

    A chemical potential shift in an organic field effect transistor (OFET) during operation has been revealed by soft X-ray operando nano-spectroscopy analysis performed using a three-dimensional nanoscale electron-spectroscopy chemical analysis system. OFETs were fabricated using ultrathin (3 ML or 12 nm) single-crystalline C10-DNBDT-NW films on SiO{sub 2} (200 nm)/Si substrates with a backgate electrode and top source/drain Au electrodes, and C 1s line profiles under biasing at the backgate and drain electrodes were measured. When applying −30 V to the backgate, there is C 1s core level shift of 0.1 eV; this shift can be attributed to a chemical potential shift corresponding to band bending by the field effect, resulting in p-type doping.

  20. Chemical potential shift in organic field-effect transistors identified by soft X-ray operando nano-spectroscopy

    NASA Astrophysics Data System (ADS)

    Nagamura, Naoka; Kitada, Yuta; Tsurumi, Junto; Matsui, Hiroyuki; Horiba, Koji; Honma, Itaru; Takeya, Jun; Oshima, Masaharu

    2015-06-01

    A chemical potential shift in an organic field effect transistor (OFET) during operation has been revealed by soft X-ray operando nano-spectroscopy analysis performed using a three-dimensional nanoscale electron-spectroscopy chemical analysis system. OFETs were fabricated using ultrathin (3 ML or 12 nm) single-crystalline C10-DNBDT-NW films on SiO2 (200 nm)/Si substrates with a backgate electrode and top source/drain Au electrodes, and C 1s line profiles under biasing at the backgate and drain electrodes were measured. When applying -30 V to the backgate, there is C 1s core level shift of 0.1 eV; this shift can be attributed to a chemical potential shift corresponding to band bending by the field effect, resulting in p-type doping.

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

    PubMed

    Yost, Erin E; Stanek, John; DeWoskin, Robert S; Burgoon, Lyle D

    2016-07-19

    The United States Environmental Protection Agency (EPA) identified 1173 chemicals associated with hydraulic fracturing fluids, flowback, or produced water, of which 1026 (87%) lack chronic oral toxicity values for human health assessments. To facilitate the ranking and prioritization of chemicals that lack toxicity values, it may be useful to employ toxicity estimates from quantitative structure-activity relationship (QSAR) models. Here we describe an approach for applying the results of a QSAR model from the TOPKAT program suite, which provides estimates of the rat chronic oral lowest-observed-adverse-effect level (LOAEL). Of the 1173 chemicals, TOPKAT was able to generate LOAEL estimates for 515 (44%). To address the uncertainty associated with these estimates, we assigned qualitative confidence scores (high, medium, or low) to each TOPKAT LOAEL estimate, and found 481 to be high-confidence. For 48 chemicals that had both a high-confidence TOPKAT LOAEL estimate and a chronic oral reference dose from EPA's Integrated Risk Information System (IRIS) database, Spearman rank correlation identified 68% agreement between the two values (permutation p-value =1 × 10(-11)). These results provide support for the use of TOPKAT LOAEL estimates in identifying and prioritizing potentially hazardous chemicals. High-confidence TOPKAT LOAEL estimates were available for 389 of 1026 hydraulic fracturing-related chemicals that lack chronic oral RfVs and OSFs from EPA-identified sources, including a subset of chemicals that are frequently used in hydraulic fracturing fluids. PMID:27172125

  2. NMR ANALYSIS OF MALE FATHEAD MINNOW URINARY METABOLITES: A POTENTIAL APPROACH FOR STUDYING IMPACTS OF CHEMICAL EXPOSURES

    EPA Science Inventory

    The potential for profiling endogenous metabolites in urine from male fathead minnows (Pimephales promelas) to assess chemical exposures was explored using nuclear magnetic resonance (NMR) spectroscopy. Both one dimensional (1D) and two dimensional (2D) NMR spectroscopy w...

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

    ERIC Educational Resources Information Center

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

    2012-01-01

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

  4. 2+1 flavor Polyakov Nambu Jona-Lasinio model at finite temperature and nonzero chemical potential

    NASA Astrophysics Data System (ADS)

    Fu, Wei-Jie; Zhang, Zhao; Liu, Yu-Xin

    2008-01-01

    We extend the Polyakov-loop improved Nambu Jona-Lasinio model to 2+1 flavor case to study the chiral and deconfinement transitions of strongly interacting matter at finite temperature and nonzero chemical potential. The Polyakov loop, the chiral susceptibility of light quarks (u and d), and the strange quark number susceptibility as functions of temperature at zero chemical potential are determined and compared with the recent results of lattice QCD simulations. We find that there is always an inflection point in the curve of strange quark number susceptibility accompanying the appearance of the deconfinement phase, which is consistent with the result of lattice QCD simulations. Predictions for the case at nonzero chemical potential and finite temperature are made as well. We give the phase diagram in terms of the chemical potential and temperature and find that the critical end point moves down to low temperature and finally disappears with the decrease of the strength of the ’t Hooft flavor-mixing interaction.

  5. Metastability of the Two-Dimensional Blume-Capel Model with Zero Chemical Potential and Small Magnetic Field

    NASA Astrophysics Data System (ADS)

    Landim, C.; Lemire, P.

    2016-07-01

    We consider the two-dimensional Blume-Capel model with zero chemical potential and small magnetic field evolving on a large but finite torus. We obtain sharp estimates for the transition time, we characterize the set of critical configurations, and we prove the metastable behavior of the dynamics as the temperature vanishes.

  6. An in vitro screening method to evaluate chemicals as potential chemotherapeutants to control Aeromonas hydrophila infection in channel catfish

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using catfish gill cells G1B and four chemicals (hydrogen peroxide, sodium chloride, potassium permanganate, and D-mannose), the feasibility of using an in vitro screening method to identify potential effective chemotherapeutants was evaluated in this study. In vitro screening results revealed that,...

  7. COMPARISON OF CHEMICAL SCREENING AND RANKING APPROACHES: THE WASTE MINIMIZATION PRIORITIZATION TOOL VERSUS TOXIC EQUIVALENCY POTENTIALS: JOURNAL ARTICLE

    EPA Science Inventory

    NRMRL-STD-0014 Pennington*, D.W., and Bare*, J.C. Comparison of Chemical Screening and Ranking Approaches: The Waste Minimization Prioritization Tool versus Toxic Equivalency Potentials. Risk Analysis (Anderson, E.L. (Ed.), Malden, MA: Blackwell Publishers) 21 (5):897-912 (2001)...

  8. Development and Validation of an Instrument for Early Assessment of Management Potential in a Mid-Size Chemical Company

    ERIC Educational Resources Information Center

    Zehner, Robert L.; Holton, Elwood F., III

    2004-01-01

    This study reports on development and concurrent validation of a competency instrument to identify potential leaders in a mid-size chemical company. Four competencies were identified: courageous problem solving, perceived energy, networking, and perceived motivation. Four different comparison groups were examined in logistic regression analyses.…

  9. Metastability of the Two-Dimensional Blume-Capel Model with Zero Chemical Potential and Small Magnetic Field

    NASA Astrophysics Data System (ADS)

    Landim, C.; Lemire, P.

    2016-06-01

    We consider the two-dimensional Blume-Capel model with zero chemical potential and small magnetic field evolving on a large but finite torus. We obtain sharp estimates for the transition time, we characterize the set of critical configurations, and we prove the metastable behavior of the dynamics as the temperature vanishes.

  10. Isospin flip as a relativistic effect: NN interactions

    NASA Technical Reports Server (NTRS)

    Buck, W. W.

    1993-01-01

    Results are presented of an analytic relativistic calculation of a OBE nucleon-nucleon (NN) interaction employing the Gross equation. The calculation consists of a non-relativistic reduction that keeps the negative energy states. The result is compared to purely non-relativistic OBEP results and the relativistic effects are separated out. One finds that the resulting relativistic effects are expressable as a power series in (tau(sub 1))(tau(sub 2)) that agrees, qualitatively, with NN scattering. Upon G-parity transforming this NN potential, one obtains, qualitatively, a short range NN spectroscopy in which the S-states are the lowest states.

  11. Open Innovation Drug Discovery (OIDD): a potential path to novel therapeutic chemical space.

    PubMed

    Alvim-Gaston, Maria; Grese, Timothy; Mahoui, Abdelaziz; Palkowitz, Alan D; Pineiro-Nunez, Marta; Watson, Ian

    2014-01-01

    The continued development of computational and synthetic methods has enabled the enumeration or preparation of a nearly endless universe of chemical structures. Nevertheless, the ability of this chemical universe to deliver small molecules that can both modulate biological targets and have drug-like physicochemical properties continues to be a topic of interest to the pharmaceutical industry and academic researchers alike. The chemical space described by public, commercial, in-house and virtual compound collections has been interrogated by multiple approaches including biochemical, cellular and virtual screening, diversity analysis, and in-silico profiling. However, current drugs and known chemical probes derived from these efforts are contained within a remarkably small volume of the predicted chemical space. Access to more diverse classes of chemical scaffolds that maintain the properties relevant for drug discovery is certainly needed to meet the increasing demands for pharmaceutical innovation. The Lilly Open Innovation Drug Discovery platform (OIDD) was designed to tackle barriers to innovation through the identification of novel molecules active in relevant disease biology models. In this article we will discuss several computational approaches towards describing novel, biologically active, drug-like chemical space and illustrate how the OIDD program may facilitate access to previously untapped molecules that may aid in the search for innovative pharmaceuticals. PMID:24283973

  12. Measurement of isospin diffusion from isoscaling of heavy fragment yields in 70 MeV/u Sn+Sn collisions

    NASA Astrophysics Data System (ADS)

    Winkelbauer, Jack; Showalter, R. H.; Tsang, M. B.; Lynch, W. G.; Chajecki, Z.; Youngs, M. D.; Coupland, D. D. S.; Lu, Fei; Sanetullaev, A.; Shane, R.; Tangwancharoen, S.; Famiano, M.; George, S.; Charity, R.; Sobotka, L.; Elson, J.; de Souza, R.; Zhang, Y.

    2015-10-01

    Much effort has been undertaken recently to improve constraints on the symmetry energy term in the nuclear equation of state. Specifically, the behavior of the symmetry energy above and below saturation density plays a significant role in the properties of neutron stars, the structure of heavy nuclei, and the dynamics of nuclear reactions. The tendency for neutrons to drift from a neutron-rich region to a neutron-deficient region during a peripheral collision of heavy nuclei is known as isospin diffusion, and has been shown to be sensitive to the symmetry energy at sub-saturation densities. Isospin diffusion between projectiles of 112 , 118 , 124Sn at 70 MeV/u and targets of 112 , 118 , 124Sn has been measured, using isoscaling ratios of heavy fragments as a tracer of the isospin content of the excited projectile-like fragment. The validity of using isoscaling as a surrogate for the isospin asymmetry will be discussed, and the associated isospin diffusion results will be presented.

  13. A Mechanical Analogue for Chemical Potential, Extent of Reaction, and the Gibbs Energy.

    ERIC Educational Resources Information Center

    Glass, Samuel V.; DeKock, Roger L.

    1998-01-01

    Presents an analogy that relates the one-dimensional mechanical equilibrium of a rigid block between two Hooke's law springs and the chemical equilibrium of two perfect gases using ordinary materials. (PVD)

  14. 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.

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

    SciTech Connect

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

    1987-03-01

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

  16. Potential impacts of agricultural chemicals on waterfowl and other wildlife inhabiting prairie wetlands: An evaluation of research needs and approaches

    USGS Publications Warehouse

    Grue, C.E.; DeWeese, L.R.; Mineau, P.; Swanson, G.A.; Foster, J.R.; Arnold, P.M.; Huckins, J.N.; Sheenan, P.J.; Marshall, W.K.; Ludden, A.P.

    1986-01-01

    The potential for agricultural chemicals to enter prairie-pothole wetlands and impact wildlife dependent on these wetlands for survival and reproduction appears to be great. However, the actual risk to wetland wildlife from the inputs of these chemicals cannot be adequately assessed at this time, because of insufficient data. Available data on the use of pesticides in the prairie-pothole region and the toxicity of these pesticides suggest that insecticides pose the greatest hazard to wetland wildlife, particularly birds. The majority of the most widely used insecticides within the region are very toxic to aquatic invertebrates and birds. Of particular concern are the impacts of agricultural chemicals on the quality of the remaining wetlands in the region and whether or not these impacts have contributed to observed declines in waterfowl populations. Although existing data suggest that adult and juvenile waterfowl may not be more sensitive to these chemicals than are other wetland wildlife, their food habits and feeding behaviors may make them more vulnerable to direct toxic effects or chemical-induced changes in the abundance of aquatic invertebrates. Laboratory and field studies in the United States and Canada are critically needed to assess these potential impacts.

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

    PubMed

    Sablon, Ludovic; Dickens, Joseph C; Haubruge, Éric; Verheggen, François J

    2012-01-01

    The Colorado potato beetle (CPB) has been a major insect pest to potato farming for over 150 years and various control methods have been established to reduce its impact on potato fields. Crop rotation and pesticide use are currently the most widely used approaches, although alternative methods are being developed. Here we review the role of various volatile and nonvolatile chemicals involved in behavior changes of CPB that may have potential for their control. First, we describe all volatile and nonvolatile chemicals involved in host plant localization and acceptance by CPB beetles, including glycoalcaloids and host plant volatiles used as kairomones. In the second section, we present the chemical signals used by CPB in intraspecific communication, including sex and aggregation pheromones. Some of these chemicals are used by natural enemies of CPBs to locate their prey and are presented in the third section. The last section of this review is devoted a discussion of the potential of some natural chemicals in biological control of CPB and to approaches that already reached efficient field applications. PMID:26466794

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

    PubMed Central

    Sablon, Ludovic; Dickens, Joseph C.; Haubruge, Éric; Verheggen, François J.

    2012-01-01

    The Colorado potato beetle (CPB) has been a major insect pest to potato farming for over 150 years and various control methods have been established to reduce its impact on potato fields. Crop rotation and pesticide use are currently the most widely used approaches, although alternative methods are being developed. Here we review the role of various volatile and nonvolatile chemicals involved in behavior changes of CPB that may have potential for their control. First, we describe all volatile and nonvolatile chemicals involved in host plant localization and acceptance by CPB beetles, including glycoalcaloids and host plant volatiles used as kairomones. In the second section, we present the chemical signals used by CPB in intraspecific communication, including sex and aggregation pheromones. Some of these chemicals are used by natural enemies of CPBs to locate their prey and are presented in the third section. The last section of this review is devoted a discussion of the potential of some natural chemicals in biological control of CPB and to approaches that already reached efficient field applications. PMID:26466794

  19. Isospin dependence of fragment spectra in heavy/super-heavy colliding nuclei at intermediate energies

    NASA Astrophysics Data System (ADS)

    Chugh, Rajiv; Kumar, Rohit; Vinayak, Karan Singh

    2016-05-01

    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.

  20. Collective flow properties of intermediate mass fragments and isospin effects in fragmentation at Fermi energies

    SciTech Connect

    Baran, V.; Zus, R.; Colonna, M.; Di Toro, M.

    2013-11-13

    Within a microscopic transport model (Stochastic Mean Field) we analyze the collective flow properties associated to the intermediate mass fragments produced in nuclear fragmentation. We study the transverse and elliptic flow parameters for each rank in mass hierarchy. The results are plotted for {sup 124}Sn + {sup 124}Sn systems at an energy of 50AMeV and for an impact parameter b=4fm. The correlation with the dynamics of the isospin degree of freedom is also discussed and the results are presented for the same systems.

  1. Chemical reactivity indices and mechanism-based read-across for non-animal based assessment of skin sensitisation potential.

    PubMed

    Roberts, David W; Aptula, Aynur O; Patlewicz, Grace; Pease, Camilla

    2008-05-01

    The skin sensitisation potential of chemicals is currently assessed using in vivo methods where the murine local lymph node assay (LLNA) is typically the method of first choice. Current regulatory initiatives are driving the impetus for the use of in vitro/in silico alternative approaches to provide the relevant information needed for the effective assessment of skin sensitisation, for both hazard characterisation and risk assessment purposes. A chemical must undergo a number of steps for it to induce skin sensitisation but the main determining step is formation of a stable covalent association with carrier protein. The ability of a chemical to react covalently with carrier protein nucleophiles relates to both its electrophilic reactivity and its hydrophobicity. This paper focuses on quantitative indices of electrophilic reactivity with nucleophiles, in a chemical mechanism-of-action context, and compares and contrasts the experimental approaches available to generate reactivity data that are suitable for mathematical modelling and making predictions of skin sensitisation potential, using new chemistry data correlated against existing in vivo bioassay data. As such, the paper goes on to describe an illustrative example of how quantitative kinetic measures of reactivity can be usefully and simply applied to perform mechanism-based read-across that enables hazard characterisation of skin sensitisation potential. An illustration of the types of quantitative mechanistic models that could be built using databases of kinetic measures of reactivity, hydrophobicity and existing in vivo bioassay data is also given. PMID:17703503

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

    USGS Publications Warehouse

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

    2015-01-01

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

  3. Evaluation of a High-Throughput Peptide Reactivity Format Assay for Assessment of the Skin Sensitization Potential of Chemicals

    PubMed Central

    Wong, Chin Lin; Lam, Ai-Leen; Smith, Maree T.; Ghassabian, Sussan

    2016-01-01

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

  4. Potential impacts on groundwater resources of deep CO2 storage: natural analogues for assessing potential chemical effects

    NASA Astrophysics Data System (ADS)

    Lions, J.; Gale, I.; May, F.; Nygaard, E.; Ruetters, H.; Beaubien, S.; Sohrabi, M.; Hatzignatiou, D. G.; CO2GeoNet Members involved in the present study Team

    2011-12-01

    Carbon dioxide Capture and Storage (CCS) is considered as one of the promising options for reducing atmospheric emissions of CO2 related to human activities. One of the main concerns associated with the geological storage of CO2 is that the CO2 may leak from the intended storage formation, migrate to the near-surface environment and, eventually, escape from the ground. This is a concern because such leakage may affect aquifers overlying the storage site and containing freshwater that may be used for drinking, industry and agriculture. The IEA Greenhouse Gas R&D Programme (IEAGHG) recently commissioned the CO2GeoNet Association to undertake a review of published and unpublished literature on this topic with the aim of summarizing 'state of the art' knowledge and identifying knowledge gaps and research priorities in this field. Work carried out by various CO2GeoNet members was also used in this study. This study identifies possible areas of conflict by combining available datasets to map the global and regional superposition of deep saline formations (DSF) suitable for CO2 storage and overlying fresh groundwater resources. A scenario classification is developed for the various geological settings where conflict could occur. The study proposes two approaches to address the potential impact mechanisms of CO2 storage projects on the hydrodynamics and chemistry of shallow groundwater. The first classifies and synthesizes changes of water quality observed in natural/industrial analogues and in laboratory experiments. The second reviews hydrodynamic and geochemical models, including coupled multiphase flow and reactive transport. Various models are discussed in terms of their advantages and limitations, with conclusions on possible impacts on groundwater resources. Possible mitigation options to stop or control CO2 leakage are assessed. The effect of CO2 pressure in the host DSF and the potential effects on shallow aquifers are also examined. The study provides a review of

  5. Quantum chemical approach for condensed-phase thermochemistry (III): Accurate evaluation of proton hydration energy and standard hydrogen electrode potential

    NASA Astrophysics Data System (ADS)

    Ishikawa, Atsushi; Nakai, Hiromi

    2016-04-01

    Gibbs free energy of hydration of a proton and standard hydrogen electrode potential were evaluated using high-level quantum chemical calculations. The solvent effect was included using the cluster-continuum model, which treated short-range effects by quantum chemical calculations of proton-water complexes, and the long-range effects by a conductor-like polarizable continuum model. The harmonic solvation model (HSM) was employed to estimate enthalpy and entropy contributions due to nuclear motions of the clusters by including the cavity-cluster interactions. Compared to the commonly used ideal gas model, HSM treatment significantly improved the contribution of entropy, showing a systematic convergence toward the experimental data.

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

    PubMed Central

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

    2015-01-01

    Background Hydraulic fracturing technologies, developed over the last 65 years, have only recently been combined with horizontal drilling to unlock oil and gas reserves previously deemed inaccessible. Although these technologies have dramatically increased domestic oil and natural gas production, they have also raised concerns for the potential contamination of local water supplies with the approximately 1,000 chemicals that are used throughout the process, including many known or suspected endocrine-disrupting chemicals. Objectives We discuss the need for an endocrine component to health assessments for drilling-dense regions in the context of hormonal and antihormonal activities for chemicals used. Methods We discuss the literature on a) surface and groundwater contamination by oil and gas extraction operations, and b) potential human exposure, particularly in the context of the total hormonal and antihormonal activities present in surface and groundwater from natural and anthropogenic sources; we also discuss initial analytical results and critical knowledge gaps. Discussion In light of the potential for environmental release of oil and gas chemicals that can disrupt hormone receptor systems, we recommend methods for assessing complex hormonally active environmental mixtures. Conclusions We describe a need for an endocrine-centric component for overall health assessments and provide information supporting the idea that using such a component will help explain reported adverse health trends as well as help develop recommendations for environmental impact assessments and monitoring programs. Citation Kassotis CD, Tillitt DE, Lin CH, McElroy JA, Nagel SC. 2016. Endocrine-disrupting chemicals and oil and natural gas operations: potential environmental contamination and recommendations to assess complex environmental mixtures. Environ Health Perspect 124:256–264; http://dx.doi.org/10.1289/ehp.1409535 PMID:26311476

  7. 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.

