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Sample records for interactions activation enthalpies

  1. Immersion enthalpies of activated carbon cloths as physical chemistry characterization parameter

    International Nuclear Information System (INIS)

    Rodriguez, Giovanny; Giraldo, Liliana; Moreno Juan Carlos

    2009-01-01

    The immersion enthalpies of five activated carbon cloths in carbon, CCl 4 , H 2 O and NaOH and HCl 0.1 M solutions are determined. The surface area values of the cloths are between 243 and 848 m 2 g-1 and exhibit a linear relationship with the immersion enthalpies in CCl 4 . The immersion enthalpies of carbon cloths are between 5.49 and 42.3 Jg-1 for CCl 4 and 3.83 and 7.54 Jg-1 for H 2 O. The immersion enthalpies in the solutions are related to the contents of acidic and basic groups and find that in the first case to increase the immersion enthalpy in NaOH increases the total acidity. Hydrophobic factor is calculated from the immersion enthalpies in CCl 4 and H 2 O, that indicate the interaction with polar and a polar compounds, and also relates to pHPZC each sample.

  2. Measuring the enthalpies of interaction between glycine, L-cysteine, glycylglycine, and sodium dodecyl sulfate in aqueous solutions

    Science.gov (United States)

    Badelin, V. G.; Mezhevoi, I. N.; Tyunina, E. Yu.

    2017-03-01

    Calorimetric measurements of enthalpies of solution Δsol H m for glycine, L-cysteine, and glycylglycine in aqueous solutions of sodium dodecyl sulfate (SDS) with concentrations of up to 0.05 mol kg-1 are made. Standard enthalpy of solution Δsol H 0 and enthalpy of transfer Δtr H 0 of the dipeptide from water into mixed solvent are calculated. The calculated enthalpy coefficients of paired interactions of amino acids and dipeptide with SDS prove to be positive. Hydrophobic interactions between the biomolecules and SDS are found to have a major impact on the enthalpies of interaction in the three-component systems under study, within the indicated range of concentrations.

  3. PREDICTION OF THE MIXING ENTHALPIES OF BINARY LIQUID ALLOYS BY MOLECULAR INTERACTION VOLUME MODEL

    Institute of Scientific and Technical Information of China (English)

    H.W.Yang; D.P.Tao; Z.H.Zhou

    2008-01-01

    The mixing enthalpies of 23 binary liquid alloys are calculated by molecular interaction volume model (MIVM), which is a two-parameter model with the partial molar infinite dilute mixing enthalpies. The predicted values are in agreement with the experimental data and then indicate that the model is reliable and convenient.

  4. Dominant Alcohol-Protein Interaction via Hydration-Enabled Enthalpy-Driven Binding Mechanism

    Science.gov (United States)

    Chong, Yuan; Kleinhammes, Alfred; Tang, Pei; Xu, Yan; Wu, Yue

    2015-01-01

    Water plays an important role in weak associations of small drug molecules with proteins. Intense focus has been on binding-induced structural changes in the water network surrounding protein binding sites, especially their contributions to binding thermodynamics. However, water is also tightly coupled to protein conformations and dynamics, and so far little is known about the influence of water-protein interactions on ligand binding. Alcohols are a type of low-affinity drugs, and it remains unclear how water affects alcohol-protein interactions. Here, we present alcohol adsorption isotherms under controlled protein hydration using in-situ NMR detection. As functions of hydration level, Gibbs free energy, enthalpy, and entropy of binding were determined from the temperature dependence of isotherms. Two types of alcohol binding were found. The dominant type is low-affinity nonspecific binding, which is strongly dependent on temperature and the level of hydration. At low hydration levels, this nonspecific binding only occurs above a threshold of alcohol vapor pressure. An increased hydration level reduces this threshold, with it finally disappearing at a hydration level of h~0.2 (g water/g protein), gradually shifting alcohol binding from an entropy-driven to an enthalpy-driven process. Water at charged and polar groups on the protein surface was found to be particularly important in enabling this binding. Although further increase in hydration has smaller effects on the changes of binding enthalpy and entropy, it results in significant negative change in Gibbs free energy due to unmatched enthalpy-entropy compensation. These results show the crucial role of water-protein interplay in alcohol binding. PMID:25856773

  5. Kinetic evidence of an apparent negative activation enthalpy in an organocatalytic process

    KAUST Repository

    Han, Xiao

    2013-08-30

    A combined kinetic and computational study on our tryptophan-based bifunctional thiourea catalyzed asymmetric Mannich reactions reveals an apparent negative activation enthalpy. The formation of the pre-transition state complex has been unambiguously confirmed and these observations provide an experimental support for the formation of multiple hydrogen bonding network between the substrates and the catalyst. Such interactions allow the creation of a binding cavity, a key factor to install high enantioselectivity.

  6. Kinetic evidence of an apparent negative activation enthalpy in an organocatalytic process

    KAUST Repository

    Han, Xiao; Lee, Richmond; Chen, Tao; Luo, Jie; Lu, Yixin; Huang, Kuo-Wei

    2013-01-01

    A combined kinetic and computational study on our tryptophan-based bifunctional thiourea catalyzed asymmetric Mannich reactions reveals an apparent negative activation enthalpy. The formation of the pre-transition state complex has been unambiguously confirmed and these observations provide an experimental support for the formation of multiple hydrogen bonding network between the substrates and the catalyst. Such interactions allow the creation of a binding cavity, a key factor to install high enantioselectivity.

  7. Relation between the adsorbed quantity and the immersion enthalpy in catechol aqueous solutions on activated carbons.

    Science.gov (United States)

    Moreno-Piraján, Juan Carlos; Blanco, Diego; Giraldo, Liliana

    2012-01-01

    An activated carbon, Carbochem(TM)-PS230, was modified by chemical and thermal treatment in flow of H(2), in order to evaluate the influence of the activated carbon chemical characteristics in the adsorption of the catechol. The catechol adsorption in aqueous solution was studied along with the effect of the pH solution in the adsorption process of modified activated carbons and the variation of immersion enthalpy of activated carbons in the aqueous solutions of catechol. The interaction solid-solution is characterized by adsorption isotherms analysis, at 298 K and pH 7, 9 and 11 in order to evaluate the adsorption value above and below that of the catechol pK(a). The adsorption capacity of carbons increases when the solution pH decreases. The retained amount increases slightly in the reduced carbon to maximum adsorption pH and diminishes in the oxidized carbon. Similar conclusions are obtained from the immersion enthalpies, whose values increase with the solute quantity retained. In granular activated carbon (CAG), the immersion enthalpies obtained are between 21.5 and 45.7 J·g(-1) for catechol aqueous solutions in a range of 20 at 1500 mg·L(-1).

  8. Relation Between the Adsorbed Quantity and the Immersion Enthalpy in Catechol Aqueous Solutions on Activated Carbons

    Directory of Open Access Journals (Sweden)

    Liliana Giraldo

    2011-12-01

    Full Text Available An activated carbon, CarbochemTM—PS230, was modified by chemical and thermal treatment in flow of H2, in order to evaluate the influence of the activated carbon chemical characteristics in the adsorption of the catechol. The catechol adsorption in aqueous solution was studied along with the effect of the pH solution in the adsorption process of modified activated carbons and the variation of immersion enthalpy of activated carbons in the aqueous solutions of catechol. The interaction solid-solution is characterized by adsorption isotherms analysis, at 298 K and pH 7, 9 and 11 in order to evaluate the adsorption value above and below that of the catechol pKa. The adsorption capacity of carbons increases when the solution pH decreases. The retained amount increases slightly in the reduced carbon to maximum adsorption pH and diminishes in the oxidized carbon. Similar conclusions are obtained from the immersion enthalpies, whose values increase with the solute quantity retained. In granular activated carbon (CAG, the immersion enthalpies obtained are between 21.5 and 45.7 J·g−1 for catechol aqueous solutions in a range of 20 at 1500 mg·L−1.

  9. Insights on activation enthalpy for non-Schmid slip in body-centered cubic metals

    International Nuclear Information System (INIS)

    Hale, Lucas M.; Lim, Hojun; Zimmerman, Jonathan A.; Battaile, Corbett C.; Weinberger, Christopher R.

    2015-01-01

    We use insights gained from atomistic simulation to develop an activation enthalpy model for dislocation slip in body-centered cubic iron. Using a classical potential that predicts dislocation core stabilities consistent with ab initio predictions, we quantify the non-Schmid stress-dependent effects of slip. The kink-pair activation enthalpy is evaluated and a model is identified as a function of the general stress state. Our model enlarges the applicability of the classic Kocks activation enthalpy model to materials with non-Schmid behavior

  10. Relation Between the Adsorbed Quantity and the Immersion Enthalpy in Catechol Aqueous Solutions on Activated Carbons

    OpenAIRE

    Moreno-Piraj?n, Juan Carlos; Blanco, Diego; Giraldo, Liliana

    2011-01-01

    An activated carbon, CarbochemTM—PS230, was modified by chemical and thermal treatment in flow of H2, in order to evaluate the influence of the activated carbon chemical characteristics in the adsorption of the catechol. The catechol adsorption in aqueous solution was studied along with the effect of the pH solution in the adsorption process of modified activated carbons and the variation of immersion enthalpy of activated carbons in the aqueous solutions of catechol. The interaction solid-so...

  11. Enthalpies of solution, enthalpies of fusion and enthalpies of solvation of polyaromatic hydrocarbons: Instruments for determination of sublimation enthalpy at 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Solomonov, Boris N., E-mail: boris.solomonov@ksu.ru; Varfolomeev, Mikhail A.; Nagrimanov, Ruslan N.; Mukhametzyanov, Timur A.; Novikov, Vladimir B.

    2015-12-20

    Graphical abstract: - Highlights: • Solution enthalpies of aromatic hydrocarbons were measured at 298.15 K. • Solution enthalpy of aromatic hydrocarbons in benzene is equal to their fusion enthalpy. • Method for calculation of solvation enthalpy of aromatic hydrocarbons was proposed. • Approach for estimation of aromatic hydrocarbons sublimation enthalpy was developed. • Obtained sublimation enthalpies coincide well with the recommended literature data. - Abstract: In this work a simple method for calculation of solvation enthalpies of polyaromatic hydrocarbons (PAHs) in various solvents at 298.15 K was proposed. According to this method the enthalpy of solvation of any polyaromatic hydrocarbon in a particular solvent can be calculated on the basis of the general formula of the compound, the solvation enthalpy of benzene in the same solvent and parameter related to the contribution of hydrogen atom into solvation enthalpy. The validity of the proposed method was confirmed by the comparison of calculated and experimentally measured values of solvation enthalpies of PAHs in benzene, tetrahydrofuran and acetonitrile. This method was used for determination of the sublimation enthalpy of PAHs at 298.15 K based on the general relationship between the enthalpy of sublimation/vaporization of the compound of interest and its enthalpies of solution and solvation in the same solvent at 298.15 K. Enthalpies of solution at infinite dilution of several PAHs were measured in acetonitrile, benzene and tetrahydrofuran at 298.15 K. It was shown that solution enthalpies of PAHs in benzene at 298.15 K are approximately equal to their fusion enthalpies at the melting temperature. Solvation enthalpies of 15 PAHs at 298.15 K calculated according to the proposed method together with corresponding fusion enthalpy values (at the melting temperature) were used to calculate the sublimation enthalpy values at 298.15 K. Comparison of the obtained results with recommended values of

  12. Effect of the pH in the adsorption and in the immersion enthalpy of monohydroxylated phenols from aqueous solutions on activated carbons.

    Science.gov (United States)

    Blanco-Martínez, D A; Giraldo, L; Moreno-Piraján, J C

    2009-09-30

    An activated carbon Carbochem--PS230 was modified by chemical and thermal treatment in flow of H(2) in order to evaluate the influence of the activated carbon chemical surface in the adsorption of the monohydroxylated phenols. The solid-solution interaction was determined by analyzing the adsorption isotherms at 298 K at pH 7, 9 and 11 during 48 h. The adsorption capacity of activated carbons increases when the pH solution decreases. The amount adsorbed increases in the reduced carbon at the maximum adsorption pH and decreases in the oxidized carbon. In the sample of granulated activated carbon, CAG, the monohydroxylated phenols adsorption capacity diminishes in the following order catechol >hydroquinone >resorcinol, at the three pH values. The experimental data are evaluated with Freundlich's and Langmuir's models. The immersion enthalpies are determined and increase with the retained amount, ranging between 21.5 and 45.7 J g(-1). In addition, the immersion enthalpies show more interaction with the reduced activated carbon that has lower total acidity contents.

  13. Enthalpies of fusion and enthalpies of solvation of aromatic hydrocarbons derivatives: Estimation of sublimation enthalpies at 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Solomonov, Boris N., E-mail: boris.solomonov@kpfu.ru; Nagrimanov, Ruslan N.; Varfolomeev, Mikhail A.; Buzyurov, Aleksey V.; Mukhametzyanov, Timur A.

    2016-03-20

    Graphical abstract: - Highlights: • Solution enthalpies of aromatic hydrocarbons derivatives (ArHD) were measured at 298.15 K. • Solution enthalpies of ArHD in benzene at 298.15 K are equal to their fusion enthalpy at melting point. • Sublimation enthalpies of 80 ArHD were calculated as a sum of fusion and solvation enthalpies. • Obtained sublimation enthalpies are in good agreement with the recommended literature data. - Abstract: Enthalpy of sublimation of solid compound can be found using the values of solution enthalpy and solvation enthalpy in any solvent. In this work enthalpies of solution at infinite dilution of a number of aromatic hydrocarbons derivatives in benzene were measured at 298.15 K. Comparison between experimental and literature solution enthalpies in benzene at 298.15 K and fusion enthalpies at melting temperature of aromatic hydrocarbon derivatives showed, that these values are approximately equal. Thereby, fusion enthalpies at melting temperature can be used instead of their solution enthalpies in benzene at 298.15 K for calculation of sublimation enthalpies at 298.15 K. Solvation enthalpies in benzene at 298.15 K required for this procedure were calculated using group additivity scheme. The sublimation enthalpies of 80 aromatic hydrocarbons derivatives at 298.15 K were evaluated as a difference between fusion enthalpies at melting temperature and solvation enthalpies in benzene at 298.15 K. Obtained in this work values of sublimation enthalpy at 298.15 K for studied compounds were in a good agreement with available literature data.

  14. Interaction enthalpies of solid human serum albumin with water-dioxane mixtures: comparison with water and organic solvent vapor sorption

    International Nuclear Information System (INIS)

    Sirotkin, Vladimir A.; Faizullin, Djihanguir A.

    2004-01-01

    Enthalpy changes (ΔH tot ) on the immersion of dehydrated human serum albumin (HSA) into water-dioxane mixtures have been measured using a Setaram BT-2.15 calorimeter at 298 K. Thermodynamic activity of water was varied from 0 to 1. Calorimetric results are discussed together with the FTIR-spectroscopic data on water and organic solvent vapor adsorption/desorption isotherms on solid HSA. Dioxane sorption exhibits a pronounced hysteresis. Calorimetric and dioxane desorption dependencies consist of two parts. No dioxane sorption was observed in low water activity region (a w tot values are close to zero. At water activity about 0.5 the sharp exothermic drop of the interaction enthalpy values was observed. This exothermic drop is accompanied by the sharp increase in the amount of sorbed dioxane and additional water sorption (compared with that for pure water). Dioxane adsorption branch resembles a smooth curve. In this case, solid HSA binds more than 300 mol dioxane/mol HSA at low water activities. By using a water activity-based comparison we distinguished between dioxane-assisted and dioxane-competitive effect on water sorption. The obtained results demonstrate that the hydration 'history' of solid protein is an important factor that controls as the state of protein macromolecule as well as the sorption of low-molecular organic molecules

  15. Examination of hydrogen-bonding interactions between dissolved solutes and alkylbenzene solvents based on Abraham model correlations derived from measured enthalpies of solvation

    Energy Technology Data Exchange (ETDEWEB)

    Varfolomeev, Mikhail A.; Rakipov, Ilnaz T. [Chemical Institute, Kazan Federal University, Kremlevskaya 18, Kazan 420008 (Russian Federation); Acree, William E., E-mail: acree@unt.edu [Department of Chemistry, 1155 Union Circle # 305070, University of North Texas, Denton, TX 76203-5017 (United States); Brumfield, Michela [Department of Chemistry, 1155 Union Circle # 305070, University of North Texas, Denton, TX 76203-5017 (United States); Abraham, Michael H. [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2014-10-20

    Highlights: • Enthalpies of solution measured for 48 solutes dissolved in mesitylene. • Enthalpies of solution measured for 81 solutes dissolved in p-xylene. • Abraham model correlations derived for enthalpies of solvation of solutes in mesitylene. • Abraham model correlations derived for enthalpies of solvation of solutes in p-xylene. • Hydrogen-bonding enthalpies reported for interactions of aromatic hydrocarbons with hydrogen-bond acidic solutes. - Abstract: Enthalpies of solution at infinite dilution of 48 organic solutes in mesitylene and 81 organic solutes in p-xylene were measured using isothermal solution calorimeter. Enthalpies of solvation for 92 organic vapors and gaseous solutes in mesitylene and for 130 gaseous compounds in p-xylene were determined from the experimental and literature data. Abraham model correlations are determined from the experimental enthalpy of solvation data. The derived correlations describe the experimental gas-to-mesitylene and gas-to-p-xylene solvation enthalpies to within average standard deviations of 1.87 kJ mol{sup −1} and 2.08 kJ mol{sup −1}, respectively. Enthalpies of X-H⋯π (X-O, N, and C) hydrogen bond formation of proton donor solutes (alcohols, amines, chlorinated hydrocarbons etc.) with mesitylene and p-xylene were calculated based on the Abraham solvation equation. Obtained values are in good agreement with the results determined using conventional methods.

  16. Resorcinol adsorption from aqueous solution on activated carbon: Relation adsorption isotherm and immersion enthalpy

    International Nuclear Information System (INIS)

    Blanco, Diago A; Giraldo, Liliana; Moreno, Juan C.

    2008-01-01

    The resorcinol adsorption on a modified activated carbon, obtained from an activated commercial carbon Carbochem T M - PS30, CAG, modified by means of chemical treatment with HNO 3 7M oxidized activated carbon (CAO) and heat treatment under H 2 flow, reduced activated carbon (CAR) are studied. The influence of solution pH, the reduction and oxidation of the activated surface carbons in resorcinol aqueous solutions is determined. The interaction solid solution is characterized by adsorption isotherms analysis at 298 K and at pHs of 7.9 and 11 in order to evaluate the system on and below the value of resorcinol pKa. The adsorption capacity of carbons increases with diminishing solution pH. The amount retained increases in the reduced carbon at maximum adsorption pH and diminishes in the oxidized carbon. the experimental results of the adsorption isotherms are adjusted to the Freundlich and Langmuir models, obtaining values for the Q m ax parameter Langmuir model in the CAG of 179, 156 and 44 mgg - 1 For pH values of 7,9 and 11 respectively. In this case of modified carbons values of 233, 179 and 164 mgg - 1 Are obtained for CAR, CAG and CAO to pH 7 respectively, as general tendency the resorcinol adsorption increases in the following order CAR > CAG > CAO. Similar conclusions from immersion enthalpies are obtained, their values increase with the amount of solute retained. In the case of the CAG, immersion enthalpies between 25.8 to 40.9 Jg - 1, are obtained for resorcinol aqueous solutions in a range from 20 to 1500 mgL - 1

  17. Study on the enthalpy of solution and enthalpy of dilution for the ionic liquid [C3mim][Val] (1-propyl-3-methylimidazolium valine)

    International Nuclear Information System (INIS)

    Guan Wei; Li Long; Ma Xiaoxue; Tong Jing; Fang Dawei; Yang Jiazhen

    2012-01-01

    Graphical abstract: The thermodynamic cycle for estimation of the hydration enthalpy of ionic liquid [C 3 mim][Val]. Highlights: ► A new amino acid ionic liquid [C 3 mim][Val] was prepared. ► The molar enthalpies of solution of the ionic liquid. ► The hydration enthalpy of the cation [C 3 mim] + was estimated. ► The molar enthalpies of dilution, of aqueous [C 3 mim][Val] were measured. - Abstract: A new amino acid ionic liquid (AAIL) [C 3 mim][Val] (1-propyl-3-methylimidazolium valine) was prepared by the neutralization method. Using the solution-reaction isoperibol calorimeter, molar solution enthalpies of the ionic liquid [C 3 mim][Val] with known amounts of water and with different concentrations in molality were measured at T = 298.15 K. In terms of standard addition method (SAM) and Archer’s method, the standard molar enthalpy of solution for [C 3 mim][Val] without water, Δ s H m ∘ = (−55.7 ± 0.4) kJ · mol −1 , was obtained. The hydration enthalpy of the cation [C 3 mim] + , ΔH + ([C 3 mim] + ) = −226 kJ · mol −1 , was estimated in terms of Glasser’s theory. Using the RD496-III heat conduction microcalorimeter, the molar enthalpies of dilution, Δ D H m (m i → m f ), of aqueous [C 3 mim][Val] with various values of molality were measured. The values of Δ D H m (m i → m f ) were fitted to Pitzer’s ion-interaction model and the values of apparent relative molar enthalpy, φ L, calculated using Pitzer’s ion-interaction model.

  18. Enthalpy-entropy compensation and the isokinetic temperature in ...

    Indian Academy of Sciences (India)

    Enthalpy-entropy compensation supposes that differences in activation enthalpy delta-H-++ for different reactions (or, typically inbiochemistry, the same reaction catalysed by enzymes obtained from different species) may be compensated for bydifferences in activation entropy delta-S-++. At the isokinetic temperature the ...

  19. Enthalpies of dilution of aqueous Li{sub 2}B{sub 4}O{sub 7} solutions at 298.15K and application of ion-interaction model

    Energy Technology Data Exchange (ETDEWEB)

    Yin Guoyin [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Yao Yan [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008 (China) and Graduate School of Chinese Academy of Sciences, Beijing 100039 (China)]. E-mail: yaoy@isl.ac.cn; Jiao Baojuan [Department of Chemistry, Northwest University, Xi' an 710069 (China); Chen Sanping [Department of Chemistry, Northwest University, Xi' an 710069 (China); Gao Shengli [Department of Chemistry, Northwest University, Xi' an 710069 (China)

    2005-09-15

    The enthalpies of dilution have been measured for aqueous Li{sub 2}B{sub 4}O{sub 7} solutions from 0.0212 to 2.1530molkg{sup -1} at 298.15K. The relative apparent molar enthalpies, L{sub {phi}}, and relative partial molar enthalpies of the solvent and solute, L-bar{sub 1} and L-bar{sub 2} were calculated. The thermodynamic properties of the complex aqueous solutions were represented with a modified Pitzer ion-interaction model.

  20. Enthalpies of vaporization of some acetylene peroxy derivatives of carboranes-12

    International Nuclear Information System (INIS)

    Dibrivnyj, V.N.; Pistun, Z.E.; Van-Chin-Syan, Yu.Ya.; Yuvchenko, A.P.; Zvereva, T.D.

    1999-01-01

    Temperature dependences of saturated vapor pressure and vaporization enthalpies of five acetylene peroxy derivatives of carboranes-12 are determined by the Knudsen effusion method. Enthalpies and melting points of crystals, as well as temperatures of liquid compounds decomposition start are determined by the method of differential scanning calorimetry. Comparison of evaporation enthalpies determined in the study confirms the conclusions on non-additive character of intermolecular interaction in carboranes and their derivatives, which have been made previously [ru

  1. The relation between inversion enthalpy and adsorption parameters for an activated carbon in aqueous Pb2+ solutions

    International Nuclear Information System (INIS)

    Giraldo, Liliana; Moreno, Juan Carlos

    2006-01-01

    We report the preparation of an activated carbon obtained by impregnation of mineral carbon samples with a phosphoric acid solution (50%).The obtained material, exhibits a superficial area of 586 m 2 .g -1 and a total pore volume of 0.37 cm 3 g -1 . With respect to the chemical properties, the activated carbon shows an increased number of acidic sites (0.92 meq g -l ) compared to basic sites (0.63 meq g-1) which yields a material with almost neutral characteristics (PHpzc: 7.4). At a pH: 4.0 the amount of Pb 2 + absorbed and the immersion enthalpy values for the activated carbon reached a maximum with values of 15.7 mg -1 y 27.6 Jg -1 respectively. It was established that similar behaviour occurs for the two properties, absorption and immersion enthalpy, as a function of pH. In addition, a second order function that relates the adsorption constant and immersion enthalpy, and the adsorption constant and pH of the solution are presented

  2. The relation between immersion enthalpy and adsorption parameters for an activated carbon in aqueous Pb2+solutions

    International Nuclear Information System (INIS)

    Girado, Liliana; Moreno, Juan Carlos

    2006-01-01

    We report the preparation of an activated carbon obtained by impregnation of mineral carbon samples with phosphoric acid solution (50%). the obtained material, exhibits a superficial area of 586 m 2 .g -1 and a total pore volume of 0,37 cm 3 g -1 . with respect to the chemical properties, the activated carbon shows an increased number of acidic sites (0,92 meq g -1 ) compared to basic sites (0,63 meq g -1 ) which yields a material with almost neutral characteristics (pH p zc: 7,4). At a pH: 4.0 the amount of pb2+ absorbed and the immersion enthalpy values for the activated carbon reached maxim with values of 15.7 mg -1 y 27,6 Jg -1 respectively. it was established that similar behavior occurs for the two properties, absorption and immersion enthalpy, as a function of pH. in addition, a second order function that relates the adsorption constant and immersion enthalpy, and the adsorption constant and ph of the solution are presented

  3. Enthalpy-entropy compensation: the role of solvation.

    Science.gov (United States)

    Dragan, Anatoliy I; Read, Christopher M; Crane-Robinson, Colyn

    2017-05-01

    Structural modifications to interacting systems frequently lead to changes in both the enthalpy (heat) and entropy of the process that compensate each other, so that the Gibbs free energy is little changed: a major barrier to the development of lead compounds in drug discovery. The conventional explanation for such enthalpy-entropy compensation (EEC) is that tighter contacts lead to a more negative enthalpy but increased molecular constraints, i.e., a compensating conformational entropy reduction. Changes in solvation can also contribute to EEC but this contribution is infrequently discussed. We review long-established and recent cases of EEC and conclude that the large fluctuations in enthalpy and entropy observed are too great to be a result of only conformational changes and must result, to a considerable degree, from variations in the amounts of water immobilized or released on forming complexes. Two systems exhibiting EEC show a correlation between calorimetric entropies and local mobilities, interpreted to mean conformational control of the binding entropy/free energy. However, a substantial contribution from solvation gives the same effect, as a consequence of a structural link between the amount of bound water and the protein flexibility. Only by assuming substantial changes in solvation-an intrinsically compensatory process-can a more complete understanding of EEC be obtained. Faced with such large, and compensating, changes in the enthalpies and entropies of binding, the best approach to engineering elevated affinities must be through the addition of ionic links, as they generate increased entropy without affecting the enthalpy.

  4. Thermodynamic study of rhodamine 123-calf thymus DNA interaction: determination of calorimetric enthalpy by optical melting study.

    Science.gov (United States)

    Masum, Abdulla Al; Chakraborty, Maharudra; Pandya, Prateek; Halder, Umesh Chandra; Islam, Md Maidul; Mukhopadhyay, Subrata

    2014-11-20

    In this paper, the interaction of rhodamine123 (R123) with calf thymus DNA has been studied using molecular modeling and other biophysical methods like UV-vis spectroscopy, fluoremetry, optical melting, isothermal titration calorimetry, and circular dichroic studies. Results showed that the binding energy is about -6 to -8 kcal/mol, and the binding process is favored by both negative enthalpy change and positive entropy change. A new method to determine different thermodynamic properties like calorimetric enthalpy and heat capacity change has been introduced in this paper. The obtained data has been crossed-checked by other methods. After dissecting the free-energy contribution, it was observed that the binding was favored by both negative hydrophobic free energy and negative molecular free energy which compensated for the positive free energies due to the conformational change loss of rotational and transitional freedom of the DNA helix.

  5. High Enthalpy Effects on Two Boundary Layer Disturbances in Supersonic and Hypersonic Flow

    Science.gov (United States)

    Wagnild, Ross Martin

    The fluid flow phenomenon of boundary layer transition is a complicated and difficult process to model and predict. The importance of the state of the boundary layer with regard to vehicle design cannot be understated. The high enthalpy environment in which high speed vehicles operate in further complicates the transition process by adding several more degrees of freedom. In this environment, the internal properties of the gas can stabilize or destabilize the boundary layer as well as modify the disturbances that cause transition. In the current work, the interaction of two types of disturbances with the high enthalpy flow environment are analyzed. The first is known as a second mode disturbance, which is acoustic in nature. The second type is known as a transient growth disturbance and is associated with flows behind roughness elements. Theoretical analyses, linear stability analyses, and computation fluid dynamics (CFD) are used to determine the ways in which these disturbances interact with the high enthalpy environment as well as the consequences of these interactions. First, acoustic wave are directly studied in order to gain a basic understanding of the response of second mode disturbances in the high enthalpy boundary layer. Next, this understanding is used in interpreting the results of several computations attempting to simulate the flow through a high enthalpy flow facility as well as experiments attempting to take advantage of the acoustic interaction with the high enthalpy environment. Because of the difficulty in modeling these experiments, direct simulations of acoustic waves in a hypersonic flow of a gas with molecular vibration are performed. Lastly, compressible transient growth disturbances are simulated using a linear optimal disturbance solver as well as a CFD solver. The effect of an internal molecular process on this type of disturbance is tested through the use of a vibrational mode. It is the goal of the current work to reinforce the

  6. Additive scheme for calculation of solvation enthalpies of heterocyclic aromatic compounds. Sublimation/vaporization enthalpy at 298.15 K

    International Nuclear Information System (INIS)

    Solomonov, Boris N.; Nagrimanov, Ruslan N.; Mukhametzyanov, Timur A.

    2016-01-01

    Highlights: • Additivity scheme for solvation enthalpies estimation of heteroaromatic compounds was proposed. • Method for determination of vaporization/sublimation enthalpies directly at 298.15 K was developed. • Solution enthalpies of 25 heteroaromatic compounds were measured. • Vaporization/sublimation enthalpies of 44 heteroaromatic compounds were determined. • Obtained values are in good agreement with the results of conventional methods. - Abstract: Hereby we propose a method for determination of vaporization and sublimation enthalpies of heterocyclic and carbonyl-containing aromatic compounds at 298.15 K. According to this method vaporization and sublimation enthalpies at 298.15 K are determined based on enthalpies of solvation and solution. Solvation enthalpies of heteroatomatic and carbonyl-containing compounds are calculated using an additive scheme from the solvation enthalpy of closest aromatic hydrocarbon and contributions related to the exchange of CH-groups of hydrocarbon with corresponding substituent atoms or groups. Measured solution enthalpies together with calculated solvation enthalpies allowed to calculate corresponding vaporization and sublimation enthalpies at 298.15 K for a large number of heterocyclic and carbonyl-containing compounds. We have also found that in a number of cases instead of solution enthalpy in benzene at 298.15 K fusion enthalpy at the melting temperature can be used. Comparison between literature data and calculated vaporization and sublimation enthalpies demonstrates satisfactory performance of the proposed method.

  7. Additive scheme for calculation of solvation enthalpies of heterocyclic aromatic compounds. Sublimation/vaporization enthalpy at 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Solomonov, Boris N., E-mail: boris.solomonov@kpfu.ru; Nagrimanov, Ruslan N.; Mukhametzyanov, Timur A.

    2016-06-10

    Highlights: • Additivity scheme for solvation enthalpies estimation of heteroaromatic compounds was proposed. • Method for determination of vaporization/sublimation enthalpies directly at 298.15 K was developed. • Solution enthalpies of 25 heteroaromatic compounds were measured. • Vaporization/sublimation enthalpies of 44 heteroaromatic compounds were determined. • Obtained values are in good agreement with the results of conventional methods. - Abstract: Hereby we propose a method for determination of vaporization and sublimation enthalpies of heterocyclic and carbonyl-containing aromatic compounds at 298.15 K. According to this method vaporization and sublimation enthalpies at 298.15 K are determined based on enthalpies of solvation and solution. Solvation enthalpies of heteroatomatic and carbonyl-containing compounds are calculated using an additive scheme from the solvation enthalpy of closest aromatic hydrocarbon and contributions related to the exchange of CH-groups of hydrocarbon with corresponding substituent atoms or groups. Measured solution enthalpies together with calculated solvation enthalpies allowed to calculate corresponding vaporization and sublimation enthalpies at 298.15 K for a large number of heterocyclic and carbonyl-containing compounds. We have also found that in a number of cases instead of solution enthalpy in benzene at 298.15 K fusion enthalpy at the melting temperature can be used. Comparison between literature data and calculated vaporization and sublimation enthalpies demonstrates satisfactory performance of the proposed method.

  8. Determination of vapor pressures, enthalpies of sublimation, and enthalpies of fusion of benzenetriols

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.; Schick, Christoph

    2004-01-01

    Molar enthalpies of sublimation of 1,2,4-, 1,2,3-, and 1,3,5-tri-hydroxy-benzene, were obtained from the temperature dependence of the vapor pressure measured by the transpiration method. The molar enthalpies of fusion and molar heat capacities of these compounds were measured by DSC. The measured data sets of vaporization, sublimation and fusion enthalpies were checked for internal consistency. Strength of the inter- and intra-molecular hydrogen bonding in di- and tri-hydroxy-benzenes have been assessed

  9. Structure of metal β-diketonates and their enthalpies of vaporization

    International Nuclear Information System (INIS)

    Domrachev, G.A.; Sevast'yanov, V.G.; Zakharov, L.N.; Krasnodubskaya, S.V.; AN SSSR, Moscow. Inst. Obshchej i Neorganicheskoj Khimii)

    1987-01-01

    Using the method of additive schemes in combinaion with the structural estimation of the degree of screening of the central atom and other elements of β-diketonate molecule while analyzing the experimental enthalpies of vaporization, the contributions of separate fragments of complexes into the enthalpy of vaporization are found. It is shown that energies of intermolecular interaction in a condensed phase of monomeric metal β-diketonates with identical substituents do not depend on the central atom type. The enthalpies of dimer dissociation in a series of rare earth dipivaloylmethanates calculated. The proposed approach is advisable fo selecting forms of metal β-diketonates, the most suitable for the purposes of deep purificaion, which are characterized by maximum chemical and physico-chemical selectivity with respect to impurities, chemical inertness to equipment material, container, etc

  10. Enthalpies of Formation of Hydrazine and Its Derivatives.

    Science.gov (United States)

    Dorofeeva, Olga V; Ryzhova, Oxana N; Suchkova, Taisiya A

    2017-07-20

    Enthalpies of formation, Δ f H 298 ° , in both the gas and condensed phase, and enthalpies of sublimation or vaporization have been estimated for hydrazine, NH 2 NH 2 , and its 36 various derivatives using quantum chemical calculations. The composite G4 method has been used along with isodesmic reaction schemes to derive a set of self-consistent high-accuracy gas-phase enthalpies of formation. To estimate the enthalpies of sublimation and vaporization with reasonable accuracy (5-20 kJ/mol), the method of molecular electrostatic potential (MEP) has been used. The value of Δ f H 298 ° (NH 2 NH 2 ,g) = 97.0 ± 3.0 kJ/mol was determined from 75 isogyric reactions involving about 50 reference species; for most of these species, the accurate Δ f H 298 ° (g) values are available in Active Thermochemical Tables (ATcT). The calculated value is in excellent agreement with the reported results of the most accurate models based on coupled cluster theory (97.3 kJ/mol, the average of six calculations). Thus, the difference between the values predicted by high-level theoretical calculations and the experimental value of Δ f H 298 ° (NH 2 NH 2 ,g) = 95.55 ± 0.19 kJ/mol recommended in the ATcT and other comprehensive reference sources is sufficiently large and requires further investigation. Different hydrazine derivatives have been also considered in this work. For some of them, both the enthalpy of formation in the condensed phase and the enthalpy of sublimation or vaporization are available; for other compounds, experimental data for only one of these properties exist. Evidence of accuracy of experimental data for the first group of compounds was provided by the agreement with theoretical Δ f H 298 ° (g) value. The unknown property for the second group of compounds was predicted using the MEP model. This paper presents a systematic comparison of experimentally determined enthalpies of formation and enthalpies of sublimation or vaporization with the results of

  11. Enthalpy-entropy compensation in protein unfolding

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Enthalpy-entropy compensation was found to be a universal law in protein unfolding based on over 3 000 experimental data. Water molecular reorganization accompanying the protein unfolding was suggested as the origin of the enthalpy-entropy compensation in protein unfolding. It is indicated that the enthalpy-entropy compensation constitutes the physical foundation that satisfies the biological need of the small free energy changes in protein unfolding, without the sacrifice of the bio-diversity of proteins. The enthalpy-entropy compensation theory proposed herein also provides valuable insights into the Privalov's puzzle of enthalpy and entropy convergence in protein unfolding.

  12. Dependence of enthalpies of dissolution of β-alanyl-β-alanine on the composition of (water + alcohol) mixtures at 298.15 K

    International Nuclear Information System (INIS)

    Smirnov, Valeriy I.; Badelin, Valentin G.

    2011-01-01

    Highlights: · Enthalpies of dissolution of β-alanyl-β-alanine are measured in aqueous methanol, ethanol, 1-propanol and 2-propanol by calorimetry. · Standard values of dissolution and transfer enthalpies of β-alanyl-β-alanine and enthalpy coefficients of pair-wise interactions are calculated. · Dependences of the thermodynamic characteristics of dissolution of β-alanyl-β-alanine on the composition of (water + alcohol) mixtures are determined. - Abstract: The dissolution enthalpies of β-alanyl-β-alanine in aqueous methanol, ethanol, 1-propanol and 2-propanol solutions with an alcohol content up to 0.4 mole fractions have been measured calorimetrically at T = 298.15 K. The standard enthalpies of dissolution, Δ sol H o and transfer, Δ tr H o , of β-alanyl-β-alanine from water into mixed solvents and the enthalpy coefficients of pair-wise interactions, h xy , of β-alanyl-β-alanine with alcohol solvent molecules have been calculated. The results are discussed in terms of solute-solute and solute-solvent interactions.

  13. Calibration models for high enthalpy calorimetric probes.

    Science.gov (United States)

    Kannel, A

    1978-07-01

    The accuracy of gas-aspirated liquid-cooled calorimetric probes used for measuring the enthalpy of high-temperature gas streams is studied. The error in the differential temperature measurements caused by internal and external heat transfer interactions is considered and quantified by mathematical models. The analysis suggests calibration methods for the evaluation of dimensionless heat transfer parameters in the models, which then can give a more accurate value for the enthalpy of the sample. Calibration models for four types of calorimeters are applied to results from the literature and from our own experiments: a circular slit calorimeter developed by the author, single-cooling jacket probe, double-cooling jacket probe, and split-flow cooling jacket probe. The results show that the models are useful for describing and correcting the temperature measurements.

  14. The enthalpy of sublimation of cubane

    International Nuclear Information System (INIS)

    Bashir-Hashemi, A.; Chickos, James S.; Hanshaw, William; Zhao Hui; Farivar, Behzad S.; Liebman, Joel F.

    2004-01-01

    The sublimation enthalpy of cubane, a key reference material for force field and quantum mechanical computations, was measured by combining the vaporization enthalpy at T = 298.15 K to the sum of the fusion enthalpy measured at T = 405 K and a solid-solid phase transition that occurs at T 394 K. The fusion and solid-solid phase transitions were measured previously. A sublimation enthalpy value of (55.2 ± 2.0) kJ mol -1 at T = 298.15 K was obtained. This value compares quite favorably the value obtained by comparing the sublimation enthalpy of similar substances as a function of their molar masses but is at odds with earlier measurements

  15. The enthalpy of sublimation of cubane

    Energy Technology Data Exchange (ETDEWEB)

    Bashir-Hashemi, A.; Chickos, James S.; Hanshaw, William; Zhao Hui; Farivar, Behzad S.; Liebman, Joel F

    2004-12-15

    The sublimation enthalpy of cubane, a key reference material for force field and quantum mechanical computations, was measured by combining the vaporization enthalpy at T = 298.15 K to the sum of the fusion enthalpy measured at T = 405 K and a solid-solid phase transition that occurs at T 394 K. The fusion and solid-solid phase transitions were measured previously. A sublimation enthalpy value of (55.2 {+-} 2.0) kJ mol{sup -1} at T = 298.15 K was obtained. This value compares quite favorably the value obtained by comparing the sublimation enthalpy of similar substances as a function of their molar masses but is at odds with earlier measurements.

  16. Enthalpies of solution of ampicillin, amoxycillin and their binary mixtures at 310.15 K.

    Science.gov (United States)

    Jain, D V; Kashid, N; Kapoor, S; Chadha, R

    2000-05-15

    Enthalpies of solutions of ampicillin, amoxycillin and their binary mixtures have been determined at pH 2, 5, and 7 using C-80 calorimeter. The systems showed endothermic behaviour; molar enthalpies of solutions of ampicillin were determined to be 13.32, 15.89 and 23.21 kJ mol(-1) and amoxycillin were 16.32, 18.45 and 26. 25 kJ mol(-1) at pH 2, 5, and 7, respectively. The excess molar enthalpies of solution have also been calculated to find any interaction between these two drugs.

  17. Enthalpies of sublimation of fullerenes by thermogravimetry

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Herrera, Melchor; Campos, Myriam; Torres, Luis Alfonso; Rojas, Aarón, E-mail: arojas@cinvestav.mx

    2015-12-20

    Graphical abstract: - Highlights: • Enthalpies of sublimation of fullerenes were measured by thermogravimetry. • Results of enthalpies of sublimation are comparable with data reported in literature. • Not previously reported enthalpy of sublimation of C{sub 78} is supplied in this work. • Enthalpies of sublimation show a strong dependence with the number of carbon atoms in the cluster. • Enthalpies of sublimation are congruent with dispersion forces ruling cohesion of solid fullerene. - Abstract: The enthalpies of sublimation of fullerenes, as measured in the interval of 810–1170 K by thermogravimetry and applying the Langmuir equation, are reported. The detailed experimental procedure and its application to fullerenes C{sub 60}, C{sub 70}, C{sub 76}, C{sub 78} and C{sub 84} are supplied. The accuracy and uncertainty associated with the experimental results of the enthalpy of sublimation of these fullerenes show that the reliability of the measurements is comparable to that of other indirect high-temperature methods. The results also indicate that the enthalpy of sublimation increases proportionally to the number of carbon atoms in the cluster but there is also a strong correlation between the enthalpy of sublimation and the polarizability of each fullerene.

  18. A combined experimental and computational investigation of excess molar enthalpies of (nitrobenzene + alkanol) mixtures

    International Nuclear Information System (INIS)

    Neyband, Razieh Sadat; Zarei, Hosseinali

    2015-01-01

    Highlights: • Excess molar enthalpies for the binary mixtures of nitrobenzene + alkanols mixtures were measured. • The infinite dilution excess partial molar enthalpies were calculated using the ab initio methods. • The PCM calculations were performed. • The computed excess partial molar enthalpies at infinite dilution were compared to experimental results. - Abstract: Excess molar enthalpies (H m E ) for the binary mixtures of {(nitrobenzene + ethanol), 1-propanol, 2-propanol, 1-butanol and 2-butanol} have been measured over the entire composition range at ambient pressure (81.5 kPa) and temperature 298 K using a Parr 1455 solution calorimeter. From the experimental results, the excess partial molar enthalpies (H i E ) and excess partial molar enthalpies at infinite dilution (H i E,∞ ) were calculated. The excess molar enthalpies (H m E ) are positive for all {nitrobenzene (1) + alkanol (2)} mixtures over the entire composition range. A state-of-the-art computational strategy for the evaluation of excess partial molar enthalpies at infinite dilution was followed at the M05-2X/6-311++G ∗∗ level of theory with the PCM model. The experimental excess partial molar enthalpies at infinite dilution have been compared to the computational data of the ab initio in liquid phase. Integrated experimental and computational results help to clarify the nature of the intermolecular interactions in {nitrobenzene (1) + alkanol (2)} mixtures. The experimental and computational work which was done in this study complements and extends the general research on the computation of excess partial molar enthalpy at infinite dilution of binary mixtures

  19. Enthalpy of Formation of N2H4 (Hydrazine) Revisited.

    Science.gov (United States)

    Feller, David; Bross, David H; Ruscic, Branko

    2017-08-17

    In order to address the accuracy of the long-standing experimental enthalpy of formation of gas-phase hydrazine, fully confirmed in earlier versions of Active Thermochemical Tables (ATcT), the provenance of that value is re-examined in light of new high-end calculations of the Feller-Peterson-Dixon (FPD) variety. An overly optimistic determination of the vaporization enthalpy of hydrazine, which created an unrealistically strong connection between the gas phase thermochemistry and the calorimetric results defining the thermochemistry of liquid hydrazine, was identified as the probable culprit. The new enthalpy of formation of gas-phase hydrazine, based on balancing all available knowledge, was determined to be 111.57 ± 0.47 kJ/mol at 0 K (97.42 ± 0.47 kJ/mol at 298.15 K). Close agreement was found between the ATcT (even excluding the latest theoretical result) and the FPD enthalpy.

  20. Characterization of Adsorption Enthalpy of Novel Water-Stable Zeolites and Metal-Organic Frameworks

    Science.gov (United States)

    Kim, Hyunho; Cho, H. Jeremy; Narayanan, Shankar; Yang, Sungwoo; Furukawa, Hiroyasu; Schiffres, Scott; Li, Xiansen; Zhang, Yue-Biao; Jiang, Juncong; Yaghi, Omar M.; Wang, Evelyn N.

    2016-01-01

    Water adsorption is becoming increasingly important for many applications including thermal energy storage, desalination, and water harvesting. To develop such applications, it is essential to understand both adsorbent-adsorbate and adsorbate-adsorbate interactions, and also the energy required for adsorption/desorption processes of porous material-adsorbate systems, such as zeolites and metal-organic frameworks (MOFs). In this study, we present a technique to characterize the enthalpy of adsorption/desorption of zeolites and MOF-801 with water as an adsorbate by conducting desorption experiments with conventional differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). With this method, the enthalpies of adsorption of previously uncharacterized adsorbents were estimated as a function of both uptake and temperature. Our characterizations indicate that the adsorption enthalpies of type I zeolites can increase to greater than twice the latent heat whereas adsorption enthalpies of MOF-801 are nearly constant for a wide range of vapor uptakes.

  1. Enthalpies of solution of methylcalix[4]resorcinarene in non-aqueous solvents as a function of concentration and temperature

    International Nuclear Information System (INIS)

    Riveros, Diana C.; Martínez, Fleming; Vargas, Edgar F.

    2012-01-01

    Highlights: ► The solution enthalpies of methylcalix[4]resorcinarene in alcohols have been measured. ► The solution enthalpies of methylcalix[4]resorcinarene in alcohols are endothermic. ► Enthalpies of transference are interpreted in terms of proton donor capacity of alcohols. - Abstract: Enthalpies of solution of 2,8,14,20-tetramethyl-4,6,10,12,16,18,22,24-octahydroxyresorci[4]arene in methanol, ethanol and propanol as a function of molal concentration at (288.15, 298.15 and 308.15) K were measured calorimetrically. The enthalpies of solvation were estimated. Using propanol as the referent solvent, transfer properties to other alcohols were also calculated. In addition, temperature dependence of the enthalpy of solution at infinite dilution was also obtained. The data were interpreted in terms of solute–solvent interactions.

  2. Status on high enthalpy geothermal resources in Greece

    International Nuclear Information System (INIS)

    Koutinas, G.A.

    1990-01-01

    Greece is privileged to have many high and medium enthalpy geothermal resources. Related activities during the last 5 years were conducted mainly on the previously discovered geothermal fields of Milos, Nisyros and Lesvos islands, without any deep geothermal drilling. Most efforts were focused on the demonstration of a high enthalpy geothermal reservoir on Milos, by generating electricity from high salinity fluid, with a 2 MW pilot plant. Significant experience has been gained there, by solving technical problems, but still site specific constraints have to be overcome in order to arrive at a comprehensive feasibility study, leading to the development phase. A pre-feasibility study has been carried out in the Nisyros geothermal field. Moreover, a detailed geoscientific exploration program has been completed on Lesvos island, where very promising geothermal areas have been identified. In this paper, reference is made to the most important data concerning high enthalpy geothermal resources by emphasizing the Milos geothermal field

  3. Anomalous enthalpy relaxation in vitreous silica

    DEFF Research Database (Denmark)

    Yue, Yuanzheng

    2015-01-01

    scans. It is known that the liquid fragility (i.e., the speed of the viscous slow-down of a supercooled liquid at its Tg during cooling) has impact on enthalpy relaxation in glass. Here, we find that vitreous silica (as a strong system) exhibits striking anomalies in both glass transition and enthalpy...... relaxation compared to fragile oxide systems. The anomalous enthalpy relaxation of vitreous silica is discovered by performing the hyperquenching-annealing-calorimetry experiments. We argue that the strong systems like vitreous silica and vitreous Germania relax in a structurally cooperative manner, whereas...... the fragile ones do in a structurally independent fashion. We discuss the origin of the anomalous enthalpy relaxation in the HQ vitreous silica....

  4. Characterization of Adsorption Enthalpy of Novel Water-Stable Zeolites and Metal-Organic Frameworks

    Science.gov (United States)

    Kim, Hyunho; Cho, H. Jeremy; Narayanan, Shankar; Yang, Sungwoo; Furukawa, Hiroyasu; Schiffres, Scott; Li, Xiansen; Zhang, Yue-Biao; Jiang, Juncong; Yaghi, Omar M.; Wang, Evelyn N.

    2016-01-01

    Water adsorption is becoming increasingly important for many applications including thermal energy storage, desalination, and water harvesting. To develop such applications, it is essential to understand both adsorbent-adsorbate and adsorbate-adsorbate interactions, and also the energy required for adsorption/desorption processes of porous material-adsorbate systems, such as zeolites and metal-organic frameworks (MOFs). In this study, we present a technique to characterize the enthalpy of adsorption/desorption of zeolites and MOF-801 with water as an adsorbate by conducting desorption experiments with conventional differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). With this method, the enthalpies of adsorption of previously uncharacterized adsorbents were estimated as a function of both uptake and temperature. Our characterizations indicate that the adsorption enthalpies of type I zeolites can increase to greater than twice the latent heat whereas adsorption enthalpies of MOF-801 are nearly constant for a wide range of vapor uptakes. PMID:26796523

  5. Enthalpy of mixing of liquid Ag–Bi–Cu alloys at 1073 K

    International Nuclear Information System (INIS)

    Fima, Przemysław; Flandorfer, Hans

    2014-01-01

    Highlights: • Partial and integral mixing enthalpies of liquid Ag–Bi–Cu alloys were determined. • Integral mixing enthalpies are small and endothermic, similar to limiting binaries. • The ternary data were fitted on the basis of Redlich–Kister–Muggianu model. - Abstract: The Ag–Bi–Cu system is among those ternary systems which have not been fully studied yet, in particular the thermodynamic description of the liquid phase is missing. Partial and integral enthalpies of mixing of liquid ternary Ag–Bi–Cu alloys were determined over a broad composition range along six sections: x(Ag)/x(Bi) = 0.25, 1, 4; x(Ag)/x(Cu) = 1.5; x(Bi)/x(Cu) = 1.86, 4. Measurements were carried out at 1073 K using two Calvet type microcalorimeters and drop calorimetric technique. It was found that integral enthalpies of mixing are small and endothermic, similarly to limiting binary alloys. The ternary data were fitted on the basis of an extended Redlich–Kister–Muggianu model for substitutional solutions. There are no significant additional ternary interactions

  6. The Activity and Enthalpy of Vaporization of Nicotine from Tobacco at Moderate Temperatures

    Directory of Open Access Journals (Sweden)

    St.Charles F. Kelley

    2016-01-01

    Full Text Available The vapor pressure of nicotine has been reported for unprotonated nicotine and for nicotine-water solutions. Yet no published values exist for nicotine in any commercially relevant matrix or for protonated forms (e.g., tobacco, smoke, electronic cigarette solutions, nicotine replacement products, nicotine salts. Therefore a methodology was developed to measure nicotine activity (defined as the vapor pressure from a matrix divided by the vapor pressure of pure nicotine. The headspace concentration of nicotine was measured for pure nicotine and tobacco stored at 23, 30, and 40 °C which allowed for conversion to vapor pressure and nicotine activity and for the estimation of enthalpy of vaporization. Burley, Flue-cured, Oriental, and cigarette blends were tested. Experiments were conducted with pure nicotine initially until the storage and sampling techniques were validated by comparison with previously published values. We found that the nicotine activity from tobacco was less than 1% with Burley > Flue-cured > Oriental. At 23 °C the nicotine vapor pressure averaged by tobacco type was 0.45 mPa for Oriental tobacco, 1.8 mPa for Flue-cured, 13 mPa for Burley while pure nicotine was 2.95 Pa. In general, the nicotine activity increased as the (calculated unprotonated nicotine concentration increased. The nicotine enthalpy of vaporization from tobacco ranged from 77 kJ/mol to 92 kJ/mol with no obvious trends with regard to tobacco origin, type, stalk position or even the wide range of nicotine activity. The mean value for all tobacco types was 86.7 kJ/mol with a relative standard deviation of 6.5% indicating that this was an intrinsic property of the nicotine form in tobacco rather than the specific tobacco properties. This value was about 30 kJ/mol greater than that of pure nicotine and is similar to the energy needed to remove a proton from monoprotonated nicotine.

  7. Enthalpies of solution of methylcalix[4]resorcinarene in non-aqueous solvents as a function of concentration and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Riveros, Diana C. [Laboratorio de Termodinamica de Soluciones, Departamento de Quimica, Facultad de Ciencias, Universidad de los Andes, Bogota D.C. (Colombia); Martinez, Fleming [Grupo de Investigaciones Farmaceutico-Fisicoquimicas, Departamento de Farmacia, Facultad de Ciencias, Universidad Nacional de Colombia, Bogota D.C. (Colombia); Vargas, Edgar F., E-mail: edvargas@uniandes.edu.co [Laboratorio de Termodinamica de Soluciones, Departamento de Quimica, Facultad de Ciencias, Universidad de los Andes, Bogota D.C. (Colombia)

    2012-11-20

    Highlights: Black-Right-Pointing-Pointer The solution enthalpies of methylcalix[4]resorcinarene in alcohols have been measured. Black-Right-Pointing-Pointer The solution enthalpies of methylcalix[4]resorcinarene in alcohols are endothermic. Black-Right-Pointing-Pointer Enthalpies of transference are interpreted in terms of proton donor capacity of alcohols. - Abstract: Enthalpies of solution of 2,8,14,20-tetramethyl-4,6,10,12,16,18,22,24-octahydroxyresorci[4]arene in methanol, ethanol and propanol as a function of molal concentration at (288.15, 298.15 and 308.15) K were measured calorimetrically. The enthalpies of solvation were estimated. Using propanol as the referent solvent, transfer properties to other alcohols were also calculated. In addition, temperature dependence of the enthalpy of solution at infinite dilution was also obtained. The data were interpreted in terms of solute-solvent interactions.

  8. The enthalpies of formation of two dibenzocyclooctadienones

    Energy Technology Data Exchange (ETDEWEB)

    Perisanu, St.; Contineanu, Iulia; Banciu, M.D.; Liebman, Joel F.; Farivar, Behzad S.; Mullan, Melissa A.; Chickos, James S.; Rath, Nigam; Hillesheim, Dorothea M

    2003-04-17

    The standard molar enthalpies of formation ({delta}{sub f}H{sub m}{sup 0}(s)/kJ mol{sup -1}) for 2,3:6,7-dibenzocycloocta-2,6-dien-1-one and 2,3:7,8-dibenzocycloocta-2,7-dien-1-one [6H-11,12-dihydro-dibenzo[a,e]cycloocten-5-one (ketone 1) and 10H-11,12-dihydrodibenzo[a,d]-cycloocten-5-one (ketone 2), respectively] were derived from enthalpies of combustion, measured by means of a microbomb calorimeter. The fusion and vaporization enthalpies of these compounds were obtained from DSC and correlation gas chromatography measurements. The standard molar enthalpies of formation in the gas phase were calculated by combining the condensed phase standard molar enthalpies of formation with the fusion and vaporization enthalpies adjusted to 298.15 K. Values for {delta}{sub f}H{sub m}{sup 0}(g) of (-39.9{+-}5.5) and (-14.8{+-}5.3) kJ mol{sup -1} were obtained for 2,3:6,7-dibenzocycloocta-2,6-dien-1-one and 2,3:7,8-dibenzocycloocta-2,7-dien-1-one, respectively. Quantum chemical calculations are reported for the compounds investigated experimentally and an additional four isomers. Isomerization enthalpies are derived from computed energies. The enthalpies of formation are also calculated by group additivity, compared with the experimental values and then correlated with the structure of the molecules investigated. The X-ray analysis of ketone 1 is also reported.

  9. The enthalpies of formation of two dibenzocyclooctadienones

    International Nuclear Information System (INIS)

    Perisanu, St.; Contineanu, Iulia; Banciu, M.D.; Liebman, Joel F.; Farivar, Behzad S.; Mullan, Melissa A.; Chickos, James S.; Rath, Nigam; Hillesheim, Dorothea M.

    2003-01-01

    The standard molar enthalpies of formation (Δ f H m 0 (s)/kJ mol -1 ) for 2,3:6,7-dibenzocycloocta-2,6-dien-1-one and 2,3:7,8-dibenzocycloocta-2,7-dien-1-one [6H-11,12-dihydro-dibenzo[a,e]cycloocten-5-one (ketone 1) and 10H-11,12-dihydrodibenzo[a,d]-cycloocten-5-one (ketone 2), respectively] were derived from enthalpies of combustion, measured by means of a microbomb calorimeter. The fusion and vaporization enthalpies of these compounds were obtained from DSC and correlation gas chromatography measurements. The standard molar enthalpies of formation in the gas phase were calculated by combining the condensed phase standard molar enthalpies of formation with the fusion and vaporization enthalpies adjusted to 298.15 K. Values for Δ f H m 0 (g) of (-39.9±5.5) and (-14.8±5.3) kJ mol -1 were obtained for 2,3:6,7-dibenzocycloocta-2,6-dien-1-one and 2,3:7,8-dibenzocycloocta-2,7-dien-1-one, respectively. Quantum chemical calculations are reported for the compounds investigated experimentally and an additional four isomers. Isomerization enthalpies are derived from computed energies. The enthalpies of formation are also calculated by group additivity, compared with the experimental values and then correlated with the structure of the molecules investigated. The X-ray analysis of ketone 1 is also reported

  10. The CPA Equation of State and an Activity Coefficient Model for Accurate Molar Enthalpy Calculations of Mixtures with Carbon Dioxide and Water/Brine

    Energy Technology Data Exchange (ETDEWEB)

    Myint, P. C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hao, Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Firoozabadi, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-03-27

    Thermodynamic property calculations of mixtures containing carbon dioxide (CO2) and water, including brines, are essential in theoretical models of many natural and industrial processes. The properties of greatest practical interest are density, solubility, and enthalpy. Many models for density and solubility calculations have been presented in the literature, but there exists only one study, by Spycher and Pruess, that has compared theoretical molar enthalpy predictions with experimental data [1]. In this report, we recommend two different models for enthalpy calculations: the CPA equation of state by Li and Firoozabadi [2], and the CO2 activity coefficient model by Duan and Sun [3]. We show that the CPA equation of state, which has been demonstrated to provide good agreement with density and solubility data, also accurately calculates molar enthalpies of pure CO2, pure water, and both CO2-rich and aqueous (H2O-rich) mixtures of the two species. It is applicable to a wider range of conditions than the Spycher and Pruess model. In aqueous sodium chloride (NaCl) mixtures, we show that Duan and Sun’s model yields accurate results for the partial molar enthalpy of CO2. It can be combined with another model for the brine enthalpy to calculate the molar enthalpy of H2O-CO2-NaCl mixtures. We conclude by explaining how the CPA equation of state may be modified to further improve agreement with experiments. This generalized CPA is the basis of our future work on this topic.

  11. A study of the vaporization enthalpies of some 1-substituted imidazoles and pyrazoles by correlation-gas chromatography.

    Science.gov (United States)

    Lipkind, Dmitry; Plienrasri, Chatchawat; Chickos, James S

    2010-12-23

    The vaporization enthalpies of 1-methyl-, 1-ethyl-, 1-phenyl-, and 1-benzylimidazole, 1-methyl- and 1-phenylpyrazole, and trans-azobenzene are evaluated by correlation-gas chromatography (C-GC) using a variety of azines and diazines as standards. The vaporization enthalpies obtained by C-GC when compared to literature values are approximately 14 kJ·mol(-1) smaller for the imidazoles and 6 kJ·mol(-1) smaller for the pyrazoles. The literature vaporization enthalpies of 1-methylpyrrole and 1-methylindole, two closely related compounds with one less nitrogen, are reproduced by C-GC. These results suggest that the magnitude of the intermolecular interactions present in 1-substituted imidazoles and pyrazoles are significantly larger than the those present in the reference compounds and greater than or equal in magnitude to the enhanced intermolecular interactions observed previously in aromatic 1,2-diazines. The vaporization enthalpy and vapor pressure of a trans-1,2-diazine, trans-azobenzene, measured by C-GC using similar standards reproduced the literature values within experimental error.

  12. Enthalpies of a binary alloy during solidification

    Science.gov (United States)

    Poirier, D. R.; Nandapurkar, P.

    1988-01-01

    The purpose of the paper is to present a method of calculating the enthalpy of a dendritic alloy during solidification. The enthalpies of the dendritic solid and interdendritic liquid of alloys of the Pb-Sn system are evaluated, but the method could be applied to other binaries, as well. The enthalpies are consistent with a recent evaluation of the thermodynamics of Pb-Sn alloys and with the redistribution of solute in the same during dendritic solidification. Because of the heat of mixing in Pb-Sn alloys, the interdendritic liquid of hypoeutectic alloys (Pb-rich) of less than 50 wt pct Sn has enthalpies that increase as temperature decreases during solidification.

  13. Standard molar enthalpy of formation of methoxyacetophenone isomers

    International Nuclear Information System (INIS)

    Amaral, Luísa M.P.F.; Morais, Victor M.F.; Ribeiro da Silva, Manuel A.V.

    2014-01-01

    Highlights: • Experimental and computational energetic study of methoxyacetophenone isomers. • Enthalpies of formation and phase transition determined by calorimetric techniques. • Quantum chemical calculations allowed estimation of enthalpies of formation. • Structure and energy correlations were established. - Abstract: Values of the standard (p o = 0.1 MPa) molar enthalpy of formation of 2′-, 3′- and 4′-methoxyacetophenones were derived from their standard molar energy of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The Calvet high temperature vacuum sublimation technique was used to measure the enthalpies of sublimation/vaporization of the compounds studied. The standard molar enthalpies of formation of the three compounds, in the gaseous phase, at T = 298.15 K, have been derived from the corresponding standard molar enthalpies of formation in the condensed phase and the standard molar enthalpies for the phase transition. The results obtained are −(232.0 ± 2.5), −(237.7 ± 2.7) and −(241.1 ± 2.1) kJ · mol −1 for 2′-, 3′- and 4′-methoxyacetophenone, respectively. Standard molar enthalpies of formation were also estimated from different methodologies: the Cox scheme as well as two different computational approaches using density functional theory-based B3LYP and the multilevel G3 methodologies

  14. High enthalpy gas dynamics

    CERN Document Server

    Rathakrishnan, Ethirajan

    2014-01-01

    This is an introductory level textbook which explains the elements of high temperature and high-speed gas dynamics. written in a clear and easy to follow style, the author covers all the latest developments in the field including basic thermodynamic principles, compressible flow regimes and waves propagation in one volume covers theoretical modeling of High Enthalpy Flows, with particular focus on problems in internal and external gas-dynamic flows, of interest in the fields of rockets propulsion and hypersonic aerodynamics High enthalpy gas dynamics is a compulsory course for aerospace engine

  15. Enthalpy of mixing of liquid Co–Sn alloys

    International Nuclear Information System (INIS)

    Yakymovych, A.; Fürtauer, S.; Elmahfoudi, A.; Ipser, H.; Flandorfer, H.

