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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.

  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.

  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. Quantum-thermodynamic treatment of intrinsic anharmonicity; Wallace's theorem revisited

    NASA Astrophysics Data System (ADS)

    Jacobs, Michel H. G.; de Jong, Bernard H. W. S.

    2005-12-01

    Wallace (in Thermodynamics of crystals, 1972) developed a theorem, rooted in rigid lattice dynamics, which incorporates intrinsic anharmonic effects in solids. The practical application of this theorem in mineral physics is computationally involved and this is the main reason for the theorem not getting the attention it deserves. Because intrinsic anharmonicity is an important issue at the extreme conditions in planetary mantles, we derived a method which removes the computational obstacles in applying this theorem. We extended the theorem to incorporate details of the phonon spectrum and tested our algorithm on forsterite (Mg2SiO4). Using a least squares inversion technique applied to all available experimental data, we show that it results in an accurate representation of thermodynamic properties and sound wave velocities of Mg2SiO4 in its complete pressure-temperature stability range. We also show that the accuracy of our results is not significantly affected by the use of a different equation of state.

  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. Revisiting the fundamental physical chemistry in heterogeneous photocatalysis: its thermodynamics and kinetics.

    PubMed

    Ohtani, Bunsho

    2014-02-01

    Although the history of photocatalysis research is not so long, many researchers have studied photocatalysis and a large number of papers on photocatalysis have been published. The objectives of this review paper are to revisit the fundamentals of photocatalysis, especially its thermodynamics and kinetics, which have not been reexamined in recent studies, to clarify the problems, if any, that prevent developments in the field of photocatalysis, and to present insights for future progress.

  8. The lisse effect revisited

    USGS Publications Warehouse

    Weeks, E.P.

    2002-01-01

    The Lisse effect is a rarely noted phenomenon occurring when infiltration caused by intense rain seals the surface soil layer to airflow, trapping air in the unsaturated zone. Compression of air by the advancing front results in a pressure increase that produces a water-level rise in an observation well screened below the water table that is several times as large as the distance penetrated by the wetting front. The effect is triggered by intense rains and results in a very rapid water-level rise, followed by a recession lasting a few days. The Lisse effect was first noted and explained by Thal Larsen in 1932 from water-level observations obtained in a shallow well in the village of Lisse, Holland. The original explanation does not account for the increased air pressure pushing up on the bottom of the wetting front. Analysis of the effect of this upward pressure indicates that a negative pressure head at the base of the wetting front, ??f, analogous to that postulated by Green and Ampt (1911) to explain initially rapid infiltration rates into unsaturated soils, is involved in producing the Lisse effect. Analysis of recorded observations of the Lisse effect by Larsen and others indicates that the water-level rise, which typically ranges from 0.10 to 0.55 m, should be only slightly larger than |??f| and that the depth of penetration of the wetting front is no more than several millimeters.

  9. Comment on the Article ``Relativistic Non-Equilibrium Thermodynamics Revisited''

    NASA Astrophysics Data System (ADS)

    Muschik, Wolfgang; von Borzeszkowski, Horst-Heino

    2007-05-01

    There are two problematic items in García-Colín and Sandoval-Villalbazo's approach to “relativistic non-equilibrium thermodynamics” (L.S. García- Colín and A. Sandoval-Villalbazo, J. Non-Equilib. Thermodyn. 31, 2006, pp. 11-22). The paper does not follow the fundamentals of relativity theory; according to them, the energy-momentum tensor (EMT) has to include all energies of the considered system. Secondly, strange thermodynamic consequences result by using the presuppositions made by the authors. The paper is critically discussed and some shortcomings are elucidated.

  10. 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.

  11. The Thermodynamics of Marine Biogeochemical Cycles: Lotka Revisited.

    PubMed

    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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. Foregrounding Effects during Reading, Revisited

    ERIC Educational Resources Information Center

    Cook, Anne E.; Gueraud, Sabine; Was, Christopher A.; O'Brien, Edward J.

    2007-01-01

    Previous researchers have argued that objects associated with a protagonist may be foregrounded, or held active, in memory. This study expanded on previous work by using an inconsistency paradigm to investigate the effects of protagonist association on object accessibility. Readers experienced more processing difficulty when a target sentence…

  17. 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

  18. Revisiting the survival mnemonic effect in children.

    PubMed

    Pand eirada, Josefa N S; Pires, Luísa; Soares, Sandra C

    2014-01-01

    The survival processing paradigm is designed to explore the adaptive nature of memory functioning. The mnemonic advantage of processing information in fitness-relevant contexts, as has been demonstrated using this paradigm, is now well established, particularly in young adults; this phenomenon is often referred to as the "survival processing effect." In the current experiment, we revisited the investigation of this effect in children and tested it in a new cultural group, using a procedure that differs from the existing studies with children. A group of 40 Portuguese children rated the relevance of unrelated words to a survival and a new moving scenario. This encoding task was followed by a surprise free-recall task. Akin to what is typically found, survival processing produced better memory performance than the control condition (moving). These data put on firmer ground the idea that a mnemonic tuning to fitness-relevant encodings is present early in development. The theoretical importance of this result to the adaptive memory literature is discussed, as well as potential practical implications of this kind of approach to the study of memory in children.

  19. 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…

  20. 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,…

  1. Anammox revisited: thermodynamic considerations in early studies of the microbial nitrogen cycle.

    PubMed

    Oren, Aharon

    2015-08-01

    This paper explores the early literature on the thermodynamics of processes in the microbial nitrogen cycle, evaluating parameters of transfer of energy which depends on the initial and final states of the system, the mechanism of the reactions involved and the rates of these reactions. Processes discussed include the anaerobic oxidation of ammonium (the anammox reaction), the use of inorganic nitrogen compounds as electron donors for anoxygenic photosynthesis, and the mechanism and bioenergetics of biological nitrogen fixation.

  2. Allowance for thermodynamic non-ideality in the characterization of protein self-association by frontal exclusion chromatography: hemoglobin revisited.

    PubMed

    Winzor, Donald J; Wills, Peter R

    2003-05-01

    This investigation re-examines theoretical aspects of the allowance for effects of thermodynamic non-ideality on the characterization of protein self-association by frontal exclusion chromatography, and thereby provides methods of analysis with greater thermodynamic rigor than those used previously. Their application is illustrated by reappraisal of published exclusion chromatography data for hemoglobin on the controlled-pore-glass matrix CPG-120. The equilibrium constant of 100/M that is obtained for dimerization of the alpha(2)beta(2) species by this means is also deduced from re-examination of published studies of concentrated hemoglobin solutions by osmotic pressure and sedimentation equilibrium methods. PMID:12834853

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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

  8. Thermodynamic theory of the plasmoelectric effect

    DOE PAGES

    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

  9. 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.

  10. 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

  11. 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.

  12. The effect of time ordering revisited

    SciTech Connect

    Rosato, J.; Boland, D.; Capes, H.; Marandet, Y.; Stamm, R.

    2008-10-22

    The effects of time ordering on line shapes are investigated for the dynamic ionic broadening of the Lyman alpha line in hydrogen plasmas. The difference between calculations with and without time ordering is calculated for an electric field created by a single particle, and for a thermal average over plasma configurations with moderate temperature and density.

  13. 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.

  14. Revisiting heritability accounting for shared environmental effects and maternal inheritance.

    PubMed

    Liu, Chunyu; Dupuis, Josée; Larson, Martin G; Cupples, L Adrienne; Ordovas, Jose M; Vasan, Ramachandran S; Meigs, James B; Jacques, Paul F; Levy, Daniel

    2015-02-01

    Heritability measures the proportion of phenotypic variation attributable to genetic factors. In addition to a shared nuclear genetic component, a number of additional variance components, such as spousal correlation, sibship, household and maternal effects, may have strong contributions to inter-individual phenotype variation. In humans, the confounding effects of these components on heritability have not been studied thoroughly. We sought to obtain unbiased heritability estimates for complex traits in the presence of multiple variance components and also to estimate the contributions of these variance components to complex traits. We compared regression and variance component methods to estimate heritability in simulations when additional variance components existed. We then revisited heritability for several traits in Framingham Heart Study (FHS) participants. Using simulations, we found that failure to account for or misclassification of necessary variance components yielded biased heritability estimates. The direction and magnitude of the bias varied depending on a variance structure and an estimation method. Using the best fitted models to account for necessary variance components, we found that heritability estimates for most FHS traits were overestimated, ranging from 4 to 47 %, when we compared models that considered necessary variance components to models that only considered familial relationships. Spousal correlation explained 14-36 % of phenotypic variation in several anthropometric and lifestyle traits. Maternal and sibling effects also contributed to phenotypic variation, ranging from 3 to 5 % and 4 to 7 %, respectively, in several anthropometric and metabolic traits. Our findings may explain, in part, the missing heritability for some traits.

  15. Landauer's blowtorch effect as a thermodynamic cross process: Brownian cooling.

    PubMed

    Das, Moupriya; Das, Debojyoti; Barik, Debashis; Ray, Deb Shankar

    2015-11-01

    The local heating of a selected region in a double-well potential alters the relative stability of the two wells and gives rise to an enhancement of population transfer to the cold well. We show that this Landauer's blowtorch effect may be considered in the spirit of a thermodynamic cross process linearly connecting the flux of particles and the thermodynamic force associated with the temperature difference and consequently ensuring the existence of a reverse cross effect. This reverse effect is realized by directing the thermalized particles in a double-well potential by application of an external bias from one well to the other, which suffers cooling. PMID:26651642

  16. 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.

  17. 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.

  18. Stochastic dynamics and non-equilibrium thermodynamics of a bistable chemical system: the Schlögl model revisited.

    PubMed

    Vellela, Melissa; Qian, Hong

    2009-10-01

    Schlögl's model is the canonical example of a chemical reaction system that exhibits bistability. Because the biological examples of bistability and switching behaviour are increasingly numerous, this paper presents an integrated deterministic, stochastic and thermodynamic analysis of the model. After a brief review of the deterministic and stochastic modelling frameworks, the concepts of chemical and mathematical detailed balances are discussed and non-equilibrium conditions are shown to be necessary for bistability. Thermodynamic quantities such as the flux, chemical potential and entropy production rate are defined and compared across the two models. In the bistable region, the stochastic model exhibits an exchange of the global stability between the two stable states under changes in the pump parameters and volume size. The stochastic entropy production rate shows a sharp transition that mirrors this exchange. A new hybrid model that includes continuous diffusion and discrete jumps is suggested to deal with the multiscale dynamics of the bistable system. Accurate approximations of the exponentially small eigenvalue associated with the time scale of this switching and the full time-dependent solution are calculated using Matlab. A breakdown of previously known asymptotic approximations on small volume scales is observed through comparison with these and Monte Carlo results. Finally, in the appendix section is an illustration of how the diffusion approximation of the chemical master equation can fail to represent correctly the mesoscopically interesting steady-state behaviour of the system.

  19. 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.

  20. 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.

  1. 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…

  2. 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…

  3. 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.

  4. Non-equilibrium Thermodynamics of the Longitudinal Spin Seebeck Effect

    NASA Astrophysics Data System (ADS)

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

    In this paper we employ non equilibrium thermodynamics of fluxes and forces to describe magnetization and heat transport. By the theory we are able to identify the thermodynamic driving force of the magnetization current as the gradient of the effective field ▿H*. This definition permits to define the spin Seebeck coefficient ɛM which relates ▿H* and the temperature gradient ▿T. By applying the theory to the geometry of the longitudinal spin Seebeck effect we are able to obtain the optimal conditions for generating large magnetization currents. Furthermore, by using the results of recent experiments, we obtain an order of magnitude for the value of ɛM ∼ 10-2 TK-1 for yttrium iron garnet (Y3Fe5O12).

  5. 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.

  6. A theoretical investigation of thermodynamic effects on developed cavitation

    NASA Technical Reports Server (NTRS)

    Weir, D. S.

    1976-01-01

    The results of a theoretical investigation of thermodynamic effects on developed cavitation are presented. An approximate solution to the conservation equations for a two-phase laminar boundary layer is obtained. This analysis produces an expression for the temperature difference between the liquid and vapor phases which can be applied to developed cavity flows. Experimental data of cavity temperature depressions are correlated using this result. In addition, a theoretical estimate of the Nusselt number for the cavity is made using a turbulent boundary layer cavity model proposed by Brennen. The result agrees in part with empirically determined expressions for the cavity Nusselt number.

  7. 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.

  8. 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.

  9. Colavita dominance effect revisited: the effect of semantic congruity.

    PubMed

    Stubblefield, Alexandra; Jacobs, Lauryn A; Kim, Yongju; Goolkasian, Paula

    2013-11-01

    To investigate the effect of semantic congruity on audiovisual target responses, participants detected a semantic concept that was embedded in a series of rapidly presented stimuli. The target concept appeared as a picture, an environmental sound, or both; and in bimodal trials, the audiovisual events were either consistent or inconsistent in their representation of a semantic concept. The results showed faster detection latencies to bimodal than to unimodal targets and a higher rate of missed targets when visual distractors were presented together with auditory targets, in comparison to auditory targets presented alone. The findings of Experiment 2 showed a cross-modal asymmetry, such that visual distractors were found to interfere with the accuracy of auditory target detection, but auditory distractors had no effect on either the speed or the accuracy of visual target detection. The biased-competition theory of attention (Desimone & Duncan Annual Review of Neuroscience 18: 1995; Duncan, Humphreys, & Ward Current Opinion in Neurobiology 7: 255-261 1997) was used to explain the findings because, when the saliency of the visual stimuli was reduced by the addition of a noise filter in Experiment 4, visual interference on auditory target detection was diminished. Additionally, the results showed faster and more accurate target detection when semantic concepts were represented in a visual rather than an auditory format.

  10. 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.

  11. 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 .

  12. Revisiting the Passerini reaction mechanism: existence of the nitrilium, organocatalysis of its formation, and solvent effect.

    PubMed

    Ramozzi, Romain; Morokuma, Keiji

    2015-06-01

    The Passerini reaction mechanism is revisited using high-level DFT calculations. Contrary to the common belief, the nitrilium intermediate is found to be stable in solution and its formation is rate-determining. The present results point out that this step is catalyzed by a second carboxylic acid molecule, as the subsequent Mumm rearrangement is. The solvent effect on the reaction rate was investigated. In a protic solvent like methanol, hydrogen bonds are responsible of the increasing barrier of the rate-determining step, compared to the commonly used solvent, the dichloromethane.

  13. Effects of Polymer Conjugation on Hybridization Thermodynamics of Oligonucleic Acids.

    PubMed

    Ghobadi, Ahmadreza F; Jayaraman, Arthi

    2016-09-15

    In this work, we perform coarse-grained (CG) and atomistic simulations to study the effects of polymer conjugation on hybridization/melting thermodynamics of oligonucleic acids (ONAs). We present coarse-grained Langevin molecular dynamics simulations (CG-NVT) to assess the effects of the polymer flexibility, length, and architecture on hybridization/melting of ONAs with different ONA duplex sequences, backbone chemistry, and duplex concentration. In these CG-NVT simulations, we use our recently developed CG model of ONAs in implicit solvent, and treat the conjugated polymer as a CG chain with purely repulsive Weeks-Chandler-Andersen interactions with all other species in the system. We find that 8-100-mer linear polymer conjugation destabilizes 8-mer ONA duplexes with weaker Watson-Crick hydrogen bonding (WC H-bonding) interactions at low duplex concentrations, while the same polymer conjugation has an insignificant impact on 8-mer ONA duplexes with stronger WC H-bonding. To ensure the configurational space is sampled properly in the CG-NVT simulations, we also perform CG well-tempered metadynamics simulations (CG-NVT-MetaD) and analyze the free energy landscape of ONA hybridization for a select few systems. We demonstrate that CG-NVT-MetaD simulation results are consistent with the CG-NVT simulations for the studied systems. To examine the limitations of coarse-graining in capturing ONA-polymer interactions, we perform atomistic parallel tempering metadynamics simulations at well-tempered ensemble (AA-MetaD) for a 4-mer DNA in explicit water with and without conjugation to 8-mer poly(ethylene glycol) (PEG). AA-MetaD simulations also show that, for a short DNA duplex at T = 300 K, a condition where the DNA duplex is unstable, conjugation with PEG further destabilizes DNA duplex. We conclude with a comparison of results from these three different types of simulations and discuss their limitations and strengths. PMID:27598692

  14. 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

  15. The Revolution Revisited: Effective Schools and Systemic Reform.

    ERIC Educational Resources Information Center

    Taylor, Barbara O.; Bullard, Pamela

    A basic tenet of the effective-schools movement is that all children can master the basic skills needed to be successful in school. Today, the twin notions of equity and excellence strongly drive the school-reform movement. This book examines the effective-schools movement as a school-reform philosophy and renewal process for the present and…

  16. 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…

  17. 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…

  18. 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

  19. Revisiting the Effect of Anthropomorphizing a Social Cause Campaign.

    PubMed

    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

  20. Revisiting the O'Connell Effect in Eclipsing Binary Systems

    NASA Astrophysics Data System (ADS)

    Wilsey, Nicholas J.; Beaky, Mathew M.

    2009-05-01

    Many eclipsing binary light curves exhibit a feature known as the O'Connell effect, where the two out-of-eclipse maxima are unequally high. The effect is entirely unexpected, because the two side-by-side configurations of the components should appear equally bright from our line of sight. Several theories have been proposed to explain the effect, including asymmetrically distributed starspots, clouds of circumstellar dust and gas, or a hot spot caused by the impact of a mass-transferring gas stream. Currently, most published models of systems with asymmetric maxima incorporate starspots to rectify their models to fit the observational data. However, the limitations of starspot solutions, as well as other possible explanations for the asymmetry, are rarely discussed. In order to revitalize the study the O'Connell effect, the astronomy program at Truman State University in Kirksville, Missouri has initiated a project to construct complete BVRI light curves of poorly studied eclipsing binary systems exhibiting the O'Connell effect, including V573 Lyr and UV Mon. We are also exploring methods of applying Fourier analysis to large, all-sky databases to extract correlations that may help to evaluate competing theories for explaining the effect.

  1. Understanding alcohol expectancy effects: revisiting the placebo condition.

    PubMed

    Testa, Maria; Fillmore, Mark T; Norris, Jeanette; Abbey, Antonia; Curtin, John J; Leonard, Kenneth E; Mariano, Kristin A; Thomas, Margaret C; Nomensen, Kim J; George, William H; Vanzile-Tamsen, Carol; Livingston, Jennifer A; Saenz, Christopher; Buck, Philip O; Zawacki, Tina; Parkhill, Michele R; Jacques, Angela J; Hayman, Lenwood W

    2006-02-01

    This article summarizes a symposium organized and cochaired by Maria Testa and presented at the 2005 Annual Meeting of the Research Society on Alcoholism, in Santa Barbara, California. The symposium explored issues relevant to understanding the function of placebo conditions and to interpreting placebo effects. Cochair Mark Fillmore began with an overview of the use of placebo conditions in alcohol research, focusing on methodological issues. Jeanette Norris and her colleagues conducted a review of studies examining placebo conditions among women. They conclude that expectancy effects are limited to a few domains. Maria Testa and Antonia Abbey presented papers suggesting that placebo manipulations may result in unanticipated compensatory effects in actual or hypothetical social situations. That is, placebo participants may compensate for anticipated cognitive impairment through vigilant attention to situational cues. John Curtin's research suggests that the compensatory strategies of placebo participants appear to involve a sensitization of evaluative control, resulting in improved performance. Kenneth Leonard provided concluding remarks on the meaning of placebo effects and the value of placebo conditions in research.

  2. 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…

  3. 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...

  4. 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…

  5. Do Some Schools Narrow the Gap? Differential School Effectiveness Revisited

    ERIC Educational Resources Information Center

    Strand, Steve

    2016-01-01

    Relatively little research has explored whether schools differ in their effectiveness for different group of pupils (e.g. by ethnicity, poverty or gender), for different curriculum subjects (e.g. English, mathematics or science) or over time (different cohorts). This paper uses multilevel modelling to analyse the national test results at age 7 and…

  6. 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

  7. 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.

  8. 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

  9. Preference or fat? Revisiting opioid effects on food intake.

    PubMed

    Taha, Sharif A

    2010-07-14

    It is well established that opioid signaling in the central nervous system constitutes a powerful stimulus for food intake. The role of opioids in determining food preference, however, is less well defined. Opioids have been proposed to promote intake of preferred foods, or, alternatively, to preferentially increase consumption of fat. In the present manuscript, I comprehensively review results from previous studies investigating this issue. Data from these studies suggests a mechanism for opioid action that may reconcile the previously proposed hypotheses: opioid effects on food intake do appear to be largely specific for fat consumption, but individual animals' sensitivity to this effect may be dependent on baseline food preferences. In addition, I highlight the possibility that the selectivity of endogenous opioid effects may importantly differ from that of exogenous agonists in the degree to which baseline preferences, rather than macronutrient intake, are altered. The paper represents an invited review by a symposium, award winner or keynote speaker at the Society for the Study of Ingestive Behavior [SSIB] Annual Meeting in Portland, July 2009. PMID:20211638

  10. 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

  11. 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.

  12. Revisiting the adaptive and maladaptive effects of crossmodal plasticity.

    PubMed

    Heimler, B; Weisz, N; Collignon, O

    2014-12-26

    One of the most striking demonstrations of experience-dependent plasticity comes from studies of sensory-deprived individuals (e.g., blind or deaf), showing that brain regions deprived of their natural inputs change their sensory tuning to support the processing of inputs coming from the spared senses. These mechanisms of crossmodal plasticity have been traditionally conceptualized as having a double-edged sword effect on behavior. On one side, crossmodal plasticity is conceived as adaptive for the development of enhanced behavioral skills in the remaining senses of early-deaf or blind individuals. On the other side, crossmodal plasticity raises crucial challenges for sensory restoration and is typically conceived as maladaptive since its presence may prevent optimal recovery in sensory-re-afferented individuals. In the present review we stress that this dichotomic vision is oversimplified and we emphasize that the notions of the unavoidable adaptive/maladaptive effects of crossmodal reorganization for sensory compensation/restoration may actually be misleading. For this purpose we critically review the findings from the blind and deaf literatures, highlighting the complementary nature of these two fields of research. The integrated framework we propose here has the potential to impact on the way rehabilitation programs for sensory recovery are carried out, with the promising prospect of eventually improving their final outcomes. PMID:25139761

  13. 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.

  14. Revisiting a pre-inflationary radiation era and its effect on the CMB power spectrum

    SciTech Connect

    Das, Suratna; Goswami, Gaurav; Rangarajan, Raghavan; Prasad, Jayanti E-mail: gaugo@prl.res.in E-mail: raghavan@prl.res.in

    2015-06-01

    We revisit the scenario where inflation is preceded by a radiation era by considering that the inflaton too could have been in thermal equilibrium early in the radiation era. Hence we take into account not only the effect of a pre-inflationary era on the inflaton mode functions but also that of a frozen thermal distribution of inflaton quanta. We initially discuss in detail the issues relevant to our scenario of a pre-inflationary radiation dominated era and then obtain the scalar power spectrum for this scenario. We find that the power spectrum is free from infrared divergences. We then use the WMAP and Planck data to determine the constraints on the inflaton comoving 'temperature' and on the duration of inflation. We find that the best fit value of the duration of inflation is less than 1 e-folding more than what is required to solve cosmological problems, while only an upper bound on the inflaton temperature can be obtained.

  15. Negative self-efficacy and goal effects revisited.

    PubMed

    Bandura, Albert; Locke, Edwin A

    2003-02-01

    The authors address the verification of the functional properties of self-efficacy beliefs and document how self-efficacy beliefs operate in concert with goal systems within a sociocognitive theory of self-regulation in contrast to the focus of control theory on discrepancy reduction. Social cognitive theory posits proactive discrepancy production by adoption of goal challenges working in concert with reactive discrepancy reduction in realizing them. Converging evidence from diverse methodological and analytic strategies verifies that perceived self-efficacy and personal goals enhance motivation and performance attainments. The large body of evidence, as evaluated by 9 meta-analyses for the effect sizes of self-efficacy beliefs and by the vast body of research on goal setting, contradicts findings (J. B. Vancouver, C. M. Thompson, & A. A. Williams, 2001; J. B. Vancouver, C. M. Thompson, E. C. Tischner, & D. J. Putka 2002) that belief in one's capabilities and personal goals is self-debilitating.

