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Sample records for effect revisited thermodynamic

  1. Temperature Effect on Micelle Formation: Molecular Thermodynamic Model Revisited.

    PubMed

    Khoshnood, Atefeh; Lukanov, Boris; Firoozabadi, Abbas

    2016-03-01

    Temperature affects the aggregation of macromolecules such as surfactants, polymers, and proteins in aqueous solutions. The effect on the critical micelle concentration (CMC) is often nonmonotonic. In this work, the effect of temperature on the micellization of ionic and nonionic surfactants in aqueous solutions is studied using a molecular thermodynamic model. Previous studies based on this technique have predicted monotonic behavior for ionic surfactants. Our investigation shows that the choice of tail transfer energy to describe the hydrophobic effect between the surfactant tails and the polar solvent molecules plays a key role in the predicted CMC. We modify the tail transfer energy by taking into account the effect of the surfactant head on the neighboring methylene group. The modification improves the description of the CMC and the predicted micellar size for aqueous solutions of sodium n-alkyl sulfate, dodecyl trimethylammonium bromide (DTAB), and n-alkyl polyoxyethylene. The new tail transfer energy describes the nonmonotonic behavior of CMC versus temperature. In the DTAB-water system, we redefine the head size by including the methylene group, next to the nitrogen, in the head. The change in the head size along with our modified tail transfer energy improves the CMC and aggregation size prediction significantly. Tail transfer is a dominant energy contribution in micellar and microemulsion systems. It also promotes the adsorption of surfactants at fluid-fluid interfaces and affects the formation of adsorbed layer at fluid-solid interfaces. Our proposed modifications have direct applications in the thermodynamic modeling of the effect of temperature on molecular aggregation, both in the bulk and at the interfaces. PMID:26854650

  2. Revisiting the Thermodynamics of Water Surfaces and the Effects of Surfactant Head Group.

    PubMed

    Hu, Dan; Mafi, Amirhossein; Chou, Keng C

    2016-03-10

    It is common knowledge that surfactants lower the surface tension of water. The typical textbook explanation of this phenomenon is that the force of attraction between surfactant and water molecules is less than that between two water molecules; hence the surface contraction force decreases in the presence of surfactants; however, this common description, based on the strength of intermolecular interactions, is overly simplified because it ignores an important thermodynamic function: the surface entropy of water. Here we report separate measurements of water's surface enthalpy and surface entropy in the presence of nonionic, zwitterionic, anionic, and cationic surfactants. While all of these surfactants decreased the surface enthalpy of water by 50-70%, the surface entropy of water could drop to near-zero or even negative values for ionic surfactants. Studies of this zero-entropy state of water surface using phase-sensitive sum-frequency generation (SFG) vibrational spectroscopy and molecular dynamics (MD) simulations suggested that the zero-entropy state of the water surface was associated with surfactant-induced ordering of water molecules and enhanced hydrogen bond formation at the water surface. Both effects reduce water molecules' degrees of freedom for motion and thus lower the surface entropy of water. The ability of a surfactant to decrease the surface entropy of water is in the order ionic > zwitterionic > nonionic. For all surfactant head groups surface entropy plays a critical role in determining the surface tension of water. The description of water's surface tension is not complete without considering its surface entropy. PMID:26842782

  3. Automated Guidance for Thermodynamics Essays: Critiquing Versus Revisiting

    NASA Astrophysics Data System (ADS)

    Donnelly, Dermot F.; Vitale, Jonathan M.; Linn, Marcia C.

    2015-12-01

    Middle school students struggle to explain thermodynamics concepts. In this study, to help students succeed, we use a natural language processing program to analyze their essays explaining the aspects of thermodynamics and provide guidance based on the automated score. The 346 sixth-grade students were assigned to either the critique condition where they criticized an explanation or the revisit condition where they reviewed visualizations. Within each condition, the student was assigned one of two types of tailored guidance based on the sophistication of their original essay. Both forms of guidance led to significant improvement in student understanding on the posttest. Guidance was more effective for students with low prior knowledge than for those with high prior knowledge (consistent with regression toward the mean). However, analysis of student responses to the guidance illustrates the value of aligning guidance with prior knowledge. All students were required to revise their essay as an embedded assessment. While effective, teachers involved in this study reported that revising is resisted by students and does not align with typical, vocabulary-focused classroom writing activities.

  4. Thermodynamics of sulfur poisoning in solid oxide fuel cells revisited: The effect of H2S concentration, temperature, current density and fuel utilization

    NASA Astrophysics Data System (ADS)

    da Silva, Aline Lima; Heck, Nestor Cezar

    2015-11-01

    Thermodynamics of sulfur poisoning in SOFCs is revisited in the present study, aiming at contributing to the understanding of the effects of different operating parameters on deactivation by sulfur. Ni-S Gibbs energy diagram shows that, whenever sulfur chemical potential is increased, the catalyst poisoning becomes greater, due to increase in nickel sulfide activity, which is a strictly increasing function of sulfur coverage on Ni surface. For studying current density effect, simulations are carried out in the range of 0 (OCV) - 1 A cm-2, at 1123 K, considering methane as a fuel. At 10 ppm H2S, an increase in current density from 0 (OCV) to 0.5 A cm-2 results in a slight increase in the nickel sulfide activity from 3.0 × 10-6 to 1.2 × 10-5; however, at 1 A cm-2, nickel sulfide activity is 25.000 times higher than at 0.5 A cm-2. At 1 A cm-2, H2 and CO are almost entirely converted to H2O and CO2 by electrochemical reaction. Therefore, the effect of current density becomes remarkable when fuel utilization approaches 100%. These theoretical findings are corroborated by the recent experimental evidences related to the detrimental influence of current density on SOFC performance during sulfur poisoning.

  5. Extended irreversible thermodynamics revisited (1988-98)

    NASA Astrophysics Data System (ADS)

    Jou, D.; Casas-Vázquez, J.; Lebon, G.

    1999-07-01

    We review the progress made in extended irreversible thermodynamics during the ten years that have elapsed since the publication of our first review on the same subject (Rep. Prog. Phys. 1988 51 1105 - 72). During this decade much effort has been devoted to achieving a better understanding of the fundamentals and a broadening of the domain of applications. The macroscopic formulation of extended irreversible thermodynamics is reviewed and compared with other non-equilibrium thermodynamic theories. The foundations of EIT are discussed on the bases of information theory, kinetic theory, stochastic phenomena and computer simulations. Several significant applications are presented, some of them of considerable practical interest (non-classical heat transport, polymer solutions, non-Fickian diffusion, microelectronic devices, dielectric relaxation), and some others of special theoretical appeal (superfluids, nuclear collisions, cosmology). We also outline some basic problems which are not yet completely solved, such as the definitions of entropy and temperature out of equilibrium, the selection of the relevant variables, and the status to be reserved to the H-theorem and its relation to the second law. In writing this review, we had four objectives in mind: to show (i) that extended irreversible thermodynamics stands at the frontiers of modern thermodynamics; (ii) that it opens the way to new and useful applications; (iii) that much progress has been achieved during the last decade, and (iv) that the subject is far from being exhausted.

  6. Automated Guidance for Thermodynamics Essays: Critiquing versus Revisiting

    ERIC Educational Resources Information Center

    Donnelly, Dermot F.; Vitale, Jonathan M.; Linn, Marcia C.

    2015-01-01

    Middle school students struggle to explain thermodynamics concepts. In this study, to help students succeed, we use a natural language processing program to analyze their essays explaining the aspects of thermodynamics and provide guidance based on the automated score. The 346 sixth-grade students were assigned to either the critique condition…

  7. The Thermodynamics of Marine Biogeochemical Cycles: Lotka Revisited

    NASA Astrophysics Data System (ADS)

    Vallino, Joseph J.; Algar, Christopher K.

    2016-01-01

    Nearly 100 years ago, Alfred Lotka published two short but insightful papers describing how ecosystems may organize. Principally, Lotka argued that ecosystems will grow in size and that their cycles will spin faster via predation and nutrient recycling so as to capture all available energy, and that evolution and natural selection are the mechanisms by which this occurs and progresses. Lotka's ideas have often been associated with the maximum power principle, but they are more consistent with recent developments in nonequilibrium thermodynamics, which assert that complex systems will organize toward maximum entropy production (MEP). In this review, we explore Lotka's hypothesis within the context of the MEP principle, as well as how this principle can be used to improve marine biogeochemistry models. We need to develop the equivalent of a climate model, as opposed to a weather model, to understand marine biogeochemistry on longer timescales, and adoption of the MEP principle can help create such models.

  8. Enthalpy-Entropy Compensation (EEC) Effect: A Revisit.

    PubMed

    Pan, Animesh; Biswas, Tapas; Rakshit, Animesh K; Moulik, Satya P

    2015-12-31

    A short account of the developments and perspectives of IKR (iso-kinetic relation) and EEC (enthalpy (H) - entropy (S) compensation) has been presented. The IKR and EEC are known to be extra thermodynamic or empirical correlations though linear H-S correlation can be thermodynamically deduced. Attempt has also been made to explain the phenomena in terms of statistical thermodynamics. In this study, we have briefly revisited the fundamentals of both IKR and EEC from kinetic and thermodynamic grounds. A detailed revisit of the EEC phenomenon on varied kinetic and equilibrium processes has been also presented. Possible correlations among the free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) changes of different similar and nonsimilar chemical processes under varied conditions have been discussed with possible future projections. PMID:26641279

  9. Finite size effect on classical ideal gas revisited

    NASA Astrophysics Data System (ADS)

    Ghosh, P.; Ghosh, S.; Mitra, J.; Bera, N.

    2015-09-01

    Finite size effects on classical ideal gas are revisited. The micro-canonical partition function for a collection of ideal particles confined in a box is evaluated using Euler-Maclaurin’s as well as Poisson's summation formula. In Poisson's summation formula there are some exponential terms which are absent in Euler-Maclaurin’s formula. In the thermodynamic limit the exponential correction is negligibly small but in the macro/nano dimensions and at low temperatures they may have a great significance. The consequences of finite size effects have been illustrated by redoing the calculations in one and three dimensions keeping the exponential corrections. Global and local thermodynamic properties, diffusion driven by the finite size effect, and effect on speed of sound have been discussed. Thermo-size effects, similar to thermoelectric effects, have been described in detail and may be a theoretical basis with which to design nano-scaled devices. This paper can also be very helpful for undergraduate and graduate students in physics and chemistry as an instructive exercise for a good course in statistical mechanics.

  10. Thermodynamic effects on developed cavitation

    NASA Technical Reports Server (NTRS)

    Holl, J. W.; Billet, M. L.; Weir, D. S.

    1975-01-01

    The results of an investigation of thermodynamic effects are presented. Distributions of temperature and pressure in a developed cavity were measured for zero- and quarter-caliber ogives. A semiempirical entrainment theory was developed to correlate the measured temperature depression in the cavity. This theory correlates the maximum temperature depression expressed in dimensionless form as the Jakob number in terms of the dimensionless numbers of Nusselt, Reynolds, Froude, and Peclet, and dimensionless cavity length, L/D. The results show that in general, the temperature depression increases with L/D and temperature and the cavitation number based on measured cavity pressure is a function of L/D for a given model contour, independent of the thermodynamic effect.

  11. Fractional quantum Hall effect revisited

    NASA Astrophysics Data System (ADS)

    Jacak, J.; Łydżba, P.; Jacak, L.

    2015-10-01

    The topology-based explanation of the fractional quantum Hall effect (FQHE) is summarized. The cyclotron braid subgroups crucial for this approach are introduced in order to identify the origin of the Laughlin correlations in 2D (two-dimensional) Hall systems. Flux-tubes and vortices for composite fermions in their standard constructions are explained in terms of cyclotron braids. The derivation of the hierarchy of the FQHE is proposed by mapping onto the integer effect within the topology-based approach. The experimental observations of the FQHE supporting the cyclotron braid picture are reviewed with a special attention paid to recent experiments with a suspended graphene. The triggering role of a carrier mobility for organization of the fractional state in Hall configuration is emphasized. The prerequisites for the FQHE are indicated including topological conditions substantially increasing the previously accepted set of physical necessities. The explanation of numerical studies by exact diagonalizations of the fractional Chern insulator states is formulated in terms of the topology condition applied to the Berry field flux quantization. Some new ideas withz regard to the synthetic fractional states in the optical lattices are also formulated.

  12. Targeting Cancer Metabolism - Revisiting the Warburg Effects

    PubMed Central

    Tran, Quangdon; Lee, Hyunji; Park, Jisoo; Kim, Seon-Hwan; Park, Jongsun

    2016-01-01

    After more than half of century since the Warburg effect was described, this atypical metabolism has been standing true for almost every type of cancer, exhibiting higher glycolysis and lactate metabolism and defective mitochondrial ATP production. This phenomenon had attracted many scientists to the problem of elucidating the mechanism of, and reason for, this effect. Several models based on oncogenic studies have been proposed, such as the accumulation of mitochondrial gene mutations, the switch from oxidative phosphorylation respiration to glycolysis, the enhancement of lactate metabolism, and the alteration of glycolytic genes. Whether the Warburg phenomenon is the consequence of genetic dysregulation in cancer or the cause of cancer remains unknown. Moreover, the exact reasons and physiological values of this peculiar metabolism in cancer remain unclear. Although there are some pharmacological compounds, such as 2-deoxy-D-glucose, dichloroacetic acid, and 3-bromopyruvate, therapeutic strategies, including diet, have been developed based on targeting the Warburg effect. In this review, we will revisit the Warburg effect to determine how much scientists currently understand about this phenomenon and how we can treat the cancer based on targeting metabolism. PMID:27437085

  13. Targeting Cancer Metabolism - Revisiting the Warburg Effects.

    PubMed

    Tran, Quangdon; Lee, Hyunji; Park, Jisoo; Kim, Seon-Hwan; Park, Jongsun

    2016-07-01

    After more than half of century since the Warburg effect was described, this atypical metabolism has been standing true for almost every type of cancer, exhibiting higher glycolysis and lactate metabolism and defective mitochondrial ATP production. This phenomenon had attracted many scientists to the problem of elucidating the mechanism of, and reason for, this effect. Several models based on oncogenic studies have been proposed, such as the accumulation of mitochondrial gene mutations, the switch from oxidative phosphorylation respiration to glycolysis, the enhancement of lactate metabolism, and the alteration of glycolytic genes. Whether the Warburg phenomenon is the consequence of genetic dysregulation in cancer or the cause of cancer remains unknown. Moreover, the exact reasons and physiological values of this peculiar metabolism in cancer remain unclear. Although there are some pharmacological compounds, such as 2-deoxy-D-glucose, dichloroacetic acid, and 3-bromopyruvate, therapeutic strategies, including diet, have been developed based on targeting the Warburg effect. In this review, we will revisit the Warburg effect to determine how much scientists currently understand about this phenomenon and how we can treat the cancer based on targeting metabolism. PMID:27437085

  14. Revisiting the Trust Effect in Urban Elementary Schools

    ERIC Educational Resources Information Center

    Adams, Curt M.; Forsyth, Patrick B.

    2013-01-01

    More than a decade after Goddard, Tschannen-Moran, and Hoy (2001) found that collective faculty trust in clients predicts student achievement in urban elementary schools, we sought to identify a plausible link for this relationship. Our purpose in revisiting the trust effect was twofold: (1) to test the main effect of collective faculty trust on…

  15. The Importance of Being a Complement: CED Effects Revisited

    ERIC Educational Resources Information Center

    Jurka, Johannes

    2010-01-01

    This dissertation revisits subject island effects (Ross 1967, Chomsky 1973) cross-linguistically. Controlled acceptability judgment studies in German, English, Japanese and Serbian show that extraction out of specifiers is consistently degraded compared to extraction out of complements, indicating that the Condition on Extraction domains (CED,…

  16. Revisiting the Role of Organizational Effectiveness in Educational Evaluation.

    ERIC Educational Resources Information Center

    Lotto, Linda S.

    Organizational effectiveness ought to play a role in educational evaluation, and the development of alternative perspectives for viewing organizations could be a starting point for revisiting organizational evaluation in education. Five possible perspectives and criteria for evaluating organizations have been developed. If an organization is…

  17. Thermodynamic properties of wadsleyite with anharmonic effect

    NASA Astrophysics Data System (ADS)

    Wu, Zhongqing

    2015-02-01

    The thermodynamic properties of crystals can be routinely calculated by density functional theory calculations combining with quasi-harmonic approximation. Based on the method developed recently by Wu and Wentzcovitch (Phys Rev B 79:104304, 2009) and Wu (Phys Rev B 81:172301, 2010), we are able to further ab initio include anharmonic effect on thermodynamic properties of crystals by one additional canonical ensemble with numbers of particle, volume and temperature fixed (NVT) molecular dynamic simulations. Our study indicates that phonon-phonon interaction causes the renormalized phonon frequencies of wadsleyite decrease with temperature. This is consistent with the Raman experimental observation. The anharmonic free energy of wadsleyite is negative and its heat capacity at constant pressure can exceed the Dulong-Petit limit at high temperature. The anharmonicity still significantly affects thermodynamic properties of wadsleyite at pressure and temperature conditions correspond to the transition zone.

  18. Strictly two-dimensional self-avoiding walks: thermodynamic properties revisited.

    PubMed

    Schulmann, N; Xu, H; Meyer, H; Polińska, P; Baschnagel, J; Wittmer, J P

    2012-09-01

    The density crossover scaling of various thermodynamic properties of solutions and melts of self-avoiding and highly flexible polymer chains without chain intersections confined to strictly two dimensions is investigated by means of molecular dynamics and Monte Carlo simulations of a standard coarse-grained bead-spring model. In the semidilute regime we confirm over an order of magnitude of the monomer density ρ the expected power law scaling for the interaction energy between different chains e(int) ~ ρ(21/8), the total pressure P ~ ρ(3) and the dimensionless compressibility g(T) = lim(q→0)S(q) ~ 1/ρ(2). Various elastic contributions associated to the affine and non-affine response to an infinitesimal strain are analyzed as functions of density and sampling time. We show how the size ξ(ρ) of the semidilute blob may be determined experimentally from the total monomer structure factor S(q) characterizing the compressibility of the solution at a given wave vector q. We comment briefly on finite persistence length effects. PMID:23015277

  19. Revisiting the thermodynamic modelling of type I gas-hydroquinone clathrates.

    PubMed

    Conde, M M; Torré, J P; Miqueu, C

    2016-04-21

    Under specific pressure and temperature conditions, certain gaseous species can be engaged in a host lattice of hydroquinone molecules, forming a supramolecular entity called a gas hydroquinone clathrate. This study is devoted to the thermodynamic modelling of type I hydroquinone clathrates. The gases considered in this work are argon, krypton, xenon, methane, nitrogen, oxygen and hydrogen sulphide. The basic van der Waals and Platteeuw model, which is, for example, not able to predict well the phase equilibrium properties of such clathrates at high temperature, is modified and extended by considering first the solubility of the guest in solid HQ and then the mutual interactions between the gaseous molecules inside the clathrate structure (i.e. guest-guest interactions). Other improvements of the basic theory, such as the choice of the reference state, are proposed, and a unique set of thermodynamic parameters valid for all the studied guests are finally calculated. Very good agreement is obtained between the model predictions and the experimental data available in the literature. Our results clearly demonstrate that the highest level of theory is necessary to describe well both the triphasic equilibrium line (where the HQ clathrate, the native hydroquinone HQα and the gas coexist), the occupancy of the guest in the clathrate, and the intercalation enthalpy. PMID:27004460

  20. The Ti-Mn system revisited: experimental investigation and thermodynamic modelling.

    PubMed

    Khan, A U; Brož, P; Premović, M; Pavlů, J; Vřeštál, J; Yan, X; Maccio, D; Saccone, A; Giester, G; Rogl, P

    2016-08-17

    As the Ti-Mn phase diagram is part of numerous ternary and higher order systems of technological importance, the present paper defines phase relations which have been experimentally established throughout this work from 800 °C to the melting range based on Differential Thermal Analyses (DTA), X-ray powder diffraction, metallography and Electron Probe Micro Analysis (EPMA) techniques on ∼50 alloys, which were prepared by arc melting or high frequency melting under high purity argon starting from freshly cleaned metal ingots. Novel compounds were identified and reaction isotherms were redefined accordingly. In the Ti-rich region a novel compound TiMn was detected, sandwiched between the known phases: TiMn1-x (∼45 at% Mn) and TiMn1+x (∼55 at% Mn). In the Mn-rich region the hitherto unknown crystal structure of TiMn∼3 was solved from X-ray single crystal diffraction data and found to be of a unique structure type Ti6(Ti1-xMnx)6Mn25 (x = 0.462; space group Pbam (#55); a = 0.79081(3) nm, b = 2.58557(9) nm, c = 0.47931(2) nm), which consists of two consecutive layers of the hexagonal MgZn2-type Laves phase (TiMn2) and a combined layer of alternate structure blocks of MgZn2 type and Zr4Al3 type. Whereas TiMn can be considered as a line compound (solubility range <∼1 at%), the homogeneity regions of the Ti-Mn compounds are significant (determined by EPMA): TiMn1-x (44.0 to 46.6 at% Mn), TiMn1+x (54.6 to 56.3 at% Mn), Ti1+xMn2-x (MgZn2-type, 59 to 69 at% Mn at 1000 °C: -0.08 < x < 0.23), TiMn∼3 (unique type; 74 to 76.5 at% Mn) and TiMn∼4 (R-phase: Ti8(TixMn1-x)6Mn39, 80 to 84 at% Ti). Supported by ab initio calculations of the ground state energy for the Laves phase, the new experimental results enabled thermodynamic modelling of the entire Ti-Mn phase diagram providing a complete and novel set of thermodynamic data thus providing a sound basis for future thermodynamic predictions of higher order Ti-Mn-X-Y systems. PMID:27498605

  1. Thermodynamic theory of the plasmoelectric effect

    PubMed Central

    van de Groep, Jorik; Sheldon, Matthew T.; Atwater, Harry A.; Polman, Albert

    2016-01-01

    Resonant metal nanostructures exhibit an optically induced electrostatic potential when illuminated with monochromatic light under off-resonant conditions. This plasmoelectric effect is thermodynamically driven by the increase in entropy that occurs when the plasmonic structure aligns its resonant absorption spectrum with incident illumination by varying charge density. As a result, the elevated steady-state temperature of the nanostructure induced by plasmonic absorption is further increased by a small amount. Here, we study in detail the thermodynamic theory underlying the plasmoelectric effect by analyzing a simplified model system consisting of a single silver nanoparticle. We find that surface potentials as large as 473 mV are induced under 100 W/m2 monochromatic illumination, as a result of a 11 mK increases in the steady-state temperature of the nanoparticle. Furthermore, we discuss the applicability of this analysis for realistic experimental geometries, and show that this effect is generic for optical structures in which the resonance is linked to the charge density. PMID:26987904

  2. Thermodynamic theory of the plasmoelectric effect

    DOE PAGESBeta

    van de Groep, Jorik; Sheldon, Matthew T.; Atwater, Harry A.; Polman, Albert

    2016-03-18

    Resonant metal nanostructures exhibit an optically induced electrostatic potential when illuminated with monochromatic light under off-resonant conditions. This plasmoelectric effect is thermodynamically driven by the increase in entropy that occurs when the plasmonic structure aligns its resonant absorption spectrum with incident illumination by varying charge density. As a result, the elevated steady-state temperature of the nanostructure induced by plasmonic absorption is further increased by a small amount. Here, we study in detail the thermodynamic theory underlying the plasmoelectric effect by analyzing a simplified model system consisting of a single silver nanoparticle. We find that surface potentials as large as 473more » mV are induced under 100 W/m2 monochromatic illumination, as a result of a 11 mK increases in the steady-state temperature of the nanoparticle. Hence, we discuss the applicability of this analysis for realistic experimental geometries, and show that this effect is generic for optical structures in which the resonance is linked to the charge density.« less

  3. Thermodynamics of silicon nitridation - Effect of hydrogen

    NASA Technical Reports Server (NTRS)

    Shaw, N. J.; Zeleznik, F. J.

    1982-01-01

    Equilibrium compositions for the nitridization of Si were calculated to detect the effectiveness of H2 in removal of the oxide film and in increasing the concentration of SiO and reducing the proportions of O2. Gibbs free energy for the formation of SiN2O was computed above 1685 K, and at lower temperatures. The thermodynamic properties of SiN2O2 were then considered from 1000-3000 K, taking into account the known thermodynamic data for 39 molecular combinations of the Si, Ni, and O. The gases formed were assumed ideal mixtures with pure phase condensed species. The mole fractions were obtained for a system of SiO2 with each Si particle covered with a thin layer of SiO2 before nitridation, and a system in which the nitriding atmosphere had access to the Si. The presence of H2 was determined to enhance the removal of NiO2 in the first system, decrease the partial pressure of O2, increase the partial pressures of SiO, Si, H2O, NH3, and SiH4, while its effects were negligible in the Si system.

  4. Dissipation effects in mechanics and thermodynamics

    NASA Astrophysics Data System (ADS)

    Güémez, J.; Fiolhais, M.

    2016-07-01

    With the discussion of three examples, we aim at clarifying the concept of energy transfer associated with dissipation in mechanics and in thermodynamics. The dissipation effects due to dissipative forces, such as the friction force between solids or the drag force in motions in fluids, lead to an internal energy increase of the system and/or to heat transfer to the surroundings. This heat flow is consistent with the second law, which states that the entropy of the universe should increase when those forces are present because of the irreversibility always associated with their actions. As far as mechanics is concerned, the effects of the dissipative forces are included in Newton’s equations as impulses and pseudo-works.

  5. Effects of Thermodynamic Properties on Slab Evolution

    NASA Astrophysics Data System (ADS)

    Wada, I.; King, S. D.; Caddick, M. J.; Ross, N.

    2012-12-01

    We perform a series of numerical experiments to investigate the effects of thermodynamic properties on the geometrical evolution of subducting slabs. We calculate density (ρ), thermal expansivity (α), and heat capacity (cp) of mantle mineral assemblages of a harzburgite composition over a range of pressure and temperature conditions applicable to the Earth's mantle, using the thermodynamic database of Stixrude and Lithgow-Bertelloni [2011] and the thermodynamic calculation code Perple_X [Connolly, 2009]. Following Nakagawa et al. [2009], we assume that thermal diffusivity (κ) follows a power-law relationship with density (κ=κ0(ρ/ρ0)3, where κ0 and ρ0 are reference diffusivity and density, respectively). The calculations show that ρ, α, and κ change significantly along mantle geotherms; the ranges of their values are 3300-5100 km/m3, 1.5-3.5 10-5/K, and 3-17 W/m K, respectively. The change in cp is small (< 5%). We incorporate the pressure and temperature (PT) dependence of these thermodynamic properties into a 2-D finite element code with compressible convection formulations under the truncated anelastic liquid approximation [Lee and King, 2009] and develop a dynamic subduction model with kinematic boundary conditions. In the model, we use a composite mantle rheology that accounts for both diffusion and dislocation creep with flow law parameterization of wet olivine [Hirth and Kohlstedt, 2003]. Following Billen and Hirth [2007] and Lee and King [2011], we adjust the flow law parameter values for the lower mantle to test the effects of viscosity contrast between the upper and lower mantle on slab evolution. We use a reference model with a constant ρ, κ α, and cp, which is equivalent to using the incompressible extended Bousisnesq approximation. Preliminary results show that incorporating PT-dependent ρ enhances the vigor of the buoyancy driven flow compared to the reference model. Further, lithostatic pressure at a given depth is higher than in the

  6. Thermodynamical effects during carbon dioxide release

    NASA Astrophysics Data System (ADS)

    Singh, A. K.; Böttcher, N.; Görke, U.-J.; Kolditz, O.

    2012-04-01

    Pruess [1] investigated the risk of carbon dioxide leakage from shallow storage sites by modeling scenarios. Such a fluid release is associated with mechanical work performed by formation fluid against expansion without taking heat from ambient environment. Understanding of heat related to mechanical work is essential to predict the temperature at the leak. According to the first law of thermodynamics, internal energy of working fluid decreases with an amount which is equivalent to this work hence, working fluid lost its own heat. Such kind of heat loss depends strongly on whether the expansion process is adiabatic or isothermal. Isothermal expansion allows the working fluid to interact thermally with the solid matrix. Adiabatic expansion is an isenthalpic process that takes heat from the working fluid and the ambient environment remains unchanged. This work is part of the CLEAN research project [6]. In this study, thermodynamic effects of mechanical work during eventual carbon dioxide leakage are investigated numerically. In particular, we are interested to detect the temperature at leakage scenarios and its deviation with different thermodynamic processes. Finite element simulation is conducted with a two-dimensional rectangular geometry representing a shallow storage site which bottom was located at -300m below the land surface. A fully saturated porous medium is assumed where the pore space is filled completely with carbon dioxide. Carbon dioxide accumulated in the secondary trap at 30 Bar and 24 °C is allowed to leak from top right point of rectangle with atmospheric pressure. With (i) adiabatic and (ii) isothermal compressibility factors, temperature around leakage area has been calculated which show a significant difference. With some simplification, this study detects leak temperature which is very close with [1]. Temporal evaluation at the leaky area shows that the working fluid temperature can be reduced to -20 °C when the leakage scenario is performed

  7. Revisiting the Scattering Greenhouse Effect of CO2 Ice Clouds

    NASA Astrophysics Data System (ADS)

    Kitzmann, D.

    2016-02-01

    Carbon dioxide ice clouds are thought to play an important role for cold terrestrial planets with thick CO2 dominated atmospheres. Various previous studies showed that a scattering greenhouse effect by carbon dioxide ice clouds could result in a massive warming of the planetary surface. However, all of these studies only employed simplified two-stream radiative transfer schemes to describe the anisotropic scattering. Using accurate radiative transfer models with a general discrete ordinate method, this study revisits this important effect and shows that the positive climatic impact of carbon dioxide clouds was strongly overestimated in the past. The revised scattering greenhouse effect can have important implications for the early Mars, but also for planets like the early Earth or the position of the outer boundary of the habitable zone.

  8. Effects of quintessence on thermodynamics of the black holes

    NASA Astrophysics Data System (ADS)

    Ghaderi, K.; Malakolkalami, B.

    2016-05-01

    In this letter, we investigate the effects of quintessence on thermodynamics of the Bardeen black hole and compare them with the results of our former paper. Black hole thermodynamic stability can be determined by studying the nature of heat capacity of the system. We use the first-law of thermodynamics to derive the thermodynamic quantities of these black holes and we compare and analyse the results. We plot the variation of mass, temperature and heat capacity as a functions of entropy related to the quintessence. Finally, we study the equation of state of these black holes with quintessence.

  9. Improved effective vector boson approximation revisited

    NASA Astrophysics Data System (ADS)

    Bernreuther, Werner; Chen, Long

    2016-03-01

    We reexamine the improved effective vector boson approximation which is based on two-vector-boson luminosities Lpol for the computation of weak gauge-boson hard scattering subprocesses V1V2→W in high-energy hadron-hadron or e-e+ collisions. We calculate these luminosities for the nine combinations of the transverse and longitudinal polarizations of V1 and V2 in the unitary and axial gauge. For these two gauge choices the quality of this approach is investigated for the reactions e-e+→W-W+νeν¯ e and e-e+→t t ¯ νeν¯ e using appropriate phase-space cuts.

  10. Thermodynamic Losses in Multi-effect Distillation Process

    NASA Astrophysics Data System (ADS)

    Shen, S.

    2015-09-01

    The multi-effect distillation (MED) is one of desalination technologies. It is also applied in chemical engineering and other industries for evaporation, distillation, crystallization, etc. In a large multi-effect distillation plant, some tiny thermodynamic losses might have a great influence to the performance and design parameters. For the detailed analysis and design of a MED desalination plant, a series of experiments were carried out. The thermodynamic losses in a MED desalination plant is analyzed as an example to show its effect on the performance and structure parameters. The thermodynamics losses have a cumulative effect. With the increase of effect number and the concentration ratio, the thermodynamic losses shall be a dominant factor for the operation performance of a MED plant.

  11. SUSY effects in Rb: Revisited under current experimental constraints

    NASA Astrophysics Data System (ADS)

    Su, Wei; Yang, Jin Min

    2016-06-01

    In this note we revisit the SUSY effects in Rb under current experimental constraints including the LHC Higgs data, the B-physics measurements, the dark matter relic density and direct detection limits, as well as the precision electroweak data. We first perform a scan to figure out the currently allowed parameter space and then display the SUSY effects in Rb. We find that although the SUSY parameter space has been severely restrained by current experimental data, both the general MSSM and the natural-SUSY scenario can still alter Rb with a magnitude sizable enough to be observed at future Z-factories (ILC, CEPC, FCC-ee, Super Z-factory) which produce 109-1012Z-bosons. To be specific, assuming a precise measurement δRb = 2.0 ×10-5 at FCC-ee, we can probe a right-handed stop up to 530 GeV through chargino-stop loops, probe a sbottom to 850 GeV through neutralino-sbottom loops and a charged Higgs to 770 GeV through the Higgs-top quark loops for a large tan ⁡ β. The full one-loop SUSY correction to Rb can reach 1 ×10-4 in natural SUSY and 2 ×10-4 in the general MSSM.

  12. Dynamical Casimir effect and minimal temperature in quantum thermodynamics

    NASA Astrophysics Data System (ADS)

    Benenti, Giuliano; Strini, Giuliano

    2015-02-01

    We study the fundamental limitations of cooling to absolute zero for a qubit, interacting with a single mode of the electromagnetic field. Our results show that the dynamical Casimir effect, which is unavoidable in any finite-time thermodynamic cycle, forbids the attainability of the absolute zero of temperature, even in the limit of an infinite number of cycles.

  13. The Peter Effect Revisited: Reading Habits and Attitudes of College Students

    ERIC Educational Resources Information Center

    Applegate, Anthony J.; Applegate, Mary DeKonty; Mercantini, Martha A.; McGeehan, Catherine M.; Cobb, Jeanne B.; DeBoy, Joanne R.; Modla, Virginia B.; Lewinski, Kimberly E.

    2014-01-01

    Certainly a primary goal of literacy education is the creation of avid, enthusiastic, and highly motivated readers. However, in this article revisiting the Peter Effect (Applegate & Applegate, 2004), researchers surveyed more than 1,000 college sophomores and found strikingly low levels of enthusiasm for reading. Only 46.6% of surveyed…

  14. Missing Data and Mixed Results: The Effects of Teach For America on Student Achievement Revisited

    ERIC Educational Resources Information Center

    Penner, Emily K.

    2013-01-01

    This paper revisits existing experimental work on Teach For America (TFA) and extends it by examining treatment effects across the distribution of student achievement. TFA is a rapidly expanding teacher preparation program that currently serves over half a million students in low-income districts across the country. Previous research results did…

  15. Quantum gravity effects on charged microblack holes thermodynamics

    NASA Astrophysics Data System (ADS)

    Abbasvandi, Niloofar; Soleimani, M. J.; Radiman, Shahidan; Wan Abdullah, W. A. T.

    2016-08-01

    The charged black hole thermodynamics is corrected in terms of the quantum gravity effects. Most of the quantum gravity theories support the idea that near the Planck scale, the standard Heisenberg uncertainty principle should be reformulated by the so-called Generalized Uncertainty Principle (GUP) which provides a perturbation framework to perform required modifications of the black hole quantities. In this paper, we consider the effects of the minimal length and maximal momentum as GUP type I and the minimal length, minimal momentum and maximal momentum as GUP type II on thermo dynamics of the charged TeV-scale black holes. We also generalized our study to the universe with the extra dimensions based on the ADD model. In this framework, the effect of the electrical charge on thermodynamics of the black hole and existence of the charged black hole remnants as a potential candidate for the dark matter particles are discussed.

  16. Correlations of thermodynamic effects for developed cavitation

    NASA Technical Reports Server (NTRS)

    Billet, M. L.; Holl, J. W.; Weir, D. S.

    1978-01-01

    The net positive suction head (NPSH) requirements for a pump are determined by the combined effects of cavitation, fluid properties, pump geometry, and pump operating point. An important part of this determination is the temperature depression (Delta T). Correlations are presented of the temperature depression for various degrees of developed cavitation on venturis and ogives. These correlations, based on a semi-empirical entrainment theory, express Delta T in terms of the dimensionless numbers of Nusselt, Reynolds, Froude, Weber, and Peclet, and dimensionless cavity length (L/D). The Delta T data were obtained in Freon 114, hydrogen and nitrogen for the venturis and in Freon 113 and water for the ogives.

  17. Surface Emissivity Effects on Thermodynamic Retrieval of IR Spectral Radiance

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Larar, Allen M.; Smith, William L.; Liu, Xu

    2006-01-01

    The surface emissivity effect on the thermodynamic parameters (e.g., the surface skin temperature, atmospheric temperature, and moisture) retrieved from satellite infrared (IR) spectral radiance is studied. Simulation analysis demonstrates that surface emissivity plays an important role in retrieval of surface skin temperature and terrestrial boundary layer (TBL) moisture. NAST-I ultraspectral data collected during the CLAMS field campaign are used to retrieve thermodynamic properties of the atmosphere and surface. The retrievals are then validated by coincident in-situ measurements, such as sea surface temperature, radiosonde temperature and moisture profiles. Retrieved surface emissivity is also validated by that computed from the observed radiance and calculated emissions based on the retrievals of surface temperature and atmospheric profiles. In addition, retrieved surface skin temperature and emissivity are validated together by radiance comparison between the observation and retrieval-based calculation in the window region where atmospheric contribution is minimized. Both simulation and validation results have lead to the conclusion that variable surface emissivity in the inversion process is needed to obtain accurate retrievals from satellite IR spectral radiance measurements. Retrieval examples are presented to reveal that surface emissivity plays a significant role in retrieving accurate surface skin temperature and TBL thermodynamic parameters.

  18. Experimental studies on thermodynamic effects of developed cavitation

    NASA Technical Reports Server (NTRS)

    Ruggeri, R. S.

    1974-01-01

    A method for predicting thermodynamic effects of cavitation (changes in cavity pressure relative to stream vapor pressure) is presented. The prediction method accounts for changes in liquid, liquid temperature, flow velocity, and body scale. Both theoretical and experimental studies used in formulating the method are discussed. The prediction method provided good agreement between predicted and experimental results for geometrically scaled venturis handling four different liquids of widely diverse physical properties. Use of the method requires geometric similarity of the body and cavitated region and a known reference cavity-pressure depression at one operating condition.

  19. Microscopic Foundations of the MEIßNER Effect: Thermodynamic Aspects

    NASA Astrophysics Data System (ADS)

    Bru, J.-B.; de Siqueira Pedra, W.

    2013-08-01

    We analyze the Meißner effect from first principles of quantum mechanics. We show in particular the existence of superconducting states minimizing the magnetic free-energy of BCS-like models and carrying surface currents which annihilate the total magnetic induction inside the bulk in the thermodynamic limit. This study is a step towards a complete explanation of the Meißner effect from microscopic models. It remains indeed to prove that those states are dynamically stable, i.e. quasi-stationary at low temperatures. Note that our analysis shows that the Meißner effect is not necessarily related to an effective magnetic susceptibility equal to -1.

  20. Local thermodynamic mapping for effective liquid density-functional theory

    NASA Technical Reports Server (NTRS)

    Kyrlidis, Agathagelos; Brown, Robert A.

    1992-01-01

    The structural-mapping approximation introduced by Lutsko and Baus (1990) in the generalized effective-liquid approximation is extended to include a local thermodynamic mapping based on a spatially dependent effective density for approximating the solid phase in terms of the uniform liquid. This latter approximation, called the local generalized effective-liquid approximation (LGELA) yields excellent predictions for the free energy of hard-sphere solids and for the conditions of coexistence of a hard-sphere fcc solid with a liquid. Moreover, the predicted free energy remains single valued for calculations with more loosely packed crystalline structures, such as the diamond lattice. The spatial dependence of the weighted density makes the LGELA useful in the study of inhomogeneous solids.

  1. Nonequilibrium thermodynamics of the spin Seebeck and spin Peltier effects

    NASA Astrophysics Data System (ADS)

    Basso, Vittorio; Ferraro, Elena; Magni, Alessandro; Sola, Alessandro; Kuepferling, Michaela; Pasquale, Massimo

    2016-05-01

    We study the problem of magnetization and heat currents and their associated thermodynamic forces in a magnetic system by focusing on the magnetization transport in ferromagnetic insulators like YIG. The resulting theory is applied to the longitudinal spin Seebeck and spin Peltier effects. By focusing on the specific geometry with one Y3Fe5O12 (YIG) layer and one Pt layer, we obtain the optimal conditions for generating large magnetization currents into Pt or large temperature effects in YIG. The theoretical predictions are compared with experiments from the literature permitting to derive the values of the thermomagnetic coefficients of YIG: the magnetization diffusion length lM˜0.4 μ m and the absolute thermomagnetic power coefficient ɛM˜10-2TK-1 .

  2. Comments to Irreversibility in Thermodynamics

    NASA Technical Reports Server (NTRS)

    Zak, M.

    1995-01-01

    The problem of irreversibility in thermodynamics was revisited and analyzed on the microscopic, stochastic, and macroscopic levels of description. It was demonstrated that Newtonian dynamics can be represented in the Reynolds form, a new phenomenological force with non-Lipschitz properties was introduced, and additional non- Lipschitz thermodynamical forces were incorporated into macroscopic models of transport phenomena.

  3. The effects of the size of nanocrystalline materials on their thermodynamic and mechanical properties

    PubMed Central

    2014-01-01

    This work has considered the intrinsic influence of bond energy on the macroscopic, thermodynamic, and mechanical properties of crystalline materials. A general criterion is proposed to evaluate the properties of nanocrystalline materials. The interrelation between the thermodynamic and mechanical properties of nanomaterials is presented and the relationship between the variation of these properties and the size of the nanomaterials is explained. The results of our work agree well with thermodynamics, molecular dynamics simulations, and experimental results. This method is of significance in investigating the size effects of nanomaterials and provides a new approach for studying their thermodynamic and mechanical properties. PMID:25288913

  4. Effect of nanoparticle size on the thermal decomposition thermodynamics in theory and experiment

    NASA Astrophysics Data System (ADS)

    Li, Wenjiao; Cui, Zixiang; Duan, Huijuan; Xue, Yongqiang

    2016-02-01

    Thermal decomposition reactions of nanoparticles are often concerned in the processes of preparation and application of nanomaterials. However, it is the nanoparticle size that leads to great difference in thermal decomposition thermodynamics between nanoparticles and corresponding bulk substances. In this paper, the decomposition model of a nanoparticle was established to investigate the theoretical size-dependent thermodynamics in nanoscale decomposition system, and the theoretical relations of the thermodynamic properties with particle size were, respectively, derived. In experiment, the decomposition thermodynamics of nanosized zinc carbonate particles was studied, and the influence regularities of particle size on thermodynamic quantities were obtained. The experimental results are in accordance with the corresponding theoretical thermodynamic relations. These results show that there is a striking effect of particle size on the decomposition thermodynamics. The thermodynamic properties decrease with the decrease of particle size, whereas the equilibrium constant and the molar heat capacity of reaction at constant volume increase; logarithm of the equilibrium constant, the heat capacity of reaction and the thermodynamic properties are linearly related to reciprocal of the particle diameter, respectively. In addition, the temperature coefficient of the heat capacity of reaction also has strong size dependence; that is, the temperature coefficient becomes smaller with the particle size decreasing.

  5. Side-effects of topical steroids: A long overdue revisit

    PubMed Central

    Coondoo, Arijit; Phiske, Meghana; Verma, Shyam; Lahiri, Koushik

    2014-01-01

    The introduction of topical steroids (TS) of varying potency have rendered the therapy of inflammatory cutaneous disorders more effective and less time-consuming. However the usefulness of these has become a double edged sword with constantly rising instances of abuse and misuse leading to serious local, systemic and psychological side effects. These side effects occur more with TS of higher potency and on particular areas of the body like face and genitalia. The article reviews the side effects of TS with special mention about peadiatric age group, also includes the measures for preventing the side effects. PMID:25396122

  6. The Use of Theory in School Effectiveness Research Revisited

    ERIC Educational Resources Information Center

    Scheerens, Jaap

    2013-01-01

    From an international review of 109 school effectiveness research studies, only 6 could be seen as theory driven. As the border between substantive conceptual models of educational effectiveness and theory-based models is not always very sharp, this number might be increased to 11 by including those studies that are based on models that make…

  7. Revisit the Effect of Teaching and Learning with Technology

    ERIC Educational Resources Information Center

    Lee, Yuan-Hsuan; Waxman, Hersh; Wu, Jiun-Yu; Michko, Georgette; Lin, Grace

    2013-01-01

    We re-examined the effect of teaching and learning with technology on student cognitive and affective outcomes using the meta-analytic technique. Screening studies obtained from an electric search of databases such as PsyInfo and ERIC resulted in 58 studies (1997-2011). Overall, effect sizes were small to moderate across the cognitive and…

  8. Calcium revisited: part II calcium supplements and their effects

    PubMed Central

    Lamy, Olivier; Burckhardt, Peter

    2014-01-01

    Calcium supplements were tested in pregnancy and lactation, in childhood and adolescence, in pre- and postmenopausal women and in elderly persons with various effects on bone density and fracture incidence. They must be properly chosen and adequately used. In this case, the reported minor negative side-effects do not restrict their use. All these aspects are reviewed here. PMID:25328675

  9. Revisiting the Effect of Anthropomorphizing a Social Cause Campaign

    PubMed Central

    Williams, Lisa A.; Masser, Barbara; Sun, Jessie

    2015-01-01

    Recent research suggests that anthropomorphism can be harnessed as a tool to boost intentions to comply with social cause campaigns. Drawing on the human tendency to extend moral concern to entities portrayed as humanlike, it has been argued that adding personified features to a social campaign elevates anticipated guilt at failing to comply, and this subsequently boosts intentions to comply with that campaign. The present research aimed to extend extant research by disentangling the effects of emotional and non-emotional anthropomorphism, and differentiating amongst other emotional mechanisms of the anthropomorphism-compliance effect (namely, anticipated pride and anticipated regret). Experiment 1 (N = 294) compared the effectiveness of positive, negative, and emotionally-neutral anthropomorphized campaign posters for boosting campaign compliance intentions against non-anthropomorphized posters. We also measured potential mechanisms including anticipated guilt, regret, and pride. Results failed to support the anthropomorphism-compliance effect, and no changes in anticipated emotion according to anthropomorphism emerged. Experiments 2 (N = 150) and 3 (N = 196) represented further tests of the anthropomorphism-compliance effect. Despite high statistical power and efforts to closely replicate the conditions under which the anthropomorphism-compliance effect had been previously observed, no differences in compliance intention or anticipated emotion according to anthropomorphism emerged. A meta-analysis of the effects of anthropomorphism on compliance and anticipated emotion across the three experiments revealed effect size estimates that did not differ significantly from zero. The results of these three experiments suggest that the anthropomorphism-compliance effect is fragile and perhaps subject to contextual and idiographic influences. Thus, this research provides important insight and impetus for future research on the applied and theoretical utility of

  10. Relative age effect revisited: findings from the dance domain.

    PubMed

    van Rossum, Jacques H A

    2006-04-01

    The relative age effect is a worldwide phenomenon. While there is solid empirical evidence for the existence in sports like soccer and ice hockey, there are also some findings indicating the absence of the phenomenon. In an earlier study, no support was found with Dutch top-level athletes in table tennis and in volleyball. The explanation was that in athletic tasks which depend heavily on the technical ability (or motor skill) of the participant, a relative age effect will not be observed. In the present study this supposition was tested again with three samples of Dutch preprofessional dance students (overall number of subjects: 546). Again no support was obtained for the relative age effect. Therefore, a case is being built that the relative age effect is not an omnipresent phenomenon. PMID:16826648

  11. Biochemical reactions in crowded environments: Revisiting the effects of volume exclusion with simulations

    NASA Astrophysics Data System (ADS)

    Gomez, David; Klumpp, Stefan

    2015-06-01

    Molecular crowding is ubiquitous within cells and affects many biological processes including protein-protein binding, enzyme activities and gene regulation. Here we revisit some generic effects of crowding using a combination of lattice simulations and reaction-diffusion simulations with the program ReaDDy. Specifically, we implement three reactions, simple binding, a diffusion-limited reaction and a reaction with Michaelis-Menten kinetics. Histograms of binding and unbinding times provide a detailed picture how crowding affects these reactions and how the separate effects of crowding on binding equilibrium and on diffusion act together. In addition, we discuss how crowding affects processes related to gene expression such as RNA polymerase-promoter binding and translation elongation.

  12. The Stiles-Crawford effect: a theoretical revisit

    NASA Astrophysics Data System (ADS)

    McIntyre, P.; Pask, C.

    2013-02-01

    In 1973, Snyder and Pask published an explanation of the Stiles-Crawford effect based on optical-waveguide theory, but used only one set of experimental data for comparison. Since then there have been many new experiments and comments on the theory. In this paper we examine the assumptions made in the original theory, introduce some refinements, address some of the comments and examine how well the theory explains the experimental results obtained since 1973. We conclude that the waveguide theory, with some minor improvements, provides the theoretical basis for understanding the Stiles-Crawford effect.

  13. Revisiting E-Learning Effectiveness: Proposing a Conceptual Model

    ERIC Educational Resources Information Center

    Macgregor, George; Turner, James

    2009-01-01

    Purpose: The use of e-learning is largely predicated upon the assumption that it can facilitate improvements in student learning and therefore can be more effective than conventional techniques. This assumption has been supported by some in the literature but has been questioned by a continuing body of contrary or indifferent evidence. The purpose…

  14. Revisiting the Novelty Effect: When Familiarity, Not Novelty, Enhances Memory

    ERIC Educational Resources Information Center

    Poppenk, J.; Kohler, S.; Moscovitch, M.

    2010-01-01

    Reports of superior memory for novel relative to familiar material have figured prominently in recent theories of memory. However, such "novelty effects" are incongruous with long-standing observations that familiar items are remembered better. In 2 experiments, we explored whether this discrepancy was explained by differences in the type of…

  15. Second Language Comprehensibility Revisited: Investigating the Effects of Learner Background

    ERIC Educational Resources Information Center

    Crowther, Dustin; Trofimovich, Pavel; Saito, Kazuya; Isaacs, Talia

    2015-01-01

    The current study investigated first language (L1) effects on listener judgment of comprehensibility and accentedness in second language (L2) speech. The participants were 45 university-level adult speakers of English from three L1 backgrounds (Chinese, Hindi, Farsi), performing a picture narrative task. Ten native English listeners used…

  16. Terminology Revisited: Effective Communications for the Agricultural Community

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pasture-based finishing systems for meat goats, sheep and cattle are growing rapidly in the eastern USA, particularly on small farms. Increasing demand for pasture-raised meat and dairy products requires renewed efforts to communicate the best practical information as effectively as possible. Many...

  17. Revisiting the Lamotrigine-Mediated Effect on Hippocampal GABAergic Transmission

    PubMed Central

    Huang, Yu-Yin; Liu, Yu-Chao; Lee, Cheng-Ta; Lin, Yen-Chu; Wang, Mong-Lien; Yang, Yi-Ping; Chang, Kaung-Yi; Chiou, Shih-Hwa

    2016-01-01

    Lamotrigine (LTG) is generally considered as a voltage-gated sodium (Nav) channel blocker. However, recent studies suggest that LTG can also serve as a hyperpolarization-activated cyclic nucleotide-gated (HCN) channel enhancer and can increase the excitability of GABAergic interneurons (INs). Perisomatic inhibitory INs, predominantly fast-spiking basket cells (BCs), powerfully inhibit granule cells (GCs) in the hippocampal dentate gyrus. Notably, BCs express abundant Nav channels and HCN channels, both of which are able to support sustained action potential generation. Using whole-cell recording in rat hippocampal slices, we investigated the net LTG effect on BC output. We showed that bath application of LTG significantly decreased the amplitude of evoked compound inhibitory postsynaptic currents (IPSCs) in GCs. In contrast, simultaneous paired recordings from BCs to GCs showed that LTG had no effect on both the amplitude and the paired-pulse ratio of the unitary IPSCs, suggesting that LTG did not affect GABA release, though it suppressed cell excitability. In line with this, LTG decreased spontaneous IPSC (sIPSC) frequency, but not miniature IPSC frequency. When re-examining the LTG effect on GABAergic transmission in the cornus ammonis region 1 (CA1) area, we found that LTG markedly inhibits both the excitability of dendrite-targeting INs in the stratum oriens and the concurrent sIPSCs recorded on their targeting pyramidal cells (PCs) without significant hyperpolarization-activated current (Ih) enhancement. In summary, LTG has no effect on augmenting Ih in GABAergic INs and does not promote GABAergic inhibitory output. The antiepileptic effect of LTG is likely through Nav channel inhibition and the suppression of global neuronal network activity. PMID:27455251

  18. IRIS Mariner 9 Data Revisited. 1; An Instrumental Effect

    NASA Technical Reports Server (NTRS)

    Formisano, V.; Grassi, D.; Piccioni, G.; Pearl, John; Bjoraker, G.; Conrath, B.; Hanel, R.

    1999-01-01

    Small spurious features are present in data from the Mariner 9 Infrared Interferometer Spectrometer (IRIS). These represent a low amplitude replication of the spectrum with a doubled wavenumber scale. This replication arises principally from an internal reflection of the interferogram at the input window. An algorithm is provided to correct for the effect, which is at the 2% level. We believe that the small error in the uncorrected spectra does not materially affect previous results; however, it may be significant for some future studies at short wavelengths. The IRIS spectra are also affected by a coding error in the original calibration that results in only positive radiances. This reduces the effectiveness of averaging spectra to improve the signal to noise ratio at small signal levels.

  19. Revisiting the mitogenetic effect of ultra-weak photon emission

    PubMed Central

    Volodyaev, Ilya; Beloussov, Lev V.

    2015-01-01

    This paper reviews the 90 years long controversial history of the so-called “mitogenetic radiation,” the first case of non-chemical distant interactions, reported by Gurwitsch (1923). It was soon described as ultraweak UV, emitted by a number of biological systems, and stimulating mitosis in “competent” (in this sense) cells. In the following 20 years this phenomenon attracted enormous interest of the scientific community, and gave rise to more than 700 publications around the world. Yet, this wave of research vanished after several ostensibly disproving works in late 1930-s, and was not resumed later, regardless of quite serious grounds for that. The authors discuss separately two aspects of the problem: (1) do living organisms emit ultraweak radiation in the UV range (irrespective of whether it has any biological role), and (2) are there any real effects of this ultraweak photon emission (UPE) upon cell division and/or other biological functions? Analysis of the available data permits to conclude, that UV fraction of UPE should be regarded real, while its biological effects are difficult to reproduce. This causes a paradox. A number of presently known qualities of UPE were initially discovered (predicted?) by the “early workers” on the basis of biological effects. Yet the qualities they discovered were proved later (the UV component of UPE, the sources of UPE among biological systems, etc…), while the biological effect they used for UPE “detection” remains questionable. Importance of this area for basic biology and medicine, and potential usefulness of UPE as a non-invasive research method, invite scientists to attack this problem again, applying powerful research facilities of modern science. Yet, because of complexity and uncertainty of the problem, further progress in this area demands comprehensive examination of both positive and negative works, with particular attention to their methodical details. PMID:26441668

  20. The case of the Doppler effect for photons revisited

    NASA Astrophysics Data System (ADS)

    Redžić, Dragan V.

    2013-11-01

    A detailed account is presented of the Doppler effect as a photon phenomenon, complementing a recent paper by Giuliani (2013 Eur. J. Phys. 34 1035-47). The essence of Schrödinger's pioneering derivation (1922 Phys. Z. 23 301-3) of a Doppler formula in terms of the corpuscular theory of light, using energy-momentum conservation, is related. Some neglected references that put the whole scene around the Ives-Stilwell experiment into a more precise perspective are highlighted. Atoms as clocks and particle-wave complementarity are also discussed briefly.

  1. Revisiting the Effect of Nicotine on Interval Timing

    PubMed Central

    Daniels, Carter W.; Watterson, Elizabeth; Garcia, Raul; Mazur, Gabriel J.; Brackney, Ryan J.; Sanabria, Federico

    2015-01-01

    This paper reviews the evidence for nicotine-induced acceleration of the internal clock when timing in the seconds-to-minutes timescale, and proposes an alternative explanation to this evidence: that nicotine reduces the threshold for responses that result in more reinforcement. These two hypotheses were tested in male Wistar rats using a novel timing task. In this task, rats were trained to seek food at one location after 8 s since trial onset and at a different location after 16 s. Some rats received the same reward at both times (group SAME); some received a larger reward at 16 s (group DIFF). Steady baseline performance was followed by 3 days of subcutaneous nicotine administration (0.3 mg/kg), baseline recovery, and an antagonist challenge (mecamylamine, 1.0 mg/kg). Nicotine induced a larger, immediate reduction in latencies to switch (LTS) in group DIFF than in group SAME. This effect was sustained throughout nicotine administration. Mecamylamine administration and discontinuation of nicotine rapidly recovered baseline performance. These results support a response-threshold account of nicotinic disruption of timing performance, possibly mediated by nicotinic acetylcholine receptors. A detailed analysis of the distribution of LTSs suggests that anomalous effects of nicotine on LTS dispersion may be due to loss of temporal control of behavior. PMID:25637907

  2. Turbulence effects on hemolysis by revisiting experiments with LES computations

    NASA Astrophysics Data System (ADS)

    Ozturk, Mesude; O'Rear, Edgar; Papavassiliou, Dimitrios

    2015-11-01

    Determining mechanically stimulated red blood cell trauma as a function of turbulence properties is required to design prosthetic heart devices. Because blood is typically exposed to turbulence in such devices, the design of prosthetic heart devices depends on determining the effect of turbulent stresses on hemolysis. While turbulent stresses increase hemolysis when cells are exposed to them, turbulent flow characteristics in the vicinity of lysed blood cells, and the mechanism of cell damage remains uncertain. In this work, LES computations are used to investigate the effect of turbulent eddy structure on cell damage. The flow was simulated for classic Couette and capillary tube experiments, in order to examine the relation between hemolysis turbulence properties related to the dissipation of turbulent kinetic energy. The hypothesis tested is that eddies that are close in size with the erythrocytes are the ones that are responsible for hemolysis, rather than Reynolds stresses or viscous stresses. We define extensive measures, like the eddy areas for small eddies comparable to the size of the red blood cells, to provide a more general understanding of the mechanical cause of blood trauma.

  3. The Kaye effect revisited: High speed imaging of leaping shampoo

    NASA Astrophysics Data System (ADS)

    Versluis, Michel; Blom, Cock; van der Meer, Devaraj; van der Weele, Ko; Lohse, Detlef

    2003-11-01

    When a visco-elastic fluid such as shampoo or shower gel is poured onto a flat surface the fluid piles up forming a heap on which rather irregular combinations of fluid buckling, coiling and folding are observed. Under specific conditions a string of fluid leaps from the heap and forms a steady jet fed by the incoming stream. Momentum transfer of the incoming jet, combined with the shear-thinning properties of the fluid, lead to a spoon-like dimple in the highly viscous fluid pool in which the jet recoils. The jet can be stable for several seconds. This effect is known as the Kaye effect. In order to reveal its mechanism we analyzed leaping shampoo through high-speed imaging. We studied the jet formation, jet stability and jet disruption mechanisms. We measured the velocity of both the incoming and recoiled jet, which was found to be thicker and slower. By inclining the surface on which the fluid was poured we observed jets leaping at upto five times.

  4. High-dilution effects revisited. 1. Physicochemical aspects.

    PubMed

    Bellavite, Paolo; Marzotto, Marta; Olioso, Debora; Moratti, Elisabetta; Conforti, Anita

    2014-01-01

    Several lines of evidence suggest that homeopathic high dilutions (HDs) can effectively have a pharmacological action, and so cannot be considered merely placebos. However, until now there has been no unified explanation for these observations within the dominant paradigm of the dose-response effect. Here the possible scenarios for the physicochemical nature of HDs are reviewed. A number of theoretical and experimental approaches, including quantum physics, conductometric and spectroscopic measurements, thermoluminescence, and model simulations investigated the peculiar features of diluted/succussed solutions. The heterogeneous composition of water could be affected by interactive phenomena such as coherence, epitaxy and formation of colloidal nanobubbles containing gaseous inclusions of oxygen, nitrogen, carbon dioxide, silica and, possibly, the original material of the remedy. It is likely that the molecules of active substance act as nucleation centres, amplifying the formation of supramolecular structures and imparting order to the solvent. Three major models for how this happens are currently being investigated: the water clusters or clathrates, the coherent domains postulated by quantum electrodynamics, and the formation of nanoparticles from the original solute plus solvent components. Other theoretical approaches based on quantum entanglement and on fractal-type self-organization of water clusters are more speculative and hypothetical. The problem of the physicochemical nature of HDs is still far from to be clarified but current evidence strongly supports the notion that the structuring of water and its solutes at the nanoscale can play a key role. PMID:24439452

  5. Revisiting the hysteresis effect in surface energy budgets

    NASA Astrophysics Data System (ADS)

    Sun, Ting; Wang, Zhi-Hua; Ni, Guang-Heng

    2013-05-01

    The hysteresis effect in diurnal cycles of net radiation Rn and ground heat flux G0 has been observed in many studies, while the governing mechanism remains vague. In this study, we link the phenomenology of hysteresis loops to the wave phase difference between the diurnal evolutions of various terms in the surface energy balance. Rn and G0 are parameterized with the incoming solar radiation and the surface temperature as two control parameters of the surface energy partitioning. The theoretical analysis shows that the vertical water flux W and the scaled ratio As*>/AT* (net shortwave radiation to outgoing longwave radiation) play crucial roles in shaping hysteresis loops of Rn and G0. Comparisons to field measurements indicate that hysteresis loops for different land covers can be well captured by the theoretical model, which is also consistent with Camuffo-Bernadi formula. This study provides insight into the surface partitioning and temporal evolution of the energy budget at the land surface.

  6. The serial nature of the masked onset priming effect revisited.

    PubMed

    Mousikou, Petroula; Coltheart, Max

    2014-01-01

    Reading aloud is faster when target words/nonwords are preceded by masked prime words/nonwords that share their first sound with the target (e.g., save-SINK) compared to when primes and targets are unrelated to each other (e.g., farm-SINK). This empirical phenomenon is the masked onset priming effect (MOPE) and is known to be due to serial left-to-right processing of the prime by a sublexical reading mechanism. However, the literature in this domain lacks a critical experiment. It is possible that when primes are real words their orthographic/phonological representations are activated in parallel and holistically during prime presentation, so any phoneme overlap between primes and targets (and not just initial-phoneme overlap) could facilitate target reading aloud. This is the prediction made by the only computational models of reading aloud that are able to simulate the MOPE, namely the DRC1.2.1, CDP+, and CDP++ models. We tested this prediction in the present study and found that initial-phoneme overlap (blip-BEST), but not end-phoneme overlap (flat-BEST), facilitated target reading aloud compared to no phoneme overlap (junk-BEST). These results provide support for a reading mechanism that operates serially and from left to right, yet are inconsistent with all existing computational models of single-word reading aloud. PMID:24853396

  7. Toward understanding the thermodynamics of TALSPEAK process. Medium effects on actinide complexation

    SciTech Connect

    Peter R Zalupski; Leigh R Martin; Ken Nash; Yoshinobu Nakamura; Masahiko Yamamoto

    2009-07-01

    The ingenious combination of lactate and diethylenetriamine-N,N,N’,N”,N”-pentaacetic acid (DTPA) as an aqueous actinide-complexing medium forms the basis of the successful separation of americium and curium from lanthanides known as the TALSPEAK process. While numerous reports in the prior literature have focused on the optimization of this solvent extraction system, considerably less attention has been devoted to the understanding of the basic thermodynamic features of the complex fluids responsible for the separation. The available thermochemical information of both lactate and DTPA protonation and metal complexation reactions are representative of the behavior of these ions under idealized conditions. Our previous studies of medium effects on lactate protonation suggest that significant departures from the speciation predicted based on reported thermodynamic values should be expected in the TALSPEAK aqueous environment. Thermodynamic parameters describing the separation chemistry of this process thus require further examination at conditions significantly removed from conventional ideal systems commonly employed in fundamental solution chemistry. Such thermodynamic characterization is the key to predictive modelling of TALSPEAK. Improved understanding will, in principle, allow process technologists to more efficiently respond to off-normal conditions during large scale process operation. In this report, the results of calorimetric and potentiometric investigations of the effects of aqueous electrolytes on the thermodynamic parameters for lactate protonation and lactate complexation of americium and neodymium will be presented. Studies on the lactate protonation equilibrium will clearly illustrate distinct thermodynamic variations between strong electrolyte aqueous systems and buffered lactate environment.

  8. The 'male effect' in sheep and goats--revisiting the dogmas.

    PubMed

    Delgadillo, J Alberto; Gelez, Helene; Ungerfeld, Rodolfo; Hawken, Penelope A R; Martin, Graeme B

    2009-06-25

    Male-induced ovulation in sheep and goats (the 'male effect'), documented during the period 1940-1960, has long been shrouded in preconceptions concerning how, when and why it worked. These preconceptions became dogmas but recent research is challenging them so, in this review, we have re-visited some major physiological (breed seasonality; characteristics of the response; the nature of the male stimuli) and physical factors (duration of male presence; isolation from male stimuli) that affect the phenomenon. We reject the dogma that ewes must be isolated from males and conclude that male 'novelty' is more important than isolation per se. Similarly, we reject the perception that the neuroendocrine component of the male effect is restricted to anovulatory females. Finally, we re-assess the relative importance of olfactory and non-olfactory signals, and develop a perspective on the way male-induced ovulation fits with preconceptions about pheromonal processes in mammals. Overall, our understanding of the male effect has evolved significantly and it is time to modify or reject our dogmas so this field of research can advance. We can now ask new questions regarding the application of the male effect in industry and develop research so we can fully understand this biological phenomenon. PMID:19374015

  9. Irrigation effects in the northern lake states: Wisconsin central sands revisited.

    PubMed

    Kraft, George J; Clancy, Katherine; Mechenich, David J; Haucke, Jessica

    2012-01-01

    Irrigated agriculture has expanded greatly in the water-rich U.S. northern lake states during the past half century. Source water there is usually obtained from glacial aquifers strongly connected to surface waters, so irrigation has a potential to locally decrease base flows in streams and water levels in aquifers, lakes, and wetlands. During the nascent phase of the irrigation expansion, water availability was explored in works of some fame in the Wisconsin central sands by Weeks et al. (1965) on the Little Plover River and Weeks and Stangland (1971) on "headwater area" streams and lakes. Four decades later, and after irrigation has grown to a dominant landscape presence, we revisited irrigation effects on central sands hydrology. Irrigation effects have been substantial, on average decreasing base flows by a third or more in many stream headwaters and diminishing water levels by more than a meter in places. This explains why some surface waters have become flow and stage impaired, sometimes to the point of drying, with attendant losses of aquatic ecosystems. Irrigation exerts its effects by increasing evapotranspiration by an estimated 45 to 142 mm/year compared with pre-irrigated land cover. We conclude that irrigation water availability in the northern lake states and other regions with strong groundwater-surface water connections is tied to concerns for surface water health, requiring a focus on managing the upper few meters of aquifers on which surface waters depend rather than the depletability of an aquifer. PMID:21707615

  10. Effects of cosmic acceleration on black hole thermodynamics

    NASA Astrophysics Data System (ADS)

    Mandal, Abhijit

    2016-07-01

    Direct local impacts of cosmic acceleration upon a black hole are matters of interest. Babichev et. al. had published before that the Friedmann equations which are prevailing the part of fluid filled up in the universe to lead (or to be very specific, `dominate') the other constituents of universe and are forcing the universe to undergo present-day accelerating phase (or to lead to violate the strong energy condition and latter the week energy condition), will themselves tell that the rate of change of mass of the central black hole due to such exotic fluid's accretion will essentially shrink the mass of the black hole. But this is a global impact indeed. The local changes in the space time geometry next to the black hole can be analysed from a modified metric governing the surrounding space time of a black hole. A charged deSitter black hole solution encircled by quintessence field is chosen for this purpose. Different thermodynamic parameters are analysed for different values of quintessence equation of state parameter, ω_q. Specific jumps in the nature of the thermodynamic space near to the quintessence or phantom barrier are noted and physically interpreted as far as possible. Nature of phase transitions and the situations at which these transitions are taking place are also explored. It is determined that before quintessence starts to work (ω_q=-0.33>-1/3) it was preferable to have a small unstable black hole followed by a large stable one. But in quintessence (-1/3>ω_q>-1), black holes are destined to be unstable large ones pre-quelled by stable/ unstable small/ intermediate mass black holes.