    2014-01-01

    Highlights: • The enthalpies of mixing of liquid Co–Sn alloys between T = (673 and 1773) K. • The temperature dependence of the enthalpies of mixing was described. • Full report of measured values including polynomial coefficients. - Abstract: A literature overview of enthalpy of mixing data for liquid Co–Sn alloys shows large scattering but no clear temperature dependence. Therefore drop calorimetry was performed in the Co–Sn system at twelve different temperatures in 100 K steps in the temperature range (673 to 1773) K. The integral enthalpy of mixing was determined starting from 1173 K and fitted to a standard Redlich–Kister polynomial. In addition, the limiting partial molar enthalpy of Co in Sn was investigated by small additions of Co to liquid Sn at temperatures (673 to 1773) K. The integral and partial molar enthalpies of the Co–Sn system generally show an exothermic mixing behavior. Significant temperature dependence was detected for the enthalpies of mixing. The minimum integral enthalpy values vary with rising temperature from approx. −7820 J/mol at T = 1173 K to −1350 J/mol at T = 1773 K; the position of the minimum is between (59 and 61) at.% Co. The results are discussed and compared with literature data available for this system. X-ray studies and scanning electron microscopy of selected alloys obtained from the calorimetric measurements were carried out in order to check the completeness of the solution process

  16. Enthalpy of dilution and volumetric properties of N-glycylglycine in aqueous xylitol solutions at T = 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Liu Min, E-mail: panpanliumin@163.co [College of Chemistry and Chemical Engineering, Liao Cheng University, Liaocheng, Shandong 252059 (China); Wang Lili; Li Guangqian; Dong Lina; Sun Dezhi [College of Chemistry and Chemical Engineering, Liao Cheng University, Liaocheng, Shandong 252059 (China); Zhu Lanying [College of Life Science and Bioengineering, Liao Cheng University, Liaocheng, Shandong 252059 (China); Di Youying [College of Chemistry and Chemical Engineering, Liao Cheng University, Liaocheng, Shandong 252059 (China)

    2011-06-15

    Highlights: Enthalpies of dilution of N-glycylglycine in aqueous xylitol solutions were determined at 298.15 K. The homogeneous enthalpic interaction coefficients were calculated. Apparent molar volumes of the ternary systems were calculated from the data of densities. Limiting partial molar volumes and limiting partial molar volumes of transfer were deduced. - Abstract: The enthalpy of dilution of N-glycylglycine ({Delta}{sub dil}H{sub m}) in aqueous xylitol solutions has been determined by means of flow-mix isothermal microcalorimetry at the temperature of 298.15 K. The homogeneous enthalpic interaction coefficients (h{sub 2}, h{sub 3}, and h{sub 4}) which characterize the interactions of examined N-glycylglycine in aqueous xylitol solutions have been calculated according to the excess enthalpy concept based on the values of dilution enthalpy. It has been found that the enthalpic pair interaction coefficients (h{sub 2}) in the systems investigated are negative and become less negative as the molality of xylitol increases. Values of the density ({rho}) of the ternary homogeneous systems were also measured with a quartz vibrating-tube densimeter at the temperature of 298.15 K. The values of the apparent molar volume (V{sub {phi}}) of the ternary systems were calculated from the data of density, which have been used to deduce limiting partial molar volumes of N-glycylglycine (V{sub {phi}}{sup o}) and limiting partial molar volumes of transfer ({Delta}{sub trs}V{sub {phi}}{sup o}) from water to aqueous xylitol solutions at different concentrations. The results have been discussed based on solute-solute interactions and solvation effects.

  17. Enthalpy of dilution and volumetric properties of N-glycylglycine in aqueous xylitol solutions at T = 298.15 K

    International Nuclear Information System (INIS)

    Liu Min; Wang Lili; Li Guangqian; Dong Lina; Sun Dezhi; Zhu Lanying; Di Youying

    2011-01-01

    Highlights: → Enthalpies of dilution of N-glycylglycine in aqueous xylitol solutions were determined at 298.15 K. → The homogeneous enthalpic interaction coefficients were calculated. → Apparent molar volumes of the ternary systems were calculated from the data of densities. → Limiting partial molar volumes and limiting partial molar volumes of transfer were deduced. - Abstract: The enthalpy of dilution of N-glycylglycine (Δ dil H m ) in aqueous xylitol solutions has been determined by means of flow-mix isothermal microcalorimetry at the temperature of 298.15 K. The homogeneous enthalpic interaction coefficients (h 2 , h 3 , and h 4 ) which characterize the interactions of examined N-glycylglycine in aqueous xylitol solutions have been calculated according to the excess enthalpy concept based on the values of dilution enthalpy. It has been found that the enthalpic pair interaction coefficients (h 2 ) in the systems investigated are negative and become less negative as the molality of xylitol increases. Values of the density (ρ) of the ternary homogeneous systems were also measured with a quartz vibrating-tube densimeter at the temperature of 298.15 K. The values of the apparent molar volume (V φ ) of the ternary systems were calculated from the data of density, which have been used to deduce limiting partial molar volumes of N-glycylglycine (V φ o ) and limiting partial molar volumes of transfer (Δ trs V φ o ) from water to aqueous xylitol solutions at different concentrations. The results have been discussed based on solute-solute interactions and solvation effects.

  18. Formation enthalpy of alkali-borosilicate glass

    International Nuclear Information System (INIS)

    Borisova, N.V.; Ushakov, V.M.

    1991-01-01

    Temperature dependence of formation enthalpy of glass of the composition 0.0438Na 2 O-0.0385K 2 O-0.3394B 2 O 3 -0.5783SiO 2 was determined using the method of high-temperature colorimetry-dissolution, mixing and differential scanning calorimetry. The glass considered has liquation nature-two-vitrification ranges at 713 K and 817 K are detected. The brightening point is 922 K. The calculation of formation enthalpy using the method of partial heat capacities is made in the temperature range of 973-1473 K. Formation enthalpy does not depend on temperature in the temperature range of 298-1273 K

  19. Thermochemistry of methoxythiophenes: Measurement of their enthalpies of vaporization and estimation of their enthalpies of formation in the condensed phase

    International Nuclear Information System (INIS)

    Temprado, Manuel; Notario, Rafael; Roux, María Victoria; Verevkin, Sergey P.

    2014-01-01

    Highlights: • The enthalpies of vaporization of 2- and 3-methoxythiophenes have been measured by the transpiration method. • We have estimated the enthalpies of formation of methoxythiophenes in liquid phase. • The optimized geometries of methoxythiophenes have been tabulated and compared with the experimental crystal structures. - Abstract: Enthalpies of vaporization of 2- and 3-methoxythiophenes (48.32 ± 0.30 and 48.54 ± 0.22 kJ · mol −1 , respectively) have been measured by the transpiration method using nitrogen as the carrying and protecting stream. Combustion experiments leading to enthalpies of formation in the liquid phase, Δ f H 0 m (l), for both isomers failed due to rapid darkening of freshly distilled samples even under a protecting atmosphere. However, combination of experimental vaporization enthalpies with values of the gaseous enthalpies of formation, Δ f H 0 m (g), obtained by quantum-chemical calculations from our previous work Notario et al. (2012) [24] permits establishing estimated Δ f H 0 m (l) values of −(68.3 ± 4.2) and −(80.1 ± 4.2) kJ · mol −1 , for 2- and 3-methoxythiophene, respectively

  20. Calculating the enthalpy of vaporization for ionic liquid clusters.

    Science.gov (United States)

    Kelkar, Manish S; Maginn, Edward J

    2007-08-16

    Classical atomistic simulations are used to compute the enthalpy of vaporization of a series of ionic liquids composed of 1-alkyl-3-methylimidazolium cations paired with the bis(trifluoromethylsulfonyl)imide anion. The calculations show that the enthalpy of vaporization is lowest for neutral ion pairs. The enthalpy of vaporization increases by about 40 kJ/mol with the addition of each ion pair to the vaporizing cluster. Non-neutral clusters have much higher vaporization enthalpies than their neutral counterparts and thus are not expected to make up a significant fraction of volatile species. The enthalpy of vaporization increases slightly as the cation alkyl chain length increases and as temperature decreases. The calculated vaporization enthalpies are consistent with two sets of recent experimental measurements as well as with previous atomistic simulations.

  1. A DFT study on the enthalpies of thermite reactions and enthalpies of formation of metal composite oxide

    Science.gov (United States)

    Zhang, Yu-ying; Wang, Meng-jie; Chang, Chun-ran; Xu, Kang-zhen; Ma, Hai-xia; Zhao, Feng-qi

    2018-05-01

    The standard thermite reaction enthalpies (ΔrHmθ) for seven metal oxides were theoretically analyzed using density functional theory (DFT) under five different functional levels, and the results were compared with experimental values. Through the comparison of the linear fitting constants, mean error and root mean square error, the Perdew-Wang functional within the framework of local density approximation (LDA-PWC) and Perdew-Burke-Ernzerhof exchange-correlation functional within the framework of generalized gradient approximation (GGA-PBE) were selected to further calculate the thermite reaction enthalpies for metal composite oxides (MCOs). According to the Kirchhoff formula, the standard molar reaction enthalpies for these MCOs were obtained and their standard molar enthalpies of formation (ΔfHmθ) were finally calculated. The results indicated that GGA-PBE is the most suitable one out of the total five methods to calculate these oxides. Tungstate crystals present the maximum deviation of the enthalpies of thermite reactions for MCOs and these of their physical metal oxide mixtures, but ferrite crystals are the minimum. The correlation coefficients are all above 0.95, meaning linear fitting results are very precise. And the molar enthalpies of formation for NiMoO4, CuMoO4, PbZrO3 (Pm/3m), PbZrO3 (PBA2), PbZrO3 (PBam), MgZrO3, CdZrO3, MnZrO3, CuWO4 and Fe2WO6 were first obtained as -1078.75, -1058.45, -1343.87, -1266.54, -1342.29, -1333.03, -1210.43, -1388.05, -1131.07 and - 1860.11 kJ·mol-1, respectively.

  2. Enthalpy-Driven RNA Folding: Single-Molecule Thermodynamics of Tetraloop–Receptor Tertiary Interaction†

    Science.gov (United States)

    Fiore, Julie L.; Kraemer, Benedikt; Koberling, Felix; Edmann, Rainer; Nesbitt, David J.

    2010-01-01

    RNA folding thermodynamics are crucial for structure prediction, which requires characterization of both enthalpic and entropic contributions of tertiary motifs to conformational stability. We explore the temperature dependence of RNA folding due to the ubiquitous GAAA tetraloop–receptor docking interaction, exploiting immobilized and freely diffusing single-molecule fluorescence resonance energy transfer (smFRET) methods. The equilibrium constant for intramolecular docking is obtained as a function of temperature (T = 21–47 °C), from which a van’t Hoff analysis yields the enthalpy (ΔH°) and entropy (ΔS°) of docking. Tetraloop–receptor docking is significantly exothermic and entropically unfavorable in 1 mM MgCl2 and 100 mM NaCl, with excellent agreement between immobilized (ΔH° = −17.4 ± 1.6 kcal/mol, and ΔS° = −56.2 ± 5.4 cal mol−1 K−1) and freely diffusing (ΔH° = −17.2 ± 1.6 kcal/mol, and ΔS° = −55.9 ± 5.2 cal mol−1 K−1) species. Kinetic heterogeneity in the tetraloop–receptor construct is unaffected over the temperature range investigated, indicating a large energy barrier for interconversion between the actively docking and nondocking subpopulations. Formation of the tetraloop–receptor interaction can account for ~60% of the ΔH° and ΔS° of P4–P6 domain folding in the Tetrahymena ribozyme, suggesting that it may act as a thermodynamic clamp for the domain. Comparison of the isolated tetraloop–receptor and other tertiary folding thermodynamics supports a theme that enthalpy- versus entropy-driven folding is determined by the number of hydrogen bonding and base stacking interactions. PMID:19186984

  3. Determinations of enthalpy and partial molar enthalpy in the alloys Bi–Cd–Ga–In–Zn, Bi–Cd–Ga–Zn and Au–Cu–Sn

    International Nuclear Information System (INIS)

    Arslan, Hüseyin

    2015-01-01

    In the present study, the relations of thermodynamic associated with Chou's general solution model (GSM), the models of Muggianu and Toop have been used in order to calculate the mixing enthalpy and partial molar mixing enthalpy of mixing of Bi–Cd–Ga–In–Zn, Bi–Cd–Ga–Zn with equimolar section at a temperature of 730 K and Au–Cu–Sn with the section x Au /x Cu = 1/1 on the entire molar fraction range as a function of alloy composition at a temperature of 900 K. Some negativities are reported in the selected alloys mentioned above, particularly at high temperatures for the human health as well as difficulties in experimental measurement and high costs. Moreover, aim of us is to close the current article gap seen in the literature. In order to close the current gap seen in the literature, the article on the thermodynamic properties of the Bi–Cd–Ga–In–Zn alloys are presented in this study. - Highlights: • Thermodynamic properties of alloys in the study in given conditions were treated. • The activity of Bi seen in all models shows greatly positive deviation from ideality. • The enthalpy of Sn shows small negative values in x Au /x Cu = 1 at 900 K. • The activity of Sn shows negative deviation from ideality in the same conditions

  4. Experimental evaluation of enthalpy efficiency and gas-phase contaminant transfer in an enthalpy recovery unit with polymer membrane foils

    DEFF Research Database (Denmark)

    Nie, Jinzhe; Yang, Jianrong; Fang, Lei

    2015-01-01

    Experimental studies were conducted in a laboratory setting to investigate the enthalpy efficiency and gas-phase contaminant transfer in a polymer membrane enthalpy recovery unit. One commercially available polymer membrane enthalpy recovery unit was used as a reference unit. Simulated indoor air...... and outdoor air by twin chambers was connected to the unit. Three chemical gases were dosed to the indoor exhaust air to mimic indoor air contaminants. Based on the measurements of temperature, humidity ratio, and contaminant concentrations of the indoor exhaust air and outdoor air supply upstream...

  5. Standard molar enthalpies of formation of monochloroacetophenone isomers

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Amaral, Luisa M.P.F.

    2010-01-01

    The standard (p 0 =0.1MPa) molar enthalpies of formation of the liquids 2'-, 3'-, and 4'-chloroacetophenones were derived from the standard molar energies of combustion, in oxygen, to yield CO 2 (g) and HCl . 600H 2 O(l), at T = 298.15 K, measured by rotating-bomb combustion calorimetry. The Calvet microcalorimetry was used to measure the enthalpies of vaporization of the three compounds. These two thermodynamic parameters yielded the standard molar enthalpies of formation of the chloroacetophenone isomers, in the gaseous phase, at T = 298.15 K. (table) An empirical scheme, developed by Cox, was used to estimate the gas-phase enthalpies of formation and the obtained values were compared with the experimental ones.

  6. Enthalpy generation from mixing in hohlraum-driven targets

    Science.gov (United States)

    Amendt, Peter; Milovich, Jose

    2016-10-01

    The increase in enthalpy from the physical mixing of two initially separated materials is analytically estimated and applied to ICF implosions and gas-filled hohlraums. Pressure and temperature gradients across a classical interface are shown to be the origin of enthalpy generation from mixing. The amount of enthalpy generation is estimated to be on the order of 100 Joules for a 10 micron-scale annular mixing layer between the solid deuterium-tritium fuel and the undoped high-density carbon ablator of a NIF-scale implosion. A potential resonance is found between the mixing layer thickness and gravitational (Cs2/ g) and temperature-gradient scale lengths, leading to elevated enthalpy generation. These results suggest that if mixing occurs in current capsule designs for the National Ignition Facility, the ignition margin may be appreciably eroded by the associated enthalpy of mixing. The degree of enthalpy generation from mixing of high- Z hohlraum wall material and low- Z gas fills is estimated to be on the order of 100 kJ or more for recent NIF-scale hohlraum experiments, which is consistent with the inferred missing energy based on observed delays in capsule implosion times. Work performed under the auspices of Lawrence Livermore National Security, LLC (LLNS) under Contract No. DE-AC52-07NA27344.

  7. Enthalpies of vaporization of organometallic compounds

    International Nuclear Information System (INIS)

    Kuznetsov, N.T.; Sevast'yanov, V.G.; Mitin, V.A.; Krasnodubskaya, S.V.; Zakharov, L.N.; Domrachev, G.A.; AN SSSR, Gor'kij. Inst. Khimii)

    1987-01-01

    A possibility to use the method of additive schemes for the calculation of vaporizaton enthalpies of uranium organometallic compounds is discussed while comparing the values obtained using the method with experimental data. The possibility of apriori evaluation of evaporation enthalpy values of different uranium compounds using the method of additive schemes and structural characteristics of molecules, such as the sum of ligand solid angles, is shown

  8. Relationships between fusion, solution, vaporization and sublimation enthalpies of substituted phenols

    International Nuclear Information System (INIS)

    Yagofarov, Mikhail I.; Nagrimanov, Ruslan N.; Solomonov, Boris N.

    2017-01-01

    Highlights: • Method for determination of sublimation and vaporization enthalpies of phenols was developed. • Vaporization enthalpies of 28 phenols at 298 K were calculated. • Sublimation enthalpies of 26 phenols at 298 K were calculated using fusion enthalpies at melting temperatures. • Obtained values are in good agreement with the results of conventional methods. - Abstract: In this work a method for determination of sublimation and vaporization enthalpies of substituted phenols was developed. This method is a modification of solution calorimetry approach. Modification is based on the novel relations, which bind solution, vaporization and sublimation enthalpies at 298.15 K and fusion enthalpy at the melting temperature. According to novel relations the equations for calculating sublimation and vaporization enthalpies at 298.15 K were offered. Calculated values of sublimation and vaporization enthalpies of phenol derivatives containing alkyls, halogens, –OCH 3 , –NO 2 , –COCH 3 , –COOCH 3 groups, and dihydroxybenzenes were compared with literature data (298.15 K) obtained by conventional methods. In most of the cases divergence does not exceed 2–3%.

  9. Standard molar enthalpies of formation of monochloroacetophenone isomers

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro da Silva, Manuel A.V., E-mail: risilva@fc.up.p [Centro de Investigacao em Quimica, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Amaral, Luisa M.P.F. [Centro de Investigacao em Quimica, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal)

    2010-12-15

    The standard (p{sup 0}=0.1MPa) molar enthalpies of formation of the liquids 2'-, 3'-, and 4'-chloroacetophenones were derived from the standard molar energies of combustion, in oxygen, to yield CO{sub 2}(g) and HCl . 600H{sub 2}O(l), at T = 298.15 K, measured by rotating-bomb combustion calorimetry. The Calvet microcalorimetry was used to measure the enthalpies of vaporization of the three compounds. These two thermodynamic parameters yielded the standard molar enthalpies of formation of the chloroacetophenone isomers, in the gaseous phase, at T = 298.15 K. (table) An empirical scheme, developed by Cox, was used to estimate the gas-phase enthalpies of formation and the obtained values were compared with the experimental ones.

  10. Enthalpy of Formation of N 2 H 4 (Hydrazine) Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Feller, David [Department; Bross, David H. [Chemical; Ruscic, Branko [Chemical; Computation

    2017-08-02

    In order to address the accuracy of the long-standing experimental enthalpy of formation of gas-phase hydrazine, fully confirmed in earlier versions of Active Thermochemical Tables (ATcT), the provenance of that value is re-examined in light of new high-end calculations of the Feller-Peterson-Dixon (FPD) variety. An overly optimistic determination of the vaporization enthalpy of hydrazine, which created an unrealistically strong connection between the gas phase thermochemistry and the calorimetric results defining the thermochemistry of liquid hydrazine was identified as the probable culprit. The new enthalpy of formation of gas-phase hydrazine, based on balancing all available knowledge, was determined to be 111.57 ± 0.47 kJ/mol at 0 K (97.41 kJ/mol at 298.15 K). Close agreement was found between the ATcT (even excluding the latest theoretical result) and FPD enthalpies.

  11. Enthalpy of formation of anisole: implications for the controversy on the O-H bond dissociation enthalpy in phenol.

    Science.gov (United States)

    Simões, Ricardo G; Agapito, Filipe; Diogo, Hermínio P; da Piedade, Manuel E Minas

    2014-11-20

    Significant discrepancies in the literature data for the enthalpy of formation of gaseous anisole, ΔfHmo(PhOCH3, g), have fueled an ongoing controversy regarding the most reliable enthalpy of formation of the phenoxy radical and of the gas phase O-H bond dissociation enthalpy, DHo(PhO-H), in phenol. In the present work ΔfHmo(PhOCH3, g) was reassessed using a combination of calorimetric determinations and high-level (W2-F12) ab initio calculations. Static-bomb combustion calorimetry led to the standard molar enthalpy of formation of liquid anisole at 298.15 K, ΔfHmo(PhOCH3, l) = −(117.1 ± 1.4) kJ·mol(-1). The corresponding enthalpy of vaporization was obtained as, ΔvapHmo(PhOCH3) = 46.41 ± 0.26 kJ·mol(-1), by Calvet-drop microcalorimetry. These results give ΔfHmo(PhOCH3, g) = −(70.7 ± 1.4) kJ·mol(-1), in excellent agreement with ΔfHmo(PhOCH3, g) = −(70.8 ± 3.2) kJ·mol(-1), obtained from the W2-F12 calculations. The ΔfHmo(PhOCH3, g) here recommended leads to ΔfHmo(PhO•, g) = 55.5 ± 2.4 kJ·mol(-)1 and DH°(PhO-H) = 368.1 ± 2.6 kJ·mol(-1).

  12. On the Enthalpy and Entropy of Point Defect Formation in Crystals

    Science.gov (United States)

    Kobelev, N. P.; Khonik, V. A.

    2018-03-01

    A standard way to determine the formation enthalpy H and entropy S of point defect formation in crystals consists in the application of the Arrhenius equation for the defect concentration. In this work, we show that a formal use of this method actually gives the effective (apparent) values of these quantities, which appear to be significantly overestimated. The underlying physical reason lies in temperature-dependent formation enthalpy of the defects, which is controlled by temperature dependence of the elastic moduli. We present an evaluation of the "true" H- and S-values for aluminum, which are derived on the basis of experimental data by taking into account temperature dependence of the formation enthalpy related to temperature dependence of the elastic moduli. The knowledge of the "true" activation parameters is needed for a correct calculation of the defect concentration constituting thus an issue of major importance for different fundamental and application issues of condensed matter physics and chemistry.

  13. The thermochemistry of 2,4-pentanedione revisited: observance of a nonzero enthalpy of mixing between tautomers and its effects on enthalpies of formation.

    Science.gov (United States)

    Temprado, Manuel; Roux, Maria Victoria; Umnahanant, Patamaporn; Zhao, Hui; Chickos, James S

    2005-06-30

    The enthalpies of formation of pure liquid and gas-phase (Z)-4-hydroxy-3-penten-2-one and 2,4-pentanedione are examined in the light of some more recent NMR studies on the enthalpy differences between gas-phase enthalpies of the two tautomers. Correlation gas chromatography experiments are used to evaluate the vaporization enthalpies of the pure tautomers. Values of (51.2 +/- 2.2) and (50.8 +/- 0.6) kJ.mol(-1) are measured for pure 2,4-pentanedione and (Z)-4-hydroxy-3-penten-2-one, respectively. The value of (50.8 +/- 0.6) kJ.mol(-1) can be contrasted to a value of (43.2 +/- 0.2) kJ.mol(-1) calculated for pure (Z)-4-hydroxy-3-penten-2-one when the vaporization enthalpy is measured in a mixture of tautomers. The difference is attributed to an endothermic enthalpy of mixing that destabilizes the mixture relative to the pure components. Calculation of new enthalpies of formation for (Z)-4-hydroxy-3-penten-2-one and 2,4-pentanedione in both the gas, Delta(f)H degrees (m)(g) = (-378.2 +/- 1.2) and (-358.9 +/- 2.5) kJ.mol(-1), respectively, and liquid phases, Delta(f)H degrees (m)(l) = (-429.0 +/- 1.0) and (-410.1 +/- 1.2) kJ.mol(-1), respectively, results in enthalpy differences between the two tautomers both in the liquid and gas phases that are identical within experimental error, and in excellent agreement with recent gas-phase NMR studies.

  14. The relationship between vapour pressure, vaporization enthalpy, and enthalpy of transfer from solution to gas: An extension of the Martin equation

    International Nuclear Information System (INIS)

    Srisaipet, A.; Aryusuk, K.; Lilitchan, S.; Krisnangkura, K.

    2007-01-01

    Martin's equation, Δ sln g G=Δ sln g G o +zδ sln g G, is extended to cover vaporization free energy (Δ l g G). The extended equation is further expanded in terms of enthalpy and entropy and then used to correlate vaporization enthalpy (Δ l g H) and enthalpy of transfer from solution to gas (Δ sln g H). Data available in the literatures are used to validate and support the speculations derived from the proposed equation

  15. Enthalpy of sublimation as measured using a silicon oscillator

    Science.gov (United States)

    Shakeel, Hamza; Pomeroy, J. M.

    In this study, we report the enthalpy of sublimation of common gases (nitrogen, oxygen, argon, carbon dioxide, neon, krypton, xenon, and water vapor) using a large area silicon oscillator with a sub-ng (~0.027 ng/cm2) mass sensitivity. The double paddle oscillator design enables high frequency stability (17 ppb) at cryogenic temperatures and provides a consistent technique for enthalpy measurements. The enthalpies of sublimation are derived from the rate of mass loss during programmed thermal desorption and are detected as a change in the resonance frequency of the self-tracking oscillator. These measured enthalpy values show excellent agreement with the accepted literature values.

  16. Estimating the melting point, entropy of fusion, and enthalpy of ...

    Science.gov (United States)

    The entropies of fusion, enthalies of fusion, and melting points of organic compounds can be estimated through three models developed using the SPARC (SPARC Performs Automated Reasoning in Chemistry) platform. The entropy of fusion is modeled through a combination of interaction terms and physical descriptors. The enthalpy of fusion is modeled as a function of the entropy of fusion, boiling point, and fexibility of the molecule. The melting point model is the enthlapy of fusion divided by the entropy of fusion. These models were developed in part to improve SPARC's vapor pressure and solubility models. These models have been tested on 904 unique compounds. The entropy model has a RMS of 12.5 J mol-1K-1. The enthalpy model has a RMS of 4.87 kJ mol-1. The melting point model has a RMS of 54.4°C. Published in the journal, SAR and QSAR in Environmental Research

  17. Vapor pressures and enthalpies of vaporization of azides

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.; Emel'yanenko, Vladimir N.; Algarra, Manuel; Manuel Lopez-Romero, J.; Aguiar, Fabio; Enrique Rodriguez-Borges, J.; Esteves da Silva, Joaquim C.G.

    2011-01-01

    Highlights: → We prepared and measured vapor pressures and vaporization enthalpies of 7 azides. → We examined consistency of new and available in the literature data. → Data for geminal azides and azido-alkanes selected for thermochemical calculations. - Abstract: Vapor pressures of some azides have been determined by the transpiration method. The molar enthalpies of vaporization Δ l g H m of these compounds were derived from the temperature dependencies of vapor pressures. The measured data sets were successfully checked for internal consistency by comparison with vaporization enthalpies of similarly structured compounds.

  18. Energetic studies on DNA-peptide interaction in relation to the enthalpy-entropy compensation paradox.

    Science.gov (United States)

    Yang, Robin C K; Huang, Jonathan T B; Chien, Shih-Chuan; Huang, Roy; Jeng, Kee-Ching G; Chen, Yen-Chung; Liao, Mokai; Wu, Jia-Rong; Hung, Wei-Kang; Hung, Chia-Chun; Chen, Yu-Ling; Waring, Michael J; Sheh, Leung

    2013-01-07

    This study aims to interpret the energetic basis of complex DNA-peptide interactions according to a novel allosteric interaction network approach. In common with other designed peptides, five new conjugates incorporating the XPRK or XHypRK motif (Hyp = hydroxyproline) attached to a N-methylpyrrole (Py) tract with a basic tail have been found to display cooperative binding to DNA involving multiple monodentate as well as interstrand bidentate interactions. Using quantitative DNase I footprinting it appears that allosteric communication via cooperative binding to multiple sites on complementary DNA strands corresponds to two different types of DNA-peptide interaction network. Temperature variation experiments using a dodecapeptide RY-12 show that lower temperature (25 °C) favor a circuit type of allosteric interaction network, whereas higher temperatures (31 and 37 °C) afford only a partial-circuit type of network. Circular dichroism studies show that our five peptides induce significant local conformational changes in DNA via the minor groove, with apparently dimeric binding stoichiometry. Isothermal titration calorimetry reveals that these peptides, together with another seven for comparison, are strongly exothermic upon binding to a model 13-mer DNA duplex, characterized by ΔH ranging from -14.7 to -74.4 kcal mol(-1), and also high TΔS ranging from -6.5 to -65.9 kcal mol(-1). Multiple monodentate and bidentate interactions, as well as ionic forces that mediate positive cooperativity in sequence recognition, are consistent with a dramatic decrease in entropy and a 'tightening' effect of DNA conformation. Distinctive enthalpy-entropy compensation (EEC) relationships are demonstrated for the interaction of all twelve designed peptides with DNA, affording a straight line of slope close to unity when ΔH is plotted versus TΔS, with a y-axis intercept (average ΔG) corresponding to -8.5 kcal mol(-1), while the observed ΔG ranges from -8.2 to -9.1 kcal mol(-1) for

  19. Enthalpy of solution of rubidium nitrate in water

    International Nuclear Information System (INIS)

    Weintraub, R.; Apelblat, A.; Tamir, A.

    1984-01-01

    Molar enthalpies of solution of RbNO 3 in water at 298.15 K were measured in an LKB calorimeter. The molar enthalpies of solution extrapolated to infinite solution are: (36788 +- 30)J. mol -1 (Alfa) and (36539 +- 52)J.mol -1 (Aldrich). (author)

  20. Vapor pressure and enthalpy of vaporization of linear aliphatic alkanediamines

    International Nuclear Information System (INIS)

    Pozdeev, Vasiliy A.; Verevkin, Sergey P.

    2011-01-01

    Highlights: → We measured vapor pressure of diamines H 2 N-(CH 2 ) n -NH 2 with n = 3 to 12. → Vaporization enthalpies at 298 K were derived. → We examined consistency of new and available in the literature data. → Enthalpies of vaporization show linear dependence on numbers n. → Enthalpies of vaporization correlate linearly with Kovat's indices. - Abstract: Vapor pressures and the molar enthalpies of vaporization of the linear aliphatic alkanediamines H 2 N-(CH 2 ) n -NH 2 with n = (3 to 12) have been determined using the transpiration method. A linear correlation of enthalpies of vaporization (at T = 298.15 K) of the alkanediamines with the number n and with the Kovat's indices has been found, proving the internal consistency of the measured data.

  1. [Enthalpy stabilization of chicken egg lysozyme in aqueous dimethylsulfoxide solutions].

    Science.gov (United States)

    Kovrigin, E L; Kirkitadze, M D; Potekhin, S A

    1996-01-01

    Scanning microcalorimetry data have been used to plot the dependences of the denaturation enthalpy of hen egg lysozyme on dimethylsulfoxide concentration at fixed temperatures. It has been shown that at dimethylsulfoxide concentrations below 40% (v/v) the enthalpy does not depend on pH of the medium. An increase of dimethylsulfoxide concentrations in this range leads to a linear growth of enthalpy. The rate of enthalpy growth decreases with the temperature increase. The denaturation enthalpy begins to considerably depend on pH at dimethylsulfoxide concentrations more than 40%. Spectroscopy data indicate that conformational changes occur in the protein in this range of concentrations already at room temperature, whereas according to scanning microcalorimetry, they take place at much higher temperatures. This difference is probably due to a decrease of the real temperature of protein melting below room temperature and a very inhibited character of the denaturational transition. This results in a decrease of calorimetric enthalpy at acidic pH owing to incomplete protein renaturation upon calorimeter cooling to the starting point.

  2. Experimental formation enthalpies for intermetallic phases and other inorganic compounds

    Science.gov (United States)

    Kim, George; Meschel, S. V.; Nash, Philip; Chen, Wei

    2017-01-01

    The standard enthalpy of formation of a compound is the energy associated with the reaction to form the compound from its component elements. The standard enthalpy of formation is a fundamental thermodynamic property that determines its phase stability, which can be coupled with other thermodynamic data to calculate phase diagrams. Calorimetry provides the only direct method by which the standard enthalpy of formation is experimentally measured. However, the measurement is often a time and energy intensive process. We present a dataset of enthalpies of formation measured by high-temperature calorimetry. The phases measured in this dataset include intermetallic compounds with transition metal and rare-earth elements, metal borides, metal carbides, and metallic silicides. These measurements were collected from over 50 years of calorimetric experiments. The dataset contains 1,276 entries on experimental enthalpy of formation values and structural information. Most of the entries are for binary compounds but ternary and quaternary compounds are being added as they become available. The dataset also contains predictions of enthalpy of formation from first-principles calculations for comparison. PMID:29064466

  3. Accounting for apparent deviations between calorimetric and van't Hoff enthalpies.

    Science.gov (United States)

    Kantonen, Samuel A; Henriksen, Niel M; Gilson, Michael K

    2018-03-01

    In theory, binding enthalpies directly obtained from calorimetry (such as ITC) and the temperature dependence of the binding free energy (van't Hoff method) should agree. However, previous studies have often found them to be discrepant. Experimental binding enthalpies (both calorimetric and van't Hoff) are obtained for two host-guest pairs using ITC, and the discrepancy between the two enthalpies is examined. Modeling of artificial ITC data is also used to examine how different sources of error propagate to both types of binding enthalpies. For the host-guest pairs examined here, good agreement, to within about 0.4kcal/mol, is obtained between the two enthalpies. Additionally, using artificial data, we find that different sources of error propagate to either enthalpy uniquely, with concentration error and heat error propagating primarily to calorimetric and van't Hoff enthalpies, respectively. With modern calorimeters, good agreement between van't Hoff and calorimetric enthalpies should be achievable, barring issues due to non-ideality or unanticipated measurement pathologies. Indeed, disagreement between the two can serve as a flag for error-prone datasets. A review of the underlying theory supports the expectation that these two quantities should be in agreement. We address and arguably resolve long-standing questions regarding the relationship between calorimetric and van't Hoff enthalpies. In addition, we show that comparison of these two quantities can be used as an internal consistency check of a calorimetry study. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Standard enthalpies of formation of uranium compounds

    International Nuclear Information System (INIS)

    Cordfunke, E.H.P.; Ouweltjes, W.

    1977-01-01

    Enthalpies of solution of β-UO 2 SO 4 and α-UO 2 SeO 4 in H 2 SO 4 (aq) and of UO 2 SeO 3 in H 2 SO 4 (aq) + Ce(SO 4 ) 2 have been measured calorimetrically. Together with measurements of the enthalpy of solution of γ-UO 3 in these solvents, the standard enthalpies of formation of anhydrous β-UO 2 SO 4 , α-UO 2 SeO 4 , and UO 2 SeO 3 have been derived. The results obtained are: ΔHsub(f) 0 (s, 298.15 K)/ kcalsub(th) mol -1 : β-UO 2 SO 4 , -(440.9 +- 0.2); α-UO 2 SeO 4 , -(367.9 +- 0.8); UO 2 SeO 3 , -(363.8 +- 0.2). (author)

  5. Enthalpy of solution of α- and β-cyclodextrin in water and in some organic solvents

    International Nuclear Information System (INIS)

    Belica, Sylwia; Sadowska, Monika; Stępniak, Artur; Graca, Anna; Pałecz, Bartłomiej

    2014-01-01

    Highlights: • A great influence of crystalline water on the energetic of dissolving compounds. • The strongest interaction between β-cyclodextrin and DMSO. • The enthalpic pair interaction coefficient, h βCD-EtOH , obtained is positive. • Predominating effects of the partial dehydration of the molecules – βCD-EtOH. -- Abstract: The calorimetric measurements of solution enthalpy of α-cyclodextrin, β-cyclodextrin in water (H 2 O), dimetyloformamid (DMF), dimethyl sulfoxide (DMSO) and aqueous ethanol solutions (H 2 O + EtOH) at 298.15 K were made. The experimental results were used to calculate the enthalpic coefficients of the interactions between cyclodextrin and ethanol molecules in water based on McMillan–Mayer’s model. The results were compared with literature data and with hydrodynamic radii of cyclodextrin in examined solvents and with donor numbers of these solvents. In order to check, if the inclusion complex formation between the solvent with the highest enthalpy of solution and cyclodextrin has happened, the calorimetric isothermal titration measurements were made and the results were interpreted

  6. Excess molar enthalpies for binary mixtures of different amines with water

    International Nuclear Information System (INIS)

    Zhang, Ruilei; Chen, Jian; Mi, Jianguo

    2015-01-01

    Highlights: • Isothermal excess molar enthalpies for binary mixtures of different amines with water. • The Redlich–Kister equation and the NRTL model was used to fit the experimental data. • The excess molar enthalpies were discussed with different structures of amines. - Abstract: The isothermal excess molar enthalpies for binary mixtures of different amines with water were measured with a C-80 Setaram calorimeter. The experimental results indicate that the excess molar enthalpy is related to the molecular structure. The experimental excess molar enthalpies were satisfactorily fitted with the Redlich–Kister equation. They were also used to test the suitability of the NRTL model, and the deviations are a little larger than the R–K equation

  7. Vapor pressures and sublimation enthalpies of novel bicyclic heterocycle derivatives

    International Nuclear Information System (INIS)

    Blokhina, Svetlana V.; Ol’khovich, Marina V.; Sharapova, Angelica V.; Perlovich, German L.; Proshin, Alexey N.

    2014-01-01

    Highlights: • The vapor pressures of novel bicyclo-derivatives of amine were measured. • Thermodynamic functions of sublimation were calculated. • The influence of substituent structure and chemical nature on the vapor pressure was studied. -- Abstract: The vapor pressures of five novel bicyclic heterocycle derivatives were measured over the temperature 341.15 to 396.15 K using the transpiration method by means of an inert gas carrier. From these results the standard enthalpies and Gibbs free energies of sublimation at the temperature 298.15 K were calculated. The effects of alkyl- and chloro-substitutions on changes in the thermodynamic functions have been investigated. Quantitative structure–property relationship on the basis HYBOT physico-chemical descriptors for biologically active compounds have been developed to predict the sublimation enthalpies and Gibbs free energies of the compounds studied

  8. The determination of the enthalpy of formation and the enthalpy increment of Cd0.5 Te0.5 by Calvet calorimetry

    International Nuclear Information System (INIS)

    Agarwal, R.; Venugopal, V.; Sood, D.D.

    1993-01-01

    In the present study the enthalpy of formation of Cd 0.5 Te 0.5 compound at 785 K were determined from the two elements by direct reaction calorimetry using two different types of set-ups. The enthalpy increment values were measured by drop technique in Calvet calorimetry. (author). 3 refs., 4 tabs

  9. Phase Transition Enthalpy Measurements of Organic and Organometallic Compounds. Sublimation, Vaporization and Fusion Enthalpies From 1880 to 2015. Part 1. C1 - C10

    Science.gov (United States)

    Acree, William; Chickos, James S.

    2016-09-01

    A compendium of phase change enthalpies published in 2010 is updated to include the period 1880-2015. Phase change enthalpies including fusion, vaporization, and sublimation enthalpies are included for organic, organometallic, and a few inorganic compounds. Part 1 of this compendium includes organic compounds from C1 to C10. Part 2 of this compendium, to be published separately, will include organic and organometallic compounds from C11 to C192. Sufficient data are presently available to permit thermodynamic cycles to be constructed as an independent means of evaluating the reliability of the data. Temperature adjustments of phase change enthalpies from the temperature of measurement to the standard reference temperature, T = 298.15 K, and a protocol for doing so are briefly discussed.

  10. Standard molar enthalpies of formation of 1- and 2-cyanonaphthalene

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Lobo Ferreira, Ana I.M.C.; Barros, Ana L.M.; Bessa, Ana R.C.; Brito, Barbara C.S.A.; Vieira, Joana A.S.; Martins, Silvia A.P.

    2011-01-01

    Highlights: → Enthalpies of formation of 1- and 2-cyanonaphthalene were measured by combustion calorimetry. → Vapor pressures of crystalline 1- and 2-cyanonaphthalene obtained by Knudsen effusion mass loss technique. → Enthalpies, entropies and Gibbs functions of sublimation at T = 298.15 K were calculated. - Abstract: The standard (p o = 0.1 MPa) molar enthalpies of formation, in the crystalline state, of the 1- and 2-cyanonaphthalene were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static-bomb combustion calorimetry. Vapor pressure measurements at different temperatures, using the Knudsen mass loss effusion technique, enabled the determination of the enthalpy, entropy, and Gibbs energy of sublimation, at T = 298.15 K, for both isomers. The standard molar enthalpies of sublimation, at T = 298.15 K, for 1- and 2-cyanonaphthalene, were also measured by high-temperature Calvet microcalorimetry. (table) Combining these two experimental values, the gas-phase standard molar enthalpies, at T = 298.15 K, were derived and compared with those estimated by employing two different methodologies: one based on the Cox scheme and the other one based on G3MP2B3 calculations. The calculated values show a good agreement with the experimental values obtained in this work.

  11. Group additivity values for enthalpies of formation (298 K), entropies (298 K), and molar heat capacities (300 K < T < 1500 K) of gaseous fluorocarbons

    International Nuclear Information System (INIS)

    Van Otterloo, Maren K.; Girshick, Steven L.; Roberts, Jeffrey T.

    2007-01-01

    A group additivity method was developed to estimate standard enthalpies of formation and standard entropies at 298 K of linear radical and closed-shell, gaseous fluorocarbon neutrals containing four or more carbon atoms. The method can also be used to estimate constant pressure molar heat capacities of the same compounds over the temperature range 300 K to 1500 K. Seventeen groups and seven fluorine-fluorine interaction terms were defined from 12 fluorocarbon molecules. Interaction term values from Yamada and Bozzelli [T. Yamada, J.W. Bozzelli, J. Phys. Chem. A 103 (1999) 7373-7379] were utilized. The enthalpy of formation group values were derived from G3MP2 calculations by Bauschlicher and Ricca [C.W. Bauschlicher, A. Ricca, J. Phys. Chem. A 104 (2000) 4581-4585]. Standard entropy and molar heat capacity group values were estimated from ab initio geometry optimization and frequency calculations at the Hartree-Fock level using the 6-31G(d) basis set. Enthalpies of formation for larger fluorocarbons estimated from the group additivity method compare well to enthalpies of formation found in the literature

  12. Enthalpies of solution of N,N,N',N'-tetramethylurea in amides, dimethylsulphoxide, and acetone at 298.15 K

    International Nuclear Information System (INIS)

    Ivanov, Evgeniy V.; Smirnov, Valeriy I.

    2008-01-01

    The enthalpies of solution Δ sol H m m were determined for N,N,N',N'-tetramethylurea in formamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulphoxide, and acetone. Measurements were made at 298.15 K and molalities m = (0.004 to 0.031) mol . kg -1 with a precise isoperibol ampoule-type calorimeter. Standard enthalpies of solution Δ sol H m 0 and transfer Δ tr H m 0 from one solvent to another were computed. The enthalpies of solution of the solute in the hydrogen-non-bonding media were found to be endothermic and weak depending on the nature of methylation in a solvent molecule. It was concluded that the solvent proton-donor ability and existing steric hindrances for hydrogen bonding and other intermolecular interactions play the key role in solvation of tetramethylurea

  13. Titration calorimetry of anesthetic-protein interaction: negative enthalpy of binding and anesthetic potency.

    Science.gov (United States)

    Ueda, I; Yamanaka, M

    1997-04-01

    Anesthetic potency increases at lower temperatures. In contrast, the transfer enthalpy of volatile anesthetics from water to macromolecules is usually positive. The transfer decreases at lower temperature. It was proposed that a few selective proteins bind volatile anesthetics with negative delta H, and these proteins are involved in signal transduction. There has been no report on direct estimation of binding delta H of anesthetics to proteins. This study used isothermal titration calorimetry to analyze chloroform binding to bovine serum albumin. The calorimetrically measured delta H cal was -10.37 kJ.mol-1. Thus the negative delta H of anesthetic binding is not limited to signal transduction proteins. The binding was saturable following Fermi-Dirac statistics and is characterized by the Langmuir adsorption isotherms, which is interfacial. The high-affinity association constant, K, was 2150 +/- 132 M-1 (KD = 0.47 mM) with the maximum binding number, Bmax = 3.7 +/- 0.2. The low-affinity K was 189 +/- 3.8 M-1 (KD = 5.29 mM), with a Bmax of 13.2 +/- 0.3. Anesthetic potency is a function of the activity of anesthetic molecules, not the concentration. Because the sign of delta H determines the temperature dependence of distribution of anesthetic molecules, it is irrelevant to the temperature dependence of anesthetic potency.

  14. An empirical equation for the enthalpy of vaporization of quantum liquids

    International Nuclear Information System (INIS)

    Kuz, Victor A.; Meyra, Ariel G.; Zarragoicoechea, Guillermo J.

    2004-01-01

    An empirical equation for the enthalpy of vaporization of quantum fluids is presented. Dimensionless analysis is used to define enthalpy of vaporization as a function of temperature with a standard deviation of about 1%. Experimental data represented in these variables show two different behaviours and exhibit different maximum values of the enthalpy of vaporization, one corresponding to fluids with a triple point and the other to fluids having a lambda point. None of the existing empirical equations are able to describe this fact. Also enthalpy of vaporization of helium-3, n-deuterium and n-tritium are estimated

  15. Activity coefficients at infinite dilution and enthalpies of solution of methanol, 1-butanol, and 1-hexanol in 1-hexyl-3-methyl-imidazolium bis(trifluoromethyl-sulfonyl) imide

    International Nuclear Information System (INIS)

    Heintz, Andreas; Verevkin, Sergey P.; Lehmann, Jochen K.; Vasiltsova, Tatiana V.; Ondo, Daniel

    2007-01-01

    Activity coefficients at infinite dilution γ i ∼ of methanol, 1-butanol, and 1-hexanol in the ionic liquid 1-hexyl-3-methyl-imidazolium bis(trifluoromethyl-sulfonyl) imide ([HMIM][NTf 2 ]) have been determined by gas chromatography using the ionic liquids as stationary phase. The measurements were carried out at different temperatures between 298K and 396K. From the temperature dependence of the limiting activity coefficients partial molar excess enthalpies at infinite dilution H i E,∼ of the alcohol in the ionic liquid have been derived. Additionally, enthalpies of solution of the same alcohols in the [HMIM][NTf 2 ] have been measured at T=298.15K in the range of low concentrations using titration calorimetry. Results at infinite dilution, H i E,∼ , are compared with those indirectly obtained from activity coefficients in infinite dilution γ i ∼ . Within the experimental error of both methods thermodynamic consistency has been confirmed

  16. Vapor pressure and enthalpy of vaporization of aliphatic propanediamines

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.; Chernyak, Yury

    2012-01-01

    Highlights: ► We measured vapor pressure of four aliphatic 1,3-diamines. ► Vaporization enthalpies at 298 K were derived. ► We examined consistency of new and available data in the literature. ► A group-contribution method for prediction was developed. - Abstract: Vapor pressures of four aliphatic propanediamines including N-methyl-1,3-propanediamine (MPDA), N,N-dimethyl-1,3-propanediamine (DMPDA), N,N-diethyl-1,3-propanediamine (DEPDA) and N,N,N′,N′-tetramethyl-1,3-propanediamine (4MPDA) were measured using the transpiration method. The vapor pressures developed in this work and reported in the literature were used to derive molar enthalpy of vaporization values at the reference temperature 298.15 K. An internal consistency check of the enthalpy of vaporization was performed for the aliphatic propanediamines studied in this work. A group-contribution method was developed for the validation and prediction vaporization enthalpies of amines and diamines.

  17. Hypervelocity Expansion Facility for Fundamental High-Enthalpy Research

    Science.gov (United States)

    2017-02-27

    ii Final Technical Report of Contract ONR N00014-15-1-2260 Entitled: HYPERVELOCITY EXPANSION FACILITY FOR FUNDAMENTAL HIGH-ENTHALPY...previous DoD investments in high-energy pulsed laser diagnostics for instantaneous planar velocimetry and thermometry to perform scientific studies of...capability for fundamental and applied studies of hypervelocity high enthalpy flows. In this document, we report on the progress over the 18-month

  18. Determination of vaporization enthalpies of polychlorinated biphenyls by correlation gas chromatography.

    Science.gov (United States)

    Puri, S; Chickos, J S; Welsh, W J

    2001-04-01

    The vaporization enthalpies of 16 polychlorinated biphenyls have been determined by correlation gas chromatography. This study was prompted by the realization that the vaporization enthalpy of the standard compounds used in previous studies, octadecane and eicosane, were values measured at 340 and 362 K, respectively, rather than at 298 K. Adjustment to 298 K amounts to a 7-8 kJ/mol increment in the values. With the inclusion of this adjustment, vaporization enthalpies evaluated by correlation gas chromatography are in good agreement with the values determined previously in the literature. The present results are based on the vaporization enthalpies of several standards whose values are well established in the literature. The standards include a variety of n-alkanes and various chlorinated hydrocarbons. The vaporization enthalpies of PCBs increased with the number of chlorine atoms and were found to be larger for meta- and para-substituted polychlorinated biphenyls.

  19. Integral enthalpy of mixing of the liquid ternary Au-Cu-Sn system

    International Nuclear Information System (INIS)

    Knott, S.; Li, Z.; Mikula, A.

    2008-01-01

    The integral enthalpy of mixing of the ternary Au-Cu-Sn has been determined with a Calvet type calorimeter at 6 different cross sections at 1273 K. The substitutional solution model of Redlich-Kister-Muggianu was used for a least square fit of the experimental data in order to get an analytical expression for the integral enthalpy of mixing. The ternary extrapolation models of Kohler, Muggianu and Toop were used to calculate the integral enthalpy of mixing and to compare measured and extrapolated values. Additional calculations of the integral enthalpy of mixing using the Chou model have been performed. With the calculated data, the iso-enthalpy lines have been determined using the Redlich-Kister-Muggianu model. A comparison of the data has been made

  20. Gas phase enthalpies of formation of nitrobenzamides using combustion calorimetry and thermal analysis

    International Nuclear Information System (INIS)

    Ximello, Arturo; Flores, Henoc; Rojas, Aarón; Adriana Camarillo, E.; Patricia Amador, M.

    2014-01-01

    Graphical abstract: - Highlights: • Formation enthalpies of the nitrobenzamides were derived from combustion calorimetry. • Enthalpies of vaporisation and sublimation were calculated by thermogravimetry. • From gas phase enthalpies of formation the stability of the isomers is studied. • Stability of isomers is not driven by a steric hindrance between functional groups. - Abstract: The standard molar energies of combustion of 2-nitrobenzamide, 3-nitrobenzamide and 4-nitrobenzamide were determined with an isoperibolic, static-bomb, combustion calorimeter. From the combustion results, the standard molar enthalpies of combustion and formation for these compounds in the condensed phase at T = 298.15 K were derived. Subsequently, to determine the enthalpies of sublimation, the vapour pressure data as a function of the temperature for the compounds under investigation were estimated using thermogravimetry by applying Langmuir’s equation, and the enthalpies of vaporisation were derived. Standard enthalpies of fusion were measured by differential scanning calorimetry then added to those of vaporisation to obtain reliable results for the enthalpy of sublimation. From the combustion and sublimation data, the gas phase enthalpies of formation were determined to be (−138.9 ± 3.5) kJ · mol −1 , (−122.9 ± 2.9) kJ · mol −1 and (−108.5 ± 3.7) kJ · mol −1 for the ortho, meta and para isomers of nitrobenzamide, respectively. The meaning of these results with regard to the enthalpic stability of these molecular structures is discussed herein

  1. Formation enthalpy of iron, chromium and aluminium vanadates

    International Nuclear Information System (INIS)

    Kesler, Ya.A.; Cheshnitskij, S.M.; Fotiev, A.A.; Tret'yakov, Yu.D.

    1985-01-01

    The enthalpies of formation of FeVO 4 , CrVO 4 and AlVO 4 orthovanadates are determined. The method for measuring reaction heats of direct synthesis of oxide compounds is used. All experiments have been conducted at 973 K. The measurements have been performed by the drop-calorimetry method using high temperature differential microcalorimeter. The specified enthalpy values of FeVO 4 , CrVO 4 , AlVO 4 and FeCr(VO 4 ) 2 formation are obtained

  2. Predicting the enthalpies of melting and vaporization for pure components

    Science.gov (United States)

    Esina, Z. N.; Korchuganova, M. R.

    2014-12-01

    A mathematical model of the melting and vaporization enthalpies of organic components based on the theory of thermodynamic similarity is proposed. In this empirical model, the phase transition enthalpy for the homological series of n-alkanes, carboxylic acids, n-alcohols, glycols, and glycol ethers is presented as a function of the molecular mass, the number of carbon atoms in a molecule, and the normal transition temperature. The model also uses a critical or triple point temperature. It is shown that the results from predicting the melting and vaporization enthalpies enable the calculation of binary phase diagrams.

  3. Standard molar enthalpies of formation and of sublimation of the terphenyl isomers

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Santos, Luis M.N.B.F.; Lima, Luis M. Spencer S.

    2008-01-01

    The standard (p 0 = 0.1 MPa) molar enthalpies of formation in the crystalline phases of ortho, meta and para-terphenyl isomers, at T = 298.15 K, were derived from the standard molar energies of combustion, measured by mini-bomb combustion calorimetry. The Knudsen mass-loss effusion technique was used to measure the dependence of the vapour pressure of the crystals with the temperature, thus deriving their standard molar enthalpies of sublimation by means of the Clausius-Clapeyron equation. Combining the standard molar enthalpies of formation and sublimation of the crystalline terphenyls, the standard molar enthalpies of formation in the gaseous state, at T = 298.15 K, were derived for the three isomers. Results are provided in a table. The results show small but detectable isomerization enthalpies between the terphenyls, indicating the following relative enthalpic stabilities: m- > p- ∼ o-terphenyl

  4. Standard molar enthalpies of formation of three N-benzoylthiocarbamic-O-alkylesters

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Santos, Luis M.N.B.F.; Schroeder, Bernd; Dietze, Frank; Beyer, Lothar

    2004-01-01

    The standard (p 0 =0.1 MPa) molar enthalpies of combustion in oxygen of three crystalline N-benzoylthiocarbamic-O-alkylesters, PhCONHCSOR, R=Et (Hbtcee), n-Bu (Hbtcbe), n-Hex (Hbtche), were measured at T=298.15 K by rotating bomb calorimetry. The standard molar enthalpies of sublimation of the three compounds were measured using Calvet microcalorimetry. These values were used to derive the standard molar enthalpies of formation of the compounds in their crystalline and gaseous phases, respectively

  5. Effect of temperature on the dilution enthalpies of α,ω-amino acids in aqueous solutions

    International Nuclear Information System (INIS)

    Romero, C.M.; Cadena, J.C.; Lamprecht, I.

    2011-01-01

    Highlights: → The dilution of 3-amino propanoic acid, 4-amino butanoic acid, 5-amino pentanoic acid, and 6-amino hexanoic acid in water is an exothermic process at T = (293.15, 298.15, 303.15, and 308.15) K. → The limiting experimental slopes of the enthalpies of dilution with respect to the molality change Δm, are negative suggesting that the solutes interact with water primarily through their alkyl groups. → The value of the pairwise coefficient is positive at the temperatures considered, and the magnitude increases linearly with the number of methylene groups. → The comparison between the pairwise interaction coefficients for α,ω-amino acids and α-amino acids shows that the change in the enthalpic interaction coefficient is related to the relative position of the polar groups. - Abstract: Dilution enthalpies of aqueous solutions of 3-amino propanoic acid, 4-amino butanoic acid, 5-amino pentanoic acid, and 6-amino hexanoic acid were determined at T = (293.15, 298.15, 303.15, and 308.15) K using an LKB flow microcalorimeter. The homotactic interaction coefficients were obtained according to the McMillan-Mayer theory from the experimental data. For all the systems studied, the dilution of α,ω-amino acids in water is an exothermic process; the pair coefficients have positive values which increases with chain length. The obtained values of the interaction coefficients are interpreted in terms of solute-solvent and solute-solute interactions and are used as indicative of hydrophobic behavior of the amino acid studied.

  6. Standard molar enthalpies of formation of 2-, 3- and 4-cyanobenzoic acids

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Amaral, Luisa M.P.F.; Boaventura, Cristina R.P.; Gomes, Jose R.B.

    2008-01-01

    The standard (p 0 = 0.1 MPa) molar enthalpies of formation of 2-, 3- and 4-cyanobenzoic acids were derived from their standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The Calvet high temperature vacuum sublimation technique was used to measure the enthalpies of sublimation of 2- and 3-cyanobenzoic acids. The standard molar enthalpies of formation of the three compounds, in the gaseous phase, at T = 298.15 K, have been derived from the corresponding standard molar enthalpies of formation in the condensed phase and standard molar enthalpies for phase transition. The results obtained are -(150.7 ± 2.0) kJ . mol -1 , -(153.6 ± 1.7) kJ . mol -1 and -(157.1 ± 1.4) kJ . mol -1 for 2-cyano, 3-cyano and 4-cyanobenzoic acids, respectively. Standard molar enthalpies of formation were also estimated by employing two different methodologies: one based on the Cox scheme and the other one based on several different computational approaches. The calculated values show a good agreement with the experimental values obtained in this work

  7. Enthalpy changes when passing from simple to complex perovskite-like oxides

    International Nuclear Information System (INIS)

    Reznitskij, L.A.

    1999-01-01

    Formation enthalpies of complex perovskite-like oxides and their hexagonal analogs of the composition: Ba 2 ReFeO 6 , Sr 2 ReFeO 6 , Sr 2 ReMnO 6 , Ca 2 ReMnO 6 , Sr 2 WCrO 6 , Sr 2 MoCrO 6 , Ca 2 MoCrO 6 , Ca 2 WCrO 6 , Ba 3 Fe 2 ReO 9 , Ba 3 Cr 2 ReO 9 , Ba 2 RhTaO 6 and B 2 ScIrO 6 from simple oxides were calculated by approximate method using enthalpies of the cations coordination change in oxygen medium. The conclusion was made that enthalpy stabilization of the oxide with regard to simple oxides is mainly determined by the change in enthalpies of alkaline earth metal cations [ru

  8. New experimental heat capacity and enthalpy of formation of lithium cobalt oxide

    International Nuclear Information System (INIS)

    Gotcu-Freis, Petronela; Cupid, Damian M.; Rohde, Magnus; Seifert, Hans J.

    2015-01-01

    Highlights: • LiCoO 2 heat capacity was measured in the temperature range (160 to 953) K using DSC. • Continuous/discontinuous methods were applied on different types of calorimeters. • Enthalpy increment of LiCoO 2 was determined using drop calorimetry at T = 974 K. • Enthalpies of formation were evaluated from oxide melt drop solution calorimetry. - Abstract: The heat capacity of LiCoO 2 (O3-phase), constituent material in cathodes for lithium-ion batteries, was measured using two differential scanning calorimeters over the temperature range from (160 to 953) K (continuous method). As an alternative, the discontinuous method was employed over the temperature range from (493 to 693) K using a third calorimeter. Based on the results obtained, the enthalpy increment of LiCoO 2 was derived from T = 298.15 K up to 974.15 K. Very good agreement was obtained between the derived enthalpy increment and our independent measurements of enthalpy increment using transposed temperature drop calorimetry at 974.15 K. In addition, values of the enthalpy of formation of LiCoO 2 from the constituent oxides and elements were assessed based on measurements of enthalpy of dissolution using high temperature oxide melt drop solution calorimetry. The high temperature values obtained by these measurements are key input data in safety analysis and optimisation of the battery management systems which accounts for possible thermal runaway events

  9. Enthalpy of formation of titanium diboride

    International Nuclear Information System (INIS)

    Akhachinskij, V.V.; Chirin, N.A.

    1975-01-01

    The values given in the literature for the enthalpy of the formation of titanium diboride, as obtained experimentally and by theoretical estimation, range between -32 and -74.4 kcal/mol. In this paper the authors use the method of direct synthesis from elements in a Calvet calorimeter to determine the enthalpy of formation, ΔHsub(f) 0 , sub(298), of titanium diboride with the composition Tisub(1.000+-0.002)Bsub(2.056+-0.006)Csub(0.009)Nsub(0.003), which was found to be -76.78+-0.83 kcal/mol. They calculate that ΔHsub(f,298) (TiBsub(2.056)=-76.14+-0.85 kcal/mol. The procedure employed makes it possible to carry out the titanium diboride synthesis reaction with the calorimeter at room temperature

  10. Formation enthalpy of iron, chromium and aluminium vanadates

    Energy Technology Data Exchange (ETDEWEB)

    Kesler, Ya.A.; Cheshnitskij, S.M.; Fotiev, A.A.; Tret' yakov, Yu.D.

    1985-04-01

    The enthalpies of formation of FeVO/sub 4/, CrVO/sub 4/ and AlVO/sub 4/ orthovanadates are determined. The method for measuring reaction heats of direct synthesis of oxide compounds is used. All experiments have been conducted at 973 K. The measurements have been performed by the drop-calorimetry method using high temperature differential microcalorimeter. The specified enthalpy values of FeVO/sub 4/, CrVO/sub 4/, AlVO/sub 4/ and FeCr(VO/sub 4/)/sub 2/ formation are obtained.

  11. What is the enthalpy of formation of pyrazine-2-carboxylic acid?

    International Nuclear Information System (INIS)

    Miranda, Margarida S.; Duarte, Darío J.R.; Liebman, Joel F.

    2016-01-01

    There are two contemporary conflicting, indeed, incompatible determinations of measurements of the enthalpies of combustion and of formation of pyrazine-2-carboxylic acid in the literature, (−2268.0 ± 0.9 and −271.2 ± 1.1 kJ · mol −1 ) and (−2211.4 ± 0.9 and −327.8 ± 1.1 kJ · mol −1 ). The current paper discusses these two sets of values and from the use of a measurement of the enthalpy of sublimation, a newly evaluated enthalpy of formation of pyrazine itself, and of the quantum chemical calculations at the G3(MP2)//B3LYP level, the former results are accepted and the derived gas phase enthalpy of formation, −(167.6 ± 3.1) kJ · mol −1 , suggested.

  12. Thermodynamics of interactions between mammalian cytochromes P450 and b5.

    Science.gov (United States)

    Yablokov, Evgeny; Florinskaya, Anna; Medvedev, Alexei; Sergeev, Gennady; Strushkevich, Natallia; Luschik, Alexander; Shkel, Tatsiana; Haidukevich, Irina; Gilep, Andrei; Usanov, Sergey; Ivanov, Alexis

    2017-04-01

    Cytochromes P450 (CYPs) play an important role in the metabolism of xenobiotics and various endogenous substrates. Being a crucial component of the microsomal monooxygenase system, CYPs are involved in numerous protein-protein interactions. However, mechanisms underlying molecular interactions between components of the monooxygenase system still need better characterization. In this study thermodynamic parameters of paired interactions between mammalian CYPs and cytochromes b5 (CYB5) have been evaluated using a Surface Plasmon Resonance (SPR) based biosensor Biacore 3000. Analysis of 18 pairs of CYB5-CYP complexes formed by nine different isoforms of mammalian CYPs and two isoforms of human CYB5 has shown that thermodynamically these complexes can be subdivided into enthalpy-driven and entropy-driven groups. Formation of the enthalpy-driven complexes was observed in the case of microsomal CYPs allosterically regulated by CYB5 (CYB5A-CYP3A4, CYB5A-CYP3A5, CYB5A-CYP17A1). The entropy-driven complexes were formed when CYB5 had no effect on the CYP activity (CYB5A-CYP51A1, CYB5A-CYP1B1, CYB5B-CYP11A1). Results of this study suggest that such interactions determining protein clustering are indirectly linked to the monooxygenase functioning. Positive ΔH values typical for such interactions may be associated with displacement of the solvation shells of proteins upon clustering. CYB5-CYP complex formation accompanied by allosteric regulation of CYP activity by CYB5 is enthalpy-dependent. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Improved algorithm based on equivalent enthalpy drop method of pressurized water reactor nuclear steam turbine

    International Nuclear Information System (INIS)

    Wang Hu; Qi Guangcai; Li Shaohua; Li Changjian

    2011-01-01

    Because it is difficulty to accurately determine the extraction steam turbine enthalpy and the exhaust enthalpy, the calculated result from the conventional equivalent enthalpy drop method of PWR nuclear steam turbine is not accurate. This paper presents the improved algorithm on the equivalent enthalpy drop method of PWR nuclear steam turbine to solve this problem and takes the secondary circuit thermal system calculation of 1000 MW PWR as an example. The results show that, comparing with the design value, the error of actual thermal efficiency of the steam turbine cycle obtained by the improved algorithm is within the allowable range. Since the improved method is based on the isentropic expansion process, the extraction steam turbine enthalpy and the exhaust enthalpy can be determined accurately, which is more reasonable and accurate compared to the traditional equivalent enthalpy drop method. (authors)

  14. Theoretical-experimental study of the solvation enthalpy of acetone in dilute aqueous solution

    International Nuclear Information System (INIS)

    Arroyo, S. Tolosa; Martin, J.A. Sanson; Garcia, A. Hidalgo

    2005-01-01

    The present paper describes molecular dynamics simulations of aqueous solutions at infinite dilution with acetone as solute. Lennard-Jones with electrostatic term (12-6-1 potentials) were employed to describe the solute-solvent interactions. The Morokuma decomposition scheme of ab initio interaction energies at the SCF level and the ESIE charges on the solute atoms were used to reproduce the exchange and Coulomb electrostatic contributions of the solute-water interaction potential. Some extensions, such as including the dispersion component evaluated at MP2 level, were added to the traditional calculation procedures in order to improve the results of the solvation enthalpy. The results obtained with the EX-DIS-ES model were compared with the experimental calorimetry values, the observed agreement being acceptable

  15. Enthalpy of Vaporization by Gas Chromatography: A Physical Chemistry Experiment

    Science.gov (United States)

    Ellison, Herbert R.

