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Sample records for strangeness chemical potentials

  1. The Strange World of Chemical Oscillations.

    ERIC Educational Resources Information Center

    MOSAIC, 1978

    1978-01-01

    Describes an oscillating chemical reaction, and discusses numerous parallels to it in research, such as in fibrillation of the heart, body-clock rhythms of animals and plants, the self-assembly of multicellular organisms, and certain stripes in volcanic rock. (GA)

  2. Strangeness enhancement - a potential signature for QGP phase

    NASA Astrophysics Data System (ADS)

    Tiwari, V. K.; Singh, C. P.

    1997-09-01

    Strangeness enhancement has always been considered as a potential signature for deconfining as well as chiral symmetry restoring quark-hadron phase transition. We obtain the ratios Λ¯/Λ, Ξ¯/Ξ and K+/K- from a quark-gluon plasma (QGP) using a modified equation of state (EOS). Similarly these ratios are also obtained from a hadron gas (HG) by using a thermodynamically consistent equation of state (EOS) which incorporates the finite size, hard-core repulsive interactions among baryons as an excluded volume effect. We then suggest that the variations of these ratios either with the energy density or with baryon density can serve as a potential signature for detecting a QGP formation in the ultra-relativistic heavy-ion collisions.

  3. Strange and heavy mesons in hadronic matter

    NASA Astrophysics Data System (ADS)

    Cabrera, Daniel; Abreu, Luciano M.; Bratkovskaya, Elena; Ilner, Andrej; Llanes-Estrada, Felipe J.; Ramos, Angels; Tolos, Laura; Torres-Rincon, Juan M.

    2014-04-01

    We present selected results on the properties of strange and heavy-flavoured mesons in a hot and dense nuclear medium, with emphasis in selfconsistent coupled-channel approaches based on the chiral Lagrangian. In the strangeness sector, we discuss how the enhanced reactivity of light strange vectors at FAIR conditions can be tied to in-medium effects on their predominant decay modes (e.g. bar K* → bar Kπ) and to the excitation of strange baryons in vector-meson nucleon interactions. In the heavy-flavour sector, we focus on recent determinations of the transport coefficients of charmed and bottomed mesons in a hadron gas at vanishing baryonic chemical potential. We comment on the role of microscopic transport simulations to establish a connection between theoretical models and experimental observables from heavy-ion collisions (HICs).

  4. Strange stars

    NASA Technical Reports Server (NTRS)

    Alcock, Charles; Farhi, Edward; Olinto, Angela

    1986-01-01

    Strange matter, a form of quark matter that is postulated to be absolute stable, may be the true ground stage of the hadrons. If this hypothesis is correct, neutron stars may convert to 'strange stars'. The mass-radius relation for strange stars is very different from that of neutron stars; there is no minimum mass, and for mass of 1 solar mass or less, mass is proportional to the cube of the radius. For masses between 1 solar mass and 2 solar masses, the radii of strange stars are about 10 km, as for neutron stars. Strange stars may have an exposed quark surface, which is capable of radiating at rates greatly exceeding the Eddington limit, but has a low emissivity for X-ray photons. The stars may have a thin crust with the same composition as the preneutron drip outer layer of a conventional neutron star crust. Strange stars cool efficiently via neutrino emission.

  5. Transverse-momentum spectra of strange particles produced in Pb+Pb collisions at = 2.76 TeV in the chemical non-equilibrium model

    NASA Astrophysics Data System (ADS)

    Florkowski, Wojciech

    2017-01-01

    It is first shown that recent problems in heavy-ion collisions at the LHC energies, connected with thermal description of the proton yield and the pion spectra at low transverse-momenta, can be simultaneously explained within a chemical non-equilibrium statistical hadronization framework. Then the predictions of this approach for the production of strange particles are presented.

  6. Strange stars at finite temperature

    NASA Astrophysics Data System (ADS)

    Ray, Subharthi; Bagchi, Manjari; Dey, Jishnu; Dey, Mira

    2006-03-01

    We calculate strange star properties, using large Nc approximation with built-in chiral symmetry restoration (CSM). We used a relativistic Hartree Fock meanfield approximation method, using a modi.ed Richardson potential with two scale parameters Λ and Λ', to find a new set of equation of state (EOS) for strange quark matter. We take the effect of temperature (T) on gluon mass, in addition to the usual density dependence, and find that the transition T from hadronic matter to strange matter is 80 MeV. Therefore formation of strange stars may be the only signal for formation of QGP with asymptotic freedom (AF) and CSM.

  7. Confirming the Potential of Systems Containing Strangeness for 3D Structure Studies of the Proton

    NASA Astrophysics Data System (ADS)

    Ali, Salina; Horn, Tanja; Carmignotto, Marco

    2017-01-01

    The additional flavor degree of freedom in kaon electroproduction provides a unique opportunity to study the mechanism underlying strangeness production and the transition from hadronic to partonic degrees of freedom in exclusive processes. At sufficiently high energies, where soft non-perturbative and hard physics have been shown to factorize, the Generalized Parton Distributions provide a spatial tomography of the nucleon. The applicability of this formalism can be experimentally verified. The E12-09-011 experiment at the 12 GeV Jefferson Lab aims to test the expected approach of the hard scattering regime through precision measurements of the fully separated exclusive kaon production cross section, and in particular the relative contributions and kinematic dependencies of the longitudinal and transverse cross sections. The longitudinal cross section also allows one to test the kaon pole dominance and could allow for kaon form factor extractions. In this talk, I will present the current status and discuss the outlook on future studies of strange quarks with kaon production as well as the particle identification requirements, and possible kaon form factor extractions at a 12-GeV Jefferson Lab. Supported in part by NSF grants PHY-1306227 and PHY-1306418.

  8. Strangeness at SIS energies

    SciTech Connect

    Koch, Volker

    2005-09-28

    In this contribution the authors discuss the physics of strange hadrons in low energy ({approx_equal} 1-2 AGeV) heavy ion collision. In this energy range the relevant strange particle are the kaons and anti-kaons. The most interesting aspect concerning these particles are so called in-medium modifications. They will attempt to review the current status of understanding of these in medium modifications. In addition they briefly discuss other issues related with kaon production, such as the nuclear equation of state and chemical equilibrium.

  9. Baryon number and strangeness: signals of a deconfinedantecedent

    SciTech Connect

    Majumder, A.; Koch, V.; Randrup, J.

    2005-06-29

    The correlation between baryon number and strangeness is used to discern the nature of the deconfined matter produced at vanishing chemical potential in high-energy nuclear collisions at the BNL RHIC. Comparisons of results of various phenomenological models with correlations extracted from lattice QCD calculations suggest that a quasi-particle picture applies. At finite baryon densities, such as those encountered at the CERN SPS, it is demonstrated that the presence of a first-order phase transition and the accompanying development of spinodal decomposition would significantly enhance the number of strangeness carriers and the associated fluctuations.

  10. Additional strange hadrons from QCD thermodynamics and strangeness freezeout in heavy ion collisions.

    PubMed

    Bazavov, A; Ding, H-T; Hegde, P; Kaczmarek, O; Karsch, F; Laermann, E; Maezawa, Y; Mukherjee, Swagato; Ohno, H; Petreczky, P; Schmidt, C; Sharma, S; Soeldner, W; Wagner, M

    2014-08-15

    We compare lattice QCD results for appropriate combinations of net strangeness fluctuations and their correlations with net baryon number fluctuations with predictions from two hadron resonance gas (HRG) models having different strange hadron content. The conventionally used HRG model based on experimentally established strange hadrons fails to describe the lattice QCD results in the hadronic phase close to the QCD crossover. Supplementing the conventional HRG with additional, experimentally uncharted strange hadrons predicted by quark model calculations and observed in lattice QCD spectrum calculations leads to good descriptions of strange hadron thermodynamics below the QCD crossover. We show that the thermodynamic presence of these additional states gets imprinted in the yields of the ground-state strange hadrons leading to a systematic 5-8 MeV decrease of the chemical freeze-out temperatures of ground-state strange baryons.

  11. Strangeness in hadronic stellar matter

    NASA Astrophysics Data System (ADS)

    Knorren, R.; Prakash, M.; Ellis, P. J.

    1995-12-01

    We examine the presence of strangeness-bearing components, hyperons and kaons, in dense neutron star matter. Calculations are performed using relativistic mean field models, in which both the baryon-baryon and kaon-baryon interactions are mediated by meson exchange. Results of kaon condensation are found to be qualitatively similar to previous work with chiral models, if compatibility of the kaon optical potentials is required. The presence of strangeness, be it in the form of hyperons or kaons, implies a reduction in the maximum mass and a relatively large number of protons, sufficient to allow rapid cooling to take place. The need to improve upon the poorly known couplings of the strange particles, which determine the composition and structure of neutron stars, is stressed. We also discuss generic problems with effective masses in mean field theories.

  12. 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)

  13. 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.

  14. The physics of strange matter

    SciTech Connect

    Olinto, A.V. |

    1991-12-01

    Strange matter may be the ground state of matter. We review the phenomenology and astrophysical implications of strange matter, and discuss the possible ways for testing the strange matter hypothesis.

  15. 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.

  16. 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.

  17. Potential community exposure to toxic chemicals

    SciTech Connect

    LaGrone, F.S. )

    1991-03-01

    There is increasing public concern over potential exposure to airborne chemical substances from all sources. Industries in Houston have cooperated to implement a comprehensive regional monitoring program to address the issue of long-term community exposure to toxic airborne chemicals. The initial results from the HRM Volatile Organic Indicator Compound Study have been used effectively to address public concerns regarding the air quality impact of airborne toxic emissions reported under Section 313 of SARA Title III.

  18. Potentiation of Chemical Ototoxicity by Noise

    PubMed Central

    Steyger, Peter S.

    2010-01-01

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

  19. Chemical-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.

  20. Strange nonchaotic stars.

    PubMed

    Lindner, John F; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G; Ditto, William L

    2015-02-06

    The unprecedented light curves of the Kepler space telescope document how the brightness of some stars pulsates at primary and secondary frequencies whose ratios are near the golden mean, the most irrational number. A nonlinear dynamical system driven by an irrational ratio of frequencies generically exhibits a strange but nonchaotic attractor. For Kepler's "golden" stars, we present evidence of the first observation of strange nonchaotic dynamics in nature outside the laboratory. This discovery could aid the classification and detailed modeling of variable stars.

  1. Once Upon a Time in Physics When Both Mathematics and Experiment Were Helpless: A Strange Life of Voltaic Contact Potential

    NASA Astrophysics Data System (ADS)

    Hong, Sungook

    2000-09-01

    This paper aims to answer the question of why the debate over the voltaic contact effect was so prolonged without a consensus during the nineteenth century. I propose that both experiment and mathematics were helpless to decide who was right. To demonstrate this, I will focus on the voltaic debates between James Clerk Maxwell and the Maxwellians, on the one hand, and William Thomson and the Thomsonians, on the other, and examine ten points: (1) the fundamental assumption, (2) the seat of the voltaic potential difference, (3) the role of the contact, (4) the magnitude of the potentials of two contacted metals, (5) the definition of potential, (6) the electrostatic measurement, (7) the thermoelectric measurement, (8) the physical interpretation of the same mathematical formula, (9) experiments in different media, and (10) experiments in the vacuum - all of which were in dispute between the Thomsonian and Maxwellian parties. I show that the two parties differed in theory, in the interpretation of measured data, in the physical interpretation of mathematical relationship, and in what they believed would constitute a crucial experiment. I assert that the Maxwellian and Thomsonian voltaic theories were incommensurable, but that this incommensurability was not exactly symmetrical because it mainly resided on the side of William Thomson.

  2. 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).

  3. Two alternative versions of strangeness

    PubMed Central

    Nishijima, Kazuhikoa

    2008-01-01

    The concept of strangeness emerged from the low energy phenomenology before the entry of quarks in particle physics. The connection between strangeness and isospin is rather accidental and loose and we recognize later that the definition of strangeness is model-dependent. Indeed, in Gell-Mann’s triplet quark model we realize that there is a simple alternative representation of strangeness. When the concept of generations is incorporated into the quark model we find that only the second alternative version of strangeness remains meaningful, whereas the original one does no longer keep its significance. PMID:18997448

  4. Strange Nonchaotic Stars

    NASA Astrophysics Data System (ADS)

    Lindner, John F.; Kohar, Vivek; Kia, Behnam; Hippke, Michael; Learned, John G.; Ditto, William L.

    2015-08-01

    Exploiting the unprecedented capabilities of the planet-hunting Kepler space telescope, which stared at 150 000 stars for four years, we discuss recent evidence that certain stars dim and brighten in complex patterns with fractal features. Such stars pulsate at primary and secondary frequencies whose ratios are near the famous golden mean, the most irrational number. A nonlinear system driven by an irrational ratio of frequencies is generically attracted toward a “strange” behavior that is geometrically fractal without displaying the “butterfly effect” of chaos. Strange nonchaotic attractors have been observed in laboratory experiments and have been hypothesized to describe the electrochemical activity of the brain, but a bluish white star 16 000 light years from Earth in the constellation Lyra may manifest, in the scale-free distribution of its minor frequency components, the first strange nonchaotic attractor observed in the wild. The recognition of stellar strange nonchaotic dynamics may improve the classification of these stars and refine the physical modeling of their interiors. We also discuss nonlinear analysis of other RR Lyrae stars in Kepler field of view and discuss some toy models for modeling these stars.References: 1) Hippke, Michael, et al. "Pulsation period variations in the RRc Lyrae star KIC 5520878." The Astrophysical Journal 798.1 (2015): 42.2) Lindner, John F., et al. "Strange nonchaotic stars." Phys. Rev. Lett. 114, 054101 (2015)

  5. Chemical Potential of a Lennard Jones Fluid

    NASA Astrophysics Data System (ADS)

    Celebonovic, V.

    2010-12-01

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

  6. Holographic phase transitions at finite chemical potential

    NASA Astrophysics Data System (ADS)

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

    2007-11-01

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

  7. Strange stars, strange dwarfs, and planetary-like strange-matter objects

    SciTech Connect

    Weber, F.; Schaab, C.; Weigel, M.K.; Glendenning, N.K.

    1995-05-01

    This paper gives an overview of the properties of all possible equilibrium sequences of compact strange-matter stars with nuclear crusts, which range from strange stars to strange dwarfs. In contrast to their non-strange counterparts--neutron stars and white dwarfs--their properties are determined by two (rather than one) parameters, the central star density and the density at the base of the nuclear crust. This leads to stellar strange-matter configurations whose properties are much more complex than those of the conventional sequence. As an example, two generically different categories of stable strange dwarfs are found, which could be the observed white dwarfs. Furthermore the authors find very-low-mass strange stellar objects, with masses as small as those of Jupiter or even lighter planets. Such objects, if abundant enough, should be seen by the presently performed gravitational microlensing searches.

  8. Strange hadronic matter

    SciTech Connect

    Schafner, J. |; Dover, C.B. |; Gal, A. ||; Greiner, C. |; Stoecker, H. |

    1993-02-01

    In an extended mean field theory, there is found a large class of bound multi-strange objects, formed from combinations of (p,n,{Lambda} {Xi}{sup 0} {Xi}{sup {minus}}, baryons, which are stable against strong decay. A maximal binding energy per baryon of E{sub B}/A {approx} {minus}21 MeV, strangeness per baryon of {integral}{sub s} {approx} 1--1.2, charge per baryon of {integral}{sub q} {approx} {minus}-0.1 to 0.1, and baryon density of 2.5--3 times that of ordinary nuclei are predicted. For A {ge} 6, stable combinations involving only ({Lambda},{Xi}{sup 0},{Xi}) hyperons are obtained.

  9. 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.

  10. Strange skyrmion molecules

    NASA Astrophysics Data System (ADS)

    Kopeliovich, Vladimir B.; Stern, Boris E.

    1997-05-01

    Composed skyrmions with B=2, strangeness content close to 0.5 and the binding energy of several tens of Mev are described. These skyrmions are obtained starting from the system of two B=1 hedgehogs located in different SU(2) subgroups of SU(3) and have the mass and baryon number distribution of molecular (dipole) type. The quantization of zero modes of skyrmion molecules and physics consequences of their existence are discussed.

  11. Strange skyrmion molecules

    SciTech Connect

    Kopeliovich, Vladimir B.; Stern, Boris E.

    1997-05-20

    Composed skyrmions with B=2, strangeness content close to 0.5 and the binding energy of several tens of Mev are described. These skyrmions are obtained starting from the system of two B=1 hedgehogs located in different SU(2) subgroups of SU(3) and have the mass and baryon number distribution of molecular (dipole) type. The quantization of zero modes of skyrmion molecules and physics consequences of their existence are discussed.

  12. Seismic Search for Strange Quark Matter

    NASA Technical Reports Server (NTRS)

    Teplitz, Vigdor

    2004-01-01

    Two decades ago, Witten suggested that the ground state of matter might be material of nuclear density made from up, down and strange quarks. Since then, much effort has gone into exploring astrophysical and other implications of this possibility. For example, neutron stars would almost certainly be strange quark stars; dark matter might be strange quark matter. Searches for stable strange quark matter have been made in various mass ranges, with negative, but not conclusive results. Recently, we [D. Anderson, E. Herrin, V. Teplitz, and I. Tibuleac, Bull. Seis. Soc. of Am. 93, 2363 (2003)] reported a positive result for passage through the Earth of a multi-ton "nugget" of nuclear density in a search of about a million seismic reports, to the U.S. Geological Survey for the years 1990-93, not associated with known Earthquakes. I will present the evidence (timing of first signals to the 9 stations involved, first signal directions, and unique waveform characteristics) for our conclusion and discuss potential improvements that could be obtained from exploiting the seismologically quieter environments of the moon and Mars.

  13. Phenomenology of strangeness production at high energies

    NASA Astrophysics Data System (ADS)

    Nasser Tawfik, Abdel; Yassin, Hayam; Abo Elyazeed, Eman R.; Maher, Muhammad; Magied Diab, Abdel; Abdel Wahab, Magda; Abou El Dahab, Eiman

    2016-12-01

    The strange-quark occupation factor (γ_s) is determined from the statistical fit of the multiplicity ratio {K}^+/π+ in a wide range of nucleon-nucleon center-of-mass energies (\\sqrt{sNN} ). From this single-strange-quark subsystem, γ_s(\\sqrt{sNN}) was parametrized as a damped trigonometric functionality and successfully implemented into the hadron resonance gas model, at chemical semi-equilibrium. Various particle ratios including {K}^-/ π- , Λ/π- , and \\barΛ/π- are well reproduced. The phenomenology of γ_s(\\sqrt{sNN}) suggests that the hadrons (γs rises) at \\sqrt{sNN} ≃ 7 \\text{GeV} seem to undergo a phase transition to a mixed phase (γs decreases), which is then derived into partons (γs remains unchanged with increasing \\sqrt{sNN} ), at \\sqrt{sNN} ≃ 20 \\text{GeV} .

  14. Strange experiments at the AGS

    SciTech Connect

    Chrien, R.

    1990-01-01

    The purpose of this review is to report recent progress in nuclear experiments involving strangeness which have been carried out at the Brookhaven Alternating Gradient Synchrotron over the past three years. These recent developments are noted in three areas: few body systems and dibaryons; strange probes of the nucleus; and associated production of hypernuclei. 9 refs., 3 figs.

  15. Electroproduction of Strange Nuclei

    SciTech Connect

    E.V. Hungerford

    2002-06-01

    The advent of high-energy, CW-beams of electrons now allows electro-production and precision studies of nuclei containing hyperons. Previously, the injection of strangeness into a nucleus was accomplished using secondary beams of mesons, where beam quality and target thickness limited the missing mass resolution. We review here the theoretical description of the (e, e'K+) reaction mechanism, and discuss the first experiment demonstrating that this reaction can be used to precisely study the spectra of light hypernuclei. Future experiments based on similar techniques, are expected to attain even better resolutions and rates.

  16. ``Towards Strange Metallic Holography'

    SciTech Connect

    Hartnoll, Sean A.; Polchinski, Joseph; Silverstein, Eva; Tong, David; /Cambridge U., DAMTP /Santa Barbara, KITP /UC, Santa Barbara

    2010-08-26

    We initiate a holographic model building approach to 'strange metallic' phenomenology. Our model couples a neutral Lifshitz-invariant quantum critical theory, dual to a bulk gravitational background, to a finite density of gapped probe charge carriers, dually described by D-branes. In the physical regime of temperature much lower than the charge density and gap, we exhibit anomalous scalings of the temperature and frequency dependent conductivity. Choosing the dynamical critical exponent z appropriately we can match the non-Fermi liquid scalings, such as linear resistivity, observed in strange metal regimes. As part of our investigation we outline three distinct string theory realizations of Lifshitz geometries: from F theory, from polarized branes, and from a gravitating charged Fermi gas. We also identify general features of renormalization group flow in Lifshitz theories, such as the appearance of relevant charge-charge interactions when z {ge} 2. We outline a program to extend this model building approach to other anomalous observables of interest such as the Hall conductivity.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  18. Converting neutron stars into strange stars

    NASA Technical Reports Server (NTRS)

    Olinto, A. V.

    1991-01-01

    If strange matter is formed in the interior of a neutron star, it will convert the entire neutron star into a strange star. The proposed mechanisms are reviewed for strange matter seeding and the possible strange matter contamination of neutron star progenitors. The conversion process that follows seeding and the recent calculations of the conversion timescale are discussed.

  19. Strangeness production in AA and pp collisions

    NASA Astrophysics Data System (ADS)

    Castorina, Paolo; Satz, Helmut

    2016-07-01

    Boost-invariant hadron production in high-energy collisions occurs in causally disconnected regions of finite space-time size. As a result, globally conserved quantum numbers (charge, strangeness, baryon number) are conserved locally in spatially restricted correlation clusters. Their size is determined by two time scales: the equilibration time specifying the formation of a quark-gluon plasma, and the hadronization time, specifying the onset of confinement. The expected values for these scales provide the theoretical basis for the suppression observed for strangeness production in elementary interactions ( pp , e^+e^- below LHC energies. In contrast, the space-time superposition of individual collisions in high-energy heavy-ion interactions leads to higher energy densities, resulting in much later hadronization and hence much larger hadronization volumes. This largely removes the causality constraints and results in an ideal hadronic resonance gas in full chemical equilibrium. In the present paper, we determine the collision energies needed for that; we also estimate when pp collisions reach comparable hadronization volumes and thus determine when strangeness suppression should disappear there as well.

  20. Magnetic Field of Strange Dwarfs

    NASA Astrophysics Data System (ADS)

    Baghdasaryan, D. S.

    2016-03-01

    The generation of a magnetic field in a strange quark star owing to differential rotation of the superfluid and superconducting quark core relative to the normal electron-nuclear crust of the star is examined. The maximum possible magnetic field on the surface is estimated for various models of strange dwarfs. Depending on the configuration parameters, i.e., the mass M and radius R of the star, a range of 103-105 G is found. These values of the magnetic field may be an additional condition for identification of strange dwarfs among the extensive class of observed white dwarfs.

  1. Grammatical complexity of strange sets

    NASA Astrophysics Data System (ADS)

    Auerbach, Ditza; Procaccia, Itamar

    1990-06-01

    Chaotic dynamical systems can be organized around an underlying strange set, which is comprised of all the unstable periodic orbits. In this paper, we quantify the complexity of such an organization; this complexity addresses the difficulty of predicting the structure of the strange set from low-order data and is independent of the entropy and the algorithmic complexity. We refer to the new measure as the grammatical complexity. The notion is introduced, discussed, and illustrated in the context of simple dynamical systems. In addition, the grammatical complexity is generalized to include metric properties arising due to the nonuniform distribution of the invariant measure on the strange set.

  2. 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.

  3. 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.

  4. Strangeness and onset of deconfinement

    SciTech Connect

    Becattini, F.

    2012-05-15

    I will review the current status of global strangeness production in relativistic heavy-ion collisions with particular emphasis on recent results from core-corona model. I will discuss its relevance for the detection of the onset of deconfinement.

  5. Strangeness and onset of deconfinement

    NASA Astrophysics Data System (ADS)

    Becattini, F.

    2012-05-01

    I will review the current status of global strangeness production in relativistic heavy-ion collisions with particular emphasis on recent results from core-corona model. I will discuss its relevance for the detection of the onset of deconfinement.

  6. 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.

  7. 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. ...

  8. Charmed mesons at finite temperature and chemical potential

    NASA Astrophysics Data System (ADS)

    Serna, Fernando E.; Krein, Gastão

    2017-03-01

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

  9. 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.

  10. Strangeness asymmetry in the proton

    NASA Astrophysics Data System (ADS)

    Alberg, Mary

    2015-04-01

    Strangeness asymmetry in the proton may arise from fluctuations of the proton into meson-baryon pairs. The leading contributions to proton strangeness are from the KΛ , KΣ , K* Λ and K* Σ states. We use a Fock state expansion of the proton in terms of these pairs to represent the strange meson cloud. We determine the strangeness distributions of the proton in a hybrid convolution model, in which the fluctuations are represented either by light-cone wave functions or meson-baryon splitting functions. For the parton distributions of the s(s) quarks in the bare baryons(mesons) of the Fock states, we use light cone wave functions or our statistical model, which expands the bare hadrons in terms of quark-gluon states. The momentum distributions of the s and s quarks in each Fock state differ because they are constituents of different hadrons. We present our results for proton strangeness asymmetry, and compare them to NuTeV and to global parton distributions. This research has been supported in part by NSF Award 1205686.

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

    EPA Pesticide Factsheets

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

  12. Strange Baryon Physics in Full Lattice QCD

    SciTech Connect

    Huey-Wen Lin

    2007-11-01

    Strange baryon spectra and form factors are key probes to study excited nuclear matter. The use of lattice QCD allows us to test the strength of the Standard Model by calculating strange baryon quantities from first principles.

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

    PubMed

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

    2015-10-21

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

  14. 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.

  15. Seismic search for strange quark nuggets

    SciTech Connect

    Herrin, Eugene T.; Rosenbaum, Doris C.; Teplitz, Vigdor L.

    2006-02-15

    Bounds on masses and abundances of Strange Quark Nuggets (SQNs) are inferred from a seismic search on Earth. Potential SQN bounds from a possible seismic search on the Moon are reviewed and compared with Earth capabilities. Bounds are derived from the data taken by seismometers implanted on the Moon by the Apollo astronauts. We show that the Apollo data implies that the abundance of SQNs in the region of 10 kg to 1 ton must be at least an order of magnitude less than would saturate the dark matter in the solar neighborhood.

  16. 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.

  17. Strangeness production at high baryon density

    NASA Astrophysics Data System (ADS)

    Satz, Helmut

    2016-08-01

    We propose to measure strange and non-strange hadron abundances at NICA in both AA and pp collisions, in order to test the validity range and possible extension schemes for present explanations of the energy and collision dependence of strange particle suppression.

  18. Strange nonchaotic self-oscillator

    NASA Astrophysics Data System (ADS)

    Jalnine, Alexey Yu.; Kuznetsov, Sergey P.

    2016-08-01

    An example of strange nonchaotic attractor (SNA) is discussed in a dissipative system of mechanical nature driven by a constant torque applied to one of the elements of the construction. So the external force is not oscillatory, and the system is autonomous. Components of the motion with incommensurable frequencies emerge due to the irrational ratio of the sizes of the involved rotating elements. We regard the phenomenon as strange nonchaotic self-oscillations, and its existence sheds new light on the question of feasibility of SNA in autonomous systems.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  1. Chemical potential calculations in dense liquids using metadynamics

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  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.

    PubMed

    Splittorff, K; Verbaarschot, J J M

    2007-01-19

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

  4. Strange hadrons and their resonances: A diagnostic tool of quark-gluon plasma freeze-out dynamics

    NASA Astrophysics Data System (ADS)

    Rafelski, Johann; Letessier, Jean; Torrieri, Giorgio

    2001-11-01

    We update our chemical analysis of (strange) hadrons produced at the SPS in Pb-Pb collisions at 158A GeV and discuss chemical analysis of RHIC results. We report that the shape of (anti)hyperon m⊥ spectra in a thermal freeze-out analysis leads to freeze-out conditions found in chemical analysis, implying sudden strange-hyperon production. We discuss how a combined analysis of several strange-hadron resonances of differing lifespan can be used to understand the dynamical process present during chemical and thermal freeze-outs. In medium resonance quenching is considered.

  5. Using the Moon as a Strange Quark Nugget Detector

    NASA Astrophysics Data System (ADS)

    Herrin, Eugene T.; Rosenbaum, Doris C.; Teplitz, Vigdor L.

    2007-11-01

    We review the romance and mystery of strange quark matter (SQM), including: its basics, our recent work on bounds on the abundance of ton-range strange quark nuggets (SQNs) from Earth seismology, potential SQN bounds from a possible seismic search on the Moon, and our recent bounds on SQNs in the 10 kilogram to ton range from the data of Apollo-implanted seismometers. Finally, we speculate a bit on using the sun or the solar system to detect passage of SQNs of much greater mass than the aforementioned.

  6. 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.

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

    PubMed

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

    2008-04-01

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

  8. Will strangeness win the prize?

    NASA Astrophysics Data System (ADS)

    Kapusta, Joseph I.

    2001-03-01

    Five groups have made predictions involving the production of strange hadrons and entered them in a competition set up by Barbara Jacak, Xin-Nian Wang and myself in the spring of 1998 for the purpose of comparing with first-year physics results from RHIC. These predictions are summarized and evaluated.