  11. Effects from switching on PIC simulations: Geospace Environmental Modeling (GEM) reconnection setup revisited

    NASA Astrophysics Data System (ADS)

    Bourdin, P. A.; Nakamura, T.; Narita, Y.

    2015-12-01

    Electromagnetic Parcile-In-Cell (PIC) simulations are widely used to study plasma phenomena where kinetic scales are coupled to fluid scales. One of these phenomena is the evolution of magnetic reconnection. Switch-on effects have been described earlier for magneto-/hydrodynamic (MHD and HD) simulations, where oscillations are ignited by the initial condition and the usual instantaneous way of starting a simulation run. Here we revisit the GEM setup (a Harris current sheet) and demonstrate the immediate generation of oscillations propagating perpendicular to the magnetic shear layer (in Bz). Also we show how these oscillations do not dissipate quickly and will later be mode-converted to generate wave power, first in By, much later also in Bx (pointing along the shear direction). One needs to take care not to interpret these oscillations as physical wave modes associated with the nature of reconnection. We propose a method to prevent such switch-on effects from the beginning, that should be considered for implementation in other PIC simulation codes as well.

  12. Revisiting the monopole components of effective interactions for the shell model

    NASA Astrophysics Data System (ADS)

    Wang, X. B.; Dong, G. X.

    2015-12-01

    In this paper, we revisit the monopole components of effective interactions for the shell model. Without going through specific nuclei or shell gaps, universal roles of central, tensor, and spin-orbit forces can be proved, reflecting the intrinsic features of shell model effective interactions. For monopole matrix elements, even and odd channels of central force often have a canceling effect. However, for the contributions to the shell evolution, its even and odd channels could have both positive or negative contributions, enhancing the role of central force on the shell structure. Tensor force is generally weaker than central force. However, for the effect on shell evolutions, tensor force can dominate or play a competitive role. A different systematics has been discovered between T = 1 and 0 channels. For example, tensor force, well established in the T = 0 channel, becomes uncertain in the T = 1 channel. We calculate the properties of neutron-rich oxygen and calcium isotopes in order to study T = 1 channel interactions further. It is learned that the main improvements of empirical interactions are traced to the central force. For non-central forces, antisymmetric spin-orbit (ALS) force, originated from many-body perturbations or three-body force, could also play an explicit role. T = 1 tensor forces are less constrained so their effect can differ in different empirical interactions. The influence of tensor force may sometimes be canceled by many-body effects. For T = 0 channels of effective interactions, which is the main source of neutron-proton correlations, central and tensor forces are the leading components. For T = 1 channels, which can act between like-particles, the request for many-body correlations could be more demanding, so that the monopole anomaly of the T = 1 channel might be more serious.

  13. Corona discharges and their effect on lightning attachment revisited: Upward leader initiation and downward leader interception

    NASA Astrophysics Data System (ADS)

    Becerra, Marley

    2014-11-01

    Previous studies have suggested the possibility of using glow corona discharges to control the frequency of lightning flashes to grounded objects. In order to revisit the theoretical basis of this proposal, the self-consistent leader inception and propagation model - SLIM - is used together with a two-dimensional glow corona drift model. The analysis is performed to quantify the effect of glow corona generated at the tip of ground-based objects on the initiation and propagation of upward positive connecting leaders under the influence of downward lightning leaders. It is found that the presence of glow corona does not influence the performance of Franklin lightning rods shorter than 15 m, while it slightly reduces the lateral distance of rods up to 60 m tall by a maximum of 10%. Furthermore, the results indicate that it is not possible to suppress the initiation of upward connecting leaders by means of glow corona. It is found instead that unconventional lightning protection systems based on the generation of glow corona attract downward lightning flashes in a similar way as a standard lightning rod with the same height.

  14. High pressure effects revisited for the cuprate superconductor family with highest critical temperature

    PubMed Central

    Yamamoto, Ayako; Takeshita, Nao; Terakura, Chieko; Tokura, Yoshinori

    2015-01-01

    How to enhance the superconducting critical temperature (Tc) has been a primary issue since the discovery of superconductivity. The highest Tc reported so far is 166 K in HgBa2Ca2Cu3O8+δ (Hg1223) at high pressure of 23 GPa, as determined with the reduction onset, but not zero, of resistivity. To clarify the possible condition of the real maximum Tc, it is worth revisiting the effects of pressure on Tc in the highest Tc family. Here we report a systematic study of the pressure dependence of Tc in HgBa2CaCu2O6+δ (Hg1212) and Hg1223 with the doping level from underdoped to overdoped. The Tc with zero resistivity is probed with a cubic-anvil-type apparatus that can produce hydrostatic pressures. Variation, not only increase but also decrease, of Tc in Hg1212 and Hg1223 with pressure strongly depends on the initial doping levels. In particular, we confirm a maximum Tc of 153 K at 22 GPa in slightly underdoped Hg1223. PMID:26619829

  15. High pressure effects revisited for the cuprate superconductor family with highest critical temperature.

    PubMed

    Yamamoto, Ayako; Takeshita, Nao; Terakura, Chieko; Tokura, Yoshinori

    2015-01-01

    How to enhance the superconducting critical temperature (Tc) has been a primary issue since the discovery of superconductivity. The highest Tc reported so far is 166 K in HgBa2Ca2Cu3O8+δ (Hg1223) at high pressure of 23 GPa, as determined with the reduction onset, but not zero, of resistivity. To clarify the possible condition of the real maximum Tc, it is worth revisiting the effects of pressure on Tc in the highest Tc family. Here we report a systematic study of the pressure dependence of Tc in HgBa2CaCu2O6+δ (Hg1212) and Hg1223 with the doping level from underdoped to overdoped. The Tc with zero resistivity is probed with a cubic-anvil-type apparatus that can produce hydrostatic pressures. Variation, not only increase but also decrease, of Tc in Hg1212 and Hg1223 with pressure strongly depends on the initial doping levels. In particular, we confirm a maximum Tc of 153 K at 22 GPa in slightly underdoped Hg1223. PMID:26619829

  16. Dynamics and thermodynamics of a tornado: Rotation effects

    NASA Astrophysics Data System (ADS)

    Ben-Amots, N.

    2016-09-01

    This paper investigates the relevant processes in the tornado including the dynamics of rotation and thermodynamics as well as condensation. The main novelty of this paper is the explanation of the phenomena occurring in the central downflow. The reduced pressure in the tornado's funnel sucks air and water vapor from the cloud above the tornado. The latent heat of condensation is released in the funnel. The centrifugal force drives the generated water drops out of the funnel. The latent heat of condensation released is also transferred out of the funnel, and supplies the helically ascending air flow surrounding the tornado with additional buoyancy energy. This process gives the tornado increased strength compared to the dust devil type of flow, thus explaining why tornadoes occur always under a cloud, and why the tornado pipe can reach a height of a kilometer and more. To sustain a tornado, the temperature of water vapor at the cloud's base should be higher than the surroundings by a certain minimal value. Remote infrared temperature measurements of clouds' bases may provide indications of the probability that a cloud can spawn a tornado, which may increase the lead time.

  17. Revisiting the S-matrix approach to the open superstring low energy effective lagrangian

    NASA Astrophysics Data System (ADS)

    Barreiro, Luiz Antonio; Medina, Ricardo

    2012-10-01

    The conventional S-matrix approach to the (tree level) open string low energy effective lagrangian assumes that, in order to obtain all its bosonic α ' N order terms, it is necessary to know the open string (tree level) ( N + 2)-point amplitude of massless bosons, at least expanded at that order in α '. In this work we clarify that the previous claim is indeed valid for the bosonic open string, but for the supersymmetric one the situation is much more better than that: there are constraints in the kinematical bosonic terms of the amplitude (probably due to Spacetime Supersymmetry) such that a much lower open superstring n-point amplitude is needed to find all the α ' N order terms. In this `revisited' S-matrix approach we have checked that, at least up to α '4 order, using these kinematical constraints and only the known open superstring 4-point amplitude, it is possible to determine all the bosonic terms of the low energy effective lagrangian. The sort of results that we obtain seem to agree completely with the ones achieved by the method of BPS configurations, proposed about ten years ago. By means of the KLT relations, our results can be mapped to the NS-NS sector of the low energy effective lagrangian of the type II string theories implying that there one can also find kinematical constraints in the N-point amplitudes and that important informations can be inferred, at least up to α '4 order, by only using the (tree level) 4-point amplitude.

  18. Thermodynamic network model for predicting effects of substrate addition and other perturbations on subsurface microbial communities

    SciTech Connect

    Jack Istok; Melora Park; James McKinley; Chongxuan Liu; Lee Krumholz; Anne Spain; Aaron Peacock; Brett Baldwin

    2007-04-19

    The overall goal of this project is to develop and test a thermodynamic network model for predicting the effects of substrate additions and environmental perturbations on microbial growth, community composition and system geochemistry. The hypothesis is that a thermodynamic analysis of the energy-yielding growth reactions performed by defined groups of microorganisms can be used to make quantitative and testable predictions of the change in microbial community composition that will occur when a substrate is added to the subsurface or when environmental conditions change.

  19. Effect of temperature on microbial growth rate - thermodynamic analysis, the arrhenius and eyring-polanyi connection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this work is to develop a new thermodynamic mathematical model for evaluating the effect of temperature on the rate of microbial growth. The new mathematical model is derived by combining the Arrhenius equation and the Eyring-Polanyi transition theory. The new model, suitable for ...

  20. Thermodynamic method of calculating the effect of alloying additives on interphase interaction in composite materials

    NASA Technical Reports Server (NTRS)

    Tuchinsky, L. I.

    1986-01-01

    The effect of alloying additives to the matrix of a composite on the high temperature solubility rate of a single component fiber was analyzed thermodynamically. With an example of binary Ni alloys, with Group IV-VI transition metals reinforced with W fibers, agreement between the calculated and experimental data was demonstrated.

  1. Thermodynamic Analysis of Isotope Effects on Triple Points and/or Melting Temperatures

    NASA Astrophysics Data System (ADS)

    Van Hook, W. Alexander

    1995-05-01

    Available literature information on triple point or melting point isotope effects (and related physical properties) is subjected to thermodynamic analysis and consistency checks. New values for the melting point isotope effects for C6H6/CgD6 and c-C6H12/c-C6D12 are reported. 6Li/7Li melting point isotope effects reported recently by Hidaka and Lunden (Z. Naturforsch. 49 a, 475 (1994)) for various inorganic salts are questioned

  2. Lakatos Revisited.

    ERIC Educational Resources Information Center

    Court, Deborah

    1999-01-01

    Revisits and reviews Imre Lakatos' ideas on "Falsification and the Methodology of Scientific Research Programmes." Suggests that Lakatos' framework offers an insightful way of looking at the relationship between theory and research that is relevant not only for evaluating research programs in theoretical physics, but in the social sciences as…

  3. Thermodynamics of multicaloric effects in multiferroic materials: application to metamagnetic shape-memory alloys and ferrotoroidics.

    PubMed

    Planes, Antoni; Castán, Teresa; Saxena, Avadh

    2016-08-13

    We develop a general thermodynamic framework to investigate multicaloric effects in multiferroic materials. This is applied to the study of both magnetostructural and magnetoelectric multiferroics. Landau models with appropriate interplay between the corresponding ferroic properties (order parameters) are proposed for metamagnetic shape-memory and ferrotoroidic materials, which, respectively, belong to the two classes of multiferroics. For each ferroic property, caloric effects are quantified by the isothermal entropy change induced by the application of the corresponding thermodynamically conjugated field. The multicaloric effect is obtained as a function of the two relevant applied fields in each class of multiferroics. It is further shown that multicaloric effects comprise the corresponding contributions from caloric effects associated with each ferroic property and the cross-contribution arising from the interplay between these ferroic properties.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'. PMID:27402925

  4. Spin Hall Effect and Irreversible Thermodynamics; Center-to-Edge Transverse Current-Induced Voltage

    NASA Astrophysics Data System (ADS)

    Saslow, Wayne

    2015-03-01

    For the first time the Dyakonov and Perel theory of the Spin Hall Effect (SHE) is examined from the viewpoint of irreversible thermodynamics, which is significantly more constraining than the symmetry arguments of pure phenomenology. As thermodynamic driving forces we include the thermal gradient, the gradient of the electrochemical potential (rather than the potential gradient and density gradient separately), and the ``internal'' magnetic field that is thermodynamically conjugate to the magnetization. In turn, we obtain the form of bulk transport coefficients relating the fluxes to the thermodynamic forces. Relative to Dyakonov and Perel, in addition to the new terms due to thermal gradients, the Onsager relations require three new (non-linear) terms in the current density, and minor revisions in the current density and spin current density. For a longitudinal current along a strip, the center-to-edge transverse voltage difference, due both to the - β P --> × E --> term of the number current density q --> and to one of the new current density terms, is determined. An ac capacitative probe likely would not significantly disturb this effect. We estimate a ΔV⊥ as large as 10-4 V for GaAs, but only 10-8 V for Pt. This work was performed while a guest of the Center for Nanoscale Science and Technology, NIST, Gaithersburg, MD, 20878.

  5. Effects of interaction on thermodynamics of a repulsive Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Satadal; Das, Tapan Kumar; Chakrabarti, Barnali

    2013-11-01

    We report the effects of interaction on thermodynamic properties of a repulsive Bose-Einstein condensate confined in a harmonic trap by using the correlated potential harmonics expansion method. This many-body technique permits the use of a realistic interactomic interaction, which gives rise to the effective long-range interaction of the condensate in terms of the s-wave scattering length. We have computed temperature (T) dependence of the chemical potential, specific heat, condensate fraction, entropy, pressure, and the average energy per particle of a system containing a large number (A) of 87Rb atoms in the Joint Institute for Laboratory Astrophysics (JILA) trap. The repulsion among the interacting bosons results in a small but measurable drop of condensate fraction and critical temperature (Tc), compared to those of a noninteracting condensate. These are in agreement with the experiment. Although all thermodynamic quantities have a strong dependence on A and to a smaller extent on the interatomic interaction, our numerical calculation appears to show that a thermodynamic quantity per particle follows a universal behavior as a function of T/Tc. This shows the importance of Tc for all thermodynamic properties of the condensate. As expected, for T>Tc, these properties follow those of a trapped noncondensed Bose gas.

  6. Interfacial solvation thermodynamics.

    PubMed

    Ben-Amotz, Dor

    2016-10-19

    Previous studies have reached conflicting conclusions regarding the interplay of cavity formation, polarizability, desolvation, and surface capillary waves in driving the interfacial adsorptions of ions and molecules at air-water interfaces. Here we revisit these questions by combining exact potential distribution results with linear response theory and other physically motivated approximations. The results highlight both exact and approximate compensation relations pertaining to direct (solute-solvent) and indirect (solvent-solvent) contributions to adsorption thermodynamics, of relevance to solvation at air-water interfaces, as well as a broader class of processes linked to the mean force potential between ions, molecules, nanoparticles, proteins, and biological assemblies. PMID:27545849

  7. Minimal Length Effects in Black Hole Thermodynamics from Tunneling Formalism

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, Sunandan

    2016-01-01

    The tunneling formalism in the Hamilton-Jacobi approach is adopted to study Hawking radiation of massless Dirac particles from spherically symmetric black hole spacetimes incorporating the effects of the generalized uncertainty principle. The Hawking temperature is found to contain corrections from the generalized uncertainty principle. Further, we show from this result that the ratio of the GUP corrected energy of the particle to the GUP corrected Hawking temperature is equal to the ratio of the corresponding uncorrected quantities. This result is then exploited to compute the Hawking temperature for more general forms of the uncertainty principle having infinite number of terms. Choosing the coefficients of the terms in the series in a specific way enables one to sum the infinite series exactly. This leads to a Hawking temperature for the Schwarzschild black hole that agrees with the result which accounts for the one loop back reaction effect. The entropy is finally computed and yields the area theorem upto logarithmic corrections.

  8. Hydration of hyaluronan: effects on structural and thermodynamic properties.

    PubMed

    Albèr, Cathrine; Engblom, Johan; Falkman, Peter; Kocherbitov, Vitaly

    2015-03-19

    Hyaluronan (HA) is a frequently occurring biopolymer with a large variety of functions in nature. During the past 60 years, there have been numerous reports on structural and dynamic behavior of HA in water. Nevertheless, studies covering a wider concentration range are still lacking. In this work, we use isothermal scanning sorption calorimetry for the first time to investigate hydration-induced transitions in HA (sodium hyaluronate, 17 kDa). From this method, we obtain the sorption isotherm and the enthalpy and the entropy of hydration. Thermotropic events are evaluated by differential scanning calorimetry (DSC), and structure analysis is performed with X-ray scattering (SWAXS) and light and scanning electron microscopy. During isothermal hydration, HA exhibits a glass transition, followed by crystallization and subsequent dissolution of HA crystals and formation of a one-phase solution. Structural analysis reveals that the crystal may be indexed on an orthorhombic unit cell with space group P212121. Crystallization of HA was found to occur either through endothermic or exothermic processes, depending on the temperature and water content. We propose a mechanism of crystallization that explains this phenomenon based on the interplay between the hydrophobic effect and strengthening of hydrogen bonds during formation of crystals. The combined results were used to construct a binary phase diagram for the HA-water system. PMID:25719495

  9. Brush Effects on DNA Chips: Thermodynamics, Kinetics, and Design Guidelines

    PubMed Central

    Halperin, A.; Buhot, A.; Zhulina, E. B.

    2005-01-01

    In biology experiments, oligonucleotide microarrays are contacted with a solution of long nucleic acid targets. The hybridized probes thus carry long tails. When the surface density of the oligonucleotide probes is high enough, the progress of hybridization gives rise to a polyelectrolyte brush due to mutual crowding of the nucleic acid tails. The free-energy penalty associated with the brush modifies both the hybridization isotherms and the rate equations: the attainable hybridization is lowered significantly as is the hybridization rate. When the equilibrium hybridization fraction, xeq, is low, the hybridization follows a Langmuir type isotherm, xeq/(1 − xeq) = ctK where ct is the target concentration and K is the equilibrium constant. K is smaller than its bulk value by a factor (n/N)2/5 due to wall effects where n and N denote the number of bases in the probe and the target. At higher xeq, when the brush is formed, the leading correction is \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}x_{{\\mathrm{eq}}}/(1-x_{{\\mathrm{eq}}})=c_{{\\mathrm{t}}}K\\hspace{.167em}{\\mathrm{exp}}\\hspace{.167em} \\left \\left[-const^{\\prime} \\left \\left(x_{{\\mathrm{eq}}}^{2/3}-x_{{\\mathrm{B}}}^{2/3}\\right) \\right \\right] \\right \\end{equation*}\\end{document} where xB corresponds to the onset of the brush regime. The denaturation rate constant in the two regimes is identical. However, the hybridization rate constant in the brush regime is lower, the leading correction being \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\mathrm{exp}}\\hspace{.167em} \\left \\left[-const^{\\prime} \\left \\left

  10. Thermodynamic analysis and experimental study of the effect of atmospheric pressure on the ice point

    SciTech Connect

    Harvey, A. H.; McLinden, M. O.; Tew, W. L.

    2013-09-11

    We present a detailed thermodynamic analysis of the temperature of the ice point as a function of atmospheric pressure. This analysis makes use of accurate international standards for the properties of water and ice, and of available high-accuracy data for the Henry's constants of atmospheric gases in liquid water. The result is an ice point of 273.150 019(5) K at standard atmospheric pressure, with higher ice-point temperatures (varying nearly linearly with pressure) at lower pressures. The effect of varying ambient CO{sub 2} concentration is analyzed and found to be significant in comparison to other uncertainties in the model. The thermodynamic analysis is compared with experimental measurements of the temperature difference between the ice point and the triple point of water performed at elevations ranging from 145 m to 4302 m, with atmospheric pressures from 101 kPa to 60 kPa.

  11. Fluorination effects on the thermodynamic, thermophysical and surface properties of ionic liquids

    PubMed Central

    Reis, P. M.; Carvalho, P. J.; Lopes-da-Silva, J. A.; Esperança, J. M. S. S.; Araújo, J. M. M.; Rebelo, L. P. N.; Freire, M. G.; Pereiro, A. B.

    2016-01-01

    This paper reports the thermal, thermodynamic, thermophysical and surface properties of eight ionic liquids with fluorinated alkyl side chain lengths equal or greater than four carbon atoms. Melting and decomposition temperatures were determined together with experimental densities, surface tensions, refractive indices, dynamic viscosities and ionic conductivities in a temperature interval ranging from 293.15 to 353.15 K. The surface properties of these fluorinated ionic liquids were discussed and several thermodynamic functions, as well as critical temperatures, were estimated. Coefficients of isobaric thermal expansion, molecular volumes and free volume effects were calculated from experimental values of density and refractive index and compared with previous data. Finally, Walden plots were used to evaluate the ionicity of the investigated ionic liquids.

  12. Thermodynamics at the microscale: from effective heating to the Brownian Carnot engine

    NASA Astrophysics Data System (ADS)

    Dinis, L.; Martínez, I. A.; Roldán, É.; Parrondo, J. M. R.; Rica, R. A.

    2016-05-01

    We review a series of experimental studies of the thermodynamics of nonequilibrium processes at the microscale. In particular, in these experiments we studied the fluctuations of the thermodynamic properties of a single optically-trapped microparticle immersed in water and in the presence of external random forces. In equilibrium, the fluctuations of the position of the particle can be described by an effective temperature that can be tuned up to thousands of Kelvin. Isothermal and non-isothermal thermodynamic processes that also involve changes in a control parameter were implemented by controlling the effective temperature of the particle and the stiffness of the optical trap. Since truly adiabatic processes are unfeasible in colloidal systems, mean adiabatic protocols where no average heat is exchanged between the particle and the environment are discussed and implemented. By concatenating isothermal and adiabatic protocols, it is shown how a single-particle Carnot engine can be constructed. Finally, we provide an in-depth study of the fluctuations of the energetics and the efficiency of the cycle.

  13. Summarizing lecture: factors influencing enzymatic H-transfers, analysis of nuclear tunnelling isotope effects and thermodynamic versus specific effects

    PubMed Central

    Marcus, R.A

    2006-01-01

    In the articles in this Discussion, a wide variety of topics are treated, including reorganization energy, initially introduced for electron transfers (‘environmentally assisted tunnelling’), nuclear tunnelling, H/D and C12/C13 kinetic isotope effects (KIEs), the effect of changes of distal and nearby amino acid residues using site-directed mutagenesis, and dynamics versus statistical effects. A coordinate-free form of semi-classical theory is used to examine topics on data such as tunnelling versus ‘over-the-barrier’ paths and temperature and pressure effects on KIEs. The multidimensional semi-classical theory includes classically allowed and classically forbidden transitions. More generally, we address the question of relating kinetic to thermodynamic factors, as in the electron transfer field, so learning about specific versus thermodynamic effects in enzyme catalysis and KIEs. PMID:16873131

  14. Effects of thermodynamic profiles on the interaction of binary tropical cyclones

    NASA Astrophysics Data System (ADS)

    Jang, Wook; Chun, Hye-Yeong

    2015-09-01

    The interactions between idealized binary tropical cyclones (TCs) on f and β planes with different separation distance and thermodynamic soundings obtained from the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data averaged over the western North Pacific are investigated through ensemble three-dimensional numerical simulations with a horizontal resolution of 10 km in a single domain. In the simulations on the f plane, two TCs show mutual cyclonic rotations with symmetric structures. Two TCs with thermodynamic profiles of larger convective available potential energy (CAPE) and maximum potential intensity (MPI) show greater interaction than those with a smaller CAPE and MPI due to the stronger tangential velocity near the TC center. In the simulations on the β plane, the two TCs do not merge, because the beta effect prevents the attraction of the two TCs by generating asymmetric motions of the TC with northwestward forcing. The relative strengths of the two TCs change with time and depend on the low-level inflow influenced by the Coriolis parameter. Similar to the results on the f plane, the two TCs only merge with the thermodynamic soundings of large CAPE and MPI.

  15. Association effects in pure methanol via Monte Carlo simulations. II. Thermodynamics

    NASA Astrophysics Data System (ADS)

    Gómez-Álvarez, Paula; Romaní, Luis; González-Salgado, Diego

    2013-01-01

    A simple methodology [P. Gómez-Álvarez, A. Dopazo-Paz, L. Romani, and D. González-Salgado, J. Chem. Phys. 134, 014512 (2011), 10.1063/1.3524201] recently developed in the light of the Monte Carlo molecular simulation technique was used in this work to study the association effects on the response functions of methanol over the whole thermodynamic state space. It consists basically on evaluating the first order properties of the fluid (energy and volume) in terms of those for two hypothetical fluids living in the bulk composed by monomers and associated molecules, respectively. In this context, the second order thermodynamic derivatives can be expressed in a perturbative way as the sum of the monomer term (reference term) and the association contribution. Specifically, both contributions to the residual isobaric heat capacity, and to the pressure and temperature derivatives of the volume were determined for the optimized potential for liquid simulation (OPLS) of methanol through NPT Monte Carlo simulations from 250 K to 1000 K along the supercritical isobars 25, 100, 200, 500 MPa, and from 800 K to 350 K at 0.1 MPa. Results showed that both terms are relevant for the residual isobaric heat capacity and that their influence depends considerably on the thermodynamic conditions; however, the volumetric response functions were found mainly affected by the monomer contribution, especially the pressure derivative of the volume.

  16. The effectiveness of problem-based learning on teaching the first law of thermodynamics

    NASA Astrophysics Data System (ADS)

    Tatar, Erdal; Oktay, Münir

    2011-11-01

    Background: Problem-based learning (PBL) is a teaching approach working in cooperation with self-learning and involving research to solve real problems. The first law of thermodynamics states that energy can neither be created nor destroyed, but that energy is conserved. Students had difficulty learning or misconceptions about this law. This study is related to the teaching of the first law of thermodynamics within a PBL environment. Purpose: This study examined the effectiveness of PBL on candidate science teachers' understanding of the first law of thermodynamics and their science process skills. This study also examined their opinions about PBL. Sample: The sample consists of 48 third-grade university students from the Department of Science Education in one of the public universities in Turkey. Design and methods: A one-group pretest-posttest experimental design was used. Data collection tools included the Achievement Test, Science Process Skill Test, Constructivist Learning Environment Survey and an interview with open-ended questions. Paired samples t-test was conducted to examine differences in pre/post tests. Results: The PBL approach has a positive effect on the students' learning abilities and science process skills. The students thought that the PBL environment supports effective and permanent learning, and self-learning planning skills. On the other hand, some students think that the limited time and unfamiliarity of the approach impede learning. Conclusions: The PBL is an active learning approach supporting students in the process of learning. But there are still many practical disadvantages that could reduce the effectiveness of the PBL. To prevent the alienation of the students, simple PBL activities should be applied from the primary school level. In order to overcome time limitations, education researchers should examine short-term and effective PBL activities.

  17. The "Sadly Cannot" Thermodynamic Cycle Revisited.

    ERIC Educational Resources Information Center

    Mills, David S.; Huston, Craig S.

    1991-01-01

    An exercise that gives students a chance to use the equations of state for both an ideal gas and for an adiabatic process in determining the points at which heat flow reverses direction and at which the working substance reaches its maximum temperature is demonstrated. (KR)

  18. Experimental study of the thermodynamic effect in a cavitating flow on a simple Venturi geometry

    NASA Astrophysics Data System (ADS)

    Petkovšek, M.; Dular, M.

    2015-12-01

    The thermodynamic effects in cavitating flow are observed on a simple Venturi profile. A thorough experimental investigation of the temperature field on cavitating flow has been performed in water of 100°C at different operating conditions. Temperature measurements were performed with Infra-Red (IR) high-speed camera, while visualisation was made with conventional high-speed camera. Both, average temperature fields and temperature dynamics are presented at different operating conditions and compared with collected data in visual spectrum. In the vicinity of the throat a temperature depression up to 0.5 K was recorded.

  19. Thermodynamic Calculation Study on Effect of Manganese on Stability of Austenite in High Nitrogen Stainless Steels

    NASA Astrophysics Data System (ADS)

    Wang, Qingchuan; Zhang, Bingchun; Yang, Ke

    2016-07-01

    A series of high nitrogen steels were studied by using thermodynamic calculations to investigate the effect of manganese on the stability of austenite. Surprisingly, it was found that the austenite stabilizing ability of manganese was strongly weakened by chromium, but it was strengthened by molybdenum. In addition, with an increase of manganese content, the ferrite stabilizing ability of chromium significantly increased, but that of molybdenum decreased. Therefore, strong interactions exist between manganese and the other alloying elements, which should be the main reason for the difference among different constituent diagrams.

  20. Effects of a scalar field on the thermodynamics of interuniversal entanglement

    NASA Astrophysics Data System (ADS)

    Garay, Iñaki; Robles-Pérez, Salvador

    2014-03-01

    We consider a multiverse scenario made up of classically disconnected regions of the spacetime that are, nevertheless, in a quantum entangled state. The addition of a scalar field enriches the model and allows us to treat both the inflationary and the "oscillatory stage" of the universe on the same basis. Imposing suitable boundary conditions on the state of the multiverse, two different representations are constructed related by a Bogoliubov transformation. We compute the thermodynamic magnitudes of the entanglement, such as entropy and energy, explore the effects introduced by the presence of the scalar field and compare with previous results in the absence of scalar field.

  1. Thermodynamic Calculation Study on Effect of Manganese on Stability of Austenite in High Nitrogen Stainless Steels

    NASA Astrophysics Data System (ADS)

    Wang, Qingchuan; Zhang, Bingchun; Yang, Ke

    2016-05-01

    A series of high nitrogen steels were studied by using thermodynamic calculations to investigate the effect of manganese on the stability of austenite. Surprisingly, it was found that the austenite stabilizing ability of manganese was strongly weakened by chromium, but it was strengthened by molybdenum. In addition, with an increase of manganese content, the ferrite stabilizing ability of chromium significantly increased, but that of molybdenum decreased. Therefore, strong interactions exist between manganese and the other alloying elements, which should be the main reason for the difference among different constituent diagrams.

  2. Revisiting the incremental effects of context on word processing: Evidence from single-word event-related brain potentials.

    PubMed

    Payne, Brennan R; Lee, Chia-Lin; Federmeier, Kara D

    2015-11-01

    The amplitude of the N400-an event-related potential (ERP) component linked to meaning processing and initial access to semantic memory-is inversely related to the incremental buildup of semantic context over the course of a sentence. We revisited the nature and scope of this incremental context effect, adopting a word-level linear mixed-effects modeling approach, with the goal of probing the continuous and incremental effects of semantic and syntactic context on multiple aspects of lexical processing during sentence comprehension (i.e., effects of word frequency and orthographic neighborhood). First, we replicated the classic word-position effect at the single-word level: Open-class words showed reductions in N400 amplitude with increasing word position in semantically congruent sentences only. Importantly, we found that accruing sentence context had separable influences on the effects of frequency and neighborhood on the N400. Word frequency effects were reduced with accumulating semantic context. However, orthographic neighborhood was unaffected by accumulating context, showing robust effects on the N400 across all words, even within congruent sentences. Additionally, we found that N400 amplitudes to closed-class words were reduced with incrementally constraining syntactic context in sentences that provided only syntactic constraints. Taken together, our findings indicate that modeling word-level variability in ERPs reveals mechanisms by which different sources of information simultaneously contribute to the unfolding neural dynamics of comprehension. PMID:26311477

  3. Effect of the thermodynamic properties of W/O microemulsions on samarium oxide nanoparticle size.

    PubMed

    Zhu, Wenqing; Xu, Lei; Ma, Jin; Yang, Rui; Chen, Yashao

    2009-12-01

    In this work, we report the preparation of the Sm2O3 nanoparticle precursors (Sm(OH)3) via a simple W/O microemulsion process, in which microemulsions of cetyltrimethylammonium bromide (CTAB)/alkanol/1-octane/Sm(NO3)3 aqueous solution were added into sodium hydroxide (NaOH) aqueous solutions. The Sm2O3 nanoparticles were then prepared by calcining the precursors at 900 degrees C. Particularly, DeltaG(c-->i), which is the change in standard Gibbs free energy for transferring cosurfactant from the continuous phase to the microemulsion interface and can be used to estimate the thermodynamic properties of microemulsions, was determined using the dilution method. The effects of alkanol carbon chain length (1-pentanol, 1-hexanol, 1-heptanol and 1-octanol) and the reaction temperatures (298, 308, 318 and 328 K) on both DeltaG(c-->i) and Sm2O3 nanoparticle size have been investigated. Specifically, the Sm2O3 nanoparticle size, when calcined at 900 degrees C, was found to be mainly controlled by DeltaG(c-->i), and was thereby affected by the thermodynamic properties of microemulsions. The obtained products were characterized by DSC-TGA, XRD, TEM and UV-Vis. The results showed that DeltaG(c-->i) decreased with the increase in both the length of alkanol carbon chain and the reaction temperature, and the average size of Sm2O3 nanoparticles decreased as DeltaG(c-->i) decreased. The effect of microemulsion thermodynamic properties on Sm2O3 nanoparticle size reported here can provide some insights in controllable preparation of other rare earth oxide nanoparticles via the microemulsion route. PMID:19740477

  4. Magneto-elastic effects and thermodynamic properties of ferromagnetic hcp Co

    NASA Astrophysics Data System (ADS)

    Kuang, Fang-Guang; Kuang, Xiao-Yu; Kang, Shu-Ying; Mao, Ai-Jie

    2014-05-01

    Using first principles projector augmented wave (PAW) potential method, the magneto-elastic effects and thermodynamic properties of ferromagnetic hcp Cobalt at high pressure and temperature are investigated. The calculated elastic constants from PBE+U method demonstrate a noticeable improvement with regard to experimental data. Various physical quantities under high pressure also present significant improvements, such as the bulk modulus, shear modulus, Young's modulus, Debye temperature, various sound velocities and the normalized acoustic velocities in the meridian plane. That is due to the fact that Cobalt system possesses large correlation effects. Meanwhile, the phonon dispersion curves are in excellent agreement with experimental data. It is not observed any anomaly or instability under compression. However, according to the E2g-phonon frequencies, the obtained pressure variation of C44 elastic modulus also suggests that the system has miraculous magneto-elastic effects. Moreover, the pressure and temperature dependence of thermodynamic properties are derived within the quasi-harmonic approximation for the first time. The obtained Grüneisen ratio, Anderon-Grüneisen parameter and the volume dependence of Grüneisen ratio display manifestly temperature and pressure dependences.

  5. Effect of drop size on the impact thermodynamics for supercooled large droplet in aircraft icing

    NASA Astrophysics Data System (ADS)

    Zhang, Chen; Liu, Hong

    2016-06-01

    Supercooled large droplet (SLD), which can cause abnormal icing, is a well-known issue in aerospace engineering. Although efforts have been exerted to understand large droplet impact dynamics and the supercooled feature in the film/substrate interface, respectively, the thermodynamic effect during the SLD impact process has not received sufficient attention. This work conducts experimental studies to determine the effects of drop size on the thermodynamics for supercooled large droplet impingement. Through phenomenological reproduction, the rapid-freezing characteristics are observed in diameters of 400, 800, and 1300 μm. The experimental analysis provides information on the maximum spreading rate and the shrinkage rate of the drop, the supercooled diffusive rate, and the freezing time. A physical explanation of this unsteady heat transfer process is proposed theoretically, which indicates that the drop size is a critical factor influencing the supercooled heat exchange and effective heat transfer duration between the film/substrate interface. On the basis of the present experimental data and theoretical analysis, an impinging heating model is developed and applied to typical SLD cases. The model behaves as anticipated, which underlines the wide applicability to SLD icing problems in related fields.

  6. Effects of thermodynamic inhibitors on the dissociation of methane hydrate: a molecular dynamics study.

    PubMed

    Yagasaki, Takuma; Matsumoto, Masakazu; Tanaka, Hideki

    2015-12-28

    We investigate the effects of methanol and NaCl, which are known as thermodynamic hydrate inhibitors, on the dissociation kinetics of methane hydrate in aqueous solutions by using molecular dynamics simulations. It is shown that the dissociation rate is not constant but changes with time. The dissociation rate in the initial stage is increased by methanol whereas it is decreased by NaCl. This difference arises from the opposite effects of the two thermodynamic inhibitors on the hydration free energy of methane. The dissociation rate of methane hydrate is increased by the formation of methane bubbles in the aqueous phase because the bubbles absorb surrounding methane molecules. It is found that both methanol and NaCl facilitate the bubble formation. However, their mechanisms are completely different from each other. The presence of ions enhances the hydrophobic interactions between methane molecules. In addition, the ions in the solution cause a highly non-uniform distribution of dissolved methane molecules. These two effects result in the easy formation of bubbles in the NaCl solution. In contrast, methanol assists the bubble formation because of its amphiphilic character. PMID:26587576

  7. Descriptive thermodynamics

    NASA Astrophysics Data System (ADS)

    Ford, David; Huntsman, Steven

    2006-06-01

    Thermodynamics (in concert with its sister discipline, statistical physics) can be regarded as a data reduction scheme based on partitioning a total system into a subsystem and a bath that weakly interact with each other. Whereas conventionally, the systems investigated require this form of data reduction in order to facilitate prediction, a different problem also occurs, in the context of communication networks, markets, etc. Such “empirically accessible” systems typically overwhelm observers with the sort of information that in the case of (say) a gas is effectively unobtainable. What is required for such complex interacting systems is not prediction (this may be impossible when humans besides the observer are responsible for the interactions) but rather, description as a route to understanding. Still, the need for a thermodynamical data reduction scheme remains. In this paper, we show how an empirical temperature can be computed for finite, empirically accessible systems, and further outline how this construction allows the age-old science of thermodynamics to be fruitfully applied to them.

  8. Iron(III) Thiocyanate Revisited: A Physical Chemistry Equilibrium Lab Incorporating Ionic Strength Effects

    NASA Astrophysics Data System (ADS)

    Cobb, Cathy L.; Love, G. A.

    1998-01-01

    A physical chemistry laboratory exercise is presented in which the thermodynamic equilibrium constant for Fe3+ + SCN- <--> Fe(SCN)2+ in 0.5 M acid is calculated from the experimentally observed equilibrium constant and activity coefficients generated by the Davies extension of the Debye-Hückel theory.

  9. Many-Body Effects on the Thermodynamics of Fluids, Mixtures, and Nanoconfined Fluids.

    PubMed

    Desgranges, Caroline; Delhommelle, Jerome

    2015-11-10

    Using expanded Wang-Landau simulations, we show that taking into account the many-body interactions results in sharp changes in the grand-canonical partition functions of single-component systems, binary mixtures, and nanoconfined fluids. The many-body contribution, modeled with a 3-body Axilrod-Teller-Muto term, results in shifts toward higher chemical potentials of the phase transitions from low-density phases to high-density phases and accounts for deviations of more than, e.g., 20% of the value of the partition function for a single-component liquid. Using the statistical mechanics formalism, we analyze how this contribution has a strong impact on some properties (e.g., pressure, coexisting densities, and enthalpy) and a moderate impact on others (e.g., Gibbs or Helmholtz free energies). We also characterize the effect of the 3-body terms on adsorption isotherms and adsorption thermodynamic properties, thereby providing a full picture of the effect of the 3-body contribution on the thermodynamics of nanoconfined fluids. PMID:26574329

  10. Effect of chain stiffness on structural and thermodynamic properties of polymer melts

    NASA Astrophysics Data System (ADS)

    Luettmer-Strathmann, Jutta

    2008-03-01

    Static and dynamic properties of polymers are affected by the stiffness of the chains. In this work, we investigate structural and thermodynamic properties of a lattice model for semiflexible polymer chains. The model is an extension of Shaffer's bond- fluctuation model [1] and includes attractive interactions between monomers and an adjustable bending penalty that determines the Kuhn segment length. For isolated chains, a competition between monomer-monomer interactions and bending penalties determines the chain conformations at low temperatures. For dense melts, packing effects play an important role in the structure and thermodynamics of the polymeric liquid. In order to investigate static properties as a function of temperature and chain stiffness, we perform Wang-Landau type simulations and construct densities of states over the two- dimensional state space of monomer-monomer and bending contributions to the internal energy. In addition, we present first results from an algorithm for equation-of-state effects in lattice models. [1] J. S. Shaffer, J. Chem. Phys. 101, 4205 (1994).

  11. Differential Effects of Hydrophobic Core Packing Residues for Thermodynamic and Mechanical Stability of a Hyperthermophilic Protein.

    PubMed

    Tych, Katarzyna M; Batchelor, Matthew; Hoffmann, Toni; Wilson, Michael C; Hughes, Megan L; Paci, Emanuele; Brockwell, David J; Dougan, Lorna

    2016-07-26

    Proteins from organisms that have adapted to environmental extremes provide attractive systems to explore and determine the origins of protein stability. Improved hydrophobic core packing and decreased loop-length flexibility can increase the thermodynamic stability of proteins from hyperthermophilic organisms. However, their impact on protein mechanical stability is not known. Here, we use protein engineering, biophysical characterization, single-molecule force spectroscopy (SMFS), and molecular dynamics (MD) simulations to measure the effect of altering hydrophobic core packing on the stability of the cold shock protein TmCSP from the hyperthermophilic bacterium Thermotoga maritima. We make two variants of TmCSP in which a mutation is made to reduce the size of aliphatic groups from buried hydrophobic side chains. In the first, a mutation is introduced in a long loop (TmCSP L40A); in the other, the mutation is introduced on the C-terminal β-strand (TmCSP V62A). We use MD simulations to confirm that the mutant TmCSP L40A shows the most significant increase in loop flexibility, and mutant TmCSP V62A shows greater disruption to the core packing. We measure the thermodynamic stability (ΔGD-N) of the mutated proteins and show that there is a more significant reduction for TmCSP L40A (ΔΔG = 63%) than TmCSP V62A (ΔΔG = 47%), as might be expected on the basis of the relative reduction in the size of the side chain. By contrast, SMFS measures the mechanical stability (ΔG*) and shows a greater reduction for TmCSP V62A (ΔΔG* = 8.4%) than TmCSP L40A (ΔΔG* = 2.5%). While the impact on the mechanical stability is subtle, the results demonstrate the power of tuning noncovalent interactions to modulate both the thermodynamic and mechanical stability of a protein. Such understanding and control provide the opportunity to design proteins with optimized thermodynamic and mechanical properties. PMID:27338140

  12. Thermodynamic analysis and experimental study of the effect of atmospheric pressure on the ice point

    NASA Astrophysics Data System (ADS)

    Harvey, A. H.; McLinden, M. O.; Tew, W. L.

    2013-09-01

    We present a detailed thermodynamic analysis of the temperature of the ice point as a function of atmospheric pressure. This analysis makes use of accurate international standards for the properties of water and ice, and of available high-accuracy data for the Henry's constants of atmospheric gases in liquid water. The result is an ice point of 273.150 019(5) K at standard atmospheric pressure, with higher ice-point temperatures (varying nearly linearly with pressure) at lower pressures. The effect of varying ambient CO2 concentration is analyzed and found to be significant in comparison to other uncertainties in the model. The thermodynamic analysis is compared with experimental measurements of the temperature difference between the ice point and the triple point of water performed at elevations ranging from 145 m to 4302 m, with atmospheric pressures from 101 kPa to 60 kPa. At the request of the authors and the Proceedings Editor the above article has been replaced with a corrected version. The original PDF file supplied to AIP Publishing contained several equations with incorrect/missing characters resulting from processes used to create the PDF file. The article has been replaced and the equations now display correctly.

  13. Effective rates from thermodynamically consistent coarse-graining of models for molecular motors with probe particles

    NASA Astrophysics Data System (ADS)

    Zimmermann, Eva; Seifert, Udo

    2015-02-01

    Many single-molecule experiments for molecular motors comprise not only the motor but also large probe particles coupled to it. The theoretical analysis of these assays, however, often takes into account only the degrees of freedom representing the motor. We present a coarse-graining method that maps a model comprising two coupled degrees of freedom which represent motor and probe particle to such an effective one-particle model by eliminating the dynamics of the probe particle in a thermodynamically and dynamically consistent way. The coarse-grained rates obey a local detailed balance condition and reproduce the net currents. Moreover, the average entropy production as well as the thermodynamic efficiency is invariant under this coarse-graining procedure. Our analysis reveals that only by assuming unrealistically fast probe particles, the coarse-grained transition rates coincide with the transition rates of the traditionally used one-particle motor models. Additionally, we find that for multicyclic motors the stall force can depend on the probe size. We apply this coarse-graining method to specific case studies of the F1-ATPase and the kinesin motor.

  14. Effects of dispersion forces on the structure and thermodynamics of fluid krypton

    PubMed

    Jakse; Bomont; Charpentier; Bretonnet

    2000-09-01

    Semianalytical and numerical calculations are performed to predict the structural and thermodynamic properties of low-density Kr fluid. Assuming that the interatomic forces can be modelled by a pairwise potential plus the three-body Axilrod-Teller potential, two different routes are explored. The first one is based on the hybridized mean spherical approximation integral equation of the theory of liquids and the second one uses large-scale molecular dynamics (MD). Algorithms for MD simulation are constructed on parallel machines to reduce the amount of computer time induced by the calculations of the three-body forces and the pair-correlation function. Our results obtained with the two methods mentioned above are in quite good agreement with the recent small-angle neutron-scattering experiments [Formisano et al., Phys. Rev. Lett. 79, 221 (1997); Benmore et al., J. Phys.: Condens. Matter 11, 3091 (1999)]. Moreover, the reliability of the asymptotic form of the integral equation is assessed for the specific case of dispersion forces including the three-body contributions, by an analysis at low wave vector and low density. It is seen that the effects of the Axilrod-Teller triple-dipole potential cannot be ignored to describe the structure and the thermodynamic properties of fluid krypton even at low density. PMID:11088867

  15. Thermodynamic properties of non-conformal soft-sphere fluids with effective hard-sphere diameters.

    PubMed

    Rodríguez-López, Tonalli; del Río, Fernando

    2012-01-28

    In this work we study a set of soft-sphere systems characterised by a well-defined variation of their softness. These systems represent an extension of the repulsive Lennard-Jones potential widely used in statistical mechanics of fluids. This type of soft spheres is of interest because they represent quite accurately the effective intermolecular repulsion in fluid substances and also because they exhibit interesting properties. The thermodynamics of the soft-sphere fluids is obtained via an effective hard-sphere diameter approach that leads to a compact and accurate equation of state. The virial coefficients of soft spheres are shown to follow quite simple relationships that are incorporated into the equation of state. The approach followed exhibits the rescaling of the density that produces a unique equation for all systems and temperatures. The scaling is carried through to the level of the structure of the fluids. PMID:22158949

  16. Thermodynamic Self-Limiting Growth of Heteroepitaxial Islands Induced by Nonlinear Elastic Effect.

    PubMed

    Hu, Hao; Niu, Xiaobin; Liu, Feng

    2016-06-01

    We investigate nonlinear elastic effect (NLEF) on the growth of heteroepitaxial islands, a topic of both scientific and technological significance for their applications as quantum dots. We show that the NLEF induces a thermodynamic self-limiting growth mechanism that hinders the strain relaxation of coherent island beyond a maximum size, which is in contrast to indefinite strain relaxation with increasing island size in the linear elastic regime. This self-limiting growth effect shows a strong dependence on the island facet angle, which applies also to islands inside pits patterned in a substrate surface with an additional dependence on the pit inclination angle. Consequently, primary islands nucleate and grow first in the pits and then secondary islands nucleate at the rim around the pits after the primary islands reach the self-limited maximum size. Our theory sheds new lights on understanding the heteroepitaxial island growth and explains a number of past and recent experimental observations. PMID:27203611

  17. Thermodynamic Study on Plasma Expansion along a Divergent Magnetic Field

    NASA Astrophysics Data System (ADS)

    Zhang, Yunchao; Charles, Christine; Boswell, Rod

    2016-01-01

    Thermodynamic properties are revisited for electrons that are governed by nonlocal electron energy probability functions in a plasma of low collisionality. Measurements in a laboratory helicon double layer experiment have shown that the effective electron temperature and density show a polytropic correlation with an index of γe=1.17 ±0.02 along the divergent magnetic field, implying a nearly isothermal plasma (γe=1 ) with heat being brought into the system. However, the evolution of electrons along the divergent magnetic field is essentially an adiabatic process, which should have a γe=5/3 . The reason for this apparent contradiction is that the nearly collisionless plasma is very far from local thermodynamic equilibrium and the electrons behave nonlocally. The corresponding effective electron enthalpy has a conservation relation with the potential energy, which verifies that there is no heat transferred into the system during the electron evolution. The electrons are shown in nonlocal momentum equilibrium under the electric field and the gradient of the effective electron pressure. The convective momentum of ions, which can be assumed as a cold species, is determined by the effective electron pressure and the effective electron enthalpy is shown to be the source for ion acceleration. For these nearly collisionless plasmas, the use of traditional thermodynamic concepts can lead to very erroneous conclusions regarding the thermal conductivity.

  18. Thermodynamic Study on Plasma Expansion along a Divergent Magnetic Field.

    PubMed

    Zhang, Yunchao; Charles, Christine; Boswell, Rod

    2016-01-15

    Thermodynamic properties are revisited for electrons that are governed by nonlocal electron energy probability functions in a plasma of low collisionality. Measurements in a laboratory helicon double layer experiment have shown that the effective electron temperature and density show a polytropic correlation with an index of γ_{e}=1.17±0.02 along the divergent magnetic field, implying a nearly isothermal plasma (γ_{e}=1) with heat being brought into the system. However, the evolution of electrons along the divergent magnetic field is essentially an adiabatic process, which should have a γ_{e}=5/3. The reason for this apparent contradiction is that the nearly collisionless plasma is very far from local thermodynamic equilibrium and the electrons behave nonlocally. The corresponding effective electron enthalpy has a conservation relation with the potential energy, which verifies that there is no heat transferred into the system during the electron evolution. The electrons are shown in nonlocal momentum equilibrium under the electric field and the gradient of the effective electron pressure. The convective momentum of ions, which can be assumed as a cold species, is determined by the effective electron pressure and the effective electron enthalpy is shown to be the source for ion acceleration. For these nearly collisionless plasmas, the use of traditional thermodynamic concepts can lead to very erroneous conclusions regarding the thermal conductivity. PMID:26824545

  19. Towards a probabilistic definition of entropy: An investigation of the effects of a new curriculum on students' understanding of thermodynamics

    NASA Astrophysics Data System (ADS)

    Colon-Garcia, Evy B.

    Thermodynamics is a vital tool in understanding why reactions happen; nevertheless, it is often considered a difficult topic. Prior studies have shown that students struggle with fundamental thermodynamic concepts such as entropy, enthalpy and Gibbs energy even in upper level physical chemistry courses. Thermodynamics, as a general chemistry topic, can be more math-intensive than other topics such as bonding or intermolecular forces. As a result, it is possible for students to get lost in the algorithms and overlook the important underlying theoretical concepts. Students' difficulties in understanding thermodynamics may be contributing to their inability to explain phenomena such as phase changes and manipulations of equilibrium systems. Current chemistry curricula split the thermodynamic chapters over a span of two semesters as well as splitting it over different units. This division fails to make explicit the connection between Enthalpy, Entropy and Gibbs Energy and how they affect how and why every reaction or process happens. The reason for this division of topics is not based on any educational research rather than opinions as to what will not overwhelm the students. Additionally, students who take only one semester of General Chemistry will leave without being instructed in what is considered to be one of the most fundamental concepts in Chemistry, Thermodynamics. Chemistry, Life, the Universe and Everything (CLUE) is a general chemistry course developed with the explicit goal of addressing the major obstacles that inhibit students from acquiring an appreciation and mastery of the chemical principles upon which other sciences depend. Using a control and treatment group, the effectiveness of this new curriculum was evaluated for two main aspects: 1. What is students' understanding of entropy?, 2. Can an alternative instructional approach to teaching Thermodynamics (Chemistry, Life, the Universe and Everything - CLUE) improve students' understanding of Entropy

  20. Temperature of systems out of thermodynamic equilibrium

    NASA Astrophysics Data System (ADS)

    Garden, J.-L.; Richard, J.; Guillou, H.

    2008-07-01

    Two phenomenological approaches are currently used in the study of the vitreous state. One is based on the concept of fictive temperature introduced by Tool [J. Res. Natl. Bur. Stand. 34, 199 (1945)] and recently revisited by Nieuwenhuizen [Phys. Rev. Lett. 80, 5580 (1998)]. The other is based on the thermodynamics of irreversible processes initiated by De Donder at the beginning of the last century [L'Affinité (Gauthier-Villars, Paris, 1927)] and recently used by Möller et al. for a thorough study of the glass transition [J. Chem. Phys. 125, 094505 (2006)]. This latter approach leads to the possibility of describing the glass transition by means of the freezing-in of one or more order parameters connected to the internal structural degrees of freedom involved in the vitrification process. In this paper, the equivalence of the two preceding approaches is demonstrated, not only for glasses but in a very general way for any system undergoing an irreversible transformation. This equivalence allows the definition of an effective temperature for all systems departed from equilibrium generating a positive amount of entropy. In fact, the initial fictive temperature concept of Tool leads to the generalization of the notion of temperature for systems out of thermodynamic equilibrium, for which glasses are just particular cases.

  1. Ancrod revisited: viscoelastic analyses of the effects of Calloselasma rhodostoma venom on plasma coagulation and fibrinolysis.

    PubMed

    Nielsen, Vance G

    2016-08-01

    Fibrinogen depletion via catalysis by snake venom enzymes as a therapeutic strategy to prevent or treat thrombotic disorders was utilized for over four decades, with ancrod being the quintessential agent. However, ancrod eventually was found to not be of clinical utility in large scale stroke trial, resulting in the eventual discontinuation of the administration of the drug for any indication. It was hypothesized that ancrod, possessing thrombin-like activity, may have unappreciated robust coagulation kinetics. Using thrombelastographic methods, a comparison of equivalent tissue factor initiated thrombin generation and Calloselasma rhodostoma venom (rich in ancrod activity) on plasmatic coagulation kinetics was performed. The venom resulted in thrombi that formed nearly twice as fast compared to thrombin formed clots, and there was no difference in fibrinolytic kinetics initiated by tissue-type plasminogen activator. In plasma containing iron and carbon monoxide modified fibrinogen, which may be found in patients at risk of stroke, the coagulation kinetic differences observed with venom was still more vigorous than that seen with thrombin. These phenomena may provide insight into the clinical failure of ancrod, and may serve as an impetus to revisit the concept of fibrinogen depletion via fibrinogenolytic enzymes, not those with thrombin-like activity. PMID:26905070

  2. Perceived parenting style and adolescent adjustment: revisiting directions of effects and the role of parental knowledge.

    PubMed

    Kerr, Margaret; Stattin, Håkan; Ozdemir, Metin

    2012-11-01

    In the present research on parenting and adolescent behavior, there is much focus on reciprocal, bidirectional, and transactional processes, but parenting-style research still adheres to a unidirectional perspective in which parents affect youth behavior but are unaffected by it. In addition, many of the most cited parenting-style studies have used measures of parental behavioral control that are questionable because they include measures of parental knowledge. The goals of this study were to determine whether including knowledge items might have affected results of past studies and to test the unidirectional assumption. Data were from 978 adolescents participating in a longitudinal study. Parenting-style and adolescent adjustment measures at 2 time points were used, with a 2-year interval between time points. A variety of internal and external adjustment measures were used. Results showed that including knowledge items in measures of parental behavioral control elevated links between behavioral control and adjustment. Thus, the results and conclusions of many of the most highly cited studies are likely to have been stronger than if the measures had focused strictly on parental behavior. In addition, adolescent adjustment predicted changes in authoritative and neglectful parenting styles more robustly than these styles predicted changes in adolescent adjustment. Adolescent adjustment also predicted changes in authoritativeness more robustly than authoritativeness predicted changes in adjustment. Thus, parenting style cannot be seen as independent of the adolescent. In summary, both the theoretical premises of parenting-style research and the prior findings should be revisited. PMID:22448987

  3. REVISITING THE FIRST GALAXIES: THE EFFECTS OF POPULATION III STARS ON THEIR HOST GALAXIES

    SciTech Connect

    Muratov, Alexander L.; Gnedin, Oleg Y.; Zemp, Marcel; Gnedin, Nickolay Y.

    2013-08-01

    We revisit the formation and evolution of the first galaxies using new hydrodynamic cosmological simulations with the adaptive refinement tree code. Our simulations feature a recently developed model for H{sub 2} formation and dissociation, and a star formation recipe that is based on molecular rather than atomic gas. Here, we develop and implement a recipe for the formation of metal-free Population III (Pop III) stars in galaxy-scale simulations that resolve primordial clouds with sufficiently high density. We base our recipe on the results of prior zoom-in simulations that resolved the protostellar collapse in pre-galactic objects. We find the epoch during which Pop III stars dominated the energy and metal budget of the first galaxies to be short-lived. Galaxies that host Pop III stars do not retain dynamical signatures of their thermal and radiative feedback for more than 10{sup 8} years after the lives of the stars end in pair-instability supernovae, even when we consider the maximum reasonable efficiency of the feedback. Though metals ejected by the supernovae can travel well beyond the virial radius of the host galaxy, they typically begin to fall back quickly, and do not enrich a large fraction of the intergalactic medium. Galaxies with a total mass in excess of 3 Multiplication-Sign 10{sup 6} M{sub Sun} re-accrete most of their baryons and transition to metal-enriched Pop II star formation.

  4. Thermodynamic and kinetic stability of zwitterionic histidine: Effects of gas phase hydration

    NASA Astrophysics Data System (ADS)

    Lee, Sung-Sik; Kim, Ju-Young; Han, Yuna; Shim, Hyun-Jin; Lee, Sungyul

    2015-09-01

    We present calculations for histidine-(H2O)n (n = 0-6) to examine the effects of micro-hydrating water molecules on the relative stability of the zwitterionic vs. canonical forms of histidine. We calculate the structures and Gibbs free energies of the conformers at wB97XD/6-311++G(d,p) level of theory. We find that six water molecules are required to produce the thermodynamically stable histidine zwitterion. By calculating the barriers of canonical ↔ zwitterionic transformation, we predict that both the most stable canonical and zwitterionic forms of histidine-(H2O)6 may be observed in low temperature gas phase environment.

  5. Effect of drying methods on the moisture sorption isotherms and thermodynamic properties of mint leaves.

    PubMed

    Dalgıç, Ali Coşkun; Pekmez, Hatice; Belibağlı, Kadir Bülent

    2012-08-01

    Mint leaves were dried by three different types of dryers, namely; tray, freeze and distributed (indirect)-type solar dryer. Sorption isotherms of fresh, solar, tray and freeze dried mint were determined at temperatures of 15 °C, 25 °C and 35 °C over a range of relative humidities (10-90%). The effect of drying method on the water sorption isotherms of dried mint samples was evaluated. Experimental data were used to determine the best models for predicting the moisture sorption content of mint. Among nine sorption models tested, Peleg, GAB, Lewicki and modified Mizrahi equations gave the best fit to experimental data. The sorption data were analyzed for determination of monolayer moisture content, density of sorbed water, number of adsorbed monolayers, percent bound water, and surface area of adsorbance. The experimental data were also used to determine some thermodynamic properties of mint. PMID:23904652

  6. Tabulation and summary of thermodynamic effects data for developed cavitation on ogive-nosed bodies

    NASA Technical Reports Server (NTRS)

    Holl, J. W.; Billet, M. L.; Weir, D. S.

    1978-01-01

    Thermodynamic effects data for developed cavitation on zero and quarter caliber ogives in Freon 113 and water are tabulated and summarized. These data include temperature depression (delta T), flow coefficient (C sub Q), and various geometrical characteristics of the cavity. For the delta T tests, the free-stream temperature varied from 35 C to 95 C in Freon 113 and from 60 C to 125 C in water for a velocity range of 19.5 m/sec to 36.6 m/sec. Two correlations of the delta T data by the entrainment method are presented. These correlations involve different combinations of the Nusselt, Reynolds, Froude, Weber, and Peclet numbers and dimensionless cavity length.

  7. The effect of substrate on thermodynamic and kinetic anisotropies in atomic thin films

    SciTech Connect

    Haji-Akbari, Amir; Debenedetti, Pablo G.

    2014-07-14

    Glasses have a wide range of technological applications. The recent discovery of ultrastable glasses that are obtained by depositing the vapor of a glass-forming liquid onto the surface of a cold substrate has sparked renewed interest in the effects of confinements on physicochemical properties of liquids and glasses. Here, we use molecular dynamics simulations to study the effect of substrate on thin films of a model glass-forming liquid, the Kob-Andersen binary Lennard-Jones system, and compute profiles of several thermodynamic and kinetic properties across the film. We observe that the substrate can induce large oscillations in profiles of thermodynamic properties such as density, composition, and stress, and we establish a correlation between the oscillations in total density and the oscillations in normal stress. We also demonstrate that the kinetic properties of an atomic film can be readily tuned by changing the strength of interactions between the substrate and the liquid. Most notably, we show that a weakly attractive substrate can induce the emergence of a highly mobile region in its vicinity. In this highly mobile region, structural relaxation is several times faster than in the bulk, and the exploration of the potential energy landscape is also more efficient. In the subsurface region near a strongly attractive substrate, however, the dynamics is decelerated and the sampling of the potential energy landscape becomes less efficient than the bulk. We explain these two distinct behaviors by establishing a correlation between the oscillations in kinetic properties and the oscillations in lateral stress. Our findings offer interesting opportunities for designing better substrates for the vapor deposition process or developing alternative procedures for situations where vapor deposition is not feasible.

  8. Testing the Effects of Helium Pressurant on Thermodynamic Vent System Performance with Liquid Hydrogen

    NASA Technical Reports Server (NTRS)

    Flachbart, R. H.; Hastings, L. J.; Hedayat, A.; Nelson, S.; Tucker, S.

    2006-01-01

    In support of the development of a zero gravity pressure control capability for liquid hydrogen, testing was conducted at the Marshall Space Flight Center using the Multipurpose Hydrogen Test Bed (MHTB) to evaluate the effects of helium pressurant on the performance of a spray bar thermodynamic vent system (TVS). Fourteen days of testing was performed in August - September 2005, with an ambient heat leak of about 70-80 watts and tank fill levels of 90%, 50%, and 25%. The TVS successfully controlled the tank pressure within a +/- 3.45 kPa (+/- 0.5 psi) band with various helium concentration levels in the ullage. Relative to pressure control with an "all hydrogen" ullage, the helium presence resulted in 10 to 30 per cent longer pressure reduction durations, depending on the fill level, during the mixing/venting phase of the control cycle. Additionally, the automated control cycle was based on mixing alone for pressure reduction until the pressure versus time slope became positive, at which time the Joule-Thomson vent was opened. Testing was also conducted to evaluate thermodynamic venting without the mixer operating, first with liquid then with vapor at the recirculation line inlet. Although ullage stratification was present, the ullage pressure was successfully controlled without the mixer operating. Thus, if vapor surrounded the pump inlet in a reduced gravity situation, the ullage pressure can still be controlled by venting through the TVS Joule Thomson valve and heat exchanger. It was evident that the spray bar configuration, which extends almost the entire length of the tank, enabled significant thermal energy removal from the ullage even without the mixer operating. Details regarding the test setup and procedures are presented in the paper. 1

  9. Dissolved Divalent Metal and pH Effects on Amino Acid Polymerization: A Thermodynamic Evaluation

    NASA Astrophysics Data System (ADS)

    Kitadai, Norio

    2016-06-01

    Polymerization of amino acids is a fundamentally important step for the chemical evolution of life. Nevertheless, its response to changing environmental conditions has not yet been well understood because of the lack of reliable quantitative information. For thermodynamics, detailed prediction over diverse combinations of temperature and pH has been made only for a few amino acid-peptide systems. This study used recently reported thermodynamic dataset for the polymerization of the simplest amino acid "glycine (Gly)" to its short peptides (di-glycine and tri-glycine) to examine chemical and structural characteristics of amino acids and peptides that control the temperature and pH dependence of polymerization. Results showed that the dependency is strongly controlled by the intramolecular distance between the amino and carboxyl groups in an amino acid structure, although the side-chain group role is minor. The polymerization behavior of Gly reported earlier in the literature is therefore expected to be a typical feature for those of α-amino acids. Equilibrium calculations were conducted to examine effects of dissolved metals as a function of pH on the monomer-polymer equilibria of Gly. Results showed that metals shift the equilibria toward the monomer side, particularly at neutral and alkaline pH. Metals that form weak interaction with Gly (e.g., Mg2+) have no noticeable influence on the polymerization, although strong interaction engenders significant decrease of the equilibrium concentrations of Gly peptides. Considering chemical and structural characteristics of Gly and Gly peptides that control their interactions with metals, it can be expected that similar responses to the addition of metals are applicable in the polymerization of neutral α-amino acids. Neutral and alkaline aqueous environments with dissolved metals having high affinity with neutral α-amino acids (e.g., Cu2+) are therefore not beneficial places for peptide bond formation on the primitive

  10. Thermodynamic Effect of Platinum Addition to beta-NiAl: An Initial Investigation

    NASA Technical Reports Server (NTRS)

    2005-01-01

    An initial investigation was conducted to determine the effect of platinum addition on the activities of aluminum and nickel in beta-NiAl(Pt) over the temperature range 1354 to 1692 K. These measurements were made with a multiple effusion-cell configured mass spectrometer (multi-cell KEMS). The results of this study show that Pt additions act to decreased alpha(Al) and increased the alpha(Ni) in beta-NiAl(Pt) for constant X(sub Ni)/X(sub Al) approx. = 1.13, while at constant X(sub Al) the affect of Pt on Al is greatly reduced. The measured partial enthalpies of mixing indicate Al-atoms have a strong self interaction while Ni- and Pt-atoms in have similar interactions with Al-atoms. Conversely the binding of Ni-atoms in beta-NiAl decreases with Pt addition independent of Al concentration. These initial results prove the technique can be applied to the Ni-Al-Pt system but more activity measurements are required to fully understand the thermodynamics of this system and how Pt additions improved the scaling behavior of nickel-based superalloys. In addition, with the choice of a suitable oxide material for the effusion-cell, the "closed" isothermal nature of the effusion-cell allows the direct investigation of an alloy-oxide equilibrium which resembles the "local-equilibrium" description of the metal-scale interface observed during high temperature oxidation. It is proposed that with an Al(l) + Al2O3(s) experimental reference state together with the route measurement of the relative partial-pressures of Al(g) and Al2O(g) allows the activities of O and Al2O3 to be determined along with the activities of Ni and Al. These measurements provide a direct method of investigating the thermodynamics of the metal-scale interface of a TGO-scale.