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

    PubMed

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

    2009-01-01

    A significant need exists for in situ sensors that can measure chemical species involved in the major processes of primary production (photosynthesis and chemosynthesis) and respiration. Some key chemical species are O2, nutrients (N and P), micronutrients (metals), pCO2, dissolved inorganic carbon (DIC), pH, and sulfide. Sensors need to have excellent detection limits, precision, selectivity, response time, a large dynamic concentration range, low power consumption, robustness, and less variation of instrument response with temperature and pressure, as well as be free from fouling problems (biological, physical, and chemical). Here we review the principles of operation of most sensors used in marine waters. We also show that some sensors can be used in several different oceanic environments to detect the target chemical species, whereas others are useful in only one environment because of various limitations. Several sensors can be used truly in situ, whereas many others involve water brought into a flow cell via tubing to the analyzer in the environment or aboard ship. Multi-element sensors that measure many chemical species in the same water mass should be targeted for further development. PMID:21141031

  9. Marine Chemical Technology and Sensors for Marine Waters: Potentials and Limits

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

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

  10. Chemical potential of oxygen in (U, Pu) mixed oxide with Pu/(U+Pu) = 0.46

    NASA Astrophysics Data System (ADS)

    Dawar, Rimpi; Chandramouli, V.; Anthonysamy, S.

    2016-05-01

    Chemical potential of oxygen in (U,Pu) mixed oxide with Pu/(U + Pu) = 0.46 was measured for the first time using H2/H2O gas equilibration combined with solid electrolyte EMF technique at 1073, 1273 and 1473 K covering an oxygen potential range of -525 to -325 kJ mol-1. The effect of oxygen potential on the oxygen to metal ratio was determined. Increase in oxygen potential increases the O/M. In this study the minimum O/M obtained was 1.985 below which reduction was not possible. Partial molar enthalpy ΔHbar O2 and entropy ΔSbar O2 of oxygen were calculated from the oxygen potential data. The values of -752.36 kJ mol-1 and 0.25 kJ mol-1 were obtained for ΔHbar O2 and ΔSbar O2 respectively.

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

    PubMed Central

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

    2011-01-01

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

  12. Kinetic and potential parts of nuclear symmetry energy: the role of Fock terms

    NASA Astrophysics Data System (ADS)

    Zhao, Qian; Sun, Bao Yuan; Long, Wen Hui

    2015-09-01

    The density dependence of nuclear symmetry energy is studied within the covariant density functional (CDF) theory in terms of the kinetic energy, isospin-singlet, and isospin-triplet potential energy parts of the energy density functional. When the Fock diagram is introduced, it is found that both isospin-singlet and isospin-triplet components of the potential energy play an important role in determining the symmetry energy. At high densities, a strong density-dependent behavior is revealed in the isospin-triplet potential part of the symmetry energy. In addition, the inclusion of the Fock terms in the CDF theory reduces the kinetic part of the symmetry energy and may lead to negative values at the supranuclear density region, which is regarded partly as the effect of the nuclear tensor-force components. The results demonstrate the importance of the Fock diagram in the CDF theory on the isospin properties of the in-medium nuclear force at high densities, especially from the isoscalar-meson coupling channels.

  13. The chemical fractionation and potential source identification of Cu, Zn and Cd on urban watershed.

    PubMed

    Zhang, Jin; Hua, Pei; Krebs, Peter

    2015-01-01

    This study showcases the chemical fractionation and primary source identification of Cu, Zn and Cd in road-deposited sediment. Results show that Zn and Cd were identified as easily mobilised and biologically available metals that pose high risks to the receiving aquatic environments. However, Cu was released in substantial amounts only under relatively extreme conditions. With the assistance of principal component analysis and chemical fractionation, two primary contributors to heavy metals in road-deposited sediment were tentatively identified as vehicle-related sources (especially, auto brake pad erosion for Cu and tyre debris for Zn) and atmospheric deposition (especially for Cd). PMID:26465315

  14. Isospin transport and reaction mechanism in nuclear reactions in the range 20–40 MeV/n

    SciTech Connect

    Barlini, S. Piantelli, S.; Casini, G.; Olmi, A.; Bini, M.; Pasquali, G.; Poggi, G.; Stefanini, A. A.; Valdré, S.; Pastore, G.; Bougault, R.; Lopez, O.; Le Neindre, N.; Parlog, M.; Vient, E.; Bonnet, E.; Chibhi, A.; Frankland, J. D. [GANIL, CEA Borderie, B.; Rivet, M. F. [Institut de Physique Nucléaire, CNRS and others

    2015-10-15

    In recent years, many efforts have been devoted to the investigation of the isospin degree of freedom in nuclear reactions. Comparing systems involving partners with different N/Z, it has been possible to investigate the isospin transport process and its influence on the final products population. This can be then related to the symmetry energy term of the nuclear EOS. From the experimental point of view, this task requires detectors able to measure both charge and mass of the emitted products, in the widest possible range of energy and size of the fragments. With this objective, the FAZIA and GARFIELD+RCo apparatus have been used with success in some recent experiments.

  15. 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.

  16. From Chemical Gardens to Fuel Cells: Generation of Electrical Potential and Current Across Self-Assembling Iron Mineral Membranes.

    PubMed

    Barge, Laura M; Abedian, Yeghegis; Russell, Michael J; Doloboff, Ivria J; Cartwright, Julyan H E; Kidd, Richard D; Kanik, Isik

    2015-07-01

    We examine the electrochemical gradients that form across chemical garden membranes and investigate how self-assembling, out-of-equilibrium inorganic precipitates-mimicking in some ways those generated in far-from-equilibrium natural systems-can generate electrochemical energy. Measurements of electrical potential and current were made across membranes precipitated both by injection and solution interface methods in iron-sulfide and iron-hydroxide reaction systems. The battery-like nature of chemical gardens was demonstrated by linking multiple experiments in series which produced sufficient electrical energy to light an external light-emitting diode (LED). This work paves the way for determining relevant properties of geological precipitates that may have played a role in hydrothermal redox chemistry at the origin of life, and materials applications that utilize the electrochemical properties of self-organizing chemical systems. PMID:25968422

  17. Relativistically corrected nuclear magnetic resonance chemical shifts calculated with the normalized elimination of the small component using an effective potential-NMR chemical shifts of molybdenum and tungsten

    NASA Astrophysics Data System (ADS)

    Filatov, Michael; Cremer, Dieter

    2003-07-01

    A new method for relativistically corrected nuclear magnetic resonance (NMR) chemical shifts is developed by combining the individual gauge for the localized orbital approach for density functional theory with the normalized elimination of a small component using an effective potential. The new method is used for the calculation of the NMR chemical shifts of 95Mo and 183W in various molybdenum and tungsten compounds. It is shown that quasirelativistic corrections lead to an average improvement of calculated NMR chemical shift values by 300 and 120 ppm in the case of 95Mo and 183W, respectively, which is mainly due to improvements in the paramagnetic contributions. The relationship between electronic structure of a molecule and the relativistic paramagnetic corrections is discussed. Relativistic effects for the diamagnetic part of the magnetic shielding caused by a relativistic contraction of the s,p orbitals in the core region concern only the shielding values, however, have little consequence for the shift values because of the large independence from electronic structure and a cancellation of these effects in the shift values. It is shown that the relativistic corrections can be improved by level shift operators and a B3LYP hybrid functional, for which Hartree-Fock exchange is reduced to 15%.

  18. Chemical Reaction CO+OH(•) → CO2+H(•) Autocatalyzed by Carbon Dioxide: Quantum Chemical Study of the Potential Energy Surfaces.

    PubMed

    Masunov, Artëm E; Wait, Elizabeth; Vasu, Subith S

    2016-08-01

    The supercritical carbon dioxide medium, used to increase efficiency in oxy combustion fossil energy technology, may drastically alter both rates and mechanisms of chemical reactions. Here we investigate potential energy surface of the second most important combustion reaction with quantum chemistry methods. Two types of effects are reported: formation of the covalent intermediates and formation of van der Waals complexes by spectator CO2 molecule. While spectator molecule alter the activation barrier only slightly, the covalent bonding opens a new reaction pathway. The mechanism includes sequential covalent binding of CO2 to OH radical and CO molecule, hydrogen transfer from oxygen to carbon atoms, and CH bond dissociation. This reduces the activation barrier by 11 kcal/mol at the rate-determining step and is expected to accelerate the reaction rate. The finding of predicted catalytic effect is expected to play an important role not only in combustion but also in a broad array of chemical processes taking place in supercritical CO2 medium. It may open a new venue for controlling reaction rates for chemical manufacturing. PMID:27351778

  19. A medium-term rat liver bioassay for rapid in vivo detection of carcinogenic potential of chemicals.

    PubMed

    Ito, Nobuyuki; Tamano, Seiko; Shirai, Tomoyuki

    2003-01-01

    A reliable medium-term bioassay system for rapid detection of carcinogenic potential of chemicals in the human environment has been developed. The 8-week-protocol consists of 2 stages; male F344 rats are given a single intraperitoneal injection of diethylnitrosamine (200 mg/kg) for initiation of liver carcinogenesis, followed by a 6-week test chemical treatment starting 2 weeks thereafter. Test chemicals are usually given in the diet or the drinking water and in the 2nd week of test chemical treatment, all rats are subjected to two-thirds partial hepatectomy in order to induce regenerative cell replication. The end-point marker is the glutathione S-transferase placental form (GST-P)-positive hepatic focus, the numbers and sizes of which are analyzed using an image-analyzer and expressed as values per unit liver section (1 cm2). When the yield of GST-P-positive foci is significantly enhanced (P<0.05) over the control value, a chemical is judged to possess carcinogenic or promotion potential for the liver. Among 313 chemicals already tested in this system in our laboratory, 30/31 (97%) mutagenic hepatocarcinogens and 29/33 (88%) non-mutagenic hepatocarcinogens gave positive results. Ten out of 43 (23%) agents known to be carcinogenic in organs other than the liver were also positive. It is particularly important that only one of 48 non-carcinogens gave a very weak positive result, so that the system has a very low false-positivity rate. It is now well documented that the assay system is highly effective for detecting hepatocarcinogens, bridging the gap between traditional long-term carcinogenicity tests and short-term screening assays. At the Fourth International Conference on Harmonization, our medium-term liver bioassay based on an initiation and promotion protocol was recommended in the guidelines as an acceptable alternative to the long-term rodent carcinogenicity test. PMID:12708466

  20. INSECTS AND THEIR CHEMICAL WEAPONRY: GREAT POTENTIAL AND NEW DISCOVERIES FROM THE ORDER PHASMATODEA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With over 1,000,000 species of insects known, Class Insecta (Phyllum Arthropoda), the largest and most diverse group of organisms, is one of the least explored in natural product drug discovery (Dossey, A. T., Nat. Prod Rep. 2010, 27, 1737–1757). Over the past five our research stick insect chemical...

  1. Can phylogeny predict chemical diversity and potential medicinal activity of plants? A case study of Amaryllidaceae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ap...

  2. ENDOCRINE-DISRUPTING CHEMICALS IN THE ENVIRONMENT: ASSESSING POTENTIAL EFFECTS IN WILDLIFE

    EPA Science Inventory

    Recent evidence suggests that xenobiotic chemicals which mimic/block the action of key hormones in a variety of endocrine pathways may be responsible for adverse effects both in humans and wildlife. This talk will provide an overview of instances in which endocrine-disrupting che...

  3. A chemical additive to limit potential bacterial contamination in chill tanks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Broiler carcasses with different types and numbers of bacteria are commonly chilled together in an ice water bath which may lead to transfer of unwanted bacteria from carcass to carcass. Historically chill tanks have been chlorinated to help prevent cross contamination and recently other chemical a...

  4. Machine learning predictions of molecular properties: Accurate many-body potentials and nonlocality in chemical space

    DOE PAGESBeta

    Hansen, Katja; Biegler, Franziska; Ramakrishnan, Raghunathan; Pronobis, Wiktor; von Lilienfeld, O. Anatole; Müller, Klaus -Robert; Tkatchenko, Alexandre

    2015-06-04

    Simultaneously accurate and efficient prediction of molecular properties throughout chemical compound space is a critical ingredient toward rational compound design in chemical and pharmaceutical industries. Aiming toward this goal, we develop and apply a systematic hierarchy of efficient empirical methods to estimate atomization and total energies of molecules. These methods range from a simple sum over atoms, to addition of bond energies, to pairwise interatomic force fields, reaching to the more sophisticated machine learning approaches that are capable of describing collective interactions between many atoms or bonds. In the case of equilibrium molecular geometries, even simple pairwise force fields demonstratemore » prediction accuracy comparable to benchmark energies calculated using density functional theory with hybrid exchange-correlation functionals; however, accounting for the collective many-body interactions proves to be essential for approaching the “holy grail” of chemical accuracy of 1 kcal/mol for both equilibrium and out-of-equilibrium geometries. This remarkable accuracy is achieved by a vectorized representation of molecules (so-called Bag of Bonds model) that exhibits strong nonlocality in chemical space. The same representation allows us to predict accurate electronic properties of molecules, such as their polarizability and molecular frontier orbital energies.« less

  5. Machine learning predictions of molecular properties: Accurate many-body potentials and nonlocality in chemical space

    SciTech Connect

    Hansen, Katja; Biegler, Franziska; Ramakrishnan, Raghunathan; Pronobis, Wiktor; von Lilienfeld, O. Anatole; Müller, Klaus -Robert; Tkatchenko, Alexandre

    2015-06-04

    Simultaneously accurate and efficient prediction of molecular properties throughout chemical compound space is a critical ingredient toward rational compound design in chemical and pharmaceutical industries. Aiming toward this goal, we develop and apply a systematic hierarchy of efficient empirical methods to estimate atomization and total energies of molecules. These methods range from a simple sum over atoms, to addition of bond energies, to pairwise interatomic force fields, reaching to the more sophisticated machine learning approaches that are capable of describing collective interactions between many atoms or bonds. In the case of equilibrium molecular geometries, even simple pairwise force fields demonstrate prediction accuracy comparable to benchmark energies calculated using density functional theory with hybrid exchange-correlation functionals; however, accounting for the collective many-body interactions proves to be essential for approaching the “holy grail” of chemical accuracy of 1 kcal/mol for both equilibrium and out-of-equilibrium geometries. This remarkable accuracy is achieved by a vectorized representation of molecules (so-called Bag of Bonds model) that exhibits strong nonlocality in chemical space. The same representation allows us to predict accurate electronic properties of molecules, such as their polarizability and molecular frontier orbital energies.

  6. Chemically modified fatty acid methyl esters: their potential for use as lubrication fluids and surfactants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A review of recent developments in the synthesis and characterization of lubrication fluids and surfactants from methyl oleate. The synthesis of materials made using an epoxidation route is the focus. This versatile method of chemical modification of fatty acid methyl esters improves their oxidati...

  7. High-Throughput Exposure Potential Prioritization for ToxCast Chemicals

    EPA Science Inventory

    The U.S. EPA must consider lists of hundreds to thousands of chemicals when prioritizing research resources in order to identify risk to human populations and the environment. High-throughput assays to identify biological activity in vitro have allowed the ToxCastTM program to i...

  8. Ecological Recovery Potential of Freshwater Organisms: Consequences for Environmental Risk Assessment of Chemicals.

    PubMed

    Gergs, Andre; Classen, Silke; Strauss, Tido; Ottermanns, Richard; Brock, Theo C M; Ratte, Hans Toni; Hommen, Udo; Preuss, Thomas G

    2016-01-01

    Chemical contaminants released into the in the environment may have adverse effects on (non-target) species, populations and communities. The return of a stressed system to its pre-disturbance or other reference state, i.e. the ecological recovery, may depend on various factors related to the affected taxon, the ecosystem of concern and the type of stressor with consequences for the assessment and management of risks associated with chemical contaminants. Whereas the effects caused by short-term exposure might be acceptable to some extent, the conditions under which ecological recovery can serve as a decision criterion in the environmental risk assessment of chemical stressors remains to be evaluated. For a generic consideration of recovery in the risk assessment of chemicals, we reviewed case studies of natural and artificial aquatic systems and evaluate five aspects that might cause variability in population recovery time: (1) taxonomic differences and life-history variability, (2) factors related to ecosystem type and community processes, (3) type of disturbance, (4) comparison of field and semi-field studies, and (5) effect magnitude, i.e., the decline in population size following disturbance. We discuss our findings with regard to both retrospective assessments and prospective risk assessment. PMID:26423077

  9. 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.

  10. 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.

  11. Masses from an inhomogeneous partial difference equation with higher-order isospin contributions

    SciTech Connect

    Masson, P.J.; Jaenecke, J.

    1988-07-01

    In the present work, a mass equation obtained as the solution of an inhomogeneous partial difference equation is used to predict masses of unknown neutron-rich and proton-rich nuclei. The inhomogeneous source terms contain shell-dependent symmetry energy expressions (quadratic in isospin), and include, as well, an independently derived shell-model Coulomb energy equation which describes all known Coulomb displacement energies with a standarad deviation of sigma/sub c/ = 41 keV. Perturbations of higher order in isospin, previously recognized as a cause of systematic effects in long-range mass extrapolations, are also incorporated. The most general solutions of the inhomogeneous difference equation have been deduced from a chi/sup 2/-minimization procedure based on the recent atomic mass adjustment of Wapstra, Audi, and Hoekstra. Subjecting the solutions further to the condition of charge symmetry preserves the accuracy of Coulomb energies and allows mass predictions for nuclei with both Ngreater than or equal toZ and Z>N. The solutions correspond to a mass equation with 470 parameters. Using this equation, 4385 mass values have been calculated for nuclei with Agreater than or equal to16 (except N = Z = odd for A<40), with a standard deviation of sigma/sub m/ = 194 keV from the experimental masses. copyright 1988 Academic Press, Inc.

  12. 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.

  13. Imaginary chemical potential approach for the pseudocritical line in the QCD phase diagram with clover-improved Wilson fermions

    NASA Astrophysics Data System (ADS)

    Nagata, Keitaro; Nakamura, Atsushi

    2011-06-01

    The QCD phase diagram is studied in the lattice QCD simulation with the imaginary chemical potential approach. We employ a clover-improved Wilson fermion action of two flavors and a renormalization-group improved gauge action and perform the simulation at an intermediate quark mass on a 83×4 lattice. The QCD phase diagram in the imaginary chemical potential μI region is investigated by performing the simulation for more than 150 points on the (β,μI) plane. We find that the Roberge-Weiss phase transition at μI/T=π/3 is first order and its endpoint is second order, which are identified by the phase of the Polyakov loop. We determine the pseudocritical line from the susceptibility of the Polyakov loop modulus. We find a clear deviation from a linear dependence of the pseudocritical line on μI2.

  14. QCD equation of state at nonzero chemical potential: continuum results with physical quark masses at order μ 2

    NASA Astrophysics Data System (ADS)

    Borsányi, Sz.; Endrődi, G.; Fodor, Z.; Katz, S. D.; Krieg, S.; Ratti, C.; Szabó, K. K.

    2012-08-01

    We determine the equation of state of QCD for nonzero chemical potentials via a Taylor expansion of the pressure. The results are obtained for N f = 2 + 1 flavors of quarks with physical masses, on various lattice spacings. We present results for the pressure, interaction measure, energy density, entropy density, and the speed of sound for small chemical potentials. At low temperatures we compare our results with the Hadron Resonance Gas model. We also express our observables along trajectories of constant entropy over particle number. A simple parameterization is given (the Matlab/Octave script parameterization.m, submitted to the arXiv along with the paper), which can be used to reconstruct the observables as functions of T and μ, or as functions of T and S/N.

  15. Mountain-Scale Coupled Thermal-Hydrological-Chemical Processes Around the Potential Nuclear Waste Repository at Yucca Mountain

    SciTech Connect

    E. Sonnenthal; C. Haukwa; N. Spycher

    2001-06-04

    The objectives of this study were to evaluate the thermal-hydrological-chemical (THC) effects on flow and geochemistry in the unsaturated zone (UZ) at Yucca Mountain at a mountain scale. The major THC processes important in the UZ are (1) mineral precipitation/dissolution affecting flow and transport to and from the potential repository, and (2) changes in the compositions of gas and liquid that may seep into drifts.