  9. A strange cat in Dublin

    NASA Astrophysics Data System (ADS)

    O'Raifeartaigh, Cormac

    2012-11-01

    Not many life stories in physics involve Nazis, illicit sex, a strange cat and the genetic code. Thus, a new biography of the great Austrian physicist Erwin Schrödinger is always of interest, and with Erwin Schrödinger and the Quantum Revolution, veteran science writer John Gribbin does not disappoint.

  10. Strange-quark-matter stars

    SciTech Connect

    Glendenning, N.K.

    1989-11-01

    We investigate the implications of rapid rotation corresponding to the frequency of the new pulsar reported in the supernovae remnant SN1987A. It places very stringent conditions on the equation of state if the star is assumed to be bound by gravity alone. We find that the central energy density of the star must be greater than 13 times that of nuclear density to be stable against the most optimistic estimate of general relativistic instabilities. This is too high for the matter to consist of individual hadrons. We conclude that it is implausible that the newly discovered pulsar, if its half-millisecond signals are attributable to rotation, is a neutron star. We show that it can be a strange quark star, and that the entire family of strange stars can sustain high rotation if strange matter is stable at an energy density exceeding about 5.4 times that of nuclear matter. We discuss the conversion of a neutron star to strange star, the possible existence of a crust of heavy ions held in suspension by centrifugal and electric forces, the cooling and other features. 34 refs., 10 figs., 1 tab.

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

    PubMed

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

    1982-01-01

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

  12. 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.

  13. 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.

  14. Response of quark condensate to the chemical potential

    NASA Astrophysics Data System (ADS)

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

    2008-07-01

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

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

    DTIC Science & Technology

    2012-07-01

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

  16. 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.

  17. Strangeness in nuclei and neutron stars

    NASA Astrophysics Data System (ADS)

    Lonardoni, Diego

    2017-01-01

    The presence of exotic particles in the core of neutron stars (NS) has been questioned for a long time. At present, it is still an unsolved problem that drives intense research efforts, both theoretical and experimental. The appearance of strange baryons in the inner regions of a NS, where the density can exceed several times the nuclear saturation density, is likely to happen due to energetic considerations. The onset of strange degrees of freedom is considered as an effective mechanism to soften the equation of state (EoS). This softening affects the entire structure of the star, reducing the pressure and therefore the maximum mass that the star can stably support. The observation of two very massive NS with masses of the order of 2M⊙ seems instead to rule out soft EoS, apparently excluding the possibility of hyperon formation in the core of the star. This inconsistency, usually referred to as the hyperon puzzle, is based on what we currently know about the interaction between strange particles and normal nucleons. The combination of a poor knowledge of the hypernuclear interactions and the difficulty of obtaining clear astrophysical evidence of the presence of hyperons in NS makes the understanding of the behavior of strange degrees of freedom in NS an intriguing theoretical challenge. We give our contribution to the discussion by studying the general problem of the hyperon-nucleon interaction. We attack this issue by employing a quantum Monte Carlo (QMC) technique, that has proven to be successful in the description of strongly correlated Fermion systems, to the study of finite size nuclear systems including strange degrees of freedom, i.e. hypernuclei. We show that many-body hypernuclear forces are fundamental to properly reproduce the ground state physics of Λ hypernuclei from light- to medium-heavy. However, the poor abundance of experimental data on strange nuclei leaves room for a good deal of indetermination in the construction of hypernuclear

  18. 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

  19. 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.

  20. Strange exotic atoms

    NASA Astrophysics Data System (ADS)

    Friedman, E.

    1998-08-01

    Exotic atoms of K- and Σ- are analyzed using density-dependent optical potentials constrained by a low-density limit. Emphasis is placed on radial sensitivities of the real potential. A potential depth of 180MeV inside nuclei is confirmed for K-. For Σ- a shallow attractive potential outside the nuclear surface becomes repulsive in the interior. The information content of limited data sets is demonstrated.

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

    NASA Astrophysics Data System (ADS)

    Kastor, David; Ray, Sourya; Traschen, Jennie

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1990-03-01

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

  3. Singularity-free anisotropic strange quintessence star

    NASA Astrophysics Data System (ADS)

    Bhar, Piyali

    2015-04-01

    Present paper provides a new model of anisotropic strange star corresponding to the exterior Schwarzschild metric. The Einstein field equations have been solved by utilizing the Krori-Barua (KB) ansatz (Krori and Barua in J. Phys. A, Math. Gen. 8:508, 1975) in presence of quintessence field characterized by a parameter ω q with . The obtained solutions are free from central singularity. Our model is potentially stable. The numerical values of mass of the different strange stars SAXJ1808.4-3658(SS1) (radius=7.07 km), 4U1820-30 (radius=10 km), Vela X-12 (radius=9.99 km), PSR J 1614-2230 (radius=10.3 km) obtained from our model is very close to the observational data that confirms the validity of our proposed model. The interior solution is also matched to the exterior Schwarzschild spacetime in presence of thin shell where negative surface pressure is required to hold the thin shell against collapsing.

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

    NASA Astrophysics Data System (ADS)

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

    2002-04-01

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

  5. 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.

  6. QCD phase diagram with a chiral chemical potential

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    NASA Technical Reports Server (NTRS)

    Stern, E. A.

    1976-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  9. Strangeness production in high-energy collisions and Hawking-Unruh radiation

    NASA Astrophysics Data System (ADS)

    Tawfik, Abdel Nasser; Yassin, Hayam; Abo Elyazeed, Eman R.

    The assumption that the production of quark-antiquark pairs and their sequential string-breaking takes place, likely as a tunneling process, through the event horizon of the color confinement determines the freezeout temperature and gives a plausible interpretation for the thermal pattern of elementary and nucleus-nucleus collisions. When relating the black-hole electric charges to the baryon-chemical potentials, it was found that the phenomenologically deduced parameters from the ratios of various particle species and the higher-order moments of net-proton multiplicity in the statistical thermal models and Polyakov linear-sigma model agree well with the ones determined from the thermal radiation from charged black hole. Accordingly, the resulting freezeout conditions, such as normalized entropy density s/T3 = 7 and average energy per particle /≃ 1GeV, are confirmed at finite chemical potentials as well. Furthermore, the problem of strangeness production in elementary collisions can be interpreted by thermal particle production from the Hawking-Unruh radiation. Consequently, the freezeout temperature depends on the quark masses. This leads to a deviation from full equilibrium and thus a suppression of the strangeness production in the elementary collisions. But in nucleus-nucleus collisions, an average temperature should be introduced in order to dilute the quark masses. This nearly removes the strangeness suppression. An extension to finite chemical potentials is introduced. The particle ratios of kaon-to-pion (K+/π+), phi-to-kaon (ϕ/K‑) and antilambda-to-pion (Λ¯/π‑) are determined from Hawking-Unruh radiation and compared with the thermal calculations and the measurements in different experiments. We conclude that these particle ratios can be reproduced, at least qualitatively, as Hawking-Unruh radiation at finite chemical potential. With increasing energy, both K+/π+ and ϕ/K‑ keep their maximum values at low SPS energies. But the further

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

    NASA Astrophysics Data System (ADS)

    Cohen, Thomas D.; Sen, Srimoyee

    2015-10-01

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

  11. Aspects of holographic entanglement at finite temperature and chemical potential

    NASA Astrophysics Data System (ADS)

    Kundu, Sandipan; Pedraza, Juan F.

    2016-08-01

    We investigate the behavior of entanglement entropy at finite temperature and chemical potential for strongly coupled large-N gauge theories in d-dimensions ( d ≥ 3) that are dual to Anti-de Sitter-Reissner-Nordstrom geometries in ( d + 1)-dimensions, in the context of gauge-gravity duality. We develop systematic expansions based on the Ryu-Takayanagi prescription that enable us to derive analytic expressions for entanglement entropy and mutual information in different regimes of interest. Consequently, we identify the specific regions of the bulk geometry that contribute most significantly to the entanglement entropy of the boundary theory at different limits. We define a scale, dubbed as the effective temperature, which determines the behavior of entanglement in different regimes. At high effective temperature, entanglement entropy is dominated by the thermodynamic entropy, however, mutual information subtracts out this contribution and measures the actual quantum entanglement. Finally, we study the entanglement/disentanglement transition of mutual information in the presence of chemical potential which shows that the quantum entanglement between two sub-regions decreases with the increase of chemical potential.

  12. Strangeness in ALICE at the LHC

    NASA Astrophysics Data System (ADS)

    Bellini, Francesca; ALICE Collaboration

    2017-01-01

    Strangeness production has been measured by the ALICE experiment in different collision systems at the unprecedented center-of-mass energies available at the CERN Large Hadron Collider. In Pb–Pb collisions at TeV the relative production of strange and multi-strange baryons relative to pions is observed to follow a saturating trend with increasing centrality, and reaching values that are consistent with those predicted by thermal model calculations in the Grand-Canonical ensemble. More recently, the multiplicity dependence of strangeness production in small systems such as pp and p–Pb has also been investigated. An overview of the most recent results on strangeness production is reported, including the first observation of strangeness enhancement with charged particle multiplicity in pp collisions.

  13. 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.

  14. A realistic model for charged strange quark stars

    NASA Astrophysics Data System (ADS)

    Thirukkanesh, S.; Ragel, F. C.

    2017-01-01

    We report a general approach to solve an Einstein-Maxwell system to describe a static spherically symmetric anisotropic strange matter distribution with linear equation of state in terms of two generating functions. It is examined by choosing Tolmann IV type potential for one of the gravitational potentials and a physically reasonable choice for the electric field. Hence, the generated model satisfies all the required major physical properties of a realistic star. The effect of electric charge on physical properties is highlighted.

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

    PubMed Central

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

    1985-01-01

    Mutagenic activity, measured by the bacterial fluctuation assay and thioether concentration in urine from workers at a chemical plant producing pharmaceuticals and explosives, was determined before and after exposure. Of 12 groups only those exposed to trinitrotoluene (n = 14) showed a significant increase in mutagenic activity using Salmonella typhimurium TA 98 without any exogenous metabolic system. The same strain responded only weakly when the S-9 mix was used; with Escherichia coli WP2 uvrA no effect of exposure was observed. Urinary thioether concentration was higher among smokers than among non-smokers, but occupational exposure had no effect. Urinary mutagenicity testing may be a useful tool for screening potentially genotoxic exposures in complex chemical environments. PMID:3899158

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

    PubMed

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

    2006-01-01

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

  17. 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

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Anghel, Dragoş-Victor; Nemnes, George Alexandru

    2016-12-01

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

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

    PubMed

    Vieira, Joaquim M; Riley, Paul R

    2013-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1993-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Liu, Yizhuang; Shuryak, Edward; Zahed, Ismail

    2016-11-01

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

  3. 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...

  4. 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.

  5. Strangeness detection in ALICE experiment at LHC

    SciTech Connect

    Safarik, K.

    1995-07-15

    The authors present some parameters of the ALICE detector which concern the detection of strange particles. The results of a simulation for neutral strange particles and cascades, together with estimated rates are presented. They also briefly discuss the detection of charged K-mesons. Finally, they mention the possibility of open charm particle detection.

  6. Maximum rotation frequency of strange stars

    SciTech Connect

    Zdunik, J.L.; Haensel, P. )

    1990-07-15

    Using the MIT bag model of strange-quark matter, we calculate the maximum angular frequency of the uniform rotation of strange stars. After studying a broad range of the MIT bag-model parameters, we obtain an upper bound of 12.3 kHz.

  7. Strangeness production with protons and pions

    SciTech Connect

    Dover, C.B.

    1993-04-01

    We discuss the spectrum of physics questions related to strangeness which could be addressed with intense beams of protons and pions in the few GeV region. We focus on various aspects of strangeness production, including hyperon production in pp collisions, studies of hyperon-nucleon scattering, production of hypernuclei in proton and pion-nucleus collisions, and spin phenomena in hypernuclei.

  8. Strange quark matter in the presence of explicit symmetry breaking interactions

    NASA Astrophysics Data System (ADS)

    Moreira, J.; Morais, J.; Hiller, B.; Osipov, A. A.; Blin, A. H.

    2015-06-01

    It is shown that a first-order transition associated with a jump in the strange-quark mass appears in a generalized three-flavor Nambu-Jona-Lasinio treatment of quark matter. The generalization of the Lagrangian displays the complete set of spin-0 interactions at leading and subleading orders (LO and NLO) in 1/Nc counting, including the recently derived NLO explicit chiral symmetry breaking interactions which are of the same order as the 't Hooft flavor determinant. The parameters of the model are tightly constrained by the low-energy characteristics in both the pseudoscalar and scalar meson sectors. The transition occurs in a moderate chemical potential region (μ ≃400 MeV for zero temperature) in addition to the usual chiral transition associated with the light-quark sector. This feature has at its root the inclusion of the explicit chiral symmetry breaking interactions, which therefore can be seen to act as a catalyst in the production of strange-quark matter when compared to the conventional version of the model that takes only into account the 't Hooft interaction in the NLO. It can be traced back to the effect of the interactions which do not violate the Okubo-Zweig-Iizuka rule, without which the empirical ordering of the scalars (mK⋆

  9. The Maximum Mass of Rotating Strange Stars

    NASA Astrophysics Data System (ADS)

    Szkudlarek, M.; Gondek-Rosiń; ska, D.; Villain, L.; Ansorg, M.

    2012-12-01

    Strange quark stars are considered as a possible alternative to neutron stars as compact objects (e.g. Weber 2003). A hot compact star (a proto-neutron star or a strange star) born in a supernova explosion or a remnant of neutron stars binary merger are expected to rotate differentially and be important sources of gravitational waves. We present results of the first relativistic calculations of differentially rotating strange quark stars for broad ranges of degree of differential rotation and maximum densities. Using a highly accurate, relativistic code we show that rotation may cause a significant increase of maximum allowed mass of strange stars, much larger than in the case of neutron stars with the same degree of differential rotation. Depending on the maximum allowed mass a massive neutron star (strange star) can be temporarily stabilized by differential rotation or collapse to a black hole.

  10. Strangeness-conserving hadronic parity violation at low energies

    NASA Astrophysics Data System (ADS)

    Liu, C.-P.

    2007-05-01

    The parity-violating nucleaon interacton is the key to understanding the strangeness-conserving hadronic weak interaction at low energies. In this brief talk, I review the past accomplishement in and current status of this subject, and outline a new joint effort between experiment and theory that that tries to address the potential problems in the past by focusing on parity violation in few-nucleon systems and using the language of effective field theory.

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

    PubMed

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

    2016-01-19

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

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Chen, Kaifeng; Fan, Shanhui

    2016-12-01

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

  15. Bottom-strange mesons in hyperonic matter

    NASA Astrophysics Data System (ADS)

    Pathak, Divakar; Mishra, Amruta

    2014-11-01

    The in-medium behavior of bottom-strange pseudoscalar mesons in hot, isospin asymmetric and dense hadronic environment is studied using a chiral effective model. The same was recently generalized to the heavy quark sector and employed to study the behavior of open-charm and open-bottom mesons. The heavy quark (anti-quark) is treated as frozen and all medium modifications of these bottom-strange mesons are due to their strange anti-quark (quark) content. We observe a pronounced dependence of their medium mass on baryonic density and strangeness content of the medium. Certain aspects of these in-medium interactions are similar to those observed for the strange-charmed mesons in a preceding investigation, such as the lifting of mass-degeneracy of BS0 and {\\bar B}S0 mesons in hyperonic matter, while the same is respected in vacuum as well as in nuclear matter. In general, however, there is a remarkable distinction between the two species, even though the formalism predicts a completely analogous in-medium interaction Lagrangian density. We discuss in detail the reason for different in-medium behavior of these bottom-strange mesons as compared to charmed-strange mesons, despite the dynamics of the heavy quark being treated as frozen in both cases.

  16. and : candidates for charmed-strange mesons

    NASA Astrophysics Data System (ADS)

    Song, Qin-Tao; Chen, Dian-Yong; Liu, Xiang; Matsuki, Takayuki

    2015-01-01

    Newly observed two charmed-strange resonances, and , are investigated by calculating their Okubo-Zweig-Iizuka-allowed strong decays, which shows that they are suitable candidates for the and states in the charmed-strange meson family. Our study also predicts other main decay modes of and , which can be accessible at the future experiment. In addition, the decay behaviors of the spin partners of and , i.e., and , are predicted in this work, which are still missing at present. The experimental search for the missing and charmed-strange mesons is an intriguing and challenging task for further experiments.

  17. Ultrarelativistic cascades and strangeness production

    SciTech Connect

    Kahana, D.E.; Kahana, S.H.

    1998-02-01

    A two phase cascade, LUCIFER II, developed for the treatment of ultra high energy Ion-Ion collisions is applied to the production of strangeness at SPS energies. This simulation is able to simultaneously describe both hard processes such as Drell-Yan and slower, soft processes such as the production of light mesons by separating the dynamics into two steps, a fast cascade involving only the nucleons in the original colliding relativistic ions followed, after an appropriate delay, by a normal multiscattering of the resulting excited baryons and mesons produced virtually in the first step. No energy loss can take place in the short time interval over which the first cascade takes place. The chief result is a reconciliation of the important Drell-Yan measurements with the apparent success of standard cascades to describe the nucleon stopping and meson production in heavy ion experiments at the CERN SPS.

  18. Examination of strangeness instabilities and effects of strange meson couplings in dense strange hadronic matter and compact stars

    NASA Astrophysics Data System (ADS)

    Torres, James R.; Gulminelli, Francesca; Menezes, Débora P.

    2017-02-01

    Background: The emergence of hyperon degrees of freedom in neutron star matter has been associated to first-order phase transitions in some phenomenological models, but conclusions on the possible physical existence of an instability in the strangeness sector are strongly model dependent. Purpose: The purposes of the present study are to assess whether strangeness instabilities are related to specific values of the largely unconstrained hyperon interactions and to study the effect of the strange meson couplings on phenomenological properties of neutron stars and supernova matter, once these latter are fixed to fulfill the constraints imposed by hypernuclear data. Method: We consider a phenomenological relativistic mean field model (RMF) model sufficiently simple to allow a complete exploration of the parameter space. Results: We show that no instability at supersaturation density exists for the RMF model, as long as the parameter space is constrained by basic physical requirements. This is at variance with a nonrelativistic functional, with a functional behavior fitted through ab initio calculations. Once the study is extended to include the full octet, we show that the parameter space allows reasonable radii for canonical neutron stars as well as massive stars above two-solar mass, together with an important strangeness content of the order of 30%, slightly decreasing with increasing entropy, even in the absence of a strangeness-driven phase transition. Conclusions: We conclude that the hyperon content of neutron stars and supernova matter cannot be established with present constraints, and is essentially governed by the unconstrained coupling to the strange isoscalar meson.

  19. Strange Baryonic Matter and Kaon Condensation

    NASA Astrophysics Data System (ADS)

    Gazda, D.; Friedman, E.; Gal, A.; Mareš, J.

    In this contribution we address the question whether kaon condensation could occur in strongly interacting self-bound strange hadronic matter. In our comprehensive dynamical relativistic mean-field (RMF) calculations of nuclear and hypernuclear systems containing several antikaons we found saturation of bar K separation energy as well as the associated nuclear and bar K density distributions upon increasing the number of bar K mesons. The saturation pattern was found to be a universal feature of these multi-strangeness configurations. Since in all cases the bar K separation energy does not exceed 200 MeV, we conclude that bar K mesons do not provide the physical "strangeness" degrees of freedom for self-bound strange hadronic matter.

  20. Strange Creatures: An Additive Wood Sculpture Project.

    ERIC Educational Resources Information Center

    Wales, Andrew

    2002-01-01

    Describes an art project where students create strange creatures using scraps of wood. Discusses how the students use the wood and other materials. Explains that the students also write about the habitat characteristics of their creatures. Includes learning objectives. (CMK)

  1. Strange quark matter fragmentation in astrophysical events

    NASA Astrophysics Data System (ADS)

    Paulucci, L.; Horvath, J. E.

    2014-06-01

    The conjecture of Bodmer-Witten-Terazawa suggesting a form of quark matter (Strange Quark Matter) as the ground state of hadronic interactions has been studied in laboratory and astrophysical contexts by a large number of authors. If strange stars exist, some violent events involving these compact objects, such as mergers and even their formation process, might eject some strange matter into the interstellar medium that could be detected as a trace signal in the cosmic ray flux. To evaluate this possibility, it is necessary to understand how this matter in bulk would fragment in the form of strangelets (small lumps of strange quark matter in which finite effects become important). We calculate the mass distribution outcome using the statistical multifragmentation model and point out several caveats affecting it. In particular, the possibility that strangelets fragmentation will render a tiny fraction of contamination in the cosmic ray flux is discussed.

  2. Strangeness contributions to nucleon form factors

    SciTech Connect

    Ross Young

    2006-09-11

    We review a recent theoretical determination of the strange quark content of the electromagnetic form factors of the nucleon. These are compared with a global analysis of current experimental measurements in parity-violating electron scattering.

  3. 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

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

    PubMed

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

    2014-01-30

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

  5. 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}.

  6. Black hole phase transitions and the chemical potential

    NASA Astrophysics Data System (ADS)

    Maity, Reevu; Roy, Pratim; Sarkar, Tapobrata

    2017-02-01

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

  7. Strangeness Physics with CLAS at Jefferson Lab

    SciTech Connect

    Burkert, Volker

    2009-10-01

    A brief overview of strangeness physics with the CLAS detector at JLab is given, mainly covering the domain of nucleon resonances. Several excited states predicted by the symmetric constituent quark model may have signiffcant couplings to the K+ or K0 channels. I will discuss data that are relevant in the search for such states in the strangeness channel, and give an outlook on the future prospects of the N* program at JLab with electromagnetic probes.

  8. 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.

  9. 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...

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

    PubMed

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

    2017-01-05

    In this work, carbon black waste - a hazardous solid residue generated from gasification of crude oil bottom in refineries - was successfully used for making an absorbent material. However, since the carbon black waste also contains significant amounts of heavy metals (especially nickel and vanadium), chemical leaching was first used to remove these hazardous impurities from the carbon black waste. Acid leaching with nitric acid was found to be a very effective method for removal of both nickel and vanadium from the carbon black waste (i.e. up to 95% nickel and 98% vanadium were removed via treatment with 2M nitric acid for 1h at 20°C), whereas alkali leaching by using NaOH under the same condition was not effective for removal of nickel (less than 10% nickel was removed). Human lung cells (MRC-5) were then used to investigate the toxicity of the carbon black waste before and after leaching. Cell viability analysis showed that the leachate from the original carbon black waste has very high toxicity, whereas the leachate from the treated samples has no significant toxicity. Finally, the efficacy of the carbon black waste treated with HNO3 as an absorbent for dye removal was investigated. This treated carbon black waste has high adsorption capacity (∼361.2mg dye/g carbonblack), which can be attributed to its high specific surface area (∼559m(2)/g). The treated carbon black waste with its high adsorption capacity and lack of cytotoxicity is a promising adsorbent material. Moreover, the carbon black waste was found to show high electrical conductivity (ca. 10S/cm), making it a potentially valuable source of conductive material.

  11. Theoretical perspectives on strange physics

    SciTech Connect

    Ellis, J.

    1983-04-01

    Kaons are heavy enough to have an interesting range of decay modes available to them, and light enough to be produced in sufficient numbers to explore rare modes with satisfying statistics. Kaons and their decays have provided at least two major breakthroughs in our knowledge of fundamental physics. They have revealed to us CP violation, and their lack of flavor-changing neutral interactions warned us to expect charm. In addition, K/sup 0/-anti K/sup 0/ mixing has provided us with one of our most elegant and sensitive laboratories for testing quantum mechanics. There is every reason to expect that future generations of kaon experiments with intense sources would add further to our knowledge of fundamental physics. This talk attempts to set future kaon experiments in a general theoretical context, and indicate how they may bear upon fundamental theoretical issues. A survey of different experiments which would be done with an Intense Medium Energy Source of Strangeness, including rare K decays, probes of the nature of CP isolation, ..mu.. decays, hyperon decays and neutrino physics is given. (WHK)

  12. Strangeness asymmetry in the proton sea

    NASA Astrophysics Data System (ADS)

    Alberg, Mary

    2015-10-01

    Meson cloud models describe the proton sea in terms of fluctuations of the proton into meson-baryon pairs. The leading contributions to proton strangeness are from states which contain a kaon and a Lambda or Sigma hyperon. We use a Fock state expansion of the proton in terms of these states to determine the strangeness distributions of the proton in a convolution model, in which the fluctuations are represented by meson-baryon splitting functions, which determine the total strangeness of the proton. Strangeness asymmetry, the difference between momentum distributions of the s and sbar quarks in the proton, arises because the quarks are constituents of different hadrons. For the parton distributions of the s(sbar) quarks in the bare baryons(mesons) of the Fock states, we use light cone wave functions or our statistical model, which expands the bare hadrons in terms of quark-gluon states. We show that strangeness asymmetry depends strongly on the parton distributions used for the hadrons in the cloud. We compare our results to NuTeV and to global parton distributions. This research has been supported in part by NSF Award 1205686.

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

    NASA Astrophysics Data System (ADS)

    Balcerzak, T.; Szałowski, K.

    2017-02-01

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

  14. Momentum distributions of strange and anti-strange quarks in the proton

    NASA Astrophysics Data System (ADS)

    Hansen, Chase; Raschko, David; Netzel, Greg

    2013-10-01

    Strangeness in the proton has been confirmed by experiment. We are using the statistical method of Zhang et al., which explained the u - d asymmetry in the proton. We expand the model to include strange quarks, to explain the existence of strangeness in the proton. We used RAMBO in order to create a Bjorken-x distribution for the partons in the proton. We adjusted RAMBO to include the strange quark mass. In order to suppress the transitions to states that include s - s pairs, we calculate energy distributions for the gluons and allow gluons to split into s - s pairs only if the gluon is above the energy threshold of twice the mass of a strange quark. We expand our view to include the meson cloud model, attempting a different approach at explaining strangeness in the proton. After Q2 evolution, we compare our calculations of strangeness probability and S+ (x) to HERMES and ATLAS data, as well as global parton distribution fits. Supported in part by NSF Grants No. 0855656 and 1205686.

  15. 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...

  16. 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...

  17. Measurements of strangeness production in the STAR experiment at RHIC

    SciTech Connect

    Wilson, W.K.

    1995-07-15

    Simulations of the ability of the STAR (Solenoidal Tracker at RHIC) detector to measure strangeness production in central Au+Au collisions at RHIC are presented. Emphasis is placed on the reconstruction of short lived particles using a high resolution inner tracker. The prospects for performing neutral kaon interferometry are discussed. Simulation results for measurements of strange and multi-strange baryons are presented.

  18. Characterization of strange attractors as inhomogeneous fractals

    NASA Astrophysics Data System (ADS)

    Paladin, G.; Vulpiani, A.

    1984-09-01

    The geometry of strange attractors of chaotic dynamical systems is investigated analytically within the framework of fractal theory. A set of easily computable exponents which generalize the fractal dimensionality and characterize the inhomogeneity of the fractals of strange attractors is derived, and sample computations are shown. It is pointed out that the fragmentation process described is similar to models of intermittency in fully developed turbulence. The exponents for the sample problems are computed in the same amount of CPU time as the computation of nu by the method of Grassberger and Procaccia (1983) but provide more information; less time is required than for the nu(n) computation of Hentschel and Procaccia (1983).

  19. Recent results from strangeness in transport models

    NASA Astrophysics Data System (ADS)

    Steinheimer, J.; Botvina, A. S.; Bleicher, M.

    2016-01-01

    In these proceedings we discuss recent developments in the microscopic description of strange particle production in nuclear collisions. We put a special emphasis on the production of hypernuclei at the upcoming FAIR and NICA facilities as well as the deep sub threshold, ϕ and Ξ- production yields measured with the HADES experiment. Employing new resonance decay channels we obtain a satisfactory description of ϕ and Ξ- production in deep sub threshold Ar+KCl reactions. Our results implicate that no new medium effects are required to describe the rare strange particle production data from low energy nuclear collisions.

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

    SciTech Connect

    Sabine Brueske, Caroline Kramer, Aaron Fisher

    2015-06-01

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

  1. 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...

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    Settles, Gary S.; McGann, William J.

    2001-08-01

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

  4. 'Strange money': risk, finance and socialized debt.

    PubMed

    Dodd, Nigel

    2011-03-01

    This paper explores an essential but neglected aspect of recent discussions of the banking and financial system, namely money itself. Specifically, I take up a distinction drawn by Susan Strange which has never been fully elaborated: between a financial system that is global, and an international monetary system that remains largely territorial. I propose a sociological elaboration of this distinction by examining each category, 'finance' and 'money', in terms of its distinctive orientation to risk and debt. Money is distinguished by its high degree of liquidity and low degree of risk, corresponding to expectations that derive from its status as a 'claim upon society'- a form of socialized debt. But as Strange argued, these features of money are being undermined by the proliferation of sophisticated instruments of financial risk management -'strange money'- that, as monetary substitutes, both weaken states' capacity to manage money, and more broadly, contribute to 'overbanking'. The ultimate danger, according to Strange, is the 'death of money'. The paper concludes by exploring the implications of the distinction for sociological arguments about the changing nature of money.