  11. Effects of Alloying on Nanoscale Grain Growth in Substitutional Binary Alloy System: Thermodynamics and Kinetics

    NASA Astrophysics Data System (ADS)

    Peng, Haoran; Chen, Yuzeng; Liu, Feng

    2015-11-01

    Applying the regular solution model, the Gibbs free energy of mixing for substitutional binary alloy system was constructed. Then, thermodynamic and kinetic parameters, e.g., driving force and solute drag force, controlling nanoscale grain growth of substitutional binary alloy systems were derived and compared to their generally accepted definitions and interpretations. It is suggested that for an actual grain growth process, the classical driving force P = γ/D ( γ the grain boundary (GB) energy, D the grain size) should be replaced by a new expression, i.e., P^' = γ /D - Δ P . Δ P represents the energy required to adjust nonequilibrium solute distribution to equilibrium solute distribution, which is equivalent to the generally accepted solute drag force impeding GB migration. By incorporating the derived new driving force for grain growth into the classical grain growth model, the reported grain growth behaviors of nanocrystalline Fe-4at. pct Zr and Pd-19at. pct Zr alloys were analyzed. On this basis, the effect of thermodynamic and kinetic parameters ( i.e., P, Δ P and the GB mobility ( M GB)) on nanoscale grain growth, were investigated. Upon grain growth, the decrease of P is caused by the reduction of γ as a result of solute segregation in GBs; the decrease of Δ P is, however, due to the decrease of grain growth velocity; whereas the decrease of M GB is attributed to the enhanced difference of solute molar fractions between the bulk and the GBs as well as the increased activation energy for GB diffusion.

  12. Structural and Thermodynamic Effects of Macrocyclization in HCV NS3/4A Inhibitor MK-5172.

    PubMed

    Soumana, Djadé I; Kurt Yilmaz, Nese; Prachanronarong, Kristina L; Aydin, Cihan; Ali, Akbar; Schiffer, Celia A

    2016-04-15

    Recent advances in direct-acting antivirals against Hepatitis C Virus (HCV) have led to the development of potent inhibitors, including MK-5172, that target the viral NS3/4A protease with relatively low susceptibility to resistance. MK-5172 has a P2-P4 macrocycle and a unique binding mode among current protease inhibitors where the P2 quinoxaline packs against the catalytic residues H57 and D81. However, the effect of macrocyclization on this binding mode is not clear, as is the relation between macrocyclization, thermodynamic stabilization, and susceptibility to the resistance mutation A156T. We have determined high-resolution crystal structures of linear and P1-P3 macrocyclic analogs of MK-5172 bound to WT and A156T protease and compared these structures, their molecular dynamics, and experimental binding thermodynamics to the parent compound. We find that the "unique" binding mode of MK-5172 is conserved even when the P2-P4 macrocycle is removed or replaced with a P1-P3 macrocycle. While beneficial to decreasing the entropic penalty associated with binding, the constraint exerted by the P2-P4 macrocycle prevents efficient rearrangement to accommodate the A156T mutation, a deficit alleviated in the linear and P1-P3 analogs. Design of macrocyclic inhibitors against NS3/4A needs to achieve the best balance between exerting optimal conformational constraint for enhancing potency, fitting within the substrate envelope and allowing adaptability to be robust against resistance mutations. PMID:26682473

  13. Thermodynamic Diagrams

    NASA Astrophysics Data System (ADS)

    Chaston, Scot

    1999-02-01

    Thermodynamic data such as equilibrium constants, standard cell potentials, molar enthalpies of formation, and standard entropies of substances can be a very useful basis for an organized presentation of knowledge in diverse areas of applied chemistry. Thermodynamic data can become particularly useful when incorporated into thermodynamic diagrams that are designed to be easy to recall, to serve as a basis for reconstructing previous knowledge, and to determine whether reactions can occur exergonically or only with the help of an external energy source. Few students in our chemistry-based courses would want to acquire the depth of knowledge or rigor of professional thermodynamicists. But they should nevertheless learn how to make good use of thermodynamic data in their professional occupations that span the chemical, biological, environmental, and medical laboratory fields. This article discusses examples of three thermodynamic diagrams that have been developed for this purpose. They are the thermodynamic energy account (TEA), the total entropy scale, and the thermodynamic scale diagrams. These diagrams help in the teaching and learning of thermodynamics by bringing the imagination into the process of developing a better understanding of abstract thermodynamic functions, and by allowing the reader to keep track of specialist thermodynamic discourses in the literature.

  14. High-throughput protein precipitation and hydrophobic interaction chromatography: salt effects and thermodynamic interrelation.

    PubMed

    Nfor, Beckley K; Hylkema, Nienke N; Wiedhaup, Koenraad R; Verhaert, Peter D E M; van der Wielen, Luuk A M; Ottens, Marcel

    2011-12-01

    Salt-induced protein precipitation and hydrophobic interaction chromatography (HIC) are two widely used methods for protein purification. In this study, salt effects in protein precipitation and HIC were investigated for a broad combination of proteins, salts and HIC resins. Interrelation between the critical thermodynamic salting out parameters in both techniques was equally investigated. Protein precipitation data were obtained by a high-throughput technique employing 96-well microtitre plates and robotic liquid handling technology. For the same protein-salt combinations, isocratic HIC experiments were performed using two or three different commercially available stationary phases-Phenyl Sepharose low sub, Butyl Sepharose and Resource Phenyl. In general, similar salt effects and deviations from the lyotropic series were observed in both separation methods, for example, the reverse Hofmeister effect reported for lysozyme below its isoelectric point and at low salt concentrations. The salting out constant could be expressed in terms of the preferential interaction parameter in protein precipitation, showing that the former is, in effect, the net result of preferential interaction of a protein with water molecules and salt ions in its vicinity. However, no general quantitative interrelation was found between salting out parameters or the number of released water molecules in protein precipitation and HIC. In other words, protein solubility and HIC retention factor could not be quantitatively interrelated, although for some proteins, regular trends were observed across the different resins and salt types. PMID:21868020

  15. Effect of heating strategies on whey protein denaturation--Revisited by liquid chromatography quadrupole time-of-flight mass spectrometry.

    PubMed

    Akkerman, M; Rauh, V M; Christensen, M; Johansen, L B; Hammershøj, M; Larsen, L B

    2016-01-01

    Previous standards in the area of effect of heat treatment processes on milk protein denaturation were based primarily on laboratory-scale analysis and determination of denaturation degrees by, for example, electrophoresis. In this study, whey protein denaturation was revisited by pilot-scale heating strategies and liquid chromatography quadrupole time-of-flight mass spectrometer (LC/MC Q-TOF) analysis. Skim milk was heat treated by the use of 3 heating strategies, namely plate heat exchanger (PHE), tubular heat exchanger (THE), and direct steam injection (DSI), under various heating temperatures (T) and holding times. The effect of heating strategy on the degree of denaturation of β-lactoglobulin and α-lactalbumin was determined using LC/MC Q-TOF of pH 4.5-soluble whey proteins. Furthermore, effect of heating strategy on the rennet-induced coagulation properties was studied by oscillatory rheometry. In addition, rennet-induced coagulation of heat-treated micellar casein concentrate subjected to PHE was studied. For skim milk, the whey protein denaturation increased significantly as T and holding time increased, regardless of heating method. High denaturation degrees were obtained for T >100°C using PHE and THE, whereas DSI resulted in significantly lower denaturation degrees, compared with PHE and THE. Rennet coagulation properties were impaired by increased T and holding time regardless of heating method, although DSI resulted in less impairment compared with PHE and THE. No significant difference was found between THE and PHE for effect on rennet coagulation time, whereas the curd firming rate was significantly larger for THE compared with PHE. Micellar casein concentrate possessed improved rennet coagulation properties compared with skim milk receiving equal heat treatment. PMID:26506552

  16. Thermodynamics and Cloud Radiative Effect from the First Year of GoAmazon

    NASA Technical Reports Server (NTRS)

    Collow, Allie Marquardt; Miller, Mark; Trabachino, Lynne

    2015-01-01

    Deforestation is an ongoing concern for the Amazon Rainforest of Brazil and associated changes to the land surface have been hypothesized to alter the climate in the region. A comprehensive set of meteorological observations at the surface and within the lower troposphere above Manacapuru, Brazil and data from the Modern Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2) are used to evaluate the seasonal cycle of cloudiness, thermodynamics, and the radiation budget. While ample moisture is present in the Amazon Rainforest year round, the northward progression of the Hadley circulation during the dry season contributes to a drying of the middle troposphere and inhibits the formation of deep convection. This results in a reduction in cloudiness and precipitation as well as an increase in the height of the lifting condensation level, which is shown to have a negative correlation to the fraction of low clouds. Frequent cloudiness prevents solar radiation from reaching the surface and clouds are often reflective with high values of shortwave cloud radiative effect at the surface and top of the atmosphere. Cloud radiative effect is reduced during the dry season however the dry season surface shortwave cloud radiative effect is still double what is observed during the wet season in other tropical locations. Within the column, the impact of clouds on the radiation budget is more prevalent in the longwave part of the spectrum, with a net warming in the wet season.

  17. Revisiting the role of global SST anomalies and their effects on West African monsoon variability

    NASA Astrophysics Data System (ADS)

    Pomposi, Catherine; Kushnir, Yochanan; Giannini, Alessandra

    2016-04-01

    The West African Monsoon is a significant component of the global monsoon system, delivering the majority of annual precipitation for the Sahel and varying on timescales from seasons to decades and beyond. Much of the internal variability of this system is driven by sea surface temperature (SST) anomalies and their resulting atmospheric teleconnections linking oceanic changes to land-based precipitation. Previous idealized studies have identified the role of particular ocean basins in driving monsoon variations on a number of key timescales, including the Atlantic basin as the main driver behind decadal-scale changes and the Pacific basin for interannual variability. However, understanding of how the monsoon responds to global SSTs remains incomplete because the system can be affected by moisture availability locally as well as tropical atmospheric stability, both of which are influenced by ocean temperatures. Furthermore, the complexity of how the global ocean basins change in relation to one another (what we refer to as superposition of anomalies) can result in Sahel precipitation anomalies that are contrary to what one might posit when considering the state of a single basin alone (e.g. the 2015 El Niño event and a relatively wet Sahel). The aim of this work is to revisit the role of global SSTs in driving Sahel rainfall variability over the recent past using a blending of observations and new model output. We seek to disentangle the state of various basins in combination with each other in driving normal or anomalously dry or wet years, resolving the ways that remote and local ocean forcings affect the movement of convection from the Guinea coast inland and northward into the Sahel, and include the study of circulation and stability components of the atmosphere. Preliminary diagnostic work suggests that varying SST conditions across ocean basins could imprint distinctly different precipitation responses in the Sahel. For example, precipitation anomalies are

  18. Effects of sulfur on lead partitioning during sludge incineration based on experiments and thermodynamic calculations

    SciTech Connect

    Liu, Jing-yong; Huang, Shu-jie; Sun, Shui-yu; Ning, Xun-an; He, Rui-zhe; Li, Xiao-ming; Chen, Tao; Luo, Guang-qian; Xie, Wu-ming; Wang, Yu-jie; Zhuo, Zhong-xu; Fu, Jie-wen

    2015-04-15

    Highlights: • A thermodynamic equilibrium calculation was carried out. • Effects of three types of sulfurs on Pb distribution were investigated. • The mechanism for three types of sulfurs acting on Pb partitioning were proposed. • Lead partitioning and species in bottom ash and fly ash were identified. - Abstract: Experiments in a tubular furnace reactor and thermodynamic equilibrium calculations were conducted to investigate the impact of sulfur compounds on the migration of lead (Pb) during sludge incineration. Representative samples of typical sludge with and without the addition of sulfur compounds were combusted at 850 °C, and the partitioning of Pb in the solid phase (bottom ash) and gas phase (fly ash and flue gas) was quantified. The results indicate that three types of sulfur compounds (S, Na{sub 2}S and Na{sub 2}SO{sub 4}) added to the sludge could facilitate the volatilization of Pb in the gas phase (fly ash and flue gas) into metal sulfates displacing its sulfides and some of its oxides. The effect of promoting Pb volatilization by adding Na{sub 2}SO{sub 4} and Na{sub 2}S was superior to that of the addition of S. In bottom ash, different metallic sulfides were found in the forms of lead sulfide, aluminosilicate minerals, and polymetallic-sulfides, which were minimally volatilized. The chemical equilibrium calculations indicated that sulfur stabilizes Pb in the form of PbSO{sub 4}(s) at low temperatures (<1000 K). The equilibrium calculation prediction also suggested that SiO{sub 2}, CaO, TiO{sub 2}, and Al{sub 2}O{sub 3} containing materials function as condensed phase solids in the temperature range of 800–1100 K as sorbents to stabilize Pb. However, in the presence of sulfur or chlorine or the co-existence of sulfur and chlorine, these sorbents were inactive. The effect of sulfur on Pb partitioning in the sludge incineration process mainly depended on the gas phase reaction, the surface reaction, the volatilization of products, and the

  19. Pearlite revisited

    NASA Astrophysics Data System (ADS)

    Steinbach, Ingo; Plapp, Mathis

    2012-11-01

    Zener's model of pearlite transformation in steels can be viewed as the prototype of many microstructure evolution models in materials science. It links principles of thermodynamics and kinetics to the scale of the microstructure. In addition it solves a very practical problem: How the hardness of steel is correlated to the conditions of processing. Although the model is well established since the 1950s, quantitative explanation of growth kinetics was missing until very recently. The present paper will shortly review the classical model of pearlite transformation. Zener's conjecture of maximum entropy production will be annotated by modern theoretical and experimental considerations of a band of stable (sometimes oscillating) states around the state of maximum entropy production. Finally, an explanation of the growth kinetics observed in experiments is proposed based on diffusion fluxes driven by stress gradients due to large transformation strain.

  20. Thermodynamic study of the effect of ethanol on two amphiphilic penicillins.

    PubMed

    Barbosa, Silvia; Taboada, Pablo; Mosquera, Víctor

    2005-12-01

    The effect of ethanol on the thermodynamic properties on two anionic amphiphilic penicillins, cloxacillin and dicloxacillin, has been investigated. Cloxacillin and dicloxacillin are two molecules that are similar structurally, differing only by an additional chlorine atom on the phenyl ring of dicloxacillin. The penicillins can be considered as hydrotropes if we considered that the term comprises hydrophilic and hydrophobic moieties that form aggregates by a stacking mechanism as is the case of both penicillins. By means of ultrasound velocities and densities, we have calculated the apparent molar volumes and adiabatic compressibilities. The critical concentrations, cc, and partition coefficients, K, have been determined, the latter using an indirect method based on the pseudophase model with the help of apparent molar data. This method has the advantage of allowing one to calculate the distribution coefficients at concentrations of the solubilizate below the saturation. The standard molar energy of Gibbs change, DeltaG0, on transfer from the aqueous to the micelar phase was calculated from the partition coefficient. The effect of the alcohol involves a slight decrease of the critical concentration because of a headgroup repulsion decrease. The enthalpies of dilution of dicloxacillin in a mixture of water and 15% w/v of ethanol were calculated. The aggregation process is more exothermic in ethanol that in pure water. PMID:16853954

  1. Thermodynamics and the hydrophobic effect in a core-softened model and comparison with experiments

    NASA Astrophysics Data System (ADS)

    Huš, Matej; Urbic, Tomaz

    2014-08-01

    A simple and computationally inexpensive core-softened model, originally proposed by Franzese [G. Franzese, J. Mol. Liq. 136, 267 (2007), 10.1016/j.molliq.2007.08.021], was adopted to show that it exhibits properties of waterlike fluid and hydrophobic effect. The potential used between particles is spherically symmetric with two characteristic lengths. Thermodynamics of nonpolar solvation were modeled as an insertion of a modified Lennard-Jones particle. It was investigated how the anomalous predictions of the model as well as the nonpolar solvation compare with the experimental data for water anomalies and the temperature dependence of noble gases hydration. It was shown that the model qualitatively follows the same trends as water. The model is able to reproduce waterlike anomalous properties (density maximum, heat capacity minimum, isothermal compressibility, etc.) and hydrophobic effect (minimum solubility for nonpolar solutes near ambient conditions, increased solubility of larger noble gases, etc.). It is argued that the model yields similar results as more complex and computationally expensive models.

  2. An effective thermodynamic potential from the instanton vacuum with the Polyakov loop

    NASA Astrophysics Data System (ADS)

    Nam, Seung-Il

    2012-02-01

    In this talk, we report our recent studies on an effective thermodynamic potential (Ωeff) at finite temperature (T ≠ 0) and zero quark-chemical potential (μR = 0), using the singular-gauge instanton solution and Matsubara formula for Nc = 3 and Nf = 2 in the chiral limit, i.e. mq = 0. The momentum-dependent constituent-quark mass is computed as a function of T, together with the Harrington-Shepard caloron solution in the large-Nc limit. In addition, we take into account the imaginary quark-chemical potential μI ≡ A4, identified as the traced Polyakov-loop (Φ) as an order parameter for the ℤ(Nc) symmetry, characterizing the confinement (intact) and deconfinement (spontaneously broken) phases. As a consequence, we observe the crossover of the chiral (χ) order parameter σ2 and Φ. It also turns out that the critical temperature for the deconfinement phase transition, Tcℤ is lowered by about (5 ~10)% in comparison to the case with the constant constituent-quark mass. This behavior can be understood by considerable effects from the partial chiral restoration and nontrivial QCD vacuum on the Φ. Numerical results show that the crossover transitions occur at (Tcχ, Tcℤ) ≈ (216, 227) MeV.

  3. An effective thermodynamic potential from the instanton with Polyakov-loop contributions

    NASA Astrophysics Data System (ADS)

    Nam, Seung-il

    2010-07-01

    We derive an effective thermodynamic potential (Ωeff) at a finite temperature (T ≠ 0) and zero quark-chemical potential (μR = 0), using the singular-gauge instanton solution and Matsubara formula for Nc = 3 and Nf = 2 in the chiral limit. The momentum-dependent constituent-quark mass is also obtained as a function of T, employing the Harrington-Shepard caloron solution in the large-Nc limit. In addition, we take into account the imaginary quark-chemical potential μI ≡ A4, translated as the traced Polayakov-loop (Φ) as an order parameter for the \\mathbb {Z}(N_{c}) symmetry, characterizing the confinement (intact) and deconfinement (spontaneously broken) phases. As a result, we observe the crossover of the chiral (χ) order parameters σ2 and Φ. It also turns out that the critical temperature T^{\\mathbb {Z}}_c, for the deconfinement phase transition, is lowered by about (5-10)% in comparison to the case with a constant constituent-quark mass. This behavior can be understood by considerable effects from the partial chiral restoration and nontrivial QCD vacuum on Φ. Numerical calculations show that the crossover transitions occur at \\big(T^{\\chi }_c,T^{\\mathbb {Z}}_c\\big)\\approx (216,227) MeV.

  4. The Effects of Quantum Delocalization on the Structural and Thermodynamic Properties of Many-Body Systems

    NASA Astrophysics Data System (ADS)

    Deckman, Jason

    The following dissertation is an account of my research in the Mandelshtam group at UC Irvine beginning in the Fall of 2006 and ending in the Summer of 2011. My general area of study falls within the realm of equilibrium quantum statistical mechanics, a discipline which attempts to relate molecular-scale properties to time averaged, macroscopic observables. The major tools used herein are the Variational Gaussian Wavepacket (VGW) approximation for quantum calculations, and Monte-Carlo methods, particularly parallel tempering, for global optimization and the prediction of equilibrium thermodynamic properties. Much of my work used these two methods to model both small and bulk systems at equilibrium where quantum effects are significant. All the systems considered are characterized by inter-molecular van der Waals forces, which are weak but significant electrostatic attractions between atoms and molecules and posses a 1/r6 dependence. The research herein begins at the microscopic level, starting with Lennard-Jones (LJ) clusters, then later shifts to the macroscopic for a study involving bulk para-hydrogen. For the LJ clusters the structural transitions induced by a changing deBoer parameter, Λ, a measure of quantum delocalization of the constituent particles, are investigated over a range of cluster sizes, N. From the data a "phase" diagram as a function of Λ and N is constructed, which depicts the structural motifs favored at different size and quantum parameter. Comparisons of the "quantum induced" structural transitions depicted in the latter are also made with temperature induced transitions and those caused by varying the range of the Morse potential. Following this, the structural properties of binary para-Hydrogen/ ortho-Deuterium clusters are investigated using the VGW approximation and Monte-Carlo methods within the GMIN framework. The latter uses the "Basin-Hopping" algorithm, which simplifies the potential energy landscape, and coupled with the VGW

  5. The super greenhouse effect in a warming world: the role of dynamics and thermodynamics

    NASA Astrophysics Data System (ADS)

    Kashinath, Karthik; O'Brien, Travis; Collins, William

    2016-04-01

    Over warm tropical oceans the increase in greenhouse trapping with increasing SST can be faster than that of the surface emission, resulting in a decrease in clear sky outgoing longwave radiation at the top of the atmosphere (OLR) when SST increases, also known as the super greenhouse effect (SGE). If the SGE is directly linked to SST changes, there are profound implications for positive climate feedbacks in the tropics. We show that CMIP5 models perform well in simulating the observed clear-sky greenhouse effect in the present day. Using global warming experiments we show that the onset and shutdown SST of the SGE, as well as the magnitude of the SGE, increase as the convective threshold SST increases. To account for an increasing convective threshold SST we use an invariant coordinate for convection proposed in a recent study [Williams et al., GRL (2009)]. However, even after accounting for the increase in tropical SST (by normalizing the SGE by surface emission) and accounting for the increase in the threshold temperature for convection (by using the invariant coordinate) we find that the models predict a distinct increase in the clear-sky greenhouse effect in a warmed world. This suggests that thermodynamics (i.e. SST) plays a crucial role in regulating the increasing clear sky greenhouse effect in a warming world. We use theoretical arguments to estimate this increase in SGE and derive its dependence on SST. Finally, as shown in previous studies, we confirm that the increase in the clear-sky greenhouse effect is primarily due to upper tropospheric moistening. Although the absolute increase in upper tropospheric water vapor is small compared to that of the lower troposphere, since the absorptivity scales with fractional changes in water vapor, the contribution of the upper troposphere is more significant, as shown by Chung et al., PNAS (2014).

  6. Revisiting the Effect of Maternal Smoking during Pregnancy on Offspring Birthweight: A Quasi-Experimental Sibling Analysis in Sweden

    PubMed Central

    Juárez, Sol Pía; Merlo, Juan

    2013-01-01

    Maternal smoking during pregnancy (SDP) seems associated with reduced birthweight in the offspring. This observation, however, is based on conventional epidemiological analyses, and it might be confounded by unobserved maternal characteristics related to both smoking habits and offspring birth weight. Therefore, we apply a quasi-experimental sibling analysis to revisit previous findings. Using the Swedish Medical Birth Register, we identified 677,922 singletons born between 2002 and 2010 from native Swedish mothers. From this population, we isolated 62,941 siblings from 28,768 mothers with discrepant habits of SDP. We applied conventional and mother-specific multilevel linear regression models to investigate the association between maternal SDP and offspring birthweight. Depending on the mother was light or heavy smoker and the timing of exposition during pregnancy (i.e., first or third trimester), the effect of smoking on birthweight reduction was between 6 and 78 g less marked in the sibling analysis than in the conventional analysis. Sibling analysis showed that continuous smoking reduces birthweight by 162 grams for mothers who were light smokers (1 to 9 cigarettes per day) and 226 g on average for those who were heavy smokers throughout the pregnancy in comparison to non-smoker mothers. Quitting smoking during pregnancy partly counteracted the smoking-related birthweight reduction by 1 to 29 g, and a subsequent smoking relapse during pregnancy reduced birthweight by 77 to 83 g. The sibling analysis provides strong evidence that maternal SDP reduces offspring birthweight, though this reduction was not as great as that observed in the conventional analysis. Our findings support public health interventions aimed to prevent SDP and to persuade those who already smoke to quit and not relapse throughout the pregnancy. Besides, further analyses are needed in order to explain the mechanisms through which smoking reduces birthweight and to identify other maternal

  7. Thermodynamical effects accompanied freezing of two water layers separated by sea ice sheet

    NASA Astrophysics Data System (ADS)

    Bogorodsky, Petr; Marchenko, Aleksey

    2014-05-01

    The process of melt pond freezing is very important for generation of sea ice cover thermodynamic and mass balance during winterperiod. However, due to significant difficulties of field measurements the available data of model estimations still have no instrumental confirmation. In May 2009 the authors carried out laboratory experiment on freezing of limited water volume in the University Centre in Svalbard ice tank. In the course of experiment fresh water layer of 27.5 cm thickness at freezing point poured on the 24 cm sea ice layer was cooled during 50 hours at the temperature -10º C and then once again during 60 hours at -20º C. For revealing process typical characteristics the data of continuous measurements of temperature and salinity in different phases were compared with data of numerical computations obtained with thermodynamic model which was formulated in the frames of 1-D equation system (infinite extension of water freezing layer) and adapted to laboratory conditions. The known surprise of the experiment became proximity of calculated and measured estimates of process dynamics that confirmed the adequacy of the problem mathematical statement (excluding probably process finale stage). This effect can be explained by formation of cracks on the upper layer of ice at sharp decreases of air temperature, which temporary compensated hydrostatic pressure growth during freezing of closed water volume. Another compensated mechanism can be migration of brine through the lower layer of ice under influence of vertical pressure gradient and also rejection of gas dissolved in water which increased its compressibility. During 110 hours cooling thickness of water layer between ice layers reduced approximately to 2 cm. According to computations this layer is not chilled completely but keeps as thin brine interlayer within ice body whose thickness (about units of mm) is determined by temperature fluctuations of cooled surface. Nevertheless, despite good coincidence of

  8. Effect of thermodynamic disequilibrium on critical liquid-vapor flow conditions

    SciTech Connect

    Bilicki, Z.; Kestin, J.

    1989-01-01

    In this lecture we characterize the effect of absence of unconstrained thermodynamic equilibrium and onset of a metastable state on the adiabatic flow of a mixture of liquid and its vapor through a convergent-divergent nozzle. We study steady-state flows and emphasize the relations that are present when the flow is choked. In such cases, there exists a cross-section in which the flow is critical and in which the adiabatic wave of small amplitude is stationary. More precisely, the relaxation process which results from the lack of equilibrium causes the system to be dispersive. In such circumstances, the critical velocity is equal to the frozen speed of sound, a/sub f/ corresponding to /omega/ /yields/ /infinity/. The relaxation process displaces the critical cross-section quite far downstream from the throat and places it in the divergent portion of the channel. We present the topological portrait of solutions in a suitably defined state-velocity space and discuss the potential appearance of normal and dispersed shock waves. In extreme cases, the singular point (usually a saddle) which enables the flow to become supercritical is displaced so far that it is located outside the exit. Then, the flow velocity is everywhere subcritical (w < a/sub f/) even though it may exceed the equilibrium speed of sound (w /approx gt/ a/sub e/) beyond a certain cross-section, and in spite of the presence of a throat. 10 refs., 4 figs.

  9. Thermodynamic estimation: Ionic materials

    SciTech Connect

    Glasser, Leslie

    2013-10-15

    Thermodynamics establishes equilibrium relations among thermodynamic parameters (“properties”) and delineates the effects of variation of the thermodynamic functions (typically temperature and pressure) on those parameters. However, classical thermodynamics does not provide values for the necessary thermodynamic properties, which must be established by extra-thermodynamic means such as experiment, theoretical calculation, or empirical estimation. While many values may be found in the numerous collected tables in the literature, these are necessarily incomplete because either the experimental measurements have not been made or the materials may be hypothetical. The current paper presents a number of simple and relible estimation methods for thermodynamic properties, principally for ionic materials. The results may also be used as a check for obvious errors in published values. The estimation methods described are typically based on addition of properties of individual ions, or sums of properties of neutral ion groups (such as “double” salts, in the Simple Salt Approximation), or based upon correlations such as with formula unit volumes (Volume-Based Thermodynamics). - Graphical abstract: Thermodynamic properties of ionic materials may be readily estimated by summation of the properties of individual ions, by summation of the properties of ‘double salts’, and by correlation with formula volume. Such estimates may fill gaps in the literature, and may also be used as checks of published values. This simplicity arises from exploitation of the fact that repulsive energy terms are of short range and very similar across materials, while coulombic interactions provide a very large component of the attractive energy in ionic systems. Display Omitted - Highlights: • Estimation methods for thermodynamic properties of ionic materials are introduced. • Methods are based on summation of single ions, multiple salts, and correlations. • Heat capacity, entropy

  10. Structural and thermodynamic effects of ANS binding to human interleukin-1 receptor antagonist

    PubMed Central

    Latypov, Ramil F.; Liu, Dingjiang; Gunasekaran, Kannan; Harvey, Timothy S.; Razinkov, Vladimir I.; Raibekas, Andrei A.

    2008-01-01

    Although 8-anilinonaphthalene-1-sulfonic acid (ANS) is frequently used in protein folding studies, the structural and thermodynamic effects of its binding to proteins are not well understood. Using high-resolution two-dimensional NMR and human interleukin-1 receptor antagonist (IL-1ra) as a model protein, we obtained detailed information on ANS–protein interactions in the absence and presence of urea. The effects of ambient to elevated temperatures on the affinity and specificity of ANS binding were assessed from experiments performed at 25°C and 37°C. Overall, the affinity of ANS was lower at 37°C compared to 25°C, but no significant change in the site specificity of binding was observed from the chemical shift perturbation data. The same site-specific binding was evident in the presence of 5.2 M urea, well within the unfolding transition region, and resulted in selective stabilization of the folded state. Based on the two-state denaturation mechanism, ANS-dependent changes in the protein stability were estimated from relative intensities of two amide resonances specific to the folded and unfolded states of IL-1ra. No evidence was found for any ANS-induced partially denatured or aggregated forms of IL-1ra throughout the experimental conditions, consistent with a cooperative and reversible denaturation process. The NMR results support earlier observations on the tendency of ANS to interact with solvent-exposed positively charged sites on proteins. Under denaturing conditions, ANS binding appears to be selective to structured states rather than unfolded conformations. Interestingly, the binding occurs within a previously identified aggregation-critical region in IL-1ra, thus providing an insight into ligand-dependent protein aggregation. PMID:18305195

  11. Effects of sulfur on lead partitioning during sludge incineration based on experiments and thermodynamic calculations.

    PubMed

    Liu, Jing-yong; Huang, Shu-jie; Sun, Shui-yu; Ning, Xun-an; He, Rui-zhe; Li, Xiao-ming; Chen, Tao; Luo, Guang-qian; Xie, Wu-ming; Wang, Yu-Jie; Zhuo, Zhong-xu; Fu, Jie-wen

    2015-04-01

    Experiments in a tubular furnace reactor and thermodynamic equilibrium calculations were conducted to investigate the impact of sulfur compounds on the migration of lead (Pb) during sludge incineration. Representative samples of typical sludge with and without the addition of sulfur compounds were combusted at 850 °C, and the partitioning of Pb in the solid phase (bottom ash) and gas phase (fly ash and flue gas) was quantified. The results indicate that three types of sulfur compounds (S, Na2S and Na2SO4) added to the sludge could facilitate the volatilization of Pb in the gas phase (fly ash and flue gas) into metal sulfates displacing its sulfides and some of its oxides. The effect of promoting Pb volatilization by adding Na2SO4 and Na2S was superior to that of the addition of S. In bottom ash, different metallic sulfides were found in the forms of lead sulfide, aluminosilicate minerals, and polymetallic-sulfides, which were minimally volatilized. The chemical equilibrium calculations indicated that sulfur stabilizes Pb in the form of PbSO4(s) at low temperatures (<1000 K). The equilibrium calculation prediction also suggested that SiO2, CaO, TiO2, and Al2O3 containing materials function as condensed phase solids in the temperature range of 800-1100 K as sorbents to stabilize Pb. However, in the presence of sulfur or chlorine or the co-existence of sulfur and chlorine, these sorbents were inactive. The effect of sulfur on Pb partitioning in the sludge incineration process mainly depended on the gas phase reaction, the surface reaction, the volatilization of products, and the concentration of Si, Ca and Al-containing compounds in the sludge. These findings provide useful information for understanding the partitioning behavior of Pb, facilitating the development of strategies to control the volatilization of Pb during sludge incineration. PMID:25554470

  12. On the Effectiveness of Nature-Inspired Metaheuristic Algorithms for Performing Phase Equilibrium Thermodynamic Calculations

    PubMed Central

    Fateen, Seif-Eddeen K.; Bonilla-Petriciolet, Adrian

    2014-01-01

    The search for reliable and efficient global optimization algorithms for solving phase stability and phase equilibrium problems in applied thermodynamics is an ongoing area of research. In this study, we evaluated and compared the reliability and efficiency of eight selected nature-inspired metaheuristic algorithms for solving difficult phase stability and phase equilibrium problems. These algorithms are the cuckoo search (CS), intelligent firefly (IFA), bat (BA), artificial bee colony (ABC), MAKHA, a hybrid between monkey algorithm and krill herd algorithm, covariance matrix adaptation evolution strategy (CMAES), magnetic charged system search (MCSS), and bare bones particle swarm optimization (BBPSO). The results clearly showed that CS is the most reliable of all methods as it successfully solved all thermodynamic problems tested in this study. CS proved to be a promising nature-inspired optimization method to perform applied thermodynamic calculations for process design. PMID:24967430

  13. Assessing nanoparticle size effects on metal hydride thermodynamics using the Wulff construction.

    PubMed

    Kim, Ki Chul; Dai, Bing; Karl Johnson, J; Sholl, David S

    2009-05-20

    The reaction thermodynamics of metal hydrides are crucial to the use of these materials for reversible hydrogen storage. In addition to altering the kinetics of metal hydride reactions, the use of nanoparticles can also change the overall reaction thermodynamics. We use density functional theory to predict the equilibrium crystal shapes of seven metals and their hydrides via the Wulff construction. These calculations allow the impact of nanoparticle size on the thermodynamics of hydrogen release from these metal hydrides to be predicted. Specifically, we study the temperature required for the hydride to generate a H(2) pressure of 1 bar as a function of the radius of the nanoparticle. In most, but not all, cases the hydrogen release temperature increases slightly as the particle size is reduced. PMID:19420649

  14. On the effectiveness of nature-inspired metaheuristic algorithms for performing phase equilibrium thermodynamic calculations.

    PubMed

    Fateen, Seif-Eddeen K; Bonilla-Petriciolet, Adrian

    2014-01-01

    The search for reliable and efficient global optimization algorithms for solving phase stability and phase equilibrium problems in applied thermodynamics is an ongoing area of research. In this study, we evaluated and compared the reliability and efficiency of eight selected nature-inspired metaheuristic algorithms for solving difficult phase stability and phase equilibrium problems. These algorithms are the cuckoo search (CS), intelligent firefly (IFA), bat (BA), artificial bee colony (ABC), MAKHA, a hybrid between monkey algorithm and krill herd algorithm, covariance matrix adaptation evolution strategy (CMAES), magnetic charged system search (MCSS), and bare bones particle swarm optimization (BBPSO). The results clearly showed that CS is the most reliable of all methods as it successfully solved all thermodynamic problems tested in this study. CS proved to be a promising nature-inspired optimization method to perform applied thermodynamic calculations for process design. PMID:24967430

  15. Thermodynamic holography

    PubMed Central

    Wei, Bo-Bo; Jiang, Zhan-Feng; Liu, Ren-Bao

    2015-01-01

    The holographic principle states that the information about a volume of a system is encoded on the boundary surface of the volume. Holography appears in many branches of physics, such as optics, electromagnetism, many-body physics, quantum gravity, and string theory. Here we show that holography is also an underlying principle in thermodynamics, a most important foundation of physics. The thermodynamics of a system is fully determined by its partition function. We prove that the partition function of a finite but arbitrarily large system is an analytic function on the complex plane of physical parameters, and therefore the partition function in a region on the complex plane is uniquely determined by its values along the boundary. The thermodynamic holography has applications in studying thermodynamics of nano-scale systems (such as molecule engines, nano-generators and macromolecules) and provides a new approach to many-body physics. PMID:26478214

  16. Thermodynamic holography.

    PubMed

    Wei, Bo-Bo; Jiang, Zhan-Feng; Liu, Ren-Bao

    2015-01-01

    The holographic principle states that the information about a volume of a system is encoded on the boundary surface of the volume. Holography appears in many branches of physics, such as optics, electromagnetism, many-body physics, quantum gravity, and string theory. Here we show that holography is also an underlying principle in thermodynamics, a most important foundation of physics. The thermodynamics of a system is fully determined by its partition function. We prove that the partition function of a finite but arbitrarily large system is an analytic function on the complex plane of physical parameters, and therefore the partition function in a region on the complex plane is uniquely determined by its values along the boundary. The thermodynamic holography has applications in studying thermodynamics of nano-scale systems (such as molecule engines, nano-generators and macromolecules) and provides a new approach to many-body physics. PMID:26478214

  17. Mg/Ca ratios in freshwater microbial carbonates: Thermodynamic, kinetic and vital effects

    NASA Astrophysics Data System (ADS)

    Saunders, P.; Rogerson, M.; Wadhawan, J. D.; Greenway, G.; Pedley, H. M.

    2014-12-01

    The ratio of magnesium to calcium (Mg/Ca) in carbonate minerals in an abiotic setting is conventionally assumed to be predominantly controlled by (Mg/Ca)solution and a temperature dependant partition coefficient. This temperature dependence suggests that both marine (e.g. foraminiferal calcite and corals) and freshwater (e.g. speleothems and surface freshwater deposits, “tufas”) carbonate deposits may be important archives of palaeotemperature data. However, there is considerable uncertainty in all these settings. In surface freshwater deposits this uncertainty is focussed on the influence of microbial biofilms. Biogenic or “vital” effects may arise from microbial metabolic activity and/or the presence of extracellular polymeric substances (EPS). This study addresses this key question for the first time, via a series of unique through-flow microcosm and agitated flask experiments where freshwater calcite was precipitated under controlled conditions. These experiments reveal there is no strong relationship between (Mg/Ca)calcite and temperature, so the assumption of thermodynamic fractionation is not viable. However, there is a pronounced influence on (Mg/Ca)calcite from precipitation rate, so that rapidly forming precipitates develop with very low magnesium content indicating kinetic control on fractionation. Calcite precipitation rate in these experiments (where the solution is only moderately supersaturated) is controlled by biofilm growth rate, but occurs even when light is excluded indicating that photosynthetic influences are not critical. Our results thus suggest the apparent kinetic fractionation arises from the electrochemical activity of EPS molecules, and are therefore likely to occur wherever these molecules occur, including stromatolites, soil and lake carbonates and (via colloidal EPS) speleothems.

  18. Heat Activation of Phycomyces blakesleeanus Spores: Thermodynamics and Effect of Alcohols, Furfural, and High Pressure

    PubMed Central

    Thevelein, Johan M.; Van Assche, Jozef A.; Carlier, Albert R.; Heremans, Karel

    1979-01-01

    The thermodynamic parameters for the heat activation of the sporangiospores of Phycomyces blakesleeanus were determined. For the apparent activation enthalpy (ΔH#) a value of 1,151 kJ/mol was found, whereas a value of 3,644 J./°K·mol was calculated for the apparent activation entropy (ΔS#). n-Alcohols (from methanol to octanol), phenethyl alcohol, and furfural lowered the activation temperature of P. blakesleeanus spores. The heat resistance of the spores was lowered concomitantly. The effect of the alcohols was a linear function of the concentration in the range that could be applied. When the log of the concentration needed to produce an equal shift of the activation temperature was plotted for each alochol against the log of the octanol/water partition coefficient, a straight line was obtained. The free energy of adsorption of the n-alcohols to their active sites was calculated to be −2,487 J/mol of CH2 groups. Although still inconclusive, this points toward an involvement of protein in the activation process. The effect of phenethyl alcohol was similar to the effect of n-alcohols, but furfural produced a greater shift than would be expected from the value of its partition coefficient. When the heat activation of the spores was performed under high pressure, the activation temperature was raised by 2 to 4°K/1,000 atm. However, with pressures higher than 1,000 atm (1.013 × 105 kPa) the activation temperature was lowered until the pressure became lethal (more than 2,500 atm). It is known that membrane phase transition temperatures are shifted upward by about 20°K/1,000 atm and that protein conformational changes are shifted upward by 2 to 6°K/1,000 atm. Consequently, heat activation of fungal spores seems to be triggered by a protein conformational change and not by a membrane phase transition. Activation volumes of −54.1 cm3/mol at 38°C and −79.3 cm2/mol at 40°C were found for the lowering effect of high pressure on the heat activation temperature

  19. Revisiting Age-of-Acquisition Effects in Spanish Visual Word Recognition: The Role of Item Imageability

    ERIC Educational Resources Information Center

    Wilson, Maximiliano A.; Cuetos, Fernando; Davies, Rob; Burani, Cristina

    2013-01-01

    Word age-of-acquisition (AoA) affects reading. The mapping hypothesis predicts AoA effects when input--output mappings are arbitrary. In Spanish, the orthography-to-phonology mappings required for word naming are consistent; therefore, no AoA effects are expected. Nevertheless, AoA effects have been found, motivating the present investigation of…

  20. An Easy and Effective Demonstration of Enzyme Stereospecificity and Equilibrium Thermodynamics

    ERIC Educational Resources Information Center

    Herdman, Chelsea; Dickman, Michael

    2011-01-01

    Enzyme stereospecificity and equilibrium thermodynamics can be demonstrated using the coupling of two amino acid derivatives by Thermoase C160. This protease will catalyze peptide bond formation between Z-L-AspOH and L-PheOMe to form the Aspartame precursor Z-L-Asp-L-PheOMe. Reaction completion manifests itself by precipitation of the product. As…

  1. The Effectiveness of Problem-Based Learning on Teaching the First Law of Thermodynamics

    ERIC Educational Resources Information Center

    Tatar, Erdal; Oktay, Munir

    2011-01-01

    Background: Problem-based learning (PBL) is a teaching approach working in cooperation with self-learning and involving research to solve real problems. The first law of thermodynamics states that energy can neither be created nor destroyed, but that energy is conserved. Students had difficulty learning or misconceptions about this law. This study…

  2. Sensory Attenuation of Self-Produced Feedback: The Lombard Effect Revisited

    PubMed Central

    Therrien, Amanda S.; Lyons, James; Balasubramaniam, Ramesh

    2012-01-01

    The Lombard effect describes the automatic and involuntary increase in vocal intensity that speakers exhibit in a noisy environment. Previous studies of the Lombard effect have typically focused on the relationship between speaking and hearing. Automatic and involuntary increases in motor output have also been noted in studies of finger force production, an effect attributed to mechanisms of sensory attenuation. The present study tested the hypothesis that sensory attenuation mechanisms also underlie expression of the Lombard effect. Participants vocalized phonemes in time with a metronome, while auditory and visual feedback of their performance were manipulated or removed during the course of the trial. We demonstrate that providing a visual reference to calibrate somatosensory-based judgments of current vocal intensity resulted in reduced expression of the Lombard effect. Our results suggest that sensory attenuation effects typically seen in fingertip force production play an important role in the control of speech volume. PMID:23145166

  3. Stochastic thermodynamics

    NASA Astrophysics Data System (ADS)

    Eichhorn, Ralf; Aurell, Erik

    2014-04-01

    'Stochastic thermodynamics as a conceptual framework combines the stochastic energetics approach introduced a decade ago by Sekimoto [1] with the idea that entropy can consistently be assigned to a single fluctuating trajectory [2]'. This quote, taken from Udo Seifert's [3] 2008 review, nicely summarizes the basic ideas behind stochastic thermodynamics: for small systems, driven by external forces and in contact with a heat bath at a well-defined temperature, stochastic energetics [4] defines the exchanged work and heat along a single fluctuating trajectory and connects them to changes in the internal (system) energy by an energy balance analogous to the first law of thermodynamics. Additionally, providing a consistent definition of trajectory-wise entropy production gives rise to second-law-like relations and forms the basis for a 'stochastic thermodynamics' along individual fluctuating trajectories. In order to construct meaningful concepts of work, heat and entropy production for single trajectories, their definitions are based on the stochastic equations of motion modeling the physical system of interest. Because of this, they are valid even for systems that are prevented from equilibrating with the thermal environment by external driving forces (or other sources of non-equilibrium). In that way, the central notions of equilibrium thermodynamics, such as heat, work and entropy, are consistently extended to the non-equilibrium realm. In the (non-equilibrium) ensemble, the trajectory-wise quantities acquire distributions. General statements derived within stochastic thermodynamics typically refer to properties of these distributions, and are valid in the non-equilibrium regime even beyond the linear response. The extension of statistical mechanics and of exact thermodynamic statements to the non-equilibrium realm has been discussed from the early days of statistical mechanics more than 100 years ago. This debate culminated in the development of linear response

  4. Effects of Sibship Structure Revisited: Evidence from Intrafamily Resource Transfer in Taiwan

    ERIC Educational Resources Information Center

    Chu, C. Y. Cyrus; Xie, Yu; Yu, Ruoh-rong

    2007-01-01

    Numerous studies have consistently found negative effects of sibship size on educational outcomes. Three main explanations of these effects have been offered in the literature: (1) the dilution of family resources, (2) a changing intellectual environment in the family for each succeeding sibling, and (3) unobserved selectivity at the family level.…

  5. The Demise of Short-Term Memory Revisited: Empirical and Computational Investigations of Recency Effects

    ERIC Educational Resources Information Center

    Davelaar,Eddy J.; Goshen-Gottstein, Yonatan; Ashkenazi, Amir; Haarmann, Henk J.; Usher, Marius

    2005-01-01

    In the single-store model of memory, the enhanced recall for the last items in a free-recall task (i.e., the recency effect) is understood to reflect a general property of memory rather than a separate short-term store. This interpretation is supported by the finding of a long-term recency effect under conditions that eliminate the contribution…

  6. Revisiting the Efficacy of Postsecondary Remediation: The Moderating Effects of Depth/Breadth of Deficiency

    ERIC Educational Resources Information Center

    Bahr, Peter Riley

    2010-01-01

    Postsecondary remediation is an important and highly contentious issue that has received comparatively little comprehensive attention with respect to evaluating its effectiveness. This study addresses two relatively unexplored aspects of remedial efficacy: the moderating effects of depth and breadth of underpreparation. I find that, regardless of…

  7. The Pill Not Taken: Revisiting Physical Education Teacher Effectiveness in a Public Health Context

    ERIC Educational Resources Information Center

    McKenzie, Thomas L.; Lounsbery, Monica A. F.

    2014-01-01

    In "Physical Education Teacher Effectiveness in a Public Health Context," we took a broad view of physical education (PE) teacher effectiveness that included public health need and support for PE. Public health officials have been consistent and fervent in their support of PE, and for more than two decades, they have called on schools to…

  8. Revisiting multi-subject random effects in fMRI: advocating prevalence estimation.

    PubMed

    Rosenblatt, J D; Vink, M; Benjamini, Y

    2014-01-01

    Random effect analysis has been introduced into fMRI research in order to generalize findings from the study group to the whole population. Generalizing findings is obviously harder than detecting activation within the study group since in order to be significant, an activation has to be larger than the inter-subject variability. Indeed, detected regions are smaller when using random effect analysis versus fixed effects. The statistical assumptions behind the classic random effect model are that the effect in each location is normally distributed over subjects, and "activation" refers to a non-null mean effect. We argue that this model is unrealistic compared to the true population variability, where due to function-anatomy inconsistencies and registration anomalies, some of the subjects are active and some are not at each brain location. We propose a Gaussian-mixture-random-effect that amortizes between-subject spatial disagreement and quantifies it using the prevalence of activation at each location. We present a formal definition and an estimation procedure of this prevalence. The end result of the proposed analysis is a map of the prevalence at locations with significant activation, highlighting activation regions that are common over many brains. Prevalence estimation has several desirable properties: (a) It is more informative than the typical active/inactive paradigm. (b) In contrast to the usual display of p-values in activated regions - which trivially converge to 0 for large sample sizes - prevalence estimates converge to the true prevalence. PMID:23988271

  9. Calcium revisited, part III: effect of dietary calcium on BMD and fracture risk.

    PubMed

    Burckhardt, Peter

    2015-01-01

    Food can be an excellent source of calcium. Dietary calcium is in general as well absorbed as calcium supplements, and exerts the same effects on bone. The main sources are dairy products, but also some vegetables and fruits contain considerable amounts of calcium. Mineral water can serve as a supplement. Cross-sectional, longitudinal and some interventional trials have shown positive effects on bone metabolism, bone density and bone loss. But the effect on fracture incidence is less certain, and that of milk, the most studied dairy product, still unproven. PMID:26331006

  10. Calcium revisited, part III: effect of dietary calcium on BMD and fracture risk

    PubMed Central

    Burckhardt, Peter

    2015-01-01

    Food can be an excellent source of calcium. Dietary calcium is in general as well absorbed as calcium supplements, and exerts the same effects on bone. The main sources are dairy products, but also some vegetables and fruits contain considerable amounts of calcium. Mineral water can serve as a supplement. Cross-sectional, longitudinal and some interventional trials have shown positive effects on bone metabolism, bone density and bone loss. But the effect on fracture incidence is less certain, and that of milk, the most studied dairy product, still unproven. PMID:26331006

  11. What Light through Yonder Window Breaks?--The Greenhouse Effect Revisited.

    ERIC Educational Resources Information Center

    Bohren, Craig F.

    1992-01-01

    Presents three experiments exploring aspects of the greenhouse effect. Topics and discussion includes radiation in energy transfer, emissivity and absorptivity, the irrelevance of reflectivity, a digression on insulators and convection, climate change, and radiative energy balance. (MCO)

  12. Marijuana Revisited.

    ERIC Educational Resources Information Center

    Archer, James, Jr.; Lopata, Ann

    1979-01-01

    This review examines recent research on psychological effects of marijuana. The article contains material on potency, research problems, use patterns in the United States, and expectancy, as well as a review of research on acute effects, including psychosis, toxic delirium, acute anxiety, and brain damage. (Author)

  13. COMPUTER SIMULATIONS WITH EXPLICIT SOLVENT: Recent Progress in the Thermodynamic Decomposition of Free Energies and in Modeling Electrostatic Effects

    NASA Astrophysics Data System (ADS)

    Levy, Ronald M.; Gallicchio, Emilio

    1998-10-01

    This review focuses on recent progress in two areas in which computer simulations with explicit solvent are being applied: the thermodynamic decomposition of free energies, and modeling electrostatic effects. The computationally intensive nature of these simulations has been an obstacle to the systematic study of many problems in solvation thermodynamics, such as the decomposition of solvation and ligand binding free energies into component enthalpies and entropies. With the revolution in computer power continuing, these problems are ripe for study but require the judicious choice of algorithms and approximations. We provide a critical evaluation of several numerical approaches to the thermodynamic decomposition of free energies and summarize applications in the current literature. Progress in computer simulations with explicit solvent of charge perturbations in biomolecules was slow in the early 1990s because of the widespread use of truncated Coulomb potentials in these simulations, among other factors. Development of the sophisticated technology described in this review to handle the long-range electrostatic interactions has increased the predictive power of these simulations to the point where comparisons between explicit and continuum solvent models can reveal differences that have their true physical origin in the inherent molecularity of the surrounding medium.

  14. The pill not taken: revisiting Physical Education Teacher Effectiveness in a Public Health Context.

    PubMed

    McKenzie, Thomas L; Lounsbery, Monica A F

    2014-09-01

    In "Physical Education Teacher Effectiveness in a Public Health Context," we took a broad view of physical education (PE) teacher effectiveness that included public health need and support for PE. Public health officials have been consistent and fervent in their support of PE, and for more than two decades, they have called on schools to promote and provide physical activity. They have strongly recommended PE because: (a) It is part of the formalized school curriculum and an essential access point to provide and promote physical activity for nearly all children, and (b) it is the only venue where the least active children experience physical activity at higher intensities. Within the current marginalized status of PE, public health is an ally. Hence, we took a broad public health position, indicated that teacher effectiveness is tied closely to PE program effectiveness, identified physical activity and its assessment as important parts of PE, offered a vision of teacher effectiveness that goes beyond the PE lesson to include components of the comprehensive school physical activity model, and emphasized the need for the collection of data to support PE and physical activity programs. We have read the written reviews and listened to dialogue about our article. In this follow-up article, we address the major comments using 4 themes: prioritizing public health over other PE emphases, PE having a muddled mission, concerns about physical activity, and extending the roles and skills of physical educators. PMID:25141081

  15. Revisiting the Marton, Simpson, and Suddeth experimental confirmation of the Aharonov-Bohm effect

    NASA Astrophysics Data System (ADS)

    Macdougall, James; Singleton, Douglas; Vagenas, Elias C.

    2015-09-01

    We perform an "archeological" study of one of the original experiments used as evidence for the static, time-independent Aharonov-Bohm effect. Since the experiment in question [1] involved a time varying magnetic field we show that there are problems with the explanation of this experiment as a confirmation of the static Aharonov-Bohm effect - specifically the previous analysis ignored the electric field which arises in conjunction with a time-varying magnetic flux. We further argue that the results of this experiment do in fact conform exactly to the recent prediction [2,3] of a cancellation between the magnetic and electric phase shifts for the time-dependent Aharonov-Bohm effect. To resolve this issue a new time-dependent Aharonov-Bohm experiment is called for.

  16. Perceptual effects of linguistic category priming: the Stapel and Semin (2007) paradigm revisited in twelve experiments.

    PubMed

    IJzerman, Hans; Regenberg, Nina F E; Saddlemyer, Justin; Koole, Sander L

    2015-05-01

    Linguistic category priming is a novel paradigm to examine automatic influences of language on cognition (Semin, 2008). An initial article reported that priming abstract linguistic categories (adjectives) led to more global perceptual processing, whereas priming concrete linguistic categories (verbs) led to more local perceptual processing (Stapel & Semin, 2007). However, this report was compromised by data fabrication by the first author, so that it remains unclear whether or not linguistic category priming influences perceptual processing. To fill this gap in the literature, the present article reports 12 studies among Dutch and US samples examining the perceptual effects of linguistic category priming. The results yielded no evidence of linguistic category priming effects. These findings are discussed in relation to other research showing cultural variations in linguistic category priming effects (IJzerman, Saddlemyer, & Koole, 2014). The authors conclude by highlighting the importance of conducting and publishing replication research for achieving scientific progress. PMID:25703607

  17. EFFECT OF HEATING RATE ON THE THERMODYNAMIC PROPERTIES OF PULVERIZED COAL

    SciTech Connect

    Ramanathan Sampath

    2000-01-01

    This final technical report describes work performed under DOE Grant No. DE-FG22-96PC96224 during the period September 24, 1996 to September 23, 1999 which covers the entire performance period of the project. During this period, modification, alignment, and calibration of the measurement system, measurement of devolatilization time-scales for single coal particles subjected to a range of heating rates and temperature data at these time-scales, and analysis of the temperature data to understand the effect of heating rates on coal thermal properties were carried out. A new thermodynamic model was developed to predict the heat transfer behavior for single coal particles using one approach based on the analogy for thermal property of polymers. Results of this model suggest that bituminous coal particles behave like polymers during rapid heating on the order of 10{sup 4}-10{sup 5} K/s. At these heating rates during the early stages of heating, the vibrational part of the heat capacity of the coal molecules appears to be still frozen but during the transition from heat-up to devolatilization, the heat capacity appears to attain a sudden jump in its value as in the case of polymers. There are a few data available in the coal literature for low heating rate experiments (10{sup 2}-10{sup 3} K/s) conducted by UTRC, our industrial partner, in this project. These data were obtained for a longer heating duration on the order of several seconds as opposed to the 10 milliseconds heating time of the single particle experiments discussed above. The polymer analogy model was modified to include longer heating time on the order of several seconds to test these data. However, the model failed to predict these low heating rate data. It should be noted that UTRC's work showed reasonably good agreement with Merrick model heat capacity predictions at these low heating rates, but at higher heating rates UTRC observed that coal thermal response was heat flux dependent. It is concluded that

  18. Large-n approach to thermodynamic Casimir effects in slabs with free surfaces

    NASA Astrophysics Data System (ADS)

    Diehl, H. W.; Grüneberg, Daniel; Hasenbusch, Martin; Hucht, Alfred; Rutkevich, Sergei B.; Schmidt, Felix M.

    2014-06-01

    The classical n-vector ϕ4 model with O (n) symmetrical Hamiltonian H is considered in a ∞2×L slab geometry bounded by a pair of parallel free surface planes at separation L. Standard quadratic boundary terms implying Robin boundary conditions are included in H. The temperature-dependent scaling functions of the excess free energy and the thermodynamic Casimir force are computed in the large-n limit for temperatures T at, above, and below the bulk critical temperature Tc. Their n =∞ limits can be expressed exactly in terms of the spectrum and eigenfunctions of a self-consistent one-dimensional Schrödinger equation. This equation is solved by numerical means for two distinct discretized versions of the model: in the first ("model A"), only the coordinate z across the slab is discretized and the integrations over momenta conjugate to the lateral coordinates are regularized dimensionally; in the second ("model B"), a simple cubic lattice with periodic boundary conditions along the lateral directions is used. Renormalization-group ideas are invoked to show that, in addition to corrections to scaling ∝L-1, anomalous ones ∝L-1lnL should occur. They can be considerably decreased by taking an appropriate g →∞ (Tc→∞) limit of the ϕ4 interaction constant g. Depending on the model A or B, they can be absorbed completely or to a large extent in an effective thickness Leff=L+δL. Excellent data collapses and consistent high-precision results for both models are obtained. The approach to the low-temperature Goldstone values of the scaling functions is shown to involve logarithmic anomalies. The scaling functions exhibit all qualitative features seen in experiments on the thinning of wetting layers of 4He and Monte Carlo simulations of XY models, including a pronounced minimum of the Casimir force below Tc. The results are in conformity with various analytically known exact properties of the scaling functions.

  19. Revisiting the Complementarity between Education and Training--The Role of Job Tasks and Firm Effects

    ERIC Educational Resources Information Center

    Görlitz, Katja; Tamm, Marcus

    2016-01-01

    This paper addresses the question to what extent the strong positive correlation between education and training can be attributed to differences in individual-, job- and firm-specific characteristics. The novelty of this paper is to analyze previously unconsidered characteristics, in particular, job tasks and firm-fixed effects. The results show…

  20. The Misinformation Effect Revisited: Interactions between Spontaneous Memory Processes and Misleading Suggestions

    ERIC Educational Resources Information Center

    Pansky, Ainat; Tenenboim, Einat; Bar, Sarah Kate

    2011-01-01

    Recent findings indicate that retained information tends to converge at the basic level (BL). The aim of the present study was to apply these findings to the investigation of misinformation phenomena. In three experiments, we examined the extent to which the contaminating effects of misinformation are influenced by its consistency with the…

  1. Role Stress Revisited: Job Structuring Antecedents, Work Outcomes, and Moderating Effects of Locus of Control

    ERIC Educational Resources Information Center

    Conley, Sharon; You, Sukkyung

    2014-01-01

    A previous study examined role stress in relation to work outcomes; in this study, we added job structuring antecedents to a model of role stress and examined the moderating effects of locus of control. Structural equation modeling was used to assess the plausibility of our conceptual model, which specified hypothesized linkages among…

  2. Revisiting the 'Gadgil effect': do interguild fungal interactions control carbon cycling in forest soils?

    PubMed

    Fernandez, Christopher W; Kennedy, Peter G

    2016-03-01

    1382 I. 1382 II. 1383 III. 1383 IV. 1384 V. 1386 VI. 1387 VII. 1389 VIII. 1391 1391 References 1391 SUMMARY: In forest ecosystems, ectomycorrhizal and saprotrophic fungi play a central role in the breakdown of soil organic matter (SOM). Competition between these two fungal guilds has long been hypothesized to lead to suppression of decomposition rates, a phenomenon known as the 'Gadgil effect'. In this review, we examine the documentation, generality, and potential mechanisms involved in the 'Gadgil effect'. We find that the influence of ectomycorrhizal fungi on litter and SOM decomposition is much more variable than previously recognized. To explain the inconsistency in size and direction of the 'Gadgil effect', we argue that a better understanding of underlying mechanisms is required. We discuss the strengths and weaknesses of each of the primary mechanisms proposed to date and how using different experimental methods (trenching, girdling, microcosms), as well as considering different temporal and spatial scales, could influence the conclusions drawn about this phenomenon. Finally, we suggest that combining new research tools such as high-throughput sequencing with experiments utilizing natural environmental gradients will significantly deepen our understanding of the 'Gadgil effect' and its consequences on forest soil carbon and nutrient cycling. PMID:26365785

  3. Revisiting Parental Monitoring: Evidence that Parental Solicitation Can Be Effective when Needed Most

    ERIC Educational Resources Information Center

    Laird, Robert D.; Marrero, Matthew D.; Sentse, Miranda

    2010-01-01

    Studies using valid measures of monitoring activities have not found the anticipated main effects linking greater monitoring activity with fewer behavioral problems. This study focused on two contexts in which monitoring activities may be particularly influential. Early adolescents (n = 218, M age = 11.5 years, 51% female, 49% European American,…

  4. Considerations of Learning and Learning Research: Revisiting the "Media Effects" Debate.

    ERIC Educational Resources Information Center

    Nathan, Mitchell; Robinson, Cecil

    2001-01-01

    Examines the "media effects" debate-whether media in and of itself affects learning-and presents an analysis of various arguments from a learning theory perspective. Proposes a dynamic process of instructional design where assessments are aimed at instructional practices as well as learning outcomes, and instructional media and method are…

  5. The Reciprocal Effects Model Revisited: Extending Its Reach to Gifted Students Attending Academically Selective Schools

    ERIC Educational Resources Information Center

    Seaton, Marjorie; Marsh, Herbert W.; Parker, Philip D.; Craven, Rhonda G.; Yeung, Alexander S.

    2015-01-01

    The reciprocal effects model (REM) predicts a reciprocal relation between academic self-concept and academic achievement, whereby prior academic self-concept is associated with future gains in achievement, and prior achievement is related to subsequent academic self-concept. Although research in this area has been extensive, there has been a…

  6. Revisiting Fixed- and Random-Effects Models: Some Considerations for Policy-Relevant Education Research

    ERIC Educational Resources Information Center

    Clarke, Paul; Crawford, Claire; Steele, Fiona; Vignoles, Anna

    2015-01-01

    The use of fixed (FE) and random effects (RE) in two-level hierarchical linear regression is discussed in the context of education research. We compare the robustness of FE models with the modelling flexibility and potential efficiency of those from RE models. We argue that the two should be seen as complementary approaches. We then compare both…

  7. The Element Effect Revisited: Factors Determining Leaving Group Ability in Activated Nucleophilic Aromatic Substitution Reactions

    PubMed Central

    Senger, Nicholas A.; Bo, Bo; Cheng, Qian; Keeffe, James R.; Gronert, Scott; Wu, Weiming

    2012-01-01

    The “element effect” in nucleophilic aromatic substitution reactions (SNAr) is characterized by the leaving group order, F > NO2 > Cl ≈ Br > I, in activated aryl halides. Multiple causes for this result have been proposed. Experimental evidence shows that the element effect order in the reaction of piperidine with 2,4-dinitrophenyl halides in methanol is governed by the differences in enthalpies of activation. Computational studies of the reaction of piperidine and dimethylamine with the same aryl halides using the polarizable continuum model (PCM) for solvation indicate that polar, polarizability, solvation, and negative hyperconjugative effects are all of some importance in producing the element effect in methanol. In addition, a reversal of polarity of the C–X bond from reactant to transition state in the case of ArCl and ArBr compared to ArF also contributes to their difference in reactivity. The polarity reversal, and hyperconjugative influences have received little or no attention in the past. Nor has differential solvation of the different transition states been strongly emphasized. An anionic nucleophile, thiolate, gives very early transition states and negative activation enthalpies with activated aryl halides. The element effect is not established for these reactions. We suggest that the leaving group order in the gas phase will be dependent on the exact combination of nucleophile, leaving group, and substrate framework. The geometry of the SNAr transition state permits useful, qualitative conceptual distinctions to be made between this reaction and other modes of nucleophilic attack. PMID:23057717

  8. The Labial-Coronal Effect Revisited: Japanese Adults Say Pata, but Hear Tapa

    ERIC Educational Resources Information Center

    Tsuji, Sho; Gomez, Nayeli Gonzalez; Medina, Victoria; Nazzi, Thierry; Mazuka, Reiko

    2012-01-01

    The labial-coronal effect has originally been described as a bias to initiate a word with a labial consonant-vowel-coronal consonant (LC) sequence. This bias has been explained with constraints on the human speech production system, and its perceptual correlates have motivated the suggestion of a perception-production link. However, previous…

  9. The Efficiency of a Group-Specific Mandated Benefit Revisited: The Effect of Infertility Mandates

    ERIC Educational Resources Information Center

    Lahey, Joanna N.