  16. Big Data in Chemical Toxicity Research: The Use of High-Throughput Screening Assays To Identify Potential Toxicants

    PubMed Central

    2015-01-01

    High-throughput screening (HTS) assays that measure the in vitro toxicity of environmental compounds have been widely applied as an alternative to in vivo animal tests of chemical toxicity. Current HTS studies provide the community with rich toxicology information that has the potential to be integrated into toxicity research. The available in vitro toxicity data is updated daily in structured formats (e.g., deposited into PubChem and other data-sharing web portals) or in an unstructured way (papers, laboratory reports, toxicity Web site updates, etc.). The information derived from the current toxicity data is so large and complex that it becomes difficult to process using available database management tools or traditional data processing applications. For this reason, it is necessary to develop a big data approach when conducting modern chemical toxicity research. In vitro data for a compound, obtained from meaningful bioassays, can be viewed as a response profile that gives detailed information about the compound’s ability to affect relevant biological proteins/receptors. This information is critical for the evaluation of complex bioactivities (e.g., animal toxicities) and grows rapidly as big data in toxicology communities. This review focuses mainly on the existing structured in vitro data (e.g., PubChem data sets) as response profiles for compounds of environmental interest (e.g., potential human/animal toxicants). Potential modeling and mining tools to use the current big data pool in chemical toxicity research are also described. PMID:25195622

  17. Consensus on the solubility of NaCl in water from computer simulations using the chemical potential route.

    PubMed

    Benavides, A L; Aragones, J L; Vega, C

    2016-03-28

    The solubility of NaCl in water is evaluated by using three force field models: Joung-Cheatham for NaCl dissolved in two different water models (SPC/E and TIP4P/2005) and Smith Dang NaCl model in SPC/E water. The methodology based on free-energy calculations [E. Sanz and C. Vega, J. Chem. Phys. 126, 014507 (2007)] and [J. L. Aragones et al., J. Chem. Phys. 136, 244508 (2012)] has been used, except, that all calculations for the NaCl in solution were obtained by using molecular dynamics simulations with the GROMACS package instead of homemade MC programs. We have explored new lower molalities and made longer runs to improve the accuracy of the calculations. Exploring the low molality region allowed us to obtain an analytical expression for the chemical potential of the ions in solution as a function of molality valid for a wider range of molalities, including the infinite dilute case. These new results are in better agreement with recent estimations of the solubility obtained with other methodologies. Besides, two empirical simple rules have been obtained to have a rough estimate of the solubility of a certain model, by analyzing the ionic pairs formation as a function of molality and/or by calculating the difference between the NaCl solid chemical potential and the standard chemical potential of the salt in solution. PMID:27036458

  18. Assessing the potential hazard of chemical substances for the terrestrial environment. Development of hazard classification criteria and quantitative environmental indicators.

    PubMed

    Tarazona, J V; Fresno, A; Aycard, S; Ramos, C; Vega, M M; Carbonell, G

    2000-03-20

    Hazard assessment constitutes an essential tool in order to evaluate the potential effects of chemical substances on organisms and ecosystems. It includes as a first step, hazard identification, which must detect the potential dangers of the substance (i.e. the kind of effects that the substance may produce), and a second step to quantify each danger and to set the expected dose/response relationships. Hazard assessment plays a key role in the regulation of chemical substances, including pollution control and sustainable development. However, the aquatic environment has largely received more attention than terrestrial ecosystems. This paper presents the extrapolation of several basic concepts from the aquatic to the terrestrial compartment, and suggests possibilities for their regulatory use. Two specific proposals are discussed. The first focuses on the scientific basis of the hazard identification-classification criteria included in the EU regulations and their extrapolation to the terrestrial environment. The second focuses on the OECD programme for environmental indicators and the development of a soil pollution pressure indicator to quantify the potential hazards for the soil compartment and its associated terrestrial ecosystem related to the toxic chemicals applied deliberately (i.e. pesticides) or not (i.e. heavy metals in sludge-based fertilisers; industrial spills) to the soil. PMID:10803544

  19. Big data in chemical toxicity research: the use of high-throughput screening assays to identify potential toxicants.

    PubMed

    Zhu, Hao; Zhang, Jun; Kim, Marlene T; Boison, Abena; Sedykh, Alexander; Moran, Kimberlee

    2014-10-20

    High-throughput screening (HTS) assays that measure the in vitro toxicity of environmental compounds have been widely applied as an alternative to in vivo animal tests of chemical toxicity. Current HTS studies provide the community with rich toxicology information that has the potential to be integrated into toxicity research. The available in vitro toxicity data is updated daily in structured formats (e.g., deposited into PubChem and other data-sharing web portals) or in an unstructured way (papers, laboratory reports, toxicity Web site updates, etc.). The information derived from the current toxicity data is so large and complex that it becomes difficult to process using available database management tools or traditional data processing applications. For this reason, it is necessary to develop a big data approach when conducting modern chemical toxicity research. In vitro data for a compound, obtained from meaningful bioassays, can be viewed as a response profile that gives detailed information about the compound's ability to affect relevant biological proteins/receptors. This information is critical for the evaluation of complex bioactivities (e.g., animal toxicities) and grows rapidly as big data in toxicology communities. This review focuses mainly on the existing structured in vitro data (e.g., PubChem data sets) as response profiles for compounds of environmental interest (e.g., potential human/animal toxicants). Potential modeling and mining tools to use the current big data pool in chemical toxicity research are also described. PMID:25195622

  20. Shear viscosity, bulk viscosity, and relaxation times of causal dissipative relativistic fluid-dynamics at finite temperature and chemical potential

    NASA Astrophysics Data System (ADS)

    Huang, Xu-Guang; Koide, Tomoi

    2012-09-01

    The microscopic formulas for the shear viscosity η, the bulk viscosity ζ, and the corresponding relaxation times τπ and τΠ of causal dissipative relativistic fluid-dynamics are obtained at finite temperature and chemical potential by using the projection operator method. The non-triviality of the finite chemical potential calculation is attributed to the arbitrariness of the operator definition for the bulk viscous pressure. We show that, when the operator definition for the bulk viscous pressure Π is appropriately chosen, the leading-order result of the ratio, ζ over τΠ, coincides with the same ratio obtained at vanishing chemical potential. We further discuss the physical meaning of the time-convolutionless (TCL) approximation to the memory function, which is adopted to derive the main formulas. We show that the TCL approximation violates the time reversal symmetry appropriately and leads results consistent with the quantum master equation obtained by van Hove. Furthermore, this approximation can reproduce an exact relation for transport coefficients obtained by using the f-sum rule derived by Kadanoff and Martin. Our approach can reproduce also the result in Baier et al. (2008) [8] by taking into account the next-order correction to the TCL approximation, although this correction causes several problems.

  1. NUMERICAL ALGORITHMS AT NON-ZERO CHEMICAL POTENTIAL. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP, VOLUME 19

    SciTech Connect

    BLUM,T.

    1999-09-14

    The RIKEN BNL Research Center hosted its 19th workshop April 27th through May 1, 1999. The topic was Numerical Algorithms at Non-Zero Chemical Potential. QCD at a non-zero chemical potential (non-zero density) poses a long-standing unsolved challenge for lattice gauge theory. Indeed, it is the primary unresolved issue in the fundamental formulation of lattice gauge theory. The chemical potential renders conventional lattice actions complex, practically excluding the usual Monte Carlo techniques which rely on a positive definite measure for the partition function. This ''sign'' problem appears in a wide range of physical systems, ranging from strongly coupled electronic systems to QCD. The lack of a viable numerical technique at non-zero density is particularly acute since new exotic ''color superconducting'' phases of quark matter have recently been predicted in model calculations. A first principles confirmation of the phase diagram is desirable since experimental verification is not expected soon. At the workshop several proposals for new algorithms were made: cluster algorithms, direct simulation of Grassman variables, and a bosonization of the fermion determinant. All generated considerable discussion and seem worthy of continued investigation. Several interesting results using conventional algorithms were also presented: condensates in four fermion models, SU(2) gauge theory in fundamental and adjoint representations, and lessons learned from strong; coupling, non-zero temperature and heavy quarks applied to non-zero density simulations.

  2. Consensus on the solubility of NaCl in water from computer simulations using the chemical potential route

    NASA Astrophysics Data System (ADS)

    Benavides, A. L.; Aragones, J. L.; Vega, C.

    2016-03-01

    The solubility of NaCl in water is evaluated by using three force field models: Joung-Cheatham for NaCl dissolved in two different water models (SPC/E and TIP4P/2005) and Smith Dang NaCl model in SPC/E water. The methodology based on free-energy calculations [E. Sanz and C. Vega, J. Chem. Phys. 126, 014507 (2007)] and [J. L. Aragones et al., J. Chem. Phys. 136, 244508 (2012)] has been used, except, that all calculations for the NaCl in solution were obtained by using molecular dynamics simulations with the GROMACS package instead of homemade MC programs. We have explored new lower molalities and made longer runs to improve the accuracy of the calculations. Exploring the low molality region allowed us to obtain an analytical expression for the chemical potential of the ions in solution as a function of molality valid for a wider range of molalities, including the infinite dilute case. These new results are in better agreement with recent estimations of the solubility obtained with other methodologies. Besides, two empirical simple rules have been obtained to have a rough estimate of the solubility of a certain model, by analyzing the ionic pairs formation as a function of molality and/or by calculating the difference between the NaCl solid chemical potential and the standard chemical potential of the salt in solution.

  3. Drug Scene Syllabus, A Manual on Drugs and Volatile Chemical of Potential Abuse.

    ERIC Educational Resources Information Center

    Johnson, Robert B.; And Others

    A brief historical review of attempts to control the abuse of drugs introduces a series of tables listing pertinent information about drugs of potential abuse. Each table provides the common commercial and slang names for the drugs, their medical and legal classification, their potential for emotional and physical dependence, whether the user…

  4. Chemical composition and bioethanol potential of different plant species found in pacific northwest conservation buffers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increase in energy demand has led towards considering lignocellulosic feedstocks as potential for ethanol production. Aim of this study was to estimate the potential of grass straws from conservation reserve program (CRP) lands as feedstocks for ethanol production. The CRP was initiated to ensure re...

  5. Coordinating Chemical and Mineralogical Analyses of Antarctic Dry Valley Sediments as Potential Analogs for Mars

    NASA Technical Reports Server (NTRS)

    Patel, S. N.; Bishop, J. L.; Englert, P.; Gibson, E. K.

    2015-01-01

    The Antarctic Dry Valleys (ADV) provide a unique terrestrial analog for Martian surface processes as they are extremely cold and dry sedimentary environments. The surface geology and the chemical composition of the Dry Valleys that are similar to Mars suggest the possible presence of these soil-formation processes on Mars. The soils and sediments from Wright Valley, Antarctica were investigated in this study to examine mineralogical and chemical changes along the surface layer in this region and as a function of depth. Surface samples collected near Prospect Mesa and Don Juan Pond of the ADV were analyzed using visible/near-infrared (VNIR) and mid-IR reflectance spectroscopy and major and trace element abundances.

  6. Embedded Fragments from U.S. Military Personnel—Chemical Analysis and Potential Health Implications

    PubMed Central

    Centeno, José A.; Rogers, Duane A.; van der Voet, Gijsbert B.; Fornero, Elisa; Zhang, Lingsu; Mullick, Florabel G.; Chapman, Gail D.; Olabisi, Ayodele O.; Wagner, Dean J.; Stojadinovic, Alexander; Potter, Benjamin K.

    2014-01-01

    Background: The majority of modern war wounds are characterized by high-energy blast injuries containing a wide range of retained foreign materials of a metallic or composite nature. Health effects of retained fragments range from local or systemic toxicities to foreign body reactions or malignancies, and dependent on the chemical composition and corrosiveness of the fragments in vivo. Information obtained by chemical analysis of excised fragments can be used to guide clinical decisions regarding the need for fragment removal, to develop therapeutic interventions, and to better anticipate future medical problems from retained fragment related injuries. In response to this need, a new U.S Department of Defense (DoD) directive has been issued requiring characterization of all removed fragments to provide a database of fragment types occurring in combat injuries. Objectives: The objective of this study is to determine the chemical composition of retained embedded fragments removed from injured military personnel, and to relate results to histological findings in tissue adjacent to fragment material. Methods: We describe an approach for the chemical analysis and characterization of retained fragments and adjacent tissues, and include case examples describing fragments containing depleted uranium (DU), tungsten (W), lead (Pb), and non-metal foreign bodies composed of natural and composite materials. Fragments obtained from four patients with penetrating blast wounds to the limbs were studied employing a wide range of chemical and microscopy techniques. Available adjacent tissues from three of the cases were histologically, microscopically, and chemically examined. The physical and compositional properties of the removed foreign material surfaces were examined with energy dispersive x-ray fluorescence spectrometry (EDXRF), scanning electron microscopy (SEM), laser ablation inductively-coupled plasma mass-spectrometry (LA-ICP-MS), and confocal laser Raman

  7. Strategies and chemical design approaches to reduce the potential for formation of reactive metabolic species.

    PubMed

    Argikar, Upendra A; Mangold, James B; Harriman, Shawn P

    2011-01-01

    Metabolic activation of new chemical entities to reactive intermediates is routinely monitored in drug discovery and development. Reactive intermediates may bind to cellular macromolecules such as proteins, DNA and may eventually lead to cell death via necrosis, apoptosis or oxidative stress. The evidence that the ultimate outcome of metabolic activation is an adverse drug reaction manifested as in vivo toxicity, is at best circumstantial. However, understanding the process of bioactivation of structural alerts by trapping the reactive intermediates is critical to guide medicinal chemistry efforts in quest for safer and potent molecules. This commentary provides a brief introduction to adverse drug reactions and mechanisms of reactive intermediate formation for various functional groups, followed by a review of chemical design approaches, examples of such strategies, possible isosteric replacements for structural alerts and rationalization of laboratory approaches to determine reactive intermediates, as a guide to today's medicinal chemist. PMID:21320068

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

    PubMed

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

    2016-11-01

    PM10 was sampled at a suburban location affected by traffic and industry in the north of Spain. The samples were analysed to determine the chemical components of PM10 (organic and elemental carbon, soluble chemical species and metals). The aim of this study was to assess the toxicity of PM10 in terms of the bulk analysis and the physico-chemical properties of the particles. Total carbon, sulphates, ammonium, chlorides and nitrates were found to be the major constituents of PM10. The contribution of the last of these was found to increase significantly with PM10 concentration (Pearson coefficient correlation of 0.7, p-value < 0.001). Individual airborne particles were characterised morphologically and chemically via a combination of Scanning Electron Microscopy and Energy-Dispersive X-ray spectroscopy (SEM-EDX). The subsequent image analysis revealed C-rich particles with shapes that pointed to combustion processes. Moreover, carbonaceous particles seemed to act as vehicles for sulphur compounds and metals (S, Na, Fe, Ca, Mg, K, Al, Mn, Zn and Cu). Coarse particles were found to be mainly constituted by crustal material and marine and carbonaceous particles. Although most of the studied individual particles in PM10 samples (86.0%) had a diameter within the 0.1-2.5 μm range, 1.8% of them had sizes lower than 0.1 μm 40.2% of the total studied particles were estimated to be inhaled and deposited in the human respiratory tract; 12.3% of these particles would reach the deepest zones, thereby posing a major risk to human health. PMID:27485798

  9. Biomonitoring and whole body cotton dosimetry to estimate potential human dermal exposure to semivolatile chemicals.

    PubMed

    Krieger, R I; Bernard, C E; Dinoff, T M; Fell, L; Osimitz, T G; Ross, J H; Ongsinthusak, T

    2000-01-01

    Current methods of estimating absorbed dosage (AD) of chemicals were evaluated to determine residue transfer from a carpet treated with chlorpyrifos (CP) to humans who performed a structured exercise routine. To determine the dislodgeability of residue, a California Department of Food and Agriculture (CDFA) roller was applied to a flat cotton cloth upon a treated carpet. Levels ranged from 0.06 to 0.99 microg CP/cm2. Cotton whole body dosimeters (WBD) were also used to assess residue transfer. The dosimeters retained 1.5 to 38 mg CP/person. Urine biomonitoring (3 days) for 3,5,6-trichloro-2-pyridinol (TCP) of persons who wore only swimsuits revealed a mean AD of 176 microg CP equivalents/person. The results show that the AD depends on the extent of contact transfer and dermal absorption of the residue. Default exposure assessments based upon environmental levels of chemicals and hypothetical transport pathways predict excessive exposure. The cotton WBD retains chemical residues and may be effectively used to predict dermal dose under experimental conditions. PMID:10703847

  10. Impact of Environmental Chemicals on the Transcriptome of Primary Human Hepatocytes: Potential for Health Effects.

    PubMed

    Mitchell, Robert D; Dhammi, Anirudh; Wallace, Andrew; Hodgson, Ernest; Roe, R Michael

    2016-08-01

    New paradigms for human health risk assessment of environmental chemicals emphasize the use of molecular methods and human-derived cell lines. In this study, we examined the effects of the insect repellent DEET (N,N-diethyl-m-toluamide) and the phenylpyrazole insecticide fipronil (fluocyanobenpyrazole) on transcript levels in primary human hepatocytes. These chemicals were tested individually and as a mixture. RNA-Seq showed that 100 μM DEET significantly increased transcript levels (α = 0.05) for 108 genes and lowered transcript levels for 64 genes and fipronil at 10 μM increased the levels of 2246 transcripts and decreased the levels for 1428 transcripts. Fipronil was 21-times more effective than DEET in eliciting changes, even though the treatment concentration was 10-fold lower for fipronil versus DEET. The mixture of DEET and fipronil produced a more than additive effect (levels increased for 3017 transcripts and decreased for 2087 transcripts). The transcripts affected for all chemical treatments were classified by GO analysis and mapped to chromosomes. The overall treatment responses, specific pathways, and individual transcripts affected were discussed at different levels of fold-change. Changes found in transcript levels in response to treatments will require further research to understand their importance in overall cellular, organ, and organismic function. PMID:27091632

  11. High potential for chemical weathering and climate effects of early lichens and bryophytes in the Late Ordovician

    NASA Astrophysics Data System (ADS)

    Porada, Philipp; Lenton, Tim; Pohl, Alexandre; Weber, Bettina; Mander, Luke; Donnadieu, Yannick; Beer, Christian; Pöschl, Ulrich; Kleidon, Axel

    2016-04-01

    Non-vascular vegetation in the Late Ordovician may have considerably increased global chemical weathering, thereby reducing atmospheric CO2 concentration and contributing to a decrease in global temperature and the onset of glaciations. Usually, enhancement of weathering by non-vascular vegetation is estimated using field experiments which are limited to small areas and a low number of species. This makes it difficult to extrapolate to the global scale and to climatic conditions of the past, which differ markedly from the recent climate. Here we present a global, spatially explicit modelling approach to estimate chemical weathering by non-vascular vegetation in the Late Ordovician. During this period, vegetation probably consisted of early forms of today's lichens and bryophytes. We simulate these organisms with a process-based model, which takes into account their physiological diversity by representing multiple species. The productivity of lichens and bryophytes is then related to chemical weathering of surface rocks. The rationale is that the organisms dissolve rocks to extract phosphorus for the production of new biomass. To account for the limited supply of unweathered rock material in shallow regions, we cap biotic weathering at the erosion rate. We estimate a potential global weathering flux of 10.2 km3 yr‑1 of rock, which is around 12 times larger than today's global chemical weathering. The high weathering potential implies a considerable impact of lichens and bryophytes on atmospheric CO2 concentration in the Ordovician. Moreover, we find that biotic weathering is highly sensitive to atmospheric CO2, which suggests a strong feedback between chemical weathering by lichens and bryophytes and climate.

  12. Application of thermoelectric potential measurements in chemical analysis-II Determination of aluminium in iron alloys.

    PubMed

    Krajina, A; Dolezal, J

    1967-12-01

    A method is proposed for the rapid determination of aluminium in iron alloys by means of thermoelectric potential measurement. An instrument has been modified, and a method devised for thermoelectro-analytical measurements. The thermoelectric potential of iron-germanium and iron-zinc alloys has been measured, and an attempt made at a theoretical explanation of the influence of alloying elements on the thermoelectric properties of transition metals. PMID:18960250

  13. Simple, rapid zebrafish larva bioassay for assessing the potential of chemical pollutants and drugs to disrupt thyroid gland function.

    PubMed

    Raldúa, Demetrio; Babin, Patrick J

    2009-09-01

    Thyroid function may be altered by a very large number of chemicals routinely found in the environment Research evaluating potential thyroid disruption is ongoing, but there are thousands of synthetic and naturally occurring drugs and chemicals to be considered. European and United States policies call for the development of simple methodologies for screening endocrine-disrupting chemicals. Zebrafish are widely used as a model organism for assessing drug effects because of their small size, high fecundity, rapid organogenesis, morphological and physiological similarities to mammals, and easewithwhich large-scale phenotypic screening is performed. A zebrafish-based short-duration screening method was developed to detect the potential effect of chemicals and drugs on thyroid function. This method used a T4 immunofluorescence quantitative disruption test (TIQDT) to measure thyroid function. The 3 day exposure window protocol, from day 2 to day 5 postfertilization (dpf), avoided any potential side effects on thyroid gland morphogenesis. Methimazole, propylthiouracil, and potassium perchlorate, three well-known goitrogens, totally abolished T4 immunoreactivity in thyroid follicles in a dose-specific manner. Amiodarone, a human pharmaceutical with a reported cytotoxic effect on thyroid follicular cells, also decreased T4 levels. Moreover, exposure to 50 nM 3,3',5-triiodothyronine induced a significant decrease in T4 immunoreactivity as did DDT, 2,4-D, and 4-nonylphenol. In conclusion, these data indicated that TIQDT may be useful for obtaining initial information about the ability of environmental pollutants and drugs to impair thyroid gland function as well as assessing the combined effects of endocrine disruptors. PMID:19764258

  14. Evaluation of the degree of restoration of broken Wigner's SU(4) spin-isospin symmetry in nuclei

    NASA Astrophysics Data System (ADS)

    Nurmukhamedov, A. M.