  16. The healthy worker effect in major league baseball revisited.

    PubMed

    Abel, Ernest L; Kruger, Michael L

    2006-01-01

    We investigated the "healthy worker effect" (HWE) in major league baseball. Ages of death of major league baseball players who debuted between 1900 and 1939 were obtained and differences between those ages and age-adjusted life expectancies were examined to determine if longevity increased with career length, controlling for decade in which a player debuted, player position, and handedness. Major league baseball players (N = 4,492) lived an average of 4.8 (+/- 15.0 Standard deviation [SD]) years longer than age-matched controls from the general public. Career length significantly and incrementally increased longevity of players from an average of 4.1 years for players playing one season to 7.4 years for players playing 11 or more years. None of the other factors, nor any of the interactions, was statistically significant. These data provide strong support for the HWE in professional baseball.

  17. Finite size effects on the QCD spectrum revisited

    SciTech Connect

    Gottlieb, S. |; MIMD Lattice Calculation Collaboration

    1992-12-31

    We have continued our study of finite size effects in the QCD spectrum on lattices ranging in size from 8{sup 3}{times}24 to 16{sup 3}{times}24. We have increased our statistics for quark mass am{sub q}=0.025 for the smallest lattice size. In addition, we have studied quark mass 0.01225 for lattice sizes 12{sup 3}{times}24. These lattice sizes correspond to a box 1.8-3.6 fm on a side when the rho mass at zero quark mass is used to set the scale. We discuss the nucleon to rho mass ratio at a smaller value of m{pi}/m{rho} than previously studied with two dynamical flavors.

  18. Finite size effects on the QCD spectrum revisited

    SciTech Connect

    Gottlieb, S. . Dept. of Physics Brookhaven National Lab., Upton, NY )

    1992-01-01

    We have continued our study of finite size effects in the QCD spectrum on lattices ranging in size from 8[sup 3][times]24 to 16[sup 3][times]24. We have increased our statistics for quark mass am[sub q]=0.025 for the smallest lattice size. In addition, we have studied quark mass 0.01225 for lattice sizes 12[sup 3][times]24. These lattice sizes correspond to a box 1.8-3.6 fm on a side when the rho mass at zero quark mass is used to set the scale. We discuss the nucleon to rho mass ratio at a smaller value of m[pi]/m[rho] than previously studied with two dynamical flavors.

  19. Multicomponent ionic diffusion in porewaters: Coulombic effects revisited

    NASA Astrophysics Data System (ADS)

    Boudreau, Bernard P.; Meysman, Filip J. R.; Middelburg, Jack J.

    2004-05-01

    The diffusion of an ion in porewaters cannot occur independently of the other ions in solution as a result of Coulombic coupling, as well as from other effects not considered here. Unfortunately, a longstanding disagreement exists about the correct form and meaning of the equations that describe Coulombic coupling in porewaters, i.e., Ben-Yaakov [Am. J. Sci. 281 (1981) 974] vs. Lasaga [Am. J. Sci. 281 (1981) 981]. This paper re-examines this controversy by reformulating the problem starting from fundamental concepts of mass and charge conservation. We show that these antagonistic formulations are both valid and, in fact, equivalent, when the different interpretations of charge balance are resolved. Most of the disagreements between Ben-Yaakov and Lasaga are then shown to result from differing methods of solution, not fundamental disparities in their models. We note, however, that the explanation for the concept of "stationary" gradients of nonreacting ions as given Ben-Yaakov is inaccurate, and such gradients do lead to diffusive fluxes that are counterbalanced by electrochemical migrational fluxes to produce no net flux (excluding advective flux). We further find that the bicarbonate diffusive flux will not balance the diffusional charge flux of sulfate during its reduction if advection is present. This latter imbalance generates compensating fluxes in the other nonreacting ions. We have applied our theory to a simplified case of sulfate reduction in a marine sediment. The results show that nonreacting ions do diffuse and that with normally expected values of porewater advection, the ratio of the bicarbonate to the sulfate flux can be far different than the ideal value of -2.

  20. The Impenetrable Barrier Revisited - Anthroprogenic Effects on Earth's Radiation Belts

    NASA Astrophysics Data System (ADS)

    Foster, J. C.; Baker, D. N.; Erickson, P. J.; Albert, J.; Fennell, J. F.; Mishin, E. V.; Starks, M. J.; Jaynes, A. N.; Li, X.; Kanekal, S. G.; Kletzing, C.

    2015-12-01

    The Van Allen Probes are contributing significantly to the understanding of processes effecting Earth's radiation belts. It has been noted that the earthward extent of the outer zone highly-relativistic electrons encounters a nearly impenetrable barrier at a radial distance (L) near 2.8 RE inside of which they are not observed. Modeling suggests that this is the result of a balance between slow inward diffusion and hiss-induced precipitation. The large storm of 17 March 2015 afforded an excellent opportunity to investigate the impenetrable barrier using the full complement of sensors carried by the Van Allen Probes. The storm was marked by the rapid reappearance of strong fluxes of MeV electrons directly outside the barrier with the formation of very steep MeV flux gradients. In spite of the strong rapid recovery of MeV electron fluxes immediately outside the barrier, the sharpness and constancy of the gradient at the barrier is strongly suggestive of a previously unrecognized fast-acting and spatially localized mechanism responsible for the formation of such a well-defined feature during these dramatic circumstances. The Van Allen Probes regularly observe a magnetically confined bubble of VLF emissions of terrestrial origin filling the inner magnetosphere. Strongest signals are from US Navy VLF transmitters used for one-way communication to submarines. These signals largely are confined to the region of L space where their frequency is < ½ fce. The strong signal from station NAA at 24 kHz is confined to L < 2.8 where it encounters the ½ fce limit. During the event, the flux of MeV electrons decreased by 1000x across 0.5 RE outside L = 2.8 simultaneous with a 6 order of magnitude increase in the VLF wave intensity as the Probes entered the VLF bubble. The VLF transmitter frequencies are amplified at the point where they overlap natural chorus band near ½ fce suggestive of transmitter-induced triggered emissions. MeV radiation belt electrons encounter this

  1. 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.

  2. Allowance for effects of thermodynamic nonideality in sedimentation equilibrium distributions reflecting protein dimerization.

    PubMed

    Wills, Peter R; Scott, David J; Winzor, Donald J

    2012-03-01

    This reexamination of a high-speed sedimentation equilibrium distribution for α-chymotrypsin under slightly acidic conditions (pH 4.1, I(M) 0.05) has provided experimental support for the adequacy of nearest-neighbor considerations in the allowance for effects of thermodynamic nonideality in the characterization of protein self-association over a moderate concentration range (up to 8 mg/mL). A widely held but previously untested notion about allowance for thermodynamic nonideality effects is thereby verified experimentally. However, it has also been shown that a greater obstacle to better characterization of protein self-association is likely to be the lack of a reliable estimate of monomer net charge, a parameter that has a far more profound effect on the magnitude of the measured equilibrium constant than any deficiency in current procedures for incorporating the effects of thermodynamic nonideality into the analysis of sedimentation equilibrium distributions reflecting reversible protein self-association.

  3. Effects of cosmic acceleration on black hole thermodynamics

    NASA Astrophysics Data System (ADS)

    Mandal, Abhijit; Biswas, Ritabrata

    2015-05-01

    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 de Sitter black hole solution encircled by quintessence field is chosen for this purpose. Different thermodynamic quantities 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 () it was preferable to have a small unstable black hole followed by a large stable one. But in quintessence (), black holes are destined to be unstable large ones pre-quelled by stable/unstable small/intermediate mass black holes.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. Polyploidy and its effect on evolutionary success: old questions revisited with new tools

    PubMed Central

    Madlung, A

    2013-01-01

    Polyploidy, the condition of possessing more than two complete genomes in a cell, has intrigued biologists for almost a century. Polyploidy is found in many plants and some animal species and today we know that polyploidy has had a role in the evolution of all angiosperms. Despite its widespread occurrence, the direct effect of polyploidy on evolutionary success of a species is still largely unknown. Over the years many attractive hypotheses have been proposed in an attempt to assign functionality to the increased content of a duplicated genome. Among these hypotheses are the proposal that genome doubling confers distinct advantages to a polyploid and that these advantages allow polyploids to thrive in environments that pose challenges to the polyploid's diploid progenitors. This article revisits these long-standing questions and explores how the integration of recent genomic developments with ecological, physiological and evolutionary perspectives has contributed to addressing unresolved problems about the role of polyploidy. Although unsatisfactory, the current conclusion has to be that despite significant progress, there still isn't enough information to unequivocally answer many unresolved questions about cause and effect of polyploidy on evolutionary success of a species. There is, however, reason to believe that the increasingly integrative approaches discussed here should allow us in the future to make more direct connections between the effects of polyploidy on the genome and the responses this condition elicits from the organism living in its natural environment. PMID:23149459

  9. 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.

  10. Thermodynamic and functional characteristics of deep-sea enzymes revealed by pressure effects.

    PubMed

    Ohmae, Eiji; Miyashita, Yurina; Kato, Chiaki

    2013-09-01

    Hydrostatic pressure analysis is an ideal approach for studying protein dynamics and hydration. The development of full ocean depth submersibles and high pressure biological techniques allows us to investigate enzymes from deep-sea organisms at the molecular level. The aim of this review was to overview the thermodynamic and functional characteristics of deep-sea enzymes as revealed by pressure axis analysis after giving a brief introduction to the thermodynamic principles underlying the effects of pressure on the structural stability and function of enzymes.

  11. Effects of precipitation on the thermodynamic structure of the trade wind boundary layer

    NASA Technical Reports Server (NTRS)

    Albrecht, Bruce A.

    1993-01-01

    A model of the thermodynamic structure of the trade wind boundary layer is formulated to include the parameterization of precipitation in relatively shallow clouds. Although the area-averaged simulated precipitation rates are relatively small (less than 1 mm/day), the inclusion of precipitation has an appreciable effect on the predicted thermodynamic structure. The cloud layer structure simulated with precipitation is warmer, drier, and more stable than that simulated without precipitation. The simulated inversion height is lowered by as much as 60 mbar when precipitation is included.

  12. 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.

  13. 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.

  14. 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 ...

  15. Student Oriented Approaches in the Teaching of Thermodynamics at Universities--Developing an Effective Course Structure

    ERIC Educational Resources Information Center

    Partanen, Lauri

    2016-01-01

    The aim of this study was to apply current pedagogical research in order to develop an effective course and exercise structure for a physical chemistry thermodynamics course intended for second or third year university students of chemistry. A mixed-method approach was used to measure the impact the changes had on student learning. In its final…

  16. 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

  17. 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'.

  18. 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

  19. Interfacial solvation thermodynamics

    NASA Astrophysics Data System (ADS)

    Ben-Amotz, Dor

    2016-10-01

    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.

  20. The effect of citric acid on the activity, thermodynamics and conformation of mushroom polyphenoloxidase.

    PubMed

    Liu, Wei; Zou, Li-qiang; Liu, Jun-ping; Zhang, Zhao-qin; Liu, Cheng-mei; Liang, Rui-hong

    2013-09-01

    Few reports have focused on the effect of citric acid on thermodynamics and conformation of polyphenoloxidase (PPO). In this study, variations on activity, thermodynamics and conformation of mushroom PPO induced by citric acid (1-60mM) and relationships among these were investigated. It showed that with the increasing concentration of citric acid, the activity of PPO decreased gradually to an inactivity condition; inactivation rate constant (k) of PPO increased and the activation energy (Ea) as well as thermodynamic parameters (ΔG, ΔH, ΔS) decreased, which indicated that the thermosensitivity, stability and number of non-covalent bonds of PPO decreased. The conformation was gradually unfolded, which was reflected in the decrease of α-helix contents, increase of β-sheet and exposure of aromatic amino acid residuals. Moreover, two linear relationships of relative activities, enthalpies (ΔH) against α-helix contents were obtained. It indicated that changes of activity and thermodynamics might correlate to the unfolding of conformation.

  1. 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…

  2. Effect of dissociation on thermodynamic properties of pure diatomic gases

    NASA Technical Reports Server (NTRS)

    Woolley, Harold W

    1955-01-01

    A graphical method is described by which the enthalpy, entropy, and compressibility factor for the equilibrium mixture of atoms and diatomic molecules for pure gaseous elements may be obtained and shown for any dissociating element for which the necessary data exist. Results are given for hydrogen, oxygen, and nitrogen. The effect of dissociation on the heat capacity is discussed briefly.

  3. 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.

  4. Effect of glycosylation on protein folding: A close look at thermodynamic stabilization

    PubMed Central

    Shental-Bechor, Dalit; Levy, Yaakov

    2008-01-01

    Glycosylation is one of the most common posttranslational modifications to occur in protein biosynthesis, yet its effect on the thermodynamics and kinetics of proteins is poorly understood. A minimalist model based on the native protein topology, in which each amino acid and sugar ring was represented by a single bead, was used to study the effect of glycosylation on protein folding. We studied in silico the folding of 63 engineered SH3 domain variants that had been glycosylated with different numbers of conjugated polysaccharide chains at different sites on the protein's surface. Thermal stabilization of the protein by the polysaccharide chains was observed in proportion to the number of attached chains. Consistent with recent experimental data, the degree of thermal stabilization depended on the position of the glycosylation sites, but only very weakly on the size of the glycans. A thermodynamic analysis showed that the origin of the enhanced protein stabilization by glycosylation is destabilization of the unfolded state rather than stabilization of the folded state. The higher free energy of the unfolded state is enthalpic in origin because the bulky polysaccharide chains force the unfolded ensemble to adopt more extended conformations by prohibiting formation of a residual structure. The thermodynamic stabilization induced by glycosylation is coupled with kinetic stabilization. The effects introduced by the glycans on the biophysical properties of proteins are likely to be relevant to other protein polymeric conjugate systems that regularly occur in the cell as posttranslational modifications or for biotechnological purposes. PMID:18550810

  5. 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.

  6. 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. PMID:27642190

  7. 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.

  8. Third-order thermodynamic perturbation theory for effective potentials that model complex fluids

    NASA Astrophysics Data System (ADS)

    Zhou, Shiqi; Solana, J. R.

    2008-08-01

    We have performed Monte Carlo simulations to obtain the thermodynamic properties of fluids with two kinds of hard-core plus attractive-tail or oscillatory potentials. One of them is the square-well potential with small well width. The other is a model potential with oscillatory and decaying tail. Both model potentials are suitable for modeling the effective potential arising in complex fluids and fluid mixtures with extremely-large-size asymmetry, as is the case of the solvent-induced depletion interactions in colloidal dispersions. For the former potential, the compressibility factor, the excess energy, the constant-volume excess heat capacity, and the chemical potential have been obtained. For the second model potential only the first two of these quantities have been obtained. The simulations cover the whole density range for the fluid phase and several temperatures. These simulation data have been used to test the performance of a third-order thermodynamic perturbation theory (TPT) recently developed by one of us [S. Zhou, Phys. Rev. E 74, 031119 (2006)] as compared with the well-known second-order TPT based on the macroscopic compressibility approximation due to Barker and Henderson. It is found that the first of these theories provides much better accuracy than the second one for all thermodynamic properties analyzed for the two effective potential models.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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)

  14. Phase stability under irradiation in alloys with a positive heat of mixing: Effective thermodynamics description

    SciTech Connect

    Enrique, Raul A.; Bellon, Pascal

    1999-12-01

    The alteration of phase stability due to the continuous production of forced atomic displacements, as is the case under irradiation, is studied. A simple kinetic model of a binary alloy exhibiting phase separation is investigated, and two limiting cases are considered: nearest-neighbor ballistic exchanges and arbitrary-length ballistic exchanges. The model is simultaneously studied by direct kinetic Monte Carlo simulations, and by theoretical approaches based in the description of the steady state by effective thermodynamics. Two theoretical frameworks are considered: a microscopic description based in effective interactions, and a macroscopic description based in effective free energies constructed over a modified Cahn-Hilliard equation. Developments of these models are proposed to allow for quantitative predictions. For nearest-neighbor ballistic exchanges, the steady-state phase diagram is evaluated for each of the approaches and the results are directly compared. In the case of arbitrary-length ballistic exchanges, the appearance of labyrinthine mesoscopic structures at steady state is rationalized in terms of the competition between short-range attractive and long-range repulsive effective interactions. The favorable comparison between the theoretical results and the direct Kinetic Monte Carlo simulations shows that the long-term behavior of this inherently far-from-equilibrium system can be described in terms of effective thermodynamic potentials. (c) 1999 The American Physical Society.

  15. Effect of hydrolysis on heat capacity, thermodynamic functions, and the relaxation transition of crab chitin and chitosan

    NASA Astrophysics Data System (ADS)

    Kashtanov, E. A.; Uryash, V. F.; Kokurina, N. Yu.; Larina, V. N.

    2014-02-01

    The heat capacity of crab chitin and chitosan is measured in a vacuum adiabatic calorimeter at 10-330 K. The thermodynamic characteristics (enthalpy, entropy, and Gibbs function) are calculated at T → 0 K to 330 K. Differential thermal analysis is used to calculate the relaxation transitions and thermal degradation of chitin and chitosan at 80-600 K. Acid hydrolysis is performed and its effect on the physicochemical properties and thermodynamic functions of chitin and chitosan is studied.

  16. 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.

  17. Shaping the composition profiles in heteroepitaxial quantum dots: Interplay of thermodynamic and kinetic effects

    SciTech Connect

    Georgiou, C.; Leontiou, T.; Kelires, P. C.

    2014-07-15

    Atomistic Monte Carlo simulations, coupling thermodynamic and kinetic effects, resolve a longstanding controversy regarding the origin of composition profiles in heteroepitaxial SiGe quantum dots. It is shown that profiles with cores rich in the unstrained (Si) component derive from near-equilibrium processes and intraisland diffusion. Profiles with cores rich in the strained (Ge) component are of nonequilibrium nature, i.e., they are strain driven but kinetically limited. They are shaped by the distribution of kinetic barriers of atomic diffusion in the islands. The diffusion pathways are clearly revealed for the first time. Geometrical kinetics play a minor role.

  18. 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.

  19. 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.

  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. 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

  2. Unravelling kinetic and thermodynamic effects on the growth of gold nanoplates by liquid transmission electron microscopy.

    PubMed

    Alloyeau, Damien; Dachraoui, Walid; Javed, Yasir; Belkahla, Hannen; Wang, Guillaume; Lecoq, Hélène; Ammar, Souad; Ersen, Ovidiu; Wisnet, Andreas; Gazeau, Florence; Ricolleau, Christian

    2015-04-01

    The growth of colloidal nanoparticles is simultaneously driven by kinetic and thermodynamic effects that are difficult to distinguish. We have exploited in situ scanning transmission electron microscopy in liquid to study the growth of Au nanoplates by radiolysis and unravel the mechanisms influencing their formation and shape. The electron dose provides a straightforward control of the growth rate that allows quantifying the kinetic effects on the planar nanoparticles formation. Indeed, we demonstrate that the surface-reaction rate per unit area has the same dose-rate dependent behavior than the concentration of reducing agents in the liquid cell. Interestingly, we also determine a critical supply rate of gold monomers for nanoparticle faceting, corresponding to three layers per second, above which the formation of nanoplates is not possible because the growth is then dominated by kinetic effects. At lower electron dose, the growth is driven by thermodynamic and the formation and shape of nanoplates are directly related to the twin-planes formed during the growth.

  3. 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.

  4. Thermodynamically consistent Langevin dynamics with spatially correlated noise predicting frictionless regime and transient attraction effect

    NASA Astrophysics Data System (ADS)

    Majka, M.; Góra, P. F.

    2016-10-01

    While the origins of temporal correlations in Langevin dynamics have been thoroughly researched, the understanding of spatially correlated noise (SCN) is rather incomplete. In particular, very little is known about the relation between friction and SCN. In this article, starting from the microscopic, deterministic model, we derive the analytical formula for the spatial correlation function in the particle-bath interactions. This expression shows that SCN is the inherent component of binary mixtures, originating from the effective (entropic) interactions. Further, employing this spatial correlation function, we postulate the thermodynamically consistent Langevin equation driven by the Gaussian SCN and calculate the adequate fluctuation-dissipation relation. The thermodynamical consistency is achieved by introducing the spatially variant friction coefficient, which can be also derived analytically. This coefficient exhibits a number of intriguing properties, e.g., the singular behavior for certain types of interactions. Eventually, we apply this new theory to the system of two charged particles in the presence of counter-ions. Such particles interact via the screened-charge Yukawa potential and the inclusion of SCN leads to the emergence of the anomalous frictionless regime. In this regime the particles can experience active propulsion leading to the transient attraction effect. This effect suggests a nonequilibrium mechanism facilitating the molecular binding of the like-charged particles.

  5. 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).

  6. 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

  7. 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.

  8. Effects of Cholesterol on the Thermodynamics and Kinetics of Passive Transport of Water through Lipid Membranes.

    PubMed

    Issack, Bilkiss B; Peslherbe, Gilles H

    2015-07-23

    While it has long been known that cholesterol reduces the permeability of biological membranes to water, the exact mechanism by which cholesterol influences transmembrane permeation is still unclear. The thermodynamic and kinetic contributions to the transport of water across mixed DPPC/cholesterol bilayers of different composition are thus examined by molecular dynamics simulations. Our analyses show that cholesterol decreases transmembrane permeability to water mainly by altering the thermodynamics of water transport. In particular, the free-energy barrier to permeation is magnified in the dense bilayer interior and the partitioning of water is significantly lowered. The changes are observed to correlate quantitatively well with the cholesterol-dependent density and thickness of the bilayers. In contrast, diffusion coefficients are relatively insensitive to cholesterol concentration, except in the sparsely populated center of the bilayer. Diffusion of water in cholesterol-containing bilayers appears to be related to changes in the free area in the middle of the bilayer and to the solute cross-sectional area in the denser hydrophobic regions. Overall, cholesterol is found to have an inhibitory effect on the permeation of water at all concentrations investigated, although bilayers containing cholesterol concentrations up to 20 mol % display a more dramatic dependence on cholesterol content than at higher concentrations. Our results show that it is possible to quantitatively reproduce the relative effects of cholesterol on lipid bilayer permeability from molecular dynamics simulations.

  9. Quantum Hall effect: The resistivity of a 2D electron gas—a thermodynamic approach

    NASA Astrophysics Data System (ADS)

    Cheremisin, M. V.

    2005-09-01

    Based on a thermodynamic approach, we have calculated the resistivity of a 2D electron gas, assumed dissipationless in a strong quantum limit. Standard measurements, with extra current leads, define the resistivity caused by a combination of Peltier and Seebeck effects. The current causes heating (cooling) at the first (second) sample contacts, due to the Peltier effect. The contact temperatures are different. The measured voltage is equal to the Peltier effect-induced thermoemf which is linear in current. As a result, the resistivity is non-zero as I→0. The resistivity is a universal function of magnetic field and temperature, expressed in fundamental units h/e2. The universal features of magnetotransport data observed in the experiment confirm our predictions.

  10. 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

  11. 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.

  12. Self-consistently thermodynamic treatment for strange quark matter in the effective mass bag model

    NASA Astrophysics Data System (ADS)

    Bao, Tmurbagan; Liu, Guang-Zhou; Zhao, En-Guang; Zhu, Ming-Feng

    2008-12-01

    In the framework of the effective mass bag model (EMBM) we have performed the thermodynamical treatment for strange quark matter (SQM) self-consistently, which overcomes the inconsistencies in the thermodynamical properties of the system. Because of the existence of the pressure extra term, the SQM equation of state (EOS) becomes stiffer comparing with the one for the original EMBM. It is interesting to find that in our treatment the SQM EOS is almost independent of the strong coupling constant g . In this case the SQM EOS seems to get back to the EOS for the original MIT bag model. However, this treatment still has influence on the EOS for hybrid star matter and the corresponding mass-radius relations. With the increase of the strong coupling constant g , the EOS for hybrid star matter gets obviously stiff. From our treatment we notice that the pressure extra term can make a hybrid star more compact than the one described in the original EMBM and this model is more suitable to describe the hybrid stars with small radii.

  13. 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.

  14. 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

  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 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.

  17. 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.

  18. Thermodynamic constraints on effective energy and mass transfer and catchment function

    NASA Astrophysics Data System (ADS)

    Rasmussen, C.