    2012-01-01

    This paper examines the labor market effects of state health insurance mandates that increase the cost of employing a demographically identifiable group. State mandates requiring that health insurance plans cover infertility treatment raise the relative cost of insuring older women of child-bearing age. Empirically, wages in this group are…

  10. Revisiting the Seductive Details Effect in Multimedia Learning: Context-Dependency of Seductive Details

    ERIC Educational Resources Information Center

    Ozdemir, Devrim; Doolittle, Peter

    2015-01-01

    The purpose of this study was to investigate the effects of context-dependency of seductive details on recall and transfer in multimedia learning environments. Seductive details were interesting yet irrelevant sentences in the instructional text. Two experiments were conducted. The purpose of Experiment 1 was to identify context-dependent and…

  11. Revisiting "What Works for Whom?": A Qualitative Framework for Evaluating Clinical Effectiveness in Child Psychotherapy

    ERIC Educational Resources Information Center

    Urwin, Cathy

    2007-01-01

    This paper describes a framework for evaluating the effectiveness of child psychotherapy used by child psychotherapists in an inner city Child and Adolescent Mental Health Service (CAMHS). The Hopes and Expectations for Treatment Approach (HETA) involves using the assessment for psychotherapy that normally precedes treatment to derive a baseline…

  12. Muscle force, work and cost: a novel technique to revisit the Fenn effect.

    PubMed

    Ortega, Justus O; Lindstedt, Stan L; Nelson, Frank E; Jubrias, Sharon A; Kushmerick, Martin J; Conley, Kevin E

    2015-07-01

    Muscle produces force by forming cross-bridges, using energy released from ATP. While the magnitude and duration of force production primarily determine the energy requirement, nearly a century ago Fenn observed that muscle shortening or lengthening influenced energetic cost of contraction. When work is done by the muscle, the energy cost is increased and when work is done on the muscle the energy cost is reduced. However, the magnitude of the 'Fenn effect' and its mirror ('negative Fenn effect') have not been quantitatively resolved. We describe a new technique coupling magnetic resonance spectroscopy with an in vivo force clamp that can directly quantify the Fenn effect [E=I+W, energy liberated (E) equals the energy cost of isometric force production (I) plus the work done (W)] and the negative Fenn effect (E=I-W) for one muscle, the first dorsal interosseous (FDI). ATP cost was measured during a series of contractions, each of which occurred at a constant force and for a constant duration, thus constant force-time integral (FTI). In all subjects, as the FTI increased with load, there was a proportional linear increase in energy cost. In addition, the cost of producing force greatly increased when the muscle shortened, and was slightly reduced during lengthening contraction. These results, though limited to a single muscle, contraction velocity and muscle length change, do quantitatively support the Fenn effect. We speculate that they also suggest that an elastic element within the FDI muscle functions to preserve the force generated within the cross-bridges. PMID:25964423

  13. Major Effects in the Thermodynamics of Detonation Products: Phase Segregation versus Ionic Dissociation

    SciTech Connect

    Bastea, S; Fried, L E

    2010-03-09

    Water (H{sub 2}O) and nitrogen (N{sub 2}) are major detonation products of high explosives and it has long been conjectured that they may phase segregate at high enough temperatures and pressures to influence detonation properties of common explosives. We analyze the phase diagram of H{sub 2}O-N{sub 2} mixtures using a thermodynamic theory for polar-nonpolar mixtures and find that phase segregation is unlikely to occur above approximately 1600K. Therefore, H{sub 2}O-N{sub 2} immiscibility is not likely to be relevant for detonation predictions. We propose instead that the high pressure ionic dissociation of water plays an important role in detonation, and model it using a new ionic thermodynamics. We employ this model in chemical equilibrium calculations of standard high explosives, e.g. PETN, HMX and RDX, and find that it performs very well under a wide range of conditions. Thus, although it may require further development, it is likely that explicitly ionic thermodynamics will become a standard tool for explosives modeling.

  14. Examining the effects of computational tools on students' understanding of thermodynamics of material concepts and representations

    NASA Astrophysics Data System (ADS)

    Ogunwuyi, Oluwatosin

    Technology is becoming a more critical agent for supporting learning as well as research in science and engineering. In particular, technology-based tools in the form of simulations and virtual environments support learning using mathematical models and computational methods. The purpose of this research is to: (a) measure the value added in conveying Thermodynamics of materials concepts with a blended learning environment using computational simulation tools with lectures; and (b) characterize students' use of representational forms to convey their conceptual understanding of core concepts within a learning environment that blended Gibbs computational resource and traditional lectures. A mix-method approach was implemented that included the use of statistical analysis to compare student test performance as a result of interacting with Gibbs tool and the use of Grounded Theory inductive analysis to explore students' use of representational forms to express their understanding of thermodynamics of material concepts. Results for the quantitative study revealed positive gains in students' conceptual understanding before and after interacting with Gibbs tool for the majority of the concepts tested. In addition, insight gained from the qualitative analysis helped provide understanding about how students utilized representational forms in communicating their understanding of thermodynamics of material concepts. Knowledge of how novice students construct meaning in this context will provide insight for engineering education instructors and researchers in understanding students' learning processes in the context of educational environments that integrate expert simulation tools as part of their instructional resources for foundational domain knowledge.

  15. VERY LARGE ARRAY DETECTION OF THE 36 GHz ZEEMAN EFFECT IN DR21W REVISITED

    SciTech Connect

    Momjian, Emmanuel; Sjouwerman, Lorant O.; Fish, Vincent L.

    2012-09-20

    We report on the observation of the 36 GHz methanol maser line in the star-forming region DR21W to accurately measure the Zeeman effect. The Zeeman signature reported by Fish et al. became suspicious after an instrumental effect was discovered in the early days of the commissioning of the Very Large Array Wide-band Digital Architecture correlator. We conclude that the previously reported magnetic field strength of 58 mG (1.7 Hz mG{sup -1}/z) is instrumental in nature and thus incorrect. With the improved performance of the array, we now deduce a 3{sigma} limit of -4.7 to +0.4 mG (1.7 Hz mG{sup -1}/z) for the line-of-sight component of the magnetic field strength in DR21W.

  16. Revisiting the thermal effect on shock wave propagation in weakly ionized plasmas

    NASA Astrophysics Data System (ADS)

    Zhou, Qianhong; Dong, Zhiwei; Yang, Wei

    2016-07-01

    Many researchers have investigated shock propagation in weakly ionized plasmas and observed the following anomalous effects: shock acceleration, shock recovery, shock weakening, shock spreading, and splitting. It was generally accepted that the thermal effect can explain most of the experimental results. However, little attention was paid to the shock recovery. In this paper, the shock wave propagation in weakly ionized plasmas is studied by fluid simulation. It is found that the shock acceleration, weakening, and splitting appear after it enters the plasma (thermal) region. The shock splits into two parts right after it leaves the thermal region. The distance between the splitted shocks keeps decreasing until they recover to one. This paper can explain a whole set of features of the shock wave propagation in weakly ionized plasmas. It is also found that both the shock curvature and the splitting present the same photoacoustic deflection (PAD) signals, so they cannot be distinguished by the PAD experiments.

  17. The efficiency of a group-specific mandated benefit revisited: the effect of infertility mandates.

    PubMed

    Lahey, Joanna N

    2012-01-01

    This paper examines the labor market effects of state health insurance mandates that increase the cost of employing a demographically identifiable group. State mandates requiring that health insurance plans cover infertility treatment raise the relative cost of insuring older women of child-bearing age. Empirically, wages in this group are unaffected, but their total labor input decreases. Workers do not value infertility mandates at cost, and so will not take wage cuts in exchange, leading employers to decrease their demand for this affected and identifiable group. Differences in the empirical effects of mandates found in the literature are explained by a model including variations in the elasticity of demand, moral hazard, ability to identify a group, and adverse selection. PMID:22180892

  18. An old experiment revisited: the Doppler effect in a ripple tank

    NASA Astrophysics Data System (ADS)

    D’Anna, M.; Corridoni, T.

    2016-07-01

    Studying waves on a water surface, in this paper we present an approach to the Doppler effect that enables students to not only perceive it qualitatively, but also to construct experimentally the well known quantitative relations, which are usually introduced in a rather formal way. The interpretation of these relations is then obtained and discussed exploiting space–time diagrams, whose role is emphasized especially in view of extending this approach to phenomena involving light.

  19. Revisiting grating orientation effects on visual contrast sensitivity using optical interferometry

    NASA Astrophysics Data System (ADS)

    Serra, P. M.; Santos, L. F.; Corte-Real, J. P.; Fiadeiro, P. T.

    2014-08-01

    Sinusoidal gratings of equal spatial frequency but different orientation require different levels of contrast to be detected by the human visual system. This phenomenon defined as oblique effect has a neuronal origin. The purpose of this work was to determine the neuronal magnitude of this effect, by isolating it from the optics of the eye. A visual interferometer was assembled to generate and project on the retina an interference pattern consisting of sinusoidal gratings with variable orientation (0º to 165º, 15º step). Adding background light to the interference pattern of 12 cycles/degree (cpd), different contrast levels were generated while the retinal illuminance was kept unaltered. A 2º circular stimulus was presented (during 500 ms) on the fovea producing a retinal illuminance of 134 Td (trolands). The contrast sensitivity threshold of four observers (ages 23, 33, 33, 52 years old) was determined using a Yes-No psychophysical method, and the 50% odds of correct response determined by a Weibull cumulative function. The four observers showed different contrast sensitivity thresholds dependent on the grating orientation. Oblique gratings (≈45º/≈135º) required more contrast to be detected than horizontal and vertical gratings. The maximum differences in contrast sensitivity between orientations ranged from 0.15 to 0.31 log units. The mean contrast threshold across all orientations was then calculated to investigate the effect of age on the contrast sensitivity. It was found a 0.046 log units decrease per decade (r=0.94). Oblique effect is an evident neuronal phenomenon with considerable inter-subject variability, making grating orientation important information in contrast sensitivity evaluation.

  20. Revisiting Wasson's Soma: exploring the effects of preparation on the chemistry of Amanita muscaria.

    PubMed

    Feeney, Kevin

    2010-12-01

    In 1968 R. Gordon Wasson first proposed his groundbreaking theory identifying Soma, the hallucinogenic sacrament of the Vedas, as the Amanita muscaria mushroom. While Wasson's theory has garnered acclaim, it is not without its faults. One omission in Wasson's theory is his failure to explain how pressing and filtering Soma, as described in the Rig Veda, supports his theory of Soma's identity. Several critics have reasoned that such preparation should be unnecessary if equivalent results can be obtained by consuming the raw plant, as is done with other psychoactive mushrooms. In order to address these specific criticisms over 600 anecdotal accounts of Amanita muscaria inebriation were collected and analyzed to determine the impact of preparation on Amanita muscaria's effects. The findings of this study demonstrated that the effects of Amanita muscaria were related to the type of preparation employed, and that its toxic effects were considerably reduced by preparations that paralleled those described for Soma in the Rig Veda. While unlikely to end debate over the identity of Soma, this study's findings help to solidify the foundation of Wasson's theory, and also to demonstrate the importance of preparation in understanding and uncovering the true identity of Soma. PMID:21305914

  1. The Baldwin effect and genetic assimilation: revisiting two mechanisms of evolutionary change mediated by phenotypic plasticity.

    PubMed

    Crispo, Erika

    2007-11-01

    Two different, but related, evolutionary theories pertaining to phenotypic plasticity were proposed by James Mark Baldwin and Conrad Hal Waddington. Unfortunately, these theories are often confused with one another. Baldwin's notion of organic selection posits that plasticity influences whether an individual will survive in a new environment, thus dictating the course of future evolution. Heritable variations can then be selected upon to direct phenotypic evolution (i.e., "orthoplasy"). The combination of these two processes (organic selection and orthoplasy) is now commonly referred to as the "Baldwin effect." Alternately, Waddington's genetic assimilation is a process whereby an environmentally induced phenotype, or "acquired character," becomes canalized through selection acting upon the developmental system. Genetic accommodation is a modern term used to describe the process of heritable changes that occur in response to a novel induction. Genetic accommodation is a key component of the Baldwin effect, and genetic assimilation is a type of genetic accommodation. I here define both the Baldwin effect and genetic assimilation in terms of genetic accommodation, describe cases in which either should occur in nature, and propose that each could play a role in evolutionary diversification. PMID:17714500

  2. Auditory and visual distance perception: The proximity-image effect revisited

    NASA Astrophysics Data System (ADS)

    Zahorik, Pavel

    2003-04-01

    The proximity-image effect [M. B. Gardner, J. Acoust. Soc. Am. 43, 163 (1968)] describes a phenomenon in which the apparent distance of an auditory target is determined by the distance of the nearest plausible visual target rather than by acoustic distance cues. Here this effect is examined using a single visual target (an un-energized loudspeaker) and invisible virtual sound sources. These sources were synthesized from binaural impulse-response measurements at distances ranging from 1 to 5 m (0.25-m steps) in the semi-reverberant room (7.7 m×4.2 m×2.7 m) in which the experiment was conducted. Listeners (n=11) were asked whether or not the auditory target appeared to be at the same distance as the visual target. Within a block of trials, the visual target was placed at a fixed distance of 1.5, 3, or 4.5 m, and the auditory target varied randomly from trial-to-trial over the sample of measurement distances. The resulting psychometric functions are consistent with the proximity-image effect, and can be predicted using a simple model of sensory integration and decision in which perceived auditory space is both compressed in distance and has lower resolution than perceived visual space. [Work supported by NIH-NEI.

  3. Revisiting the picture-superiority effect in symbolic comparisons: do pictures provide privileged access?

    PubMed

    Amrhein, Paul C; McDaniel, Mark A; Waddill, Paula

    2002-09-01

    In 4 experiments, symbolic comparisons were investigated to test semantic-memory retrieval accounts espousing processing advantages for picture over word stimuli. In Experiment 1, participants judged pairs of animal names or pictures by responding to questions probing concrete or abstract attributes (texture or size, ferocity or intelligence). Per pair, attributes were salient or nonsalient concerning their prerated relevance to animals being compared. Distance (near or far) between attribute magnitudes was also varied. Pictures did not significantly speed responding relative to words across all other variables. Advantages were found forfar attribute magnitudes (i.e., the distance effect) and salient attributes. The distance effect was much less for salient than nonsalient concrete-attribute comparisons. These results were consistently found in additional experiments with increased statistical power to detect modality effects. Our findings argue against dual-coding and some common-code accounts of conceptual attribute processing, urging reexamination of the assumption that pictures confer privileged access to long-term knowledge. PMID:12219794

  4. Post-traumatic stress disorder: revisiting adrenergics, glucocorticoids, immune system effects and homeostasis.

    PubMed Central

    Griffin, Gerald D; Charron, Dominique; Al-Daccak, Rheem

    2014-01-01

    This review focuses on post-traumatic stress disorder (PTSD). Several sequelae of PTSD are partially attributed to glucocorticoid-induced neuronal loss in the hippocampus and amygdala. Glucocorticoids and adrenergic agents cause both immediate and late sequelae and are considered from the perspective of their actions on the expression of cytokines as well as some of their physiological and psychological effects. A shift in immune system balance from Th1 to Th2 dominance is thought to result from the actions of both molecular groups. The secretion of glucocorticoids and adrenergic agents is commonly induced by trauma or stress, and synergy between these two parallel but separate pathways can produce long- and short-term sequelae in individuals with PTSD. Potential therapies are suggested, and older therapies that involve the early effects of adrenergics or glucocorticoids are reviewed for their control of acute symptoms. These therapies may also be useful for acute flashback therapy. Timely and more precise glucocorticoid and adrenergic control is recommended for maintaining these molecular groups within acceptable homeostatic limits and thus managing immune and brain sequelae. Psychotherapy should supplement the above therapeutic measures; however, psychotherapy is not the focus of this paper. Instead, this review focuses on the probable molecular basis of PTSD. Integrating historical findings regarding glucocorticoids and adrenergic agents into current research and clinical applications returns the focus to potentially life-changing treatments. Autologous adoptive immune therapy may also offer utility. This paper reports clinical and translational research that connects and challenges separate fields of study, current and classical, in an attempt to better understand and ameliorate the effects of PTSD. PMID:25505957

  5. Strain engineering for mechanical properties in graphene nanoribbons revisited: The warping edge effect

    NASA Astrophysics Data System (ADS)

    Jiang, Jin-Wu

    2016-06-01

    We investigate the strain engineering and the edge effect for mechanical properties in graphene nanoribbons. The free edges of the graphene nanoribbons are warped due to compressive edge stresses. There is a structural transformation for the free edges from the three-dimensional warping configuration to the two-dimensional planar structure at the critical strain ɛc = 0.7%, at which the applied mechanical stress is equal to the intrinsic compressive edge stress. This structural transformation leads to step-like changes in several mechanical properties studied in the present work, including the Young's modulus, the Poisson's ratio, the quality factor of nanomechanical resonators, and the phonon edge mode.

  6. Contextual learning and context effects during infancy: 30 years of controversial research revisited.

    PubMed

    Revillo, D A; Cotella, E; Paglini, M G; Arias, C

    2015-09-01

    Over the last 30years a considerable number of reports have explored learning about context during infancy in both humans and rats. This research was stimulated by two different theoretical frameworks. The first, known as the neuromaturational model, postulates that learning and behavior are context-independent during early ontogeny, a hypothesis based on the idea that contextual learning is dependent on the hippocampal function, and that this brain structure does not reach full maturity until late in infancy. The second theoretical framework views infants not as immature organisms, but rather as perfectly matured ones, given that their behavioral and cognitive capacities allow them to adapt appropriately to the demands of their specific environment in accordance with their maturational level. This model predicts significant ontogenetic variations in learning and memory due to developmental differences in what is perceived and attended to during learning episodes, which can result in ontogenetic differences in contextual learning depending on the specific demands of the task. The present manuscript reviews those studies that have examined potential developmental differences in contextual learning and context effects in rats. The reviewed results show that, during infancy, context can exert a similar influence over learning and memory as that described for the adult rat. Moreover, in some cases, contextual learning and context effects were greater in infants than in adults. In contrast, under other experimental conditions, no evidence of contextual learning or context effects was observed. We analyzed the procedural factors of these studies with the aim of detecting those that favor or impede contextual learning during infancy, and we discussed whether existing empirical evidence supports the claim that the functionality of the hippocampus is a limiting factor for this type of learning during infancy. Finally, conclusions from human research into contextual learning

  7. Cats protecting birds revisited.

    PubMed

    Fan, Meng; Kuang, Yang; Feng, Zhilan

    2005-09-01

    In this paper, we revisit the dynamical interaction among prey (bird), mesopredator (rat), and superpredator (cat) discussed in [Courchamp, F., Langlais, M., Sugihara, G., 1999. Cats protecting birds: modelling the mesopredator release effect. Journal of Animal Ecology 68, 282-292]. First, we develop a prey-mesopredator-superpredator (i.e., bird-rat-cat, briefly, BRC) model, where the predator's functional responses are derived based on the classical Holling's time budget arguments. Our BRC model overcomes several model construction problems in Courchamp et al. (1999), and admits richer, reasonable and realistic dynamics. We explore the possible control strategies to save or restore the bird by controlling or eliminating the rat or the cat when the bird is endangered. We establish the existence of two types of mesopredator release phenomena: severe mesopredator release, where once superpredators are suppressed, a burst of mesopredators follows which leads their shared prey to extinction; and mild mesopredator release, where the mesopredator release could assert more negative impact on the endemic prey but does not lead the endemic prey to extinction. A sharp sufficient criterion is established for the occurrence of severe mesopredator release. We also show that, in a prey-mesopredator-superpredator trophic food web, eradication of introduced superpredators such as feral domestic cats in the BRC model, is not always the best solution to protect endemic insular prey. The presence of a superpredator may have a beneficial effect in such systems. PMID:15998496

  8. The revisited levels of free and bound phenolics in rice: Effects of the extraction procedure.

    PubMed

    Alves, Gabriela Hörnke; Ferreira, Cristiano Dietrich; Vivian, Patrícia Gomes; Monks, Jander Luis Fernandes; Elias, Moacir Cardoso; Vanier, Nathan Levien; de Oliveira, Maurício

    2016-10-01

    The effects of the type of solvolytic solution and number of extraction steps on the recovery of free phenolics, anthocyanins and proanthocyanidins from different rice samples were evaluated. Moreover, bound phenolic acids were determined as a function of enzymatic and/or alkaline hydrolysis treatment of the rice residue obtained after the extraction of free phenolics. The Acetone/Water (70:30 v/v) was the most effective solvolytic solution for extracting free phenolics from pigmented rice, as well as anthocyanins from black and wild rice, and proanthocyanidins from red rice. The application of three extraction steps increased the recovery of free phenolics up to 10%. The adoption of an enzymatic treatment, with α-amylase in order to reduce the paste viscosity of the residue, increased the extractability of bound phenolics. α-Amylase at 37°C during 15min followed by an alkaline hydrolysis at 37°C was the best treatment for the recovery of bound phenolics. PMID:27132831

  9. Viewing time effects revisited: prolonged response latencies for sexually attractive targets under restricted task conditions.

    PubMed

    Imhoff, Roland; Schmidt, Alexander F; Nordsiek, Uta; Luzar, Charlotte; Young, Andrew W; Banse, Rainer

    2010-12-01

    Sexually attractive stimuli are watched longer than unattractive stimuli. The processes underlying this robust and reliable viewing time effect are presently not well understood. In the present research comprising four experiments (total N = 250), four classes of potential explanations are proposed and the derived implications were experimentally tested. Contrary to explanations based on either deliberate delay or attentional adhesion to sexually attractive stimuli, prolonged response latencies were also found under restricted task conditions. Sexually preferred targets elicited longer response latencies in a self-paced evaluation task when stimulus pictures were presented for 750 ms (Experiment 1) or for 500 ms and followed by a pattern mask (Experiment 2). Prolonged latencies for sexually preferred targets were also observed when sexual attractiveness was rated in a speeded binary decision task with a response window of 1000 ms (Experiment 3). Eventually, it was shown that the response latency effect in the speeded binary choice task was still preserved when only the heads of target individuals were presented instead of the bodies (Experiment 4). Mate identification and schematic processes are discussed as the remaining plausible mechanisms for prolonged response latencies for sexually attractive targets under restricted conditions. PMID:20198414

  10. Predator interference effects on biological control: The "paradox" of the generalist predator revisited

    NASA Astrophysics Data System (ADS)

    Parshad, Rana D.; Bhowmick, Suman; Quansah, Emmanuel; Basheer, Aladeen; Upadhyay, Ranjit Kumar

    2016-10-01

    An interesting conundrum in biological control questions the efficiency of generalist predators as biological control agents. Theory suggests, generalist predators are poor agents for biological control, primarily due to mutual interference. However field evidence shows they are actually quite effective in regulating pest densities. In this work we provide a plausible answer to this paradox. We analyze a three species model, where a generalist top predator is introduced into an ecosystem as a biological control, to check the population of a middle predator, that in turn is depredating on a prey species. We show that the inclusion of predator interference alone, can cause the solution of the top predator equation to blow-up in finite time, while there is global existence in the no interference case. This result shows that interference could actually cause a population explosion of the top predator, enabling it to control the target species, thus corroborating recent field evidence. Our results might also partially explain the population explosion of certain species, introduced originally for biological control purposes, such as the cane toad (Bufo marinus) in Australia, which now functions as a generalist top predator. We also show both Turing instability and spatio-temporal chaos in the model. Lastly we investigate time delay effects.

  11. Depth effect on lightness revisited: The role of articulation, proximity and fields of illumination.

    PubMed

    Radonjić, Ana; Gilchrist, Alan L

    2013-01-01

    The coplanar ratio principle proposes that when the luminance range in an image is larger than the canonical reflectance range of 30:1, the lightness of a target surface depends on the luminance ratio between that target and its adjacent coplanar neighbor (Gilchrist, 1980). This conclusion is based on experiments in which changes in the perceived target depth produced large changes in its perceived lightness without significantly altering the observers' retinal image. Using the same paradigm, we explored how this depth effect on lightness depends on display complexity (articulation), proximity of the target to its highest coplanar luminance and spatial distribution of fields of illumination. Importantly, our experiments allowed us to test differing predictions made by the anchoring theory (Gilchrist et al., 1999), the coplanar ratio principle, as well as other models. We report three main findings, generally consistent with anchoring theory predictions: (1) Articulation can substantially increase the depth effect. (2) Target lightness depends not on the adjacent luminance but on the highest coplanar luminance, irrespective of its position relative to the target. (3) When a plane contains multiple fields of illumination, target lightness depends on the highest luminance in its field of illumination, not on the highest coplanar luminance. PMID:24349701

  12. The Community College Effect Revisited: The Importance of Attending to Heterogeneity and Complex Counterfactuals*

    PubMed Central

    Brand, Jennie E.; Pfeffer, Fabian T.; Goldrick-Rab, Sara

    2015-01-01

    Community colleges are controversial educational institutions, often said to simultaneously expand college opportunities and diminish baccalaureate attainment. We assess the seemingly contradictory functions of community colleges by attending to effect heterogeneity and to alternative counterfactual conditions. Using data on postsecondary outcomes of high school graduates of Chicago Public Schools, we find that enrolling at a community college penalizes more advantaged students who otherwise would have attended four-year colleges, particularly highly selective schools; however, these students represent a relatively small portion of the community college population, and these estimates are almost certainly biased. On the other hand, enrolling at a community college has a modest positive effect on bachelor's degree completion for disadvantaged students who otherwise would not have attended college; these students represent the majority of community college goers. We conclude that discussions among scholars, policymakers, and practitioners should move beyond considering the pros and cons of community college attendance for students in general to attending to the implications of community college attendance for targeted groups of students. PMID:25825705

  13. Revisiting within-modality and cross-modality attentional blinks: effects of target-distractor similarity.

    PubMed

    Arnell, Karen M; Jenkins, Ryan

    2004-10-01

    When two masked targets (T1 and T2) require attention and are presented within half a second of each other, the report accuracy for T2 is reduced, relative to when the two targets are presented farther apart in time. This effect is known as the attentional blink (AB). Potter, Chun, Banks, and Muckenhoupt (1998) argued that all AB-like effects observed when at least one of the targets was presented outside of the visual modality did not represent true instances of the AB, but instead were artifacts of task-set switching. However, in the Potter et al. experiments the presence or absence of task-set switching opportunities was confounded with the T2 task, as well as the alphanumeric class of T2 with respect to the distractors. In the present experiment, we examine the influence of T1 alphanumeric class, T2 alphanumeric class, and switching operations in a fully crossed design that unconfounds these factors. In contrast to the conclusions of Potter et al., the present results suggest that the T2 alphanumeric class can account for the pattern of ABs observed across conditions, without necessarily implicating a separate switch cost. The implications for theoretical models of the AB and the debate over the validity of cross-modal ABs are discussed. PMID:15751472

  14. Position-effect variegation revisited: HUSHing up heterochromatin in human cells.

    PubMed

    Timms, Richard T; Tchasovnikarova, Iva A; Lehner, Paul J

    2016-04-01

    Much of what we understand about heterochromatin formation in mammals has been extrapolated from forward genetic screens for modifiers of position-effect variegation (PEV) in the fruit fly Drosophila melanogaster. The recent identification of the HUSH (Human Silencing Hub) complex suggests that more recent evolutionary developments contribute to the mechanisms underlying PEV in human cells. Although HUSH-mediated repression also involves heterochromatin spreading through the reading and writing of the repressive H3K9me3 histone modification, clear orthologues of HUSH subunits are not found in Drosophila but are conserved in vertebrates. Here we compare the insights into the mechanisms of PEV derived from genetic screens in the fly, the mouse and in human cells, review what is currently known about the HUSH complex and discuss the implications of HUSH-mediated silencing for viral latency. Future studies will provide mechanistic insight into HUSH complex function and reveal the relationship between HUSH and other epigenetic silencing complexes. PMID:26853531

  15. Chowchilla revisited: the effects of psychic trauma four years after a school-bus kidnapping.

    PubMed

    Terr, L C

    1983-12-01

    A 4-year follow-up study of 25 school-bus kidnapping victims and one child who narrowly missed the experience revealed that every child exhibited posttraumatic effects. Symptom severity was related to the child's prior vulnerabilities, family pathology, and community bonding. Important new findings included pessimism about the future, belief in omens and prediction, memories of incorrect perceptions, thought suppression, shame, fear of reexperiencing traumatic anxiety, trauma-specific and mundane fears, posttraumatic play, behavioral reenactment, repetitions of psychophysiological disturbances that began with the kidnapping, repeated nightmares, and dreams of personal death. Brief treatment 5-13 months after the kidnapping did not prevent symptoms and signs 4 years later. PMID:6650683

  16. Nernst effect of the intermediate valence compound YbAl3: revisiting the thermoelectric properties.

    PubMed

    Wei, Beipei; Zhang, Jiahao; Sun, Peijie; Wang, Wenquan; Wang, Nanlin; Steglich, Frank

    2015-03-18

    The Nernst effect and thermopower of the prototypical Yb-based intermediate valence compound YbAl(3) were investigated. Different to the thermopower whose absolute values are enhanced with increasing temperature and assume a broad maximum at 175 K, the Nernst coefficient of YbAl(3) is enhanced only below T ≈ 75 K. While the two quantities in the heavy-fermion compound CeCu(2)Si(2) were recently found to be related by the anomalous Hall mobility due to the local asymmetric Kondo scattering, this theorem fails when being applied to YbAl(3). Rather, the thermopower of YbAl(3) is well described by a simple narrow-band model. We discuss the reason for this in terms of the intermediate valence nature of YbAl(3) that is conceptually different from the local Kondo physics. PMID:25706931

  17. Revisiting visco-elastic effects on interseismic deformation and locking degree: Case study of Chilean margin

    NASA Astrophysics Data System (ADS)

    Li, Shaoyang; Moreno, Marcos; Bedford, Jonathan; Rosenau, Matthias; Oncken, Onno

    2015-04-01

    Viscoelastic effects are thought to play an important role during all phases of the earthquake cycle in subduction zones. However, models rarely consider the viscoelastic relaxation effects present in the interseismic deformation measurements. Here we use synthetic Finite Element Method (FEM) models to investigate the control of viscoelasticity on interseismic deformation and to present the pitfalls of interpreting the data with elastic models for both the forward and inverse problems. Additionally, we construct a 3-D spherical FEM model of the entire Chilean Subduction Zone constrained by GPS data to estimate along-strike variations of locking degree. Our results confirm that elastic models can overestimate the interseismic locking depth. The application of the viscoelastic model, rather than the elastic model, improves the fit to the interseismic deformation, especially in the inland area. Part of the signals previously interpreted as back-arc shortening in elastic models can be alternatively explained by viscoelastic deformation, which, in turn, refines the interseismic locking pattern in both dip and strike directions. Our viscoelastic locking map exhibits very good correlation with the slips of previous earthquakes and present the transitional limits between wide locked regions to dominantly creeping sections, proving a detailed view of the locking state useful to determine slip deficit. We conclude that incorrect elastic assumptions affect the analysis of interseismic deformation build up mechanism and the calculated slip deficit. Our results thus suggest that it is necessary to thoroughly re-evaluate the elastic locking models, some of which potentially attribute viscoelastic deformation to different sources as e.g. microplate sliver motions

  18. Prioritization and the elusive effect on welfare - a Norwegian health care reform revisited.

    PubMed

    Aakvik, Arild; Holmås, Tor Helge; Kjerstad, Egil

    2015-03-01

    The Faster Return to Work (FRW) scheme that Norwegian authorities implemented in 2007 is an example of a policy that builds on the human capital approach. The main idea behind the scheme is that long waiting times for hospital treatment lead to unnecessarily long periods of absence from work. To achieve a reduction in average sickness absence duration, the allocation of FRW funds and new treatment capacity is exclusively aimed at people on sick leave. Many countries have allocated funds to reduce waiting times for hospital treatment and research shows that more resources allocated to the hospital sector can reduce waiting times. Our results support this as the FRW scheme significantly reduces waiting times. However, on average the reduction in waiting times is not transformed into an equally large reduction in the sickness absence period. We find significant difference in the effects of FRW on length of sick leave between surgical and non-surgical patients though. The duration of sick leave for FRW patients undergoing surgical treatment is approximately 14 days shorter than for surgical patients on the regular waiting list. We find no significant effect of the scheme on length of sick leave for non-surgical patients. In sum, our welfare analysis indicates that prioritization of the kind that the FRW scheme represents is not as straightforward as one would expect. The FRW scheme costs more than it contributes in reduced productivity loss. We base our analyses on several different econometric methods using register data on approximately 13,500 individuals over the period 2007-2008. PMID:25637910

  19. Doppler ultrasound--basics revisited.

    PubMed

    Eagle, Mary

    Palpation of pedal pulses alone is known to be an unreliable indicator for the presence of arterial disease. Using portable Doppler ultrasound to measure the resting ankle brachial pressure index is superior to palpation of peripheral pulses as an assessment of the adequacy pf the arterial supply in the lower limb. Revisiting basics, this article aims to aid the clinician to understand and perform hand-held Doppler ultrasound effectively while involving the client or patient in the process. The author describes the basics of Doppler ultrasound, how to select correct equipment for the process, and interpretation of results to further enhance clinicians' knowledge. PMID:16835512

  20. The Raspberry model for hydrodynamic interactions revisited. II. The effect of confinement

    NASA Astrophysics Data System (ADS)

    de Graaf, Joost; Peter, Toni; Fischer, Lukas P.; Holm, Christian

    2015-08-01

    The so-called "raspberry" model refers to the hybrid lattice-Boltzmann (LB) and Langevin molecular dynamics schemes for simulating the dynamics of suspensions of colloidal particles, originally developed by Lobaskin and Dünweg [New J. Phys. 6, 54 (2004)], wherein discrete surface points are used to achieve fluid-particle coupling. In this paper, we present a follow up to our study of the effectiveness of the raspberry model in reproducing hydrodynamic interactions in the Stokes regime for spheres arranged in a simple-cubic crystal [Fischer et al., J. Chem. Phys. 143, 084107 (2015)]. Here, we consider the accuracy with which the raspberry model is able to reproduce such interactions for particles confined between two parallel plates. To this end, we compare our LB simulation results to established theoretical expressions and finite-element calculations. We show that there is a discrepancy between the translational and rotational mobilities when only surface coupling points are used, as also found in Part I of our joint publication. We demonstrate that adding internal coupling points to the raspberry can be used to correct said discrepancy in confining geometries as well. Finally, we show that the raspberry model accurately reproduces hydrodynamic interactions between a spherical colloid and planar walls up to roughly one LB lattice spacing.

  1. Revisiting Aerosol Effects in Global Climate Models Using an Aerosol Lidar Simulator

    NASA Astrophysics Data System (ADS)

    Ma, P. L.; Chepfer, H.; Winker, D. M.; Ghan, S.; Rasch, P. J.

    2015-12-01

    Aerosol effects are considered a major source of uncertainty in global climate models and the direct and indirect radiative forcings have strong model dependency. These forcings are routinely evaluated (and calibrated) against observations, among them satellite retrievals are greatly used for their near-global coverage. However, the forcings calculated from model output are not directly comparable with those computed from satellite retrievals since sampling and algorithmic differences (such as cloud screening, noise reduction, and retrieval) between models and observations are not accounted for. It is our hypothesis that the conventional model validation procedures for comparing satellite observations and model simulations can mislead model development and introduce biases. Hence, we have developed an aerosol lidar simulator for global climate models that simulates the CALIOP lidar signal at 532nm. The simulator uses the same algorithms as those used to produce the "GCM-oriented CALIPSO Aerosol Product" to (1) objectively sample lidar signal profiles; and (2) derive aerosol fields (e.g., extinction profile, aerosol type, etc) from lidar signals. This allows us to sample and derive aerosol fields in the model and real atmosphere in identical ways. Using the Department of Energy's ACME model simulations, we found that the simulator-retrieved aerosol distribution and aerosol-cloud interactions are significantly different from those computed from conventional approaches, and that the model is much closer to satellite estimates than previously believed.

  2. Cretinism revisited.

    PubMed

    Chen, Zu-Pei; Hetzel, Basil S

    2010-02-01

    Endemic cretinism includes two syndromes: a more common neurological disorder with brain damage, deaf mutism, squint and spastic paresis of the legs and a less common syndrome of severe hypothyroidism, growth retardation and less severe mental defect. Both conditions are due to dietary iodine deficiency and can be prevented by correction of iodine deficiency before pregnancy. Endemic cretinism is now included in the spectrum of the effects of iodine deficiency in a population termed the 'iodine deficiency disorders (IDDs)', which also includes a wide range of lesser degrees of cognitive defect that can be prevented by the correction of iodine deficiency. Iodine deficiency is now recognised by the World Health Organization (WHO) as the most common preventable cause of brain damage with in excess of 2 billion at risk from 130 countries. A global United Nations (UN) programme of prevention has achieved 68% household usage of iodised salt by the year 2000 compared with less than 20% prior to 1990. PMID:20172469

  3. The Cyclopentadienyl Radical Revisited: the Effects of Asymmetric Deuteration of Jahn-Teller Molecules

    NASA Astrophysics Data System (ADS)

    Strom, Samantha; Liu, Jinjun

    2012-06-01

    Asymmetric deuteration of Jahn-Teller active molecules partially lifts the vibronic degeneracy and hence provides a unique approach to understanding the Jahn-Teller effect. Previously, a spectroscopic model was proposed and used to simulate the spectra of the asymmetrically deuterated isotopomers of the methoxy radical. The same model has been implemented and successfully simulated the previously reported high-resolution laser-induced fluorescence (LIF) spectra of the asymmetrically deuterated cyclopentadienyl radical (C_5H_4D and C_5HD_4). A joint fitting of the transitions from both of the zero-point levels of the tilde X ^2E''_1 ground electronic state, split by the asymmetric deuteration, to the tilde A ^2A''_2 state yields one set of molecular constants for both levels, which, when combined with molecular constants of C_5H_5 and C_5D_5, can be used to determine the molecular geometry and magnitude of the Jahn-Teller distortion. The main goal of this new investigation is to resolve the discrepancy between the experimentally determined and the ab initio calculated Jahn-Teller distortion. In addition, a theoretic model is proposed to quantitatively reproduce the splitting of the zero-point level due to the asymmetric deuteration and zero-point energies for the Jahn-Teller distorted structures around the conical intersection. D. G. Melnik, J. Liu, R. F. Curl, and T. A. Miller, Mol. Phys. 105, 529 (2007). D. G. Melnik, J. Liu, M.-W. Chen, T. A. Miller, and R. F. Curl, J. Chem. Phys. 135, 094310 (2011) L. Yu, D.W. Cullin, J.M. Williamson, and T.A. Miller, J. Chem. Phys. 98, 2682 (1993). M. J. Bearpark, M. A. Robb, and N. Yamamoto, Spectrochim. Acta Part A 55, 639 (1999).

  4. Prediction of cavitation performance and choking flow limit of inducers for cold water and for fluids with thermodynamic effect

    NASA Astrophysics Data System (ADS)

    Sauvage-Boutar, E.; Desclaux, J.

    1990-07-01

    Two methods of prediction of partial cavitation in inducers of rocket engine turbopumps have been developed. The first one is an analytical method previously developed to predict minimum NPSH (inlet total head minus vapor pressure) and the choking flow limit which was modified to include the computation of blade and boundary layer blockage. The second one is a method based on the work of Moore and Ruggeri (1969). This method takes into account thermodynamic effect for the prediction of the cavitation parameter Ki. For the choking flow limit, the first method can be extended to cryogenic fluids. Comparisons with available experimental data obtained with VULCAIN inducer pumping water and liquid hydrogen are presented.

  5. Theoretical Thermodynamics Study of Polyamidoamine Deposited Around a Nanotube as Motor Controlled by Light and Under Temperature Effect.

    PubMed

    Santos, Julio C S; Costa, J F S; Neto, J C; Borges, R S; Ramalho, Teodorico C; Chen, James; Machado, Nélio T

    2015-04-01

    We simulated a system like a Polyamidoamine (PAMAM) deposited on open carbon nanotube. We used five first generation PAMAM. The initial position of PAMAM is out of CN symmetry position. It permits the PAMAM to relax around the nanotube due to van der Waals force. After that, we have analyzed the thermal effects on behavior of 4G PAMAM. We performed computational simulation using classical molecular dynamics with standard parameterization. The thermodynamics properties of this device as molar specific heat and molar entropy variation were calculated. The CN has 690 carbon atoms with up to almost 0.1 ns of simulation. PMID:26353502

  6. Thermoset recycling via high-pressure high-temperature sintering: Revisiting the effect of interchange chemistry

    NASA Astrophysics Data System (ADS)

    Morin, Jeremy Edward

    In 1844 Charles Goodyear obtained U.S. Patent #3,633 for his "Gum Elastic Composition". In a published circular, which describes his patent for the sulfur vulcanization of gum elastic composition, he stated: "No degree of heat, without blaze, can melt it (rubber)... It resists the most powerful chemical reagents. Aquafortis (nitric acid), sulphuric acid, essential and common oils, turpentine and other solvents... ..." Goodyear's sulfur vulcanization of rubber fueled much of the industrial revolution and made transportation possible, as it exists today. In doing so, Goodyear created one of the most difficult materials to recycle. Rubber will not melt, dissolve, or lend itself to the usual methods of chemical decomposition. Ironically, Goodyear recognized this problem and in 1853 he patented the process of adding ground rubber to virgin material, now currently known as regrind blending. Today, scrap tires represent one of the most serious sources of pollution in the world. Studies estimate that there are roughly 2 billion scrap tires in U.S. landfills and more are being added at a rate of over 273 million tires per year. Current methods of recycling waste tires are crude, ineffective, and use rubber powder as a low cost filler instead of a new rubber. The groundwork for a very simple and effective method of producing high-quality rubber goods using 100% scrap rubber was discovered in 1944 by A. V. Tobolsky et al. This application, however, was not recognized until recently in our laboratory. The process as studied to date represents a method of creating quality, high-value added rubber goods with nothing other than heat and pressure. High pressure is required to obtain a void-free compaction of the rubber particles by forcing all of the free surfaces into intimate contact. High temperature then activates the chemical rearrangement, scission, and reformation of the chemical bonds thus providing new bridges between the once fractured interfaces. This occurs both within

  7. Lorentz violation naturalness revisited

    NASA Astrophysics Data System (ADS)

    Belenchia, Alessio; Gambassi, Andrea; Liberati, Stefano

    2016-06-01

    We revisit here the naturalness problem of Lorentz invariance violations on a simple toy model of a scalar field coupled to a fermion field via a Yukawa interaction. We first review some well-known results concerning the low-energy percolation of Lorentz violation from high energies, presenting some details of the analysis not explicitly discussed in the literature and discussing some previously unnoticed subtleties. We then show how a separation between the scale of validity of the effective field theory and that one of Lorentz invariance violations can hinder this low-energy percolation. While such protection mechanism was previously considered in the literature, we provide here a simple illustration of how it works and of its general features. Finally, we consider a case in which dissipation is present, showing that the dissipative behaviour does not percolate generically to lower mass dimension operators albeit dispersion does. Moreover, we show that a scale separation can protect from unsuppressed low-energy percolation also in this case.

  8. Remote Sensing the Vertical Profile of Cloud Droplet Effective Radius, Thermodynamic Phase, and Temperature

    NASA Technical Reports Server (NTRS)

    Martins, J. V.; Marshak, A.; Remer, L. A.; Rosenfeld, D.; Kaufman, Y. J.; Fernandez-Borda, R.; Koren, I.; Correia, A. L.; Zubko, V.; Artaxo, P.

    2011-01-01

    Cloud-aerosol interaction is a key issue in the climate system, affecting the water cycle, the weather, and the total energy balance including the spatial and temporal distribution of latent heat release. Information on the vertical distribution of cloud droplet microphysics and thermodynamic phase as a function of temperature or height, can be correlated with details of the aerosol field to provide insight on how these particles are affecting cloud properties and their consequences to cloud lifetime, precipitation, water cycle, and general energy balance. Unfortunately, today's experimental methods still lack the observational tools that can characterize the true evolution of the cloud microphysical, spatial and temporal structure in the cloud droplet scale, and then link these characteristics to environmental factors and properties of the cloud condensation nuclei. Here we propose and demonstrate a new experimental approach (the cloud scanner instrument) that provides the microphysical information missed in current experiments and remote sensing options. Cloud scanner measurements can be performed from aircraft, ground, or satellite by scanning the side of the clouds from the base to the top, providing us with the unique opportunity of obtaining snapshots of the cloud droplet microphysical and thermodynamic states as a function of height and brightness temperature in clouds at several development stages. The brightness temperature profile of the cloud side can be directly associated with the thermodynamic phase of the droplets to provide information on the glaciation temperature as a function of different ambient conditions, aerosol concentration, and type. An aircraft prototype of the cloud scanner was built and flew in a field campaign in Brazil.

  9. Viscoplasticity: A thermodynamic formulation

    NASA Technical Reports Server (NTRS)

    Freed, A. D.; Chaboche, J. L.

    1989-01-01

    A thermodynamic foundation using the concept of internal state variables is given for a general theory of viscoplasticity, as it applies to initially isotropic materials. Three fundamental internal state variables are admitted. They are: a tensor valued back stress for kinematic effects, and the scalar valued drag and yield strengths for isotropic effects. All three are considered to phenomenologically evolve according to competitive processes between strain hardening, strain induced dynamic recovery, and time induced static recovery. Within this phenomenological framework, a thermodynamically admissible set of evolution equations is put forth. This theory allows each of the three fundamental internal variables to be composed as a sum of independently evolving constituents.

  10. Bulk and boundary effects on the decay of the thermodynamic Casimir force

    NASA Astrophysics Data System (ADS)

    Delfino, Gesualdo; Squarcini, Alessio

    2015-01-01

    We consider the decay of the thermodynamic Casimir force in phases with a finite correlation length. For the case of the strip, we use properties of low-energy two-dimensional field theory to show that the decay depends on the symmetry properties of the boundary conditions, in distinctive ways that we determine exactly. Features characteristic of the bulk universality class may induce modifications that we also discuss. Symmetry-breaking and symmetry-preserving boundary conditions exchange their role with respect to the decay of the force when exchanging spontaneously broken with disordered phases. Several of our arguments extend to higher dimensions.

  11. Effects of a Maximal Energy Scale in Thermodynamics for Photon Gas and Construction of Path Integral

    NASA Astrophysics Data System (ADS)

    Das, Sudipta; Pramanik, Souvik; Ghosh, Subir

    2014-11-01

    In this article, we discuss some well-known theoretical models where an observer-independent energy scale or a length scale is present. The presence of this invariant scale necessarily deforms the Lorentz symmetry. We study different aspects and features of such theories about how modifications arise due to this cutoff scale. First we study the formulation of energy-momentum tensor for a perfect fluid in doubly special relativity (DSR), where an energy scale is present. Then we go on to study modifications in thermodynamic properties of photon gas in DSR. Finally we discuss some models with generalized uncertainty principle (GUP).

  12. An analysis of quantum effects on the thermodynamic properties of cryogenic hydrogen using the path integral method.

    PubMed

    Nagashima, H; Tsuda, S; Tsuboi, N; Koshi, M; Hayashi, K A; Tokumasu, T

    2014-04-01

    In this paper, we describe the analysis of the thermodynamic properties of cryogenic hydrogen using classical molecular dynamics (MD) and path integral MD (PIMD) method to understand the effects of the quantum nature of hydrogen molecules. We performed constant NVE MD simulations across a wide density-temperature region to establish an equation of state (EOS). Moreover, the quantum effect on the difference of molecular mechanism of pressure-volume-temperature relationship was addressed. The EOS was derived based on the classical mechanism idea only using the MD simulation results. Simulation results were compared with each MD method and experimental data. As a result, it was confirmed that although the EOS on the basis of classical MD cannot reproduce the experimental data of saturation property of hydrogen in the high-density region, the EOS on the basis of PIMD well reproduces those thermodynamic properties of hydrogen. Moreover, it was clarified that taking quantum effects into account makes the repulsion force larger and the potential well shallower. Because of this mechanism, the intermolecular interaction of hydrogen molecules diminishes and the virial pressure increases. PMID:24712800

  13. The effect of particle size on the morphology and thermodynamics of diblock copolymer/tethered-particle membranes

    SciTech Connect

    Zhang, Bo; Edwards, Brian J.

    2015-06-07

    A combination of self-consistent field theory and density functional theory was used to examine the effect of particle size on the stable, 3-dimensional equilibrium morphologies formed by diblock copolymers with a tethered nanoparticle attached either between the two blocks or at the end of one of the blocks. Particle size was varied between one and four tenths of the radius of gyration of the diblock polymer chain for neutral particles as well as those either favoring or disfavoring segments of the copolymer blocks. Phase diagrams were constructed and analyzed in terms of thermodynamic diagrams to understand the physics associated with the molecular-level self-assembly processes. Typical morphologies were observed, such as lamellar, spheroidal, cylindrical, gyroidal, and perforated lamellar, with the primary concentration region of the tethered particles being influenced heavily by particle size and tethering location, strength of the particle-segment energetic interactions, chain length, and copolymer radius of gyration. The effect of the simulation box size on the observed morphology and system thermodynamics was also investigated, indicating possible effects of confinement upon the system self-assembly processes.

  14. An analysis of quantum effects on the thermodynamic properties of cryogenic hydrogen using the path integral method

    SciTech Connect

    Nagashima, H.; Tsuda, S.; Tsuboi, N.; Koshi, M.; Hayashi, K. A.; Tokumasu, T.

    2014-04-07

    In this paper, we describe the analysis of the thermodynamic properties of cryogenic hydrogen using classical molecular dynamics (MD) and path integral MD (PIMD) method to understand the effects of the quantum nature of hydrogen molecules. We performed constant NVE MD simulations across a wide density–temperature region to establish an equation of state (EOS). Moreover, the quantum effect on the difference of molecular mechanism of pressure–volume–temperature relationship was addressed. The EOS was derived based on the classical mechanism idea only using the MD simulation results. Simulation results were compared with each MD method and experimental data. As a result, it was confirmed that although the EOS on the basis of classical MD cannot reproduce the experimental data of saturation property of hydrogen in the high-density region, the EOS on the basis of PIMD well reproduces those thermodynamic properties of hydrogen. Moreover, it was clarified that taking quantum effects into account makes the repulsion force larger and the potential well shallower. Because of this mechanism, the intermolecular interaction of hydrogen molecules diminishes and the virial pressure increases.

  15. Panspermia revisited

    NASA Astrophysics Data System (ADS)

    Horneck, Gerda

    "Panspermia", coined by S. Arrhenius in 1903, suggests that microscopic forms of life, e.g., bacterial spores, can be dispersed in space by the radiation pressure from the Sun thereby seeding life from one planet to another or even beyond our Solar System. Being ignored for almost the rest of the century, the scenario of interplanetary transfer of life has received increased support from recent discoveries, such as the detection of Martian meteorites and the high resistance of microorganisms to outer space conditions. With the aid of space technology and adequate laboratory devices the following decisive step required for viable transfer from one planet to another have been tested: (i) the escape process, i.e. impact ejection into space; (ii) the journey through space over extended periods of time; and (iii) the landing process, i.e. non-destructive deposition of the biological material on another planet. In systematic shock recovery experiments within a pressure range observed in Martian meteorites (5-50 GPa) a vital launch window of 5-40 GPa has been determined for spores of Bacillus subtilis and the lichen Xanthoria elegans, whereas this window was restricted to 5-10 GPa for the endolithic cyanobaterium Chroococcidiopsis. Traveling through space implies exposure to high vacuum, an intense radiation regime of cosmic and solar origin and high temperature fluctuations. In several space experiments the biological efficiency of these different space parameters has been tested: extraterrestrial solar UV radiation has exerted the most deleterious effects to viruses, as well as to bacterial and fungal spores; however shielding against this intense insolation resulted in 70 % survival of B. subtilis spores after spending 6 years in outer space. Lichens survived 2 weeks in space, even without any shielding. The entry process of microorganisms has been recently tested in the STONE facility attached to the heat shield of a reentry capsule. The data support the scenario of

  16. Thermodynamic modelling of the effect of temperature on the hydration and porosity of Portland cement

    SciTech Connect

    Lothenbach, Barbara Matschei, Thomas; Moeschner, Goeril; Glasser, Fred P.

    2008-01-15

    The composition of the phase assemblage and the pore solution of Portland cements hydrated between 0 and 60 deg. C were modelled as a function of time and temperature. The results of thermodynamic modelling showed a good agreement with the experimental data gained at 5, 20, and 50 deg. C. At 5 and at 20 deg. C, a similar phase assemblage was calculated to be present, while at approximately 50 deg. C, thermodynamic calculations predicted the conversion of ettringite and monocarbonate to monosulphate. Modelling showed that in Portland cements which have an Al{sub 2}O{sub 3}/SO{sub 3} ratio of > 1.3 (bulk weight), above 50 deg. C monosulphate and monocarbonate are present. In Portland cements which contain less Al (Al{sub 2}O{sub 3}/SO{sub 3} < 1.3), above 50 deg. C monosulphate and small amounts of ettringite are expected to persist. A good correlation between calculated porosity and measured compressive strength was observed.

  17. Inviscid spatial stability of a compressible mixing layer. Part 3: Effect of thermodynamics

    NASA Technical Reports Server (NTRS)

    Jackson, T. L.; Grosch, C. E.

    1989-01-01

    The results of a comprehensive comparative study of the inviscid spatial stability of a parallel compressible mixing layer using various models for the mean flow are reported. The models are: (1) the hyperbolic tangent profile for the mean speed and the Crocco relation for the mean temperature, with the Chapman viscosity-temperature relation and a Prandtl number of one; (2) the Lock profile for the mean speed and the Crocco relation for the mean temperature, with the Chapman viscosity-temperature relation and a Prandtl number of one; and (3) the similarity solution for the coupled velocity and temperature equations using the Sutherland viscosity temperature relation and arbitrary but constant Prandtl number. The purpose was to determine the sensitivity of the stability characteristics of the compressible mixing layer to the assumed thermodynamic properties of the fluid. It is shown that the quantative features of the stability characteristics are quite similiar for all models but that there are quantitative differences resulting from the difference in the thermodynamic models. In particular, it is shown that the stability characteristics are sensitive to the value of the Prandtl number.

  18. Thermodynamic Casimir effect for films in the three-dimensional Ising universality class: Symmetry-breaking boundary conditions

    NASA Astrophysics Data System (ADS)

    Hasenbusch, Martin

    2010-09-01

    We study the thermodynamic Casimir force for films in the three-dimensional Ising universality class with symmetry-breaking boundary conditions. To this end we simulate the improved Blume-Capel model on the simple cubic lattice. We study the two cases ++ , where all spins at the boundary are fixed to +1 and +- , where the spins at one boundary are fixed to +1 while those at the other boundary are fixed to -1 . An important issue in analyzing Monte Carlo and experimental data are corrections to scaling. Since we simulate an improved model, leading corrections to scaling, which are proportional to L0-ω , where L0 is the thickness of the film and ω≈0.8 , can be ignored. This allows us to focus on corrections to scaling that are caused by the boundary conditions. The analysis of our data shows that these corrections can be accounted for by an effective thickness L0,eff=L0+Ls . Studying the correlation length of the films, the energy per area, the magnetization profile, and the thermodynamic Casimir force at the bulk critical point we find Ls=1.9(1) for our model and the boundary conditions discussed here. Using this result for Ls we find a nice collapse of the finite-size scaling curves obtained for the thicknesses L0=8.5 , 16.5, and 32.5 for the full range of temperatures that we consider. We compare our results for the finite-size scaling functions θ++ and θ+- of the thermodynamic Casimir force with those obtained in a previous Monte Carlo study, by the de Gennes-Fisher local-functional method, field theoretic methods, and an experiment with a classical binary liquid mixture.

  19. Entanglement thermodynamics

    NASA Astrophysics Data System (ADS)

    Schliemann, John

    2014-09-01

    We investigate further the relationship between the entanglement spectrum of a composite many-body system and the energy spectrum of a subsystem making use of concepts of canonical thermodynamics. In many important cases the entanglement Hamiltonian is, in the limit of strong coupling between subsystems, proportional to the energy Hamiltonian of the subsystem. The proportionality factor is an appropriately defined coupling parameter, suggesting to interpret the latter as a inverse temperature. We identify a condition on the entanglement Hamiltonian which rigorously guarantees this interpretation to hold and removes any ambiguity in the definition of the entanglement Hamiltonian regarding contributions proportional to the unit operator. Illustrations of our findings are provided by spin ladders of arbitrary spin length, and by bilayer quantum Hall systems at total filling factor ν = 2. Within mean-field description, the latter system realizes an entanglement spectrum of free fermions with just two levels of equal modulus where the analogies to canonical thermodynamics are particularly close.

  20. Effects of scandium composition on the structural, electronic, and thermodynamic properties of SCxY1-x metallic alloys

    NASA Astrophysics Data System (ADS)

    López-Pérez, W.; Castro-Diago, P.; Ramírez-Montes, L.; González-García, A.; González-Hernández, R.

    2016-02-01

    The aim of this work is to analyse the compositional dependence of the structural, electronic and thermodynamic properties of ? alloys. Density functional calculations have been carried out to reveal compositional dependence of the structural, electronic and thermodynamic properties of ? alloys. The lattice constants of the binary compounds are in fairly good agreement with the available experimental data. The variation of calculated lattice constant with scandium concentration is almost linear, and shows a slight deviation from Vegard's law. The effect of scandium composition on bulk modulus gives nonlinear dependence on concentration x. A small deviation of the bulk modulus from linear concentration dependence was observed. The metallic nature of binary precursor compounds ScP and YP was confirmed. Our findings indicate that the ? alloys are metallic for ? 0.25, 0.5, 0.75. The calculated excess mixing enthalpy is positive over the entire scandium composition range. The positive mixing enthalpies indicate meta-stability of the ? alloys at high temperatures. The effect of temperature on the volume, bulk modulus, Debye temperature and the heat capacity for ? alloys were analysed using the quasi-harmonic Debye model. Results show that the heat capacity is slightly sensitive to composition as temperature increases.

  1. Study of wetting on chemically soften interfaces by using combined solution thermodynamics and DFT calculations: forecasting effective softening elements.

    PubMed

    Shu, Guo Gang; Xu, Qiang; Wu, Ping

    2015-04-15

    Despite recent progress in understanding the wetting principles on soft solids, the roles of chemical bonding in the formation of interfaces have been largely ignored, because most of these studies are conducted at room temperatures. Here we propose a universal wetting principle from solution thermodynamics to account for the softening of both the solid and liquid surfaces (stable or metastable). Density functional theory (DFT) calculations are applied to evaluate the stability and electron transportation across the interfaces. We find that wetting is dominated by the system entropy changes involving not only the stable liquid alloy phase but also the metastable liquid oxide phases. The state-of-art multicomponent solution thermodynamic models and databases are applied to describe the entropy changes and predict the wetting behaviors. Our results show that by chemically softening either the liquid or the solid phase, the wetting angle reduces. And an effective soften agent/additive (either in the form of chemical elements or molecules) will weaken the bonds within the liquid (or solid) phase and promote new bonds at the interfaces, thus increasing the interface entropy. Subsequently, as an example, Ti and Zr are proposed as effective softening elements to improve the wetting of aluminum liquid on B6Si(s). This approach provides a concept and tool to advance research in catalytic chemistry, nucleation (growth), elastowetting, and cell-substrate interactions. PMID:25844936

  2. Effects of surface charge on interfacial interactions related to membrane fouling in a submerged membrane bioreactor based on thermodynamic analysis.

    PubMed

    Cai, Huihui; Fan, Hao; Zhao, Leihong; Hong, Huachang; Shen, Liguo; He, Yiming; Lin, Hongjun; Chen, Jianrong

    2016-03-01

    Effects of both membrane and sludge foulant surface zeta potentials on interfacial interactions between membrane and sludge foulant in different interaction scenarios were systematically investigated based on thermodynamic methods. Under conditions in this study, it was found that zeta potential had marginal effects on total interfacial interaction between two infinite planar surfaces, and the total interfacial interaction between foulant particles and membrane would be more repulsive with increase of absolute value of zeta potential. Adhesion of foulant particles on membrane surface should overcome an energy barrier. There exists a critical zeta potential below which energy barrier would disappear. Results also showed that rough surface membrane corresponded to significantly low strength of interfacial interactions. This study not only provided a series of methods to quantitatively assess the interfacial interactions between membrane and sludge foulants, but also reconciled the contradictory conclusions regarding effects of zeta potential in literature, giving important implications for membrane fouling mitigation. PMID:26641562

  3. Assessing life's effects on the interior dynamics of planet Earth using non-equilibrium thermodynamics

    NASA Astrophysics Data System (ADS)

    Dyke, J. G.; Gans, F.; Kleidon, A.

    2010-09-01

    Vernadsky described life as the geologic force, while Lovelock noted the role of life in driving the Earth's atmospheric composition to a unique state of thermodynamic disequilibrium. Here, we use these notions in conjunction with thermodynamics to quantify biotic activity as a driving force for geologic processes. Specifically, we explore the hypothesis that biologically-mediated processes operating on the surface of the Earth, such as the biotic enhancement of weathering of continental crust, affect interior processes such as mantle convection and have therefore shaped the evolution of the whole Earth system beyond its surface and atmosphere. We set up three simple models of mantle convection, oceanic crust recycling and continental crust recycling. We describe these models in terms of non-equilibrium thermodynamics in which the generation and dissipation of gradients is central to driving their dynamics and that such dynamics can be affected by their boundary conditions. We use these models to quantify the maximum power that is involved in these processes. The assumption that these processes, given a set of boundary conditions, operate at maximum levels of generation and dissipation of free energy lead to reasonable predictions of core temperature, seafloor spreading rates, and continental crust thickness. With a set of sensitivity simulations we then show how these models interact through the boundary conditions at the mantle-crust and oceanic-continental crust interfaces. These simulations hence support our hypothesis that the depletion of continental crust at the land surface can affect rates of oceanic crust recycling and mantle convection deep within the Earth's interior. We situate this hypothesis within a broader assessment of surface-interior interactions by setting up a work budget of the Earth's interior to compare the maximum power estimates that drive interior processes to the power that is associated with biotic activity. We estimate that the

  4. Thermodynamics of Biological Processes

    PubMed Central

    Garcia, Hernan G.; Kondev, Jane; Orme, Nigel; Theriot, Julie A.; Phillips, Rob

    2012-01-01

    There is a long and rich tradition of using ideas from both equilibrium thermodynamics and its microscopic partner theory of equilibrium statistical mechanics. In this chapter, we provide some background on the origins of the seemingly unreasonable effectiveness of ideas from both thermodynamics and statistical mechanics in biology. After making a description of these foundational issues, we turn to a series of case studies primarily focused on binding that are intended to illustrate the broad biological reach of equilibrium thinking in biology. These case studies include ligand-gated ion channels, thermodynamic models of transcription, and recent applications to the problem of bacterial chemotaxis. As part of the description of these case studies, we explore a number of different uses of the famed Monod–Wyman–Changeux (MWC) model as a generic tool for providing a mathematical characterization of two-state systems. These case studies should provide a template for tailoring equilibrium ideas to other problems of biological interest. PMID:21333788

  5. Soft wetting and the Shuttleworth effect, at the crossroads between thermodynamics and mechanics

    NASA Astrophysics Data System (ADS)

    Andreotti, Bruno; Snoeijer, Jacco H.

    2016-03-01

    Extremely compliant elastic materials, such as thin membranes or soft gels, can be deformed when wetted by a liquid drop. It is commonly assumed that the solid capillarity in “soft wetting” can be treated in the same manner as liquid surface tension. However, the physical chemistry of a solid interface is itself affected by any distortion with respect to the elastic reference state. This gives rise to phenomena that have no counterpart in liquids: the mechanical surface stress is different from the excess free energy in surface. Here we point out some striking consequences of this “Shuttleworth effect” in the context of wetting on deformable substrates, such as the appearance of elastic singularities and unconventional capillary forces. We provide a synthesis between different viewpoints on soft wetting (microscopic and macroscopic, mechanics and thermodynamics), and point out key open issues in the field.

  6. Inclusion of line tension effect in classical nucleation theory for heterogeneous nucleation: A rigorous thermodynamic formulation and some unique conclusions

    SciTech Connect

    Singha, Sanat K.; Das, Prasanta K. Maiti, Biswajit

    2015-03-14

    A rigorous thermodynamic formulation of the geometric model for heterogeneous nucleation including line tension effect is missing till date due to the associated mathematical hurdles. In this work, we develop a novel thermodynamic formulation based on Classical Nucleation Theory (CNT), which is supposed to illustrate a systematic and a more plausible analysis for the heterogeneous nucleation on a planar surface including the line tension effect. The appreciable range of the critical microscopic contact angle (θ{sub c}), obtained from the generalized Young’s equation and the stability analysis, is θ{sub ∞} < θ{sub c} < θ′ for positive line tension and is θ{sub M} < θ{sub c} < θ{sub ∞} for negative line tension. θ{sub ∞} is the macroscopic contact angle, θ′ is the contact angle for which the Helmholtz free energy has the minimum value for the positive line tension, and θ{sub M} is the local minima of the nondimensional line tension effect for the negative line tension. The shape factor f, which is basically the dimensionless critical free energy barrier, becomes higher for lower values of θ{sub ∞} and higher values of θ{sub c} for positive line tension. The combined effect due to the presence of the triple line and the interfacial areas (f{sup L} + f{sup S}) in shape factor is always within (0, 3.2), resulting f in the range of (0, 1.7) for positive line tension. A formerly presumed appreciable range for θ{sub c}(0 < θ{sub c} < θ{sub ∞}) is found not to be true when the effect of negative line tension is considered for CNT. Estimation based on the property values of some real fluids confirms the relevance of the present analysis.

  7. Joint interaction of ethidium bromide and methylene blue with DNA. The effect of ionic strength on binding thermodynamic parameters.

    PubMed

    Vardevanyan, Poghos O; Antonyan, Ara P; Parsadanyan, Marine A; Torosyan, Margarita A; Karapetian, Armen T

    2016-07-01

    Large amount of data of experimental and theoretical studies have shown that ethidium bromide (EtBr) and methylene blue (MB) may bind to nucleic acids via three modes: intercalation between two adjacent base pairs, insertion into the plane between neighboring bases in the same strand (semi-intercalation), and outside binding with negatively charged backbone phosphate groups. The aim of the given research is to examine the behavior of these two ligands at both separate and joint DNA binding. The obtained experimental data show that the effect of simultaneous binding of EtBr and MB on double-stranded DNA has a non-additive effect of separate binding. The analyses of the melting thermodynamic parameters of DNA complexes with two bound ligands suggest competitive mechanism of interaction. PMID:26239502

  8. Effects of Salts and Ionic Liquids on the Thermodynamics of Poly(ethylene oxide)-Containing Block Copolymers

    NASA Astrophysics Data System (ADS)

    Wanakule, Nisita; Virgili, Justin; Teran, Alexander; Balsara, Nitash

    2010-03-01

    We explore the thermodynamics of block copolymers doped with the salt, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and the ionic liquid, imidazolium bis(trifluoromethanesulfonyl) imide ([Im][TFSI]). The block copolymers comprise of polyethylene oxide (PEO), a polymer with a higher dielectric constant, and polystyrene (PS), a polymer with a lower dielectric constant. A combination of small-angle x-ray scattering (SAXS) and birefringence was used to determine morphology and order-to-disorder transition temperatures (ODT). Leibler's theory for microphase separation was employed to determine the effective Flory-Huggins interaction parameter. These values are compared to theoretically-determined values of the effective interaction parameter which were calculated with no adjustable parameters using a theory developed by Zhen-Gang Wang.