    2012-01-01

    The Franzini-Radicati factor R was calculated on the basis of experimental data on the masses of nuclei in the mass-number range of 5 ≤ A ≤ 257. The values calculated for this factor made it possible to evaluate the degree of fulfillment of Wigner's SU(4) spin-isospin symmetry in nuclei. An expression for the factor R was obtained on the basis of Wigner's mass formula. This expression is isospin-dependent and takes into account odd-even variations in the mass. The formula for the factor R describes the separation of nuclei into threeWigner-type groups. The values calculated for the factor R were analyzed by the method of Student's t criterion, and it was inferred from the results of this analysis that only for nuclei having odd values of the mass number A and an isospin in the range of T z ≥ 53/2 is broken Wigner's SU(4) spin-isospin symmetry restored, the confidence level being α = 0.01.

  15. Potential halogenated industrial carcinogenic and mutagenic chemicals. II. Halogenated saturated hydrocarbons.

    PubMed

    Fishbein, L

    1979-03-01

    The halogenated saturated hydrocarbons analogously to the previously considered halogenated unsaturated hydrocarbons (Part I) possess considerable utility in a broad spectrum of applications including; solvents, dry-cleaning fluids, refrigerants, fumigants, degreasing agents, propellants and intermediates in the production of other chemicals, textiles and plastics. Methyl chloride, methylene chloride, chloroform, carbon tetrachloride, methyl chloroform, 1,1,2-trichloroethane, hexachloroethane, ethyl chloride and fluorocarbons were reviewed principally in terms of their synthesis (or occurrence), areas of application, stability, distribution, reactivity, levels of exposure, populations at risk, carcinogenicity, mutagenicity and metabolism. PMID:373115

  16. An assessment of clinical chemical sensing technology for potential use in space station health maintenance facility

    NASA Technical Reports Server (NTRS)

    1987-01-01

    A Health Maintenance Facility is currently under development for space station application which will provide capabilities equivalent to those found on Earth. This final report addresses the study of alternate means of diagnosis and evaluation of impaired tissue perfusion in a microgravity environment. Chemical data variables related to the dysfunction and the sensors required to measure these variables are reviewed. A technology survey outlines the ability of existing systems to meet these requirements. How the candidate sensing system was subjected to rigorous testing is explored to determine its suitability. Recommendations for follow-on activities are included that would make the commercial system more appropriate for space station applications.

  17. Potential energy surfaces for chemical reactions. Progress report, March 15, 1988--1989

    SciTech Connect

    Schaefer, H.F. III

    1995-01-01

    The crystal structure of two esters, both coupled bicyclo[1.1.0] butane derivatives, are found to have extremely short carbon-carbon central bonds (1.440-1.445 angstroms). The phenomena is tested by quantum mechanical methods since chemical experiments are not currently possible. Theoretical models employed were the minimum basis set (MBS), the standard double zeta(DZ), the double zeta plus d(DZ+d), the double zeta plus polarization(DZ+P), along with the self-consistent field method provide predictions for intra-cyclic bond lengths and angles including the central bond length.

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

    SciTech Connect

    Valerio, Luis G. . E-mail: luis.valerio@FDA.HHS.gov; Arvidson, Kirk B.; Chanderbhan, Ronald F.; Contrera, Joseph F.

    2007-07-01

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

  19. Investigation of potential health effects associated with well water chemical contamination in Londonderry Township, Pennsylvania, U.S.A.

    PubMed

    Logue, J N; Stroman, R M; Reid, D; Hayes, C W; Sivarajah, K

    1985-01-01

    A community health survey was conducted by the Pennsylvania Department of Health in Londonderry Township, Dauphin County, Pennsylvania, in response to concerns about potential health effects associated with residential exposure to chemical contaminants in well water. The data indicate that there were no observable adverse health effects in the exposed group of residents, compared with the control group, which could be ascribed to long-term, low-level exposure to trichloroethylene (TCE) and other volatile organic chemicals. Significantly more individuals in the exposed group than in the control group experienced eye irritation, diarrhea, and sleepiness during the 12-month period prior to the survey. This indicated the possibility of an association of contaminated water with the manifestation of symptoms. It is hypothesized that the increased rate of symptoms observed in the exposed group, when compared to the control group, may have been caused by one or more of the following factors: (1) effect of TCE at a threshold level higher than 28 ppb, (2) effect of a single chemical entity other than TCE, and (3) additive or synergistic effects of several chemicals. It is also possible that there are factors other than water contaminants associated with the recorded symptoms, e.g., stress, that may have had an important influence in the exposed group but not in the control group. PMID:4026385

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

    PubMed

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

    2016-08-15

    MERLIN-Expo merges and integrates advanced exposure assessment methodologies, allowing the building of complex scenarios involving several pollution sources and targets. The assessment of exposure and risks to human health from chemicals is of major concern for policy and ultimately benefits all citizens. The development and operational fusion of the advanced exposure assessment methodologies envisaged in the MERLIN-Expo tool will have a significant impact in the long term on several policies dealing with chemical safety management. There are more than 30 agencies in Europe related to exposure and risk evaluation of chemicals, which have an important role in implementing EU policies, having especially tasks of technical, scientific, operational and/or regulatory nature. The main purpose of the present paper is to introduce MERLIN-Expo and to highlight its potential for being effectively integrated within the group of tools available to assess the risk and exposure of chemicals for EU policy. The main results show that the tool is highly suitable for use in site-specific or local impact assessment, with minor modifications it can also be used for Plant Protection Products (PPPs), biocides and REACH, while major additions would be required for a comprehensive application in the field of consumer and worker exposure assessment. PMID:27107646

  1. Tuning Chemical Potential Difference across Alternately Doped Graphene p-n Junctions for High-Efficiency Photodetection.

    PubMed

    Lin, Li; Xu, Xiang; Yin, Jianbo; Sun, Jingyu; Tan, Zhenjun; Koh, Ai Leen; Wang, Huan; Peng, Hailin; Chen, Yulin; Liu, Zhongfan

    2016-07-13

    Being atomically thin, graphene-based p-n junctions hold great promise for applications in ultrasmall high-efficiency photodetectors. It is well-known that the efficiency of such photodetectors can be improved by optimizing the chemical potential difference of the graphene p-n junction. However, to date, such tuning has been limited to a few hundred millielectronvolts. To improve this critical parameter, here we report that using a temperature-controlled chemical vapor deposition process, we successfully achieved modulation-doped growth of an alternately nitrogen- and boron-doped graphene p-n junction with a tunable chemical potential difference up to 1 eV. Furthermore, such p-n junction structure can be prepared on a large scale with stable, uniform, and substitutional doping and exhibits a single-crystalline nature. This work provides a feasible method for synthesizing low-cost, large-scale, high efficiency graphene p-n junctions, thus facilitating their applications in optoelectronic and energy conversion devices. PMID:27351273

  2. hERGAPDbase: a database documenting hERG channel inhibitory potentials and APD-prolongation activities of chemical compounds.

    PubMed

    Hishigaki, Haretsugu; Kuhara, Satoru

    2011-01-01

    Drug-induced QT interval prolongation is one of the most common reasons for the withdrawal of drugs from the market. In the past decade, at least nine drugs, i.e. terfenadine, astemizole, grepafloxacin, terodiline, droperidol, lidoflazine, sertindole, levomethadyl and cisapride, have been removed from the market or their use has been severely restricted because of drug-induced QT interval prolongation. Therefore, this irregularity is a major safety concern in the case of drugs submitted for regulatory approval. The most common mechanism of drug-induced QT interval prolongation may be drug-related inhibition of the human ether-á-go-go-related gene (hERG) channel, which subsequently results in prolongation of the cardiac action potential duration (APD). hERGAPDbase is a database of electrophysiological experimental data documenting potential hERG channel inhibitory actions and the APD-prolongation activities of chemical compounds. All data entries are manually collected from scientific papers and curated by a person. With hERGAPDbase, we aim to provide useful information for chemical and pharmacological scientists and enable easy access to electrophysiological experimental data on chemical compounds. Database URL: http://www.grt.kyushu-u.ac.jp/hergapdbase/. PMID:21586548

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

    PubMed

    Gunaseelan, Victor Nallathambi

    2016-03-01

    In this study, the biochemical CH4 potential, rate, biodegradability, NaOH treatment and the influence of chemical composition on CH4 yield of yard wastes generated from seven trees were examined. All the plant parts were sampled for their chemical composition and subjected to the biochemical CH4 potential assay. The component parts exhibited significant variation in biochemical CH4 potential, which was reflected in their ultimate CH4 yields that ranged from 109 to 382 ml g(-1) volatile solids added and their rate constants that ranged from 0.042 to 0.173 d(-1). The biodegradability of the yard wastes ranged from 0.26 to 0.86. Variation in the biochemical CH4 potential of the yard wastes could be attributed to variation in the chemical composition of the different fractions. In the Thespesia yellow withered leaf, Tamarindus fruit pericarp and Albizia pod husk, NaOH treatment enhanced the ultimate CH4 yields by 17%, 77% and 63%, respectively, and biodegradability by 15%, 77% and 61%, respectively, compared with the untreated samples. The effectiveness of NaOH treatment varied for different yard wastes, depending on the amounts of acid detergent fibre content. Gliricidia petals, Prosopis leaf, inflorescence and immature pod, Tamarindus seeds, Albizia seeds, Cassia seeds and Delonix seeds exhibited CH4 yields higher than 300 ml g(-1) volatile solids added. Multiple linear regression models for predicting the ultimate CH4 yield and biodegradability of yard wastes were designed from the results of this work. PMID:26790450

  4. Chemical reactivity and long-range transport potential of polycyclic aromatic hydrocarbons--a review.

    PubMed

    Keyte, Ian J; Harrison, Roy M; Lammel, Gerhard

    2013-12-21

    Polycyclic aromatic hydrocarbons (PAHs) are of considerable concern due to their well-recognised toxicity and especially due to the carcinogenic hazard which they present. PAHs are semi-volatile and therefore partition between vapour and condensed phases in the atmosphere and both the vapour and particulate forms undergo chemical reactions. This article briefly reviews the current understanding of vapour-particle partitioning of PAHs and the PAH deposition processes, and in greater detail, their chemical reactions. PAHs are reactive towards a number of atmospheric oxidants, most notably the hydroxyl radical, ozone, the nitrate radical (NO3) and nitrogen dioxide. Rate coefficient data are reviewed for reactions of lower molecular weight PAH vapour with these species as well as for heterogeneous reactions of higher molecular weight compounds. Whereas the data for reactions of the 2-3-ring PAH vapour are quite extensive and generally consistent, such data are mostly lacking for the 4-ring PAHs and the heterogeneous rate data (5 and more rings), which are dependent on the substrate type and reaction conditions, are less comprehensive. The atmospheric reactions of PAH lead to the formation of oxy and nitro derivatives, reviewed here, too. Finally, the capacity of PAHs for long range transport and the results of numerical model studies are described. Research needs are identified. PMID:24077263

  5. Ranking the potential carcinogenic hazards to workers from exposures to chemicals that are tumorigenic in rodents

    SciTech Connect

    Gold, L.S.; Backman, G.M.; Hooper, N.K.; Peto, R.

    1987-12-01

    For 41 chemicals there exist both reasonable data on carcinogenic potency in experimental animals and also a defined Permissible Exposure Level (PEL), which is the upper limit of legally permissible chronic occupational exposure for US workers. These 41 agents are ranked by an index that compares the permitted chronic human exposure to the chronic dose rate that induces tumors in 50% of laboratory animals. This index, the Permitted Exposure/Rodent Potency index, or PERP, does not estimate absolute risks directly, but rather suggests the relative hazards that such substances may pose. The PERP values for these 41 substances differ by more than 100,000-fold from each other. The PERP does not take into account the actual level of exposure or the number of exposed workers. Nevertheless, it might be reasonable to give priority attention to the reduction of allowable worker exposures to substances that appear most hazardous by this index and that some workers may be exposed to full-time near the PEL. Ranked by PERP, these chemicals are: ethylene dibromide, ethylene dichloride, 1,3-butadiene, tetrachloroethylene, propylene oxide, chloroform, formaldehyde, methylene chloride, dioxane, and benzene.

  6. Potential effects of oil spills and other chemical pollutants on marine mammals occurring in Alaskan waters

    SciTech Connect

    Hansen, D.J.

    1985-01-01

    The outer continental shelf report describes and assesses the potential effects of oil spills and other contaminants on marine mammals that occur in Alaskan waters, assuming that a spill or contamination occurs. The report focuses primarily on the potential direct and indirect effects of oil spills on marine mammals and addresses both short-term effects that may occur at the time of contact with oil, and long-term effects that may occur long after contact with oil. The report also briefly reviews the literature on the potential effects of other contaminants such as heavy metals and organochlorines (DDT and PCB's) on marine mammals. The assessment concludes that sea otters, polar bears, fur seals, and very young seal pups could suffer serious or lethal effects if contact with oil occurred.

  7. Precision measurement of isospin diffusion in peripheral Sn+Sn collisions at 70 MeV/u

    NASA Astrophysics Data System (ADS)

    Winkelbauer, Jack Robert

    Much effort has been undertaken recently to improve constraints on the symmetry energy term in the Nuclear Equation of State (EOS). Specifically, the behavior of the symmetry energy above and below nuclear saturation density plays a significant role in the properties of neutron stars, the structure of heavy nuclei, and the dynamics of nuclear reactions. The tendency for neutrons to drift from a neutron-rich region to a neutron-deficient region during a peripheral collision of heavy nuclei is known as isospin diffusion, and has been previously shown to be a sensitive observable for the study of the symmetry energy at sub-saturation densities. Projectile fragmentation reactions with beams of 112,118,124Sn at 70MeV/u on targets of 112,118,124Sn have been measured at Michigan State University, in order to understand the effect of the isospin asymmetry on the reaction dynamics. Heavy fragments with Z > 20 were detected and isotopically identified using the S800 Spectrometer, and the momentum distributions of these fragments were reconstructed. Additionally, light charged particles and intermediate mass fragments were detected in an array of Si-CsI telescopes to simultaneously determine the isotopic distributions of fragments with Z < 8. The impact parameter of the collision was characterized by a measurement of the charged particle multiplicity in a 4pi scintillator array. These data provide a detailed picture of the evolution of the projectile-like residue over a range of isospin asymmetries and impact parameter. The measured yield ratios have been used to extract information about the diffusion of neutrons between the projectile and target during peripheral collisions. The validity of using isotopic yield ratios as a surrogate for the isospin asymmetry of the compound system are discussed, and the associated isospin diffusion results are presented.

  8. Thermo-chemical and biological conversion potential of various biomass feedstocks to ethanol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The goal of this study is to evaluate the potential and the economy of producing ethanol from gasification-fermentation of various biomass feedstocks. The biomass feedstocks include winter cover crops (wheat, rye, clover, hairy betch), summer cover crop (sunhemp), chicken litter, and woody biomass. ...

  9. Chemical and structural indicators for large redox potentials in Fe-based positive electrode materials.

    PubMed

    Melot, Brent C; Scanlon, David O; Reynaud, Marine; Rousse, Gwenaëlle; Chotard, Jean-Noël; Henry, Marc; Tarascon, Jean-Marie

    2014-07-23

    Li-ion batteries have enabled a revolution in the way portable consumer-electronics are powered and will play an important role as large-scale electrochemical storage applications like electric vehicles and grid-storage are developed. The ability to identify and design promising new positive insertion electrodes will be vital in continuing to push Li-ion technology to its fullest potential. Utilizing a combination of computational tools and structural analysis, we report new indicators which will facilitate the recognition of phases with the desired redox potential. Most importantly of these, we find there is a strong correlation between the presence of Li ions sitting in close-proximity to the redox center of polyanionic phases and the open circuit voltage in Fe-based cathodes. This common structural feature suggests that the bonding associated with Li may have a secondary inductive effect which increases the ionic character of Fe bonds beyond what is typically expected based purely on arguments of electronegativity associated with the polyanionic group. This correlation is supported by ab initio calculations which show the Bader charge increases (reflecting an increased ionicity) in a nearly linear fashion with the experimental cell potentials. These features are demonstrated to be consistent across a wide variety of compositions and structures and should help to facilitate the design of new, high-potential, and environmentally sustainable insertion electrodes. PMID:24588538

  10. Variation in chemical composition and allelopathic potential of mixoploid Trigonella foenum-graecum L. with developmental stages.

    PubMed

    Omezzine, Faten; Bouaziz, Mohamed; Simmonds, Monique S J; Haouala, Rabiaa

    2014-04-01

    This study was conducted to evaluate the influence of developmental stages (vegetative, flowering and fruiting) of mixoploid fenugreek aerial parts on their chemical composition and allelopathic potential, assessed on lettuce germination and seedling growth. Aqueous and organic extracts significantly delayed germination, reduced its rate and affected seedling growth. Ethyl acetate and methanol extracts of aerial parts harvested at vegetative stage were the most toxic for lettuce germination and seedling growth, respectively. LC-MS/MS analysis of T. foenum-graecum aerial parts methanolic extract showed nine different flavonol glycosides (quercetin and kaempferol glucosides). Chemical composition of aerial parts differed with the developmental stage; indeed, at the vegetative and fruiting stages, analysis revealed the presence of 9 compounds as compared to only 6 compounds at the flowering stage. Thus, it is necessary to follow the qualitative changes of allelochemicals production at different developmental stages to identify the most productive one. PMID:24262545

  11. The potential for chemical mixtures from the environment to enable the cancer hallmark of sustained proliferative signalling

    PubMed Central

    Engström, Wilhelm; Darbre, Philippa; Eriksson, Staffan; Gulliver, Linda; Hultman, Tove; Karamouzis, Michalis V.; Klaunig, James E.; Mehta, Rekha; Moorwood, Kim; Sanderson, Thomas; Sone, Hideko; Vadgama, Pankaj; Wagemaker, Gerard; Ward, Andrew; Singh, Neetu; Al-Mulla, Fahd; Al-Temaimi, Rabeah; Amedei, Amedeo; Colacci, Anna Maria; Vaccari, Monica; Mondello, Chiara; Scovassi, A. Ivana; Raju, Jayadev; Hamid, Roslida A.; Memeo, Lorenzo; Forte, Stefano; Roy, Rabindra; Woodrick, Jordan; Salem, Hosni K.; Ryan, Elizabeth; Brown, Dustin G.; Bisson, William H.

    2015-01-01

    The aim of this work is to review current knowledge relating the established cancer hallmark, sustained cell proliferation to the existence of chemicals present as low dose mixtures in the environment. Normal cell proliferation is under tight control, i.e. cells respond to a signal to proliferate, and although most cells continue to proliferate into adult life, the multiplication ceases once the stimulatory signal disappears or if the cells are exposed to growth inhibitory signals. Under such circumstances, normal cells remain quiescent until they are stimulated to resume further proliferation. In contrast, tumour cells are unable to halt proliferation, either when subjected to growth inhibitory signals or in the absence of growth stimulatory signals. Environmental chemicals with carcinogenic potential may cause sustained cell proliferation by interfering with some cell proliferation control mechanisms committing cells to an indefinite proliferative span. PMID:26106143

  12. An overview on chemical aspects and potential health benefits of limonoids and their derivatives.

    PubMed

    Tundis, Rosa; Loizzo, Monica Rosa; Menichini, Francesco

    2014-01-01

    Limonoids are heavily oxygenated, modified triterpenes dominant in Meliaceae and Rutaceae plant families. The term 'limonoid' is derived from limonin, which was first identified as the bitter constituent of Citrus seeds in 1841. This group of secondary metabolites exhibits a wide range of biological properties, including anticancer, antibacterial, antifungal, antimalarial, and antiviral activities. Significant progress on the role of limonoids as promising candidates for cancer chemoprevention and/or therapy has been achieved in particular in recent years. The aim of this review article is to discuss the recent developments on limonoids chemical aspects and biological activities with the relationship between structure and activity, supporting the new possibilities for the medicinal and/or nutraceutical use of these compounds. PMID:24188270

  13. Prebiotic coordination chemistry: The potential role of transition-metal complexes in the chemical evolution

    NASA Technical Reports Server (NTRS)

    Beck, M.

    1979-01-01

    In approaching the extremely involved and complex problem of the origin of life, consideration of the coordination chemistry appeared not only as a possibility but as a necessity. The first model experiments appear to be promising because of prebiotic-type synthesis by means of transition-metal complexes. It is especially significant that in some instances various types of vitally important substances (nucleic bases, amino acids) are formed simultaneously. There is ground to hope that systematic studies in this field will clarify the role of transition-metal complexes in the organizatorial phase of chemical evolution. It is obvious that researchers working in the fields of the chemistry of cyano and carbonyl complexes, and of the catalytic effect of transition-metal complexes are best suited to study these aspects of the attractive and interesting problem of the origin of life.