    2012-03-01

    Understanding how water, energy and carbon are partitioned to primary production and effective precipitation is central to quantifying the limits on critical zone evolution. Recent work suggests quantifying energetic transfers to the critical zone in the form of effective precipitation and primary production provides a first order approximation of critical zone process and structural organization. However, explicit linkage of this effective energy and mass transfer (EEMT; W m-2) to critical zone state variables and well defined physical limits remains to be developed. The objective of this work was to place EEMT in the context of thermodynamic state variables of temperature and vapor pressure deficit, with explicit definition of EEMT physical limits using a global climate dataset. The relation of EEMT to empirical measures of catchment function was also examined using a subset of the Model Parameter Estimation Experiment (MOPEX) catchments. The data demonstrated three physical limits for EEMT: (i) an absolute vapor pressure deficit threshold of 1200 Pa above which EEMT is zero; (ii) a temperature dependent vapor pressure deficit limit following the saturated vapor pressure function up to a temperature of 292 K; and (iii) a minimum precipitation threshold required from EEMT production at temperatures greater than 292 K. Within these limits, EEMT scales directly with precipitation, with increasing conversion of the precipitation to EEMT with increasing temperature. The state-space framework derived here presents a simplified framework with well-defined physical limits that has the potential for directly integrating regional to pedon scale heterogeneity in effective energy and mass transfer relative to critical zone structure and function within a common thermodynamic framework.

  19. Thermodynamic constraints on effective energy and mass transfer and catchment function

    NASA Astrophysics Data System (ADS)

    Rasmussen, C.

    2011-07-01

    Understanding how water, energy and carbon are partitioned to primary production and effective precipitation is central to quantifying the limits on critical zone evolution. Recent work suggests quantifying energetic transfers to the critical zone in the form of effective precipitation and primary production provides a first order approximation of critical zone process and structural organization. However, explicit linkage of this effective energy and mass transfer (EEMT; W m-2) to critical zone state variables and well defined physical limits remains to be developed. The objective of this work was to place EEMT in the context of thermodynamic state variables of temperature and vapor pressure deficit, with explicit definition of EEMT physical limits using a global climate dataset. The relation of EEMT to empirical measures of catchment function was also examined using a subset of the Model Parameter Estimation Experiment (MOPEX) catchments. The data demonstrated three physical limits for EEMT: (i) an absolute vapor pressure deficit threshold of 1200 Pa above which EEMT is zero; (ii) a temperature dependent vapor pressure deficit limit following the saturated vapor pressure function up to a temperature of 292 K; and (iii) a minimum precipitation threshold required from EEMT production at temperatures greater than 292 K. Within these limits, EEMT scales directly with precipitation, with increasing conversion of the precipitation to EEMT with increasing temperature. The state-space framework derived here presents a simplified framework with well-defined physical limits that has the potential for directly integrating regional to pedon scale heterogeneity in effective energy and mass transfer relative to critical zone structure and function within a common thermodynamic framework.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Chelate cooperativity and spacer length effects on the assembly thermodynamics and kinetics of divalent pseudorotaxanes.

    PubMed

    Jiang, Wei; Nowosinski, Karol; Löw, Nora L; Dzyuba, Egor V; Klautzsch, Fabian; Schäfer, Andreas; Huuskonen, Juhani; Rissanen, Kari; Schalley, Christoph A

    2012-01-25

    Homo- and heterodivalent crown-ammonium pseudorotaxanes with different spacers connecting the two axle ammonium binding sites have been synthesized and characterized by NMR spectroscopy and ESI mass spectrometry. The homodivalent pseudorotaxanes are investigated with respect to the thermodynamics of divalent binding and to chelate cooperativity. The shortest spacer exhibits a chelate cooperativity much stronger than that of the longer spacers. On the basis of crystal structure, this can be explained by a noninnocent spacer, which contributes to the binding strength in addition to the two binding sites. Already very subtle changes in the spacer length, i.e., the introduction of an additional methylene group, cause substantial changes in the magnitude of cooperative binding as expressed in the large differences in effective molarity. With a similar series of heterodivalent pseudorotaxanes, the spacer effects on the barrier for the intramolecular threading step has been examined with the result that the shortest spacer causes a strained transition structure and thus the second binding event occurs slower than that of the longer spacers. The activation enthalpies and entropies show clear trends. While the longer spacers reduce the enthalpic strain that is present in the transition state for the shortest member of the series, the longer spacers become entropically slightly more unfavorable because of conformational fixation of the spacer chain during the second binding event. These results clearly show the noninnocent spacers to complicate the analysis of multivalent binding. An approximate description which considers the binding sites to be connected just by a flexible chain turns out to be more a rough approximation than a good model. The second conclusion from the results presented here is that multivalency is expressed in both the thermodynamics and the kinetics in different ways. A spacer optimized for strong binding is suboptimal for fast pseudorotaxane formation.

  6. 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

  7. 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.

  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. 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.

  10. Thermodynamic effects of the hydrophobic surfactant proteins on the early adsorption of pulmonary surfactant.

    PubMed

    Schram, V; Hall, S B

    2001-09-01

    We determined the influence of the two hydrophobic proteins, SP-B and SP-C, on the thermodynamic barriers that limit adsorption of pulmonary surfactant to the air-water interface. We compared the temperature and concentration dependence of adsorption, measured by monitoring surface tension, between calf lung surfactant extract (CLSE) and the complete set of neutral and phospholipids (N&PL) without the proteins. Three stages generally characterized the various adsorption isotherms: an initial delay during which surface tension remained constant, a fall in surface tension at decreasing rates, and, for experiments that reached approximately 40 mN/m, a late acceleration of the fall in surface tension to approximately 25 mN/m. For the initial change in surface tension, the surfactant proteins accelerated adsorption for CLSE relative to N&PL by more than ten-fold, reducing the Gibbs free energy of transition (DeltaG(O)) from 119 to 112 kJ/mole. For the lipids alone in N&PL, the enthalpy of transition (DeltaH(O), 54 kJ/mole) and entropy (-T. DeltaS, 65 kJ/mole at 37 degrees C) made roughly equal contributions to DeltaG(O). The proteins in CLSE had little effect on -T. DeltaS(O) (68 kJ/mole), but lowered DeltaG(O) for CLSE by reducing DeltaH(O) (44 kJ/mole). Models of the detailed mechanisms by which the proteins facilitate adsorption must meet these thermodynamic constraints.

  11. 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.

  12. Revisiting the First Galaxies: The Effects of Population III Stars on their Host Galaxies

    NASA Astrophysics Data System (ADS)

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

    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 H2 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 108 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 × 106 M ⊙ re-accrete most of their baryons and transition to metal-enriched Pop II star formation.

  13. 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.

  14. Life-history traits and effective population size in species with overlapping generations revisited: the importance of adult mortality.

    PubMed

    Waples, R S

    2016-10-01

    The relationship between life-history traits and the key eco-evolutionary parameters effective population size (Ne) and Ne/N is revisited for iteroparous species with overlapping generations, with a focus on the annual rate of adult mortality (d). Analytical methods based on populations with arbitrarily long adult lifespans are used to evaluate the influence of d on Ne, Ne/N and the factors that determine these parameters: adult abundance (N), generation length (T), age at maturity (α), the ratio of variance to mean reproductive success in one season by individuals of the same age (φ) and lifetime variance in reproductive success of individuals in a cohort (Vk•). Although the resulting estimators of N, T and Vk• are upwardly biased for species with short adult lifespans, the estimate of Ne/N is largely unbiased because biases in T are compensated for by biases in Vk• and N. For the first time, the contrasting effects of T and Vk• on Ne and Ne/N are jointly considered with respect to d and φ. A simple function of d and α based on the assumption of constant vital rates is shown to be a robust predictor (R(2)=0.78) of Ne/N in an empirical data set of life tables for 63 animal and plant species with diverse life histories. Results presented here should provide important context for interpreting the surge of genetically based estimates of Ne that has been fueled by the genomics revolution. PMID:27273324

  15. 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.

  16. 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

  17. 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

  18. 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).

  19. 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.

  20. 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.

  1. 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.

  2. Thermodynamic and Structural Effects of Macrocyclic Constraints in Protein−Ligand Interactions

    PubMed Central

    2010-01-01

    The thermodynamic and structural effects of macrocyclization as a tactic for stabilizing the biologically active conformation of Grb2 SH2 binding peptides were investigated using isothermal titration calorimetry and X-ray crystallography. 23-Membered macrocycles containing the sequence pYVN were slightly more potent than their linear controls; however, preorganization did not necessarily eventuate in a more favorable binding entropy. Structures of complexes of macrocycle 7 and its acyclic control 8 are similar except for differences in relative orientations of corresponding atoms in the linking moieties of 7 and 8. There are no differences in the number of direct or water-mediated protein−ligand contacts that might account for the less favorable binding enthalpy of 7; however, an intramolecular hydrogen bond between the pY and the pY+3 residues in 8 that is absent in 7 may be a factor. These studies highlight the difficulties associated with correlating energetics and structure in protein−ligand interactions. PMID:21116482

  3. Thermodynamic, spectroscopic, and computational studies of lanthanide complexation with Diethylenetriaminepentaacetic acide: temperature effect and coordination modes

    SciTech Connect

    Guoxin Tian; Leigh R. Martin; Zhiyong Zhang; Linfeng Rao

    2011-04-01

    Stability constants of two DTPA (diethylenetriaminepentaacetic acid) complexes with lanthanides (ML2- and MHL-, where M stands for Nd and Eu and L stands for diethylenetriaminepentaacetate) at 10, 25, 40, 55, and 70 degrees C were determined by potentiometry, absorption spectrophotometry, and luminescence spectroscopy. The enthalpies of complexation at 25 degrees C were determined by microcalorimetry. Thermodynamic data show that the complexation of Nd3þ and Eu3þ with DTPA is weakened at higher temperatures, a 10-fold decrease in the stability constants of ML2- and MHL- as the temperature is increased from 10 to 70 degrees C. The effect of temperature is consistent with the exothermic enthalpy of complexation directly measured by microcalorimetry. Results by luminescence spectroscopy and density functional theory (DFT) calculations suggest that DTPA is octa-dentate in both the EuL2- and EuHL- complexes and, for the first time, the coordination mode in the EuHL- complex was clarified by integration of the experimental data and DFT calculations. In the EuHL- complex, the Eu is coordinated by an octa-dentate H(DTPA) ligand and a water molecule, and the protonation occurs on the oxygen of a carboxylate group.

  4. 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

  5. Oxidative phosphorylation revisited.

    PubMed

    Nath, Sunil; Villadsen, John

    2015-03-01

    The fundamentals of oxidative phosphorylation and photophosphorylation are revisited. New experimental data on the involvement of succinate and malate anions respectively in oxidative phosphorylation and photophosphorylation are presented. These new data offer a novel molecular mechanistic explanation for the energy coupling and ATP synthesis carried out in mitochondria and chloroplast thylakoids. The mechanism does not suffer from the flaws in Mitchell's chemiosmotic theory that have been pointed out in many studies since its first appearance 50 years ago, when it was hailed as a ground-breaking mechanistic explanation of what is perhaps the most important process in cellular energetics. The new findings fit very well with the predictions of Nath's torsional mechanism of energy transduction and ATP synthesis. It is argued that this mechanism, based on at least 15 years of experimental and theoretical work by Sunil Nath, constitutes a fundamentally different theory of the energy conversion process that eliminates all the inconsistencies in Mitchell's chemiosmotic theory pointed out by other authors. It is concluded that the energy-transducing complexes in oxidative phosphorylation and photosynthesis are proton-dicarboxylic acid anion cotransporters and not simply electrogenic proton translocators. These results necessitate revision of previous theories of biological energy transduction, coupling, and ATP synthesis. The novel molecular mechanism is extended to cover ATP synthesis in prokaryotes, in particular to alkaliphilic and haloalkaliphilic bacteria, essentially making it a complete theory addressing mechanistic, kinetic, and thermodynamic details. Finally, based on the new interpretation of oxidative phosphorylation, quantitative values for the P/O ratio, the amount of ATP generated per redox package of the reduced substrates, are calculated and compared with experimental values for fermentation on different substrates. It is our hope that the presentation of

  6. 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

  7. 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

  8. 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.

  9. 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

  10. Drug Resistance Resulting from Kinase Dimerization Is Rationalized by Thermodynamic Factors Describing Allosteric Inhibitor Effects.

    PubMed

    Kholodenko, Boris N

    2015-09-22

    Treatment of cancer patients with ATP-competitive inhibitors of BRAF/CRAF kinases surprisingly increases total kinase activity, especially in wild-type BRAF cells, subverting the desired clinical outcome. Similar inhibition resistance is observed for numerous kinases involving homo/heterodimerization in their activation cycles. Here, I demonstrate that drug resistance resulting from kinase dimerization can be explained using thermodynamic principles. I show that allosteric regulation by inhibitors is described by thermodynamic factors that quantify inhibitor-induced changes in kinase dimerization and the difference in the drug affinity for a free monomer versus a dimer harboring one drug molecule. The analysis extends to kinase homo- and heterodimers, allows for their symmetric and asymmetric conformations, and predicts how thermodynamic factors influence dose-response dependencies. I show how two inhibitors, ineffective on their own, when combined can abolish drug resistance at lower doses than either inhibitor applied alone. Thus, the mechanistic models suggest ways to overcome resistance to kinase inhibitors.

  11. Statistical Thermodynamics and Microscale Thermophysics

    NASA Astrophysics Data System (ADS)

    Carey, Van P.

    1999-08-01

    Many exciting new developments in microscale engineering are based on the application of traditional principles of statistical thermodynamics. In this text Van Carey offers a modern view of thermodynamics, interweaving classical and statistical thermodynamic principles and applying them to current engineering systems. He begins with coverage of microscale energy storage mechanisms from a quantum mechanics perspective and then develops the fundamental elements of classical and statistical thermodynamics. Subsequent chapters discuss applications of equilibrium statistical thermodynamics to solid, liquid, and gas phase systems. The remainder of the book is devoted to nonequilibrium thermodynamics of transport phenomena and to nonequilibrium effects and noncontinuum behavior at the microscale. Although the text emphasizes mathematical development, Carey includes many examples and exercises to illustrate how the theoretical concepts are applied to systems of scientific and engineering interest. In the process he offers a fresh view of statistical thermodynamics for advanced undergraduate and graduate students, as well as practitioners, in mechanical, chemical, and materials engineering.

  12. Kinetics and thermodynamics of chlorpromazine interaction with lipid bilayers: effect of charge and cholesterol.

    PubMed

    Martins, Patrícia T; Velazquez-Campoy, Adrian; Vaz, Winchil L C; Cardoso, Renato M S; Valério, Joana; Moreno, Maria João

    2012-03-01

    Passive transport across cell membranes is the major route for the permeation of xenobiotics through tight endothelia such as the blood–brain barrier. The rate of passive permeation through lipid bilayers for a given drug is therefore a critical step in the prediction of its pharmacodynamics. We describe a detailed study on the kinetics and thermodynamics for the interaction of chlorpromazine (CPZ), an antipsychotic drug used in the treatment of schizophrenia, with neutral and negatively charged lipid bilayers. Isothermal titration calorimetry was used to study the partition and translocation of CPZ in lipid membranes composed of pure POPC, POPC:POPS (9:1), and POPC:Chol:POPS (6:3:1). The membrane charge due to the presence of POPS as well as the additional charge resulting from the introduction of CPZ in the membrane were taken into account, allowing the calculation of the intrinsic partition coefficients (K(P)) and the enthalpy change (ΔH) associated with the process. The enthalpy change upon partition to all lipid bilayers studied is negative, but a significant entropy contribution was also observed for partition to the neutral membrane. Because of the positive charge of CPZ, the presence of negatively charged lipids in the bilayer increases both the observed amount of CPZ that partitions to the membrane (KP(obs)) and the magnitude of ΔH. However, when the electrostatic effects are discounted, the intrinsic partition coefficient was smaller, indicating that the hydrophobic contribution was less significant for the negatively charged membrane. The presence of cholesterol strongly decreases the affinity of CPZ for the bilayer in terms of both the amount of CPZ that associates with the membrane and the interaction enthalpy. A quantitative characterization of the rate of CPZ translocation through membranes composed of pure POPC and POPC:POPS (9:1) was also performed using an innovative methodology developed in this work based on the kinetics of the heat evolved

  13. 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.

  14. 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…

  15. 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…

  16. 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

  17. Methodology of Thermodynamics

    ERIC Educational Resources Information Center

    Mohan, Gyan

    1969-01-01

    Presents a systematization of the mathematical formulae in thermodynamics. From the set of thermodynamic variables, four equations are derived which contain the total mathematical jargon of thermodynamics. (LC)

  18. 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

  19. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Temporal and thermodynamic characteristics of plasma formation

    NASA Astrophysics Data System (ADS)

    Ignatavichyus, M. V.; Kazakyavichyus, É.; Orshevski, G.; Danyunas, V.

    1991-11-01

    An investigation was made of plasma formation accompanying the interaction with aluminum, iron, and VK-6 alloy targets of nanosecond radiation from a YAG:Nd3+ laser (Emax = 50 mJ, τ = 3-8 ns). The duration of the plasma formation process depended weakly on the laser radiation parameters [the power density was varied in the range 1-3 GW/cm2, the pulse rise time in the range 2-8 ns, or the rate of rise of the power density in the range (1-8) × 108 W · cm - 2 · ns -1]. A study was made of the establishment of a local thermodynamic equilibrium in a plasma jet excited by radiation from nanosecond and picosecond (E = 30 mJ, τ = 40 ps) lasers. The maximum of the luminescence from an aluminum plasma excited by picosecond laser radiation was found to correspond to a local thermodynamic equilibrium. A local thermodynamic equilibrium could be absent in the case of excitation by nanosecond laser radiation.

  20. 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.

  1. 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.

  2. Phoneme-Specific Interference in Reading: The Tongue-Twister Effect Revisited.

    ERIC Educational Resources Information Center

    McCutchen, Deborah; And Others

    1991-01-01

    Examines the tongue-twister effect to help determine the role of phonological information during silent reading. Concludes that the tongue-twister effect results from phonetic rather than visual confusion, and that the locus of the effect is within working memory. (MG)

  3. 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…

  4. 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

  5. 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.

  6. 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)

  7. 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…

  8. 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…

  9. 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…

  10. The role of parity, physical size, and magnitude in numerical cognition: the SNARC effect revisited.

    PubMed

    Fitousi, Daniel; Shaki, Samuel; Algom, Daniel

    2009-01-01

    People indicate the physical size or the parity status of small numbers faster by a left-hand key and those of larger numbers by a right-hand key. Because magnitude information is not required for successful performance in these tasks, the presence of a number-space association (the SNARC effect) has been taken to indicate the automatic activation of numerical magnitude in all tasks with numerals. In order to test this account, in a series of five experiments, we derived two consensual markers of automatic activation of irrelevant numerical magnitude, the size congruity effect (for judgments of physical size), and the Garner effect (for judgments of parity). Both markers were found independent of the SNARC effect. Consequently, we question the traditional explanation of the SNARC effect and offer an alternative account in terms of a highly overlearned stimulus-response loop.

  11. 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

  12. 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

  13. Direct allowance for the effects of thermodynamic nonideality in the quantitative characterization of protein self-association by osmometry.

    PubMed

    Wills, Peter R; Winzor, Donald J

    2009-12-01

    A procedure is described for the direct analysis of osmotic pressure data for reversibly dimerizing proteins that makes allowance for effects of thermodynamic nonideality on the statistical-mechanical basis of the potential-of-mean-force between molecules. Detailed consideration is also given to calculation of the magnitudes of the required virial coefficients. After illustration of the approach with analysis of simulated osmotic pressure data, the method is used to obtain dimerization constants from published osmotic pressure data for soybean proteinase inhibitor, hemoglobin and alpha-chymotrypsin. PMID:19782460

  14. 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

  15. Turbulence effects on warm-rain formation in precipitating shallow convection revisited

    NASA Astrophysics Data System (ADS)

    Seifert, Axel; Onishi, Ryo

    2016-09-01

    Two different collection kernels which include turbulence effects on the collision rate of liquid droplets are used as a basis to develop a parameterization of the warm-rain processes autoconversion, accretion, and self-collection. The new parameterization is tested and validated with the help of a 1-D bin microphysics model. Large-eddy simulations of the rain formation in shallow cumulus clouds confirm previous results that turbulence effects can significantly enhance the development of rainwater in clouds and the occurrence and amount of surface precipitation. The detailed behavior differs significantly for the two turbulence models, revealing a considerable uncertainty in our understanding of such effects. In addition, the large-eddy simulations show a pronounced sensitivity to grid resolution, which suggests that besides the effect of sub-grid small-scale isotropic turbulence which is parameterized as part of the collection kernel also the larger turbulent eddies play an important role for the formation of rain in shallow clouds.

  16. 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)

  17. The Solubilities and Thermodynamic Equilibrium of Anhydrite and Gypsum

    NASA Astrophysics Data System (ADS)

    Serafeimidis, K.; Anagnostou, G.

    2015-01-01

    Anhydritic claystones consist of a clay matrix with finely distributed anhydrite. Their swelling has led to severe damage and high repair costs in several tunnels. Gypsum growth combined with water uptake by the clay minerals is the main cause of the swelling process. Identifying the conditions under which gypsum rather than anhydrite represents the stable phase is crucial for understanding rock swelling. As existing studies on the anhydrite-gypsum-water equilibrium appear to be contradictory and do not provide all of the information required, we revisit this classic problem here by formulating and studying a thermodynamic model. In contrast to earlier research, our model is not limited to the anhydrite-gypsum equilibrium, but allows for the determination of the equilibrium concentrations of the individual anhydrite dissolution and gypsum precipitation reactions that underlie the sulphate transformation. The results of the paper are, therefore, also valuable for the formulation of comprehensive sulphate-water interaction models that consider diffusive and advective ion transport simultaneously with the chemical dissolution and precipitation reactions. Furthermore, in addition to the influencing factors that have been considered by previous studies (i.e., fluid and solid pressures, concentration of foreign ions, temperature), we consistently incorporate the effect of the surface energy of the sulphate crystals into the thermodynamic equations and discuss the effect of the clay minerals on the equilibrium conditions. The surface energy effects, which are important particularly in the case of claystones with extremely small pores, increase the solubility of gypsum, thus shifting the thermodynamic equilibrium in favour of anhydrite. Clay minerals also favour anhydrite because they lower the activity of the water. The predictions from the model are compared with experimental results and with predictions from other models in the literature. Finally, a comprehensive

  18. Anion effects on kinetics and thermodynamics of CO2 absorption in ionic liquids.

    PubMed

    Gonzalez-Miquel, Maria; Bedia, Jorge; Abrusci, Concepcion; Palomar, Jose; Rodriguez, Francisco

    2013-03-28

    A thermogravimetric technique based on a magnetic suspension balance operating in dynamic mode was used to study the thermodynamics (in terms of solubility and Henry's law constants) and kinetics (i.e., diffusion coefficients) of CO2 in the ionic liquids [bmim][PF6], [bmim][NTf2], and [bmim][FAP] at temperatures of 298.15, 308.15, and 323.15 K and pressures up to 20 bar. The experimental technique employed was shown to be a fast, accurate, and low-solvent-consuming method to evaluate the suitability of the ionic liquids (ILs) to be used as CO2 absorbents. Thermodynamic results confirmed that the solubility of CO2 in the ILs followed the order [bmim][FAP] > [bmim][NTf2] > [bmim][PF6], increasing with decreasing temperatures and increasing pressures. Kinetic data showed that the diffusion coefficients of CO2 in the ILs followed a different order, [bmim][NTf2] > [bmim][FAP] > [bmim][PF6], increasing with increasing temperatures and pressures. These results evidenced the different influence of the IL structure and operating conditions on the solubility and absorption rate of CO2, illustrating the importance of considering both thermodynamic and kinetic aspects to select adequate ILs for CO2 absorption. On the other hand, the empirical Wilke-Chang correlation was successfully applied to estimate the diffusion coefficients of the systems, with results indicating the suitability of this approach to foresee the kinetic performance of ILs to absorb CO2. The research methodology proposed herein might be helpful in the selection of efficient absorption solvents based on ILs for postcombustion CO2 capture.

  19. 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.

  20. 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.