  9. The effect of variation in conformational size in pom-pom polymer on bulk and surface thermodynamics

    NASA Astrophysics Data System (ADS)

    Yang, Sewoo; Lee, Namheui; Quirk, Roderic P.; Foster, Mark D.; Hammouda, Boualem; Satija, Sushil

    2006-10-01

    We have investigated the effect on bulk and surface thermodynamics of changing the size of the linear portion between junctions of a pom-pom polymer in blends of linear and branched polystyrene (PS). A series of pom-pom PS synthesized using anionic polymerization had well-defined structures and narrow molecular weight distributions. Small Angle Neutron Scattering (SANS) measurements of bulk blend samples revealed that varying the linear portion of the pom-pom branched polymer altered the effective interaction parameter. In addition, the purely entropic contribution to the interaction parameters was estimated by extrapolating data measured in blends with linear PS-r-deuterated PS linear copolymers having different degrees of deuterium labeling Neutron Reflectometry (NR), and Surface Enhanced Raman Spectroscopy (SERS) measurements show that varying the length of the central linear portion of the pom-pom polymer also affects the surface segregation.

  10. Coherency effects on the mixing thermodynamics of cubic Ti1 -xAlxN /TiN (001) multilayers

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Abrikosov, Igor A.; Simak, Sergei I.; Odén, Magnus; Mücklich, Frank; Tasnádi, Ferenc

    2016-05-01

    In this work, we discuss the mixing thermodynamics of cubic (B1) Ti1 -xAlxN /TiN (001 ) multilayers. We show that interfacial effects suppress the mixing enthalpy compared to bulk Ti1 -xAlxN . The strongest stabilization occurs for compositions in which the mixing enthalpy of bulk Ti1 -xAlxN has its maximum. The effect is split into a strain and an interfacial (or chemical) contribution, and we show that both contributions are significant. An analysis of the local atomic structure reveals that the Ti atoms located in the interfacial layers relax significantly different from those in the other atomic layers of the multilayer. Considering the electronic structure of the studied system, we demonstrate that the lower Ti-site projected density of states at ɛF in the Ti1 -xAlxN /TiN multilayers compared to the corresponding monolithic bulk explains a decreased tendency toward decomposition.

  11. Neutron-Proton pairing effect on the thermodynamical quantities of even-even proton-rich nuclei

    NASA Astrophysics Data System (ADS)

    Belabbas, M.; Fellah, M.; Allal, N. H.; Ami, I.

    2012-02-01

    Expressions of the thermodynamical quantities, i.e. the energy E, the entropy S and the heat capacity C are established by including the isovector neutron-proton (np) pairing effect. They are deduced using temperature-dependent gap equations . E, S and C are numerically studied as a function of the temperature for some even-even proton-rich nuclei. The single-particle energies used are those of a Woods-Saxon deformed mean field. It is shown that the isovector pairing effect on E, S and C is non-negligible, not only in the 0 <= T <= Tcnp region (Tcnp being the critical temperature beyond which the np pairing vanishes), but also in the Tcnp <= T <= Tcn region (Tcn being the neutron-system critical temperature).

  12. A Hydrostatic Paradox Revisited

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2012-01-01

    This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon…

  13. Revisiting Bioaccumulation Criteria

    EPA Science Inventory

    The objective of workgroup 5 was to revisit the B(ioaccumulation) criteria that are currently being used to identify POPs under the Stockholm Convention and PBTs under CEPA, TSCA, REACh and other programs. Despite the lack of a recognized definition for a B substance, we defined ...

  14. Colloquial Hebrew Imperatives Revisited

    ERIC Educational Resources Information Center

    Bolozky, Shmuel

    2009-01-01

    In revisiting Bolozky's [Bolozky, Shmuel, 1979. "On the new imperative in colloquial Hebrew." "Hebrew Annual Review" 3, 17-24] and Bat-El's [Bat-El, Outi, 2002. "True truncation in colloquial Hebrew imperatives." "Language" 78(4), 651-683] analyses of colloquial Hebrew imperatives, the article argues for restricting Imperative Truncation to the…

  15. Swedish Successful Schools Revisited

    ERIC Educational Resources Information Center

    Hoog, Jonas; Johansson, Olof; Olofsson, Anders

    2009-01-01

    Purpose: The purpose of this paper is to describe the results of a follow-up study of two Swedish schools in which, five years previously, the principals had been successful leaders. Had this success been maintained? Design/methodology/approach: Two schools were revisited to enable the authors to interview principals and teachers as well as…

  16. Revisiting the Rhetorical Curriculum

    ERIC Educational Resources Information Center

    Rutten, Kris; Soetaert, Ronald

    2012-01-01

    The aim of the special strand on "Revisiting the rhetorical curriculum" is to explore the educational potential of a new rhetorical perspective, specifically in relation to different traditions within educational and rhetorical studies. This implies that we do not only look at education "in" rhetoric, but that we position education also "as" a…

  17. Revisiting Curriculum Potential

    ERIC Educational Resources Information Center

    Deng, Zongyi

    2011-01-01

    This article analyzes the notion of curriculum potential by revisiting the ideas of Miriam Ben-Peretz and Joseph Schwab. Invoking the German "Didaktik" tradition and by way of a curriculum-making framework, the paper argues that interpreting curriculum materials for curriculum potential requires a careful analysis and unpacking of the meanings and…

  18. Anodic Polarization Curves Revisited

    ERIC Educational Resources Information Center

    Liu, Yue; Drew, Michael G. B.; Liu, Ying; Liu, Lin

    2013-01-01

    An experiment published in this "Journal" has been revisited and it is found that the curve pattern of the anodic polarization curve for iron repeats itself successively when the potential scan is repeated. It is surprising that this observation has not been reported previously in the literature because it immediately brings into…

  19. The Linguistic Repertoire Revisited

    ERIC Educational Resources Information Center

    Busch, Brigitta

    2012-01-01

    This article argues for the relevance of poststructuralist approaches to the notion of a linguistic repertoire and introduces the notion of language portraits as a basis for empirical study of the way in which speakers conceive and represent their heteroglossic repertoires. The first part of the article revisits Gumperz's notion of a linguistic…

  20. Thermodynamics of Nitinol

    NASA Astrophysics Data System (ADS)

    McNichols, J. L., Jr.; Cory, J. S.

    1987-02-01

    A self-consistent macroscopic thermodynamics is developed for the calculation of work, heat, and dissipation for thermodynamic paths of the shape memory alloy, Nitinol. The thermodynamic system analyzed is a Nitinol helix for which extensive force-length-temperature (FLT) equation of state measurements have been made. The Nitinol system exhibits significant hysteresis and is determined to be a nonequilibrium thermostatic system. A set of equations of state are provided which correlate all reversible and irreversible Nitinol thermodynamic paths to both the set of helix (FLT) thermodynamic state variables and to new ``history'' state variables. It is shown that these equations predict observed cyclic behaviors not previously interpreted. In the absence of calorimetric measurements for the Nitinol helix system, a physical assumption is made that reversible paths are of constant phase. This assumption is used to estimate the reversible path thermal and mechanical heat capacities for the Nitinol system. With the state equations and the estimated reversible path heat capacities, the nonequilibrium thermostatic formalism is employed to derive expressions for the heat flow for any Nitinol thermodynamic path. It is shown that predicted calorimetric quantities are in good qualitative agreement with measurements. It is also shown that the calorimetric quantities are sensitive to state equation coefficients, which in turn are sensitive to cold-working or ``conditioning'' of the material. The large heat of transformation, ˜2.4 cal/g, an estimated isentropic temperature change of 22 °C and the large dimensional changes associated with the shape memory effect, imply that Nitinol may be useful for many applications, including use as a working medium for low-grade thermal-energy conversion (i.e., heat engines).

  1. Thermodynamics and thermal decomposition for shape memory effects with crystallization based on dissipation and logarithmic strain

    NASA Astrophysics Data System (ADS)

    Hall, R. B.; Rao, I. J.; Qi, H. J.

    2014-05-01

    The present effort provides a 3-D thermodynamic framework generalizing the 1-D modeling of 2-way shape memory materials described by Westbrook et al. (J. Eng. Mater. Technol. 312:041010, 2010) and Chung et al. (Macromolecules 41:184-192, 2008), while extending the strain-induced crystallization and shape memory approaches of Rao and Rajagopal (Interfaces Free Bound. 2:73-94, 2000; Int. J. Solids Struct. 38:1149-1167, 2001), Barot and Rao (Z. Angew. Math. Phys. 57:652-681, 2006), and Barot et al. (Int. J. Eng. Sci. 46:325-351, 2008) to include finite thermal expansion within a logarithmic strain basis. The free energy of newly-formed orthotropic crystallites is assumed additive, with no strains in their respective configurations of formation. A multiplicative decomposition is assumed for the assumed thermoelastic orthotropic expansional strains of the respective crystallites. The properties of the crystallites are allowed to depend both on current temperature and their respective temperatures of formation. The entropy production rate relation is written in the frame rotating with the logarithmic spin and produces stress and entropy relations incorporating the integrated configurational free energies, and a driving term for the crystallization analogous to that obtained by the previous studies of Rao et al. The salient attributes of the 1-D modeling of Westbrook et al. are recovered, and applications are discussed.

  2. Thermodynamic study of colorimetric transitions in polydiacetylene vesicles induced by the solvent effect.

    PubMed

    Pires, Ana Clarissa S; Soares, Nilda de Fátima F; da Silva, Luis Henrique M; da Silva, Maria C Hespanhol; Mageste, Aparecida B; Soares, Rêmili F; Teixeira, Álvaro V N C; Andrade, Nélio J

    2010-10-28

    We report the synthesis of 10,12-pentacosadyinoic acid (PCDA) and PCDA + cholesterol (CHO) + sphingomyelin (SPH) vesicles dispersed in water and the determination of their colorimetric response induced by small amount of organic solvents. In the absence of solvent, PCDA and PCDA/CHO/SPH vesicles showed an intense blue color. The addition of CHCl(3), CH(2)Cl(2), and CCl(4) caused a colorimetric transition (CT) in both structures with the following efficiency: CHCl(3) > CH(2)Cl(2) ≅ CCl(4). However, CH(3)OH did not cause a blue-to-red transition. By microcalorimetric technique we also determined, for the first time, the enthalpy change associated with the CT process and the energy of interaction between solvent molecules and vesicle self-assembly. We observed that the chloride solvents induced a colorimetric transition, but the thermodynamic mechanism was different for each of them. CT induced by CHCl(3) was enthalpically driven, while that caused by CH(2)Cl(2) or CCl(4) was entropically driven. PMID:20883002

  3. Thermodynamic analysis of nanoparticle size effect on kinetics in Fischer-Tropsch synthesis by lanthanum promoted iron catalyst

    NASA Astrophysics Data System (ADS)

    Nakhaei Pour, Ali; Housaindokht, Mohammad Reza; Behroozsarand, Alireza; Khodagholi, Mohammad Ali

    2014-08-01

    The kinetic parameters of the Fischer-Tropsch synthesis (FTS) on iron catalyst are analyzed by size-dependent thermodynamic method. A Langmuir-Hinshelwood kinetic equation is considered for evaluation of catalytic activity of lanthanum promoted iron catalyst. A series of unsupported iron catalysts with different particle sizes were prepared via microemulsion method. The experimental results showed that catalyst activity pass from a maximum value by increasing the iron particle size. Also, data presented that iron particle size has considerable effects on adsorption parameters and FTS rates. The ratio of surface tension ( σ) to nanoparticle radius ( r) is important in FTS reaction on iron catalyst. Finally, the results showed that by increasing of iron particle size from 18 to 45 nm the activation energies of catalysts and heats of adsorption of catalysts as two main parameters of FTS reaction increased from 89 to 114 kJ/mol and from 51 to 71 kJ/mol, respectively.

  4. Unified first law and the thermodynamics of the apparent horizon in the FRW universe

    SciTech Connect

    Cai Ronggen; Cao Liming

    2007-03-15

    In this paper we revisit the relation between the Friedmann equations and the first law of thermodynamics. We find that the unified first law first proposed by Hayward to treat the outertrapping horizon of a dynamical black hole can be used to the apparent horizon (a kind of inner trapping horizon in the context of the FRW cosmology) of the FRW universe. We discuss three kinds of gravity theorties: Einstein theory, Lovelock thoery, and scalar-tensor theory. In Einstein theory, the first law of thermodynamics is always satisfied on the apparent horizon. In Lovelock theory, treating the higher derivative terms as an effective energy-momentum tensor, we find that this method can give the same entropy formula for the apparent horizon as that of black hole horizon. This implies that the Clausius relation holds for the Lovelock theory. In scalar-tensor gravity, we find, by using the same procedure, the Clausius relation no longer holds. This indicates that the apparent horizon of the FRW universe in the scalar-tensor gravity corresponds to a system of nonequilibrium thermodynamics. We show this point by using the method developed recently by Eling et al. for dealing with the f(R) gravity.

  5. EFFECT OF HEATING RATE ON THE THERMODYNAMIC PROPERTIES OF PULVERIZED COAL

    SciTech Connect

    Ramanathan Sampath

    1999-11-02

    This semi-annual technical progress report describes work performed under DOE Grant No. DE-FG22-96PC96224 during the period March 24, 1999 to September 23, 1999 which covers the last (sixth) six months of the project. During this reporting period, extraction of devolatilization time-scales and temperature data at these time-scales analyzing the high-speed films taken during the experiments was complete. Also a new thermodynamic model was developed to predict the heat transfer behavior for coal particles subjected to a range of heating rates using one approach based on the analogy of polymers. Sensitivity analyses of this model suggest that bituminous coal particles behave like polymers during rapid heating on the order of 10{sup 4}-10{sup 7} K/s. At these heating rates during the early stages within the first few milliseconds of heating time, the vibrational part of the heat capacity of the coal molecules appears to be still frozen but during the transition from heat-up to devolatization, the heat capacity appears to attain a sudden jump in its value as in the case of polymers. There are few data available in the coal literature for 10{sup 2}-10{sup 3} K/s obtained by UTRC in their previous studies. These data were obtained for a longer heating duration on the order of several seconds as opposed to the 10 milliseconds heating time in the single particle experiments discussed above. The polymer analogy model is being modified to include longer heating time on the order of several seconds to test these data. It is expected that the model might still do a good job in the case of these larger heating time but very low heating rate experiments. Completion of the numerical analysis of the experimental data and preparation of the final report are in progress.

  6. Revisit of Alfvén ballooning modes in isotropic, ideal MHD plasmas: Effect of diamagnetic condition

    NASA Astrophysics Data System (ADS)

    Ma, John Z. G.; Hirose, Akira

    2014-04-01

    Alfvén ballooning modes provide an important mechanism to explain explosive phenomena in regions where field lines transit from dipole-like to taillike shapes. However, commonly used analytical results were unable to recover Alfvén modes in uniform plasmas and basic ballooning mode in inhomogeneous plasmas. We rigidly revisited previous work on isotropic, ideal magnetospheric plasmas and found where the problems occurred. This paper shows accurate expressions of the ballooning modes. Under the dimagnetic condition (an infinite ky), the modes have two groups depending on the relations of the three equilibrium parameters: plasma β, pressure gradient kp, and magnetic curvature kc (magnetic gradient kB is no more than a tenth of kc and thus neglected in magnetotail plasma). If the constraint is relaxed (a finite ky), the dispersion relation includes the following: (1) the fast compressional Alfvén branch; (2) two groups of ballooning instabilities: Group 1 appears when kp is independent of β, and Group 2 emerges when kc is independent of β; and (3) in Group 1, a critical β exists above which the wave mode becomes unstable, while the perpendicular wave number (k⊥) affects the instability by modulating the critical β values; by contrast, in Group 2, there is no critical β, and the wave keeps its original stable or unstable mode, while k⊥ has a critical value above which the wave mode becomes unstable.

  7. Natural thermodynamics

    NASA Astrophysics Data System (ADS)

    Annila, Arto

    2016-02-01

    The principle of increasing entropy is derived from statistical physics of open systems assuming that quanta of actions, as undividable basic build blocks, embody everything. According to this tenet, all systems evolve from one state to another either by acquiring quanta from their surroundings or by discarding quanta to the surroundings in order to attain energetic balance in least time. These natural processes result in ubiquitous scale-free patterns: skewed distributions that accumulate in a sigmoid manner and hence span log-log scales mostly as straight lines. Moreover, the equation for least-time motions reveals that evolution is by nature a non-deterministic process. Although the obtained insight in thermodynamics from the notion of quanta in motion yields nothing new, it accentuates that contemporary comprehension is impaired when modeling evolution as a computable process by imposing conservation of energy and thereby ignoring that quantum of actions are the carriers of energy from the system to its surroundings.

  8. Effects of multi-frequency power ultrasound on the enzymolysis of corn gluten meal: Kinetics and thermodynamics study.

    PubMed

    Jin, Jian; Ma, Haile; Qu, Wenjuan; Wang, Kai; Zhou, Cunshan; He, Ronghai; Luo, Lin; Owusu, John

    2015-11-01

    The effects of multi-frequency power ultrasound (MPU) pretreatment on the kinetics and thermodynamics of corn gluten meal (CGM) were investigated in this research. The apparent constant (KM), apparent break-down rate constant (kA), reaction rate constants (k), energy of activation (Ea), enthalpy of activation (ΔH), entropy of activation (ΔS) and Gibbs free energy of activation (ΔG) were determined by means of the Michaelis-Menten equation, first-order kinetics model, Arrhenius equation and transition state theory, respectively. The results showed that MPU pretreatment can accelerate the enzymolysis of CGM under different enzymolysis conditions, viz. substrate concentration, enzyme concentration, pH, and temperature. Kinetics analysis revealed that MPU pretreatment decreased the KM value by 26.1% and increased the kA value by 7.3%, indicating ultrasound pretreatment increased the affinity between enzyme and substrate. In addition, the values of k for ultrasound pretreatment were increased by 84.8%, 41.9%, 28.9%, and 18.8% at the temperature of 293, 303, 313 and 323 K, respectively. For the thermodynamic parameters, ultrasound decreased Ea, ΔH and ΔS by 23.0%, 24.3% and 25.3%, respectively, but ultrasound had little change in ΔG value in the temperature range of 293-323 K. In conclusion, MPU pretreatment could remarkably enhance the enzymolysis of CGM, and this method can be applied to protein proteolysis industry to produce peptides. PMID:26186819

  9. The influence of the permanent dipole and quadrupole moments in water on the thermodynamic characteristics of the hydrophobic effect

    NASA Astrophysics Data System (ADS)

    Goldman, Saul

    1981-10-01

    A thermodynamic perturbation theory that derives from the work of Gray, Gubbins, and Stell is used to analyze the influence of the permanent dipole and quadrupole moments in water on a variety of thermodynamic functions that characterize hydrophobic solvation and hydrophobic interactions. The model used for water was a generalized Stockmayer potential. Experimental values were used for the dipole moment and for the three components of the quadrupole tensor of water, and the parameters for the Lennard-Jones part of this potential were taken from Finney et al.'s polarizable electropole model for water. This potential function involves reduced dipole and quadrupole moments that are shown to be within the range of validity of Stell's Padé approximant. Induced moments were not considered. The solute-solute and solute-solvent pair potential functions were taken to be the same as the Lennard-Jones part of the solvent-solvent pair potential function. The effects of three types of anisotropies, namely, dipole forces only, generalized quadrupole forces only, dipole-dipole plus generalized quadrupole-generalized quadrupole plus dipole-generalized quadrupole forces, are considered separately. Values obtained for the Henry's law constant, the heat of solution, the partial molal volume, and the partial molal heat capacity, at infinite dilution, are compared with ranges of experimental values for these quantities for the rare gases in water. The closeness of our results to those data, for our solvent with all the anisotropies simultaneously turned on, is, with the exception of the partial molal volume, remarkable good. The reason for this one failure is discussed. Most surprising perhaps was the result, again for the solvent with the most complicated anisotropy, that it was possible, over a restricted temperature range, to mimic the drop in the osmotic second virial coefficient that is found in real aqueous systems at ordinary temperatures. A physical explanation for this

  10. Kinetic and thermodynamic analysis of the inhibitory effects of maltose, glucose, and related carbohydrates on wheat β-amylase.

    PubMed

    Daba, Tadessa; Kojima, Kenji; Inouye, Kuniyo

    2013-04-10

    Inhibition of wheat β-amylase (WBA) by glucose and maltose was studied by kinetics and thermodynamics. The inhibitory effects of fructose, difructose, sucrose, trehalose, cellobiose, acarbose, and 1-deoxynojirimycin on WBA were also evaluated. The half maximal inhibitory concentrations (IC50) of acarbose, maltose and glucose were 0.06±0.01M, 0.22±0.09M, and 1.41±0.17M, respectively. The inhibitor constant (Ki) and the thermodynamic parameters such as changes in Gibbs energy (ΔG), enthalpy (ΔH), and entropy (ΔS) of the dissociation reactions of the WBA-glucose and WBA-maltose complexes were temperature and pH-dependent. The dissociation reactions were endothermic and enthalpy-driven. Both glucose and maltose behaved as competitive inhibitors at pH 3.0 and 5.4 at a temperature of 25°C with respective Ki values of 0.33±0.02M and 0.12±0.03M. In contrast, both sugars exhibited uncompetitive inhibition at pH 9 at a temperature of 25°C with Ki values of 0.21±0.03M for glucose and 0.11±0.04M for maltose. The pH-dependence of the inhibition type and Ki values indicate that the ionizing groups of WBA influence drastically the interaction with these carbohydrates. This evidence enables us to consider temperature and pH in the WBA-catalyzed hydrolysis to manipulate the inhibition by end-product, maltose, and even by glucose. PMID:23540927

  11. Advances in thermodynamics

    SciTech Connect

    Sieniutycz, S. ); Salamon, P. )

    1990-01-01

    This book covers: nonequilibrium thermodynamics for solar energy applications; finite-time thermodynamics as applied to solar power conversion; thermodynamics and economics; exergy analysis; and an analysis of cumulative exergy consumption and exergy losses.

  12. Thermodynamic studies on the solvent effects in chromatography on molecularly imprinted polymers

    SciTech Connect

    Kim, Hyunjung; Guiochon, Georges A

    2005-03-01

    Molecularly imprinted polymers (MIPs) are used as highly enantioselective stationary phases in liquid chromatography. To optimize the binding performance of MIPs, different types of polar modifiers are frequently used. Previous studies have shown that the hydrogen-bonding donor parameter (HBD) of the modifier has a large influence on the binding performance of MIPs in chiral separations. This possibility is addressed in a detailed thermodynamic study of a Fmoc-l-tryptophan (Fmoc-l-Trp) imprinted polymer, eluted with four different polar modifiers, i.e., THF, propan-2-ol, methanol, and acetic acid, which have different HBDs (0.00, 0.33, 0.43, and 0.61, respectively). Adsorption isotherm data for each enantiomer in each of these organic modifiers were acquired by frontal analysis over a 20000 dynamic concentration range. Nonlinear regression of the isotherm data, along with independent calculation of the affinity energy distributions, identified four different types of binding sites coexisting for the enantiomers on the MIP. The exception was acetic acid, which has the highest HBD. In this case, three types of binding sites only coexist on the MIP. The isotherm parameters obtained from these data show the following: (1) The association energies of the two enantiomers with a given type of sites have a similar magnitude; however, the density of the sites is higher for the template than for its antipode. (2) The nature of the organic modifier has a larger influence on the density of high-energy sites than on the association constant of these sites. (3) The molecular size of the organic modifier has a larger influence on the site density (especially for Fmoc-d-Trp) than does HBD. (4) Using an organic modifier with a higher HBD reduces the enantioselectivity on each site. (5) High-energy sites are more enantioselective than low-energy ones. (6) Using an organic modifier with a high HBD causes a larger reduction in the density of high-energy sites approached by the

  13. The effects of organic solvents on the folding pathway and associated thermodynamics of proteins: a microscopic view.

    PubMed

    Yu, Yuqi; Wang, Jinan; Shao, Qiang; Shi, Jiye; Zhu, Weiliang

    2016-01-01

    Protein folding is subject to the effects of solvation environment. A variety of organic solvents are used as additives for in vitro refolding of denatured proteins. Examination of the solvent effects on protein folding could be of fundamental importance to understand the molecular interactions in determining protein structure. This article investigated the folding of α-helix and β-hairpin structures in water and the solutions of two representative refolding additives (methanol (MeOH) and 1-Ethyl-3-methylimidazolium chloride (EMIM-Cl) ionic liquid) using REMD simulations. For both α-helix and β-hairpin in MeOH/water solution or α-helix in EMIM-Cl/water solution, the transient structures along the folding pathway are consistent with the counterparts in water but the relative statistical weights are changed, leading to the decrease in the overall folding free energy barrier. Accordingly, MeOH promotes the folding of both α-helix and β-hairpin but EMIM-Cl ionic liquid only promotes the folding of α-helix, consistent with experimental observations. The present study reveals for the first time the trivial effects on folding route but significant effects on folding thermodynamics from MeOH and EMIM-Cl, explaining the function of protein refolding additives and testifying the validity of the folding mechanism revealed by in vitro protein folding study using refolding additives. PMID:26775871

  14. The effects of organic solvents on the folding pathway and associated thermodynamics of proteins: a microscopic view

    PubMed Central

    Yu, Yuqi; Wang, Jinan; Shao, Qiang; Shi, Jiye; Zhu, Weiliang

    2016-01-01

    Protein folding is subject to the effects of solvation environment. A variety of organic solvents are used as additives for in vitro refolding of denatured proteins. Examination of the solvent effects on protein folding could be of fundamental importance to understand the molecular interactions in determining protein structure. This article investigated the folding of α-helix and β-hairpin structures in water and the solutions of two representative refolding additives (methanol (MeOH) and 1-Ethyl-3-methylimidazolium chloride (EMIM-Cl) ionic liquid) using REMD simulations. For both α-helix and β-hairpin in MeOH/water solution or α-helix in EMIM-Cl/water solution, the transient structures along the folding pathway are consistent with the counterparts in water but the relative statistical weights are changed, leading to the decrease in the overall folding free energy barrier. Accordingly, MeOH promotes the folding of both α-helix and β-hairpin but EMIM-Cl ionic liquid only promotes the folding of α-helix, consistent with experimental observations. The present study reveals for the first time the trivial effects on folding route but significant effects on folding thermodynamics from MeOH and EMIM-Cl, explaining the function of protein refolding additives and testifying the validity of the folding mechanism revealed by in vitro protein folding study using refolding additives. PMID:26775871

  15. Simultaneous determination of structural and thermodynamic effects of carbohydrate solutes on the thermal stability of ribonuclease A.

    PubMed

    O'Connor, Thomas F; Debenedetti, Pablo G; Carbeck, Jeffrey D

    2004-09-29

    This communication describes a new technique for the study of the effects of carbohydrates on the thermal stability of proteins. This approach combines capillary electrophoresis (CE) and protein charge ladders, collections of proteins that differ incrementally in number of chemically modified charged groups, to provide information on both the thermodynamics (i.e., the free energy, DeltaGN-D, of denaturation), and structural changes (i.e., the effective hydrodynamic radius, RH, of proteins in both the native and denatured states) associated with stability. This information, obtained in a single set of electrophoresis experiments, allows a simple microscopic interpretation of the effects of carbohydrate solutes on protein stability. We use this technique to show that the stabilization of ribonuclease A at pH 8.4 by sucrose and fructose can be explained entirely by the contribution these solutes make to the entropy of formation of the protein-solution interface. There is no need, in this case, to refer to quasichemical concepts such as preferential hydration, binding, or exchange of solutes with water at specific sites on the protein to account for the stabilizing effects observed. PMID:15382905

  16. Time functions revisited

    NASA Astrophysics Data System (ADS)

    Fathi, Albert

    2015-07-01

    In this paper we revisit our joint work with Antonio Siconolfi on time functions. We will give a brief introduction to the subject. We will then show how to construct a Lipschitz time function in a simplified setting. We will end with a new result showing that the Aubry set is not an artifact of our proof of existence of time functions for stably causal manifolds.

  17. Revisiting Dialogues and Monologues

    ERIC Educational Resources Information Center

    Kvernbekk, Tone

    2012-01-01

    In educational discourse dialogue tends to be viewed as being (morally) superior to monologue. When we look at them as basic forms of communication, we find that dialogue is a two-way, one-to-one form and monologue is a one-way, one-to-many form. In this paper I revisit the alleged (moral) superiority of dialogue. First, I problematize certain…

  18. Thermodynamic investigation of the effect of alkali metal impuries on the processing of aluminum and magnesium alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Shengjun

    2006-12-01

    Aluminum and magnesium alloys are widely used in the automobile and aerospace industries as structural materials due to their light weight, high specific strength and good formability. However, they suffer from the poor hot rolling characteristics due to undesired impurities like calcium, potassium, lithium and sodium. They increase the hydrogen solubility in the melt and promote the formation of porosity in aluminum castings. During fabrication of aluminum alloys, they cause the hot-shortness and embrittlement due to cracking. They also led to "blue haze" corrosion which promotes the discoloration of aluminum under humid condition. The removal of these elements increases overall melt loss of aluminum alloys when aluminum products are remelted and recast. Na is one of the common impurities in the Al and Mg alloys. In industry, primary Al is produced by the Hall-Heroult process, through the electrolysis of the mixture of molten alumina and cryolite (Al2O3+Na 3AlF6), the latter being added to lower the melting point. Therefore, Al inevitably contains some Na (>0.002%) without further treatment. The Na content in Al is influenced by the thermodynamics and kinetics of the electrolysis. Similarly, in the electrolytic production and subsequent processing of Mg, Mg is commonly in contact with molten salt mixtures of NaCl and MgCl 2. Consequently, 2--20 wt. ppm Na is often found in Mg alloys. Besides originating from the industrial production process, Na can be introduced in laboratory experiments from alumina crucibles by the reaction between the molten Al-Mg alloys and the Na2O impurity in the alumina crucible. The trace element K plays a similar role in Al alloys although it is seldom discussed. No systematic theoretic research has been carried out to investigate the behavior of these impurities during the processing of aluminum alloys. The thermodynamic description of the Al-Ca-K-Li-Mg-Na system is needed to understand the effects of Ca, K, Li and Na on phase stability

  19. Neurobehavioral effects of exposure to propionic acid revisited-Does psychosocial stress interfere with distractive effects in volunteers?

    PubMed

    Pacharra, Marlene; Schäper, Michael; Kleinbeck, Stefan; Blaszkewicz, Meinolf; Golka, Klaus; van Thriel, Christoph

    2016-07-01

    Local irritants stimulate the nervous system via chemosensory pathways that trigger cognitive distraction, subjective complaints about impaired health, and physiological defense reflexes (e.g. eye-blinks). At workplaces and in the environment chemical exposures often co-occur with psychosocial stress. This study investigated if stress modulates adverse effects of exposure to the local irritant and malodorant propionic acid (PA). Forty-eight participants were randomly assigned to an experimental (false negative feedback+salient surveillance) or control group. In a cross-over design, both groups were exposed for 4h to PA in concentrations of 0.3 and 0-20ppm (time-weighted average=10ppm). In the experimental group, the stress protocol induced moderate psychosocial stress as indicated by salivary cortisol and subjective responses. Despite concentration-dependent increases in chemosensory perceptions and symptoms, the level of exposure to PA had no impact upon the results of four out of six neurobehavioral tests. In the sustained attention test, there was a significant increase in error rates that corresponded to the exposure levels. However, a concentration-dependent impairment of spatial working memory and an adverse increase in eye-blink frequency were restricted to the control group. Stressed participants had shorter simple reaction times and high eye-blink frequency irrespective of exposure suggesting enhanced alertness. Psychosocial stress increased complaints, ocular irritation and unspecific symptoms at the end of the 0.3ppm exposure to a level that was comparable with that in the control group during exposure to 0-20ppm. Results indicate that the adverse effects of a local irritant and psychosocial stress are non-additive. PMID:27246649

  20. Effect of the air hammer on the hands of stonecutters. The limestone quarries of Bedford, Indiana, revisited.

    PubMed

    Taylor, W; Wasserman, D; Behrens, V; Reynolds, D; Samueloff, S

    1984-08-01

    In the limestone quarries of Indiana, USA, pneumatic percussive hammers replaced the mallet and hammer around 1900. By 1917 the air hammer was being used exclusively for periods of eight to ten hours a shift. In 1918 Alice Hamilton investigated an unusual "disease" in these stonecutters of Bedford, Indiana, who complained of "attacks of numbness and blanching of the fingers coming on suddenly under the influence of cold and then disappearing." The prevalence of vibration induced white finger (VWF) found in this population of 38 stonecutters was 89%, with decreased light touch, pain, and temperature appreciation in advanced cases. In 1978 a VWF research team revisited these limestone quarries. During the 60 year interval the stonecutting industry had contracted from 4000 workers in 40 quarries in 1918 to 3-400 in 10 quarries in 1978, with only 50 employees remaining in the Bedford area. In a population of 30 stonecutters the prevalence of VWF in 1978 was 80%, with similar sensory loss in light touch, pain, and temperature appreciation. Between 1918 and 1978 no change had taken place in the design of the air hammers used for stonecutting. Vibration levels of 4859 metres/s2 on the chisel, and 2010 metres/s2 on the barrel were measured over a frequency range 6.3 to 1000 Hz. The fundamental frequency was 75 Hz. These measured vibration levels are outside the ISO/DIS/5349 (1979) recommended limits for human exposure to vibration transmitted to the hand. The VWF data presented in this paper, and those originally reported by Hamilton in 1918, call for an immediate redesign of stonecutting pneumatic hammers in order to remove one cause of Raynaud's phenomenon of occupational origin. PMID:6378250

  1. Dynamic Topography Revisited

    NASA Astrophysics Data System (ADS)

    Moresi, Louis

    2015-04-01

    Dynamic Topography Revisited Dynamic topography is usually considered to be one of the trinity of contributing causes to the Earth's non-hydrostatic topography along with the long-term elastic strength of the lithosphere and isostatic responses to density anomalies within the lithosphere. Dynamic topography, thought of this way, is what is left over when other sources of support have been eliminated. An alternate and explicit definition of dynamic topography is that deflection of the surface which is attributable to creeping viscous flow. The problem with the first definition of dynamic topography is 1) that the lithosphere is almost certainly a visco-elastic / brittle layer with no absolute boundary between flowing and static regions, and 2) the lithosphere is, a thermal / compositional boundary layer in which some buoyancy is attributable to immutable, intrinsic density variations and some is due to thermal anomalies which are coupled to the flow. In each case, it is difficult to draw a sharp line between each contribution to the overall topography. The second definition of dynamic topography does seem cleaner / more precise but it suffers from the problem that it is not measurable in practice. On the other hand, this approach has resulted in a rich literature concerning the analysis of large scale geoid and topography and the relation to buoyancy and mechanical properties of the Earth [e.g. refs 1,2,3] In convection models with viscous, elastic, brittle rheology and compositional buoyancy, however, it is possible to examine how the surface topography (and geoid) are supported and how different ways of interpreting the "observable" fields introduce different biases. This is what we will do. References (a.k.a. homework) [1] Hager, B. H., R. W. Clayton, M. A. Richards, R. P. Comer, and A. M. Dziewonski (1985), Lower mantle heterogeneity, dynamic topography and the geoid, Nature, 313(6003), 541-545, doi:10.1038/313541a0. [2] Parsons, B., and S. Daly (1983), The

  2. Thermodynamic interpolation

    SciTech Connect

    Maiden, D E

    1998-10-01

    A method for constructing bicubic interpolation polynomials for the pressure P and internal energy E that are thermodynamically consistent at the mesh ponts and continuous across mesh boundaries is presented. The slope boundary conditions for the pressure and energy are derived from finite differences of the data and from Maxwell's consistency relation. Monotonicity of the sound speed and the specific heat is obtained by a bilinear interpolation of the slopes of the tabulated data. Monotonicity of the functions near steep gradients may be achieved by mesh refinement or by using a non-consistent bilinear to the data. Mesh refinement is very efficient for uniform-linear or uniform-logarithmic spaced data because a direct table lookup can be used. The direct method was compared to binary search and was 37 percent faster for logarithmic-spaced data and 106 percent faster for linear-spaced data. This improvement in speed is very important in the radiation-transport opacity-lookup part of the calculation. Interpolation in P-E space, with mesh refinement, can be made simple, robust, and conserve energy. In the final analysis the interpolation of the free energy and entropy (Maiden and Cook) remains a competitor.

  3. The Effect of Temperature on the Enzyme-Catalyzed Reaction: Insights from Thermodynamics

    ERIC Educational Resources Information Center

    Aledo, Juan Carlos; Jimenez-Riveres, Susana; Tena, Manuel

    2010-01-01

    When teaching the effect of temperature on biochemical reactions, the problem is usually oversimplified by confining the thermal effect to the catalytic constant, which is identified with the rate constant of the elementary limiting step. Therefore, only positive values for activation energies and values greater than 1 for temperature coefficients…

  4. Effect of Backbone Design on Hybridization Thermodynamics of Oligo-nucleic Acids: A Coarse-Grained Molecular Dynamics Simulation Study

    NASA Astrophysics Data System (ADS)

    Ghobadi, Ahmadreza F.; Jayaraman, Arthi

    DNA hybridization is the basis of various bio-nano technologies, such as DNA origami and assembly of DNA-functionalized nanoparticles. A hybridized double stranded (ds) DNA is formed when complementary nucleobases on hybridizing strands exhibit specific and directional hydrogen bonds through canonical Watson-Crick base-pairing interactions. In recent years, the need for cheaper alternatives and significant synthetic advances have driven design of DNA mimics with new backbone chemistries. However, a fundamental understanding of how these backbone modifications in the oligo-nucleic acids impact the hybridization and melting behavior of the duplex is still lacking. In this talk, we present our recent findings on impact of varying backbone chemistry on hybridization of oligo-nucleic acid duplexes. We use coarse-grained molecular dynamics simulations to isolate the effect of strand flexibility, electrostatic interactions and nucleobase spacing on the melting curves for duplexes with various strand sequences and concentrations. Since conjugation of oligo-nucleic acids with polymers serve as building blocks for thermo-responsive polymer networks and gels, we also present the effect of such conjugation on hybridization thermodynamics and polymer conformation.

  5. NON-LOCAL THERMODYNAMICAL EQUILIBRIUM EFFECTS ON THE IRON ABUNDANCE OF ASYMPTOTIC GIANT BRANCH STARS IN 47 TUCANAE

    SciTech Connect

    Lapenna, E.; Mucciarelli, A.; Lanzoni, B.; Ferraro, F. R.; Dalessandro, E.; Massari, D.

    2014-12-20

    We present the iron abundance of 24 asymptotic giant branch (AGB) stars, members of the globular cluster 47 Tucanae, obtained with high-resolution spectra collected with the FEROS spectrograph at the MPG/ESO 2.2 m Telescope. We find that the iron abundances derived from neutral lines (with a mean value [Fe I/H] =–0.94 ± 0.01, σ = 0.08 dex) are systematically lower than those derived from single ionized lines ([Fe II/H] =–0.83 ± 0.01, σ = 0.05 dex). Only the latter are in agreement with those obtained for a sample of red giant branch (RGB) cluster stars, for which the Fe I and Fe II lines provide the same iron abundance. This finding suggests that non-local thermodynamical equilibrium (NLTE) effects driven by overionization mechanisms are present in the atmosphere of AGB stars and significantly affect the Fe I lines while leaving Fe II features unaltered. On the other hand, the very good ionization equilibrium found for RGB stars indicates that these NLTE effects may depend on the evolutionary stage. We discuss the impact of this finding on both the chemical analysis of AGB stars and on the search for evolved blue stragglers.

  6. Numerical investigation and thermodynamic analysis of the effect of electrolyte flow rate on performance of all vanadium redox flow batteries

    NASA Astrophysics Data System (ADS)

    Khazaeli, Ali; Vatani, Ali; Tahouni, Nassim; Panjeshahi, Mohammad Hassan

    2015-10-01

    In flow batteries, electrolyte flow rate plays a crucial role on the minimizing mass transfer polarization which is at the compensation of higher pressure drop. In this work, a two-dimensional numerical method is applied to investigate the effect of electrolyte flow rate on cell voltage, maximum depth of discharge and pressure drop a six-cell stack of VRFB. The results show that during the discharge process, increasing electrolyte flow rate can raise the voltage of each cell up to 50 mV on average. Moreover, the maximum depth of discharge dramatically increases with electrolyte flow rate. On the other hand, the pressure drop also positively correlates with electrolyte flow rate. In order to investigate all these effects simultaneously, average energy and exergy efficiencies are introduced in this study for the transient process of VRFB. These efficiencies give insight into choosing an appropriate strategy for the electrolyte flow rate. Finally, the energy efficiency of electricity storage using VRFB is investigated and compared with other energy storage systems. The results illustrate that this kind of battery has at least 61% storage efficiency based on the second law of thermodynamics, which is considerably higher than that of their counterparts.

  7. The effect of quaternary element on the thermodynamic parameters and structure of CuAlMn shape memory alloys

    NASA Astrophysics Data System (ADS)

    Aksu Canbay, C.; Karagoz, Z.

    2013-10-01

    In this study, the Cu-based shape memory alloys were produced by arc melting. We have investigated the effects of the alloying elements on the characteristic transformation temperatures, enthalpy, entropy values, and the structure of Cu-Al-Mn ternary system. The evolution of the transformation temperatures was studied by the differential scanning calorimetry. The characteristic transformation temperatures can be controlled by the variations in the aluminum and manganese content. Additionally, the effect of magnesium and iron on the transformation temperatures and thermodynamic parameters was investigated in the Cu-Al-Mn ternary system. The addition of the magnesium decreases the characteristic transformation temperatures of the Cu-Al-Mn system, but that of the iron increases. The structural changes of the samples were studied by X-ray diffraction measurements and optical microscope observations. Due to the low solubility of the magnesium, the magnesium addition into the Cu-Al-Mn system forms precipitates in the matrix. It is evaluated that the transformation parameters of the CuAlMn shape memory alloys can be controlled by the change of the alloying elements and the weight percentages of alloying elements.

  8. Revisiting Twomey's approximation for peak supersaturation

    NASA Astrophysics Data System (ADS)

    Shipway, B. J.

    2015-04-01

    Twomey's seminal 1959 paper provided lower and upper bound approximations to the estimation of peak supersaturation within an updraft and thus provides the first closed expression for the number of nucleated cloud droplets. The form of this approximation is simple, but provides a surprisingly good estimate and has subsequently been employed in more sophisticated treatments of nucleation parametrization. In the current paper, we revisit the lower bound approximation of Twomey and make a small adjustment that can be used to obtain a more accurate calculation of peak supersaturation under all potential aerosol loadings and thermodynamic conditions. In order to make full use of this improved approximation, the underlying integro-differential equation for supersaturation evolution and the condition for calculating peak supersaturation are examined. A simple rearrangement of the algebra allows for an expression to be written down that can then be solved with a single lookup table with only one independent variable for an underlying lognormal aerosol population. While multimodal aerosol with N different dispersion characteristics requires 2N+1 inputs to calculate the activation fraction, only N of these one-dimensional lookup tables are needed. No additional information is required in the lookup table to deal with additional chemical, physical or thermodynamic properties. The resulting implementation provides a relatively simple, yet computationally cheap, physically based parametrization of droplet nucleation for use in climate and Numerical Weather Prediction models.

  9. Dynamically tunable transformation thermodynamics

    NASA Astrophysics Data System (ADS)

    García-Meca, Carlos; Barceló, Carlos

    2016-04-01

    Recently, the introduction of transformation thermodynamics has provided a way to design thermal media that alter the flow of heat according to any spatial deformation, enabling the construction of novel devices such as thermal cloaks or concentrators. However, in its current version, this technique only allows static deformations of space. Here, we develop a space–time theory of transformation thermodynamics that incorporates the possibility of performing time-varying deformations. This extra freedom greatly widens the range of achievable effects, providing an additional degree of control for heat management applications. As an example, we design a reconfigurable thermal cloak that can be opened and closed dynamically, therefore being able to gradually adjust the temperature distribution of a given region.

  10. Thermodynamics of Radiation Modes

    ERIC Educational Resources Information Center

    Pina, Eduardo; de la Selva, Sara Maria Teresa

    2010-01-01

    We study the equilibrium thermodynamics of the electromagnetic radiation in a cavity of a given volume and temperature. We found three levels of description, the thermodynamics of one mode, the thermodynamics of the distribution of frequencies in a band by summing over the frequencies in it and the global thermodynamics by summing over all the…

  11. Thermodynamic modelling of a double-effect LiBr-H2O absorption refrigeration cycle

    NASA Astrophysics Data System (ADS)

    Iranmanesh, A.; Mehrabian, M. A.

    2012-12-01

    The goal of this paper is to estimate the conductance of components required to achieve the approach temperatures, and gain insights into a double-effect absorption chiller using LiBr-H2O solution as the working fluid. An in-house computer program is developed to simulate the cycle. Conductance of all components is evaluated based on the approach temperatures assumed as input parameters. The effect of input data on the cycle performance and the exergetic efficiency are investigated.

  12. Effects of Storms on Coastal Vulnerability Through Revisiting Sites Impacted by Super Storm Sandy Offshore Long Island, New York

    NASA Astrophysics Data System (ADS)

    Hosseini, P.; McHugh, C.; Christensen, B. A.; Yong, W. Y.; Delligatti, M.

    2015-12-01

    Recent models indicate that due to climate change storm activity can intensify. Sea level rise as a result of climate change can lead to storm flooding and coastal damage in low-lying populated areas such as NE, USA. The New York metropolitan area experienced one of the highest storm surges in its history during Hurricane Sandy. The peak storm-tide elevation measured by USGS in Jamaica Bay was about 3.5 m, 1.4 m higher than historical measurements in the same area. As part of a National Science Foundation Rapid Response we surveyed from the R/V Pritchard and sampled the bays and inlets along the southern shore of Long Island after Super Storm Sandy in January 2013 and during June 2014 for assessing the impact of the storm. Short-lived radioisotopes, heavy metals and grain size variability were used to track the path of the storm. In 2013 high concentrations of metals (Pb 184 ppm) were deposited on the landward side of barrier islands and were tracked offshore for10 km. In 2014, we revisited the 2013 locations. The offshore, metal enriched mud layer was seen as small inclusions in sand and not present at the surface suggestive that natural processes are cleansing the sea-floor. Inland the cores showed three facies. From the base upwards: 1) coarse sand with low Pb 99 ppm. Interpreted as either sand transported landwards by the storm or in situ; 2) fine-grained, organic rich sediment with the high Pb 443 ppm and interpreted as seaward transport by the storm; 3) organic rich mud with lower Pb 200 ppm was found in the core tops. Most importantly the sea-floor was colonized by tubeworms suggestive that the environment is returning to normal conditions. These results coupled to other regional studies indicate that the storm was catastrophic and resulted in significant sediment transport. The surge brought sand inland modifying channel and inlet depths but most damaging was the seaward surge that brought contaminants offshore. It appears that the bays and inlets are

  13. The effect of native point defect thermodynamics on off-stoichiometry in beta-Mg17Al12

    SciTech Connect

    Wolverton, Christopher

    2012-01-01

    The mechanical strength of Mg-Al-Zn alloys can be affected by a fine spatial dispersion of {beta}-Mg{sub 17}Al{sub 12} precipitates in the Mg matrix. In an effort to understand the phase stability and the unusual asymmetric off-stoichiometry observed in {beta}-Mg{sub 17}Al{sub 12}, we have performed a series of first-principles density functional theory (DFT) calculations of bulk and defect properties of Mg{sub 17}Al{sub 12}. Specifically, we consider native point defects (i.e. vacancies and anti-sites) in all four sublattices of Mg{sub 17}Al{sub 12}, i.e. 2a, 8c, 24g (Mg) and 24g (Al). The T = 0 K static energies of defect Mg{sub 17}Al{sub 12} supercells indicate that anti-site defects are energetically favored over vacancies, and the lowest anti-site defect formation energies are in 24g sites for both Al{sub Mg} and Mg{sub Al}. These Al-rich and Mg-rich anti-site defect formation energies are similar in magnitude, and thus do not explain the asymmetric off-stoichiometry of Mg{sub 17}Al{sub 12}. We also investigate the effect of atomic vibrations via DFT phonon calculations on native point defect free energies of Mg{sub 17}Al{sub 12} and combine these entropic contributions with the point defect formation energies to evaluate the thermodynamics of off-stoichiometry in this phase. We find that the formation of the Al{sub Mg} anti-site is not strongly stabilized by vibrational entropy. Thus, we conclude that the observed asymmetry in the off-stoichiometry of the {beta}-Mg{sub 17}Al{sub 12} phase in the Mg-Al phase diagram is not explained by simple native point defect thermodynamics, and must involve a more complicated defect formation mechanism, such as multi-defect clustering.

  14. The effects of thermodynamic data on the design and operation of distillation columns

    SciTech Connect

    Zeck, S. )

    1993-04-01

    The relative importance of various physical properties for distillation-column design and operation is classified. Vapor-liquid equilibrium data have a dominant effect. It is possible to quantify the effect of errors of relative volatility on the uncertainty of the number of stages required for a given simple binary separation problem by using the simplest, so-termed short-cut methods of column design, because the results obtained are, practically, the same as those found by more sophisticated methods. The same error in the relative volatility [alpha] leads to a sharply increasing uncertainty in the number of stages required as the value of [alpha] approaches unity.

  15. Simplified thermodynamic functions for vapor-liquid phase separation and fountain effect pumps

    NASA Technical Reports Server (NTRS)

    Yuan, S. W. K.; Hepler, W. A.; Frederking, T. H. K.

    1984-01-01

    He-4 fluid handling devices near 2 K require novel components for non-Newtonian fluid transport in He II. Related sizing of devices has to be based on appropriate thermophysical property functions. The present paper presents simplified equilibrium state functions for porous media components which serve as vapor-liquid phase separators and fountain effect pumps.

  16. Photovoltaic canopies: thermodynamics to achieve a sustainable systems approach to mitigate the urban heat island hysteresis lag effect

    NASA Astrophysics Data System (ADS)

    Golden, Jay S.

    2006-03-01

    At a time of greater attention to global climate change and increased costs of energy, our planet is rapidly urbanizing and transitioning regions from the natural rural vegetation to man-made urban engineered infrastructure. The anthropogenic-induced change has manifested itself in micro-scale and meso-scale increase in temperatures in comparison to adjacent rural regions which is known as the urban heat island effect ? Tu- r; (Oke 1987, Brazel 2003) and results in the increased need of electricity for mechanical cooling as well as various adverse environmental, social, and economic consequences for local and global communities (Golden 2004). Prior research has documented that between 29% and 45% of the urban fabric comprised paved surfaces to support mobility (Akbari et al. 1999). The increase in paved surfaces as a function of thermodynamics alters the urban energy budget due to changes in albedo, thermal mass as well as conduction, convection, and evapotranspiration. An emerging engineering option to reduce the significant role that surface pavements play in adding to the urban heat island is to capitalize on the capturing and shading of incident solar energy by means of utilization of photovoltaic panels to provide covered parking for this large portion of the urban fabric.

  17. Nylon 6 electrospun nanofibers mat as effective sorbent for the removal of estrogens: kinetic and thermodynamic studies.

    PubMed

    Qi, Fei-Fei; Cao, Yang; Wang, Min; Rong, Fei; Xu, Qian

    2014-01-01

    Nylon 6 electrospun nanofibers mat was prepared via electrospinning for the removal of three estrogens, namely, diethylstilbestrol (DES), dienestrol (DS), and hexestrol (HEX) from aqueous solution. Static adsorption as well as the dynamic adsorption was evaluated by means of batch and dynamic disk flow mode, respectively. The kinetic study indicated that the adsorption of the target compounds could be well fitted by the pseudo-second-order equation, suggesting the intra-particle/membrane diffusion process as the rate-limiting step of the adsorption process. The adsorption equilibrium data were all fitted well to the Freundlich isotherm models, with a maximum adsorption capacity values in the range of 97.71 to 208.95 mg/g, which can be compared to or moderately higher than other sorbents published in the literatures. The dynamic disk mode studies indicated that the mean removal yields of three model estrogens were over 95% with a notable smaller amount of adsorbent (4 mg). Thermodynamic study revealed that the adsorption process was exothermic and spontaneous in nature. Desorption results showed that the adsorption capacity can remain up to 80% after seven times usage. It was suggested that Nylon 6 electrospun nanofibers mat has great potential as a novel effective sorbent material for estrogens removal. PMID:25114645

  18. Nylon 6 electrospun nanofibers mat as effective sorbent for the removal of estrogens: kinetic and thermodynamic studies

    NASA Astrophysics Data System (ADS)

    Qi, Fei-Fei; Cao, Yang; Wang, Min; Rong, Fei; Xu, Qian

    2014-07-01

    Nylon 6 electrospun nanofibers mat was prepared via electrospinning for the removal of three estrogens, namely, diethylstilbestrol (DES), dienestrol (DS), and hexestrol (HEX) from aqueous solution. Static adsorption as well as the dynamic adsorption was evaluated by means of batch and dynamic disk flow mode, respectively. The kinetic study indicated that the adsorption of the target compounds could be well fitted by the pseudo-second-order equation, suggesting the intra-particle/membrane diffusion process as the rate-limiting step of the adsorption process. The adsorption equilibrium data were all fitted well to the Freundlich isotherm models, with a maximum adsorption capacity values in the range of 97.71 to 208.95 mg/g, which can be compared to or moderately higher than other sorbents published in the literatures. The dynamic disk mode studies indicated that the mean removal yields of three model estrogens were over 95% with a notable smaller amount of adsorbent (4 mg). Thermodynamic study revealed that the adsorption process was exothermic and spontaneous in nature. Desorption results showed that the adsorption capacity can remain up to 80% after seven times usage. It was suggested that Nylon 6 electrospun nanofibers mat has great potential as a novel effective sorbent material for estrogens removal.

  19. Effect of Methyl, Hydroxyl, and Chloro Substituents in Position 3 of 3',4',7-Trihydroxyflavylium: Stability, Kinetics, and Thermodynamics.

    PubMed

    Alejo-Armijo, Alfonso; Salido, Sofía; Altarejos, Joaquín; Parola, A Jorge; Gago, Sandra; Basílio, Nuno; Cabrita, Luis; Pina, Fernando

    2016-08-22

    The effect of methyl, hydroxyl, and chloride substituents in position 3 of the 3',4',7-trihydroxyflavylium core structure was studied. The stability, relative energy of each of chemical species (thermodynamics), and their rates of interconversion (kinetics) are very dependent on these substituents. By comparing the mole fraction distribution at equilibrium of the three multistate systems with the parent 3',4',7-trihydroxyflavylium, introduction of a methyl substituent in position 3 increases the mole fraction of hemiketal at the expense of the trans-chalcone and increases the hydration rate very significantly; a hydroxyl substituent in position 3 gives rise to a degradation process, as observed in anthocyanidins. In the case of 3-chloro-3',4',7-trihydroxyflavylium, a dramatic increase of the flavylium cation acidity was observed and a photochromic system can be operated upon irradiation of the respective trans-chalcone in 1 m HCl. According to the photochromic response of 3,3',4',7-tetrahydroxyflavylium and 3',4',7-trihydroxyflavylium, some requirements for a good photochromic performance are discussed. PMID:27465267

  20. Nylon 6 electrospun nanofibers mat as effective sorbent for the removal of estrogens: kinetic and thermodynamic studies

    PubMed Central

    2014-01-01

    Nylon 6 electrospun nanofibers mat was prepared via electrospinning for the removal of three estrogens, namely, diethylstilbestrol (DES), dienestrol (DS), and hexestrol (HEX) from aqueous solution. Static adsorption as well as the dynamic adsorption was evaluated by means of batch and dynamic disk flow mode, respectively. The kinetic study indicated that the adsorption of the target compounds could be well fitted by the pseudo-second-order equation, suggesting the intra-particle/membrane diffusion process as the rate-limiting step of the adsorption process. The adsorption equilibrium data were all fitted well to the Freundlich isotherm models, with a maximum adsorption capacity values in the range of 97.71 to 208.95 mg/g, which can be compared to or moderately higher than other sorbents published in the literatures. The dynamic disk mode studies indicated that the mean removal yields of three model estrogens were over 95% with a notable smaller amount of adsorbent (4 mg). Thermodynamic study revealed that the adsorption process was exothermic and spontaneous in nature. Desorption results showed that the adsorption capacity can remain up to 80% after seven times usage. It was suggested that Nylon 6 electrospun nanofibers mat has great potential as a novel effective sorbent material for estrogens removal. PMID:25114645

  1. Separating climate change signals into thermodynamic, lapse-rate and circulation effects: theory and application to the European summer climate

    NASA Astrophysics Data System (ADS)

    Kröner, Nico; Kotlarski, Sven; Fischer, Erich; Lüthi, Daniel; Zubler, Elias; Schär, Christoph

    2016-07-01

    Climate models robustly project a strong overall summer warming across Europe showing a characteristic north-south gradient with enhanced warming and drying in southern Europe. However, the processes that are responsible for this pattern are not fully understood. We here employ an extended surrogate or pseudo-warming approach to disentangle the contribution of different mechanisms to this response pattern. The basic idea of the surrogate technique is to use a regional climate model and apply a large-scale warming to the lateral boundary conditions of a present-day reference simulation, while maintaining the relative humidity (and thus implicitly increasing the specific moisture content). In comparison to previous studies, our approach includes two important extensions: first, different vertical warming profiles are applied in order to separate the effects of a mean warming from lapse-rate effects. Second, a twin-design is used, in which the climate change signals are not only added to present-day conditions, but also subtracted from a scenario experiment. We demonstrate that these extensions provide an elegant way to separate the full climate change signal into contributions from large-scale thermodynamic (TD), lapse-rate (LR), and circulation and other remaining effects (CO). The latter in particular include changes in land-ocean contrast and spatial variations of the SST warming patterns. We find that the TD effect yields a large-scale warming across Europe with no distinct latitudinal gradient. The LR effect, which is quantified for the first time in our study, leads to a stronger warming and some drying in southern Europe. It explains about 50 % of the warming amplification over the Iberian Peninsula, thus demonstrating the important role of lapse-rate changes. The effect is linked to an extending Hadley circulation. The CO effect as inherited from the driving GCM is shown to further amplify the north-south temperature change gradient. In terms of mean summer

  2. Kinetic and thermodynamic properties of beef heart mitochondrial ATPase: effect of co-solvent systems.

    PubMed

    Clark, D D; Schuster, S M

    1980-12-01

    The effects of glycerol and methanol upon beef heart mitochondrial ATPase (F1) were studied. Glycerol was found to be a potent reversible inhibitor of the F1-catalyzed hydrolysis of ATP and ITP. The inhibition of ATP hydrolysis was linear with respect to glycerol concentrations, while that of ITP was not. From the temperature dependence of Vmax for F1-catalyzed ATP and ITP hydrolysis in glycerol or methanol solutions, the energy of activation and the enthalpy of activation were calculated. The inhibitory effect of ADP on F1 hydrolytic activity was studied in three solvent systems (totally aqueous, 20% methanol, and 20% glycerol). Compared to the aqueous system, methanol decreased the potency of ADP as an inhibitor, and glycerol enhanced the potency. PMID:6455417

  3. Role of Solvation Effects in Protein Denaturation: From Thermodynamics to Single Molecules and Back

    PubMed Central

    England, Jeremy L.; Haran, Gilad

    2011-01-01

    Protein stability often is studied in vitro through the use of urea and guanidinium chloride, chemical cosolvents that disrupt protein native structure. Much controversy still surrounds the underlying mechanism by which these molecules denature proteins. Here we review current thinking on various aspects of chemical denaturation. We begin by discussing classic models of protein folding and how the effects of denaturants may fit into this picture through their modulation of the collapse, or coil-globule transition, which typically precedes folding. Subsequently, we examine recent molecular dynamics simulations that have shed new light on the possible microscopic origins of the solvation effects brought on by denaturants. It seems likely that both denaturants operate by facilitating solvation of hydrophobic regions of proteins. Finally, we present recent single-molecule fluorescence studies of denatured proteins, the analysis of which corroborates the role of denaturants in shifting the equilibrium of the coil-globule transition. PMID:21219136

  4. Reframing in dentistry: revisited.

    PubMed

    Nuvvula, Sivakumar; Kamatham, Rekalakshmi; Challa, Ramasubbareddy; Asokan, Sharath

    2013-01-01

    The successful practice of dentistry involves a good combination of technical skills and soft skills. Soft skills or communication skills are not taught extensively in dental schools and it can be challenging to learn and at times in treating dental patients. Guiding the child's behavior in the dental operatory is one of the preliminary steps to be taken by the pediatric dentist and one who can successfully modify the behavior can definitely pave the way for a life time comprehensive oral care. This article is an attempt to revisit a simple behavior guidance technique, reframing and explain the possible psychological perspectives behind it for better use in the clinical practice. PMID:24021326

  5. Bottomonium spectrum revisited

    NASA Astrophysics Data System (ADS)

    Segovia, Jorge; Ortega, Pablo G.; Entem, David R.; Fernández, Francisco

    2016-04-01

    We revisit the bottomonium spectrum motivated by the recently exciting experimental progress in the observation of new bottomonium states, both conventional and unconventional. Our framework is a nonrelativistic constituent quark model which has been applied to a wide range of hadronic observables from the light to the heavy quark sector, and thus the model parameters are completely constrained. Beyond the spectrum, we provide a large number of electromagnetic, strong and hadronic decays in order to discuss the quark content of the bottomonium states and give more insights about a better way to determine their properties experimentally.

  6. The improvement of soil thermodynamics and its effects on land surface meteorology in the IPSL climate model

    NASA Astrophysics Data System (ADS)

    Wang, F.; Cheruy, F.; Dufresne, J.-L.

    2016-01-01

    This paper describes the implementation of an improved soil thermodynamics in the hydrological module of Earth system model (ESM) developed at the Institut Pierre Simon Laplace (IPSL) and its effects on land surface meteorology in the IPSL climate model. A common vertical discretization scheme for the soil moisture and for the soil temperature is adopted. In addition to the heat conduction process, the heat transported by liquid water into the soil is modeled. The thermal conductivity and the heat capacity are parameterized as a function of the soil moisture and the texture. Preliminary tests are performed in an idealized 1-D (one-dimensional) framework and the full model is then evaluated in the coupled land-atmospheric module of the IPSL ESM. A nudging approach is used in order to avoid the time-consuming long-term simulations required to account for the natural variability of the climate. Thanks to this nudging approach, the effects of the modified parameterizations can be modeled. The dependence of the soil thermal properties on moisture and texture lead to the most significant changes in the surface energy budget and in the surface temperature, with the strongest effects on the surface energy budget taking place over dry areas and during the night. This has important consequences on the mean surface temperature over dry areas and during the night and on its short-term variability. The parameterization of the soil thermal properties could therefore explain some of the temperature biases and part of the dispersion over dry areas in simulations of extreme events such as heat waves in state-of-the-art climate models.

  7. The improvement of soil thermodynamics and its effects on land surface meteorology in the IPSL climate model

    NASA Astrophysics Data System (ADS)

    Wang, F.; Cheruy, F.; Dufresne, J.-L.

    2015-10-01

    This paper describes the implementation of an improved soil thermodynamics in the hydrological module of Earth System Model (ESM) developed at the Institut Pierre Simon Laplace (IPSL) and its effects on land surface meteorology in the IPSL climate model. A common vertical discretization scheme for the soil moisture and for the soil temperature is adopted. In addition to the heat conduction process, the heat transported by liquid water into the soil is modeled. The thermal conductivity and the heat capacity are parameterized as a function of the soil moisture and the texture. Preliminary tests are performed in an idealized 1-D framework and the full model is then evaluated in the coupled land/atmospheric module of the IPSL ESM. A nudging approach is used in order to avoid the time-consuming long-term simulations required to account for the natural variability of the climate. Thanks to this nudging approach, the effects of the modified parameterizations can be modeled. The dependence of the soil thermal properties on moisture and texture lead to the most significant changes in the surface energy budget and in the surface temperature, with the strongest effects on the surface energy budget taking place over dry areas and during the night. This has important consequences on the mean surface temperature over dry areas and during the night and on its short-term variability. The parameterization of the soil thermal properties could therefore explain some of the temperature biases and part of the dispersion over dry areas in simulations of extreme events such as heat waves in state-of-the-art climate models.

  8. Nonequilibrium thermodynamics of nucleation.

    PubMed

    Schweizer, M; Sagis, L M C

    2014-12-14

    We present a novel approach to nucleation processes based on the GENERIC framework (general equation for the nonequilibrium reversible-irreversible coupling). Solely based on the GENERIC structure of time-evolution equations and thermodynamic consistency arguments of exchange processes between a metastable phase and a nucleating phase, we derive the fundamental dynamics for this phenomenon, based on continuous Fokker-Planck equations. We are readily able to treat non-isothermal nucleation even when the nucleating cores cannot be attributed intensive thermodynamic properties. In addition, we capture the dynamics of the time-dependent metastable phase being continuously expelled from the nucleating phase, and keep rigorous track of the volume corrections to the dynamics. Within our framework the definition of a thermodynamic nuclei temperature is manifest. For the special case of nucleation of a gas phase towards its vapor-liquid coexistence, we illustrate that our approach is capable of reproducing recent literature results obtained by more microscopic considerations for the suppression of the nucleation rate due to nonisothermal effects. PMID:25494727

  9. Nonequilibrium thermodynamics of nucleation

    SciTech Connect

    Schweizer, M.; Sagis, L. M. C.

    2014-12-14

    We present a novel approach to nucleation processes based on the GENERIC framework (general equation for the nonequilibrium reversible-irreversible coupling). Solely based on the GENERIC structure of time-evolution equations and thermodynamic consistency arguments of exchange processes between a metastable phase and a nucleating phase, we derive the fundamental dynamics for this phenomenon, based on continuous Fokker-Planck equations. We are readily able to treat non-isothermal nucleation even when the nucleating cores cannot be attributed intensive thermodynamic properties. In addition, we capture the dynamics of the time-dependent metastable phase being continuously expelled from the nucleating phase, and keep rigorous track of the volume corrections to the dynamics. Within our framework the definition of a thermodynamic nuclei temperature is manifest. For the special case of nucleation of a gas phase towards its vapor-liquid coexistence, we illustrate that our approach is capable of reproducing recent literature results obtained by more microscopic considerations for the suppression of the nucleation rate due to nonisothermal effects.

  10. Thermodynamics. II - The extended thermodynamic system

    NASA Technical Reports Server (NTRS)

    Zeleznik, F. J.

    1981-01-01

    The algebraic theory of thermodynamics developed in a previous paper is extended to include the algebraic structure that arises from the introduction of a physical body into the theory. The extension is based on very general definitions of both the thermodynamic states of a body and subsystems of that body. The algebraic analysis, which includes bodies in nonuniform states, shows that the set of all thermodynamic states of a body has the same algebraic structure as the set of thermodynamic states and that composite systems are induced by the algebraic structure of thermodynamic states. The analysis also justifies a variational treatment of thermodynamic bodies in uniform as well as nonuniform states. The variational calculation includes all conventional methods of calculation as special cases and helps to illuminate the origin and interpretation of the electrochemical potential.