  14. Chemical Characteristics, Synthetic Methods, and Biological Potential of Quinazoline and Quinazolinone Derivatives

    PubMed Central

    2014-01-01

    The heterocyclic fused rings quinazoline and quinazolinone have drawn a huge consideration owing to their expanded applications in the field of pharmaceutical chemistry. Quinazoline and quinazolinone are reported for their diversified biological activities and compounds with different substitutions bring together to knowledge of a target with understanding of the molecule types that might interact with the target receptors. Quinazolines and quinazolinones are considered as an important chemical for the synthesis of various physiological significance and pharmacological utilized molecules. Quinazolines and quinazolinone are a large class of biologically active compounds that exhibited broad spectrum of biological activities such as anti-HIV, anticancer, antifungal, antibacterial, antimutagenic, anticoccidial, anticonvulsant, anti-inflammatory, antidepressant, antimalarial, antioxidant, antileukemic, and antileishmanial activities and other activities. Being considered as advantaged scaffold, the alteration is made with different substituent. PMID:25692041

  15. Isospin asymmetries in B→(K*,ρ)γ/l+l- and B→Kl+l- in and beyond the standard model

    NASA Astrophysics Data System (ADS)

    Lyon, James; Zwicky, Roman

    2013-11-01

    We compute the isospin asymmetries in B→(K*,ρ)γ and B→(K,K*,ρ)l+l- for low lepton pair invariant mass q2, within the Standard Model (SM) and beyond the SM in a generic dimension six operator basis. Within the SM the CP-averaged isospin asymmetries for B→(K,K*,ρ)ll, between 1GeV2≤q2≤4mc2, are predicted to be small (below 1.5%) though with significant cancellation. In the SM the non-CP-averaged asymmetries for B→ρll deviate by ≈±5% from the CP-averaged ones. We provide physical arguments, based on resonances, of why isospin asymmetries have to decrease for large q2 (towards the endpoint). Two types of isospin violating effects are computed: ultraviolet isospin violation due to differences between operators coupling to up and down quarks, and infrared isospin violation where a photon is emitted from the spectator quark and is hence proportional to the difference between the up- and down-quark charges. These isospin violating processes may be subdivided into weak annihilation (WA), quark loop spectator scattering, and a chromomagnetic contribution. Furthermore we discuss generic selection rules based on parity and angular momentum for the B→Kll transition as well as specific selection rules valid for WA at leading order in the strong coupling constant. We clarify that the relation between the K and the longitudinal part of the K* only holds for leading twist and for left-handed currents. In general the B→ρll and B→K*ll isospin asymmetries are structurally different yet the closeness of αCKM to 90° allows us to construct a (quasi)null test for the SM out of the respective isospin symmetries. We provide and discuss an update on B(B0→K*0γ)/B(Bs→ϕγ) which is sensitive to WA.

  16. Chemical composition and antifungal potential of Brazilian propolis against Candida spp.

    PubMed

    Freires, I A; Queiroz, V C P P; Furletti, V F; Ikegaki, M; de Alencar, S M; Duarte, M C T; Rosalen, P L

    2016-06-01

    Propolis is known to have biological properties against numerous microorganisms of clinical interest. This study aimed to determine the chemical composition and antifungal activity of Brazilian propolis (types 3 and 13) against Candida spp. and their effects on the morphology of preformed and mature Candida biofilms. Samples of propolis (3 and 13) collected by Apis mellifera honeybees were obtained from different regions in Brazil. Ethanolic extracts of propolis (EEP) were prepared, fractionated and submitted to chemical analysis by GC/MS. The extracts and their hexane, dichloromethane and ethyl acetate fractions were tested for their ability to inhibit Candida spp. (C. albicans, C. dubliniensis, C. glabrata, C. kruzei, C. tropicalis and C. parapsilosis) by determination of the minimum inhibitory and fungicidal concentrations (MIC/MFC). Additionally, their effects on morphology of preformed and mature biofilms were observed by scanning electron microscopy. The phenolic compounds p-coumaric acid, caffeic acid phenethyl ester (CAPE), kaempferol and quercetin were identified in the EEP-3 and its bioactive dichloromethane fraction; and isoflavonoids such as medicarpin, vestitol and formononetin were found in the EEP-13, and triterpenes in its bioactive hexane fraction. The EEP-3 and EEP-13 and their bioactive fractions showed MIC values ranging from 0.2 to 125μg/mL and MFC values between 125 and 500μg/mL. The EEP and fractions were predominantly fungistatic agents. All extracts and fractions disrupted biofilm structures at 500μg/mL and amorphous areas with cell damage were clearly observed in preformed and mature biofilms. Propolis types 3 and 13 have strong anti-Candida activity and should be considered as promising candidates to treat oral and systemic candidiasis. PMID:26916845

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

    SciTech Connect

    Diaz, A.F.; Modestino, A.J.; Howard, J.B.

    1995-12-31

    Diversification of the raw materials base for manufacturing premium fuels and chemicals offers U.S. and international consumers economic and strategic benefits. Extensive reserves of natural gas in the world provide a valuable source of clean gaseous fuel and chemical feedstock. Assuming the availability of suitable conversion processes, natural gas offers the prospect of improving flexibility in liquid fuels and chemicals manufacture, and thus, the opportunity to complement, supplement, or displace petroleum-based production as economic and strategic considerations require. The composition of natural gas varies from reservoir to reservoir but the principal hydrocarbon constituent is always methane (CH{sub 4}). With its high hydrogen-to-carbon ratio, methane has the potential to produce hydrogen or hydrogen-rich products. However, methane is a very chemically stable molecule and, thus, is not readily transformed to other molecules or easily reformed to its elements (H{sub 2} and carbon). In many cases, further research is needed to augment selectivity to desired product(s), increase single-pass conversions, or improve economics (e.g. there have been estimates of $50/bbl or more for liquid products) before the full potential of these methodologies can be realized on a commercial scale. With the trade-off between gas conversion and product selectivity, a major challenge common to many of these technologies is to simultaneously achieve high methane single-pass conversions and high selectivity to desired products. Based on the results of the scoping runs, there appears to be strong indications that a breakthrough has finally been achieved in that synthesis of magnesium carbides from MgO and methane in the arc discharge reactor has been demonstrated.

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

    PubMed

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

    2015-11-01

    Since the need for raw materials in countries undergoing industrialisation (like China) is rising, the availability of metal and fossil fuel energy resources (like ores or coal) has changed in recent years. Landfill sites can contain considerable amounts of recyclables and energy-recoverable materials, therefore, landfill mining is an option for exploiting dumped secondary raw materials, saving primary sources. For the purposes of this article, two sanitary landfill sites have been chosen for obtaining actual data to determine the resource potential of Austrian landfills. To evaluate how pretreating waste before disposal affects the resource potential of landfills, the first landfill site has been selected because it has received untreated waste, whereas mechanically-biologically treated waste was dumped in the second. The scope of this investigation comprised: (1) waste characterisation by sorting analyses of recovered waste; and (2) chemical analyses of specific waste fractions for quality assessment regarding potential energy recovery by using it as solid recovered fuels. The content of eight heavy metals and the net calorific values were determined for the chemical characterisation tests. PMID:26347181

  19. Analysis of experimental data on nuclear masses within Wigner spin-isospin SU(4) symmetry

    SciTech Connect

    Nurmukhamedov, A. M.

    2009-03-15

    The problem of the realization of Wigner spin-isospin SU(4) symmetry in nuclei is analyzed on the basis of available experimental data on nuclide masses in the mass-number range 1 {<=} A {<=} 257. Empirical expressions are obtained for the universal functions in the Wigner mass formula. The experimental values of the energy of spin-orbit interaction are determined for the aforementioned nuclides. An alternative mechanism of the origin of the odd-even effect in nuclei having an even mass number associated with a specific property of the Casimir operator is proposed. The results obtained in this study suggest that SU(4) symmetry is broken predominantly by spin-orbit interaction.

  20. Dipolar degrees of freedom and isospin equilibration processes in heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Papa, M.; Berceanu, I.; Acosta, L.; Amorini, F.; Agodi, C.; Anzalone, A.; Auditore, L.; Cardella, G.; Cavallaro, S.; Chatterjee, M. B.; De Filippo, E.; Francalanza, L.; Geraci, E.; Grassi, L.; Gnoffo, B.; Han, J.; La Guidara, E.; Lanzalone, G.; Lombardo, I.; Maiolino, C.; Minniti, T.; Pagano, A.; Pagano, E. V.; Pirrone, S.; Politi, G.; Porto, F.; Quattrocchi, L.; Rizzo, F.; Rosato, E.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.

    2015-04-01

    The dipolar degrees of freedom on the 48Ca+27Al system at 40 MeV/nucleon have been investigated for the first time with the 4 π multidetector CHIMERA. The global variable was measured for well-reconstructed events in binary dissipative processes. Both the close link with isospin equilibration processes and its insensitivity to later statistical hot source decays have been discussed. This latter feature provides the opportunity to investigate globally and exclusively the dynamics of the equilibration processes. At this first level of investigation the experimental evidence, supported by the study of the reference system 27Al+40Ca and the auxiliary one 27Ca+48Ca , substantially agree with the CoMD-III calculations by describing the isovectorial forces through stiffness parameter values γ ≈0.8 -1.2 .

  1. 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.

  2. Direct CP, Lepton Flavor, and Isospin Asymmetries in the Decays B→K(*)l+l-

    NASA Astrophysics Data System (ADS)

    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.

    2009-03-01

    We measure branching fractions and integrated rate asymmetries for the rare decays B→K(*)l+l-, where l+l- is either e+e- or μ+μ-, using a sample of 384×106 B Bmacr 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/ψ resonance, we find evidence for unexpectedly large isospin asymmetries in both B→Kl+l- and B→K*l+l- which differ, respectively, by 3.2σ and 2.7σ, including systematic uncertainties, from the standard model expectations.

  3. 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.

  4. The phase-shift of isospin-2 pi-pi scattering from lattice QCD

    SciTech Connect

    Jozef J. Dudek, Robert G. Edwards, Michael J. Peardon, David G. Richards, Christopher E. Thomas

    2011-04-01

    Finite-volume lattice QCD calculations offer the possibility of extracting resonance parameters from the energy-dependent elastic phase-shift computed using the L\\"uscher technique. In this letter, as a trial of the method, we report on the extraction of the non-resonant phase-shift for $S$ and $D$-wave $\\pi\\pi$ isospin-2 scattering from dynamical lattice QCD computations. We define a variational basis of operators resembling pairs of pions of definite relative momentum and extract a spectrum of excited states that maps to phase-shifts at a set of discrete scattering momenta. Computations are performed with pion masses between $400$ and $520$ MeV on multiple spatial volumes. We observe no significant quark mass dependence in the phase-shifts extracted which are in reasonable agreement with the available experimental data at low momentum.

  5. 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.

  6. 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.

  7. Measurement of Branching Fractions and CP and Isospin Asymmetries of B -> K* g

    SciTech Connect

    Yarritu, A.; /SLAC

    2008-08-20

    We present a preliminary analysis of the decays B{sup 0} {yields} K*{sup 0}{gamma} and B{sup +} {yields} K*{sup +}{gamma} using a sample of 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}) = (4.58 {+-} 0.10 {+-} 0.16) x 10{sup -5} and {Beta}(B{sup +} {yields} K*{sup +}{gamma}) = (4.73 {+-} 0.15 {+-} 0.17) x 10{sup -5}. We measure the direct CP asymmetry to be -0.043 < {Alpha}(B {yields} K*{gamma}) < 0.025 and the isospin asymmetry to be -0.021 < {Delta}{sub 0-} < 0.079, where the limits are determined at the 90% confidence interval and include both the statistical and systematic uncertainties.

  8. 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

    2009-03-01

    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. PMID:19392508

  9. Isospin Symmetry Along The N=Z Line In The sd Shell

    SciTech Connect

    Della Vedova, F.; Lenzi, S. M.; Farnea, E.; Nespolo, M.; Bazzacco, D.; Brandolini, F.; Lunardi, S.; Menegazzo, R.; Rossi Alvarez, C.; Ur, C.A.; Ionescu-Bujor, M.; Bucurescu, D.; Iordachescu, A.; Marginean, N.; De Angelis, G.; Axiotis, M.; Napoli, D. R.; Bizzeti-Sona, A.; Bizzeti, P.G.

    2005-04-05

    Excited states have been studied in sd-shell nuclei following the 16O (70 MeV) + 24Mg (400 {mu}g/cm2) fusion-evaporation reaction. The GASP spectrometer in conjunction with the charged-particle detector ISIS and the Neutron ring allowed the detection of the {gamma}-rays in coincidence with evaporated light particles. New data on the mirror pairs A=31 and A=35 have been obtained. In particular, the comparison between the level schemes of 35Ar and 35Cl has confirmed the importance of the electromagnetic spin-orbit term, which explains the large Mirror Energy Difference values. Evidence of isospin mixing can be deduced from the E1 transitions.

  10. Phase shift of isospin-2 {pi}{pi} scattering from lattice QCD

    SciTech Connect

    Dudek, Jozef J.; Edwards, Robert G.; Richards, David G.; Thomas, Christopher E.; Peardon, Michael J.

    2011-04-01

    Finite-volume lattice QCD calculations offer the possibility of extracting resonance parameters from the energy-dependent elastic phase-shift computed using the Luescher technique. In this letter, as a trial of the method, we report on the extraction of the nonresonant phase-shift for S and D-wave {pi}{pi} isospin-2 scattering from dynamical lattice QCD computations. We define a variational basis of operators resembling pairs of pions of definite relative momentum and extract a spectrum of excited states that maps to phase-shifts at a set of discrete scattering momenta. Computations are performed with pion masses between 400 and 520 MeV on multiple spatial volumes. We observe no significant quark mass dependence in the phase-shifts extracted which are in reasonable agreement with the available experimental data at low momentum.

  11. 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.

  12. Measurement of B-->K{*}(892)gamma branching fractions and CP and Isospin asymmetries.

    PubMed

    Aubert, B; Karyotakis, Y; Lees, J P; Poireau, V; Prencipe, E; Prudent, X; Tisserand, V; Garra Tico, J; Grauges, E; Martinelli, M; Palano, A; Pappagallo, M; Eigen, G; Stugu, B; Sun, L; Battaglia, M; Brown, D N; Kerth, L T; Kolomensky, Yu G; Lynch, G; Osipenkov, I L; Tackmann, K; Tanabe, T; Hawkes, C M; Soni, N; Watson, A T; Koch, H; Schroeder, T; Asgeirsson, D J; Fulsom, B G; Hearty, C; Mattison, T S; McKenna, J A; Barrett, M; Khan, A; Randle-Conde, 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; Atmacan, H; Gary, J W; Liu, F; Long, O; 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; Heusch, C A; Kroseberg, J; Lockman, W S; Martinez, A J; Schalk, T; Schumm, B A; Seiden, A; Wang, L; 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; Wagner, S R; Ayad, R; Toki, W H; Wilson, R J; Feltresi, E; Hauke, A; Jasper, H; Karbach, T M; Merkel, J; Petzold, A; Spaan, B; Wacker, K; Kobel, M J; Nogowski, R; Schubert, K R; Schwierz, R; Volk, A; Bernard, D; Latour, E; Verderi, M; Clark, P J; Playfer, S; Watson, J E; Andreotti, M; Bettoni, D; Bozzi, C; Calabrese, R; Cecchi, A; Cibinetto, G; Fioravanti, E; Franchini, P; Luppi, E; Munerato, M; 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; Contri, R; Guido, E; Lo Vetere, M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Tosi, S; Chaisanguanthum, K S; Morii, M; Adametz, A; Marks, J; Schenk, S; Uwer, U; Bernlochner, F U; Klose, V; Lacker, H M; Bard, D J; Dauncey, P D; Tibbetts, M; Behera, P K; Charles, M J; Mallik, U; Cochran, J; Crawley, H B; Dong, L; Eyges, V; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Gao, Y Y; Gritsan, A V; Guo, Z J; Arnaud, N; Béquilleux, J; D'Orazio, A; Davier, M; Derkach, D; Firmino da Costa, J; Grosdidier, G; Le Diberder, F; Lepeltier, V; Lutz, A M; Malaescu, B; 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; Di Lodovico, F; Sacco, R; Sigamani, M; Cowan, G; Paramesvaran, S; Wren, A C; Brown, D N; Davis, C L; Denig, A G; Fritsch, M; Gradl, W; Hafner, A; Alwyn, K E; Bailey, D; Barlow, R J; 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; Salvati, E; Saremi, S; Cowan, R; Dujmic, D; Fisher, P H; Henderson, S W; Sciolla, G; Spitznagel, M; Yamamoto, R K; Zhao, M; Patel, P M; Robertson, S H; Schram, M; Lazzaro, A; Lombardo, V; Palombo, F; Stracka, S; Bauer, J M; Cremaldi, L; Godang, R; Kroeger, R; Sonnek, P; Summers, D J; Zhao, H W; Simard, M; Taras, P; 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; 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; Bonneaud, G R; Briand, H; Chauveau, J; Hamon, O; Leruste, Ph; Marchiori, G; Ocariz, J; Perez, A; Prendki, J; Sitt, S; Gladney, L; Biasini, M; Manoni, E; Angelini, C; Batignani, G; Bettarini, S; Calderini, G; Carpinelli, M; Cervelli, A; Forti, F; Giorgi, M A; Lusiani, A; 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; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Jackson, P D; Li Gioi, L; Mazzoni, M A; Morganti, S; Piredda, G; Renga, F; Voena, C; Ebert, M; Hartmann, T; Schröder, H; Waldi, R; Adye, T; Franek, B; Olaiya, E O; Wilson, F F; Emery, S; Esteve, L; Hamel de Monchenault, G; Kozanecki, W; Vasseur, G; Yèche, Ch; Zito, M; Allen, M T; Aston, D; Bartoldus, R; 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; Franco Sevilla, M; Gabareen, A M; 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; 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; Young, C C; Ziegler, V; Chen, X R; Liu, H; Park, W; Purohit, M V; White, R M; Wilson, J R; Burchat, P R; Edwards, A J; Miyashita, T S; Ahmed, S; Alam, M S; Ernst, J A; Pan, B; Saeed, M A; Zain, S B; Soffer, A; Spanier, S M; Wogsland, B J; Eckmann, R; Ritchie, J L; Ruland, A M; Schilling, C J; Schwitters, R F; Wray, B C; 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; King, G J; 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; Puccio, E M T; Band, H R; Chen, X; Dasu, S; Flood, K T; Pan, Y; Prepost, R; Vuosalo, C O; Wu, S L

    2009-11-20

    We present an analysis of the decays B{0}-->K{*0}(892)gamma and B{+}-->K{*+}(892)gamma using a sample of about 383 x 10{6} BB[-over ] events collected with the BABAR detector at the PEP-II asymmetric energy B factory. We measure the branching fractions B(B{0}-->K{*0}gamma)=(4.47+/-0.10+/-0.16) x 10{-5} and B(B{+}-->K{*+}gamma)=(4.22+/-0.14+/-0.16) x 10{-5}. We constrain the direct CP asymmetry to be -0.033K{*}gamma)<0.028 and the isospin asymmetry to be 0.017

  13. ATLAS diboson excesses as an evidence for a heavy WW resonance with the weak isospin 2

    NASA Astrophysics Data System (ADS)

    Arbuzov, Boris A.; Zaitsev, Ivan V.

    2015-12-01

    Recently reported diboson excesses at LHC are interpreted as indications for heavy resonance with weak isospin 2 due to would-be anomalous interaction of the weak bosons, which is defined by a constant λ. In the framework of an approach to the spontaneous generation of such interaction, we obtain estimates for the effect, which qualitatively agrees with ATLAS data. Effects are predicted in inclusive production of W+W+, W+(Z,γ), W+W-, (Z,γ)(Z,γ), W-(Z,γ), W-W- resonances in the vicinity of MR ≃ 2TeV, which could be reliably checked at the upgraded LHC with s = 13TeV.

  14. 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.

  15. Isospin coherence and final-state scattering of a disoriented chiral condensate

    SciTech Connect

    Huang, Z.; Suzuki, M.

    1995-09-01

    We examine the validity of the notion of the coherent state for pions and the quantum scattering effect in the final state of pion emission. When the number of particles is large, the effect caused by the small but finite mass difference between the neutral and charged pions can add up substantially in the quantum evolution of an initially coherent state. As a result, the states with quite different numbers of neutral or charged pions are essentially {ital incoherent}. The importance of the quantum scattering in the final-state isospin charge distribution of a disoriented chiral condensate (DCC) is investigated. We find that the scattering effect significantly reduces the spectacular Centauro and anti-Centauro events. A deformation of the charge distribution {ital dP}/{ital df} predicted by the classical field theory is significant only for a DCC with a size of 10 fm or more.

  16. A three-tier QSAR modeling strategy for estimating eye irritation potential of diverse chemicals in rabbit for regulatory purposes.

    PubMed

    Basant, Nikita; Gupta, Shikha; Singh, Kunwar P

    2016-06-01

    Experimental determination of the eye irritation potential (EIP) of chemicals is not only tedious, time and resource intensive, it involves cruelty to test animals. In this study, we have established a three-tier QSAR modeling strategy for estimating the EIP of chemicals for the use of pharmaceutical industry and regulatory agencies. Accordingly, a qualitative (binary classification: irritating, non-irritating), semi-quantitative (four-category classification), and quantitative (regression) QSAR models employing the SDT, DTF, and DTB methods were developed for predicting the EIP of chemicals in accordance with the OECD guidelines. Structural features of chemicals responsible for eye irritation were extracted and used in QSAR analysis. The external predictive power of the developed QSAR models were evaluated through the internal and external validation procedures recommended in QSAR literature. In test data, the two and four category classification QSAR models (DTF, DTB) rendered accuracy of >93%, while the regression QSAR models (DTF, DTB) yielded correlation (R(2)) of >0.92 between the measured and predicted EIPs. Values of various statistical validation coefficients derived for the test data were above their respective threshold limits (except rm(2) in DTF), thus put a high confidence in this analysis. The applicability domain of the constructed QSAR models were defined using the descriptors range and leverage approaches. The QSAR models in this study performed better than any of the previous studies. The results suggest that the developed QSAR models can reliably predict the EIP of diverse chemicals and can be useful tools for screening of candidate molecules in the drug development process. PMID:27018829

  17. Transport of chemical and microbial compounds from known wastewater discharges: Potential for use as indicators of human fecal contamination

    USGS Publications Warehouse

    Glassmeyer, S.T.; Furlong, E.T.; Kolpin, D.W.; Cahill, J.D.; Zaugg, S.D.; Werner, S.L.; Meyer, M.T.; Kryak, D.D.