    2005-01-01

    An experiment is conducted to measure the enthalpy of vaporization of volatile compounds like methylene chloride, carbon tetrachloride, and others by using gas chromatography. This physical property was measured using a very tiny quantity of sample revealing that it is possible to measure the enthalpies of two or more compounds at the same time.

  16. Aerosol volatility and enthalpy of sublimation of carboxylic acids.

    Science.gov (United States)

    Salo, Kent; Jonsson, Asa M; Andersson, Patrik U; Hallquist, Mattias

    2010-04-08

    The enthalpy of sublimation has been determined for nine carboxylic acids, two cyclic (pinonic and pinic acid) and seven straight-chain dicarboxylic acids (C(4) to C(10)). The enthalpy of sublimation was determined from volatility measurements of nano aerosol particles using a volatility tandem differential mobility analyzer (VTDMA) set-up. Compared to the previous use of a VTDMA, this novel method gives enthalpy of sublimation determined over an extended temperature range (DeltaT approximately 40 K). The determined enthalpy of sublimation for the straight-chain dicarboxylic acids ranged from 96 to 161 kJ mol(-1), and the calculated vapor pressures at 298 K are in the range of 10(-6)-10(-3) Pa. These values indicate that dicarboxylic acids can take part in gas-to-particle partitioning at ambient conditions and may contribute to atmospheric nucleation, even though homogeneous nucleation is unlikely. To obtain consistent results, some experimental complications in producing nanosized crystalline aerosol particles were addressed. It was demonstrated that pinonic acid "used as received" needed a further purification step before being suspended as a nanoparticle aerosol. Furthermore, it was noted from distinct differences in thermal properties that aerosols generated from pimelic acid solutions gave two types of particles. These two types were attributed to crystalline and amorphous configurations, and based on measured thermal properties, the enthalpy of vaporization was 127 kJ mol(-1) and that of sublimation was 161 kJ mol(-1). This paper describes a new method that is complementary to other similar methods and provides an extension of existing experimental data on physical properties of atmospherically relevant compounds.

  17. Enthalpy and void distributions in subchannels of PHWR fuel bundles

    Energy Technology Data Exchange (ETDEWEB)

    Park, J W; Choi, H; Rhee, B W [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1999-12-31

    Two different types of the CANDU fuel bundles have been modeled for the ASSERT-IV code subchannel analysis. From calculated values of mixture enthalpy and void fraction distribution in the fuel bundles, it is found that net buoyancy effect is pronounced in the central region of the DUPIC fuel bundle when compared with the standard CANDU fuel bundle. It is also found that the central region of the DUPIC fuel bundle can be cooled more efficiently than that of the standard fuel bundle. From the calculated mixture enthalpy distribution at the exit of the fuel channel, it is found that the mixture enthalpy and void fraction can be highest in the peripheral region of the DUPIC fuel bundle. On the other hand, the enthalpy and the void fraction were found to be highest in the central region of the standard CANDU fuel bundle at the exit of the fuel channel. This study shows that the subchannel analysis is very useful in assessing thermal behavior of the fuel bundle that could be used in CANDU reactors. 10 refs., 4 figs., 2 tabs. (Author)

  18. Enthalpy and void distributions in subchannels of PHWR fuel bundles

    Energy Technology Data Exchange (ETDEWEB)

    Park, J. W.; Choi, H.; Rhee, B. W. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    Two different types of the CANDU fuel bundles have been modeled for the ASSERT-IV code subchannel analysis. From calculated values of mixture enthalpy and void fraction distribution in the fuel bundles, it is found that net buoyancy effect is pronounced in the central region of the DUPIC fuel bundle when compared with the standard CANDU fuel bundle. It is also found that the central region of the DUPIC fuel bundle can be cooled more efficiently than that of the standard fuel bundle. From the calculated mixture enthalpy distribution at the exit of the fuel channel, it is found that the mixture enthalpy and void fraction can be highest in the peripheral region of the DUPIC fuel bundle. On the other hand, the enthalpy and the void fraction were found to be highest in the central region of the standard CANDU fuel bundle at the exit of the fuel channel. This study shows that the subchannel analysis is very useful in assessing thermal behavior of the fuel bundle that could be used in CANDU reactors. 10 refs., 4 figs., 2 tabs. (Author)

  19. Vapour pressure and enthalpy of vaporization of aliphatic poly-amines

    International Nuclear Information System (INIS)

    Efimova, Anastasia A.; Emel'yanenko, Vladimir N.; Verevkin, Sergey P.; Chernyak, Yury

    2010-01-01

    Molar enthalpies of vaporization of aliphatic poly-amines: 1,4-dimethylpiperazine [106-58-1], 1-(2-aminoethyl)-piperazine, [140-31-8], 1-(2-aminoethyl)-4-methyl-piperazine [934-98-5], and triethylenetetramine [112-24-3] were obtained from the temperature dependence of the vapour pressure measured by the transpiration method. A large number of the primary experimental results on temperature dependences of vapour pressures of the parent compounds have been collected from the literature and have been treated uniformly in order to derive vaporization enthalpies of poly-amines at the reference temperature 298.15 K. An internal consistency check was performed on enthalpy of vaporization values for poly-amines studied in this work.

  20. The excess enthalpies of liquid Ge-Pb-Te alloys

    International Nuclear Information System (INIS)

    Blachnik, R.; Binder, J.; Schlieper, A.

    1997-01-01

    The excess enthalpies of liquid alloys in the ternary system Ge-Pb-Te were determined at 1210 K in a heat flow calorimeter for five sections Ge y Pb 1-y -Te with y = 0.2, 0.4, 0.5, 0.6 and 0.8 and at 1153 K for Ge 0.5 Pb 0.5 -Te. The enthalpy surface in the ternary system is determined by a valley of exothermic minima, stretching from an exothermic minimum at the composition GeTe to one at the composition PbTe in the respective binaries. The excess enthalpies in the limiting metallic binary were adapted with the Redlich-Kister formalism. For the description of the thermodynamic functions in the ternary system the equation of Bonnier was taken using ternary coefficients. The calculated curves are in good agreement with the experimental data. (orig.)

  1. Enthalpy of sublimation/vaporization of trans-cyclohexyl-1,4-diamine and cis-cyclohexyl-1,2-diamine

    International Nuclear Information System (INIS)

    Tome, Luciana I.N.; Rosado, Mario T.S.; Nunes, Sandra C.C.; Maria, Teresa M.R.; Canotilho, Joao; Eusebio, M. Ermelinda S.

    2007-01-01

    The molar enthalpy of sublimation, Δ cr g H m 0 , of trans-cyclohexyl-1,4-diamine and the molar enthalpy of vaporization, Δ l g H m 0 , of cis-cyclohexyl-1,2-diamine, at the temperature 298.15 K, were determined by calorimetry. Δ cr g H m 0 (T=298.15K)=(105.0±0.8)kJ.mol -1 was obtained for the trans-isomer and Δ l g H m 0 (T=298.15K)=(62.2±1.0)kJ.mol -1 for the cis form. The molar enthalpy of fusion of the first compound, at T = 342.1 K, was determined by differential scanning calorimetry. The molar enthalpy of vaporization of the 1,4-isomer was estimated by combining the value of the enthalpy of sublimation with that of the enthalpy of fusion. The values obtained for molar standard enthalpy of vaporization and those available for the enthalpy of the diamines in the gas state were used to calculate the difference between the enthalpies of both compounds in the liquid state

  2. Enthalpy estimation for thermal comfort and energy saving in air conditioning system

    International Nuclear Information System (INIS)

    Chu, C.-M.; Jong, T.-L.

    2008-01-01

    The thermal comfort control of a room must consider not only the thermal comfort level but also energy saving. This paper proposes an enthalpy estimation that is conducive for thermal comfort control and energy saving. The least enthalpy estimator (LEE) combines the concept of human thermal comfort with the theory of enthalpy to predict the load for a suitable setting pair in order to maintain more precisely the thermal comfort level and save energy in the air conditioning system

  3. Enthalpy of formation of zircon

    International Nuclear Information System (INIS)

    Ellison, A.J.G.; Navrotsky, A.

    1992-01-01

    Using high-temperature solution calorimetry in molt 2PbO · B 2 O 3 , the enthalpy of reaction of the formation of zircon, ZrSiO 4 , from its constituent oxides has been determined: Δ 4 H 977 (ZrSiO 4 ) = -27.9 (±1.9) kJ/mol. With previously reported data for the heat contents of ZrO 2 SiO 2 and ZrSiO 4 and standard-state enthalpies of formation of ZrO 2 and SiO 2 , we obtain Δ f H 298 degrees. (ZrSiO 4 ) = -2034.2 (±3.1) kJ/mol and Δ t G 298 degrees (ZrSiO 4 ) = -1919.8 kJ/mol. The free energy value is in excellent agreement with a range previously estimated from solid-state reaction equilibria. At higher temperature also the data are in close agreement with existing data, though the data sets diverge somewhat with increasing T. In this paper the limitations of the data for predicting the breakdown temperature of zircon into its constituent oxides are discussed

  4. Excess molar enthalpies of binary systems containing 2-octanone, hexanoic acid, or octanoic acid at T = 298.15 K

    International Nuclear Information System (INIS)

    Liao, Wei-Chen; Lin, Ho-mu; Lee, Ming-Jer

    2012-01-01

    Highlights: → An isothermal titration calorimeter was used for enthalpy data measurement. → The investigated binary systems contain 2-octanone, hexanoic acid, or octanoic acid. → The excess enthalpies are all positive except for mixtures containing DMSO and DMF. → The Peng-Robinson equation with two parameters yielded the best representation. - Abstract: An isothermal titration calorimeter was used to measure the excess molar enthalpies (H E ) of six binary systems at T = 298.15 K under atmospheric pressure. The systems investigated include (1-hexanol + 2-octanone), (1-octanol + 2-octanone), (1-hexanol + octanoic acid), (1-hexanol + hexanoic acid), {N,N-dimethylformamide (DMF) + hexanoic acid}, and {dimethyl sulfoxide (DMSO) + hexanoic acid}. The values of excess molar enthalpies are all positive except for the DMSO- and the DMF-containing systems. In the 1-hexanol with hexanoic acid or octanoic acid systems, the maximum values of H E are located around the mole fraction of 0.4 of 1-hexanol, but the H E vary nearly symmetrically with composition for other four systems. In addition to the modified Redlich-Kister and the NRTL models, the Peng-Robinson (PR) and the Patel-Teja (PT) equations of state were used to correlate the excess molar enthalpy data. The modified Redlich-Kister equation correlates the H E data to within about experimental uncertainty. The calculated results from the PR and the PT are comparable. It is indicated that the overall average absolute relative deviations (AARD) of the excess enthalpy calculations are reduced from 18.8% and 18.8% to 6.6% and 7.0%, respectively, as the second adjustable binary interaction parameter, k bij , is added in the PR and the PT equations. Also, the NRTL model correlates the H E data to an overall AARD of 10.8% by using two adjustable model parameters.

  5. Ionic liquids: differential scanning calorimetry as a new indirect method for determination of vaporization enthalpies.

    Science.gov (United States)

    Verevkin, Sergey P; Emel'yanenko, Vladimir N; Zaitsau, Dzmitry H; Ralys, Ricardas V; Schick, Christoph

    2012-04-12

    Differential scanning calorimetry (DSC) has been used to measure enthalpies of synthesis reactions of the 1-alkyl-3-methylimidazolium bromide [C(n)mim][Br] ionic liquids from 1-methylimidazole and n-alkyl bromides (with n = 4, 5, 6, 7, and 8). The optimal experimental conditions have been elaborated. Enthalpies of formation of these ionic liquids in the liquid state have been determined using the DSC results according to the Hess Law. The ideal-gas enthalpies of formation of [C(n)mim][Br] were calculated using the methods of quantum chemistry. They were used together with the DSC results to derive indirectly the enthalpies of vaporization of the ionic liquids under study. In order to validate the indirect determination, the experimental vaporization enthalpy of [C(4)mim][Br] was measured by using a quartz crystal microbalance (QCM). The combination of reaction enthalpy measurements by DSC with modern high-level first-principles calculations opens valuable indirect thermochemical options to obtain values of vaporization enthalpies of ionic liquids.

  6. Excess molar enthalpies and volumes of binary mixtures of two hydrofluoroethers with hexane, or benzene, or ethanol, or 1-propanol, or 2-butanone at T=298.15 K

    International Nuclear Information System (INIS)

    Ogawa, Hideo; Karashima, Shinya; Takigawa, Takayo; Murakami, Sachio

    2003-01-01

    Excess molar enthalpies and volumes at T=298.15 K are reported for binary mixtures of {1,1,2,3,3,3-hexafluoro-1-methoxypropane (HFE-356mec), [CF 3 CHFCF 2 -O-CH 3 ], or 1,1,2,2-tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (HFE-347pc-f) [CHF 2 CF 2 -O-CH 2 CF 3 ] + hexane (Hx), or benzene (Bz), or ethanol (EtOH), or 1-propanol (PrOH), or 2-butanone (MEK)}. The results of excess molar enthalpies are endothermic over the whole range of concentration, except for the MEK systems, in which excess molar enthalpies are exothermic over the whole range of concentration, and the EtOH systems, in which they are exothermic in the smaller mole fraction range. On the other hand, excess molar volumes are positive over the whole concentration range for all the mixtures. The values of the excess molar enthalpies for the (HFE-347pc-f + Hx) system show the linear composition dependence in the range of ca. 0.3< x<0.7, suggesting the quasi-stable state in solution. The results are explained by means of the destruction of the dipolar interactions and hydrogen bond in the pure component liquids, the difference of the dispersion interactions between the pure component liquid and solution, and the formation of the intermolecular hydrogen bond and dipolar interaction between unlike molecules

  7. Standard molar enthalpies of formation of three methyl-pyrazole derivatives

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Cabral, Joana I.T.A.

    2012-01-01

    Highlights: ► Combustion calorimetry was used to determine Δ f H m ∘ (cr) of methyl-pyrazole derivatives. ► Vapour pressures were determined by the Knudsen mass-loss effusion technique. ► Gas-phase Δ f H m ∘ of the studied compounds have been derived. - Abstract: The standard (p ° = 0.1 MPa) molar enthalpies of formation of the crystalline 3-methyl-1-pyrazolecarboxamide; 3-methyl-3-pyrazoline-5-one; and 4-methyl-2-pyrazoline-5-one were derived from the standard massic energies of combustion, in oxygen, to yield CO 2 (g), H 2 O (l) and N 2 (g), at T = 298.15 K, measured by static bomb combustion calorimetry. The standard molar enthalpies of sublimation were calculated from the variation of the vapour pressures of each compound with temperature, measured by the Knudsen effusion technique. These two thermodynamic parameters yielded the standard molar enthalpies of formation of the pyrazole derivatives, in the gaseous phase, at T = 298.15 K. The derived standard molar enthalpies of formation, in gaseous state, are analyzed in terms of enthalpic increments and interpreted in terms of molecular structure.

  8. Phase Transition Enthalpy Measurements of Organic and Organometallic Compounds and Ionic Liquids. Sublimation, Vaporization, and Fusion Enthalpies from 1880 to 2015. Part 2. C11-C192

    Science.gov (United States)

    Acree, William; Chickos, James S.

    2017-03-01

    The second part of this compendium concludes with a collection of phase change enthalpies of organic molecules inclusive of C11-C192 reported over the period 1880-2015. Also included are phase change enthalpies including fusion, vaporization, and sublimation enthalpies for organometallic, ionic liquids, and a few inorganic compounds. Paper I of this compendium, published separately, includes organic compounds from C1 to C10 and describes a group additivity method for evaluating solid, liquid, and gas phase heat capacities as well as temperature adjustments of phase changes. Paper II of this compendium also includes an updated version of a group additivity method for evaluating total phase change entropies which together with the fusion temperature can be useful in estimating total phase change enthalpies. Other uses include application in identifying potential substances that either form liquid or plastic crystals or exhibit additional phase changes such as undetected solid-solid transitions or behave anisotropically in the liquid state.

  9. Specification and comparative calculation of enthalpies and Gibbs formation energies of anhydrous lanthanide nitrates

    International Nuclear Information System (INIS)

    Del' Pino, Kh.; Chukurov, P.M.; Drakin, S.I.

    1980-01-01

    Analyzed are the results of experimental depermination of formation enthalpies of waterless nitrates of lanthane cerium, praseodymium, neodymium and samarium. Using method of comparative calculation computed are enthalpies of formation of waterless lanthanide and yttrium nitrates. Calculated values of enthalpies and Gibbs energies of waterless lanthanide nitrate formation are tabulated

  10. Effects of electric fields in polymerization on enthalpy of PMAA anhydridization

    Energy Technology Data Exchange (ETDEWEB)

    Chang Zhenqi; Liu Gang; Zhang Zhicheng

    2004-02-19

    PMAA (polymethacrylic acid) polymerized by {gamma}-irradiation in electric field forms six-membered cyclic anhydride during heating process and the enthalpy of PMAA anhydridization was determined by DSC. Why the endothermic peak of PMAA anhydridization in DSC curve between 200 and 300 deg. C appears is particularly explained by calculation. The relations between applied electric field and the enthalpy of PMAA anhydridization are studied. The results show that, with the increases of the intensity of electric field in polymerization, the enthalpy of PMAA forming anhydrides nonlinearly increase, which might be related to orientation of carboxylic acid groups of the PMAA in an electric field.

  11. Standard molar enthalpies of formation of 2-furancarbonitrile, 2-acetylfuran, and 3-furaldehyde

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Amaral, Luisa M.P.F.

    2009-01-01

    The standard (p 0 = 0.1 MPa) molar energies of combustion of 2-furancarbonitrile, 2-acetylfuran, and 3-furaldehyde were measured by static bomb combustion calorimetry; the Calvet high-temperature microcalorimetry was used to measure the enthalpies of vaporization of these liquid compounds. The standard molar enthalpies of formation of the three compounds, in the gaseous phase, at T = 298.15 K, have been derived from the corresponding standard molar enthalpies of formation in the liquid phase and the standard molar enthalpies of phase transition, as (106.8 ± 1.1) kJ . mol -1 , -(207.4 ± 1.3) kJ . mol -1 , and -(151.9 ± 1.1) kJ . mol -1 , for 2-furancarbonitrile, 2-acetylfuran, and 3-furaldehyde, respectively. Standard molar enthalpies of formation are discussed in terms of the isomerization ortho meta. Enthalpic increment values of the introduction of the functional groups -CN, -CHO, and -COCH 3 were also compared with some other heterocycles; i.e. thiophene and pyridine

  12. Formation enthalpies of Al–Fe–Zr–Nd system calculated by using geometric and Miedema's models

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei [Department of Mathematics and Information Science, Guangxi College of Education, Nanning 530023 (China); Wang, Rongcheng; Tao, Xiaoma; Guo, Hui; Chen, Hongmei [College of Physical Science and Technology, Guangxi University, Nanning 530004 (China); Ouyang, Yifang, E-mail: ouyangyf@gxu.edu.cn [College of Physical Science and Technology, Guangxi University, Nanning 530004 (China)

    2015-04-15

    Formation enthalpy is important for the phase stability and amorphous forming ability of alloys. The formation enthalpies of Fe{sub 17}RE{sub 2} (RE=Ce, Pr, Nd, Gd and Er) obtained by Miedema's theory are in good agreement with those of the experiments. The dependence of formation enthalpy on concentration of Al for intermetallic (Al{sub x}Fe{sub 1−x}){sub 17}Nd{sub 2} have been calculated by Miedema's theory and the geometric model. The solid solubility of Al in (Al{sub x}Fe{sub 1−x}){sub 17}Nd{sub 2} is coincident with the concentration dependence of formation enthalpy. The mixing enthalpies of liquid alloys and formation enthalpies of alloys for Al–Fe–Zr–Nd system have been predicted. The calculated mixing enthalpy indicates that the adding of Fe or Nd decreases monotonously the magnitude of enthalpy. The formation enthalpies of Al–Fe–Zr–Nd system indicate that the shape of the enthalpy contour map changes when the content of Al is less than 50.0 at% and then it remains unchanged except the decrease of magnitude. The formation enthalpy of Al–Fe–Zr–Nd increases with the increase of Fe and/or Nd content. The negative formation enthalpy indicates that Al–Fe–Zr–Nd system has higher amorphous forming ability and wide amorphous forming range. The certain contents of Zr and/or Al are beneficial for the formation of Al–Fe–Zr–Nd intermetallics.

  13. High-temperature enthalpies of plutonium monocarbide and plutonium sesquicarbide

    International Nuclear Information System (INIS)

    Oetting, F.L.

    1979-01-01

    The high-temperature enthalpies of plutonium monocarbide and plutonium sesquicarbide have been determined with a copper-block calorimeter of the isoperibol type. The experimental enthalpy data, which was measured relative to 298 K, covered the temperature range from 400 to 1500 K. The calculation of the temperature rise of the calorimeter takes into account the added heat evolution from the radioactive decay of the plutonium samples. These enthalpy results, combined with the heat capacity and entropy of the respective carbide at 298 K available from the literature, has made it possible to generate tables of thermodynamic functions for the plutonium carbides. The behavior of the heat capacity of both of the plutonium carbides, i.e., a relatively steep increase in the heat capacity as the temperature increases, may be attributed to a premelting effect with the formation of vacancies within the crystal lattice although a theoretical treatment of this phenomenon is not given

  14. Determination of melting and solidification enthalpy of hypereutectic silumins

    Directory of Open Access Journals (Sweden)

    J. Piątkowski

    2008-04-01

    Full Text Available The study was related with determination of the values of enthalpy of melting and solidification of hypereutectic AlSi18, AlSi21 and AlSi24 silumins modified with phosphorus in the form of Cu-P. The calorimetry, preceded by thermal analysis and derivative thermal analysis (TA and DTA, respectively was carried out on a high-temperature scanning calorimeter, model MHTC-96, made by SETARAM, applying the method of direct determination of parameters of the high-temperature process, and in particular of the enthalpy of phase transformations. Modern control and measuring instruments coupled with PC computer provide a very precise tool for determination of these transformations. An additional advantage was development of appropriate software called „SETSOFT”, owing to which it was possible to determine in an easy way the enthalpy of the investigated phase transformations. Moreover, an additional thermal effect, related most probably with pre-eutectic crystallization of primary silicon, was observed and confirmed by calorimetric examinations.

  15. A correct enthalpy relationship as thermal comfort index for livestock.

    Science.gov (United States)

    Rodrigues, Valéria Cristina; da Silva, Iran José Oliveira; Vieira, Frederico Márcio Corrêa; Nascimento, Sheila Tavares

    2011-05-01

    Researchers working with thermal comfort have been using enthalpy to measure thermal energy inside rural facilities, establishing indicator values for many situations of thermal comfort and heat stress. This variable turned out to be helpful in analyzing thermal exchange in livestock systems. The animals are exposed to an environment which is decisive for the thermoregulatory process, and, consequently, the reactions reflect states of thermal comfort or heat stress, the last being responsable for problems of sanity, behavior and productivity. There are researchers using enthalpy as a qualitative indicator of thermal environment of livestock such as poultry, cattle and hogs in tropical regions. This preliminary work intends to check different enthalpy equations using information from classical thermodynamics, and proposes a direct equation as thermal comfort index for livestock systems.

  16. Energetic and binding properties of DNA upon interaction with dodecyl trimethylammonium bromide.

    Science.gov (United States)

    Bathaie, S Z; Moosavi-Movahedi, A A; Saboury, A A

    1999-02-15

    The interaction of dodecyl trimethylammonium bromide (DTAB), a cationic surfactant, with calf thymus DNA has been studied by various methods, including potentiometric technique using DTAB-selective plastic membrane electrode at 27 and 37 degreesC, isothermal titration microcalorimetry and UV spectrophotometry at 27 degreesC using 0.05 M Tris buffer and 0.01 M NaCl at pH 7.4. The free energy is calculated from binding isotherms on the basis of Wyman binding potential theory and the enthalpy of binding according to van't Hoff relation. The enthalpy of unfolding has been determined by subtraction of the enthalpy of binding from the microcalorimetric enthalpy. The results show that, after the interaction of first DTAB molecule to DNA (base molarity) through the electrostatic interaction, the second DTAB molecule also binds to DNA through electrostatic interaction. At this stage, the predom-inant DNA conformational change occurs. Afterwards up to 20 DTAB molecules, below the critical micelle concentration of DTAB, bind through hydrophobic interactions.

  17. Formation enthalpy of NiBe and Ni5Be21

    International Nuclear Information System (INIS)

    Ivanov, M.I.; Karpova, T.F.; Dalago, N.Yu.

    1981-01-01

    The method of dissolution calorimetry is used to determine standard enthalpies of NiBe and Ni 5 Be 21 formation, which are 84.8+-2.2 and (-669+-37)kJ/mol. The enthalpy values of NiBe and Ni 5 Be 21 at 331 K are shown to coincide (within the limits of errors of these values) with the values at the standard temperature of 298.15 K [ru

  18. Experimental investigation of the enthalpy and mass flow distribution between subchannels in a BWR cluster geometry (PELCO-S)

    International Nuclear Information System (INIS)

    Herkenrath, H.; Hufschmidt, W.

    1979-01-01

    Experiments based on the subchannel isokinetic technique have been carried out at the JRC of the European Community at Ispra, using a purposely designed 16-rod test section, simulating in a rather accurate way a typical BWR geometry. The adopted system allows the simultaneous determination of mass flow and enthalpy, at the end of the bundle active length, in four characteristic subchannels of the 16-rod lattice. The results show some pronounced flow and enthalpy variations within the bundle, not accurately taken into account by current subchannel codes, such as COBRA-3C. In particular low values both in mass flow and enthalpy have been found in corner subchannel, in disagreement with code predictions, but confirming previous General Electric experiments carried out in a 9-rod test section. This report deals only with the experimental procedure and the results

  19. Enthalpy of sublimation/vaporization of trans-cyclohexyl-1,4-diamine and cis-cyclohexyl-1,2-diamine

    OpenAIRE

    Tomé, Luciana I. N.; Rosado, Mário T. S.; Nunes, Sandra C. C.; Maria, Teresa M. R.; Canotilho, João; Eusébio, M. Ermelinda S.

    2007-01-01

    The molar enthalpy of sublimation, , of trans-cyclohexyl-1,4-diamine and the molar enthalpy of vaporization, , of cis-cyclohexyl-1,2-diamine, at the temperature 298.15 K, were determined by calorimetry. was obtained for the trans-isomer and for the cis form. The molar enthalpy of fusion of the first compound, at T = 342.1 K, was determined by differential scanning calorimetry. The molar enthalpy of vaporization of the 1,4-isomer was estimated by combining the value of the enthalpy of sublimat...

  20. Enthalpies of formation of dihydroxybenzenes revisited: Combining experimental and high-level ab initio data

    International Nuclear Information System (INIS)

    Gonçalves, Elsa M.; Agapito, Filipe; Almeida, Tânia S.; Martinho Simões, José A.

    2014-01-01

    Highlights: • Thermochemistry of hydroxyphenols probed by experimental and theoretical methods. • A new paradigm for obtaining enthalpies of formation of crystalline compounds. • High-level ab initio results for the thermochemistry of gas-phase hydroxyphenols. • Sublimation enthalpies of hydroxyphenols determined by Calvet microcalorimetry. - Abstract: Accurate values of standard molar enthalpies of formation in condensed phases can be obtained by combining high-level quantum chemistry calculations of gas-phase enthalpies of formation with experimentally determined enthalpies of sublimation or vapourization. The procedure is illustrated for catechol, resorcinol, and hydroquinone. Using W1-F12, the gas-phase enthalpies of formation of these compounds at T = 298.15 K were computed as (−270.6, −269.4, and −261.0) kJ · mol −1 , respectively, with an uncertainty of ∼0.4 kJ · mol −1 . Using well characterised solid samples, the enthalpies of sublimation were determined with a Calvet microcalorimeter, leading to the following values at T = 298.15 K: (88.3 ± 0.3) kJ · mol −1 , (99.7 ± 0.4) kJ · mol −1 , and (102.0 ± 0.9) kJ · mol −1 , respectively. It is shown that these results are consistent with the crystalline structures of the compounds

  1. Vaporization thermodynamics and enthalpy of formation of aluminum silicon carbide

    International Nuclear Information System (INIS)

    Behrens, R.G.; Rinehart, G.H.

    1984-01-01

    The vaporization thermodynamics of aluminum silicon carbide was investigated using Knudsen effusion mass spectrometry. Vaporization occurred incongruently to give Al(g), SiC(s), and graphite as reaction products. The vapor pressure of aluminum above (Al 4 SiC 4 + SiC + C) was measured using graphite effusion cells with orifice areas between 1.1 X 10 -2 and 3.9 X 10 -4 cm 2 . The vapor pressure of aluminum obtained between 1427 and 1784 K using an effusion cell with the smallest orifice area, 3.9 X 10 -4 cm 2 , is expressed as log p (Pa) = - (18567 + or - 86) (K/T) + (12.143 + or - 0.054) The third-law calculation of the enthalpy change for the reaction Al 4 SiC 4 (s) = 4Al(g) + SiC(hex) + 3C(s) using the present aluminum pressures gives ΔH 0 (298.15 K) = (1455 + or - 79) kJ /SUP ./ mol -1 . The corresponding second-law result is ΔH 0 (298.15 K) = (1456 + or - 47) kJ /SUP ./ mol -1 . The standard enthalpy of formation of Al 4 SiC 4 (s) from the elements calculated from the present vaporization enthalpy (third-law calculation) and the enthalpies of formation of Al(g) and hexagonal SiC is ΔH 0 /SUB f/ (298.15 K) = -(221 + or - 85) kJ /SUP ./ mol -1 . The standard enthalpy of formation of Al 4 SiC 4 (s) from its constituent carbides Al 4 C 3 (s) and SiC(c, hex) is calculated to be ΔH 0 (298.15 K) = (38 + or - 92) KJ /SUP ./ mol -1

  2. Experimental standard molar enthalpies of formation of some methylbenzenediol isomers

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Lobo Ferreira, Ana I.M.C.

    2009-01-01

    The present work is part of a research program on the energetics of formation of alkyl substituted benzenediols, aiming the study of the enthalpic effect of the introduction of methyl substituents into benzenediols. In this work we present the results of the thermochemical research on 2-methylresorcinol, 3-methylresorcinol, 4-methylresorcinol, and methylhydroquinone. The standard (p 0 =0.1MPa) molar enthalpies of formation, in the crystalline phase, at T = 298.15 K, of the compounds mentioned above were derived from their standard massic energies of combustion, measured by static-bomb combustion calorimetry, while the standard molar enthalpies of sublimation of those compounds were obtained by the temperature dependence of their vapour pressures determined by the Knudsen effusion technique. From experimental values, the standard molar enthalpies of formation of the studied methylbenzenediols in the gaseous phase, at T = 298.15 K were then derived. The results are interpreted in terms of structural contributions to the energetics of the substituted benzenediols and compared with the same parameters estimated from the Cox Scheme. Moreover, the standard (p 0 =0.1MPa) molar enthalpies, entropies, and Gibbs energies of sublimation, at T = 298.15 K, were derived for the four isomers of methylbenzenediols.

  3. Effect of Calcium chloride and Cadmium chloride on the enthalpy of ...

    African Journals Online (AJOL)

    This paper presents the effect of two dissolved inorganic salts, CaCl2 and CdCl2 on the enthalpy of mixing of the binary 1,4 dioxane + water system has been investigated at 303.15 K in an isothermal displacement calorimeter with vapour space. A significantly increasing trend in the endothermic excess enthalpy values for ...

  4. Vapour pressures and enthalpies of vaporization of a series of the ferrocene derivatives

    International Nuclear Information System (INIS)

    Emel'yanenko, Vladimir N.; Verevkin, Sergey P.; Krol, Olesya V.; Varushchenko, Raisa M.; Chelovskaya, Nelly V.

    2007-01-01

    Vapour pressures of the ferrocene, ferrocene-methanol, benzyl-ferrocene, and benzoyl-ferrocene have been determined by the transpiration method. The molar enthalpies of sublimation Δ cr g H m and of vaporization Δ l g H m have been determined from the temperature dependence of the vapour pressure. The molar enthalpies of fusion of these compounds were measured by d.s.c. The measured data sets of vaporization, sublimation, and fusion enthalpies were checked for internal consistency

  5. Enthalpies of formation of UAl1 and UAl3 by calorimetry

    International Nuclear Information System (INIS)

    Nagarajan, K.; Babu, R.; Mathews, C.K.

    1993-01-01

    Enthalpies of formation of the intermetallic compounds UAl 4 and UAl 3 at 298.15 K were determined by high temperature solution calorimetry in which liquid aluminium was used as the solvent. The thermal effects of dissolution of UAl 4 , UAl 3 and U in liquid aluminium were measured in separate experiments by dropping the samples held at the ambient temperature into liquid aluminium maintained at 980 K in the calorimeter. The thermal effects of dissolution of these samples at infinite dilution in liquid aluminium were derived from these measurements and based on this data the enthalpies of formation of UAl 4 and UAl 3 at 298.15 K were computed. The values obtained are ΔH f,298.15 (UAl 4 )=-126.5±13.3 kJ mol -1 and ΔH f,298.15 (UAl 3 )=-118.1±8.2 kJ mol -1 . The integral enthalpies of formation of U-Al alloys at 978 K, 1078 K and 1094 K were measured by dropping U samples maintained at the ambient temperature into liquid aluminium in the calorimeter at the experimental temperature. From the integral enthalpies of formation of U-Al alloys in the two phase regions, {U-Al}+ 4 > and {U-Al}+ 3 >, the enthalpies of formation of UAl 4 and UAl 3 , respectively, at the temperatures of measurement were derived. These results are discussed in comparison with the literature data. (orig.)

  6. Calorimetric determination of the enthalpy of 1-butyl-3-methylimidazolium bromide synthesis: a key quantity in thermodynamics of ionic liquids.

    Science.gov (United States)

    Paulechka, Yauheni U; Kabo, Andrey G; Blokhin, Andrey V

    2009-11-05

    The enthalpy of the 1-butyl-3-methylimidazolium bromide [C(4)mim]Br ionic liquid synthesis reaction 1-methylimidazole (liq) + 1-bromobutane (liq) --> [C(4)mim]Br (liq) was determined in a homemade small-volume isoperibol calorimeter to be Delta(r)H degrees (298) = -87.7 +/- 1.6 kJ x mol(-1). The activation energy for this reaction in a homogeneous system E(A) = 73 +/- 4 kJ x mol(-1) was found from the results of calorimetric measurements. The formation enthalpies for the crystalline and liquid [C(4)mim]Br were determined from the calorimetric data: Delta(f)H degrees (298)(cr) = -178 +/- 5 kJ x mol(-1) and Delta(f)H degrees (298)(liq) = -158 +/- 5 kJ x mol(-1). The ideal-gas formation enthalpy of this compound Delta(f)H degrees (298)(g) = 16 +/- 7 kJ x mol(-1) was calculated using the methods of quantum chemistry and statistical thermodynamics. The vaporization enthalpy of [C(4)mim]Br, Delta(vap)H degrees (298) = 174 +/- 9 kJ x mol(-1), was estimated from the experimental and calculated formation enthalpies. It was demonstrated that vapor pressure of this ionic liquid cannot be experimentally determined.

  7. Determination of the immersion enthalpy of activated carbon in aqueous solutions of phenol and its relation with the adsorption capacity

    International Nuclear Information System (INIS)

    Giraldo G, Liliana; Moreno P, Juan Carlos

    2002-01-01

    The immersion enthalpy for commercial micro-porous activated carbon is determined at 298 k in aqueous solutions of phenol in a concentration range from 10 to 100 mg. L 1 , without ph control; values are obtained between 15 and 36 J.g-l. The quantity of phenol adsorbed is determined in the same range of concentrations and the quantity adsorbed in the monolayer is calculated of 164 mg.g-1. The relationship is established down between the immersion heat and the quantity of phenol adsorbed and a bigger change is detected for the immersion heat in the intermediate region of the studied concentration range

  8. Standard molar enthalpies of formation of sodium alkoxides

    International Nuclear Information System (INIS)

    Chandran, K.; Srinivasan, T.G.; Gopalan, A.; Ganesan, V.

    2007-01-01

    The molar enthalpies of solution of sodium in methanol, ethanol, and n-propanol and of sodium alkoxides in their corresponding alcohols were measured at T=298.15K using an isoperibol solution calorimeter. From these results and other auxiliary data, the standard molar enthalpies of formation, Δ f H m o (RONa,cr) of sodium methoxide, sodium ethoxide, and sodium n-propoxide were calculated and found to be {(-366.21+/-1.38) (-413.39+/-1.45), and (-441.57+/-1.18)}kJ.mol -1 , respectively. A linear correlation has been found between Δ f H m o (RONa)andΔ f H m o (ROH) for R=n-alkyl, enabling the prediction of data for other sodium alkoxides

  9. Standard molar enthalpies of formation of 2-, 3-, and 4-piperidinomethanol isomers

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Cabral, Joana I.T.A.

    2006-01-01

    The standard (p o =0.1MPa) molar energies of combustion in oxygen of 2-piperidinemethanol, 3-piperidinemethanol, and 4-piperidinemethanol, all in the crystalline phase, were measured, at T=298.15K, by static bomb calorimetry. These values were used to derive the standard molar enthalpies of combustion and the standard molar enthalpies of formation, in the condensed phase, for these compounds. Further, the standard molar enthalpies of sublimation, at T=298.15K, of these three piperidinomethanol isomers were determined by Cavet microcalorimetry. The combustion calorimetry results together with those from the Calvet microcalorimetry, were used to derive the standard molar enthalpies of formation, at T=298.15K, in the gaseous phase, of the three piperidinemethanol studied. -Δ c H m o (cr)Δ cr g H m o kJ.mol -1 kJ.mol -1 2-Piperidinemethanol3890.70+/-0.9293.02+/-0.503- Piperidinemethanol3895.3+/-1.195.9+/-1.44-Piperidinemethanol3891.3+/- 1.198.31+/-0.69

  10. Experimental redetermination of the gas-phase enthalpy of formation of ethyl 2-thiophenecarboxylate

    International Nuclear Information System (INIS)

    Santos, Ana Filipa L.O.M.; Ribeiro da Silva, Manuel A.V.

    2013-01-01

    The condensed phase standard (p° = 0.1 MPa) molar enthalpy of formation of ethyl-2-thiophenecarboxylate was derived from the remeasured standard molar energy of combustion, in oxygen, at T = 298.15 K, by rotating bomb combustion calorimetry and the standard molar enthalpy of vaporization, at T = 298.15 K, remeasured by Calvet microcalorimetry. Combining these two values, the following enthalpy of formation in the gas phase, at T = 298.15 K, was then derived for ethyl-2-thiophenecarboxylate: −(277.7 ± 2.9) kJ · mol −1 . The calculated gas-phase enthalpy of formation of the title compound, through the G3(MP2)//B3LYP approach was found to be 278.9 kJ · mol −1 , in excellent agreement with the experimental measured value

  11. Interaction of a weak and a strong shock in reacting high enthalpy flow; Wechselwirkung einer starken und einer schwachen Stosswelle in reagierender Hochenthalpiestroemung

    Energy Technology Data Exchange (ETDEWEB)

    Schnieder, M.

    1998-11-01

    In the free piston driven shock tunnel HEG the interaction of shock waves in front of a blunt body is studied in reacting high enthalpy flow. The influence of high temperature effects is of interest. The so called type IV interaction produces a free jet that impinges onto the body and creates high pressure and heat loads on the body surface. A cylinder wedge model is used. At the cylinder surface pressure and heat flux are measured. Holographic interferometry and schlieren optic are applied to visualize the flow. The measured loads show unsteady behaviour. At higher Reynolds numbers the upper bow shock shows a strong disturbance. It is assumed that this disturbance is caused by an unstable shear layer if the convective Mach number (i.e. the Mach number of the flow relative to a frame of reference moving with the shear layer structures) is larger than one. A study of the influence of dissociation on the convective Mach number shows, that the convective Mach number increases. Numerical calculations and an analytical model, which is based on the ideal dissociating gas model and the Fay Riddell solution to stagnation point flows are discussed in comparison with the experiments. (orig.)

  12. Enthalpy of solution of potassium iodide in the water-formamide-dimethyl sulfoxide mixtures

    International Nuclear Information System (INIS)

    Belova, L.N.; Solov'ev, S.N.; Vorob'ev, A.F.

    1985-01-01

    Solution enthalpies are measured for potassium iodide in the water-formamide-dimethyl sulfoxide mixtures in a sealed oscillating calorimeter with an isothermal shell at a constant water molar fraction equal to 0.3; 0.5 and 0.7 at 298.15 K. A diagram of the dependence of solution enthalpies on the of mixed solvent composition is plotted. Deviations of experimental solution enthalpies from the calculated ones are negative over the entire concentration range studied, which testifies to the preferable solvatation of electrolyte by the formid and dimthyl sulfoxide molecules

  13. Experimental standard molar enthalpies of formation of some 4-alkoxybenzoic acids

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Lobo Ferreira, Ana I.M.C.; Maciel, Fabrice M.

    2010-01-01

    The present work is part of a research program on the energetics of the linear 4-n-alkoxybenzoic acids, aiming the study of the enthalpic effect of the introduction of an alkoxy chain in the position 4- of the benzoic acid ring. In this work, we present the results of the thermochemical research on 4-n-alkoxybenzoic acids with the alkoxy chain length n = 2, 4, and 8. The standard (p 0 =0.1MPa) molar enthalpy of formation of crystalline 4-ethoxybenzoic acid, 4-butoxybenzoic acid, and 4-(octyloxy)benzoic acid was measured, at T = 298.15 K, by static-bomb calorimetry. These values, combined with the values of standard molar enthalpies of sublimation, were used to derive the standard molar enthalpies of formation in the gaseous phase.

  14. Recommended sublimation pressure and enthalpy of benzene

    Czech Academy of Sciences Publication Activity Database

    Růžička, K.; Fulem, Michal; Červinka, C.

    2014-01-01

    Roč. 68, Jan (2014), s. 40-47 ISSN 0021-9614 Institutional support: RVO:68378271 Keywords : benzene * vapor pressure * heat capacity * ideal - gas thermodynamic properties * sublimation enthalpy * recommended vapor pressure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.679, year: 2014

  15. Enthalpy of vaporization and vapor pressure of whiskey lactone and menthalactone by correlation gas chromatography

    International Nuclear Information System (INIS)

    Simmons, Daniel; Chickos, James

    2017-01-01

    Highlights: • The vapor pressure and vaporization enthalpies of cis and trans-whiskey lactone have been evaluated. • Enthalpies of vaporization and vapor pressures of (+)-isomintlactone and (−)-mintlactone were also evaluated. • The sublimation enthalpy and corresponding vapor pressure of (+) -isomintlactone at T = 298.15 K is estimated. - Abstract: Enthalpies of vaporization at T = 298.15 K of cis and trans-whiskey lactone have been evaluated by correlation gas chromatography to be (68.4 ± 1.7) kJ·mol −1 and (67.5 ± 1.7) kJ·mol −1 , respectively. The enthalpies of vaporization of isomintlactone and mintlactone also evaluated by correlation gas chromatography have been found to have vaporization enthalpies of (74.2 ± 1.8) kJ·mol −1 and (73.2 ± 1.8) kJ·mol −1 respectively. The vapor pressures for cis and trans-whiskey lactone at T = 298.15 K have been evaluated as (1.5 ± 0.09) Pa and (2.0 ± 0.1) Pa using vapor pressures of a series of lactones as standards. Vapor pressures for isomintlactone and mintlactone were evaluated as (0.26 ± 0.012) Pa and (0.33 ± 0.02) Pa, respectively. Fusion and sublimation enthalpies for (+)-isomintlactone as well as the vapor pressure of the solid have been estimated.

  16. A molecular dynamics study of ambient and high pressure phases of silica: structure and enthalpy variation with molar volume.

    Science.gov (United States)

    Rajappa, Chitra; Sringeri, S Bhuvaneshwari; Subramanian, Yashonath; Gopalakrishnan, J

    2014-06-28

    Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, α-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar volume-for low and medium-density polymorphs, it is almost independent of volume, while for high-pressure phases a steep dependence is seen. A detailed analysis indicates that the increased short-range contributions to enthalpy in the high-density phases arise not only from an increased coordination number of silicon but also shorter Si-O bond lengths. Our results indicate that amorphous phases of silica exhibit better optimization of short-range interactions than crystalline phases at the same density while the magnitude of Coulombic contributions is lower in the amorphous phase.

  17. Enthalpy of mixing of liquid Cu-Fe-Hf alloys at 1873 K

    Energy Technology Data Exchange (ETDEWEB)

    Agraval, Pavel; Turchanin, Mikhail [Donbass State Engineering Academy, Kramatorsk (Ukraine). Metallurgical Dept.; Dreval, Liya [Donbass State Engineering Academy, Kramatorsk (Ukraine). Metallurgical Dept.; Materials Science International Services GmbH (MSI), Stuttgart (Germany)

    2016-12-15

    In the ternary Cu-Fe-Hf system, the mixing enthalpies of liquid alloys were investigated at 1873 K using a high-temperature isoperibolic calorimeter. The experiments were performed along the sections x{sub Cu}/x{sub Fe} = 3/1, 1/1 at x{sub Hf} = 0-0.47 and along the section x{sub Cu}/x{sub Fe} = 1/3 at x{sub Hf} = 0-0.13. The limiting partial enthalpies of mixing of undercooled liquid hafnium in liquid Cu-Fe alloys, Δ{sub mix} anti H{sub Hf}{sup ∞}, are (-122 ± 9) kJ mol{sup -1} (section x{sub Cu}/x{sub Fe} = 3/1), (-106 ± 9) kJ mol{sup -1} (section x{sub Cu}/x{sub Fe} = 1/1), and (-105 ± 2) kJ mol{sup -1} (section x{sub Cu}/x{sub Fe} = 1/3). In the investigated composition range, the integral mixing enthalpies are sign-changing. For the integral mixing enthalpy, an analytical expression was obtained by the least squares fit of the experimental results using the Redlich-Kister-Muggianu polynomial.

  18. The enthalpy of sublimation and thermodynamic functions of fermium

    International Nuclear Information System (INIS)

    Haire, R.G.; Gibson, J.K.

    1989-01-01

    The enthalpy of sublimation of fermium (Fm), element 100, has now been determined directly by measuring the partial pressure of Fm over alloys, for the temperature range of 642 to 905 K. The partial pressures were determined using Knudsen effusion and target collection techniques. Dilute (10 -5 --10 -7 atom %) solid alloys of Fm and mixtures of Fm and Es in both Sm and Yb solvents were studied. The presence of Es in two of the alloys allowed a direct comparison of the behavior of Fm and Es, where the latter could be used as a reference. It was possible to calculate enthalpies of sublimation and a hypothetical vapor pressure/temperature relationship for pure Fm metal by selecting Yb as the solvent most likely to form a nearly ideal alloy with Fm. From the experimental vapor pressure data, we derived average Second Law values of 33.8±3 kcal/mol and 23.5±3 cal/mol deg for the enthalpy and entropy of sublimation of Fm at 298 K. Third Law enthalpy values were also calculated using the experimental partial pressure data and entropies estimated from derived free energy functions and heat capacities for the solid and gaseous forms of Fm. The average Third Law values (34.8 kcal/mol and 25.1 cal/mol deg, respectively, at 298 K) are in agreement with those obtained via the Second Law. These results establish that Fm, like Es (element 99), is a divalent metal. The finding that Fm metal is the second divalent actinide element experimentally establishes the trend towards metallic divalency expected in the second half of the actinide series

  19. Standard enthalpy of formation of Sm6UO12 acid dissolution calorimetry

    International Nuclear Information System (INIS)

    Venkata Krishnan, R.; Jogeswararao, G.; Ananthasivan, K.

    2016-01-01

    The standard molar enthalpies of formation of Δ f (298 K) of Sm 6 UO 12 have been determined by using an indigenously developed isoperibol acid solution calorimeter. The water equivalent of this calorimeter was determined by electrical calibration. The accuracy of measurement were determined by using standard materials KCl and tris(hydroxyl methyl) amino-methane (TRIS) and was found to be within ±2%. The enthalpies of solution at 298 K of Sm 2 O 3 , UO 3 and Sm 6 UO 12 were measured by using this calorimeter. From these experimental results the enthalpies of formation of Sm 6 UO 12 at 298 K were computed by using Hess's law of summation. (author)

  20. Enthalpies of solvation of ethylene oxide oligomers CH{sub 3}O(CH{sub 2}CH{sub 2}O){sub n}CH{sub 3} (n = 1 to 4) in different H-bonding solvents: Methanol, chloroform, and water. Group contribution method as applied to the polar oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Barannikov, Vladimir P., E-mail: vpb@isc-ras.ru [Institute of Solution Chemistry, Russian Academy of Sciences, Academicheskaya Str. 1, Ivanovo 153045 (Russian Federation); Guseynov, Sabir S.; Vyugin, Anatoliy I. [Institute of Solution Chemistry, Russian Academy of Sciences, Academicheskaya Str. 1, Ivanovo 153045 (Russian Federation)

    2011-12-15

    Highlights: > Solvation enthalpy is found for ethylene oxide oligomers in chloroform and methanol. > Coefficients of solute-solute interaction are determined for oligomers in methanol. > Enthalpies of hydrogen bonding of oligomers with chloroform and water are estimated. > Additivity scheme is developed for describing enthalpies of solvation of oligomers. - Abstract: The enthalpies of solution and solvation of ethylene oxide oligomers CH{sub 3}O(CH{sub 2}CH{sub 2}O){sub n}CH{sub 3} (n = 1 to 4) in methanol and chloroform have been determined from calorimetric measurements at T = 298.15 K. The enthalpic coefficients of pairwise solute-solute interaction for methanol solutions have been calculated. The enthalpic characteristics of the oligomers in methanol, chloroform, water and tetrachloromethane have been compared. The hydrogen bonding of the oligomers with chloroform and water molecules is exhibited in the values of solvation enthalpy and coefficient of solute-solute interaction. This effect is not observed for methanol solvent. The thermochemical data evidence an existence of multi-centred hydrogen bonds in associates of polyethers with the solvent molecules. Enthalpies of hydrogen bonding of the oligomers with chloroform and water have been estimated. The additivity scheme has been developed to describe the enthalpies of solvation of ethylene oxide oligomers, unbranched monoethers and n-alkanes in chloroform, methanol, water, and tetrachloromethane. The correction parameters for contribution of repeated polar groups and correction term for methoxy-compounds have been introduced. The obtained group contributions permit to describe the enthalpies of solvation of unbranched monoethers and ethylene oxide oligomers in the solvents with standard deviation up to 0.6 kJ . mol{sup -1}. The values of group contributions and corrections are strongly influenced by solvent properties.

  1. Melting temperature and enthalpy variations of phase change materials (PCMs): a differential scanning calorimetry (DSC) analysis

    Science.gov (United States)

    Sun, Xiaoqin; Lee, Kyoung Ok; Medina, Mario A.; Chu, Youhong; Li, Chuanchang

    2018-06-01

    Differential scanning calorimetry (DSC) analysis is a standard thermal analysis technique used to determine the phase transition temperature, enthalpy, heat of fusion, specific heat and activation energy of phase change materials (PCMs). To determine the appropriate heating rate and sample mass, various DSC measurements were carried out using two kinds of PCMs, namely N-octadecane paraffin and calcium chloride hexahydrate. The variations in phase transition temperature, enthalpy, heat of fusion, specific heat and activation energy were observed within applicable heating rates and sample masses. It was found that the phase transition temperature range increased with increasing heating rate and sample mass; while the heat of fusion varied without any established pattern. The specific heat decreased with the increase of heating rate and sample mass. For accuracy purpose, it is recommended that for PCMs with high thermal conductivity (e.g. hydrated salt) the focus will be on heating rate rather than sample mass.

  2. Direct determination of enthalpies of solid phase reactions by immersion method; Determination directe des enthalpies de reaction en phase solide par une methode de plongee

    Energy Technology Data Exchange (ETDEWEB)

    Roux, A; Richard, M; Eyraud, L; Stevanovic, M; Elston, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    It is not generally possible to measure the enthalpy change corresponding to solid phase reactions using the dynamic differential thermal analysis method because these reactions are usually too slow at the temperature of operation of present equipment. A ballistic differential thermal analysis apparatus has been developed which is based on an immersion-compensation method; it overcomes the difficulties previously encountered. This apparatus has been used after calibration for determining the enthalpies of formation of calcium and cadmium titanates. and also the Wigner energies of BeO, MgO and Al{sub 2}O{sub 3} samples irradiated at variable dose at a temperature of under 100 deg. C. (authors) [French] Il n'est generalement pas possible de mesurer la variation d'enthalpie correspondant aux reactions en phase solide par la methode d'analyse thermique differentielle dynamique. En effet, ces reactions sont le plus souvent trop lentes aux temperatures d'utilisation des dispositifs actuels. Un appareil d'analyse thermique differentielle balistique, base sur une methode de plongee avec compensation, a ete mis au point et permet de surmonter les difficultes precedentes. Apres etalonnages, cet appareil a ete utilise pour la determination des enthalpies de formation du titanate de calcium et du titanate de cadmium ainsi que pour celle des energies Wigner emmagasinees dans des echantillons de BeO, MgO et Al{sub 2}O{sub 3} irradies a une temperature inferieure a 100 deg. C et a differentes doses. (auteurs)

  3. Modelling of high-enthalpy, high-Mach number flows

    International Nuclear Information System (INIS)

    Degrez, G; Lani, A; Panesi, M; Chazot, O; Deconinck, H

    2009-01-01

    A review is made of the computational models of high-enthalpy flows developed over the past few years at the von Karman Institute and Universite Libre de Bruxelles, for the modelling of high-enthalpy hypersonic (re-)entry flows. Both flows in local thermo-chemical equilibrium (LTE) and flows in thermo-chemical non-equilibrium (TCNEQ) are considered. First, the physico-chemical models are described, i.e. the set of conservation laws, the thermodynamics, transport phenomena and chemical kinetics models. Particular attention is given to the correct modelling of elemental (LTE flows) and species (chemical non-equilibrium-CNEQ-flows) transport. The numerical algorithm, based on a state-of-the-art finite volume discretization, is then briefly described. Finally, selected examples are included to illustrate the capabilities of the developed solver. (review article)

  4. Standard molar enthalpy of formation of 1-benzosuberone: An experimental and computational study

    International Nuclear Information System (INIS)

    Miranda, Margarida S.; Morais, Victor M.F.; Matos, M. Agostinha R.; Liebman, Joel F.

    2010-01-01

    The energetics of 1-benzosuberone was studied by a combination of calorimetric techniques and computational calculations. The standard (p o = 0.1 MPa) molar enthalpy of formation of 1-benzosuberone, in the liquid phase, was derived from the massic energy of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The standard molar enthalpy of vaporization, at T = 298.15 K, was measured by Calvet microcalorimetry. From these two parameters the standard (p o = 0.1 MPa) molar enthalpy of formation, in the gaseous phase, at T = 298.15 K, was derived: -(96.1 ± 3.4) kJ . mol -1 . The G3(MP2)//B3LYP composite method and appropriate reactions were used to computationally calculate the standard molar enthalpy of formation of 1-benzosuberone, in the gaseous phase, at T = 298.15 K. The computational results are in very good agreement with the experimental value.

  5. Investigation of enthalpy and specific heat of the gallium-indium-tin eutectic alloy

    International Nuclear Information System (INIS)

    Roshchupkin, V.V.; Migaj, L.L.; Fordeeva, L.K.; Perlova, N.L.

    1978-01-01

    Enthalpy and specific heat of the fusible (melting point is 10.6 deg C) eutectic alloy (67% Ga - 20.5% In - 12.5% Sn according to mass) are determined by the mixing method. The determination was carried out in vacuum at the residual pressure of >= 1x10 -5 torr in the temperature range from 59.3 to 437.0 deg C. It is established that temperature dependence of alloy enthalpy is described by the equation: Hsub(t) - Hsub(0degC)=1.014+0.0879t-0.0000129 t 2 , where (Hsub(t) - Hsub(0degC)) is enthalpy, cal/g; t-temperature, deg C. Mean-square dispersion is +-0.6%. Temperature dependence of alloy specific heat in the temperature range under study was determined by differentiation of the equation obtained for enthalpy: Csub(p)=0.0879-0.000026t, where Csub(p)-specific heat, cal/gx deg. It is supposed that temperature increase makes it possible to decrease slightly specific heat

  6. Excess enthalpies and (vapour + liquid) equilibrium data for the binary mixtures of dimethylsulphoxide with ketones

    International Nuclear Information System (INIS)

    Radhamma, M.; Venkatesu, P.; Rao, M.V. Prabhakara; Prasad, D.H.L.

    2007-01-01

    Excess enthalpies (H E ), at ambient pressure and T = 298.15 K, have been measured by using a solution calorimeter for the binary liquid mixtures of dimethyl sulphoxide (DMSO) with ketones, as a function of composition. The ketones chosen in the present investigation were methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone (CH). The H E values are positive over the entire composition range for the three binary mixtures. Furthermore, the (vapour + liquid) equilibrium (VLE) was measured at 715 Torr for these mixtures, of different compositions, with the help of Swietoslawski-ebulliometer. The experimental temperature-mole fraction (t-x) data were used to compute Wilson parameters and then used to calculate the equilibrium vapour-phase compositions as well as the theoretical points for these binary mixtures. These Wilson parameters are used to calculate activity coefficients (γ) and these in turn to calculate excess Gibbs free energy (G E ). The intermolecular interactions and structural effects were analyzed on the basis of the measured and derived properties

  7. Enthalpies of formation of selected Co{sub 2}YZ Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Ming, E-mail: myin1@hawk.iit.edu; Chen, Song; Nash, Philip

    2013-11-15

    Highlights: •Enthalpies of formation of selected Co{sub 2}YZ were measured by drop calorimeters. •Enthalpy decreases as the Z element approaches the top right corner of the periodic table. •For the Y element, enthalpy increases on increasing the number of d electrons. •Result of L2{sub 1} structured compounds agrees with first principles data. •Lattice parameters and related phase relationships were consistent with literature data. -- Abstract: Standard enthalpies of formation at 298 K of selected ternary Co{sub 2}-based Heusler compounds Co{sub 2}YZ (Y = Fe, Hf, Mn, Ti, V, Zr; Z = Al, Ga, In, Si, Ge, Sn) were measured by high temperature direct synthesis calorimetry. The measured enthalpies of formation (in kJ/mole of atoms) of the L2{sub 1} compounds are: Co{sub 2}FeGa (−25.8 ± 2.6); Co{sub 2}FeSi (−38.4 ± 2.2); Co{sub 2}FeGe (−11.6 ± 2.1); Co{sub 2}MnGa (−30.1 ± 2.3); Co{sub 2}MnSi (−42.4 ± 1.2); Co{sub 2}MnGe (−31.6 ± 3.0); Co{sub 2}MnSn (−15.6 ± 2.8); Co{sub 2}TiAl (−55.0 ± 3.7); Co{sub 2}TiGa (−54.2 ± 2.6); Co{sub 2}TiSi (−61.4 ± 1.7); Co{sub 2}TiGe (−59.3 ± 3.8); Co{sub 2}TiSn (−38.4 ± 2.0); Co{sub 2}VGa (−28.4 ± 1.1) and for the B2 compounds: Co{sub 2}FeAl (−22.5 ± 2.5), Co{sub 2}MnAl (−27.6 ± 2.7). Values are compared with those from first principles calculation when available and the extended semi-empirical model of Miedema. Trends in enthalpy of formation with element atomic number are discussed. Lattice parameters of the compounds with L2{sub 1} structure are determined by X-ray diffraction analysis.

  8. Enthalpy of phase transition and prediction of phase Equilibria in systems of glycols and glycol ethers

    OpenAIRE

    Esina, Zoya; Miroshnikov, Aleksandr; Korchuganova, Margarita

    2014-01-01

    The PCEAS model was used to study the liquid-solid and liquid-vapor phase transitions at constant pressure in systems containing glycols and glycol ethers. This method is based on minimizing the excess Gibbs energy over the solvation parameter, which takes into account the processes of association of molecules in various phases. To compute the diagrams, the data on enthalpy and phase transition temperatures of pure components are required, while the information about the interactions in the b...

  9. Skin-friction measurements in high-enthalpy hypersonic boundary layers

    Science.gov (United States)

    Goyne, C. P.; Stalker, R. J.; Paull, A.

    2003-06-01

    Skin-friction measurements are reported for high-enthalpy and high-Mach-number laminar, transitional and turbulent boundary layers. The measurements were performed in a free-piston shock tunnel with air-flow Mach number, stagnation enthalpy and Reynolds numbers in the ranges of 4.4 6.7, 3 13 MJ kg(-1) and 0.16× 10(6) 21× 10(6) , respectively. Wall temperatures were near 300 K and this resulted in ratios of wall enthalpy to flow-stagnation enthalpy in the range of 0.1 0.02. The experiments were performed using rectangular ducts. The measurements were accomplished using a new skin-friction gauge that was developed for impulse facility testing. The gauge was an acceleration compensated piezoelectric transducer and had a lowest natural frequency near 40 kHz. Turbulent skin-friction levels were measured to within a typical uncertainty of ± 7%. The systematic uncertainty in measured skin-friction coefficient was high for the tested laminar conditions; however, to within experimental uncertainty, the skin-friction and heat-transfer measurements were in agreement with the laminar theory of van Driest (1952). For predicting turbulent skin-friction coefficient, it was established that, for the range of Mach numbers and Reynolds numbers of the experiments, with cold walls and boundary layers approaching the turbulent equilibrium state, the Spalding & Chi (1964) method was the most suitable of the theories tested. It was also established that if the heat transfer rate to the wall is to be predicted, then the Spalding & Chi (1964) method should be used in conjunction with a Reynolds analogy factor near unity. If more accurate results are required, then an experimentally observed relationship between the Reynolds analogy factor and the skin-friction coefficient may be applied.

  10. Enthalpies of Formation of Transition Metal Diborides: A First Principles Study

    Directory of Open Access Journals (Sweden)

    Catherine Colinet

    2015-11-01

    Full Text Available The enthalpies of formation of transition metals diborides in various structures have been obtained from density functional theory (DFT calculations in order to determine the ground state at T = 0 K and p = 0. The evolution of the enthalpies of formation along the 3D, 4D, and 5D series has been correlated to the considered crystal structures. In the whole, the calculated values of the enthalpies of formation of the diborides in their ground state are in good agreement with the experimental ones when available. The calculated values of the lattice parameters at T = 0 K of the ground state agree well with the experimental values. The total and partial electronic densities of states have been computed. Special features of the transition metal electronic partial density of states have been evidenced and correlated to the local environment of the atoms.

  11. Air-Sea Momentum and Enthalpy Exchange in Coupled Atmosphere-Wave-Ocean Modeling of Tropical Cyclones

    Science.gov (United States)

    Curcic, M.; Chen, S. S.