  11. A Thermodynamic Study of Dopant Interfacial Segregation Effect on Nanostability and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Wu, Longjia

    Nanoparticles, with great surface area and high surface to volume ratio, have been widely applied in many applications due to their unique size related effects. However, this high surface area character of nanoparticles also brings great excess energy to the whole system, making the system unstable and even causing the failure of nanoparticles, especially at higher temperatures. In order to maintain nanocrystalline structure of the materials, nanostability enhancement is of great significance in nanotechnology. It is well known that the global driving force for particles growth is to eliminate the excess energy brought by surface and grain boundary. Therefore, interfacial energetics has a great influence on the nanostability of the materials. And according to previous studies, dopant interfacial segregation could be a potential way to control the interfacial energetics of the nanoparticles and possibly lead to an improved nanostability. Furthermore, the interfacial energetics even can affect mechanical properties of nano-grain ceramic materials based on recent research. The main goals of the present work were to experimentally measure the interfacial energies of nanoparticles as well as nano-grain ceramics, modify the interfacial energetics through dopant segregation effect and engineer the nanostability and mechanical properties of the nanocrystalline materials through interfacial energetics modification. To achieve this goal, Mn cation has been chosen to introduce Mn interfacial segregation on ceria nanoparticles, and La cation has been added to 12 mol% yttria stabilized zirconia (12YSZ) and magnesium aluminate spinel (MAO) two-phase nano-grain ceramics to cause La interfacial segregation. Both of the dopant segregation phenomena were directly proved by electron energy loss spectroscopy (EELS). To quantify the dopant segregation effect on the interfacial energies, high-temperature oxide melt drop solution calorimetry, water adsorption calorimetry and differential

  12. Effects of atmospheric dusty plasma generated by natural radioactivity on the atmosphere thermodynamics and electrodynamics

    NASA Astrophysics Data System (ADS)

    Pulinets, Sergey; Ouzounov, Dimitar

    Natural radioactivity of the Earth through ionization creates a large number of new ions in the boundary layer of atmosphere from the ground surface up to near 1 km altitude. In specific conditions the ion concentration can reach 10 (6) -10 (7) cm (-3) . This sharp increase of ion concentration leads to the process of so called Ion Induced Nucleation (IIN) when due to ion's hydration the large complex ion clusters are formed with the very low recombination rate, i.e. we deal with formation of dusty atmospheric plasma in the boundary layer. Our theoretical estimates and experimental results of ground based and remote sensing satellite monitoring revealed two main consequences of IIN: release of large amount of the latent heat leading to the changes of air temperature and humidity, and sharp changes of air conductivity in the vertical column of the Global Electric Circuit (GEC) leading to formation of large scale irregularities of electron concentration in the ionosphere. The mechanism has universal character and its effects are observed in different natural and anthropogenic disasters like hurricanes, earthquakes, volcano eruption, artificial ionization, emergencies at atomic power plants, etc. Experimental evidences for many cases demonstrating effects of IIN are presented.

  13. Effects of Phosphine-Carbene Substitutions on the Electrochemical and Thermodynamic Properties of Nickel Complexes

    SciTech Connect

    Galan, Brandon R.; Wiedner, Eric S.; Helm, Monte L.; Linehan, John C.; Appel, Aaron M.

    2014-05-12

    Nickel(II) complexes containing chelating N-heterocyclic carbene-phosphine ligands ([NiL2](BPh4)2, for which L = [MeIm(CH2)2PR2]) have been synthesized for the purpose of studying how this class of ligand effects the electrochemical properties compared to the nickel bis- diphosphine analogues. The nickel complexes were synthesized and characterized by x-ray crystallography and electrochemical methods. Based on the half wave potentials (E1/2), substitution of an NHC for one of the phosphines in a diphoshine ligand results in shifts in potential to 0.6 V to 1.2 V more negative than the corresponding nickel bis-diphosphine complexes. These quantitative results highlight the substantial effect that NHC ligands can have upon the electronic properties of the metal complexes. BRG, JCL, and AMA acknowledge the support by the US Department of Energy Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. MLH acknoledges the support of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  14. Thermodynamic study on the effects of β-cyclodextrin inclusion with berberine

    NASA Astrophysics Data System (ADS)

    Yu, Jun-Sheng; Wei, Fang-Di; Gao, Wei; Zhao, Chang-Chun

    2002-01-01

    The fluorescence enhancement of berberine (Berb) as a result of complex with β-cyclodextrin (β-CD) is investigated. The association constants of α-CD and β-CD with Berb are 60 and 137 M -1 at 20 °C in pH 7.20 aqueous solution. Effects of temperature on the forming inclusion complexes of β-CD with Berb have been examined through using fluorescence titration. Enthalpy and entropy values calculated from fluorescence data are -33.7·kJ mol -1 and 74.3 J·mol -1·K -1, respectively. It was found that the dielectric constant of β-CD cavity is about 24 in a rough analogy with absolute alcohol. These results suggest that the extrusion of 'high energy water' molecules from the cavity of β-CD and hydrophobic interaction upon the inclusion complex formation are the main forces of the inclusion reaction. Effect of pH on the association of β-CD with Berb was also studied. Mechanism of the inclusion of β-CD with Berb is further studied by absorption and NMR measurements. Results show that β-CD forms a 1:1 inclusion complex with Berb.

  15. Influence of velocity effects on the shape of N2 (and air) broadened H2O lines revisited with classical molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Ngo, N. H.; Tran, H.; Gamache, R. R.; Bermejo, D.; Domenech, J.-L.

    2012-08-01

    The modeling of the shape of H2O lines perturbed by N2 (and air) using the Keilson-Storer (KS) kernel for collision-induced velocity changes is revisited with classical molecular dynamics simulations (CMDS). The latter have been performed for a large number of molecules starting from intermolecular-potential surfaces. Contrary to the assumption made in a previous study [H. Tran, D. Bermejo, J.-L. Domenech, P. Joubert, R. R. Gamache, and J.-M. Hartmann, J. Quant. Spectrosc. Radiat. Transf. 108, 126 (2007)], 10.1016/j.jqsrt.2007.03.009, the results of these CMDS show that the velocity-orientation and -modulus changes statistically occur at the same time scale. This validates the use of a single memory parameter in the Keilson-Storer kernel to describe both the velocity-orientation and -modulus changes. The CMDS results also show that velocity- and rotational state-changing collisions are statistically partially correlated. A partially correlated speed-dependent Keilson-Storer model has thus been used to describe the line-shape. For this, the velocity changes KS kernel parameters have been directly determined from CMDS, while the speed-dependent broadening and shifting coefficients have been calculated with a semi-classical approach. Comparisons between calculated spectra and measurements of several lines of H2O broadened by N2 (and air) in the ν3 and 2ν1 + ν2 + ν3 bands for a wide range of pressure show very satisfactory agreement. The evolution of non-Voigt effects from Doppler to collisional regimes is also presented and discussed.

  16. Thermodynamics and kinetics of apoazurin folding under macromolecular crowding effect and chemical interference

    NASA Astrophysics Data System (ADS)

    Zegarra, Fabio; Cheung, Margaret

    2013-03-01

    Proteins fold in a cellular milieu crowded by different kinds of macromolecules. They exert volume exclusion impacting protein folding processes in vivo. Folding processes, however, has been studied by chemical denaturation under in vitro conditions. The impact of the two factors as an attempt to advance the understanding of folding mechanism in vivo is not understood. Here, we investigate the folding mechanisms of apoazurin affected by the macromolecular crowding and chemical interference by using coarse-grained molecular simulations. Crowding agents are modeled as hard-spheres and the chemical denaturation effects are implemented into an energy function of the side chain and backbone interactions. Protein folding stability, mechanism, and kinetics rates of apoazurin under chemical interference and macromolecular crowding conditions are being investigated. Supported by NSF, Molecular & Cellular Biosciences (MCB0919974).

  17. Effects of solutes on thermodynamic activity of tritium in liquid lithium blanket of fusion reactor

    SciTech Connect

    Lyublinski, I.E.; Evtikhin, V.A.; Krassine, V.P.

    1995-10-01

    The study of tritium dissolved in liquid lithium systems containing metallic impurities is of technological interest for tritium removal processes and suppression of the tritium leakages from the blanket in a fusion reactor. The interaction parameter formalism and coordination cluster theory have been used to calculate the tritium activity coefficients in Li-T-Al, Li-T-Mg, Li-T-Si, Li-T-Y and Li-T-La systems. Calculations performed demonstrated that silicon, aluminum and magnesium have no influence on the tritium activity coefficients in dilute lithium solutions within the temperature range 400-800{degree}C, but yttrium and lanthanum may be used to effectively decrease this coefficient in lithium melts. 13 refs., 3 figs., 2 tabs.

  18. Effects of vacancy cluster defects on electrical and thermodynamic properties of silicon crystals.

    PubMed

    Huang, Pei-Hsing; Lu, Chi-Ming

    2014-01-01

    A first-principle plane-wave pseudopotential method based on the density function theory (DFT) was employed to investigate the effects of vacancy cluster (VC) defects on the band structure and thermoelectric properties of silicon (Si) crystals. Simulation results showed that various VC defects changed the energy band and localized electron density distribution of Si crystals and caused the band gap to decrease with increasing VC size. The results can be ascribed to the formation of a defect level produced by the dangling bonds, floating bonds, or high-strain atoms surrounding the VC defects. The appearance of imaginary frequencies in the phonon spectrum of defective Si crystals indicates that the defect-region structure is dynamically unstable and demonstrates phase changes. The phonon dispersion relation and phonon density of state were also investigated using density functional perturbation theory. The obtained Debye temperature ( θ D ) for a perfect Si crystal had a minimum value of 448 K at T = 42 K and a maximum value of 671 K at the high-temperature limit, which is consistent with the experimental results reported by Flubacher. Moreover, the Debye temperature decreased with increases in the VC size. VC defects had minimal effects on the heat capacity (C v ) value when temperatures were below 150 K. As the temperature was higher than 150 K, the heat capacity gradually increased with increasing temperature until it achieved a constant value of 11.8 cal/cell · K. The heat capacity significantly decreased as the VC size increased. For a 2 × 2 × 2 superlattice Si crystal containing a hexagonal ring VC (HRVC10), the heat capacity decreased by approximately 17%. PMID:24526923

  19. A density functional reactivity theory (DFRT) based approach to understand the effect of symmetry of fullerenes on the kinetic, thermodynamic and structural aspects of carbon NanoBuds

    NASA Astrophysics Data System (ADS)

    Sarmah, Amrit; Roy, Ram Kinkar

    2016-06-01

    In the present study, we have rationalized the effect of variation in the symmetry of relatively smaller fullerene (C32) on the mode of its interaction with semi-conducting Single-Walled Carbon Nanotubes (SWCNTs) in the process of formation of stable hybrid carbon NanoBuds. Thermodynamic and kinetic parameters, along with the charge transfer values associated with the interaction between fullerene and SWCNTs, have been evaluated using an un-conventional and computationally cost-effective method based on density functional reactivity theory (DFRT). In addition to this, conventional DFT based studies are also performed to substantiate the growth of NanoBud structures formed by the interaction between fullerene and SWCNTs. The findings of the present study suggest that the kinetic, thermodynamic and structural aspects of hybrid carbon NanoBuds are significantly influenced by both the symmetry of C32 fullerene and its site of covalent attachment to the SWCNT.

  20. Annealing effect on thermodynamic and physical properties of mesoporous silicon: A simulation and nitrogen sorption study

    NASA Astrophysics Data System (ADS)

    Kumar, Pushpendra; Huber, Patrick

    2016-04-01

    Discovery of porous silicon formation in silicon substrate in 1956 while electro-polishing crystalline Si in hydrofluoric acid (HF), has triggered large scale investigations of porous silicon formation and their changes in physical and chemical properties with thermal and chemical treatment. A nitrogen sorption study is used to investigate the effect of thermal annealing on electrochemically etched mesoporous silicon (PS). The PS was thermally annealed from 200˚C to 800˚C for 1 hr in the presence of air. It was shown that the pore diameter and porosity of PS vary with annealing temperature. The experimentally obtained adsorption / desorption isotherms show hysteresis typical for capillary condensation in porous materials. A simulation study based on Saam and Cole model was performed and compared with experimentally observed sorption isotherms to study the physics behind of hysteresis formation. We discuss the shape of the hysteresis loops in the framework of the morphology of the layers. The different behavior of adsorption and desorption of nitrogen in PS with pore diameter was discussed in terms of concave menisci formation inside the pore space, which was shown to related with the induced pressure in varying the pore diameter from 7.2 nm to 3.4 nm.

  1. Thermodynamic effects of replacements of Pro residues in helix interiors of maltose-binding protein.

    PubMed

    Prajapati, R S; Lingaraju, G M; Bacchawat, Kiran; Surolia, Avadhesha; Varadarajan, Raghavan

    2003-12-01

    Introduction of Pro residues into helix interiors results in protein destabilization. It is currently unclear if the converse substitution (i.e., replacement of Pro residues that naturally occur in helix interiors would be stabilizing). Maltose-binding protein is a large 370-amino acid protein that contains 21 Pro residues. Of these, three nonconserved residues (P48, P133, and P159) occur at helix interiors. Each of the residues was replaced with Ala and Ser. Stabilities were characterized by differential scanning calorimetry (DSC) as a function of pH and by isothermal urea denaturation studies as a function of temperature. The P48S and P48A mutants were found to be marginally more stable than the wild-type protein. In the pH range of 5-9, there is an average increase in T(m) values of P48A and P48S of 0.4 degrees C and 0.2 degrees C, respectively, relative to the wild-type protein. The other mutants are less stable than the wild type. Analysis of the effects of such Pro substitutions in MBP and in three other proteins studied to date suggests that substitutions are more likely to be stabilizing if the carbonyl group i-3 or i-4 to the mutation site is not hydrogen bonded in the wild-type protein. PMID:14635128

  2. Thermodynamic studies on the solvent effects in molecularly imprinted polymers. 2. Concentration of the organic modifier

    SciTech Connect

    Kim, Hyunjung; Guiochon, Georges A

    2005-03-01

    The effects of the organic modifier concentration on the isotherm parameters of the two enantiomers of Fmoc-tryptophan (Fmoc-l,d-Trp) on an Fmoc-l-Trp-imprinted polymer were investigated over a wide concentration range (0.005-100 mM), using frontal analysis. The modifier was acetic acid; concentrations of 0.2, 0.9, 1.7, and 3.7 M in an acetonitrile-based mobile phase were studied. At each concentration, adsorption isotherm data were acquired for each enantiomer. From these data, the isotherm parameters of each compound were derived from nonlinear isotherm fitting and the affinity energy distributions were calculated independently. We found that three types of sites coexist for Fmoc-l-Trp but only two types of sites for Fmoc-d-Trp, except at the lowest acetic acid concentration (0.2 M), at which three types of sites coexist. Increasing the acetic acid concentration decreases the selectivity and the overall affinity of both enantiomers. The overall affinity of Fmoc-l-Trp is dominated by the contribution of the low-density highest energy sites while that of Fmoc-d-Trp is dominated by the most abundant, low-energy sites. For the low-energy sites, increasing the acetic acid concentration affects the association constant of the enantiomers more than the number of corresponding sites. In contrast, for the highest energy sites (sites that exist only for Fmoc-l-Trp), increasing the concentration of acetic acid affects significantly the number of sites but hardly changes the association constant.

  3. Statistical Thermodynamics for Actin-Myosin Binding: The Crucial Importance of Hydration Effects.

    PubMed

    Oshima, Hiraku; Hayashi, Tomohiko; Kinoshita, Masahiro

    2016-06-01

    Actomyosin is an important molecular motor, and the binding of actin and myosin is an essential research target in biophysics. Nevertheless, the physical factors driving or opposing the binding are still unclear. Here, we investigate the role of water in actin-myosin binding using the most reliable statistical-mechanical method currently available for assessing biomolecules immersed in water. This method is characterized as follows: water is treated not as a dielectric continuum but as an ensemble of molecules; the polyatomic structures of proteins are taken into consideration; and the binding free energy is decomposed into physically insightful entropic and energetic components by accounting for the hydration effect to its full extent. We find that the actin-myosin binding brings large gains of electrostatic and Lennard-Jones attractive interactions. However, these gains are accompanied by even larger losses of actin-water and myosin-water electrostatic and LJ attractive interactions. Although roughly half of the energy increase due to the losses is cancelled out by the energy decrease arising from structural reorganization of the water released upon binding, the remaining energy increase is still larger than the energy decrease brought by the gains mentioned above. Hence, the net change in system energy is positive, which opposes binding. Importantly, the binding is driven by a large gain of configurational entropy of water, which surpasses the positive change in system energy and the conformational entropy loss occurring for actin and myosin. The principal physical origin of the large water-entropy gain is as follows: the actin-myosin interface is closely packed with the achievement of high shape complementarity on the atomic level, leading to a large increase in the total volume available to the translational displacement of water molecules in the system and a resultant reduction of water crowding (i.e., entropic correlations among water molecules). PMID

  4. Radiolytic Cryovolcanism Revisited

    NASA Astrophysics Data System (ADS)

    Cooper, J. F.; Cooper, P. D.; Sittler, E. C.; Wesenberg, R. P.

    2013-12-01

    Active geysers of water vapor and ice grains from the south pole of Enceladus are not yet definitively explained in terms of energy sources and processes. Other instances of hot (Io) and cold (Mars, Triton) volcanism beyond Earth are known if not fully understood. We revisit, in comparison to other models, the 'Old Faithful' theory of radiolytic gas-driven cryovolcanism first proposed by Cooper et al. [Plan. Sp. Sci. 2009]. In the energetic electron irradiation environment of Enceladus within Saturn's magnetosphere, a 10-percent duty cycle could be maintained for current geyser activity driven by gases from oxidation of ammonia to N2 and methane to CO2 in the thermal margins of a south polar sea. Much shorter duty cycles down to 0.01 percent would be required to account for thermal power output up to 16 GW, Steady accumulation of oxidant energy over four billion years could have powered all Enceladus emissions over the past four hundred thousand to four hundred million years. There could be separate energy sources driving mass flow and thermal emission over vastly different time scales. Since episodic tidal dissipation on 10 Myr time scales at 0.1 - 1 Gyr intervals [O'Neill and Nimmo, Nature 2010], and thus duty cycles 1 - 10 percent, could heat the polar sea to the current level, the radiolytic energy source could easily power and modulate the geyser mass flow on million-year time scales. Maximum thermal emission temperature 223 K [Abramov and Spencer, Icarus 2009] hints at thermal buffering in the basal and vent wall layers by a 1:1 H2O:H2O2 radiolytic eutectic, assuming deep ice crust saturation with H2O2 from long cumulative surface irradiation and downward ice convection. Due to density stratification the peroxide eutectic and salt water layers could separate, so that the denser peroxide layer (1.2 g/cc) descends to the polar sea while the lighter salt water (1.05 g/cc) rises along separate channels. Methane reservoirs could be found dissolved into the polar

  5. Measuring Thermodynamic Length

    SciTech Connect

    Crooks, Gavin E

    2007-09-07

    Thermodynamic length is a metric distance between equilibrium thermodynamic states. Among other interesting properties, this metric asymptotically bounds the dissipation induced by a finite time transformation of a thermodynamic system. It is also connected to the Jensen-Shannon divergence, Fisher information, and Rao's entropy differential metric. Therefore, thermodynamic length is of central interestin understanding matter out of equilibrium. In this Letter, we will consider how to denethermodynamic length for a small system described by equilibrium statistical mechanics and how to measure thermodynamic length within a computer simulation. Surprisingly, Bennett's classic acceptance ratio method for measuring free energy differences also measures thermodynamic length.

  6. EFFECT OF HEATING RATE ON THE THERMODYNAMIC PROPERTIES OF PULVERIZED COAL

    SciTech Connect

    Ramanathan Sampath

    1999-04-29

    This semi-annual technical progress report describes work performed under DOE Grant No. DE-FG22-96PC96224 during the period September 24, 1998 to March 23, 1999 which covers the fifth six months of the project. Devolatilization is an important initial step in virtually all commercial fossil fuel applications such as combustion, gasification, and liquefaction. Characterization of the temperature history of pulverized coal particles under high heating rates, representative of coal combustors, is critical to the understanding of devolatilization. During this reporting period, characterization experiments were continued from the previous reporting period and completed to a total of 28 single coal particles. These particles were caught in the electrodynamic balance and their volume, external surface area, mass, and density were measured. The same single particles were then heated bidirectionally with a pulsed (10 ms pulse width) Nd:YAG laser beams of equal intensity with heating rates (10{sup 4} - 10{sup 7} K/s) representative of coal combustors. The temporal power variation in the laser pulse was monitored for use in the heat transfer analysis by an ultra-fast fiber optic uv light transmitter included in the beam path and coupled to a silicon photodiode. Transient surface temperatures of the particles were measured using a single-color pyrometer. Dynamics of volatile evolution and particle swelling were recorded using well established time-resolved high-speed cinematography. Presently, extraction of devolatilization time-scales and temperature data at these time-scales running the high-speed films taken during the experiments employing a 16mm movie projector are in progress. Heat transfer analyses for the devolatilization time-scales, and temperature measurements (and hence an understanding of the effect of heating rates on coal thermal properties) are also in progress. Shipment of the donated heated grid system components from our industrial partner, United

  7. Fundamental limitations for quantum and nanoscale thermodynamics.

    PubMed

    Horodecki, Michał; Oppenheim, Jonathan

    2013-01-01

    The relationship between thermodynamics and statistical physics is valid in the thermodynamic limit-when the number of particles becomes very large. Here we study thermodynamics in the opposite regime-at both the nanoscale and when quantum effects become important. Applying results from quantum information theory, we construct a theory of thermodynamics in these limits. We derive general criteria for thermodynamical state transitions, and, as special cases, find two free energies: one that quantifies the deterministically extractable work from a small system in contact with a heat bath, and the other that quantifies the reverse process. We find that there are fundamental limitations on work extraction from non-equilibrium states, owing to finite size effects and quantum coherences. This implies that thermodynamical transitions are generically irreversible at this scale. As one application of these methods, we analyse the efficiency of small heat engines and find that they are irreversible during the adiabatic stages of the cycle. PMID:23800725

  8. Fundamental limitations for quantum and nanoscale thermodynamics

    NASA Astrophysics Data System (ADS)

    Horodecki, Michał; Oppenheim, Jonathan

    2013-06-01

    The relationship between thermodynamics and statistical physics is valid in the thermodynamic limit—when the number of particles becomes very large. Here we study thermodynamics in the opposite regime—at both the nanoscale and when quantum effects become important. Applying results from quantum information theory, we construct a theory of thermodynamics in these limits. We derive general criteria for thermodynamical state transitions, and, as special cases, find two free energies: one that quantifies the deterministically extractable work from a small system in contact with a heat bath, and the other that quantifies the reverse process. We find that there are fundamental limitations on work extraction from non-equilibrium states, owing to finite size effects and quantum coherences. This implies that thermodynamical transitions are generically irreversible at this scale. As one application of these methods, we analyse the efficiency of small heat engines and find that they are irreversible during the adiabatic stages of the cycle.

  9. A thermodynamic tank model for studying the effect of higher hydrocarbons on natural gas storage in metal-organic frameworks

    SciTech Connect

    Zhang, HD; Deria, P; Farha, OK; Hupp, JT; Snurr, RQ

    2015-01-01

    Metal-organic frameworks (MOFs) are promising materials for storing natural gas in vehicular applications. Evaluation of these materials has focused on adsorption of pure methane, although commercial natural gas also contains small amounts of higher hydrocarbons such as ethane and propane, which adsorb more strongly than methane. There is, thus, a possibility that these higher hydrocarbons will accumulate in the MOF after multiple operating (adsorption/desorption) cycles, and reduce the storage capacity. To study the net effect of ethane and propane on the performance of an adsorbed natural gas (ANG) tank, we developed a mathematical model based on thermodynamics and mass balance equations that describes the state of the tank at any instant. The required inputs are the pure-component isotherms, and mixture adsorption data are calculated using the Ideal Adsorbed Solution Theory (IAST). We focused on how the "deliverable energy'' provided by the ANG tank to the engine changed over 200 operating cycles for a sample of 120 MOF structures. We found that, with any MOF, the ANG tank performance monotonically declines during early operating cycles until a "cyclic steady state'' is reached. We determined that the best materials when the fuel is 100% methane are not necessarily the best when the fuel includes ethane and propane. Among the materials tested, some top MOFs are MOF-143 > NU-800 > IRMOF-14 > IRMOF-20 > MIL-100 > NU-125 > IRMOF-1 > NU-111. MOF-143 is predicted to deliver 5.43 MJ L-1 of tank to the engine once the cyclic steady state is reached. The model also provided insights that can assist in future work to discover more promising adsorbent materials for natural gas storage.

  10. Solvent effect on molecular structure, IR spectra, thermodynamic properties and chemical stability of zoledronic acid: DFT study.

    PubMed

    Liu, Qingzhu; Qiu, Ling; Wang, Yang; Lv, Gaochao; Liu, Guiqing; Wang, Shanshan; Lin, Jianguo

    2016-04-01

    Zoledronic acid (ZL) has been used widely for treating skeletal diseases because of its high potency in inhibiting bone resorption. A detailed understanding of its physicochemical characteristics may be of great significance in both medicinal chemistry and structural biology for the design of novel bisphosphonates with higher activity. In the present work, the monoclinic (IM) and triclinic (IT) polymorphs of ZL in the gas phase and the aqueous phase were studied by density functional theory (DFT) method at the B3LYP/6-311++G** level. The polarizable continuum model (PCM) was employed to study the solvent effect on structures and properties. The optimized IM and IT conformations in both phases are in reasonable agreement with the experimental structures with the overall mean absolute percent deviation (MAPD%) less than 3.1 %. The presence of intramolecular hydrogen bond within both conformations was identified in the solvent. The IR spectra were simulated and assigned in detail, which agreed well with the experimental data. The intramolecular hydrogen bonding interactions resulted in the shift of vibrational frequencies of hydroxyl to the low band by 12-22 cm(-1) and 24-26 cm(-1) for IM and IT conformations, respectively. Their thermodynamic properties were also calculated based on the harmonic vibrational analysis, including standard heat capacity (C (°) p,m), entropy (S (°) m), and enthalpy (H (°) m). The molecular stability, hydrogen bonding interaction and other electronic properties have been further analyzed by the natural bond orbital (NBO), atoms in molecules (AIM), molecular electrostatic potential (MEP) and frontier molecular orbital (FMO) analysis. Graphical abstract FMOs of IM and IT conformations in the gas phase and in the water. PMID:26994018

  11. Thermodynamic Studies for Drug Design and Screening

    PubMed Central

    Garbett, Nichola C.; Chaires, Jonathan B.

    2012-01-01

    Introduction A key part of drug design and development is the optimization of molecular interactions between an engineered drug candidate and its binding target. Thermodynamic characterization provides information about the balance of energetic forces driving binding interactions and is essential for understanding and optimizing molecular interactions. Areas covered This review discusses the information that can be obtained from thermodynamic measurements and how this can be applied to the drug development process. Current approaches for the measurement and optimization of thermodynamic parameters are presented, specifically higher throughput and calorimetric methods. Relevant literature for this review was identified in part by bibliographic searches for the period 2004 – 2011 using the Science Citation Index and PUBMED and the keywords listed below. Expert opinion The most effective drug design and development platform comes from an integrated process utilizing all available information from structural, thermodynamic and biological studies. Continuing evolution in our understanding of the energetic basis of molecular interactions and advances in thermodynamic methods for widespread application are essential to realize the goal of thermodynamically-driven drug design. Comprehensive thermodynamic evaluation is vital early in the drug development process to speed drug development towards an optimal energetic interaction profile while retaining good pharmacological properties. Practical thermodynamic approaches, such as enthalpic optimization, thermodynamic optimization plots and the enthalpic efficiency index, have now matured to provide proven utility in design process. Improved throughput in calorimetric methods remains essential for even greater integration of thermodynamics into drug design. PMID:22458502

  12. Study of the thermodynamic properties of CeO{sub 2} from ab initio calculations: The effect of phonon-phonon interaction

    SciTech Connect

    Niu, Zhen-Wei; Zeng, Zhao-Yi; Hu, Cui-E; Cai, Ling-Cang; Chen, Xiang-Rong

    2015-01-07

    The thermodynamic properties of CeO{sub 2} have been reevaluated by a simple but accurate scheme. All our calculations are based on the self-consistent ab initio lattice dynamical (SCAILD) method that goes beyond the quasiharmonic approximation. Through this method, the effects of phonon-phonon interactions are included. The obtained thermodynamic properties and phonon dispersion relations are in good agreement with experimental data when considering the correction of phonon-phonon interaction. We find that the correction of phonon-phonon interaction is equally important and should not be neglected. At last, by comparing with quasiharmonic approximation, the present scheme based on SCAILD method is probably more suitable for high temperature systems.

  13. Effect of the specific surface area on thermodynamic and kinetic properties of nanoparticle anatase TiO2 in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Madej, Edyta; Klink, Stefan; Schuhmann, Wolfgang; Ventosa, Edgar; La Mantia, Fabio

    2015-11-01

    Anatase TiO2 nanoparticles with a specific surface area of 100 m2 g-1 and 300 m2 g-1 have been investigated as negative insertion electrode material for lithium-ion batteries. Galvanostatic intermittent titration (GITT) and electrochemical impedance spectroscopy (EIS) were used to investigate the effect of the specific surface area on the performance of the material. GITT was performed at C/10 rate, followed by an EIS measurement after each relaxation step. Separation of kinetic and thermodynamic contributions to the overpotential of the phase transformation on Li+ (de-)insertion allowed revealing a dependency of both terms on the specific surface area. The material with higher surface area undergoes intrinsic transformation during the initial cycles affecting the thermodynamics of (de-)insertion while the sample with lower surface area shows large and asymmetric kinetic hindrances. For the material with 15 nm particles, Li+ de-insertion appears to have a higher resistance than lithium insertion.

  14. An Assessment of Thermodynamic Database Effects on Reactive Transport Models' Predictions of Permeability Fields: Insights from CO2/Brine Experiments

    NASA Astrophysics Data System (ADS)

    Tutolo, B. M.; Seyfried, W. E.; Saar, M. O.

    2011-12-01

    Numerical modeling software such as TOUGHREACT, ECLIPSE, and Geochemist's Workbench provide modules that couple mineral reactive chemistry with porosity and permeability modifications to predict the behavior of energy byproducts, such as carbon dioxide, in the subsurface. Modern coders have already included increasingly complex equations that describe natural systems (i.e. mineral dissolution/precipitation kinetic parameters and porosity/permeability functions) into these and other software applications. Generally, these computer models use the bulk volumetric changes predicted by geochemical calculations to infer porosity changes, and subsequently use highly simplified porosity/permeability correlation functions, such as the Carman-Kozeny equation, to modify permeability fields. In spite of the computational complexity provided in these models, they require, as a foundation, fundamental information on the thermodynamic stability of minerals and aqueous species at a wide range of temperatures and pressures to produce accurate predictions of the geochemistry of long-term energy byproduct storage in the subsurface, even in the simplest cases. With improvements in geochemical thermodynamic databases, researchers may begin to produce more realistic simulations of the complex interactions between fluid and heat flow and geological systems. Unfortunately, the requisite thermodynamic data is often lacking, or inaccurate. In this study, therefore, we provide a discussion of geochemical thermodynamic databases, discuss the synthesis and reconciliation of the databases used in this study, and compare predictions from reactive transport software with single phase CO2/brine experiments performed at temperatures and pressures applicable to geologic storage conditions.

  15. Revisiting Constructivist Teaching Methods in Ontario Colleges Preparing for Accreditation

    ERIC Educational Resources Information Center

    Schultz, Rachel A.

    2015-01-01

    At the time of writing, the first community colleges in Ontario were preparing for transition to an accreditation model from an audit system. This paper revisits constructivist literature, arguing that a more pragmatic definition of constructivism effectively blends positivist and interactionist philosophies to achieve both student centred…

  16. Revisiting Lambert's problem

    NASA Astrophysics Data System (ADS)

    Izzo, Dario

    2015-01-01

    The orbital boundary value problem, also known as Lambert problem, is revisited. Building upon Lancaster and Blanchard approach, new relations are revealed and a new variable representing all problem classes, under L-similarity, is used to express the time of flight equation. In the new variable, the time of flight curves have two oblique asymptotes and they mostly appear to be conveniently approximated by piecewise continuous lines. We use and invert such a simple approximation to provide an efficient initial guess to an Householder iterative method that is then able to converge, for the single revolution case, in only two iterations. The resulting algorithm is compared, for single and multiple revolutions, to Gooding's procedure revealing to be numerically as accurate, while having a significantly smaller computational complexity.

  17. Quantum duel revisited

    NASA Astrophysics Data System (ADS)

    Schmidt, Alexandre G. M.; Paiva, Milena M.

    2012-03-01

    We revisit the quantum two-person duel. In this problem, both Alice and Bob each possess a spin-1/2 particle which models dead and alive states for each player. We review the Abbott and Flitney result—now considering non-zero α1 and α2 in order to decide if it is better for Alice to shoot or not the second time—and we also consider a duel where players do not necessarily start alive. This simple assumption allows us to explore several interesting special cases, namely how a dead player can win the duel shooting just once, or how can Bob revive Alice after one shot, and the better strategy for Alice—being either alive or in a superposition of alive and dead states—fighting a dead opponent.

  18. Anonymous Signatures Revisited

    NASA Astrophysics Data System (ADS)

    Saraswat, Vishal; Yun, Aaram

    We revisit the notion of the anonymous signature, first formalized by Yang, Wong, Deng and Wang [10], and then further developed by Fischlin [4] and Zhang and Imai [11]. We present a new formalism of anonymous signature, where instead of the message, a part of the signature is withheld to maintain anonymity. We introduce the notion unpretendability to guarantee infeasibility for someone other than the correct signer to pretend authorship of the message and signature. Our definition retains applicability for all previous applications of the anonymous signature, provides stronger security, and is conceptually simpler. We give a generic construction from any ordinary signature scheme, and also show that the short signature scheme by Boneh and Boyen [2] can be naturally regarded as such a secure anonymous signature scheme according to our formalism.

  19. Satellite failures revisited

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2012-12-01

    In January 1994, the two geostationary satellites known as Anik-E1 and Anik-E2, operated by Telesat Canada, failed one after the other within 9 hours, leaving many northern Canadian communities without television and data services. The outage, which shut down much of the country's broadcast television for hours and cost Telesat Canada more than $15 million, generated significant media attention. Lam et al. used publicly available records to revisit the event; they looked at failure details, media coverage, recovery effort, and cost. They also used satellite and ground data to determine the precise causes of those satellite failures. The researchers traced the entire space weather event from conditions on the Sun through the interplanetary medium to the particle environment in geostationary orbit.

  20. The effect of dynamic-thermodynamic icebergs on the Southern Ocean climate in a three-dimensional model

    NASA Astrophysics Data System (ADS)

    Jongma, Jochem I.; Driesschaert, Emmanuelle; Fichefet, Thierry; Goosse, Hugues; Renssen, Hans

    Melting icebergs are a mobile source of fresh water as well as a sink of latent heat. In most global climate models, the spatio-temporal redistribution of fresh water and latent heat fluxes related to icebergs is parameterized by an instantaneous more or less arbitrary flux distribution over some parts of the oceans. It is uncertain if such a parameterization provides a realistic representation of the role of icebergs in the coupled climate system. However, icebergs could have a significant climate role, in particular during past abrupt climate change events which have been associated with armada's of icebergs. We therefore present the interactive coupling of a global climate model to a dynamic thermodynamic iceberg model, leading to a more plausible spatio-temporal redistribution of fresh water and heat fluxes. We show first that our model is able to reproduce a reasonable iceberg distribution in both hemispheres when compared to recent data. Second, in a series of sensitivity experiments we explore cooling and freshening effects of dynamical icebergs on the upper Southern Ocean and we compare these dynamic iceberg results to the effects of an equivalent parameterized iceberg flux. In our model without interactive icebergs, the parameterized fluxes are distributed homogeneously South of 55°S, whereas dynamic icebergs are found to be concentrated closer to shore except for a plume of icebergs floating North-East from the tip of the Antarctic Peninsula. Compared to homogeneous fluxes, the dynamic icebergs lead to a 10% greater net production of Antarctic bottom water (AABW). This increased bottom water production involves open ocean convection, which is enhanced by a less efficient stratification of the ocean when comparing to a homogeneous flux distribution. Icebergs facilitate the formation of sea-ice. In the sensitivity experiments, both the fresh water and the cooling flux lead to a significant increase in sea-ice area of 12% and 6%, respectively, directly

  1. Detection of DNA damage: effect of thymidine glycol residues on the thermodynamic, substrate and interfacial acoustic properties of oligonucleotide duplexes.

    PubMed

    Yang, F; Romanova, E; Kubareva, E; Dolinnaya, N; Gajdos, V; Burenina, O; Fedotova, E; Ellis, J S; Oretskaya, T; Hianik, T; Thompson, M

    2009-01-01

    Thymidine glycol residues in DNA are biologically active oxidative molecular damage sites caused by ionizing radiation and other factors. One or two thymidine glycol residues were incorporated in 19- to 31-mer DNA fragments during automatic oligonucleotide synthesis. These oligonucleotide models were used to estimate the effect of oxidized thymidines on the thermodynamic, substrate and interfacial acoustic properties of DNA. UV-monitoring melting data revealed that modified residues in place of thymidines destabilize the DNA double helix by 8-22 degrees C, depending on the number of lesions, the length of oligonucleotide duplexes and their GC-content. The diminished hybridizing capacity of modified oligonucleotides is presumably due to the loss of aromaticity and elevated hydrophilicity of thymine glycol in comparison to the thymine base. According to circular dichroism (CD) data, the modified DNA duplexes retain B-form geometry, and the thymidine glycol residue introduces only local perturbations limited to the lesion site. The rate of DNA hydrolysis by restriction endonucleases R.MvaI, R.Bst2UI, R.MspR9I and R.Bme1390I is significantly decreased as the thymidine glycol is located in the central position of the double-stranded recognition sequences 5'-CC / WGG-3' (W = A, T) or 5'-CC / NGG-3' (N = A, T, G, C) adjacent to the cleavage site. On the other hand, the catalytic properties of enzymes R.Psp6I and R.BstSCI recognizing the similar sequence are not changed dramatically, since their cleavage site is separated from the point of modification by several base-pairs. Data obtained by gel-electrophoretic analysis of radioactive DNA substrates were confirmed by direct spectrophotometric assay developed by the authors. The effect of thymidine glycol was also observed on DNA hybridization at the surface of a thickness-shear mode acoustic wave device. A 1.9-fold decrease in the rate of duplex formation was noted for oligonucleotides carrying one or two thymidine glycol

  2. Fluid mechanics revisited

    NASA Astrophysics Data System (ADS)

    Brenner, Howard

    2006-10-01

    neighbors when formulating physically satisfactory statistical-mechanical theories of irreversible transport processes in gases. Overall, the results of the present work implicitly support the unorthodox view, implicit in the GENERIC scheme, that the translation of Newton's discrete mass-point molecular mechanics into continuum mechanics, the latter as embodied in the Cauchy linear momentum equation of fluid mechanics, cannot be correctly effected independently of the laws of thermodynamics. While Öttinger's modification of GENERIC necessitates fundamental changes in the foundations of fluid mechanics in regard to momentum transport, no basic changes are required in the foundations of linear irreversible thermodynamics (LIT) beyond recognizing the need to add volume to the usual list of extensive physical properties undergoing transport in single-species fluid continua, namely mass, momentum and energy. An alternative, nonGENERICally based approach to LIT, derived from our findings, is outlined at the conclusion of the paper. Finally, our proposed modifications of both Cauchy's linear momentum equation and Newton's rheological constitutive law for fluid-phase continua are noted to be mirrored by counterparts in the literature for solid-phase continua dating back to the classical interdiffusion experiments of Kirkendall and their subsequent interpretation by Darken in terms of diffuse volume transport.

  3. Stirling Engine Gets Revisited

    ERIC Educational Resources Information Center

    Thompson, Frank

    2010-01-01

    One of the basic truths regarding energy conversion is that no thermodynamic cycle can be devised that is more efficient than a Carnot cycle operating between the same temperature limits. The efficiency of the Stirling cycle (patented by Rev. Robert Stirling in 1816) can approach that of the Carnot cycle and yet has not had the commercial success…

  4. Thermodynamics: Frontiers and Foundations.

    Energy Science and Technology Software Center (ESTSC)

    2009-07-27

    Version 00 Dr. J.D. Lewins has now released the following new book for free distribution: Thermodynamics: Frontiers and Foundations, Preface by Sir Alan Cottrell Introduction 1. Four-Square Foundations: The Laws of Thermodynamics 2. Maximum Entropy and Minimum Energy: The Master Functions and Equations 3. Ideal Gases and their Applications 4. Real Fluids and Some Applications 5. Van der Waals: A Model for Real Fluids 6. Surface Tension: Bubbles and Drops 7. Inert and Reactive Mixtures;more » An introduction to Chemical Thermodynamics 8. Radiation Thermodynamics: Solar Power Potential 9. Outposts of the Empire 10. A Glimpse into Statistical Thermodynamics Envoi« less

  5. Thermodynamics: Frontiers and Foundations.

    SciTech Connect

    JEFFERY,; LEWINS, D.

    2009-07-27

    Version 00 Dr. J.D. Lewins has now released the following new book for free distribution: Thermodynamics: Frontiers and Foundations, Preface by Sir Alan Cottrell Introduction 1. Four-Square Foundations: The Laws of Thermodynamics 2. Maximum Entropy and Minimum Energy: The Master Functions and Equations 3. Ideal Gases and their Applications 4. Real Fluids and Some Applications 5. Van der Waals: A Model for Real Fluids 6. Surface Tension: Bubbles and Drops 7. Inert and Reactive Mixtures; An introduction to Chemical Thermodynamics 8. Radiation Thermodynamics: Solar Power Potential 9. Outposts of the Empire 10. A Glimpse into Statistical Thermodynamics Envoi

  6. Nonlocal thermodynamic equilibrium effects in stratospheric HF by collisional energy transfer from electronically excited O2 and implications for infrared remote sensing

    NASA Technical Reports Server (NTRS)

    Kaye, Jack A.

    1989-01-01

    A possible nonlocal thermodynamic equilibrium (non-LTE) effect involving stratospheric HF arising from the direct photochemical excitation of vibrationally excited HF by collisional energy transfer from electronically excited O2 is presented. Although this non-LTE effect is smaller that one associated with the direct solar excitation of both HF(nv = 1) and HF(nv = 2), calculations show that inclusion of the mechanism into retrieval algorithms is necessary if correct daytime upper stratosphere HF profiles are to be inferred in future IR thermal emission measurements.

  7. Pressure effect on structural, elastic, and thermodynamic properties of tetragonal B{sub 4}C{sub 4}

    SciTech Connect

    Zheng, Baobing; Zhang, Meiguang; Luo, Hong-Gang

    2015-03-15

    The compressibility, elastic anisotropy, and thermodynamic properties of the recently proposed tetragonal B{sub 4}C{sub 4} (t-B{sub 4}C{sub 4}) are investigated under high temperature and high pressure by using of first-principles calculations method. The elastic constants, bulk modulus, shear modulus, Young’s modulus, Vickers hardness, Pugh’s modulus ratio, and Poisson’s ratio for t-B{sub 4}C{sub 4} under various pressures are systematically explored, the obtained results indicate that t-B{sub 4}C{sub 4} is a stiffer material. The elastic anisotropies of t-B{sub 4}C{sub 4} are discussed in detail under pressure from 0 GPa to 100 GPa. The thermodynamic properties of t-B{sub 4}C{sub 4}, such as Debye temperature, heat capacity, and thermal expansion coefficient are investigated by the quasi-harmonic Debye model.

  8. Effects of dynamic heterogeneity and density scaling of molecular dynamics on the relationship among thermodynamic coefficients at the glass transition

    SciTech Connect

    Koperwas, K. Grzybowski, A.; Grzybowska, K.; Wojnarowska, Z.; Paluch, M.

    2015-07-14

    In this paper, we define and experimentally verify thermodynamic characteristics of the liquid-glass transition, taking into account a kinetic origin of the process. Using the density scaling law and the four-point measure of the dynamic heterogeneity of molecular dynamics of glass forming liquids, we investigate contributions of enthalpy, temperature, and density fluctuations to spatially heterogeneous molecular dynamics at the liquid-glass transition, finding an equation for the pressure coefficient of the glass transition temperature, dTg/dp. This equation combined with our previous formula for dTg/dp, derived solely from the density scaling criterion, implies a relationship among thermodynamic coefficients at Tg. Since this relationship and both the equations for dTg/dp are very well validated using experimental data at Tg, they are promising alternatives to the classical Prigogine-Defay ratio and both the Ehrenfest equations in case of the liquid-glass transition.

  9. Thermodynamics of Thermoelectric Materials

    NASA Astrophysics Data System (ADS)

    Doak, Jeff W.

    driving force(s) for nanostructure formation, 2) investigate the thermodynamics of PbTe--PbS alloys in more detail, including the effects of thermal motion, which are important and difficult to investigate due to the inherently anharmonic nature of PbTe, 3) investigate the thermodynamics of doping Na into PbTe and PbS, 4) investigate the thermodynamics of Na at the interface between PbTe and PbS, to understand how a nominal dopant can also cause changes in the morphology of nanostructures, and 5) apply the lessons learned in the above investigations, combined with measures of good electronic properties to screen for new thermoelectric alloys of II--VI, IIb--VI, and IV--VI compounds which will have improved thermoelectric performance. With this work we can move the field of thermoelectric materials forward, providing insight and predictions for further experimental refinement, leading to more efficient materials, and a more energy efficient future.

  10. Thermodynamic aspects of materials science

    NASA Astrophysics Data System (ADS)

    Rusanov, A. I.

    2016-01-01

    As materials science studies physicochemical properties of materials, it needs a support of thermodynamics, which predicts general regularities for physicochemical properties of matter. This survey deals with solid materials the thermodynamic description of which is especially complicated. The achievements of last years provide better insight in the chemical potential anisotropy and, on this grounding, in the anisotropy of chemical affinity governing all processes in solid materials. The survey summarizes novel approaches and thermodynamic equations and then exhibits their use in materials science. As examples, the solubility, creep and corrosion of materials are analyzed. A newly discovered phenomenon, the strain sign effect in corrosion under stress (e.g., a difference in the corrosion rate on the opposite sides of a bent metallic plate), is described and explained thermodynamically. A modern theory of the strength of materials developed during last years is also presented with the characterization of crack properties, the mechanisms of crack propagation and estimation of the ultimate stress. The development of this area required the introduction of a novel thermodynamic potential that formed the basis for the theory of strength. The bibliography includes 47 references.

  11. In-car countermeasures open window and music revisited on the real road: popular but hardly effective against driver sleepiness.

    PubMed

    Schwarz, Johanna F A; Ingre, Michael; Fors, Carina; Anund, Anna; Kecklund, Göran; Taillard, Jacques; Philip, Pierre; Åkerstedt, Torbjörn

    2012-10-01

    This study investigated the effects of two very commonly used countermeasures against driver sleepiness, opening the window and listening to music, on subjective and physiological sleepiness measures during real road driving. In total, 24 individuals participated in the study. Sixteen participants received intermittent 10-min intervals of: (i) open window (2 cm opened); and (ii) listening to music, during both day and night driving on an open motorway. Both subjective sleepiness and physiological sleepiness (blink duration) was estimated to be significantly reduced when subjects listened to music, but the effect was only minor compared with the pronounced effects of night driving and driving duration. Open window had no attenuating effect on either sleepiness measure. No significant long-term effects beyond the actual countermeasure application intervals occurred, as shown by comparison to the control group (n = 8). Thus, despite their popularity, opening the window and listening to music cannot be recommended as sole countermeasures against driver sleepiness. PMID:22458959

  12. Coherence and measurement in quantum thermodynamics.

    PubMed

    Kammerlander, P; Anders, J

    2016-01-01

    Thermodynamics is a highly successful macroscopic theory widely used across the natural sciences and for the construction of everyday devices, from car engines to solar cells. With thermodynamics predating quantum theory, research now aims to uncover the thermodynamic laws that govern finite size systems which may in addition host quantum effects. Recent theoretical breakthroughs include the characterisation of the efficiency of quantum thermal engines, the extension of classical non-equilibrium fluctuation theorems to the quantum regime and a new thermodynamic resource theory has led to the discovery of a set of second laws for finite size systems. These results have substantially advanced our understanding of nanoscale thermodynamics, however putting a finger on what is genuinely quantum in quantum thermodynamics has remained a challenge. Here we identify information processing tasks, the so-called projections, that can only be formulated within the framework of quantum mechanics. We show that the physical realisation of such projections can come with a non-trivial thermodynamic work only for quantum states with coherences. This contrasts with information erasure, first investigated by Landauer, for which a thermodynamic work cost applies for classical and quantum erasure alike. Repercussions on quantum work fluctuation relations and thermodynamic single-shot approaches are also discussed. PMID:26916503

  13. Coherence and measurement in quantum thermodynamics

    PubMed Central

    Kammerlander, P.; Anders, J.

    2016-01-01

    Thermodynamics is a highly successful macroscopic theory widely used across the natural sciences and for the construction of everyday devices, from car engines to solar cells. With thermodynamics predating quantum theory, research now aims to uncover the thermodynamic laws that govern finite size systems which may in addition host quantum effects. Recent theoretical breakthroughs include the characterisation of the efficiency of quantum thermal engines, the extension of classical non-equilibrium fluctuation theorems to the quantum regime and a new thermodynamic resource theory has led to the discovery of a set of second laws for finite size systems. These results have substantially advanced our understanding of nanoscale thermodynamics, however putting a finger on what is genuinely quantum in quantum thermodynamics has remained a challenge. Here we identify information processing tasks, the so-called projections, that can only be formulated within the framework of quantum mechanics. We show that the physical realisation of such projections can come with a non-trivial thermodynamic work only for quantum states with coherences. This contrasts with information erasure, first investigated by Landauer, for which a thermodynamic work cost applies for classical and quantum erasure alike. Repercussions on quantum work fluctuation relations and thermodynamic single-shot approaches are also discussed. PMID:26916503

  14. Coherence and measurement in quantum thermodynamics

    NASA Astrophysics Data System (ADS)

    Kammerlander, P.; Anders, J.

    2016-02-01

    Thermodynamics is a highly successful macroscopic theory widely used across the natural sciences and for the construction of everyday devices, from car engines to solar cells. With thermodynamics predating quantum theory, research now aims to uncover the thermodynamic laws that govern finite size systems which may in addition host quantum effects. Recent theoretical breakthroughs include the characterisation of the efficiency of quantum thermal engines, the extension of classical non-equilibrium fluctuation theorems to the quantum regime and a new thermodynamic resource theory has led to the discovery of a set of second laws for finite size systems. These results have substantially advanced our understanding of nanoscale thermodynamics, however putting a finger on what is genuinely quantum in quantum thermodynamics has remained a challenge. Here we identify information processing tasks, the so-called projections, that can only be formulated within the framework of quantum mechanics. We show that the physical realisation of such projections can come with a non-trivial thermodynamic work only for quantum states with coherences. This contrasts with information erasure, first investigated by Landauer, for which a thermodynamic work cost applies for classical and quantum erasure alike. Repercussions on quantum work fluctuation relations and thermodynamic single-shot approaches are also discussed.

  15. The Effect of Head Orientation on Perceived Gaze Direction: Revisiting Gibson and Pick (1963) and Cline (1967).

    PubMed

    Moors, Pieter; Verfaillie, Karl; Daems, Thalia; Pomianowska, Iwona; Germeys, Filip

    2016-01-01

    Two biases in perceived gaze direction have been observed when eye and head orientation are not aligned. An overshoot effect indicates that perceived gaze direction is shifted away from head orientation (i.e., a repulsive effect), whereas a towing effect indicates that perceived gaze direction falls in between head and eye orientation (i.e., an attraction effect). In the 60s, three influential papers have been published with respect to the effect of head orientation on perceived gaze direction (Gibson and Pick, 1963; Cline, 1967; Anstis et al., 1969). Throughout the years, the results of two of these (Gibson and Pick, 1963; Cline, 1967) have been interpreted differently by a number of authors. In this paper, we critically discuss potential sources of confusion that have led to differential interpretations of both studies. At first sight, the results of Cline (1967), despite having been a major topic of discussion, unambiguously seem to indicate a towing effect whereas Gibson and Pick's (1963) results seem to be the most ambiguous, although they have never been questioned in the literature. To shed further light on this apparent inconsistency, we repeated the critical experiments reported in both studies. Our results indicate an overshoot effect in both studies. PMID:27559325

  16. The Effect of Head Orientation on Perceived Gaze Direction: Revisiting Gibson and Pick (1963) and Cline (1967)

    PubMed Central

    Moors, Pieter; Verfaillie, Karl; Daems, Thalia; Pomianowska, Iwona; Germeys, Filip

    2016-01-01

    Two biases in perceived gaze direction have been observed when eye and head orientation are not aligned. An overshoot effect indicates that perceived gaze direction is shifted away from head orientation (i.e., a repulsive effect), whereas a towing effect indicates that perceived gaze direction falls in between head and eye orientation (i.e., an attraction effect). In the 60s, three influential papers have been published with respect to the effect of head orientation on perceived gaze direction (Gibson and Pick, 1963; Cline, 1967; Anstis et al., 1969). Throughout the years, the results of two of these (Gibson and Pick, 1963; Cline, 1967) have been interpreted differently by a number of authors. In this paper, we critically discuss potential sources of confusion that have led to differential interpretations of both studies. At first sight, the results of Cline (1967), despite having been a major topic of discussion, unambiguously seem to indicate a towing effect whereas Gibson and Pick’s (1963) results seem to be the most ambiguous, although they have never been questioned in the literature. To shed further light on this apparent inconsistency, we repeated the critical experiments reported in both studies. Our results indicate an overshoot effect in both studies. PMID:27559325

  17. Revisiting the therapeutic effect of rTMS on negative symptoms in schizophrenia: A meta-analysis

    PubMed Central

    Shi, Chuan; Yu, Xin; Cheung, Eric F.C.; Shum, David H.K.; Chan, Raymond C.K.

    2014-01-01

    This study sought to determine the moderators in the treatment effect of repetitive transcranial magnetic stimulation (rTMS) on negative symptoms in schizophrenia. We performed a meta-analysis of prospective studies on the therapeutic application of rTMS in schizophrenia assessing the effects of both low-frequency and high-frequency rTMS on negative symptoms. Results indicate that rTMS is effective in alleviating negative symptoms in schizophrenia. The effect size was moderate (0.63 and 0.53, respectively). The effect size of rTMS on negative symptoms in sham-controlled trials was 0.80 as measured by the SANS and 0.41 as measured by the PANSS. A longer duration of illness was associated with poorer efficacy of rTMS on negative symptoms. A 10 Hz setting, at least 3 consecutive weeks of treatment, treatment site at the left dorsolateral prefrontal cortex (DLPFC) and a 110% motor threshold (MT) were found to be the best rTMS parameters for the treatment of negative symptoms. The results of our meta-analysis suggest that rTMS is an effective treatment option for negative symptoms in schizophrenia. The moderators of rTMS on negative symptoms included duration of illness, stimulus frequency, duration of illness, position and intensity of treatment as well as the type of outcome measures used. PMID:24411074

  18. Thermodynamics of Error Correction

    NASA Astrophysics Data System (ADS)

    Sartori, Pablo; Pigolotti, Simone

    2015-10-01

    Information processing at the molecular scale is limited by thermal fluctuations. This can cause undesired consequences in copying information since thermal noise can lead to errors that can compromise the functionality of the copy. For example, a high error rate during DNA duplication can lead to cell death. Given the importance of accurate copying at the molecular scale, it is fundamental to understand its thermodynamic features. In this paper, we derive a universal expression for the copy error as a function of entropy production and work dissipated by the system during wrong incorporations. Its derivation is based on the second law of thermodynamics; hence, its validity is independent of the details of the molecular machinery, be it any polymerase or artificial copying device. Using this expression, we find that information can be copied in three different regimes. In two of them, work is dissipated to either increase or decrease the error. In the third regime, the protocol extracts work while correcting errors, reminiscent of a Maxwell demon. As a case study, we apply our framework to study a copy protocol assisted by kinetic proofreading, and show that it can operate in any of these three regimes. We finally show that, for any effective proofreading scheme, error reduction is limited by the chemical driving of the proofreading reaction.

  19. Revisiting the Effect of Capture Heterogeneity on Survival Estimates in Capture-Mark-Recapture Studies: Does It Matter?

    PubMed Central

    Abadi, Fitsum; Botha, Andre; Altwegg, Res

    2013-01-01

    Recently developed capture-mark-recapture methods allow us to account for capture heterogeneity among individuals in the form of discrete mixtures and continuous individual random effects. In this article, we used simulations and two case studies to evaluate the effectiveness of continuously distributed individual random effects at removing potential bias due to capture heterogeneity, and to evaluate in what situation the added complexity of these models is justified. Simulations and case studies showed that ignoring individual capture heterogeneity generally led to a small negative bias in survival estimates and that individual random effects effectively removed this bias. As expected, accounting for capture heterogeneity also led to slightly less precise survival estimates. Our case studies also showed that accounting for capture heterogeneity increased in importance towards the end of study. Though ignoring capture heterogeneity led to a small bias in survival estimates, such bias may greatly impact management decisions. We advocate reducing potential heterogeneity at the sampling design stage. Where this is insufficient, we recommend modelling individual capture heterogeneity in situations such as when a large proportion of the individuals has a low detection probability (e.g. in the presence of floaters) and situations where the most recent survival estimates are of great interest (e.g. in applied conservation). PMID:23646131

  20. Sex Offender Recidivism Revisited: Review of Recent Meta-analyses on the Effects of Sex Offender Treatment.

    PubMed

    Kim, Bitna; Benekos, Peter J; Merlo, Alida V

    2016-01-01

    The effectiveness of sex offender treatment programs continues to generate misinformation and disagreement. Some literature reviews conclude that treatment does not reduce recidivism while others suggest that specific types of treatment may warrant optimism. The principal purpose of this study is to update the most recent meta-analyses of sex offender treatments and to compare the findings with an earlier study that reviewed the meta-analytic studies published from 1995 to 2002. More importantly, this study examines effect sizes across different age populations and effect sizes across various sex offender treatments. Results of this review of meta-analyses suggest that sex offender treatments can be considered as "proven" or at least "promising," while age of participants and intervention type may influence the success of treatment for sex offenders. The implications of these findings include achieving a broader understanding of intervention moderators, applying such interventions to juvenile and adult offenders, and outlining future areas of research. PMID:25575803

  1. Nature of Interactions during Teacher-Student Writing Conferences, Revisiting the Potential Effects of Self-Efficacy Beliefs

    ERIC Educational Resources Information Center

    Bayraktar, Aysegül

    2013-01-01

    Problem Statement: Within Language Arts instruction the use of teacher-student writing conferences is accepted as an effective strategy for teaching writing. The writing conference allows for an individual one-on-one teacher-student conversation about the students' writing or writing process and provides the student an audience in terms of…

  2. Revisiting Gordon's Teacher Effectiveness Training: An Intervention Study on Teachers' Social and Emotional Learning

    ERIC Educational Resources Information Center

    Talvio, Markus; Lonka, Kirsti; Komulainen, Erkki; Kuusela, Marjo; Lintunen, Taru

    2013-01-01

    Introduction: This study explored the development of teachers' social and emotional learning (SEL) skills by using "Teacher Effectiveness Training (TET)" (Gordon Training International) as an intervention with two groups of teachers. Further Gordon's model was approached from the perspective of modern educational psychology.…

  3. Effects of Familiarity on the Perceptual Integrality of the Identity and Expression of Faces: The Parallel-Route Hypothesis Revisited

    ERIC Educational Resources Information Center

    Ganel, Tzvi; Goshen-Gottstein, Yonatan

    2004-01-01

    The effects of familiarity on selective attention for the identity and expression of faces were tested using Garner's speeded-classification task. In 2 experiments, participants classified expression (or identity) of familiar and unfamiliar faces while the irrelevant dimension of identity (or expression) was either held constant (baseline…

  4. Revisiting the health effects of psychological stress—its influence on susceptibility to ionizing radiation: a mini-review

    PubMed Central

    Wang, Bing; Katsube, Takanori; Begum, Nasrin; Nenoi, Mitsuru

    2016-01-01

    Both psychological stress (PS) and ionizing radiation (IR) cause varied detrimental effects on humans. There has been no direct evidence so far showing PS alone could cause cancer; however, long-lasting PS may affect our overall health and ability to cope with cancer. Due to their living conditions and occupations, some people may encounter concurrent exposure to both PS and IR to a high extent. In addition to possible health effects resulting directly from exposure to IR on these people, fear of IR exposure is also a cause of PS. The question of whether PS would influence susceptibility to IR, radiocarcinogenesis in particular, is of great concern by both the academic world and the public. Recently, investigations using animal PS models demonstrated that PS could modulate susceptibility to IR, causing increased susceptibility to radiocarcinogenesis in Trp53-heterozygous mice, hematological toxicity in peripheral blood and elevated chromosome aberration (dicentrics) frequency in splenocytes of Trp53–wild-type mice. To actively reduce health risk from exposure to IR, further studies are needed to cumulate more evidence and provide insights into the mechanisms underlying the alterations in susceptibility due to PS modulation. This mini-review gives a general overview of the significance of PS effects on humans and experimental animals, with a special focus on summarizing the latest weight-of-evidence approaches to radiobiological studies on PS-induced alterations in susceptibility in experimental animal models. The susceptibility being investigated is mainly in the context of the impact of the modulatory effect of PS on radiocarcinogenesis; we seek to improve understanding of the combined effects of exposure to both PS and IR in order to facilitate, via active intervention, strategies for radiation risk reduction. PMID:27242342

  5. Revisiting the health effects of psychological stress-its influence on susceptibility to ionizing radiation: a mini-review.

    PubMed

    Wang, Bing; Katsube, Takanori; Begum, Nasrin; Nenoi, Mitsuru

    2016-07-01

    Both psychological stress (PS) and ionizing radiation (IR) cause varied detrimental effects on humans. There has been no direct evidence so far showing PS alone could cause cancer; however, long-lasting PS may affect our overall health and ability to cope with cancer. Due to their living conditions and occupations, some people may encounter concurrent exposure to both PS and IR to a high extent. In addition to possible health effects resulting directly from exposure to IR on these people, fear of IR exposure is also a cause of PS. The question of whether PS would influence susceptibility to IR, radiocarcinogenesis in particular, is of great concern by both the academic world and the public. Recently, investigations using animal PS models demonstrated that PS could modulate susceptibility to IR, causing increased susceptibility to radiocarcinogenesis in Trp53-heterozygous mice, hematological toxicity in peripheral blood and elevated chromosome aberration (dicentrics) frequency in splenocytes of Trp53-wild-type mice. To actively reduce health risk from exposure to IR, further studies are needed to cumulate more evidence and provide insights into the mechanisms underlying the alterations in susceptibility due to PS modulation. This mini-review gives a general overview of the significance of PS effects on humans and experimental animals, with a special focus on summarizing the latest weight-of-evidence approaches to radiobiological studies on PS-induced alterations in susceptibility in experimental animal models. The susceptibility being investigated is mainly in the context of the impact of the modulatory effect of PS on radiocarcinogenesis; we seek to improve understanding of the combined effects of exposure to both PS and IR in order to facilitate, via active intervention, strategies for radiation risk reduction. PMID:27242342

  6. The core group revisited: the effect of partner mixing and migration on the spread of gonorrhea, Chlamydia, and HIV.

    PubMed

    Stigum, H; Falck, W; Magnus, P

    1994-03-01

    A set of differential equations are used to model the spread of sexually transmitted diseases (STDs) in a one-sex population that includes a core group of highly sexually active subjects. The effects of partner mixing between groups and migration to and from the core on the equilibrium number of infected are shown for gonorrhea, chlamydia, and HIV. The STDs are described by the transmission probability per sexual contact and the duration of infectiousness. Partner change and intercourse frequencies are estimated from sexual survey data on heterosexual behavior. The core group is small (3% of the total population) with a partner change frequency 15 times and an intercourse frequency 2 times that of the remaining population. The degree of partner mixing and migration between the two groups can be varied. The number of sexual contacts in the three types of partnerships (core-core, "mixed," remaining population-remaining population) is also modeled. The mixed partnerships are assumed to be casual and to have a low frequency of intercourse. The model is fairly simple, and the emphasis is on qualitative rather that predictive results. The effects of partner mixing are found to be strikingly different for gonorrhea, chlamydia, and HIV. With increasing partner mixing between groups, gonorrhea shows a small increase and then a decrease in the total number of infected, whereas chlamydial infection shows a strong increase. For HIV infection the effect depends on the transmission probability; when it is 0.001 per sexual contact, the number of infected with HIV is almost unaffected by the partner mixing, and when the transmission probability is 0.002 per sexual contact, there is a strong increase in the number of HIV infected with increasing partner mixing. The effects of migration are also different for each disease. With increasing migration between groups, gonorrhea is almost unaffected in the total number of infected, whereas chlamydial infection shows a strong increase

  7. Stacking Global Seismograms Revisited

    NASA Astrophysics Data System (ADS)

    Shearer, P. M.; Buehler, J. S.; Denolle, M.; Fan, W.; Ma, Z.; Mancinelli, N. J.; Matoza, R. S.; Wang, W.; Wang, Y.; Zhan, Z.

    2014-12-01

    Over 20 years ago, stacks of global seismograms produced direct images of the global seismic wavefield highlighting the visibility, frequency content, and polarity of known seismic phases, and also identified a host of new phases associated with reflections and phase conversions from upper-mantle discontinuities. Two different stacking methods proved particularly useful: (1) STA/LTA-filtered stacks that describe the local signal-to-noise characteristics of the major seismic phases. These serve to image the entire wavefield in a uniform way for educational purposes and to show which phases are observed most clearly as a guide to future research. These stacks also resolve SH versus SV timing differences consistent with radial anisotropy. (2) Reference-phase stacks that preserve the polarity, amplitude, and timing of traces with respect to a specified target phase. These show a large number of top-side and bottom-side reflections and phase conversions from the 410- and 660-km discontinuities that create weak phases with a characteristic "railroad track" appearance both preceding and following many of the main seismic phases. Reference-phase stacking can also be used to produce coherent surface-wave stacks at very long periods, which directly show the dispersive character of the surface waves. Here we revisit and update these stacks by exploiting the vastly increased data now available from the IRIS DMC to produce greatly improved wavefield images. We present several examples of the different stacking approaches and point out their various features, including promising targets for future research.

  8. Multinomial pattern matching revisited

    NASA Astrophysics Data System (ADS)

    Horvath, Matthew S.; Rigling, Brian D.