    2005-01-01

    The quality of drinking and recreational water is currently (2005) determined using indicator bacteria. However, the culture tests used to analyze for these bacteria require a long time to complete and do not discriminate between human and animal fecal material sources. One complementary approach is to use chemicals found in human wastewater, which would have the advantages of (1) potentially shorter analysis times than the bacterial culture tests and (2) being selected for human-source specificity. At 10 locations, water samples were collected upstream and at two successive points downstream from a wastewaster treatment plant (WWTP); a treated effluent sample was also collected at each WWTP. This sampling plan was used to determine the persistence of a chemically diverse suite of emerging contaminants in streams. Samples were also collected at two reference locations assumed to have minimal human impacts. Of the 110 chemical analytes investigated in this project, 78 were detected at least once. The number of compounds in a given sample ranged from 3 at a reference location to 50 in a WWTP effluent sample. The total analyte load at each location varied from 0.018 μg/L at the reference location to 97.7 μg/L in a separate WWTP effluent sample. Although most of the compound concentrations were in the range of 0.01−1.0 μg/L, in some samples, individual concentrations were in the range of 5−38 μg/L. The concentrations of the majority of the chemicals present in the samples generally followed the expected trend:  they were either nonexistent or at trace levels in the upstream samples, had their maximum concentrations in the WWTP effluent samples, and then declined in the two downstream samples. This research suggests that selected chemicals are useful as tracers of human wastewater discharge.

  18. ToxAlerts: A Web Server of Structural Alerts for Toxic Chemicals and Compounds with Potential Adverse Reactions

    PubMed Central

    2012-01-01

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

  19. Physico-chemical analysis and antimicrobial potential of Apis dorsata, Apis mellifera and Ziziphus jujube honey samples from Pakistan

    PubMed Central

    Fahim, Hira; Dasti, Javid Iqbal; Ali, Ihsan; Ahmed, Safia; Nadeem, Muhammad

    2014-01-01

    Objective To evaluate physico-chemical properties and antimicrobial potential of indigenous honey samples against different reference strains including Escherichia coli ATCC 8739, Enterobacter aerogenes ATCC 13048, Pseudomonas aeroginosa ATCC 9027, Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 25923, Salmonella typhi ATCC 14028, Klebsiella pneumonia ATCC 13883, Aspergillus niger ATCC 16404, Rhizopus oligosporus PCSIR1, Candida albicans ATCC 14053 and Candida utilis ATCC 9950. Methods By using standard methods samples were evaluated for their antimicrobial properties including additive effect of starch and non-peroxidase activity, antioxidative properties (phenol contents, flavonoid contents, 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity). Prior to this evaluation, complete physico-chemical properties including pH, color, ash contents, protein contents, moisture contents, hydroxymethyl furfural contents, total sugar contents, reducing sugar and non-reducing sugar contents were analyzed. Results Relatively higher ash contents were found in the Siddar honey i.e. (0.590 0±0.033 6)% and small honey showed relatively higher protein contents i.e. (777.598±9.880) mg/kg. The moisture contents of tested honey samples ranged between 13.8%-16.6%, total sugar contents from 61.672%-72.420% and non-reducing sugar contents from 1.95%-3.93%. Presences of phenolic contents indicate higher antioxidant potential of these honey samples. All bacteria showed clear inhibition zones in response to tested honey samples whereas fungi and yeast showed inhibition at higher concentrations of these honey samples. For Escherichia coli, Bacillus subtilis, Salmonella typhi, Pseudomonas aeroginosa and Aspergillus niger, overall the small honey showed the higher activity than other honey samples. Conclusion Physico-chemical analysis of honey samples confirmed good quality of honey according to the standards set by European Union Commission and Codex Alimentarius Commission

  20. Phase diagram of Script N = 4 super-Yang-Mills theory with R-symmetry chemical potentials

    NASA Astrophysics Data System (ADS)

    Yamada, Daisuke; Yaffe, Laurence G.

    2006-09-01

    The phase diagram of large Nc, weakly-coupled Script N = 4 supersymmetric Yang-Mills theory on a three-sphere with non-zero chemical potentials is examined. In the zero coupling limit, a transition line in the μ-T plane is found, separating a ``confined'' phase in which the Polyakov loop has vanishing expectation value from a ``deconfined'' phase in which this order parameter is non-zero. For non-zero but weak coupling, perturbative methods may be used to construct a dimensionally reduced effective theory valid for sufficiently high temperature. If the maximal chemical potential exceeds a critical value, then the free energy becomes unbounded below and no genuine equilibrium state exists. However, the deconfined plasma phase remains metastable, with a lifetime which grows exponentially with Nc (not Nc2). This metastable phase persists with increasing chemical potential until a phase boundary, analogous to a spinodal decomposition line, is reached. Beyond this point, no long-lived locally stable quasi-equilibrium state exists. The resulting picture for the phase diagram of the weakly coupled theory is compared with results believed to hold in the strongly coupled limit of the theory, based on the AdS/CFT correspondence and the study of charged black hole thermodynamics. The confinement/deconfinement phase transition at weak coupling is in qualitative agreement with the Hawking-Page phase transition in the gravity dual of the strongly coupled theory. The black hole thermodynamic instability line may be the counterpart of the spinodal decomposition phase boundary found at weak coupling, but no black hole tunneling instability, analogous to the instability of the weakly coupled plasma phase is currently known.

  1. Chemical and Physical Approaches to Extend the Replicative and Differentiation Potential of Stem Cells.

    PubMed

    Hwang, Eun Seong; Ok, Jeong Soo; Song, SeonBeom

    2016-06-01

    Cell therapies using mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) are increasing in regenerative medicine, with applications to a growing number of aging-associated dysfunctions and degenerations. For successful therapies, a certain mass of cells is needed, requiring extensive ex vivo expansion of the cells. However, the proliferation of both MSCs and EPCs is limited as a result of telomere shortening-induced senescence. As cells approach senescence, their proliferation slows down and differentiation potential decreases. Therefore, ways to delay senescence and extend the replicative lifespan these cells are needed. Certain proteins and pathways play key roles in determining the replicative lifespan by regulating ROS generation, damage accumulation, or telomere shortening. And, their agonists and gene activators exert positive effects on lifespan. In many of the treatments, importantly, the lifespan is extended with the retention of differentiation potential. Furthermore, certain culture conditions, including the use of specific atmospheric conditions and culture substrates, exert positive effects on not only the proliferation rate, but also the extent of proliferation and differentiation potential as well as lineage determination. These strategies and known underlying mechanisms are introduced in this review, with an evaluation of their pros and cons in order to facilitate safe and effective MSC expansion ex vivo. PMID:27085715

  2. Sugar-borate esters--potential chemical agents in prostate cancer chemoprevention.

    PubMed

    Scorei, Romulus Ion; Popa, Radu

    2013-07-01

    The potential value of sugar-borate esters (SBEs) in the chemo-preventive therapy of prostate cancer has been reviewed. We propose that SBEs act as boron (B) vehicles, increasing the concentration of borate inside cancer cells relative to normal cells. Increased intracellular concentration of borate activates borate transporters, but also leads to growth inhibition and apoptosis. The effects of SBEs on normal cells are less dramatic because SBEs are naturally-occurring biochemicals, common and abundant in some fruits and vegetables, and also because borate dissociated from SBEs in natural diet doses is easily exported from normal cells. Cancer cell lines that over-express sugar transporters or under-express borate export are potential targets for SBE-based therapy. With regard to efficiency against cancer cells and drug preparation requirements, trigonal cis-diol boric monoesters will be one of the most effective class of SBEs. Because negative correlation exists between borate intake and the incidence of prostate cancer, and because most cancer cells overexpress sugar transporters, SBEs are proposed as a potential chemopreventive avenue in the fight against primary and recurrent prostate cancer. PMID:23293883

  3. Absence of X-point band overlap in divalent hexaborides and variability of the surface chemical potential

    SciTech Connect

    Denlinger, Jonathan D.; Gweon, Gey-Hong; Mo, Sung-Kwan; Allen, James W.; Sarrao, John L.; Bianchi, Adrian D.; Fisk, Zachary

    2001-11-04

    Angle-resolved photoemission measurements of divalent hexaborides reveals a >1 eV X-point gap between the valence and conduction bands, in contradiction to the band overlap assumed in several models of their novel ferromagnetism. While the global ARPES band structure and gap size observed are consistent with the results of bulk-sensitive soft x-ray absorption and emission boron K-edge spectroscopy, the surface-sensitive photoemission measurements also show a variation with cation, surface and time of the position of the surface chemical potential in the band structure.

  4. Study of the Z{sub 3} symmetry in QCD at finite temperature and chemical potential using a worm algorithm

    SciTech Connect

    Krein, Gastao; Leme, Rafael R.; Woitek, Marcio

    2013-03-25

    Traditional Monte Carlo simulations of QCD in the presence of a baryon chemical potential are plagued by the complex phase problem and new numerical approaches are necessary for studying the phase diagram of the theory. In this work we consider a Z{sub 3} Polyakov loop model for the deconfining phase transition in QCD and discuss how a flux representation of the model in terms of dimer and monomer variable solves the complex action problem. We present results of numerical simulations using a worm algorithm for the specific heat and two-point correlation function of Polyakov loops. Evidences of a first order deconfinement phase transition are discussed.

  5. Combining galantamine and memantine in multitargeted, new chemical entities potentially useful in Alzheimer's disease.

    PubMed

    Simoni, Elena; Daniele, Simona; Bottegoni, Giovanni; Pizzirani, Daniela; Trincavelli, Maria L; Goldoni, Luca; Tarozzo, Glauco; Reggiani, Angelo; Martini, Claudia; Piomelli, Daniele; Melchiorre, Carlo; Rosini, Michela; Cavalli, Andrea

    2012-11-26

    Herein we report on a novel series of multitargeted compounds obtained by linking together galantamine and memantine. The compounds were designed by taking advantage of the crystal structures of acetylcholinesterase (AChE) in complex with galantamine derivatives. Sixteen novel derivatives were synthesized, using spacers of different lengths and chemical composition. The molecules were then tested as inhibitors of AChE and as binders of the N-methyl-d-aspartate (NMDA) receptor (NMDAR). Some of the new compounds were nanomolar inhibitors of AChE and showed micromolar affinities for NMDAR. All compounds were also tested for selectivity toward NMDAR containing the 2B subunit (NR2B). Some of the new derivatives showed a micromolar affinity for NR2B. Finally, selected compounds were tested using a cell-based assay to measure their neuroprotective activity. Three of them showed a remarkable neuroprotective profile, inhibiting the NMDA-induced neurotoxicity at subnanomolar concentrations (e.g., 5, named memagal, IC(50) = 0.28 nM). PMID:23033965

  6. Investigations of novel unsaturated bile salts of male sea lamprey as potential chemical cues

    USGS Publications Warehouse

    Johnson, Nicholas S.; Yun, Sang-Seon; Li, Weiming

    2014-01-01

    Sulfated bile salts function as chemical cues that coordinate reproduction in sea lamprey, Petromyzon marinus. 7α, 12α, 24-trihydroxy-5α-cholan-3-one 24-sulfate (3kPZS) is the most abundant known bile salt released by sexually mature male sea lampreys and attracts ovulated females. However, previous studies showed that the male-produced pheromone consists of unidentified components in addition to 3kPZS. Here, analysis of water conditioned with mature male sea lampreys indicated the presence of 4 oxidized, unsaturated compounds with molecular weights of 466 Da, 468 Da, and 2 of 470 Da. These compounds were not detectable in water conditioned with immature male sea lampreys. By using mass spectrometry, 4 A-ring unsaturated sulfated bile salts were tentatively identified from male washings as 2 4-ene, a 1-ene, and a 1,4-diene analogs. These were synthesized to determine if they attracted ovulated female sea lampreys to spawning nests in natural streams. One of the novel synthetic bile salts, 3 keto-1-ene PZS, attracted ovulated females to the point of application at a concentration of 10-12 M. This study reveals the structural diversity of bile salts in sea lamprey, some of which have been demonstrated to be pheromonal cues.

  7. Dimethylglycine and chemically related amines tested for mutagenicity under potential nitrosation conditions.

    PubMed

    Hoorn, A J

    1989-04-01

    Dimethylglycine (DMG) and the chemically related amino acids glycine, sarcosine (monomethylglycine) and betaine (trimethylglycine) were tested in Salmonella typhimurium strain TA100 after treatment with sodium nitrite under acidic conditions using a modified Ames Salmonella/microsome assay as reported by Colman et al. (1980). The increase in the number of revertants observed both with and without metabolic activation was also induced in the control mixtures without adding the amines. From the subsequent testing of the individual components of the mixtures, we concluded that non-consumed nitrite was responsible for the mutagenic responses observed in the different reaction mixtures, and not the amines themselves. There were no consistent indications of mutagenic activity of the DMG test mixture as compared to the control mixture which exhibited both consistent mutagenic activity and a toxic effect which was not increased by the addition of DMG. In fact, DMG seemed to decrease the toxicity of the control reaction solution to the Salmonella which was clearly observed at the higher doses. DMG cannot be considered mutagenic under the test conditions employed. The same can be said of the other amino acids as well. PMID:2468082

  8. Mesoporous carbon/zirconia composites: a potential route to chemically functionalized electrically-conductive mesoporous materials.

    PubMed

    Oh, Jung-Min; Kumbhar, Amar S; Geiculescu, Olt; Creager, Stephen E

    2012-02-14

    Mesoporous nanocomposite materials in which nanoscale zirconia (ZrO(2)) particles are embedded in the carbon skeleton of a templated mesoporous carbon matrix were prepared, and the embedded zirconia sites were used to accomplish chemical functionalization of the interior surfaces of mesopores. These nanocomposite materials offer a unique combination of high porosity (e.g., ∼84% void space), electrical conductivity, and surface tailorability. The ZrO(2)/carbon nanocomposites were characterized by thermogravimetric analysis, nitrogen-adsorption porosimetry, helium pychnometry, powder X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Comparison was made with templated mesoporous carbon samples prepared without addition of ZrO(2). Treatment of the nanocomposites with phenylphosphonic acid was undertaken and shown to result in robust binding of the phosphonic acid to the surface of ZrO(2) particles. Incorporation of nanoscale ZrO(2) surfaces in the mesoporous composite skeleton offers unique promise as a means for anchoring organophosphonates inside of pores through formation of robust covalent Zr-O-P bonds. PMID:22248432

  9. Sulfur and ash reduction potential and selected chemical and physical properties of United States coals

    SciTech Connect

    Cavallaro, J.A.; Deurbrouck, A.W.; Killmeyer, R.P.; Fuchs, W. ); Jacobsen, P.S. )

    1991-09-01

    This report summarizes the washability and comprehensive characterization of 975 raw coal channel samples collected from the Eastern, Central, and Western Regions (including Alaska) of the United States. All of this information is sorted in the Pittsburgh Energy Technology Center (PETC) Coal Technology Data Base. Individual reports for each region were completed previously as Volumes 1, 2, and 3 and included the detailed data for each of the 975 samples. This report is a summation of the results of those three reports on a state- and region-wide basis only, and does not include the data for individual samples, but only includes the composite data for each state and region. Graphical summations are presented by state, section or rank, and region showing the effects of crushing on impurity reductions and showing the distribution of raw and clean coal samples meeting various levels of SO{sub 2} emissions. The statistical evaluations in the Appendices present the composited washability data of 1.30, 1.40, and 1.60 specific gravities of separation, the selected chemical and physical properties, and the composited washability data interpolated at various levels of Btu recovery. 13 refs., 93 figs., 9 tabs.

  10. Identifying chemical carcinogens and assessing potential risk in short-term bioassays using transgenic mouse models.

    PubMed Central

    Tennant, R W; French, J E; Spalding, J W

    1995-01-01

    Cancer is a worldwide public health concern. Identifying carcinogens and limiting their exposure is one approach to the problem of reducing risk. Currently, epidemiology and rodent bioassays are the means by which putative human carcinogens are identified. Both methods have intrinsic limitations: they are slow and expensive processes with many uncertainties. The development of methods to modify specific genes in the mammalian genome has provided promising new tools for identifying carcinogens and characterizing risk. Transgenic mice may provide advantages in shortening the time required for bioassays and improving the accuracy of carcinogen identification; transgenic mice might now be included in the testing armamentarium without abandoning the two-year bioassay, the current standard. We show that mutagenic carcinogens can be identified with increased sensitivity and specificity using hemizygous p53 mice in which one allele of the p53 gene has been inactivated. Furthermore, the TG.AC transgenic model, carrying a v-Ha-ras construct, has developed papillomas and malignant tumors in response to a number of mutagenic and nonmutagenic carcinogens and tumor promoters, but not to noncarcinogens. We present a decision-tree approach that permits, at modest extra cost, the testing of more chemicals with improved ability to extrapolate from rodents to humans. Images Figure 1. Figure 2. Figure 3. PMID:8529591

  11. Controlling Heteroepitaxy by Oxygen Chemical Potential: Exclusive Growth of (100) Oriented Ceria Nanostructures on Cu(111)

    DOE PAGESBeta

    Höcker, Jan; Duchoň, Tomáš; Veltruská, Kateřina; Matolín, Vladimír; Falta, Jens; Senanayake, Sanjaya D.; Flege, J. Ingo

    2016-01-06

    We present a novel and simple method for the preparation of a well-defined CeO2(100) model system on Cu(111) based on the adjustment of the Ce/O ratio during growth. The method yields micrometer-sized, several nanometers high, single-phase CeO2(100) islands with controllable size and surface termination that can be benchmarked against the known (111) nanostructured islands on Cu(111). We also demonstrate the ability to adjust the Ce to O stoichiometry from CeO2(100) (100% Ce4+) to c-Ce2O3(100) (100% Ce3+), which can be readily recognized by characteristic surface reconstructions observed by low-energy electron diffraction. Finally, the discovery of the highly stable CeOx(100) phase onmore » a hexagonally close packed metal surface represents an unexpected growth mechanism of ceria on Cu(111), and it provides novel opportunities to prepare more elaborate models, benchmark surface chemical reactivity, and thus gain valuable insights into the redox chemistry of ceria in catalytic processes.« less

  12. Chemical characteristics and oxidative potential of particulate matter emissions from gasoline, diesel, and biodiesel cars.

    PubMed

    Cheung, Ka Lam; Polidori, Andrea; Ntziachristos, Leonidas; Tzamkiozis, Theodoros; Samaras, Zissis; Cassee, Flemming R; Gerlofs, Miriam; Sioutas, Constantinos

    2009-08-15

    Three light-duty vehicles in five different configurations [a Honda Accord operating with diesel with a closed-coupled oxidation catalyst and an underfloor catalyst replaced in some tests with a diesel particle filter (DPF), a Toyota Corolla operating with gasoline, and a VW Golf alternatively operating with petrodiesel or biodiesel] were tested in a dynamometer facility to develop an improved understanding of the factors affecting the toxicity of particulate exhaust emissions. The vehicles were tested using a variety of real-world driving cycles, more than the certification test (New European Driving Cycle). Particle samples were collected and analyzed for elemental and organic carbon (EC and OC, respectively), water soluble and water insoluble organic carbon (WSOC and WISOC, respectively), and inorganic ions, and the emission rates (mg/km) for each vehicle/configuration were determined. A dithiothreitol (DTT) assay was used to assess the oxidative potential of the particulate matter (PM) samples. The DPF-equipped diesel and gasoline vehicles were characterized by the lowest overall PM mass emissions, while the diesel and biodiesel cars produced the most potent exhaust in terms of oxidative activity. When the DPF was fitted on the Honda Accord diesel vehicle, the mass emission rates and distance-based oxidative potential were both decreased by 98%, compared to the original configuration. Correlation analysis showed that the DTT consumption rate was highly associated with WSOC, WISOC, and OC (R = 0.98, 0.93, and 0.94, respectively), consistent with previous findings. PMID:19746734

  13. The potentiality of botanicals and their products as an alternative to chemical insecticides to sandflies (Diptera: Psychodidae): a review.

    PubMed

    Dinesh, Diwakar Singh; Kumari, Seema; Kumar, Vijay; Das, Pradeep

    2014-03-01

    Use of chemical pesticides is the current method for controlling sandflies. However, resistance is being developed in sandflies against the insecticide of choice that is DDT (dichlorodiphenyl trichloroethane). Botanicals have potential to act as an alternative to chemical insecticides as the crude extracts and active molecules of some plants show insecticidal effect to sandflies. This will lead to safe, easy and environment friendly method for control of sandflies. Therefore, information regarding botanicals acting as alternative to chemical insecticide against sandflies assumes importance in the context of development of resistance to insecticides as well as to prevent environment from contamination. This review deals with some plants and their products having repellent and insecticidal effect to sandflies in India and abroad. Different methods of extraction and their bioassay on sandflies have been emphasized in the text. Various extracts of some plants like Ricinus communis (Euphorbiaceae), Solanum jasminoides (Solanaceae), Bougainvillea glabra (Nyctaginaceae), Capparis spinosa (Capparidaceae), Acalypha fruticosa (Euphorbiaceae) and Tagetes minuta (Asteraceae) had shown repellent/insecticidal effect on sandflies. This review will be useful in conducting the research work to find out botanicals of Indian context having insecticidal effect on sandflies. PMID:24717195

  14. Identifying potential endocrine disruptors among industrial chemicals and their metabolites--development and evaluation of in silico tools.