  5. The mystery of the strange formulae

    NASA Astrophysics Data System (ADS)

    Bracken, Tony

    2016-10-01

    On a recent visit to the Wilhelm Röntgen memorial in Wurzburg, Germany, I noticed two strange trigonometric formulae set in the terrazzo floor at the western entrance to the building that houses Röntgen's X-ray laboratory.

  6. Last orbits of binary strange quark stars

    SciTech Connect

    Limousin, Francois; Gourgoulhon, Eric; Gondek-Rosinska, Dorota

    2005-03-15

    We present the first relativistic calculations of the final phase of inspiral of a binary system consisting of two stars built predominantly of strange quark matter (strange quark stars). We study the precoalescing stage within the Isenberg-Wilson-Mathews approximation of general relativity using a multidomain spectral method. A hydrodynamical treatment is performed under the assumption that the flow is either rigidly rotating or irrotational, taking into account the finite density at the stellar surface--a distinctive feature with respect to the neutron star case. The gravitational-radiation driven evolution of the binary system is approximated by a sequence of quasiequilibrium configurations at fixed baryon number and decreasing separation. We find that the innermost stable circular orbit (ISCO) is given by an orbital instability both for synchronized and irrotational systems. This contrasts with neutron stars for which the ISCO is given by the mass-shedding limit in the irrotational case. The gravitational wave frequency at the ISCO, which marks the end of the inspiral phase, is found to be {approx}1400 Hz for two irrotational 1.35 M{sub {center_dot}} strange stars and for the MIT bag model of strange matter with massless quarks and a bag constant B=60 MeV fm{sup -3}. Detailed comparisons with binary neutrons star models, as well as with third order post-Newtonian point-mass binaries are given.

  7. Spontaneous superfluid current generation in the kaon condensed color flavor locked phase at nonzero strange quark mass

    SciTech Connect

    Kryjevski, Andrei

    2008-01-01

    We find that for a large enough strange quark mass, m{sub s}{sup 2}/4{mu}{delta}>2/3(1-0.023) ({mu} is the quark number chemical potential, {delta} is the superconducting gap), the kaon condensed color flavor locked (CFL) phase of asymptotically dense strongly interacting 3 flavor quark matter is unstable with respect to spontaneous generation of currents of Nambu Goldstone bosons due to spontaneous breaking of baryon number symmetry and hypercharge symmetry in the CFLK{sup 0} ground state. The total baryon and hypercharge currents vanish in the ground state. We find that CFLK{sup 0} and the new state are separated by a first order phase transition. The result is derived in the mean field approximation of high density effective theory with electromagnetic interactions turned off.

  8. Potential Military Chemical/Biological Agents and Compounds

    DTIC Science & Technology

    2005-01-01

    toxins, bioregulators, or prions. (1) Pathogens. Pathogens are disease-producing microorganisms,6 such as bacteria , rickettsiae , or viruses...disability. Potential biological antipersonnel agents include toxins, bacteria , rickettsiae , viruses, and toxins. (2) Antianimal. Biological...microorganisms such as pathogens (which include disease-causing bacteria , rickettsiae , and viruses) and toxins. NOTES: 1. See Table IV-1 (page IV-2) for the

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

    PubMed

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

    2012-10-01

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

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

    PubMed

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

    2013-09-28

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

  11. 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.

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

    SciTech Connect

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

    1994-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Jury, William A.; Tseng, Peng-Hsiang

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

  14. 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.

  15. 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.

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

    PubMed

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

    2015-12-01

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

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

    PubMed Central

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

    2016-01-01

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

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

    EPA Science Inventory

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

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

    EPA Science Inventory

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

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

  20. 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…

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

    EPA Pesticide Factsheets

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

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

    EPA Science Inventory

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

  3. Unique signatures for QGP in strangeness sector

    NASA Astrophysics Data System (ADS)

    Tiwari, V. K.; Singh, C. P.

    1998-03-01

    We suggest that the variations of certain strange particle ratios either with the energy density or with the baryon density constitute a significant signal for identification of the QGP formation in ultra-relativistic nucleus-nucleus collisions. We use realistic equations of state (EOS) for the QGP as well as for dense, hot hadron gas (HG) scenarios. We suggest that a direct comparison of the ratios obtained in the QGP and HG scenarios will be immensely helpful in identifying the QGP formation.

  4. Charmed-strange mesons revisited: Mass spectra and strong decays

    NASA Astrophysics Data System (ADS)

    Song, Qin-Tao; Chen, Dian-Yong; Liu, Xiang; Matsuki, Takayuki

    2015-03-01

    Inspired by the present experimental status of charmed-strange mesons, we perform a systematic study of the charmed-strange meson family in which we calculate the mass spectra of the charmed-strange meson family by taking a screening effect into account in the Godfrey-Isgur model and investigate the corresponding strong decays via the quark pair creation model. These phenomenological analyses of charmed-strange mesons not only shed light on the features of the observed charmed-strange states, but also provide important information on future experimental search for the missing higher radial and orbital excitations in the charmed-strange meson family, which will be a valuable task in LHCb, the forthcoming Belle II, and PANDA.

  5. Complete strangeness measurements in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Tomášik, Boris; Kolomeitsev, Evgeni E.

    2016-08-01

    We discuss strangeness production in heavy-ion collisions within and around the energy range of the planned NICA facility. We describe a minimal statistical model, in which the total strangeness yield is fixed by the observed or calculated K+ multiplicity. We show how the exact strangeness conservation can be taken into account on event-by-event basis in such a model. We argue that from strange particle yields one can reveal information about the collision dynamics and about possible modifications of particle properties in medium. This can be best achieved if the complete strangeness measurement is performed, i.e. kaons, antikaons, hyperons and multistrange hyperons are registered in the same experimental setup. In particular, production of hadrons containing two and more strange quarks, like Ξ and Ω baryons could be of interest.

  6. Strangeness production in antiproton annihilation on nuclei

    NASA Astrophysics Data System (ADS)

    Cugnon, J.; Deneye, P.; Vandermeulen, J.

    1990-04-01

    The strangeness production in antiproton annihilation on nuclei is investigated by means of a cascade-type model, within the frame of the conventional picture of the annihilation on a single nucleon followed by subsequent rescattering proceeding in the hadronic phase. The following hadrons are introduced: N, Λ, Σ, Λ¯, π, η, ω, K, and K¯ and, as far as possible, the experimental reaction cross sections are used in our simulation. The numerical results are compared with experimental data up to 4 GeV/c. The Λ¯ yield is correctly reproduced, while the Λ and Ks yields are overestimated in the p¯Ta and p¯Ne cases. On the other hand, the rapidity and perpendicular momentum distributions are well reproduced. It is shown that total strange yield is not very much affected by the associated production taking place during the rescattering process. It is also shown that the Λ/Ks ratio is largely due to the strangeness exchange reactions induced by antikaons. In particular, values of the order of 1 to 3 are expected in the energy range investigated here, independently of the detail of the hadronic phase dynamics. Finally, it is stressed that rapidity distributions are consistent with the rescattering process. Comparison with other works and implications of our results are examined.

  7. Strangeness in the baryon ground states

    NASA Astrophysics Data System (ADS)

    Semke, A.; Lutz, M. F. M.

    2012-10-01

    We compute the strangeness content of the baryon octet and decuplet states based on an analysis of recent lattice simulations of the BMW, PACS, LHPC and HSC groups for the pion-mass dependence of the baryon masses. Our results rely on the relativistic chiral Lagrangian and large-Nc sum rule estimates of the counter terms relevant for the baryon masses at N3LO. A partial summation is implied by the use of physical baryon and meson masses in the one-loop contributions to the baryon self energies. A simultaneous description of the lattice results of the BMW, LHPC, PACS and HSC groups is achieved. From a global fit we determine the axial coupling constants F ≃ 0.45 and D ≃ 0.80 in agreement with their values extracted from semi-leptonic decays of the baryons. Moreover, various flavor symmetric limits of baron octet and decuplet masses as obtained by the QCDSF-UKQCD group are recovered. We predict the pion- and strangeness sigma terms and the pion-mass dependence of the octet and decuplet ground states at different strange quark masses.

  8. 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.

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

    PubMed

    Cohen, Thomas D

    2003-11-28

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

  10. Strange fireball as an explanation of the muon excess in Auger data

    NASA Astrophysics Data System (ADS)

    Anchordoqui, Luis A.; Goldberg, Haim; Weiler, Thomas J.

    2017-03-01

    We argue that ultrahigh-energy cosmic-ray collisions in Earth's atmosphere can probe the strange quark density of the nucleon. These collisions have center-of-mass energies ≳1 04.6A GeV , where A ≥14 is the nuclear baryon number. We hypothesize the formation of a deconfined thermal fireball which undergoes a sudden hadronization. At production the fireball has a very high matter density and consists of gluons and two flavors of light quarks (u , d ). Because the fireball is formed in the baryon-rich projectile fragmentation region, the high baryochemical potential damps the production of u u ¯ and d d ¯ pairs, resulting in gluon fragmentation mainly into s s ¯. The strange quarks then become much more abundant and upon hadronization the relative density of strange hadrons is significantly enhanced over that resulting from a hadron gas. Assuming the momentum distribution functions can be approximated by Fermi-Dirac and Bose-Einstein statistics, we estimate a kaon-to-pion ratio of about 3 and expect a similar (total) baryon-to-pion ratio. We show that, if this were the case, the excess of strange hadrons would suppress the fraction of energy which is transferred to decaying π0's by about 20%, yielding an ˜40 % enhancement of the muon content in atmospheric cascades, in agreement with recent data reported by the Pierre Auger Collaboration.

  11. 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...

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

    PubMed

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

    2016-09-14

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

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

    PubMed

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

    2014-01-01

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

  14. Strange baryonic resonances and resonances coupling to strange hadrons at SIS energies

    NASA Astrophysics Data System (ADS)

    Fabbietti, L.

    2016-01-01

    The role played by baryonic resonances in the production of final states containing strangeness for proton-proton reactions at 3.5 GeV measured by HADES is discussed by means of several very different measurements. First the associate production of Δ resonances accompanying final states with strange hadrons is presented, then the role of interferences among N* resonances, as measured by HADES for the first time, is summarised. Last but not least the role played by heavy resonances, with a mass larger than 2 GeV/c2 in the production of strange and non-strange hadrons is discussed. Experimental evidence for the presence of a Δ(2000)++ are presented and hypotheses are discussed employing the contribution of similar objects to populate the excesses measured by HADES for the Ξ in A+A and p+A collisions and in the dilepton sector for A+A collisions. This extensive set of results helps to better understand the dynamic underlaying particle production in elementary reactions and sets a more solid basis for the understanding of heavy ion collisions at the same energies and even higher as planned at the FAIR facility.

  15. Strange baryonic resonances and resonances coupling to strange hadrons at SIS energies

    SciTech Connect

    Fabbietti, L.

    2016-01-22

    The role played by baryonic resonances in the production of final states containing strangeness for proton-proton reactions at 3.5 GeV measured by HADES is discussed by means of several very different measurements. First the associate production of Δ resonances accompanying final states with strange hadrons is presented, then the role of interferences among N{sup *} resonances, as measured by HADES for the first time, is summarised. Last but not least the role played by heavy resonances, with a mass larger than 2 GeV/c{sup 2} in the production of strange and non-strange hadrons is discussed. Experimental evidence for the presence of a Δ(2000){sup ++} are presented and hypotheses are discussed employing the contribution of similar objects to populate the excesses measured by HADES for the Ξ in A+A and p+A collisions and in the dilepton sector for A+A collisions. This extensive set of results helps to better understand the dynamic underlaying particle production in elementary reactions and sets a more solid basis for the understanding of heavy ion collisions at the same energies and even higher as planned at the FAIR facility.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

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

  18. 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.

  19. TORSIONAL OSCILLATIONS OF NONBARE STRANGE STARS

    SciTech Connect

    Mannarelli, Massimo; Pagliaroli, Giulia; Parisi, Alessandro; Pilo, Luigi; Tonelli, Francesco

    2015-12-20

    Strange stars are one of the possible compact stellar objects that can form after a supernova collapse. We consider a model of a strange star having an inner core in the color-flavor locked phase surmounted by a crystalline color superconducting (CCSC) layer. These two phases constitute the quarksphere, which we assume to be the largest and heaviest part of the strange star. The next layer consists of standard nuclear matter forming an ionic crust, hovering on the top of the quarksphere and prevented from falling by a strong dipolar electric field. The dipolar electric field arises because quark matter is confined in the quarksphere by the strong interaction, but electrons can leak outside forming an electron layer a few hundred fermi thick separating the ionic crust from the underlying quark matter. The ionic matter and the CCSC matter constitute two electromagnetically coupled crust layers. We study the torsional oscillations of these two layers. Remarkably, we find that if a fraction larger than 10{sup −4} of the energy of a Vela-like glitch is conveyed to a torsional oscillation, the ionic crust will likely break. The reason is that the very rigid and heavy CCSC crust layer will absorb only a small fraction of the glitch energy, leading to a large-amplitude torsional oscillation of the ionic crust. The maximum stress generated by the torsional oscillation is located inside the ionic crust and is very close to the star’s surface. This peculiar behavior leads to a much easier crust cracking than in standard neutron stars.

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

    PubMed

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

    2015-06-01

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

  1. 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

  2. Strangeness and charm production in high energy heavy ion collisions

    SciTech Connect

    Xu, Nu

    2001-01-01

    We discuss the dynamical effects of strangeness and charm production in high energy nuclear collisions. In order to understand the early stage dynamical evolution, it is necessary to study the transverse momentum distributions of multi-strange hadrons like {Xi} and {Omega} and charm mesons like J/{Psi} as a function of collision centrality.

  3. Strange Quark Matter Status and Prospects

    NASA Technical Reports Server (NTRS)

    Sandweiss, J.

    2004-01-01

    The existence of quark states with more than three quarks is allowed in QCD. The stability of such quark matter states has been studied with lattice QCD and phenomenological bag models, but is not well constrained by theory. The addition of strange quarks to the system allows the quarks to be in lower energy states despite the additional mass penalty. There is additional stability from reduced Coulomb repulsion. SQM is expected to have a low Z/A. Stable or metastable massive multiquark states contain u, d, and s quarks.

  4. Kaon condensation and multi-strange matter

    NASA Astrophysics Data System (ADS)

    Gazda, D.; Friedman, E.; Gal, A.; Mareš, J.

    2010-04-01

    We report on dynamical calculations of multi- K¯ hypernuclei, which were performed by adding K¯ mesons to particle-stable configurations of nucleons, Λ and Ξ hyperons. The K¯ separation energy as well as the baryonic densities saturate with the number of antikaons. We demonstrate that the saturation is a robust feature of multi- K¯ hypernuclei. Because the K¯ separation energy B does not exceed 200 MeV, we conclude that kaon condensation is unlikely to occur in finite strong-interaction self-bound {N,Λ,Ξ} strange hadronic systems.

  5. Associated strangeness production on light nuclei

    NASA Astrophysics Data System (ADS)

    Ernst, J.; Kingler, J.; Lippert, C.

    1991-04-01

    The study of light hyper-nuclei via associated strangeness production in (p, K+) reactions is discussed. Though the process is characterized by a very large momentum transfer the presence of short range correlations is expected to rise the cross section up to the order of nb/sr. Two approved proposals for high resolution studies of this reaction are discussed and respective detection limits are presented. The first is scheduled for October 1990 at the SPES4 spectrometer at the SATURNE acclerator (LNS Saclay). The second deals with the planned upgrading of the BIG KARL magnetic spectrograph at the cooled beam facility COSY being bulit at Forschungsanlage Jülich.

  6. Stability of charged strange quark stars

    SciTech Connect

    Arbañil, José D. V.; Malheiro, Manuel

    2015-12-17

    We investigate the hydrostatic equilibrium and the stability of charged stars made of a charged perfect fluid. The matter contained in the star follows the MIT bag model equation of state and the charge distribution to a power-law of the radial coordinate. The hydrostatic equilibrium and the stability of charged strange stars are analyzed using the Tolman-Oppenheimer-Volkoff equation and the Chandrasekhar’s equation pulsation, respectively. These two equation are modified from their original form to the inclusion of the electric charge. We found that the stability of the star decreases with the increment of the central energy density and with the increment of the amount of charge.

  7. Identified Light and Strange Hadron Spectra at √sNN = 14.5 GeV with STAR at RHIC BES I

    NASA Astrophysics Data System (ADS)

    Brandenburg, James Daniel

    2016-08-01

    With the recently measured Au+Au collisions at √sNN=14.5 GeV, RHIC completed its first phase of the Beam Energy Scan (BES) program. The main motivation of the BES program is the search for a conjectured critical point and possible first order phase transition. Amongst the various collision energies of 7.7, 11.5, 19.6, 27, and 39 GeV, that have been previously presented by STAR, collisions at 14.5 GeV will provide data set in the relatively large chemical potential gap between the 11.5 and 19.6 GeV center-of-mass energies. In this contribution, we report new STAR measurements of Au+Au at √sNN=14.5 GeV that include identified light particle RCP and spectra, as well as measurements of the strange hadrons (K0 s, A, ξ, and ω). The spectra from both light and strange particles cover a significant range of the intermediate transverse momentum (2 < pT < 5 GeV/c) in all beam energies. We will discuss the physics implications of these observables and whether hadronic or partonic interactions dominate the collision dynamics at a given center-of-mass energy.

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

    PubMed

    Bloch, Jacques; Wettig, Tilo

    2006-07-07

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

  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. FEROS Finds a Strange Star

    NASA Astrophysics Data System (ADS)

    1999-02-01

    New Spectrograph Explores the Skies from La Silla While a major effort is now spent on the Very Large Telescope and its advanced instruments at Paranal, ESO is also continuing to operate and upgrade the extensive research facilities at La Silla, its other observatory site. ESO PR Photo 03a/99 ESO PR Photo 03a/99 [Preview - JPEG: 800 x 1212 pix - 606k] [High-Res - JPEG: 1981 x 3000 pix - 3.6M] Caption to PR Photo 03a/99 : This photo shows the ESO 1.52-m telescope, installed since almost 30 years in its dome at the La Silla observatory in the southern Atacama desert. The new FEROS spectrograph is placed in an adjacent, thermally and humidity controlled room in the telescope building (where a classical coudé spectrograph was formerly located). The light is guided from the telescope to the spectrograph by 14-m long optical fibres. Within this programme, a new and powerful spectrograph, known as the Fibre-fed Extended Range Optical Spectrograph (FEROS) , has recently been built by a consortium of European institutes. It was commissioned in late 1998 at the ESO 1.52-m telescope by a small team of astronomers and engineers and has already produced the first, interesting scientific results. FEROS is able to record spectra of comparatively faint stars. For instance, it may be used to measure the chemical composition of stars similar to our Sun at distances of up to about 2,500 light-years, or to study motions in the atmospheres of supergiant stars in the Magellanic Clouds. These satellite galaxies to the Milky Way are more than 150,000 light-years away and can only be observed with telescopes located in the southern hemisphere. First FEROS observations uncover an unusual star ESO PR Photo 03b/99 ESO PR Photo 03b/99 [Preview - JPEG: 800 x 958 pix - 390k] [High-Res - JPEG: 3000 x 3594 pix - 1.7M] Caption to PR Photo 03b/99 : This diagramme shows the spectrum of the Lithium rich giant star S50 in the open stellar cluster Be21 , compared to that of a normal giant star ( S156

  11. Dilepton and strangeness production probed with HADES

    SciTech Connect

    Rustamov, A.

    2012-05-15

    With the High Acceptance Di-Electron Spectrometer (HADES) at GSI we have studied dilepton production in the few-GeV energy regime in various collisions systems, from elementary NN, over pA, up to the medium-heavy Ar + KCl system. We have thus confirmed the puzzling results of the former DLS Collaboration at the Bevalac. While we have traced the origin of the excess pair yield in CC collisions to elementary pp and pn processes, in our Ar + KCl data a contribution from the dense phase of the collision has been identified. Together with the e{sup +}e{sup -} pairs, we have also obtained in the Ar + KCl system at 1.76 A GeV a high-statistics data set on open and hidden strangeness, i.e. K{sup {+-}}, K{sub s}{sup 0}, {Lambda}, {phi}, and {Xi}{sup -}, allowing for a comprehensive discussion of strangeness production in this system.

  12. Radial stability of anisotropic strange quark stars

    NASA Astrophysics Data System (ADS)

    Arbañil, José D. V.; Malheiro, M.

    2016-11-01

    The influence of the anisotropy in the equilibrium and stability of strange stars is investigated through the numerical solution of the hydrostatic equilibrium equation and the radial oscillation equation, both modified from their original version to include this effect. The strange matter inside the quark stars is described by the MIT bag model equation of state. For the anisotropy two different kinds of local anisotropic σ = pt-pr are considered, where pt and pr are respectively the tangential and the radial pressure: one that is null at the star's surface defined by pr(R) = 0, and one that is nonnull at the surface, namely, σs = 0 and σs ≠ 0. In the case σs = 0, the maximum mass value and the zero frequency of oscillation are found at the same central energy density, indicating that the maximum mass marks the onset of the instability. For the case σs ≠ 0, we show that the maximum mass point and the zero frequency of oscillation coincide in the same central energy density value only in a sequence of equilibrium configurations with the same value of σs. Thus, the stability star regions are determined always by the condition dM/dρc > 0 only when the tangential pressure is maintained fixed at the star surface's pt(R). These results are also quite important to analyze the stability of other anisotropic compact objects such as neutron stars, boson stars and gravastars.

  13. Strange Particles and Heavy Ion Physics

    SciTech Connect

    Bassalleck, Bernd; Fields, Douglas

    2016-04-28

    This very long-running grant has supported many experiments in nuclear and particle physics by a group from the University of New Mexico. The gamut of these experiments runs from many aspects of Strangeness Nuclear Physics, to rare Kaon decays, to searches for exotic Hadrons such as Pentaquark or H-Dibaryon, and finally to Spin Physics within the PHENIX collaboration at RHIC. These experiments were performed at a number of laboratories worldwide: first and foremost at Brookhaven National Lab (BNL), but also at CERN, KEK, and most recently at J-PARC. In this Final Technical Report we summarize progress and achievements for this award since our last Progress Report, i.e. for the period of fall 2013 until the award’s termination on November 30, 2015. The report consists of two parts, representing our two most recent experimental efforts, participation in the Nucleon Spin Physics program of the PHENIX experiment at RHIC, the Relativistic Heavy Ion Collider at BNL – Task 1, led by Douglas Fields; and participation in several Strangeness Nuclear Physics experiments at J-PARC, the Japan Proton Accelerator Research Center in Tokai-mura, Japan – Task 2, led by Bernd Bassalleck.

  14. Strangeness in STAR experiment at RHIC

    NASA Astrophysics Data System (ADS)

    Shi, Shusu; STAR collaboration

    2017-01-01

    We present the recent results of strangeness production at the mid-rapidity in Au + Au collisions at RHIC, from to 200 GeV. Elliptic asymmetry v 2 of multi-strange baryon Ω and φ mesons are similar to that of pions and protons in the intermediate pT range (2 - 5 GeV/c) in GeV Au + Au collisions, indicating that the major part of collective ow has been built up at partonic stage. The breaking of mass ordering between φ mesons and protons in the low pT range (< 1 GeV/c) is consistent with a picture that φ mesons are less sensitive to later hadronic interaction. The nuclear modification factor R CP and baryon to meson ratio change dramatically when the collision energy is lower than 19.6 GeV. It suggests a possible change of the created QCD medium properties at lower energies compared to those from high energies.

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

    SciTech Connect

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

    2016-03-23

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

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

    PubMed Central

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

    2014-01-01

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

  18. 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...

  19. 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 ...

  20. 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...

  1. 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...

  2. 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.

  3. 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.

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

    EPA Pesticide Factsheets

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

  5. 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.

  6. 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.

  7. 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

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

    PubMed

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

    2015-01-01

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

  9. Strange-face illusions during inter-subjective gazing.

    PubMed

    Caputo, Giovanni B

    2013-03-01

    In normal observers, gazing at one's own face in the mirror for a few minutes, at a low illumination level, triggers the perception of strange faces, a new visual illusion that has been named 'strange-face in the mirror'. Individuals see huge distortions of their own faces, but they often see monstrous beings, archetypal faces, faces of relatives and deceased, and animals. In the experiment described here, strange-face illusions were perceived when two individuals, in a dimly lit room, gazed at each other in the face. Inter-subjective gazing compared to mirror-gazing produced a higher number of different strange-faces. Inter-subjective strange-face illusions were always dissociative of the subject's self and supported moderate feeling of their reality, indicating a temporary lost of self-agency. Unconscious synchronization of event-related responses to illusions was found between members in some pairs. Synchrony of illusions may indicate that unconscious response-coordination is caused by the illusion-conjunction of crossed dissociative strange-faces, which are perceived as projections into each other's visual face of reciprocal embodied representations within the pair. Inter-subjective strange-face illusions may be explained by the subject's embodied representations (somaesthetic, kinaesthetic and motor facial pattern) and the other's visual face binding. Unconscious facial mimicry may promote inter-subjective illusion-conjunction, then unconscious joint-action and response-coordination.

  10. 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.

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

    PubMed

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

    2014-10-01

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

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

    PubMed

    Brown, Trevor N; Wania, Frank

    2008-07-15

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

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

    PubMed

    Neimark, Alexander V; Vishnyakov, Aleksey

    2005-06-15

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

  14. Using low-energy neutrinos from pion decay at rest to probe the proton strangeness.

    PubMed

    Pagliaroli, G; Lujan-Peschard, C; Mitra, M; Vissani, F

    2013-07-12

    The study of the neutral current elastic scattering of neutrinos on protons at lower energies can be used as a compelling probe to improve our knowledge of the strangeness of the proton. We consider a neutrino beam generated from pion decay at rest, as provided by a cyclotron or a spallation neutron source and a 1 kton scintillating detector with a potential similar to the Borexino detector. Despite several backgrounds from solar and radioactive sources, it is possible to estimate two optimal energy windows for the analysis, one between 0.65 and 1.1 MeV and another between 1.73 and 2.2 MeV. The expected number of neutral current events in these two regions, for an exposure of 1 yr, is enough to obtain an error on the strange axial charge 10 times smaller than available at present.

  15. The Universe is a Strange Place

    NASA Astrophysics Data System (ADS)

    Wilczek, Frank

    Our understanding of ordinary matter is remarkably accurate and complete, but it is based on principles that are very strange and unfamiliar. As I'll explain, we've come to understand matter to be a Music of the Void, in a remarkably literal sense. Just as we physicists finalized that wonderful understanding, towards the end of the twentieth century, astronomers gave us back our humility, by informing us that ordinary matter - what we, and chemists and biologists, and astronomers themselves, have been studying all these centuries constitutes only about 5% of the mass of the universe as a whole. I'll describe some of our promising attempts to rise to this challenge by improving, rather than merely complicating, our description of the world.

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

    PubMed

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

    2011-12-07

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

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

    PubMed

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

    2014-04-07

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

  19. Strange Stars, Neutron Stars and Pulsar Emission

    NASA Astrophysics Data System (ADS)

    Benvenuto, O. G.; Horvath, J. E.

    1990-11-01

    RESUMEN. Se ha conjeturado que una partlecula de dieciocho quarks, sin Carga, sin espi'n y sin colar (quark-alfa) podri'a ser estable a ba5as tern peraturas y presiones aiTh COfl respecto a materia extrafla. Presentamos en este trabajo la estmctura de estrellas extraflas incluyendo los efectos y apariencia de parti'culas uark-alfa en las capas exteriores. La estruc tura interna ya no es hoinogenea del centro a la superficie, sino que muestra un centro de materia extrafla, capas s6lidas y una costra delgada de materia normal en la superficie. La superficie de materia nonnal permite la fornaci6n de una magnetosfera, la que se piensa sea el sitlo en donde ocurre la emisi6n del pulsar. La superficie de superflui'do ayuda a explicar el fen6rneno de `glitch', el cual ba sido observado en muchos pulsares. Se discute la ecuaci6n de estado para rnateria quark-alfa relevante en este regimen. ABSTIZACT:It has been conjectured that an quark, uncharged, spinless and colorless particle Cquark-alpha) could be stable at low pressures and temperatures even with respect to strange matter. We present in work tlie structure of stars including the effects of the appearance of quark-alpi' particles ii their outer layers. The internal structure is no longer from tlie center to the surface, but show a strange matter core, a solid and superfluid layers and a thin crust of normal matter at the surface. The normal matter surface allows tlie fon tion of a magnetosphere, whicl is to be tl place where pulsar emission occurs. A superfluid layer helps to explain tlie glitch , wlflch has been observed in . equation of state for quark-alpha matter relevant in regime is also discussed. Keq LA)OtL : ARY S - OF STATF - ?.ACT

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2003-01-01

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

  2. PREFACE: Strangeness in Quark Matter (SQM2009) Strangeness in Quark Matter (SQM2009)

    NASA Astrophysics Data System (ADS)

    Fraga, Eduardo; Kodama, Takeshi; Padula, Sandra; Takahashi, Jun

    2010-09-01

    The 14th International Conference on Strangeness in Quark Matter (SQM2009) was held in Brazil from 27 September to 2 October 2009 at Hotel Atlântico, Búzios, Rio de Janeiro. The conference was jointly organized by Universidade Federal do Rio de Janeiro, Universidade Estadual de Campinas, Centro Brasileiro de Pesquisas Físicas, Universidade de São Paulo, Universidade Estadual Paulista and Universidade Federal do Rio Grande do Sul. Over 120 scientists from Argentina, Brazil, China, France, Germany, Hungary, Italy, Japan, Mexico, The Netherlands, Norway, Poland, Russia, Slovakia, South Africa, Switzerland, the UK and the USA gathered at the meeting to discuss the physics of hot and dense matter through the signals of strangeness and also the behavior of heavy quarks. Group photograph The topics covered were strange and heavy quark production in nuclear collisions, strange and heavy quark production in elementary processes, bulk matter phenomena associated with strange and heavy quarks, and strangeness in astrophysics. In view of the LHC era and many other upcoming new machines, together with recent theoretical developments, sessions focused on `New developments and new facilities' and 'Open questions' were also included. A stimulating round-table discussion on 'Physics opportunities in the next decade in the view of strangeness and heavy flavor in matter' was chaired in a relaxed atmosphere by Grazyna Odyniec and conducted by P Braun-Munzinger, W Florkowski, K Redlich, K Šafařík and H Stöcker, We thank these colleagues for pointing out to young participants new physics directions to be pursued. We also thank J Dunlop and K Redlich for excellent introductory lectures given on the Sunday evening pre-conference session. In spite of the not-so-helpful weather, the beauty and charm of the town of Búzios helped to make the meeting successful. Nevertheless, the most important contributions were the excellent talks, whose contents are part of these proceedings, given

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

    PubMed

    Hui, C-Y; Jagota, A

    2013-09-10

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

  4. 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

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

    PubMed

    Santos, Andrés

    2012-09-21

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

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

    PubMed

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

    2014-10-29

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

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

    SciTech Connect

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

    1995-12-31

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

  8. 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.