    2015-05-01

    Multinomial pattern matching (MPM) is an automatic target recognition algorithm developed for specifically radar data at Sandia National Laboratories. The algorithm is in a family of algorithms that first quantizes pixel value into Nq bins based on pixel amplitude before training and classification. This quantization step reduces the sensitivity of algorithm performance to absolute intensity variation in the data, typical of radar data where signatures exhibit high variation for even small changes in aspect angle. Our previous work has focused on performance analysis of peaky template matching, a special case of MPM where binary quantization is used (Nq = 2). Unfortunately references on these algorithms are generally difficult to locate and here we revisit the MPM algorithm and illustrate the underlying statistical model and decision rules for two algorithm interpretations: the 1-of-K vector form and the scalar. MPM can also be used as a detector and specific attention is given to algorithm tuning where "peak pixels" are chosen based on their underlying empirical probabilities according to a reward minimization strategy aimed at reducing false alarms in the detection scenario and false positives in a classification capacity. The algorithms are demonstrated using Monte Carlo simulations on the AFRL civilian vehicle dataset for variety of choices of Nq.

  9. CGL description revisited

    NASA Astrophysics Data System (ADS)

    Hunana, P.; Zank, G. P.; Goldstein, M. L.; Webb, G. M.; Adhikari, L.

    2016-03-01

    Solar wind observational studies have emphasized that the solar wind plasma data is bounded by the mirror and firehose instabilities, and it is often believed that these instabilities are of a purely kinetic nature. The simplest fluid model that generalizes magnetohydrodynamics with anisotropic temperatures is the Chew-Goldberger-Low model (CGL). Here we briefly revisit the CGL description and discuss its (otherwise well-documented) linear firehose and mirror instability thresholds; namely that the firehose instability threshold is identical to the one found from linear kinetic theory and that the mirror threshold contains a factor of 6 error. We consider a simple higher-order fluid model with time dependent heat flux equations and show that the mirror instability threshold is correctly reproduced. We also present fully nonlinear three-dimensional simulations of freely decaying turbulence for the Hall-CGL model with isothermal electrons. The spatial resolution of these simulations is 5123 and the formation of a spectral break in magnetic and velocity field spectra around the proton inertial length is found.

  10. Revisiting caspases in sepsis

    PubMed Central

    Aziz, M; Jacob, A; Wang, P

    2014-01-01

    Sepsis is a life-threatening illness that occurs due to an abnormal host immune network which extends through the initial widespread and overwhelming inflammation, and culminates at the late stage of immunosupression. Recently, interest has been shifted toward therapies aimed at reversing the accompanying periods of immune suppression. Studies in experimental animals and critically ill patients have demonstrated that increased apoptosis of lymphoid organs and some parenchymal tissues contributes to this immune suppression, anergy and organ dysfunction. Immediate to the discoveries of the intracellular proteases, caspases for the induction of apoptosis and inflammation, and their striking roles in sepsis have been focused elaborately in a number of original and review articles. Here we revisited the different aspects of caspases in terms of apoptosis, pyroptosis, necroptosis and inflammation and focused their links in sepsis by reviewing several recent findings. In addition, we have documented striking perspectives which not only rewrite the pathophysiology, but also modernize our understanding for developing novel therapeutics against sepsis. PMID:25412304

  11. Searle's"Dualism Revisited"

    SciTech Connect

    P., Henry

    2008-11-20

    A recent article in which John Searle claims to refute dualism is examined from a scientific perspective. John Searle begins his recent article 'Dualism Revisited' by stating his belief that the philosophical problem of consciousness has a scientific solution. He then claims to refute dualism. It is therefore appropriate to examine his arguments against dualism from a scientific perspective. Scientific physical theories contain two kinds of descriptions: (1) Descriptions of our empirical findings, expressed in an every-day language that allows us communicate to each other our sensory experiences pertaining to what we have done and what we have learned; and (2) Descriptions of a theoretical model, expressed in a mathematical language that allows us to communicate to each other certain ideas that exist in our mathematical imaginations, and that are believed to represent, within our streams of consciousness, certain aspects of reality that we deem to exist independently of their being perceived by any human observer. These two parts of our scientific description correspond to the two aspects of our general contemporary dualistic understanding of the total reality in which we are imbedded, namely the empirical-mental aspect and the theoretical-physical aspect. The duality question is whether this general dualistic understanding of ourselves should be regarded as false in some important philosophical or scientific sense.

  12. Sevelamer revisited: pleiotropic effects on endothelial and cardiovascular risk factors in chronic kidney disease and end-stage renal disease

    PubMed Central

    2013-01-01

    Endothelial dysfunction underlies multiple cardiovascular consequences of chronic kidney disease (CKD) and antecedent diabetes or hypertension. Endothelial insults in CKD or end-stage renal disease (ESRD) patients include uremic toxins, serum uric acid, hyperphosphatemia, reactive oxygen species, and advanced glycation endproducts (AGEs). Sevelamer carbonate, a calcium-free intestinally nonabsorbed polymer, is approved for hyperphosphatemic dialysis patients in the US and hyperphosphatemic stage 3–5 CKD patients in many other countries. Sevelamer has been observed investigationally to reduce absorption of AGEs, bacterial toxins, and bile acids, suggesting that it may reduce inflammatory, oxidative, and atherogenic stimuli in addition to its on-label action of lowering serum phosphate. Some studies also suggest that noncalcium binders may contribute less to vascular calcification than calcium-based binders. Exploratory sevelamer carbonate use in patients with stages 2–4 diabetic CKD significantly reduced HbA1c, AGEs, fibroblast growth factor (FGF)-23, and total and low-density lipoprotein (LDL) cholesterol versus calcium carbonate; inflammatory markers decreased and defenses against AGEs increased. Sevelamer has also been observed to reduce circulating FGF-23, potentially reducing risk of left ventricular hypertrophy. Sevelamer but not calcium-based binders in exploratory studies increases flow-mediated vasodilation, a marker of improved endothelial function, in patients with CKD. In contrast, lanthanum carbonate and calcium carbonate effects on FMV did not differ in hemodialysis recipients. The recent INDEPENDENT-CKD randomized trial compared sevelamer versus calcium carbonate in predialysis CKD patients (investigational in the US, on-label in European participants); sevelamer reduced 36-month mortality and the composite endpoint of mortality or dialysis inception. Similarly, INDEPENDENT-HD in incident dialysis patients showed improved survival with 24 months

  13. Reactive and internal contributions to the thermal conductivity of local thermodynamic equilibrium nitrogen plasma: The effect of electronically excited states

    NASA Astrophysics Data System (ADS)

    Bruno, D.; Colonna, G.; Laricchiuta, A.; Capitelli, M.

    2012-12-01

    Internal and reactive contributions to the thermal conductivity of a local thermodynamic equilibrium nitrogen plasma have been calculated using the Chapman-Enskog method. Low-lying (LL) electronically excited states (i.e., states with the same principal quantum number of the ground state) and high-lying (HL) ones (i.e., states with principal quantum number n > 2) have been considered. Several models have been developed, the most accurate being a model that treats the LL states as separate species while disregarding the presence of HL states, on account of their enormous transport cross sections.

  14. Atomistic Calculations of the Effect of Minor Actinides on Thermodynamic and Kinetic Properties of UO{sub 2{+-}x}

    SciTech Connect

    Deo, Chaitanya; Adnersson, Davis; Battaile, Corbett; uberuaga, Blas

    2012-10-30

    The team will examine how the incorporation of actinide species important for mixed oxide (MOX) and other advanced fuel designs impacts thermodynamic quantities of the host UO{sub 2} nuclear fuel and how Pu, Np, Cm and Am influence oxygen mobility. In many cases, the experimental data is either insufficient or missing. For example, in the case of pure NpO2, there is essentially no experimental data on the hyperstoichiometric form it is not even known if hyperstoichiometry NpO{sub 2{+-}x} is stable. The team will employ atomistic modeling tools to calculate these quantities

  15. Reactive and internal contributions to the thermal conductivity of local thermodynamic equilibrium nitrogen plasma: The effect of electronically excited states

    SciTech Connect

    Bruno, D.; Colonna, G.; Laricchiuta, A.; Capitelli, M.

    2012-12-15

    Internal and reactive contributions to the thermal conductivity of a local thermodynamic equilibrium nitrogen plasma have been calculated using the Chapman-Enskog method. Low-lying (LL) electronically excited states (i.e., states with the same principal quantum number of the ground state) and high-lying (HL) ones (i.e., states with principal quantum number n> 2) have been considered. Several models have been developed, the most accurate being a model that treats the LL states as separate species while disregarding the presence of HL states, on account of their enormous transport cross sections.

  16. Chlorination pattern effect on thermodynamic parameters and environmental degradability for C10-SCCPs: Quantum chemical calculation based on virtual combinational library.

    PubMed

    Sun, Yuzhen; Pan, Wenxiao; Lin, Yuan; Fu, Jianjie; Zhang, Aiqian

    2016-01-01

    Short-chain chlorinated paraffins (SCCPs) are still controversial candidates for inclusion in the Stockholm Convention. The inherent mixture nature of SCCPs makes it rather difficult to explore their environmental behaviors. A virtual molecule library of 42,720 C10-SCCP congeners covering the full structure spectrum was constructed. We explored the structural effects on the thermodynamic parameters and environmental degradability of C10-SCCPs through semi-empirical quantum chemical calculations. The thermodynamic properties were acquired using the AM1 method, and frontier molecular orbital analysis was carried out to obtain the EHOMO, ELUMO and ELUMO-EHOMO for degradability exploration at the same level. The influence of the chlorination degree (NCl) on the relative stability and environmental degradation was elucidated. A novel structural descriptor, μ, was proposed to measure the dispersion of the chlorine atoms within a molecule. There were significant correlations between thermodynamic values and NCl, while the reported NCl-dependent pollution profile of C10-SCCPs in environmental samples was basically consistent with the predicted order of formation stability of C10-SCCP congeners. In addition, isomers with large μ showed higher relative stability than those with small μ. This could be further verified by the relationship between μ and the reactivity of nucleophilic substitution and OH attack respectively. The C10-SCCP congeners with less Cl substitution and lower dispersion degree are susceptible to environmental degradation via nucleophilic substitution and hydroxyl radical attack, while direct photolysis of C10-SCCP congeners cannot readily occur due to the large ELUMO-EHOMO values. The chlorination effect and the conclusions were further checked with appropriate density functional theory (DFT) calculations. PMID:26899657

  17. Aptitude-treatment interactions revisited: effect of metacognitive intervention on subtypes of written expression in elementary school students.

    PubMed

    Hooper, Stephen R; Wakely, Melissa B; de Kruif, Renee E L; Swartz, Carl W

    2006-01-01

    We examined the effectiveness of a metacognitive intervention for written language performance, based on the Hayes model of written expression, for 73 fourth-grade (n = 38) and fifth-grade (n = 35) students. The intervention consisted of twenty 45-min writing lessons designed to improve their awareness of writing as a problem-solving process. Each of the lessons addressed some aspect of planning, translating, and reflecting on written products; their self-regulation of these processes; and actual writing practice. All instruction was conducted in intact classrooms. Prior to the intervention, all students received a battery of neurocognitive tests measuring executive functions, attention, and language. In addition, preintervention writing samples were obtained and analyzed holistically and for errors in syntax, semantics, and spelling. Following the intervention, the writing tasks were readministered and cluster analysis of the neurocognitive data was conducted. Cluster analytic procedures yielded 7 reliable clusters: 4 normal variants, 1 Problem Solving weakness, 1 Problem Solving Language weaknesses, and 1 Problem Solving strength. The response to the single treatment by these various subtypes revealed positive but modest findings. Significant group differences were noted for improvement in syntax errors and spelling, with only spelling showing differential improvement for the Problem Solving Language subtype. In addition, there was a marginally significant group effect for holistic ratings. These findings provide initial evidence that Writing Aptitude (subtype) x Single Treatment interactions exist in writing, but further research is needed with other classification schemes and interventions. PMID:16390295

  18. 42 CFR 488.30 - Revisit user fee for revisit surveys.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 5 2012-10-01 2012-10-01 false Revisit user fee for revisit surveys. 488.30 Section 488.30 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES General Provisions § 488.30 Revisit user fee...

  19. Thermodynamics and holography of tachyon cosmology

    NASA Astrophysics Data System (ADS)

    Farajollahi, H.; Ravanpak, A.; Abolghasemi, M.

    2013-02-01

    Recently, we have investigated the dynamics of the universe in tachyon cosmology with non-minimal coupling to matter (Farajollahi et al. in Mod Phys Lett A 26(15):1125-1135, 2011; Phys Lett B 711(3-4)15:225-231,2012; Phys Rev D 83:124042, 2011; JCAP 10:014, 20112011; JCAP 05:017, 2011). In particular, for the interacting holographic dark energy (IHDE), the model is studied in Farajollahi et al. (Astrophys Space Sci 336(2):461-467, 2011). In the current work, a significant observational program has been conducted to unveil the model's thermodynamic properties. Our result shows that the IHDE version of our model better fits the observational data than Λ CDM model. The first and generalized second thermodynamics laws for the universe enveloped by cosmological apparent and event horizon are revisited. From the results, both first and generalized second laws, constrained by the observational data, are satisfied on cosmological apparent horizon.In addition, the total entropy is verified with the observation only if the horizon of the universe is taken as apparent horizon. Then, due to validity of generalized second law, the current cosmic acceleration is also predicted.

  20. Revisiting Antagonist Effects in Hypoglossal Nucleus: Brainstem Circuit for the State-Dependent Control of Hypoglossal Motoneurons: A Hypothesis

    PubMed Central

    Fenik, Victor B.

    2015-01-01

    We reassessed and provided new insights into the findings that were obtained in our previous experiments that employed the injections of combined adrenergic, serotonergic, GABAergic, and glycinergic antagonists into the hypoglossal nucleus in order to pharmacologically abolish the depression of hypoglossal nerve activity that occurred during carbachol-induced rapid-eye-movement (REM) sleep-like state in anesthetized rats. We concluded that noradrenergic disfacilitation is the major mechanism that is responsible for approximately 90% of the depression of hypoglossal motoneurons, whereas the remaining 10% can be explained by serotonergic mechanisms that have net inhibitory effect on hypoglossal nerve activity during REM sleep-like state. We hypothesized that both noradrenergic and serotonergic state-dependent mechanisms indirectly control hypoglossal motoneuron excitability during REM sleep; their activities are integrated and mediated to hypoglossal motoneurons by reticular formation neurons. In addition, we proposed a brainstem neural circuit that can explain the new findings. PMID:26648908

  1. A coarse-grained model for DNA-functionalized spherical colloids, revisited: effective pair potential from parallel replica simulations.

    PubMed

    Theodorakis, Panagiotis E; Dellago, Christoph; Kahl, Gerhard

    2013-01-14

    We discuss a coarse-grained model recently proposed by Starr and Sciortino [J. Phys.: Condens. Matter 18, L347 (2006)] for spherical particles functionalized with short single DNA strands. The model incorporates two key aspects of DNA hybridization, i.e., the specificity of binding between DNA bases and the strong directionality of hydrogen bonds. Here, we calculate the effective potential between two DNA-functionalized particles of equal size using a parallel replica protocol. We find that the transition from bonded to unbonded configurations takes place at considerably lower temperatures compared to those that were originally predicted using standard simulations in the canonical ensemble. We put particular focus on DNA-decorations of tetrahedral and octahedral symmetry, as they are promising candidates for the self-assembly into a single-component diamond structure. Increasing colloid size hinders hybridization of the DNA strands, in agreement with experimental findings. PMID:23320725

  2. The great Indian haze revisited: aerosol distribution effects on microphysical and optical properties of warm clouds over peninsular India

    NASA Astrophysics Data System (ADS)

    Ghanti, R.; Ghosh, S.

    2010-03-01

    The Indian subcontinent is undergoing a phase of rapid urbanisation. Inevitable fallout of this process is a concomitant increase in air pollution much of which can be attributed to the infamous great Indian haze phenomena. One observes that the aerosol size distributions vary considerably along the Bay of Bengal (BOB), Arabian Sea (AS) and the Indian Ocean (IO), although, the dynamical attributes are very similar, particularly over the BOB and the AS during this season. Unlike major European studies (e.g. Aerosol Characterization Experiment-2, Ghosh et al., 2005), there are no cloud microphysical modelling studies to complement these observational results for the Indian sub-continent. Ours is the first modelling study over this important region where a time-tested model (O'Dowd et al., 1999a; Ghosh et al., 2007; Rap et al., 2009) is used to obtain cloud microphysical and optical properties from observed aerosol size distributions. Un-activated aerosol particles and very small cloud droplets have to be treated specially to account for non-ideal effects-our model does this effectively yielding realistic estimate of cloud droplet number concentrations (Nc). Empirical relationships linking aerosol concentration to (Nc) yield a disproportionately higher Nc suggesting that such empirical formulations should be used with caution. Our modelling study reveals that the cloud's microphysical and optical properties are very similar along the AS and the BOB despite them having disparate dry aerosol spectral distributions. This is non-intuitive, as one would expect changes in microphysical development with widely different aerosol distributions. There is some increase in cloud droplet numbers with increased haze concentrations but much less than a simple proportion would indicate.

  3. Effect of pH and monovalent cations on the Raman spectrum of water: Basics revisited and application to measure concentration gradients at water/solid interface in Si3N4 biomaterial

    NASA Astrophysics Data System (ADS)

    Pezzotti, Giuseppe; Puppulin, Leonardo; La Rosa, Angelo; Boffelli, Marco; Zhu, Wenliang; McEntire, Bryan J.; Hosogi, Shigekuni; Nakahari, Takashi; Marunaka, Yoshinori

    2015-12-01

    The effect of hydrogen carbonate (HCO3-) and cations (Na+, K+) solvated in water were revisited according to high spectrally resolved Raman measurements. Water solutions with different bicarbonate concentrations or added with increasing amounts of monovalent cations were examined with respect to their Raman spectra both in the bulk state and at the solid/liquid interface with a silicon nitride (Si3N4) bioceramic. Spectroscopic calibrations confirmed that the Raman emission from OH-stretching in water is sensitive to molarity variations (in the order of tens of mM). The concentration gradient developed at the solid/liquid interface in cation-added solutions interacting with a Si3N4 surface was measured and found to be peculiar to individual cations. Local variation in pH was detected in ionic solutions interacting with Si3N4 samples, which might represent a useful property for Si3N4 in a number of biomedical applications.

  4. Hierarchical structure of the energy landscape of proteins revisited by time series analysis. II. Investigation of explicit solvent effects

    NASA Astrophysics Data System (ADS)

    Alakent, Burak; Camurdan, Mehmet C.; Doruker, Pemra

    2005-10-01

    Time series analysis tools are employed on the principal modes obtained from the Cα trajectories from two independent molecular-dynamics simulations of α-amylase inhibitor (tendamistat). Fluctuations inside an energy minimum (intraminimum motions), transitions between minima (interminimum motions), and relaxations in different hierarchical energy levels are investigated and compared with those encountered in vacuum by using different sampling window sizes and intervals. The low-frequency low-indexed mode relationship, established in vacuum, is also encountered in water, which shows the reliability of the important dynamics information offered by principal components analysis in water. It has been shown that examining a short data collection period (100ps) may result in a high population of overdamped modes, while some of the low-frequency oscillations (<10cm-1) can be captured in water by using a longer data collection period (1200ps). Simultaneous analysis of short and long sampling window sizes gives the following picture of the effect of water on protein dynamics. Water makes the protein lose its memory: future conformations are less dependent on previous conformations due to the lowering of energy barriers in hierarchical levels of the energy landscape. In short-time dynamics (<10ps), damping factors extracted from time series model parameters are lowered. For tendamistat, the friction coefficient in the Langevin equation is found to be around 40-60cm-1 for the low-indexed modes, compatible with literature. The fact that water has increased the friction and that on the other hand has lubrication effect at first sight contradicts. However, this comes about because water enhances the transitions between minima and forces the protein to reduce its already inherent inability to maintain oscillations observed in vacuum. Some of the frequencies lower than 10cm-1 are found to be overdamped, while those higher than 20cm-1 are slightly increased. As for the long

  5. Cultural Warping of Childbirth, Revisited

    PubMed Central

    Budin, Wendy C.

    2007-01-01

    In this column, the editor of The Journal of Perinatal Education revisits Doris Haire's classic 1972 article, “The Cultural Warping of Childbirth,” and describes the birth culture of today. The editor also describes the contents of this issue, which offer a broad range of resources, research, and inspiration for childbirth educators in their efforts to promote normal birth.

  6. Erratum: Interstellar Abundance Standards Revisited

    NASA Astrophysics Data System (ADS)

    Sofia, U. J.; Meyer, D. M.

    2001-09-01

    In the Letter ``Interstellar Abundance Standards Revisited'' by U. J. Sofia and D. M. Meyer (ApJ, 554, L221 [2001]), Table 2 and its footnotes contain several typographical errors. The corrected table is shown below. We note that the solar reference standard now implies a positive abundance of nitrogen in halo dust.

  7. The "Mushroom Cloud" Demonstration Revisited

    ERIC Educational Resources Information Center

    Panzarasa, Guido; Sparnacci, Katia

    2013-01-01

    A revisitation of the classical "mushroom cloud" demonstration is described. Instead of aniline and benzoyl peroxide, the proposed reaction involves household chemicals such as alpha-pinene (turpentine oil) and trichloroisocyanuric acid ("Trichlor") giving an impressive demonstration of oxidation and combustion reactions that…

  8. Positronium formation and annihilation in liquid crystalline smectic-E phase revisited

    NASA Astrophysics Data System (ADS)

    Dryzek, E.; Juszyńska-Gałazka, E.

    2016-02-01

    The results of the positron lifetime measurements of the quenched smectic-E (Sm-E ) phase of 4-butyl-4'-isothiocyano-1,1'-biphenyl (4TCB) are revisited. The sites of positronium formation and annihilation, according to the model with nanosegregated layered structure of the Sm-E phase and molten state of alkyl chains of molecules, are identified in the sublayer containing alkyl chains of molecules. The possibility of vitrification of the Sm-E phase for 4TCB consisting in freezing of the alkyl chain motions is considered as a cause of the thermally activated creation of sites where o -Ps is formed and annihilates in the quenched Sm-E phase. The description of the temperature dependence of ortho-positronium intensity is performed using the glass transition model which assumes that the molecules occupy two thermodynamic states: solidlike or liquidlike regarding mobility of their alkyl chains. The equilibrium temperature between solidlike and liquidlike domains of the model obtained from positron lifetime measurements coincides with the exothermic effect in the temperature dependence of the heat capacity.

  9. Black hole thermodynamics in MOdified Gravity (MOG)

    NASA Astrophysics Data System (ADS)

    Mureika, Jonas R.; Moffat, John W.; Faizal, Mir

    2016-06-01

    We analyze the thermodynamical properties of black holes in a modified theory of gravity, which was initially proposed to obtain correct dynamics of galaxies and galaxy clusters without dark matter. The thermodynamics of non-rotating and rotating black hole solutions resembles similar solutions in Einstein-Maxwell theory with the electric charge being replaced by a new mass dependent gravitational charge Q =√{ αGN } M. This new mass dependent charge modifies the effective Newtonian constant from GN to G =GN (1 + α), and this in turn critically affects the thermodynamics of the black holes. We also investigate the thermodynamics of regular solutions, and explore the limiting case when no horizons forms. So, it is possible that the modified gravity can lead to the absence of black hole horizons in our universe. Finally, we analyze corrections to the thermodynamics of a non-rotating black hole and obtain the usual logarithmic correction term.

  10. Atrazine and Methyl Viologen Effects on Chlorophyll-a Fluorescence Revisited-Implications in Photosystems Emission and Ecotoxicity Assessment.

    PubMed

    Iriel, Analia; Novo, Johanna M; Cordon, Gabriela B; Lagorio, María G

    2014-01-01

    In this work, we use the effect of herbicides that affect the photosynthetic chain at defined sites in the photosynthetic reaction steps to derive information about the fluorescence emission of photosystems. The interpretation of spectral data from treated and control plants, after correction for light reabsorption processes, allowed us to elucidate current controversies in the subject. Results were compatible with the fact that a nonnegligible Photosystem I contribution to chlorophyll fluorescence in plants at room temperature does exist. In another aspect, variable and nonvariable chlorophyll fluorescence were comparatively tested as bioindicators for detection of both herbicides in aquatic environment. Both methodologies were appropriate tools for this purpose. However, they showed better sensitivity for pollutants disconnecting Photosystem II-Photosystem I by blocking the electron transport between them as Atrazine. Specifically, changes in the (experimental and corrected by light reabsorption) red to far red fluorescence ratio, in the maximum photochemical quantum yield and in the quantum efficiency of Photosytem II for increasing concentrations of herbicides have been measured and compared. The most sensitive bioindicator for both herbicides was the quantum efficiency of Photosystem II. PMID:23869421

  11. The botanist effect revisited: plant species richness, county area, and human population size in the United States.

    PubMed

    Pautasso, Marco; McKinney, Michael L

    2007-10-01

    The "botanist effect" is thought to be the reason for higher plant species richness in areas where botanists are disproportionately present as an artefactual consequence of a more thorough sampling. We examined whether this was the case for U.S. counties. We collated the number of species of vascular plants, human population size, and the area of U.S. counties. Controlling for spatial autocorrelation and county area, plant species richness increased with human population size and density in counties with and without universities and/or botanical gardens, with no significant differences in the relation between the two subsets. This is consistent with previous findings and further evidence of a broad-scale positive correlation between species richness and human population presence, which has important consequences for the experience of nature by inhabitants of densely populated regions. Combined with the many reports of a negative correlation between the two variables at a local scale, the positive relation between plant species richness in U.S. counties and human population presence stresses the need for the conservation of seminatural areas in urbanized ecosystems and for the containment of urban and suburban sprawl. PMID:17883498

  12. Thermodynamics of the Earth

    NASA Astrophysics Data System (ADS)

    Stacey, Frank D.

    2010-04-01

    Applications of elementary thermodynamic principles to the dynamics of the Earth lead to robust, quantitative conclusions about the tectonic effects that arise from convection. The grand pattern of motion conveys deep heat to the surface, generating mechanical energy with a thermodynamic efficiency corresponding to that of a Carnot engine operating over the adiabatic temperature gradient between the heat source and sink. Referred to the total heat flux derived from the Earth's silicate mantle, the efficiency is 24% and the power generated, 7.7 × 1012 W, causes all the material deformation apparent as plate tectonics and the consequent geological processes. About 3.5% of this is released in seismic zones but little more than 0.2% as seismic waves. Even major earthquakes are only localized hiccups in this motion. Complications that arise from mineral phase transitions can be used to illuminate details of the motion. There are two superimposed patterns of convection, plate subduction and deep mantle plumes, driven by sources of buoyancy, negative and positive respectively, at the top and bottom of the mantle. The patterns of motion are controlled by the viscosity contrasts (>104 : 1) at these boundaries and are self-selected as the least dissipative mechanisms of heat transfer for convection in a body with very strong viscosity variation. Both are subjects of the thermodynamic efficiency argument. Convection also drives the motion in the fluid outer core that generates the geomagnetic field, although in that case there is an important energy contribution by compositional separation, as light solute is rejected by the solidifying inner core and mixed into the outer core, a process referred to as compositional convection. Uncertainty persists over the core energy balance because thermal conduction is a drain on core energy that has been a subject of diverse estimates, with attendant debate over the need for radiogenic heat in the core. The geophysical approach to

  13. Thermodynamics and combustion modeling

    NASA Technical Reports Server (NTRS)

    Zeleznik, Frank J.

    1986-01-01

    Modeling fluid phase phenomena blends the conservation equations of continuum mechanics with the property equations of thermodynamics. The thermodynamic contribution becomes especially important when the phenomena involve chemical reactions as they do in combustion systems. The successful study of combustion processes requires (1) the availability of accurate thermodynamic properties for both the reactants and the products of reaction and (2) the computational capabilities to use the properties. A discussion is given of some aspects of the problem of estimating accurate thermodynamic properties both for reactants and products of reaction. Also, some examples of the use of thermodynamic properties for modeling chemically reacting systems are presented. These examples include one-dimensional flow systems and the internal combustion engine.

  14. Thermodynamic Insight in the High-Pressure Behavior of UiO-66: Effect of Linker Defects and Linker Expansion

    PubMed Central

    2016-01-01

    In this Article, we present a molecular-level understanding of the experimentally observed loss of crystallinity in UiO-66-type metal–organic frameworks, including the pristine UiO-66 to -68 as well as defect-containing UiO-66 materials, under the influence of external pressure. This goal is achieved by constructing pressure-versus-volume profiles at finite temperatures using a thermodynamic approach relying on ab initio derived force fields. On the atomic level, the phenomenon is reflected in a sudden drop in the number of symmetry operators for the crystallographic unit cell because of the disordered displacement of the organic linkers with respect to the inorganic bricks. For the defect-containing samples, a reduced mechanical stability is observed, however, critically depending on the distribution of these defects throughout the material, hence demonstrating the importance of judiciously characterizing defects in these materials. PMID:27594765

  15. Thermodynamic power of non-Markovianity.

    PubMed

    Bylicka, Bogna; Tukiainen, Mikko; Chruściński, Dariusz; Piilo, Jyrki; Maniscalco, Sabrina

    2016-01-01

    The natural framework to discuss thermodynamics at the quantum level is the theory of open quantum systems. Memory effects arising from strong system-environment correlations may lead to information back-flow, that is non-Markovian behaviour. The relation between non-Markovianity and quantum thermodynamics has been until now largely unexplored. Here we show by means of Landauer's principle that memory effects control the amount of work extraction by erasure in presence of realistic environments. PMID:27323947

  16. Thermodynamic power of non-Markovianity

    PubMed Central

    Bylicka, Bogna; Tukiainen, Mikko; Chruściński, Dariusz; Piilo, Jyrki; Maniscalco, Sabrina

    2016-01-01

    The natural framework to discuss thermodynamics at the quantum level is the theory of open quantum systems. Memory effects arising from strong system-environment correlations may lead to information back-flow, that is non-Markovian behaviour. The relation between non-Markovianity and quantum thermodynamics has been until now largely unexplored. Here we show by means of Landauer’s principle that memory effects control the amount of work extraction by erasure in presence of realistic environments. PMID:27323947

  17. Thermodynamic studies of the interaction of alpha-chymotrypsin with water. II. Statistical analyses of the enthalpy-entropy compensation effect.

    PubMed

    Lüscher, M; Rüegg, M; Schindler, P

    1978-09-26

    Differential enthalpies (deltaH) and entropies (deltaS) of the interaction of water with a high and low temperature conformer of alpha-chymotrypsin were determined previously by multitemperature sorption measurements. The changes in (deltaH) and (deltaS) with water content of the protein were found to show a pronounced compensation pattern. It is known that van 't Hoff data may exhibit enthalpy-entropy compensation, which is entirely due to statistical error propagation. To discriminate between artifactual and significant compensation, the experimental results are analyzed by statistical methods. The results of two different statistical analyses show that a linear, chemically caused compensation effect can be established for the interaction of water with both chymotrypsin conformers. The compensation temperature beta = deltaH/deltaS was found to be 433 +/- 22 K. The compensation effect is detectable only in the water content range above the monolayer volume (upsilonm), computed by the Brunauer, Emmett and Teller equation. This result is discussed in terms of a monolayer hydration mechanism, formulated on the basis of previous thermodynamic results: The interaction of the first water monolayer with the charged and polar surface area of the dry protein, largely stabilizes its tertiary structure. Further water addition then occurs to a practically invariable protein surface. According to this mechanism (which ensures a maximum of conformational stability with a minimum of hydration water), large conformational changes can be expected to occur mainly in the monolayer water content range. This expectation is confirmed by extra-thermodynamic data (infrared and X-ray measurements). The thermodynamic quantities of the sorption process are thus governed by conformational effects below upsilonm. Above the monolayer water content range, however, the water binding process per se strongly predominates. The deltaH/deltaS compensation effect established for this water content

  18. The Pharmacopsychometric Triangle to Illustrate the Effectiveness of T-PEMF Concomitant with Antidepressants in Treatment Resistant Patients: A Double-Blind, Randomised, Sham-Controlled Trial Revisited with Focus on the Patient-Reported Outcomes

    PubMed Central

    Bech, P.; Gefke, M.; Lunde, M.; Lauritzen, L.; Martiny, K.

    2011-01-01

    Background. Our T-PEMF trial has been revisited with focus on the pharmacopsychometric triangle in which effect size is used when comparing wanted versus unwanted clinical effects and quality of life as outcomes. In this analysis, we have especially focused on the self-reported HAM-D6. Methods. The antidepressive medication which the patients were resistant to was kept unchanged during the five weeks of active versus sham T-PEMF. Results. In total 21, patients received active T-PEMF, and 19 patients received sham T-PEMF. The effect size was 1.02 and 0.90, respectively, on HAM-D6 and HAM-D6-S. Concerning side effects, the active T-PEMF reduced the baseline score on concentration problems with an effect size of 0.44 while inducing more autonomic symptoms than sham T-PEMF with an effect size of −0.41. The advantage of active over sham T-PEMF obtained an effect size of 0.48. Conclusion. Active T-PEMF was found superior to sham T-PEMF within the pharmacopsychometric triangle with a clinically significant effect size level above 0.40. PMID:21738869

  19. Effect of Ni and Pd Addition on Mechanical, Thermodynamic, and Electronic Properties of AuSn4-Based Intermetallics: A Density Functional Investigation

    NASA Astrophysics Data System (ADS)

    Tian, Yali; Zhou, Wei; Wu, Ping

    2016-05-01

    The effects of Ni and Pd addition on the mechanical, thermodynamic, and electronic properties of AuSn4-based intermetallic compounds (IMCs) have been investigated by first-principles calculations to reveal the essence of Au embrittlement. Three kinds of doped (namely Ni-doped, Pd-doped, and Ni/Pd-codoped) IMCs are considered in this work. The polycrystalline elastic properties are deduced from single-crystal elastic constants. It is found that the doped systems together with nondoped AuSn4 are all ductile phases. For Ni-doped AuSn4, the modulus, hardness, brittleness, Debye temperature, and minimum thermal conductivity increase with the Ni fraction, but this is not the case for the Pd-doped material, since Au0.75Pd0.25Sn4 is the more brittle phase. For Au0.5Pd0.25Ni0.25Sn4, the mechanical, thermodynamic, and electronic properties are similar to those of Au0.5Pd0.5Sn4.

  20. Thermodynamic effects of calcium and iron oxides on crystal phase formation in synthetic gasifier slags containing from 0 to 27wt.% V2O3

    DOE PAGESBeta

    Nakano, Jinichiro; Duchesne, Marc; Bennett, James; Kwong, Kyei -Sing; Nakano, Anna; Hughes, Robin

    2014-11-15

    Thermodynamic phase equilibria in synthetic slags (Al2O3–CaO–FeO–SiO2–V2O3) were investigated with 0–27 wt.% vanadium oxide corresponding to industrial coal–petroleum coke (petcoke) feedstock blends in a simulated gasifier environment. Samples encompassing coal–petcoke mixed slag compositions were equilibrated at 1500 °C in a 64 vol.% CO/36 vol.% CO2 atmosphere (Po2 ≈ 10–8 atm at 1500 °C) for 72 h, followed by rapid water quench, then analyzed by inductively coupled plasma optical emission spectrometry, X-ray diffractometry, and scanning electron microscopy with wavelength dispersive spectroscopy. With increasing CaO content, FeO content, or both; the slag homogeneity region expanded and a composition range exhibiting crystals wasmore » reduced. The mullite (Al6Si2O13) crystalline phase was not present in the slags above 9 wt.% FeO while the karelianite (V2O3) crystalline phase was always present in compositions studied if a sufficient amount of vanadium existed in the slag. Furthermore, based on the present experimental equilibrium evaluation, a set of isothermal phase diagrams showing effects of CaO and FeO on thermodynamic phase stabilities in the vanadium-bearing slags is proposed. Some uses of the diagrams for potential industrial practice are discussed.« less

  1. Modeling Dense Granular Flow: A Nonequilibrium Thermodynamics Approach and Implications of Grain Fragmentation, Acoustic Effects and Interparticle Friction on Dynamic Friction

    NASA Astrophysics Data System (ADS)

    Lieou, Charles Ka Cheong

    Granular flow rheology has broad implications on earth science and industrial processing of raw materials. This dissertation is an overview of our effort to understand dense granular flow and the influence of microscopic, grain-scale processes on dynamic friction from basic principles of nonequilibrium thermodynamics. First, I will provide a short introduction to the Shear-Transformation-Zone (STZ) theory of plastic deformation and the underlying theoretical framework of nonequilibrium thermodynamics, and use the Haxton-Liu hard-sphere simulations as a testing ground for the theory. Next, I will briefly discuss grain fragmentation and examine its implication on shear weakening and shear localization; in so doing, we account for the formation and persistence of shear bands of fragmented particles. Finally, I propose a way to incorporate acoustic effects, particle angularity, and interparticle friction into the STZ model. We show good agreement with laboratory experiments on angular sand particles that indicate shear-induced acoustic compaction at intermediate strain rates. We show in addition that friction between particles is essential in producing stick-slip instabilities, which can be controlled by the confining pressure and external vibrations.

  2. Effect of Ni and Pd Addition on Mechanical, Thermodynamic, and Electronic Properties of AuSn4-Based Intermetallics: A Density Functional Investigation

    NASA Astrophysics Data System (ADS)

    Tian, Yali; Zhou, Wei; Wu, Ping

    2016-08-01

    The effects of Ni and Pd addition on the mechanical, thermodynamic, and electronic properties of AuSn4-based intermetallic compounds (IMCs) have been investigated by first-principles calculations to reveal the essence of Au embrittlement. Three kinds of doped (namely Ni-doped, Pd-doped, and Ni/Pd-codoped) IMCs are considered in this work. The polycrystalline elastic properties are deduced from single-crystal elastic constants. It is found that the doped systems together with nondoped AuSn4 are all ductile phases. For Ni-doped AuSn4, the modulus, hardness, brittleness, Debye temperature, and minimum thermal conductivity increase with the Ni fraction, but this is not the case for the Pd-doped material, since Au0.75Pd0.25Sn4 is the more brittle phase. For Au0.5Pd0.25Ni0.25Sn4, the mechanical, thermodynamic, and electronic properties are similar to those of Au0.5Pd0.5Sn4.

  3. Compounding effects of fluid confinement and surface strain on the wet–dry transition, thermodynamic response, and dynamics of water–graphene systems

    DOE PAGESBeta

    Chialvo, Ariel A.; Vlcek, Lukas; Cummings, Peter T.

    2015-01-01

    We studied the link between the water-mediated (tensile or compressive) strain-driven hydration free energy changes in the association process involving finite-size graphene surfaces, the resulting water-graphene interfacial behavior, and the combined effect of surface strain and fluid confinement on the thermodynamic response functions and the dynamics of water. In this study, we found that either small surface corrugation (compressive strain) or surface stretching (tensile strain) is able to enhance significantly the water-graphene hydrophobicity relative to that of the unstrained surface, an effect that exacerbates the confinement impact on the isothermal compressibility and isobaric thermal expansivity of confined water, as wellmore » as on the slowing down of its dynamics that gives rise to anomalous diffusivity.« less

  4. Compounding effects of fluid confinement and surface strain on the wet–dry transition, thermodynamic response, and dynamics of water–graphene systems

    SciTech Connect

    Chialvo, Ariel A.; Vlcek, Lukas; Cummings, Peter T.

    2015-01-01

    We studied the link between the water-mediated (tensile or compressive) strain-driven hydration free energy changes in the association process involving finite-size graphene surfaces, the resulting water-graphene interfacial behavior, and the combined effect of surface strain and fluid confinement on the thermodynamic response functions and the dynamics of water. In this study, we found that either small surface corrugation (compressive strain) or surface stretching (tensile strain) is able to enhance significantly the water-graphene hydrophobicity relative to that of the unstrained surface, an effect that exacerbates the confinement impact on the isothermal compressibility and isobaric thermal expansivity of confined water, as well as on the slowing down of its dynamics that gives rise to anomalous diffusivity.

  5. Compounding effects of fluid confinement and surface strain on the wet-dry transition, thermodynamic response, and dynamics of water-graphene systems

    NASA Astrophysics Data System (ADS)

    Chialvo, Ariel A.; Vlcek, Lukas; Cummings, Peter T.

    2015-05-01

    We studied the link between the water-mediated (tensile or compressive) strain-driven hydration free energy changes in the association process involving finite-size graphene surfaces, the resulting water-graphene interfacial behaviour, and the combined effect of surface strain and fluid confinement on the thermodynamic response functions and the dynamics of water. We found that either small surface corrugation (compressive strain) or surface stretching (tensile strain) is able to enhance significantly the water-graphene hydrophobicity relative to that of the unstrained surface, an effect that exacerbates the confinement impact on the isothermal compressibility and isobaric thermal expansivity of confined water, as well as on the slowdown of its dynamics that gives rise to anomalous diffusivity.

  6. Linear stability of a vortex ring revisited

    NASA Astrophysics Data System (ADS)

    Fukumoto, Yasuhide; Hattori, Yuji

    We revisit the stability of an elliptically strained vortex and a thin axisymmetric vortex ring, embedded in an inviscid incompressible fluid, to three-dimensional disturbances of infinitesimal amplitude. The results of Tsai & Widnall (1976) for an elliptically strained vortex are simplified by providing an explicit expression for the disturbance flow field. A direct relation is established with the elliptical instability. For Kelvin's vortex ring, the primary perturbation to the Rankine vortex is a dipole field. We show that the dipole field causes a parametric resonance instability between axisymmetric and bending waves at intersection points of the dispersion curves. It is found that the dipole effect predominates over the straining effect for a very thin core. The mechanism is attributable to stretching of the disturbance vortex lines in the toroidal direction.

  7. Stories to Make Thermodynamics and Related Subjects More Palatable

    NASA Astrophysics Data System (ADS)

    Bartell, Lawrence S.

    2001-08-01

    A collection of vignettes either recounting the personalities of some of the architects of thermodynamics or noting steps and missteps in the development of thermodynamics and the kinetic theory is combined with a set of stories illustrating thermodynamic principles. These offerings turned out to be much more easily remembered by students and were more effective in conveying certain points than a direct, unadorned exposition of thermodynamic laws and applications. For one thing, the stories kept the students awake and receptive to ideas. Students had invariably entered the class having heard horror stories about how tedious and impossibly difficult thermodynamics courses are.

  8. The Transverse Momentum Dependent Statistical Parton Distributions Revisited

    NASA Astrophysics Data System (ADS)

    Bourrely, Claude; Buccella, Franco; Soffer, Jacques

    2013-04-01

    The extension of the statistical parton distributions to include their transverse momentum dependence (TMD) is revisited by considering that the proton target has a finite longitudinal momentum. The TMD will be generated by means of a transverse energy sum rule. The new results are mainly relevant for electron-proton inelastic collisions in the low Q2 region. We take into account the effects of the Melosh-Wigner rotation for the helicity distributions.

  9. Indoor air and human health revisited: A recent IAQ symposium

    SciTech Connect

    Gammage, R.B.

    1994-12-31

    Indoor Air and Human Health Revisited was a speciality symposium examining the scientific underpinnings of sensory and sensitivity effects, allergy and respiratory disease, neurotoxicity and cancer. An organizing committee selected four persons to chain the sessions and invite experts to give state-of-the-art presentations that will be published as a book. A summary of the presentations is made and some critical issues identified.

  10. Embedded-atom-method effective-pair-interaction study of the structural and thermodynamic properties of Cu-Ni, Cu-Ag, and Au-Ni solid solutions

    SciTech Connect

    Asta, M.; Foiles, S.M.

    1996-02-01

    The structural and thermodynamic properties of Cu-Ni, Cu-Ag, and Au-Ni solid solutions have been studied using a computational approach which combines an embedded-atom-method (EAM) description of alloy energetics with a second-order-expansion (SOE) treatment of compositional and displacive disorder. It is discussed in detail how the SOE approach allows the EAM expression for the energy of a substitutional alloy to be cast in the form of a generalized lattice-gas Hamiltonian containing effective pair interactions with arbitrary range. Furthermore, we show how the SOE-EAM method can be combined with either mean-field or Monte Carlo statistical mechanics techniques in order to calculate short-range-order (SRO) parameters, average nearest-neighbor bond lengths, and alloy thermodynamic properties which include contributions from static displacive relaxations and dynamic atomic vibrations. We demonstrate that the contributions to alloy heats of mixing arising from displacive relaxations can be sizeable, and that the neglect of these terms can lead to large overestimations of calculated phase-transition temperatures. The effects of vibrational free-energy contributions on the results of composition-temperature phase diagram calculations are estimated to be relatively small for the phase-separating alloy systems considered in this study. It is shown that within the SOE approach displacive effects can act only to displace the peak in the Fourier-transformed SRO parameter away from Brillouin-zone-boundary special points and towards the origin. Consistent with this result, we show that the unusual SRO observed in diffuse scattering experiments for Au-Ni solid solutions can be understood as arising from a competition between chemical and displacive driving forces which favor ordering and clustering, respectively. {copyright} {ital 1996 The American Physical Society.}

  11. First Grade Writers Revisit Their Work

    ERIC Educational Resources Information Center

    Hansen, Jane A.

    2007-01-01

    In this article, the author focuses on first grade readers and writers who revisit their work and describes what first-graders do when they revisit their writing about science and literature and review collections of their work. The first-graders discussed here are in Elaine O'Connor's classroom at Clark Elementary School in Charlottesville. In a…

  12. Effect of dispersive long-range corrections to the pressure tensor: The vapour-liquid interfacial properties of the Lennard-Jones system revisited

    SciTech Connect

    Martínez-Ruiz, F. J.; Blas, F. J.; Mendiboure, B.; Moreno-Ventas Bravo, A. I.

    2014-11-14

    We propose an extension of the improved version of the inhomogeneous long-range corrections of Janeček [J. Phys. Chem. B 110, 6264–6269 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] to account for the intermolecular potential energy of spherical, rigid, and flexible molecular systems, to deal with the contributions to the microscopic components of the pressure tensor due to the dispersive long-range corrections. We have performed Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of spherical Lennard-Jones molecules with different cutoff distances, r{sub c} = 2.5, 3, 4, and 5σ. In addition, we have also considered cutoff distances r{sub c} = 2.5 and 3σ in combination with the inhomogeneous long-range corrections proposed in this work. The normal and tangential microscopic components of the pressure tensor are obtained using the mechanical or virial route in combination with the recipe of Irving and Kirkwood, while the macroscopic components are calculated using the Volume Perturbation thermodynamic route proposed by de Miguel and Jackson [J. Chem. Phys. 125, 164109 (2006)]. The vapour-liquid interfacial tension is evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the Test-Area methodology. In addition to the pressure tensor and the surface tension, we also obtain density profiles, coexistence densities, vapour pressure, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the cutoff distance and the long-range corrections on these properties. According to our results, the main effect of increasing the cutoff distance (at fixed temperature) is to sharpen the vapour-liquid interface, to decrease the vapour pressure, and to increase the width of the biphasic coexistence region. As a result, the interfacial

  13. Effect of dispersive long-range corrections to the pressure tensor: The vapour-liquid interfacial properties of the Lennard-Jones system revisited

    NASA Astrophysics Data System (ADS)

    Martínez-Ruiz, F. J.; Blas, F. J.; Mendiboure, B.; Moreno-Ventas Bravo, A. I.

    2014-11-01

    We propose an extension of the improved version of the inhomogeneous long-range corrections of Janeček [J. Phys. Chem. B 110, 6264-6269 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] to account for the intermolecular potential energy of spherical, rigid, and flexible molecular systems, to deal with the contributions to the microscopic components of the pressure tensor due to the dispersive long-range corrections. We have performed Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of spherical Lennard-Jones molecules with different cutoff distances, rc = 2.5, 3, 4, and 5σ. In addition, we have also considered cutoff distances rc = 2.5 and 3σ in combination with the inhomogeneous long-range corrections proposed in this work. The normal and tangential microscopic components of the pressure tensor are obtained using the mechanical or virial route in combination with the recipe of Irving and Kirkwood, while the macroscopic components are calculated using the Volume Perturbation thermodynamic route proposed by de Miguel and Jackson [J. Chem. Phys. 125, 164109 (2006)]. The vapour-liquid interfacial tension is evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the Test-Area methodology. In addition to the pressure tensor and the surface tension, we also obtain density profiles, coexistence densities, vapour pressure, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the cutoff distance and the long-range corrections on these properties. According to our results, the main effect of increasing the cutoff distance (at fixed temperature) is to sharpen the vapour-liquid interface, to decrease the vapour pressure, and to increase the width of the biphasic coexistence region. As a result, the interfacial thickness

  14. Origin of Asymmetric Solvation Effects for Ions in Water and Organic Solvents Investigated Using Molecular Dynamics Simulations: The Swain Acity-Basity Scale Revisited.

    PubMed

    Reif, Maria M; Hünenberger, Philippe H

    2016-08-25

    absolute sense, the atomistic simulations playing the role of an extra-thermodynamic assumption, and is optimally compatible with the simulation results. Considering the 55 solvents in the Swain set, it is observed that a moderate basity (Σ between -0.9 and -0.3, related to electronic polarization) represents the baseline for most solvents, while a highly variable acity (Σ between 0.0 and 3.0, related to hydrogen-bond donor capacity modulated by inductive effects) represents a landmark of protic solvents. PMID:27173101

  15. Benjamin Franklin and Mesmerism, revisited.

    PubMed

    McConkey, Kevin M; Perry, Campbell

    2002-10-01

    The authors revisit and update their previous historiographical note (McConkey & Perry, 1985) on Benjamin Franklin's involvement with and investigation of animal magnetism or mesmerism. They incorporate more recent literature and offer additional comment about Franklin's role in and views about mesmerism. Franklin had a higher degree of personal involvement with and a more detailed opinion of mesmerism than has been previously appreciated. PMID:12362950

  16. Thermodynamic aspects of cholesterol effect on properties of phospholipid monolayers: Langmuir and Langmuir-Blodgett monolayer study.

    PubMed

    Jurak, Małgorzata

    2013-04-01

    Cholesterol is an important component of lipid rafts in mammalian cell membranes. Studies of phospholipid monolayers containing cholesterol provide insight into the role of cholesterol in regulating the properties of animal cells, raft stability, and organization. In this contribution, a study of the characteristics of binary Langmuir monolayers consisting of phospholipids, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 2-oleoyl-1-palmitoyl-sn-glycero-3-phosphocholine (POPC), 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1-glycerol) (DPPG), and cholesterol (Chol), was conducted on the basis of the surface pressure-area per molecule (π-A) isotherms. Analysis of the results obtained provided information on the mean molecular area, the excess Gibbs energy of mixing, and condensation in the monolayer. The mixed monolayers were also deposited onto the mica plates and investigated by the contact angle measurements of water, formamide, and diiodomethane. The contact angles allowed calculating surface free energy of the films from the van Oss et al. approach. It was found that cholesterol determines the molecular packing and ordering of the monolayers closely connected with the kind of phospholipid. This is reflected in the values of surface free energy of the model membranes. From the thermodynamic analysis of phospholipid/cholesterol/liquid interactions, one may draw conclusions about the most favorable composition (stoichiometry) of the binary film which is especially important in view of the lipid rafts formation. PMID:23470025

  17. Thermodynamics: A Stirling effort

    NASA Astrophysics Data System (ADS)

    Horowitz, Jordan M.; Parrondo, Juan M. R.

    2012-02-01

    The realization of a single-particle Stirling engine pushes thermodynamics into stochastic territory where fluctuations dominate, and points towards a better understanding of energy transduction at the microscale.

  18. Electrochemical thermodynamic measurement system

    DOEpatents

    Reynier, Yvan; Yazami, Rachid; Fultz, Brent T.

    2009-09-29

    The present invention provides systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and electrochemical energy storage and conversion systems. Systems and methods of the present invention are configured for simultaneously collecting a suite of measurements characterizing a plurality of interconnected electrochemical and thermodynamic parameters relating to the electrode reaction state of advancement, voltage and temperature. Enhanced sensitivity provided by the present methods and systems combined with measurement conditions that reflect thermodynamically stabilized electrode conditions allow very accurate measurement of thermodynamic parameters, including state functions such as the Gibbs free energy, enthalpy and entropy of electrode/electrochemical cell reactions, that enable prediction of important performance attributes of electrode materials and electrochemical systems, such as the energy, power density, current rate and the cycle life of an electrochemical cell.

  19. The Thermodynamics of Portfolios

    NASA Astrophysics Data System (ADS)

    Piotrowski, E. W.; Sladkowski, J.

    2001-02-01

    We propose a new method of valuation of portfolios and their respective investing strategies. To this end we define a canonical ensemble of portfolios that allows to use the formalism of thermodynamics.

  20. Thermodynamics and Frozen Foods.

    ERIC Educational Resources Information Center

    Kerr, William L.; Reid, David S.

    1993-01-01

    The heat content of a food at a given temperature can be described by the thermodynamic property of enthalpy. Presents a method to construct a simple calorimeter for measuring the enthalpy changes of different foods during freezing. (MDH)

  1. Effect of intramolecular Paternò-Büchi reaction on the thermodynamics and kinetics of nearly degenerate [3,3]-sigmatropic shift in fluxional polycycles.

    PubMed

    Valiulin, Roman A; Dressen, Donald G; Riggs, Jennifer R; Habte, Faven M; Kutateladze, Andrei G

    2009-05-01

    In reactions with weak dienophiles, cyclooctatetraene (COT) often yields 2:1 adducts possessing the fluxional bicyclo[5.1.0]octadiene moiety. They undergo fast, nearly degenerate Cope rearrangement with an activation barrier similar to that of the parent dihydrobullvalene. Irradiation to excite the carbonyl moiety induces an intramolecular Paterno-Buchi cyclization yielding endo-oxetanes and significantly changing the Cope-averaged NMR spectra. In this paper we examine the effect of skeletal distortion caused by intramolecular [2 + 2]-photoaddition on thermodynamics and the activation barrier of the [3,3]-sigmatropic tautomerism. Our finding is that such a distortion lifts the energetic degeneracy of the two valence tautomers, while not affecting the activation barrier. PMID:19344135

  2. Simple, chemoselective hydrogenation with thermodynamic stereocontrol.

    PubMed

    Iwasaki, Kotaro; Wan, Kanny K; Oppedisano, Alberto; Crossley, Steven W M; Shenvi, Ryan A

    2014-01-29

    Few methods permit the hydrogenation of alkenes to a thermodynamically favored configuration when steric effects dictate the alternative trajectory of hydrogen delivery. Dissolving metal reduction achieves this control, but with extremely low functional group tolerance. Here we demonstrate a catalytic hydrogenation of alkenes that affords the thermodynamic alkane products with remarkably broad functional group compatibility and rapid reaction rates at standard temperature and pressure. PMID:24428640

  3. Thermodynamics of interacting holographic dark energy

    NASA Astrophysics Data System (ADS)

    Arevalo, Fabiola; Cifuentes, Paulo; Peña, Francisco

    2016-01-01

    The thermodynamics of a scheme of dark matter-dark energy interaction is studied considering a holographic model for the dark energy in a flat Friedmann-Lemaitre-Robertson-Walker background. We obtain a total entropy rate for a general horizon and we study the Generalized Second Law of Thermodynamics for a cosmological interaction as a free function. Additionally, we discuss two horizons related to the Ricci and Ricci-like model and its effect on an interacting system.

  4. Thermodynamics of Bioreactions.

    PubMed

    Held, Christoph; Sadowski, Gabriele

    2016-06-01

    Thermodynamic principles have been applied to enzyme-catalyzed reactions since the beginning of the 1930s in an attempt to understand metabolic pathways. Currently, thermodynamics is also applied to the design and analysis of biotechnological processes. The key thermodynamic quantity is the Gibbs energy of reaction, which must be negative for a reaction to occur spontaneously. However, the application of thermodynamic feasibility studies sometimes yields positive Gibbs energies of reaction even for reactions that are known to occur spontaneously, such as glycolysis. This article reviews the application of thermodynamics in enzyme-catalyzed reactions. It summarizes the basic thermodynamic relationships used for describing the Gibbs energy of reaction and also refers to the nonuniform application of these relationships in the literature. The review summarizes state-of-the-art approaches that describe the influence of temperature, pH, electrolytes, solvents, and concentrations of reacting agents on the Gibbs energy of reaction and, therefore, on the feasibility and yield of biological reactions. PMID:27276551

  5. Configurational Entropy Revisited

    NASA Astrophysics Data System (ADS)

    Lambert, Frank L.

    2007-09-01

    Entropy change is categorized in some prominent general chemistry textbooks as being either positional (configurational) or thermal. In those texts, the accompanying emphasis on the dispersal of matter—independent of energy considerations and thus in discord with kinetic molecular theory—is most troubling. This article shows that the variants of entropy can be treated from a unified viewpoint and argues that to decrease students' confusion about the nature of entropy change these variants of entropy should be merged. Molecular energy dispersal in space is implicit but unfortunately tacit in the cell models of statistical mechanics that develop the configurational entropy change in gas expansion, fluids mixing, or the addition of a non-volatile solute to a solvent. Two factors are necessary for entropy change in chemistry. An increase in thermodynamic entropy is enabled in a process by the motional energy of molecules (that, in chemical reactions, can arise from the energy released from a bond energy change). However, entropy increase is only actualized if the process results in a larger number of arrangements for the system's energy, that is, a final state that involves the most probable distribution for that energy under the new constraints. Positional entropy should be eliminated from general chemistry instruction and, especially benefiting "concrete minded" students, it should be replaced by emphasis on the motional energy of molecules as enabling entropy change.

  6. Thermodynamic stoichiometries of participation of water, cations and anions in specific and non-specific binding of lac repressor to DNA. Possible thermodynamic origins of the "glutamate effect" on protein-DNA interactions.

    PubMed

    Ha, J H; Capp, M W; Hohenwalter, M D; Baskerville, M; Record, M T

    1992-11-01

    The objective of this study is to quantify the contributions of cations, anions and water to stability and specificity of the interaction of lac repressor (lac R) protein with the strong-binding symmetric lac operator (Osym) DNA site. To this end, binding constants Kobs and their power dependences on univalent salt (MX) concentration (SKobs = d log Kobs/d log[MX]) have been determined for the interactions of lac R with Osym operator and with non-operator DNA using filter binding and DNA cellulose chromatography, respectively. For both specific and non-specific binding of lac R, Kobs at fixed salt concentration [KX] increases when chloride (Cl-) is replaced by the physiological anion glutamate (Glu-). At 0.25 M-KX, the increase in Kobs for Osym is observed to be approximately 40-fold, whereas for non-operator DNA the increase in Kobs is estimated by extrapolation to be approximately 300-fold. For non-operator DNA, SKobsRD is independent of salt concentration within experimental uncertainty, and is similar in KCl (SKobs,RDKCl = -9.8(+/- 1.0) between 0.13 M and 0.18 M-KCl) and KGlu (SKobs,RDKGlu = -9.3(+/- 0.7) between 0.23 M and 0.36 M-KGlu). For Osym DNA, SKobsRO varies significantly with the nature of the anion, and, at least in KGlu appears to decrease in magnitude with increasing [KGlu]. Average magnitudes of SKobsRO are less than SKobsRD, and, for specific binding decrease in the order [SKobsRO,KCl[>[SKobsRO,KAc[>[SKobsRO,KGlu[ . Neither KobsRO nor SKobsRO is affected by the choice of univalent cation M+ (Na+, K+, NH4+, or mixtures thereof, all as the chloride salt), and SKobsRO is independent of [MCl] in the range examined (0.125 to 0.3 M). This behavior of SKobsRO is consistent with that expected for a binding process with a large contribution from the polyelectrolyte effect. However, the lack of an effect of the nature of the cation on the magnitude of KobsRO at a fixed [MX] is somewhat unexpected, in view of the order of preference of cations for the

  7. Methanol conversion to light olefins over nanostructured CeAPSO-34 catalyst: Thermodynamic analysis of overall reactions and effect of template type on catalytic properties and performance

    SciTech Connect

    Aghamohammadi, Sogand; Haghighi, Mohammad; Charghand, Mojtaba

    2014-02-01

    Graphical abstract: In this research nanostructured CeAPSO-34 was synthesized to explore the effect of TEAOH and morpholine on its physiochemical properties and MTO performance. Prepared catalysts were characterized with XRD, FESEM, BET, FTIR and NH3-TPD techniques. The results indicated that the nature of the template determines the physiochemical properties of CeAPSO-34 due to different rate of crystal growth. The catalyst obtained by using morpholine showed longer life time as well as sustaining light olefins selectivity at higher values. Furthermore, a comprehensive thermodynamic analysis of overall reactions network was carried out to address the major channels of methanol to olefins conversion. - Highlights: • Introduction of Ce into SAPO-34 framework. • Comparison of CeAPSO-34 synthesized using morpholine and TEAOH. • The nature of the template determines the physiochemical properties of CeAPSO-34. • Morpholine enhances catalyst lifetime in MTO process. • Presenting a complete reaction network for MTO process. - Abstract: TEAOH and morpholine were employed in synthesis of nanostructured CeAPSO-34 molecular sieve and used in methanol to olefins conversion. Prepared samples were characterized by XRD, FESEM, EDX, BET, FTIR and NH{sub 3}-TPD techniques. XRD patterns reflected the higher crystallinity of the catalyst synthesized with morpholine. The FESEM results indicated that the nature of the template determines the morphology of nanostructured CeAPSO-34 due to different rate of crystal growth. There was a meaningful difference in the strength of both strong and weak acid sites for CeAPSO-34 catalysts synthesized with TEAOH and morpholine templates. The catalyst synthesized with morpholine showed higher desorption temperature of both weak and strong acid sites evidenced by NH{sub 3}-TPD characterization. The catalyst obtained using morpholine template had the longer lifetime and sustained desired light olefins at higher values. A comprehensive

  8. The Aqueous Thermodynamics and Complexation Reactions of Anionic Silica Species to High Concentration: Effects on Neutralization of Leaked Tank Wastes and Migration of Radionuclides in the Subsurface

    SciTech Connect

    Felmy, Andrew R.; Choppin, Gregory; Dixon, David A.

    2002-06-01

    Highly basic tank wastes contain several important radionuclides, including {sup 90}Sr, {sup 99}Tc, and {sup 60}Co, as well as actinide elements (i.e., isotopes of U, Pu, and Am). These highly basic tank wastes are known to have leaked into the vadose zone at the Hanford Site. Upon entering the sediments in the vadose zone, the highly basic solutions dissolve large concentrations of silica from the silica and aluminosilicate minerals present in the subsurface. These dissolution reactions alter the chemical composition of the leaking solutions, transforming them from a highly basic (as high as 2M NaOH) solution into a pore solution with a very high concentration of dissolved silica and a significantly reduced pH. This moderately basic (pH 9 to 11), high-silica solution has the potential to complex radionuclides and move through the subsurface. Such strong radionuclide complexation is a currently unconsidered transport vector that has the potential to expedite radionuclide transport through the vadose zone. These strong complexation effects have the ability to significantly alter current conceptual models of contaminant migration beneath leaking tanks. In this project, we are determining the aqueous thermodynamics and speciation of dissolved silica and silica-radionuclide complexes to high silica concentration using a combination of (1) studies of chemical species structure and composition [via nuclear magnetic resonance (NMR) and, where applicable, laser-induced fluorescence spectroscopy and x-ray absorption spectroscopy] (2) molecular simulations to help identify key species structures and assist in interpreting experimental measurements (3) fundamental physical chemistry measurements, including solubility, electromotive force, and isopiestic measurements, to obtain the necessary thermodynamic data for predicting contaminant complexation and waste neutralization reactions. The radioactive elements we are studying include Sr, Co, Cs, Am(III), and U(VI).

  9. Effects of temperature on the thermodynamic and dynamical properties of glycerol-water mixtures: a computer simulation study of three different force fields.

    PubMed

    Akinkunmi, Frederick O; Jahn, David A; Giovambattista, Nicolas

    2015-05-21

    Glycerol-water solutions are relevant in technological and scientific applications, such as in the preservation of biomolecules and tissues at low temperatures. We perform molecular dynamics simulations of glycerol-water mixtures with glycerol molar fractions of χg = 0-100% at P = 0.1 MPa and T = 210-460 K. We focus on the effects of temperature and concentration on the thermodynamic (density ρ, thermal expansion coefficient αP, isobaric specific heat cP, compressibility κT) and dynamical (glycerol and water diffusion coefficients, Dg and Dw) properties of the mixtures. In particular, we test the sensitivity of computer simulation results to the glycerol force field and water model (TIP3P and TIP4P/2005) employed. All mixture models underestimate ρ at high T and tend to overestimate ρ at low T; only the mixture model based on TIP4P/2005 water exhibits a density maximum at low χg, as expected. All models overestimate αP, cP, and κT; they are able to reproduce qualitatively the T dependence of αP and κT but fail in the case of cP. In all cases, Dg and Dw follow the Vogel-Tamman-Fulcher equation and decouple at low T, with Dw/Dg increasing upon cooling. Overall, the mixture based on TIP4P/2005 water provides better thermodynamic and dynamical properties than the mixtures based on TIP3P water, even at χg = 20%. PMID:25901644

  10. Nonequilibrium thermodynamics of pressure solution

    NASA Astrophysics Data System (ADS)

    Lehner, F. K.; Bataille, J.

    1984-01-01

    This paper is concerned with the thermodynamic theory of solution and precipitation processes in wet crustal rocks and with the mechanism of steady pressure-solution slip in ‘contact zones,’ such as grain-to-grain contacts, fracture surfaces, and permeable gouge layers, that are infiltrated by a mobile aqueous solution phase. A local dissipation jump condition at the phase boundary is fundamental to identifying the thermodynamic force driving the solution and precipitation process and is used here in setting up linear phenomenological relations to model near-equilibrium phase transformation kinetics. The local thermodynamic equilibrium of a stressed pure solid in contact with its melt or solution phase is governed by Gibbs's relation, which is rederived here, in a manner emphasizing its independence of constitutive assumptions for the solid while neglecting surface tension and diffusion in the solid. Fluid-infiltrated contact zones, such as those formed by rough surfaces, cannot generally be in thermodynamic equilibrium, especially during an ongoing process of pressure-solution slip, and the existing equilibrium formulations are incorrect in overlooking dissipative processes tending to eliminate fluctuations in superficial free energies due to stress concentrations near asperities, defects, or impurities. Steady pressure-solution slip is likely to exhibit a nonlinear dependence of slip rate on shear stress and effective normal stress, due to a dependence of the contact-zone state on the latter. Given that this dependence is negligible within some range, linear relations for pressure-solution slip can be derived for the limiting cases of diffusion-controlled and interface-reaction-controlled rates. A criterion for rate control by one of these mechanisms is set by the magnitude of the dimensionless quantity kδ/2C pD, where k is the interfacial transfer coefficient, δ is the mean diffusion path length, C p is the solubility at pressure p, and D is the mass

  11. Mechanics and thermodynamics in lubrication

    NASA Technical Reports Server (NTRS)

    Cameron, A.; Gentle, C. R.