    2016-02-01

    The atmosphere and ocean are coupled through momentum, enthalpy, and mass fluxes. Accurate representation of these fluxes in a wide range of weather and climate conditions is one of major challenges in prediction models. Their current parameterizations are based on sparse observations in low-to-moderate winds and are not suited for high wind conditions such as tropical cyclones (TCs) and winter storms. In this study, we use the Unified Wave INterface - Coupled Model (UWIN-CM), a high resolution, fully-coupled atmosphere-wave-ocean model, to better understand the role of ocean surface waves in mediating air-sea momentum and enthalpy exchange in TCs. In particular, we focus on the explicit treatment of wave growth and dissipation for calculating atmospheric and oceanic stress, and its role in upper ocean mixing and surface cooling in the wake of the storm. Wind-wave misalignment and local wave disequilibrium result in difference between atmospheric and oceanic stress being largest on the left side of the storm. We find that explicit wave calculation in the coupled model reduces momentum transfer into the ocean by more than 10% on average, resulting in reduced cooling in TC's wake and subsequent weakening of the storm. We also investigate the impacts of sea surface temperature and upper ocean parameterization on air-sea enthalpy fluxes in the fully coupled model. High-resolution UWIN-CM simulations of TCs with various intensities and structure are conducted in this study to better understand the complex TC-ocean interaction and improve the representation of air-sea coupling processes in coupled prediction models.

  12. Thermodynamics of Uranyl Minerals: Enthalpies of Formation of Uranyl Oxide Hydrates

    International Nuclear Information System (INIS)

    Kubatko, K.; Helean, K.; Navrotsky, A.; Burns, P.C.

    2005-01-01

    The enthalpies of formation of seven uranyl oxide hydrate phases and one uranate have been determined using high-temperature oxide melt solution calorimetry: [(UO 2 ) 4 O(OH) 6 ](H 2 O) 5 , metaschoepite; β-UO 2 (OH) 2 ; CaUO 4 ; Ca(UO 2 ) 6 O 4 (OH) 6 (H 2 O) 8 , becquerelite; Ca(UO 2 ) 4 O 3 (OH) 4 (H 2 O) 2 ; Na(UO 2 )O(OH), clarkeite; Na 2 (UO 2 ) 6 O 4 (OH) 6 (H 2 O) 7 , the sodium analogue of compreignacite and Pb 3 (UO 2 ) 8 O 8 (OH) 6 (H 2 O) 2 , curite. The enthalpy of formation from the binary oxides, ΔH f-ox , at 298 K was calculated for each compound from the respective drop solution enthalpy, ΔH ds . The standard enthalpies of formation from the elements, ΔH f o , at 298 K are -1791.0 ± 3.2, -1536.2 ± 2.8, -2002.0 ± 3.2, -11389.2 ± 13.5, -6653.1 ± 13.8, -1724.7 ± 5.1, -10936.4 ± 14.5 and -13163.2 ± 34.4 kJ mol -1 , respectively. These values are useful in exploring the stability of uranyl oxide hydrates in auxiliary chemical systems, such as those expected in U-contaminated environments

  13. Enthalpy recovery in glassy materials: Heterogeneous versus homogenous models

    Science.gov (United States)

    Mazinani, Shobeir K. S.; Richert, Ranko

    2012-05-01

    Models of enthalpy relaxations of glasses are the basis for understanding physical aging, scanning calorimetry, and other phenomena that involve non-equilibrium and non-linear dynamics. We compare models in terms of the nature of the relaxation dynamics, heterogeneous versus homogeneous, with focus on the Kovacs-Aklonis-Hutchinson-Ramos (KAHR) and the Tool-Narayanaswamy-Moynihan (TNM) approaches. Of particular interest is identifying the situations for which experimental data are capable of discriminating the heterogeneous from the homogeneous scenario. The ad hoc assumption of a single fictive temperature, Tf, is common to many models, including KAHR and TNM. It is shown that only for such single-Tf models, enthalpy relaxation of a glass is a two-point correlation function in reduced time, implying that experimental results are not decisive regarding the underlying nature of the dynamics of enthalpy relaxation. We also find that the restriction of the common TNM model to a Kohlrausch-Williams-Watts type relaxation pattern limits the applicability of this approach, as the particular choice regarding the distribution of relaxation times is a more critical factor compared with isothermal relaxation experiments. As a result, significant improvements in fitting calorimetry data can be achieved with subtle adjustments in the underlying relaxation time distribution.

  14. Excess Enthalpies of Mixing of Binary Mixtures of NaCl, KCl, NaBr ...

    African Journals Online (AJOL)

    NJD

    2004-07-01

    Jul 1, 2004 ... NaBr and KBr in Mixed Ternary Solvent Systems at 298.15 K. Bal Raj Deshwala* ... industrial waters and their thermodynamic properties are of practical interest for .... The enthalpy of mixing (∆Hm) is the difference between the excess enthalpy of the ..... tural (categorized by softness, open- ness, and ...

  15. Interface Enthalpy-Entropy Competition in Nanoscale Metal Hydrides

    Directory of Open Access Journals (Sweden)

    Nicola Patelli

    2018-01-01

    Full Text Available We analyzed the effect of the interfacial free energy on the thermodynamics of hydrogen sorption in nano-scaled materials. When the enthalpy and entropy terms are the same for all interfaces, as in an isotropic bi-phasic system, one obtains a compensation temperature, which does not depend on the system size nor on the relative phase abundance. The situation is different and more complex in a system with three or more phases, where the interfaces have different enthalpy and entropy. We also consider the possible effect of elastic strains on the stability of the hydride phase and on hysteresis. We compare a simple model with experimental data obtained on two different systems: (1 bi-phasic nanocomposites where ultrafine TiH2 crystallite are dispersed within a Mg nanoparticle and (2 Mg nanodots encapsulated by different phases.

  16. Solution enthalpies of alkali metal halides in water and heavy water mixtures with dimethyl sulfoxide

    International Nuclear Information System (INIS)

    Egorov, G.I.

    1994-01-01

    Solution enthalpies of CsF, LiCl, NaI, CsI and some other halides of alkali metals and tetrabutylammonium have been measured by the method of calorimetry. Standard solution enthalpies of all alkali metals (except rubidium) halides in water and heavy water mixtures with dimethylsulfoxide at 298.15 K have been calculated. Isotopic effects in solvation enthalpy of the electrolytes mentioned in aqueous solutions of dimethylsulfoxide have been discussed. 29 refs., 2 figs., 4 tabs

  17. Glass transition memorized by the enthalpy-entropy compensation in the shear thinning of supercooled metallic liquids

    Science.gov (United States)

    Zhang, Meng; Liu, Lin

    2018-06-01

    To unravel the true nature of glass transition, broader insights into glass forming have been gained by examining the stress-driven glassy systems, where strong shear thinning, i.e. a reduced viscosity under increasing shear rate, is encountered. It is argued that arbitrarily small stress-driven shear rates would ‘melt’ the glass and erase any memory of its thermal history. In this work, we report a glass transition memorized by the enthalpy-entropy compensation in strongly shear-thinned supercooled metallic liquids, which coincides with the thermal glass transition in both the transition temperature and the activation Gibbs free energy. Our findings provide distinctive insights into both glass forming and shear thinning, and enrich current knowledge on the ubiquitous enthalpy-entropy compensation empirical law in condensed matter physics.

  18. Molecular simulation of excess isotherm and excess enthalpy change in gas-phase adsorption.

    Science.gov (United States)

    Do, D D; Do, H D; Nicholson, D

    2009-01-29

    We present a new approach to calculating excess isotherm and differential enthalpy of adsorption on surfaces or in confined spaces by the Monte Carlo molecular simulation method. The approach is very general and, most importantly, is unambiguous in its application to any configuration of solid structure (crystalline, graphite layer or disordered porous glass), to any type of fluid (simple or complex molecule), and to any operating conditions (subcritical or supercritical). The behavior of the adsorbed phase is studied using the partial molar energy of the simulation box. However, to characterize adsorption for comparison with experimental data, the isotherm is best described by the excess amount, and the enthalpy of adsorption is defined as the change in the total enthalpy of the simulation box with the change in the excess amount, keeping the total number (gas + adsorbed phases) constant. The excess quantities (capacity and energy) require a choice of a reference gaseous phase, which is defined as the adsorptive gas phase occupying the accessible volume and having a density equal to the bulk gas density. The accessible volume is defined as the mean volume space accessible to the center of mass of the adsorbate under consideration. With this choice, the excess isotherm passes through a maximum but always remains positive. This is in stark contrast to the literature where helium void volume is used (which is always greater than the accessible volume) and the resulting excess can be negative. Our definition of enthalpy change is equivalent to the difference between the partial molar enthalpy of the gas phase and the partial molar enthalpy of the adsorbed phase. There is no need to assume ideal gas or negligible molar volume of the adsorbed phase as is traditionally done in the literature. We illustrate this new approach with adsorption of argon, nitrogen, and carbon dioxide under subcritical and supercritical conditions.

  19. Study of Shallow Low-Enthalpy Geothermal Resources Using Integrated Geophysical Methods

    Science.gov (United States)

    De Giorgi, Lara; Leucci, Giovanni

    2015-02-01

    The paper is focused on low enthalpy geothermal exploration performed in south Italy and provides an integrated presentation of geological, hydrogeological, and geophysical surveys carried out in the area of municipality of Lecce. Geological and hydrogeological models were performed using the stratigraphical data from 51 wells. A ground-water flow (direction and velocity) model was obtained. Using the same wells data, the ground-water annual temperature was modeled. Furthermore, the ground surface temperature records from ten meteorological stations were studied. This allowed us to obtain a model related to the variations of the temperature at different depths in the subsoil. Integrated geophysical surveys were carried out in order to explore the low-enthalpy geothermal fluids and to evaluate the results of the model. Electrical resistivity tomography (ERT) and self-potential (SP) methods were used. The results obtained upon integrating the geophysical data with the models show a low-enthalpy geothermal resource constituted by a shallow ground-water system.

  20. Ionic liquids. Combination of combustion calorimetry with high-level quantum chemical calculations for deriving vaporization enthalpies.

    Science.gov (United States)

    Emel'yanenko, Vladimir N; Verevkin, Sergey P; Heintz, Andreas; Schick, Christoph

    2008-07-10

    In this work, the molar enthalpies of formation of the ionic liquids [C2MIM][NO3] and [C4MIM][NO3] were measured by means of combustion calorimetry. The molar enthalpy of fusion of [C2MIM][NO3] was measured using differential scanning calorimetry. Ab initio calculations of the enthalpy of formation in the gaseous phase have been performed for the ionic species using the G3MP2 theory. We have used a combination of traditional combustion calorimetry with modern high-level ab initio calculations in order to obtain the molar enthalpies of vaporization of a series of the ionic liquids under study.

  1. Vaporization, fusion and sublimation enthalpies of the dicarboxylic acids from C4 to C14 and C16

    International Nuclear Information System (INIS)

    Roux, Maria Victoria; Temprado, Manuel; Chickos, James S.

    2005-01-01

    The fusion enthalpies of the series butanedioic acid through to tetradecanedioic acid and hexadecanedioic acids have been measured by DSC. In addition to fusion, a number of solid-solid phase transitions have also been detected in these diacids. The vaporization enthalpies of these compounds have been measured by correlation gas chromatography using the vaporization enthalpies of butanedioic, hexanedioic and decanedioic acids as standards. The vaporization enthalpies of the diacids from C 4 to C 10 correlated linearly with the number of methylene groups present. Above C 10 , the vaporization enthalpies of C 11 -C 14 and C 16 begin to deviate from linearity. The vaporization enthalpies for these compounds are dependent on the temperature of the GC column used. Similar departure from linearity has also been observed previously in the sublimation enthalpies for these compounds. The results are discussed in terms of formation of a cyclic intramolecular hydrogen bonded network in the gas phase similar to the bimolecular association observed in smaller mono-carboxylic acids at ambient temperatures

  2. Enthalpies of mixing in binary liquid alloys of lutetium with 3d metals

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Michael; Berezutski, Vadim [National Academy of Sciences, Kyiv (Ukraine). I. Frantsevich Institute for Problems of Materials Science; Usenko, Natalia; Kotova, Natalia [Taras Shevchenko National Univ., Kyiv (Ukraine). Dept. of Chemistry

    2017-01-15

    The enthalpies of mixing in binary liquid alloys of lutetium with chromium, cobalt, nickel and copper were determined at 1 773 - 1 947 K by isoperibolic calorimetry. The enthalpies of mixing in the Lu-Cr melts (measured up to 40 at.% Cr) demonstrate endothermic effects (ΔH = 6.88 ± 0.66 kJ . mol{sup -1} at x{sub Lu} = 0.60), whereas significant exothermic enthalpies of mixing have been established within a wide composition region for the Co-Lu, Ni-Lu and Cu-Lu liquid alloys. Minimum values of the integral enthalpy of mixing are as follows: ΔH{sub min} = -23.57 ± 1.41 kJ . mol{sup -1} at x{sub Lu} = 0.38 for the Co-Lu system; ΔH{sub min} = -48.65 ± 2.83 kJ . mol{sup -1} at x{sub Lu} = 0.40 for the Ni-Lu system; ΔH{sub min} = -24.63 ± 1.52 kJ . mol{sup -1} at x{sub Lu} = 0.37 for the Cu-Lu system.

  3. Enthalpy of mixing of Sn-Cd system using high temperature Calvet microcalorimeter

    International Nuclear Information System (INIS)

    Jayanthi, K.; Iyer, V.S.; Venugopal, V.

    1993-01-01

    The integral enthalpy of mixing of Sn + Cd alloys were determined at 690 K for mole fraction of cadmium (X Cd ) from 0.06 to 0.958. In the present study, the use of small quantities of metals and the determination of enthalpy of mixing of an endothermic reaction without stirring the bath solution. This was possible due to the high sensitivity of the Calvet calorimeter. (author). 3 refs., 3 tabs

  4. Borate-polyol complexes in aqueous solution: determination of enthalpies by thermometric titrimetry.

    Science.gov (United States)

    Aruga, R

    1985-06-01

    Enthalpies for the reaction of borate with 1,2-ethanediol, 1,2-propanediol, 1,2,3-propanetriol and d-mannitol have been determined by thermometric titrimetry. From these enthalpies and equilibrium constants taken from the literature, corresponding entropies have been calculated. The data refer to aqueous solutions at 25 degrees and I = 1.0M (NaNO(3)). The results indicate reasons for the differences in the stabilities of the complexes.

  5. Energetics of the interaction of the antitumour agent titanocene dichloride with glycine: enthalpy of formation of [Ti(η5-C5H5)2(OOCCH2NH3)2]Cl2

    International Nuclear Information System (INIS)

    Nunes, Paulo M.; Minas da Piedade, Manuel E.

    2004-01-01

    The standard molar enthalpy of formation of [Ti(η 5 -C 5 H 5 ) 2 (OOCCH 2 NH 3 ) 2 ]Cl 2 in the crystalline state, at T=298.15 K, was determined as Δ f H m 0 {[Ti(η 5 -C 5 H 5 ) 2 (OOCCH 2 NH 3 ) 2 ]Cl 2 , cr}=-(1447.6 ± 8.1) kJ · mol -1 , by reaction-solution calorimetry. A discussion of the energetics of the direct interaction of the antitumour agent Ti(η 5 -C 5 H 5 ) 2 Cl 2 with glycine is also presented

  6. Knudsen cell vaporization of rare earth nitrides: enthalpy of vaporization of HoN098

    International Nuclear Information System (INIS)

    Brown, R.C.; Clark, N.J.

    1975-01-01

    The enthalpy of vaporization of HoN 0 . 98 was measured by the weight-loss Knudsen cell technique using Motzfeldt-Whitman extrapolations to zero orifice area. A third-law enthalpy of vaporization of HoN 0 . 98 of 155.9 +- 5 kcal mole -1 was obtained compared to a second-law value of 162.0 +- 5 kcal mole -1 . Similar measurements on the nitrides of samarium, erbium, and ytterbium gave third-law enthalpies of vaporization of 126.8 +-- 5 kcal mole -1 ; 159.6 +- 5 kcal mole -1 , and 121.0 +- 5 kcal mole -1 , respectively. 7 tables

  7. Effect of electrostatic interaction on thermochemical behavior of 12-crown-4 ether in various polar solvents

    International Nuclear Information System (INIS)

    Barannikov, Vladimir P.; Guseynov, Sabir S.; Vyugin, Anatoliy I.

    2010-01-01

    The enthalpies of solution of 12-crown-4 ether have been measured in chloroform, ethyl acetate, acetone, pyridine, acetonitrile and methanol at 298.15 K. The values of enthalpy of solvation and solute-solvent interaction were determined from the obtained results and similar literature data for 12-crown-4 in solvents of various polarities. It was shown that the certain correlation is observed between the enthalpy of solute-solvent interaction and the squared dipole moment of the solvent molecules for solutions in tetrachlormethane, ethyl acetate, pyridine, acetonitrile, DMF, DMSO and propylene carbonate. This means that the electrostatic interaction of 12-crown-4 with polar solvent molecules contributes significantly to the exothermic effect of solvation. The understated negative value was found for the enthalpy of interaction of 12-crown-4 with acetone that can be connected with domination of low polar conformer of the crown ether in acetone medium. The most negative values of enthalpy of solvation are observed for solutions in chloroform and water because of hydrogen bonding between O-atoms of crown ether and molecules of the indicated solvents. This effect is not observed for methanol. The negative coefficient of pairwise solute-solute interaction in methanol indicates that the effects of solvophobic solute-solute interaction and H-bonding of the ether molecule with chain associates of methanol are not evinced in the thermochemical behavior of 12-crown-4.

  8. Investigation on the transient enthalpy of coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Pei-fang; Wang, Na; Yu, Bo; Zhang, Bin; Liu, Yang; Zhou, Huai-chun [Huazhong Univ. of Science and Technology, Wuhan (China). State Key Lab. of Coal Combustion

    2013-07-01

    The transient enthalpy ({Delta}h) of coal/char combustion of the three different coals (including anthracite, bituminous, and lignite) during the process of combustion is determined as a function of burn-off degree by using thermo-gravimetric-differential scanning calorimeter (TG-DSC) simultaneous thermal analyzer, and The error of determining calorific values of coals/chars is less 5% compared the results of TG-DSC with that of an automatic isoperibol calorimeter. It is found that In the initial stage, all the {Delta}h of coals are greater than that of the char pyrolysized from parent coal for many of volatiles contained more a great deal of heat per unit mass oxidized at low temperature, it also imply that coal is more easily ignited than char corresponded; And in the middle stage, all the {Delta}h of coals is lower than that of the char pyrolysized, so the pyrolysized char oxidation can supply much more of thermo-energy per unit mass. {Delta}h are almost a constant when the burn-off degree is equal to between 0.35/0.15 and 0.95/0.85 for ZCY bituminous coal/char and JWY anthracite/char, between 0.35/0.35 and 0.75/0.9 for SLH lignite/char; In the later stage, the {Delta}h of the coal/char decreased with the burn-off degree, it imply that the activity of the coal/char decreases. Therefore, coal pyrolysis changes not only the structure of char, but also the property of release heat; the transient enthalpy of coal/char combustion has been in change with the burn-out degree.

  9. Prediction of failure enthalpy and reliability of irradiated fuel rod under reactivity-initiated accidents by means of statistical approach

    International Nuclear Information System (INIS)

    Nam, Cheol; Choi, Byeong Kwon; Jeong, Yong Hwan; Jung, Youn Ho

    2001-01-01

    During the last decade, the failure behavior of high-burnup fuel rods under RIA has been an extensive concern since observations of fuel rod failures at low enthalpy. Of great importance is placed on failure prediction of fuel rod in the point of licensing criteria and safety in extending burnup achievement. To address the issue, a statistics-based methodology is introduced to predict failure probability of irradiated fuel rods. Based on RIA simulation results in literature, a failure enthalpy correlation for irradiated fuel rod is constructed as a function of oxide thickness, fuel burnup, and pulse width. From the failure enthalpy correlation, a single damage parameter, equivalent enthalpy, is defined to reflect the effects of the three primary factors as well as peak fuel enthalpy. Moreover, the failure distribution function with equivalent enthalpy is derived, applying a two-parameter Weibull statistical model. Using these equations, the sensitivity analysis is carried out to estimate the effects of burnup, corrosion, peak fuel enthalpy, pulse width and cladding materials used

  10. Effects of partitioned enthalpy of mixing on glass-forming ability

    Energy Technology Data Exchange (ETDEWEB)

    Song, Wen-Xiong; Zhao, Shi-Jin, E-mail: shijin.zhao@shu.edu.cn [Institute of Materials Science, Shanghai University, Shanghai 200072 (China)

    2015-04-14

    We explore the inherent reason at atomic level for the glass-forming ability of alloys by molecular simulation, in which the effect of partitioned enthalpy of mixing is studied. Based on Morse potential, we divide the enthalpy of mixing into three parts: the chemical part (Δ E{sub nn}), strain part (Δ E{sub strain}), and non-bond part (Δ E{sub nnn}). We find that a large negative Δ E{sub nn} value represents strong AB chemical bonding in AB alloy and is the driving force to form a local ordered structure, meanwhile the transformed local ordered structure needs to satisfy the condition (Δ E{sub nn}/2 + Δ E{sub strain}) < 0 to be stabilized. Understanding the chemical and strain parts of enthalpy of mixing is helpful to design a new metallic glass with a good glass forming ability. Moreover, two types of metallic glasses (i.e., “strain dominant” and “chemical dominant”) are classified according to the relative importance between chemical effect and strain effect, which enriches our knowledge of the forming mechanism of metallic glass. Finally, a soft sphere model is established, different from the common hard sphere model.

  11. Standard molar enthalpies of formation of copper(II) β-diketonates and monothio-β-diketonates

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Santos, Luis M.N.B.F.

    2006-01-01

    The standard (p o =0.1MPa) molar enthalpies of formation of the crystalline complexes of dibenzoylmethane (Hdbm), thenoyltrifluoroacetone (Httfa), monothiodibenzoylmethane (HdbmS), and monothiothenoyltrifluoroacetone (HttfaS) of copper(II) were determined, at T=298.15K, by high precision solution-reaction calorimetry. The standard molar enthalpies of sublimation of the copper(II) β-diketonate complexes were measured by high-temperature Calvet microcalorimetry. From the standard molar enthalpies of formation of the complexes in the gaseous state, the mean molar dissociation enthalpies copper(II)-ligand, m >(Cu-L), were derived. Δ f H m o (cr)Δ cr g H m o kJ.mol -1 kJ.mol -1 Bis(dibenzoylmethanate)copper(II), Cu(dbm) 2 -364.0+/-3.9230.7+/-8.2Bis(thenoyltrifluoroacetonate)copper(II), Cu(ttfa) 2 -1824.3+/-8.3167.9+/-7.4Bis(monothiodibenzoylmethanate)copper(II), Cu(dbmS) 2 35.6+/-7.7[241+/-15]Bis(monothiothenoyltrifluoroacetonate) copper(II), Cu(ttfaS) 2 -1405.7+/-8.3[177+/-15

  12. Determination of the vacancy formation enthalpy for high purity Ni

    International Nuclear Information System (INIS)

    Lynn, K.G.; Snead, C.L. Jr.; Hurst, J.J.; Farrell, K.

    1979-01-01

    Positron-annihilation lifetime measurements have been made on Ni over a temperature range of 4.2 to 1700 K. We find a small change in the lifetime from 4.2 to 900 K indicating a very small thermal-expansion effect. A small precursor effect is observed before the onset of significant vacancy trapping. A monovacancy formation enthalpy of 1.54/sub +0.2//sup -0.1/ eV is extracted without taking divacancies into consideration in the analysis. No detrapping from mono-vacancies is observed even at the higher temperatures. The vacancy formation enthalpy extracted from the lifetime data is compared to values obtained by Doppler-broadening and angular-correlation techniques

  13. The vapor pressure and enthalpy of vaporization of M-xylene

    International Nuclear Information System (INIS)

    Rothenberg, S.J.; Seiler, F.A.; Bechtold, W.E.; Eidson, A.F.

    1988-01-01

    We measured the vapor pressure of m-xylene over the temperature range 273 to 293 deg K with a single-sided capacitance manometer. The enthalpy of vaporization was 42.2 ± 0.1 (SE) kj/ g·mol. Combining our own data with previously published data, we recommend using the values 42.0, 40.6, and 39.1 (± 0.1) (SE) kjg·mol for the enthalpy of vaporization of m-xylene at 300, 340, and 380 deg. K, respectively, and a value for the change in heat capacity on vaporization (ΔCpdeg.) of 35 ± 3 (SE) J/g·mol·K over the temperature range studied. (author)

  14. Determination of the vacancy formation enthalpy for high purity Ni

    International Nuclear Information System (INIS)

    Lynn, K.G.; Snead, C.L. Jr.; Hurst, J.J.; Farrell, K.

    1979-01-01

    Positron-annihilation lifetime measurements have been made on Ni over a temperature range of 4.2 to 1700 K. We find a small change in the lifetime from 4.2 - 900 K indicating a very small thermal-expansion effect. A small precursor effect is observed before the onset of significant vacancy trapping. A monovacancy formation enthalpy of 1.54sub(+0.2)sup(-0.1) eV is extracted without taking divacancies into consideration in the analysis. No detrapping from mono-vacancies is observed even at the higher temperatures. The vacancy formation enthalpy extracted from the lifetime data is compared to values obtained by Doppler-broadening and angular-correlation techniques. (author)

  15. Calorimetric measurement of the enthalpy of extraction of uranyl nitrate by tri-n-amyl phosphate

    International Nuclear Information System (INIS)

    Srinivasan, T.G.; Vasudeva Rao, P.R.; Venugopal, V.; Sood, D.D.

    2002-01-01

    Enthalpy of extraction of uranyl nitrate by tri n-amyl phosphate (TAP) and its solutions in n-dodecane has been directly measured by solution calorimetry for the first time. Measurements have been made at 303±1 K, in both forward as well as the reverse extraction modes. The enthalpies of the accompanying reactions such as the dilution of the uranyl nitrate in the aqueous phase, the hydration of TAP, the mixing of TAP and n-dodecane, the mixing of the metal-solvate (UO 2 (NO 3 ) 2 ·2TAP) and n-dodecane and mixing of the metal-solvate and TAP have also been independently measured and used to derive both the equilibrium state enthalpies and the standard state enthalpies for the extraction. Two distinct standard states have been used for the organic phase, viz., 1) all solutes infinitely diluted in diluent (ΔH*) and 2) all solutes infinitely diluted in the water saturated extractant (ΔH 0 ). The results have been compared with the enthalpies of extraction measured by employing the temperature dependence of the distribution ratio as well as calorimetry reported in the literature for extraction of uranyl nitrate by TAP and TBP. (author)

  16. Low-enthalpy geothermal resources for electricity production: A demand-side management study for intelligent communities

    DEFF Research Database (Denmark)

    Xydis, George A.; Nanaki, Evanthia A.; Koroneos, Christopher J.

    2013-01-01

    The geological conditions in Greece contributed to the creation of important low-enthalpy geothermal energy resources (LEGERs). The resources are divided into low, medium and high enthalpy, or temperature, based on criteria that are generally based on the energy content of the fluid. LEGERs...... and northern part of the country, as well as in many of the Aegean Islands. The aim of this work is to review the options for managing wind load by using low-enthalpy geothermal energy for electricity (through heat pump utilisation) according to the local energy demand....... are those sources of the hot water whose temperature is between 25 and 100°C, which are used for heating residences and in the agricultural or industrial sector. The investigation for the exploitation of low-enthalpy geothermal fluids, which began around 1980, intensified in the last two decades. The low...

  17. Building blocks for ionic liquids: Vapor pressures and vaporization enthalpies of 1-(n-alkyl)-imidazoles

    International Nuclear Information System (INIS)

    Emel'yanenko, Vladimir N.; Portnova, Svetlana V.; Verevkin, Sergey P.; Skrzypczak, Andrzej; Schubert, Thomas

    2011-01-01

    Highlights: → We measured vapor pressures of the 1-(n-alkyl)-imidazoles by transpiration method. → Variations on the alkyl chain length n were C 3 , C 5 -C 7 , and C 9 -C 10 . → Enthalpies of vaporization were derived from (p, T) dependencies. → Enthalpies of vaporization at 298.15 K were linear dependent on the chain length. - Abstract: Vapor pressures of the linear 1-(n-alkyl)-imidazoles with the alkyl chain C 3 , C 5 -C 7 , and C 9 -C 10 have been measured by the transpiration method. The molar enthalpies of vaporization Δ l g H m of these compounds were derived from the temperature dependencies of vapor pressures. A linear correlation of enthalpies of vaporization Δ l g H m (298.15 K) of the 1-(n-alkyl)-imidazoles with the chain length has been found.

  18. Solute-solute interactions in intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Debashis; Murray, Ryan; Collins, Gary S., E-mail: collins@wsu.edu [Washington State University, Department of Physics and Astronomy (United States); Zacate, Matthew O. [Northern Kentucky University, Department of Physics and Geology (United States)

    2017-11-15

    Experiments were carried out on highly ordered GdAl{sub 2} samples containing extremely dilute mole fractions of{sup 111}In/Cd probe-atom solutes (about 10{sup −11}), intrinsic antisite atoms Al{sub Gd} having mole fractions of order 0-10{sup −2}, and doped with Ag solutes at mole fractions of order 10{sup −2}. Three types of defect interactions were investigated. (1) Quadrupole interactions caused by Ag-solute atoms neighboring{sup 111}In/Cd solute probe atoms were detected using the method of perturbed angular correlation of gamma rays (PAC). Three complexes of pairs of In-probes and Ag-solutes occupying neighboring positions on Gd- and Al-sublattices were identified by comparing site fractions in Gd-poor and Gd-rich GdAl{sub 2}(Ag) samples and from the symmetry of the quadrupole interactions. Interaction enthalpies between solute-atom pairs were determined from temperature dependences of observed site fractions. Repulsive interactions were observed for close-neighbor complexes In{sub Gd}+Ag{sub Gd} and In{sub Gd}+Ag{sub Al} pairs, whereas a slightly attractive interaction was observed for In{sub Al}+Ag{sub Al}. Interaction enthalpies were all small, in the range ±0.15 eV. (2) Quadrupole interactions caused by intrinsic antisite atoms Al{sub Gd} neighboring In{sub Gd} probes were also detected and site fractions measured as a function of temperature, as in previous work on samples not doped with Ag-solutes [Temperature- and composition-driven changes in site occupation of solutes in Gd{sub 1+3x}Al{sub 2−3x}, Zacate and Collins (Phys. Rev. B69, 174202 (1))]. However, the effective binding enthalpy between In{sub Gd} probe and Al{sub Gd} antisite was found to change sign from -0.12 eV (attractive interaction) in undoped samples to + 0.24 eV (repulsive) in Ag-doped samples. This may be attributed to an attractive interaction between Al{sub Gd} antisite atoms and Ag-dopants that competes with the attractive interaction between In{sub Gd} and Al{sub Gd

  19. Modified enthalpy method for the simulation of melting and ...

    Indian Academy of Sciences (India)

    These include the implicit time stepping method of Voller & Cross. (1981), explicit enthalpy method of Tacke (1985), centroidal temperature correction method ... In variable viscosity method, viscosity is written as a function of liquid fraction.

  20. Determination of the protonation enthalpy of humic acid by calorimetric titration technique

    International Nuclear Information System (INIS)

    Kimuro, Shingo; Kirishima, Akira; Sato, Nobuaki

    2015-01-01

    Graphical abstract: The thermodynamic quantities of protonation of humic acid were determined by the combination of potentiometric titration and calorimetric titration. It was observed that the protonation enthalpy and Gibbs free energy had been affected by pH of solution. As a result, the thermodynamics of the protonation reaction of humic acid is influenced by the polyelectrolyte effect and the heterogeneity. - Highlights: • We applied calorimetric titration technique to the protonation of humic acid. • The thermodynamic quantities of protonation of humic acid were determined. • The protonation enthalpy of humic acid is affected by the heterogeneity. • Gibbs free energy of the protonation is affected by the polyelectrolyte effect. - Abstract: In this study, the calorimetric titration technique was used to determine the protonation enthalpy of two reference humic acids and polyacrylic acid. First, we obtained the apparent protonation constant of two kinds of humic acid purchased from IHSS (International Humic Substances Society) and polyacrylic acid by potentiometric titration. Second, we obtained the protonation enthalpy of them by calorimetric titration. The protonation enthalpy of humic acid was affected by pH and the ionic strength of bulk solution. From the comparison of ΔH between humic acid and polyacrylic acid, it was concluded that the pH dependence of ΔH is attributed to the heterogeneity of humic acid. And ΔH of phenolic hydroxyl group in humic acid is strongly influenced by the electric double layer of humic acid’s surface. This is considered to be a reason of the ionic strength dependence of ΔH. On the other hand, Gibbs free energy of the protonation of humic acid is affected by the electrostatic attraction with the progress of dissociation of functional groups such as carboxyl group and phenolic hydroxyl group. Consequently, the thermodynamics of the protonation of humic acid is affected by the polyelectrolyte effect and the

  1. Vapor pressures and vaporization enthalpy of codlemone by correlation gas chromatography

    International Nuclear Information System (INIS)

    Schultz, Shannon M.; Harris, Harold H.; Chickos, James S.

    2015-01-01

    Highlights: • The vaporization enthalpy of codlemone has been evaluated. • The vapor pressure of codlemone has been evaluated from T = (298.15 to T b ) K. • Vapor pressures for the 1-alkanols standards are available from T = (298.15 to 500) K. - Abstract: The vapor pressure and vaporization enthalpy of codlemone (trans, trans 8,10-dodecadien-1-ol), the female sex hormone of the codling moth is evaluated by correlation gas chromatography using a series of saturated primary alcohols as standards. A vaporization enthalpy of (92.3 ± 2.6) kJ · mol −1 and a vapor pressure, p/Pa = (0.083 ± 0.012) were evaluated at T = 298.15 K. An equation for the evaluation of vapor pressure from ambient temperature to boiling has been derived by correlation for codlemone. The calculated boiling temperature of T B = 389 K at p = 267 Pa is within the temperature range reported in the literature. A normal boiling temperature of T B = (549.1 ± 0.1) K is also estimated by extrapolation

  2. Determination of formation enthalpies of incongruently fusing compounds

    Energy Technology Data Exchange (ETDEWEB)

    Kesler, Ya.A.; Cheshnitskij, S.M.; Fotiev, A.A.; Tret' yakov, Yu.D.

    1985-04-01

    Using the method of drop-calorimetry i.e. drop into the calorimeter cell being at the specified temperature of the specimen thermostated at 298 K, for studying reactions of peritectic decomposition of compounds for determining their formation enthalpies is considered. The measurements have been performed at 973 K using high temperature double microcalorimeter. The values ..delta..H/sub 1/=(367.0 +- 2.8) kJ/mol and ..delta..H/sub 2/=)343.9 +- 3.1) kJ/mol are obtained as a result of two series of measurements (6 experiments in each). The advantage of the described technique consists in the fact that the value of enthalpy of compound formation is obtained as a result of direct calorimetric measurements while in the e.m.f. method this value is determined as a coefficient in the Gibbs energy temperature dependence. The method is simple and does not require much time (one measurement takes 30-40 min).

  3. Determination of formation enthalpies of incongruently fusing compounds

    International Nuclear Information System (INIS)

    Kesler, Ya.A.; Cheshnitskij, S.M.; Fotiev, A.A.; Tret'yakov, Yu.D.

    1985-01-01

    Using the method of drop-calorimetry i.e. drop into the calorimeter cell being at the specified temperature of the specimen thermostated at 298 K, for studying reactions of peritectic decomposition of compounds for determining their formation enthalpies is considered. The measurements have been performed at 973 K using high temperature double microcalorimeter. The values ΔH 1 =(367.0+-2.8) kJ/mol and ΔH 2 =)343.9+-3.1) kJ/mol are obtained as a result of two series of measurements (6 experiments in each). The advantage of the described technique consists in the fact that the value of enthalpy of compound formation is obtained as a result of direct calorimetric measurements while in the e.m.f. method this value is determined as a coefficient in the Gibbs energy temperature dependence. The method is simple and does not require much time (one measurement takes 30-40 min)

  4. Vaporization enthalpies of imidazolium based ionic liquids. A thermogravimetric study of the alkyl chain length dependence

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.; Zaitsau, Dzmitry H.; Emel’yanenko, Vladimir N.; Ralys, Ricardas V.; Yermalayeu, Andrei V.; Schick, Christoph

    2012-01-01

    Highlights: ► Enthalpies of vaporization of ionic liquids were measured with thermogravimetry. ► We studied 1-alkyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide. ► The linear alkyl chain length was 4, 6, 8, 10, 12, 14, 16, and 18 C-atoms. ► A linear dependence on the chain length of the alkyl-imidazolium cation was found. - Abstract: Vaporization enthalpies for a series of ten ionic liquids (ILs) 1-alkyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide [C n mim][NTf 2 ], with the alkyl chain length n = 4, 6, 8, 10, 12, 14, 16, and 18 were determined using the thermogravimetric method. An internally consistent set of experimental data and vaporization enthalpies at 540 K was obtained. Vaporization enthalpies at 540 K have shown a linear dependence on the chain length of the alkyl-imidazolium cation in agreement with the experimental results measured previously with a quartz crystal microbalance. Ambiguity of Δ l g C pm o -values required for the extrapolation of experimental vaporization enthalpies to the reference temperature 298 K has been discussed.

  5. Thermodynamics of Uranyl Minerals: Enthalpies of Formation of Uranyl Oxide Hydrates

    Energy Technology Data Exchange (ETDEWEB)

    K. Kubatko; K. Helean; A. Navrotsky; P.C. Burns

    2005-05-11

    The enthalpies of formation of seven uranyl oxide hydrate phases and one uranate have been determined using high-temperature oxide melt solution calorimetry: [(UO{sub 2}){sub 4}O(OH){sub 6}](H{sub 2}O){sub 5}, metaschoepite; {beta}-UO{sub 2}(OH){sub 2}; CaUO{sub 4}; Ca(UO{sub 2}){sub 6}O{sub 4}(OH){sub 6}(H{sub 2}O){sub 8}, becquerelite; Ca(UO{sub 2}){sub 4}O{sub 3}(OH){sub 4}(H{sub 2}O){sub 2}; Na(UO{sub 2})O(OH), clarkeite; Na{sub 2}(UO{sub 2}){sub 6}O{sub 4}(OH){sub 6}(H{sub 2}O){sub 7}, the sodium analogue of compreignacite and Pb{sub 3}(UO{sub 2}){sub 8}O{sub 8}(OH){sub 6}(H{sub 2}O){sub 2}, curite. The enthalpy of formation from the binary oxides, {Delta}H{sub f-ox}, at 298 K was calculated for each compound from the respective drop solution enthalpy, {Delta}H{sub ds}. The standard enthalpies of formation from the elements, {Delta}H{sub f}{sup o}, at 298 K are -1791.0 {+-} 3.2, -1536.2 {+-} 2.8, -2002.0 {+-} 3.2, -11389.2 {+-} 13.5, -6653.1 {+-} 13.8, -1724.7 {+-} 5.1, -10936.4 {+-} 14.5 and -13163.2 {+-} 34.4 kJ mol{sup -1}, respectively. These values are useful in exploring the stability of uranyl oxide hydrates in auxiliary chemical systems, such as those expected in U-contaminated environments.

  6. Standard enthalpies of formation of selected Rh2YZ Heusler compounds

    International Nuclear Information System (INIS)

    Yin, Ming; Nash, Philip

    2015-01-01

    The standard enthalpies of formation (Δ f H°) of selected ternary Rh-based Rh 2 YZ (Y = Cu, Fe, Mn, Ni, Ru, Ti, V; Z = Al, Ga, In, Si, Ge, Sn) compounds were measured using high temperature direct reaction calorimetry. The measured standard enthalpies of formation (in kJ/mol of atoms) are, for the Heusler compound Rh 2 MnSn (−40.1 ± 3.6), for the B2-structured compounds: Rh 2 FeAl (−48.5 ± 2.9); Rh 2 MnAl (−72.4 ± 2.7); Rh 2 MnGa (−55.3 ± 2.0); Rh 2 MnIn (−35.3 ± 1.9), for the tetragonal compounds: Rh 2 FeSn (−28.9 ± 1.3); Rh 2 TiAl (−97.6 ± 2.2); Rh 2 TiGa (−79.0 ± 1.8); Rh 2 TiSn (−74.7 ± 3.1). Values are compared with those from first principles calculations in published papers and the Open Quantum Materials Database (OQMD). Lattice parameters of these compounds are determined using X-ray diffraction analysis (XRD). Microstructures were characterized using scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). - Highlights: • Standard enthalpies of formation of Rh 2 YZ were measured using a drop calorimeter. • Measured enthalpies agree with first principles data in general. • Lattice parameters and related phase relationships were consistent with literature data. • Rh 2 TiSn of tI8 structure were reported for the first time.

  7. pH effect on the enthalpy of dilution and volumetric properties of protocatechuic acid at T = 298.15 K

    International Nuclear Information System (INIS)

    Zheng, Yan; Liu, Min; Wang, Yong; Wang, Chunmei; Sun, Dezhi; Wang, Bingquan

    2014-01-01

    Graphical abstract: The dilution thermal power of PCA in potassium phosphate buffer solutions at different pHs and apparent molar volumes were determined in order to investigate the interactions of PCA with the coexistent spicies. - Highlights: • Enthalpies of dilution and apparent molar volumes of PCA in PBS at different pHs were measured. • Enthalpic interaction coefficients, limiting partial molar volumes and experimental slopes of PCA were determined. • The pH dependence of the weak interactions in the investigated system was obtained. • (Solute + solvent) interactions and structure making/breaking ability of solutes in the given system were discussed. - Abstract: The enthalpies of dilution of protocatechuic acid, a natural anti-cancer substance, in sodium phosphate and potassium phosphate buffer solutions with different pH values were measured by using a mixing-flow microcalorimeter at T = 298.15 K. Densities of the pseudo binary system (phosphate buffer + protocatechuic acid) were also measured with a quartz vibrating-tube densimeter. The enthalpic interaction coefficients (h 2 , h 3 and h 4 ) were computed according to the McMillan–Mayer model. Apparent molar volumes of the system were calculated from the data of densities, which have been used to deduce limiting partial molar volumes (V ϕ 0 ) of protocatechuic acid at different pH values. The aim of the experiments and data process is to investigate the interaction between the molecules of the important drug and that of the drug molecule with coexistent species in aqueous solutions as well as the influences on these interactions of such factors as pH and ion strength. Change trends of the enthalpic pair wise interaction coefficient h 2 and V ϕ 0 of protocatechuic acid with pH increasing in the both phosphate buffer solutions were obtained. The thermodynamic properties, h 2 and V ϕ 0 in potassium phosphate buffer solutions were compared with those in sodium phosphate buffer solutions at

  8. The vapor pressure and enthalpy of vaporization of M-xylene

    Energy Technology Data Exchange (ETDEWEB)

    Rothenberg, S J; Seiler, F A; Bechtold, W E; Eidson, A F

    1988-12-01

    We measured the vapor pressure of m-xylene over the temperature range 273 to 293 deg K with a single-sided capacitance manometer. The enthalpy of vaporization was 42.2 {+-} 0.1 (SE) kj/ g{center_dot}mol. Combining our own data with previously published data, we recommend using the values 42.0, 40.6, and 39.1 ({+-} 0.1) (SE) kjg{center_dot}mol for the enthalpy of vaporization of m-xylene at 300, 340, and 380 deg. K, respectively, and a value for the change in heat capacity on vaporization ({delta}Cpdeg.) of 35 {+-} 3 (SE) J/g{center_dot}mol{center_dot}K over the temperature range studied. (author)

  9. Thermodynamics of hydrogen bonding and van der Waals interactions of organic solutes in solutions of imidazolium based ionic liquids: “Structure-property” relationships

    International Nuclear Information System (INIS)

    Varfolomeev, Mikhail A.; Khachatrian, Artashes A.; Akhmadeev, Bulat S.; Solomonov, Boris N.

    2016-01-01

    Highlights: • Solution enthalpies of organic solutes in imidazolium based ionic liquids were measured. • van der Waals interactions scale of imidazolium based ionic liquids was proposed. • Enthalpies of solvation of organic solutes in ionic liquids were determined. • Hydrogen bond enthalpies of organic solutes with ionic liquids were calculated. • Relationships between structure of ionic liquids and thermochemical data were obtained. - Abstract: In the present work thermochemistry of intermolecular interactions of organic compounds in solutions of imidazolium based ionic liquids (ILs) has been studied using solution calorimetry method. Enthalpies of solution at infinite dilution of non-polar (alkanes, aromatic hydrocarbons) and polar (alcohols, amides, and etc.) organic solutes in two ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium trifluoromethanesulfonate were measured at 298.15 K. The scale of van der Waals interactions of imidazolium based ILs has been proposed on the basis of solution enthalpies of n-alkanes in their media. The effect of the cation and anion structure of ILs on the enthalpies of solvation was analyzed. Enthalpies of hydrogen bonding of organic solutes with imidazolium based ILs were determined. It has been shown that these values are close to zero for proton acceptor solutes. At the same time, enthalpies of hydrogen bonding of proton donor solutes with ionic liquids are increased depending the anion: tetrafluoroborate ≈ bis(trifluoromethylsulfonyl)imide < 2-(2-methoxyethoxy)ethyl sulfate < trifluoromethanesulfonate. Enthalpies of van der Waals interactions and hydrogen bonding in the solutions of imidazolium based ionic liquids were compared with the same data for molecular solvents.

  10. Thermodynamics of hydrogen bonding and van der Waals interactions of organic solutes in solutions of imidazolium based ionic liquids: “Structure-property” relationships

    Energy Technology Data Exchange (ETDEWEB)

    Varfolomeev, Mikhail A., E-mail: vma.ksu@gmail.com; Khachatrian, Artashes A.; Akhmadeev, Bulat S.; Solomonov, Boris N.

    2016-06-10

    Highlights: • Solution enthalpies of organic solutes in imidazolium based ionic liquids were measured. • van der Waals interactions scale of imidazolium based ionic liquids was proposed. • Enthalpies of solvation of organic solutes in ionic liquids were determined. • Hydrogen bond enthalpies of organic solutes with ionic liquids were calculated. • Relationships between structure of ionic liquids and thermochemical data were obtained. - Abstract: In the present work thermochemistry of intermolecular interactions of organic compounds in solutions of imidazolium based ionic liquids (ILs) has been studied using solution calorimetry method. Enthalpies of solution at infinite dilution of non-polar (alkanes, aromatic hydrocarbons) and polar (alcohols, amides, and etc.) organic solutes in two ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium trifluoromethanesulfonate were measured at 298.15 K. The scale of van der Waals interactions of imidazolium based ILs has been proposed on the basis of solution enthalpies of n-alkanes in their media. The effect of the cation and anion structure of ILs on the enthalpies of solvation was analyzed. Enthalpies of hydrogen bonding of organic solutes with imidazolium based ILs were determined. It has been shown that these values are close to zero for proton acceptor solutes. At the same time, enthalpies of hydrogen bonding of proton donor solutes with ionic liquids are increased depending the anion: tetrafluoroborate ≈ bis(trifluoromethylsulfonyl)imide < 2-(2-methoxyethoxy)ethyl sulfate < trifluoromethanesulfonate. Enthalpies of van der Waals interactions and hydrogen bonding in the solutions of imidazolium based ionic liquids were compared with the same data for molecular solvents.

  11. Enthalpy - entropy compensation effect in grain boundary phenomena

    Czech Academy of Sciences Publication Activity Database

    Lejček, Pavel

    2005-01-01

    Roč. 96, č. 10 (2005), s. 1129-1133 ISSN 0044-3093 R&D Projects: GA MPO(CZ) FF-P2/053 Institutional research plan: CEZ:AV0Z10100520 Keywords : compensation effect * enthalpy * entropy * thermodynamics * grain boundary Subject RIV: BJ - Thermodynamics Impact factor: 0.842, year: 2005

  12. Weak interactions in clobazam–lactose mixtures examined by differential scanning calorimetry: Comparison with the captopril–lactose system

    International Nuclear Information System (INIS)

    Toscani, S.; Cornevin, L.; Burgot, G.

    2012-01-01

    Highlights: ► Thermodynamic and kinetic parameters of weak interactions in binary systems by DSC. ► Energy-barrier decrease for lactose dehydration induced by clobazam. ► Recrystallisation of metastable liquid clobazam induced by anhydrous alpha lactose. ► Decrease of lactose dehydration temperature in binary mixtures with captopril. ► Increase of lactose dehydration enthalpy in binary mixtures with captopril. - Abstract: The thermal behaviour of binary mixtures of two drugs (clobazam and captopril, respectively) and a pharmaceutical excipient (lactose monohydrate) was measured with differential scanning calorimetry to determine thermodynamic and kinetic parameters (dehydration and melting enthalpies and dehydration and glass-transition activation energies) which might be affected by intermolecular interactions. A kinetic study showed that lactose dehydration is not a single-step conversion and that clobazam contributed to reduce the energy barrier for the bulk dehydration of the excipient. On the other hand, the physical interactions between metastable liquid clobazam and crystalline anhydrous α-lactose obtained from monohydrate dehydration gave rise to the recrystallisation of clobazam. In the captopril–lactose system, the liquid captopril influenced the lactose dehydration: a sharp increase of the dehydration enthalpy and a concurrent reduction of the dehydration temperature were observed. Finally, it turned out that solid-phase transitions were enhanced by the contact with a liquid phase.

  13. Standard molar enthalpies of formation of copper(II) {beta}-diketonates and monothio-{beta}-diketonates

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro da Silva, Manuel A.V. [Centro de Investigacao em Quimica, Departamento de Quimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal)]. E-mail: risilva@fc.up.pt; Santos, Luis M.N.B.F. [Centro de Investigacao em Quimica, Departamento de Quimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal)

    2006-07-15

    The standard (p{sup o}=0.1MPa) molar enthalpies of formation of the crystalline complexes of dibenzoylmethane (Hdbm), thenoyltrifluoroacetone (Httfa), monothiodibenzoylmethane (HdbmS), and monothiothenoyltrifluoroacetone (HttfaS) of copper(II) were determined, at T=298.15K, by high precision solution-reaction calorimetry. The standard molar enthalpies of sublimation of the copper(II) {beta}-diketonate complexes were measured by high-temperature Calvet microcalorimetry. From the standard molar enthalpies of formation of the complexes in the gaseous state, the mean molar dissociation enthalpies copper(II)-ligand, (Cu-L), were derived. {delta}{sub f}H{sub m}{sup o} (cr){delta}{sub cr}{sup g}H{sub m}{sup o} kJ.mol{sup -1}kJ.mol{sup -1}Bis(dibenzoylmethanate)copper(II), Cu(dbm){sub 2}-364.0+/-3.9230.7+/-8.2Bis(thenoyltrifluoroacetonate)copper(II), Cu(ttfa){sub 2}-1824.3+/-8.3167.9+/-7.4Bis(monothiodibenzoylmethanate)copper(II), Cu(dbmS){sub 2}35.6+/-7.7[241+/-15]Bis(monothiothenoyltrifluoroacetonate) copper(II), Cu(ttfaS){sub 2}-1405.7+/-8.3[177+/-15].

  14. COTHERM: Geophysical Modeling of High Enthalpy Geothermal Systems

    Science.gov (United States)

    Grab, Melchior; Maurer, Hansruedi; Greenhalgh, Stewart

    2014-05-01

    In recent years geothermal heating and electricity generation have become an attractive alternative energy resource, especially natural high enthalpy geothermal systems such as in Iceland. However, the financial risk of installing and operating geothermal power plants is still high and more needs to be known about the geothermal processes and state of the reservoir in the subsurface. A powerful tool for probing the underground system structure is provided by geophysical techniques, which are able to detect flow paths and fracture systems without drilling. It has been amply demonstrated that small-scale features can be well imaged at shallow depths, but only gross structures can be delineated for depths of several kilometers, where most high enthalpy systems are located. Therefore a major goal of our study is to improve geophysical mapping strategies by multi-method geophysical simulations and synthetic data inversions, to better resolve structures at greater depth, characterize the reservoir and monitor any changes within it. The investigation forms part of project COTHERM - COmbined hydrological, geochemical and geophysical modeling of geoTHERMal systems - in which a holistic and synergistic approach is being adopted to achieve multidisciplinary cooperation and mutual benefit. The geophysical simulations are being performed in combination with hydrothermal fluid flow modeling and chemical fluid rock interaction modeling, to provide realistic constraints on lithology, pressure, temperature and fluid conditions of the subsurface. Two sites in Iceland have been selected for the study, Krafla and Reykjanes. As a starting point for the geophysical modeling, we seek to establish petrophysical relations, connecting rock properties and reservoir conditions with geophysical parameters such as seismic wave speed, attenuation, electrical conductivity and magnetic susceptibility with a main focus on seismic properties. Therefore, we follow a comprehensive approach involving

  15. Enthalpies of mixing in the ternary system aluminium chloride - potassium chloride - aluminium chloride monoamine

    Energy Technology Data Exchange (ETDEWEB)

    Hatem, G.; Gaune-Escard, M.; Bros, J.P. (Aix-Marseille-2 Univ., 13 - Marseille (France). Centre de Saint Jerome); Ostvold, T. (Norges Tekniske Hoegskole, Trondheim (Norway). Inst. for Uorganisk Kjemi)

    1988-06-01

    Quasi binary enthalpy of mixing experiments have been performed in the ternary liquid system AlCl{sub 3}-AlCl{sub 3}NH{sub 3}-KCl by mixing AlCl{sub 3} + KCl with AlCl{sub 3}NH{sub 3} keeping the ratio X{sub AlCl3}/X{sub KCl} = 1.125, 1.5 and 2.0, respectively. At X{sub AlCl3}NH{sub 3} = 0.5 and T = 270deg C the enthalpies of mixing were {approx equal} -430 J mol{sup -1} for all the quasi-binaries studied. The new enthalpy data are not fully consistent with published vapour pressure data and thermodynamic model calculations. (orig.).

  16. Determination of standard molar enthalpies of formation of SrMoO4 micro/nano structures

    International Nuclear Information System (INIS)

    Guo, Yunxiao; Fan, Gaochao; Huang, Zaiyin; Sun, Jilong; Wang, Lude; Wang, Tenghui; Chen, Jie

    2012-01-01

    Graphical abstract: Schematic illustration of thermochemical cycle between the nano and bulk reaction systems. Highlights: ► A thermochemical cycle was designed. ► Relationship of standard molar enthalpies of formation between micro/nano and bulk SrMoO 4 was gained. ► Microcalorimetry was used as a supplementary technology. ► Standard molar enthalpies of formation of the synthesized micro/nano SrMoO 4 were obtained. ► This novel approach can be used to other micro/nano materials. - Abstract: SrMoO 4 micro/nano structures were prepared by a simple reverse microemulsion method and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscope (SEM). In order to associate standard molar enthalpies of formation of nano SrMoO 4 with bulk SrMoO 4 , the relationship of them was obtained through designing a thermochemical cycle according to thermodynamic potential function method. Combined with microcalorimetry, the standard molar enthalpies of formation of the synthesized micro/nano SrMoO 4 at 298.15 K were gained in this paper. And the variation of standard molar enthalpies of formation of micro/nano SrMoO 4 with different morphologies and sizes was discussed.

  17. Modified solution calorimetry approach for determination of vaporization and sublimation enthalpies of branched-chain aliphatic and alkyl aromatic compounds at T = 298.15 K

    International Nuclear Information System (INIS)

    Varfolomeev, Mikhail A.; Novikov, Vladimir B.; Nagrimanov, Ruslan N.; Solomonov, Boris N.

    2015-01-01

    Highlights: • Solution enthalpies of 18 branching-chain alkyl aromatic and aliphatic compounds in cyclohexane were measured. • Group contributions to the enthalpy of solvation due to branching and substitution in carbon chain were evaluated. • Modified solution calorimetry based approach for determination of vaporization/sublimation enthalpies was proposed. • This approach provides vaporization/sublimation enthalpies directly at T = 298.15 K. • Vaporization/sublimation enthalpies of 35 branched-chain alkyl aromatic and aliphatic compounds were determined. - Abstract: The enthalpies of solution, solvation and vaporization/sublimation are interrelated values combined in the simplest thermodynamic circle. Hence, experimental determination of vaporization/sublimation enthalpy can be substituted by experimentally simpler determination of solution enthalpy when solvation enthalpy is known. Previously it was found that solvation enthalpies of a wide range of unbranched aliphatic and aromatic solutes in saturated hydrocarbons are in good linear correlation with their molar refraction values. This allows to estimate the vaporization/sublimation enthalpy of any unbranched organic compound from its solution enthalpy in saturated hydrocarbon and molar refraction. In the present work this approach was modified for determination of vaporization/sublimation enthalpy of branched-chain alkyl aromatic and aliphatic compounds. Group contributions to the enthalpy of solvation due to the branching of carbon chain were evaluated. Enthalpies of solution at infinite dilution of 18 branched-chain aliphatic and alkyl aromatic compounds were measured at T = 298.15 K. Vaporization/sublimation enthalpies for 35 branched aliphatic and alkyl aromatic compounds were determined by using modified solution calorimetry approach. These values are in good agreement with available literature data on vaporization/sublimation enthalpies obtained by conventional methods.

  18. Kinetics and enthalpy of crystallization of uric acid dihydrate

    International Nuclear Information System (INIS)

    Sádovská, Galina; Honcová, Pavla; Sádovský, Zdeněk

    2013-01-01

    Highlights: • The kinetic constant and growth order of crystallization of uric acid dihydrate was calculated. • The equation describing first-order crystal growth was derived. • The enthalpy of crystallization of uric acid dihydrate was determined. - Abstract: The kinetics of crystallization of uric acid dihydrate in aqueous solution with a constant ionic strength 0.3 mol dm −3 NaCl and at thermodynamic and physiological temperature (25 and 37 °C) was studied using isoperibolic reaction twin calorimeter. The enthalpy of crystallization Δ cr H = −47.3 ± 0.9 and −46.2 ± 1.4 kJ mol −1 and kinetic constant k g = 2.0 × 10 −8 and 9.6 × 10 −8 m 4 s −1 mol −1 were determined at 25 and 37 °C, respectively

  19. Standard molar enthalpies of formation of 1-methyl-2-piperidinemethanol, 1-piperidineethanol, and 2-piperidineethanol

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Cabral, Joana I.T.A.

    2006-01-01

    The standard (p o =0.1MPa) molar enthalpies of combustion, Δ c H m o , for the liquid compounds 1-methyl-2-piperidinemethanol, 1-piperidineethanol, and 2-piperidineethanol, were measured by static bomb calorimetry, in oxygen, at T=298.15K. The standard molar enthalpies of vaporization, at T=298.15K, of these three liquid compounds were determined by Calvet microcalorimetry. -Δ c H m o (l)/(kJ.mol -1 )Δ l g H m o /(kJ.mol -1 )1-Methyl-2-piperidinemethanol4598.3+/-1.868. 22+/-0.711-Piperidineethanol4595.2+/-1.764.18+/-0.812 -Piperidineethanol4566.2+/-1.375.24+/-0.52 These values, were used to derive the standard molar enthalpies of formation of the compounds, at T=298.15K, in their liquid and gaseous phase, respectively. The derived standard molar enthalpies of formation, in the gaseous state, are analyzed in terms of enthalpic increments and interpreted in terms of molecular structure.

  20. Enthalpy-based equation of state for highly porous materials employing modified soft sphere fluid model

    Science.gov (United States)

    Nayak, Bishnupriya; Menon, S. V. G.

    2018-01-01

    Enthalpy-based equation of state based on a modified soft sphere model for the fluid phase, which includes vaporization and ionization effects, is formulated for highly porous materials. Earlier developments and applications of enthalpy-based approach had not accounted for the fact that shocked states of materials with high porosity (e.g., porosity more than two for Cu) are in the expanded fluid region. We supplement the well known soft sphere model with a generalized Lennard-Jones formula for the zero temperature isotherm, with parameters determined from cohesive energy, specific volume and bulk modulus of the solid at normal condition. Specific heats at constant pressure, ionic and electronic enthalpy parameters and thermal excitation effects are calculated using the modified approach and used in the enthalpy-based equation of state. We also incorporate energy loss from the shock due to expansion of shocked material in calculating porous Hugoniot. Results obtained for Cu, even up to initial porosities ten, show good agreement with experimental data.

  1. The mixing enthalpy of the Pb-Te system

    International Nuclear Information System (INIS)

    Blachnik, R.; Gather, B.

    1983-01-01

    The thermodynamic properties of molten Pb-Te alloys were measured at 1210 K in a Setaram-Calvet-type calorimeter. It was found that the enthalpy of mixing has a pronounced minimum of -26250 +- 950 J mol - 1 at 52 mol.%Te. The results obtained are discussed in terms of an ionic model. (Auth.)

  2. Extension of the segment-based Wilson and NRTL models for correlation of excess molar enthalpies of polymer solutions

    International Nuclear Information System (INIS)

    Sadeghi, Rahmat

    2005-01-01

    The polymer Wilson model and the polymer NRTL model have been extended for the representation of the excess enthalpy of multicomponent polymer solutions. Applicability of obtained equations in the correlation of the excess enthalpies of polymer solutions has been examined. It is found that the both models are suitable models in representing the published excess enthalpy data for the tested polymer solutions

  3. Generalized enthalpy model of a high-pressure shift freezing process

    KAUST Repository

    Smith, N. A. S.

    2012-05-02

    High-pressure freezing processes are a novel emerging technology in food processing, offering significant improvements to the quality of frozen foods. To be able to simulate plateau times and thermal history under different conditions, in this work, we present a generalized enthalpy model of the high-pressure shift freezing process. The model includes the effects of pressure on conservation of enthalpy and incorporates the freezing point depression of non-dilute food samples. In addition, the significant heat-transfer effects of convection in the pressurizing medium are accounted for by solving the two-dimensional Navier-Stokes equations. We run the model for several numerical tests where the food sample is agar gel, and find good agreement with experimental data from the literature. © 2012 The Royal Society.

  4. Low-enthalpy geothermal resources for electricity production: A demand-side management study for intelligent communities

    International Nuclear Information System (INIS)

    Xydis, George A.; Nanaki, Evanthia A.; Koroneos, Christopher J.

    2013-01-01

    The geological conditions in Greece contributed to the creation of important low-enthalpy geothermal energy resources (LEGERs). The resources are divided into low, medium and high enthalpy, or temperature, based on criteria that are generally based on the energy content of the fluid. LEGERs are those sources of the hot water whose temperature is between 25 and 100 °C, which are used for heating residences and in the agricultural or industrial sector. The investigation for the exploitation of low-enthalpy geothermal fluids, which began around 1980, intensified in the last two decades. The low-enthalpy geothermal potential in Greece is rather significant as most of the geothermal fields have been found in regions with favourable developmental conditions, and it seems that they do not present serious environmental or technical exploitation problems. LEGER areas are abundant in Greece, mainly in the eastern and northern part of the country, as well as in many of the Aegean Islands. The aim of this work is to review the options for managing wind load by using low-enthalpy geothermal energy for electricity (through heat pump utilisation) according to the local energy demand. -- Highlights: •Approximately 45.43 GWh per year of electricity can be covered from low-enthalpy geothermal energy resources (LEGERs). •In particular, 10% of the electricity demand can be covered from the LEGER N. Kessani (NK). •The needs for LEGER contribution were increased when wind turbine (WT) production was low. •In winter, where there is abundance of wind, LEGER can be used mostly for heating. •During summer, LEGER can assist more in electricity when heating is not needed

  5. Equivalent Temperature-Enthalpy Diagram for the Study of Ejector Refrigeration Systems

    Directory of Open Access Journals (Sweden)

    Mohammed Khennich

    2014-05-01

    Full Text Available The Carnot factor versus enthalpy variation (heat diagram has been used extensively for the second law analysis of heat transfer processes. With enthalpy variation (heat as the abscissa and the Carnot factor as the ordinate the area between the curves representing the heat exchanging media on this diagram illustrates the exergy losses due to the transfer. It is also possible to draw the paths of working fluids in steady-state, steady-flow thermodynamic cycles on this diagram using the definition of “the equivalent temperature” as the ratio between the variations of enthalpy and entropy in an analyzed process. Despite the usefulness of this approach two important shortcomings should be emphasized. First, the approach is not applicable for the processes of expansion and compression particularly for the isenthalpic processes taking place in expansion valves. Second, from the point of view of rigorous thermodynamics, the proposed ratio gives the temperature dimension for the isobaric processes only. The present paper proposes to overcome these shortcomings by replacing the actual processes of expansion and compression by combinations of two thermodynamic paths: isentropic and isobaric. As a result the actual (not ideal refrigeration and power cycles can be presented on equivalent temperature versus enthalpy variation diagrams. All the exergy losses, taking place in different equipments like pumps, turbines, compressors, expansion valves, condensers and evaporators are then clearly visualized. Moreover the exergies consumed and produced in each component of these cycles are also presented. The latter give the opportunity to also analyze the exergy efficiencies of the components. The proposed diagram is finally applied for the second law analysis of an ejector based refrigeration system.