  9. 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.

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

    SciTech Connect

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

    2009-02-15

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

  11. 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.

  12. Strangeness production in small and large collision systems at RHIC

    NASA Astrophysics Data System (ADS)

    Heinz, Mark T.

    2006-07-01

    We present measurements of strange and multi-strange hadrons in p+p collisions at √s =200 GeV measured by STAR. We will compare these preliminary results to leading-order (LO) and next-to-leading order (NLO) perturbative QCD models widely believed to describe the production mechanisms. In particular we will point out recent changes of the model calculations which improve the agreement with our data significantly and will discuss the physics consequences. In larger collision systems, produced with heavy ions at RHIC, we observe the centrality dependence of strange and multi-strange particle production. The non-linear dependency between (anti)-hyperon yields and the system size Npart seems to indicate that the correlation volume does not scale exactly with Npart in contradiction to previous assumptions by thermal models.

  13. K meson-nucleus interactions: strangeness and nuclear matter

    SciTech Connect

    Kahana, S.

    1985-01-01

    A brief review is provided of some straightforward K-nuclear and ..lambda..-hypernuclear systems. A discussion of less straightforward speculations on H-dibaryons and strange quark matter by many authors, is also given. 28 refs., 6 figs.

  14. Role of strangeness in hybrid stars and possible observables

    NASA Astrophysics Data System (ADS)

    Dexheimer, V.; Negreiros, R.; Schramm, S.

    2015-05-01

    We study the effects of strangeness on the quark sector of a hybrid-star equation of state. Since the model we use to describe quarks is the same as the one we use to describe hadrons, we can also study the effects of strangeness on the chiral symmetry restoration and deconfinement phase transitions (first order or crossover). Finally, we analyze the combined effects of hyperons and quarks on global properties of hybrid stars such as mass, radius, and cooling profiles. It is found that a large amount of strangeness in the core is related to the generation of twin-star solutions, which can have the same mass as the lower or zero strangeness counterpart, but with smaller radii.

  15. Intriguing aspects of strangeness production at CERN energies

    SciTech Connect

    Odyniec, G.

    1996-07-01

    Strange particle production in pp, pA and AA collisions at CERN SPS energies is reviewed. First results from Pb beam experiments are briefly presented. The emerging picture (still incomplete) is discussed.

  16. 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.

  17. 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.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

    Ebrahimian, N.; Safiee, Z.

    2017-03-01

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

  20. Nucleation of strange matter in dense stellar cores

    SciTech Connect

    Horvath, J.E. Sao Paulo, Sao Paulo ); Benvenuto, O.G. La Plata ); Vucetich, H. La Plata )

    1992-05-15

    We investigate the nucleation of strange quark matter inside hot, dense nuclear matter. Applying Zel'dovich's kinetic theory of nucleation we find a lower limit of the temperature {ital T} for strange-matter bubbles to appear, which happens to be satisfied inside the Kelvin-Helmholtz cooling era of a compact star life but not much after it. Our bounds thus suggest that a prompt conversion could be achieved, giving support to earlier expectations for nonstandard type-II supernova scenarios.

  1. Strange form factors of octet and decuplet baryons

    SciTech Connect

    Hong, Soon-Tae

    1999-11-22

    The strange form factors of baryon octet are evaluated, in the chiral models with the general chiral SU(3) group structure, to yield the theoretical predictions comparable to the recent experimental data of SAMPLE Collaboration and to study the spin symmetries. Other model predictions are also briefly reviewed to compare with our results and then the strange form factors of baryon octet and decuplet are predicted.

  2. Overview of Issues Surrounding Strangeness in the Nucleon

    SciTech Connect

    Thomas, Anthony W.

    2009-12-17

    The calculation of the strangeness content of the nucleon and its experimental verification is a fundamental step in establishing non-perturbative QCD as the correct theory describing the structure of hadrons. It holds a role in QCD analogous to the correct calculation of the Lamb shift in QED. We review the latest developments in the vector and scalar matrix elements of the strange quarks in the proton, where there has recently been considerable progress.

  3. Overview of Issues Surrounding Strangeness in the Nucleon

    SciTech Connect

    A. W. Thomas

    2009-12-01

    The calculation of the strangeness content of the nucleon and its experimental verification is a fundamental step in establishing non-perturbative QCD as the correct theory describing the structure of hadrons. It holds a role in QCD analogous to the correct calculation of the Lamb shift in QED. We review the latest developments in the vector and scalar matrix elements of the strange quarks in the proton, where there has recently been considerable progress.

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

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

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

    PubMed Central

    Battersby, Nigel S.; Wilson, Valerie

    1989-01-01

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

  8. 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

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

    PubMed

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

    2005-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Kwon, Kideok D.; Newton, Aric G.

    2016-10-01

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

  11. Strangeness as a probe to baryon-rich QCD matter at NICA

    NASA Astrophysics Data System (ADS)

    Fukushima, Kenji

    2016-08-01

    We elucidate a prospect of strangeness fluctuation measurements in the heavy-ion collision at NICA energies. The strangeness fluctuation is sensitive to quark deconfinement. At the same time strangeness has a strong correlation with the baryon number under the condition of vanishing net strangeness, which leads to an enhancement of Λ0, Ξ0, Ξ-, and K+ at high baryon density. The baryon density is maximized around the NICA energies, and strangeness should be an ideal probe to investigate quark deconfinement phenomena of baryon-rich QCD matter created at NICA. We also utilize the hadron resonance gas model to estimate a mixed fluctuation of strangeness and baryon number.

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

    NASA Astrophysics Data System (ADS)

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

    1999-01-01

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

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  15. New results on mesons containing strange quarks

    SciTech Connect

    Aston, D.; Awaji, N.; Bienz, T.; Bird, F.; D'Amore, J.; Dunwoodie, W.; Endorf, R.; Fujii, K.; Hayashii, H.; Iwata, S.

    1987-01-01

    Recent results of strange and strangeonium mesons are presented. The data come from a high sensitivity study (4.1 ev/nb) of K/sup -/p interactions at 11 GeV/c using the LASS spectrometer at SLAC. The complete leading orbitally-excited K* series up through J/sup P/ = 5/sup -/ and a substantial number of the expected underlying states are observed decaying into K/sup -/..pi../sup +/, anti K/sub 3//sup 0/..pi../sup +/..pi../sup -/, and K eta final states, and new measurements are made of their masses, widths, and branching ratios. Production of strangeonium states via hypercharge exchange is observed into K/sub 3//sup 0/K/sub 3//sup 0/, K/sup -/K/sup +/, and K/sub 3//sup 0/K/sup + -/..pi../sup - +/ final states. The leading orbitally-excited phi series through J/sup P/ = 3/sup -/ is clearly seen and evidence is presented for additional high spin structure in the 2.2 GeV/c/sup 2/ region. No f/sub 2/(1720) is observed. The K/sub 3//sup 0/K/sup + -/..pi../sup - +/ spectrum is dominated by 1/sup +/(K* anti K + anti K* K) production in the region below 1.6 GeV/c/sup 2/. These results are compared with data on the same systems produced by different production mechanisms. 12 refs., 28 figs.

  16. Atmospheric neutrinos can make beauty strange

    NASA Astrophysics Data System (ADS)

    Harnik, Roni; Larson, Daniel T.; Murayama, Hitoshi; Pierce, Aaron

    2004-05-01

    The large observed mixing angle in atmospheric neutrinos, coupled with grand unification, motivates the search for large mixing between right-handed strange and bottom squarks. Such mixing does not appear in the standard Cabibbo-Kobayashi-Maskawa phenomenology, but may induce significant b→s transitions through gluino diagrams. Working in the mass eigenbasis, we show quantitatively that an O(1) effect on CP violation in B0d→φKS is possible due to a large mixing between sR and bR, while still satisfying constraints from b→sγ. We also include the effect of bL-bR mixing proportional to mbμ tan β. In the case where mbμ tan β≪M2SUSY there may be a large effect in Bs mixing correlated with a large effect in B0d→φKS, typically yielding an unambiguous signal of new physics at Tevatron run II.

  17. Atmospheric neutrinos can make beauty strange

    SciTech Connect

    Harnik, Roni; Larson, Daniel T.; Murayama, Hitoshi; Pierce, Aaron

    2002-12-01

    The large observed mixing angle in atmospheric neutrinos, coupled with Grand Unification, motivates the search for a large mixing between right-handed strange and bottom squarks. Such mixing does not appear in the standard CKM phenomenology, but may induce significant b {yields} s transitions through gluino diagrams. Working in the mass eigenbasis, we show quantitatively that an order one effect on CP violation in B{sub d}{sup 0} {yields} {pi}K{sub S} is possible due to a large mixing between right-handed b and s squarks, while still satisfying constraints from b {yields} s {gamma}. We also include the effect of right- and left-handed bottom squark mixing proportional to m{sub b}{mu} tan{beta}. For small {mu}tan{beta} there may also be a large effect in B{sub s} mixing correlated with a large effect in B{sub d}{sup 0} {yields} {phi}K{sub S}, typically yielding an unambiguous signal of new physics at Tevatron Run II.

  18. 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

  19. Strange mode instability driven finite amplitude pulsations and mass-loss in models of massive zero-age main-sequence stars

    NASA Astrophysics Data System (ADS)

    Yadav, Abhay Pratap; Glatzel, Wolfgang

    2017-02-01

    The stability with respect to radial perturbations of massive zero-age main-sequence stars having solar chemical composition and masses between 50 and 150 M⊙ is reinvestigated. As a first step, a linear non-adiabatic stability analysis is performed, confirming the existence of dynamical strange mode instabilities for models with masses above 58 M⊙. For selected models, the evolution of the strange mode instabilities into the non-linear regime is followed by numerical simulation. The final results of strange mode instabilities are thus found to be finite amplitude pulsations with periods between 3 and 24 h. Mean acoustic luminosities capable to drive winds with mass-loss rates of the order of 0.5 × 10-7 M⊙ yr-1, which can at most marginally affect stellar evolution in the vicinity of the zero-age main sequence, are associated with these finite amplitude pulsations.

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

    NASA Astrophysics Data System (ADS)

    Caracciolo, Sergio; Palumbo, Fabrizio

    2012-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Kopeć, T. K.

    2005-08-01

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

  2. 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.

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

    PubMed Central

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

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

    PubMed

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

    2017-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Estey, Paul Norman

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

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

    PubMed

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

    2009-12-25

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

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

    PubMed

    Caroli, S; Menditto, A; Chiodo, F

    1996-06-01

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

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

    PubMed

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

    2015-01-01

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

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

    PubMed

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

    2016-02-26

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

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

    PubMed

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

    2013-01-01

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

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

    PubMed

    Papilloud, S; Baudraz, D

    2002-02-01

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

  13. 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.

  14. 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

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

    PubMed

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

    2016-01-04

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

  16. 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

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

    PubMed Central

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

    1989-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

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

    NASA Astrophysics Data System (ADS)

    Tutuc, Emanuel

    2015-03-01

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

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

    PubMed

    Pendleton, Jack Norman; Gilmore, Brendan F

    2015-08-01

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

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

    SciTech Connect

    Pillay, P.

    1996-08-01

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

  3. 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

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

    PubMed

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

    2013-01-01

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

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

    PubMed

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

    2013-02-01

    The economic, environmental, and human health impacts of the deepwater horizon (DWH) oil spill have been of significant concern in the general public and among scientists. This study employs parallel experiments to test the effects of crude oil from the DWH oil well, chemical dispersant Corexit 9500A, and dispersant-oil mixture on growth and reproduction in the model organism Caenorhabditis elegans. Both the crude oil and the dispersant significantly inhibited the reproduction of C. elegans. Dose-dependent inhibitions of hatched larvae production were observed in worms exposed to both crude oil and dispersant. Importantly, the chemical dispersant Corexit 9500A potentiated crude oil effects; dispersant-oil mixture induced more significant effects than oil or dispersant-alone exposures. While oil-alone exposure and dispersant-alone exposure have none to moderate inhibitory effects on hatched larvae production, respectively, the mixture of dispersant and oil induced much more significant inhibition of offspring production. The production of hatched larvae was almost completely inhibited by several high concentrations of the dispersant-oil mixture. This suggests a sensitive bioassay for future investigation of oil/dispersant impacts on organisms. We also investigated the effects of crude oil/dispersant exposure at the molecular level by measuring the expressions of 31 functional genes. Results showed that the dispersant and the dispersant-oil mixture induced aberrant expressions of 12 protein-coding genes (cat-4, trxr-2, sdhb-1, lev-8, lin-39, unc-115, prdx-3, sod-1, acr-16, ric-3, unc-68, and acr-8). These 12 genes are associated with a variety of biological processes, including egg-laying, oxidative stress, muscle contraction, and neurological functions. In summary, the toxicity potentiating effect of chemical dispersant must be taken into consideration in future crude oil cleanup applications.

  6. Strangeness production in Si + Au interactions at 14. 6 GeV/c per nucleon

    SciTech Connect

    Hansen, O.

    1989-01-01

    Production of strange particles in proton-proton interactions is systematically suppressed relative to the production of non-strange particles. A first order goal of experiments on strangeness production in nucleus-nucleus collisions is to find out if strangeness is suppressed in a way similar to the p-p interactions or whether the nuclear environment changes the behaviour. This paper investigates this possibility. 13 refs., 1 tab.

  7. Evaluation of in silico tools to predict the skin sensitization potential of chemicals.

    PubMed

    Verheyen, G R; Braeken, E; Van Deun, K; Van Miert, S

    2017-01-01

    Public domain and commercial in silico tools were compared for their performance in predicting the skin sensitization potential of chemicals. The packages were either statistical based (Vega, CASE Ultra) or rule based (OECD Toolbox, Toxtree, Derek Nexus). In practice, several of these in silico tools are used in gap filling and read-across, but here their use was limited to make predictions based on presence/absence of structural features associated to sensitization. The top 400 ranking substances of the ATSDR 2011 Priority List of Hazardous Substances were selected as a starting point. Experimental information was identified for 160 chemically diverse substances (82 positive and 78 negative). The prediction for skin sensitization potential was compared with the experimental data. Rule-based tools perform slightly better, with accuracies ranging from 0.6 (OECD Toolbox) to 0.78 (Derek Nexus), compared with statistical tools that had accuracies ranging from 0.48 (Vega) to 0.73 (CASE Ultra - LLNA weak model). Combining models increased the performance, with positive and negative predictive values up to 80% and 84%, respectively. However, the number of substances that were predicted positive or negative for skin sensitization in both models was low. Adding more substances to the dataset will increase the confidence in the conclusions reached. The insights obtained in this evaluation are incorporated in a web database www.asopus.weebly.com that provides a potential end user context for the scope and performance of different in silico tools with respect to a common dataset of curated skin sensitization data.

  8. COALESCENCE OF STRANGE-QUARK PLANETS WITH STRANGE STARS: A NEW KIND OF SOURCE FOR GRAVITATIONAL WAVE BURSTS

    SciTech Connect

    Geng, J. J.; Huang, Y. F.; Lu, T.

    2015-05-01

    Strange-quark matter (SQM) may be the true ground state of hadronic matter, indicating that the observed pulsars may actually be strange stars (SSs), but not neutron stars. According to the SQM hypothesis, the existence of a hydrostatically stable sequence of SQM stars has been predicted, ranging from 1 to 2 solar mass SSs, to smaller strange dwarfs and even strange planets. While gravitational wave (GW) astronomy is expected to open a new window to the universe, it will shed light on the search for SQM stars. Here we show that due to their extreme compactness, strange planets can spiral very close to their host SSs without being tidally disrupted. Like inspiraling neutron stars or black holes, these systems would serve as new sources of GW bursts, producing strong GWs at the final stage. The events occurring in our local universe can be detected by upcoming GW detectors, such as Advanced LIGO and the Einstein Telescope. This effect provides a unique probe to SQM objects and is hopefully a powerful tool for testing the SQM hypothesis.

  9. Coalescence of Strange-quark Planets with Strange Stars: a New Kind of Source for Gravitational Wave Bursts

    NASA Astrophysics Data System (ADS)

    Geng, J. J.; Huang, Y. F.; Lu, T.

    2015-05-01

    Strange-quark matter (SQM) may be the true ground state of hadronic matter, indicating that the observed pulsars may actually be strange stars (SSs), but not neutron stars. According to the SQM hypothesis, the existence of a hydrostatically stable sequence of SQM stars has been predicted, ranging from 1 to 2 solar mass SSs, to smaller strange dwarfs and even strange planets. While gravitational wave (GW) astronomy is expected to open a new window to the universe, it will shed light on the search for SQM stars. Here we show that due to their extreme compactness, strange planets can spiral very close to their host SSs without being tidally disrupted. Like inspiraling neutron stars or black holes, these systems would serve as new sources of GW bursts, producing strong GWs at the final stage. The events occurring in our local universe can be detected by upcoming GW detectors, such as Advanced LIGO and the Einstein Telescope. This effect provides a unique probe to SQM objects and is hopefully a powerful tool for testing the SQM hypothesis.

  10. The strange flight behaviour of slowly spinning soccer balls

    NASA Astrophysics Data System (ADS)

    Mizota, Taketo; Kurogi, Kouhei; Ohya, Yuji; Okajima, Atsushi; Naruo, Takeshi; Kawamura, Yoshiyuki

    2013-05-01

    The strange three-dimensional flight behaviour of slowly spinning soccer balls is one of the most interesting and unknown phenomenon associated with the trajectories of sports balls. Many spectators have experienced numerous exciting and emotional instances while observing the curious flight behaviour of these balls. We examine the aerodynamic mechanisms of erratic ball behaviours through real flight observations, unsteady force measurements and flow pattern visualisations. The strange behaviour is elucidated by the relationship between the unsteady forces on the ball and the wake flow. The irregular changes in position for twin longitudinal vortices have already been discovered in the supercritical Reynolds number region of a sphere with a smooth surface. This finding is applicable to the strange behaviour of the flight of soccer balls with this supercritical flow. The players, spectators, and television viewers will gain greater insight into the effects of soccer ball flights.

  11. Studies of the Strange Sea-Quarks Spin with Kaons

    NASA Astrophysics Data System (ADS)

    Benmokhtar, Fatiha; Voloshin, Andrew; Goodwill, Justin; Lendacky, Andrew

    2017-01-01

    It is well known that quarks and gluons give the substructure to the nucleons. and understanding of the spin structure of the nucleon in terms of quarks and gluons has been the goal of intense investigations during the last decades. The determination of strangeness is challenging and the only way of determining the strange distribution accurately from data is to improve the semi-inclusive information. This talk is focused on the determination of the strange sea contribution to the nucleon spin through the pseudo-scalar method using semi-inclusive Kaon detection technique with CLAS12 at Jefferson Lab. A Ring Imaging CHerenkov (RICH) detector is under construction and will be used for pion-kaon-proton separation. National Science Foundation #1615067.

  12. A meson cloud model of strangeness asymmetry in the proton

    NASA Astrophysics Data System (ADS)

    Netzel, Greg; Raschko, David; Hansen, Chase

    2013-10-01

    We use a meson cloud model to describe strangeness in the proton. In this model the proton can fluctuate into meson-baryon pairs, as allowed by the Heisenberg uncertainty principle. The leading contributions to strangeness are from the meson-baryon pairs K Λ or K Σ. In this model, the probability of finding strange quark pairs depends on both the splitting functions, which represent the probability of splitting into a given meson-baryon state, and the phenomenological vertex form factors. Because the s and {s} quarks reside in different hadrons, their momentum distributions will differ, as suggested by the NuTeV anomaly and recent global parton distribution fits. We compare our results to other theoretical calculations and to experimental data from HERMES and ATLAS, and to global parton distribution fits. Supported in part by NSF Grants No. 0855656 and 1205686.

  13. Identified Light and Strange Hadron Spectra at √{sNN} = 14.5 GeV and Systematic Study of Baryon/Meson Effect at Intermediate Transverse Momentum with STAR at RHIC BES I

    NASA Astrophysics Data System (ADS)

    Brandenburg, James D.

    2016-12-01

    With the recently measured Au+Au collisions at √{sNN} = 14.5 GeV, STAR completed its first phase of the Beam Energy Scan (BES) program at RHIC. The main motivation of the BES program is the study of the QCD phase diagram and the search for a conjectured critical point. Amongst the various collision energies of 7.7, 11.5, 19.6, 27, and 39 GeV, that have been previously presented by STAR, collisions at 14.5 GeV will provide data set in the relatively large chemical potential gap between the 11.5 and 19.6 GeV center-of-mass energies. In this contribution, we report new STAR measurements of Au+Au at √{sNN} = 14.5 GeV that include identified light particle RCP and spectra, as well as measurements of the strange hadrons (Ks0, Λ , Ξ , Ω, and ϕ). The spectra from both light and strange particles cover a significant range of the intermediate transverse momentum (2

  14. Chemical reactivity and skin sensitization potential for benzaldehydes: can Schiff base formation explain everything?

    PubMed

    Natsch, Andreas; Gfeller, Hans; Haupt, Tina; Brunner, Gerhard

    2012-10-15

    Skin sensitizers chemically modify skin proteins rendering them immunogenic. Sensitizing chemicals have been divided into applicability domains according to their suspected reaction mechanism. The widely accepted Schiff base applicability domain covers aldehydes and ketones, and detailed structure-activity-modeling for this chemical group was presented. While Schiff base formation is the obvious reaction pathway for these chemicals, the in silico work was followed up by limited experimental work. It remains unclear whether hydrolytically labile Schiff bases can form sufficiently stable epitopes to trigger an immune response in the living organism with an excess of water being present. Here, we performed experimental studies on benzaldehydes of highly differing skin sensitization potential. Schiff base formation toward butylamine was evaluated in acetonitrile, and a detailed SAR study is presented. o-Hydroxybenzaldehydes such as salicylaldehyde and the oakmoss allergens atranol and chloratranol have a high propensity to form Schiff bases. The reactivity is highly reduced in p-hydroxy benzaldehydes such as the nonsensitizing vanillin with an intermediate reactivity for p-alkyl and p-methoxy-benzaldehydes. The work was followed up under more physiological conditions in the peptide reactivity assay with a lysine-containing heptapeptide. Under these conditions, Schiff base formation was only observable for the strong sensitizers atranol and chloratranol and for salicylaldehyde. Trapping experiments with NaBH₃CN showed that Schiff base formation occurred under these conditions also for some less sensitizing aldehydes, but the reaction is not favored in the absence of in situ reduction. Surprisingly, the Schiff bases of some weaker sensitizers apparently may react further to form stable peptide adducts. These were identified as the amides between the lysine residues and the corresponding acids. Adduct formation was paralleled by oxidative deamination of the parent

  15. 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

  16. Statistical properties of chaotic dynamical systems which exhibit strange attractors

    SciTech Connect

    Jensen, R.V.; Oberman, C.R.

    1981-07-01

    A path integral method is developed for the calculation of the statistical properties of turbulent dynamical systems. The method is applicable to conservative systems which exhibit a transition to stochasticity as well as dissipative systems which exhibit strange attractors. A specific dissipative mapping is considered in detail which models the dynamics of a Brownian particle in a wave field with a broad frequency spectrum. Results are presented for the low order statistical moments for three turbulent regimes which exhibit strange attractors corresponding to strong, intermediate, and weak collisional damping.

  17. Effect of hyperons on phase coexistence in strange matter

    NASA Astrophysics Data System (ADS)

    Das, P.; Mallik, S.; Chaudhuri, G.

    2017-01-01

    The study of the liquid gas phase transition in the fragmentation of nuclei in heavy ion collisions has been extended to the strangeness sector using the statistical model for multifragmentation. Helmholtz's free energy, specific heat, and a few other thermodynamic observables have been analyzed in order to examine the occurrence of phase transition in the strange matter. The bimodal behavior of the largest cluster formed in fragmentation also strongly indicates a coexistence of both the phases. The presence of hyperons strengthens the signals and also shifts the transition temperature to lower values.

  18. A strange horn between Paolo Mantegazza and Charles Darwin.

    PubMed

    Garbarino, Carla; Mazzarello, Paolo

    2013-09-01

    During the preparation of an exhibition in Pavia dedicated to the centennial anniversary of the death of the Italian Pathologist Paolo Mantegazza, a strange cheratinic horn was found at the Museum for the History of the University of Pavia labelled as 'spur of a cock transplanted into an ear of a cow.' After some historical investigation, we found this strange object was at the centre of a scientific correspondence between Mantegazza and Charles Darwin, who made reference to it in his book The Variation of Animals and Plants under Domestication.

  19. Summary of recent experimental results on strangeness production

    NASA Astrophysics Data System (ADS)

    Kalweit, Alexander

    2017-01-01

    This article summarises the highlights of the recent experimental findings on strangeness production presented at the 16th edition of the International Conference on Strangeness in Quark Matter in Berkeley. Results obtained by eight large experimental collaborations (ALICE, ATLAS, CMS, HADES, LHCb, NA-61, PHENIX, STAR) spanning a large range in centre-of-mass energy and a variety of collision systems were presented at the conference. The article does not aim at being a complete review, but rather at connecting the experimental highlights of the different collaborations and at pointing towards questions which should be addressed by these experiments in future.

  20. Chiral extrapolations on the lattice with strange sea quarks

    NASA Astrophysics Data System (ADS)

    Descotes-Genon, Sébastien

    2005-06-01

    The (light but not-so-light) strange quark may play a special role in the low-energy dynamics of QCD. Strange sea-quark pairs may induce significant differences in the pattern of chiral symmetry breaking in the chiral limits of two and three massless flavours, in relation with the violation of the Zweig rule in the scalar sector. This effect could affect chiral extrapolations of unquenched lattice simulations with three dynamical flavours, and it could be detected through the quark-mass dependence of hadron observables [S. Descotes-Genon, hep-ph/0410233].

  1. Exploring remnants of invariants buried in a deep potential well in chemical reactions.

    PubMed

    Teramoto, Hiroshi; Komatsuzaki, Tamiki

    2008-09-07

    We revisit the concept of "remnant of invariant manifolds" originally discussed by Shirts and Reinhardt in a two degrees of freedom Henon-Heiles system [J. Chem. Phys. 77, 5204 (1982)]. This is regarded as the remnants of a destroyed invariant manifold that can dominate the transport in phase space even at high energy regions where most of all tori vanish. We present a novel technique to extract such remnants of invariants from a sea of chaos in highly nonlinear coupled molecular systems in terms of the canonical perturbation theory based on Lie transforms. As an illustrative example we demonstrate in HCN isomerization reaction that the conventional procedure based on a finite order truncation of the coordinate transformation prevent us from detecting remnants of invariants. However, our technique correctly captures the underlying remnants of invariants that shed light on the energetics of chemical reaction, that is, how the reactive mode acquires (releases) energy from (to) the other vibrational mode in order to overcome the potential barrier (to be trapped in the potential well). We also found the qualitative difference between the two potential wells, HCN and CNH, which coincides with the nearest neighbor level spacing distribution of the vibrational quantum states within the wells.

  2. Generalization of classical mechanics for nuclear motions on nonadiabatically coupled potential energy surfaces in chemical reactions.

    PubMed

    Takatsuka, Kazuo

    2007-10-18

    Classical trajectory study of nuclear motion on the Born-Oppenheimer potential energy surfaces is now one of the standard methods of chemical dynamics. In particular, this approach is inevitable in the studies of large molecular systems. However, as soon as more than a single potential energy surface is involved due to nonadiabatic coupling, such a naive application of classical mechanics loses its theoretical foundation. This is a classic and fundamental issue in the foundation of chemistry. To cope with this problem, we propose a generalization of classical mechanics that provides a path even in cases where multiple potential energy surfaces are involved in a single event and the Born-Oppenheimer approximation breaks down. This generalization is made by diagonalization of the matrix representation of nuclear forces in nonadiabatic dynamics, which is derived from a mixed quantum-classical representation of the electron-nucleus entangled Hamiltonian [Takatsuka, K. J. Chem. Phys. 2006, 124, 064111]. A manifestation of quantum fluctuation on a classical subsystem that directly contacts with a quantum subsystem is discussed. We also show that the Hamiltonian thus represented gives a theoretical foundation to examine the validity of the so-called semiclassical Ehrenfest theory (or mean-field theory) for electron quantum wavepacket dynamics, and indeed, it is pointed out that the electronic Hamiltonian to be used in this theory should be slightly modified.