    1973-01-01

    The causes for breakdown in the lubricant film of mineral oils are discussed. It is stated that the critical point is caused by desorption of the naturally occurring surface active agent and can be described by thermodynamic analysis. The effect of different metals in lubrication is surveyed. The problem of breakdown in elastohydrodynamic lubrication is treated phenomenologically by studying traction. The topics considered are classical and non-Newtonian explanations, anomalous film thickness and viscosity effects, surface roughness contributions, and solidification of the lubricant. Reasons for the apparent granular traction characteristics are examined.

  12. Universal ideal behavior and macroscopic work relation of linear irreversible stochastic thermodynamics

    NASA Astrophysics Data System (ADS)

    Ma, Yi-An; Qian, Hong

    2015-06-01

    We revisit the Ornstein-Uhlenbeck (OU) process as the fundamental mathematical description of linear irreversible phenomena, with fluctuations, near an equilibrium. By identifying the underlying circulating dynamics in a stationary process as the natural generalization of classical conservative mechanics, a bridge between a family of OU processes with equilibrium fluctuations and thermodynamics is established through the celebrated Helmholtz theorem. The Helmholtz theorem provides an emergent macroscopic ‘equation of state’ of the entire system, which exhibits a universal ideal thermodynamic behavior. Fluctuating macroscopic quantities are studied from the stochastic thermodynamic point of view and a non-equilibrium work relation is obtained in the macroscopic picture, which may facilitate experimental study and application of the equalities due to Jarzynski, Crooks, and Hatano and Sasa.

  13. Effect of Non-local Thermodynamic Equilibrium Model Atmospheres on Photometric Amplitudes and Phases of Early B-type Pulsating Stars

    NASA Astrophysics Data System (ADS)

    Daszyńska-Daszkiewicz, J.; Szewczuk, W.

    2011-02-01

    Amplitudes and phases of the light variation of a pulsating star in various photometric passbands contain information about the geometry of observed modes. Because oscillation spectra of early B-type main-sequence stars do not exhibit regular patterns, these observables are very often the only ones from which mode identification can be derived. Moreover, these data can yield valuable constraints on mean stellar parameters, subphotospheric convection, microphysics, and atmospheres. We study all possible sources of inaccuracy in theoretical values of the photometric observables, i.e., amplitude ratios and phase differences, of early B-type main-sequence pulsators. Here, we discuss the effects of parameters coming from both model atmospheres and linear nonadiabatic theory of stellar pulsation. In particular, we evaluate for the first time the effect of the departure from the local thermodynamic equilibrium (LTE) approximation. To this end, for non-LTE model atmospheres, we compute tables with the passband fluxes, flux derivatives over effective temperature and gravity, as well as the nonlinear limb-darkening coefficients in 12 passbands most often used. We make these tables publicly available at the Wrocław HELAS Web site.

  14. Thermodynamics of Nonadditive Systems

    NASA Astrophysics Data System (ADS)

    Latella, Ivan; Pérez-Madrid, Agustín; Campa, Alessandro; Casetti, Lapo; Ruffo, Stefano

    2015-06-01

    The usual formulation of thermodynamics is based on the additivity of macroscopic systems. However, there are numerous examples of macroscopic systems that are not additive, due to the long-range character of the interaction among the constituents. We present here an approach in which nonadditive systems can be described within a purely thermodynamics formalism. The basic concept is to consider a large ensemble of replicas of the system where the standard formulation of thermodynamics can be naturally applied and the properties of a single system can be consequently inferred. After presenting the approach, we show its implementation in systems where the interaction decays as 1 /rα in the interparticle distance r , with α smaller than the embedding dimension d , and in the Thirring model for gravitational systems.

  15. THERMODYNAMIC MODELING AND FIRST-PRINCIPLES CALCULATIONS

    SciTech Connect

    Turchi, P; Abrikosov, I; Burton, B; Fries, S; Grimvall, G; Kaufman, L; Korzhavyi, P; Manga, R; Ohno, M; Pisch, A; Scott, A; Zhang, W

    2005-12-15

    The increased application of quantum mechanical-based methodologies to the study of alloy stability has required a re-assessment of the field. The focus is mainly on inorganic materials in the solid state. In a first part, after a brief overview of the so-called ab initio methods with their approximations, constraints, and limitations, recommendations are made for a good usage of first-principles codes with a set of qualifiers. Examples are given to illustrate the power and the limitations of ab initio codes. However, despite the ''success'' of these methodologies, thermodynamics of complex multi-component alloys, as used in engineering applications, requires a more versatile approach presently afforded within CALPHAD. Hence, in a second part, the links that presently exist between ab initio methodologies, experiments, and CALPHAD approach are examined with illustrations. Finally, the issues of dynamical instability and of the role of lattice vibrations that still constitute the subject of ample discussions within the CALPHAD community are revisited in the light of the current knowledge with a set of recommendations.

  16. The Thermodynamics of General and Local Anesthesia

    NASA Astrophysics Data System (ADS)

    Græsbøll, Kaare; Sasse-Middelhoff, Henrike; Heimburg, Thomas

    2014-05-01

    General anesthetics are known to cause depression of the freezing point of transitions in biomembranes. This is a consequence of ideal mixing of the anesthetic drugs in the membrane fluid phase and exclusion from the solid phase. Such a generic law provides physical justification of the famous Meyer-Overton rule. We show here that general anesthetics, barbiturates and local anesthetics all display the same effect on melting transitions. Their effect is reversed by hydrostatic pressure. Thus, the thermodynamic behavior of local anesthetics is very similar to that of general anesthetics. We present a detailed thermodynamic analysis of heat capacity profiles of membranes in the presence of anesthetics. This analysis is able to describe experimentally observed calorimetric profiles and permits prediction of the anesthetic features of arbitrary molecules. In addition, we discuss the thermodynamic origin of the cutoff-effect of long-chain alcohols and the additivity of the effect of general and local anesthetics.

  17. The Thermodynamics of General and Local Anesthesia

    PubMed Central

    Græsbøll, Kaare; Sasse-Middelhoff, Henrike; Heimburg, Thomas

    2014-01-01

    General anesthetics are known to cause depression of the freezing point of transitions in biomembranes. This is a consequence of ideal mixing of the anesthetic drugs in the membrane fluid phase and exclusion from the solid phase. Such a generic law provides physical justification of the famous Meyer-Overton rule. We show here that general anesthetics, barbiturates, and local anesthetics all display the same effect on melting transitions. Their effect is reversed by hydrostatic pressure. Thus, the thermodynamic behavior of local anesthetics is very similar to that of general anesthetics. We present a detailed thermodynamic analysis of heat capacity profiles of membranes in the presence of anesthetics. Using this analysis, we are able to describe experimentally observed calorimetric profiles and predict the anesthetic features of arbitrary molecules. In addition, we discuss the thermodynamic origin of the cutoff effect of long-chain alcohols and the additivity of the effect of general and local anesthetics. PMID:24853743

  18. The thermodynamics of general and local anesthesia.

    PubMed

    Graesbøll, Kaare; Sasse-Middelhoff, Henrike; Heimburg, Thomas

    2014-05-20

    General anesthetics are known to cause depression of the freezing point of transitions in biomembranes. This is a consequence of ideal mixing of the anesthetic drugs in the membrane fluid phase and exclusion from the solid phase. Such a generic law provides physical justification of the famous Meyer-Overton rule. We show here that general anesthetics, barbiturates, and local anesthetics all display the same effect on melting transitions. Their effect is reversed by hydrostatic pressure. Thus, the thermodynamic behavior of local anesthetics is very similar to that of general anesthetics. We present a detailed thermodynamic analysis of heat capacity profiles of membranes in the presence of anesthetics. Using this analysis, we are able to describe experimentally observed calorimetric profiles and predict the anesthetic features of arbitrary molecules. In addition, we discuss the thermodynamic origin of the cutoff effect of long-chain alcohols and the additivity of the effect of general and local anesthetics. PMID:24853743

  19. Thermodynamics of graphene

    NASA Astrophysics Data System (ADS)

    Rusanov, A. I.

    2014-12-01

    The 21st century has brought a lot of new results related to graphene. Apparently, graphene has been characterized from all points of view except surface science and, especially, surface thermodynamics. This report aims to close this gap. Since graphene is the first real two-dimensional solid, a general formulation of the thermodynamics of two-dimensional solid bodies is given. The two-dimensional chemical potential tensor coupled with stress tensor is introduced, and fundamental equations are derived for energy, free energy, grand thermodynamic potential (in the classical and hybrid forms), enthalpy, and Gibbs energy. The fundamentals of linear boundary phenomena are formulated with explaining the concept of a dividing line, the mechanical and thermodynamic line tensions, line energy and other linear properties with necessary thermodynamic equations. The one-dimensional analogs of the Gibbs adsorption equation and Shuttleworth-Herring relation are presented. The general thermodynamic relationships are illustrated with calculations based on molecular theory. To make the reader sensible of the harmony of chemical and van der Waals forces in graphene, the remake of the classical graphite theory is presented with additional variable combinations of graphene sheets. The calculation of the line energy of graphene is exhibited including contributions both from chemical bonds and van der Waals forces (expectedly, the latter are considerably smaller than the former). The problem of graphene holes originating from migrating vacancies is discussed on the basis of the Gibbs-Curie principle. An important aspect of line tension is the planar sheet/nanotube transition where line tension acts as a driving force. Using the bending stiffness of graphene, the possible radius range is estimated for achiral (zigzag and armchair) nanotubes.

  20. Thermodynamics of lattice OCD

    SciTech Connect

    Matsuoka, H.

    1985-01-01

    The thermodynamic consequences of QCD are explored in the framework of lattice gauge theory. Attention is focused upon the nature of the chiral symmetry restoration transition at finite temperature and at finite baryon density, and possible strategies for identifying relevant thermodynamic phases are discussed. Some numerical results are presented on the chiral symmetry restoration in the SU(2) gauge theory at high baryon density. The results suggest that with T approx. = 110 MeV there is a second order restoration transition at the critical baryon density n/sub B//sup c/ approx. = 0.62 fm/sup -3/.

  1. The frictionless damping of a piston in thermodynamics

    NASA Astrophysics Data System (ADS)

    Bringuier, E.

    2015-09-01

    The paper revisits Rüchardt’s experiment and the two-chamber variant of Clark and Katz, where the oscillating motion of a freely sliding piston involves the adiabatic exponent of the gas enclosed in a thermally isolated chamber. While the common theoretical account of the experiment correctly predicts the frequency of the oscillation, the damping is usually ascribed to a linear frictional force of an undetermined mechanical nature. In this paper, we argue that the irreversibility of the damped motion calls for a thermodynamical treatment involving dissipation (entropy production). The theory of Rüchardt’s experiment is reworked at the undergraduate level by allowing entropy to change owing to heat transfer into or out of the chamber. It is calculated that a linear heat transfer can explain the observed damping without assuming any mechanical friction. The calculation is quantitatively supported by an experiment. It is also calculated that the mechanical and thermal equilibrations occur at the same rate. Besides possibly improving Rüchardt and Clark-and-Katz apparatuses by shedding light on the damping, the paper helps to better grasp thermodynamics, and how to use entropy, by constrasting the mechanical and thermodynamical reasonings on the example of the damped motion of a piston.

  2. Friction in macroscopic thermodynamics: A kinetic point of view

    NASA Astrophysics Data System (ADS)

    Bizarro, João P. S.

    2015-12-01

    To provide a solid support to a macroscopic framework developed to explicitly account for friction in thermodynamics, a kinetic description of frictional dissipation is developed. Using either a dissipative Fokker-Planck equation for Brownian motion or a Boltzmann equation with a friction-force term added, it is shown that both approaches lead to the emergence of the macroscopic thermodynamic relations that state the first and second laws with friction. The analysis is directly applied to the problem of determining the minimum amount of heating generated by memory erasure, known in computer science as Landauer's bound, and leads to a better understanding of the energetics behind the latter. A generalisation of Boltzmann's H theorem to include friction explicitly is also recovered, and the thermodynamics of granular rotators acted by a frictional torque and of radio-frequency (RF) current drive of fusion plasmas, in which collisional drag is present, are addressed as well. Various physics results are revisited employing the first and second laws with friction that have been derived from the appropriate dissipative kinetic equations, lower bounds for entropy production rates being derived both for granular rotators and for RF current drive.

  3. Effect of combined external uniaxial stress and dc bias on the dielectric property of BaTiO3-based dielectrics in multilayer ceramic capacitor: thermodynamics and experiments

    NASA Astrophysics Data System (ADS)

    Yang, Gang; Yue, Zhenxing; Sun, Tieyu; Gou, Huanlin; Li, Longtu

    2008-02-01

    The dielectric properties of (Nb, Y)-doped BaTiO3 in a multilayer ceramic capacitor (MLCC) under combined external uniaxial compressive stress and dc bias field were investigated at room temperature by using a modified Ginsburg-Landau-Devonshire thermodynamic theory and the dielectric measurement. It is found that although dc bias decreases the dielectric properties dominantly, the influence of the external uniaixial compressive stress should not be neglected. When applied along a direction perpendicular to the internal electrode layer in the MLCC, the external uniaixal compressive stress will strengthen the negative effect of dc bias. In contrast, the external uniaxial compressive stress along a direction parallel to the internal electrode layer in the MLCC will increase the dielectric permittivity under dc bias field, i.e. improve the ɛ-V response of the MLCC. Furthermore, although there is a difference between the calculated permittivity and the measured permittivity, the effects of the combined external uniaxial compressive stress and dc bias field on the dielectric permittivity described through two approaches are in good agreement.

  4. SLIM--An Early Work Revisited

    SciTech Connect

    Chao, Alex; /SLAC

    2008-07-25

    An early, but at the time illuminating, piece of work on how to deal with a general, linearly coupled accelerator lattice is revisited. This work is based on the SLIM formalism developed in 1979-1981.

  5. Black Hole Thermodynamics in an Undergraduate Thermodynamics Course.

    ERIC Educational Resources Information Center

    Parker, Barry R.; McLeod, Robert J.

    1980-01-01

    An analogy, which has been drawn between black hole physics and thermodynamics, is mathematically broadened in this article. Equations similar to the standard partial differential relations of thermodynamics are found for black holes. The results can be used to supplement an undergraduate thermodynamics course. (Author/SK)

  6. Thermodynamics of convective circulations

    NASA Astrophysics Data System (ADS)

    Adams, D. K.; Renno, N. O.

    2003-04-01

    The heat engine framework has proven successful for studies of atmospheric phenomena ranging from small to large scales. At large scales, the heat engine framework provides estimates of convective available potential energy, convective velocities, and fractional area covered by convection. At the smaller end of the spectrum, the framework provides estimates of the intensity of convective vortices such as dust devils and waterspouts. The heat engine framework sheds light on the basic physics of planetary atmospheres. In particular, it allows the calculation of their thermodynamic efficiency. Indeed, this is a fundamental number for atmospheric circulations because it quantifies the amount of heat that is converted into kinetic energy. As such, it is a valuable number not only for comparison of models with nature, but also for the intercomparison of models. In the present study, we generalize the heat engine framework to large-scale circulations, both open (e.g., the Hadley circulation) and closed (e.g., the general circulation) and apply it to an idealized global climate model to ascertain the thermodynamic efficiency of model circulations, both global and regional. Our results show that the thermodynamic efficiency is sensitive to model resolution and provides a baseline for minimum model resolution in climate studies. The value of the thermodynamic efficiency of convective circulations in nature is controversial. It has been suggested that both nature and numerical models are extremely irreversible. We show that both the global and the Hadley circulation of the idealized model are, to a first approximation, reversible.

  7. Program Computes Thermodynamic Functions

    NASA Technical Reports Server (NTRS)

    Mcbride, Bonnie J.; Gordon, Sanford

    1994-01-01

    PAC91 is latest in PAC (Properties and Coefficients) series. Two principal features are to provide means of (1) generating theoretical thermodynamic functions from molecular constants and (2) least-squares fitting of these functions to empirical equations. PAC91 written in FORTRAN 77 to be machine-independent.

  8. Thermodynamics of Resource Recycling.

    ERIC Educational Resources Information Center

    Hauserman, W. B.

    1988-01-01

    Evaluates the overall economic efficiency of a closed resource cycle. Uses elementary thermodynamic definitions of overall thermal efficiency for determining an economically quantifiable basis. Selects aluminum for investigation and includes a value-entropy diagram for a closed aluminum cycle. (MVL)

  9. Thermodynamics of Dilute Solutions.

    ERIC Educational Resources Information Center

    Jancso, Gabor; Fenby, David V.

    1983-01-01

    Discusses principles and definitions related to the thermodynamics of dilute solutions. Topics considered include dilute solution, Gibbs-Duhem equation, reference systems (pure gases and gaseous mixtures, liquid mixtures, dilute solutions), real dilute solutions (focusing on solute and solvent), terminology, standard states, and reference systems.…

  10. Thermodynamics with Design Problems.

    ERIC Educational Resources Information Center

    Cilento, E. V.; Sears, J. T.

    1983-01-01

    Discusses how basic thermodynamics concepts are integrated with design problems. Includes course goals, instructional strategies, and major advantages/disadvantages of the integrated design approach. Advantages include making subject more concrete, emphasizing interrelation of variables, and reinforcing concepts by use in design analysis; whereas…

  11. Focus on stochastic thermodynamics

    NASA Astrophysics Data System (ADS)

    Van den Broeck, Christian; Sasa, Shin-ichi; Seifert, Udo

    2016-02-01

    We introduce the thirty papers collected in this ‘focus on’ issue. The contributions explore conceptual issues within and around stochastic thermodynamics, use this framework for the theoretical modeling and experimental investigation of specific systems, and provide further perspectives on and for this active field.

  12. On Teaching Thermodynamics

    ERIC Educational Resources Information Center

    Debbasch, F.

    2011-01-01

    The logical structure of classical thermodynamics is presented in a modern, geometrical manner. The first and second law receive clear, operatively oriented statements and the Gibbs free energy extremum principle is fully discussed. Applications relevant to chemistry, such as phase transitions, dilute solutions theory and, in particular, the law…

  13. Fluctuating Thermodynamics for Biological Processes

    NASA Astrophysics Data System (ADS)

    Ham, Sihyun

    Because biomolecular processes are largely under thermodynamic control, dynamic extension of thermodynamics is necessary to uncover the mechanisms and driving factors of fluctuating processes. The fluctuating thermodynamics technology presented in this talk offers a practical means for the thermodynamic characterization of conformational dynamics in biomolecules. The use of fluctuating thermodynamics has the potential to provide a comprehensive picture of fluctuating phenomena in diverse biological processes. Through the application of fluctuating thermodynamics, we provide a thermodynamic perspective on the misfolding and aggregation of the various proteins associated with human diseases. In this talk, I will present the detailed concepts and applications of the fluctuating thermodynamics technology for elucidating biological processes. This work was supported by Samsung Science and Technology Foundation under Project Number SSTF-BA1401-13.

  14. The Cutaneous Rabbit Revisited

    ERIC Educational Resources Information Center

    Flach, Rudiger; Haggard, Patrick

    2006-01-01

    In the cutaneous rabbit effect (CRE), a tactile event (so-called attractee tap) is mislocalized toward an adjacent attractor tap. The effect depends on the time interval between the taps. The authors delivered sequences of taps to the forearm and asked participants to report the location of one of the taps. The authors replicated the original CRE…

  15. Public Speaking: Revisited.

    ERIC Educational Resources Information Center

    Taufen, Phyllis M.

    There is a simple but effective process for developing public speakers in elementary and junior high schools. After discussing the importance of effective speaking, the teacher puts a topic sentence, on favorite desserts for example, on the board or overhead projector and students think of their favorite desserts and some related words and…

  16. Inconsistencies in steady state thermodynamics

    NASA Astrophysics Data System (ADS)

    Dickman, Ronald; Motai, Ricardo

    2014-03-01

    We address the issue of extending thermodynamics to nonequilibrium steady states. Using driven stochastic lattice gases, we ask whether consistent definitions of an effective chemical potential μ, and an effective temperature Te, are possible. These quantities are determined via zero-flux conditions of particles and energy between the driven system and a reservoir. For the models considered here, the fluxes are given in terms of certain stationary average densities, eliminating the need to perturb the system by actually exchanging particles; μ and Te are thereby obtained via open-circuit measurements, using a virtual reservoir. In the lattice gas with nearest-neighbor exclusion, temperature is not relevant, and we find that the effective chemical potential, a function of density and drive strength, satisfies the zeroth law, and correctly predicts the densities of coexisting systems. In the Katz-Lebowitz-Spohn driven lattice gas, both μ and Te need to be defined. We show analytically that the zeroth law is violated, and determine the size of the violations numerically. Our results highlight a fundamental inconsistency in the extension of thermodynamics to nonequilibrium steady states. Research supported by CNPq, Brazil.

  17. Thermodynamic characterization of the interaction behavior of a hydrophobically modified polyelectrolyte and oppositely charged surfactants in aqueous solution: effect of surfactant alkyl chain length.

    PubMed

    Bai, Guangyue; Nichifor, Marieta; Lopes, António; Bastos, Margarida

    2005-01-13

    We have used a precision isothermal titration microcalorimeter (ITC) to measure the enthalpy curves for the interaction of a hydrophobically modified polyelectrolyte (D40OCT30) with oppositely charged surfactants (SC(n)S) in aqueous solution. D40OCT30 is a newly synthesized polymer based on dextran having pendant N-(2-hydroxypropyl)-N,N-dimethyl-N-octylammonium chloride groups randomly distributed along the polymer backbone with degree of substitution of 28.1%. The employed anionic surfactants are sodium octyl sulfate (SC(8)S) and sodium tetradecyl sulfate (SC(14)S). Microcalorimetric results along with turbidity and kinematic viscosity measurements demonstrate systematically the thermodynamic characterization of the interaction of D40OCT30/SC(n)S. A three-dimensional diagram with the derived phase boundaries is drawn to describe the effect of the alkyl chain length of surfactant and of the ratio between surfactant and pendant groups on the interaction. A more complete picture of the interaction mechanism for D40OCT30/SC(n)S systems is proposed here. PMID:16851043

  18. Thermodynamics and phase relations of the Fe-O-S-Si2(sat) system at 1200 °C and the effect of copper

    NASA Astrophysics Data System (ADS)

    Li, H.; Rankin, W. J.

    1994-01-01

    A laboratory investigation was carried out in which iron was reacted in silica crucibles with an atmosphere of controlled oxygen and sulfur partial pressures. The equilibrium compositions of the melts were determined over the range 10-12 to 10-9 atm oxygen and 10-2.75 to 10-1 atm sulfur and it was found that the Fe-O-S-SiO2 system can exist as either a slag or oxysulfide. The oxysulfide contained appreciable quantities of dissolved oxygen and silica, although the levels decreased as the sulfur content was increased. Sulfur also had the effect of reducing the solubility of silica in the slag. When copper was added to the system, the solubility of oxygen and silica in the oxysulfide phase decreased dramatically. The results are examined in terms of the thermodynamics of the relevant reactions, and the predominance area diagram for the copper-free system was established by combining the present results with those of earlier investigations.

  19. Effect of Mg²⁺ and Al²⁺ Ions on Thermodynamic and Physiochemical Properties of Aspergillus niger Invertases.

    PubMed

    Nadeem, Habibullah; Rashid, Muhammad H; Siddique, Muhammad H

    2015-01-01

    In the present study, we reported for the first time the effect of various concentrations (0.5- 3.0 mM) of Mg(2+) and Al(3+) ions on the kinetics and thermodynamics of Aspergillus niger invertases for sucrose hydrolysis. We found that both metal ions enhanced the affinity of invertase for sucrose by decreasing the Km. In the presence of 0.5 mM Al(3+) ions invertase have maximum affinity for sucrose (Km = 0.00914 M sucrose). Invertase was activated by Mg(2+) ions at low concentrations (0.5-2.0 mM) and 341% increase in turnover (Kcat) and maximum decrease in ΔG* was observed in the presence of 0.5 mM Mg(2+) ions. The entropy change for activation of substrate hydrolysis (ΔS*) was increased by all concentrations of Mg(2+) ions and was highest (-94 J mol(-1) K(-1)) for invertases bound with 1.5 mM Mg(2+) ions. PMID:26021385

  20. Effects of the adsorption of alkali metal oxides on the electronic, optical, and thermodynamic properties of the Mg12O12nanocage: a density functional theory study.

    PubMed

    Mohammadi Hesari, Asghar; Shamlouei, Hamid Reza; Raoof Toosi, Ali

    2016-08-01

    The effect of alkali metal oxides M n O (M = Li, Na, K; n = 2, 3, 4) on the geometric, electronic, and linear and nonlinear optical properties of the Mg12O12 nanocage was investigated by density-functional-based methods. According to the computational results, these alkali metal oxides are adsorbed on the Mg12O12 nanocage because this adsorption reduces its energy gap. The static first hyperpolarizability (β 0) of the nanocage is dramatically increased in the presence of the alkali metal oxides, with the greatest increase seen in the presence of the superalkalis (i.e., M3O; M = Li, Na, and K). The highest first hyperpolarizability (β 0 ≈ 600,000 a.u.) was calculated for K3O@Mg12O12, which was considerably more than that for Mg12O12. The thermodynamic properties and relative stabilities of these inorganic compounds are discussed. Graphical Abstract Optimized structure and DOS spectrum of K3O(e@Mg12O12). PMID:27449668

  1. A constitutive model for magnetostriction based on thermodynamic framework

    NASA Astrophysics Data System (ADS)

    Ho, Kwangsoo

    2016-08-01

    This work presents a general framework for the continuum-based formulation of dissipative materials with magneto-mechanical coupling in the viewpoint of irreversible thermodynamics. The thermodynamically consistent model developed for the magnetic hysteresis is extended to include the magnetostrictive effect. The dissipative and hysteretic response of magnetostrictive materials is captured through the introduction of internal state variables. The evolution rate of magnetostrictive strain as well as magnetization is derived from thermodynamic and dissipative potentials in accordance with the general principles of thermodynamics. It is then demonstrated that the constitutive model is competent to describe the magneto-mechanical behavior by comparing simulation results with the experimental data reported in the literature.

  2. Revisiting Tversky's diagnosticity principle.

    PubMed

    Evers, Ellen R K; Lakens, Daniël

    2014-01-01

    Similarity is a fundamental concept in cognition. In 1977, Amos Tversky published a highly influential feature-based model of how people judge the similarity between objects. The model highlights the context-dependence of similarity judgments, and challenged geometric models of similarity. One of the context-dependent effects Tversky describes is the diagnosticity principle. The diagnosticity principle determines which features are used to cluster multiple objects into subgroups. Perceived similarity between items within clusters is expected to increase, while similarity between items in different clusters decreases. Here, we present two pre-registered replications of the studies on the diagnosticity effect reported in Tversky (1977). Additionally, one alternative mechanism that has been proposed to play a role in the original studies, an increase in the choice for distractor items (a substitution effect, see Medin et al., 1995), is examined. Our results replicate those found by Tversky (1977), revealing an average diagnosticity-effect of 4.75%. However, when we eliminate the possibility of substitution effects confounding the results, a meta-analysis of the data provides no indication of any remaining effect of diagnosticity. PMID:25161638

  3. Revisiting Tversky's diagnosticity principle

    PubMed Central

    Evers, Ellen R. K.; Lakens, Daniël

    2013-01-01

    Similarity is a fundamental concept in cognition. In 1977, Amos Tversky published a highly influential feature-based model of how people judge the similarity between objects. The model highlights the context-dependence of similarity judgments, and challenged geometric models of similarity. One of the context-dependent effects Tversky describes is the diagnosticity principle. The diagnosticity principle determines which features are used to cluster multiple objects into subgroups. Perceived similarity between items within clusters is expected to increase, while similarity between items in different clusters decreases. Here, we present two pre-registered replications of the studies on the diagnosticity effect reported in Tversky (1977). Additionally, one alternative mechanism that has been proposed to play a role in the original studies, an increase in the choice for distractor items (a substitution effect, see Medin et al., 1995), is examined. Our results replicate those found by Tversky (1977), revealing an average diagnosticity-effect of 4.75%. However, when we eliminate the possibility of substitution effects confounding the results, a meta-analysis of the data provides no indication of any remaining effect of diagnosticity. PMID:25161638

  4. Effects of nanosized titanium dioxide on the physicochemical stability of activated sludge flocs using the thermodynamic approach and Kelvin probe force microscopy.

    PubMed

    Yang, Xiaonan; Cui, Fuyi; Guo, Xiaochun; Li, Dapeng

    2013-08-01

    The wide application of nanosized titanium dioxide (nano-TiO2) will result in high concentrations of the molecule in the aquatic environment, especially in the influent of wastewater treatment plants. The present study focuses on the potential effect of nano-TiO2 on the physicochemical stability of activated sludge flocs after long-term exposure, on which limited information is currently available. Kelvin probe force microscopy (KPFM) was innovatively applied to assess the surface potential of the activated sludge in situ. The physicochemical characteristics of the bioflocs with and without long-term exposure to nano-TiO2 were well elucidated by the thermodynamic approach. The results showed that the repulsive force predominated the bioflocs system as the concentration of nano-TiO2 increased, owing to the corresponding increase in the density of the negative charge. The bioflocs exposed to 100 ppm nano-TiO2 presented the strongest stability compared to the other two samples with low concentrations of nano-TiO2, which also indicated that the bioflocs with long-term exposure to nano-TiO2 had a low settlement efficiency of the corresponding activated sludge. Further, the extended Derjaugin, Landau, Verwey, and Overbeek (XDLVO) theory was used to explore the flocculation stability of the bioflocs system. As the concentration of nano-TiO2 increased, the ΔGiwi(LW)attraction (the van der Waals interaction) and the effective Hamaker constant decreased, the ΔGiwi(EL)(the electrostatic double-layers interaction) increasingly contributed to the interfacial repulsion, the ΔGiwi(AB)(the Lewis acid-base interaction) also exhibited a repulsive contribution to the total interaction energy and the ΔGiwi(TOT) (the total free energy of interaction) exhibited a repulsive contribution. These results are the keys for interpreting the adverse effects of nano-TiO2 on the activated sludge flocs of wastewater treatment plant (WWTP). PMID:23706860

  5. Microbial surface thermodynamics and applications.

    PubMed

    Strevett, Keith A; Chen, Gang

    2003-06-01

    Microbial surface thermodynamics is the reflection of microbial physicochemical and biological characteristics and it bridges micro-scale structures with macro-scale biological functions. Microbial surface thermodynamics is theoretically based on colloid surface thermodynamics using the classical theory of colloidal stability, Derjauin-Landau-Verwey-Overbeek (DLVO) theory. An extended DLVO theory is applied to for the hydration forces not considered in the classical DLVO theory. Herein, a review of current application of microbial surface thermodynamic theory is presented. Microbial surface thermodynamic theory is the fundamental theory in interpreting microbial hydrophilicity or hydrophobicity, microbial attachment, and microbial biofilm development. PMID:12837508

  6. The Quiet American Revisited.

    ERIC Educational Resources Information Center

    Legters, Lyman H.

    1984-01-01

    What is wrong in the American parochialism about foreign languages is the assumption that language acquisition is a cosmetic gain, without any immediate or forseeable practical use. Languages will only be learned effectively when Americans learn that they can be used in getting tasks accomplished. (MSE)

  7. Thermodynamic analysis of spectra

    SciTech Connect

    Mitchell, G. E.; Shriner, J. F. Jr.

    2008-04-04

    Although random matrix theory had its initial application to neutron resonances, there is a relative scarcity of suitable nuclear data. The primary reason for this is the sensitivity of the standard measures used to evaluate spectra--the spectra must be essential pure (no state with a different symmetry) and complete (no states missing). Additional measures that are less sensitive to these experimental limitations are of significant value. The standard measure for long range order is the {delta}{sub 3} statistic. In the original paper that introduced this statistic, Dyson and Mehta also attempted to evaluate spectra with thermodynamic variables obtained from the circular orthogonal ensemble. We consider the thermodynamic 'internal energy' and evaluate its sensitivity to experimental limitations such as missing and spurious levels. Monte Carlo simulations suggest that the internal energy is less sensitive to mistakes than is {delta}{sub 3}, and thus the internal energy can serve as a addition to the tool kit for evaluating experimental spectra.

  8. Perspective on quantum thermodynamics

    NASA Astrophysics Data System (ADS)

    Millen, James; Xuereb, André

    2016-01-01

    Classical thermodynamics is unrivalled in its range of applications and relevance to everyday life. It enables a description of complex systems, made up of microscopic particles, in terms of a small number of macroscopic quantities, such as work and entropy. As systems get ever smaller, fluctuations of these quantities become increasingly relevant, prompting the development of stochastic thermodynamics. Recently we have seen a surge of interest in exploring the quantum regime, where the origin of fluctuations is quantum rather than thermal. Many questions, such as the role of entanglement and the emergence of thermalisation, lie wide open. Answering these questions may lead to the development of quantum heat engines and refrigerators, as well as to vitally needed simple descriptions of quantum many-body systems.

  9. Thermodynamics of nuclear transport

    NASA Astrophysics Data System (ADS)

    Wang, Ching-Hao; Mehta, Pankaj; Elbaum, Michael

    Molecular transport across the nuclear envelope is important for eukaryotes for gene expression and signaling. Experimental studies have revealed that nuclear transport is inherently a nonequilibrium process and actively consumes energy. In this work we present a thermodynamics theory of nuclear transport for a major class of nuclear transporters that are mediated by the small GTPase Ran. We identify the molecular elements responsible for powering nuclear transport, which we term the ``Ran battery'' and find that the efficiency of transport, measured by the cargo nuclear localization ratio, is limited by competition between cargo molecules and RanGTP to bind transport receptors, as well as the amount of NTF2 (i.e. RanGDP carrier) available to circulate the energy flow. This picture complements our current understanding of nuclear transport by providing a comprehensive thermodynamics framework to decipher the underlying biochemical machinery. Pm and CHW were supported by a Simons Investigator in the Mathematical Modeling in Living Systems grant (to PM).

  10. Statistical Thermodynamics of Biomembranes

    PubMed Central

    Devireddy, Ram V.

    2010-01-01

    An overview of the major issues involved in the statistical thermodynamic treatment of phospholipid membranes at the atomistic level is summarized: thermodynamic ensembles, initial configuration (or the physical system being modeled), force field representation as well as the representation of long-range interactions. This is followed by a description of the various ways that the simulated ensembles can be analyzed: area of the lipid, mass density profiles, radial distribution functions (RDFs), water orientation profile, Deuteurium order parameter, free energy profiles and void (pore) formation; with particular focus on the results obtained from our recent molecular dynamic (MD) simulations of phospholipids interacting with dimethylsulfoxide (Me2SO), a commonly used cryoprotective agent (CPA). PMID:19460363

  11. Canonical fluid thermodynamics

    NASA Technical Reports Server (NTRS)

    Schmid, L. A.

    1972-01-01

    The space-time integral of the thermodynamic pressure plays the role of the thermodynamic potential for compressible, adiabatic flow in the sense that the pressure integral for stable flow is less than for all slightly different flows. This stability criterion can be converted into a variational minimum principle by requiring the molar free-enthalpy and the temperature, which are the arguments of the pressure function, to be generalized velocities, that is, the proper-time derivatives of scalar spare-time functions which are generalized coordinates in the canonical formalism. In a fluid context, proper-time differentiation must be expressed in terms of three independent quantities that specify the fluid velocity. This can be done in several ways, all of which lead to different variants (canonical transformations) of the same constraint-free action integral whose Euler-Lagrange equations are just the well-known equations of motion for adiabatic compressible flow.

  12. Revisiting Interpretation of Canonical Correlation Analysis: A Tutorial and Demonstration of Canonical Commonality Analysis

    ERIC Educational Resources Information Center

    Nimon, Kim; Henson, Robin K.; Gates, Michael S.

    2010-01-01

    In the face of multicollinearity, researchers face challenges interpreting canonical correlation analysis (CCA) results. Although standardized function and structure coefficients provide insight into the canonical variates produced, they fall short when researchers want to fully report canonical effects. This article revisits the interpretation of…

  13. Framing the Future: Revisiting the Place of Educational Expectations in Status Attainment

    ERIC Educational Resources Information Center

    Bozick, Robert; Alexander, Karl; Entwisle, Doris; Dauber, Susan; Kerr, Kerri

    2010-01-01

    This study revisits the Wisconsin model of status attainment from a life course developmental perspective. Fixed-effects regression analyses lend strong support to the Wisconsin framework's core proposition that academic performance and significant others' influence shape educational expectations. However, investigating the process of expectation…

  14. Service-Learning in Crisis Communication Education: Revisiting Coombs' Objectives for the Crisis Communication Course

    ERIC Educational Resources Information Center

    Maresh-Fuehrer, Michelle M.

    2015-01-01

    The purpose of this study was to revisit Coombs' suggestions for teaching the crisis communication course using service-learning as a framework. The author sought to assess the effectiveness of using this method in terms of the benefits to both students and the partnering organization and students' perceptions of whether they met the learning…

  15. Diatomics-in-Molecules Modeling of Many-Body Effects on the Structure and Thermodynamics of Mercury Clusters.

    PubMed

    Calvo, F; Pahl, E; Schwerdtfeger, P; Spiegelman, F

    2012-02-14

    The stable structures and melting behavior of Hgn clusters, 2 ≤ n < 60, have been theoretically investigated using an updated diatomics-in-molecules (DIM) model initially proposed by Kitamura [Chem. Phys. Lett.2006, 425, 2056]. Global optimization and sampling at finite temperature are achieved on the basis of hierarchical and nested Markov chain Monte Carlo methods, respectively. The DIM model predicts highly symmetric icosahedral global minima that are generally similar to the standard van der Waals atomic clusters, without any indication of distorted or low-coordinated geometries, but also at variance with the global minima found with the pairwise Hg2 potential. The combined influences of surface and many-body effects due to s-p mixing are considerable on the melting point: although the model predicts a bulk melting temperature in fair agreement with experimental results, it is found to decrease with increasing cluster size. PMID:26596612

  16. Contact symmetries and Hamiltonian thermodynamics

    SciTech Connect

    Bravetti, A.; Lopez-Monsalvo, C.S.; Nettel, F.

    2015-10-15

    It has been shown that contact geometry is the proper framework underlying classical thermodynamics and that thermodynamic fluctuations are captured by an additional metric structure related to Fisher’s Information Matrix. In this work we analyse several unaddressed aspects about the application of contact and metric geometry to thermodynamics. We consider here the Thermodynamic Phase Space and start by investigating the role of gauge transformations and Legendre symmetries for metric contact manifolds and their significance in thermodynamics. Then we present a novel mathematical characterization of first order phase transitions as equilibrium processes on the Thermodynamic Phase Space for which the Legendre symmetry is broken. Moreover, we use contact Hamiltonian dynamics to represent thermodynamic processes in a way that resembles the classical Hamiltonian formulation of conservative mechanics and we show that the relevant Hamiltonian coincides with the irreversible entropy production along thermodynamic processes. Therefore, we use such property to give a geometric definition of thermodynamically admissible fluctuations according to the Second Law of thermodynamics. Finally, we show that the length of a curve describing a thermodynamic process measures its entropy production.

  17. Modulation of DNA-polyamide interaction by β-alanine substitutions: a study of positional effects on binding affinity, kinetics and thermodynamics.

    PubMed

    Wang, Shuo; Aston, Karl; Koeller, Kevin J; Harris, G Davis; Rath, Nigam P; Bashkin, James K; Wilson, W David

    2014-10-14

    Hairpin polyamides (PAs) are an important class of sequence-specific DNA minor groove binders, and frequently employ a flexible motif, β-alanine (β), to reduce the molecular rigidity to maintain the DNA recognition register. To better understand the diverse effects that β can have on DNA-PA binding affinity, selectivity, and especially kinetics, which have rarely been reported, we have initiated a detailed study for an eight-heterocyclic hairpin PA and its β derivatives with their cognate and mutant sequences. With these derivatives, all internal pyrroles of the parent PA are systematically substituted with single or double βs. A set of complementary experiments have been conducted to evaluate the molecular interactions in detail: UV-melting, biosensor-surface plasmon resonance, circular dichroism and isothermal titration calorimetry. The β substitutions generally weaken the binding affinities of these PAs with cognate DNA, and have large and diverse influences on PA binding kinetics in a position- and number-dependent manner. The DNA base mutations have also shown positional effects on the binding of a single PA. Besides the β substitutions, the monocationic Dp group [3-(dimethylamino)propylamine] in parent PA has been modified into a dicationic Ta group (3,3'-diamino-N-methyldipropylamine) to minimize the frequently observed PA aggregation with ITC experiments. The results clearly show that the Ta modification not only maintains the DNA binding mode and affinity of PA, but also significantly reduces PA aggregation and allows the complete thermodynamic signature of eight-ring hairpin PA to be determined for the first time. This combined set of results significantly extends our understanding of the energetic basis of specific DNA recognition by PAs. PMID:25141096

  18. Effects of pulling forces, osmotic pressure, condensing agents and viscosity on the thermodynamics and kinetics of DNA ejection from bacteriophages to bacterial cells: a computational study

    NASA Astrophysics Data System (ADS)

    Petrov, Anton S.; Douglas, Scott S.; Harvey, Stephen C.

    2013-03-01

    In this work, we report on simulations of double-stranded DNA (dsDNA) ejection from bacteriophage ϕ29 into a bacterial cell. The ejection was studied with a coarse-grained model, in which viral dsDNA was represented by beads on a torsion-less string. The bacteriophage’s capsid and the bacterial cell were defined by sets of spherical constraints. To account for the effects of the viscous medium inside the bacterial cell, the simulations were carried out using a Langevin dynamics protocol. Our simplest simulations (involving constant viscosity and no external biasing forces) produced results compatible with the push-pull model of DNA ejection, with an ejection rate significantly higher in the first part of ejection than in the latter parts. Additionally, we performed more complicated simulations, in which we included additional factors such as external forces, osmotic pressure, condensing agents and ejection-dependent viscosity. The effects of these factors (independently and in combination) on the thermodynamics and kinetics of DNA ejection were studied. We found that, in general, the dependence of ejection forces and ejection rates on the amount of DNA ejected becomes more complex if the ejection is modeled with a broader, more realistic set of parameters and influences (such as variation in the solvent’s viscosity and the application of an external force). However, certain combinations of factors and numerical parameters led to the opposition of some ejection-driving and ejection-inhibiting influences, ultimately causing an apparent simplification of the ejection profiles.

  19. Modulation of DNA-Polyamide Interaction by β-alanine Substitutions: A Study of Positional Effects on Binding Affinity, Kinetics and Thermodynamics

    PubMed Central

    Wang, Shuo; Aston, Karl; Koeller, Kevin J.; Harris, G. Davis; Rath, Nigam P.

    2014-01-01

    Hairpin polyamides (PAs) are an important class of sequence-specific DNA minor groove binders, and frequently employ a flexible motif, β-alanine (β), to reduce the molecular rigidity to maintain the DNA recognition register. To better understand the diverse effects β can have on DNA-PA binding affinity, selectivity, and especially kinetics, which have rarely been reported, we have initiated a detailed study for an eight-heterocyclic hairpin PA and its β derivatives with their cognate and mutant sequences. With these derivatives, all internal pyrroles of the parent PA are systematically substituted with single or double βs. A set of complementary experiments have been conducted to evaluate the molecular interactions in detail: UV-melting, biosensor-surface plasmon resonance, circular dichroism and isothermal titration calorimetry. The β substitutions generally weaken the binding affinities of these PAs with cognate DNA, and have large and diverse influences on PA binding kinetics in a position- and number-dependent manner. The DNA base mutations have also shown positional effects on binding of a single PA. Besides the β substitutions, the monocationic Dp group [3-(dimethylamino) propylamine] in parent PA has been modified into a dicationic Ta group (3, 3'-Diamino-N-methyldipropylamine) to minimize the frequently observed PA aggregation with ITC experiments. The results clearly show that the Ta modification not only maintains the DNA binding mode and affinity of PA, but also significantly reduces PA aggregation and allows the complete thermodynamic signature of eight-ring hairpin PA to be determined for the first time. This combined set of results significantly extends our understanding of the energetic basis of specific DNA recognition by PAs. PMID:25141096

  20. The discovery of thermodynamics

    NASA Astrophysics Data System (ADS)

    Weinberger, Peter

    2013-07-01

    Based on the idea that a scientific journal is also an "agora" (Greek: market place) for the exchange of ideas and scientific concepts, the history of thermodynamics between 1800 and 1910 as documented in the Philosophical Magazine Archives is uncovered. Famous scientists such as Joule, Thomson (Lord Kelvin), Clausius, Maxwell or Boltzmann shared this forum. Not always in the most friendly manner. It is interesting to find out, how difficult it was to describe in a scientific (mathematical) language a phenomenon like "heat", to see, how long it took to arrive at one of the fundamental principles in physics: entropy. Scientific progress started from the simple rule of Boyle and Mariotte dating from the late eighteenth century and arrived in the twentieth century with the concept of probabilities. Thermodynamics was the driving intellectual force behind the industrial revolution, behind the enormous social changes caused by this revolution. The history of thermodynamics is a fascinating story, which also gives insights into the mechanism that seem to govern science.

  1. Radiative processes and non-equilibrium thermodynamics

    NASA Astrophysics Data System (ADS)

    Callies, U.; Herbert, F.

    1988-03-01

    With the assumption of an elementary physical concept meteorologically effective radiative processes (absorption-emission, scattering) can be included consistently in nonequilibrium thermodynamics of irreversible phenomena. Analogously to the usual Gibbs relations a fundamental equation was formulated for monochromatic light rays as the nucleus of the theory. Using the methods of classical irreversible theory, a complete entropy balance equation is derived in which the entropy variations of the mass as well as of the radiation field are explicitly represented. The resulting entropy source strength function σ through its analytical structure reveals the dynamical character of the irreversible variation terms. The σ-expression being positive according to the second law of thermodynamics is found to have a bilinear form as a function of the irreversible fluxes representing the entropy generating radiative processes and their conjugated thermodynamic forces. The mathematical structure and the positive sign of σ, following the usual line of reasoning, motivate the assumption of constitutive relations for the irreversible radiative processes. These equations developed from purely thermodynamical reasoning turn out to be equivalent to the usual radiative transfer equation which is founded on a very different theoretical concept. A very fundamental relationship can be deduced in this context from the entropy production function. It provides a direct thermodynamical proof that in nonscattering media the definition of a local temperature is necessarily accompanied by the validity of the Kirchhoff law.

  2. The thermodynamics of simple biomembrane mimetic systems

    PubMed Central

    Raudino, Antonio; Sarpietro, Maria Grazia; Pannuzzo, Martina

    2011-01-01

    Insight into the forces governing a system is essential for understanding its behavior and function. Thermodynamic investigations provide a wealth of information that is not, or is hardly, available from other methods. This article reviews thermodynamic approaches and assays to measure collective properties such as heat adsorption / emission and volume variations. These methods can be successfully applied to the study of lipid vesicles (liposomes) and biological membranes. With respect to instrumentation, differential scanning calorimetry, pressure perturbation calorimetry, isothermal titration calorimetry, dilatometry, and acoustic techniques aimed at measuring the isothermal and adiabatic processes, two- and three-dimensional compressibilities are considered. Applications of these techniques to lipid systems include the measurement of different thermodynamic parameters and a detailed characterization of thermotropic, barotropic, and lyotropic phase behavior. The membrane binding and / or partitioning of solutes (proteins, peptides, drugs, surfactants, ions, etc.) can also be quantified and modeled. Many thermodynamic assays are available for studying the effect of proteins and other additives on membranes, characterizing non-ideal mixing, domain formation, bilayer stability, curvature strain, permeability, solubilization, and fusion. Studies of membrane proteins in lipid environments elucidate lipid–protein interactions in membranes. Finally, a plethora of relaxation phenomena toward equilibrium thermodynamic structures can be also investigated. The systems are described in terms of enthalpic and entropic forces, equilibrium constants, heat capacities, partial volume changes, volume and area compressibility, and so on, also shedding light on the stability of the structures and the molecular origin and mechanism of the structural changes. PMID:21430953

  3. Efficiencies of thermodynamics when temperature-dependent energy levels exist.

    PubMed

    Yamano, Takuya

    2016-03-14

    Based on a generalized form of the second law of thermodynamics, in which the temperature-dependent energy levels of a system are appropriately included in entropy generation, we show that the effect reasonably appears in efficiencies of thermodynamic processes. PMID:26890276

  4. Natural family planning revisited.

    PubMed

    Al-Ateeg, Fahad A

    2004-03-01

    The article focuses on the role of natural family planning NFP as a component of reproductive health. It distinguishes NFP from the concept of fertility awareness method. Furthermore, the effectiveness of NFP as determined by previous studies is presented and the advantages and disadvantages of NFP are highlighted. Additionally, factors that influence the use of NFP methods are examined. Finally, delivery strategies and options for mainstreaming NFP into reproductive health services are identified and discussed. PMID:15048163

  5. Vitamin C revisited.

    PubMed

    Oudemans-van Straaten, Heleen M; Spoelstra-de Man, Angelique Me; de Waard, Monique C

    2014-01-01

    This narrative review summarizes the role of vitamin C in mitigating oxidative injury-induced microcirculatory impairment and associated organ failure in ischemia/reperfusion or sepsis. Preclinical studies show that high-dose vitamin C can prevent or restore microcirculatory flow impairment by inhibiting activation of nicotinamide adenine dinucleotide phosphate-oxidase and inducible nitric oxide synthase, augmenting tetrahydrobiopterin, preventing uncoupling of oxidative phosphorylation, and decreasing the formation of superoxide and peroxynitrite, and by directly scavenging superoxide. Vitamin C can additionally restore vascular responsiveness to vasoconstrictors, preserve endothelial barrier by maintaining cyclic guanylate phosphatase and occludin phosphorylation and preventing apoptosis. Finally, high-dose vitamin C can augment antibacterial defense. These protective effects against overwhelming oxidative stress due to ischemia/reperfusion, sepsis or burn seems to mitigate organ injury and dysfunction, and promote recovery after cardiac revascularization and in critically ill patients, in the latter partially in combination with other antioxidants. Of note, several questions remain to be solved, including optimal dose, timing and combination of vitamin C with other antioxidants. The combination obviously offers a synergistic effect and seems reasonable during sustained critical illness. High-dose vitamin C, however, provides a cheap, strong and multifaceted antioxidant, especially robust for resuscitation of the circulation. Vitamin C given as early as possible after the injurious event, or before if feasible, seems most effective. The latter could be considered at the start of cardiac surgery, organ transplant or major gastrointestinal surgery. Preoperative supplementation should consider the inhibiting effect of vitamin C on ischemic preconditioning. In critically ill patients, future research should focus on the use of short-term high-dose intravenous vitamin

  6. Boundary lubrication: Revisited

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.

    1982-01-01

    A review of the various lubrication regimes, with particular, emphasis on boundary lubrication, is presented. The types of wear debris and extent of surface damage is illustrated for each regime. The role of boundary surface films along with their modes of formation and important physical properties are discussed. In addition, the effects of various operating parameters on friction and wear in the boundary lubrication regime are considered.

  7. Disentanglement of growth dynamic and thermodynamic effects in LaAlO3/SrTiO3 heterostructures

    PubMed Central

    Xu, Chencheng; Bäumer, Christoph; Heinen, Ronja Anika; Hoffmann-Eifert, Susanne; Gunkel, Felix; Dittmann, Regina

    2016-01-01

    The influence of non-equilibrium and equilibrium processes during growth of LaAlO3/SrTiO3 (LAO/STO) heterostructures is analyzed. We investigate the electronic properties of LAO/STO heterostructures obtained at constant growth conditions after annealing in different oxygen atmospheres within the typical growth window (1 × 10−4 mbar –1 × 10−2 mbar). The variation of annealing conditions is found to cause a similar change of electronic properties as observed for samples grown in different oxygen pressure. The results indicate that equilibrium defect formation is the dominant process for establishing the properties of the two-dimensional electron gas (2DEG), while growth dynamics play a minor role in the typical LAO/STO growth regime. Furthermore, the effects of non-equilibrium processes occurring during growth are investigated in detail by quenching just-grown LAO/STO heterostructures directly after growth. We show that during growth the sample is pushed into a non-equilibrium state. After growth, the sample then relaxes towards equilibrium, while the relaxation rate strongly depends on the ambient pressure. The observed relaxation behavior is mainly associated with a reoxidation of the STO bulk, while the 2DEG is formed immediately after the growth. PMID:27009359

  8. Effect of 1,10-phenanthroline aromaticity in carboxylic acids:1H NMR spectroscopy, GIAO calculations and thermodynamic properties

    NASA Astrophysics Data System (ADS)

    Machado, Camila M. B.; Santos, Vanessa F. C.; Belarmino, Marcia K. D. L.; França, José A. A.; Moura, Gustavo L. C.; Lima, Nathalia B. D.

    2016-08-01

    Hydrogen bonding represents a class of chemical interactions, which are directly responsible for several physical properties, such as: energetic stabilities, boiling points, vibrational modes, bond lengths, etc. In this article, we examine from the point of view of 1H NMR spectroscopy and GIAO calculations, the effects associated with the process of formation of the hydrogen bonds as they appear in the chemical shifts of the acidic hydrogens in the complexes between nitrogenated compounds, PHEN, BIPY and DIBIPY, and carboxylic acids, HOOCH, HOOCCH3 and HOOCC6H5. All computational simulations were performed using the quantum chemical methods B3LYP/6-31++G(d,p) and ωB97X-D/def2-TZVP. The 1H NMR spectroscopy results showed that, in both cases, the hydrogen nucleus of the OH group is the most affected in the process of hydrogen bond formation. For the complexes involving PHEN we observed that the hydrogen nucleus is more strongly shielded when compared with this signal in the corresponding complexes involving BIPY and DIBIPY.

  9. Thermodynamic analysis of polydispersity in ionic micellar systems and its effect on small-angle neutron scattering data treatment

    SciTech Connect

    Sheu, E.Y.; Chen, S.H.

    1988-07-28

    The authors analyze small-angle neutron scattering (SANS) data of sodium dodecyl sulfate (SDS) and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) ionic micellar solutions taking into account the effect of size polydispersity on the particle form factor. The intermicellar structure factor is computed by a generalized one-component macroion theory (GOCM) assuming a constant fractional charge. The model fittings to SANS data for different concentrations allow us to extract the free energy parameters of micelle formation and growth, the size distribution function of micelles, and the minimum micelle size which is consistent with the fully stretched hydrocarbon tail lengths of the surfactant molecules. The critical micellar concentration (cmc) is predicted from the free energy parameters correctly. Combining the free energy of micelle formation with the double-layer free energy around the averaged micellar surface calculated by the nonlinear Poisson-Boltzmann equation, they obtain the hydrophobic free energy of micellization which is in quantitative agreement with the literature value. These analyses confirm the applicability of the ladder model of micellar growth in salt free ionic micellar solutions at moderate concentrations. The degree of polydispersity in size is about 11% for 2% SDS solution at 40/degrees/C and 17% for 1% AOT at 22.6/degrees/C.

  10. Secret Public Key Protocols Revisited

    NASA Astrophysics Data System (ADS)

    Lim, Hoon Wei; Paterson, Kenneth G.

    Password-based protocols are important and popular means of providing human-to-machine authentication. The concept of secret public keys was proposed more than a decade ago as a means of securing password-based authentication protocols against off-line password guessing attacks, but was later found vulnerable to various attacks. In this paper, we revisit the concept and introduce the notion of identity-based secret public keys. Our new identity-based approach allows secret public keys to be constructed in a very natural way using arbitrary random strings, eliminating the structure found in, for example, RSA or ElGamal keys. We examine identity-based secret public key protocols and give informal security analyses, indicating that they are secure against off-line password guessing and other attacks.

  11. Extended equal area criterion revisited

    SciTech Connect

    Xue, X.; Wehenkel, L.; Belhomme, R.; Rousseaux, P.; Pavella, M. ); Euxibie, E.; Heilbronn, B.; Lesigne, J.F. )

    1992-08-01

    This paper reports on a case study conducted on the EHV French power system in order to revisit the extended equal area criterion and test its suitability as a fast transient stability indicator. The assumptions underlying the method are reexamined, causes liable to invalidate them are identified, and indices are devised to automatically circumvent them. The selection of candidate critical machines is also reconsidered and an augmented criterion is proposed. The various improvements are developed and tested on about 1000 stability scenarios, covering the entire 400-kV system; the severity of the scenarios, resulting from the combination of weakened both pre- and post-fault configurations, subjects the method to particularly stringent conditions. The obtained results show that the devised tools contribute to significantly reinforce its robustness and reliability.

  12. Conformational transitions of duplex and triplex nucleic acid helices: thermodynamic analysis of effects of salt concentration on stability using preferential interaction coefficients.

    PubMed Central

    Bond, J. P.; Anderson, C. F.; Record, M. T.

    1994-01-01

    For order-disorder transitions of double- and triple-stranded nucleic acid helices, the midpoint temperatures Tm depend strongly on a +/-, the mean ionic activity of uniunivalent salt. Experimental determinations of dTm/d ln a +/- and of the enthalpy change (delta H(o)) accompanying the transition in excess salt permit evaluation of delta gamma, the stoichiometrically weighted combination of preferential interaction coefficients, each of which reflects thermodynamic effects of interactions of salt ions with a reactant or product of the conformational transition (formula; see text) Here delta H(o) is defined per mole of nucleotide by analogy to delta gamma. Application of Eq. 1 to experimental values of delta H(o) and Tm yields values of delta gamma for the denaturation of B-DNA over the range of NaCl concentrations 0.01-0.20 M (Privalov et al. (1969), Biopolymers 8,559) and for each of four order-disorder transitions of poly rA.(poly rU)n, n = 1, 2 over the range of NaCl concentrations 0.01-1.0 M (Krakauer and Sturtevant (1968), Biopolymers 6, 491). For denaturation of duplexes and triplexes, delta gamma is negative and not significantly dependent on a +/-, but delta gamma is positive and dependent on a +/- for the disproportionation transition of poly rA.poly rU duplexes. Quantitative interpretations of these trends and magnitudes of delta gamma in terms of coulombic and excluded volume effects are obtained by fitting separately each of the two sets of thermodynamic data using Eq. 1 with delta gamma PB evaluated from the cylindrically symmetric Poisson-Boltzmann (PB) equation for a standard model of salt-polyelectrolyte solutions. The only structural parameters required by this model are: b, the mean axial distance between the projections of adjacent polyion charges onto the cylindrical axis; and a, the mean distance of closest approach between a salt ion center and the cylindrical axis. Fixing bMS and aMS for the multi-stranded (ordered) conformations, we

  13. Thermodynamic significance of human basal metabolism

    NASA Astrophysics Data System (ADS)

    Wang, Cuncheng

    1993-06-01

    The human basal state, a non-equilibrium steady state, is analysed in this paper in the light of the First and Second Laws of Thermodynamics whereby the thermodynamic significance of the basal metabolic rate and its distinction to the dissipation function and exergy loss are identified. The analysis demonstrates the correct expression of the effects of the blood flow on the heat balance in a human-body bio-heat model and the relationship between the basal metabolic rate and the blood perfusion.

  14. Drought Definitions Revisited

    NASA Astrophysics Data System (ADS)

    Van Loon, A.; Van Lanen, H.; Gleeson, T.

    2014-12-01

    Drought is commonly defined as a temporary lack of water compared to normal conditions. In the traditional definition used in the natural sciences (climate science, hydrology, earth science) only natural drivers are included and the human effect on water resources is excluded. Drought impact studies, however, using observed crop yields, wildfire data, reservoir information, etc., can hardy make this division. The interdisciplinarity of drought asks for a broader definition that considers the interplay between the hazard, impacts and management. In the IPCC-SREX report definitional issues are mentioned as one of the reasons that no clear conclusions can be drawn about historic and future changes in drought. Human activities related to drought are mentioned by IPCC, but not included in their definition of drought. In the anthropocene the human aspects of drought can no longer be neglected. The IAHS Panta Rhei initiative, for example, urges hydrologists to include the connection with human systems. We propose a paradigm shift in the definition of drought, namely to expand it to include the effects of human action. For attribution we can then distinguish between climate-induced drought and human-induced drought. In this presentation, we will present a conceptual diagram that will do justice to the interdisciplinarity of drought. We will discuss issues of variability and change, scale (both temporal and spatial scales), feedbacks, and direct and indirect anthropogenic effects. The revised definition provides recognition and a common ground to researchers in all fields of research and is better aligned with drought impacts and with stakeholders' and policy maker's views on drought.

  15. Strong Poison Revisited

    SciTech Connect

    Prince, R.C.; Gailer, J.; Gunson, D.E.; Turner, R.J.; George, G.N.; Pickering, I.J.

    2009-06-04

    Selenium in the form of selenocysteine plays an essential role in a number of proteins, but its role in non-enzymatic biochemistry is also important. In this short review we discuss the interactions between inorganic selenium, arsenic and mercury under physiological conditions, especially in the presence of glutathione. This chemistry is obviously important in making the arsenic and mercury unavailable for more toxic interactions, but in the process it suggests that a side-effect of chronic arsenic and/or mercury exposure is likely to be functional selenium deficiency.

  16. Hyperbranched polymer stars with Gaussian chain statistics revisited.

    PubMed

    Polińska, P; Gillig, C; Wittmer, J P; Baschnagel, J

    2014-02-01

    Conformational properties of regular dendrimers and more general hyperbranched polymer stars with Gaussian statistics for the spacer chains between branching points are revisited numerically. We investigate the scaling for asymptotically long chains especially for fractal dimensions df = 3 (marginally compact) and df = 2.5 (diffusion limited aggregation). Power-law stars obtained by imposing the number of additional arms per generation are compared to truly self-similar stars. We discuss effects of weak excluded-volume interactions and sketch the regime where the Gaussian approximation should hold in dense solutions and melts for sufficiently large spacer chains. PMID:24574057

  17. Onsager-Casimir relations revisited

    SciTech Connect

    Hubmer, G.F.; Titulaer, U.M.

    1987-10-01

    The authors study the fate of the Onsager-Casimir reciprocity relations for a continuous system when some of its variables are eliminated adiabatically. Just as for discrete systems, deviations appear in correction terms to the reduced evolution equation that are of higher order in the time scale ratio. The deviations are not removed by including correction terms to the coarse-grained thermodynamic potential. However, via a reformulation of the theory, in which the central role of the thermodynamic potential is taken over by an associated Lagrangian-type expression, they arrive at a modified form of the Onsager-Casimir relations that survives the adiabatic elimination procedure. There is a simple relation between the time evolution of the redefined thermodynamic forces and that of the basic thermodynamic variables; this relation also survives the adiabatic elimination. The formalism is illustrated by explicit calculations for the Klein-Kramers equation, which describes the phase space distribution of Brownian particles, and for the corrected Smoluchowski equation derived from it by adiabatic elimination of the velocity variable. The symmetry relation for the latter leads to a simple proof that the reality of the eigenvalues of the simple Smoluchowski equation is not destroyed by the addition of higher order corrections, at least not within the framework of a formal perturbation expansion in the time scale ratio.

  18. The recombination epoch revisited

    NASA Technical Reports Server (NTRS)

    Krolik, Julian H.

    1989-01-01

    Previous studies of cosmological recombination have shown that this process produces as a by-product a highly superthermal population of Ly-alpha photons which retard completion of recombination. Cosmological redshifting was thought to determine the frequency distribution of the photons, while two-photon decay of hydrogen's 2s state was thought to control their numbers. It is shown here that frequency diffusion due to photon scattering dominate the cosmological redshift in the frequency range near line center which fixes the ratio of ground state to excited state population, while incoherent scattering into the far-red damping wing effectively destroys Ly-alpha photons as a rate which is competitive with two-photon decay. The former effect tends to hold back recombination, while the latter tends to accelerate it; the net results depends on cosmological parameters, particularly the combination Omega(b) h/sq rt (2q0), where Omega(b) is the fraction of the critical density provided by baryons.

  19. The effect of water on the physical and thermodynamic properties of calc-alkaline basalt and basaltic andesite

    NASA Astrophysics Data System (ADS)

    Robert, G.; Whittington, A. G.; Stechern, A.; Behrens, H.

    2013-12-01

    We present corresponding viscosity and heat capacity data obtained on a series of hydrated glasses and supercooled melts for Fe-free calc-alkaline basaltic (sb, NBO/T = 0.67) and basaltic andesite analogues (sba, NBO/T = 0.40). Water contents range from nominally anhydrous to 3.76 wt.% H2O. Density measurements on relaxed (1 atm) hydrous glasses (post-viscometry) yield a partial molar volume of H2O of 12.9 and of 11.4 cm3mol-1 for sba and sb, respectively. Viscosity data were obtained at temperatures in the neighbourhood of the glass transition using the parallel-plate method, and at superliquidus temperatures using the concentric-cylinder and falling-sphere methods. The effect of water on viscosity is most dramatic at low temperatures, with the addition of ~2 wt.% H2O resulting in a reduction of the temperature at which the viscosity of the melt is 1012 Pa s (T12) of 170-180°C. The viscosity of a calc-alkaline basaltic andesite magma with 2 wt.% H2O at depth would increase by a factor of ~100 upon complete degassing during ascent. Calorimetric measurements were made with a Perkin-Elmer 8500 Differential Scanning Calorimeter up to 750°C, the limit of the instrument, depending on the sample water content. The increase in heat capacity associated with the transition from a glass to a supercooled liquid is on the order of ~25-30% and is higher in magnitude the more depolymerized the liquid. Our preliminary results suggest that the heat capacity of the hydrous sba and sb liquids decreases with increasing temperature immediately above the glass transition, similar to borosilicate and titanosilicate melts. In the anhydrous titano- and boro-silicate melts, this anomalous behaviour was linked to T-dependent mixing of B or Ti with Si. In sb and sba, the observed decrease in configurational heat capacity with increasing temperature may be related to the interplay of 'polymerizing' (viscosity-increasing) vs. 'depolymerizing' (viscosity-decreasing) solution mechanisms of

  20. Thermodynamically based DNA strand design

    PubMed Central

    Tulpan, Dan; Andronescu, Mirela; Chang, Seo Bong; Shortreed, Michael R.; Condon, Anne; Hoos, Holger H.; Smith, Lloyd M.

    2005-01-01

    We describe a new algorithm for design of strand sets, for use in DNA computations or universal microarrays. Our algorithm can design sets that satisfy any of several thermodynamic and combinatorial constraints, which aim to maximize desired hybridizations between strands and their complements, while minimizing undesired cross-hybridizations. To heuristically search for good strand sets, our algorithm uses a conflict-driven stochastic local search approach, which is known to be effective in solving comparable search problems. The PairFold program of Andronescu et al. [M. Andronescu, Z. C. Zhang and A. Condon (2005) J. Mol. Biol., 345, 987–1001; M. Andronescu, R. Aguirre-Hernandez, A. Condon, and H. Hoos (2003) Nucleic Acids Res., 31, 3416–3422.] is used to calculate the minimum free energy of hybridization between two mismatched strands. We describe new thermodynamic measures of the quality of strand sets. With respect to these measures of quality, our algorithm consistently finds, within reasonable time, sets that are significantly better than previously published sets in the literature. PMID:16145053