  1. Models and mechanisms of Hofmeister effects in electrolyte solutions, and colloid and protein systems revisited.

    PubMed

    Salis, Andrea; Ninham, Barry W

    2014-11-01

    Specific effects of electrolytes have posed a challenge since the 1880's. The pioneering work was that of Franz Hofmeister who studied specific salt induced protein precipitation. These effects are the rule rather the exception and are ubiquitous in chemistry and biology. Conventional electrostatic theories (Debye-Hückel, DLVO, etc.) cannot explain such effects. Over the past decades it has been recognised that additional quantum mechanical dispersion forces with associated hydration effects acting on ions are missing from theory. In parallel Collins has proposed a phenomenological set of rules (the law of matching water affinities, LMWA) which explain and bring to order the order of ion-ion and ion-surface site interactions at a qualitative level. The two approaches appear to conflict. Although the need for inclusion of quantum dispersion forces in one form or another is not questioned, the modelling has often been misleading and inappropriate. It does not properly describe the chemical nature (kosmotropic/chaotropic or hard/soft) of the interacting species. The success of the LMWA rules lies in the fact that they do. Here we point to the way that the two apparently opposing approaches might be reconciled. Notwithstanding, there are more challenges, which deal with the effect of dissolved gas and its connection to 'hydrophobic' interactions, the problem of water at different temperatures and 'water structure' in the presence of solutes. They take us to another dimension that requires the rebuilding of theoretical foundations.

  2. Thermodynamic study on the effects of beta-cyclodextrin inclusion with anilinonaphthalenesulfonates.

    PubMed

    Catena, G C; Bright, F V

    1989-04-15

    Thermodynamic parameters and stoichiometries for the binding of anilinonaphthalenesulfonates to beta-cyclodextrin are obtained from steady-state fluorescence intensity and anisotropy measurements. Specifically, formation constant, enthalpy, and entropy values are obtained for complexes of beta-cyclodextrin with eight different substrate molecules at five different temperatures and six different pH values, and their associated errors are given. We propose an explanation of the relative magnitudes of the values obtained with regard to the geometry of the substrate and the importance of the various noncovalent interactions responsible for the complexation.

  3. An easy and effective demonstration of enzyme stereospecificity and equilibrium thermodynamics.

    PubMed

    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 the product has almost zero solubility, the equilibrium favors condensation and thus a normally hydrolytic enzyme catalyzes the opposite reaction. Neither Z-D-AspOH with L-PheOMe nor Z-L-AspOH with D-PheOMe produces any visible product. PMID:21948505

  4. Proton-lattice coupling and vibronic effects in KDP-family thermodynamics

    NASA Astrophysics Data System (ADS)

    Levin, A. A.; Dolin, S. P.; Mikhailova, T. Yu; Solin, M. V.

    2013-04-01

    Based on the vibronic theory of heteroligand complexes a new model Hamiltonian is proposed for the ferroelectrics of KDP (KH2PO4) family. In local representation three items of this Hamiltonian describe the H-bond protons, the potential energy of lattice's oscillators and the coupling of these two subsystems respectively. In Ising form, convenient for numerical calculations, the Hamiltonian offered includes explicitly the characteristics of the electronic structure as well as the orbital vibronic constants of the AO4 tetrahedra. The Ising version of theory is then applied to numerical studying of some questions for KDP thermodynamics.

  5. An easy and effective demonstration of enzyme stereospecificity and equilibrium thermodynamics.

    PubMed

    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 the product has almost zero solubility, the equilibrium favors condensation and thus a normally hydrolytic enzyme catalyzes the opposite reaction. Neither Z-D-AspOH with L-PheOMe nor Z-L-AspOH with D-PheOMe produces any visible product.

  6. How not to revisit Highway 61: negative repetition effects in a post-cue naming task.

    PubMed

    Mayall, Kate; Humphreys, Glyn W; Kotsanis, Sotiris

    2002-01-01

    Repetition effects were studied in a post-cue naming task, in which participants were cued to name one of two stimuli following their presentation. When pairs of pictures were repeated in a second block, former distractors (not named in Block 1) were named faster than former targets (named in Block 1). This negative repetition effect was not found when two words rather than two pictures were used or when a semantic categorization task was used with two pictures. From this we conclude that the effect reflects a process of mapping from a semantic representation to a name. Negative repetition was not found with a simultaneous selection cue, suggesting that it arose only when there was competition for name selection. It was also dependent on memory for previous acts of semantic naming. We propose that negative repetition reflects a form of speech monitoring that is applied when there is competition in the process of mapping from semantic to name representations.

  7. 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.

  8. Concreteness effects revisited: the influence of dynamic visual noise on memory for concrete and abstract words.

    PubMed

    Parker, Andrew; Dagnall, Neil

    2009-05-01

    Two experiments are presented that investigate the effects of dynamic visual noise (DVN) on memory for concrete and abstract words. Memory for concrete words is typically superior to that of abstract words and is referred to as the concreteness effect. DVN is a procedure that has been demonstrated to interfere selectively with visual working memory and the generation of images from long-term memory. It was reasoned that if concreteness effects arise because of the ability of the latter to activate visual representations, then DVN should selectively impair memory for concrete words. Experiment 1 found DVN to selectively reduce free recall of concrete words. Experiment 2 investigated recognition memory and found DVN to reduce memory accuracy and remember responses, while increasing know responses to concrete words.

  9. New evidence of the effects of education on health in the US: compulsory schooling laws revisited.

    PubMed

    Fletcher, Jason M

    2015-02-01

    Estimating the effects of education on health and mortality has been the subject of intense debate and competing findings and summaries. The original Lleras-Muney (2005) methods utilizing state compulsory schooling laws as instrumental variables for completed education and US data to establish effects of education on mortality have been extended to several countries, with mixed and often null findings. However, additional US studies have lagged behind due to small samples and/or lack of mortality information in many available datasets. This paper uses a large, novel survey from the AARP on several hundred thousand respondents to present new evidence of the effects of education on a variety of health outcomes. Results suggest that education may have a role in improving several dimensions of health, such as self reports, cardiovascular outcomes, and weight outcomes. Other results appear underpowered, suggesting that further use of this methodology may require even larger, and potentially unattainable, sample sizes in the US.

  10. Syllabi Revisited.

    ERIC Educational Resources Information Center

    Nakamura, Yoshihiro

    Many teachers feel that the primary goal of language education is the development of communicative rather than linguistic competence. This shift in focus has affected syllabus design. However, no single syllabus appears satisfactory by itself. The grammatical syllabus is effective to instill in learners automatic production of accurate structural…

  11. The prototype effect revisited: Evidence for an abstract feature model of face recognition.

    PubMed

    Wallis, Guy; Siebeck, Ulrike E; Swann, Kellie; Blanz, Volker; Bülthoff, Heinrich H

    2008-01-01

    Humans typically have a remarkable memory for faces. Nonetheless, in some cases they can be fooled. Experiments described in this paper provide new evidence for an effect in which observers falsely "recognize" a face that they have never seen before. The face is a chimera (prototype) built from parts extracted from previously viewed faces. It is known that faces of this kind can be confused with truly familiar faces, a result referred to as the prototype effect. However, recent studies have failed to find evidence for a full effect, one in which the prototype is regarded not only as familiar, but as more familiar than faces which have been seen before. This study sought to reinvestigate the effect. In a pair of experiments, evidence is reported for the full effect based on both an old/new discrimination task and a familiarity ranking task. The results are shown to be consistent with a recognition model in which faces are represented as combinations of reusable, abstract features. In a final experiment, novel predictions of the model are verified by comparing the size of the prototype effect for upright and upside-down faces. Despite the fundamentally piecewise nature of the model, an explanation is provided as to how it can also account for the sensitivity of observers to configural and holistic cues. This discussion is backed up with the use of an unsupervised network model. Overall, the paper describes how an abstract feature-based model can reconcile a range of results in the face recognition literature and, in turn, lessen currently perceived differences between the representation of faces and other objects. PMID:18484826

  12. 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.

  13. 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.

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

    PubMed

    Zhang, Bo; Edwards, Brian J

    2015-06-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Zhang, Bo; Edwards, Brian J.

    2015-06-01

    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.

  16. 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,…

  17. 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…

  18. 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…

  19. 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…

  20. 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…

  1. 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…

  2. 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…

  3. 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…

  4. Home-Career Conflict Reduction Revisited: The Effect of Experimental Directions on KOIS Scores for Women

    ERIC Educational Resources Information Center

    Tittle, Carol Kehr; Denker, Elenor Rubin

    1976-01-01

    The effect of experimental directions designed to reduce a home-career conflict in women's occupational choices on the Kuder Occupational Interest Survey was investigated. Results indicate that the validity of the Kuder survey is not compromised by the experimental directions. Tables are presented and implications are discussed. (Author/JKS)

  5. 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…

  6. 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…

  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 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

  9. 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.

  10. Revisiting parental monitoring: evidence that parental solicitation can be effective when needed most.

    PubMed

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

    2010-12-01

    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, 47% African American) reported their unsupervised time, beliefs about the legitimacy of their parents' authority, and their own involvement in antisocial behavior. Mothers and adolescents reported their perceptions of adolescent disclosure and parental solicitation and control. Adolescents' perceptions of greater parental solicitation at age 11 were associated with less antisocial behavior at age 12 (when controlling for age 11 antisocial behavior) among adolescents reporting large amounts of unsupervised time and weak legitimacy beliefs. Perceived parental solicitation may be an effective deterrent of antisocial behavior when adolescents spend a lot of time unsupervised and for adolescents who are likely to challenge the legitimacy of their parents' authority.

  11. 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.

  12. 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.

  13. 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

  14. Thermodynamic analysis and effect of crystallinity for silicon monoxide negative electrode for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Yasuda, Kouji; Kashitani, Yusuke; Kizaki, Shingo; Takeshita, Kohki; Fujita, Takehisa; Shimosaki, Shinji

    2016-10-01

    The electrochemical behavior of SiO negative electrodes for lithium ion batteries is thermodynamically and experimentally investigated. The analysis of the reaction pathway and the calculation of the reaction potentials during the Li insertion/extraction reactions are carried out by the construction of the ternary phase diagram for the Li-Si-O system. In the initial reaction of Li insertion, metallic Si and lithium silicates are formed above 0.37 V vs. Li/Li+ as a conversion reaction of the SiO negative electrode. Further Li insertion produces Li-Si alloys as reversible reaction phases. The decomposition of the Li4SiO4 phase begins before the formation of the Li-Si alloy is completed. The measured electrode behavior of the SiO negative electrode basically agrees with the thermodynamic calculations, especially at a low reaction rate; deviations can be ascribed to kinetic factors and electrode resistance. The values of over 1898 mA h g-1 and 71.0% were obtained for the discharge capacity and the coulombic efficiency, respectively. Furthermore, the overvoltage for an amorphous SiO electrode was smaller than that for a disproportionated SiO electrode into Si and SiO2 phases.

  15. Sequence effects of aminofluorene-modified DNA duplexes: thermodynamic and circular dichroism properties

    PubMed Central

    Meneni, Srinivasa Rao; D'Mello, Rhijuta; Norigian, Gregory; Baker, Gregory; Gao, Lan; Chiarelli, M. Paul; Cho, Bongsup P.

    2006-01-01

    Circular dichroism (CD) and UV-melting experiments were conducted with 16 oligodeoxynucleotides modified by the carcinogen 2-aminofluorene, whose sequence around the lesion was varied systematically [d(CTTCTNG[AF]NCCTC), N = G, A, C, T], to gain insight into the factors that determine the equilibrium between base-displaced stacked (S) and external B-type (B) duplex conformers. Differing stabilities among the duplexes can be attributed to different populations of S and B conformers. The AF modification always resulted in sequence-dependent thermal (Tm) and thermodynamic (−ΔG°) destabilization. The population of B-type conformers derived from eight selected duplexes (i.e. -AG*N- and -CG*N-) was inversely proportional to the −ΔG° and Tm values, which highlights the importance of carcinogen/base stacking in duplex stabilization even in the face of disrupted Watson–Crick base pairing in S-conformation. CD studies showed that the extent of the adduct-induced negative ellipticities in the 290–350 nm range is correlated linearly with −ΔG° and Tm, but inversely with the population of B-type conformations. Taken together, these results revealed a unique interplay between the extent of carcinogenic interaction with neighboring base pairs and the thermodynamic properties of the AF-modified duplexes. The sequence-dependent S/B heterogeneities have important implications in understanding how arylamine–DNA adducts are recognized in nucleotide excision repair. PMID:16449208

  16. 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.

  17. The labial-coronal effect revisited: Japanese adults say pata, but hear tapa.

    PubMed

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

    2012-12-01

    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 studies exclusively considered languages in which LC sequences are globally more frequent than their counterpart. The current study examined the LC bias in speakers of Japanese, a language that has been claimed to possess more CL than LC sequences. We first conducted an analysis of Japanese corpora that qualified this claim, and identified a subgroup of consonants (plosives) exhibiting a CL bias. Second, focusing on this subgroup of consonants, we found diverging results for production and perception such that Japanese speakers exhibited an articulatory LC bias, but a perceptual CL bias. The CL perceptual bias, however, was modulated by language of presentation, and was only present for stimuli recorded by a Japanese, but not a French, speaker. A further experiment with native speakers of French showed the opposite effect, with an LC bias for French stimuli only. Overall, we find support for a universal, articulatory motivated LC bias in production, supporting a motor explanation of the LC effect, while perceptual biases are influenced by distributional frequencies of the native language.

  18. 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

  19. 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.

  20. The demographic effects of income redistribution and accelerated economic growth revisited.

    PubMed

    Flegg, A T

    1988-05-01

    The statistical basis of Winegarden's conclusions, i.e., that an egalitarian redistribution of incomes in a typical low-income country would cause a substantial increase in fertility, was examined in detail in that it casts doubt about the validity of all previous econometric studies based on international cross-sectional data. Winegarden's model is reproduced as are his findings. The reexamination of Winegarden's (1984) findings revealed 3 areas which suggest that his conclusions may require modification. In regard to family planning, Winegarden's results indicated that the introduction of a state-supported family planning program would cause a large decline in natality after about a decade. A much weaker relationship emerged when the fertility equation was recomputed using a more appropriate economic method. Further, the results were highly sensitive to changes in the threshold year used to classify countries with regard to family planning programs. It is argued that a qualitative index devised by Mauldin and Berelson (1978) provides a more reliable way to measure the effects of such programs than the binary variable Winegarden used. The use of this index fundamentally altered the findings regarding economic growth and income distribution. According to Winegarden's calculations, faster economic growth would have a pronatal impact in the more economically advanced nations yet help to reduce fertility for those countries in the early stages of development. In contrast, it was found that variations in the rate of economic growth had no discernible impact on natality. Winegarden's results suggested that an egalitarian redistribution of incomes would cause substantial increase in fertility in a typical low-income country, but it was found here that these distributional effects would be fairly modest over a wide range of incomes. Consequently, it appears that any concern about the demographic effects of greater equality in less-developed countries is not well

  1. The effect of HMOs on fee-for-service health care expenditures: evidence from Medicare revisited.

    PubMed

    Batata, Amber

    2004-09-01

    This paper implements a new method for calculating the extent of selection in the aged Medicare HMO market. Selection is measured as the difference in average costs between new Medicare HMO enrollees and Medicare fee-for-service stayers with data from 1990 to 1994. Results suggest Medicare HMO enrollees were 1030 US dollars cheaper in their first year of enrollment. The effect is found entirely in Part A (hospital) expenditures, confirming selection is based on inpatient rather than outpatient or preventive care. These results are consistent with previous work.

  2. 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

  3. Vilkovisky-Dewitt Effective Potential Revisited in Gauge-Free Framework

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Srijit

    2015-01-01

    An alternative approach to scalar quantum electrodynamics has been proposed where the usual gauge redundancy of the theory do not manifest. The gauge-dependence of Coleman- Weinberg effective potential is resolved using gauge-free approach leading to a unique scalar to vector mass ratio. The gauge-free result is compared with the one obtained in Vilkovisky-DeWitt's geometric framework and it is shown that it differs from the standard result reported earlier. It is also shown that for reparametrization invariance of the Coleman-Weinberg potential one must combine the Vilkovisky-DeWitt's method with the gauge-free approach.

  4. 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.

  5. 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.

  6. 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.

  7. Baseline adjustment and change revisited: effect of smoking on change in periodontal status following periodontal therapy.

    PubMed

    Preus, Hans R; Sandvik, Leiv; Gjermo, Per; Baelum, Vibeke

    2014-04-01

    Smokers have frequently been reported to have more severe periodontitis, to respond less favorably to periodontal therapy, and to show elevated rate of recurrence compared with non-smokers. The aims of this study was to compare the results of baseline-adjusted and -unadjusted analyses when assessing the effect of smoking on change in periodontal status following therapy and to discuss the methodological issues involved. This is a secondary analysis of data from 180 periodontitis patients enrolled in a randomized controlled clinical intervention trial. Information on smoking habits was elicited from the participants before, and 12 months after, therapy. The clinical parameters analyzed were probing pocket depth and clinical attachment level, using both simple analysis of change (SAC) and analysis of covariance (ancova), adjusting for age, gender, and treatment group. The current smokers presented with more severe periodontitis at baseline than did former and never smokers. Results of the SAC indicated that the current smokers benefitted more from treatment than did former or never smokers, whereas the results of the baseline-adjusted ancova indicated no such differences. Both sets of results are likely to be biased with respect to valid conclusions regarding the 'causal' effect of smoking. Possible sources of bias are discussed.

  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.

  9. 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

  10. The influence of multiple readings on the missing-letter effect revisited.

    PubMed

    Saint-Aubin, Jean; Roy-Charland, Anie; Klein, Raymond M

    2007-10-01

    In searching for a target letter while reading, participants make more omissions when the target letter is embedded in frequent function words than when it is embedded in less frequent content words. According to the guidance-organization (GO) model, this occurs because high-frequency function words are processed faster than low-frequency content words, leaving less time available for letter processing. We tested this hypothesis in three experiments by increasing word-processing speed through text repetition, which should translate into higher omission rates. Participants either read the text and searched for the target letter once or read the text three times and searched for a target letter on all readings or the final reading only. In all the experiments in which participants could not anticipate the target letter to be used, results revealed the presence of a large missing-letter effect that was unaffected by familiarity with the text. In addition, when participants knew from the start the target letter to be used on the final reading, the missing-letter effect was eliminated. Repeated search of the same text for different targets increased omissions equally for function words and content words, but this finding was present even when a new text was used, suggesting that repetition of the search task, rather than familiarity with the text, was responsible.

  11. 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

  12. 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

  13. 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.

  14. The jamming transition in high dimension: an analytical study of the TAP equations and the effective thermodynamic potential

    NASA Astrophysics Data System (ADS)

    Altieri, Ada; Franz, Silvio; Parisi, Giorgio

    2016-09-01

    We present a parallel derivation of the Thouless-Anderson-Palmer (TAP) equations and of an effective thermodynamic potential for the negative perceptron and soft sphere models in high dimension. Both models are continuous constrained satisfaction problems with a critical jamming transition characterized by the same exponents. Our analysis reveals that a power expansion of the potential up to the second order constitutes a successful framework to approach the jamming points from the SAT phase (the region of the phase diagram where at least one configuration verifies all the constraints), where the ground-state energy is zero. An interesting outcome is that approaching the jamming line the effective thermodynamic potential has a logarithmic contribution, which turns out to be dominant in a proper scaling regime. Our approach is quite general and can be directly applied to other interesting models. Finally we study the spectrum of small harmonic fluctuations in the SAT phase recovering the typical scaling D(ω )˜ {ω2} below the cutoff frequency but a different behavior characterized by a non-trivial exponent above it.

  15. The jamming transition in high dimension: an analytical study of the TAP equations and the effective thermodynamic potential

    NASA Astrophysics Data System (ADS)

    Altieri, Ada; Franz, Silvio; Parisi, Giorgio

    2016-09-01

    We present a parallel derivation of the Thouless–Anderson–Palmer (TAP) equations and of an effective thermodynamic potential for the negative perceptron and soft sphere models in high dimension. Both models are continuous constrained satisfaction problems with a critical jamming transition characterized by the same exponents. Our analysis reveals that a power expansion of the potential up to the second order constitutes a successful framework to approach the jamming points from the SAT phase (the region of the phase diagram where at least one configuration verifies all the constraints), where the ground-state energy is zero. An interesting outcome is that approaching the jamming line the effective thermodynamic potential has a logarithmic contribution, which turns out to be dominant in a proper scaling regime. Our approach is quite general and can be directly applied to other interesting models. Finally we study the spectrum of small harmonic fluctuations in the SAT phase recovering the typical scaling D(ω )∼ {ω2} below the cutoff frequency but a different behavior characterized by a non-trivial exponent above it.

  16. Revisit of basal effective friction and pore pressure for Japan trench from topographic point of view

    NASA Astrophysics Data System (ADS)

    Koge, H.; Fujiwara, T.; Kodaira, S.; Sasaki, T.; Kameda, J.; Hamahashi, M.; Hamada, Y.; Kimura, G.

    2013-12-01

    2011 Tohoku-oki earthquake (Mw9.0) produced a fault rupture, extending to the shallow part of the Japan Trench. Based on the bathymetry difference before and after the earthquake, it is demonstrated that the seafloor on outermost landward slope moved ~50 m east-southeastward towards the trench and uplifted ~7 to 10 m. Although the mechanism of the fault rupture is not clear, deformation and frictional properties beneath the forearc are the key to elucidate this important issue. Kimura et al (2012) focused on seismic reflection data along one seismic transect at the Japan Trench (name the transect), and calculated the basal effective friction of the plate boundary by using the critical taper theory. Limited profiles from narrow area, however, never represent general friction property of the plate boundary in the Japan trench. Therefore, several profiles are examined to investigate for the better understanding along-trench variation of the basal frictional properties. Bathymetric and seismic reflection data were taken before and after the Tohoku-oki earthquake to obtain the following angles; slope angle of upper surface, basal dip of the outer wedge. Acuired angles are limited to only the lowest trench slope of the Japan Trench. The limitation enables us to treat the wedge as a more uniform body than would have been achieved with the whole range of seismic cross sections. Applying the critical taper theory to the individual seismic cross sections, force balance among the interior and base of the wedge, fluid pressure ratio, and the basal effective friction of the plate boundary are calculated. Additionally, by using "earth pressure theory", we estimated basal effective friction of ~0.15 under the assumption that branching faults act as back-stops in lower slope areas. References Cubas et al., Geophysical Research Letters: DOI:10.1002/grl.50682 Fujiwara et al., Science 2 December 2011: Vol. 334 no. 6060 p. 1240 Wang and Hu, Journal of Geophysical Research, v.111, p1

  17. 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.

  18. Healing and the invention of metaphor: the effectiveness of symbols revisited.

    PubMed

    Kirmayer, L J

    1993-06-01

    In this essay, I argue that a theory of meaning adequate to account for the effectiveness of symbolic healing and psychotherapy requires some variant of the three concepts of myth, metaphor and archetype. Myth stands for the overarching narrative structures of the self produced and lent authority by cultural tradition. Archetype stands not for performed ideas or images, but for the bodily-given in meaning. Metaphor occupies an intermediate realm, linking narrative and bodily-given experience through imaginative constructions and enactments that allow movement in sensory-affective quality space. This pluralistic perspective itself constitutes a middle-ground between constructivist and realist approaches to meaning that can integrate causal and interpretive models of symbolic healing.

  19. 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.

  20. 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.

  1. Pangloss revisited: a critique of the dilution effect and the biodiversity-buffers-disease paradigm.

    PubMed

    Randolph, S E; Dobson, A D M

    2012-06-01

    The twin concepts of zooprophylaxis and the dilution effect originated with vector-borne diseases (malaria), were driven forward by studies on Lyme borreliosis and have now developed into the mantra "biodiversity protects against disease". The basic idea is that by diluting the assemblage of transmission-competent hosts with non-competent hosts, the probability of vectors feeding on transmission-competent hosts is reduced and so the abundance of infected vectors is lowered. The same principle has recently been applied to other infectious disease systems--tick-borne, insect-borne, indirectly transmitted via intermediate hosts, directly transmitted. It is claimed that the presence of extra species of various sorts, acting through a variety of distinct mechanisms, causes the prevalence of infectious agents to decrease. Examination of the theoretical and empirical evidence for this hypothesis reveals that it applies only in certain circumstances even amongst tick-borne diseases, and even less often if considering the correct metric--abundance rather than prevalence of infected vectors. Whether dilution or amplification occurs depends more on specific community composition than on biodiversity per se. We warn against raising a straw man, an untenable argument easily dismantled and dismissed. The intrinsic value of protecting biodiversity and ecosystem function outweighs this questionable utilitarian justification.

  2. 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.

  3. 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.