  3. Computed Potential Energy Surfaces and Minimum Energy Pathways for Chemical Reactions

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

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

    SciTech Connect

    2004-08-01

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

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

    SciTech Connect

    Werpy, T.; Petersen, G.

    2004-08-01

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

  6. [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.

  7. Chemical attractants in horseshoe crab, Limulus polyphemus, eggs: the potential for an artificial bait.

    PubMed

    Ferrari, Kirstin M; Targett, Nancy M

    2003-02-01

    Horseshoe crabs, Limulus polyphemus, are the preferred bait in the eel and conch fisheries along the east coast of the United States. However, recent management measures have restricted the availability of horseshoe crabs to commercial fisheries, creating the need for sustainable, alternative bait sources. In this study, we examined the chemistry underlying the predator-prey attraction to determine if specific, isolable attractant metabolites from the horseshoe crab could be identified and characterized for incorporation into an artifical bait. Initial assays with the mud snail, Hyanassa obsoleta, suggested that the chemoattractants were concentrated in L. polyphemus eggs. Chemical analyses and biological assays of the egg extract indicated the primary cue was a heat-stable, proteinaceous compound (>10 kDa). A carbohydrate-rich fraction of low molecular mass (< 10 kDa) also enhanced mud snail chemotaxis. Analysis of egg digests with SDS-PAGE confirmed the presence of glycoproteins or carbohydrate-binding proteins in the horseshoe crab egg extract. Because the attractant appears to be a complex protein or glycoprotein, conventional chemical synthesis is unlikely. However, the tools of modem biotechnology offer the potential to produce this attractant in a system independent of the horseshoe crab. Such an attractant could be incorporated into an artificial bait, providing an ecologically sound alternative for commercial eel and whelk fisheries.

  8. Chemical composition of core samples from Newark Basin, a potential carbon sequestration site

    NASA Astrophysics Data System (ADS)

    Seltzer, A. M.; Yang, Q.; Goldberg, D.

    2012-12-01

    Injection of carbon dioxide into deep saline aquifers has been identified as a promising mitigation option of greenhouse gases, the successful management of which is considered to be one of the most urgent and important challenges. Given the high energy production in the New York metropolitan area, the Newark Basin region is considered to be a potential future sequestration site. However, the risk of an upward leak of sequestered CO2, especially to a shallow drinking water aquifer, is a key concern facing geological sequestration as a safe and viable mitigation option. In this study, we measured the chemical composition of 25 cores from various depths throughout Newark Basin as a precursor for an ex situ incubation experiment using these rock samples and aquifer water to simulate a leak event. Inductively coupled plasma mass spectrometry analysis of microwave-assisted digested rock powders and X-ray fluorescence analysis of the rock powders were conducted to obtain the concentrations of major and trace elements. Most of the major and trace elements show wide concentration ranges at one to two orders of magnitude. Understanding the chemical composition of these Newark Basin core samples is important not only for characterizing materials used for the later lab incubation, but also for gaining a broader understanding of the chemistry of the Newark Basin and profiling the region according to the varying risks associated with a leak of sequestered CO2 to a drinking water aquifer.

  9. 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.

  10. Critical temperature of chiral symmetry restoration for quark matter with a chiral chemical potential

    NASA Astrophysics Data System (ADS)

    Ruggieri, M.; Peng, G. X.

    2016-12-01

    In this article we study the restoration of chiral symmetry at a finite temperature for quark matter with a chiral chemical potential, {μ }5, by means of a nonlocal Nambu-Jona-Lasinio model. This model allows the introduction of, in the simplest way possible, a Euclidean momentum, p E , dependent quark mass function which decays (neglecting logarithms) as 1/{p}{E}2 for large p E , in agreement with the asymptotic behaviour expected in quantum chromodynamics in the presence of a nonperturbative quark condensate. We focus on the critical temperature for chiral symmetry restoration in the chiral limit, T c, versus {μ }5, as well as on the order of the phase transition. We find that T c increases with {μ }5, and that the transition remains of the second order for the whole range of {μ }5 considered.

  11. 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

  12. 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.

  13. Unfolding the Therapeutic Potential of Chemical Chaperones for Age-related Macular Degeneration

    PubMed Central

    Sauer, Theodor; Patel, Mrinali; Chan, Chi-Chao; Tuo, Jingsheng

    2008-01-01

    SUMMARY Recent studies suggest that pathological processes involved in age-related macular degeneration (AMD) might induce endoplasmic reticulum (ER) stress. Growing evidence demonstrates the ability of chemical chaperones to decrease ER stress and ameliorate ER stress-related disease phenotypes, suggesting that the field of chaperone therapy might hold novel treatments for AMD. In this review, we examine the evidence suggesting a role for ER stress in AMD. Furthermore, we discuss the use of chaperone therapy for the treatment of ER stress-associated diseases, including other neurodegenerative diseases and retinopathies. Finally, we examine strategies for identifying potential chaperone compounds and for experimentally demonstrating chaperone activity in in vitro and in vivo models of human disease. PMID:18528533

  14. 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.

  15. Relaxation of the Chiral Chemical Potential in the Dense Matter of a Neutron Star

    NASA Astrophysics Data System (ADS)

    Dvornikov, M. S.

    2017-03-01

    A model of the generation of a magnetic field in a neutron star is developed, based on an instability of the magnetic field caused by the electroweak interaction between electrons and nucleons in nuclear matter. The rate of change of the helicity of electrons as they scatter on protons in the dense matter of a neutron star is calculated with the help of methods of quantum field theory. The influence of the electroweak interaction between electrons and background nucleons on the process of change of the helicity is examined. A kinetic equation is derived for the evolution of the chiral chemical potential. The results obtained are used to describe the evolution of the magnetic field in magnetars.

  16. 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.

  17. 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.

  18. Changes in the Chemical Barrier Composition of Tears in Alzheimer's Disease Reveal Potential Tear Diagnostic Biomarkers.

    PubMed

    Kalló, Gergő; Emri, Miklós; Varga, Zsófia; Ujhelyi, Bernadett; Tőzsér, József; Csutak, Adrienne; Csősz, Éva

    2016-01-01

    Alzheimer's disease (AD) is one of the most common neurodegenerative diseases, with increasing prevalence affecting millions of people worldwide. Currently, only autopsy is able to confirm the diagnosis with a 100% certainty, therefore, biomarkers from body fluids obtained by non-invasive means provide an attractive alternative for the diagnosis of Alzheimer`s disease. Global changes of the protein profile were examined by quantitative proteomics; firstly, electrophoresis and LC-MS/MS were used, thereafter, SRM-based targeted proteomics method was developed and applied to examine quantitative changes of tear proteins. Alterations in the tear flow rate, total tear protein concentration and composition of the chemical barrier specific to AD were demonstrated, and the combination of lipocalin-1, dermcidin, lysozyme-C and lacritin was shown to be a potential biomarker, with an 81% sensitivity and 77% specificity.

  19. Time difference of arrival to blast localization of potential chemical/biological event on the move

    NASA Astrophysics Data System (ADS)

    Morcos, Amir; Desai, Sachi; Peltzer, Brian; Hohil, Myron E.

    2007-10-01

    Integrating a sensor suite with ability to discriminate potential Chemical/Biological (CB) events from high-explosive (HE) events employing a standalone acoustic sensor with a Time Difference of Arrival (TDOA) algorithm we developed a cueing mechanism for more power intensive and range limited sensing techniques. Enabling the event detection algorithm to locate to a blast event using TDOA we then provide further information of the event as either Launch/Impact and if CB/HE. The added information is provided to a range limited chemical sensing system that exploits spectroscopy to determine the contents of the chemical event. The main innovation within this sensor suite is the system will provide this information on the move while the chemical sensor will have adequate time to determine the contents of the event from a safe stand-off distance. The CB/HE discrimination algorithm exploits acoustic sensors to provide early detection and identification of CB attacks. Distinct characteristics arise within the different airburst signatures because HE warheads emphasize concussive and shrapnel effects, while CB warheads are designed to disperse their contents over large areas, therefore employing a slower burning, less intense explosive to mix and spread their contents. Differences characterized by variations in the corresponding peak pressure and rise time of the blast, differences in the ratio of positive pressure amplitude to the negative amplitude, and variations in the overall duration of the resulting waveform. The discrete wavelet transform (DWT) is used to extract the predominant components of these characteristics from air burst signatures at ranges exceeding 3km. Highly reliable discrimination is achieved with a feed-forward neural network classifier trained on a feature space derived from the distribution of wavelet coefficients and higher frequency details found within different levels of the multiresolution decomposition. The development of an adaptive noise

  20. 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.

  1. 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.

  2. Potential flux landscapes determine the global stability of a Lorenz chaotic attractor under intrinsic fluctuations

    NASA Astrophysics Data System (ADS)

    Li, Chunhe; Wang, Erkang; Wang, Jin

    2012-05-01

    We developed a potential flux landscape theory to investigate the dynamics and the global stability of a chemical Lorenz chaotic strange attractor under intrinsic fluctuations. Landscape was uncovered to have a butterfly shape. For chaotic systems, both landscape and probabilistic flux are crucial to the dynamics of chaotic oscillations. Landscape attracts the system down to the chaotic attractor, while flux drives the coherent motions along the chaotic attractors. Barrier heights from the landscape topography provide a quantitative measure for the robustness of chaotic attractor. We also found that the entropy production rate and phase coherence increase as the molecular numbers increase. Power spectrum analysis of autocorrelation function provides another way to quantify the global stability of chaotic attractor. We further found that limit cycle requires more flux and energy to sustain than the chaotic strange attractor. Finally, by detailed analysis we found that the curl probabilistic flux may provide the origin of the chaotic attractor.

  3. A DNA minor groove electronegative potential genome map based on photo-chemical probing.

    PubMed

    Lindemose, Søren; Nielsen, Peter Eigil; Hansen, Morten; Møllegaard, Niels Erik

    2011-08-01

    The double-stranded DNA of the genome contains both sequence information directly relating to the protein and RNA coding as well as functional and structural information relating to protein recognition. Only recently is the importance of DNA shape in this recognition process being fully appreciated, and it also appears that minor groove electronegative potential may contribute significantly in guiding proteins to their cognate binding sites in the genome. Based on the photo-chemical probing results, we have derived an algorithm that predicts the minor groove electronegative potential in a DNA helix of any given sequence. We have validated this model on a series of protein-DNA binding sites known to involve minor groove electrostatic recognition as well as on stable nucleosome core complexes. The algorithm allows for the first time a full minor groove electrostatic description at the nucleotide resolution of any genome, and it is illustrated how such detailed studies of this sequence dependent, inherent property of the DNA may reflect on genome organization, gene expression and chromosomal condensation.

  4. Multidirectional characterisation of chemical composition and health-promoting potential of Rosa rugosa hips.

    PubMed

    Olech, Marta; Nowak, Renata; Pecio, Łukasz; Łoś, Renata; Malm, Anna; Rzymowska, Jolanta; Oleszek, Wiesław

    2017-03-01

    Rugosa rose provides one of the largest hips frequently used in the preparation of pharmaceutical and food products. The aim of work was to conduct multidirectional study of biological activity and chemical composition of Rosa rugosa hips. Antiradical, cytotoxic (against cervical and breast cancer cell lines), antibacterial (against eight bacterial strains) and antifungal potential of the species in question was evaluated. Total contents of phenolics, phenolic acids, flavonoids, tannins, carotenoids and ascorbic acid were determined. LC-ESI-MS/MS analysis was performed in order to investigate closely phenolic acids and flavonoid glycosides. As a result, interesting selective cytotoxic effects on cervical (HeLa) and breast cancer (T47D) cell lines, significant antiradical activity (EC50 2.45 mg mg(-1) DPPH(•)) and moderate antimicrobial potential (MIC 0.625-1.25 mg mL(-1)) were observed. Nine phenolic acids and 11 flavonoid glycosides were qualitatively and quantitatively determined, including 7 compounds previously not reported in R. rugosa hips.

  5. 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

  6. Estimating the One-Electron Reduction Potential for Vanadium (V) by Chemical Techniques: An Experiment for General Chemistry.

    ERIC Educational Resources Information Center

    Wentworth, R. A. D.

    1985-01-01

    Describes an experiment which requires only qualitative observations, is suitable for general chemistry students, prompts an understanding of thermodynamic spontaneity, gives chemical meaning to electrode potentials, requires non-electrochemical equipment, and allows estimates of the standard potential for the reduction of Vanadium (V) to V (IV).…

  7. 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.

  8. Some measurements for determining strangeness matrix elements in the nucleon

    SciTech Connect

    Henley, E.M.; Pollock, S.J.; Ying, S.; Frederico, T.; Krein,; Williams, A.G.

    1991-12-31

    Some experiments to measure strangeness matrix elements of the proton are proposed. Two of these suggestions are described in some detail, namely electro-production of phi mesons and the difference between neutrino and antineutrino scattering for isospin zero targets such as deuterium.

  9. Some measurements for determining strangeness matrix elements in the nucleon

    SciTech Connect

    Henley, E.M.; Pollock, S.J.; Ying, S. ); Frederico, T. , Sao Jose dos Campos, SP . Inst. de Estudos Avancados); Krein, . Inst. de Fisica Teorica); Williams, A.G. )

    1991-01-01

    Some experiments to measure strangeness matrix elements of the proton are proposed. Two of these suggestions are described in some detail, namely electro-production of phi mesons and the difference between neutrino and antineutrino scattering for isospin zero targets such as deuterium.

  10. Probing the strange nature of the nucleon with phi photoproduction

    SciTech Connect

    Lowry, M.M.

    1997-03-06

    The presence inside the nucleon of a significant component of strange-antistrange quark pairs has been invoked to explain a number of current puzzles in the low energy realm of QCD. The {sigma} term in {pi}N scattering is a venerable conundrum which can be explained with a 10%--20% admixture. The spin crisis brought on by the EMC result and follow on experiments was first interpreted as requiring a large strange content of s quarks whose spin helped cancel the contribution of the u and d quarks to the nucleon spin, again of order 10%. Excess phi meson production in p{anti p} annihilation at LEAR has also been explained in terms of up to a 19% admixture of s{anti s} pairs. Charm production in deep-inelastic neutrino scattering would appear to provide evidence for a 3% strange sea. It is clear that a definite probe of the strange quark content would be an invaluable tool in unraveling a number of mysteries. The longitudinal beam target asymmetry in {psi} photoproduction is a particularly sensitive probe of that content. It is explored here.

  11. Measuring Infant-Mother Attachment: Is the Strange Situation Enough?

    ERIC Educational Resources Information Center

    Clarke-Stewart, K. Alison; Goossens, Frits A.; Allhusen, Virginia D.

    2001-01-01

    Examined validity of the California Attachment Procedure (CAP), which does not involve mother-child separations. Overall, toddlers were more likely to be classified as secure in the CAP than in the Strange Situation (SS) test. The CAP yielded higher rates of security, particularly for children in day care, and security in the CAP correlated more…

  12. Oral osteomyelitis: pre-AIDS manifestation or strange coincidence?

    PubMed

    Harel-Raviv, M; Gorsky, M; Lust, I; Raviv, E

    1996-01-01

    A bizarre and unexplained localized osteomyelitis was discovered in the mandible of an otherwise apparently healthy 36-year-old man. This strange oral manifestation was followed 2 years later by a diagnosis of Pneumocystis carinii pneumonia, which indicated full-blown AIDS. Could osteomyelitis of the mandible be an alarming oral manifestation of AIDS before the disease is manifested in other ways?

  13. Surface effects in color superconducting strange-quark matter

    SciTech Connect

    Oertel, Micaela; Urban, Michael

    2008-04-01

    Surface effects in strange-quark matter play an important role for certain observables which have been proposed in order to identify strange stars, and color superconductivity can strongly modify these effects. We study the surface of color superconducting strange-quark matter by solving the Hartree-Fock-Bogoliubov equations for finite systems ('strangelets') within the MIT bag model, supplemented with a pairing interaction. Because of the bag-model boundary condition, the strange-quark density is suppressed at the surface. This leads to a positive surface charge, concentrated in a layer of {approx}1 fm below the surface, even in the color-flavor locked (CFL) phase. However, since in the CFL phase all quarks are paired, this positive charge is compensated by a negative charge, which turns out to be situated in a layer of a few tens of fm below the surface, and the total charge of CFL strangelets is zero. We also study the surface and curvature contributions to the total energy. Because of the strong pairing, the energy as a function of the mass number is very well reproduced by a liquid-drop type formula with curvature term.

  14. Strangeness -2 and -3 Baryons in a Constituent Quark Model

    SciTech Connect

    Muslema Pervin; Winston Roberts

    2007-09-19

    We apply a quark model developed in earlier work to the spectrum of baryons with strangeness -2 and -3. The model describes a number of well-established baryons successfully, and application to cascade baryons allows the quantum numbers of some known states to be deduced.

  15. Strange vector form factors from parity-violating electron scattering

    SciTech Connect

    Kent Paschke, Anthony Thomas, Robert Michaels, David Armstrong

    2011-06-01

    The simplest models might describe the nucleon as 3 light quarks, but this description would be incomplete without inclusion of the sea of glue and qbar q pairs which binds it. Early indications of a particularly large contribution from strange quarks in this sea to the spin and mass of the nucleon motivated an experimental program examining the role of these strange quarks in the nucleon vector form factors. The strangeness form factors can be extracted from the well-studied electromagnetic structure of the nucleon using parity-violation in electron-nuclear scattering to isolate the effect of the weak interaction. With high luminosity and polarization, and a very stable beam due to its superconducting RF cavities, CEBAF at Jefferson Lab is a precision instrument uniquely well suited to the challenge of measurements of the small parity-violating asymmetries. The techniques and results of the two major Jefferson Lab experimental efforts in parity-violation studies, HAPPEX and G0, as well as efforts to describe the strange form factors in QCD, will be reviewed.

  16. Exploring Strange Nonchaotic Attractors through Jacobian Elliptic Functions

    ERIC Educational Resources Information Center

    Garcia-Hoz, A. Martinez; Chacon, R.

    2011-01-01

    We demonstrate the effectiveness of Jacobian elliptic functions (JEFs) for inquiring into the reshaping effect of quasiperiodic forces in nonlinear nonautonomous systems exhibiting strange nonchaotic attractors (SNAs). Specifically, we characterize analytically and numerically some reshaping-induced transitions starting from SNAs in the context of…

  17. Study of doubly strange systems using stored antiprotons

    NASA Astrophysics Data System (ADS)

    Singh, B.; Erni, W.; Krusche, B.; Steinacher, M.; Walford, N.; Liu, B.; Liu, H.; Liu, Z.; Shen, X.; Wang, C.; Zhao, J.; Albrecht, M.; Erlen, T.; Fink, M.; Heinsius, F.; Held, T.; Holtmann, T.; Jasper, S.; Keshk, I.; Koch, H.; Kopf, B.; Kuhlmann, M.; Kümmel, M.; Leiber, S.; Mikirtychyants, M.; Musiol, P.; Mustafa, A.; Pelizäus, M.; Pychy, J.; Richter, M.; Schnier, C.; Schröder, T.; Sowa, C.; Steinke, M.; Triffterer, T.; Wiedner, U.; Ball, M.; Beck, R.; Hammann, C.; Ketzer, B.; Kube, M.; Mahlberg, P.; Rossbach, M.; Schmidt, C.; Schmitz, R.; Thoma, U.; Urban, M.; Walther, D.; Wendel, C.; Wilson, A.; Bianconi, A.; Bragadireanu, M.; Caprini, M.; Pantea, D.; Patel, B.; Czyzycki, W.; Domagala, M.; Filo, G.; Jaworowski, J.; Krawczyk, M.; Lisowski, E.; Lisowski, F.; Michałek, M.; Poznański, P.; Płażek, J.; Korcyl, K.; Kozela, A.; Kulessa, P.; Lebiedowicz, P.; Pysz, K.; Schäfer, W.; Szczurek, A.; Fiutowski, T.; Idzik, M.; Mindur, B.; Przyborowski, D.; Swientek, K.; Biernat, J.; Kamys, B.; Kistryn, S.; Korcyl, G.; Krzemien, W.; Magiera, A.; Moskal, P.; Psyzniak, A.; Rudy, Z.; Salabura, P.; Smyrski, J.; Strzempek, P.; Wronska, A.; Augustin, I.; Böhm, R.; Lehmann, I.; Nicmorus Marinescu, D.; Schmitt, L.; Varentsov, V.; Al-Turany, M.; Belias, A.; Deppe, H.; Dzhygadlo, R.; Ehret, A.; Flemming, H.; Gerhardt, A.; Götzen, K.; Gromliuk, A.; Gruber, L.; Karabowicz, R.; Kliemt, R.; Krebs, M.; Kurilla, U.; Lehmann, D.; Löchner, S.; Lühning, J.; Lynen, U.; Orth, H.; Patsyuk, M.; Peters, K.; Saito, T.; Schepers, G.; Schmidt, C. J.; Schwarz, C.; Schwiening, J.; Täschner, A.; Traxler, M.; Ugur, C.; Voss, B.; Wieczorek, P.; Wilms, A.; Zühlsdorf, M.; Abazov, V. M.; Alexeev, G.; Arefiev, A.; Astakhov, V. I.; Barabanov, M. Yu.; Batyunya, B. V.; Davydov, Yu. I.; Dodokhov, V. Kh.; Efremov, A. A.; Fechtchenko, A.; Fedunov, A. G.; Galoyan, A.; Grigoryan, S.; Koshurnikov, E. K.; Lobanov, V. I.; Lobanov, Y. Yu.; Makarov, A. F.; Malinina, L. V.; Malyshev, V. L.; Olshevskiy, A.; Perevalova, E.; Piskun, A. A.; Pocheptsov, T.; Pontecorvo, G.; Rodionov, V.; Rogov, Y.; Salmin, R.; Samartsev, A.; Sapozhnikov, M. G.; Shabratova, G.; Skachkov, N. B.; Skachkova, A. N.; Strokovsky, E. A.; Suleimanov, M.; Teshev, R.; Tokmenin, V.; Uzhinsky, V.; Vodopyanov, A.; Zaporozhets, S. A.; Zhuravlev, N. I.; Zorin, A. G.; Branford, D.; Glazier, D.; Watts, D.; Böhm, M.; Britting, A.; Eyrich, W.; Lehmann, A.; Pfaffinger, M.; Uhlig, F.; Dobbs, S.; Seth, K.; Tomaradze, A.; Xiao, T.; Bettoni, D.; Carassiti, V.; Cotta Ramusino, A.; Dalpiaz, P.; Drago, A.; Fioravanti, E.; Garzia, I.; Savriè, M.; Akishina, V.; Kisel, I.; Kozlov, G.; Pugach, M.; Zyzak, M.; Gianotti, P.; Guaraldo, C.; Lucherini, V.; Bersani, A.; Bracco, G.; Macri, M.; Parodi, R. F.; Biguenko, K.; Brinkmann, K.; Di Pietro, V.; Diehl, S.; Dormenev, V.; Drexler, P.; Düren, M.; Etzelmüller, E.; Galuska, M.; Gutz, E.; Hahn, C.; Hayrapetyan, A.; Kesselkaul, M.; Kühn, W.; Kuske, T.; Lange, J. S.; Liang, Y.; Metag, V.; Nanova, M.; Nazarenko, S.; Novotny, R.; Quagli, T.; Reiter, S.; Rieke, J.; Rosenbaum, C.; Schmidt, M.; Schnell, R.; Stenzel, H.; Thöring, U.; Ullrich, M.; Wagner, M. N.; Wasem, T.; Wohlfarth, B.; Zaunick, H.; Ireland, D.; Rosner, G.; Seitz, B.; Deepak, P. N.; Kulkarni, A.; Apostolou, A.; Babai, M.; Kavatsyuk, M.; Lemmens, P.; Lindemulder, M.; Loehner, H.; Messchendorp, J.; Schakel, P.; Smit, H.; Tiemens, M.; van der Weele, J. C.; Veenstra, R.; Vejdani, S.; Dutta, K.; Kalita, K.; Kumar, A.; Roy, A.; Sohlbach, H.; Bai, M.; Bianchi, L.; Büscher, M.; Cao, L.; Cebulla, A.; Dosdall, R.; Gillitzer, A.; Goldenbaum, F.; Grunwald, D.; Herten, A.; Hu, Q.; Kemmerling, G.; Kleines, H.; Lehrach, A.; Nellen, R.; Ohm, H.; Orfanitski, S.; Prasuhn, D.; Prencipe, E.; Pütz, J.; Ritman, J.; Schadmand, S.; Sefzick, T.; Serdyuk, V.; Sterzenbach, G.; Stockmanns, T.; Wintz, P.; Wüstner, P.; Xu, H.; Zambanini, A.; Li, S.; Li, Z.; Sun, Z.; Xu, H.; Rigato, V.; Isaksson, L.; Achenbach, P.; Corell, O.; Denig, A.; Distler, M.; Hoek, M.; Karavdina, A.; Lauth, W.; Liu, Z.; Merkel, H.; Müller, U.; Pochodzalla, J.; Schlimme, S.; Sfienti, C.; Thiel, M.; Ahmadi, H.; Ahmed, S.; Bleser, S.; Capozza, L.; Cardinali, M.; Dbeyssi, A.; Deiseroth, M.; Feldbauer, F.; Fritsch, M.; Fröhlich, B.; Jasinski, P.; Kang, D.; Khaneft, D.; Klasen, R.; Leithoff, H. H.; Lin, D.; Maas, F.; Maldaner, S.; Martìnez Rojo, M.; Marta, M.; Michel, M.; Mora Espì, M. C.; Morales Morales, C.; Motzko, C.; Nerling, F.; Noll, O.; Pflüger, S.; Pitka, A.; Rodríguez Piñeiro, D.; Sanchez Lorente, A.; Steinen, M.; Valente, R.; Weber, T.; Zambrana, M.; Zimmermann, I.; Fedorov, A.; Korjik, M.; Missevitch, O.; Boukharov, A.; Malyshev, O.; Marishev, I.; Balanutsa, P.; Balanutsa, V.; Chernetsky, V.; Demekhin, A.; Dolgolenko, A.; Fedorets, P.; Gerasimov, A.; Goryachev, V.; Chandratre, V.; Datar, V.; Dutta, D.; Jha, V.; Kumawat, H.; Mohanty, A. K.; Parmar, A.; Roy, B.; Sonika, G.; Fritzsch, C.; Grieser, S.; Hergemöller, A. K.; Hetz, B.; Hüsken, N.; Khoukaz, A.; Wessels, J. P.; Khosonthongkee, K.; Kobdaj, C.; Limphirat, A.; Srisawad, P.; Yan, Y.; Barnyakov, M.; Barnyakov, A. Yu.; Beloborodov, K.; Blinov, A. E.; Blinov, V. E.; Bobrovnikov, V. S.; Kononov, S.; Kravchenko, E. A.; Kuyanov, I. A.; Martin, K.; Onuchin, A. P.; Serednyakov, S.; Sokolov, A.; Tikhonov, Y.; Atomssa, E.; Kunne, R.; Marchand, D.; Ramstein, B.; Van de Wiele, J.; Wang, Y.; Boca, G.; Costanza, S.; Genova, P.; Montagna, P.; Rotondi, A.; Abramov, V.; Belikov, N.; Bukreeva, S.; Davidenko, A.; Derevschikov, A.; Goncharenko, Y.; Grishin, V.; Kachanov, V.; Kormilitsin, V.; Levin, A.; Melnik, Y.; Minaev, N.; Mochalov, V.; Morozov, D.; Nogach, L.; Poslavskiy, S.; Ryazantsev, A.; Ryzhikov, S.; Semenov, P.; Shein, I.; Uzunian, A.; Vasiliev, A.; Yakutin, A.; Tomasi-Gustafsson, E.; Roy, U.; Yabsley, B.; Belostotski, S.; Gavrilov, G.; Izotov, A.; Manaenkov, S.; Miklukho, O.; Veretennikov, D.; Zhdanov, A.; Makonyi, K.; Preston, M.; Tegner, P.; Wölbing, D.; Bäck, T.; Cederwall, B.; Rai, A. K.; Godre, S.; Calvo, D.; Coli, S.; De Remigis, P.; Filippi, A.; Giraudo, G.; Lusso, S.; Mazza, G.; Mignone, M.; Rivetti, A.; Wheadon, R.; Balestra, F.; Iazzi, F.; Introzzi, R.; Lavagno, A.; Olave, J.; Amoroso, A.; Bussa, M. P.; Busso, L.; De Mori, F.; Destefanis, M.; Fava, L.; Ferrero, L.; Greco, M.; Hu, J.; Lavezzi, L.; Maggiora, M.; Maniscalco, G.; Marcello, S.; Sosio, S.; Spataro, S.; Birsa, R.; Bradamante, F.; Bressan, A.; Martin, A.; Calen, H.; Ikegami Andersson, W.; Johansson, T.; Kupsc, A.; Marciniewski, P.; Papenbrock, M.; Pettersson, J.; Schönning, K.; Wolke, M.; Galnander, B.; Diaz, J.; Pothodi Chackara, V.; Chlopik, A.; Kesik, G.; Melnychuk, D.; Slowinski, B.; Trzcinski, A.; Wojciechowski, M.; Wronka, S.; Zwieglinski, B.; Bühler, P.; Marton, J.; Steinschaden, D.; Suzuki, K.; Widmann, E.; Zmeskal, J.; Gerl, Jürgen; Kojouharov, Ivan; Kojouharova, Jasmina

    2016-10-01

    Bound nuclear systems with two units of strangeness are still poorly known despite their importance for many strong interaction phenomena. Stored antiprotons beams in the GeV range represent an unparalleled factory for various hyperon-antihyperon pairs. Their outstanding large production probability in antiproton collisions will open the floodgates for a series of new studies of systems which contain two or even more units of strangeness at the P ‾ ANDA experiment at FAIR. For the first time, high resolution γ-spectroscopy of doubly strange ΛΛ-hypernuclei will be performed, thus complementing measurements of ground state decays of ΛΛ-hypernuclei at J-PARC or possible decays of particle unstable hypernuclei in heavy ion reactions. High resolution spectroscopy of multistrange Ξ--atoms will be feasible and even the production of Ω--atoms will be within reach. The latter might open the door to the | S | = 3 world in strangeness nuclear physics, by the study of the hadronic Ω--nucleus interaction. For the first time it will be possible to study the behavior of Ξ‾+ in nuclear systems under well controlled conditions.