    PubMed

    Rybacka, Aleksandra; Rudén, Christina; Tetko, Igor V; Andersson, Patrik L

    2015-11-01

    The aim of this study was to improve the identification of endocrine disrupting chemicals (EDCs) by developing and evaluating in silico tools that predict interactions at the estrogen (E) and androgen (A) receptors, and binding to transthyretin (T). In particular, the study focuses on evaluating the use of the EAT models in combination with a metabolism simulator to study the significance of bioactivation for endocrine disruption. Balanced accuracies of the EAT models ranged from 77-87%, 62-77%, and 65-89% for E-, A-, and T-binding respectively. The developed models were applied on a set of more than 6000 commonly used industrial chemicals of which 9% were predicted E- and/or A-binders and 1% were predicted T-binders. The numbers of E- and T-binders increased 2- and 3-fold, respectively, after metabolic transformation, while the number of A-binders marginally changed. In-depth validation confirmed that several of the predicted bioactivated E- or T-binders demonstrated in vivo estrogenic activity or influenced blood levels of thyroxine in vivo. The metabolite simulator was evaluated using in vivo data from the literature which showed a 50% accuracy for studied chemicals. The study stresses, in summary, the importance of including metabolic activation in prioritization activities of potentially emerging contaminants. PMID:26210185

  15. Potential endocrine disrupting organic chemicals in treated municipal wastewater and river water

    USGS Publications Warehouse

    Barber, L.B.; Brown, G.K.; Zaugg, S.D.

    2000-01-01

    Select endocrine disrupting organic chemicals were measured in treated wastewater from Chicago, IL, Minneapolis/St. Paul, MN, Detroit, MI, and Milwaukee, WI, and in the Des Plaines, Illinois, and Minnesota Rivers during the fall of 1997 and the spring of 1998. Emphasis was given to alkylphenolpolyethoxylate (APEO) derived compounds, although 17-??-estradiol, bisphenol A, caffeine, total organic carbon, ethylenediaminetetraacetic acid (EDTA), and other compounds also were measured. Contaminants were isolated by continuous liquid-liquid extraction (CLLE) with methylene chloride and analyzed by gas chromatography/mass spectrometry in full scan and selected ion monitoring modes. The extracts were derivatized to form the methyl esters of alkylphenolethoxycarboxylates (APEC), and EDTA was isolated by evaporation and derivatized to form the tetrapropyl ester. The mass spectra of nonylphenol (NP) and octylphenol (OP) compounds are complex and show variations among the different ethoxylate and carboxylate homologs, reflecting variations in the ethylene oxide chain length. Recoveries for target compounds and surrogate standards ranged from 20-130%, with relative standard deviations of 9.9-53%. Detection limits for the various compounds ranged from 0.06-0.35 ??g/L. Analysis of the wastewater effluents detected a number of compounds including NP, NPEO, OP, OPEO, NPEC, caffeine, and EDTA at concentrations ranging from <1-439 ??g/L, with EDTA and NPEC being most abundant. There was variability in compound distributions and concentrations between the various sewage treatment plants, indicating differences in treatment type and influent composition. Several wastewater-derived compounds were detected in the river samples, with EDTA and NPEC persisting for considerable distance downstream from wastewater discharges, and NP and NPEO being attenuated more rapidly.

  16. The Kinematic and Chemical Properties of a Potential Core-forming Clump: Perseus B1-E

    NASA Astrophysics Data System (ADS)

    Sadavoy, S. I.; Shirley, Y.; Di Francesco, J.; Henning, Th.; Currie, M. J.; André, Ph.; Pezzuto, S.

    2015-06-01

    We present 13CO and {{C}18}O (1-0), (2-1), and (3-2) maps toward the core-forming Perseus B1-E clump using observations from the James Clerk Maxwell Telescope, the Submillimeter Telescope of the Arizona Radio Observatory, and the IRAM 30 m telescope. We find that the 13CO and {{C}18}O line emission both have very complex velocity structures, indicative of multiple velocity components within the ambient gas. The (1-0) transitions reveal a radial velocity gradient across B1-E of ˜ 1 km {{s}-1} p{{c}-1} that increases from northwest to southeast, whereas the majority of the Perseus cloud has a radial velocity gradient increasing from southwest to northeast. In contrast, we see no evidence of a velocity gradient associated with the denser Herschel-identified substructures in B1-E. Additionally, the denser substructures have much lower systemic motions than the ambient clump material, which indicates that they are likely decoupled from the large-scale gas. Nevertheless, these substructures themselves have broad line widths (˜0.4 km {{s}-1}) similar to that of the {{C}18}O gas in the clump, which suggests they inherited their kinematic properties from the larger-scale, moderately dense gas. Finally, we find evidence of {{C}18}O depletion only toward one substructure, B1-E2, which is also the only object with narrow (transonic) line widths. We suggest that as prestellar cores form, their chemical and kinematic properties are linked in evolution, such that these objects must first dissipate their turbulence before they deplete in CO.

  17. Cloud Formation Potential of Biomass Burning Aerosol Surrogate-Particles Chemically Aged by OH

    NASA Astrophysics Data System (ADS)

    Slade, J. H.; Thalman, R. M.; Wang, J.; Li, Z. Q.; Knopf, D. A.

    2014-12-01

    Heterogeneous or multiphase reactions between trace gases such as OH and atmospheric aerosol can influence physicochemical properties of the particles including composition, morphology and lifetime. In this work, the cloud condensation nuclei (CCN) activity of laboratory-generated biomass burning aerosol (BBA) exposed to OH radicals is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type and OH exposure ([OH]×time) using a CCN counter coupled to a custom-built aerosol flow reactor (AFR). The composition of particles collected by a micro-orifice uniform deposit impactor (MOUDI) first subjected to different OH exposures is analyzed by Raman and scanning transmission X-ray microscopy coupled with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative compounds found in BBA that have different hygroscopicity, chemical functionalities, and reactivity with OH radicals. BBA surrogate-particles are generated following atomization of aqueous solutions with mass ratios LEV:MNC:KS of 1:0:0, 0:1:0, 0:0:1, 1:1:0, 0:1:1, 1:0:1, 1:1:1, and 1:0.03:0.3. OH radicals are generated in the AFR following photolysis of O3 in the presence of H2O using a variable intensity ultra-violet (UV) lamp, which allows equivalent atmospheric OH exposures from days to weeks. In addition, we investigate how κ changes i) in response to varying [O3] with and without OH, and ii) at a fixed OH exposure while varying RH. The impact of OH exposure on the CCN activity of BBA will be presented and its atmospheric implications will be discussed.

  18. Chemical Composition and Allelopathic Potential of Essential Oils from Tipuana tipu (Benth.) Kuntze Cultivated in Tunisia.

    PubMed

    El Ayeb-Zakhama, Asma; Sakka-Rouis, Lamia; Bergaoui, Afifa; Flamini, Guido; Jannet, Hichem Ben; Harzallah-Skhiri, Fethia

    2016-03-01

    In Tunisia, Tipuana tipu (Benth.) Kuntze is an exotic tree, which was introduced many years ago and planted as ornamental street, garden, and park tree. The present work reported, for the first time, the chemical composition and evaluates the allelopathic effect of the hydrodistilled essential oils of the different parts of this tree, viz., roots, stems, leaves, flowers, and pods gathered in the area of Sousse, a coastal region, in the East of Tunisia. In total, 86 compounds representing 89.9 - 94.9% of the whole oil composition, were identified in these oils by GC-FID and GC/MS analyses. The root essential oil was clearly distinguished for its high content in sesquiterpene hydrocarbons (β-caryophyllene, 1 (44); 24.1% and germacrene D, 2 (53); 20.0%), while those obtained from pods, leaves, stems, and flowers were dominated by non-terpene hydrocarbons. The most important ones were n-tetradecane (41, 16.3%, pod oil), 1,7-dimethylnaphthalene (43, 15.6%, leaf oil), and n-octadecane (77, 13.1%, stem oil). The leaf oil was rich in the apocarotene (E)-β-ionone (4 (54); 33.8%), and the oil obtained from flowers was characterized by hexahydrofarnesylacetone (5 (81); 19.9%) and methyl hexadecanoate (83, 10.2%). Principal component and hierarchical cluster analyses separated the five essential oils into three groups and two subgroups, each characterized by the major oil constituents. Contact tests showed that the germination of lettuce seeds was totally inhibited by the root essential oil tested at 1 mg/ml. The inhibitory effect on the shoot and root elongation varied from -1.6% to -32.4%, and from -2.5% to -64.4%, respectively. PMID:26916976

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

    SciTech Connect

    Vedani, Angelo; Dobler, Max; Smieško, Martin

    2012-06-01

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

  20. Generation and characterization of phage-GnRH chemical conjugates for potential use in cat and dog immunocontraception.

    PubMed

    Samoylov, A; Cox, N; Cochran, A; Wolfe, K; Donovan, C; Kutzler, M; Petrenko, V; Baker, H; Samoylova, T

    2012-12-01

    Overpopulation of cats and dogs is a serious worldwide problem that demands novel, safe and cost-effective solutions. The objective of this study was to generate and characterize phage-peptide conjugates with gonadotropin-releasing hormone (GnRH) for potential use as an immunocontraceptive. A filamentous phage vector f5-8 with wild-type phage coat proteins was used as a carrier for construction of chemical conjugates with GnRH, a peptide that acts as a master reproductive hormone. In such conjugates, the phage body plays the role of a carrier protein, while multiple copies of GnRH peptide stimulate production of neutralizing anti-GnRH antibodies potentially leading to contraceptive effects. To generate the constructs, four different GnRH-based peptides were synthesized and conjugated to phage particles in a two-step procedure: (i) peptides were reacted with phage to form a conjugate using 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride chemistry (EDC) and (ii) the conjugates were separated from remaining free peptides by dialysis. Formation and specificity of phage-GnRH conjugates were confirmed by three independent methods: spectrophotometry, electron microscopy and ELISA. When the conjugates were tested for interaction with sera collected from cats and dogs immunized with GnRH-based vaccines in independent studies, strong specific ELISA signals were obtained, suggesting the potential use of the conjugates for cat and dog immunosterilization. The ability of the conjugates to stimulate production of anti-GnRH antibodies in vivo was evaluated in mice. While optimization of dose, immunization route and adjuvant still requires investigation, our preliminary results demonstrated the presence of anti-GnRH antibodies in sera of mice immunized with such conjugates. Fertility trials in cats and dogs will be needed to evaluate contraceptive potentials of the phage-GnRH peptide chemical conjugates. PMID:23279551

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

    PubMed Central

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

    2014-01-01

    Background: Mitochondrial dysfunction has been implicated in the pathogenesis of a variety of disorders including cancer, diabetes, and neurodegenerative and cardiovascular diseases. Understanding whether different environmental chemicals and druglike molecules impact mitochondrial function represents an initial step in predicting exposure-related toxicity and defining a possible role for such compounds in the onset of various diseases. Objectives: We sought to identify individual chemicals and general structural features associated with changes in mitochondrial membrane potential (MMP). Methods: We used a multiplexed [two end points in one screen; MMP and adenosine triphosphate (ATP) content] quantitative high throughput screening (qHTS) approach combined with informatics tools to screen the Tox21 library of 10,000 compounds (~ 8,300 unique chemicals) at 15 concentrations each in triplicate to identify chemicals and structural features that are associated with changes in MMP in HepG2 cells. Results: Approximately 11% of the compounds (913 unique compounds) decreased MMP after 1 hr of treatment without affecting cell viability (ATP content). In addition, 309 compounds decreased MMP over a concentration range that also produced measurable cytotoxicity [half maximal inhibitory concentration (IC50) in MMP assay/IC50 in viability assay ≤ 3; p < 0.05]. More than 11% of the structural clusters that constitute the Tox21 library (76 of 651 clusters) were significantly enriched for compounds that decreased the MMP. Conclusions: Our multiplexed qHTS approach allowed us to generate a robust and reliable data set to evaluate the ability of thousands of drugs and environmental compounds to decrease MMP. The use of structure-based clustering analysis allowed us to identify molecular features that are likely responsible for the observed activity. Citation: Attene-Ramos MS, Huang R, Michael S, Witt KL, Richard A, Tice RR, Simeonov A, Austin CP, Xia M. 2015. Profiling of the Tox

  2. Antigenic potential of a highly conserved Neisseria meningitidis lipopolysaccharide inner core structure defined by chemical synthesis.

    PubMed

    Reinhardt, Anika; Yang, You; Claus, Heike; Pereira, Claney L; Cox, Andrew D; Vogel, Ulrich; Anish, Chakkumkal; Seeberger, Peter H

    2015-01-22

    Neisseria meningitidis is a leading cause of bacterial meningitis worldwide. We studied the potential of synthetic lipopolysaccharide (LPS) inner core structures as broadly protective antigens against N. meningitidis. Based on the specific reactivity of human serum antibodies to synthetic LPS cores, we selected a highly conserved LPS core tetrasaccharide as a promising antigen. This LPS inner core tetrasaccharide induced a robust IgG response in mice when formulated as an immunogenic glycoconjugate. Binding of raised mouse serum to a broad collection of N. meningitidis strains demonstrated the accessibility of the LPS core on viable bacteria. The distal trisaccharide was identified as the crucial epitope, whereas the proximal Kdo moiety was immunodominant and induced mainly nonprotective antibodies that are responsible for lack of functional protection in polyclonal serum. Our results identified key antigenic determinants of LPS core glycan and, hence, may aid the design of a broadly protective immunization against N. meningitidis. PMID:25601073

  3. DRAR-CPI: a server for identifying drug repositioning potential and adverse drug reactions via the chemical-protein interactome.

    PubMed

    Luo, Heng; Chen, Jian; Shi, Leming; Mikailov, Mike; Zhu, Huang; Wang, Kejian; He, Lin; Yang, Lun

    2011-07-01

    Identifying new indications for existing drugs (drug repositioning) is an efficient way of maximizing their potential. Adverse drug reaction (ADR) is one of the leading causes of death among hospitalized patients. As both new indications and ADRs are caused by unexpected chemical-protein interactions on off-targets, it is reasonable to predict these interactions by mining the chemical-protein interactome (CPI). Making such predictions has recently been facilitated by a web server named DRAR-CPI. This server has a representative collection of drug molecules and targetable human proteins built up from our work in drug repositioning and ADR. When a user submits a molecule, the server will give the positive or negative association scores between the user's molecule and our library drugs based on their interaction profiles towards the targets. Users can thus predict the indications or ADRs of their molecule based on the association scores towards our library drugs. We have matched our predictions of drug-drug associations with those predicted via gene-expression profiles, achieving a matching rate as high as 74%. We have also successfully predicted the connections between anti-psychotics and anti-infectives, indicating the underlying relevance of anti-psychotics in the potential treatment of infections, vice versa. This server is freely available at http://cpi.bio-x.cn/drar/. PMID:21558322

  4. Chemical composition and antioxidant-prooxidant potential of a polyphenolic extract and a proanthocyanidin-rich fraction of apple skin.

    PubMed

    Mendoza-Wilson, Ana María; Castro-Arredondo, Sergio Ivan; Espinosa-Plascencia, Angélica; Robles-Burgueño, María Del Refugio; Balandrán-Quintana, René Renato; Bermúdez-Almada, María Del Carmen

    2016-02-01

    The apple is a food rich in diverse classes of polyphenols (PP), among which the proanthocyanidins (PCs), which are primarily concentrated in the skin, are one of the most abundant. These compounds are of considerable interest for their possible positive health effects because of their antioxidant properties. However, depending on the classes of PP present (chemical composition) and their relative concentrations in the apple skin, their antioxidant effects vary and some of their components can even generate prooxidant effects. This work determined the chemical composition and antioxidant-prooxidant potential of a polyphenolic extract (PPE) and a proanthocyanidin-rich fraction (PRF) of apple skin, along with the contribution of their most abundant individual compounds, based on their copper chelating ability, ease in reducing peroxidase-generated free radicals and TEAC (Trolox-Equivalent Antioxidant Capacity) assay. For this purpose, chromatographic and colorimetric methods were used. The majority compounds identified in PPE were flavan-3-ols (44.58%), flavonols (42.89%) and dihydrochalcones (11.60%). In PRF, we detected monomers and oligomers from dimers to heptamers, which were composed of 97% (-)-epicatechin and 3% (+)-catechin. The antioxidant potential was notably higher in PRF than in PPE. The (-)-epicatechin monomer and the procyanidin B2 dimer showed more ease in reducing peroxidase-generated free radicals compared to other compounds of the apple skin, whereas phloridzin dihydrochalcone produced prooxidant effects. PMID:27441252

  5. Potential hazards to embryo implantation: A human endometrial in vitro model to identify unwanted antigestagenic actions of chemicals

    SciTech Connect

    Fischer, L.; Deppert, W.R.; Pfeifer, D.; Stanzel, S.; Weimer, M.; Hanjalic-Beck, A.; Stein, A.; Straßer, M.; Zahradnik, H.P.; Schaefer, W.R.

    2012-05-01

    Embryo implantation is a crucial step in human reproduction and depends on the timely development of a receptive endometrium. The human endometrium is unique among adult tissues due to its dynamic alterations during each menstrual cycle. It hosts the implantation process which is governed by progesterone, whereas 17β-estradiol regulates the preceding proliferation of the endometrium. The receptors for both steroids are targets for drugs and endocrine disrupting chemicals. Chemicals with unwanted antigestagenic actions are potentially hazardous to embryo implantation since many pharmaceutical antiprogestins adversely affect endometrial receptivity. This risk can be addressed by human tissue-specific in vitro assays. As working basis we compiled data on chemicals interacting with the PR. In our experimental work, we developed a flexible in vitro model based on human endometrial Ishikawa cells. Effects of antiprogestin compounds on pre-selected target genes were characterized by sigmoidal concentration–response curves obtained by RT-qPCR. The estrogen sulfotransferase (SULT1E1) was identified as the most responsive target gene by microarray analysis. The agonistic effect of progesterone on SULT1E1 mRNA was concentration-dependently antagonized by RU486 (mifepristone) and ZK137316 and, with lower potency, by 4-nonylphenol, bisphenol A and apigenin. The negative control methyl acetoacetate showed no effect. The effects of progesterone and RU486 were confirmed on the protein level by Western blotting. We demonstrated proof of principle that our Ishikawa model is suitable to study quantitatively effects of antiprogestin-like chemicals on endometrial target genes in comparison to pharmaceutical reference compounds. This test is useful for hazard identification and may contribute to reduce animal studies. -- Highlights: ► We compare progesterone receptor-mediated endometrial effects of chemicals and drugs. ► 4-Nonylphenol, bisphenol A and apigenin exert weak

  6. Inhibition of the compound action potentials of frog sciatic nerves by aroma oil compounds having various chemical structures

    PubMed Central

    Ohtsubo, Sena; Fujita, Tsugumi; Matsushita, Akitomo; Kumamoto, Eiichi

    2015-01-01

    Plant-derived chemicals including aroma oil compounds have an ability to inhibit nerve conduction and modulate transient receptor potential (TRP) channels. Although applying aroma oils to the skin produces a local anesthetic effect, this has not been yet examined throughly. The aim of the present study was to know how nerve conduction inhibitions by aroma oil compounds are related to their chemical structures and whether these activities are mediated by TRP activation. Compound action potentials (CAPs) were recorded from the frog sciatic nerve by using the air-gap method. Citral (aldehyde), which activates various types of TRP channels, attenuated the peak amplitude of CAP with the half-maximal inhibitory concentration (IC50) value of 0.46 mmol/L. Another aldehyde (citronellal), alcohol (citronellol, geraniol, (±)-linalool, (−)-linalool, (+)-borneol, (−)-borneol, α-terpineol), ester (geranyl acetate, linalyl acetate, bornyl acetate), and oxide (rose oxide) compounds also reduced CAP peak amplitudes (IC50: 0.50, 0.35, 0.53, 1.7, 2.0, 1.5, 2.3, 2.7, 0.51, 0.71, 0.44, and 2.6 mmol/L, respectively). On the other hand, the amplitudes were reduced by a small extent by hydrocarbons (myrcene and p-cymene) and ketone (camphor) at high concentrations (2–5 mmol/L). The activities of citral and other TRP agonists ((+)-borneol and camphor) were resistant to TRP antagonist ruthenium red. An efficacy sequence for the CAP inhibitions was generally aldehydes ≥ esters ≥ alcohols > oxides >> hydrocarbons. The CAP inhibition by the aroma oil compound was not related to its octanol–water partition coefficient. It is suggested that aroma oil compounds inhibit nerve conduction in a manner specific to their chemical structures without TRP activation. PMID:26038703

  7. Chemical composition and potential health effects of prunes: a functional food?

    PubMed

    Stacewicz-Sapuntzakis, M; Bowen, P E; Hussain, E A; Damayanti-Wood, B I; Farnsworth, N R