  4. Moose body mass variation revisited: disentangling effects of environmental conditions and genetics.

    PubMed

    Herfindal, Ivar; Haanes, Hallvard; Solberg, Erling J; Røed, Knut H; Høgda, Kjell Arild; Sæther, Bernt-Erik

    2014-02-01

    Large-scale geographical variation in phenotypic traits within species is often correlated to local environmental conditions and population density. Such phenotypic variation has recently been shown to also be influenced by genetic structuring of populations. In ungulates, large-scale geographical variation in phenotypic traits, such as body mass, has been related to environmental conditions and population density, but little is known about the genetic influences. Research on the genetic structure of moose suggests two distinct genetic lineages in Norway, structured along a north-south gradient. This corresponds with many environmental gradients, thus genetic structuring provides an additional factor affecting geographical phenotypic variation in Norwegian moose. We investigated if genetic structure explained geographical variation in body mass in Norwegian moose while accounting for environmental conditions, age and sex, and if it captured some of the variance in body mass that previously was attributed to environmental factors. Genetic structuring of moose was the most important variable in explaining the geographic variation in body mass within age and sex classes. Several environmental variables also had strong explanatory power, related to habitat diversity, environmental seasonality and winter harshness. The results suggest that environmental conditions, landscape characteristics, and genetic structure should be evaluated together when explaining large-scale patterns in phenotypic characters or life history traits. However, to better understand the role of genetic and environmental effects on phenotypic traits in moose, an extended individual-based study of variation in fitness-related characters is needed, preferably in an area of convergence between different genetic lineages.

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

    PubMed

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

    2015-08-28

    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. PMID:26328819

  6. Effects of Cooling Rate on Blocking Temperature and Paleointensity, Revisited: Old and New Results

    NASA Astrophysics Data System (ADS)

    Halgedahl, S. L.

    2002-12-01

    Recent years have witnessed a renaissance in experiments to determine paleointensities. Some of the most notable studies have focused on the rapidly chilled margins of oceanic pillow basalts; other studies have yielded paleointensities from single domain magnetite within parent crystals which cooled slowly within an igneous body. Yet, work by several authors has shown theoretically that cooling rate can affect the blocking temperature and the intensity of weak-field thermoremanent magnetization (TRM) acquired by single domain (SD) grains. If the natural cooling rate was sufficiently slow, a Thellier-Thellier paleointensity experiment can yield an ancient field value that is several tens of percent higher than the true field in which the particles originally cooled. In this talk, the theory of this effect is reviewed for SD magnetite. New calculations are presented, which account for a range of grain volumes and aspect ratios in SD magnetite particles, as well as for different sizes and shapes of the cooling body. These results are discussed in light of time variations in the virtual dipole moment and secular variation in direction of the earth's field.

  7. Rheological modelling of complex fluids. I. The concept of effective volume fraction revisited

    NASA Astrophysics Data System (ADS)

    Quemada, D.

    1998-01-01

    Number of complex fluids (as slurries, drilling muds, paints and coatings, many foods, cosmetics, biofluids...) can approximately be described as concentrated dispersions of Structural Units (SUs). Due to shear forces, SUs are assumed to be approximately spherical in shape and uniform in size under steady flow conditions, so that a complex fluid can be considered as a roughly monodisperse dispersion of roughly spherical SUs (with a shear-dependent mean radius), what allows to generalize hard sphere models of monodisperse suspensions to complex fluids. A rheological model of such dispersions of SUs is based on the concept of the effective volume fraction, φ_{eff} which depends on flow conditions. Indeed, in competition with particle interactions, hydrodynamic forces can modify (i) S, the number fraction of particles that all SUs contain, (ii) both SUs arrangements and their internal structure, especially the SU's compactness, \\varphi. As a structural variable, S is governed by a kinetic equation. Through the shear-dependent kinetic rates involved in the latter, the general solution S depends on Γ, a dimensionless shear variable, leading to φ_{eff}(t, Γ; \\varphi). The structural modelling is achieved by introducing this expression of φ_{eff} into a well-established viscosity model of hard sphere suspensions. Using the steady state solution of the kinetic equation, S_{eq}(Γ ), allows to model non-Newtonian behaviors of complex fluids under steady shear conditions, as pseudo-plastic, plastic, dilatant ... ones. In this model, the ratio of high shear to low shear limiting viscosities appears as a key variable. Different examples of application will be discussed.

  8. Nanoscopic Thermodynamics.

    PubMed

    Qi, Weihong

    2016-09-20

    Conventional thermodynamics for bulk substances encounters challenges when one considers materials on the nanometer scale. Quantities such as entropy, enthalpy, free energy, melting temperature, ordering temperature, Debye temperature, and specific heat no longer remain constant but change with the crystal dimension, size, and morphology. Often, one phenomenon is associated with a variety of theories from different perspectives. Still, a model that can reconcile the size and shape dependence of the thermal properties of the nanoscaled substances remains one of the goals of nanoscience and nanotechnology. This Account highlights the nanoscopic thermodynamics for nanoparticles, nanowires, and nanofilms, with particular emphasis on the bond energy model. The central idea is that the atomic cohesive energy determines the thermodynamic performance of a substance and the cohesive energy varies with the atomic coordination environment. It is the cohesive energy difference between the core and the shell that dictates the nanoscopic thermodynamics. This bond energy model rationalizes the following: (i) how the surface dangling bonds depress the melting temperature, entropy, and enthalpy; (ii) how the order-disorder transition of the nanoparticles depends on particle size and how their stability may vary when they are embedded in an appropriate matrix; (iii) predictions of the existence of face-centered cubic structures of Ti, Zr, and Hf at small size; (iv) how two elements that are immiscible in the bulk can form an alloy on the nanoscale, where the critical size can be predicted. The model has enabled us to reproduce the size and shape dependence of a number of physical properties, such as melting temperature, melting entropy, melting enthalpy, ordering temperature, Gibbs free energy, and formation heat, among others, for materials such as Pd, Au, Ag, Cu, Ni, Sn, Pb, In, Bi, Al, Ti, Zr, Hf, In-Al, Ag-Ni, Co-Pt, Cu-Ag, Cu-Ni, Au-Ni, Ag-Pt, and Au-Pt on the nanometer scale

  9. Trapping Effect of Periodic Structures on the Thermodynamic Properties of a Fermi Gas

    NASA Astrophysics Data System (ADS)

    Salas, P.; Solís, M. A.

    2014-04-01

    We report the thermodynamic properties of an ideal Fermi gas immersed in periodic structures such as penetrable multilayers or multitubes simulated by one (planes) or two perpendicular (tubes) external Dirac comb potentials, while the particles are allowed to move freely in the remaining directions. In contrast to what happens to the bosonic chemical potential, which is a constant for T< T c , a non decreasing with temperature anomalous behavior of the fermionic chemical potential is confirmed and monitored as the tube bundle goes from 3D to 1D when the wall impenetrability overcomes a threshold value. In the specific heat curves dimensional crossovers are very noticeable at high temperatures, where the system behavior goes from 3D to 2D for multilayers or from 3D to 1D for multitubes, as the wall impenetrability is increased.

  10. 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

  11. 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

  12. The effect of iron on montmorillonite stability. (I) Background and thermodynamic considerations

    NASA Astrophysics Data System (ADS)

    Wilson, James; Savage, David; Cuadros, Javier; Shibata, Masahiro; Ragnarsdottir, K. Vala

    2006-01-01

    It is envisaged that high-level nuclear waste (HLW) will be disposed of in underground repositories. Many proposed repository designs include steel waste canisters and bentonite backfill. Natural analogues and experimental data indicate that the montmorillonite component of the backfill could react with steel corrosion products to produce non-swelling Fe-rich phyllosilicates such as chamosite, berthierine, or Fe-rich smectite. In K-bearing systems, the alteration of montmorillonite to illite/glauconite could also be envisaged. If montmorillonite were altered to non-swelling minerals, the swelling capacity and self-healing properties of the bentonite backfill could be reduced, thereby diminishing backfill performance. The main aim of this paper was to investigate Fe-rich phyllosilicate mineral stability at the canister-backfill interface using thermodynamic modelling. Estimates of thermodynamic properties were made for Fe-rich clay minerals in order to construct approximate phase-relations for end-member/simplified mineral compositions in logarithmic activity space. Logarithmic activity diagrams (for the system Al 2O 3-FeO-Fe 2O 3-MgO-Na 2O-SiO 2-H 2O) suggest that if pore waters are supersaturated with respect to magnetite in HLW repositories, Fe(II)-rich saponite is the most likely montmorillonite alteration product (if f values are significantly lower than magnetite-hematite equilibrium). Therefore, the alteration of montmorillonite may not be detrimental to nuclear waste repositories that include Fe, as long as the swelling behaviour of the Fe-rich smectite produced is maintained. If f exceeds magnetite-hematite equilibrium, and solutions are saturated with respect to magnetite in HLW repositories, berthierine is likely to be more stable than smectite minerals. The alteration of montmorillonite to berthierine could be detrimental to the performance of HLW repositories.

  13. Thermodynamic Effects on Phase Stabilities and Structural Properties of TiO2 from the First-principles

    NASA Astrophysics Data System (ADS)

    Aoki, Yuta; Saito, Susumu

    2013-03-01

    Titanium dioxide (TiO2) is one of the most representative photocatalytic materials and much attention is focused on understanding and improvement of its photocatalytic activity. At the same time, TiO2 is known to be a highly polymorphic material and as many as eleven crystal phases have been identified so far. It is expected that TiO2 show various photocatalytic properties depending on crystal phases. However, relative stabilities of these identified phases are still controversial. In order to clarify the thermodynamic phase stabilities of TiO2, we obtain the free energies of its several representative phases, rutile, anatase, brookite, and TiO2-II within the framework of the density-functional theory using the pseudopotential method. We calculate both the static energy and the contribution of phonons to the free energy through the quasiharmonic approximation for each phase. It is found that treatment of semicore electrons in constructing the pseudopotential of the Ti atom significantly affects the relative phase stabilities. From the phase diagram obtained, we find that the anatase phase is the most stable at lower temperature and pressure. We also discuss the thermodynamic effects on structural properties such as thermal expansion. We acknowledge the financial supports from the Global Center-of-Excellence Program by MEXT, Japan through the Nanoscience and Quantum Physics Project of Tokyo Institute of Technology, and the Elements Science and Technology Project by MEXT.

  14. 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.

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

    PubMed

    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 (θc), obtained from the generalized Young's equation and the stability analysis, is θ∞ < θc < θ' for positive line tension and is θM < θc < θ∞ for negative line tension. θ∞ 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 θM 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∞ and higher values of θc for positive line tension. The combined effect due to the presence of the triple line and the interfacial areas (f(L) + f(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 θc(0 < θc < θ∞) 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.

  16. 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.

  17. 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.

  18. Unruh effect revisited

    SciTech Connect

    Longhi, Pietro; Soldati, Roberto

    2011-05-15

    A new and exact derivation of the Bogoliubov coefficients is obtained for the simplest case of a spinless, neutral, massive field in a uniformly accelerated frame with a constant acceleration. The method can be suitably generalized in a straightforward manner to any field with spin and charges.

  19. 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.

  20. Surface Arginine Saturation Effect on Unfolding Reaction of Firefly Luciferase: A Thermodynamic and Kinetic Perspective.

    PubMed

    Solgi, Zahra; Khalifeh, Khosrow; Hosseinkhani, Saman; Ranjbar, Bijan

    2016-09-01

    Replacement of some hydrophobic solvent-exposed residues in Lampyris turkestanicus luciferase with arginine increases thermostability of this enzyme. Herein, thermodynamic and kinetic of unfolding reactions of wild type (WT), E354R/356R, E354R/356R-I232R and E354R/356R-Q35R/L182R/I232R variants, has been investigated. Fluorescence and Far-UV circular dichroism measurements using urea as a chemical denaturant indicated that the value of ΔG(H2O) for all variants is greater than that of WT enzyme. Analysis of m-values, as a measure of difference in the solvent accessible surface area between the native and denatured states of protein, revealed that higher stability of mutants is related to their higher degree of compactness in the folded state. Results of unfolding kinetic experiments showed that all variants have three-exponential behavior in which they unfolded with three rate constants and corresponding amplitudes. Increasing the rate constants of fast unfolding phase in mutants relative to WT protein may be attributed to more compactness and more kinetic sensitivity of their folded state to urea. However, more population of WT protein was unfolded from fast unfolding phase. Results of this investigation highlight kinetic stability of luciferase via a slow rate of unfolding.

  1. Surface Arginine Saturation Effect on Unfolding Reaction of Firefly Luciferase: A Thermodynamic and Kinetic Perspective.

    PubMed

    Solgi, Zahra; Khalifeh, Khosrow; Hosseinkhani, Saman; Ranjbar, Bijan

    2016-09-01

    Replacement of some hydrophobic solvent-exposed residues in Lampyris turkestanicus luciferase with arginine increases thermostability of this enzyme. Herein, thermodynamic and kinetic of unfolding reactions of wild type (WT), E354R/356R, E354R/356R-I232R and E354R/356R-Q35R/L182R/I232R variants, has been investigated. Fluorescence and Far-UV circular dichroism measurements using urea as a chemical denaturant indicated that the value of ΔG(H2O) for all variants is greater than that of WT enzyme. Analysis of m-values, as a measure of difference in the solvent accessible surface area between the native and denatured states of protein, revealed that higher stability of mutants is related to their higher degree of compactness in the folded state. Results of unfolding kinetic experiments showed that all variants have three-exponential behavior in which they unfolded with three rate constants and corresponding amplitudes. Increasing the rate constants of fast unfolding phase in mutants relative to WT protein may be attributed to more compactness and more kinetic sensitivity of their folded state to urea. However, more population of WT protein was unfolded from fast unfolding phase. Results of this investigation highlight kinetic stability of luciferase via a slow rate of unfolding. PMID:27343841

  2. Effects of solution composition on the theoretical prediction of ice nucleation kinetics and thermodynamics.

    PubMed

    Karlsson, Jens O M

    2010-02-01

    Predictions by various mathematical models of intracellular ice formation (proposed by Mazur, Pitt, Toner, and Karlsson, respectively) were compared to the known thermodynamic and kinetic behavior of ice formation in supercooled aqueous systems. The older models (Mazur, Pitt, and Toner) significantly underestimated the magnitude of colligative nonequilibrium freezing point depression in response to increased concentration of solutes, such as salts or cryoprotectants. Furthermore, kinetics predicted using phenomenological models (by Mazur and Pitt) exhibited implausible temperature-dependence, with the probability of intracellular ice formation being allowed to increase even at temperatures below the glass transition point. The Toner model, on the other hand, produced invalid results at temperatures below -48 degrees C. The Karlsson model was the only model that consistently yielded realistic predictions over a wide range of temperatures and solute concentrations, especially in the presence of cryoprotectant additives. To facilitate adoption of the Karlsson model of intracellular ice nucleation, the complete set of model equations has been collected and described in detail.

  3. 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.

  4. 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…

  5. 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…

  6. 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…

  7. 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 ...

  8. 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…

  9. 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…

  10. Influence of Response-Effect Feedback on Learning and Performance of a Complex Key-Pressing Task: Morin and Grant (1955) Revisited.

    PubMed

    Chen, Jing; Proctor, Robert W

    2015-01-01

    Response effects, also called action effects, are events produced as a consequence of a response. Morin and Grant (1955) conducted an 8-choice task in which, when one of the response keys was pressed, a feedback light (i.e., response effect) was lit in a row below the stimulus lights. Across participants, stimulus-response and response-effect mappings varied in compatibility, ranging from perfectly corresponding, to random, to perfectly mirror-reversed mapping. After several practice sessions, the feedback lights were removed in a transfer session, and response times increased greatly, particularly for the mappings without much structure, indicating reliance on the feedback during practice. We revisited this paradigm by means of 2 experiments that examined the influence on acquisition and transfer performance of task instruction, reliability of the visual feedback, and task difficulty. Lower task difficulty and unreliable visual feedback resulted in superior performance in the transfer session, indicating better learning of the stimulus-response mapping and less reliance on the feedback during learning. Task instructions that emphasized learning of the mapping or indicated that there would be a later test without the feedback lights did not influence participants' performance in the transfer session. These findings are discussed in relation to several of Healy and colleagues' principles of skill acquisition and transfer and in the context of contemporary research on response-effect associations.

  11. 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.

  12. 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.

  13. Effect of Water Content in N-Methylmorpholine N-Oxide/Cellulose Solutions on Thermodynamics, Structure, and Hydrogen Bonding.

    PubMed

    Rabideau, Brooks D; Ismail, Ahmed E

    2015-12-01

    Native crystalline cellulose is notoriously difficult to dissolve due to its dense hydrogen bond network between chains and weaker hydrophobic forces between cellulose sheets. N-Methylmorpholine N-oxide (NMMO), the solvent behind the Lyocell process, is one of the most successful commercial solvents for the nonderivatized dissolution of cellulose. In this process, water plays a very important role. Its presence at low concentrations allows NMMO to dissolve substantial amounts of cellulose, while at much higher concentrations it precipitates the crystalline fibers. Using all-atom molecular dynamics, we study the thermodynamic and structural properties of ternary solutions of cellulose, NMMO, and water. Using the two-phase thermodynamic method to calculate solvent entropy, we estimate the free energy of dissolution of cellulose as a function of the water concentration and find a transition of spontaneity that is in excellent agreement with experiment. In pure water, we find that cellulose dissolution is nonspontaneous, a result that is due entirely to strong decreases in water entropy. Although the combined effect of enthalpy on dissolution in water is negligible, we observe a net loss of hydrogen bonds, resulting in a change in hydrogen bond energy that opposes dissolution. At lower water concentrations, cellulose dissolution is spontaneous and largely driven by decreases in enthalpy, with solvent entropy playing only a very minor role. When searching for the root causes of this enthalpy decrease, a complex picture emerges in which not one but many different factors contribute to NMMO's good solvent behavior. The reduction in enthalpy is led by the formation of strong hydrogen bonds between cellulose and NMMO's N-oxide, intensified through van der Waals interactions between NMMO's nonpolar body and the nonpolar surfaces of cellulose and unhindered by water at low concentrations due to the formation of efficient hydrogen bonds between water and cellulose.

  14. A modeling study of the aerosol effects on ice microphysics in convective cloud and precipitation development under different thermodynamic conditions

    NASA Astrophysics Data System (ADS)

    Lee, Hannah; Yum, Seong Soo; Lee, Seoung-Soo

    2014-08-01

    An improved approach for cloud droplet activation process parameterization is proposed that can utilize the empirically determined hygroscopicity information and practically limit the sizes of newly activated droplets. With the implementation of the improved approach in a cloud model, the aerosol effects on ice microphysics in convective cloud and precipitation development under different thermodynamic conditions is investigated. The model is run for four different thermodynamic soundings and three different aerosol types, maritime (M), continental (C) and polluted (P). Warm rain suppression by increased aerosol (i.e., CCN) is clearly demonstrated when weakly convective warm clouds are generated but the results are mixed when relatively stronger convective warm clouds are generated. For one of the two soundings that generate strong convective cold clouds, the accumulated precipitation amount is larger for C and P than for M, demonstrating the precipitation enhancement by increased CCN. For the maritime cloud, precipitation is initiated by the warm rain processes but ice hydrometeor particles form fast, which leads to early but weak cloud invigoration. Another stronger cloud invigoration occurs later for M but it is still weaker than that for C and P. It is the delayed accumulation of more water drops and ice particles for a burst of riming process and the latent heat release during the depositional growth of rimed ice particles that invigorate the cloud strongly for C and P. For the other sounding where freezing level is low, ice particles form fast for all three aerosol types and therefore warm rain suppression is not clearly shown. However, there still is more precipitation for C and P than for M until the accumulated precipitation amount becomes larger for M than for C near to the end of the model run. The results demonstrate that the precipitation response to aerosols indeed depends on the environmental conditions.

  15. 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

  16. Thermodynamics of Protein–Protein Interactions of cMyc, Max, and Mad: Effect of Polyions on Protein Dimerization†

    PubMed Central

    Banerjee, Anamika; Hu, Jianzhong; Goss, Dixie J.

    2010-01-01

    The Myc–Max–Mad network of proteins activates or represses gene transcription depending on whether the dimerization partner of Max is c-Myc or Mad. To elucidate the physical properties of these protein–protein interactions, fluorescence anisotropy of TRITC-labeled Max was used. The binding affinities and thermodynamics of dimerization of the Max–Max homodimer and c-Myc–Max and Mad–Max heterodimers were determined. Our results indicate that c-Myc and Max form the most stable heterodimer. Previous work [Kohler, J. J., Metallo, S. J., Schneider, T. L., and Schepartz, A. (1999) Proc. Natl. Acad. Sci. U.S.A. 96, 11735–9] has shown that instead of dimerizing first and then binding to DNA, these proteins use a monomer pathway in which a monomer binds to DNA followed by dimerization on the surface of the DNA. The DNA E-box affects the dimerization, but nonspecific effects may also play a role. The influence of polyions, poly-l-lysine and poly-l-glutamic acid, were investigated to determine the effects of charged polymers other than DNA on homodimerization and heterodimerization. While the positively charged poly-l-lysine, PLL, did not show any significant effect, negatively charged poly-l-glutamic acid, PLG, stabilized both heterodimers and homodimers by 2–3 kJ/mol. These data suggest that in the cell nucleus the presence of negatively charged DNA or RNA could nonspecifically aid in association of these proteins. Calculations of ΔH° and ΔS° from the temperature dependence of Kd indicated that although the thermodynamic parameters for the dimer are different, the reactions for all three dimers are driven by negative (favorable) enthalpic and negative (unfavorable) entropic contributions. In the presence of PLG, entropy became more negative with the effect being largest for c-Myc–Max heterodimers. This suggests that van der Waals and H-bonding interactions are predominant in dimerization of these proteins. PMID:16475822

  17. 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…

  18. 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.

  19. Water in Basaltic Melts: an Experimental and Thermodynamic Study of the Effect of H2O on Liquidus Temperatures.

    NASA Astrophysics Data System (ADS)

    Medard, E.; Grove, T. L.

    2006-12-01

    We present a thermodynamic model for the influence of H2O on liquidus temperatures of olivine-saturated primitive basaltic and andesitic melts. The thermodynamic model has been fitted to a suite of H2O-saturated liquidus experiments carried out on a primitive high-alumina basalt from Medicine Lake Volcano (82-72f) over a pressure range of 10 to 1000 MPa. The model of Silver and Stolper (S+S, 1985, J.Geol. 93:161) has been applied to the experimental data. This model uses the assumption of simple ideal mixing between water species and the anionic matrix in the melt. Water in the melt dissolves as molecular H2O, or dissociates to hydroxyl groups and an oxygen atomic network. For 82-72f, the liquidus olivine shows little compositional variability (Fo87.4 to Fo88.4) over the broad range of pressures and temperatures investigated that is not correlated with H2O content of the melt. This observation supports our assumption that major effect of H2O is on the anionic species in the melt and not on the cation equilibria (e.g. Mg and Si). The model reproduces the experimental data well. We find that there is a large influence of H2O addition on melting point for small amounts of H2O, resulting in a concave-down curvature when liquidus depression is plotted against the amount of H2O added. For addition of 0.8 and 5 wt% H2O to 82-72f, the liquidus is depressed by 35 K and 130 K, respectively. The best fits are obtained by assuming partial water dissociation to OH and H2O species, using the equilibrium constant measured by Stolper (1982). S+S applied their model to simple systems (diopside/H2O, albite/H2O, silica/H2O), and recovered the melting behavior extremely well. They also suggested that melt structure/composition influences the amount of liquidus depression caused by H2O addition. We have investigated the influence of bulk composition by performing complementary experiments on a high-magnesian andesite from Mount Shasta, and on a K, Na, and P rich alkali basalt from

  20. 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…

  1. 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.