  18. Familiar-Strange: Teaching the Scripture as John Would Teach

    ERIC Educational Resources Information Center

    Ha, Tung-Chiew

    2014-01-01

    The Gospel of John teaches through telling the story of Jesus in light of the familiar Hebrew faith stories. It is an interpretive task that presents Jesus to his audience and teaches them adequate faith. John the Teacher skillfully uses narrative skills to create the familiar-strange effect in his storytelling. Each story is followed by a…

  19. Biodegradability and denitrification potential of settleable chemical oxygen demand in domestic wastewater.

    PubMed

    Tas, Didem Okutman; Karahan, Ozlem; Insel, Güçlü; Ovez, Süleyman; Orhon, Derin; Spanjers, Henri

    2009-07-01

    The effect of settling on mass balance and biodegradation characteristics of domestic wastewater and on denitrification potential was studied primarily using model calibration and evaluation of oxygen uptake rate profiles. Raw domestic wastewater was settled for a period of 30 minutes and a period of 2 hours to assess the effect of primary settling on wastewater characterization and composition. Mass balances in the system were made to evaluate the effect of primary settling on major parameters. Primary settling of the selected raw wastewater for 2 hours resulted in the removal of 32% chemical oxygen demand (COD), 9% total Kjeldahl nitrogen, 9% total phosphorus, and 47% total suspended solids. Respirometric analysis identified COD removed by settling as a new COD fraction, namely settleable slowly biodegradable COD (X(ss)), characterized by a hydrolysis rate of 1.0 day(-1) and a hydrolysis half-saturation coefficient of 0.08. A model simulation to test the fate and availability of suspended (X(s)) and settleable (X(ss)) COD fractions as carbon sources for denitrification showed that both particulate COD components were effectively removed aerobically at sludge ages higher than 1.5 to 2.0 days. Under anoxic conditions, the biodegradation of both COD fractions was reduced, especially below an anoxic sludge retention time of 3.0 days. Consequently, modeling results revealed that the settleable COD removed by primary settling could represent up to approximately 40% of the total denitrification potential of the system, depending on the specific configuration selected for the nitrogen removal process. This way, the results showed the significant effect of primary settling on denitrification, indicating that the settleable COD fraction could contribute an additional carbon source in systems where the denitrification potential associated with the influent becomes rate-limiting for the denitrification efficiency.

  20. Chemical Analysis of Extracts from Newfoundland Berries and Potential Neuroprotective Effects

    PubMed Central

    Hossain, Mohammad Z.; Shea, Emily; Daneshtalab, Mohsen; Weber, John T.

    2016-01-01

    Various species of berries have been reported to contain several polyphenolic compounds, such as anthocyanins and flavonols, which are known to possess high antioxidant activity and may be beneficial for human health. To our knowledge, a thorough chemical analysis of polyphenolics in species of these plants native to Newfoundland, Canada has not been conducted. The primary objective of this study was to determine the polyphenolic compounds present in commercial extracts from Newfoundland berries, which included blueberries (V. angustifolium), lingonberries (V. vitis-idaea) and black currant (Ribes lacustre). Anthocyanin and flavonol glycosides in powdered extracts from Ribes lacustre and the Vaccinium species were identified using the high performance liquid chromatographic (HPLC) separation method with mass spectrometric (MS) detection. The identified compounds were extracted from dried berries by various solvents via ultrasonication followed by centrifugation. A reverse-phase analytical column was employed to identify the retention time of each chemical component before submission for LC–MS analysis. A total of 21 phenolic compounds were tentatively identified in the three species. Further, we tested the effects of the lingonberry extract for its ability to protect neurons and glia from trauma utilizing an in vitro model of cell injury. Surprisingly, these extracts provided complete protection from cell death in this model. These findings indicate the presence of a wide variety of anthocyanins and flavonols in berries that grow natively in Newfoundland. These powdered extracts maintain these compounds intact despite being processed from berry fruit, indicating their potential use as dietary supplements. In addition, these recent findings and previous data from our lab demonstrate the ability of compounds in berries to protect the nervous system from traumatic insults. PMID:27775557

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

    PubMed

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

    2017-01-01

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

  2. 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.

  3. Localization and visualization of excess chemical potential in statistical mechanical integral equation theory 3D-HNC-RISM.

    PubMed

    Du, Qi-Shi; Liu, Peng-Jun; Huang, Ri-Bo

    2008-02-01

    In this study the excess chemical potential of the integral equation theory, 3D-RISM-HNC [Q. Du, Q. Wei, J. Phys. Chem. B 107 (2003) 13463-13470], is visualized in three-dimensional form and localized at interaction sites of solute molecule. Taking the advantage of reference interaction site model (RISM), the calculation equations of chemical excess potential are reformulized according to the solute interaction sites s in molecular space. Consequently the solvation free energy is localized at every interaction site of solute molecule. For visualization of the 3D-RISM-HNC calculation results, the excess chemical potentials are described using radial and three-dimensional diagrams. It is found that the radial diagrams of the excess chemical potentials are more sensitive to the bridge functions than the radial diagrams of solvent site density distributions. The diagrams of average excess chemical potential provide useful information of solute-solvent electrostatic and van der Waals interactions. The local description of solvation free energy at active sites of solute in 3D-RISM-HNC may broaden the application scope of statistical mechanical integral equation theory in solution chemistry and life science.

  4. Relating the strangeness content of the nucleon with the mass shift of the ϕ meson in nuclear matter

    SciTech Connect

    Gubler, Philipp; Ohtani, Keisuke

    2016-01-22

    The behavior of the ϕ meson at finite density is studied, making use of a QCD sum rule approach in combination with the maximum entropy method. It is demonstrated that a possible mass shift of the ϕ in nuclear matter is strongly correlated to the strangeness content of the nucleon, which is proportional to the strange sigma term, σ{sub sN}. In contrast to earlier studies, our results show that, depending on the value of σ{sub sN}, the ϕ meson could receive both a positive or negative mass shift at nuclear matter density. We find that these results depend only weakly on potential modifications of the width of the ϕ meson peak and on assumptions made on the behavior of four-quark condensates at finite density.

  5. Adsorption and capillary condensation in porous media as a function of the chemical potential of water in carbon dioxide

    NASA Astrophysics Data System (ADS)

    Heath, Jason E.; Bryan, Charles R.; Matteo, Edward N.; Dewers, Thomas A.; Wang, Yifeng; Sallaberry, Cédric J.

    2014-03-01

    The chemical potential of water may play an important role in adsorption and capillary condensation of water under multiphase conditions at geologic CO2 storage sites. Injection of large volumes of anhydrous CO2 will result in changing values of the chemical potential of water in the supercritical CO2 phase. We hypothesize that the chemical potential will at first reflect the low concentration of dissolved water in the dry CO2. As formation water dissolves into and is transported by the CO2 phase, the chemical potential of water will increase. We present a pore-scale model of the CO2-water interface or menisci configuration based on the augmented Young-Laplace equation, which combines adsorption on flat surfaces and capillary condensation in wedge-shaped pores as a function of chemical potential of water. The results suggest that, at a given chemical potential for triangular and square pores, liquid water saturation will be less in the CO2-water system under potential CO2 sequestration conditions relative to the air-water vadose zone system. The difference derives from lower surface tension of the CO2-water system and thinner liquid water films, important at pore sizes <1 × 10-6 m, relative to the air-water system. Water movement due to capillary effects will likely be minimal in reservoir rocks, but still may be important in finer grained, clayey caprocks, where very small pores may retain water and draw water back into the system via adsorption and capillary condensation, if dry-out and then rewetting were to occur.

  6. Autotransplantation of a Strange Positioned Impacted Central Incisor in a surgically Prepared Socket: A Miracle Esthetic Concept

    PubMed Central

    Jaiswara, Chandresh; Dhiman, Neeraj

    2016-01-01

    Esthetics is a prime concern for a young lady. Any anomaly in the anterior tooth may create anxiety and depression. This anxiety and depression may hamper her married life and overall personality. This case report reveals an unerupted right central incisor situated in a strange position, creating space in the maxillary anterior region and giving an unesthetic appearance. Autotransplantation is a method of choice for a strangely positioned impacted central incisor in a new appropriate site. This method offers a new treatment option for some clinical situations if orthodontic approach is not possible. It permits tooth movement to a distant or the opposite side of the same dental arch as well as to the opposite jaw. This procedure also offers potential benefits of reestablishment of normal alveolar process development, esthetics, functions, and arch integrity. This procedure has the potential to become a viable alternative treatment plan for young patients of low socioeconomic status, allowing the reestablish-ment and restoration of a missing tooth and their functions. This article discusses methods of auto-reimplantation of a tooth in a fresh surgically prepared socket, its biological principle, and establishment of functions, esthetics, and phonetics. How to cite this article Jaiswara C, Srivastava VK, Dhiman N. Autotransplantation of a Strange Positioned Impacted Central Incisor in a surgically Prepared Socket: A Miracle Esthetic Concept. Int J Clin Pediatr Dent 2016;9(3):269-272. PMID:27843261

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Chemical potential of a test hard sphere of variable size in a hard-sphere fluid

    NASA Astrophysics Data System (ADS)

    Heyes, David M.; Santos, Andrés

    2016-12-01

    The Labík and Smith Monte Carlo simulation technique to implement the Widom particle insertion method is applied using Molecular Dynamics (MD) instead to calculate numerically the insertion probability, P0(η ,σ0) , of tracer hard-sphere (HS) particles of different diameters, σ0, in a host HS fluid of diameter σ and packing fraction, η , up to 0.5. It is shown analytically that the only polynomial representation of -ln ⁡P0 (η ,σ0) consistent with the limits σ0→0 and σ0→∞ has necessarily a cubic form, c0(η ) +c1(η ) σ0 /σ +c2(η ) (σ0/σ ) 2 +c3(η ) (σ0/σ ) 3 . Our MD data for -ln ⁡P0 (η ,σ0) are fitted to such a cubic polynomial and the functions c0(η ) and c1(η ) are found to be statistically indistinguishable from their exact solution forms. Similarly, c2(η ) and c3(η ) agree very well with the Boublík-Mansoori-Carnahan-Starling-Leland and Boublík-Carnahan-Starling-Kolafa formulas. The cubic polynomial is extrapolated (high density) or interpolated (low density) to obtain the chemical potential of the host fluid, or σ0→σ , as β μex =c0+c1+c2+c3 . Excellent agreement between the Carnahan-Starling and Carnahan-Starling-Kolafa theories with our MD data is evident.

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

    SciTech Connect

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

    2008-08-01

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

  16. 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

  17. 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).

  18. Transport coefficients of heavy quarks around Tc at finite quark chemical potential

    NASA Astrophysics Data System (ADS)

    Berrehrah, H.; Gossiaux, P. B.; Aichelin, J.; Cassing, W.; Torres-Rincon, J. M.; Bratkovskaya, E.

    2014-11-01

    The interactions of heavy quarks with the partonic environment at finite temperature T and finite quark chemical potential μq are investigated in terms of transport coefficients within the dynamical quasiparticle model (DQPM) designed to reproduce the lattice-QCD (lQCD) results (including the partonic equation of state) in thermodynamic equilibrium. These results are confronted with those of nuclear many-body calculations close to the critical temperature Tc. The hadronic and partonic spatial diffusion coefficients join smoothly and show a pronounced minimum around Tc at μq=0 as well as at finite μq. Close to and above Tc its absolute value matches the lQCD calculations for μq=0 . The smooth transition of the heavy-quark transport coefficients from the hadronic to the partonic medium corresponds to a crossover in line with lattice calculations, and differs substantially from perturbative-QCD calculations which show a large discontinuity at Tc. This indicates that in the vicinity of Tc dynamically dressed massive partons should be the effective degrees of freedom in the quark-gluon plasma.

  19. Chemical speciation and potential mobility of heavy metals in the soil of former tin mining catchment.

    PubMed

    Ashraf, M A; Maah, M J; Yusoff, I

    2012-01-01

    This study describes the chemical speciation of Pb, Zn, Cu, Cr, As, and Sn in soil of former tin mining catchment. Total five sites were selected for sampling and subsequent subsamples were collected from each site in order to create a composite sample for analysis. Samples were analysed by the sequential extraction procedure using optical emission spectrometry (ICP OES). Small amounts of Cu, Cr, and As retrieved from the exchangeable phase, the ready available for biogeochemical cycles in the ecosystem. Low quantities of Cu and As could be taken up by plants in these kind of acidic soils. Zn not detected in the bioavailable forms while Pb is only present in negligible amounts in very few samples. The absence of mobile forms of Pb eliminates the toxic risk both in the trophic chain and its migration downwards the soil profile. The results also indicate that most of the metals have high abundance in residual fraction indicating lithogenic origin and low bioavailability of the metals in the studied soil. The average potential mobility for the metals giving the following order: Sn > Cu > Zn > Pb > Cr > As.

  20. Chemical reactivity trends of ergotamine and butenolide from electrostatic potentials and charge sensitivities

    SciTech Connect

    Mrozek, J.; Michalak, A.

    1995-12-05

    A set of reactivity indices, including maps of the electrostatic potential and local and condensed Fukui function (FF) indices in the atomic resolution, are reported for two vasoconstricting mycotoxins: butenolide and ergotamine; both the finite difference approach of Parr and Yan as well as charge sensitivity analysis, determining the charge responses via the inversion of the hardness tensor, have been used to generate the FF data. These two routes of arriving at the atomic FF indices provide an opportunity to evaluate the available parametrizations of the semiempirical NDDO-type of methods which have been used to determine the input charge distribution; namely, the best parametrization should generate consistent FF predictions resulting from both approaches. For butenolide, the MNDO parametrization was found to fulfill this consistency requirement. The chemical reactivity information has been used to trace possible similarities in reactivity trends of the butenolide molecule and the related fragment of ergotamine, toward hypothetical nucleophilic, electrophilic, and radical attacks. These predictions have been compared to experimental data available for other unsaturated lactones. 13 refs., 18 figs., 1 tab.

  1. Lepidopteran defence droplets - a composite physical and chemical weapon against potential predators.

    PubMed

    Pentzold, Stefan; Zagrobelny, Mika; Khakimov, Bekzod; Engelsen, Søren Balling; Clausen, Henrik; Petersen, Bent Larsen; Borch, Jonas; Møller, Birger Lindberg; Bak, Søren

    2016-03-04

    Insects often release noxious substances for their defence. Larvae of Zygaena filipendulae (Lepidoptera) secrete viscous and cyanogenic glucoside-containing droplets, whose effectiveness was associated with their physical and chemical properties. The droplets glued mandibles and legs of potential predators together and immobilised them. Droplets were characterised by a matrix of an aqueous solution of glycine-rich peptides (H-WG11-NH2) with significant amounts of proteins and glucose. Among the proteins, defensive proteins such as protease inhibitors, proteases and oxidases were abundant. The neurotoxin β-cyanoalanine was also found in the droplets. Despite the presence of cyanogenic glucosides, which release toxic hydrogen cyanide after hydrolysis by a specific β-glucosidase, the only β-glucosidase identified in the droplets (ZfBGD1) was inactive against cyanogenic glucosides. Accordingly, droplets did not release hydrogen cyanide, unless they were mixed with specific β-glucosidases present in the Zygaena haemolymph. Droplets secreted onto the cuticle hardened and formed sharp crystalline-like precipitates that may act as mandible abrasives to chewing predators. Hardening followed water evaporation and formation of antiparallel β-sheets of the peptide oligomers. Consequently, after mild irritation, Zygaena larvae deter predators by viscous and hardening droplets that contain defence proteins and β-cyanoalanine. After severe injury, droplets may mix with exuding haemolymph to release hydrogen cyanide.

  2. 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

  3. 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.

  4. The pDynamo Program for Molecular Simulations using Hybrid Quantum Chemical and Molecular Mechanical Potentials.

    PubMed

    Field, Martin J

    2008-07-01

    The pDynamo program has been developed for the simulation of molecular systems using hybrid quantum chemical (QC) and molecular mechanical (MM) potentials. pDynamo is written in a mixture of the computer languages Python and C and is a successor to the previous version of Dynamo, now denoted fDynamo, that was written in Fortran 90 (J. Comput. Chem. 2000, 21, 1088). The current version of Dynamo has a similar range of functionality to the older one but extends it in some significant ways, including the addition of a density functional theory QC capability. This paper gives a general description of pDynamo and outlines some of the advantages and disadvantages that have been encountered in switching computer languages. Some technical aspects of the implementation of pDynamo's algorithms are also discussed and illustrated with the results of example calculations. pDynamo is available on the Web at the address http://www.pdynamo.org and is released under the CeCILL license which is equivalent to the GNU general public license but conforms to the principles of French law.

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

    PubMed

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

    2016-03-25

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

  7. 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

  8. Individual complex Dirac eigenvalue distributions from random matrix theory and comparison to quenched lattice QCD with a quark chemical potential.

    PubMed

    Akemann, G; Bloch, J; Shifrin, L; Wettig, T

    2008-01-25

    We analyze how individual eigenvalues of the QCD Dirac operator at nonzero quark chemical potential are distributed in the complex plane. Exact and approximate analytical results for both quenched and unquenched distributions are derived from non-Hermitian random matrix theory. When comparing these to quenched lattice QCD spectra close to the origin, excellent agreement is found for zero and nonzero topology at several values of the quark chemical potential. Our analytical results are also applicable to other physical systems in the same symmetry class.

  9. 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.

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

    PubMed

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

    2010-07-01

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

  11. Deciphering potential chemical compounds of gaseous oxidized mercury in Florida, USA

    NASA Astrophysics Data System (ADS)

    Huang, Jiaoyan; Miller, Matthieu B.; Edgerton, Eric; Sexauer Gustin, Mae

    2017-02-01

    The highest mercury (Hg) wet deposition in the United States of America (USA) occurs along the Gulf of Mexico, and in the southern and central Mississippi River Valley. Gaseous oxidized Hg (GOM) is thought to be a major contributor due to high water solubility and reactivity. Therefore, it is critical to understand concentrations, potential for wet and dry deposition, and GOM compounds present in the air. Concentrations and dry-deposition fluxes of GOM were measured and calculated for Naval Air Station Pensacola Outlying Landing Field (OLF) in Florida using data collected by a Tekran® 2537/1130/1135, the University of Nevada Reno Reactive Mercury Active System (UNRRMAS) with cation exchange and nylon membranes, and the Aerohead samplers that use cation-exchange membranes to determine dry deposition. Relationships with Tekran®-derived data must be interpreted with caution, since the GOM concentrations measured are biased low depending on the chemical compounds in air and interferences with water vapor and ozone.Criteria air pollutants were concurrently measured. This allowed for comparison and better understanding of GOM.In addition to other methods previously applied at OLF, use of the UNRRMAS provided a platform for determination of the chemical compounds of GOM in the air. Results from nylon membranes with thermal desorption analyses indicated seven GOM compounds in this area, including HgBr2, HgCl2, HgO, Hg-nitrogen and sulfur compounds, and two unknown compounds. This indicates that the site is influenced by different gaseous phase reactions and sources. Using back-trajectory analysis during a high-GOM event related to high CO, but average SO2, indicated air parcels moved from the free troposphere and across Arkansas, Mississippi, and Alabama at low elevation (< 300 m). This event was initially characterized by HgBr2, followed by a mixture of GOM compounds. Overall, GOM chemistry indicates oxidation reactions with local mobile source pollutants and long

  12. Framework for identifying chemicals with structural features associated with the potential to act as developmental or reproductive toxicants.

    PubMed

    Wu, Shengde; Fisher, Joan; Naciff, Jorge; Laufersweiler, Michael; Lester, Cathy; Daston, George; Blackburn, Karen

    2013-12-16

    Developmental and reproductive toxicity (DART) end points are important hazard end points that need to be addressed in the risk assessment of chemicals to determine whether or not they are the critical effects in the overall risk assessment. These hazard end points are difficult to predict using current in silico tools because of the diversity of mechanisms of action that elicit DART effects and the potential for narrow windows of vulnerability. DART end points have been projected to consume the majority of animals used for compliance with REACH; thus, additional nonanimal predictive tools are urgently needed. This article presents an empirically based decision tree for determining whether or not a chemical has receptor-binding properties and structural features that are consistent with chemical structures known to have toxicity for DART end points. The decision tree is based on a detailed review of 716 chemicals (664 positive, 16 negative, and 36 with insufficient data) that have DART end-point data and are grouped into defined receptor binding and chemical domains. When tested against a group of chemicals not included in the training set, the decision tree is shown to identify a high percentage of chemicals with known DART effects. It is proposed that this decision tree could be used both as a component of a screening system to identify chemicals of potential concern and as a component of weight-of-evidence decisions based on structure-activity relationships (SAR) to fill data gaps without generating additional test data. In addition, the chemical groupings generated could be used as a starting point for the development of hypotheses for in vitro testing to elucidate mode of action and ultimately in the development of refined SAR principles for DART that incorporate mode of action (adverse outcome pathways).

  13. Surveillance of potentially hazardous chemicals in food in the United Kingdom.

    PubMed

    Knowles, M E; Bell, J R; Norman, J A; Watson, D H

    1991-01-01

    Surveillance of chemical contaminants in food plays an important role in helping to ensure a safe food supply in those countries that undertake it. This paper reviews the methods used in the UK as a means of highlighting the essential elements required by any food chemical surveillance programme. The following topics have been covered: quantifying food consumption, setting priorities in food surveillance, developing a common approach to the surveillance of different chemicals in the food supply (including the use of Total and Duplicate Diet Studies), estimating human intakes of chemicals from the diet, developing suitably sensitive and reliable methods of analysis, obtaining representative samples, and assessing and managing risk.

  14. 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.

  15. 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,…

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. Chemical potentials and phase equilibria of Lennard-Jones mixtures: a self-consistent integral equation approach.

    PubMed

    Wilson, D Scott; Lee, Lloyd L

    2005-07-22

    We explore the vapor-liquid phase behavior of binary mixtures of Lennard-Jones-type molecules where one component is supercritical, given the system temperature. We apply the self-consistency approach to the Ornstein-Zernike integral equations to obtain the correlation functions. The consistency checks include not only thermodynamic consistencies (pressure consistency and Gibbs-Duhem consistency), but also pointwise consistencies, such as the zero-separation theorems on the cavity functions. The consistencies are enforced via the bridge functions in the closure which contain adjustable parameters. The full solution requires the values of not only the monomer chemical potentials, but also the dimer chemical potentials present in the zero-separation theorems. These are evaluated by the direct chemical-potential formula [L. L. Lee, J. Chem. Phys. 97, 8606 (1992)] that does not require temperature nor density integration. In order to assess the integral equation accuracy, molecular-dynamics simulations are carried out alongside the states studied. The integral equation results compare well with simulation data. In phase calculations, it is important to have pressure consistency and valid chemical potentials, since the matching of phase boundaries requires the equality of the pressures and chemical potentials of both the liquid and vapor phases. The mixtures studied are methane-type and pentane-type molecules, both characterized by effective Lennard-Jones potentials. Calculations on one isotherm show that the integral equation approach yields valid answers as compared with the experimental data of Sage and Lacey. To study vapor-liquid phase behavior, it is necessary to use consistent theories; any inconsistencies, especially in pressure, will vitiate the phase boundary calculations.

  1. Non-Chemical Distant Cellular Interactions as a potential confounder of cell biology experiments

    PubMed Central

    Farhadi, Ashkan

    2014-01-01

    Distant cells can communicate with each other through a variety of methods. Two such methods involve electrical and/or chemical mechanisms. Non-chemical, distant cellular interactions may be another method of communication that cells can use to modify the behavior of other cells that are mechanically separated. Moreover, non-chemical, distant cellular interactions may explain some cases of confounding effects in Cell Biology experiments. In this article, we review non-chemical, distant cellular interactions studies to try to shed light on the mechanisms in this highly unconventional field of cell biology. Despite the existence of several theories that try to explain the mechanism of non-chemical, distant cellular interactions, this phenomenon is still speculative. Among candidate mechanisms, electromagnetic waves appear to have the most experimental support. In this brief article, we try to answer a few key questions that may further clarify this mechanism. PMID:25368582

  2. Multi-strangeness production in hadron induced reactions

    NASA Astrophysics Data System (ADS)

    Gaitanos, T.; Moustakidis, Ch.; Lalazissis, G. A.; Lenske, H.

    2016-10-01

    We discuss in detail the formation and propagation of multi-strangeness particles in reactions induced by hadron beams relevant for the forthcoming experiments at FAIR. We focus the discussion on the production of the decuplet-particle Ω and study for the first time the production and propagation mechanism of this heavy hyperon inside hadronic environments. The transport calculations show the possibility of Ω-production in the forthcoming P ‾ANDA-experiment, which can be achieved with measurable probabilities using high-energy secondary Ξ-beams. We predict cross sections for Ω-production. The theoretical results are important in understanding the hyperon-nucleon and, in particular, the hyperon-hyperon interactions also in the high-strangeness sector. We emphasize the importance of our studies for the research plans at FAIR.

  3. Parity Violating Electron Scattering and Strangeness in the Nucleon

    SciTech Connect

    Maas, Frank E.

    2008-10-13

    A measurement of the weak form factor of the proton allows a flavor separation of the strangeness contribution to the electromagnetic form factors. The weak form factor is accessed experimentally by the measurement of a parity violating (PV) asymmetry in the scattering of polarized electrons on unpolarized protons. An extended experimental program to measure these parity violating asymmetries has been performed and is going on at different accelerators. After the first round of experiments allowing a separation of the strangeness form factors G{sub E}{sup s} and G{sub M}{sup s} at a Q{sup 2}-value of 0.1 (GeV/c){sup 2}, new, preliminary results have been achieved at 0.23 (GeV/c){sup 2}.

  4. Strange quintessence star in Krori-Barua spacetime

    NASA Astrophysics Data System (ADS)

    Bhar, Piyali

    2015-04-01

    In the present paper a new model of a compact star is obtained by utilizing the Krori-Barua (KB) ansatz [Krori and Barua in J. Phys. A, Math. Gen. 8:508, 1975] in the presence of a quintessence field characterized by a parameter ω q with . The obtained model of strange stars is singularity free and satisfies all the physical requirements. Our model is stable as well as it is in static equilibrium. The numerical values of the mass of the strange stars 4U1820-30 (radius=10 km), SAX J1808.4-3658(SS1) (radius=7.07 km) and Her X-1 (radius=7.7 km) calculated from our model are very close to the standard data. The interior solution is matched to the exterior Schwarzschild spacetime in the presence of a thin shell where a negative surface pressure is needed to keep the thin shell from collapsing.

  5. Strange attractors in weakly turbulent Couette-Taylor flow

    NASA Technical Reports Server (NTRS)

    Brandstater, A.; Swinney, Harry L.

    1987-01-01

    An experiment is conducted on the transition from quasi-periodic to weakly turbulent flow of a fluid contained between concentric cylinders with the inner cylinder rotating and the outer cylinder at rest. Power spectra, phase-space portraits, and circle maps obtained from velocity time-series data indicate that the nonperiodic behavior observed is deterministic, that is, it is described by strange attractors. Various problems that arise in computing the dimension of strange attractors constructed from experimental data are discussed and it is shown that these problems impose severe requirements on the quantity and accuracy of data necessary for determining dimensions greater than about 5. In the present experiment the attractor dimension increases from 2 at the onset of turbulence to about 4 at a Reynolds number 50-percent above the onset of turbulence.

  6. 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.

  7. 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.

  8. 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…

  9. 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,...

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

    PubMed

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

    2015-05-04

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

  11. 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...