  6. Effect of Solution pH on the Adsorption of Paracetamol on Chemically Modified Activated Carbons

    Directory of Open Access Journals (Sweden)

    Valentina Bernal

    2017-06-01

    Full Text Available Paracetamol adsorption in acidic, neutral and basic media on three activated carbons with different chemistry surfaces was studied. A granular activated carbon (GAC was prepared from coconut shell; starting from this sample, an oxidized activated carbon (GACo was obtained by treating the GAC with a boiling solution of 6 M nitric acid, so to generate a greater number of oxygenated surface groups. In addition, a reduced activated carbon (GACr was obtained by heating the GAC at 1173 K, to remove the oxygenated surface groups. Paracetamol adsorption was higher for GACr due to the lower presence of oxygenated surface functional groups. Moreover, adsorption was highest at neutral pH. The magnitude of the interactions between paracetamol molecules and activated carbons was studied by measuring the immersion enthalpies of activated carbons in solution of paracetamol at different concentrations and pH values and by calculating the interaction enthalpy. The highest value was obtained for GACr in a paracetamol solution of 1000 mg L−1 at pH 7, confirming that paracetamol adsorption is favoured on basic activated carbons at pH values near to neutrality. Finally, the Gibbs energy changes confirmed the latter result, allowing explaining the different magnitudes of the interactions between paracetamol and activated carbons, as a function of solution pH.

  7. Standard molar enthalpies of formation of nickel(II) {beta}-diketonates and monothio-{beta}-diketonates

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro da Silva, Manuel A.V. [Centro de Investigacao em Quimica, Departamento de Quimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal)]. E-mail: risilva@fc.up.pt; Santos, Luis M.N.B.F. [Centro de Investigacao em Quimica, Departamento de Quimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Giera, Edward [Faculty of Chemistry, Wroclaw University, ul. F. Joliot-Curie 14, 50-383 Wroclaw (Poland)

    2007-03-15

    The standard (p{sup o}=0.1MPa) molar enthalpies of formation of the crystalline diaquobis(dibenzoylmethanate)nickel(II), Ni(dbm){sub 2}(H{sub 2}O){sub 2}, diaquobis(thenoyltrifluoroacetonate)nickel(II), Ni(ttfa){sub 2}(H{sub 2}O){sub 2} bis(monothiodibenzoylmethanate)nickel(II), Ni(dbmS){sub 2} and bis(monothiothenoyltrifluoroacetonate)nickel(II), Ni(HttfaS){sub 2} were determined, at T=298.15K, by high precision solution-reaction calorimetry. The standard molar enthalpy of sublimation of the monothiothenoyltrifluoroacetone (HttfaS) complex was measured by high-temperature Calvet microcalorimetry. From the standard molar enthalpies of formation of the complexes in the gaseous state, the mean nickel(II)-ligand molar dissociation enthalpies, (Ni-L), were derived. {delta}{sub f}H{sub m}{sup o}(cr)/(kJ.mol{sup -1})Diaquobis(dibenzoylmethanate)nickel(II), Ni(dbm){sub 2}(H{sub 2}O){sub 2}-993.3+/-3.8Diaquobis(thenoyltrifluoroacetonate)nickel(II), Ni(ttfa){sub 2}(H{sub 2}O){sub 2}-2452.0+/-8.3Bis(monothiodibenzoylmethanate)nickel(II), Ni(dbmS){sub 2}-42.1+/-5.9Bis(monothiothenoyltrifluoroacetonate)nickel(II), Ni(ttfaS){sub 2}-1473.5+/-8.1.

  8. Kinetics and enthalpy of crystallization of uric acid dihydrate

    Energy Technology Data Exchange (ETDEWEB)

    Sádovská, Galina, E-mail: galina.sadovska@upce.cz; Honcová, Pavla; Sádovský, Zdeněk

    2013-08-20

    Highlights: • The kinetic constant and growth order of crystallization of uric acid dihydrate was calculated. • The equation describing first-order crystal growth was derived. • The enthalpy of crystallization of uric acid dihydrate was determined. - Abstract: The kinetics of crystallization of uric acid dihydrate in aqueous solution with a constant ionic strength 0.3 mol dm{sup −3} NaCl and at thermodynamic and physiological temperature (25 and 37 °C) was studied using isoperibolic reaction twin calorimeter. The enthalpy of crystallization Δ{sub cr}H = −47.3 ± 0.9 and −46.2 ± 1.4 kJ mol{sup −1}and kinetic constant k{sub g} = 2.0 × 10{sup −8} and 9.6 × 10{sup −8} m{sup 4} s{sup −1} mol{sup −1} were determined at 25 and 37 °C, respectively.

  9. Vapour pressures and enthalpies of vapourization of a series of the linear aliphatic nitriles

    International Nuclear Information System (INIS)

    Emel'yanenko, Vladimir N.; Verevkin, Sergey P.; Koutek, Bohumir; Doubsky, Jan

    2005-01-01

    Vapour pressures and the molar enthalpies of vapourization ΔlgHm-bar of the linear aliphatic nitriles C 7 -C 17 have been determined by the transpiration method. Kovat's indices of these compounds were measured by capillary gas-chromatography. A linear correlation of enthalpies of vapourization ΔlgHm-bar at T=298.15 K of the nitriles studied with the Kovats indices has been found

  10. Measurement of the enthalpies of vaporization and sublimation of solids aromatic hydrocarbons by differential scanning calorimetry

    International Nuclear Information System (INIS)

    Rojas, Aaron; Orozco, Eulogio

    2003-01-01

    An experimental procedure is proposed for direct measurement of the heat involved in the vaporization of a solid organic compound above its normal melting temperature. This technique consists on the fusion of a solid aromatic hydrocarbon, which is then vaporized by a sudden decrease of the pressure. The direct register of heat flow as function of time by differential scanning calorimetry allows the quantifying of the enthalpy of vaporization of compounds such as phenanthrene, β-naphthol, pyrene, and anthracene. Enthalpies of vaporization were measured in an isothermal mode over a range of temperatures from 10 to 20 K above the melting temperatures of each compound, while enthalpies of fusion were determined from separate experiments performed in a scanning mode. Enthalpies of sublimation are computed from results of fusion and vaporization, and then compared with results from the literature, which currently are obtained by calorimetric or indirect techniques

  11. Experimental and theoretical excess molar enthalpies of ternary and binary mixtures containing 2-Methoxy-2-Methylpropane, 1-propanol, heptane

    International Nuclear Information System (INIS)

    Mato, Marta M.; Cebreiro, Susana M.; Paz Andrade, María Inmaculada; Legido, José Luis

    2013-01-01

    Highlights: • Experimental enthalpies for the ternary system MTBE + propanol + heptane were measured. • No experimental ternary values were found in the currently available literature. • Experimental enthalpies for the binary system propanol + heptane were measured. • Excess molar enthalpies are positive over the whole range of composition. • The ternary contribution is also positive, and the representation is asymmetric. -- Abstract: Excess molar enthalpies, at the temperature of 298.15 K and atmospheric pressure, have been measured for the ternary system {x 1 2-Methoxy-2-Methylpropane (MTBE) + x 2 1-propanol + (1 − x 1 − x 2 ) heptane}, over the whole composition range. Also, experimental data of excess molar enthalpy for the involved binary mixture {x 1-propanol + (1 − x) heptane} at the 298.15 K and atmospheric pressure, are reported. We are not aware of any previous experimental measurement of excess enthalpy in the literature for the ternary system presented in this study. Values of the excess molar enthalpies were measured using a Calvet microcalorimeter. The ternary contribution to the excess enthalpy was correlated with the equation due to Morris et al. (1975) [15], and the equation proposed by Myers–Scott (1963) [14] was used to fitted the experimental binary mixture measured in this work. Additionally, the experimental results are compared with the estimations obtained by applying the group contribution model of UNIFAC, in the versions of Larsen et al. (1987) [16] and Gmehling et al. (1993) [17]. Several empirical expressions for estimating ternary properties from binary results were also tested

  12. The Calculation of Standard Enthalpies of Formation of Alkanes: Illustrating Molecular Mechanics and Spreadsheet Programs

    Science.gov (United States)

    Hawk, Eric Leigh

    1999-02-01

    How group increment methods may be used to predict standard enthalpies of formation of alkanes is outlined as an undergraduate computational chemistry experiment. The experiment requires input and output data sets. Although users may create their own data sets, both sets are provided. The input data set contains experimentally determined gas-phase standard enthalpies of formation and calculated steric energies for 10 alkanes. The steric energy for an alkane is calculated via a Molecular Mechanics approach employing Allinger's MM3 force field. Linear regression analysis on data contained in the input data set generates the coefficients that are used with the output data set to calculate standard enthalpies of formation for 15 alkanes. The average absolute error for the calculated standard enthalpies of formation is 1.22 kcal/mol. The experiment is highly suited to those interested in incorporating more computational chemistry in their curricula. In this regard, it is ideally suited for a physical chemistry laboratory, but it may be used in an organic chemistry course as well.

  13. A new method for the determination of vaporization enthalpies of ionic liquids at low temperatures.

    Science.gov (United States)

    Verevkin, Sergey P; Zaitsau, Dzmitry H; Emelyanenko, Vladimir N; Heintz, Andreas

    2011-11-10

    A new method for the determination of vaporization enthalpies of extremely low volatile ILs has been developed using a newly constructed quartz crystal microbalance (QCM) vacuum setup. Because of the very high sensitivity of the QCM it has been possible to reduce the average temperature of the vaporization studies by approximately 100 K in comparison to other conventional techniques. The physical basis of the evaluation procedure has been developed and test measurements have been performed with the common ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C(2)mim][NTf(2)] extending the range of measuring vaporization enthalpies down to 363 K. The results obtained for [C(2)mim][NTf(2)] have been tested for thermodynamic consistency by comparison with data already available at higher temperatures. Comparison of the temperature-dependent vaporization enthalpy data taken from the literature show only acceptable agreement with the heat capacity difference of -40 J K(-1) mol(-1). The method developed in this work opens also a new way to obtain reliable values of vaporization enthalpies of thermally unstable ionic liquids.

  14. Enthalpy-increment measurements for CsI(s) and Cs2CrO4(s) by high-temperature Calvet calorimetry

    International Nuclear Information System (INIS)

    Venugopal, V.; Agarwal, R.; Roy, K.N.; Prasad, R.; Sood, D.D.

    1987-01-01

    Molar thermodynamic properties of CsI(s) and Cs 2 Cr O 4 (s) have been evaluated by enthalpy-increment measurements, using a Calvet high-temperature calorimeter. Least squares analyses were performed on the enthalpy increment results. Data is presented in tabular form for the dependence of enthalpy increments on temperature, in the range 333 to 822 K, for both caesium compounds, along with the thermal properties of the compounds. Good agreement is found between the present data and previously reported results on reduced enthalpy increments of CsI(s) and Cs 2 CrO 4 (s). (U.K.)

  15. Assessment of semiempirical enthalpy of formation in solution as an effective energy function to discriminate native-like structures in protein decoy sets.

    Science.gov (United States)

    Urquiza-Carvalho, Gabriel Aires; Fragoso, Wallace Duarte; Rocha, Gerd Bruno

    2016-08-05

    In this work, we tested the PM6, PM6-DH+, PM6-D3, and PM7 enthalpies of formation in aqueous solution as scoring functions across 33 decoy sets to discriminate native structures or good models in a decoy set. In each set these semiempirical quantum chemistry methods were compared according to enthalpic and geometric criteria. Enthalpically, we compared the methods according to how much lower was the enthalpy of each native, when compared with the mean enthalpy of its set. Geometrically, we compared the methods according to the fraction of native contacts (Q), which is a measure of geometric closeness between an arbitrary structure and the native. For each set and method, the Q of the best decoy was compared with the Q0 , which is the Q of the decoy closest to the native in the set. It was shown that the PM7 method is able to assign larger energy differences between the native structure and the decoys in a set, arguably because of a better description of dispersion interactions, however PM6-DH+ was slightly better than the rest at selecting geometrically good models in the absence of a native structure in the set. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  16. Sequential water molecule binding enthalpies for aqueous nanodrops containing a mono-, di- or trivalent ion and between 20 and 500 water molecules† †Electronic supplementary information (ESI) available: Detailed description of the experimental and computational modeling methods. Isolation, BIRD and UVPD sequence for [Ru(NH3)6]3+·(H2O)169–171, nanoESI spectra for 2+ and 3+ ions. Detailed description of the isotope distribution simulation program. Comparison between experimental and simulated 1+, 2+ and 3+ ion isotope distributions. Wavelength dependence of the deduced sequential binding enthalpies. Comparison of experimental UVPD binding enthalpies to the liquid drop model at different temperatures. Complete list of binding enthalpies and average number of water molecules lost upon UVPD. See DOI: 10.1039/c6sc04957e Click here for additional data file.

    Science.gov (United States)

    Heiles, Sven; Cooper, Richard J.; DiTucci, Matthew J.

    2017-01-01

    Sequential water molecule binding enthalpies, ΔH n,n–1, are important for a detailed understanding of competitive interactions between ions, water and solute molecules, and how these interactions affect physical properties of ion-containing nanodrops that are important in aerosol chemistry. Water molecule binding enthalpies have been measured for small clusters of many different ions, but these values for ion-containing nanodrops containing more than 20 water molecules are scarce. Here, ΔH n,n–1 values are deduced from high-precision ultraviolet photodissociation (UVPD) measurements as a function of ion identity, charge state and cluster size between 20–500 water molecules and for ions with +1, +2 and +3 charges. The ΔH n,n–1 values are obtained from the number of water molecules lost upon photoexcitation at a known wavelength, and modeling of the release of energy into the translational, rotational and vibrational motions of the products. The ΔH n,n–1 values range from 36.82 to 50.21 kJ mol–1. For clusters containing more than ∼250 water molecules, the binding enthalpies are between the bulk heat of vaporization (44.8 kJ mol–1) and the sublimation enthalpy of bulk ice (51.0 kJ mol–1). These values depend on ion charge state for clusters with fewer than 150 water molecules, but there is a negligible dependence at larger size. There is a minimum in the ΔH n,n–1 values that depends on the cluster size and ion charge state, which can be attributed to the competing effects of ion solvation and surface energy. The experimental ΔH n,n–1 values can be fit to the Thomson liquid drop model (TLDM) using bulk ice parameters. By optimizing the surface tension and temperature change of the logarithmic partial pressure for the TLDM, the experimental sequential water molecule binding enthalpies can be fit with an accuracy of ±3.3 kJ mol–1 over the entire range of cluster sizes. PMID:28451364

  17. Toward engineering intra-receptor interactions into bis(crown ethers).

    Science.gov (United States)

    Krause, Martin R; Kubik, Stefan

    2012-03-01

    A synthetic receptor was designed in which cooperative binding of two crown ether moieties to an alkali metal ion simultaneously causes two hydrophobic substituents not involved in direct host-guest interactions to converge. Hydrophobic interactions between these substituents can be expected to contribute to the overall complex stability. Independent binding studies involving two diastereoisomers of this bis(crown ether), one in which intra-receptor interactions between the substituents are potentially possible and one in which they are not, using isothermal titration calorimetry showed that both isomers bind potassium ions in different solvent mixtures with the same overall affinity. Profound differences were observed for each isomer, however, in the enthalpies and entropies of binding, which are consistent with intra-receptor interactions in one compound. These interactions are counteracted by enthalpy-entropy compensation so that no overall improvement in cation affinity could be observed.

  18. A rigidifying salt-bridge favors the activity of thermophilic enzyme at high temperatures at the expense of low-temperature activity.

    Science.gov (United States)

    Lam, Sonia Y; Yeung, Rachel C Y; Yu, Tsz-Ha; Sze, Kong-Hung; Wong, Kam-Bo

    2011-03-01

    Thermophilic enzymes are often less active than their mesophilic homologues at low temperatures. One hypothesis to explain this observation is that the extra stabilizing interactions increase the rigidity of thermophilic enzymes and hence reduce their activity. Here we employed a thermophilic acylphosphatase from Pyrococcus horikoshii and its homologous mesophilic acylphosphatase from human as a model to study how local rigidity of an active-site residue affects the enzymatic activity. Acylphosphatases have a unique structural feature that its conserved active-site arginine residue forms a salt-bridge with the C-terminal carboxyl group only in thermophilic acylphosphatases, but not in mesophilic acylphosphatases. We perturbed the local rigidity of this active-site residue by removing the salt-bridge in the thermophilic acylphosphatase and by introducing the salt-bridge in the mesophilic homologue. The mutagenesis design was confirmed by x-ray crystallography. Removing the salt-bridge in the thermophilic enzyme lowered the activation energy that decreased the activation enthalpy and entropy. Conversely, the introduction of the salt-bridge to the mesophilic homologue increased the activation energy and resulted in increases in both activation enthalpy and entropy. Revealed by molecular dynamics simulations, the unrestrained arginine residue can populate more rotamer conformations, and the loss of this conformational freedom upon the formation of transition state justified the observed reduction in activation entropy. Our results support the conclusion that restricting the active-site flexibility entropically favors the enzymatic activity at high temperatures. However, the accompanying enthalpy-entropy compensation leads to a stronger temperature-dependency of the enzymatic activity, which explains the less active nature of the thermophilic enzymes at low temperatures.

  19. A rigidifying salt-bridge favors the activity of thermophilic enzyme at high temperatures at the expense of low-temperature activity.

    Directory of Open Access Journals (Sweden)

    Sonia Y Lam

    2011-03-01

    Full Text Available Thermophilic enzymes are often less active than their mesophilic homologues at low temperatures. One hypothesis to explain this observation is that the extra stabilizing interactions increase the rigidity of thermophilic enzymes and hence reduce their activity. Here we employed a thermophilic acylphosphatase from Pyrococcus horikoshii and its homologous mesophilic acylphosphatase from human as a model to study how local rigidity of an active-site residue affects the enzymatic activity.Acylphosphatases have a unique structural feature that its conserved active-site arginine residue forms a salt-bridge with the C-terminal carboxyl group only in thermophilic acylphosphatases, but not in mesophilic acylphosphatases. We perturbed the local rigidity of this active-site residue by removing the salt-bridge in the thermophilic acylphosphatase and by introducing the salt-bridge in the mesophilic homologue. The mutagenesis design was confirmed by x-ray crystallography. Removing the salt-bridge in the thermophilic enzyme lowered the activation energy that decreased the activation enthalpy and entropy. Conversely, the introduction of the salt-bridge to the mesophilic homologue increased the activation energy and resulted in increases in both activation enthalpy and entropy. Revealed by molecular dynamics simulations, the unrestrained arginine residue can populate more rotamer conformations, and the loss of this conformational freedom upon the formation of transition state justified the observed reduction in activation entropy.Our results support the conclusion that restricting the active-site flexibility entropically favors the enzymatic activity at high temperatures. However, the accompanying enthalpy-entropy compensation leads to a stronger temperature-dependency of the enzymatic activity, which explains the less active nature of the thermophilic enzymes at low temperatures.

  20. Weak interactions in clobazam-lactose mixtures examined by differential scanning calorimetry: Comparison with the captopril-lactose system

    Energy Technology Data Exchange (ETDEWEB)

    Toscani, S. [Departement de Chimie - UMR 6226, Faculte des Sciences, Universite de Rennes 1, Batiment 10B, 263 avenue du General Leclerc, F-35042 Rennes Cedex (France); Cornevin, L. [Universite de Rennes 1, Faculte de Pharmacie, 2 Avenue Leon Bernard, F-35043 Rennes Cedex (France); Burgot, G., E-mail: Gwenola.burgot@univ-rennes1.fr [Universite de Rennes 1, Faculte de Pharmacie, Laboratoire de Chimie Analytique, EA 1274 ' Mouvement, sports, sante' , 2 Avenue Leon Bernard, F-35043 Rennes Cedex (France); CHGR Rennes, Pole Medico-Technique Pharmacie, F-35703 Rennes Cedex (France)

    2012-09-10

    Highlights: Black-Right-Pointing-Pointer Thermodynamic and kinetic parameters of weak interactions in binary systems by DSC. Black-Right-Pointing-Pointer Energy-barrier decrease for lactose dehydration induced by clobazam. Black-Right-Pointing-Pointer Recrystallisation of metastable liquid clobazam induced by anhydrous alpha lactose. Black-Right-Pointing-Pointer Decrease of lactose dehydration temperature in binary mixtures with captopril. Black-Right-Pointing-Pointer Increase of lactose dehydration enthalpy in binary mixtures with captopril. - Abstract: The thermal behaviour of binary mixtures of two drugs (clobazam and captopril, respectively) and a pharmaceutical excipient (lactose monohydrate) was measured with differential scanning calorimetry to determine thermodynamic and kinetic parameters (dehydration and melting enthalpies and dehydration and glass-transition activation energies) which might be affected by intermolecular interactions. A kinetic study showed that lactose dehydration is not a single-step conversion and that clobazam contributed to reduce the energy barrier for the bulk dehydration of the excipient. On the other hand, the physical interactions between metastable liquid clobazam and crystalline anhydrous {alpha}-lactose obtained from monohydrate dehydration gave rise to the recrystallisation of clobazam. In the captopril-lactose system, the liquid captopril influenced the lactose dehydration: a sharp increase of the dehydration enthalpy and a concurrent reduction of the dehydration temperature were observed. Finally, it turned out that solid-phase transitions were enhanced by the contact with a liquid phase.

  1. Molar enthalpy of mixing and refractive indices of choline chloride-based deep eutectic solvents with water

    International Nuclear Information System (INIS)

    Ma, Chunyan; Guo, Yanhua; Li, Dongxue; Zong, Jianpeng; Ji, Xiaoyan; Liu, Chang

    2017-01-01

    Highlights: • Molar enthalpy of mixing and refractive indices for binary mixtures of different deep eutectic solvents with water. • The Redlich–Kister equation and the NRTL model was used to fit the experimental data. • The NRTL model with fitted parameters were used to predict the vapour pressure and compared with experimental data. - Abstract: The molar enthalpies of mixing were measured for binary systems of choline chloride-based deep eutectic solvents (glycerol, ethylene glycol and malonic acid) with water at 298.15 K and 308.15 K, and atmospheric pressure with an isothermal calorimeter. Refractive indices were also measured at 303.15 K and atmospheric pressure. The binary mixtures of {chcl/glycerol (1:2) + water, chcl/ethylene glycol (1:2) + water} showed exothermic behaviour over the entire range of composition, while the binary mixture of {chcl/malonic acid (1:1) + water} showed endothermic behaviour at first and then changed to be exothermic with the increasing content of chcl/malonic acid (1:1). Experimental refractive indices were fitted with the Redlich–Kister equation, and experimental molar enthalpies of mixing were correlated with the Redlich–Kister equation and the non-random two-liquid (NRTL) model. The NRTL model with the fitted parameters was used to predict the vapour pressures of these three mixtures. For mixtures of {chcl/glycerol (1:2) + water} and {chcl/ethylene glycol (1:2) + water}, the predicted vapour pressures agreed well with the experimental results from the literature. While for mixture of {chcl/malonic acid (1:1) + water}, the predicted vapour pressures showed deviation at the high concentration of chcl/malonic acid (1:1), and this was probably because of the complex molecular interaction between chcl/malonic acid (1:1) and water.

  2. Isothermogravimetric determination of the enthalpies of vaporization of 1-alkyl-3-methylimidazolium ionic liquids.

    Science.gov (United States)

    Luo, Huimin; Baker, Gary A; Dai, Sheng

    2008-08-21

    Vaporization enthalpies for two series of ionic liquids (ILs) composed of 1- n-alkyl-3-methylimidazolium cations, [Imm1+] (m=2, 3, 4, 6, 8, or 10), paired with either the bis(trifluoromethanesulfonyl)amide, [Tf2N-], or the bis(perfluoroethylsulfonyl)amide anion, [beti-], were determined using a simple, convenient, and highly reproducible thermogravimetric approach, and from these values, Hildebrand solubility parameters were estimated. Our results reveal two interesting and unanticipated outcomes: (i) methylation at the C2 position of [Imm1+] affords a significantly higher vaporization enthalpy; (ii) in all cases, the [beti-] anion served to lower the enthalpy of vaporization relative to [Tf2N-]. The widespread availability of the apparatus required for these measurements coupled with the ease of automation suggests the broad potential of this methodology for determining this critical parameter in a multitude of ILs.

  3. Preferential interactions and the effect of protein PEGylation

    DEFF Research Database (Denmark)

    Holm, Louise Stenstrup; Thulstrup, Peter Waaben; Kasimova, Marina Robertovna

    2015-01-01

    enthalpy was decreased to half the value for PEGylated lysozyme. The ratio between calorimetric and van't Hoff enthalpy suggests that our PEGylated lysozyme is a dimer. CONCLUSION/SIGNIFICANCE: The PEGylated model protein displayed similar stability responses to the addition of preferentially active...

  4. Vapor pressures and enthalpies of vaporization of a series of γ and δ-lactones by correlation gas chromatography

    International Nuclear Information System (INIS)

    Kozlovskiy, Mikhail; Gobble, Chase; Chickos, James

    2014-01-01

    Highlights: • The vaporization enthalpies of γ-octanolactone, γ- and δ-undecanolactone and γ and δ-dodecanolactone are reported. • Equations for predicting the vapor pressures over the temperature range T = (298.15 to 350) K are provided. • Vaporization enthalpies are compared to predicted values. - Abstract: The vaporization enthalpies of γ-octanolactone, γ- and δ-undecanolactone and γ and δ-dodecanolactone used commercially as flavor ingredients are reported as are their vapor pressures over the temperature range T = (298.15 to 350) K. Vaporization enthalpies at T = 298.15 K of: (66.0 ± 3.9), (79.4 ± 4.4), (80.1 ± 4.5), (83.9 ± 4.6), and (84.61 ± 4.7) kJ · mol −1 and vapor pressures also at T = 298.15 K of: (2.8 ± 0.9), (0.12 ± 0.05), (0.09 ± 0.04), (0.04 ± 0.02), and (0.03 ± 0.02) Pa, respectively, have been evaluated by correlation gas chromatography experiments. The vaporization enthalpies of the lactones studied are reproduced within ±0.5 kJ · mol −1 using a group additivity scheme reported previously for γ- and δ-lactones. The vaporization enthalpies of the γ- and δ-lactones are compared to a similar series of ω-lactones

  5. Standard enthalpies of formation of selected Rh{sub 2}YZ Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Ming, E-mail: myin1@hawk.iit.edu; Nash, Philip

    2015-11-25

    The standard enthalpies of formation (Δ{sub f}H°) of selected ternary Rh-based Rh{sub 2}YZ (Y = Cu, Fe, Mn, Ni, Ru, Ti, V; Z = Al, Ga, In, Si, Ge, Sn) compounds were measured using high temperature direct reaction calorimetry. The measured standard enthalpies of formation (in kJ/mol of atoms) are, for the Heusler compound Rh{sub 2}MnSn (−40.1 ± 3.6), for the B2-structured compounds: Rh{sub 2}FeAl (−48.5 ± 2.9); Rh{sub 2}MnAl (−72.4 ± 2.7); Rh{sub 2}MnGa (−55.3 ± 2.0); Rh{sub 2}MnIn (−35.3 ± 1.9), for the tetragonal compounds: Rh{sub 2}FeSn (−28.9 ± 1.3); Rh{sub 2}TiAl (−97.6 ± 2.2); Rh{sub 2}TiGa (−79.0 ± 1.8); Rh{sub 2}TiSn (−74.7 ± 3.1). Values are compared with those from first principles calculations in published papers and the Open Quantum Materials Database (OQMD). Lattice parameters of these compounds are determined using X-ray diffraction analysis (XRD). Microstructures were characterized using scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). - Highlights: • Standard enthalpies of formation of Rh{sub 2}YZ were measured using a drop calorimeter. • Measured enthalpies agree with first principles data in general. • Lattice parameters and related phase relationships were consistent with literature data. • Rh{sub 2}TiSn of tI8 structure were reported for the first time.

  6. Enthalpies of formation of 5,6-dihydro-5-methyluracil and 5,6-dihydro-6-methyluracil

    International Nuclear Information System (INIS)

    Amaral, Luísa M.P.F.; Szterner, Piotr; Ribeiro da Silva, Manuel A.V.

    2013-01-01

    Highlights: • Δ c H m ° of two methyl-5,6-dihydrouracils have been determined by combustion calorimetry. • Vapor pressures were measured by the Knudsen effusion technique. • Gas phase enthalpies of formation of methyl-5,6-dihydrouracils, have been derived. -- Abstract: The standard (p° = 0.1 MPa) molar enthalpy of combustion, Δ c H m ° , of two crystalline compounds, 5,6-dihydro-5-methyluracil and 5,6-dihydro-6-methyluracil, were determined, at T = 298.15 K, using a static bomb combustion calorimeter. The vapor pressures as a function of the temperature were measured for those compounds, by the Knudsen effusion technique, and the standard molar enthalpies of sublimation at the mean temperature of the vapor pressure measurements were derived from the Clausius–Clapeyron equation, and corrected to T = 298.15 K using an estimated value for Δ cr g C p,m ° . These values were used to derive the standard molar enthalpies of formation of the two compounds studied, in the condensed and gaseous phases. Some considerations about the relative stability of the two isomers were made and compared with similar compounds

  7. Temperature dependences of saturated vapor pressure and the enthalpy of vaporization of n-pentyl esters of dicarboxylic acids

    Science.gov (United States)

    Portnova, S. V.; Krasnykh, E. L.; Levanova, S. V.

    2016-05-01

    The saturated vapor pressures and enthalpies of vaporization of n-pentyl esters of linear C2-C6 dicarboxylic acids are determined by the transpiration method in the temperature range of 309.2-361.2 K. The dependences of enthalpies of vaporization on the number of carbon atoms in the molecule and on the retention indices have been determined. The predictive capabilities of the existing calculation schemes for estimation of enthalpy of vaporization of the studied compounds have been analyzed.

  8. Application of low enthalpy geothermal energy

    International Nuclear Information System (INIS)

    Stancher, B.; Giannone, G.

    2007-01-01

    Geothermal energy comes from the superficial layers of the Earth's crust; it can be exploited in several ways, depending on its temperature. Many systems have been developed to use this clean and renewable energy resource. This paper deals with a particular application of low enthalpy geothermal energy in Latisana (district of Udine NE, Italy). The Latisana's indoor stadium is equipped with geothermal plant that uses low temperature water (29-30 0 ) to provide heating. Economic analysis shows that the cost of its plant is comparable to the cost powered by other kinds of renewable energy resources

  9. Group vector space method for estimating enthalpy of vaporization of organic compounds at the normal boiling point.

    Science.gov (United States)

    Wenying, Wei; Jinyu, Han; Wen, Xu

    2004-01-01

    The specific position of a group in the molecule has been considered, and a group vector space method for estimating enthalpy of vaporization at the normal boiling point of organic compounds has been developed. Expression for enthalpy of vaporization Delta(vap)H(T(b)) has been established and numerical values of relative group parameters obtained. The average percent deviation of estimation of Delta(vap)H(T(b)) is 1.16, which show that the present method demonstrates significant improvement in applicability to predict the enthalpy of vaporization at the normal boiling point, compared the conventional group methods.

  10. Standard formation enthalpies of mononuclear and cluster oxoanions of boron, silicon and phosphorus

    International Nuclear Information System (INIS)

    Glybin, V.P.; Svirko, L.K.

    2000-01-01

    Standard formation enthalpies of boron, silicon and phosphorus are calculated. For calculations thermochemical method in conjunction with potential energy model of oxoanions in approximation of valence-force field of molecules and crystals are used. In the model of valence-force field ion-covalent crystals are considered as population of clusters of molecular type the number of which is equal to number of translation-nonequivalent atoms in the lattice dipped in nonhomogeneous electrostatic field of long-range interactions. For gaseous oxoanions field created by end oxygen atoms or other ones on which negative charge of anions is localized serves as equivalent of nonhomogeneous electrostatic field. In such approach potential energy of oxoanion is equal to sum of energy of electrostatic repulsion of negatively charged atoms and energy of valent element-oxygen bonds in neutral cluster [ru

  11. Enthalpy measurement of lithium meta-titanate by drop calorimetry and its derived heat capacity

    International Nuclear Information System (INIS)

    Ishioka, Rika; Mukai, Keisuke; Terai, Takayuki; Suzuki, Akihiro

    2013-01-01

    Highlights: • Li 2 TiO 3 was synthesized by a neutralizing method. • Enthalpy of Li 2 TiO 3 was measured by a drop calorimeter. • Heat capacity of Li 2 TiO 3 was derived as a function of temperature. -- Abstract: Enthalpy of Li 2 TiO 3 , which was synthesized by a neutralizing method and its Li/Ti ratio was determined to be Li/Ti ratio (mol/mol) = 1.97, was measured by a drop calorimeter, and its heat capacity was derived as a function of temperature. XRD (X-ray diffraction) analysis of the sample before and after the enthalpy measurement indicated no phase change during the measurement and a single phase of Li 2 TiO 3 was observed. The enthalpy data were expressed as H(T) − H(323.17) (J/g) = 2.2 × 10 −5 ·T 2 + 1.4·T + 2.7 × 10 4 /T − 5.6 × 10 2 (373–1273 K), where T is temperature in K. The heat capacity was calculated as C p (J/g K) = 2.2 × 2 × 10 −5 ·T + 1.4–2.7 × 10 4 /T 2 by differentiating the equation by temperature. These equations have accuracy of 3%

  12. Structural studies of cyclic ureas: 3. Enthalpy of formation of barbital

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Maria das Dores M.C.; Ribeiro da Silva, Manuel A.V.; Freitas, Vera L.S.; Roux, Maria Victoria; Jimenez, Pilar; Temprado, Manuel; Davalos, Juan Z.; Cabildo, Pilar; Claramunt, Rosa M.; Elguero, Jose

    2009-01-01

    A thermochemical and thermophysical study has been carried out for crystalline barbital [5,5'-diethylbarbituric acid]. The thermochemical study was made by static bomb combustion calorimetry, from which the standard (p 0 =0.1MPa) molar enthalpy of formation of the crystalline barbital, at T = 298.15 K, was derived as -(753.0 ± 1.8) kJ . mol -1 . The thermophysical study was made by differential scanning calorimetry over the temperature interval (265 to 470) K. A solid-solid phase transition was found at T = 413.3 K. The vapour pressures of the crystalline barbital were measured at several temperatures between T = (355 and 377) K, by the Knudsen mass-loss effusion technique, from which the standard molar enthalpy of sublimation, at T = 298.15 K was derived as (117.3 ± 0.6) kJ . mol -1 . The combination of the experimental results yielded the standard molar enthalpy of formation of barbital in the gaseous phase, at T = 298.15 K, as -(635.8 ± 1.9) kJ . mol -1 . This value is compared and discussed with our theoretical calculations by several methods (Gaussian-n theories G2 and G3, complete basis set CBS-QB3, density functional B3P86 and B3LYP) by means of atomization and isodesmic reaction schemes.

  13. Enthalpy of dissociation and hydration number of methane hydrate from the Clapeyron equation

    International Nuclear Information System (INIS)

    Anderson, Graydon K.

    2004-01-01

    The enthalpies of the reactions in which methane hydrate is dissociated to methane vapor and either (1) water, or (2) ice are determined by a new analysis using the Clapeyron equation. The difference in enthalpies of the two reactions is used to infer the hydration number at the quadruple point where hydrate, ice, liquid water, and methane vapor coexist. By appropriate corrections, the hydration number at points removed from the quadruple point is also determined. The most important feature of the new analysis is the direct use of the Clapeyron equation. The method avoids the use of certain simplifying assumptions that have compromised the accuracy of previous analyses in which the Clausius-Clapeyron equation was used. The analysis takes into account the finite volumes of all phases, the non-ideality of the vapor phase, and the solubility of methane in water. The results show that the enthalpy of dissociation and hydration number are constant within experimental error over the entire (hydrate, liquid, vapor) coexistence region. The results are more accurate than but entirely consistent with almost all previous studies

  14. Stable isotope studies of some low enthalpy geothermal systems in Kenya

    Science.gov (United States)

    Tole, Mwakio P.

    Oxygen and hydrogen isotope compositions of some low enthalpy geothermal systems in Kenya have been determined. Plots on δ 18O versus δD diagrams show that the compositions do not deviate appreciably from local meteoric water values. This would indicate that local meteoric waters are heated at depth and rise to the surface without much interaction with the country rocks. This is interpreted to be the case for the geothermal systems at Majimoto and Narosura, which have salinities of less than 350 ppm TDS and calculated reservoir temperatures of less than 110°C. The geothermal systems at Kapedo and Homa mountain which have high salinities (> 2 000 ppm TDS) and relatively higher calculated reservoir temperatures (> 150° C) are interpreted to have been operating for long periods of time, such that the rocks through which the present day geothermal waters are circulating have attained isotopic equilibrium with local meteoric waters.

  15. Molar volume, excess enthalpy, and Prigogine-Defay ratio of some silicate glasses with different (P,T) histories.

    Science.gov (United States)

    Wondraczek, Lothar; Behrens, Harald

    2007-10-21

    Structural relaxation in silicate glasses with different (p,T) histories was experimentally examined by differential scanning calorimetry and measurements of molar volume under ambient pressure. Temperature and pressure-dependent rates of changes in molar volume and generation of excess enthalpy were determined for sodium trisilicate, soda lime silicate, and sodium borosilicate (NBS) compositions. From the derived data, Prigogine-Defay ratios are calculated and discussed. Changes of excess enthalpy are governed mainly by changes in short-range structure, as is shown for NBS where boron coordination is highly sensitive to pressure. For all three glasses, it is shown how the relaxation functions that underlie volume, enthalpy, and structural relaxation decouple for changes in cooling rates and pressure of freezing, respectively. The magnitude of the divergence between enthalpy and volume may be related to differences in structural sensitivity to changes in the (p,V,T,t) space on different length scales. The findings suggest that the Prigogine-Defay ratio is related to the magnitude of the discussed decoupling effect.

  16. Enthalpy of Vaporization and Vapor Pressures: An Inexpensive Apparatus

    Science.gov (United States)

    Battino, Rubin; Dolson, David A.; Hall, Michael A.; Letcher, Trevor M.

    2007-01-01

    A simple and inexpensive method to determine the enthalpy of vaporization of liquids by measuring vapor pressure as a function of temperature is described. The vapor pressures measured with the stopcock cell were higher than the literature values and those measured with the sidearm rubber septum cell were both higher and lower than literature…

  17. Excess molar enthalpies of binary mixtures containing 2-decanone or dipentyl ether with long-chain n-alkanes at T = 298.15 K

    International Nuclear Information System (INIS)

    Liao, Wei-Chen; Lin, Ho-mu; Lee, Ming-Jer

    2011-01-01

    Research highlights: → An isothermal titration calorimeter was used for enthalpy data measurment. → The investigated systems are 2-decanone or dipentyl ether with long-chain n-alkanes. → The excess enthalpies are all positive over entire composition range. → The Patel-Teja equation of state with two parameters gives the best representation. - Abstract: Excess molar enthalpies (H E ) of binary mixtures of 2-decanone or dipentyl ether with n-alkanes, including n-dodecane, n-tetradecane, and n-hexadecane, were measured with an isothermal titration calorimeter (ITC) at T = 298.15 K under atmospheric pressure. All the measured H E values are positive over the entire range of composition, indicating that all these mixing processes are endothermic. The H E values varying with composition are found to be nearly symmetric for each binary system. It was also shown that the H E values follow the order of n-hexadecane > n-tetradecane > n-dodecane at a given composition in either the 2-decanone or dipentyl ether binary systems. An empirical Redlich-Kister equation correlated quantitatively these new H E data. The Peng-Robinson and the Patel-Teja equations of state, and the NRTL model were also applied to fit the H E results. Among these tested correlative models, the Patel-Teja equation of state with two adjustable binary interaction parameters generally yielded the best representation.

  18. Enthalpy and the mechanics of AdS black holes

    International Nuclear Information System (INIS)

    Kastor, David; Traschen, Jennie; Ray, Sourya

    2009-01-01

    We present geometric derivations of the Smarr formula for static AdS black holes and an expanded first law that includes variations in the cosmological constant. These two results are further related by a scaling argument based on Euler's theorem. The key new ingredient in the constructions is a two-form potential for the static Killing field. Surface integrals of the Killing potential determine the coefficient of the variation of Λ in the first law. This coefficient is proportional to a finite, effective volume for the region outside the AdS black hole horizon, which can also be interpreted as minus the volume excluded from a spatial slice by the black hole horizon. This effective volume also contributes to the Smarr formula. Since Λ is naturally thought of as a pressure, the new term in the first law has the form of effective volume times change in pressure that arises in the variation of the enthalpy in classical thermodynamics. This and related arguments suggest that the mass of an AdS black hole should be interpreted as the enthalpy of the spacetime.

  19. Direct measurements of the enthalpy of solution of solid solute in supercritical fluids: study on the CO2-naphthalene system.

    Science.gov (United States)

    Zhang, X; Han, B; Zhang, J; Li, H; He, J; Yan, H

    2001-10-01

    A setup for a calorimeter for simultaneously measuring the solubility and the solution enthalpy of solid solutes in supercritical fluids (SCFs) has been established. The enthalpy of solution of naphthalene in supercritical CO2 was measured at 308.15 K in the pressure range from 8.0-11.0 MPa. It was found that the enthalpy of solution (deltaH) was negative in the pressure range from 8.0 to 9.5 MPa, and the absolute value decreased with increasing pressure. In this pressure range, the dissolution of the solute was enthalpy driven. However, the deltaH became positive at pressures higher than 9.5 MPa, and the dissolution was entropy driven. Monte Carlo simulation was performed to analyze the local structural environment of the solvated naphthalene molecules in supercritical CO2 under the experimental conditions for the calorimetric measurements. By combining the enthalpy data and the simulation results, it can be deduced that the energy level of CO2 in the high compressible region is higher than that at higher pressures, which results in the large negative enthalpy of solution and the larger degree of solvent-solute clustering in the high compressible region.

  20. Numerical Investigation of Double-Cone Flows with High Enthalpy Effects

    Science.gov (United States)

    Nompelis, I.; Candler, G. V.

    2009-01-01

    A numerical study of shock/shock and shock/boundary layer interactions generated by a double-cone model that is placed in a hypersonic free-stream is presented. Computational results are compared with the experimental measurements made at the CUBRC LENS facility for nitrogen flows at high enthalpy conditions. The CFD predictions agree well with surface pressure and heat-flux measurements for all but one of the double-cone cases that have been studied by the authors. Unsteadiness is observed in computations of one of the LENS cases, however for this case the experimental measurements show that the flowfield is steady. To understand this discrepancy, several double-cone experiments performed in two different facilities with both air and nitrogen as the working gas are examined in the present study. Computational results agree well with measurements made in both the AEDC tunnel 9 and the CUBRC LENS facility for double-cone flows at low free-stream Reynolds numbers where the flow is steady. It is shown that at higher free- stream pressures the double-cone simulations develop instabilities that result in an unsteady separation.

  1. Enthalpy increment measurements of Sr3Zr2O7(s) and Sr4Zr3O10(s)

    International Nuclear Information System (INIS)

    Banerjee, A.; Dash, S.; Prasad, R.; Venugopal, V.

    1998-01-01

    Enthalpy increment measurements on Sr 3 Zr 2 O 7 (s) and Sr 4 Zr 3 O 10 (s) were carried out using a Calvet micro-calorimeter. The enthalpy increment values were least squares analyzed with the constraints that H 0 (T)-H 0 (298.15 K) at 298.15 K equals to zero and C p 0 (298.15 K) equals to the estimated value. The dependence of enthalpy increment with temperature is given. (orig.)

  2. Standard formation enthalpies of Nasub(2+x)Vsub(6)Osub(16-y) bronze of kappa type

    International Nuclear Information System (INIS)

    Khodos, M.Ya.; Slobodin, B.V.; Surat, L.L.; Fotiev, A.A.

    1980-01-01

    Standard formation enthalpies of sodium oxide vanadium bronze of kappa Nasub(2+x)Vsub(6)Osub(16-y) type of different composition have been determined by the method of solution calorimetry. It has been ascertained that within the limits of homogeneity a standard formation enthalpy decreases insignificantly with the increase of bronze oxygen defectiveness and is a linear function of sodium content

  3. Structure–property relationships in ionic liquids: Influence of branched and cyclic groups on vaporization enthalpies of imidazolium-based ILs

    International Nuclear Information System (INIS)

    Zaitsau, Dzmitry H.; Varfolomeev, Mikhail A.; Verevkin, Sergey P.; Stanton, Alexander D.; Hindman, Michelle S.; Bara, Jason E.

    2016-01-01

    Highlights: • Ionic liquids [Rmim][NTf_2] with iso-alkyl and cyclic substituents were synthesized. • Vaporization enthalpies were measured using quartz-crystal microbalance. • Data consistency was tested by comparison with the homomorph compounds. • Vaporization enthalpies of branched ILs are generally on the same level as for linear. • These findings are useful for the quick estimation of vaporization enthalpies. - Abstract: Ionic liquids (ILs) with branched and cyclic substituents are seldom studied in the literature, and as such there are little to no data characterizing their thermophysical properties. ILs with branched and cyclic substituents are just as convenient to synthesize and study as their counterparts with linear substituents, but the effects of these substituents on IL properties are not yet well-defined due to the preference for linear substituents. Standard molar vaporization enthalpies of six imidazolium based ionic liquids [Rmim][NTf_2] with iso-alkyl and cyclic substituents (R = iso-propyl, iso-butyl, sec-butyl, methylcyclopropyl, cyclopentyl and methylcyclohexyl) were derived from quartz-crystal microbalance (QCM) method. Enthalpies of vaporization measured at elevated temperatures have been adjusted to the reference temperature 298 K and tested for consistency by comparison with the homomorphy alkane, alkylbenzenes and alkyl-imidazoles. It was found that vaporization enthalpies of ILs with the iso-alkyl and cyclic groups are generally on the same level within (±2 to 3) kJ · mol"−"1 significantly compared to the analogous ILs with the imidazolium cation substituted with the linear alkyl substituents of the same chain length. These findings are useful for the quick estimation of vaporization enthalpies of various substituted IL cations (e.g. pyrrolidinium, ammonium, pyridinium, etc.).

  4. Étude de l'énergétique de l'air humide et des paramétrisations physiques de l'atmosphère : propriétés de l'exergie, de l'enthalpie utilisable, de l'entropie et de l'enthalpie

    OpenAIRE

    Marquet , Pascal

    2016-01-01

    This memory describes my old research activities (since 1988) about the application to atmospheric energetics of the concept of "available enthalpy", one of the form of what is called "exergy" in general thermodynamics. This memoir also describes my new research activities, started in 2008, on the study of the Third Law of thermodynamics and the corresponding absolute definition of the moist-air entropy.; Ce mémoire de HDR retrace, d'une part, les recherches engagées depuis 1988 sur les appli...

  5. Coupling geophysical investigation with hydrothermal modeling to constrain the enthalpy classification of a potential geothermal resource.

    Science.gov (United States)

    White, Jeremy T.; Karakhanian, Arkadi; Connor, Chuck; Connor, Laura; Hughes, Joseph D.; Malservisi, Rocco; Wetmore, Paul

    2015-01-01

    An appreciable challenge in volcanology and geothermal resource development is to understand the relationships between volcanic systems and low-enthalpy geothermal resources. The enthalpy of an undeveloped geothermal resource in the Karckar region of Armenia is investigated by coupling geophysical and hydrothermal modeling. The results of 3-dimensional inversion of gravity data provide key inputs into a hydrothermal circulation model of the system and associated hot springs, which is used to evaluate possible geothermal system configurations. Hydraulic and thermal properties are specified using maximum a priori estimates. Limited constraints provided by temperature data collected from an existing down-gradient borehole indicate that the geothermal system can most likely be classified as low-enthalpy and liquid dominated. We find the heat source for the system is likely cooling quartz monzonite intrusions in the shallow subsurface and that meteoric recharge in the pull-apart basin circulates to depth, rises along basin-bounding faults and discharges at the hot springs. While other combinations of subsurface properties and geothermal system configurations may fit the temperature distribution equally well, we demonstrate that the low-enthalpy system is reasonably explained based largely on interpretation of surface geophysical data and relatively simple models.

  6. Influence of Concrete Properties on Molten Core-Concrete Interaction: A Simulation Study

    Directory of Open Access Journals (Sweden)

    Jin-yang Jiang

    2016-01-01

    Full Text Available In a severe nuclear power plant accident, the molten core can be released into the reactor pit and interact with sacrificial concrete. In this paper, a simulation study is presented that aims to address the influence of sacrificial concrete properties on molten core-concrete interaction (MCCI. In particular, based on the MELCOR Code, the ferrosiliceous concrete used in European Pressurized Water Reactor (EPR is taken into account with respect to the different ablation enthalpy and Fe2O3 and H2O contents. Results indicate that the concrete ablation rate as well as the hydrogen generation rate depends much on the concrete ablation enthalpy and Fe2O3 and H2O contents. In practice, the ablation enthalpy of sacrificial concrete is the higher the better, while the Fe2O3 and H2O content of sacrificial concrete is the lower the better.

  7. Dissolved organic carbon--contaminant interaction descriptors found by 3D force field calculations.

    Science.gov (United States)

    Govers, H A J; Krop, H B; Parsons, J R; Tambach, T; Kubicki, J D

    2002-03-01

    Enthalpies of transfer at 300 K of various partitioning processes were calculated in order to study the suitability of 3D force fields for the calculation of partitioning constants. A 3D fulvic acid (FA) model of dissolved organic carbon (DOC) was built in a MM+ force field using AMI atomic charges and geometrical optimization (GO). 3,5-Dichlorobiphenyl (PCB14), 4,4'-dichlorobiphenyl (PCB15), 1,1,1-trichloro-2,2-bis-(4-chlorophenyl)-ethane (PPDDT) and 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (Atrazine) were inserted into different sites and their interaction energies with FA were calculated. Energies of hydration were calculated and subtracted from FA-contaminant interactions of selected sites. The resulting values for the enthalpies of transfer from water to DOC were 2.8, -1.4, -6.4 and 0.0 kcal/mol for PCB 14, PCB15, PPDDT and Atrazine, respectively. The value of PPDDT compared favorably with the experimental value of -5.0 kcal/mol. Prior to this, the method was studied by the calculation of the enthalpies of vaporization and aqueous solution using various force fields. In the MM + force field GO predicted enthalpies of vaporization deviated by +0.7 (PCB14), +3.6 (PCB15) and -0.7 (PPDDT)kcal/mol from experimental data, whereas enthalpies of aqueous solution deviated by -3.6 (PCB14), +5.8 (PCB15) and +3.7 (PPDDT) kcal/mol. Only for PCB14 the wrong sign of this enthalpy value was predicted. Potential advantages and limitations of the approach were discussed.

  8. Heat Effect of the Protonation of Glycine and the Enthalpies of Resolvation of Participating Chemical Species in Water-Dimethylsulfoxide Solvent Mixtures

    Science.gov (United States)

    Isaeva, V. A.; Sharnin, V. A.

    2018-02-01

    Enthalpies of the protonation of glycine in water‒dimethylsulfoxide (DMSO) mixed solvents are determined calorimetrically in the range of DMSO mole fractions of 0.0 to 0.9, at T = 298.15 K and an ionic strength μ = 0.3 (NaClO4). It is established that the protonation of glycine becomes more exothermic with an increasing mole fraction of DMSO, and the enthalpies of resolvation of glycine and glycinium ions in water‒DMSO solvent mixtures are calculated. It is shown that the small changes in the enthalpy of protonation observed at low mole fractions of DMSO are caused by the contributions from the solvation of proton and protonated glycine cancelling each other out. The enthalpy term of the Gibbs energy of the reaction leading to the formation of glycinium ion is estimated along with the enthalpy of resolvation of the reacting species in the water‒DMSO mixed solvent.

  9. The solvent effect on the enthalpy of hydrolysis of cyclic adenosine 3',5'-monophosphate : a quantum chemical study

    NARCIS (Netherlands)

    Scheffers - Sap, Miek; Buck, H.M.

    1978-01-01

    The solvent effect on the enthalpy of hydrolysis has been studied by the Extended-Hückel method for the hydrolysis reactions of cyclic adenosine 3',5'-monophosphate (cyclic 3',5'-AMP) and related cyclic phosphate diesters. The results show that the difference in enthalpy of hydrolysis between cyclic

  10. A proposal to investigate higher enthalpy geothermal systems in the USA

    Science.gov (United States)

    Elders, W. A.

    2013-12-01

    After more than 50 years of development only ~3,400 MWe of electric power is currently being produced from geothermal resources in the USA. That is only about 0.33% of the country's total installed electrical capacity. In spite of the large demonstrated potential of geothermal resources, only ~2,500 MWe of new geothermal electrical capacity are under development, and the growth rate of this environmentally benign energy resource is overshadowed by the rapid increase in the installed capacity of wind and solar energy. Most of the new geothermal developments in the USA involve relatively small, moderate-temperature, geothermal systems. In contrast, development of higher enthalpy geothermal systems for power production has obvious advantages; specifically higher temperatures yield higher power outputs per well so that fewer wells are needed, leading to smaller environmental footprints for a given size of power plant. Disadvantages include that the fact that locations of suitable geothermal systems are restricted to young volcanic terrains, production of very high enthalpy fluids usually requires drilling deeper wells and may require enhanced geothermal (EGS) technology, and drilling deep into hot hostile environments is technologically challenging. However the potential for very favorable economic returns suggests that the USA should begin developing such a program. One approach to mitigating the cost issue is to form a consortium of industry, government and academia to share the costs and broaden the scope an investigation. An excellent example of such a collaboration is the Iceland Deep Drilling Project (IDDP) which is investigating the economic feasibility of producing electricity from supercritical geothermal reservoirs. This industry-government consortium planned to drill a deep well in the volcanic caldera of Krafla in NE Iceland. However drilling had to be terminated at 2.1 km depth when 900°C rhyolite magma flowed into the well. The resultant well was highly

  11. Interomolecular interactions in diluted solutions of potassium iodocuprates (1) in dimethyl ether of diethylene glycol

    International Nuclear Information System (INIS)

    Gorodinskaya, Eh.Ya.; Mel'nikova, N.B.; Yurin, K.V.

    1991-01-01

    The role of donor solvent in the formation of potassium mononuclear iodocuprates (1) in the system CuI-KI-dimethyl ether of diethylene glycol has been considerd. The calculated values of enthalpy, free energy and entropy of viscous flow activation in the range of temperatures 298-318 K for the solutions testify to decomposition of the solvent structure. Negative deviations of mole volumes from the additivity rule characterized strong molecular interaction

  12. Excess enthalpies of the ternary mixtures: {tetrahydrofuran + 3-methylpentane + (octane or decane)} at the temperature 298.15 K

    International Nuclear Information System (INIS)

    Wang Zhaohui; Benson, George C.; Lu, Benjamin C.-Y.

    2003-01-01

    Measurements of excess molar enthalpies at the temperature 298.15 K in a flow microcalorimeter, are reported for the two ternary mixtures {X 1 C 4 H 8 O + X 2 CH 3 CH 2 CH(CH 3 )CH 2 CH 3 + (1-X 1 -X 2 )CH 3 (CH 2 ) v-2 CH 3 } with v=8 and 10. Smooth representations of the results are described and used to construct constant-enthalpy contours on Roozeboom diagrams. It is shown that useful estimates of the ternary enthalpies can be obtained from the Liebermann-Fried model, using only the physical properties of the components and their binary mixtures

  13. Methanol wetting enthalpy on few-layer graphene decorated hierarchical carbon foam for cooling applications

    Energy Technology Data Exchange (ETDEWEB)

    Paul, R., E-mail: paul24@purdue.edu [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Zemlyanov, D. [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Voevodin, A.A.; Roy, A.K. [Materials and Manufacturing Directorate, Air Force Research Laboratory, WPAFB, OH 45433 (United States); Fisher, T.S. [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Department of Mechanical Engineering, Purdue University, West Lafayette, IN 47907 (United States)

    2014-12-01

    Vertical few-layer thick graphene petals are grown on macro-porous carbon foam surfaces having an intrinsic open porosity of 75%. This provides a hierarchical porous structure with a potential for surface adsorption/desorption or wetting/dewetting based thermal energy storage applications. Carbon foams have a combined advantage of large surface area and high thermal conductivity critical for thermal energy storage, but they are prone to oxidation and exhibit low adsorption enthalpies for lightweight hydrocarbons. Here we report graphene petal decoration of carbon foam surfaces and subsequent chemical modification through boron nitride incorporation in hexagonal carbon planes of both carbon foams and graphene petals. This chemically reactive hierarchical structure is characterized with FESEM, Raman, XRD, and XPS measurements. Methanol wetting enthalpy of this three-dimensional hierarchical material was measured with a solution calorimeter, and had shown a six fold increase (from 78 to 522 J/g of foam) as compared to the carbon foam prior to the surface modification. Influences of petal decoration on the surface morphology of carbon foam, BN chemical modification, structure and stoichiometry of the hierarchical material surface, and methanol wetting enthalpy improvement are discussed in detail. The applicability of this hierarchical porous material for thermal energy applications is established. - Highlights: • 500 nm thick few layer graphene petals decoration vertically on macroporous carbon foam surface. • Microwave heating assisted chemical treatment for boron-nitride modification. • Defective petals edges due to boron nitride domain formation. • 20 at. % boron and nitrogen incorporation. • Six fold increase in methanol wetting enthalpy on boron-nitride modification.

  14. Methanol wetting enthalpy on few-layer graphene decorated hierarchical carbon foam for cooling applications

    International Nuclear Information System (INIS)

    Paul, R.; Zemlyanov, D.; Voevodin, A.A.; Roy, A.K.; Fisher, T.S.

    2014-01-01

    Vertical few-layer thick graphene petals are grown on macro-porous carbon foam surfaces having an intrinsic open porosity of 75%. This provides a hierarchical porous structure with a potential for surface adsorption/desorption or wetting/dewetting based thermal energy storage applications. Carbon foams have a combined advantage of large surface area and high thermal conductivity critical for thermal energy storage, but they are prone to oxidation and exhibit low adsorption enthalpies for lightweight hydrocarbons. Here we report graphene petal decoration of carbon foam surfaces and subsequent chemical modification through boron nitride incorporation in hexagonal carbon planes of both carbon foams and graphene petals. This chemically reactive hierarchical structure is characterized with FESEM, Raman, XRD, and XPS measurements. Methanol wetting enthalpy of this three-dimensional hierarchical material was measured with a solution calorimeter, and had shown a six fold increase (from 78 to 522 J/g of foam) as compared to the carbon foam prior to the surface modification. Influences of petal decoration on the surface morphology of carbon foam, BN chemical modification, structure and stoichiometry of the hierarchical material surface, and methanol wetting enthalpy improvement are discussed in detail. The applicability of this hierarchical porous material for thermal energy applications is established. - Highlights: • 500 nm thick few layer graphene petals decoration vertically on macroporous carbon foam surface. • Microwave heating assisted chemical treatment for boron-nitride modification. • Defective petals edges due to boron nitride domain formation. • 20 at. % boron and nitrogen incorporation. • Six fold increase in methanol wetting enthalpy on boron-nitride modification

  15. The enthalpies of formation of neutral and charged components of saturated vapor over europium dichloride

    International Nuclear Information System (INIS)

    Pogrebnoj, A.M.; Kudin, L.S.

    2003-01-01

    Composition of saturated vapor over europium dichloride was studied by the method of high-temperature mass spectrometry in the temperature range of 1154 - 1267 K. For neutral components of the vapor, represented by monomer and dimer molecules, partial pressures were determined. Enthalpies of sublimation of europium dichloride Δ s H 0 (298 K) as monomers (338 ± 9) and dimers (407 ± 20 kJ/mol) were calculated. Equilibrium constants of ion-molecular and ion-ionic reactions were measured, their enthalpies being ascertained. Enthalpies of formation of molecules and ions Δ f H 0 (298 K) were calculated: -486 ± 11 (EuCl 2 ), -1242 ± 22 (Eu 2 Cl 4 ), 1 ± 12 (Eu 2 Cl 2 + ), -347 ± 20 (Eu 2 Cl 3 + ), -1111 ± 42 (Eu 3 Cl 5 + ), -975 ± 20 (EuCl 3 - ), -1309 ± 17(EuCl 4 - ), -1734 ± 20 (Eu 2 Cl 5 - ) kJ/mol [ru

  16. Solid-State Characterization and Relative Formation Enthalpies To Evaluate Stability of Cocrystals of an Antidiabetic Drug.

    Science.gov (United States)

    Duggirala, Naga Kiran; Frericks Schmidt, Heather L; Lei, Zhaohui; Zaworotko, Michael J; Krzyzaniak, Joseph F; Arora, Kapildev K

    2018-05-07

    The current study integrates formation enthalpy and traditional slurry experiments to quickly assess the physical stability of cocrystal drug substance candidates for their potential to support drug development. Cocrystals of an antidiabetic drug (GKA) with nicotinamide (NMA), vanillic acid (VLA), and ethyl vanillin (EVL) were prepared and characterized by powder X-ray diffractometry (PXRD), spectroscopic, and thermal techniques. The formation enthalpies of the cocrystals, and their physical mixtures (GKA + coformer) were measured by the differential scanning calorimetry (DSC) method reported by Zhang et al. [ Cryst. Growth Des. 2012 , 12 ( 8 ), 4090 - 4097 ]. The experimentally measured differences in the relative formation enthalpies obtained by integrating the heat flow of each cocrystal against the respective physical mixture were correlated to the physical stability of the cocrystals in the solid state. The relative formation enthalpies of all of the cocrystals studied suggest that the cocrystals are not physically stable at room temperature versus their physical mixtures. To further address relative stability, the cocrystals were slurried in 30% v/v aqueous ethanol, and it was observed that all of the cocrystals revert to GKA within 48 h at room temperature. The slurry experiments are consistent with the relative instability of the cocrystals with respect to their physical mixtures suggested by the DSC results.

  17. Spectroscopic investigation of the effect of salt on binding of tartrazine with two homologous serum albumins: quantification by use of the Debye-Hückel limiting law and observation of enthalpy-entropy compensation.

    Science.gov (United States)

    Bolel, Priyanka; Datta, Shubhashis; Mahapatra, Niharendu; Halder, Mintu

    2012-08-30

    Formation of ion pair between charged molecule and protein can lead to interesting biochemical phenomena. We report the evolution of thermodynamics of the binding of tartrazine, a negatively charged azo colorant, and serum albumins with salt. The dye binds predominantly electrostatically in low buffer strengths; however, on increasing salt concentration, affinity decreases considerably. The calculated thermodynamic parameters in high salt indicate manifestation of nonelectrostatic interactions, namely, van der Waals force and hydrogen bonding. Site-marker competitive binding studies and docking simulations indicate that the dye binds with HSA in the warfarin site and with BSA at the interface of warfarin and ibuprofen binding sites. The docked poses indicate nearby amino acid positive side chains, which are possibly responsible for electrostatic interaction. Using the Debye-Hückel interionic attraction theory for binding equilibria, it is shown that, for electrostatic binding the calculated free energy change increases linearly with square root of ionic strength. Also UV-vis, fluorescence, CD data indicate a decrease of interaction with salt concentration. This study quantitatively relates how ionic strength modulates the strength of the protein-ligand electrostatic interaction. The binding enthalpy and entropy have been found to compensate one another. The enthalpy-entropy compensation (EEC), general property of weak intermolecular interactions, has been discussed.

  18. Free Energy, Enthalpy and Entropy from Implicit Solvent End-Point Simulations.

    Science.gov (United States)

    Fogolari, Federico; Corazza, Alessandra; Esposito, Gennaro

    2018-01-01

    Free energy is the key quantity to describe the thermodynamics of biological systems. In this perspective we consider the calculation of free energy, enthalpy and entropy from end-point molecular dynamics simulations. Since the enthalpy may be calculated as the ensemble average over equilibrated simulation snapshots the difficulties related to free energy calculation are ultimately related to the calculation of the entropy of the system and in particular of the solvent entropy. In the last two decades implicit solvent models have been used to circumvent the problem and to take into account solvent entropy implicitly in the solvation terms. More recently outstanding advancement in both implicit solvent models and in entropy calculations are making the goal of free energy estimation from end-point simulations more feasible than ever before. We review briefly the basic theory and discuss the advancements in light of practical applications.