  2. Clinical ethics revisited

    PubMed Central

    Singer, Peter A; Pellegrino, Edmund D; Siegler, Mark

    2001-01-01

    A decade ago, we reviewed the field of clinical ethics; assessed its progress in research, education, and ethics committees and consultation; and made predictions about the future of the field. In this article, we revisit clinical ethics to examine our earlier observations, highlight key developments, and discuss remaining challenges for clinical ethics, including the need to develop a global perspective on clinical ethics problems. PMID:11346456

  3. Enceladus' tidal dissipation revisited

    NASA Astrophysics Data System (ADS)

    Tobie, Gabriel; Behounkova, Marie; Choblet, Gael; Cadek, Ondrej; Soucek, Ondrej

    2016-10-01

    A series of chemical and physical evidence indicates that the intense activity at Enceladus' South Pole is related to a subsurface salty water reservoir underneath the tectonically active ice shell. The detection of a significant libration implies that this water reservoir is global and that the average ice shell thickness is about 20-25km (Thomas et al. 2016). The interpretation of gravity and topography data further predicts large variations in ice shell thickness, resulting in a shell potentially thinner than 5 km in the South Polar Terrain (SPT) (Cadek et al. 2016). Such an ice shell structure requires a very strong heat source in the interior, with a focusing mechanism at the SPT. Thermal diffusion through the ice shell implies that at least 25-30 GW is lost into space by passive diffusion, implying a very efficient dissipation mechanism in Enceladus' interior to maintain such an ocean/ice configuration thermally stable.In order to determine in which conditions such a large dissipation power may be generated, we model the tidal response of Enceladus including variable ice shell thickness. For the rock core, we consider a wide range of rheological parameters representative of water-saturated porous rock materials. We demonstrate that the thinning toward the South Pole leads to a strong increase in heat production in the ice shell, with a optimal thickness obtained between 1.5 and 3 km, depending on the assumed ice viscosity. Our results imply that the heat production in the ice shell within the SPT may be sufficient to counterbalance the heat loss by diffusion and to power eruption activity. However, outside the SPT, a strong dissipation in the porous core is required to counterbalance the diffusive heat loss. We show that about 20 GW can be generated in the core, for an effective viscosity of 1012 Pa.s, which is comparable to the effective viscosity estimated in water-saturated glacial tills on Earth. We will discuss the implications of this revisited tidal

  4. 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.

  5. Effect of different sulfides on cadmium distribution during sludge combustion based on experimental and thermodynamic calculation approaches.

    PubMed

    Liu, Jing-Yong; Fu, Jie-Wen; Sun, Shui-Yu; Ning, Xun-An; Wang, Yu-Jie; Chen, Tao; Luo, Guang-Qian; Xie, Wu-Ming; Yang, Zuo-Yi; Zhuo, Zhong-Xu

    2015-01-01

    The effects of sulfur compounds on the migration of a semi-volatile heavy metal (cadmium) during sludge incineration were investigated with two methods, i.e., experiments in a tubular furnace reactor and thermodynamic equilibrium calculations. The representative typical sludge with and without the addition of sulfur compounds was incinerated at 850 °C. The partitioning of Cd among the solid phase (bottom ash) and gas phase (fly ash and flue gas) was quantified. The results indicate that sulfur compounds in the elemental form and a reduced state could stabilize Cd in the form of CdS, aluminosilicate minerals, and polymetallic sulfides, whereas sulfur in the oxidized forms slightly increases Cd volatilization during incineration. For Cd solidification points, the inhibition effect on the volatilization of Cd is as follows: S > Na2SO4 > Na2S. Chemical equilibrium calculations indicate that sulfur binds with Cd and alters Cd speciation at low temperatures (<950 K). Furthermore, SiO2- and Al2O3-containing minerals can function as sorbents stabilizing Cd as condensed phase solids (CdSiO4 and CdAl2O4) according to the results of equilibrium calculations. These findings provide useful information for understanding the partitioning of Cd and thus facilitate the development of strategies to control Cd volatilization during sludge incineration.

  6. 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.

  7. 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.

  8. Acute Kidney Injury: Controversies Revisited

    PubMed Central

    Yong, Kenneth; Dogra, Gursharan; Boudville, Neil; Pinder, Mary; Lim, Wai

    2011-01-01

    This paper addresses the epidemiology of AKI specifically in relation to recent changes in AKI classification and revisits the controversies regarding the timing of initiation of dialysis and the use of peritoneal dialysis as a renal replacement therapy for AKI. In summary, the new RIFLE/AKIN classifications of AKI have facilitated more uniform diagnosis of AKI and clinically significant risk stratification. Regardless, the issue of timing of dialysis initiation still remains unanswered and warrants further examination. Furthermore, peritoneal dialysis as a treatment modality for AKI remains underutilised in spite of potential beneficial effects. Future research should be directed at identifying early reliable biomarkers of AKI, which in conjunction with RIFLE/AKIN classifications of AKI could facilitate well-designed large randomised controlled trials of early versus late initiation of dialysis in AKI. In addition, further studies of peritoneal dialysis in AKI addressing dialysis dose and associated complications are required for this therapy to be accepted more widely by clinicians. PMID:21660314

  9. 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…

  10. 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.

  11. 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.

  12. 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

  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. 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

  15. Range effects of the Coulombic forces on structures, thermodynamic properties and potential energy landscapes: (KCl)32 and related systems

    NASA Astrophysics Data System (ADS)

    Wang, Chengju; Stephen Berry, R.; Jellinek, Julius

    2012-05-01

    By introducing two shielding parameters into the Coulombic part of the Coulomb plus Born-Mayer potential originally developed for (KCl)n systems, we study the effects of the range of the Coulombic interactions on the structures, thermodynamic properties and the potential energy landscapes of binary ionically bonded systems as illustrated by the case of n = 32. Our calculations show that shortening of the Coulomb interaction range leads to a decrease in the energy of the most stable structure, and the structure itself changes from the rocksalt cubic to a hollow cage type. The energy range, in which the heat capacity exhibits a negative value, gradually narrows and eventually disappears. The number of stationary points on the potential energy surface increases, and their energies get spread over a larger interval. The extent of the Coulombic interaction also affects the energy difference (gap) between the most stable structure and the structure that follows it. All these changes translate into changes in the melting behavior of the system. An analysis of the melting behavior as a function of the range of the Coulombic interaction is presented and correlated with the range-dependent changes in the topography of the underlying potential energy surface.

  16. 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.

  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. 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.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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 temperature change signal is not only added to present-day conditions, but also subtracted from a scenario experiment. We use the regional climate model COSMO-CLM with a grid spacing of approximately 50 km (EURO-CORDEX EUR-44 setup) using transient simulations (1950-2100) with the RCP8.5 emissions scenario. We demonstrate that the aforementioned extensions provide an elegant way to separate the full climate change signal into contributions from large-scale thermodynamics (LST), lapse-rate (LR) and large-scale circulation (LSC). In our framework the LSC effect also includes effects due to changes in land-sea contrast and the spatial variations of the SST warming pattern. We find that the LST effect yields a large-scale warming across Europe without any 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

  3. 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.

  4. Solvent isotope effect on the dark adaptation of bacteriorhodopsin in purple membrane: viewpoints of kinetics and thermodynamics.

    PubMed

    Chiang, Han-Kuei; Chu, Li-Kang

    2014-03-13

    The thermal retinal isomerization from all-trans, 15-anti to 13-cis, 15-syn of bacteriorhodopsin in purple membrane in H2O and D2O during dark adaptation was investigated at 30-55 °C at neutral pH. In this temperature range, phase transition of purple membrane and destruction of the tertiary structure of bacteriorhodopsin did not take place. We found that the solvent isotope effect is inverted below about 45 °C; i.e., k(f)(D2O)/k(f)(H2O) > 1. Applying the transition state theory, the changes in enthalpy from the initial state to the transition state along the thermal trans-to-cis forward reaction coordinate, ΔH(f)*, were determined to be 24.7 ± 1.2 and 20.1 ± 0.4 kcal mol(-1) in H2O and D2O, respectively. The relative entropic change of the transition state in H2O and D2O, ΔΔS(f)* = ΔS(f)*(D2O) - ΔS(f)*(H2O), was -14.4 ± 3.9 cal mol(-1) K(-1). In addition, the Gibbs free energy of trans-to-cis thermal isomerization reaction in D2O is 0.4-0.7 kcal mol(-1) lower than that in H2O. It is the first time the entropy and enthalpy of the transition state have been quantified to elucidate the solvent isotope effect in the retinal thermal isomerization of bacteriorhodopsin during dark adaptation. The solvent isotope effect on the thermodynamics properties and kinetics implied that the hydrogen bonding in the transition state during the dark adaptation of bR is stronger than that in the initial state.

  5. 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.

  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.

    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.

  7. 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

  8. Nonlocal thermodynamic equilibrium effects in stratospheric NO and implications for infrared remote sensing

    NASA Technical Reports Server (NTRS)

    Kaye, Jack A.; Kumer, John B.

    1987-01-01

    It is shown that the vibrational state population of stratospheric nitric oxide (NO) could be substantially different from that expected on the basis of LTE. Deviations from LTE may arise because stratospheric NO can be photochemically produced from NO2 with several vibrational quanta. Model calculations suggest that the population of NO(v = 1) could be some 30 percent above that expected from LTE at 30 km, with smaller enhancements above and below. Substantially larger enhancements are predicted for NO(v = 2). This result is shown to have important implications for NO determination by remote sensing of IR emission. Data needed for the quantification of these effects are enumerated.

  9. Thermodynamic study on the effects of beta-cyclodextrin inclusion with berberine.

    PubMed

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

    2002-01-15

    The fluorescence enhancement of berberine (Berb) as a result of complex with beta-cyclodextrin (beta-CD) is investigated. The association constants of alpha-CD and beta-CD with Berb are 60 and 137 M(-1) at 20 degrees C in pH 7.20 aqueous solution. Effects of temperature on the forming inclusion complexes of beta-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 x mol(-1) K(-1) respectively. It was found that the dielectric constant of beta-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 beta-CD and hydrophobic interaction upon the inclusion complex formation are the main forces of the inclusion reaction. Effect of pH on the association of beta-CD with Berb was also studied. Mechanism of the inclusion of beta-CD with Berb is further studied by absorption and NMR measurements. Results show that beta-CD forms a 1:1 inclusion complex with Berb.

  10. 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.

  11. 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.

  12. Thermodynamic effects of laser irradiation of implants placed in bone: an in vitro study.

    PubMed

    Leja, Chris; Geminiani, Alessandro; Caton, Jack; Romanos, Georgios E

    2013-11-01

    Lasers have been proposed for various applications involving dental implants, including uncovering implants and treating peri-implantitis. However, the effect of laser irradiation on the implant surface temperature is only partially known. The aim of this pilot study was to determine the effect of irradiation with diode, carbon dioxide, and Er:YAG lasers on the surface temperature of dental implants placed in bone, in vitro. For this study, one dental implant was placed in a bovine rib. A trephine bur was used to create a circumferential defect to simulate peri-implantitis, and thermocouples were placed at the coronal and apical aspect of the implant. The implant was irradiated for 60 s using four different lasers independently and change in temperature as well as time to reach a 10 °C increase in temperature were recorded. There was wide variability in results among the lasers and settings. Time for a 10 °C increase ranged from 0.9 to over 60 s for the coronal thermocouple and from 18 to over 60 s for the apical thermocouple. Maximum temperature ranged from 5.9 to 70.9 °C coronally and from 1.4 to 23.4 °C apically. During laser irradiation of dental implants, a surface temperature increase beyond the "critical threshold" of 10 °C can be reached after only 18 s.

  13. 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

  14. 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.

  15. Thermodynamics of a nonionic sponge phase.

    PubMed

    Le, T D; Olsson, U; Wennerström, H; Schurtenberger, P

    1999-10-01

    Different suggestions for the mechanism governing the narrow stability of the L(3) (sponge) phase have led to a series of debates in recent years. There have been several models developed to describe such a mechanism via thermodynamics. To date, experimental data are insufficient to test present theories. In this study, we revisit the sponge phase with two series of thermodynamic data performed on the well-characterized C(12)E(5)-n-decane-H(2)O system. These thermodynamic data sets stem from phase equilibrium and static light scattering experiments designed to link system-specific parameters such as the temperature dependence of the spontaneous curvature H(o) and the two bending moduli kappa and (-)kappa, which have only been loosely connected in earlier experiments. The use of a well-characterized system is important in that it allows usage of molecular descriptors from earlier studies to reduce fit parameters. Another advantage for using this system is that its phase behavior is analogous to a two-component system which, from an experimental standpoint, is more practical to perform accurate measurements and, from a theoretical standpoint, more simple to model. In the present investigation, we use these tools to quantitatively test parameters obtained by different experimental techniques and assumptions inherited in theoretical models designed to interpret them. PMID:11970283

  16. 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

  17. 42 CFR 488.30 - Revisit user fee for revisit surveys.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... surveys conducted during the time period for which authority to levy a revisit user fee exists. (e... of the revisit user fee, such as clerical errors, billing for a fee already paid, or assessment of a... 42 Public Health 5 2010-10-01 2010-10-01 false Revisit user fee for revisit surveys....

  18. 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.

  19. 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

  20. 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

  1. Multicomponent diffusion revisited

    NASA Astrophysics Data System (ADS)

    Lam, S. H.

    2006-07-01

    The derivation of the multicomponent diffusion law is revisited. Following Furry [Am. J. Phys. 16, 63 (1948)], Williams [Am. J. Phys. 26, 467 (1958); Combustion Theory, 2nd ed. (Benjamin/Cummings , Menlo Park, CA,1985)] heuristically rederived the classical kinetic theory results using macroscopic equations, and pointed out that the dynamics of the mixture fluid had been assumed inviscid. This paper generalizes the derivation, shows that the inviscid assumption can easily be relaxed to add a new term to the classical diffusion law, and the thermal diffusion term can also be easily recovered. The nonuniqueness of the multicomponent diffusion coefficient matrix is emphasized and discussed.

  2. A thermodynamics based damage mechanics framework for fatigue analysis of microelectronics solder joints with size effects

    NASA Astrophysics Data System (ADS)

    Gomez, Juan

    a structure whose size is close to a 100mum or larger several and relatively simple to implement constitutive models are now available in the literature, and it can be generally stated that the level of understanding has reached a mature level. However, the same problem when the size of the structure is below this characteristic dimension has not been studied before. In other words, the available constitutive models completely neglect the incidence of size effects when evaluating the true behavior of the material at small scales. (Abstract shortened by UMI.)

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. Thermodynamically stable p-channel strained-layer AlGaAs/InGaAs/GaAs heterostructure field effect transistor

    NASA Astrophysics Data System (ADS)

    Baca, A. G.; Zipperian, T. E.; Howard, A. J.; Klem, J. F.; Tigges, C. P.

    1994-08-01

    Device characteristics of a thermodynamically stable p-channel, strained quantum-well heterostructure field effect transistor (HFET) are reported. The AlGaAs/InGaAs/GaAs material system was used to fabricate the p-channel HFETs with Al and In mole fractions of 0.20 and 0.18, respectively. Transconductances of 32 and 94 mS/mm were achieved at 300 and 77 K, respectively, for devices with 1.2 μm recessed gates. These numbers are comparable to InGaAs quantum-well, recessed gate pHFETs whose quantum-well thicknesses exceed the thermodynamic stability limit. These results have important implications for high performance self-aligned devices which require high-temperature processing.

  8. Thermodynamically stable [ital p]-channel strained-layer AlGaAs/InGaAs/GaAs heterostructure field effect transistor

    SciTech Connect

    Baca, A.G.; Zipperian, T.E.; Howard, A.J.; Klem, J.F.; Tigges, C.P. )

    1994-08-08

    Device characteristics of a thermodynamically stable [ital p]-channel, strained quantum-well heterostructure field effect transistor (HFET) are reported. The AlGaAs/InGaAs/GaAs material system was used to fabricate the [ital p]-channel HFETs with Al and In mole fractions of 0.20 and 0.18, respectively. Transconductances of 32 and 94 mS/mm were achieved at 300 and 77 K, respectively, for devices with 1.2 [mu]m recessed gates. These numbers are comparable to InGaAs quantum-well, recessed gate [ital p]HFETs whose quantum-well thicknesses exceed the thermodynamic stability limit. These results have important implications for high performance self-aligned devices which require high-temperature processing.

  9. 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.

  10. 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

  11. Thermodynamics: Frontiers and Foundations.

    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

  12. Climatic effects of 30 years of landscape change over the Greater Phoenix, Arizona, region: 2. Dynamical and thermodynamical response

    NASA Astrophysics Data System (ADS)

    Georgescu, M.; Miguez-Macho, G.; Steyaert, L. T.; Weaver, C. P.

    2009-03-01

    This paper is part 2 of a two-part study evaluating the climatic effect of one of the nation's most rapidly expanding metropolitan complexes, the Greater Phoenix, Arizona, region. Part 1, using a set of sensitivity experiments, estimated the potential impact of observed landscape evolution, since the dawn of the Landsat satellite era on the near surface climate, with a primary focus on the alteration of the surface radiation and energy budgets and through use of high-resolution, 2km grid spacing, Regional Atmospheric Modeling System (RAMS) simulations with circa 1973, circa 1992, and circa 2001 landscape data sets. In this paper, part 2, we address the role of the previously discussed surface budget changes and subsequent repartitioning of energy on the mesoscale dynamics and thermodynamics of the region, the effect on convective rainfall, and their association with the large-scale North American Monsoon System (NAMS). Our results show that contrasts in surface heating resulting from landscape change are responsible for the development of preferentially located mesoscale circulations, on most days, which were stronger for the 2001 compared to the 1973 landscape, due to increased planetary boundary layer (PBL) heating via enhanced turbulent heat flux. The effect of these stronger circulations was to warm and dry the lower part of the PBL and moisten the upper part of the PBL for the 2001 relative to the 1973 landscape. The precise physical pathway(s) whereby precipitation enhancement is initiated with evolving landscape, since the early 1970s, reveals a complicated interplay among scales (from the turbulent to the synoptic scale) that warrants future research. Precipitation recycling, however, was found to be an important driver in the overall sustenance of rainfall enhancement. Although this study was not designed to investigate other radiative forcing factors such as greenhouse gas emissions and aerosols, the results of our sensitivity experiments do suggest that

  13. 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

  14. 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.

  15. 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.

  16. Coherence and measurement in quantum thermodynamics.

    PubMed

    Kammerlander, P; Anders, J

    2016-02-26

    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.

  17. 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

  18. 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

  19. pH and solvent H/D isotope effects on the thermodynamics and kinetics of electron transfer for electrode-immobilized native and urea-unfolded stellacyanin.

    PubMed

    Ranieri, Antonio; Battistuzzi, Gianantonio; Borsari, Marco; Bortolotti, Carlo Augusto; Di Rocco, Giulia; Sola, Marco

    2012-10-23

    The thermodynamics of Cu(II) to Cu(I) reduction and the kinetics of the electron transfer (ET) process for Rhus vernicifera stellacyanin (STC) immobilized on a decane-1-thiol coated gold electrode have been measured through cyclic voltammetry at varying pH and temperature, in the presence of urea and in D(2)O. Immobilized STC undergoes a limited conformational change that mainly results in an enhanced exposure of one or both copper binding histidines to solvent which slightly stabilizes the cupric state and increases histidine basicity. The large immobilization-induced increase in the pK(a) for the acid transition (from 4.5 to 6.3) makes this electrode-SAM-protein construct an attractive candidate as a biomolecular ET switch operating near neutral pH in molecular electronics. Such a potential interest is increased by the robustness of this interface against chemical unfolding as it undergoes only moderate changes in the reduction thermodynamics and in the ET rate in the presence of up to 8 M urea. The sensitivity of these parameters to solvent H/D isotope effects testifies to the role of protein solvation as effector of the thermodynamics and kinetics of ET.

  20. The effect of thermodynamic properties of solvent mixtures explains the difference between methanol and ethanol in C.antarctica lipase B catalyzed alcoholysis.

    PubMed

    Sasso, Francesco; Kulschewski, Tobias; Secundo, Francesco; Lotti, Marina; Pleiss, Jürgen

    2015-11-20

    Kinetic modelling, molecular modelling, and experimental determination of the initial reaction velocity of lipase-catalyzed alcoholysis were combined to study the effect of the alcohol substrate to catalytic activity. The model system consisted of methanol or ethanol at varying concentrations, vinyl acetate as ester substrate 15.2% (v/v), toluene as organic solvent, water at a controlled thermodynamic activity of 0.09, and C. antarctica lipase B as enzyme. For both alcohol substrates, the initial reaction velocity increased sharply at low concentrations and reached a maximum at 0.7% (v/v) for methanol and 2% (v/v) for ethanol. For higher concentrations, the reaction rate decreased to a level of 74% and 60% of the peak value, respectively, due to substrate inhibition. The concentration dependency was described by a kinetic model, including a ping-pong bi-bi mechanism and competitive inhibition by the alcohol, and confirmed previous observations that methanol is more efficiently inhibiting the enzyme than ethanol. However, if the initial reaction velocity was expressed in terms of thermodynamic activity of the two alcohol substrates, the maximum of initial reaction velocity was similar for methanol (a MeOH(max)=0.19) and ethanol (a EtOH(max)=0.21). This was confirmed by molecular modelling which resulted in similar KM (0.22 and 0.19) and Ki values (0.44 and 0.49) for methanol and ethanol, respectively, if expressed in thermodynamic activities. Thus, the experimentally observed difference between methanol and ethanol is not due to differences in interaction with the enzyme but is a consequence of the thermodynamics of the substrate-solvent mixture. For low concentrations in toluene, the activity coefficient of methanol is 40% higher than the activity coefficient of ethanol (γ MeOH=8.5, γ EtOH=6.1).

  1. Thermodynamics from a scaling Hamiltonian

    NASA Astrophysics Data System (ADS)

    Del Pino, L. A.; Troncoso, P.; Curilef, S.

    2007-11-01

    There are problems with defining the thermodynamic limit of systems with long-range interactions; as a result, the thermodynamic behavior of these types of systems is anomalous. In the present work, we review some concepts from both extensive and nonextensive thermodynamic perspectives. We use a model, whose Hamiltonian takes into account spins ferromagnetically coupled in a chain via a power law that decays at large interparticle distance r as 1/rα for α⩾0 . Here, we review old nonextensive scaling. In addition, we propose a Hamiltonian scaled by 2((N/2)1-α-1)/(1-α) that explicitly includes symmetry of the lattice and dependence on the size N of the system. The approach enabled us to improve upon previous results. A numerical test is conducted through Monte Carlo simulations. In the model, periodic boundary conditions are adopted to eliminate surface effects.

  2. 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.

  3. 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.

  4. 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.

  5. Solvent effect on the complex formation of a crown ether derivative with sodium and potassium ions. Thermodynamic background of selectivity

    NASA Astrophysics Data System (ADS)

    Li, Yin; Huszthy, Péter; Móczár, Ildikó; Szemenyei, Balázs; Kunsági-Máté, Sándor

    2013-01-01

    The complexation properties of dimethyl-pyridino-18-crown-6 ether (M2P18C6) with Na+ and K+ in different primary alcohols including methanol (MeOH), ethanol (EtOH) and n-propanol (n-PrOH) were investigated by UV-vis spectroscopy. Stability constants and thermodynamic parameters have been determined applying the van't Hoff theory. In the cases of both Na+ and K+ the stability constants increase with decreasing permittivity of the solvent used. M2P18C6 always exhibits better affinity to K+ in each alcoholic solution compared to Na+. Thermodynamic studies suggest that in both cases there is a correlation between the permittivity of the solvent and the enthalpy and entropy change of complex formation.

  6. 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.

  7. 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…

  8. 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.

  9. 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.

  10. 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.

  11. 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…

  12. 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.

  13. Circular revisit orbits design for responsive mission over a single target

    NASA Astrophysics Data System (ADS)

    Li, Taibo; Xiang, Junhua; Wang, Zhaokui; Zhang, Yulin

    2016-10-01

    The responsive orbits play a key role in addressing the mission of Operationally Responsive Space (ORS) because of their capabilities. These capabilities are usually focused on supporting specific targets as opposed to providing global coverage. One subtype of responsive orbits is repeat coverage orbit which is nearly circular in most remote sensing applications. This paper deals with a special kind of repeating ground track orbit, referred to as circular revisit orbit. Different from traditional repeat coverage orbits, a satellite on circular revisit orbit can visit a target site at both the ascending and descending stages in one revisit cycle. This typology of trajectory allows a halving of the traditional revisit time and does a favor to get useful information for responsive applications. However the previous reported numerical methods in some references often cost lots of computation or fail to obtain such orbits. To overcome this difficulty, an analytical method to determine the existence conditions of the solutions to revisit orbits is presented in this paper. To this end, the mathematical model of circular revisit orbit is established under the central gravity model and the J2 perturbation. A constraint function of the circular revisit orbit is introduced, and the monotonicity of that function has been studied. The existent conditions and the number of such orbits are naturally worked out. Taking the launch cost into consideration, optimal design model of circular revisit orbit is established to achieve a best orbit which visits a target twice a day in the morning and in the afternoon respectively for several days. The result shows that it is effective to apply circular revisit orbits in responsive application such as reconnoiter of natural disaster.