    2001-05-01

    Prunes are dried plums, fruits of Prunus domestica L., cultivated and propagated since ancient times. Most dried prunes are produced from cultivar d'Agen, especially in California and France, where the cultivar originated. After harvest, prune-making plums are dehydrated in hot air at 85 to 90 degrees C for 18 h, then further processed into prune juice, puree, or other prune products. This extensive literature review summarizes the current knowledge of chemical composition of prunes and their biological effects on human health. Because of their sweet flavor and well-known mild laxative effect, prunes are considered to be an epitome of functional foods, but the understanding of their mode of action is still unclear. Dried prunes contain approximately 6.1 g of dietary fiber per 100 g, while prune juice is devoid of fiber due to filtration before bottling. The laxative action of both prune and prune juice could be explained by their high sorbitol content (14.7 and 6.1 g/100 g, respectively). Prunes are good source of energy in the form of simple sugars, but do not mediate a rapid rise in blood sugar concentration, possibly because of high fiber, fructose, and sorbitol content. Prunes contain large amounts of phenolic compounds (184 mg/100 g), mainly as neochlorogenic and chlorogenic acids, which may aid in the laxative action and delay glucose absorption. Phenolic compounds in prunes had been found to inhibit human LDL oxidation in vitro, and thus might serve as preventive agents against chronic diseases, such as heart disease and cancer. Additionally, high potassium content of prunes (745 mg/100 g) might be beneficial for cardiovascular health. Dried prunes are an important source of boron, which is postulated to play a role in prevention of osteoporosis. A serving of prunes (100 g) fulfills the daily requirement for boron (2 to 3 mg). More research is needed to assess the levels of carotenoids and other phytochemicals present in prunes to ensure correct labeling and

  8. Exploratory synthesis of copper alkoxides as potential precursors for chemical vapor deposition of copper

    NASA Astrophysics Data System (ADS)

    Himes, Charles Leonard

    Volatile copper compounds are needed by the electronics industry for applying thin films of copper during integrated circuit fabrication. Copper alkoxides comprise a class of compounds that offer promise for this purpose. This research investigated possible synthesis pathways to candidate compounds. Syntheses of aminoalkoxocopper(II) compounds by metathesis in water and under an inert atmosphere were investigated. 2-Aminoalkoxocopper(II) can be made in both environments. N-Alkylamino substituted copper(II) aminoethanolates were synthesized only under an inert atmosphere. 2- N,N-Dimethylaminoethoxocopper(II), 2-N,N-diethylaminoethoxocopper(II), and 2-N-ethylaminoethoxocopper(II) were synthesized. This synthesis method is suggested as a general method for preparation of aminoalkoxocopper(II) compounds. The volatility of 2-N,N-dialkylaminoethoxocopper(II) compounds suggests that they may be appropriate for further development as solid chemical vapor deposition precursors for copper and copper oxides. Their volatility might be controllable by variation of their alkyl substituents. Attempted formation of oxidatively-stable aminoalkoxocopper(I) compounds, in air, by replacement of nitrato and chlorido groups from triphenylphosphine-stablized copper(I) compounds was unsuccessful. The observed reactions suggest successful syntheses might be conducted under an inert atmosphere. The synthesis of volatile alkoxocopper(I) compounds was attempted by using a stabilizing ligand to interrupt their polymeric structures. Derivatives of methoxocopper(I) and ethoxocopper(I) compounds using triphenylphosphine were attempted. Methods of separation and isolation of the products were studied. Chloride contamination in reactants and production of copper(I) oxide interfered with success in these syntheses. Nitratobis(triphenylphosphine)copper(I) was used as a novel starting material for syntheses of triphenylphosphine-stabilized tert-butoxocopper(I) compounds and proved to be a valuable

  9. Chemical characterization and hydrothermal pretreatment of Salicornia bigelovii straw for enhanced enzymatic hydrolysis and bioethanol potential.

    PubMed

    Cybulska, Iwona; Chaturvedi, Tanmay; Brudecki, Grzegorz P; Kádár, Zsófia; Meyer, Anne S; Baldwin, Robert M; Thomsen, Mette Hedegaard

    2014-02-01

    Salicornia bigelovii straw was characterized and evaluated as a potential lignocellulosic bioethanol feedstock. S. bigelovii used in the study was grown in the United Arab Emirates using saltwater (40ppt) for irrigation. Salt removal was performed prior to pretreatment to protect the processing equipment and avoid inhibition of enzymes and yeast. Composition of the washed biomass was comparable to traditional lignocellulosic biomasses with relatively high glucan and xylan content (26 and 22g/100gDM, respectively) but with lower lignin content (7g/100gDM). The washed feedstock was subjected to hydrothermal pretreatment, producing highly digestible (up to 92% glucan-to-glucose conversion) and fermentable (up to 100% glucose-to-ethanol conversion) fiber fractions. Liquid fractions obtained in the pretreatment did not show inhibition towards Saccharomyces cerevisiae. No significant differences among the enzymatic convertibility and microbial fermentability of the fibers as well as low xylose recoveries suggest that lower severity pretreatment conditions could be exploited for S. bigelovii. PMID:24362358

  10. Synthesis, physical and chemical properties, and potential applications of graphite fluoride fibers

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh; Long, Martin; Stahl, Mark

    1987-01-01

    Graphite fluoride fibers can be produced by fluorinating pristine or intercalated graphite fibers. The higher the degree of graphitization of the fibers, the higher the temperature needed to reach the same degree of fluorination. Pitched based fibers were fluorinated to flourine-to-carbon atom rations between 0 and 1. The graphite fluoride fibers with a fluorine-to-carbon atom ration near 1 have extensive visible structural damage. On the other hand, fluorination of fibers pretreated with bromine or fluorine and bromine result in fibers with a fluorine-to-carbon atom ratio nearly equal to 0.5 with no visible structural damage. The electrical resistivity of the fibers is dependent upon the fluorine to carbon atom ratio and ranged from .01 to 10 to the 11th ohm/cm. The thermal conductivity of these fibers ranged from 5 to 73 W/m-k, which is much larger than the thermal conductivity of glass, which is the regular filler in epoxy composites. If graphite fluoride fibers are used as a filler in epoxy or PTFE, the resulting composite may be a high thermal conductivity material with an electrical resistivity in either the insulator or semiconductor range. The electrically insulating product may provide heat transfer with lower temperature gradients than many current electrical insulators. Potential applications are presented.

  11. Chemical Composition and Food Potential of Pachymerus nucleorum Larvae Parasitizing Acrocomia aculeata Kernels

    PubMed Central

    Alves, Ariana Vieira; Sanjinez Argandoña, Eliana Janet; Linzmeier, Adelita Maria; Cardoso, Claudia Andrea Lima; Macedo, Maria Lígia Rodrigues

    2016-01-01

    Insect consumption as food is culturally practiced in various regions of the world. In Brazil, there are more than 130 species of edible insects registered, from nine orders, among which stands out the Coleoptera. The larva of the beetle Pachymerus nucleorum Fabricius, 1792, grows into the bocaiuva fruit (Acrocomia aculeata (Jacq.) Lodd. Ex Mart., 1845), which has proven nutritional quality. The aim of this work was to evaluate the nutritional potential of P. nucleorum larvae compared to bocaiuva kernels for human consumption. Proteins were the second largest portion of the larvae nutritional composition (33.13%), with percentage higher than the bocaiuva kernels (14.21%). The larval lipid content (37.87%) was also high, very close to the kernels (44.96%). The fraction corresponding to fatty acids in the oil extracted from the larvae was 40.17% for the saturated and 46.52% for the unsaturated. The antioxidant activity value was 24.3 uM trolox/g of oil extracted from larvae. The larvae tryptic activity was 0.032±0.006 nmol BAPNA/min. Both the larvae and the bocaiuva kernel presented absence of anti-nutritional factors. These results favor the use of P. nucleorum larvae as food, which are a great protein and lipid sources with considerable concentrations of unsaturated fatty acids compared to the bocaiuva kernel. PMID:27031500

  12. Chemical characterisation of dredged sediments in relation to their potential use in civil engineering.

    PubMed

    Zuliani, Tea; Mladenovič, Ana; Ščančar, Janez; Milačič, Radmila

    2016-04-01

    During capital and/or maintenance dredging operations, large amounts of material are produced. Instead of their discharge, dredged sediments may be a valuable natural resource if not contaminated. One of the possible areas of application is civil engineering. In the present work, the environmental status of seaport dredged sediment was evaluated in order to investigate its potential applicability as a secondary raw material. Sediments were analysed for element concentrations in digested samples, aqueous extracts and fractions from sequential extraction; for fluoride, chloride and sulphate concentrations in aqueous extracts; and for tributyltin (TBT). Granulometric and mineralogical compositions were also analysed. The elemental impact was evaluated by calculation of the enrichment factors. The total element concentrations determined showed moderate contamination of the dredged sediments as was confirmed also by their moderate enrichment factors, presumably as a result of industrial and port activities. Elemental concentrations in the aqueous extract were very low and therefore do not represent any hazard for the environment. The water-soluble element concentrations were under the threshold levels set by the EU Directive on the landfill of waste, on the basis of which the applicability of dredged sediments in civil engineering is evaluated, while the content of chloride and sulphate were above the threshold levels. It was found out that due to the large amounts of sediment available, civil engineering applications such as the construction of embankments and backfilling is the most beneficial recycling solution at present. PMID:27000319

  13. Chemical dechlorination of hexachlorobenzene with polyethylene glycol and hydroxide: Dominant effect of temperature and ionic potential

    PubMed Central

    Xiao, Ye; Jiang, Jianguo; Huang, Hai

    2014-01-01

    Persistent organic pollutants (POPs) originating from POP waste are playing an increasingly important role in the elevation of regional POP levels. In this study we realized the complete dechlorination of high concentration hexachlorobenzene (HCB) waste in the presence of polyethylene glycol and hydroxide, rather than using conventional high temperature incineration. Here, we demonstrate the dominant effect of temperature and hydroxide on HCB dechlorination in this process. Complete dechlorination of HCB was only observed at temperature about 200°C or above within 4 h reaction, and the apparent activation energy of this process was 43.1 kJ/mol. The alkalinity of hydroxides had notable effects on HCB dechlorination, and there was a considerable linear relationship between the natural logarithm of the HCB dechlorination rate constant and square root of the ionic potential of metal cation (R2 = 0.9997, p = 0.0081, n = 3). This study highlights a promising technology to realize complete dechlorination of POP waste, especially at high concentrations, in the presence of PEG in conjunction with hydroxide. PMID:25200551

  14. Physico-chemical properties and cytotoxic potential of Cordyceps sinensis metabolites.

    PubMed

    Lee, Eun-Jeong; Jang, Ka-Hee; Im, Seon-Young; Lee, Yoon-Kyung; Farooq, Muhammad; Farhoudi, Rozbeh; Lee, Dong-Jin

    2015-01-01

    This study was conducted to estimate the antioxidant activities, biochemical properties and biological activities of one of the entomopathogenic fungi, Cordyceps sinensis. Analysis of fungal metabolites indicated that the most abundant free sugar was glucose; the highest component of organic acids was citric acid from 10-day culture medium and the glutamate was the predominant amino acid observed from 3-day culture medium. Maximum total polyphenols and flavonoids were detected in the 15-day culture medium. For cytotoxicity test, three cancer cell lines, HepG2 (liver), MCF-7 (breast) and A549 (lung) were used. The IC50 values of the highest toxicity of HepG2 cell lines were observed from 10-day cultured medium, whereas the highest toxicity of MCF-7 and A549 was observed on 5-day cultured medium. This is the first study reporting on the strong antioxidant and cytotoxic potential of C. sinensis. Culture medium of C. sinensis may thus be used as an effective antioxidant and anticancer treatment of natural origin. PMID:25135771

  15. Centrifugal microfluidic platform for radiochemistry: potentialities for the chemical analysis of nuclear spent fuels.

    PubMed

    Bruchet, Anthony; Taniga, Vélan; Descroix, Stéphanie; Malaquin, Laurent; Goutelard, Florence; Mariet, Clarisse

    2013-11-15

    The use of a centrifugal microfluidic platform is for the first time reported as an alternative to classical chromatographic procedures for radiochemistry. The original design of the microfluidic platform has been thought to fasten and simplify the prototyping process with the use of a circular platform integrating four rectangular microchips made of thermoplastic. The microchips, dedicated to anion-exchange chromatographic separations, integrate a localized monolithic stationary phase as well as injection and collection reservoirs. The results presented here were obtained with a simplified simulated nuclear spent fuel sample composed of non-radioactive isotopes of Europium and Uranium, in proportion usually found for uranium oxide nuclear spent fuel. While keeping the analytical results consistent with the conventional procedure (extraction yield for Europium of ≈97%), the use of the centrifugal microfluidic platform allowed to reduce the volume of liquid needed by a factor of ≈250. Thanks to their unique "easy-to-use" features, centrifugal microfluidic platforms are potential successful candidates for the downscaling of chromatographic separation of radioactive samples (automation, multiplexing, easy integration in glove-boxes environment and low cost of maintenance). PMID:24148434

  16. NOx Direct Decomposition: Potentially Enhanced Thermodynamics and Kinetics on Chemically Modified Ferroelectric Surfaces

    NASA Astrophysics Data System (ADS)

    Kakekhani, Arvin; Ismail-Beigi, Sohrab

    2014-03-01

    NOx are regulated pollutants produced during automotive combustion. As part of an effort to design catalysts for NOx decomposition that operate in oxygen rich environment and permit greater fuel efficiency, we study chemistry of NOx on (001) ferroelectric surfaces. Changing the polarization at such surfaces modifies electronic properties and leads to switchable surface chemistry. Using first principles theory, our previous work has shown that addition of catalytic RuO2 monolayer on ferroelectric PbTiO3 surface makes direct decomposition of NO thermodynamically favorable for one polarization. Furthermore, the usual problem of blockage of catalytic sites by strong oxygen binding is overcome by flipping polarization that helps desorb the oxygen. We describe a thermodynamic cycle for direct NO decomposition followed by desorption of N2 and O2. We provide energy barriers and transition states for key steps of the cycle as well as describing their dependence on polarization direction. We end by pointing out how a switchable order parameter of substrate,in this case ferroelectric polarization, allows us to break away from some standard compromises for catalyst design(e.g. the Sabatier principle). This enlarges the set of potentially catalytic metals. Primary support from Toyota Motor Engineering and Manufacturing, North America, Inc.

  17. Chemical Composition and Food Potential of Pachymerus nucleorum Larvae Parasitizing Acrocomia aculeata Kernels.

    PubMed

    Alves, Ariana Vieira; Sanjinez Argandoña, Eliana Janet; Linzmeier, Adelita Maria; Cardoso, Claudia Andrea Lima; Macedo, Maria Lígia Rodrigues

    2016-01-01

    Insect consumption as food is culturally practiced in various regions of the world. In Brazil, there are more than 130 species of edible insects registered, from nine orders, among which stands out the Coleoptera. The larva of the beetle Pachymerus nucleorum Fabricius, 1792, grows into the bocaiuva fruit (Acrocomia aculeata (Jacq.) Lodd. Ex Mart., 1845), which has proven nutritional quality. The aim of this work was to evaluate the nutritional potential of P. nucleorum larvae compared to bocaiuva kernels for human consumption. Proteins were the second largest portion of the larvae nutritional composition (33.13%), with percentage higher than the bocaiuva kernels (14.21%). The larval lipid content (37.87%) was also high, very close to the kernels (44.96%). The fraction corresponding to fatty acids in the oil extracted from the larvae was 40.17% for the saturated and 46.52% for the unsaturated. The antioxidant activity value was 24.3 uM trolox/g of oil extracted from larvae. The larvae tryptic activity was 0.032±0.006 nmol BAPNA/min. Both the larvae and the bocaiuva kernel presented absence of anti-nutritional factors. These results favor the use of P. nucleorum larvae as food, which are a great protein and lipid sources with considerable concentrations of unsaturated fatty acids compared to the bocaiuva kernel. PMID:27031500

  18. Chemical vapor deposition of boron carbo-nitride as a potential passivation layer for germanium surfaces

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, Patrick Ryan

    Motivated by the need for a Ge surface passivation layer, chemical vapor deposition of thin (< 10 nm) films of amorphous boron carbo-nitride (BC xNy) on Ge(100) surfaces were studied to assess film continuity, interface bonding, Ge oxidation prevention, and electrical passivation. BC xNy nominally 2.5--5 nm thick continuously covers Ge(100), as determined by ion scattering spectroscopy and two angle resolved x-ray photoelectron spectroscopy (ARXPS) techniques. ARXPS analysis reveals no evidence of an interfacial layer due to elemental intermixing at the BCxN y--Ge(100) interface. High resolution transmission electron microscopy images of HfO2/BCxNy/Ge(100) cross-sections reveal abrupt BCxNy--Ge(100) interfaces. XPS was used to track Ge oxidation of BCxNy-covered Ge(100) upon exposure to ambient, 50 °C deionized water, and a 250 °C atomic layer deposition HfO2 process. If the BCxNy layer is continuous (≥ ˜ 4 nm), the underlying Ge(100) surface is not oxidized despite incorporation of O into BCxNy. Thinner films (≤ 3.2 nm) permitted Ge(100) oxidation in each oxidizing environment studied. Ge nanowires with a 5.7 nm BCxNy coating were resistant to oxidation for at least 5 months of ambient exposure. C--V and I--V measurements were made for metal-insulator-semiconductor (MIS) structures fabricated from n-Si(100) and n-Ge(100) wafers passivated with 4.5--5 nm BCxNy. C-rich BC0.61N0.08 films studied up to this point exhibited large amounts of hysteresis and fixed negative charge, so they were abandoned in favor of N-rich BCxNy (0.09 ≤ x ≤ 0.15, 0.38 ≤ y ≤ 0.52). N-rich BCxNy grown at 275--400 °C showed that lower deposition temperatures resulted in improved electrical characteristics, including decreased hysteresis, lower VFB shift, lower leakage current, and less C--V stretch-out. The electrical improvement is attributed to decreased bulk and interfacial defects in BCxNy deposited at lower temperatures. Even for the lowest growth temperature studied (275

  19. Descriptions of surface chemical reactions using a neural network representation of the potential-energy surface

    NASA Astrophysics Data System (ADS)

    Lorenz, Sönke; Scheffler, Matthias; Gross, Axel

    2006-03-01

    A neural network (NN) approach is proposed for the representation of six-dimensional ab initio potential-energy surfaces (PES) for the dissociation of a diatomic molecule at surfaces. We report tests of NN representations that are fitted to six-dimensional analytical PESs for H2 dissociation on the clean and the sulfur covered Pd(100) surfaces. For the present study we use high-dimensional analytical PESs as the basis for the NN training, as this enables us to investigate the influence of phase space sampling on adsorption rates in great detail. We note, however, that these analytical PESs were obtained from detailed density functional theory calculations. When information about the PES is collected only from a few high-symmetric adsorption sites, we find that the obtained adsorption probabilities are not reliable. Thus, intermediate configurations need to be considered as well. However, it is not necessary to map out complete elbow plots above nonsymmetric sites. Our study suggests that only a few additional energies need to be considered in the region of activated systems where the molecular bond breaks. With this understanding, the required number of NN training energies for obtaining a high-quality PES that provides a reliable description of the dissociation and adsorption dynamics is orders of magnitude smaller than the number of total-energy calculations needed in traditional ab initio on the fly molecular dynamics. Our analysis also demonstrates the importance of a reliable, high-dimensional PES to describe reaction rates for dissociative adsorption of molecules at surfaces.

  20. Cellular uptake and cytotoxic potential of respirable bentonite particles with different quartz contents and chemical modifications in human lung fibroblasts.

    PubMed

    Geh, Stefan; Yücel, Raif; Duffin, Rodger; Albrecht, Catrin; Borm, Paul J A; Armbruster, Lorenz; Raulf-Heimsoth, Monika; Brüning, Thomas; Hoffmann, Eik; Rettenmeier, Albert W; Dopp, Elke

    2006-02-01

    Considering the biological reactivity of pure quartz in lung cells, there is a strong interest to clarify the cellular effects of respirable siliceous dusts, like bentonites. In the present study, we investigated the cellular uptake and the cytotoxic potential of bentonite particles (Ø< 10 microm) with an alpha-quartz content of up to 6% and different chemical modifications (activation: alkaline, acidic, organic) in human lung fibroblasts (IMR90). Additionally, the ability of the particles to induce apoptosis in IMR90-cells and the hemolytic activity was tested. All bentonite samples were tested for endotoxins with the in vitro-Pyrogen test and were found to be negative. Cellular uptake of particles by IMR90-cells was studied by transmission electron microscopy (TEM). Cytotoxicity was analyzed in IMR90-cells by determination of viable cells using flow cytometry and by measuring of the cell respiratory activity. Induced apoptotic cells were detected by AnnexinV/Propidiumiodide-staining and gel electrophoresis. Our results demonstrate that activated bentonite particles are better taken up by IMR90-cells than untreated (native) bentonite particles. Also, activated bentonite particles with a quartz content of 5-6% were more cytotoxic than untreated bentonites or bentonites with a quartz content lower than 4%. The bentonite samples induced necrotic as well as apoptotic cell death. In general, bentonites showed a high membrane-damaging potential shown as hemolytic activity in human erythrocytes. We conclude that cellular effects of bentonite particles in human lung cells are enhanced after chemical treatment of the particles. The cytotoxic potential of the different bentonites is primarily characterized by a strong lysis of the cell membrane. PMID:16059726