  19. Free Energy, Enthalpy and Entropy from Implicit Solvent End-Point Simulations

    Directory of Open Access Journals (Sweden)

    Federico Fogolari

    2018-02-01

    Full Text Available Free energy is the key quantity to describe the thermodynamics of biological systems. In this perspective we consider the calculation of free energy, enthalpy and entropy from end-point molecular dynamics simulations. Since the enthalpy may be calculated as the ensemble average over equilibrated simulation snapshots the difficulties related to free energy calculation are ultimately related to the calculation of the entropy of the system and in particular of the solvent entropy. In the last two decades implicit solvent models have been used to circumvent the problem and to take into account solvent entropy implicitly in the solvation terms. More recently outstanding advancement in both implicit solvent models and in entropy calculations are making the goal of free energy estimation from end-point simulations more feasible than ever before. We review briefly the basic theory and discuss the advancements in light of practical applications.

  20. Free-flight measurement technique in the free-piston high-enthalpy shock tunnel

    Science.gov (United States)

    Tanno, H.; Komuro, T.; Sato, K.; Fujita, K.; Laurence, S. J.

    2014-04-01

    A novel multi-component force-measurement technique has been developed and implemented at the impulse facility JAXA-HIEST, in which the test model is completely unrestrained during the test and thus experiences free-flight conditions for a period on the order of milliseconds. Advantages over conventional free-flight techniques include the complete absence of aerodynamic interference from a model support system and less variation in model position and attitude during the test itself. A miniature on-board data recorder, which was a key technology for this technique, was also developed in order to acquire and store the measured data. The technique was demonstrated in a HIEST wind-tunnel test campaign in which three-component aerodynamic force measurement was performed on a blunted cone of length 316 mm, total mass 19.75 kg, and moment of inertia 0.152 kgm2. During the test campaign, axial force, normal forces, and pitching moment coefficients were obtained at angles of attack from 14° to 32° under two conditions: H0 = 4 MJ/kg, P0 = 14 MPa; and H0 = 16 MJ/kg, P0 = 16 MPa. For the first, low-enthalpy condition, the test flow was considered a perfect gas; measurements were thus directly compared with those obtained in a conventional blow-down wind tunnel (JAXA-HWT2) to evaluate the accuracy of the technique. The second test condition was a high-enthalpy condition in which 85% of the oxygen molecules were expected to be dissociated; high-temperature real-gas effects were therefore evaluated by comparison with results obtained in perfect-gas conditions. The precision of the present measurements was evaluated through an uncertainty analysis, which showed the aerodynamic coefficients in the HIEST low enthalpy test agreeing well with those of JAXA-HWT2. The pitching-moment coefficient, however, showed significant differences between low- and high-enthalpy tests. These differences are thought to result from high-temperature real-gas effects.

  1. Investigating ultra high-enthalpy geothermal systems: a collaborative initiative to promote scientific opportunities

    Science.gov (United States)

    Elders, W. A.; Nielson, D.; Schiffman, P.; Schriener, A., Jr.

    2014-12-01

    Scientists, engineers, and policy makers gathered at a workshop in the San Bernardino Mountains of southern California in October 2013 to discuss the science and technology involved in developing high-enthalpy geothermal fields. A typical high-enthalpy geothermal well between 2000 and 3000 m deep produces a mixture of hot water and steam at 200-300 °C that can be used to generate about 5-10 MWe of electric power. The theme of the workshop was to explore the feasibility and economic potential of increasing the power output of geothermal wells by an order of magnitude by drilling deeper to reach much higher pressures and temperatures. Development of higher enthalpy geothermal systems for power production has obvious advantages; specifically higher temperatures yield higher power outputs per well so that fewer wells are needed, leading to smaller environmental footprints for a given size of power plant. Plans for resource assessment and drilling in such higher enthalpy areas are already underway in Iceland, New Zealand, and Japan. There is considerable potential for similar developments in other countries that already have a large production of electricity from geothermal steam, such as Mexico, the Philippines, Indonesia, Italy, and the USA. However drilling deeper involves technical and economic challenges. One approach to mitigating the cost issue is to form a consortium of industry, government and academia to share the costs and broaden the scope of investigation. An excellent example of such collaboration is the Iceland Deep Drilling Project (IDDP), which is investigating the economic feasibility of producing electricity from supercritical geothermal reservoirs, and this approach could serve as model for future developments elsewhere. A planning committee was formed to explore creating a similar initiative in the USA.

  2. The enthalpies of formation of alkyl carbamates: Experimental and computational redetermination

    International Nuclear Information System (INIS)

    Santos, Ana Filipa L.O.M.; Ribeiro da Silva, Manuel A.V.

    2013-01-01

    Highlights: ► Combustion calorimetry was used to redetermine Δ f H m o (cr) of methyl and ethyl carbamates. ► Δ cr g H m o of methyl and ethyl carbamates were redetermined by Calvet Microcalorimetry. ► Gas-phase Δ f H m o of the studied compounds have been derived from the experimental values of Δ f H m o (cr) and Δ cr g H m o . ► Gas-phase Δ f H m o of the studied compounds have been calculated by computational thermochemistry. ► The obtained Δ f H m o (g) for the alkylcarbamates are discussed versus literature values for the same compounds. - Abstract: In the present work, a redetermination of thermochemical data of methyl carbamate and ethyl carbamate was performed by both experimental and computational techniques. Their gas-phase standard (p o = 0.1 MPa) molar enthalpies of formation, Δ f H m o (g), at T = 298.15 K, were derived from the standard molar enthalpies of formation, in the crystalline phase, Δ f H m o (cr), and from the standard molar enthalpies of sublimation, Δ cr g H m o at T = 298.15 K, measured, respectively, by static bomb combustion calorimetry and high temperature Calvet microcalorimetry. The experimental results were compared with computational data, calculated at the G3(MP2)//B3LYP level, as well as with values reported in the literature. At the B3LYP/6-31G(d) level of theory, the molecular structure of both carbamates was obtained.

  3. Thermally decarboxylated sodium bicarbonate: Interactions with water vapour, calorimetric study

    Directory of Open Access Journals (Sweden)

    Natalia Volkova

    2013-06-01

    Full Text Available Isothermal titration calorimetry (ITC was used to study interactions between water vapour and the surface of thermally converted sodium bicarbonate (NaHCO3. The decarboxylation degree of the samples was varied from 3% to 35% and the humidity range was 54–100%. The obtained enthalpy values were all exothermic and showed a positive linear correlation with decarboxylation degrees for each humidity studied. The critical humidity, 75% (RHo, was determined as the inflection point on a plot of the mean−ΔHkJ/mole Na2CO3 against RH. Humidities above the critical humidity lead to complete surface dissolution. The water uptake (m was determined after each calorimetric experiment, complementing the enthalpy data. A mechanism of water vapour interaction with decarboxylated samples, including the formation of trona and Wegscheider’s salt on the bicarbonate surface is proposed for humidities below RHo. Keywords: Isothermal titration calorimetry, Sodium bicarbonate, Sodium carbonate, Trona salt, Wegscheider’s salt, Enthalpy, Relative humidity, Pyrolytic decarboxylation

  4. The enthalpy of solid scandium in the temperature range 406 - 1812 K

    International Nuclear Information System (INIS)

    Lyapunov, K.M.; Baginskij, A.V.; Stankus, S.V.

    2001-01-01

    Enthalpy of pure scandium was measured on massive calorimeter in the range from 406 to 1812 K by mixing method. The enthalpy of face centered close cubic lattice - body centered cubic lattice transformation is equal to ΔH t 4068 J/mol. Obtained value within the limits of error is compatible with the results given earlier (4009 J/mol). The dependence of the middle specific heat of scandium C p (T) on the temperature was shown in correlation with the results of other works. The results of the conducted experiments reinforce the conclusion made earlier about an absence (or a little) in the decomposition of an anharmonic component of the oscillation specific heat of scandium C p a (T) members proportional to the first or the second degrees of temperature [ru

  5. Evaluation of enthalpy of interfacial reactions from temperature dependency of interfacial equilibrium

    International Nuclear Information System (INIS)

    Kallay, Nikola; Cop, Ana

    2005-01-01

    Temperature dependency of equilibrium at metal oxide-aqueous electrolyte solution interface was analyzed by numerical simulation. Derivations of inner surface potential with respect to temperature were performed at constant values of several different parameters. When surface charge density in inner plane was kept constant the reasonable results were obtained, i.e. the electrostatic contribution to enthalpy of protonation of amphotheric surface sites was found to be positive in the pH region below the point of zero potential and negative above this point. All other examined possibilities produced opposite results. Derivation of empirical interfacial equilibrium constant at constant surface potential indicated that electrostatic effect on protonation entropy is negligible and that electrostatic contributions to reaction Gibbs energy and enthalpy are equal and directly related to the surface potential in the inner plane

  6. Isotope effect in enthalpy of solvation of the lithium ion

    International Nuclear Information System (INIS)

    Krestov, G.A.; Egorov, G.I.; Korolev, V.P.

    1989-01-01

    At 298.15 K, the authors determined the standard enthalpies of solution for 6 LiCl and 7 LiCl in water, heavy water, dimethylsulfoxide (DMSO) and aqueous solutions of DMSO. The authors have established that solvation of 6 Li + is differentiated in water and DMSO to a greater degree than for 7 Li +

  7. Experimental Determination of the Formation Enthalpy of Calcium Cobaltate from Sol–Gel Precursors

    DEFF Research Database (Denmark)

    Holgate, Tim C.; Wu, NingYu; Van Nong, Ngo

    2017-01-01

    Calcium cobaltate (Ca3Co4O9) remains one of the most promising p-type oxide materials for high-temperature thermoelectric energy conversion. While much progress has been made in refining our understanding of the unique structure of the material, as well as optimization of the transport properties...... as observations of its decomposition into the Ca3Co2O6 phase. The reaction enthalpy of forming Ca3Co4O9 from CaCO3 and Co3O4 sol–gel precursors was determined to be +284 (±2%) kJ/mol, leading to a standard enthalpy of Ca3Co4O9 of −3307 (±3.5%) kJ/mol....

  8. Oxidation potentials, Gibbs energies, enthalpies and entropies of actinide ions in aqueous solutions

    International Nuclear Information System (INIS)

    1977-01-01

    The values of the Gibbs energy, enthalpy, and entropy of different actinide ions, thermodynamic characteristics of the processes of hydration of these ions, and the presently known ionization potentials of actinides are given. The enthalpy and entropy components of the oxidation potentials of actinide elements are considered. The curves of the dependence of the Gibbs energy of ion formation on the atomic number of the element and the Frost diagrams are analyzed. The diagram proposed by Frost represents the graphical dependence of the Gibbs energy of hydrated ions on the degree of oxidation of the element. Using the Frost diagram it is easy to establish whether a given ion is stable to disproportioning

  9. Accurate Experimental and Theoretical Enthalpies of Association of TiCl4 with Typical Lewis Bases Used in Heterogeneous Ziegler-Natta Catalysis

    KAUST Repository

    Credendino, Raffaele

    2017-09-18

    Adducts of TiCl4 with Lewis bases used as internal or external donors in heterogeneous Ziegler-Natta (ZN) catalysis represents a fundamental interaction contributing to the final composition of MgCl2 supported ZN-catalysts. This study presents the accurate experimental evaluation, from titration calorimetry, of the formation enthalpy of TiCl4 adducts with 15 Lewis bases of industrial interests. In addition, we report accurate energies of association of TiCl4 with the same Lewis bases from calculations at the DLPNO-CCSD(T) level of theory. These accurate experimental and theoretical association values are compared with selected methods based on density functional theory (DFT) in combination with popular continuum solvation models. Calculations suggest that the PBE-D3, and M06 functionals in combination with a triple-ζ plus polarization quality basis set provide the best performance when the basis set superposition error (BSSE) is not removed from the association energies. Cleaning the association energies by the BSSE with the counterpoise protocol suggests the B3LYP-D3, TPSS-D3 and M06L as the best performing functionals. Introducing solvent effects with the PCM and SMD continuum solvation models allows comparing the DFT based association enthalpies with the experimental values obtained from titration calorimetry. Both solvation models in combination with the PBE-D3, PBE0-D3, B3LYP-D3, TPSS-D3, M06L, and M06 functionals provide association enthalpies close to the experimental values with MUEs in range 10 – 15 kJ/mol.

  10. Diluent and extractant effects on the enthalpy of extraction of uranium(VI) and americium(III) nitrates by trialkyl phosphates

    International Nuclear Information System (INIS)

    Srinivasan, T.G.; Vasudeva Rao, P.R.; Sood, D.D.

    1998-01-01

    The effect of various diluents such as n-hexane, n-heptane n-octane, isooctane, n-decane, n-undecane, n-dodecane, n-tetradecane, n-hexadecane, cyclohexane, benzene, toluene, p-xylene, mesitylene and o-dichlorobenzene on the enthalpy of extraction of uranyl nitrate by tri-n-amyl phosphate (TAP) over the temperature range 283 K--333 K has been studied. The results indicate that the enthalpy of extraction does not vary significantly with the diluents studied. Also enthalpies of extraction of uranyl nitrate and americium(III) nitrate by neutral organo phosphorous extractants such as tri-n-butyl phosphate (TBP), tri-n-amyl phosphate (TAP), tri-sec-butyl phosphate (TsBP), tri-isoamyl phosphate (TiAP) and tri-n-hexyl phosphate (THP) have been studied. An attempt has been made to explain the trends, on the basis of the nature of the solvate formed and the different terms which contribute to the overall enthalpy change

  11. Enthalpies of potassium iodide dissolution in dimethyl acetamide mixtures with water

    International Nuclear Information System (INIS)

    Privalova, N.M.; Gritsenko, S.I.; Vorob'ev, A.F.

    1986-01-01

    Enthalpies of potassium iodide dissolution in mixed dimethyl acetamide - water solvent at 298.15 K in the whole range of dimethyl acetamide compositions are measured by the calorimetric method. From the plots of KI dissolution enthalpy dependence and dependence of experimental ΔH p∞ 0 value deviations from calculational ones on solvent composition, as well as from the results of calculation of solvate shell composition of potassium iodide ions in the mixed solvent, it is obvious that in the region of 0-15 mol% concentrations of dimethyl acetamide insufficient enrichment of solvate ion shells by dimethyl acetamide (DMAA) occurs, in the region of 15-40 mol% DMAA compositions enrichment of solvate shells of ions by water occurs, in the region of 40-100 mol% DMAA enrichment of solvate ion shells by the organic component in comparison with mixture compostion occurs. Maximum enrichment of solvate ion shells by mixture components in three above mentioned regions of the mixed solvent occurs at 10, 30 and 80 mol% DMAA concentrations

  12. Influence of tribomechanical micronization and hydrocolloids addition on enthalpy and apparent specific heat of whey protein model solutions

    Directory of Open Access Journals (Sweden)

    Zoran Herceg

    2002-01-01

    Full Text Available Knowledge of thermophysical properties, especially the phase transitions temperature, specific heat and enthalpy, are essential in defining the freezing process parameters as well as storage conditions of frozen food. In this work thermophysical properties of 10% model solutions prepared with 60% whey protein concentrate (WPC with various hydrocolloids addition (HVEP, YO-EH, YO-L i YO-M were investigated. Powdered whey protein concentrate was treated in equipment for tribomechanical micronization and activation at 40000 rpm (Patent: PCT/1B99/00757 just before model solutions preparation. Particle size analysis was performed using Frich –laser particle sizer “analysette 22”. The phase transition temperatures were determined by differential thermal analysis (DTA, while specific heat and enthalpy were calculated according to several mathematical equations. The results have shown that, due to tribomechanical treatment, certain changes in thermophysical and energetic properties of materials occurred. Tribomechanical treatment affects changes in granulometrical composition of WPC which result in higher abilities of reactions with hydrocolloids in model solutions and significant changes in thermophysical properties of the mentioned models.

  13. SGC method for predicting the standard enthalpy of formation of pure compounds from their molecular structures

    International Nuclear Information System (INIS)

    Albahri, Tareq A.; Aljasmi, Abdulla F.

    2013-01-01

    Highlights: • ΔH° f is predicted from the molecular structure of the compounds alone. • ANN-SGC model predicts ΔH° f with a correlation coefficient of 0.99. • ANN-MNLR model predicts ΔH° f with a correlation coefficient of 0.90. • Better definition of the atom-type molecular groups is presented. • The method is better than others in terms of combined simplicity, accuracy and generality. - Abstract: A theoretical method for predicting the standard enthalpy of formation of pure compounds from various chemical families is presented. Back propagation artificial neural networks were used to investigate several structural group contribution (SGC) methods available in literature. The networks were used to probe the structural groups that have significant contribution to the overall enthalpy of formation property of pure compounds and arrive at the set of groups that can best represent the enthalpy of formation for about 584 substances. The 51 atom-type structural groups listed provide better definitions of group contributions than others in the literature. The proposed method can predict the standard enthalpy of formation of pure compounds with an AAD of 11.38 kJ/mol and a correlation coefficient of 0.9934 from only their molecular structure. The results are further compared with those of the traditional SGC method based on MNLR as well as other methods in the literature

  14. Enthalpic characteristics of interactions occurring between an ascorbic acid and some saccharides in aqueous solutions

    International Nuclear Information System (INIS)

    Terekhova, Irina V.; Kulikov, Oleg V.; Titova, Elena S.

    2004-01-01

    The enthalpies of solution of mono- and disaccharides were measured in water and aqueous ascorbic acid solutions at 298.15 K using a calorimeter of solution. Enthalpies of transfer of saccharides from water to aqueous ascorbic acid solutions were derived, and enthalpic coefficients of pair interaction h xy were calculated according to MacMillan-Mayer theory. Interactions of ascorbic acid with D-fructose and sucrose are energetically favorable and characterized by negative h xy coefficients while h xy for the interactions occurring between ascorbic acid and α-D glucose, D-galactose and maltose are positive. The obtained results are interpreted in terms of the influence of structure and solvation of solutes on the thermodynamic parameters of their interaction in solutions

  15. Accurate Gas Phase Formation Enthalpies of Alloys and Refractories Decomposition Products

    KAUST Repository

    Minenkov, Yury; Sliznev, Valery V.; Cavallo, Luigi

    2017-01-01

    predicted the ΔHf values of a series of these compounds having a group 4, 6, or 14 metal. The ΔHf values in question were derived within a composite Feller-Dixon-Peterson (FDP) scheme based protocol that combines the DLPNO-CCSD(T) enthalpy of ad hoc designed

  16. Electrical resistivities and solvation enthalpies for solutions of salts in liquid alkali metals

    International Nuclear Information System (INIS)

    Hubberstey, P.; Dadd, A.T.

    1982-01-01

    An empirical correlation is shown to exist between the resistivity coefficients drho/dc for solutes in liquid alkali metals and the corresponding solvation enthalpies Usub(solvn) of the neutral gaseous solute species. Qualitative arguments based on an electrostatic solvation model in which the negative solute atom is surrounded by a solvation sphere of positive solvent ion cores are used to show that both parameters are dependent on the charge density of the solute atom and hence on the extent of charge transfer from solvent to solute. Thus as the charge density of the solute increases, the solvation enthalpy increases regularly and the resistivity coefficients pass through a maximum to give the observed approximately parabolic drho/dc versus Usub(solvn) relationship. (Auth.)

  17. Enthalpy-Entropy Compensation in the Binding of Modulators at Ionotropic Glutamate Receptor GluA2

    DEFF Research Database (Denmark)

    Krintel, Christian; Francotte, Pierre; Pickering, Darryl S

    2016-01-01

    of 5 was examined with x-ray crystallography, showing that the only change compared to that of earlier compounds was the orientation of Ser-497 pointing toward the hydroxyl group of 5. The favorable enthalpy can be explained by the formation of a hydrogen bond from the side-chain hydroxyl group of Ser...... of modulators BPAM97 (2) and BPAM344 (3) into a hydroxyl group (BPAM557 (4) and BPAM521 (5), respectively), leads to a more favorable binding enthalpy (ΔH, kcal/mol) from −4.9 (2) and −7.5 (3) to −6.2 (4) and −14.5 (5), but also a less favorable binding entropy (−TΔS, kcal/mol) from −2.3 (2) and −1.3 (3) to −0......-497 to the hydroxyl group of 5, whereas the unfavorable entropy might be due to desolvation effects combined with a conformational restriction of Ser-497 and 5. In summary, this study shows a remarkable example of enthalpy-entropy compensation in drug development accompanied with a likely explanation...

  18. The intermetallic ThRh5: microstructure and enthalpy increments

    International Nuclear Information System (INIS)

    Banerjee, Aparna; Joshi, A.R.; Kaity, Santu; Mishra, R.; Roy, S.B.

    2013-01-01

    Actinide intermetallics are one of the most interesting and important series of compounds. Thermochemistry of these compounds play significant role in understand the nature of bonding in alloys and nuclear fuel performance. In the present paper we report synthesis and characterization of thorium based intermetallic compound ThRh 5 (s) by SEM/EDX technique. The mechanical properties and enthalpy increment as a function of temperature of the alloy has been measured. (author)

  19. Problem-based learning in teaching chemistry: enthalpy changes in systems

    Science.gov (United States)

    Ayyildiz, Yildizay; Tarhan, Leman

    2018-01-01

    Problem-based learning (PBL) as a teaching strategy has recently become quite widespread in especially chemistry classes. Research has found that students, from elementary through college, have many alternative conceptions regarding enthalpy changes in systems. Although there are several studies focused on identifying student alternative conceptions and misunderstandings of this subject, studies on preventing the formation of these alternative conceptions are limited.

  20. Combustion energies and standard molar enthalpies of formation for the complexes of the first-row transitional metal chlorides with L-α-histidine

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Seven novel solid complexes of the first-row transitional metal with L-α-histidine were synthesized, and their compositions were determined. The constant-volume combustion energies of the complexes were measured by a precision rotation bomb calorimeter. The standard molar enthalpies of combustion and the standard molar enthalpies of formation were calculated. The results indicated thatthe plots of the standard enthalpies of formation against the atomic number of the metal show a regularity of zigzag.

  1. Investigation of variation of additional enthalpy of proteins with respect to pH by statistical mechanical methods

    International Nuclear Information System (INIS)

    Oylumoglu, G.

    2005-01-01

    In this study variation of additional enthalpy with respect to pH has been investigated by the statistical mechanical methods.. To bring up the additional effect, the partition function of the proteins are calculated by single protein molecule approximation. From the partition function, free energies of the proteins are obtained and by this way additional free energy has been used in the calculation of the terms in the thermodynamical quantity. Additional enthalpy H D has been obtained by taking effective electric field E and constant dipole moment M as thermodynamical variables and using Maxwell Equations. In the presented semi phenomenological theory, necessary data are taken from the experimental study of P.L. Privalov. The variation in the additional enthalpy H D has been investigated in the pH interval of 1-5 and the results of the calculations are discussed for Lysozyme

  2. Energetics of the molecular interactions of L-alanine and L-serine with xylitol, D-sorbitol, and D-mannitol in aqueous solutions at 298.15 K

    Science.gov (United States)

    Mezhevoi, I. N.; Badelin, V. G.

    2013-04-01

    Integral enthalpies of dissolution Δsol H m of L-alanine and L-serine are measured via the calorimetry of dissolution in aqueous solutions of xylitol, D-sorbitol, and D-mannitol. Standard enthalpies of dissolution (Δsol H ○) and the transfer (Δtr H ○) of amino acids from water to binary solvent are calculated from the experimental data. Using the McMillan-Mayer theory, enthalpy coefficients of pairwise interactions h xy of amino acids with molecules of polyols are calculated that are negative. The obtained results are discussed within the theory of the prevalence of different types of interactions in mixed solutions and the effect of the structural features of interacting biomolecules on the thermochemical parameters of dissolution of amino acids.

  3. Effect of the initial stage of annealing on modeling of enthalpy relaxation in a hyperquenched glass

    DEFF Research Database (Denmark)

    Zhang, Yanfei; Guo, Xiaoju; Yue, Yuanzheng

    2013-01-01

    One of the major challenges in glass relaxation study is to establish a universal model describing the enthalpy relaxation in both the hyperquenched glass (HQG) (i.e., far from equilibrium) and the partially annealed hyperquenched glass(AHQG). In particular, the detailed features of the enthalpy ...... proposed composite relaxation function [L. Hornboell, et al., Chem. Phys. Lett. 1-3 (2010) 37] is a reasonable approach for describing those features. In addition, our modeling results imply that the structural heterogeneity plays a crucial role in relaxation of HQG....

  4. The Atmospherically Important Reaction of Hydroxyl Radicals with Methyl Nitrate: A Theoretical Study Involving the Calculation of Reaction Mechanisms, Enthalpies, Activation Energies, and Rate Coefficients.

    Science.gov (United States)

    Ng, Maggie; Mok, Daniel K W; Lee, Edmond P F; Dyke, John M

    2017-09-07

    A theoretical study, involving the calculation of reaction enthalpies, activation energies, mechanisms, and rate coefficients, was made of the reaction of hydroxyl radicals with methyl nitrate, an important process for methyl nitrate removal in the earth's atmosphere. Four reaction channels were considered: formation of H 2 O + CH 2 ONO 2 , CH 3 OOH + NO 2 , CH 3 OH + NO 3 , and CH 3 O + HNO 3 . For all channels, geometry optimization and frequency calculations were performed at the M06-2X/6-31+G** level, while relative energies were improved at the UCCSD(T*)-F12/CBS level. The major channel is found to be the H abstraction channel, to give the products H 2 O + CH 2 ONO 2 . The reaction enthalpy (ΔH 298 K RX ) of this channel is computed as -17.90 kcal mol -1 . Although the other reaction channels are also exothermic, their reaction barriers are high (>24 kcal mol -1 ), and therefore these reactions do not contribute to the overall rate coefficient in the temperature range considered (200-400 K). Pathways via three transition states were identified for the H abstraction channel. Rate coefficients were calculated for these pathways at various levels of variational transition state theory including tunneling. The results obtained are used to distinguish between two sets of experimental rate coefficients, measured in the temperature range of 200-400 K, one of which is approximately an order of magnitude greater than the other. This comparison, as well as the temperature dependence of the computed rate coefficients, shows that the lower experimental values are favored. The implications of the results to atmospheric chemistry are discussed.

  5. Numerical simulation of nonequilibrium flow in high-enthalpy shock tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, M.; Men' shov, I.; Nakamura, Y

    2005-03-01

    The flow field of a nozzle starting process with thermal and chemical nonequilibrium has been simulated. This flow is produced in high enthalpy impulse facilities such as the free piston shock tunnel. The governing equations are the axisymmetric, compressible Navier-Stokes equations. In this study, Park's two-temperature model, where air consists of five species, is used for defining the thermodynamic properties of air as a driven gas. The numerical scheme employed here is the hybrid scheme of the explicit and implicit methods, which was developed in our laboratory, along with AUSM{sup +} to evaluate inviscid fluxes. In the present simulation, the Mach number of an incident shock wave is set at M{sub s}=10.0. It corresponds to a specific enthalpy, h{sub 0}, of 12 MJ/kg. The results clearly show the complicated thermal and chemical nonequilibrium flow field around the end of the shock tube section and at the nozzle inlet during the initial stage of the nozzle starting process. They also suggest that the phenomenon of nozzle melting might be associated with a flow separation at the nozzle inlet.

  6. Melting point gram-atomic volumes and enthalpies of atomization for liquid elements

    International Nuclear Information System (INIS)

    Lamoreaux, R.H.

    1976-01-01

    Values of the gram-atomic volumes and enthalpies of atomization to the monatomic ideal gas state for liquid elements at their melting points are collected to facilitate predictions of the behavior of mixed systems. Estimated values are given for experimentally undetermined quantities

  7. Corollary from the Exact Expression for Enthalpy of Vaporization

    OpenAIRE

    A. A. Sobko

    2011-01-01

    A problem on determining effective volumes for atoms and molecules becomes actual due to rapidly developing nanotechnologies. In the present study an exact expression for enthalpy of vaporization is obtained, from which an exact expression is derived for effective volumes of atoms and molecules, and under certain assumptions on the form of an atom (molecule) it is possible to find their linear dimensions. The accuracy is only determined by the accuracy of measurements of thermodynamic paramet...

  8. The vaporization enthalpy and vapor pressure of S (+)-methamphetamine at T = 298.15 K by correlation gas chromatography

    International Nuclear Information System (INIS)

    Thornton, Melissa; Gobble, Chase; Chickos, James

    2014-01-01

    Highlights: • The vaporization enthalpy of (d)-methamphetamine was measured. • The vapor pressure of (d)-methamphetamine as a function of temperature was evaluated. • The vapor pressure of 4-benzylpiperidine as a function of temperature was evaluated. - Abstract: The vaporization enthalpy and vapor pressure of S (+)-methamphetamine is evaluated by correlation-gas chromatography. A vaporization enthalpy of (58.7 ± 4.3) kJ · mol −1 and a vapor pressure, p = (38 ± 9) Pa has been obtained using a variety of secondary aliphatic amines as standards. In addition, equations describing the vapor pressure temperature dependence are provided for standards and S (+)-methamphetamine covering the temperature range from T = 298.15 K to the boiling temperature. Boiling temperatures are reproduced within an interval of 8 K or less

  9. Vapor pressure and enthalpy of vaporization of oil of catnip by correlation gas chromatography

    International Nuclear Information System (INIS)

    Simmons, Daniel; Gobble, Chase; Chickos, James

    2016-01-01

    Highlights: • Vaporization enthalpies of the nepetalactones from oil of catnip have been evaluated. • Vapor pressures from T = (298.15 to 350) K have been evaluated. • Oil of catnip has a vapor pressure similar to DEET at T = 298.15 K. - Abstract: The vaporization enthalpy and vapor pressure of the two nepetalactones found in Nepeta cataria have been evaluated by correlation gas chromatography. Vaporization enthalpies at T = 298.15 K of {(68.0 ± 1.9) and (69.4 ± 1.9)} kJ ⋅ mol"−"1 have been derived for the minor diastereomer, (4aS,7S,7aS)-nepetalactone, and major one, (4aS,7S,7aR)-nepetalactone, respectively. Vapor pressures also at T = 298.15 K of p = (1.2 ± 0.04) Pa and (0.91 ± 0.03) Pa have been evaluated for the minor and the major stereoisomer. In addition to being of interest because of the remarkable effect it has on various felids, oil of catnip is also quite effective in repelling mosquitoes, comparable to diethyl-m-toluamide (DEET). The vapor pressures evaluated in this work suggest that the two stereoisomers have similar volatility to DEET at ambient temperatures.

  10. Solution enthalpy of potassium iodide in furfural and its mixtures with dimethylsulfoxide

    International Nuclear Information System (INIS)

    Vlasenko, K.K.; Belov, A.A.; Vorob'ev, A.F.

    1986-01-01

    Solution enthalpy of potassium iodide in furfural-dimethylsulfoxide mixtures at 298.15 K and furfural concentration 17.3-100% are determined experimentally. K + and I - ion solvate shell composition, which in the general case doesn't correspond to the mixed solvent composition, is calculated

  11. The vaporization enthalpies and vapor pressures of fatty acid methyl esters C18, C21 to C23, and C25 to C29 by correlation - gas chromatography

    International Nuclear Information System (INIS)

    Chickos, James S.; Zhao Hui; Nichols, Gary

    2004-01-01

    Vapor pressures and vaporization enthalpies for methyl heptadecanoate and methyl heneicosanoate to methyl octacosanoate exclusive of methyl tricosanoate are evaluated as a function of temperature over the temperature range T = 298.15-450 K by correlation gas chromatography. The results are generated by an extrapolative process using literature values for methyl tetradecanoate to methyl eicosanoate as standards. Relationships for calculating vapor pressures of the title compounds from T = 298.15 to 450 K are provided. Experimental fusion enthalpies are also reported for the methyl esters from methyl hexadecanoate to methyl octacosanoate excluding methyl tridecanoate. Vaporization enthalpies and fusion enthalpies adjusted for temperature to T = 298.15 K are combined to provide sublimation enthalpies. The results are compared to available literature values. A rationale for the linear relationship observed between enthalpies of vaporization and enthalpies of transfer from solution to the vapor is also provided

  12. Estimation of formation enthalpies of vanadates by Born-Gaber cycle method

    International Nuclear Information System (INIS)

    Golovkin, B.G.

    1993-01-01

    Principle possibility of calculating Gibbs energy of ionic compound formation as a function of thermochemical radii of component ions of temperature and pressure is shown. Formula for determination of thermochemical radii of polyatomic ions is suggested. Enthalpies of formation of 81 vanadates were estimated with the use of Kapustinsky equation and Born-Gaber cycle

  13. Enthalpy of mixing and heat of vaporization of ethyl acetate with benzene and toluene at 298.15 k and 308.15 k

    OpenAIRE

    K. L. Shivabasappa; P. Nirguna Babu; Y. Jagannadha Rao

    2008-01-01

    The present work was carried out in two phases. First, enthalpy of mixing was measured and then the heat of vaporization for the same mixtures was obtained. The data are useful in the design of separation equipments. From the various designs available for the experimental determination of enthalpy of mixing, and heat of vaporization, the apparatus was selected, modified and constructed. The apparatus of enthalpy of mixing was tested with a known system Benzene - i-Butyl Alcohol and the data o...

  14. Enthalpies of proton adsorption onto Bacillus licheniformis at 25, 37, 50, and 75 °C

    Science.gov (United States)

    Gorman-Lewis, Drew

    2011-03-01

    Understanding bacterial surface reactivity requires many different lines of investigation. Toward this end, we used isothermal titration calorimetry to measure heats of proton adsorption onto a Gram positive thermophile Bacillus licheniformis at 25, 37, 50, and 75 °C. Proton adsorption under all conditions exhibited exothermic heat production. Below pH 4.5, exothermic heats decreased as temperature increased above 37 °C; above pH 4.5, there was no significant difference in heats evolved at the temperatures investigated. Total proton uptake did not vary significantly with temperature. Site-specific enthalpies and entropies were calculated by applying a 4-site, non-electrostatic surface complexation model to the calorimetric data. Interpretation of site-specific enthalpies and entropies of proton adsorption for site L1, L2, and L4 are consistent with previous interpretations of phosphoryl, carboxyl, and hydroxyl/amine site-identities, respectively, and with previous calorimetric measurements of proton adsorption onto mesophilic species. Enthalpies and entropies for surface site L3 are not consistent with the commonly inferred phosphoryl site-identity and are more consistent with sulfhydryl functional groups. These results reveal intricacies of surface reactivity that are not detectable by other methods.

  15. Short Pulsed Laser Methods for Velocimetry and Thermometry in High Enthalpy Facilities, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A suite of laser-based diagnostics is proposed to measure velocity and temperature simultaneously using unseeded techniques in high enthalpy flows relevant to...

  16. The system analysis of temperature and melting enthalpy of intermetallic compounds of antimony-lanthanoids system of Sb Ln, Sb2Ln composition

    International Nuclear Information System (INIS)

    Badalova, M.A.; Chamanova, M.; Dodkhoev, E.S.; Badalov, A.; Abdusalyamova, M.N.

    2015-01-01

    Present article is devoted to system analysis of temperature and melting enthalpy of intermetallic compounds of antimony-lanthanoids system of Sb Ln, Sb 2 Ln composition. The melting enthalpy was estimated. The temperature value was determined.

  17. The standard enthalpies of formation of L-asparagine and L-{alpha}-glutamine

    Energy Technology Data Exchange (ETDEWEB)

    Contineanu, Iulia, E-mail: icontineanu@yahoo.com [Institute of Physical Chemistry ' I.G. Murgulescu' , Spl. Independentei 202, Bucharest (Romania); Neacsu, Ana, E-mail: anna_matache@yahoo.com [Institute of Physical Chemistry ' I.G. Murgulescu' , Spl. Independentei 202, Bucharest (Romania); Perisanu, Stefan T., E-mail: stefan.perisanu@upb.ro [Laboratory of General Chemistry, Polytechnic University of Bucharest, str. Polizu nr. 1, Bucuresti (Romania)

    2010-01-10

    The energies of combustion of L-asparagine and L-{alpha}-glutamine were measured in a static bomb adiabatic calorimeter. Corrections were made for the heats due to the ignition of sample and for the nitric acid formation. The derived enthalpies of formation in solid state of asparagine monohydrate, nonhydrated asparagine and glutamine are respectively -1084.1 {+-} 3.0, -788.1 {+-} 4.7 and -834.3 {+-} 4.6 kJ mol{sup -1}. The data of enthalpy of formation are compared with the literature values and with estimated values by means of group additivity, using parameters recommended by Domalski and Hearing. The discrepancies between experimental and calculated values are explained by considering the number and strength of intermolecular hydrogen bonds. The dehydration of asparagine monohydrate and the possible melting of the three amino acids were investigated by means of DSC. Glutamine melts without considerable decomposition at about 182 {sup o}C, while asparagines decompose during the fusion process (208 {sup o}C).

  18. Mass spectrometric study of thermodynamic properties of gaseous lead tellurates. Estimation of formation enthalpies of gaseous lead polonates

    Energy Technology Data Exchange (ETDEWEB)

    Shugurov, S.M., E-mail: s.shugurov@spbu.ru; Panin, A.I.; Lopatin, S.I.; Emelyanova, K.A.

    2016-10-15

    Gaseous reactions involving lead oxides, tellurium oxide and lead tellurates were studied by the Knudsen effusion mass spectrometry. Equilibrium constants and reaction enthalpies were evaluated. Structures, molecular parameters and thermodynamic functions of gaseous PbTeO{sub 3} and Pb{sub 2}TeO{sub 4} were calculated by quantum chemistry methods. The formation enthalpies Δ{sub f}H{sup 0} (298.15) = −294 ± 13 for gaseous PbTeO{sub 3} and Δ{sub f}H{sup 0} (298.15) = −499 ± 12 for gaseous Pb{sub 2}TeO{sub 4} were obtained. On the base of these results the formation enthalpies of gaseous PbPoO{sub 3} and Pb{sub 2}PoO{sub 4} were estimated as −249 ± 34 and −478 ± 38, respectively. - Highlights: • Gaseous lead tellurates PbTeO{sub 3}, Pb{sub 2}TeO{sub 4} were discovered. • Their thermodynamic properties were studied using both high temperature mass spectrometry and quantum chemistry computations. • The obtained data allows to predict the formation enthalpies of gaseous lead polonates PbPoO{sub 3}, Pb{sub 2}PoO{sub 4}.

  19. Active-constructive-interactive: a conceptual framework for differentiating learning activities.

    Science.gov (United States)

    Chi, Michelene T H

    2009-01-01

    Active, constructive, and interactive are terms that are commonly used in the cognitive and learning sciences. They describe activities that can be undertaken by learners. However, the literature is actually not explicit about how these terms can be defined; whether they are distinct; and whether they refer to overt manifestations, learning processes, or learning outcomes. Thus, a framework is provided here that offers a way to differentiate active, constructive, and interactive in terms of observable overt activities and underlying learning processes. The framework generates a testable hypothesis for learning: that interactive activities are most likely to be better than constructive activities, which in turn might be better than active activities, which are better than being passive. Studies from the literature are cited to provide evidence in support of this hypothesis. Moreover, postulating underlying learning processes allows us to interpret evidence in the literature more accurately. Specifying distinct overt activities for active, constructive, and interactive also offers suggestions for how learning activities can be coded and how each kind of activity might be elicited. Copyright © 2009 Cognitive Science Society, Inc.

  20. Down-Hole Heat Exchangers: Modelling of a Low-Enthalpy Geothermal System for District Heating

    Directory of Open Access Journals (Sweden)

    M. Carlini

    2012-01-01

    Full Text Available In order to face the growing energy demands, renewable energy sources can provide an alternative to fossil fuels. Thus, low-enthalpy geothermal plants may play a fundamental role in those areas—such as the Province of Viterbo—where shallow groundwater basins occur and conventional geothermal plants cannot be developed. This may lead to being fuelled by locally available sources. The aim of the present paper is to exploit the heat coming from a low-enthalpy geothermal system. The experimental plant consists in a down-hole heat exchanger for civil purposes and can supply thermal needs by district heating. An implementation in MATLAB environment is provided in order to develop a mathematical model. As a consequence, the amount of withdrawable heat can be successfully calculated.

  1. Vapor pressures and vaporization enthalpy of (−) α-bisabolol and (dl) menthol by correlation gas chromatography

    International Nuclear Information System (INIS)

    Keating, Leasa; Harris, Harold H.; Chickos, James S.

    2017-01-01

    Highlights: • The vaporization enthalpy and vapor pressure of (−) α-bisabolol and (dl)-menthol have been measured as a function of temperature. • Vapor pressures, vaporization enthalpies and boiling temperatures have been compared to available literature data. • Vapor pressures of (l)-menthol are compared to (dl)-menthol. - Abstract: The vapor pressures and vaporization enthalpies of (−) α-bisabolol and (dl)-menthol, two GRAS chemicals (generally recognized as safe) are evaluated by correlation gas chromatography using a series of saturated primary alcohols as standards. Vaporization enthalpies of (96.6 ± 2.4) and (74.2 ± 2.8) kJ mol −1 and vapor pressures of p/Pa = (0.020 ± 0.003) and (4.5 ± 0.44) were evaluated at T = 298.15 K for (−) α-bisabolol and (dl)-menthol, respectively, and compared to literature values. The vapor pressures of both compounds from T = (298.15 to 500) K have been derived from correlations using vapor pressures of a series of 1-alkanols and corresponding gas chromatographic retention times at 10 K intervals. The results were fit to a second order polynomial. Calculated normal boiling temperatures of T B = (574.8 and 492.7) K are calculated for (−) α-bisabolol and (dl)-menthol, respectively. A normal boiling temperature of T B = (485.2, and 489.7) K has previously been reported for (dl)-menthol. Vapor pressures for both (l)-menthol and (dl)-menthol from a previous study and (dl)-menthol from this study are compared with literature values.

  2. Energetic studies of urea derivatives: Standard molar enthalpy of formation of 3,4,4'-trichlorocarbanilide

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro da Silva, Maria das Dores M.C. [Centro de Investigacao em Quimica, Department of Chemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Ribeiro da Silva, Manuel A.V., E-mail: risilva@fc.up.p [Centro de Investigacao em Quimica, Department of Chemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Freitas, Vera L.S. [Centro de Investigacao em Quimica, Department of Chemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Roux, Maria Victoria; Jimenez, Pilar; Davalos, Juan Z. [Instituto de Quimica Fisica ' Rocasolano' , C.S.I.C., Serrano, 119, E-28006 Madrid (Spain); Cabildo, Pilar; Claramunt, Rosa M. [Departamento de Quimica Organica y Bio-Organica, Facultad de Ciencias, UNED, Senda del Rey, 9, E-28040 Madrid (Spain); Pinilla, Elena; Rosario Torres, M. [Departamento de Quimica Inorganica I, Laboratorio de Difraccion de Rayos X, Facultad de Ciencias Quimicas, E-28040 Madrid (Spain); Elguero, Jose [Instituto de Quimica Medica, C.S.I.C., Juan de la Cierva, 3, E-28006 Madrid (Spain)

    2010-04-15

    Thermochemical and thermophysical studies have been carried out for crystalline 3,4,4'-trichlorocarbanilide. The standard (p{sup o} = 0.1 MPa) molar enthalpy of formation, at T = 298.15 K, for the crystalline 3,4,4'-trichlorocarbanilide (TCC) was experimentally determined using rotating-bomb combustion calorimetry, as -(234.6 +- 8.3) kJ . mol{sup -1}. The standard enthalpy of sublimation, at the reference temperature of 298.15 K, was measured by the vacuum drop microcalorimetric technique, using a High Temperature Calvet Microcalorimeter as (182.1 +- 1.7) kJ . mol{sup -1}. These two thermochemical parameters yielded the standard molar enthalpy of formation of the studied compound, in the gaseous phase, at T = 298.15 K, as -(52.5 +- 8.5) kJ . mol{sup -1}. This parameter was also calculated by computational thermochemistry at M05-2X/6-311++G** and B3LYP/6-311++G(3df, 2p) levels, with a deviation less than 4.5 kJ . mol{sup -1} from experimental value. Moreover, the thermophysical study was made by differential scanning calorimetry, DSC, over the temperature interval between T = 263 K and its onset fusion temperature, T = (527.5 +- 0.4) K. A solid-solid phase transition was found at T = (428 +- 1) K, with the enthalpy of transition of (6.1 +- 0.1) kJ . mol{sup -1}. The X-ray crystal structure of TCC was determined and the three-centred N-H...O=C hydrogen bonds present analyzed.

  3. Calculation of partial enthalpies in argon-krypton mixtures by NPT molecular dynamics

    NARCIS (Netherlands)

    Sindzingre, P.; Massobrio, C.; Ciccotti, G.; Frenkel, D.

    1989-01-01

    In an earlier paper, we have indicated how, by using a particle-insertion technique, partial molar enthalpies and related quantities can be evaluated from simulations on a single state point. In the present paper we apply this method to a Lennard-Jones argon-krypton mixture. For this particular

  4. Experimental-numerical study of heat flow in deep low-enthalpy geothermal conditions

    NARCIS (Netherlands)

    Saeid, S.; Al-Khoury, R.; Nick, H.M.; Barends, F.

    2014-01-01

    This paper presents an intensive experimental-numerical study of heat flow in a saturated porous domain. A temperature and a flow rate range compared to that existing in a typical deep low-enthalpy hydrothermal system is studied. Two main issues are examined: the effect of fluid density and

  5. Standard molar enthalpies of formation of 2-chloroquinoline, 4-chloroquinoline, 6-chloroquinoline and 4,7-dichloroquinoline by rotating-bomb calorimetry

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Matos, Maria Agostinha R.; Amaral, Luisa M.P.F.

    2006-01-01

    The standard (p o =0.1MPa) molar enthalpies of combustion, Δ c H m - bar , for crystalline 2-, 4-, 6-chloroquinoline and 4,7-dichloroquinoline were determined at the temperature 298.15K using a rotating-bomb combustion calorimeter. The standard molar enthalpies of sublimation, Δ cr g H m o , at T= 298.15K, were determined by Calvet microcalorimetry. The results were as follows: -Δ c H m o (cr)/(kJ.mol -1 )Δ cr g H m o /(kJ.mol -1 )2-Chloroquinoline4492.5+/-1.684.3+/-2.64-Chloroquinoline4508.4 +/ -1.678.6+/-1.76-Chloroquinoline4508.2+/-1.680.8+/-1.94,7-Dichloroquinoline 4353.3+/-1.389.5+/-2.3 These values were used to derive the standard molar enthalpies of formation of the compounds in their crystalline and gaseous phases, respectively. The derived standard molar enthalpies of formation, in the gaseous state, are analysed in terms of enthalpic increments and interpreted in terms of molecular structure

  6. ENTHALPY EU PROJECT: ENABLING THE DRYING PROCESS TO SAVE ENERGY AND WATER, REALISING PROCESS EFFICIENCY IN THE DAIRY CHAIN

    OpenAIRE

    Berta ALVAREZ PENEDO; Sandra FORSTNER; Alexandru RUSU

    2016-01-01

    The EU funded ENTHALPY project aims to significantly reduce the consumption of water and energy in milk powder production to increase efficiency in the dairy production chain. Using a systematic approach, ENTHALPY project focusses on innovations within the post-harvest chain representing the highest energy and water consumption such as RF heating, solar thermal energy, mono-disperse atomising, dryer modelling, inline monitoring, enzymatic cleaning and membrane technology,

  7. The Role of Structural Enthalpy in Spherical Nucleic Acid Hybridization.

    Science.gov (United States)

    Fong, Lam-Kiu; Wang, Ziwei; Schatz, George C; Luijten, Erik; Mirkin, Chad A

    2018-05-23

    DNA hybridization onto DNA-functionalized nanoparticle surfaces (e.g., in the form of a spherical nucleic acid (SNA)) is known to be enhanced relative to hybridization free in solution. Surprisingly, via isothermal titration calorimetry, we reveal that this enhancement is enthalpically, as opposed to entropically, dominated by ∼20 kcal/mol. Coarse-grained molecular dynamics simulations suggest that the observed enthalpic enhancement results from structurally confining the DNA on the nanoparticle surface and preventing it from adopting enthalpically unfavorable conformations like those observed in the solution case. The idea that structural confinement leads to the formation of energetically more stable duplexes is evaluated by decreasing the degree of confinement a duplex experiences on the nanoparticle surface. Both experiment and simulation confirm that when the surface-bound duplex is less confined, i.e., at lower DNA surface density or at greater distance from the nanoparticle surface, its enthalpy of formation approaches the less favorable enthalpy of duplex formation for the linear strand in solution. This work provides insight into one of the most important and enabling properties of SNAs and will inform the design of materials that rely on the thermodynamics of hybridization onto DNA-functionalized surfaces, including diagnostic probes and therapeutic agents.

  8. A Simple Experiment for Determining Vapor Pressure and Enthalpy of Vaporization of Water.

    Science.gov (United States)

    Levinson, Gerald S.

    1982-01-01

    Laboratory procedures, calculations, and sample results are described for a freshman chemistry experiment in which the Clausius-Clapeyron equation is introduced as a means of describing the variation of vapor pressure with temperature and for determining enthalpy of vaporization. (Author/SK)

  9. Enthalpy-entropy compensation for the solubility of drugs in solvent mixtures: paracetamol, acetanilide, and nalidixic acid in dioxane-water.

    Science.gov (United States)

    Bustamante, P; Romero, S; Pena, A; Escalera, B; Reillo, A

    1998-12-01

    In earlier work, a nonlinear enthalpy-entropy compensation was observed for the solubility of phenacetin in dioxane-water mixtures. This effect had not been earlier reported for the solubility of drugs in solvent mixtures. To gain insight into the compensation effect, the behavior of the apparent thermodynamic magnitudes for the solubility of paracetamol, acetanilide, and nalidixic acid is studied in this work. The solubility of these drugs was measured at several temperatures in dioxane-water mixtures. DSC analysis was performed on the original powders and on the solid phases after equilibration with the solvent mixture. The thermal properties of the solid phases did not show significant changes. The three drugs display a solubility maximum against the cosolvent ratio. The solubility peaks of acetanilide and nalidixic acid shift to a more polar region at the higher temperatures. Nonlinear van't Hoff plots were observed for nalidixic acid whereas acetanilide and paracetamol show linear behavior at the temperature range studied. The apparent enthalpies of solution are endothermic going through a maximum at 50% dioxane. Two different mechanisms, entropy and enthalpy, are suggested to be the driving forces that increase the solubility of the three drugs. Solubility is entropy controlled at the water-rich region (0-50% dioxane) and enthalpy controlled at the dioxane-rich region (50-100% dioxane). The enthalpy-entropy compensation analysis also suggests that two different mechanisms, dependent on cosolvent ratio, are involved in the solubility enhancement of the three drugs. The plots of deltaH versus deltaG are nonlinear, and the slope changes from positive to negative above 50% dioxane. The compensation effect for the thermodynamic magnitudes of transfer from water to the aqueous mixtures can be described by a common empirical nonlinear relationship, with the exception of paracetamol, which follows a separate linear relationship at dioxane ratios above 50%. The

  10. Field tests for the comparative evaluation of heat and enthalpy exchangers in compact ventilation units; Feldvergleich von Waerme- und Enthalpieuebertragern in Kompakt-Lueftungsgeraeten - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Frei, B.

    2007-07-01

    In an efficiency review on low energy buildings promoted by the Swiss Federal Office of Energy, low air humidity has been measured during thousands of annual hours. Modern compact ventilation units are being increasingly offered with transmission of heat and moisture. One possibility to raise the air humidity level is an enthalpy exchanger with steam-permeable membranes. With an enthalpy exchanger you can not only recover heat but also a good part of the humidity of the return air. In a comparative field study alternate applications with enthalpy or heat exchangers have been analysed at four different locations. Also calculations have been made to estimate how a rotating heat exchanger with ion-exchange resin would have performed. The comparative field study has shown that the enthalpy exchanger is able to raise the humidity level. Conditions for this are internal humidity loads, balanced air volume rates which correspond to occupancy as well as low leakages of the ventilation unit. Over-moistening due to the system with enthalpy exchanger was not found. The measurements have been affected by a sequence of winter months which have been partially warmer than usual. Otherwise the difference between enthalpy and heat exchangers would have been more significant. (author)

  11. Revision of standard molar enthalpies of formation of glycine and L-alanine in the gaseous phase on the basis of theoretical calculations

    International Nuclear Information System (INIS)

    Dorofeeva, Olga V.; Ryzhova, Oxana N.

    2009-01-01

    The standard molar enthalpies of formation of urea, glycine, and L-alanine in the gaseous phase at 298.15 K were calculated by the high-level Gaussian-3X method. The agreement with the available experimental data is very good for urea and glycine and, thus, supports the high accuracy of calculated values. A significant discrepancy between theoretical and experimental enthalpy of formation values for L-alanine provides a reason to reconsider the experimental data previously used to derive the standard molar enthalpy of formation of L-alanine in the gaseous phase at 298.15 K. To obtain a more reliable value of enthalpy of sublimation at 298.15 K, the heat capacity values of gaseous L-alanine were calculated by standard statistical thermodynamics formulae using molecular parameters determined from B3LYP/cc-pVTZ calculations. With the obtained value of C p,m 0 (L-alanine, g, 298.15 K) = 112.6 ± 4.0 J . K -1 . mol -1 the original published experimental values of enthalpy of sublimation of L-alanine were readjusted to the reference temperature: Δ cr g H m (L-alanine, 298.15 K) = 135.2 ± 2.0 kJ . mol -1 . This value, together with the experimental enthalpy of formation of solid L-alanine, Δ f H m 0 (L-alanine, cr, 298.15 K) = -560.0 ± 1.0 kJ . mol -1 [S.N. Ngauv, R. Sabbah, M. Laffitte, Thermochim. Acta 20 (1977) 371-380; I. Contineanu, D.I. Marchidan, Rev. Roum. Chim. 29 (1984) 43-48], gives a new value for the enthalpy of formation of L-alanine in the gaseous phase, Δ f H m 0 (L-alanine, g, 298.15 K) = -424.8 ± 2.0 kJ . mol -1 , which is in good agreement with our theoretical G3X result, -427.6 ± 4.0 kJ . mol -1 . The same procedure for glycine allowed us to improve the literature value of the enthalpy of formation for this compound, Δ f H m 0 (glycine, g, 298.15 K) = -393.7 ± 1.5 kJ . mol -1 . As a result a set of self-consistent thermochemical data for glycine and L-alanine is proposed

  12. Vapor pressures and enthalpies of vaporization of a series of 1- and 2-halogenated naphthalenes

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.

    2003-01-01

    Molar enthalpies of vaporization, Δ l g H m 0 , of 1-methyl-naphthalene, 1-chloro-napthalene, 2-chloro-naphthalene, 1-bromo-naphthalene, 2-bromo-naphthalene, and 1-iodo-naphthalene, as well as molar enthalpies of sublimation, Δ s g H m 0 , of 2-chloro-naphthalene and 2-bromo-naphthalene have been obtained from the temperature dependence of the vapor pressure determined with the transpiration method. These values and the correlation gas-chromatography method, based on the Kovat's index, have been used to determine Δ l g H m 0 and Δ s g H m 0 of 2-iodo-naphthalene. Results obtained in this work have been compared with those from the literature and found consistent

  13. Enthalpies of Dissolution of Crystalline Naproxen Sodium in Water and Potassium Hydroxide Aqueous Solutions at 298 K

    Science.gov (United States)

    Lytkin, A. I.; Chernikov, V. V.; Krutova, O. N.; Bychkova, S. A.; Volkov, A. V.; Skvortsov, I. A.

    2018-03-01

    The enthalpies of dissolution of crystalline naproxen sodium in water and aqueous solutions of KOH at 298.15 K are measured by direct calorimetric means in a wide range of concentrations. The acid-base properties of naproxen sodium at ionic strength I 0 and I = 0.1 (KNO3) and a temperature of 298.15 K are studied by spectrophotometric means. The concentration and thermodynamic dissociation constants are determined. The standard enthalpies of the formation of naproxen sodium and the products of its dissociation in aqueous solution are calculated.

  14. Effect of halogen substitution on the enthalpies of solvation and hydrogen bonding of organic solutes in chlorobenzene and 1,2-dichlorobenzene derived using multi-parameter correlations

    Energy Technology Data Exchange (ETDEWEB)

    Varfolomeev, Mikhail A.; Rakipov, Ilnaz T.; Khachatrian, Artashes A. [Department of Physical Chemistry, Kazan Federal University, Kremlevskaya 18, Kazan 420008 (Russian Federation); Acree, William E., E-mail: acree@unt.edu [Department of Chemistry, 1155 Union Circle # 305070, University of North Texas, Denton, TX 76203-5017 (United States); Brumfield, Michela [Department of Chemistry, 1155 Union Circle # 305070, University of North Texas, Denton, TX 76203-5017 (United States); Abraham, Michael H. [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2015-10-10

    Graphical abstract: - Highlights: • Enthalpies of solution measured for 43 solutes dissolved in chlorobenzene. • Enthalpies of solution measured for 72 solutes dissolved in 1,2-dichlorobenzene. • Mathematical expressions derived for predicting enthalpies of solvation of solutes in chlorobenzene. • Mathematical expressions derived for predicting enthalpies of solvation of solutes in 1,2-chlorobenzene. - Abstract: Enthalpies of solution at infinite dilution at 298 K, Δ{sub soln}H{sup A/Solvent}, have been measured by isothermal solution calorimetry for 43 and 72 organic solutes dissolved in chlorobenzene and 1,2-dichlorobenzene, respectively. The measured Δ{sub soln}H{sup A/Solvent} data, along with published Δ{sub soln}H{sup A/Solvent} values taken from the published literature for solutes dissolved in both chlorobenzene solvents, were converted to enthalpies of solvation, Δ{sub solv}H{sup A/Solvent}, using standard thermodynamic equations. Abraham model correlations were developed from the experimental Δ{sub solv}H{sup A/Solvent} data. The best derived correlations describe the experimental gas-to-chlorobenzene and gas-to-1,2-dichlorobenzene enthalpies of solvation to within standard deviations of 1.5 kJ mol{sup −1} and 1.9 kJ mol{sup −1}, respectively. Enthalpies of X−H…π (X – O, N, and C) hydrogen bond formation of proton donor solutes (alcohols, amines, chlorinated hydrocarbons, etc.) with chlorobenzene and 1,2-dichlorobenzene were calculated based on the Abraham solvation equation. Obtained values are in good agreement with the results determined using conventional methods.

  15. ENTHALPY EU PROJECT: ENABLING THE DRYING PROCESS TO SAVE ENERGY AND WATER, REALISING PROCESS EFFICIENCY IN THE DAIRY CHAIN

    Directory of Open Access Journals (Sweden)

    Berta ALVAREZ PENEDO

    2016-11-01

    Full Text Available The EU funded ENTHALPY project aims to significantly reduce the consumption of water and energy in milk powder production to increase efficiency in the dairy production chain. Using a systematic approach, ENTHALPY project focusses on innovations within the post-harvest chain representing the highest energy and water consumption such as RF heating, solar thermal energy, mono-disperse atomising, dryer modelling, inline monitoring, enzymatic cleaning and membrane technology,

  16. Temperatures and enthalpies of melting of alkali-metal perrhenates

    International Nuclear Information System (INIS)

    Lukas, W.; Gaune-Escard, M.

    1982-01-01

    Melting temperatures and enthalpies of melting were determined for alkali-metal perrhenates by differential enthalpic analysis using a high-temperature Calvet microcalorimeter. The following values were obtained: for LiReO 4 : 692 K and 24.9 kJ.mol -1 ; for NaReO 4 : 693 K and 33 kJ.mol -1 ; for KReO 4 : 828 K and 36 kJ.mol -1 ; for RbReO 4 : 878 K and 34 kJ.mol -1 ; for CsReO 4 : 893 K and 34 kJ.mol -1 . (author)

  17. Vacancy formation enthalpies in bcc and fcc FeCo by positron annihilation

    International Nuclear Information System (INIS)

    Jackman, J.A.; Kim, S.M.; Buyers, W.J.L.

    1982-01-01

    A long slit angular correlation apparatus was used to measure the peak coincidence count rate in stoichiometric FeCo from 290 K to 1510 K. The count rate did not change significantly at the order-disorder phase transition (1008 K), but decreased sharply by 3.2% at the bcc-fcc phase transition at 1258 K. The threshold temperatures for the trapping of positrons in vacancies are measured to be 1125 K for the bcc phase and 1260 K for the fcc phase. The vacancy formation enthalpies in the bcc and fcc phases are determined to be 1.45 +- 0.05 eV and 1.63 +- 0.05 eV. The activation energies for self-diffusion have been estimated from the threshold temperatures, and are found to be 2.45 eV and 2.74 eV for the bcc and fcc phases respectively. (Auth.)

  18. Determination of molar enthalpy of sublimation in case of orotic acid as obtained from experimental and computational data

    Science.gov (United States)

    Marochkin, Ilya I.; Altova, Ekaterina P.; Chilingarov, Norbert S.; Vilkova, Anna L.; Shishkov, Igor F.

    2018-03-01

    Saturated vapor pressure, ln(p/Pa) = (-21316 ± 511)/(T/K)+(41.64 ± 0.11), and enthalpy of sublimation of orotic acid, Δsub Hm0 (Tm) = 177 ± 4 kJ/mol, were determined by means of Knudsen effusion mass spectrometry in the temperature range of 423÷493 K. The computational approaches supported the experimental results reported. The theoretical estimation of the gas-phase enthalpy of formation for orotic acid was done with different working reactions used.

  19. Temperature dependence of enthalpies and entropies of formation and migration of mono-vacancy in BCC iron

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Haohua; Woo, C.H., E-mail: chungho@cityu.edu.hk

    2014-12-15

    Entropies and enthalpies of vacancy formation and diffusion in BCC iron are calculated for each temperature directly from free-energies using phase-space trajectories obtained from spin–lattice dynamics simulations. Magnon contributions are found to be particularly substantial in the temperature regime near the α−β (ferro/para-magnetic) transition. Strong temperature dependence and singular behavior can be seen in this temperature regime, reflecting magnon softening effects. Temperature dependence of the lattice component in this regime is also much more significant compared to previous estimations based on Arrhenius-type fitting. Similar effects on activation processes involving other irradiation-produced defects in magnetic materials are expected.

  20. Vapor pressures and enthalpies of vaporization of a series of the linear aliphatic aldehydes

    Czech Academy of Sciences Publication Activity Database

    Verevkin, S. P.; Krasnykh, E. L.; Vasiltsova, T. V.; Koutek, Bohumír; Doubský, Jan; Heintz, A.

    2003-01-01

    Roč. 206, - (2003), s. 331-339 ISSN 0378-3812 Institutional research plan: CEZ:AV0Z4055905 Keywords : aldehydes * vapor pressure * enthalpy of vaporization Subject RIV: CC - Organic Chemistry Impact factor: 1.165, year: 2003

  1. Characteristics and thermodynamics of the interaction of 6-shogaol with human serum albumin as studied by isothermal titration calorimetry

    Directory of Open Access Journals (Sweden)

    Shevin Rizal Feroz

    Full Text Available ABSTRACT The interaction between 6-shogaol, a pharmacologically active ginger constituent, and human serum albumin (HSA, the main in vivo drug transporter, was investigated using isothermal titration calorimetry (ITC. The value of the binding constant, Ka (5.02 ± 1.37 × 104 M−1 obtained for the 6-shogaol-HSA system suggested intermediate affinity. Analysis of the ITC data revealed feasibility of the binding reaction due to favorable enthalpy and entropy changes. The values of the thermodynamic parameters suggested involvement of van der Waals forces, hydrogen bonds and hydrophobic interactions in the 6-shogaol-HSA complex formation.

  2. Enthalpy model for heating, melting, and vaporization in laser ablation

    OpenAIRE

    Vasilios Alexiades; David Autrique

    2010-01-01

    Laser ablation is used in a growing number of applications in various areas including medicine, archaeology, chemistry, environmental and materials sciences. In this work the heat transfer and phase change phenomena during nanosecond laser ablation of a copper (Cu) target in a helium (He) background gas at atmospheric pressure are presented. An enthalpy model is outlined, which accounts for heating, melting, and vaporization of the target. As far as we know, this is the first model th...

  3. A new apparatus for the determination of adsorption isotherms and adsorption enthalpies on microporous and meso-porous media

    International Nuclear Information System (INIS)

    Mouahid, A.