  14. A B3LYP and MP2(full) theoretical investigation into cooperativity effects, aromaticity and thermodynamic properties in the Na(+)⋯benzonitrile⋯H2O ternary complex.

    PubMed

    Zhao, Guang-ming; Liu, Yu-cun; Shi, Wen-jing; Chai, Tao; Ren, Fu-de

    2014-07-01

    The cooperativity effects between H-bonding and Na(+)⋯π or Na(+)⋯σ interactions in Na(+)⋯benzonitrile⋯H2O complexes were investigated using the B3LYP and MP2(full) methods with 6-311++G(2d,p) and aug-cc-pVTZ basis sets. The thermodynamic cooperativity and the influence of this cooperativity on aromaticity was evaluated by nucleus-independent chemical shifts (NICS). The results showed that the influence of the Na(+)⋯σ or Na(+)⋯π interaction on the hydrogen bond is more pronounced than that of the latter on the former. The cooperativity effect appeared in the Na(+)⋯σ interaction complex while the anti-cooperativity effect tended to be in the Na(+)⋯π system. The change in enthalpy is the major factor driving cooperativity. Thermodynamic cooperativity is not in accordance with the cooperativity effect evaluated by the change of interaction energy. The ring aromaticity of is weakened while the bond dissociation energy (BDE) of the C-CN bond increases upon ternary complex formation. The cooperativity effect (E coop) correlates with R c (NICS(1)ternary/NICS(1)binary) and ΔΔδ (Δδ ternary - Δδ binary) involving the ring and C ≡ N bond, as well as R BDE(C-CN) [BDE(C-CN)ternary/BDE(C-CN)binary], respectively. AIM (atoms in molecules) analysis confirms the existence of cooperativity. PMID:25005001

  15. Substituent effects in cation-π interactions revisited: a general approach based on intrinsic properties of the arenes.

    PubMed

    Bauzá, A; Deyà, P M; Frontera, A; Quiñonero, D

    2014-01-28

    The controversial proposal that substituent effects in cation-π interactions can be attributed mainly to electrostatic effects between the ion and local dipoles has been theoretically studied by analyzing 171 aromatics interacting with Na(+). Our results stress the importance of both electrostatic and π-polarization effects to properly describe cation-π interactions.

  16. Fundamental and effective Yang-Mills vertices

    SciTech Connect

    Hofmann, Ralf

    2012-09-26

    Calorons and plane waves within and in between them collectively give rise to a thermal ground state. The latter provides a homgeneous energy density and a negative pressure, and it induces quasiparticle masses to part of the propagating spectrum of deconfining SU(2) Yang-Mills thermodynamics (dynamical gauge-symmetry breaking). In the present talk we discuss the role of a single caloron in inducing effective local vertices, characterized by powers of h, mediating the interaction of plane waves which propagate over large distances. The constraints on momentum transfers through effective 4-vertices are revisited.

  17. 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

  18. Thermodynamic Modeling of the SRS Evaporators: Part III. Temperature, Evaporation, and Composition Effects on Process Control Strategy

    SciTech Connect

    Jantzen, C.M.

    2003-04-08

    Accumulations of two solid phases (a nitrated aluminosilicate) and sodium diuranate, in the form of scale, caused the SRS 2H Evaporator pot to become completely inoperable in October 1999. The accumulation of the sodium diuranate phase, which selectively precipitated with the aluminosilicate phase, caused criticality concerns in the 2H Evaporator. In order to understand the role of steady state saturation on the scale formation, solutions processed from the SRS 2H, 2F, and 3H Evaporators were evaluated with a commercially available thermodynamic equilibrium code known as Geochemist's Workbench.

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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

  8. Revisiting caspases in sepsis.

    PubMed

    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

  9. 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.

  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. 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.

  12. 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.

  13. 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…

  14. 12-Step Treatment for Alcohol and Substance Abuse Revisited: Best Available Evidence Suggests Lack of Effectiveness or Harm

    ERIC Educational Resources Information Center

    Miller, John Clark

    2008-01-01

    Approaches incorporating 12-Step beliefs and practices have dominated substance abuse treatment despite a lack of empirical support. Recent claims for effectiveness relying on results from a large, multisite research project in the U.S. were re-evaluated based on critical analysis of design, methodology, and construction of outcome measures.…

  15. Revisiting Cost-Benefit Relationships of Behavior Management Strategies: What Special Educators Say about Usefulness, Intensity, and Effectiveness

    ERIC Educational Resources Information Center

    Kaff, Marilyn S.; Zabel, Robert H.; Milham, Morgan

    2007-01-01

    In this study, the authors determine special educators' judgments of the use, intensity, and effectiveness of communication and behavior management strategies. In an earlier study, F. H. Wood (1991) examined general educators' cost-benefit considerations in managing behavior of students with emotional or behavioral disorders. As an extension of…

  16. 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.…

  17. 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

  18. 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

  19. Positronium formation and annihilation in liquid crystalline smectic-E phase revisited.

    PubMed

    Dryzek, E; Juszyńska-Gałązka, 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.

  20. 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.

  1. 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

  2. Dynamical effects on the core-mantle boundary from depth-dependent thermodynamical properties of the lower mantle

    NASA Technical Reports Server (NTRS)

    Zhang, Shuxia; Yuen, David A.

    1988-01-01

    A common assumption in modeling dynamical processes in the lower mantle is that both the thermal expansivity and thermal conductivity are reasonably constant. Recent work from seismic equation of state leads to substantially higher values for the thermal conductivity and much lower thermal expansivity values in the deep mantle. The dynamical consequences of incorporating depth-dependent thermodynamic properties on the thermal-mechanical state of the lower mantle are examined with the spherical-shell mean-field equations. It is found that the thermal structure of the seismically resolved anomalous zone at the base of the mantle is strongly influenced by these variable properties and, in particular, that the convective distortion of the core-mantle boundary (CMB) is reduced with the decreasing thermal expansivity. Such a reduction of the dynamically induced topography from pure thermal convection would suggest that some other dynamical mechanism must be operating at the CMB.

  3. 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.

  4. 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

  5. Sevelamer revisited: pleiotropic effects on endothelial and cardiovascular risk factors in chronic kidney disease and end-stage renal disease.

    PubMed

    Rastogi, Anjay

    2013-12-01

    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 of

  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. 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.

  9. 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.

  10. Effects of alkyl chain length and solvents on thermodynamic dissociation constants of the ionic liquids with one carboxyl group in the alkyl chain of imidazolium cations.

    PubMed

    Chen, Yuehua; Wang, Huiyong; Wang, Jianji

    2014-05-01

    Thermodynamic dissociation constants of the Brønsted acidic ionic liquids (ILs) are important for their catalytic and separation applications. In this work, a series of imidazolium bromides with one carboxylic acid substitute group in their alkyl chain ([{(CH2)nCOOH}mim]Br, n = 1,3,5,7) have been synthesized, and their dissociation constants (pKa) at different ionic strengths have been determined in aqueous and aqueous organic solvents at 0.1 mole fraction (x) of ethanol, glycol, iso-propanol, and dimethyl sulfoxide by potentiometric titrations at 298.2 K. The standard thermodynamic dissociation constants (pKa(T)) of the ILs in these solvents were calculated from the extended Debye-Hückel equation. It was found that the pKa values increased with the increase of ionic strength of the media and of the addition of organic solvent in water. The pKa(T) values also increased with the increase of the alkyl chain length of cations of the ILs. In addition, the effect of solvent nature on pKa(T) values is interpreted from solvation of the dissociation components and their Gibbs energy of transfer from water to aqueous organic solutions. PMID:24720707

  11. Effects of alkyl chain length and solvents on thermodynamic dissociation constants of the ionic liquids with one carboxyl group in the alkyl chain of imidazolium cations.

    PubMed

    Chen, Yuehua; Wang, Huiyong; Wang, Jianji

    2014-05-01

    Thermodynamic dissociation constants of the Brønsted acidic ionic liquids (ILs) are important for their catalytic and separation applications. In this work, a series of imidazolium bromides with one carboxylic acid substitute group in their alkyl chain ([{(CH2)nCOOH}mim]Br, n = 1,3,5,7) have been synthesized, and their dissociation constants (pKa) at different ionic strengths have been determined in aqueous and aqueous organic solvents at 0.1 mole fraction (x) of ethanol, glycol, iso-propanol, and dimethyl sulfoxide by potentiometric titrations at 298.2 K. The standard thermodynamic dissociation constants (pKa(T)) of the ILs in these solvents were calculated from the extended Debye-Hückel equation. It was found that the pKa values increased with the increase of ionic strength of the media and of the addition of organic solvent in water. The pKa(T) values also increased with the increase of the alkyl chain length of cations of the ILs. In addition, the effect of solvent nature on pKa(T) values is interpreted from solvation of the dissociation components and their Gibbs energy of transfer from water to aqueous organic solutions.

  12. 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.

  13. 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.

  14. 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

  15. Isotope effects in aqueous systems. Excess thermodynamic properties of 1,3-dimethylurea solutions in H{sub 2}O and D{sub 2}O

    SciTech Connect

    Jakli, G.; Hook, W.A. Van

    1997-11-01

    The osmotic coefficients of 1,3-dimethylurea-h{sub 2}(DMUh{sub 2})/H{sub 2}O and 1,3-dimethylurea-d{sub 2}(DMUd{sub 2})/D{sub 2}O solutions (1, 2, 4, 12, and 20 m{sub aq}, 15 < t/{degree}C < 80) were obtained from differential vapor pressure measurements. Excess partial molar free energies, enthalpies, and entropies for the solvent and their isotope effects were calculated from the temperature derivatives of the osmotic coefficients. New partial molar volume data are reported at 25 C at low and intermediate concentrations. The thermodynamic properties of solution are compared with those of urea and discussed using the cage model of hydrophobic hydration. The results support the mixed (polar-apolar) character of this compound and show that its structural effect on water changes with temperature and concentration.

  16. Compounding effects of fluid confinement and surface strain on the wet–dry transition, thermodynamic response, and dynamics of water–graphene systems

    DOE PAGES

    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

  17. 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.

  18. 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.

  19. Cholesterol's decoupling effect on membrane partitioning and permeability revisited: is there anything beyond Fick's law of diffusion?

    PubMed

    Missner, Andreas; Horner, Andreas; Pohl, Peter

    2008-10-01

    In general, Fick's law of diffusion describes membrane permeation of hydrophobic or amphiphilic molecules. In contrast to this, Thomae et al. recently identified the volume ratio between barrier and aqueous compartments as important additional determinants of membrane permeability (Pm) [A.V. Thomae, T. Koch, C. Panse, H. Wunderli-Allenspach, and S.D. Kramer, Comparing the lipid membrane affinity and permeation of drug-like acids: the intriguing effects of cholesterol and charged lipids, Pharm. Res. 24 (2007) 1457-1472.]. This new theory was supported by the striking observation that low concentrations of cholesterol increased Pm of salicylic acid. As Fick's law is of fundamental importance to all membrane transport processes, we reinvestigated this phenomenon. We measured the electrophoretic mobility of vesicles and used electrochemical scanning microscopy to study the adsorption of the SA anion to lipid vesicular bilayers and SA transport through planar lipid bilayers, respectively. As predicted by Fick's law, Pm of SA decreased continuously with increasing cholesterol content. Thomae et al. made the contrasting artifactual observation because their kinetic approach lacked the required time resolution and led to an underestimation of Pm by five orders of magnitude. We conclude that there is nothing beyond Fick's law of diffusion. It is still valid.

  20. 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.

  1. 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

  2. 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.

  3. Nutational Damping Revisited

    NASA Astrophysics Data System (ADS)

    Burns, J. A.; Sharma, I.

    2000-10-01

    Motivated by the recent detection of complex rotational states for several asteroids and comets, as well as by the ongoing and planned spacecraft missions to such bodies, which should allow their rotational states to be accurately determined, we revisit the problem of the nutational damping of small solar system bodies. The nutational damping of asteroids has been approximately analyzed by Prendergast (1958), Burns and Safronov (1973), and Efroimsky and Lazarian (2000). Many other similar dynamical studies concern planetary wobble decay (e.g., Peale 1973; Yoder and Ward 1979), interstellar dust grain alignment (e.g., Purcell 1979; Lazarian and Efroimsky 1999) and damping of Earth's Chandler wobble (Lambeck 1980). Recall that rotational energy loss for an isolated body aligns the body's angular momentum vector with its axis of maximum inertia. Assuming anelastic dissipation, simple dimensional analysis determines a functional form of the damping timescale, on which all the above authors agree. However, the numerical coefficients of published results are claimed to differ by orders of magnitude. Differences have been ascribed to absent physics, to solutions that fail to satisfy boundary conditions perfectly, and to unphysical choices for the Q parameter. The true reasons for the discrepancy are unclear since, despite contrary claims, the full 3D problem (nutational damping of an anelastic ellipsoid) is analytically intractable so far. To move the debate forward, we compare the solution of a related 2D problem to the expressions found previously, and we present results from a finite element model. On this basis, we feel that previous rates for the decay of asteroidal tumbling (Harris 1994), derived from Burns and Safronov (1973), are likely to be accurate, at least to a factor of a few. Funded by NASA.

  4. 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.

  5. 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.

  6. 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)

  7. A thermodynamically stable nanophase material.

    PubMed

    Lin, Zhang; Gilbert, Benjamin; Liu, Quanlin; Ren, Guoqiang; Huang, Feng

    2006-05-10

    Nanoparticles are metastable relative to the equivalent bulk material due to the positive excess interfacial free energy (IFE). Previous studies have shown that, with increasing surface interaction strength, the IFE diminishes but remains positive. We describe an experimental multicomponent system in which a nanoscale ZnS material is thermodynamically favored and can be formed at the expense of bulk ZnS. In 17 M sodium hydroxide solution, at 230 degrees C, both 3 nm ZnS nanoparticles and bulk ZnS are transformed into sheetlike nanocrystals with a ZnS polytype structure. Our results are theoretically compatible with the concept of a negative IFE, although not with the assumption of constant interface composition. We clarify the meaning of an effective negative IFE and present the necessary conditions for strong chemical surface interactions to stabilize nanoscale inorganic materials relative to bulk matter. Our results show that synthesis methods employing thermodynamic controls can produce nanomaterials with novel morphology.

  8. Distribution of Fullerene Nanoparticles between Water and Solid Supported Lipid Membranes: Thermodynamics and Effects of Membrane Composition on Distribution.

    PubMed

    Ha, Yeonjeong; Katz, Lynn E; Liljestrand, Howard M

    2015-12-15

    The distribution coefficient (Klipw) of fullerene between solid supported lipid membranes (SSLMs) and water was examined using different lipid membrane compositions. Klipw of fullerene was significantly higher with a cationic lipid membrane compared to that with a zwitterionic or anionic lipid membrane, potentially due to the strong interactions between negative fullerene dispersions and positive lipid head groups. The higher Klipw for fullerene distribution to ternary lipid mixture membranes was attributed to an increase in the interfacial surface area of the lipid membrane resulting from phase separation. These results imply that lipid composition can be a critical factor that affects bioconcentration of fullerene. Distribution of fullerene into zwitterionic unsaturated lipid membranes was dominated by the entropy contribution (ΔS) and the process was endothermic (ΔH > 0). This result contrasts the partitioning thermodynamics of highly and moderately hydrophobic chemicals indicating that the lipid-water distribution mechanism of fullerene may be different from that of molecular level chemicals. Potential mechanisms for the distribution of fullerene that may explain these differences include adsorption on the lipid membrane surfaces and partitioning into the center of lipid membranes (i.e., absorption).

  9. The effect of CaF2 on thermodynamics of CaO-CaF2-SiO2(-MgO) slags

    NASA Astrophysics Data System (ADS)

    Choi, Chul-Hwan; Jo, Sung-Koo; Kim, Seon-Hyo; Lee, Kwang-Ro; Kim, Jeong-Tae

    2004-02-01

    To address the role of CaF2 in the CaO-CaF2-SiO2(-MgO) slag system employed for the production of low-pressure rotor steels, the thermodynamic aspects of the slag were investigated by equilibrating it with liquid iron at 1873 K in CaO or MgO crucibles. Presaturation of slag with an oxide block piece of CaO or MgO in a Pt crucible and application of a carbon paste to the outside of an oxide crucible were designed to prevent crucible failure during the slag-metal experiments. The liquidus isotherm and phase boundary of the preceding slag system were investigated using the slag-metal equilibria. Also, the effect of CaF2 on the sulfide capacity and the activity coefficient of Fe t O were of particular interest in controlling the sulfur level and cleanliness of low-pressure rotor steels.

  10. The kinetic and thermodynamic sorption and stabilization of multiwalled carbon nanotubes in natural organic matter surrogate solutions: the effect of surrogate molecular weight.

    PubMed

    Li, Tingting; Lin, Daohui; Li, Lu; Wang, Zhengyu; Wu, Fengchang

    2014-03-01

    Styrene sulfonate (SS) and polystyrene sulfonates (PSSs) were used as surrogates of natural organic matter to study the effect of molecular weight (from 206.2 to 70,000 Da) on their sorption by a multiwalled carbon nanotube (MWCNT) and an activated carbon (AC) and on their stabilization of MWCNT suspension. Results indicate that surface-diffusion through the liquid-sorbent boundary was the rate-controlling step of the kinetic sorption of both MWCNTs and AC, and surface-occupying and pore-filling mechanisms respectively dominated the thermodynamic sorption of MWCNTs and AC. Sorption rates and capacities of MWCNTs and AC in molecular concentration of SS and PSS decreased with increasing molecular weight. The PSSs but not SS facilitated the stabilization of MWCNT suspension because of the increased electrosteric repulsion. The PSSs with more monomers had greater capabilities to stabilize the MWCNT suspension, but the capabilities were comparable after being normalized by the total monomer number.

  11. 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

  12. Nonlinear Hall effect for materials with weak thermoelectric power coefficients: preliminary comparisons between theoretical results of the thermodynamic field theory and experimental data.

    PubMed

    Sonnino, Giorgio; Peeters, Philippe

    2004-09-01

    This paper forms a part of a series of manuscripts which we intend to submit for publication in the near future, aiming to test the validity of the thermodynamic field theory (TFT), previously formulated, comparing the theoretical results with experimental data. In this particular case, we shall analyze the Hall effect. As known, when a magnetic field is applied at right angles to the direction of an electric current or a thermal gradient, galvano- and thermomagnetic effects appear in the material. In this paper, we shall show that if we study these effects in nonlinear regime, the TFT foresees an interesting effect: the nonlinear Hall effect. This prediction is herein submitted to experimental verifications. In this paper, we shall analyze this effect studying materials with weak thermoelectric power coefficients. We shall show the agreement between the theoretical predictions of the TFT and experiments. Experimental curves related to the nonlinear Hall effect allow us to determine the order of magnitude of the constant chi introduced in the TFT.

  13. 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

  14. 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.

  15. 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

  16. Calculation of magnetic oscillations via the magnetic-field-containing relativistic tight-binding approximation method: Revisiting the de Haas-van Alphen effect

    NASA Astrophysics Data System (ADS)

    Hamal, Dipendra Bahadur; Higuchi, Masahiko; Higuchi, Katsuhiko

    2015-06-01

    The magnetic-field-containing relativistic tight-binding approximation (MFRTB) method [Phys. Rev. B 91, 075122 (2015), 10.1103/PhysRevB.91.075122] is the first-principles calculation method for electronic structures of materials immersed in the magnetic field. In this paper, the MFRTB method is applied to the simple cubic lattice immersed in the magnetic field. The total energy and magnetization oscillate with the inverse of the magnitude of the magnetic field, which means that the de Haas-van Alphen oscillation is revisited directly through the MFRTB method. It is shown that the conventional Lifshitz-Kosevich (LK) formula is a good approximation to the results of the MFRTB method in the experimentally available magnetic field. Furthermore, the additional oscillation peaks of the magnetization are found especially in the high magnetic field, which cannot be explained by the LK formula.

  17. 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

  18. Effect of dispersive long-range corrections to the pressure tensor: the vapour-liquid interfacial properties of the Lennard-Jones system revisited.

    PubMed

    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(c) = 2.5, 3, 4, and 5σ. In addition, we have also considered cutoff distances r(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 thickness

  19. 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%.

  20. 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

  1. 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

  2. Effect of stacking interactions on the thermodynamics and kinetics of lumiflavin: a study with improved density functionals and density functional tight-binding protocol.

    PubMed

    Bresnahan, Caitlin G; Reinhardt, Clorice R; Bartholow, Thomas G; Rumpel, John P; North, Michael; Bhattacharyya, Sudeep

    2015-01-01

    The π-π stacking interaction between lumiflavin and a number of π-electron-rich molecules has been studied by density functional theory using several new-generation density functionals. Six known lumiflavin-aromatic adducts were used and the models were evaluated by comparing the geometry and energetics with experimental results. The study found that dispersion-corrected and hybrid functionals with larger (>50%) Hartree-Fock exchanges produced superior results in modeling thermodynamic characteristics of these complexes. The functional producing the best energetics for these model systems was used to study the stacking interactions of lumiflavin with biologically relevant aromatic groups. Additionally, the reduction of flavin-in the presence of both a hydride donor and a nondonor π-electronic system was also studied. Weak interactions were observed in the stacked lumiflavin complexes of benzene, phenol, and indole, mimicking phenyl alanine, tryptophan, and tyrosine side chains, respectively, of an enzyme. The stacked complex of naphthalene and flavin showed little change in flavin's redox potential indicating insignificant effect on the thermodynamics of the hydride transfer reaction. In contrast, the hydride transfer reaction with the hydride donor N-methyl nicotinamide tells a different story, as the transition state was found to be strongly impacted by the stacking interactions. A comparison of performance between the density functional theory (DFT) and the computationally less expensive dispersion-corrected self-consistent density functional tight-binding (SCC-DFTB-D) theory revealed that the latter produces consistent energetics for this hydride transfer reaction and additional DFT-computed perturbative corrections could significantly improve these results.

  3. 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.

  4. Should the recommended number of IUD revisits be reduced?

    PubMed

    Janowitz, B; Hubacher, D; Petrick, T; Dighe, N

    1994-01-01

    This study uses data from clinical trials of intrauterine devices to examine the effect of reducing the recommended number of IUD follow-up visits. Over 11,000 follow-up forms were analyzed to estimate the number of health problems that would have escaped detection if women with no or mild symptoms had not made recommended revisits. Less than one percent of woman-visits with no or only mild symptoms had an underlying health risk that could have gone undetected if the follow-up visits that were made in the clinic trial setting had not been made. The results from this analysis suggest that a reduction in the number of recommended follow-up visits is safe, when measured according to selected conditions. Additional research is necessary to determine whether any revisits should be recommended in the absence of signs or symptoms.

  5. Accurate calculation of mutational effects on the thermodynamics of inhibitor binding to p38α MAP kinase: a combined computational and experimental study.

    PubMed

    Zhu, Shun; Travis, Sue M; Elcock, Adrian H

    2013-07-01

    A major current challenge for drug design efforts focused on protein kinases is the development of drug resistance caused by spontaneous mutations in the kinase catalytic domain. The ubiquity of this problem means that it would be advantageous to develop fast, effective computational methods that could be used to determine the effects of potential resistance-causing mutations before they arise in a clinical setting. With this long-term goal in mind, we have conducted a combined experimental and computational study of the thermodynamic effects of active-site mutations on a well-characterized and high-affinity interaction between a protein kinase and a small-molecule inhibitor. Specifically, we developed a fluorescence-based assay to measure the binding free energy of the small-molecule inhibitor, SB203580, to the p38α MAP kinase and used it measure the inhibitor's affinity for five different kinase mutants involving two residues (Val38 and Ala51) that contact the inhibitor in the crystal structure of the inhibitor-kinase complex. We then conducted long, explicit-solvent thermodynamic integration (TI) simulations in an attempt to reproduce the experimental relative binding affinities of the inhibitor for the five mutants; in total, a combined simulation time of 18.5 μs was obtained. Two widely used force fields - OPLS-AA/L and Amber ff99SB-ILDN - were tested in the TI simulations. Both force fields produced excellent agreement with experiment for three of the five mutants; simulations performed with the OPLS-AA/L force field, however, produced qualitatively incorrect results for the constructs that contained an A51V mutation. Interestingly, the discrepancies with the OPLS-AA/L force field could be rectified by the imposition of position restraints on the atoms of the protein backbone and the inhibitor without destroying the agreement for other mutations; the ability to reproduce experiment depended, however, upon the strength of the restraints' force constant

  6. Thermodynamics of ABC transporters.

    PubMed

    Zhang, Xuejun C; Han, Lei; Zhao, Yan

    2016-01-01

    ABC transporters form the largest of all transporter families, and their structural study has made tremendous progress over recent years. However, despite such advances, the precise mechanisms that determine the energy-coupling between ATP hydrolysis and the conformational changes following substrate binding remain to be elucidated. Here, we present our thermodynamic analysis for both ABC importers and exporters, and introduce the two new concepts of differential-binding energy and elastic conformational energy into the discussion. We hope that the structural analysis of ABC transporters will henceforth take thermodynamic aspects of transport mechanisms into account as well.