  12. Finite size effects in the presence of a chemical potential: A study in the classical nonlinear O(2) sigma model

    NASA Astrophysics Data System (ADS)

    Banerjee, Debasish; Chandrasekharan, Shailesh

    2010-06-01

    In the presence of a chemical potential, the physics of level crossings leads to singularities at zero temperature, even when the spatial volume is finite. These singularities are smoothed out at a finite temperature but leave behind nontrivial finite size effects which must be understood in order to extract thermodynamic quantities using Monte Carlo methods, particularly close to critical points. We illustrate some of these issues using the classical nonlinear O(2) sigma model with a coupling β and chemical potential μ on a 2+1-dimensional Euclidean lattice. In the conventional formulation this model suffers from a sign problem at nonzero chemical potential and hence cannot be studied with the Wolff cluster algorithm. However, when formulated in terms of the worldline of particles, the sign problem is absent, and the model can be studied efficiently with the “worm algorithm.” Using this method we study the finite size effects that arise due to the chemical potential and develop an effective quantum mechanical approach to capture the effects. As a side result we obtain energy levels of up to four particles as a function of the box size and uncover a part of the phase diagram in the (β,μ) plane.

  13. Bulk viscosity of strange quark matter: Urca versus nonleptonic processes

    SciTech Connect

    Sa'd, Basil A.; Shovkovy, Igor A.; Rischke, Dirk H.

    2007-06-15

    A general formalism for calculating the bulk viscosity of strange quark matter is developed. Contrary to the common belief that the nonleptonic processes alone give the dominant contribution to the bulk viscosity, the inclusion of the Urca processes is shown to play an important role at intermediate densities when the characteristic r-mode oscillation frequencies are not too high. The interplay of nonleptonic and Urca processes is analyzed in detail.

  14. Strange hadron production at SIS energies: an update from HADES

    NASA Astrophysics Data System (ADS)

    Lorenz, M.; Adamczewski-Musch, J.; Arnold, O.; Atomssa, E. T.; Behnke, C.; Berger-Chen, J. C.; Biernat, J.; Blanco, A.; Blume, C.; Böhmer, M.; Bordalo, P.; Chernenko, S.; Deveaux, C.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Fonte, P.; Franco, C.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzón, J. A.; Gill, K.; Golubeva, M.; Guber, F.; Gumberidze, M.; Harabasz, S.; Hennino, T.; Hlavac, S.; Höhne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Jurkovic, M.; Kämpfer, B.; Karavicheva, T.; Kardan, B.; Koenig, I.; Koenig, W.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kotte, R.; Krása, A.; Krebs, E.; Kuc, G.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Lopes, L.; Mahmoud, T.; Maier, L.; Mangiarotti, A.; Markert, J.; Metag, V.; Michel, J.; Müntz, C.; Münzer, R.; Naumann, L.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Petousis, V.; Pietraszko, J.; Przygoda, W.; Ramstein, B.; Rehnisch, L.; Reshetin, A.; Rost, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schmidt-Sommerfeld, K.; Schuldes, H.; Sellheim, P.; Siebenson, J.; Silva, L.; Sobolev, Yu. G.; Spataro, S.; Ströbele, H.; Stroth, J.; Strzempek, P.; Sturm, C.; Svoboda, O.; Tarantola, A.; Teilab, K.; Tlusty, P.; Traxler, M.; Tsertos, H.; Vasiliev, T.; Wagner, V.; Wendisch, C.; Wirth, J.; Wüstenfeld, J.; Zanevsky, Y.; Zumbruch, P.

    2016-01-01

    We present and discuss recent experimental activities of the HADES collaboration on open and hidden strangeness production close or below the elementary NN threshold. Special emphasis is put on the feed-down from ϕ mesons to antikaons, the presence of the Ξ- excess in cold nuclear matter and the comparison of statistical model rates to elementary p+p data. The implications for the interpretation of heavy-ion data are discussed as well.

  15. A useful approximate isospin equality for charmless strange B decays.

    SciTech Connect

    Lipkin, H. J.; High Energy Physics; Weizmann Inst. of Science; Aviv Univ.

    1999-01-01

    A useful inequality is obtained if charmless strange B decays are assumed to be dominated by a {Delta}l=0 transition like that from the gluonic penguin diagram and the contributions of all other diagrams including the tree, electroweak penguin and annihilation diagrams are small but not negligible. The interference contributions which are linear in these other amplitudes are included but the direct contributions which are quadratic are neglected.

  16. 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.

  17. Quark-hadron phase transition and strangeness conservation constraints

    NASA Astrophysics Data System (ADS)

    Saeed-Uddin

    1999-01-01

    The implications of the strangeness conservation in a hadronic resonance gas (HRG) on the expected phase transition to the quark gluon plasma (QGP) are investigated. It is assumed that under favourable conditions a first order hadron-quark matter phase transition may occur in the hot hadronic matter such as those produced in the ultra-relativistic heavy-ion collisions at CERN and BNL. It is however shown that the criteria of strict strangeness conservation in the HRG may not permit the occurrence of a strict first order equilibrium quark-hadron phase transition unlike a previous study. This emerges as a consequence of the application of a realistic equation of state (EOS) for the HRG and QGP phases, which account for the finite-size effect arising from the short range hard-core hadronic repulsion in the HRG phase and the perturbative QCD interactions in the QGP phase. For a first order hadron-quark matter phase transition to occur one will therefore require large fluctuations in the critical thermal parameters, which might arise due to superheating, supercooling or other nonequlibrium effects. We also discuss a scenario proposed earlier, leading to a possible strangeness separation process during hadronization.

  18. Metal-Organic Frameworks as Potential Platforms for Carbon Dioxide Capture and Chemical Transformation

    NASA Astrophysics Data System (ADS)

    Gao, Wenyang

    The anthropogenic carbon dioxide (CO2) emission into the atmosphere, mainly through the combustion of fossil fuels, has resulted in a balance disturbance of the carbon cycle. Overwhelming scientific evidence proves that the escalating level of atmospheric CO2 is deemed as the main culprit for global warming and climate change. It is thus imperative to develop viable CO2 capture and sequestration (CCS) technologies to reduce CO2 emissions, which is also essential to avoid the potential devastating effects in future. The drawbacks of energy-cost, corrosion and inefficiency for amine-based wet-scrubbing systems which are currently used in industry, have prompted the exploration of alternative approaches for CCS. Extensive efforts have been dedicated to the development of functional porous materials, such as activated carbons, zeolites, porous organic polymers, and metal-organic frameworks (MOFs) to capture CO2. However, these adsorbents are limited by either poor selectivity for CO2 separation from gas mixtures or low CO2 adsorption capacity. Therefore, it is still highly demanding to design next-generation adsorbent materials fulfilling the requirements of high CO2 selectivity and enough CO2 capacity, as well as high water/moisture stability under practical conditions. Metal-organic frameworks (MOFs) have been positioned at the forefront of this area as a promising type of candidate amongst various porous materials. This is triggered by the modularity and functionality of pore size, pore walls and inner surface of MOFs by use of crystal engineering approaches. In this work, several effective strategies, such as incorporating 1,2,3-triazole groups as moderate Lewis base centers into MOFs and employing flexible azamacrocycle-based ligands to build MOFs, demonstrate to be promising ways to enhance CO 2 uptake capacity and CO2 separation ability of porous MOFs. It is revealed through in-depth studies on counter-intuitive experimental observations that the local electric

  19. Effects of non-Newtonian gravity on the properties of strange stars

    NASA Astrophysics Data System (ADS)

    Lu, Zhen-Yan; Peng, Guang-Xiong; Zhou, Kai

    2017-02-01

    The properties of strange star matter are studied in the equivparticle model with inclusion of non-Newtonian gravity. It is found that the inclusion of non-Newtonian gravity makes the equation of state stiffer if Witten’s conjecture is true. Correspondingly, the maximum mass of strange stars becomes as large as two times the solar mass, and the maximum radius also becomes bigger. The coupling to boson mass ratio has been constrained within the stability range of strange quark matter.

  20. Does chemical aposematic (warning) signaling occur between host plants and their potential parasitic plants?

    PubMed

    Lev-Yadun, Simcha

    2013-07-01

    Aposematism (warning) signaling is a common defensive mechanism toward predatory or herbivorous animals, i.e., interactions between different trophic levels. I propose that it should be considered at least as a working hypothesis that chemical aposematism operates between certain host plants and their plant predators, parasitic plants, and that although they are also plants, they belong to a higher trophic level. Specific host plant genotypes emit known repelling chemical signals toward parasitic plants, which reduce the level of, slow the directional parasite growth (attack) toward the signaling hosts, or even cause parasitic plants to grow away from them in response to these chemicals. Chemical host aposematism toward parasitic plants may be a common but overlooked defense from parasitic plants.

  1. 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)

  2. The strange gases of Jupiter and Saturn

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.

    1990-12-01

    The various gases found in the atmospheres of Jupiter and Saturn are discussed. A history of scientific investigation of these planets is outlined and results of these discoveries are considered. The molecular species found in these two planets are classified into several groups. The first group consists of H2, He, CH4, NH3, and H2O while the second group contains gases formed as the chemical byproducts of solar radiation, including simple hydrocarbons such as C2H2 and C2H6 and charged particles such as H3(+). The last group contains compounds which are chemically unstable in parts of Jupiter's atmosphere that have been probed and include Ge and As; two elements usually found in minerals on earth. An investigation of origin of these elements which are currently part of the upper reaches of the atmosphere of Jupiter and Saturn has led to discoveries about much deeper and hotter parts of atmospheres that can never be observed directly. A number of hypotheses are presented to account for the presence of various unexpected compounds, such as carbon monoxide.

  3. 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

  4. 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.

  5. The reaction-field effect on the chemical potentials of polar aprotic non-aromatic liquids 1. Vapour pressure

    NASA Astrophysics Data System (ADS)

    Rosseinsky, D. R.; Stead, K.; Mowforth, C. W.

    1998-10-01

    The reaction field for the interaction of a molecule with its identical neighbours is shown to be a major determinant of the chemical potential of many dipolar liquids. The electrostatic potential w, derived for immersion of the dipolar molecule in its own kind, and notably comprising solely static and hf permittivities, is equated with the difference between the polar-liquid chemical potential and that of an isostructural non-polar hydrocarbon. For all the 26 non-aromatic Onsager liquids for which the requisite data are available, acceptable conformity is established of the vapour pressure calculated from w with that observed, fluorocarbons excepted. If w turns out to be small, vapour pressures of (these 12) dipolars approximate quite closely to those of the isostructural non-polars, as expected. For ketones and nitroalkanes varied-temperature data are available and well reproduced via w: thus calculated vaporization enthalpies equal the observed.

  6. Chemical potential constraints on the composition and subcellular localization of proteins

    NASA Astrophysics Data System (ADS)

    Dick, J. M.; Helgeson, H. C.

    2004-12-01

    The distribution and speciation of the metallome in organisms is amenable to study using thermodynamic calculations that take into account the chemical potentials obtaining in living cells. In particular, subcellular spatial gradients of the negative logarithms of the activities of the electron and proton (pe and pH, respectively) strongly influence the speciation of aqueous metals and other inorganic species, as well as aqueous organic and biomacromolecular species. Although pe-pH diagrams are commonly used to describe speciation in inorganic aqueous systems, they have not been applied to assess and quantify the relative stabilities of biomacromolecules in living organisms. Nevertheless, there is much to be gained by doing so. The purpose of the present communication is to demonstrate this by generating pe-pH and other equilibrium activity diagrams for proteins in the system C-H-N-O-S. The relative abundances of amino acid residues in the proteins considered are representative of proteins found in different subcellular locations. For example, the boundaries of the stability fields for extracellular, cytoplasmic, and nuclear proteins can be assessed and portrayed on pe-pH diagrams. By overlaying pe-pH diagrams for proteins with those for metals, one can predict the oxidation states of metals compatible with the proteins found in the different subcellular locations. The standard molal thermodynamic properties of these proteins can be estimated from group additivity algorithms that include provision for protein ionization as a function of solution pH. The temperature and pressure dependence of these properties can be computed with the aid of the revised HKF equations of state. Because quantifying the relative stabilities of proteins is a multidimensional problem, a Gibbs free energy minimization software package was used to carry out a plethora of computer experiments for specified temperatures, pressures, and bulk compositions. Plotting the results of the Gibbs free

  7. Strange quark matter and quark stars with the Dyson-Schwinger quark model

    NASA Astrophysics Data System (ADS)

    Chen, H.; Wei, J.-B.; Schulze, H.-J.

    2016-09-01

    We calculate the equation of state of strange quark matter and the interior structure of strange quark stars in a Dyson-Schwinger quark model within rainbow or Ball-Chiu vertex approximation. We emphasize constraints on the parameter space of the model due to stability conditions of ordinary nuclear matter. Respecting these constraints, we find that the maximum mass of strange quark stars is about 1.9 solar masses, and typical radii are 9-11km. We obtain an energy release as large as 3.6 × 10^{53} erg from conversion of neutron stars into strange quark stars.

  8. 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

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

    PubMed

    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

  10. Steroid profiling in H295R cells to identify chemicals potentially disrupting the production of adrenal steroids.

    PubMed

    Strajhar, Petra; Tonoli, David; Jeanneret, Fabienne; Imhof, Raphaella M; Malagnino, Vanessa; Patt, Melanie; Kratschmar, Denise V; Boccard, Julien; Rudaz, Serge; Odermatt, Alex

    2017-04-15

    The validated OECD test guideline 456 based on human adrenal H295R cells promotes measurement of testosterone and estradiol production as read-out to identify potential endocrine disrupting chemicals. This study aimed to establish optimal conditions for using H295R cells to detect chemicals interfering with the production of key adrenal steroids. H295R cells' supernatants were characterized by liquid chromatography-mass spectrometry (LC-MS)-based steroid profiling, and the influence of experimental conditions including time and serum content was assessed. Steroid profiles were determined before and after incubation with reference compounds and chemicals to be tested for potential disruption of adrenal steroidogenesis. The H295R cells cultivated according to the OECD test guideline produced progestins, glucocorticoids, mineralocorticoids and adrenal androgens but only very low amounts of testosterone. However, testosterone contained in Nu-serum was metabolized during the 48h incubation. Thus, inclusion of positive and negative controls and a steroid profile of the complete medium prior to the experiment (t=0h) was necessary to characterize H295R cells' steroid production and indicate alterations caused by exposure to chemicals. Among the tested chemicals, octyl methoxycinnamate and acetyl tributylcitrate resembled the corticosteroid induction pattern of the positive control torcetrapib. Gene expression analysis revealed that octyl methoxycinnamate and acetyl tributylcitrate enhanced CYP11B2 expression, although less pronounced than torcetrapib. Further experiments need to assess the toxicological relevance of octyl methoxycinnamate- and acetyl tributylcitrate-induced corticosteroid production. In conclusion, the extended profiling and appropriate controls allow detecting chemicals that act on steroidogenesis and provide initial mechanistic evidence for prioritizing chemicals for further investigations.

  11. 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.

    2016-01-01

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

  12. 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.

  13. Effect of chemical amendments on remediation of potentially toxic trace elements (PTEs) and soil quality improvement in paddy fields.

    PubMed

    Kim, Sung Chul; Hong, Young Kyu; Oh, Se Jin; Oh, Seung Min; Lee, Sang Phil; Kim, Do Hyung; Yang, Jae E

    2017-04-01

    Remediation of potentially toxic trace elements (PTEs) in paddy fields is fundamental for crop safety. In situ application of chemical amendments has been widely adapted because of its cost-effectiveness and environmental safety. The main purpose of this research was to (1) evaluate the reduction in dissolved concentrations of cadmium (Cd) and arsenic (As) with the application of chemical amendments and (2) monitor microbial activity in the soil to determine the remediation efficiency. Three different chemical amendments, lime stone, steel slag, and acid mine drainage sludge, were applied to paddy fields, and rice (Oryza sativa L. Milyang 23) was cultivated. The application of chemical amendments immobilized both Cd and As in soil. Between the two PTEs, As reduction was significant (p < 0.05) with the addition of chemical amendments, whereas no significant reduction was observed for Cd than that for the control. Among six soil-related variables, PTE concentration showed a negative correlation with soil pH (r = -0.70 for As and r = -0.54 for Cd) and soil respiration (SR) (r = -0.88 for As and r = -0.45 for Cd). This result indicated that immobilization of PTEs in soil is dependent on soil pH and reduces PTE toxicity. Overall, the application of chemical amendments could be utilized for decreasing PTE (As and Cd) bioavailability and increasing microbial activity in the soil.

  14. Peptide reactivity assay using spectrophotometric method for high-throughput screening of skin sensitization potential of chemical haptens.

    PubMed

    Jeong, Yun Hyeok; An, Susun; Shin, Kyeho; Lee, Tae Ryong

    2013-02-01

    Haptens must react with cellular proteins to be recognized by antigen presenting cells. Therefore, monitoring reactivity of chemicals with peptide/protein has been considered an in vitro skin sensitization testing method. The reactivity of peptides with chemicals (peptide reactivity) has usually been monitored by chromatographic methods like HPLC or LC/MS, which are robust tools for monitoring common chemical reactions but are rather expensive and time consuming. Here, we examined the possibility of using spectrophotometric methods to monitor peptide reactivity. Two synthetic peptides, Ac-RWAACAA and Ac-RWAAKAA, were reacted with 48 chemicals (34 sensitizers and 14 non-sensitizers). Peptide reactivity was measured by monitoring unreacted peptides with UV-Vis spectrophotometer using 5,5'-dithiobis-2-nitrobenzoic acid as a detection reagent for the free thiol group of cysteine-containing peptide or fluorometer using fluorescamine™ as a detection reagent for the free amine group of lysine-containing peptide. Chemicals were categorized as sensitizers when they induced more than 10% depletion of cysteine-containing peptide or 20% depletion of lysine-containing peptide. The sensitivity, specificity, and accuracy of this method were 82.4%, 85.7%, and 83.3%, respectively. These results demonstrate that spectrophotometric methods can be easy, fast, and high-throughput screening tools for the prediction of the skin sensitization potential of chemical haptens.

  15. 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

  16. Development of Phenotypic and Transcriptional Biomarkers to Evaluate Relative Activity of Potentially Estrogenic Chemicals in Ovariectomized Mice

    PubMed Central

    Winuthayanon, Wipawee; Pockette, Brianna; Kerns, Robnet T.; Foley, Julie F.; Flagler, Norris; Ney, Elizabeth; Suksamrarn, Apichart; Piyachaturawat, Pawinee; Bushel, Pierre R.; Korach, Kenneth S.

    2015-01-01

    Background: Concerns regarding potential endocrine-disrupting chemicals (EDCs) have led to a need for methods to evaluate candidate estrogenic chemicals. Our previous evaluations of two such EDCs revealed a response similar to that of estradiol (E2) at 2 hr, but a less robust response at 24 hr, similar to the short-acting estrogen estriol (E3). Objectives: Microarray analysis using tools to recognize patterns of response have been utilized in the cancer field to develop biomarker panels of transcripts for diagnosis and selection of treatments most likely to be effective. Biological effects elicited by long- versus short-acting estrogens greatly affect the risks associated with exposures; therefore, we sought to develop tools to predict the ability of chemicals to maintain estrogenic responses. Methods: We used biological end points in uterine tissue and a signature pattern–recognizing tool that identified coexpressed transcripts to develop and test a panel of transcripts in order to classify potentially estrogenic compounds using an in vivo system. The end points used are relevant to uterine tissue, but the resulting classification of the compounds is important for other sensitive tissues and species. Results: We evaluated biological and transcriptional end points with proven short- and long-acting estrogens and verified the use of our approach using a phytoestrogen. With our model, we were able to classify the diarylheptanoid D3 as a short-acting estrogen. Conclusions: We have developed a panel of transcripts as biomarkers which, together with biological end points, might be used to screen and evaluate potentially estrogenic chemicals and infer mode of activity. Citation: Hewitt SC, Winuthayanon W, Pockette B, Kerns RT, Foley JF, Flagler N, Ney E, Suksamrarn A, Piyachaturawat P, Bushel PR, Korach KS. 2015. Development of phenotypic and transcriptional biomarkers to evaluate relative activity of potentially estrogenic chemicals in ovariectomized mice. Environ

  17. 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

  18. 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

  19. Non-chemical stressors and cumulative risk assessment: an overview of current initiatives and potential air pollutant interactions.

    PubMed

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

    2011-06-01

    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

  20. 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.

  1. 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

    2015-07-06

    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.

  2. 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

    2016-08-04

    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.

  3. Chemical reaction CO+OH • → CO2+H• autocatalyzed by carbon dioxide: Quantum chemical study of the potential energy surfaces

    DOE PAGES

    Masunov, Artem E.; Wait, Elizabeth; Vasu, Subith S.

    2016-06-28

    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 tomore » 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. Furthermore, tt may open a new venue for controlling reaction rates for chemical manufacturing.« less

  4. 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.

  5. 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...

  6. 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...

  7. Machine Learning Predictions of Molecular Properties: Accurate Many-Body Potentials and Nonlocality in Chemical Space.

    PubMed

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

    2015-06-18

    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. In addition, the same representation allows us to predict accurate electronic properties of molecules, such as their polarizability and molecular frontier orbital energies.

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

    DOE PAGES

    Hansen, Katja; Biegler, Franziska; Ramakrishnan, Raghunathan; ...

    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

  9. 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.

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. [Monsters of Phlegon--hermaphrodites, sex-changers and other strange beings in Phlegon's marvellous stories].

    PubMed

    Pataricza, Dóra

    2010-01-01

    The 1st-2nd century greek writer, Phlegon was a representative of the genre "paradoxography". In his book entitled Peri thaumasion (Book of wonders) he collected 35 extraordinary stories among which he described hermaphrodites, sex-changers and strange births. Phlegon's stories are only a part of the more than 79 ancient writings from Greek and Roman literature that describe children born with congenital defects. The article discusses the aspects of hermaphroditism in ancient times as well as ancient teratology. These stories might have had a core of truth. Although it is extremely difficult to identify a single potential cause for it, already ancient writers tried to give an explanation. With the help of modern teratology sciences many teratogenous causes can be partly identified. A part of the most probable factors among these were the same as today: malnutrition, viruses, alcohol, vitamin deficiencies etc., but lead poisoning has also be taken into account as a principal cause.

  15. The stability of TiC surfaces in the environment with various carbon chemical potential and surface defects

    NASA Astrophysics Data System (ADS)

    Mao, Jianjun; Li, Shasha; Zhang, Yanxing; Chu, Xingli; Yang, Zongxian

    2016-11-01

    The low-index surfaces of TiC are studied using the first-principles method based on density functional theory. The surface energy of TiC is calculated with consideration of the surface orientation, termination and carbon chemical potential, as well as the influence of surface vacancy defects of various concentrations. It is found that the surface relaxation results in rumpling of the (001) and (110) surfaces and the contraction of the (111) surfaces. The relative stability of the low-index surfaces of TiC varies with the carbon chemical potential, surface defects and vacancy concentrations, which will have an effect on the nanoparticles morphology and catalytic performance in practical applications. The results will serve as a guidance for understanding and designing novel TiC nanocatalysts with special morphology.

  16. Simulation of chemical potentials and phase equilibria in two- and three-dimensional square-well fluids: finite size effects.

    PubMed

    Vörtler, Horst L; Schäfer, Katja; Smith, William R

    2008-04-17

    We study the simulation cell size dependence of chemical potential isotherms in subcritical square-well fluids by means of series of canonical ensemble Monte Carlo simulations with increasing numbers of particles, for both three-dimensional bulk systems and two-dimensional planar layers, using Widom-like particle insertion methods. By estimating the corresponding vapor/liquid coexistence densities using a Maxwell-like equal area rule for the subcritical chemical potential isotherms, we are able to study the influence of system size not only on chemical potentials but also on the coexistence properties. The chemical potential versus density isotherms show van der Waals-like loops in the subcritical vapor/liquid coexistence range that exhibit distinct finite size effects for both two- and three-dimensional fluids. Generally, in agreement with recent findings for related studies of Lennard-Jones fluids, the loops shrink with increasing number of particles. In contrast to the subcritical isotherms themselves, the equilibrium vapor/liquid densities show only a weak system size dependence and agree quantitatively with the best-known literature values for three-dimensional fluids. This allows our approach to be used to accurately predict the phase coexistence properties. Our resulting phase equilibrium results for two-dimensional square-well fluids are new. Knowledge concerning finite size effects of square-well systems is important not only for the simulation of thermodynamic properties of simple fluids, but also for the simulation of models of more complex fluids (such as aqueous or polymer fluids) involving square-well interactions.

  17. 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.

  18. Determination of chemical oxygen demand (COD) using ultrasound digestion and oxidation-reduction potential-based titration.

    PubMed

    Kim, Hyunook; Lim, Honglae; Colosimo, Mark F

    2007-09-01

    A new method for determining wastewater chemical oxygen demand (COD) using ultrasonic digestion and titration based on oxidation reduction potential (ORP) was developed. COD values of potassium hydrogen phthalate solution obtained by ultrasonic digestion were well matched with those obtained using Standard Methods. When applied to determine COD of real wastewater collected from a local treatment plant, results from the new method were within 80% to 90% of those obtained using Standard Methods. Nonetheless, the proposed strategy has the potential to be implemented into an online COD analyzing system.

  19. 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

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  3. Chemical potential shift and gap-state formation in SrTiO3-δ revealed by photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Pal, Prabir; Kumar, Pramod; Aswin, V.; Dogra, Anjana; Joshi, Amish G.

    2014-08-01

    In this study, we report on investigations of the electronic structure of SrTiO3 annealed at temperature ranging between 550 and 840 °C in an ultrahigh vacuum. Annealing induced oxygen vacancies (Ovac) impart considerable changes in the electronic structure of SrTiO3. Using core-level photoemission spectroscopy, we have studied the chemical potential shift (Δμ) as a function of annealing temperature. The result shows that the chemical potential monotonously increases with electron doping in SrTiO3-δ. The monotonous increase of the chemical potential rules out the existence of electronic phase separation in the sample. Using valence band photoemission, we have demonstrated the formation of a low density of states at the near Fermi level electronic spectrum of SrTiO3-δ. The gap-states were observed by spectral weight transfer over a large energy scale of the stoichiometric band gap of SrTiO3 system leading finally to an insulator-metal transition. We have interpreted our results from the point of structural distortions induced by oxygen vacancies.

  4. 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.

  5. 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.

  6. Bottomonium states in hot asymmetric strange hadronic matter

    NASA Astrophysics Data System (ADS)

    Mishra, Amruta; Pathak, Divakar

    2014-08-01

    We calculate the in-medium masses of the bottomonium states [Υ(1S),Υ(2S),Υ(3S), and Υ (4S)] in isospin asymmetric strange hadronic matter at finite temperatures. The medium modifications of the masses arise due to the interaction of these heavy quarkonium states with the gluon condensates of QCD. The gluon condensates in the hot hadronic matter are computed from the medium modification of a scalar dilaton field within a chiral SU(3) model, introduced in the hadronic model to incorporate the broken scale invariance of QCD. There is seen to be a drop in the masses of the bottomonium states and mass shifts are observed to be quite considerable at high densities for the excited states. The effects of density, isospin asymmetry, strangeness, as well as temperature of the medium on the masses of the Υ states are investigated. The effects of the isospin asymmetry as well as strangeness fraction of the medium are seen to be appreciable at high densities and small temperatures. The density effects are the most dominant medium effects which should have observable consequences in the compressed baryonic matter (CBM) in the heavy ion collision experiments in the future facility at FAIR, GSI. The study of the Υ states will, however, require access to energies higher than the energy regime planned at CBM experiment. The density effects on the bottomonium masses should also show up in the dilepton spectra at the Super Proton Synchrotron (SPS) energies, especially for the excited states for which the mass drop is observed to quite appreciable.

  7. 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

  8. 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.

  9. Development of chemical inhibitors of the SARS coronavirus: viral helicase as a potential target.

    PubMed

    Keum, Young-Sam; Jeong, Yong-Joo

    2012-11-15

    Severe acute respiratory syndrome (SARS) was the first pandemic in the 21st century to claim more than 700 lives worldwide. However, effective anti-SARS vaccines or medications are currently unavailable despite being desperately needed to adequately prepare for a possible SARS outbreak. SARS is caused by a novel coronavirus, and one of its components, a viral helicase, is emerging as a promising target for the development of chemical SARS inhibitors. In the following review, we describe the characterization, family classification, and kinetic movement mechanisms of the SARS coronavirus (SCV) helicase-nsP13. We also discuss the recent progress in the identification of novel chemical inhibitors of nsP13 in the context of our recent discovery of the strong inhibition of the SARS helicase by natural flavonoids, myricetin and scutellarein. These compounds will serve as important resources for the future development of anti-SARS medications.

  10. 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...

  11. 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…

  12. Modelling the chemically aged and mixed aerosols over the eastern central Atlantic Ocean - potential impacts

    NASA Astrophysics Data System (ADS)

    Astitha, M.; Kallos, G.; Spyrou, C.; O'Hirok, W.; Lelieveld, J.; Denier van der Gon, H. A. C.