    2010-01-01

    A specific thermostated experimental device comprising a differential heat flow calorimeter coupled with a home built manometric system has been built for the simultaneous determination of adsorption isotherms and adsorption enthalpies. The differential heat flow calorimeter is a Tian Calvet Setaram C80 model which measures the heat flux of a gas and can be operated isothermally, the manometric system is a stainless steel homemade apparatus. This coupled apparatus allows measurements for pressure up to 2.5 MPa and temperature up to 423.15 K. On the one hand, the apparatus and the experimental procedures are described. On the second hand the reliability and reproducibility were established by measuring adsorption isotherms on a benchmark (Filtrasorb F400) at 318.15 K. The gravimetric method has been used at higher pressure at various temperatures. These devices allowed us to study the adsorption of supercritical fluid (nitrogen N 2 , methane CH 4 , carbon dioxide CO 2 ) in activated carbons and microporous or meso-porous silica. The adsorption of methane on a rock of type (TGR) was also studied. These experimental results are used for the study of the interactions fluid / solid that must be taken into account in molecular simulations or DFT theory. (author)

  4. On determination of enthalpies of complex formation reactions by means of temperature coefficient of complexing degree

    International Nuclear Information System (INIS)

    Povar, I.G.

    1995-01-01

    Equations describing the relation between temperature coefficient of ∂lnα/∂T complexing degree and the sum of changes in the enthalpy of complex formation of the composition M m L n δH mn multiplied by the weight coefficients k mm , are presented. A method to determine changes in the enthalpy of certain ΔH mm reactions from ∂lnα/∂T derivatives has been suggested. The best approximating equation from lnα/(T) dependence has been found. Errors of thus determined δH mm values are estimated and the results of calculation experiment for the system In 3+ -F - are provided. 10 refs., 2 figs., 3 tabs

  5. Standard Test Method for Calculation of Stagnation Enthalpy from Heat Transfer Theory and Experimental Measurements of Stagnation-Point Heat Transfer and Pressure

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2005-01-01

    1.1 This test method covers the calculation from heat transfer theory of the stagnation enthalpy from experimental measurements of the stagnation-point heat transfer and stagnation pressure. 1.2 Advantages 1.2.1 A value of stagnation enthalpy can be obtained at the location in the stream where the model is tested. This value gives a consistent set of data, along with heat transfer and stagnation pressure, for ablation computations. 1.2.2 This computation of stagnation enthalpy does not require the measurement of any arc heater parameters. 1.3 Limitations and ConsiderationsThere are many factors that may contribute to an error using this type of approach to calculate stagnation enthalpy, including: 1.3.1 TurbulenceThe turbulence generated by adding energy to the stream may cause deviation from the laminar equilibrium heat transfer theory. 1.3.2 Equilibrium, Nonequilibrium, or Frozen State of GasThe reaction rates and expansions may be such that the gas is far from thermodynamic equilibrium. 1.3.3 Noncat...

  6. Prediction of the enthalpies of vaporization for room-temperature ionic liquids: Correlations and a substitution-based additive scheme

    International Nuclear Information System (INIS)

    Kabo, Gennady J.; Paulechka, Yauheni U.; Zaitsau, Dzmitry H.; Firaha, Alena S.

    2015-01-01

    Highlights: • The available literature data on Δ l g H for ionic liquids were analyzed. • Correlation equations for Δ l g H were derived using symbolic regression. • A substitution-based incremental scheme for Δ l g H was developed. • The proposed scheme has an advantage over the existing predictive procedures. - Abstract: The literature data on the enthalpies of vaporization for aprotic ionic liquids (ILs) published by the end of May 2014 were analyzed and the most reliable Δ l g H m values were derived for 68 ILs. The selected enthalpies of vaporization were correlated with density and surface tension using symbolic regression and a number of effective correlation equations were proposed. The substitution-based incremental scheme for prediction of the enthalpies of vaporization of imidazolium, pyridinium and pyrrolidinium ILs was developed. The standard error of the regression for the developed scheme is significantly lower than that for the atom-based group-contribution schemes proposed earlier

  7. Prediction of the vapor pressure and vaporization enthalpy of 1-n-alkyl-3-methylimidazolium-bis-(trifluoromethanesulfonyl) amide ionic liquids.

    Science.gov (United States)

    Diedenhofen, Michael; Klamt, Andreas; Marsh, Kenneth; Schäfer, Ansgar

    2007-09-07

    The vapor pressures and vaporization enthalpies of a series of 1-n-alkyl-3-methylimidazolium-bis-(trifluoromethanesulfonyl) amide ionic liquids have been predicted with two different approaches using the COSMO-RS method and quantum chemical gas phase calculations. While the calculated enthalpies are in good agreement with the experimental data, COSMO-RS seems to underestimate the vapor pressures by roughly 0.5-4 log units dependent on the IL and approach used.

  8. Interaction between a hydrophobic rigid face and a flexible alkyl tail: Thermodynamics of self-assembling of sodium cholate and SDS

    International Nuclear Information System (INIS)

    Bai, Guangyue; Sheng, Jianhui; Wang, Yujie; Wu, Hui; Zhao, Yang; Zhuo, Kelei; Bastos, Margarida

    2016-01-01

    Highlights: • Critical concentrations and enthalpy changes for stepwise aggregation are obtained by ITC. • ITC allowed the thermodynamic characterization for NaCA/SDS self-assembling. • Steroid face-to-alkyl chain hydrophobic interaction tends to be saturated at molar ratio 1:1.5. • Alkyl-steroid interaction favors micellization of NaCA/SDS and the mixture shows nonideal behavior. • Intermolecular interaction and excess enthalpies were discussed according to Rubingh’s model. - Abstract: The thermodynamics of molecular self-assembling of an anionic biosurfactant, sodium cholate (NaCA) and its mixtures with sodium dodecyl sulfate (SDS) in aqueous solution have been investigated by isothermal titration calorimetry (ITC), along with fluorescence and conductivity measurements. Different critical concentrations were obtained by these three techniques – critical pre-micelle concentration (cmc_p_r_e) and critical micelle concentration (cmc) for pure NaCA, and critical micelle concentrations (cmc_m_i_x) for the mixed systems with differently initial SDS concentrations. Importantly, ITC allowed us to directly measure the enthalpy changes of pre-micelle formation (ΔH_p_r_e_m_i_c = (−0.28 ± 0.02) kJ·mol"−"1) and of micelle formation (ΔH_m_i_c = (−1.76 ± 0.05) kJ·mol"−"1) for pure NaCA as well as the enthalpies for micellization for the mixed systems NaCA/SDS. The non-ideality of the mixed surfactant solution was evaluated in terms of interaction parameters and excess enthalpies that were calculated in the light of Clint’s and Rubingh’s models. It was found that there is an obvious synergistic effect in the NaCA/SDS mixed system. From all these results we can ascribe the strong interaction between the same charge surfactants NaCA and SDS to the structural difference in their hydrophobic moieties. In fact, the flexible alkyl chains of SDS and the non-planar hydrophobic β-faces of NaCA tend to have a more compact packing than pure NaCA.

  9. Calorimetric determination of enthalpy changes for the proton ionization of 3-[N-morpholino]propanesulfonic acid (MOPS), 4-[N-morpholino]butanesulfonic acid (MOBS) and 3-[N-morpholino]-2-hydroxypropanesulfonic acid (MOPSO) in water-methanol mixtures

    International Nuclear Information System (INIS)

    Jumean, F.H.; Abdo, N.M.; Khamis, M.I.

    2011-01-01

    Highlights: → Two-stage proton ionizations for three N-substituted sulfonic acid derivatives of morpholine. → ΔH 1 and ΔH 2 in x methanol = 0-0.360 measured for MOPS, MOBS and MOPSO. → In water, ΔH 1 = ±1.2 kJ mol -1 , ΔH 2 range 20.7-26.3 kJ mol -1 . → Methanol addition had little effect on ΔH 1 but ΔH 2 rose steadily to 32.2 kJ mol -1 . → Results related to molecular and solvent parameters. - Abstract: Proton ionization enthalpies for three structurally related biological buffers, each with two ionizable protons, were determined using solution calorimetry. These buffers are 3-[N-morpholino]propanesulfonic acid (MOPS), 4-[N-morpholino]butanesulfonic acid (MOBS) and 3-[N-morpholino]-2-hydroxypropanesulfonic acid (MOPSO). Enthalpies were obtained in water-methanol mixtures with methanol mole fraction (X m ) from 0 to 0.360. The first ionization enthalpy (ΔH 1 ) of all buffers was small (±1.2 kJ mol -1 ) at all solvent compositions. The second ionization enthalpy (ΔH 2 ) increased steadily with X m , rising from 20.7 to 25.6 kJ mol -1 for MOPS, 26.3-31.0 kJ mol -1 for MOBS and 23.5-32.2 kJ mol -1 for MOPSO. The results were compared to those for related biological buffers. The observed variations were interpreted in terms of solvent-solvent and solvent-solute interactions.

  10. Air to air fixed plate enthalpy heat exchanger, performance variation and energy analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nasif, Mohammad Shakir [Universiti Teknologi Petronas, Bandar Seri Iskandar (Malaysia); Alwaked, Rafat [Prince Mohammad Bin Fahd University, Al Khobar (Saudi Arabia); Behnia, Masud [University of Sydney, Sydney (Australia); Morrison, Graham [The University of New South Wales, Sydney (Australia)

    2013-11-15

    The thermal performance of a Z shape enthalpy heat exchanger utilising 70 gsm Kraft paper as the heat and moisture transfer surface has been investigated. Effects of different inlet air humidity ratio conditions on the heat exchanger effectiveness and on the energy recovered by the heat exchanger have been the main focus of this investigation. A typical air conditioning cooling coil which incorporates an enthalpy heat exchanger has been modelled for tropical climate. Under test conditions, results have shown that latent effectiveness and the moisture resistance coefficient have strong dependency on the inlet air humidity ratio. Moreover, the latent effectiveness has been found to be strongly dependent on the moisture resistance coefficient rather than the convective mass transfer coefficient. Finally, annual energy analysis for Singapore weather conditions have also shown that energy recovered under variable inlet air conditions is 15% less than that recovered under constant inlet air conditions for the same heat exchanger.

  11. Standard molar enthalpies of formation of hydroxy-, chlor-, and bromapatite

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Fernando J.A.L. [Centro de Quimica Estrutural, Complexo Interdisciplinar, Instituto Superior Tecnico 1049-001 Lisbon (Portugal); Minas da Piedade, Manuel E. [Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, 1749-016 Lisbon (Portugal); Calado, Jorge C.G. [Centro de Quimica Estrutural, Complexo Interdisciplinar, Instituto Superior Tecnico 1049-001 Lisbon (Portugal)]. E-mail: jcalado@ist.utl.pt

    2005-10-15

    The standard (p{sup 0} =0.1MPa) molar enthalpies of formation in the crystalline state of hydroxyapatite, chlorapatite and a preliminary value for bromapatite, at T=298.15K, were determined by reaction-solution calorimetry as: {delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2},cr]=-(13399+/-11)kJ.mol{sup -1},{delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}Cl{sub 2},cr]=-(13231+/-82)kJ.mol{sup -1},and{delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}Br{sub 2},cr]=-(13063+/-81)kJ.mol{sup -1}. A critical assessment of these results and of previously published data is made. Finally, the standard molar enthalpy of formation of iodapatite is estimated as {delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}I{sub 2},cr]=-12949kJ.mol{sup -1}, from a linear correlation of {delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}X{sub 2},cr] (X=OH, F, Cl, Br) against the corresponding {delta}{sub f}H{sub m}{sup 0} [CaX{sub 2},cr].

  12. Activity-Based Collaboration for Interactive Spaces

    DEFF Research Database (Denmark)

    Bardram, Jakob Eyvind; Esbensen, Morten; Tabard, Aurélien

    2017-01-01

    , folder, documents, etc., users are able to interact with ‘activities’ which encapsulate files and other low-level resources. In ABC an ‘activity’ can be shared between collaborating users and can be accessed on different devices. As such, ABC is a framework that suits the requirements of designing...... interactive spaces. This chapter provides an overview of ABC with a special focus on its support for collaboration (‘Activity Sharing’) and multiple devices (‘Activity Roaming’). These ABC concepts are illustrated as implemented in two different interactive spaces technologies; ReticularSpaces [1] and the e......LabBench [2, 3]. The chapter discusses the benefits of activity-based collaboration support for these interactive spaces, while also discussing limitations and challenges to be addressed in further research....

  13. DNA interaction studies of sesamol (3,4-methylenedioxyphenol) food additive.

    Science.gov (United States)

    Kashanian, Soheila; Tahmasian Ghobadi, Ameneh; Roshanfekr, Hamideh; Shariati, Zohreh

    2013-02-01

    The interaction of native calf thymus DNA (CT-DNA) with sesamol (3,4-methylenedioxyphenol) in Tris-HCl buffer at neutral pH 7.4 was monitored by absorption spectrophotometry, viscometry and spectrofluorometry. It is found that sesamol molecules could interact with DNA outside and/or groove binding modes, as are evidenced by: hyperchromism in UV absorption band, very slow decrease in specific viscosity of DNA, and small increase in the fluorescence of methylene blue (MB)-DNA solutions in the presence of increasing amounts of sesamol, which indicates that it is able to partially release the bound MB. Furthermore, the enthalpy and entropy of the reaction between sesamol and CT-DNA showed that the reaction is enthalpy-favored and entropy-disfavored (ΔH = -174.08 kJ mol(-1); ΔS = -532.92 J mol(-1) K(-1)). The binding constant was determined using absorption measurement and found to be 2.7 × 10(4) M(-1); its magnitude suggests that sesamol interacts to DNA with a high affinity.

  14. The gaseous enthalpy of formation of the ionic liquid 1-butyl-3-methylimidazolium dicyanamide from combustion calorimetry, vapor pressure measurements, and ab initio calculations.

    Science.gov (United States)

    Emel'yanenko, Vladimir N; Verevkin, Sergey P; Heintz, Andreas

    2007-04-04

    Ionic liquids are attracting growing interest as alternatives to conventional molecular solvents. Experimental values of vapor pressure, enthalpy of vaporization, and enthalpy of formation of ionic liquids are the key thermodynamic quantities, which are required for the validation and development of the molecular modeling and ab initio methods toward this new class of solvents. In this work, the molar enthalpy of formation of the liquid 1-butyl-3-methylimidazolium dicyanamide, 206.2 +/- 2.5 kJ.mol-1, was measured by means of combustion calorimetry. The molar enthalpy of vaporization of 1-butyl-3-methylimidazolium dicyanamide, 157.2 +/- 1.1 kJ.mol-1, was obtained from the temperature dependence of the vapor pressure measured using the transpiration method. The latter method has been checked with measurements of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, where data are available from the effusion technique. The first experimental determination of the gaseous enthalpy of formation of the ionic liquid 1-butyl-3-methylimidazolium dicyanamide, 363.4 +/- 2.7 kJ.mol-1, from thermochemical measurements (combustion and transpiration) is presented. Ab initio calculations of the enthalpy of formation in the gaseous phase have been performed for 1-butyl-3-methylimidazolium dicyanamide using the G3MP2 theory. Excellent agreement with experimental results has been observed. The method developed opens a new way to obtain thermodynamic properties of ionic liquids which have not been available so far.

  15. Making sense of enthalpy of vaporization trends for ionic liquids: new experimental and simulation data show a simple linear relationship and help reconcile previous data.

    Science.gov (United States)

    Verevkin, Sergey P; Zaitsau, Dzmitry H; Emel'yanenko, Vladimir N; Yermalayeu, Andrei V; Schick, Christoph; Liu, Hongjun; Maginn, Edward J; Bulut, Safak; Krossing, Ingo; Kalb, Roland

    2013-05-30

    Vaporization enthalpy of an ionic liquid (IL) is a key physical property for applications of ILs as thermofluids and also is useful in developing liquid state theories and validating intermolecular potential functions used in molecular modeling of these liquids. Compilation of the data for a homologous series of 1-alkyl-3-methylimidazolium bis(trifluoromethane-sulfonyl)imide ([C(n)mim][NTf2]) ILs has revealed an embarrassing disarray of literature results. New experimental data, based on the concurring results from quartz crystal microbalance, thermogravimetric analyses, and molecular dynamics simulation have revealed a clear linear dependence of IL vaporization enthalpies on the chain length of the alkyl group on the cation. Ambiguity of the procedure for extrapolation of vaporization enthalpies to the reference temperature 298 K was found to be a major source of the discrepancies among previous data sets. Two simple methods for temperature adjustment of vaporization enthalpies have been suggested. Resulting vaporization enthalpies obey group additivity, although the values of the additivity parameters for ILs are different from those for molecular compounds.

  16. Low-temperature heat capacities and standard molar enthalpy of formation of N-methylnorephedrine C211H17NO(s)

    Institute of Scientific and Technical Information of China (English)

    Di You-Ying; Wang Da-Qi; Shi Quan; Tan Zhi-Cheng

    2008-01-01

    This paper reports that low-temperature heat capacities of N-methylnorephedrine C11H17NO(s) have been mea- sured by a precision automated adiabatic calorimeter over the temperature range from T=78 K to T=400 K. A solid to liquid phase transition of the compound was found in the heat capacity curve in the temperature range of T=342- 364 K. The peak temperature, molar enthalpy and entropy of fusion of the substance were determined. The experimental values of the molar heat capacities in the temperature regions of T=78-342 K and T=364-400 K were fitted to two poly- nomial equations of heat capacities with the reduced temperatures by least squares method. The smoothed molar heat capacities and thermodynamic functions of N-methylnorephedrine C11H17NO(s) relative to the standard refer- ence temperature 298.15 K were calculated based on the fitted polynomials and tabulated with an interval of 5 K. The constant-volume energy of combustion of the compound at T=298.15 K was measured by means of an isoperibol preci- sion oxygen-bomb combustion calorimeter. The standard molar enthalpy of combustion of the sample was calculated. The standard molar enthalpy of formation of the compound was determined from the combustion enthalpy and other auxiliary thermodynamic data through a Hess thermochemical cycle.

  17. Thermodynamics of the interaction between antihistamines with native and hydroxypropyl-cyclodextrin derivatives in aqueous solutions

    International Nuclear Information System (INIS)

    Alvarez-Lopez, Enrique; Perez-Casas, Silvia

    2013-01-01

    Highlights: • The complexes formation between cyclodextrins and pheniramines were studied by ITC. • In all the cases, the process is enthalpy driven. • The interactions between cyclodextrins and pheniramines are discussed. -- Abstract: The interactions of native and hydroxypropyl-cyclodextrin derivatives with pheniramine, (±)-brompheniramine, (+)-brompheniramine, (±)-chlorpheniramine, (+)-chlorpheniramine, carbinoxamine maleate salts and doxylamine succinate salt have been studied by isothermal titration calorimetry at T = 298.15 K in aqueous solution. The enthalpies and association constants for the complex formation were obtained, from which the Gibbs energy and entropy changes were derived. The thermodynamic parameters corresponding to the transfer process of the guest from the native to the modified CD are also calculated. The results show that the hydrophobic interactions are important in this process, but the size of the guest and the nature of the substituent are also of some importance

  18. Vapor pressures and standard molar enthalpies, entropies and Gibbs energies of sublimation of two hexachloro herbicides using a TG unit

    International Nuclear Information System (INIS)

    Vecchio, Stefano

    2010-01-01

    The vapor pressures above the solid hexachlorobenzene (HCB) and above both the solid and liquid 1,2,3,4,5,6-hexachlorocyclohexane (lindane) were determined in the ranges 332-450 K and 347-429 K, respectively, by measuring the mass loss rates recorded by thermogravimetry under both isothermal and nonisothermal conditions. The results obtained were compared with those taken from literature. From the temperature dependence of vapor pressure derived by the experimental thermogravimetry data the molar enthalpies of sublimation Δ cr g H m o ( ) were selected for HCB and lindane as well as the molar enthalpy of vaporization Δ l g H m o ( ) for lindane only, at the middle of the respective temperature intervals. The melting temperatures and the molar enthalpies of fusion Δ cr l H m o (T fus ) of lindane were measured by differential scanning calorimetry. Finally, the standard molar enthalpies of sublimation Δ cr g H m o (298.15 K) were obtained for both chlorinated compounds at the reference temperature of 298.15 K using the Δ cr g H m o ( ), Δ l g H m o ( ) and Δ cr l H m o (T fus ) values, as well as the heat capacity differences between gas and liquid and the heat capacity differences between gas and solid, Δ l g C p,m o and Δ cr g C p,m o , respectively, both estimated by applying a group additivity procedure. Therefore, the averages of the standard (p o = 0.1 MPa) molar enthalpies, entropies and Gibbs energies of sublimation at 298.15 K, have been derived.

  19. Study of the distributions of flow rate and enthalpy in the sub-channels of a bundle geometry of nuclear reactors in one and two-phase flow

    International Nuclear Information System (INIS)

    Bayoumi, M.A.A.

    1976-10-01

    A bibliographic study shows that the experimental studies examined, have been developed to understand the phenomenon acting on the mixing between the sub-channels of which geometries are such these of rod bundles used in some nuclear reactors. Experimental devices and tests have been developed to study the influence of the following parameters, operating conditions, pressure, flow rate, power brought to the bundle and inlet temperature on the distribution of flow rates and vapor content among the different sub-channels. By means of non isokinetic sampling, one has determined the enthalpy of the fluid participating to the mixing between the communicating sub-channels and it has been shown that the value of this enthalpy depends strongly on the type of fluid flow and that this enthalpy cannot be either the enthalpy of one of the two sub-channels, nor (always) an average of these two enthalpies. The experimental results have been compared with calculations developed with the code FLICA, concerning the mass velocity distribution, the exchange term of linear momentum, and the variation of the transversal enthalpy with regard to the type of fluid flow. A study of local void ratio measurement, by means of optical probes, has been proposed. The present study has been carried out with a smooth geometry [fr

  20. Enthalpy increment measurements of NaCrO2 using a high temperature Calvet calorimeter

    International Nuclear Information System (INIS)

    Iyer, V.S.; Jayanthi, K.; Ramarao, G.A.; Venugopal, V.; Sood, D.D.

    1991-01-01

    Enthalpy increment measurements on NaCrO 2 (s) were carried out in the temperature range 323 to 839 K using a high temperature Calvet micro calorimeter. The enthalpy increment values were least-squares fitted with temperature with the constraint that (Hdeg T - Hdeg 298 ) at 298.18 K equals zero, and can be given by: (Hdeg T - Hdeg 298 ) J/mol) ± 336 = -23515 + 75.364T(K) + 0.01256T 2 (K) (323 to 839 K). The first differential of the above equation with temperature gives the constant pressure molar heat capacity of NaCrO 2 (s), which is given by: Cdeg p (NaCrO 2 , s, T) (J/K mol) = 75.364 + 0.02512T(K). The thermal properties of NaCrO 2 (s) were calculated using the molar heat capacities from the present study and Sdeg(298 K) from the literature. (orig.)

  1. Calorimetric determination of enthalpies for the proton ionization of N,N-bis[2-hydroxyethyl]-2-aminoethanesulfonic acid (BES) and N-tris[hydroxymethyl]methyl-2-aminoethanesulfonic acid (TES) in water-methanol mixtures

    International Nuclear Information System (INIS)

    Bulos, B.N.; Jumean, F.H.

    2004-01-01

    The enthalpies of proton ionization of the biochemical buffers N,N-bis[2-hydroxyethyl]-2-aminoethanesulfonic acid (BES) and N-tris[hydroxymethyl]methyl-2-aminoethanesulfonic acid (TES) were obtained in water-methanol mixtures in which the methanol mole fraction (X m ) varied in the range 0-0.36. For both buffers, ionization enthalpy for the first proton (ΔH 1 ) was small in all solvent media. However, upon addition of methanol, ΔH 2 increased steadily from 22.2 to a maximum of 27.2 kJ mol -1 for BES, whereas for TES it varied from 30.0 to 32.4, with a minimum of 28.6 kJ mol -1 at X m =0.123. It is noteworthy that this solvent composition lies within the region of maximum structure enhancement of water by methanol. The results were interpreted in terms of methanol-water interactions

  2. Excess enthalpies of ternary mixtures of (oxygenated additives + aromatic hydrocarbon) mixtures in fuels and bio-fuels: (Dibutyl-ether + 1-propanol + benzene), or toluene, at T = (298.15 and 313.15) K

    International Nuclear Information System (INIS)

    Alaoui, Fatima E.M.; Aguilar, Fernando; González-Fernández, María Jesús; Dakkach, Mohamed; Montero, Eduardo A.

    2015-01-01

    Highlights: • New excess enthalpy data for ternary mixtures of (dibutyl ether + aromatic hydrocarbon + 1-propanol) are reported. • 2 ternary systems at T = (298.15 and 313.15) K were measured by means of an isothermal flow calorimeter. • 230 data were fitted to a Redlich–Kister rational equation. • Intermolecular and association effects involved in these systems have been discussed. - Abstract: New experimental excess molar enthalpy data of the ternary systems (dibutyl ether + 1-propanol + benzene, or toluene), and the corresponding binary systems at T = (298.15 and 313.15) K at atmospheric pressure are reported. A quasi-isothermal flow calorimeter has been used to make the measurements. All the binary and ternary systems show endothermic character at both temperatures. The experimental data for the systems have been fitted using the Redlich–Kister rational equation. Considerations with respect the intermolecular interactions amongst ether, alcohol and hydrocarbon compounds are presented

  3. Evaluation and Modeling of Vapor-Liquid Equilibrium and CO2 Absorption Enthalpies of Aqueous Designer Diamines for Post Combustion Capture Processes.

    Science.gov (United States)

    Luo, Weiliang; Yang, Qi; Conway, William; Puxty, Graeme; Feron, Paul; Chen, Jian

    2017-06-20

    Novel absorbents with improved characteristics are required to reduce the existing cost and environmental barriers to deployment of large scale CO 2 capture. Recently, bespoke absorbent molecules have been specifically designed for CO 2 capture applications, and their fundamental properties and suitability for CO 2 capture processes evaluated. From the study, two unique diamine molecules, 4-(2-hydroxyethylamino)piperidine (A4) and 1-(2-hydroxyethyl)-4-aminopiperidine (C4), were selected for further evaluation including thermodynamic characterization. The solubilities of CO 2 in two diamine solutions with a mass fraction of 15% and 30% were measured at different temperatures (313.15-393.15 K) and CO 2 partial pressures (up to 400 kPa) by thermostatic vapor-liquid equilibrium (VLE) stirred cell. The absorption enthalpies of reactions between diamines and CO 2 were evaluated at different temperatures (313.15 and 333.15 K) using a CPA201 reaction calorimeter. The amine protonation constants and associated protonation enthalpies were determined by potentiometric titration. The interaction of CO 2 with the diamine solutions was summarized and a simple mathematical model established that could make a preliminary but good prediction of the VLE and thermodynamic properties. Based on the analyses in this work, the two designer diamines A4 and C4 showed superior performance compared to amines typically used for CO 2 capture and further research will be completed at larger scale.

  4. Interactions between alkaline earth cations and oxo ligands. DFT study of the affinity of the Mg²+ cation for phosphoryl ligands.

    Science.gov (United States)

    da Costa, Leonardo Moreira; de Mesquita Carneiro, José Walkimar; Paes, Lilian Weitzel Coelho

    2011-08-01

    DFT (B3LYP/6-31+G(d)) calculations of Mg(2+) affinities for a set of phosphoryl ligands were performed. Two types of ligands were studied: a set of trivalent [O = P(R)] and a set of pentavalent phosphoryl ligands [O = P(R)(3)] (R = H, F, Cl, Br, OH, OCH(3), CH(3), CN, NH(2) and NO(2)), with R either bound directly to the phosphorus atom or to the para position of a phenyl ring. The affinity of the Mg(2+) cation for the ligands was quantified by means of the enthalpy for the substitution of one water molecule in the [Mg(H(2)O)(6)](2+) complex for a ligand. The enthalpy of substitution was correlated with electronic and geometric parameters. Electron-donor groups increase the interaction between the cation and the ligand, while electron-acceptor groups decrease the interaction enthalpy.

  5. Prediction of enthalpy and standard Gibbs energy of vaporization of haloaromatics from atomic properties.

    Science.gov (United States)

    Monte, M J S; Almeida, A R R P; Liebman, J F

    2015-11-01

    Halogenated benzenes form a class of pollutants with a huge number of members - 1504 distinct benzene compounds, where one or more hydrogen atoms are replaced by halogens, may exist theoretically. This study presents a user friendly method for accurate prediction of vapor pressures and enthalpies of vaporization, at 298.15 K, of any mono or poly halobenzene compound. The derived equations for the prediction of those vaporization properties depend just on the number of each constituent halogen atom. This is a consequence of the absence of intramolecular interactions between the halogen atoms, revealed after examining vaporization results of ca. 40 halogenated benzenes. In order to rationalize the estimation equations, the contribution of the halogen atoms for the referred to above properties of vaporization was decomposed into two atomic properties - the volume and electron affinity. Extension of the applicability of the estimation method to substituted benzenes containing other substituent groups beyond halogen atoms as well as to some polycyclic aromatic species was tested with success. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Low-temperature heat capacity and standard molar enthalpy of formation of 9-fluorenemethanol (C14H12O)

    International Nuclear Information System (INIS)

    Di, You-Ying; Tan, Zhi-Cheng.; Sun, Xiao-Hong; Wang, Mei-Han; Xu, Fen; Liu, Yuan-Fa; Sun, Li-Xian; Zhang, Hong-Tao

    2004-01-01

    Low-temperature heat capacities of the 9-fluorenemethanol (C 14 H 12 O) have been precisely measured with a small sample automatic adiabatic calorimeter over the temperature range between T=78 K and T=390 K. The solid-liquid phase transition of the compound has been observed to be T fus =(376.567±0.012) K from the heat-capacity measurements. The molar enthalpy and entropy of the melting of the substance were determined to be Δ fus H m =(26.273±0.013) kJ · mol -1 and Δ fus S m =(69.770±0.035) J · K -1 · mol -1 . The experimental values of molar heat capacities in solid and liquid regions have been fitted to two polynomial equations by the least squares method. The constant-volume energy and standard molar enthalpy of combustion of the compound have been determined, Δ c U(C 14 H 12 O, s)=-(7125.56 ± 4.62) kJ · mol -1 and Δ c H m compfn (C 14 H 12 O, s)=-(7131.76 ± 4.62) kJ · mol -1 , by means of a homemade precision oxygen-bomb combustion calorimeter at T=(298.15±0.001) K. The standard molar enthalpy of formation of the compound has been derived, Δ f H m compfn (C 14 H 12 O,s)=-(92.36 ± 0.97) kJ · mol -1 , from the standard molar enthalpy of combustion of the compound in combination with other auxiliary thermodynamic quantities through a Hess thermochemical cycle

  7. A compilation of correlation parameters for predicting the enthalpy and thermal conductivity of solid foods within the temperature range of -40 C to +40 C

    Energy Technology Data Exchange (ETDEWEB)

    Amos, N.D. [Comvita New Zealand Limited, Private Bag 1, Te Puke 3153 (New Zealand); Willix, J.; North, M.F. [AgResearch Limited, MIRINZ Centre, Ruakura Campus, East Street, Private Bag 3123, Hamilton (New Zealand); Chadderton, T. [Crop and Food Research Ltd, PO Box 5114, Nelson (New Zealand)

    2008-11-15

    This paper presents thermal conductivity data for 40 foods, enthalpy data for 58 foods and density data for nine foods, along with the compositions of the foods. Measurements cover a range of solid food types (including meats, fats, offal, fish, dairy products and horticultural products). Some measurements reported are for foods that have never before been studied, others have been published elsewhere, but are included here for convenience. Thermal conductivity was measured using a guarded hot-plate apparatus, enthalpy using an adiabatic calorimeter and density using a water displacement meter. Thermal conductivity and enthalpy values were measured within the temperature range of -40 C to +40 C. (author) [French] Cette publication presente des donnes sur la conductivite thermique, l'enthalpie et la densite respectivement de 40, 58 et 9 produits alimentaires, ainsi que leurs compositions. Les mesures couvrent une variete de types de produits alimentaires (viande, matieres grasses, abats, poisson, produits laitiers, produits horticoles). Certaines sont rapportees pour des produits qui n 'ant jamais ete etudie auparavant, d'autres ant ete publie ailleurs mais sont aussi inclues pour plus de commodite. La conductivite thermique a ete mesure avec un appareil a plaque electrique protegee, l'enthalpie avec un calorimetre adiabatique et la densite avec un appareil mesurant Ie deplacement d'eau. La conductivite thermique et l'enthalpie ont ete toutes les mesures pour une fourchette de temperatures allant de -40 C a 40 C. (orig.)

  8. Enthalpies of formation of Cd0.917Sr0.083, Cd0.857Sr0.143 and Cd0.667Sr0.333 intermetallic compounds

    International Nuclear Information System (INIS)

    Agarwal, Renu; Singh, Ziley

    2008-01-01

    Cadmium is expected to be the solvent for pyrochemical processing of the metallic nuclear fuel. Therefore, thermodynamic properties of cadmium with various fuel and clad elements are of interest. Enthalpies of formation of the intermetallic compounds of Cd-Sr system, Cd 0.917 Sr 0.083 , Cd 0.857 Sr 0.143 and Cd 0.667 Sr 0.333 were determined by precipitation using Calvet calorimeter. Enthalpies of formation of the compounds were found to be -3.05 ± 0.5 kJ mol -1 at 723 K, -14.2 ± 0.7 kJ mol -1 at 843 K and -28.4 ± 0.8 kJ mol -1 at 863 K, respectively. Enthalpies of formation of Cd 0.917 Sr 0.083 and Cd 0.857 Sr 0.143 were also determined by partial enthalpy of formation measurements and the values were found to be -3.9 ± 1.1 kJ mol -1 at 723 K and -13.42 ± 1.2 kJ mol -1 at 843 K, respectively. Miedema model was used to estimate the enthalpies of formation of these compounds and the estimated values were compared with the experimentally determined values

  9. The thermodynamic properties of the upper continental crust: Exergy, Gibbs free energy and enthalpy

    International Nuclear Information System (INIS)

    Valero, Alicia; Valero, Antonio; Vieillard, Philippe

    2012-01-01

    This paper shows a comprehensive database of the thermodynamic properties of the most abundant minerals of the upper continental crust. For those substances whose thermodynamic properties are not listed in the literature, their enthalpy and Gibbs free energy are calculated with 11 different estimation methods described in this study, with associated errors of up to 10% with respect to values published in the literature. Thanks to this procedure we have been able to make a first estimation of the enthalpy, Gibbs free energy and exergy of the bulk upper continental crust and of each of the nearly 300 most abundant minerals contained in it. Finally, the chemical exergy of the continental crust is compared to the exergy of the concentrated mineral resources. The numbers obtained indicate the huge chemical exergy wealth of the crust: 6 × 10 6 Gtoe. However, this study shows that approximately only 0.01% of that amount can be effectively used by man.

  10. Enthalpic interactions of N-glycylglycine with xylitol in aqueous sodium chloride and potassium chloride solutions at T = 298.15 K

    International Nuclear Information System (INIS)

    Liu Min; Wang Lili; Zhu Lanying; Li Hui; Sun Dezhi; Di Youying; Li Linwei

    2010-01-01

    The mixing enthalpies of N-glycylglycine with xylitol and their respective enthalpies of dilution in aqueous sodium chloride and potassium chloride solutions have been determined by using flow-mix isothermal microcalorimetry at the temperature of 298.15 K. These experimental results have been used to determine the heterotactic enthalpic interaction coefficients (h xy , h xxy , and h xyy ) according to the McMillan-Mayer theory. It has been found that the heterotactic enthalpic pairwise interaction coefficients h xy between N-glycylglycine and xylitol in aqueous sodium chloride and potassium chloride solutions are negative and become less negative with an increase in the molality of sodium chloride or potassium chloride. The results are discussed in terms of solute-solute and solute-solvent interactions.

  11. Enthalpic interactions of N-glycylglycine with xylitol in aqueous sodium chloride and potassium chloride solutions at T = 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Liu Min, E-mail: panpanliumin@163.co [College of Chemistry and Chemical Engineering, Liao Cheng University, Liaocheng, Shandong 252059 (China); Wang Lili [College of Chemistry and Chemical Engineering, Liao Cheng University, Liaocheng, Shandong 252059 (China); Zhu Lanying [College of Life Science and Bioengineering, Liao Cheng University, Liaocheng, Shandong 252059 (China); Li Hui; Sun Dezhi; Di Youying; Li Linwei [College of Chemistry and Chemical Engineering, Liao Cheng University, Liaocheng, Shandong 252059 (China)

    2010-07-15

    The mixing enthalpies of N-glycylglycine with xylitol and their respective enthalpies of dilution in aqueous sodium chloride and potassium chloride solutions have been determined by using flow-mix isothermal microcalorimetry at the temperature of 298.15 K. These experimental results have been used to determine the heterotactic enthalpic interaction coefficients (h{sub xy}, h{sub xxy}, and h{sub xyy}) according to the McMillan-Mayer theory. It has been found that the heterotactic enthalpic pairwise interaction coefficients h{sub xy} between N-glycylglycine and xylitol in aqueous sodium chloride and potassium chloride solutions are negative and become less negative with an increase in the molality of sodium chloride or potassium chloride. The results are discussed in terms of solute-solute and solute-solvent interactions.

  12. Thermodynamic aspects of polymer–surfactant interactions: Gemini (16-5-16-PVP-water system

    Directory of Open Access Journals (Sweden)

    Naved Azum

    2016-11-01

    Full Text Available The interaction between polyvinylpyrrolidone (PVP and gemini surfactant (16-5-16 in aqueous solution has been analyzed using conductometry. From conductivity data the critical aggregation concentration (cac, critical micelle concentration (cmc, the effective degree of counter-ion binding (β at different temperatures were obtained. The thermodynamic parameters, i.e., Gibbs energy of aggregation and micellization, standard enthalpy of aggregation, and standard entropy of aggregation of surfactant/polymer system were estimated, employing pseudophase separation model. The negative values of Gibbs energy and standard enthalpy suggest that the surfactant/polymer aggregation process is spontaneous and exothermic respectively.

  13. Enthalpy of mixing and heat of vaporization of ethyl acetate with benzene and toluene at 298.15 k and 308.15 k

    Directory of Open Access Journals (Sweden)

    K. L. Shivabasappa

    2008-03-01

    Full Text Available The present work was carried out in two phases. First, enthalpy of mixing was measured and then the heat of vaporization for the same mixtures was obtained. The data are useful in the design of separation equipments. From the various designs available for the experimental determination of enthalpy of mixing, and heat of vaporization, the apparatus was selected, modified and constructed. The apparatus of enthalpy of mixing was tested with a known system Benzene - i-Butyl Alcohol and the data obtained was in very good agreement with literature values. Experiments were then conducted for mixtures of Ethyl Acetate with Benzene and Toluene. The experimental data was fitted to the standard correlations and the constants were evaluated. Heat of vaporization data were obtained from a static apparatus and tested for accuracy by conducting experiments with a known system Benzene - n-Hexane and the data obtained were found to be in agreement with literature values. Experiments were then conducted to measure heat of vaporization for the mixtures of Ethyl Acetate with Benzene and Toluene. Using experimental data of enthalpy of mixing from the first phase, and heat capacity data, the heat of vaporization were calculated.

  14. Vapour pressures and enthalpies of vaporization of a series of the linear n-alkyl acetates

    Czech Academy of Sciences Publication Activity Database

    Krasnykh, E. L.; Verevkin, S. P.; Koutek, Bohumír; Doubský, Jan

    2006-01-01

    Roč. 38, č. 6 (2006), s. 717-723 ISSN 0021-9614 Institutional research plan: CEZ:AV0Z40550506 Keywords : aliphatic acetates * transpiration method * vapour pressure * enthalpy of vaporization Subject RIV: CC - Organic Chemistry Impact factor: 1.842, year: 2006

  15. Liquid-Liquid Equilibrium and Excess Enthalpies in the Binary System 2-Methylpentane + N,N-Dimethylformamide

    Czech Academy of Sciences Publication Activity Database

    Bendová, Magdalena; Řehák, K.; Matouš, J.; Novák, J. P.

    2004-01-01

    Roč. 49, č. 5 (2004), s. 1318-1322 ISSN 0021-9568 Institutional research plan: CEZ:AV0Z4072921 Keywords : liquid-liquid equilibrium * excess enthalpies * thermodynamic models Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.368, year: 2004

  16. Method of determining the enthalpy and moisture content of wet steam

    International Nuclear Information System (INIS)

    Silvestri, G.J. Jr.

    1991-01-01

    This patent describes a nuclear powered multi-stage steam turbine system wherein steam at higher than atmospheric pressure is introduced into the turbine system at a high pressure turbine element and thereafter flows through a series of turbine elements at successively decreasing pressures, wherein portions of the steam are extracted from the turbine elements at a plurality of lower pressure points and the steam is finally exhausted at a lowest pressure point, the method of determining moisture content and enthalpy of steam at a selected pressure point. It comprises sampling a small quantity of steam at the selected pressure point; super heating the steam sample to a single-phase state by reducing its pressure and bottling it in a closed measuring chamber whereby the flow energy of the sample is converted into internal energy; measuring the pressure of the steam sample within the chamber; determining the sonic velocity of the steam sample by passing a sound wave through the sample from a transmitter to a receiver located at a known distance from the transmitter and measuring the time required for the sound wave to travel from transmitter to receiver; and utilizing the measured pressure and sonic velocity of the steam sample to calculate the moisture content and enthalpy of the steam at the selected pressure point

  17. Calorimetric determination of enthalpies for the proton ionization of N,N-bis[2-hydroxyethyl]-2-aminoethanesulfonic acid (BES) and N-tris[hydroxymethyl]methyl-2-aminoethanesulfonic acid (TES) in water-methanol mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Bulos, B.N.; Jumean, F.H

    2004-02-19

    The enthalpies of proton ionization of the biochemical buffers N,N-bis[2-hydroxyethyl]-2-aminoethanesulfonic acid (BES) and N-tris[hydroxymethyl]methyl-2-aminoethanesulfonic acid (TES) were obtained in water-methanol mixtures in which the methanol mole fraction (X{sub m}) varied in the range 0-0.36. For both buffers, ionization enthalpy for the first proton ({delta}H{sub 1}) was small in all solvent media. However, upon addition of methanol, {delta}H{sub 2} increased steadily from 22.2 to a maximum of 27.2 kJ mol{sup -1} for BES, whereas for TES it varied from 30.0 to 32.4, with a minimum of 28.6 kJ mol{sup -1} at X{sub m}=0.123. It is noteworthy that this solvent composition lies within the region of maximum structure enhancement of water by methanol. The results were interpreted in terms of methanol-water interactions.

  18. The effect of a fourth element (Co, Cu, Fe, Pd) on the standard enthalpy of formation of the Heusler compound Ni{sub 2}MnSn

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Ming, E-mail: myin1@hawk.iit.edu; Nash, Philip

    2016-05-15

    The standard enthalpies of formation of quaternary Heusler compounds (X, Ni){sub 2}MnSn (X = Co, Cu, Fe, Pd) were investigated experimentally using high temperature direct reaction calorimetry. Lattice parameters of these compounds were determined using X-ray diffraction analysis. Microstructures were identified using scanning electron microscopy and energy dispersive spectroscopy. The effect of an additional X element on the standard enthalpy of formation of the Heusler compound Ni{sub 2}MnSn is discussed. - Highlights: • Enthalpies of formation of (X,Ni){sub 2}YZ (X = Co, Cu, Fe, Pd) were measured by drop calorimeters. • Magnetic contribution to enthalpy of formation plays an important role. • Introducing a fourth element could stabilize an unstable Heusler structure. • Lattice parameters do not necessarily obey the Vegard's law. • It is possible to tailor properties of Heusler compounds with enough background information.

  19. Outlook on principles for designing integrated and cascade use of low enthalpy geothermal energy in Albania

    International Nuclear Information System (INIS)

    Frasheri, Alfred

    2000-01-01

    In the countries of Western Europe, USA and Japan, the technologies of a new generation evolved to exploit high and low enthalpy geothermal sources and mineral waters. There are great experiences for modern complex exploitation of these resources, which increase natural wealth values, in European Community Countries. In Albania, rich in geothermal resources of low enthalpy and mineral waters, similar new technologies have been either partly developed or remain still untouched. Modern complex exploitation is very rare phenomena. Large numbers of geothermal energy of high and low enthalpy resources, a lot of mineral water sources and some CO 2 gas reservoirs represent the base for successfully application of modern technologies in Albania, to achieve economic effectively and success of complex exploitation. Actuality, there are many geothermal, hydrogeological, hydrochemical, biological and medical investigations and studies of thermal and mineral water resources carried out in Albania. Generally, these investigations and studies are separated each from the other. Their information and data will serve for studies and evaluations in Albania regional scale. These studies and evaluations are necessary to well know in regional plane the thermal and mineral water resources potential and geothermal market of the Albania. According to results of these new studies, the evaluation for the perspective level of the best areas in country will be necessary. After the evaluation is possible to start investments in these areas. These investments will be profitable in a short period of time. Integrated and cascade use of geothermal energy of low enthalpy it is important condition for profitable investment. In Albania, there are several geothermal energy sources that can be used. Such geothermal energy sources are natural thermal water springs and deep wells with a temperature of up to 65,5 o C. Deep abandoned oil wells can be used as 'Vertical Earth Heat Probe'. The integrated and

  20. Thermodynamic and aromaticity studies for the assessment of the halogen⋯cyano interactions on Iodobenzonitrile

    International Nuclear Information System (INIS)

    Rocha, Inês M.; Ribeiro da Silva, Maria D.M.C.; Ribeiro da Silva, Manuel A.V.

    2013-01-01

    Highlights: • Vapour pressure study of the iodobenzonitrile isomers by Knudsen effusion technique. • Enthalpies of formation of the iodobenzonitrile isomers by combustion calorimetry. • NICS, HOMA, SA indices used as aromaticity criteria for iodobenzonitrile isomers. • QTAIMs properties, HOMO–LUMO gap, UV–Vis spectra of iodobenzonitriles. • Bromo and fluorobenzonitriles are taken as references for the aromaticity analysis. -- Abstract: The standard (p° = 0.1 MPa) molar enthalpies of formation, in the gaseous phase, of the 2-, 3- and 4-iodobenzonitrile isomers were derived from the combination of the corresponding standard molar enthalpies of formation, in the condensed phase, at T = 298.15 K, and the standard molar enthalpies of sublimation, at the same temperature, calculated respectively from the standard molar energies of combustion in oxygen, measured by rotating-bomb calorimetry, and from the vapour-pressure study of the referred compounds, measured by mass-loss Knudsen effusion technique. The strength of the halogen-halogen and the halogen-cyano intermolecular interactions, in the crystal, are evaluated by the enthalpies and entropies of phase transition of the iodobenzonitrile derived from mass-loss Knudsen technique and differential scanning calorimetry measurements and compared with those reported to fluorobenzonitrile and bromobenzonitrile isomers. The computational calculations complement the experimental work, using different aromaticity criteria (HOMA, NICS, Shannom Aromaticity, PDI and ATI) for the analysis of the electronic behaviour of each iodobenzonitrile isomer

  1. Using Enthalpy as a Prognostic Variable in Atmospheric Modelling with Variable Composition

    Science.gov (United States)

    2016-04-14

    Sela, personal communication, 2005). These terms are also routinely neglected in models. In models with a limited number of gaseous tracers, such as...so-called energy- exchange term (second term on the left- hand side) in Equation (5). The finite-difference schemes in existing atmospheric models have...equation for the sum of enthalpy and kinetic energy of horizontal motion is solved. This eliminates the energy- exchange term and automatically

  2. Accuracy of the DLPNO-CCSD(T) method for non-covalent bond dissociation enthalpies from coinage metal cation complexes

    KAUST Repository

    Minenkov, Yury; Chermak, Edrisse; Cavallo, Luigi

    2015-01-01

    The performance of the domain based local pair-natural orbital coupled-cluster (DLPNO-CCSD(T)) method has been tested to reproduce the experimental gas phase ligand dissociation enthalpy in a series of Cu+, Ag+ and Au+ complexes. For 33 Cu+ - non-covalent ligand dissociation enthalpies all-electron calculations with the same method result in MUE below 2.2 kcal/mol, although a MSE of 1.4 kcal/mol indicates systematic underestimation of the experimental values. Inclusion of scalar relativistic effects for Cu either via effective core potential (ECP) or Douglass-Kroll-Hess Hamiltonian, reduces the MUE below 1.7 kcal/mol and the MSE to -1.0 kcal/mol. For 24 Ag+ - non-covalent ligand dissociation enthalpies the DLPNO-CCSD(T) method results in a mean unsigned error (MUE) below 2.1 kcal/mol and vanishing mean signed error (MSE). For 15 Au+ - non-covalent ligand dissociation enthalpies the DLPNO-CCSD(T) methods provides larger MUE and MSE, equal to 3.2 and 1.7 kcal/mol, which might be related to poor precision of the experimental measurements. Overall, for the combined dataset of 72 coinage metal ion complexes DLPNO-CCSD(T) results in a MUE below 2.2 kcal/mol and an almost vanishing MSE. As for a comparison with computationally cheaper density functional theory (DFT) methods, the routinely used M06 functional results in MUE and MSE equal to 3.6 and -1.7 kca/mol. Results converge already at CC-PVTZ quality basis set, making highly accurate DLPNO-CCSD(T) estimates to be affordable for routine calculations (single-point) on large transition metal complexes of > 100 atoms.

  3. Accuracy of the DLPNO-CCSD(T) method for non-covalent bond dissociation enthalpies from coinage metal cation complexes

    KAUST Repository

    Minenkov, Yury

    2015-08-27

    The performance of the domain based local pair-natural orbital coupled-cluster (DLPNO-CCSD(T)) method has been tested to reproduce the experimental gas phase ligand dissociation enthalpy in a series of Cu+, Ag+ and Au+ complexes. For 33 Cu+ - non-covalent ligand dissociation enthalpies all-electron calculations with the same method result in MUE below 2.2 kcal/mol, although a MSE of 1.4 kcal/mol indicates systematic underestimation of the experimental values. Inclusion of scalar relativistic effects for Cu either via effective core potential (ECP) or Douglass-Kroll-Hess Hamiltonian, reduces the MUE below 1.7 kcal/mol and the MSE to -1.0 kcal/mol. For 24 Ag+ - non-covalent ligand dissociation enthalpies the DLPNO-CCSD(T) method results in a mean unsigned error (MUE) below 2.1 kcal/mol and vanishing mean signed error (MSE). For 15 Au+ - non-covalent ligand dissociation enthalpies the DLPNO-CCSD(T) methods provides larger MUE and MSE, equal to 3.2 and 1.7 kcal/mol, which might be related to poor precision of the experimental measurements. Overall, for the combined dataset of 72 coinage metal ion complexes DLPNO-CCSD(T) results in a MUE below 2.2 kcal/mol and an almost vanishing MSE. As for a comparison with computationally cheaper density functional theory (DFT) methods, the routinely used M06 functional results in MUE and MSE equal to 3.6 and -1.7 kca/mol. Results converge already at CC-PVTZ quality basis set, making highly accurate DLPNO-CCSD(T) estimates to be affordable for routine calculations (single-point) on large transition metal complexes of > 100 atoms.

  4. Theoretical calculation of enthalpy of formation of multiconformational molecules: 1,2-ethanediol, propanediols, and glycerol

    Science.gov (United States)

    Dorofeeva, Olga V.; Suchkova, Taisiya A.

    2018-04-01

    The gas-phase enthalpies of formation of four molecules with high flexibility, which leads to the existence of a large number of low-energy conformers, were calculated with the G4 method to see whether the lowest energy conformer is sufficient to achieve high accuracy in the computed values. The calculated values were in good agreement with the experiment, whereas adding the correction for conformer distribution makes the agreement worse. The reason for this effect is a large anharmonicity of low-frequency torsional motions, which is ignored in the calculation of ZPVE and thermal enthalpy. It was shown that the approximate correction for anharmonicity estimated using a free rotor model is of very similar magnitude compared with the conformer correction but has the opposite sign, and thus almost fully compensates for it. Therefore, the common practice of adding only the conformer correction is not without problems.

  5. Standard partial molar heat capacities and enthalpies of formation of aqueous aluminate under hydrothermal conditions from integral heat of solution measurements

    International Nuclear Information System (INIS)

    Coulier, Yohann; Tremaine, Peter R.

    2014-01-01

    Highlights: • Heats of solution of NaAlO 2 (s) were measured at five temperatures up to 250 °C. • Standard molar enthalpies of solution were determined from the measured heats of solution. • Standard molar enthalpies of solution were correlated with the density model. • The density model allows us to determine the standard molar heat capacities of reaction. - Abstract: Heats of solution of sodium aluminum oxide, NaAlO 2 (s), were measured in aqueous sodium hydroxide solutions using a Tian–Calvet heat-flow calorimeter (Setaram, Model C80) with high pressure “batch cells” made of hastelloy C-276, at five temperatures from (373.15 to 523.15) K, steam saturation pressure, and concentrations from (0.02 to 0.09) mol · kg −1 . Standard molar enthalpies of solution, Δ soln H ∘ , and relative standard molar enthalpies, [H ∘ (T) − H ∘ (298.15 K)], of NaAl(OH) 4 (aq) were determined from the measured heats of solution. The results were fitted with the “density” model. The temperature dependence of Δ soln H ∘ from the model yielded the standard molar heat capacities of reaction, Δ soln C p ∘ , from which standard partial molar heat capacities for aqueous aluminate, C p ∘ [A1(OH) 4 − ,aq], were calculated. Standard partial molar enthalpies of formation, Δ f H ∘ , and entropies, S ∘ , of A1(OH) 4 − (aq) were also determined. The values for C p ∘ [A1(OH) 4 − ,aq] agree with literature data determined up to T = 413 K from enthalpy of solution and heat capacity measurements to within the combined experimental uncertainties. They are consistent with differential heat capacity measurements up to T = 573 K from Schrödle et al. (2010) [29] using the same calorimeter, but this method has the advantage that measurements could be made at much lower concentrations in the presence of an excess concentration of ligand. To our knowledge, these are the first standard partial molar heat capacities measured under hydrothermal conditions by the

  6. Enthalpy model for heating, melting, and vaporization in laser ablation

    Directory of Open Access Journals (Sweden)

    Vasilios Alexiades

    2010-09-01

    Full Text Available Laser ablation is used in a growing number of applications in various areas including medicine, archaeology, chemistry, environmental and materials sciences. In this work the heat transfer and phase change phenomena during nanosecond laser ablation of a copper (Cu target in a helium (He background gas at atmospheric pressure are presented. An enthalpy model is outlined, which accounts for heating, melting, and vaporization of the target. As far as we know, this is the first model that connects the thermodynamics and underlying kinetics of this challenging phase change problem in a self-consistent way.

  7. Correlation between structural relaxation enthalpy and superconducting properties of amorphous Zr70Cu30 and Zr70Ni30 alloys

    International Nuclear Information System (INIS)

    Inoue, A.; Matsuzaki, K.; Toyota, N.; Chen, H.S.; Masumoto, T.; Fukase, T.

    1985-01-01

    The anneal-induced change in the superconducting properties together with the irrecoverable relaxation enthalpy (ΔHsub(i,exo)) and recoverable relaxation enthalpy (ΔHsub(r,endo)) of amorphous Zr 70 Cu 30 and Zr 70 Ni 30 alloys was examined. The increase in ΔHsub(i,exo) and the degradation of Tsub(c) progress logarithmically with annealing time tsub(a) in a temperature range of 373 to 523 K. The activation energy and the attempted frequency were respectively estimated to be 1.5 eV and 6.6 x 10 13 sec -1 for the increase in ΔHsub(i,exo) and 1.5 eV and 1.9 x 10 14 sec -1 for the degradation of Tsub(c). The recoverable structure relaxation exerts little effect on Tsub(c). Based on the agreement between the kinetic parameters for the changes of ΔHsub(i,exo) and Tsub(c), it appears that the degradation of Tsub(c) on annealing is associated with the irrecoverable structural relaxation as a result of the annihilation of frozen-in defects and the topological and compositional atomic rearrangement. The values of the attempted frequency being of the order of Debye frequency suggest that the irrecoverable structural relaxation processes occur more or less independently from each other. (author)

  8. The relation between relaxed enthalpy and volume during physical aging of amorphous polymers and selenium

    Czech Academy of Sciences Publication Activity Database

    Slobodian, P.; Říha, Pavel; Rychwalski, R. W.; Emri, I.; Sáha, P.; Kubát, J.

    2006-01-01

    Roč. 42, č. 10 (2006), s. 2824-2837 ISSN 0014-3057 R&D Projects: GA AV ČR IAA2060401 Institutional research plan: CEZ:AV0Z20600510 Keywords : Enthalpy relaxation * Polymer aging Subject RIV: BJ - Thermodynamics Impact factor: 2.113, year: 2006

  9. Estimation of water-coal surface interaction during heat treatment of coal by use of FTir and DSC; FTir to DSC wo mochiita sekitan-mizu kan sogo sayo no teiryoteki hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Miura, K.; Mae, K.; Morozumi, F.; Kusakawa, T. [Kyoto University, Kyoto (Japan)

    1997-10-30

    The authors have recently presented a method to estimate the strength distribution of hydrogen bondings in coal using FTir and DSC. The method was applied to estimate the strength of coal-water interaction in two different coals and to estimate the enthalpy change deriving from the change in hydrogen bondings during the desorption of water. The estimated enthalpy change was compared with the total enthalpy change estimated by DSC measurement to examine the importance of hydrogen bondings during the desertion of water. 1 ref., 6 figs.

  10. Applicability of the theory of thermodynamic similarity to predict the enthalpies of vaporization of aliphatic aldehydes

    Science.gov (United States)

    Esina, Z. N.; Korchuganova, M. R.

    2015-06-01

    The theory of thermodynamic similarity is used to predict the enthalpies of vaporization of aliphatic aldehydes. The predicted data allow us to calculate the phase diagrams of liquid-vapor equilibrium in a binary water-aliphatic aldehyde system.

  11. A Mixed Enthalpy-Temperature Finite Element Method For Generalized Phase-Change Problems

    DEFF Research Database (Denmark)

    krabbenhøft, Kristian; Damkilde, Lars

    2003-01-01

    In a large number of problems of engineering interest the transition of the material from one phase to another is of vital importance in describing the overall physical behaviour. Common applications include metal casting, freezing and thawing of foodstuffs and other biological materials, ground ...... freezing and solar energy storage. The phase-change problem is characterized by an abrupt change in enthalpy per unit temperature in a narrow temperature range around the freezing point....

  12. A Mixed Enthalpy-Temperature Finite Element Method For Generalized Phase-Change Problems

    DEFF Research Database (Denmark)

    krabbenhøft, Kristian; Damkilde, Lars

    2003-01-01

    In a large number of problems of engineering interest the transition of the material from one phase to another is of vital importance in describing the overall physical behaviour. Common applications include metal casting, freezing and thawing of foodstuffs and other biological materials, ground...... freezing and solar energy storage. The phase-change problem is characterized by an abrupt change in enthalpy per unit temperature in a narrow temperature range around the freezing point....

  13. Experimental measurement of enthalpy increments of Th0.25Ce0.75O2

    International Nuclear Information System (INIS)

    Babu, R.; Balakrishnan, S.; Ananthasivan, K.; Nagarajan, K.

    2013-01-01

    Thorium has been suggested as an alternative fertile material for a nuclear fuel cycle, and an inert matrix for burning plutonium and for waste disposal. The third stage of India's nuclear power programme envisages utilization of thorium and plutonium as a fuel in Advanced Heavy Water Reactor (AHWR) and Accelerator Driven Sub-critical Systems (ADSS). Solid solutions of ThO 2 -PuO 2 are of importance because of coexistence of Th with Pu during the breeding cycle. CeO 2 is used as a PuO 2 analog due to similar ionic radii of cations and similar physico-chemical properties of the oxides. ThO 2 forms a homogeneous solid solution with the cubic fluorite structure when doped with Ce in the entire compositional range. In the development of mixed oxide nuclear fuels, knowledge of thermodynamic properties of thorium oxide and its mixtures has become extremely importance for understanding the fuel behavior during irradiation and for predicting the performance of the fuel under accidental conditions. Thermodynamic functions such as the enthalpy increment and heat capacity of the theria-ceria solid solution have not been measured experimentally. Hence, the enthalpy increments of thoria-ceria solid solutions, Th 0.25 Ce 0.75 O 2 by inverse drop calorimetry in the temperature range 523-1723 K have been measured. The measured enthalpy increments were fitted in to polynomial functions by using the least squares method and the other thermodynamic functions such as heat capacity, entropy and Gibbs energy functions were computed in the temperature range 298-1800 K. The reported thermodynamic functions for Th 0.25 Ce 0.75 O 2 forms the first experimental data and the heat capacity of (Th,Ce)O 2 solid solutions was shown to obey the Neumann-Kopp's rule. (author)

  14. Formation enthalpies of LaLn'O{sub 3} (Ln'=Ho, Er, Tm and Yb) interlanthanide perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Jianqi [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Laboratory of High Energy Density Physics of Ministry of Education, Sichuan University, Chengdu 610064 (China); Guo, Xiaofeng [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); Mielewczyk-Gryn, Aleksandra [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); Faculty of Applied Physics and Mathematics, Department of Solid State Physics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk (Poland); Navrotsky, Alexandra, E-mail: anavrotsky@ucdavis.edu [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States)

    2015-07-15

    High-temperature oxide melt solution calorimetry using 3Na{sub 2}O·MoO{sub 3} at 802 °C was performed for interlanthanide perovskites LaLn'O{sub 3} (Ln'=Ho, Er, Tm and Yb) and lanthanide oxides (La{sub 2}O{sub 3}, Ho{sub 2}O{sub 3}, Er{sub 2}O{sub 3}, Tm{sub 2}O{sub 3} and Yb{sub 2}O{sub 3}). The enthalpies of formation of these interlanthanide perovskites from binary lanthanide oxides at room temperature (25 °C) were determined to be −8.3±3.4 kJ/mol for LaHoO{sub 3}, −9.9±3.0 kJ/mol for LaErO{sub 3}, −10.8±2.7 kJ/mol for LaTmO{sub 3} and −12.3±2.9 kJ/mol for LaYbO{sub 3}. There is a roughly linear relationships between these enthalpy values and the tolerance factor for these and for other LaM{sup 3+}O{sub 3} (M=In, Sc, Ga, Al, Fe and Cr) perovskites, confirming that the distortion of the perovskites as results from ionic radius difference of A-site and B-site cations, is the main factor determining the stability of these compounds. - Graphical abstract: A linear relationship between the enthalpy of formation and the tolerance factor for interlanthanide LaLn'O{sub 3} (Ln'=Ho, Er, Tm, and Yb) and other LaM{sup 3+}O{sub 3} (M=In, Sc, Ga, Al, Fe and Cr) perovskites. - Highlights: • Interlanthanide perovskites were synthesized by solid state reactions. • Their enthalpies of formation were measured by oxide melt solution calorimetry. • ΔH{sub f,ox} shows a linear relationship with tolerance factor.

  15. Interaction of Hydrogen with MOF-5.

    Science.gov (United States)

    Bordiga, Silvia; Vitillo, Jenny G; Ricchiardi, Gabriele; Regli, Laura; Cocina, Donato; Zecchina, Adriano; Arstad, Bjørnar; Bjørgen, Morten; Hafizovic, Jasmina; Lillerud, Karl Petter

    2005-10-06

    Hydrogen storage is among the most demanding challenges in the hydrogen-based energy cycle. One proposed strategy for hydrogen storage is based on physisorption on high surface area solids such as metal-organic frameworks (MOFs). Within this class of materials, MOF-5 has been the first structure studied for hydrogen storage. The IR spectroscopy of adsorbed H2 performed at 15 K and ab initio calculations show that the adsorptive properties of this material are mainly due to dispersive interactions with the internal wall structure and to weak electrostatic forces associated with O13Zn4 clusters. Calculated and measured binding enthalpies are between 2.26 and 3.5 kJ/mol, in agreement with the H2 rotational barriers reported in the literature. A minority of binding sites with higher adsorption enthalpy (7.4 kJ/mol) is also observed. These species are probably associated with OH groups on the external surfaces present as termini of the microcrystals.