  7. Beyond Equilibrium Thermodynamics

    NASA Astrophysics Data System (ADS)

    Öttinger, Hans Christian

    2005-01-01

    Beyond Equilibrium Thermodynamics fills a niche in the market by providing a comprehensive introduction to a new, emerging topic in the field. The importance of non-equilibrium thermodynamics is addressed in order to fully understand how a system works, whether it is in a biological system like the brain or a system that develops plastic. In order to fully grasp the subject, the book clearly explains the physical concepts and mathematics involved, as well as presenting problems and solutions; over 200 exercises and answers are included. Engineers, scientists, and applied mathematicians can all use the book to address their problems in modelling, calculating, and understanding dynamic responses of materials.

  8. Effect of side by side interactions on the thermodynamic properties of adsorbed CO molecules on the Ni(111) surface: a cluster model study

    NASA Astrophysics Data System (ADS)

    Shamkhali, Amir N.; Parsafar, Gholamabbas

    2010-05-01

    The effect of electrostatic interactions on vibrational frequencies and thermodynamic properties of CO adsorbate on the Ni(111) surface is calculated by taking the first and second nearest-neighbour interactions into account. In order to obtain reasonable results, the cluster model of various surface adsorption sites with CO adsorbate is partially optimized, using Density Functional Theory and also the MP2 method for the hcp site. Comparison between DFT and MP2 results shows that DFT results are more reliable for this system. The stretching and bending frequencies of CO adsorbate are calculated using both Partial Hessian Analysis and Cluster-Adsorbate Coupling methods. Stretching and bending frequencies are both shifted by the side by side interactions. The coupling of surface phonons and adsorbate vibrations reduces the side effects. The largest side effects on the vibrational internal energy, isochoric heat capacity, entropy and total Helmholtz free energy of adsorbed CO molecule calculated using the CAC method are found for 0.5 ML coverage. The results of the CAC method are better, but the PHA method can be used as a simple upper bound estimation. The adsorptive phase acts as an intelligent material in such a way that it changes its configuration in order to reduce the side effects.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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)

  15. 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.

  16. 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.

  17. 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)

  18. 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.

  19. 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.

  20. Thermodynamics in dynamical spacetimes

    NASA Astrophysics Data System (ADS)

    Tresguerres, Romualdo

    2014-03-01

    We derive a general formulation of the laws of irreversible thermodynamics in the presence of electromagnetism and gravity. For the handling of macroscopic material media, we use as a guide the field equations and the Noether identities of fundamental matter as deduced in the framework of gauge theories of the Poincaré ⊗ U(1) group.

  1. 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…

  2. 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.…

  3. 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.

  4. Thermodynamic Curvature and Black Holes

    NASA Astrophysics Data System (ADS)

    Ruppeiner, George

    In my talk, I will discuss black hole thermodynamics, particularly what happens when you add thermodynamic curvature to the mix. Although black hole thermodynamics is a little off the main theme of this workshop, I hope nevertheless that my message will be of some interest to researchers in supersymmetry and supergravity.

  5. 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.

  6. Black hole thermodynamics based on unitary evolutions

    NASA Astrophysics Data System (ADS)

    Feng, Yu-Lei; Chen, Yi-Xin

    2015-10-01

    In this paper, we try to construct black hole thermodynamics based on the fact that the formation and evaporation of a black hole can be described by quantum unitary evolutions. First, we show that the Bekenstein-Hawking entropy SBH may not be a Boltzmann or thermal entropy. To confirm this statement, we show that the original black hole's ‘first law’ may not simply be treated as the first law of thermodynamics formally, due to some missing metric perturbations caused by matter. Then, by including those (quantum) metric perturbations, we show that the black hole formation and evaporation can be described effectively in a unitary manner, through a quantum channel between the exterior and interior of the event horizon. In this way, the paradoxes of information loss and firewall can be resolved effectively. Finally, we show that black hole thermodynamics can be constructed in an ordinary way, by constructing statistical mechanics.

  7. Lithium in the Pleiades Revisited

    NASA Astrophysics Data System (ADS)

    King, J. R.; Hobbs, L. M.; Schuler, S. C.; Pinsonneault, M. H.

    2003-12-01

    New Li abundances have been derived for some 15-20 Pleiades dwarfs using new high-resolution and high S/N spectroscopy from HET/HRS. Previous studies suggested that our objects, all modest (projected) rotators, evinced considerable scatter in their Li abundances. We revisit the question of this scatter and its origin. This work has been supported by NSF grants AST 00-86576 and 02-39518, a South Carolina Space Grant Scholarship award, a generous donation from the Curry Foundation of Seneca, SC, and the NOAO Public Access Program.

  8. Thermodynamics of random reaction networks.

    PubMed

    Fischer, Jakob; Kleidon, Axel; Dittrich, Peter

    2015-01-01

    Reaction networks are useful for analyzing reaction systems occurring in chemistry, systems biology, or Earth system science. Despite the importance of thermodynamic disequilibrium for many of those systems, the general thermodynamic properties of reaction networks are poorly understood. To circumvent the problem of sparse thermodynamic data, we generate artificial reaction networks and investigate their non-equilibrium steady state for various boundary fluxes. We generate linear and nonlinear networks using four different complex network models (Erdős-Rényi, Barabási-Albert, Watts-Strogatz, Pan-Sinha) and compare their topological properties with real reaction networks. For similar boundary conditions the steady state flow through the linear networks is about one order of magnitude higher than the flow through comparable nonlinear networks. In all networks, the flow decreases with the distance between the inflow and outflow boundary species, with Watts-Strogatz networks showing a significantly smaller slope compared to the three other network types. The distribution of entropy production of the individual reactions inside the network follows a power law in the intermediate region with an exponent of circa -1.5 for linear and -1.66 for nonlinear networks. An elevated entropy production rate is found in reactions associated with weakly connected species. This effect is stronger in nonlinear networks than in the linear ones. Increasing the flow through the nonlinear networks also increases the number of cycles and leads to a narrower distribution of chemical potentials. We conclude that the relation between distribution of dissipation, network topology and strength of disequilibrium is nontrivial and can be studied systematically by artificial reaction networks.

  9. Thermodynamics of random reaction networks.

    PubMed

    Fischer, Jakob; Kleidon, Axel; Dittrich, Peter

    2015-01-01

    Reaction networks are useful for analyzing reaction systems occurring in chemistry, systems biology, or Earth system science. Despite the importance of thermodynamic disequilibrium for many of those systems, the general thermodynamic properties of reaction networks are poorly understood. To circumvent the problem of sparse thermodynamic data, we generate artificial reaction networks and investigate their non-equilibrium steady state for various boundary fluxes. We generate linear and nonlinear networks using four different complex network models (Erdős-Rényi, Barabási-Albert, Watts-Strogatz, Pan-Sinha) and compare their topological properties with real reaction networks. For similar boundary conditions the steady state flow through the linear networks is about one order of magnitude higher than the flow through comparable nonlinear networks. In all networks, the flow decreases with the distance between the inflow and outflow boundary species, with Watts-Strogatz networks showing a significantly smaller slope compared to the three other network types. The distribution of entropy production of the individual reactions inside the network follows a power law in the intermediate region with an exponent of circa -1.5 for linear and -1.66 for nonlinear networks. An elevated entropy production rate is found in reactions associated with weakly connected species. This effect is stronger in nonlinear networks than in the linear ones. Increasing the flow through the nonlinear networks also increases the number of cycles and leads to a narrower distribution of chemical potentials. We conclude that the relation between distribution of dissipation, network topology and strength of disequilibrium is nontrivial and can be studied systematically by artificial reaction networks. PMID:25723751

  10. 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.

  11. 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.

  12. 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).

  13. 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.

  14. Effects of the single-ion anisotropy on magnetic and thermodynamic properties of a ferrimagnetic mixed-spin (1, 3/2) cylindrical Ising nanowire

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Bi, Jiang-lin; Liu, Rui-jia; Chen, Xu; Liu, Jin-ping

    2016-10-01

    Monte Carlo simulation has been performed in detail to study magnetic and thermodynamic properties of a ferrimagnetic mixed-spin (1, 3/2) cylindrical Ising nanowire with core-shell structure. The ground phase diagrams are obtained for different single-ion anisotropies. The system can display rich phase transitions such as the second- and first-order phase transitions, the tricritical points and the compensation points. Especially, emphasis has been given to the effects of the single-ion anisotropy and the temperate on the magnetization, the internal energy, the specific heat, the compensation points and hysteresis loops of the system as well as two sublattices. A number of characteristic phenomena such as such as various types of magnetization curves and triple, duadruple as well as quintuple hysteresis loops behaviors have been observed for certain physical parameters, originating from the competitions among the anisotropies, temperature and the longitudinal magnetic field. It is found that the single-ion anisotropy and the temperature strongly affect the coercivity and the remanence of the system. A satisfactory agreement can be achieved from comparisons between our results and previous theoretical and experimental works.

  15. 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.

  16. CODATA thermodynamic tables

    SciTech Connect

    Garvin, D.; Parker, V.B.; White, H.J. Jr.

    1987-01-01

    Recommended values are presented for chemical thermodynamic properties of selected compounds of calcium and their mixtures. These have been prepared in accord with a previously developed plan and as a test of it. All values in the present table are mutually consistent and are consistent with the CODATA Key Values for Thermodynamics. The values are recommended for general use. This work has been an activity of the CODATA Task Group on Chemical Thermodynamic Tables. The evaluated data are for common compounds of calcium (element, oxide, hydroxide, peroxide, fluoride, sulfate, nitrate and carbonate, their hydrates and their ions in aqueous solution) and for three systems: Ca-Mg, CaCl/sub 2/-KCl and CaCl/sub 2/-H/sub 2/O. Forty one tables of thermal functions (heat capacity, entropy, enthalpy, and Gibbs energy functions) are given for those compounds of magnesium, calcium and potassium for which the properties have been evaluated in this work. Twenty four tables of thermal functions are given for auxiliary substances. Each table spans the temperature range 0 to 4000 K, to the extent that data are available. Formation properties at 298.15 K (enthalpy and Gibbs energy of formation) are given for 68 compounds of calcium, magnesium and potassium plus the relevant values for 54 auxiliary substances.

  17. 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.

  18. 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.

  19. Thermodynamics Insights for the Redshift Drift

    NASA Astrophysics Data System (ADS)

    Zhang, Ming-Jian; Liu, Wen-Biao

    2015-01-01

    The secular redshift drift is a potential measurement to directly probe the cosmic expansion. Previous study on the redshift drift mainly focused on the model-dependent simulation. Apparently, the physical insights on the redshift drift are very necessary. So in this paper, it is investigated using thermodynamics on the apparent, Hubble and event horizons. Thermodynamics could analytically present the model-independent upper bounds of redshift drift. For specific assumption on the cosmological parameters, we find that the thermodynamics bounds are nearly one order of magnitude larger than the expectation in standard ΛCDM model. We then examine ten observed redshift drift from Green Bank Telescope at redshift 0.09 < z < 0.69, and find that these observational results are inconsistent with the thermodynamics. The size of the errorbars on these measurements is about three orders of magnitude larger than the effect of thermodynamical bounds for the redshift drift. Obviously, we have not yet hit any instrumental systematics at the shift level of 1m s-1 yr-1.

  20. A thermodynamic formulation of root water uptake

    NASA Astrophysics Data System (ADS)

    Hildebrandt, Anke; Kleidon, Axel; Bechmann, Marcel

    2016-08-01

    By extracting bound water from the soil and lifting it to the canopy, root systems of vegetation perform work. Here we describe how root water uptake can be evaluated thermodynamically and demonstrate that this evaluation provides additional insights into the factors that impede root water uptake. We derive an expression that relates the energy export at the base of the root system to a sum of terms that reflect all fluxes and storage changes along the flow path in thermodynamic terms. We illustrate this thermodynamic formulation using an idealized setup of scenarios with a simple model. In these scenarios, we demonstrate why heterogeneity in soil water distribution and rooting properties affect the impediment of water flow even though the mean soil water content and rooting properties are the same across the scenarios. The effects of heterogeneity can clearly be identified in the thermodynamics of the system in terms of differences in dissipative losses and hydraulic energy, resulting in an earlier start of water limitation in the drying cycle. We conclude that this thermodynamic evaluation of root water uptake conveniently provides insights into the impediments of different processes along the entire flow path, which goes beyond resistances and also accounts for the role of heterogeneity in soil water distribution.

  1. 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

  2. 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

  3. 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.

  4. Thermodynamic optimization of a Penrose process: An engineers' approach to black hole thermodynamics

    NASA Astrophysics Data System (ADS)

    Bravetti, A.; Gruber, C.; Lopez-Monsalvo, C. S.

    2016-03-01

    In this work we present a new view on the thermodynamics of black holes introducing effects of irreversibility by employing thermodynamic optimization and finite-time thermodynamics. These questions are of importance both in physics and in engineering, combining standard thermodynamics with optimal control theory in order to find optimal protocols and bounds for realistic processes without assuming anything about the microphysics involved. We work out the details of the thermodynamic optimization of a Penrose process, i.e. the problem of finding the maximum work that can be extracted from a Kerr black hole in finite time. This problem has already been addressed in the case of an isolated black hole. Here we consider the case of a black hole immersed in a reservoir and show that the presence of the reservoir can dramatically improve the work output. We discuss the relevance of our results for real astrophysical phenomena, for the comparison with laboratory black holes analogues and for other theoretical aspects of black hole thermodynamics.

  5. 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…

  6. 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…

  7. Thermodynamic and kinetic investigations of the release of oxidized phospholipids from lipid membranes and its effect on vascular integrity

    PubMed Central

    Heffern, Charles T.R.; Pocivavsek, Luka; Birukova, Anna A.; Moldobaeva, Nurgul; Bochkov, Valery N.; Lee, Ka Yee C.; Birukov, Konstantin G.

    2013-01-01

    The lipid membrane not only provides a rich interface with an array of receptor signaling complexes with which a cell communicates, but it also serves as a source of lipid derived bioactive molecules. In pathologic conditions of acute lung injury (ALI) associated with activation of oxidative stress, unsaturated phosphatidyl cholines overlooking a luminal space undergo oxidation leading to generation of fragmented phospholipids such as 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine (lysoPC), or 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PAPC) full length oxygenation products (oxPAPC). Using Langmuir monolayers as models of the lipid bilayer, we evaluated the propensity of these phospholipids to solubilize from the cell membrane. The results suggest that lysoPC is rapidly released as it is produced, while oxPAPC has a longer membrane bound lifetime. After being released from cell membranes, these oxidized phospholipids exhibit potent agonist-like effects on neighboring cells. Therefore, we correlate the presence of the two phospholipid groups with the onset and resolution of increased vascular leakiness associated with ALI through testing their effect on vascular endothelial barrier integrity. Our work shows that cells respond differently to these two groups of products of phosphatidyl choline oxidation. LysoPC disrupts cell–cell junctions and increases endothelial permeability while oxPAPC enhances endothelial barrier. These data suggest a model whereby rapid release of lysoPC results in onset of ALI associated vascular leak, and the release of a reserve of oxPAPC as oxidative stress subsides restores the vascular barrier properties. PMID:23911706

  8. Conceptests for a Chemical Engineering Thermodynamics Course

    ERIC Educational Resources Information Center

    Falconer, John L.

    2007-01-01

    Examples of conceptests and suggestions for preparing them for use in an undergraduate, chemical engineering thermodynamics course are presented. Conceptests, combined with hand-held transmitters (clickers), is an effective method to engage students in class. This method motivates students, improves their functional understanding of…

  9. Heat Transfer and Thermodynamics: a Compilation

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A compilation is presented for the dissemination of information on technological developments which have potential utility outside the aerospace and nuclear communities. Studies include theories and mechanical considerations in the transfer of heat and the thermodynamic properties of matter and the causes and effects of certain interactions.

  10. 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.

  11. 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.

  12. 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

    PubMed Central

    Petrov, Anton S.; Douglas, Scott S.; Harvey, Stephen C.

    2013-01-01

    In the current 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 torsionless 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 dependency 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. PMID:23399864

  13. Thermodynamics of quantum heat engines

    NASA Astrophysics Data System (ADS)

    Goswami, Himangshu Prabal; Harbola, Upendra

    2013-07-01

    We consider a recently proposed four-level quantum heat engine (QHE) model to analyze the role of quantum coherences in determining the thermodynamic properties of the engine, such as flux, output power, and efficiency. A quantitative analysis of the relative effects of the coherences induced by the two thermal baths is brought out. By taking account of the dissipation in the cavity mode, we define useful work obtained from the QHE and present some analytical results for the optimal values of relative coherences that maximizes flux (hence output power) through the engine. We also analyze the role of quantum effects in inducing population inversion (lasing) between the states coupled to the cavity mode. The universal behavior of the efficiency at maximum power (EMP) is examined. In accordance with earlier theoretical predictions, to leading order, we find that EMP˜ηc/2, where ηc is Carnot efficiency. However, the next higher order coefficient is system dependent and hence nonuniversal.

  14. 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

  15. 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.

  16. 'What price speed', revisited

    NASA Astrophysics Data System (ADS)

    Teitler, S.; Proodian, R. E.

    1980-02-01

    An attempt is made to examine fuel transport effectiveness as a function of vehicle cruise velocity, when studying limits in speed beyond which a particular form of locomotion becomes inefficient and economically unattractive. Attention is given to the Dix-Riddell relationship and to the specific fuel energy expenditure ratio. It is concluded that for each value of speed at which useful work is carried out, there is an experiential maximum that sets the standard for fuel transport effectiveness at that speed.

  17. Effects of Zeolite Structural Confinement on Adsorption Thermodynamics and Reaction Kinetics for Monomolecular Cracking and Dehydrogenation of n-Butane.

    PubMed

    Janda, Amber; Vlaisavljevich, Bess; Lin, Li-Chiang; Smit, Berend; Bell, Alexis T

    2016-04-13

    The effects of zeolite structure on the kinetics of n-butane monomolecular cracking and dehydrogenation are investigated for eight zeolites differing in the topology of channels and cages. Monte Carlo simulations are used to calculate enthalpy and entropy changes for adsorption (ΔHads-H+ and ΔSads-H+) of gas-phase alkanes onto Brønsted protons. These parameters are used to extract intrinsic activation enthalpies (ΔHint‡), entropies (ΔSint‡), and rate coefficients (kint) from measured data. As ΔSads-H+ decreases (i.e., as confinement increases), ΔHint‡ and ΔSint‡ for terminal cracking and dehydrogenation decrease for a given channel topology. These results, together with positive values observed for ΔSint‡, indicate that the transition states for these reactions resemble products. For central cracking (an earlier transition state), ΔHint‡ is relatively constant, while ΔSint‡ increases as ΔSads-H+ decreases because less entropy is lost upon protonation of the alkane. Concurrently, selectivities to terminal cracking and dehydrogenation decrease relative to central cracking because ΔSint‡ decreases for the former reactions. Depending on channel topology, changes in the measured rate coefficients (kapp) with confinement are driven by changes in kint or by changes in the adsorption equilibrium constant (Kads-H+). Values of ΔSint‡ and ΔHint‡ are positively correlated, consistent with weaker interactions between the zeolite and transition state and with the greater freedom of movement of product fragments within more spacious pores. These results differ from earlier reports that ΔHint‡ and ΔSint‡ are structure-insensitive and that kapp is dominated by Kads-H+. They also suggest that ΔSads-H+ is a meaningful descriptor of confinement for zeolites having similar channel topologies. PMID:26909765

  18. RNA Thermodynamic Structural Entropy

    PubMed Central

    Garcia-Martin, Juan Antonio; Clote, Peter

    2015-01-01

    Conformational entropy for atomic-level, three dimensional biomolecules is known experimentally to play an important role in protein-ligand discrimination, yet reliable computation of entropy remains a difficult problem. Here we describe the first two accurate and efficient algorithms to compute the conformational entropy for RNA secondary structures, with respect to the Turner energy model, where free energy parameters are determined from UV absorption experiments. An algorithm to compute the derivational entropy for RNA secondary structures had previously been introduced, using stochastic context free grammars (SCFGs). However, the numerical value of derivational entropy depends heavily on the chosen context free grammar and on the training set used to estimate rule probabilities. Using data from the Rfam database, we determine that both of our thermodynamic methods, which agree in numerical value, are substantially faster than the SCFG method. Thermodynamic structural entropy is much smaller than derivational entropy, and the correlation between length-normalized thermodynamic entropy and derivational entropy is moderately weak to poor. In applications, we plot the structural entropy as a function of temperature for known thermoswitches, such as the repression of heat shock gene expression (ROSE) element, we determine that the correlation between hammerhead ribozyme cleavage activity and total free energy is improved by including an additional free energy term arising from conformational entropy, and we plot the structural entropy of windows of the HIV-1 genome. Our software RNAentropy can compute structural entropy for any user-specified temperature, and supports both the Turner’99 and Turner’04 energy parameters. It follows that RNAentropy is state-of-the-art software to compute RNA secondary structure conformational entropy. Source code is available at https://github.com/clotelab/RNAentropy/; a full web server is available at http

  19. RNA Thermodynamic Structural Entropy.

    PubMed

    Garcia-Martin, Juan Antonio; Clote, Peter

    2015-01-01

    Conformational entropy for atomic-level, three dimensional biomolecules is known experimentally to play an important role in protein-ligand discrimination, yet reliable computation of entropy remains a difficult problem. Here we describe the first two accurate and efficient algorithms to compute the conformational entropy for RNA secondary structures, with respect to the Turner energy model, where free energy parameters are determined from UV absorption experiments. An algorithm to compute the derivational entropy for RNA secondary structures had previously been introduced, using stochastic context free grammars (SCFGs). However, the numerical value of derivational entropy depends heavily on the chosen context free grammar and on the training set used to estimate rule probabilities. Using data from the Rfam database, we determine that both of our thermodynamic methods, which agree in numerical value, are substantially faster than the SCFG method. Thermodynamic structural entropy is much smaller than derivational entropy, and the correlation between length-normalized thermodynamic entropy and derivational entropy is moderately weak to poor. In applications, we plot the structural entropy as a function of temperature for known thermoswitches, such as the repression of heat shock gene expression (ROSE) element, we determine that the correlation between hammerhead ribozyme cleavage activity and total free energy is improved by including an additional free energy term arising from conformational entropy, and we plot the structural entropy of windows of the HIV-1 genome. Our software RNAentropy can compute structural entropy for any user-specified temperature, and supports both the Turner'99 and Turner'04 energy parameters. It follows that RNAentropy is state-of-the-art software to compute RNA secondary structure conformational entropy. Source code is available at https://github.com/clotelab/RNAentropy/; a full web server is available at http

  20. Methods for First-Principles Alloy Thermodynamics

    NASA Astrophysics Data System (ADS)

    van de Walle, Axel

    2013-11-01

    Traditional first-principles calculations excel at providing formation energies at absolute zero, but obtaining thermodynamic information at nonzero temperatures requires suitable sampling of all the excited states visited in thermodynamic equilibrium, which would be computationally prohibitive via brute-force quantum mechanical calculations alone. In the context of solid-state alloys, this issue can be addressed via the coarse-graining concept and the cluster expansion formalism. This process generates simple, effective Hamiltonians that accurately reproduce quantum mechanical calculation results and that can be used to efficiently sample configurational, vibrational, and electronic excitations and enable the prediction of thermodynamic properties at nonzero temperatures. Vibrational and electronic degrees of freedom are formally eliminated from the problem by writing the system's partition function in a nested form in which the inner sums can be readily evaluated to yield an effective Hamiltonian. The remaining outermost sum corresponds to atomic configurations and can be handled via Monte Carlo sampling driven by the resulting effective Hamiltonian, thereby delivering thermodynamic properties at nonzero temperatures. This article describes these techniques and their implementation in the alloy theoretic automated toolkit, an open-source software package. The methods are illustrated by applications to various alloy systems.