    2010-07-01

    Detailed information on the chemical and physical properties of aerosols is important for assessing their role in air quality and climate. This work explores the origin and fate of continental aerosols transported over the Central Atlantic Ocean, in terms of chemical composition, number and size distribution, using chemistry-transport models, satellite data and in situ measurements. We focus on August 2005, a period with intense hurricane and tropical storm activity over the Atlantic Ocean. A mixture of anthropogenic (sulphates, nitrates), natural (desert dust, sea salt) and chemically aged (sulphate and nitrate on dust) aerosols is found entering the hurricane genesis region, most likely interacting with clouds in the area. Results from our modelling study suggest rather small amounts of accumulation mode desert dust, sea salt and chemically aged dust aerosols in this Atlantic Ocean region. Aerosols of smaller size (Aitken mode) are more abundant in the area and in some occasions sulphates of anthropogenic origin and desert dust are of the same magnitude in terms of number concentrations. Typical aerosol number concentrations are derived for the vertical layers near shallow cloud formation regimes, indicating that the aerosol number concentration can reach several thousand particles per cubic centimetre. The vertical distribution of the aerosols shows that the desert dust particles are often transported near the top of the marine cloud layer as they enter into the region where deep convection is initiated. The anthropogenic sulphate aerosol can be transported within a thick layer and enter the cloud deck through multiple ways (from the top, the base of the cloud, and by entrainment). The sodium (sea salt related) aerosol is mostly found below the cloud base. The results of this work may provide insights relevant for studies that consider aerosol influences on cloud processes and storm development in the Central Atlantic region.

  13. Chemically aged and mixed aerosols over the Central Atlantic Ocean - potential impacts

    NASA Astrophysics Data System (ADS)

    Astitha, M.; Kallos, G.; Spyrou, C.; O'Hirok, W.; Lelieveld, J.; Denier van der Gon, H. A. C.

    2010-02-01

    Detailed information on the chemical and physical properties of aerosols is important for assessing their role in air quality and climate. This work explores the origin and fate of continental aerosols transported over the Central Atlantic Ocean, in terms of chemical composition, number and size distribution, using chemistry-transport models, satellite data and in situ measurements. We focus on August 2005, a period with intense hurricane and tropical storm activity over the Atlantic Ocean. A mixture of anthropogenic (sulphates, nitrates), natural (desert dust, sea salt) and chemically aged (sulphate and nitrate on dust) aerosols is found entering the hurricane genesis region, most likely interacting with clouds in the area. Results from our modelling study suggest rather small amounts of accumulation mode desert dust, sea salt and chemically aged dust aerosols in this Atlantic Ocean region. Aerosols of smaller size (Aitken mode) are more abundant in the area and in some occasions sulphates of anthropogenic origin and desert dust are of the same magnitude in terms of number concentrations. Typical aerosol number concentrations are derived for the vertical layers near shallow cloud formation regimes, designating that the aerosol number concentration can reach several thousand particles per cubic centimetre. The vertical distribution of the aerosols indicates that the desert dust particles are often transported near the top of the marine cloud layer as they enter into the region where deep convection is initiated. The anthropogenic sulphate aerosol can be transported within a thick layer and enter the cloud deck through multiple ways (from the top, the base of the cloud and entrainment). The sodium (sea salt related) aerosol is mostly found below the cloud base. The results of this work may provide insights relevant for studies that consider aerosol influences on cloud processes and storm development in the Central Atlantic region.

  14. Asymmetries between strange and antistrange particle production inpion-proton interactions

    SciTech Connect

    Gutierrez, T.D.; Vogt, R.

    2002-01-29

    Recent measurements of the asymmetries between Feynman x-distributions of strange and antistrange hadrons in {pi}{sup -}A interactions show a strong effect as a function of x{sub F}. We calculate strange hadron production in the context of the intrinsic model and make predictions for particle/antiparticle asymmetries in these interactions.

  15. In Medium Properties of Charmed Strange Mesons in Dense Hadron ic Matter

    NASA Astrophysics Data System (ADS)

    Kumar, Sushil

    2015-05-01

    The medium modifications of the charmed strange mesons in the dense hadronic matter are investigated within chiral S U(4) model. The charmed strange meson properties modifies due to their interactions with the nucleons, hyperons and the scalar mesons (scalar-isoscalar mesons ( σ, ζ), scalar isovector meson ( δ)) in the dense hadronic medium. The various parameters used in the chiral model are obtained by fitting the vacuum baryon masses and saturation properties of nuclear matter. The non-linear coupled equations of the scalar fields are solved to obtain their baryon density, isospin and strangeness dependent values. Furthermore, the dispersion relations are derived for charmed strange mesons. Effects of isospin asymmetry and strangeness on the energies of charmed strange mesons are investigated. The in medium properties of charmed strange mesons can be particularly relevant to the experiments with neutron rich beams at the Facility for Antiproton and Ion Research (FAIR) at GSI, Germany, as well as to experiments at the Rare Isotope Accelerator (RIA) laboratory, USA. The present study of the in medium properties of charmed strange mesons will be of direct relevance for the observables from the compressed baryonic matter, resulting from the heavy ion collision experiments.

  16. Aspects of strangeness production with 15 -- 30 GeV proton beams

    SciTech Connect

    Dover, C.B.

    1992-04-01

    We discuss the spectrum of physics questions related to strangeness which could be addressed with a 15--30 GeV proton storage ring. We focus on various aspects of strangeness production, including hyperon production in pp collisions, studies of hyperon-nucleon scattering, production of hyper-fragments in p-nucleus collisions, and hyperon spin observables in inclusive production.

  17. Universal strangeness production in hadronic and nuclear collisions

    NASA Astrophysics Data System (ADS)

    Castorina, P.; Plumari, S.; Satz, H.

    2016-07-01

    We show that strangeness suppression in hadronic and nuclear collisions is fully determined by the initial energy density of the collision. The suppression factor γs(s), with s denoting the collision energy, can be expressed as a universal function of the initial energy density ɛ0(s), and the resulting pattern is in excellent agreement with data from p-p, p-Pb, Cu-Cu, Au-Au and Pb-Pb data over a wide range of energies and for different centralities.

  18. Extracting nucleon strange and anapole form factors from data

    SciTech Connect

    R.D. Young; J. Roche; R.D. Carlini; A.W. Thomas

    2006-04-14

    Using the complete world set of parity violating electron scattering data up to Q{sup 2} {approx} 0.3 GeV{sup 2}, we extract the current best determination of the strange electric and magnetic form factors of the proton, as well as the weak axial form factors of the proton and neutron at Q{sup 2} = 0.1 GeV{sup 2}. The results are consistent with state of the art calculations of all four form factors, with the latter including the anapole contribution.

  19. Connected, disconnected and strange quark contributions to HVP

    NASA Astrophysics Data System (ADS)

    Bijnens, Johan; Relefors, Johan

    2016-11-01

    We calculate all neutral vector two-point functions in Chiral Perturbation Theory (ChPT) to two-loop order and use these to estimate the ratio of disconnected to connected contributions as well as contributions involving the strange quark. We extend the ratio of -1/10 derived earlier in two flavour ChPT at one-loop order to a large part of the higher order contributions and discuss corrections to it. Our final estimate of the ratio disconnected to connected is negative and a few % in magnitude.

  20. 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.

  1. Evidence for Strange Stellar Family (Artist Concept)

    NASA Technical Reports Server (NTRS)

    2007-01-01

    This artist concept depicts a quadruple-star system called HD 98800. The system is approximately 10 million years old, and is located 150 light-years away in the constellation TW Hydrae.

    HD 98800 contains four stars, which are paired off into doublets, or binaries. The stars in the binary pairs orbit around each other, and the two pairs also circle each other like choreographed ballerinas. One of the stellar pairs, called HD 98800B, has a disk of dust around it, while the other pair does not.

    Although the four stars are gravitationally bound, the distance separating the two binary pairs is about 50 astronomical units (AU) -- slightly more than the average distance between our sun and Pluto.

    Using NASA's Spitzer Space Telescope, scientists finally have a detailed view of HD 98800B's potential planet-forming disk. Astronomers used the telescope's infrared spectrometer to detect the presence of two belts in the disk made of large dust grains. One belt sits approximately 5.9 AU away from the central binary, or about the distance from the sun to Jupiter, and is likely made up of asteroids and comets. The other belt sits at 1.5 to 2 AU, comparable to the area where Mars and the asteroid belt sit, and is made up of sand-sized dust grains.

  2. Skin sensitizers induce antioxidant response element dependent genes: application to the in vitro testing of the sensitization potential of chemicals.

    PubMed

    Natsch, Andreas; Emter, Roger

    2008-03-01

    Tests for skin sensitization are required prior to the market launch of new cosmetic ingredients and in vitro tests are needed to replace the current animal tests. Protein reactivity is the common feature of skin sensitizers and it is a crucial question whether a cellular in vitro assay can detect protein reactivity of diverse test chemicals. The signaling pathway involving the repressor protein Keap1 and the transcription factor nuclear factor-erythroid 2-related factor 2, which binds to the antioxidant response element (ARE) in the promoter of many phase II detoxification genes, is a potential cellular marker because Keap1 had been shown to be covalently modified by electrophiles which leads to activation of ARE-dependent genes. To evaluate whether this regulatory pathway can be used to develop a predictive cellular in vitro test for sensitization, 96 different chemicals of known skin sensitization potential were added to Hepa1C1C7 cells and the induction of the ARE-regulated quinone reductase (QR) activity was determined. In parallel, 102 chemicals were tested on the reporter cell line AREc32, which contains an eightfold repeat of the ARE sequence upstream of a luciferase gene. Among the strong/extreme skin sensitizers 14 out of 15 and 30 out of 34 moderate sensitizers induced the ARE-dependent luciferase activity and in many cases this response was paralleled by an induction of QR activity in Hepa1C1C7 cells. Sixty percent of the weak sensitizers also induced luciferase activity, and the overall accuracy of the assay was 83 percent. Only four of 30 tested nonsensitizers induced low levels of luciferase activity, indicating a high specificity of the assay. Thus, measurement of the induction of this signaling pathway provides an interesting in vitro test to screen for the skin sensitization potential of novel chemicals.

  3. Using the Moon As A Low-Noise Seismic Detector For Strange Quark Nuggets

    NASA Technical Reports Server (NTRS)

    Banerdt, W. Bruce; Chui, Talso; Griggs, Cornelius E.; Herrin, Eugene T.; Nakamura, Yosio; Paik, Ho Jung; Penanen, Konstantin; Rosenbaum, Doris; Teplitz, Vigdor L.; Young, Joseph

    2006-01-01

    Strange quark matter made of up, down and strange quarks has been postulated by Witten [1]. Strange quark matter would be nearly charge neutral and would have density of nuclear matter (10(exp 14) gm/cu cm). Witten also suggested that nuggets of strange quark matter, or strange quark nuggets (SQNs), could have formed shortly after the Big Bang, and that they would be viable candidates for cold dark matter. As suggested by de Rujula and Glashow [2], an SQN may pass through a celestial body releasing detectable seismic energy along a straight line. The Moon, being much quieter seismically than the Earth, would be a favorable place to search for such events. We review previous searches for SQNs to illustrate the parameter space explored by using the Moon as a low-noise detector of SQNs. We also discuss possible detection schemes using a single seismometer, and using an International Lunar Seismic Network.

  4. Measurement of strange particle production in the NICA fixed-target programme

    NASA Astrophysics Data System (ADS)

    Friese, Volker

    2016-08-01

    Strange particles provide a sensitive tool to study the dense and hot matter created in relativistic nuclear collisions. Although strangeness production in such collisions has been a topic of experimental and theoretical research for many years, its understanding is far from being complete. This holds in particular for multi-strange hyperons and for lower collision energies as relevant for NICA and FAIR. Multi-strange particles, being sensitive to both the mechanism of strangeness production and the net-baryon density, are expected to shed light on the state of the created matter and to indicate possible transitions to new phases of strongly interacting matter. We thus advocate the measurement of hyperons and φ mesons in a fixed-target experiment at NICA (BM@N), which can be achieved by a relatively compact detector system.

  5. 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

  6. Biochemical Testing of Potentially Hazardous Chemicals for Toxicity Using Mammalian Liver Cell Cultures.

    DTIC Science & Technology

    1992-04-09

    the 1i. a. neeeae ind -nc.-.Dlenrn I rp, 1 •he ŽIP’Ton .)? f.-tm ’ ltn ’pC .Die,, ’t’J P h f, burden " .’.’- !re . j’ t ther 4sIe’ t jf-’s * oIle ,lion I...amines, nitrosamines and aflatoxins , are among the important classes of chemical carcinogens that become bound to tissue macromolecules (e.g...g centrifugation of the cell homogenate. When protein concentration was determined, it rose sharply between 2 and 4h, was essentially unchanged

  7. 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.

  8. Anionic cyclophanes as potential reversal agents of muscle relaxants by chemical chelation.

    PubMed

    Cameron, Kenneth S; Fielding, Lee; Mason, Rona; Muir, Alan W; Rees, David C; Thorn, Simon; Zhang, Ming Qiang

    2002-03-11

    A series of carboxyl-containing cyclophanes have been designed and synthesised as chemical chelators (or host molecules) of cationic muscle relaxant drugs (or guest molecules). Three of these cyclophane derivatives, 1-3, have been shown by NMR to form 1:1 complexes with the muscle relaxants pancuronium, and gallamine, in D(2)O, with association constants up to 10(4) M(-1). When tested in an in vitro chick biventer muscle preparation, the cyclophanes reversed the neuromuscular block induced by pancuronium and gallamine, with having the most effective reversal against pancuronium (EC(50) 40 microM.

  9. Parasitism as a source of potential distortion in studies on endocrine disrupting chemicals in molluscs.

    PubMed

    Morley, Neil J

    2006-11-01

    The effects of endocrine disrupting chemicals (EDC) on molluscs in both marine and freshwater polluted environments are a continuing area of concern resulting in many field and laboratory studies. However, molluscs are commonly infected with trematode parasites which, in order to obtain sufficient nutrients for their own development, naturally disrupt the functioning of the endocrine system of the host. The physiological effects of parasitisation on the reproduction and immune response of molluscs are summarised, using a number of examples, and the implications for EDC studies are discussed.

  10. Potential External Contamination with Bisphenol A and Other Ubiquitous Organic Environmental Chemicals during Biomonitoring Analysis: An Elusive Laboratory Challenge

    PubMed Central

    Ye, Xiaoyun; Zhou, Xiaoliu; Hennings, Ryan; Kramer, Joshua

    2013-01-01

    Background: Biomonitoring studies are conducted to assess internal dose (i.e., body burden) to environmental chemicals. However, because of the ubiquitous presence in the environment of some of these chemicals, such as bisphenol A (BPA), external contamination during handling and analysis of the biospecimens collected for biomonitoring evaluations could compromise the reported concentrations of such chemicals. Objectives: We examined the contamination with the target analytes during analysis of biological specimens in biomonitoring laboratories equipped with state-of-the-art analytical instrumentation. Discussions: We present several case studies using the quantitative determination of BPA and other organic chemicals (i.e., benzophenone-3, triclosan, parabens) in human urine, milk, and serum to identify potential contamination sources when the biomarkers measured are ubiquitous environmental contaminants. Conclusions: Contamination with target analytes during biomonitoring analysis could result from solvents and reagents, the experimental apparatus used, the laboratory environment, and/or even the analyst. For biomonotoring data to be valid—even when obtained from high-quality analytical methods and good laboratory practices—the following practices must be followed to identify and track unintended contamination with the target analytes during analysis of the biological specimens: strict quality control measures including use of laboratory blanks; replicate analyses; engineering controls (e.g., clean rooms, biosafety cabinets) as needed; and homogeneous matrix-based quality control materials within the expected concentration ranges of the study samples. PMID:23458838

  11. 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.

  12. Chemical trapping of vancomycin: a potential strategy for preventing selection of vancomycin-resistant Enterococci.

    PubMed

    Horwitz, Ehud; Tal-Gan, Yftah; Temper, Violetta; Shapiro, Mervyn; Gilon, Chaim; Hoffman, Amnon

    2012-04-01

    Emergence of antimicrobial resistance is among the most worrisome issues in public health worldwide. Vancomycin resistance is rapidly spreading, resulting in increased morbidity, mortality, and healthcare-associated costs. Multiple strategies are required to preserve the effectiveness of this essential antibiotic. It has been recently shown that biliary excretion of vancomycin following parenteral administration results in significant fecal concentrations of vancomycin that may lead to selection of vancomycin-resistant strains within the colon. In this study we present a novel strategy for preventing this undesired effect and its consequences, using chemical trapping of vancomycin by a tripeptide analog that mimics the natural bacterial vancomycin binding-site. Initially, we demonstrated that a tripeptide analog can neutralize vancomycin activity against Enterococci at a molar excess of 28. In the second phase, two chemical modifications, designed to attach the tripeptide to vancomycin covalently, were explored. Attachment of a 4-flurosulfonyl-benzoic acid (FSBA) moiety to the parent tripeptide resulted in vancomycin neutralization at a molar ratio of less than 4:1. Finally it was shown that the FSBA-bound tripeptide analog can prevent in-vitro selection of vancomycin-resistant Enterococci (VRE) from a mixed vancomycin susceptible/resistant population following exposure to vancomycin. These findings demonstrate the ability of the proposed strategy to prevent selection of VRE. The present proof-of-concept study provides the basis for further development of the proposed strategy. Further, this strategy may be implemented for combating resistance to other antimicrobials.

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

    PubMed Central

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

    1987-01-01

    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 U.S. 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. PMID:3447901

  14. Comparing Two Attachment Classification Methods Applied to Preschool Strange Situations

    PubMed Central

    Spieker, Susan; Crittenden, Patricia Mckinsey

    2013-01-01

    This study compared two methods for classifying preschool-age children's behavior in the Strange Situation procedure, the MacArthur (MAC) and the Preschool Assessment of Attachment (PAA), to determine whether they operationalized converging or diverging approaches to attachment theory. Strange Situations of 306 randomly selected 3-year-old children and their mothers in the NICHD Study of Early Child Care and Youth Development were classified with the MAC and PAA. The methods showed 50% agreement. A block of seven demographic, child and family predictors was unrelated to MAC classifications, but accounted for 19% of the variance in PAA classifications. The MAC and PAA each had associations with some child outcomes in grades 1-5 (ages 6-10) totalling 5% and 12% of the variance respectively, but some of the MAC associations were counter to the hypothesis. The MAC and PAA were sufficiently different to reflect both different classificatory methods and different theoretical understandings of attachment. Results are discussed in terms of limitations of the sample and measures available to compare the two methods, and clinical implications. PMID:19914941

  15. Electroproduction of baryon-meson states and strangeness suppression

    NASA Astrophysics Data System (ADS)

    Santopinto, E.; García-Tecocoatzi, H.; Bijker, R.

    2016-08-01

    We describe the electroproduction ratios of baryon-meson states from nucleon, inferring from the sea quarks in the nucleon using an extension of the quark model that takes into account the sea. As a result we provide, with no adjustable parameters, the predictions of ratios of exclusive meson-baryon final states: ΛK+, Σ* K, ΣK, pπ0, and nπ+. These predictions are in agreement with the new JLab experimental data showing that sea quarks play an important role in the electroproduction. We also predicted further ratios of exclusive reactions that can be measured and tested in future experiments. In particular, we suggested new experiments on deuterium and tritium. Such measurements can provide crucial tests of different predictions concerning the structure of nucleon and its sea quarks helping to solve an outstanding problem. Finally, we compute the so called strangeness suppression factor, λs, that is the suppression of strange quark-antiquark pairs compared to nonstrange pairs, and we found that our finding with this simple extension of the quark model is in good agreement with the results of JLab and CERN experiments.

  16. "Making strange": a role for the humanities in medical education.

    PubMed

    Kumagai, Arno K; Wear, Delese

    2014-07-01

    Stories, film, drama, and art have been used in medical education to enhance empathy, perspective-taking, and openness to "otherness," and to stimulate reflection on self, others, and the world. Yet another, equally important function of the humanities and arts in the education of physicians is that of "making strange"-that is, portraying daily events, habits, practices, and people through literature and the arts in a way that disturbs and disrupts one's assumptions, perspectives, and ways of acting so that one sees the self, others, and the world anew. Tracing the development of this concept from Viktor Shklovsky's "enstrangement" (ostranenie) through Bertolt Brecht's "alienation effect," this essay describes the use of this technique to disrupt the "automaticity of thinking" in order to discover new ways of perceiving and being in the world.Enstrangement may be used in medical education in order to stimulate critical reflection and dialogue on assumptions, biases, and taken-for-granted societal conditions that may hinder the realization of a truly humanistic clinical practice. In addition to its ability to enhance one's critical understanding of medicine, the technique of "making strange" does something else: By disrupting fixed beliefs, this approach may allow a reexamination of patient-physician relationships in terms of human interactions and provide health care professionals an opportunity-an "open space"-to bear witness and engage with other individuals during challenging times.

  17. Detectability of strange matter in heavy ion experiments

    SciTech Connect

    Schaffner, J., ||; Diener, A.; Stocker, H.,; Greiner, C.,

    1997-06-01

    We discuss the properties of two distinct forms of hypothetical strange matter, small lumps of strange quark matter (strangelets) and of hyperon matter [metastable exotic multihypernuclear objects (MEMO{close_quote}s)], with special emphasis on their relevance for present and future heavy ion experiments. The masses of small strangelets up to A{sub B}=40 are calculated using the MIT bag model with shell mode filling for various bag parameters. The strangelets are checked for possible strong and weak hadronic decays, also taking into account multiple hadron decays. It is found that strangelets which are stable against strong decay are most likely highly negatively charged, contrary to previous findings. Strangelets can be stable against weak hadronic decay but their masses and charges are still rather high. This has serious impact on the present high sensitivity searches in heavy ion experiments at the AGS and CERN facilities. On the other hand, highly charged MEMO{close_quote}s are predicted on the basis of an extended relativistic mean-field model. Those objects could be detected in future experiments searching for short-lived, rare composites. It is demonstrated that future experiments can be sensitive to a much wider variety of strangelets. {copyright} {ital 1997} {ital The American Physical Society}

  18. An almost symmetric Strang splitting scheme for nonlinear evolution equations.

    PubMed

    Einkemmer, Lukas; Ostermann, Alexander

    2014-07-01

    In this paper we consider splitting methods for the time integration of parabolic and certain classes of hyperbolic partial differential equations, where one partial flow cannot be computed exactly. Instead, we use a numerical approximation based on the linearization of the vector field. This is of interest in applications as it allows us to apply splitting methods to a wider class of problems from the sciences. However, in the situation described, the classic Strang splitting scheme, while still being a method of second order, is not longer symmetric. This, in turn, implies that the construction of higher order methods by composition is limited to order three only. To remedy this situation, based on previous work in the context of ordinary differential equations, we construct a class of Strang splitting schemes that are symmetric up to a desired order. We show rigorously that, under suitable assumptions on the nonlinearity, these methods are of second order and can then be used to construct higher order methods by composition. In addition, we illustrate the theoretical results by conducting numerical experiments for the Brusselator system and the KdV equation.

  19. An almost symmetric Strang splitting scheme for nonlinear evolution equations☆

    PubMed Central

    Einkemmer, Lukas; Ostermann, Alexander

    2014-01-01

    In this paper we consider splitting methods for the time integration of parabolic and certain classes of hyperbolic partial differential equations, where one partial flow cannot be computed exactly. Instead, we use a numerical approximation based on the linearization of the vector field. This is of interest in applications as it allows us to apply splitting methods to a wider class of problems from the sciences. However, in the situation described, the classic Strang splitting scheme, while still being a method of second order, is not longer symmetric. This, in turn, implies that the construction of higher order methods by composition is limited to order three only. To remedy this situation, based on previous work in the context of ordinary differential equations, we construct a class of Strang splitting schemes that are symmetric up to a desired order. We show rigorously that, under suitable assumptions on the nonlinearity, these methods are of second order and can then be used to construct higher order methods by composition. In addition, we illustrate the theoretical results by conducting numerical experiments for the Brusselator system and the KdV equation. PMID:25844017

  20. 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.

  1. DART MS based chemical profiling for therapeutic potential of Piper betle landraces.

    PubMed

    Bajpai, Vikas; Pandey, Renu; Negi, Mahendra Pal Singh; Kumar, Nikhil; Kumar, Brijesh

    2012-12-01

    Piper betle Linn. leaves are traditionally used as a folk medicine in India and other Asiatic countries. Twenty-one P. betle landraces were analyzed using a Direct Analysis in Real Time (DART) mass spectral technique and evaluated on the basis of molecules detected in the leaves. Clustering of landraces based on three well known biologically active phenols (m/z 151,165,193) showed two broad groups with high and low phenol contents suggesting differences in their therapeutic potential. Findings of this study could be useful in rapid screening of the landraces for determining their medicinal potential and optimum utilization of the bioresource.

  2. Machine learning scheme for fast extraction of chemically interpretable interatomic potentials

    NASA Astrophysics Data System (ADS)

    Dolgirev, Pavel E.; Kruglov, Ivan A.; Oganov, Artem R.

    2016-08-01

    We present a new method for a fast, unbiased and accurate representation of interatomic interactions. It is a combination of an artificial neural network and our new approach for pair potential reconstruction. The potential reconstruction method is simple and computationally cheap and gives rich information about interactions in crystals. This method can be combined with structure prediction and molecular dynamics simulations, providing accuracy similar to ab initio methods, but at a small fraction of the cost. We present applications to real systems and discuss the insight provided by our method.

  3. Effects of gamma irradiation on chemical composition and antioxidant potential of processed samples of the wild mushroom Macrolepiota procera.

    PubMed

    Fernandes, Ângela; Barreira, João C M; Antonio, Amilcar L; Oliveira, M Beatriz P P; Martins, Anabela; Ferreira, Isabel C F R

    2014-04-15

    It was previously demonstrated that gamma irradiation was the processing technology with the highest capacity to maintain the chemical profile of fresh Macrolepiota procera wild mushroom, when compared to freeze-dried or oven-dried samples. Herein, it was aimed to evaluate gamma irradiation effects on processed samples. Chemical composition and antioxidant potential of irradiated (0.5 and 1 kGy) fresh, frozen and dried samples were determined by chromatographic techniques and in vitro assays, respectively. M. procera irradiation attenuated the effects caused by oven-drying or freezing; combining freeze treatment with 0.5 kGy dose preserved total tocopherols. Rather than a conservation methodology, gamma irradiation might act as a useful adjuvant to other conservation techniques (e.g., freezing or oven-drying).

  4. A quantum chemical based toxicity study of estimated reduction potential and hydrophobicity in series of nitroaromatic compounds.

    PubMed

    Gooch, A; Sizochenko, N; Sviatenko, L; Gorb, L; Leszczynski, J

    2017-02-01

    Nitroaromatic compounds and the products of their degradation are toxic to bacteria, cells and animals. Various studies have been carried out to better understand the mechanism of toxicity of aromatic nitrocompounds and their relationship to humans and the environment. Recent data relate cytotoxicity of nitroaromatic compounds to their single- or two-electron enzymatic reduction. However, mechanisms of animal toxicity could be more complex. This work investigates the estimated reduction and oxidation potentials of 34 nitroaromatic compounds using quantum chemical approaches. All geometries were optimized with density functional theory (DFT) using the solvation model based on density (SMD) and polarizable continuum model (PCM) solvent model protocols. Quantitative structure-activity/property (QSAR/QSPR) models were developed using descriptors obtained from quantum chemical optimizations as well as the DRAGON software program. The QSAR/QSPR equations developed consist of two to four descriptors. Correlations have been identified between electron affinity (ELUMO) and hydrophobicity (log P).

  5. 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.

  6. 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

  7. 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.

  8. Artificial Force Induced Reaction (AFIR) Method for Exploring Quantum Chemical Potential Energy Surfaces.

    PubMed

    Maeda, Satoshi; Harabuchi, Yu; Takagi, Makito; Taketsugu, Tetsuya; Morokuma, Keiji

    2016-10-01

    In this account, a technical overview of the artificial force induced reaction (AFIR) method is presented. The AFIR method is one of the automated reaction-path search methods developed by the authors, and has been applied extensively to a variety of chemical reactions, such as organocatalysis, organometallic catalysis, and photoreactions. There are two modes in the AFIR method, i.e., a multicomponent mode and a single-component mode. The former has been applied to bimolecular and multicomponent reactions and the latter to unimolecular isomerization and dissociation reactions. Five numerical examples are presented for an Aldol reaction, a Claisen rearrangement, a Co-catalyzed hydroformylation, a fullerene structure search, and a nonradiative decay path search in an electronically excited naphthalene molecule. Finally, possible applications of the AFIR method are discussed.

  9. 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.

  10. Chemical synthesis of D-ribo-phytosphingosine-1-phosphate, a potential modulator of cellular processes.

    PubMed

    Li, S; Wilson, W K; Schroepfer, G J

    1999-01-01

    d-erythro -Sphingosine-1-phosphate (2), an intermediate in sphingosine metabolism, shows a diversity of biological activities. Comparable roles might be anticipated for d-ribo -phytosphingosine-1-phosphate (1). We describe an efficient three-step chemical synthesis of 1 from d-ribo -phytosphingosine. Our approach is based on standard phosphoramidite methodology and on the finding of Boumendjel and Miller ( J. Lipid Res. 1994. 35: 2305-2311) that sphingosine can be monophosphorylated at the 1-hydroxyl without protection of the 3-hydroxyl. However, we were unable to duplicate their reported synthesis of 2 without important modifications in reagents and reaction conditions. Under the reported conditions for preparing 2, we obtained a cyclic carbamate (14), which we have isolated and identified. The structures of 1 and the cyclic carbamate 14 were elucidated by a combination of mass spectrometry and 1D and 2D nuclear magnetic resonance spectroscopy.

  11. 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

  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.

  13. 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.

  14. 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. ...

  15. 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.

  16. 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

  17. 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.

  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.

  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. Computed potential energy surfaces for chemical reactions. Semiannual report, 1 January-30 June 1990

    SciTech Connect

    Walch, S.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.