  16. Fractured Anhydrite as a Geothermal Source in a Low Enthalpy Context (Southern Permian Basin, Netherlands)

    NARCIS (Netherlands)

    Daniilidis, Alexandros; Herber, Marinus

    2015-01-01

    Increased heat flow associated with the presence of salt domes could be beneficial for geothermal energy applications in a low enthalpy nvironment. Anhydrite layers within such salt domes could be a potential geothermal target. These layers are known to undergo brittle deformation, which in turn can

  17. Vapor pressures and standard molar enthalpies, entropies, and Gibbs free energies of sublimation of 2,4- and 3,4-dinitrobenzoic acids

    International Nuclear Information System (INIS)

    Vecchio, Stefano; Brunetti, Bruno

    2009-01-01

    The vapor pressures of the solid and liquid 2,4- and 3,4-dinitrobenzoic acids were determined by torsion-effusion and thermogravimetry under both isothermal and non-isothermal conditions, respectively. From the temperature dependence of vapor pressure derived by the experimental torsion-effusion and thermogravimetry data the molar enthalpies of sublimation Δ cr g H m 0 ( ) and vaporization Δ l g H m 0 ( ) were determined, respectively, at the middle of the respective temperature intervals. The melting temperatures and the molar enthalpies of fusion of these compounds were measured by d.s.c. Finally, the results obtained by all the methods proposed were corrected at the reference temperature of 298.15 K using the estimated heat capacity differences between gas and liquid for vaporization experiments and the estimated heat capacity differences between gas and solid for sublimation experiments. Therefore, the averages of the standard (p o = 0.1 MPa) molar enthalpies, entropies and Gibbs free energies of sublimation at 298.15 K, have been derived.

  18. Extremes temperatures and enthalpy in Finland and Sweden in a changing climate

    International Nuclear Information System (INIS)

    Venaelaeinen, A.; Saku, S.; Jylhae, K.; Nikulin, G.; Kjellstroem, E.; Baerring, L.

    2009-06-01

    Though risks caused by harsh weather conditions are taken into account in the planning of nuclear power plants, some exceptional weather events or combination of different events may prevent normal power operation and simultaneously endanger safe shutdown of the plant. Extreme weather events could influence, for example, the external power grid connection, emergency diesel generators (blockage of air intakes), ventilation and cooling of electric and electronics equipment rooms and the seawater intake. Due to the influence of an intensified greenhouse effect the climate is changing rapidly during the coming decades and this change is expected to have an influence also on the occurrence of extreme weather events. In this report we have examined extreme temperatures. Enthalpy is a parameter that combines air temperature and air humidity and it is used in the design of air conditioning systems. Therefore, we have included also return levels of enthalpy in our analysis. The influence of climate change on extreme temperatures is analysed based on regional climate model simulations. The reoccurrence times of high temperatures combined with high air humidity was analysed based on measurements made at five Finnish and three Swedish meteorological stations. Based on the observational records we find the 10 year return level of daily maximum temperature to be around 32 deg. C and the 100 year return level around 35 deg. C. If we look the return levels of warm and humid conditions then for example in Helsinki the 10 year return level of one week mean temperature in case mean air humidity is above 80% is 20.1 deg. C. The 10 year return level of daily maximum enthalpy is around 60 kJ/kg and the 100 year return level almost 70 kJ/kg. According to the climate model simulations the largest increase of 50-year return level of daily maximum temperature is found in southern Sweden and south-western Finland. By the end of this century the increase can be 3-5 deg. C. The largest change

  19. Extremes temperatures and enthalpy in Finland and Sweden in a changing climate

    Energy Technology Data Exchange (ETDEWEB)

    Venaelaeinen, A.; Saku, S.; Jylhae, K. (Finnish Meteorological Institute (Finland)); Nikulin, G.; Kjellstroem, E.; Baerring, L. (Swedish Meteorological Institute (Sweden))

    2009-06-15

    Though risks caused by harsh weather conditions are taken into account in the planning of nuclear power plants, some exceptional weather events or combination of different events may prevent normal power operation and simultaneously endanger safe shutdown of the plant. Extreme weather events could influence, for example, the external power grid connection, emergency diesel generators (blockage of air intakes), ventilation and cooling of electric and electronics equipment rooms and the seawater intake. Due to the influence of an intensified greenhouse effect the climate is changing rapidly during the coming decades and this change is expected to have an influence also on the occurrence of extreme weather events. In this report we have examined extreme temperatures. Enthalpy is a parameter that combines air temperature and air humidity and it is used in the design of air conditioning systems. Therefore, we have included also return levels of enthalpy in our analysis. The influence of climate change on extreme temperatures is analysed based on regional climate model simulations. The reoccurrence times of high temperatures combined with high air humidity was analysed based on measurements made at five Finnish and three Swedish meteorological stations. Based on the observational records we find the 10 year return level of daily maximum temperature to be around 32 deg. C and the 100 year return level around 35 deg. C. If we look the return levels of warm and humid conditions then for example in Helsinki the 10 year return level of one week mean temperature in case mean air humidity is above 80% is 20.1 deg. C. The 10 year return level of daily maximum enthalpy is around 60 kJ/kg and the 100 year return level almost 70 kJ/kg. According to the climate model simulations the largest increase of 50-year return level of daily maximum temperature is found in southern Sweden and south-western Finland. By the end of this century the increase can be 3-5 deg. C. The largest change

  20. Standard enthalpies of formation of selected Ru{sub 2}YZ Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Ming, E-mail: myin1@hawk.iit.edu; Nash, Philip

    2015-06-15

    Highlights: • Standard enthalpies of formation of Ru{sub 2}YZ were measured using a drop calorimeter. • Result of L2{sub 1} structured compounds agrees with first principles data. • Lattice parameters and related phase relationships were consistent with literature data. • Ru{sub 2}HfSn, Ru{sub 2}TiSn, Ru{sub 2}VGa, Ru{sub 2}VSi, Ru{sub 2}VSn of L2{sub 1} structure were reported for the first time. - Abstract: The standard enthalpies of formation of selected ternary Ru-based Heusler compounds Ru{sub 2}YZ (Y = Fe, Hf, Mn, Ti, V; Z = Al, Ga, In, Si, Ge, Sn) were measured using high temperature direct reaction calorimetry. The measured enthalpies of formation (in kJ/mole of atoms) of the Heusler compounds are, Ru{sub 2}FeGe (−19.7 ± 3.3); Ru{sub 2}HfSn (−24.9 ± 3.6); Ru{sub 2}MnSi (−46.0 ± 2.6); Ru{sub 2}MnGe (−29.7 ± 1.0); Ru{sub 2}MnSn (−20.6 ± 2.4); Ru{sub 2}TiSi (−94.9 ± 4.0); Ru{sub 2}TiGe (−79.1 ± 3.2); Ru{sub 2}TiSn (−60.6 ± 1.8); Ru{sub 2}VSi (−55.9 ± 1.7);for the B2-structured compounds, Ru{sub 2}FeSi (−28.5 ± 0.8); Ru{sub 2}HfAl (−70.8 ± 1.9); Ru{sub 2}MnAl (−32.3 ± 1.9); Ru{sub 2}MnGa (−25.3 ± 3.0); Ru{sub 2}TiAl (−62.7 ± 3.5); Ru{sub 2}VAl (−30.9 ± 1.6); Ru{sub 2}ZrAl (−64.5 ± 1.5). Values were compared with those from published first principles calculations and the OQMD (Open Quantum Materials Database). Lattice parameters of these compounds were determined using X-ray diffraction analysis (XRD). Microstructures were identified using scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS)

  1. Entropic Ratchet transport of interacting active Brownian particles

    Energy Technology Data Exchange (ETDEWEB)

    Ai, Bao-Quan, E-mail: aibq@hotmail.com [Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, 510006 Guangzhou (China); He, Ya-Feng [College of Physics Science and Technology, Hebei University, 071002 Baoding (China); Zhong, Wei-Rong, E-mail: wrzhong@jnu.edu.cn [Department of Physics and Siyuan Laboratory, College of Science and Engineering, Jinan University, 510632 Guangzhou (China)

    2014-11-21

    Directed transport of interacting active (self-propelled) Brownian particles is numerically investigated in confined geometries (entropic barriers). The self-propelled velocity can break thermodynamical equilibrium and induce the directed transport. It is found that the interaction between active particles can greatly affect the ratchet transport. For attractive particles, on increasing the interaction strength, the average velocity first decreases to its minima, then increases, and finally decreases to zero. For repulsive particles, when the interaction is very weak, there exists a critical interaction at which the average velocity is minimal, nearly tends to zero, however, for the strong interaction, the average velocity is independent of the interaction.

  2. Entropic Ratchet transport of interacting active Brownian particles

    International Nuclear Information System (INIS)

    Ai, Bao-Quan; He, Ya-Feng; Zhong, Wei-Rong

    2014-01-01

    Directed transport of interacting active (self-propelled) Brownian particles is numerically investigated in confined geometries (entropic barriers). The self-propelled velocity can break thermodynamical equilibrium and induce the directed transport. It is found that the interaction between active particles can greatly affect the ratchet transport. For attractive particles, on increasing the interaction strength, the average velocity first decreases to its minima, then increases, and finally decreases to zero. For repulsive particles, when the interaction is very weak, there exists a critical interaction at which the average velocity is minimal, nearly tends to zero, however, for the strong interaction, the average velocity is independent of the interaction

  3. Thermodynamic state, specific heat, and enthalpy function of saturated UO2 vapor between 3,000 K and 5,000 K

    International Nuclear Information System (INIS)

    Karow, H.U.

    1977-02-01

    The properties have been determined by means of statistical mechanics. The discussion of the thermodynamic state includes the evaluation of the plasma state and its contribution to the caloric variables-of-state of saturated oxide fuel vapor. Because of the extremely high ion and electron density due to thermal ionization, the ionized component of the fuel vapor does no more represent a perfect kinetic plasma. At temperatures around 5,000 K, UO 2 vapor reaches the collective plasma state and becomes increasingly 'metallic'. - Moreover, the nonuniform molecular equilibrium composition of UO 2 vapor has been taken into account in calculating its caloric functions-of-state. The contribution to specific heat and enthalpy of thermally excited electronic states of the vapor molecules has been derived by means of a Rydberg orbital model of the UO 2 molecule. The resulting enthalpy functions and specific heats for saturated UO 2 vapor of equilibrium composition and that for pure UO 2 gas are compared with the enthalpy and specific heat data of gaseous UO 2 at lower temperatures known from literature. (orig./HP) [de

  4. Microcalorimetric and spectrographic studies on host-guest interactions of {alpha}-, {beta}-, {gamma}- and M{beta}-cyclodextrin with resveratrol

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hui; Xu, Xiangyu; Liu, Min [College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, Shandong Province (China); Sun, Dezhi, E-mail: sundezhisdz@163.com [College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, Shandong Province (China); Li, Linwei, E-mail: lilinwei@lcu.edu.cn [College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, Shandong Province (China)

    2010-10-20

    Thermal effects of inclusion processes of {alpha}-, {beta}-, {gamma}- and M{beta}-cyclodextrin with resveratrol (RES) in aqueous solutions were determined by isothermal titration calorimetry (ITC) with nanowatt sensitivity at the temperature of 298.15 K. Standard enthalpy changes, stoichiometry and equilibrium constants of the inclusion complexes were derived from the direct calorimetric data utilizing nonlinear simulation. The thermodynamic parameters were discussed in the light of weak interactions between the host and the guest molecules combining with UV spectral message. The results indicate that all of the complexes formed in the aqueous solutions are in 1:1 stoichiometry. The binding processes of {alpha}-, {beta}- and M{beta}-cyclodextrin with the guest are mainly driven by enthalpy, while that of {gamma}-cyclodextrin with the drug is driven by both enthalpy and entropy.

  5. Power-feedwater enthalpy operating domain for SBWR applying Monte Carlo simulation

    International Nuclear Information System (INIS)

    Quezada-Garcia, S.; Espinosa-Martinez, E.-G.; Vazquez-Rodriguez, A.; Varela-Ham, J.R.; Espinosa-Paredes, G.

    2014-01-01

    In this work the analyses of the feedwater enthalpy effects on reactor power in a simplified boiling water reactor (SBWR) applying a methodology based on Monte Carlo's simulation (MCS), is presented. The MCS methodology was applied systematically to establish operating domain, due that the SBWR are not yet in operation, the analysis of the nuclear and thermalhydraulic processes must rely on numerical modeling, with the purpose of developing or confirming the design basis and qualifying the existing or new computer codes to enable reliable analyses. (author)

  6. A moderate enthalpy and a low pollution load in healthy buildings

    DEFF Research Database (Denmark)

    Fanger, Povl Ole

    1998-01-01

    For the design of healthy buildings with a comfortable indoor environment, some general recommendations are provided. New research highlights the importance of controlling the enthalpy of indoor air at a moderate level, i.e., by controlling air temperature and relative humidity at a rather low...... level, still compatible with thermal comfort. A decrement of air temperature or humidity improves the perceived air quality and may decrease the required ventilation rate. A moderate air temperature and humidity plus individual control by radiation and conduction is recommended in order to decrease...

  7. The Relationship between Lattice Enthalpy and Melting Point in Magnesium and Aluminium Oxides. Science Notes

    Science.gov (United States)

    Talbot, Christopher; Yap, Lydia

    2013-01-01

    This "Science Note" presents a study by Christopher Talbot and Lydia Yap, who teach IB Chemistry at Anglo-Chinese School (Independent), Republic of Singapore, to pre-university students. Pre-university students may postulate the correlation between the magnitude of the lattice enthalpy compound and its melting point, since both…

  8. Understanding the Relationship between Red Wine Matrix, Tannin Activity, and Sensory Properties.

    Science.gov (United States)

    Watrelot, Aude A; Byrnes, Nadia K; Heymann, Hildegarde; Kennedy, James A

    2016-11-30

    One major red wine mouthfeel characteristic, astringency, is derived from grape-extracted tannins and is considered to be a result of interaction with salivary proteins and the oral mucosa. To improve our understanding of the role that the enthalpy of interaction of tannin with a hydrophobic surface (tannin activity) has in astringency perception, a chromatographic method was used to determine the tannin concentration and activity of 34 Cabernet Sauvignon wines, as well as sensory analysis done on 13 of those wines. In addition, astringency-relevant matrix parameters (pH, titratable acidity, ethanol, glucose, and fructose) were measured across all wines. Tannin activity was not significantly correlated with any matrix variables, and the perception of drying and grippy was not correlated with tannin concentration and activity. However, ethanol content was well related to mouthfeel attributes and appeared to drive perceived drying. Although fructose and glucose content were well correlated, they did not drive the perception of sweetness, which is explained by the well-known mixture suppression effect.

  9. The molar enthalpies of solution and vapour pressures of saturated aqueous solutions of some cesium salts

    International Nuclear Information System (INIS)

    Apelblat, Alexander; Korin, Eli

    2006-01-01

    Vapour pressures of water over saturated solutions of cesium chloride, cesium bromide, cesium nitrate, cesium sulfate, cesium formate, and cesium oxalate were determined as a function of temperature. These vapour pressures were used to evaluate the water activities, osmotic coefficients and molar enthalpies of vapourization. Molar enthalpies of solution of cesium chloride, Δ sol H m (T = 295.73 K; m = 0.0622 mol . kg -1 ) = (17.83 ± 0.50) kJ . mol -1 ; cesium bromide, Δ sol H m (T = 293.99 K; m = 0.0238 mol . kg -1 ) = (26.91 ± 0.59) kJ . mol -1 ; cesium nitrate, Δ sol H m (T = 294.68 K; m = 0.0258 mol . kg -1 ) = (37.1 ± 2.3) kJ . mol -1 ; cesium sulfate, Δ sol H m (T = 296.43 K; m = 0.0284 mol . kg -1 ) (16.94 ± 0.43) kJ . mol -1 ; cesium formate, Δ sol H m (T = 295.64 K; m = 0.0283 mol . kg -1 ) = (11.10 ± 0.26) kJ . mol -1 and Δ sol H m (T = 292.64 K; m = 0.0577 mol . kg -1 ) = (11.56 ± 0.56) kJ . mol -1 ; and cesium oxalate, Δ sol H m (T = 291.34 K; m = 0.0143 mol . kg -1 ) = (22.07 ± 0.16) kJ . mol -1 were determined calorimetrically. The purity of the chemicals was generally greater than 0.99 mass fraction, except for HCOOCs and (COOCs) 2 where purities were approximately 0.95 and 0.97 mass fraction, respectively. The uncertainties are one standard deviations

  10. Bayesian Statistical Mechanics: Entropy-Enthalpy Compensation and Universal Equation of State at the Tip of Pen

    Directory of Open Access Journals (Sweden)

    Evgeni B. Starikov

    2018-02-01

    Full Text Available This work has shown the way to put the formal statistical-mechanical basement under the hotly debated notion of enthalpy-entropy compensation. The possibility of writing down the universal equation of state based upon the statistical mechanics is discussed here.

  11. Determination of saturation pressure and enthalpy of vaporization of semi-volatile aerosols: the integrated volume mentod

    Science.gov (United States)

    This study presents the integrated volume method for estimating saturation pressure and enthalpy of vaporization of a whole aerosol distribution. We measure the change of total volume of an aerosol distribution between a reference state and several heated states, with the heating...

  12. Prediction of enthalpy of fusion of pure compounds using an Artificial Neural Network-Group Contribution method

    International Nuclear Information System (INIS)

    Gharagheizi, Farhad; Salehi, Gholam Reza

    2011-01-01

    Highlights: → An Artificial Neural Network-Group Contribution method is presented for prediction of enthalpy of fusion of pure compounds at their normal melting point. → Validity of the model is confirmed using a large evaluated data set containing 4157 pure compounds. → The average percent error of the model is equal to 2.65% in comparison with the experimental data. - Abstract: In this work, the Artificial Neural Network-Group Contribution (ANN-GC) method is applied to estimate the enthalpy of fusion of pure chemical compounds at their normal melting point. 4157 pure compounds from various chemical families are investigated to propose a comprehensive and predictive model. The obtained results show the Squared Correlation Coefficient (R 2 ) of 0.999, Root Mean Square Error of 0.82 kJ/mol, and average absolute deviation lower than 2.65% for the estimated properties from existing experimental values.

  13. The Correlation of Standard Entropy with Enthalpy Supplied from 0 to 298.15 K

    Science.gov (United States)

    Lambert, Frank L.; Leff, Harvey S.

    2009-01-01

    As a substance is heated at constant pressure from near 0 K to 298 K, each incremental enthalpy increase, dH, alters entropy by dH/T, bringing it from approximately zero to its standard molar entropy S degrees. Using heat capacity data for 32 solids and CODATA results for another 45, we found a roughly linear relationship between S degrees and…

  14. Enthalpies of formation of europium alkoxides: What lessons can be drawn from them

    International Nuclear Information System (INIS)

    Branco, Joaquim B.; Carretas, José M.; Epple, Matthias; Cruz, Adelaide; Pires de Matos, A.; Leal, João Paulo

    2014-01-01

    Highlights: • First time measurement of europium(II) alkoxides enthalpy of formation. • Calculation of alkoxides thermochemical radii and M–O distances in this environment. • Comparison of experimental EXAFS distance with the calculated ones. • Hints on the type of bond existing in these compounds. • Correlation of bond type and possible use as catalysts. - Abstract: The synthesis and characterization of two europium alkoxides, Eu(OCH 3 ) 2 and Eu(OC 2 H 5 ) 2 , were described. For the first time the enthalpies of formation of divalent lanthanide alkoxides were determined by using reaction-solution calorimetry. The values obtained are Δ f H 0 [Eu(OCH 3 ) 2 ,cr] = −850.5 ± 5.0 kJ/mol and Δ f H 0 [Eu(OC 2 H 5 ) 2 ,cr] = −902.5 ± 5.5 kJ/mol, respectively. Since these compounds have a large use as catalysts or catalysts precursors, the first step of the reaction of them with CO 2 was addressed, which permits to have an idea of the kind of bond involved in those compounds. Moreover, insertion of CO 2 in the europium oxygen bond and formation of metal carboxylate complexes, is in both cases presumably bidentate

  15. Three-dimensional quantitative structure-property relationship (3D-QSPR) models for prediction of thermodynamic properties of polychlorinated biphenyls (PCBs): enthalpy of vaporization.

    Science.gov (United States)

    Puri, Swati; Chickos, James S; Welsh, William J

    2002-01-01

    Three-dimensional Quantitative Structure-Property Relationship (QSPR) models have been derived using Comparative Molecular Field Analysis (CoMFA) to correlate the vaporization enthalpies of a representative set of polychlorinated biphenyls (PCBs) at 298.15 K with their CoMFA-calculated physicochemical properties. Various alignment schemes, such as inertial, as is, and atom fit, were employed in this study. The CoMFA models were also developed using different partial charge formalisms, namely, electrostatic potential (ESP) charges and Gasteiger-Marsili (GM) charges. The most predictive model for vaporization enthalpy (Delta(vap)H(m)(298.15 K)), with atom fit alignment and Gasteiger-Marsili charges, yielded r2 values 0.852 (cross-validated) and 0.996 (conventional). The vaporization enthalpies of PCBs increased with the number of chlorine atoms and were found to be larger for the meta- and para-substituted isomers. This model was used to predict Delta(vap)H(m)(298.15 K) of the entire set of 209 PCB congeners.

  16. Gene-physical activity interactions and their impact on diabetes

    DEFF Research Database (Denmark)

    Oskari Kilpeläinen, Tuomas; Franks, Paul W

    2014-01-01

    to an equal bout of physical activity. Individuals with specific genetic profiles are also expected to be more responsive to the beneficial effects of physical activity in the prevention of type 2 diabetes. Identification of such gene-physical activity interactions could give new insights into the biological...... the reader to the recent advances in the genetics of type 2 diabetes, summarize the current evidence on gene-physical activity interactions in relation to type 2 diabetes, and outline how information on gene-physical activity interactions might help improve the prevention and treatment of type 2 diabetes....... Finally, we will discuss the existing and emerging strategies that might enhance our ability to identify and exploit gene-physical activity interactions in the etiology of type 2 diabetes. © 2014 S. Karger AG, Basel....

  17. An evaluation of interferences in heat production from low enthalpy geothermal doublets systems

    DEFF Research Database (Denmark)

    Willems, Cees J. L.; Nick, Hamidreza M.; Weltje, Gert Jan

    2017-01-01

    Required distance between doublet systems in low enthalpy geothermal heat exploitation is often not fully elucidated. The required distance aims to prevent negative interference influencing the utilisation efficiency of doublet systems. Currently production licence areas are often issued based...... and minimal required production temperature. The results of this study can be used to minimize negative interference or optimise positive interference aiming at improving geothermal doublet deployment efficiency. (C) 2017 The Authors. Published by Elsevier Ltd....

  18. Vapor pressures and sublimation enthalpies of seven heteroatomic aromatic hydrocarbons measured using the Knudsen effusion technique

    International Nuclear Information System (INIS)

    Goldfarb, Jillian L.; Suuberg, Eric M.

    2010-01-01

    The vapor pressures of seven heteroatom-containing cyclic aromatic hydrocarbons, ranging in molecular weight from (168.19 to 208.21) g . mol -1 were measured over the temperature range of (301 to 486) K using the isothermal Knudsen effusion technique. The compounds measured include: anthraquinone, 9-fluorenone, 9-fluorenone oxime, phenoxazine, phenoxathiin, and 9H-pyrido[3,4-b]indole. These solid-state sublimation measurements provided values that are compared to vapor pressures of parent aromatic compounds (anthracene and fluorene) and to others with substituent groups in order to examine the effects of alcohol, ketone, pyridine, and pyrrole functionality on this property. The enthalpies and entropies of sublimation for each compound were determined from the Clausius-Clapeyron equation. Though there is no consistent trend in terms of the effects of substitutions on changes in the enthalpy or entropy of sublimation, we note that the prevalence of enthalpic or entropic driving forces on vapor pressure depend on molecule-specific factors and not merely molecular weight of the substituents.

  19. Facing the challenge of predicting the standard formation enthalpies of n-butyl-phosphate species with ab initio methods

    Science.gov (United States)

    Saab, Mohamad; Réal, Florent; Šulka, Martin; Cantrel, Laurent; Virot, François; Vallet, Valérie

    2017-06-01

    Tributyl-phosphate (TBP), a ligand used in the PUREX liquid-liquid separation process of spent nuclear fuel, can form an explosive mixture in contact with nitric acid that might lead to a violent explosive thermal runaway. In the context of safety of a nuclear reprocessing plant facility, it is crucial to predict the stability of TBP at elevated temperatures. So far, only the enthalpies of formation of TBP are available in the literature with rather large uncertainties, while those of its degradation products, di-(HDBP) and mono-(H2MBP), are unknown. In this goal, we have used state-of-the art quantum chemical methods to compute the formation enthalpies and entropies of TBP and its degradation products di-(HDBP) and mono-(H2MBP) in gas and liquid phases. Comparisons of levels of quantum chemical theory revealed that there are significant effects of correlation on their electronic structures, pushing for the need of not only high level of electronic correlation treatment, namely, local coupled cluster with single and double excitation operators and perturbative treatment of triple excitations, but also extrapolations to the complete basis to produce reliable and accurate thermodynamics data. Solvation enthalpies were computed with the conductor-like screening model for real solvents [COSMO-RS], for which we observe errors not exceeding 22 kJ mol-1. We thus propose with final uncertainty of about 20 kJ mol-1 standard enthalpies of formation of TBP, HDBP, and H2MBP which amounts to -1281.7 ± 24.4, -1229.4 ± 19.6, and -1176.7 ± 14.8 kJ mol-1, respectively, in the gas phase. In the liquid phase, the predicted values are -1367.3 ± 24.4, -1348.7 ± 19.6, and -1323.8± 14.8 kJ mol-1, to which we may add about -22 kJ mol-1 error from the COSMO-RS solvent model. From these data, the complete hydrolysis of TBP is predicted as an exothermic phenomena but showing a slightly endergonic process.

  20. Interactive activation and mutual constraint satisfaction in perception and cognition.

    Science.gov (United States)

    McClelland, James L; Mirman, Daniel; Bolger, Donald J; Khaitan, Pranav

    2014-08-01

    In a seminal 1977 article, Rumelhart argued that perception required the simultaneous use of multiple sources of information, allowing perceivers to optimally interpret sensory information at many levels of representation in real time as information arrives. Building on Rumelhart's arguments, we present the Interactive Activation hypothesis-the idea that the mechanism used in perception and comprehension to achieve these feats exploits an interactive activation process implemented through the bidirectional propagation of activation among simple processing units. We then examine the interactive activation model of letter and word perception and the TRACE model of speech perception, as early attempts to explore this hypothesis, and review the experimental evidence relevant to their assumptions and predictions. We consider how well these models address the computational challenge posed by the problem of perception, and we consider how consistent they are with evidence from behavioral experiments. We examine empirical and theoretical controversies surrounding the idea of interactive processing, including a controversy that swirls around the relationship between interactive computation and optimal Bayesian inference. Some of the implementation details of early versions of interactive activation models caused deviation from optimality and from aspects of human performance data. More recent versions of these models, however, overcome these deficiencies. Among these is a model called the multinomial interactive activation model, which explicitly links interactive activation and Bayesian computations. We also review evidence from neurophysiological and neuroimaging studies supporting the view that interactive processing is a characteristic of the perceptual processing machinery in the brain. In sum, we argue that a computational analysis, as well as behavioral and neuroscience evidence, all support the Interactive Activation hypothesis. The evidence suggests that

  1. Thermodynamics of solvent interaction with the metal-organic framework MOF-5.

    Science.gov (United States)

    Akimbekov, Zamirbek; Wu, Di; Brozek, Carl K; Dincă, Mircea; Navrotsky, Alexandra

    2016-01-14

    The inclusion of solvent in metal-organic framework (MOF) materials is a highly specific form of guest-host interaction. In this work, the energetics of solvent MOF-5 interactions has been investigated by solution calorimetry in 5 M sodium hydroxide (NaOH) at room temperature. Solution calorimetric measurement of enthalpy of formation (ΔH(f)) of Zn4O(C8H4O4)3·C3H7NO (MOF-5·DMF) and Zn4O(C8H4O4)3·0.60C5H11NO (MOF-5·0.60DEF) from the dense components zinc oxide (ZnO), 1,4-benzenedicarboxylic acid (H2BDC), N,N-dimethylformamide (DMF) and N,N-diethylformamide (DEF) gives values of 16.69 ± 1.21 and 45.90 ± 1.46 kJ (mol Zn4O)(-1), respectively. The enthalpies of interaction (ΔH(int)) for DMF and DEF with MOF-5 are -82.78 ± 4.84 kJ (mol DMF)(-1) and -89.28 ± 3.05 kJ (mol DEF)(-1), respectively. These exothermic interaction energies suggest that, at low guest loading, Lewis base solvents interact more strongly with electron accepting Zn4O clusters in the MOF than at high solvent loading. These data provide a quantitative thermodynamic basis to investigate transmetallation and solvent assisted linker exchange (SALE) methods and to synthesize new MOFs.

  2. Activation volume and interaction of metal particulate media

    Energy Technology Data Exchange (ETDEWEB)

    Tetsukawa, Hiroki [Sony Corporation, 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo 141-0001 (Japan)]. E-mail: tetsukaw@arc.sony.co.jp; Kondo, Hirofumi [Sony Corporation, 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo 141-0001 (Japan)

    2005-09-15

    We have investigated the activation volume (V{sub ac}) and magnetostatic interaction of metal particulate (MP) media. The activation volume of MP media decreases with the decrease of physical volume (V{sub phy}) of metal particles. The activation volume and the ratio of V{sub phy}/V{sub ac} of advanced metal particles are 6x10{sup -24}m{sup 3} and 1.5, respectively. It can be predicted that the physical volume of metal particle is about 3x10{sup -24}m{sup 3} when the physical volume is equal to the activation volume. This value is agreement with the practical lower limit of physical volume of metal particle predicted by Sharrock. The negative interaction (demagnetization effect) in MP media decreases with low saturation magnetization of the metal particles, a thin magnetic layer, a high orientation of MP media, and a low packing fraction of metal particles in the MP media. The activation volume of the MP media decreased as the negative interactions decreased. In advanced MP media with low M{sub r}.t (M{sub r}=remanent magnetization and t=thickness), the influence of interaction on the activation volume is reduced.

  3. Activation volume and interaction of metal particulate media

    International Nuclear Information System (INIS)

    Tetsukawa, Hiroki; Kondo, Hirofumi

    2005-01-01

    We have investigated the activation volume (V ac ) and magnetostatic interaction of metal particulate (MP) media. The activation volume of MP media decreases with the decrease of physical volume (V phy ) of metal particles. The activation volume and the ratio of V phy /V ac of advanced metal particles are 6x10 -24 m 3 and 1.5, respectively. It can be predicted that the physical volume of metal particle is about 3x10 -24 m 3 when the physical volume is equal to the activation volume. This value is agreement with the practical lower limit of physical volume of metal particle predicted by Sharrock. The negative interaction (demagnetization effect) in MP media decreases with low saturation magnetization of the metal particles, a thin magnetic layer, a high orientation of MP media, and a low packing fraction of metal particles in the MP media. The activation volume of the MP media decreased as the negative interactions decreased. In advanced MP media with low M r .t (M r =remanent magnetization and t=thickness), the influence of interaction on the activation volume is reduced

  4. Thermodynamics of binding interactions between extracellular polymeric substances and heavy metals by isothermal titration microcalorimetry.

    Science.gov (United States)

    Yan, Peng; Xia, Jia-Shuai; Chen, You-Peng; Liu, Zhi-Ping; Guo, Jin-Song; Shen, Yu; Zhang, Cheng-Cheng; Wang, Jing

    2017-05-01

    Extracellular polymeric substances (EPS) play a crucial role in heavy metal bio-adsorption using activated sludge, but the interaction mechanism between heavy metals and EPS remains unclear. Isothermal titration calorimetry was employed to illuminate the mechanism in this study. The results indicate that binding between heavy metals and EPS is spontaneous and driven mainly by enthalpy change. Extracellular proteins in EPS are major participants in the binding process. Environmental conditions have significant impact on the adsorption performance. Divalent and trivalent cations severely impeded the binding of heavy metal ions to EPS. Electrostatic interaction mainly attributed to competition between divalent cations and heavy metal ions; trivalent cations directly competed with heavy metal ions for EPS binding sites. Trivalent cations were more competitive than divalent cations for heavy metal ion binding because they formed complexing bonds. This study facilitates a better understanding about the interaction between heavy metals and EPS in wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Characteristics of low-enthalpy geothermal applications in Greece

    International Nuclear Information System (INIS)

    Andritsos, N.; Dalabakis, P.; Karydakis, G.; Kolios, N.; Fytikas, M.

    2011-01-01

    The paper offers a brief overview of the current direct geothermal uses in Greece and discusses their characteristics, with emphasis to the economical and technical problems encountered. Greece holds a prominent place in Europe regarding the existence of promising geothermal resources (both high and low-enthalpy), which can be economically exploited. Currently, no geothermal electricity is produced in Greece. The installed capacity of direct uses at the end of 2009 is estimated at about 155 MW t , exhibiting an increase of more than 100% compared to the figures reported at the World Geothermal Congress 2005. The main uses, in decreasing share, are geothermal heat pumps, swimming and balneology, greenhouse heating and soil warming. Earth-coupled and groundwater (or seawater) heat pumps have shown a drastic expansion during the past 2-3 years, mainly due to high oil prices two years ago and easing of the license requirements for drilling shallow wells. (author)

  6. Changes of enthalpy slope in subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Collado, Francisco J.; Monne, Carlos [Universidad de Zaragoza-CPS, Departamento de Ingenieria Mecanica-Motores Termicos, Zaragoza (Spain); Pascau, Antonio [Universidad de Zaragoza-CPS, Departamento de Ciencia de los Materiales y Fluidos-Mecanica de Fluidos, Zaragoza (Spain)

    2006-03-01

    Void fraction data in subcooled flow boiling of water at low pressure measured by General Electric in the 1960s are analyzed following the classical model of Griffith et al. (in Proceedings of ASME-AIChE heat transfer conference, 58-HT-19, 1958). In addition, a new proposal for analyzing one-dimensional steady flow boiling is used. This is based on the physical fact that if the two phases have different velocities, they cannot cover the same distance - the control volume length - in the same time. So a slight modification of the heat balance is suggested, i.e., the explicit inclusion of the vapor-liquid velocity ratio or slip ratio as scaling time factor between the phases, which is successfully checked against the data. Finally, the prediction of void fraction using correlations of the net rate of change of vapor enthalpy in the fully developed regime of subcooled flow boiling is explored. (orig.)

  7. Fluorescence spectrometry of the interaction of multi-walled carbon nanotubes with catalase

    International Nuclear Information System (INIS)

    Fan, Y.; Cai, H.; Miao, J.; Yang, Q.; Li, Y.; Li, J.; Fu, D.

    2014-01-01

    The interaction of multi-walled carbon nanotubes (MWCNTs) with catalase is investigated using fluorescence and circular dichroism spectroscopic techniques. The results of the fluorescence experiments suggest that MWCNTs quench the intrinsic fluorescence of catalase via a static quenching mechanism. The circular dichroism spectral results reveal the unfolding of catalase with a significant decrease in the α-helix content in the presence of MWCNTs, which indicates that the conformation of catalase is changed in the binding process, thereby remarkably decreasing its activity. The binding constants and the number of binding sites of the MWCNT to the catalase are calculated at different temperatures. The thermodynamic parameters, such as the changes in free energy (ΔG), enthalpy (ΔH), and entropy (ΔS), are calculated using thermodynamic equations. The fact that all negative values of ΔG, ΔH, and ΔS are obtained suggests that the interaction of the MWCNTs with catalase is spontaneous, and that hydrogen bonding and van der Waals interactions play an important role in the binding process. (authors)

  8. A Non-Isothermal Chemical Lattice Boltzmann Model Incorporating Thermal Reaction Kinetics and Enthalpy Changes

    Directory of Open Access Journals (Sweden)

    Stuart Bartlett

    2017-08-01

    Full Text Available The lattice Boltzmann method is an efficient computational fluid dynamics technique that can accurately model a broad range of complex systems. As well as single-phase fluids, it can simulate thermohydrodynamic systems and passive scalar advection. In recent years, it also gained attention as a means of simulating chemical phenomena, as interest in self-organization processes increased. This paper will present a widely-used and versatile lattice Boltzmann model that can simultaneously incorporate fluid dynamics, heat transfer, buoyancy-driven convection, passive scalar advection, chemical reactions and enthalpy changes. All of these effects interact in a physically accurate framework that is simple to code and readily parallelizable. As well as a complete description of the model equations, several example systems will be presented in order to demonstrate the accuracy and versatility of the method. New simulations, which analyzed the effect of a reversible reaction on the transport properties of a convecting fluid, will also be described in detail. This extra chemical degree of freedom was utilized by the system to augment its net heat flux. The numerical method outlined in this paper can be readily deployed for a vast range of complex flow problems, spanning a variety of scientific disciplines.

  9. Ferromagnetic interaction model of activity level in workplace communication

    Science.gov (United States)

    Akitomi, Tomoaki; Ara, Koji; Watanabe, Jun-ichiro; Yano, Kazuo

    2013-03-01

    The nature of human-human interaction, specifically, how people synchronize with each other in multiple-participant conversations, is described by a ferromagnetic interaction model of people’s activity levels. We found two microscopic human interaction characteristics from a real-environment face-to-face conversation. The first characteristic is that people quite regularly synchronize their activity level with that of the other participants in a conversation. The second characteristic is that the degree of synchronization increases as the number of participants increases. Based on these microscopic ferromagnetic characteristics, a “conversation activity level” was modeled according to the Ising model. The results of a simulation of activity level based on this model well reproduce macroscopic experimental measurements of activity level. This model will give a new insight into how people interact with each other in a conversation.

  10. NMR Studies of Protein Hydration and Protein-Ligand Interactions

    Science.gov (United States)

    Chong, Yuan

    Water on the surface of a protein is called hydration water. Hydration water is known to play a crucial role in a variety of biological processes including protein folding, enzymatic activation, and drug binding. Although the significance of hydration water has been recognized, the underlying mechanism remains far from being understood. This dissertation employs a unique in-situ nuclear magnetic resonance (NMR) technique to study the mechanism of protein hydration and the role of hydration in alcohol-protein interactions. Water isotherms in proteins are measured at different temperatures via the in-situ NMR technique. Water is found to interact differently with hydrophilic and hydrophobic groups on the protein. Water adsorption on hydrophilic groups is hardly affected by the temperature, while water adsorption on hydrophobic groups strongly depends on the temperature around 10 C, below which the adsorption is substantially reduced. This effect is induced by the dramatic decrease in the protein flexibility below 10 C. Furthermore, nanosecond to microsecond protein dynamics and the free energy, enthalpy, and entropy of protein hydration are studied as a function of hydration level and temperature. A crossover at 10 C in protein dynamics and thermodynamics is revealed. The effect of water at hydrophilic groups on protein dynamics and thermodynamics shows little temperature dependence, whereas water at hydrophobic groups has stronger effect above 10 C. In addition, I investigate the role of water in alcohol binding to the protein using the in-situ NMR detection. The isotherms of alcohols are first measured on dry proteins, then on proteins with a series of controlled hydration levels. The free energy, enthalpy, and entropy of alcohol binding are also determined. Two distinct types of alcohol binding are identified. On the one hand, alcohols can directly bind to a few specific sites on the protein. This type of binding is independent of temperature and can be

  11. Thermodynamics of the interactions of a homologous series of some amino acids with trimethylamine N-oxide: Volumetric, compressibility, and calorimetric studies

    International Nuclear Information System (INIS)

    Choudhary, Sinjan; Kishore, Nand

    2011-01-01

    Highlights: → Thermodynamics of interaction of amino acids with trimethy N-oxide (TMAO) studied. → Partial molar properties in aqueous osmolyte provide interaction details. → Volumes, compressibilites, enthalpies indicate predominant hydrophobic interactions. → TMAO exerts its effect both by preferential hydration and hydrophobic interactions. → Results suggest hydrophobic interactions lead to destabilization of the protein. - Abstract: The values of apparent molar volume V 2,φ and apparent molar compressibility K S,2,φ of glycine, L-alanine, DL-α-amino-n-butyric acid, L-valine, and L-leucine have been determined in the aqueous solution of 1 mol . kg -1 and 2 mol . kg -1 trimethylamine N-oxide (TMAO) solutions by density and sound velocity measurements. Isothermal titration calorimetry has been employed to determine the values of heats of dilution q of the aqueous solutions of these amino acids in TMAO at temperatures from T = 288.15 K to T = 308.15 K. These data have been used to calculate values of the infinite dilution standard partial molar volume (V 2,m 0 ), standard partial molar isentropic compressibility (K S,2,m 0 ) and limiting enthalpy of dilution (Δ dil H o ) of the amino acids in aqueous TMAO solutions. The standard partial molar volumes of transfer (Δ tr V 2,m 0 ), isentropic compressibility of transfer (Δ tr K S,2,m 0 ), and enthalpy of dilution of transfer (Δ tr Δ dil H o ) of amino acids from water to aqueous TMAO solutions have been calculated from the measured quantities for these thermodynamic quantities. The linear correlation of V 2,m 0 for a homologous series of amino acids has been utilized to calculate the contribution of the charged end groups (NH 3 + , COO - ), CH 2 groups, and the other alkyl chains of the amino acids to V 2,m 0 . The results for the partial molar properties of transfer from water to aqueous TMAO solutions have been interpreted in terms of ion-ion, ion-polar, hydrophilic-hydrophobic, and hydrophobic

  12. Temperature-dependent enthalpy of oxygenation in Antarctic fish hemoglobins

    DEFF Research Database (Denmark)

    Fago, A.; Wells, R.M.G.; Weber, Roy E.

    1997-01-01

    The effect of temperature on the oxygen-binding properties of the hemoglobins of three cold-adapted Antarctic fish species, Dissostichus mawsoni, Pagothenia borchgrevinki and Trematomus, sp., has been investigated under different pH values and buffer conditions. A clear non linear van't Hoff plot...... (logP(50) vs 1/T) of D. mawsoni hemoglobin indicates that the enthalpy of oxygenation (slope of the plot) is temperature dependent and that at high temperatures oxygen-binding becomes less exothermic. Nearly linear relationships were found in the hemoglobins of the other two species. The data were...... oxygen binding. The degree of the temperature dependence of the heat of oxygenation observed in these hemoglobins seems to reflect the differences in their allosteric effects rather than a specific molecular adaptation to low temperatures. Moreover, this study indicates that the disagreement between...

  13. Analysis of Adsorbate-Adsorbate and Adsorbate-Adsorbent Interactions to Decode Isosteric Heats of Gas Adsorption.

    Science.gov (United States)

    Madani, S Hadi; Sedghi, Saeid; Biggs, Mark J; Pendleton, Phillip

    2015-12-21

    A qualitative interpretation is proposed to interpret isosteric heats of adsorption by considering contributions from three general classes of interaction energy: fluid-fluid heat, fluid-solid heat, and fluid-high-energy site (HES) heat. Multiple temperature adsorption isotherms are defined for nitrogen, T=(75, 77, 79) K, argon at T=(85, 87, 89) K, and for water and methanol at T=(278, 288, 298) K on a well-characterized polymer-based, activated carbon. Nitrogen and argon are subjected to isosteric heat analyses; their zero filling isosteric heats of adsorption are consistent with slit-pore, adsorption energy enhancement modelling. Water adsorbs entirely via specific interactions, offering decreasing isosteric heat at low pore filling followed by a constant heat slightly in excess of water condensation enthalpy, demonstrating the effects of micropores. Methanol offers both specific adsorption via the alcohol group and non-specific interactions via its methyl group; the isosteric heat increases at low pore filling, indicating the predominance of non-specific interactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Enthalpy of formation of vanadates of iron, chromium, and aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Kesler, Y.A.; Cheshnitskii, S.M.; Fotiev, A.A.; Tret' yakov, Y.D.

    1985-09-01

    The study of vanadates of iron, aluminum and chromium is of importance for the analysis of the functioning of catalysts of organic synthesis reactions and for the study of vanadium corrosion of structural materials. Of principal interest, however, are the processes in the treatment of vanadium-containing metallurgical slags and waste from thermal power plants, in which these compounds play a major role. At the same time, the thermochemical properties of these substances, which are necessary for creating the physicochemical foundations of industrially important processes, have not been investigated sufficiently. The authors therefore undertake here a study of the compounds FeVO/sub 4/, AIVO/sub 4/, CrVO/sub 4/ and FeCr(VO/sub 4/)/sub 2/, to determine their enthalpies of formation.

  15. Indium-defect interactions in FCC and BCC metals studied using the modified embedded atom method

    Energy Technology Data Exchange (ETDEWEB)

    Zacate, M. O., E-mail: zacatem1@nku.edu [Northern Kentucky University, Department of Physics, Geology, and Engineering Technology (United States)

    2016-12-15

    With the aim of developing a transferable potential set capable of predicting defect formation, defect association, and diffusion properties in a wide range of intermetallic compounds, the present study was undertaken to test parameterization strategies for determining empirical pair-wise interaction parameters in the modified embedded atom method (MEAM) developed by Baskes and coworkers. This report focuses on indium-solute and indium-vacancy interactions in FCC and BCC metals, for which a large set of experimental data obtained from perturbed angular correlation measurements is available for comparison. Simulation results were found to be in good agreement with experimental values after model parameters had been adjusted to reproduce as best as possible the following two sets of quantities: (1) lattice parameters, formation enthalpies, and bulk moduli of hypothetical equiatomic compounds with the NaCl crystal structure determined using density functional theory and (2) dilute solution enthalpies in metals as predicted by Miedema’s semi-empirical model.

  16. Standard enthalpies of formation of some Lanthanide–Cobalt binary alloys by high temperature direct synthesis calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Meschel, S.V., E-mail: meschel@jfi.uchicago.edu [Illinois Institute of Technology, Thermal Processing Technology Center, 10 W. 32nd Street, Chicago, IL (United States); University of Chicago, Gordon Center of Interactive Science, 929 E 57th Street, Chicago, IL 60637 (United States); Nash, P. [Illinois Institute of Technology, Thermal Processing Technology Center, 10 W. 32nd Street, Chicago, IL (United States); Gao, Q.N.; Wang, J.C.; Du, Y. [Central South University, State Key Laboratory of Powder Metallurgy, Changsha, Hunan 410083 (China)

    2013-11-25

    Highlights: •Studied binary Lanthanide–Cobalt intermetallic alloys by high temperature calorimetry. •Determined the enthalpies of formation of 16 magnetostrictive alloys. •Compared the experimental measurements with theoretical predictions by two different models. -- Abstract: The standard enthalpies of formation of intermetallic compounds of some Lanthanide–Cobalt systems have been measured by high temperature direct synthesis calorimetry at 1373 ± 2 K. The following results in kJ/mol of atoms are reported: CeCo{sub 5}(−9.4 ± 3.3); Ce{sub 2}Co{sub 17}(−6.8 ± 3.2); PrCo{sub 5}(−10.5 ± 2.4); Pr{sub 2}Co{sub 17}(−6.8 ± 3.6); NdCo{sub 5}(−12.7 ± 2.6); Nd{sub 2}Co{sub 17}(−6.6 ± 2.7); SmCo{sub 5}(−12.2 ± 1.8); Sm{sub 2}Co{sub 17}(−7.2 ± 2.5); GdCo{sub 5}(−10.0 ± 2.4); Tb{sub 2}Co{sub 17}(−7.7 ± 2.9); Dy{sub 2}Co{sub 17}(−8.1 ± 2.9); HoCo{sub 3}(−17.5 ± 2.2); ErCo{sub 3}(−19.7 ± 3.3); TmCo{sub 3}(−22.9 ± 3.0); LuCo{sub 3}(−23.0 ± 2.6). The measurements are compared with values from the literature and with predicted values of the semi empirical model of Miedema and Coworkers. We also compare the measurements with predicted values by ab initio calculations. We will present a systematic picture of how the enthalpies of formation may be related to the atomic number of the Lanthanide element (LA). We will also compare the thermochemical behavior of the Fe, Co and Ni binary alloys with Lanthanide elements.

  17. Volumetric and Viscometric Studies of Molecular Interactions in ...

    African Journals Online (AJOL)

    NJD

    molar volume, VE, deviation in viscosity, ∆0, excess Gibbs en- ergy of activation ... the Gibbs energy, ∆G*, enthalpy, ∆H*, and entropy, ∆S*, of acti- vation of viscous ... of DMA and BA determined by GLC were found to be >99.5%. The mixtures ...

  18. Vapor pressures and sublimation enthalpies of seven heteroatomic aromatic hydrocarbons measured using the Knudsen effusion technique

    Energy Technology Data Exchange (ETDEWEB)

    Goldfarb, Jillian L., E-mail: JillianLGoldfarb@gmail.co [Division of Engineering, Brown University, Providence, RI 02912 (United States); Suuberg, Eric M., E-mail: Eric_Suuberg@brown.ed [Division of Engineering, Brown University, Providence, RI 02912 (United States)

    2010-06-15

    The vapor pressures of seven heteroatom-containing cyclic aromatic hydrocarbons, ranging in molecular weight from (168.19 to 208.21) g . mol{sup -1} were measured over the temperature range of (301 to 486) K using the isothermal Knudsen effusion technique. The compounds measured include: anthraquinone, 9-fluorenone, 9-fluorenone oxime, phenoxazine, phenoxathiin, and 9H-pyrido[3,4-b]indole. These solid-state sublimation measurements provided values that are compared to vapor pressures of parent aromatic compounds (anthracene and fluorene) and to others with substituent groups in order to examine the effects of alcohol, ketone, pyridine, and pyrrole functionality on this property. The enthalpies and entropies of sublimation for each compound were determined from the Clausius-Clapeyron equation. Though there is no consistent trend in terms of the effects of substitutions on changes in the enthalpy or entropy of sublimation, we note that the prevalence of enthalpic or entropic driving forces on vapor pressure depend on molecule-specific factors and not merely molecular weight of the substituents.

  19. Characterizing interactive engagement activities in a flipped introductory physics class

    Directory of Open Access Journals (Sweden)

    Anna K. Wood

    2016-06-01

    Full Text Available Interactive engagement activities are increasingly common in undergraduate physics teaching. As research efforts move beyond simply showing that interactive engagement pedagogies work towards developing an understanding of how they lead to improved learning outcomes, a detailed analysis of the way in which these activities are used in practice is needed. Our aim in this paper is to present a characterization of the type and duration of interactions, as experienced by students, that took place during two introductory physics courses (1A and 1B at a university in the United Kingdom. Through this work, a simple framework for analyzing lectures—the framework for interactive learning in lectures (FILL, which focuses on student interactions (with the lecturer, with each other, and with the material is proposed. The pedagogical approach is based on Peer Instruction (PI and both courses are taught by the same lecturer. We find lecture activities can be categorized into three types: interactive (25%, vicarious interactive (20% (involving questions to and from the lecturer, and noninteractive (55%. As expected, the majority of both interactive and vicarious interactive activities took place during PI. However, the way that interactive activities were used during non-PI sections of the lecture varied significantly between the two courses. Differences were also found in the average time spent on lecturer-student interactions (28% for 1A and 12% for 1B, although not on student-student interactions (12% and 12% or on individual learning (10% and 7%. These results are explored in detail and the implications for future research are discussed.

  20. Social interaction is associated with changes in infants’ motor activity

    Directory of Open Access Journals (Sweden)

    Céline Scola

    2015-11-01

    Full Text Available Background: In developmental research, infants are commonly assumed to be early stakeholders in interactions with their caregivers. The tools that infants can use to interact with others vary from visual contact to smiling or vocalizing, and also include motor activity. However, surprisingly few studies have explored how the nature and context of social interactions affect infants’ engagement in motor activity. Methods: We investigated the kinematic properties of foot and face movements produced by 11 infants aged between 5 and 9 months during six contrasting dyadic episodes (i.e. passive presence of a stranger or the infant's mother, weak or intense interaction with the stranger/mother as she sings a nursery play song. Results: The infants’ face and foot motor activity was significantly reduced during the interactive episodes, compared with the episodes without any interaction, in both the mother and stranger conditions. Furthermore, the level of their motor activity was significantly lower in the stranger condition than in the mother one for some parameters. Conclusion: These results are in line with those reported by previous studies and confirm the relevance of using motor activity to delineate the early forms of interactive episodes in infants.

  1. Gene × physical activity interactions in obesity

    DEFF Research Database (Denmark)

    Ahmad, Shafqat; Rukh, Gull; Varga, Tibor V

    2013-01-01

    Numerous obesity loci have been identified using genome-wide association studies. A UK study indicated that physical activity may attenuate the cumulative effect of 12 of these loci, but replication studies are lacking. Therefore, we tested whether the aggregate effect of these loci is diminished...... in adults of European ancestry reporting high levels of physical activity. Twelve obesity-susceptibility loci were genotyped or imputed in 111,421 participants. A genetic risk score (GRS) was calculated by summing the BMI-associated alleles of each genetic variant. Physical activity was assessed using self...... combined using meta-analysis weighted by cohort sample size. The meta-analysis yielded a statistically significant GRS × physical activity interaction effect estimate (Pinteraction  = 0.015). However, a statistically significant interaction effect was only apparent in North American cohorts (n = 39...

  2. Isopiestic Determination of the Osmotic and Activity Coefficients of Li2SO4(aq) at T=298.15 and 323.15 K, and Representation with an Extended Ion-Interaction (Pitzer) Model

    Energy Technology Data Exchange (ETDEWEB)

    Rard, Joseph A. [Lawrence Livermore National Laboratory (LLNL); Clegg, Simon L. [University of East Anglia, Norwich, United Kingdom; Palmer, Donald [ORNL

    2007-01-01

    Isopiestic vapor-pressure measurements were made for Li{sub 2}SO{sub 4}(aq) from 0.1069 to 2.8190 mol{center_dot}kg{sup -1} at 298.15 K, and from 0.1148 to 2.7969 mol{center_dot}kg{sup -1} at 323.15 K, with NaCl(aq) as the reference standard. Published thermodynamic data for this system were reviewed, recalculated for consistency, and critically assessed. The present results and the more reliable published results were used to evaluate the parameters of an extended version of Pitzer's ion-interaction model with an ionic-strength dependent third-virial coefficient, as well as those of the standard Pitzer model, for the osmotic and activity coefficients at both temperatures. Published enthalpies of dilution at 298.15 K were also analyzed to yield the parameters of the ion-interaction models for the relative apparent molar enthalpies of dilution. The resulting models at 298.15 K are valid to the saturated solution molality of the thermodynamically stable phase Li{sub 2}SO{sub 4}{center_dot}H{sub 2}O(cr). Solubilities of Li{sub 2}SO{sub 4}{center_dot}H{sub 2}O(cr) at 298.15 K were assessed and the selected value of m(sat.)=3.13{+-}0.04 mol{center_dot}kg{sup -1} was used to evaluate the thermodynamic solubility product K {sub s}(Li{sub 2}SO{sub 4}{center_dot}H{sub 2}O, cr, 298.15 K) = (2.62{+-}0.19) and a CODATA-compatible standard molar Gibbs energy of formation {Delta}{sub f} G m{sup 0}(Li{sub 2}SO{sub 4}{center_dot}H{sub 2}O, cr, 298.15 K) = -(1564.6{+-}0.5) kJ{center_dot}mol{sup -1}.

  3. Experimental and predicted data of excess molar enthalpies and excess molar volumes for the ternary system (1,3-dichlorobenzene + benzene + 1-chlorohexane) at T = 298.15 K

    International Nuclear Information System (INIS)

    Mato, Marta M.; Verdes, Pedro V.; Paz Andrade, M.I.; Legido, José Luis

    2014-01-01

    Graphical abstract: - Highlights: • Experimental enthalpy and densitiy for the mixture 1,3-dichlorobenzene + benzene + 1-chlorohexane were measured. • The excess molar volumes were calculated from the densities of the pure liquids and their mixtures. • The Cibulka equation was used to correlate the ternary contribution of the excess molar properties. • The experimental data were used to test several empirical equations. - Abstract: Experimental excess molar enthalpies, densities and excess molar volumes for the ternary system {x 1 1,3-dichlorobenzene + x 2 benzene + (1 − x 1 − x 2 ) 1-chlorohexane} have been determined at the temperature of 298.15 K and atmospheric pressure. Values of excess molar enthalpies were measured using a Calvet microcalorimeter, and excess molar volumes were determined from the densities of the pure liquids and mixtures, using a vibrating-tube densimeter. The results were fitted by means of different variable degree polynomials. Smooth representations of the results are presented and used to construct constant contours of excess molar enthalpy and excess molar volume on Roozeboom diagrams. Several empirical expressions that have been suggested for use with parameters and predicting excess properties of ternary mixtures from the experimental binary data were tested

  4. The vapor pressure and vaporization enthalpy of R-(+)-menthofuran, a hepatotoxin metabolically derived from the abortifacient terpene, (R)-(+)-pulegone by correlation gas chromatography

    International Nuclear Information System (INIS)

    Gobble, Chase; Chickos, James S.

    2016-01-01

    Highlights: • The vaporization enthalpy and vapor pressure of R-(+) menthofuran is evaluated. • The normal boiling temperature is predicted and compared to experimental and predicted values. • A vapor pressure equation as a function of temperature for menthofuran is evaluated. - Abstract: The vapor pressure as a function of temperature and its vaporization enthalpy at T = 298.15 K of R-(+)-menthofuran, a substance metabolically derived from R-(+)-pulegone that is both a flavoring agent at low concentrations and a hepatotoxin at larger ones, is evaluated by correlation-gas chromatography. A vapor pressure p/Pa = (36 ± 12) has been evaluated at T = 298.15 K, and a normal boiling temperature of T_b/K = 482.4 K is predicted. A boiling temperature of T_b/K = 374.3 compares with the literature value of T_b/K = 371.2 at reduced pressure, p/kPa = 2.93. The vaporization enthalpy of (56.5 ± 3.0) kJ·mol"−"1 compares to an estimated value of (57.8 ± 2.9) kJ·mol"−"1.

  5. Relation between textural and energetic parameters of activated carbon monoliths from coconut shells

    International Nuclear Information System (INIS)

    Vargas, Diana Paola; Giraldo, Liliana; Moreno, Juan C.

    2009-01-01

    Structural characteristics and the energetic parameters of five monoliths of activated carbon were compared. The samples were obtained from coconut shells by means of chemical activation using different concentrations of phosphoric acid. The samples are characterized by means of physical adsorption of N 2 at 77K, CO 2 at 273K, and immersion calorimetry in benzene. From the data obtained the volumes of micropore, mesopore, narrow micro porosity and energy parameters of immersion enthalpy were calculated. Also were calculated, K of the Langmuir model and characteristic energies, Eo, of the Dubinin-Radushkevich model. The experimental results show that the activation with phosphoric acid develops micro porosity, giving a micropore volume between 0,36 and 0,45 cm 3 g-1, area BET between 975 and 1320 m 2 g-1 and immersion enthalpy between 112,9 and 147,7 Jg-1. It was found that for higher BET area, there is a greater immersion enthalpy in benzene, lower characteristic energy and smaller value of K.

  6. Boundary Layer Transition and Trip Effectiveness on an Apollo Capsule in the JAXA High Enthalpy Shock Tunnel (HIEST) Facility

    Science.gov (United States)

    Kirk, Lindsay C.; Lillard, Randolph P.; Olejniczak, Joseph; Tanno, Hideyuki

    2015-01-01

    Computational assessments were performed to size boundary layer trips for a scaled Apollo capsule model in the High Enthalpy Shock Tunnel (HIEST) facility at the JAXA Kakuda Space Center in Japan. For stagnation conditions between 2 MJ/kg and 20 MJ/kg and between 10 MPa and 60 MPa, the appropriate trips were determined to be between 0.2 mm and 1.3 mm high, which provided kappa/delta values on the heatshield from 0.15 to 2.25. The tripped configuration consisted of an insert with a series of diamond shaped trips along the heatshield downstream of the stagnation point. Surface heat flux measurements were obtained on a capsule with a 250 mm diameter, 6.4% scale model, and pressure measurements were taken at axial stations along the nozzle walls. At low enthalpy conditions, the computational predictions agree favorably to the test data along the heatshield centerline. However, agreement becomes less favorable as the enthalpy increases conditions. The measured surface heat flux on the heatshield from the HIEST facility was under-predicted by the computations in these cases. Both smooth and tripped configurations were tested for comparison, and a post-test computational analysis showed that kappa/delta values based on the as-measured stagnation conditions ranged between 0.5 and 1.2. Tripped configurations for both 0.6 mm and 0.8 mm trip heights were able to effectively trip the flow to fully turbulent for a range of freestream conditions.

  7. Excess enthalpies of ternary mixtures of oxygenated additives + hydrocarbon mixtures in fuels and bio-fuels: Dibutyl ether (DBE) and 1-butanol and 1-hexene or cyclohexane or 2,2,4 trimethylpentane at 298.15 K and 313.15 K

    International Nuclear Information System (INIS)

    Aguilar, Fernando; Alaoui, Fatima E.M.; Segovia, José J.; Montero, Eduardo A.

    2013-01-01

    Highlights: ► New excess enthalpy data for ternary mixtures of dibutyl ether + hydrocarbon + 1-butanol are reported. ► Four ternary systems at 298.15 K and 313.15 K were measured by means of an isothermal flow calorimeter. ► 420 Data were fitted to a Redlich–Kister rational equation. ► Intermolecular and association effects involved in these systems have been discussed. - Abstract: New experimental excess molar enthalpy data (420 points) of the ternary systems dibutyl ether (DBE) and 1-butanol and 1-hexene at 298.15 K and 313.15 K, and DBE and 1-butanol and cyclohexane or 2,2,4-trimethylpentane (TMP) at 313.15 K at atmospheric pressure are reported. A quasi-isothermal flow calorimeter has been used to make the measurements. All the ternary systems show endothermic character. The experimental data for the ternary systems have been fitted using the Redlich–Kister rational equation. Considerations with respect the intermolecular interactions amongst ether, alcohol and hydrocarbon compounds are presented.

  8. Interaction in activity location scheduling

    NARCIS (Netherlands)

    Tabak, V.; Vries, de B.; Dijkstra, J.; Jessurun, A.J.

    2006-01-01

    In this paper we discuss the interaction in activity location scheduling which is the main subject of an ongoing research project called "User Simulation of Space Utilization". The aim of this research project is to develop an overall model for the simulation of human movement and utilization of

  9. Enthalpies of combustion and formation of {alpha}-D-glucoheptono-1,4-lactone and {alpha},{beta}-glucooctanoic-1,4-lactone

    Energy Technology Data Exchange (ETDEWEB)

    Amador, Patricia [Facultad de Ciencias Qui' micas, Benemerita Universidad Autonoma de Puebla, 14 Sur y Av. San Claudio, Col. Manuel, C.P. 72570 Puebla Pue (Mexico)], E-mail: cs000721@siu.buap.mx; Mata, Marian Y.; Flores, Henoc [Facultad de Ciencias Qui' micas, Benemerita Universidad Autonoma de Puebla, 14 Sur y Av. San Claudio, Col. Manuel, C.P. 72570 Puebla Pue (Mexico)

    2008-05-15

    The standard molar energies of combustion, {delta}{sub c}U{sub m}{sup 0}(cr,298.15K), of {alpha}-D-glucoheptono-1,4-lactone (GH) and {alpha},{beta}-glucooctanoic-1,4-lactone (GO) were obtained by micro-combustion calorimetry. The obtained values are -(2924.6 {+-} 2.3) kJ . mol{sup -1} and -(3459.5 {+-} 2.5) kJ . mol{sup -1}, respectively. From combustion energies, the standard molar enthalpies of formation in crystalline phase, {delta}{sub f}H{sub m}{sup 0}(cr,298.15K), for GH and GO were determined as -(1546.2 {+-} 2.5) kJ . mol{sup -1} and -(1690.6 {+-} 2.7) kJ . mol{sup -1}, respectively. Also it was found that when the hydroxyl group number increases in the aldonolactones their standard molar enthalpies of formation increase too.

  10. Interactions between whey protein isolate and gum Arabic.

    Science.gov (United States)

    Klein, Miri; Aserin, Abraham; Ben Ishai, Paul; Garti, Nissim

    2010-09-01

    In this study we have attempted to understand the nature of "charge interactions" between two negatively charged biopolymers (whey protein isolate, WPI and gum Arabic, GA) and, consequently, why their mixture exhibits better interfacial activity. Surface tension (gamma(0)) measurements indicated that at ca. 1 wt.% of the biopolymer mixture (3:1 wt. ratio) the air/water surface is saturated. At 5 wt.% the gamma(0) of the mixture is lower than the calculated co-operative value. The zeta-potential measurements revealed that the isoelectric point of the WPI:GA 3:1 wt. ratio mixture is 3.8. The zeta-potential values up to pH 6 are below those calculated. Similarly, the electrical conductivities of the mixture are lower than those calculated. All these measurements indicate: (1) partial charge neutralization in spite of the fact that both biopolymers are negative or (2) partial charge-charge interactions between the two biopolymers. The thermal heating behavior of the frozen water in the aqueous mixture studied by DSC (heating cycle of the frozen sample) clearly indicates that the two biopolymers are interacting. We calculated the enthalpy, the free energy and the chemical potential of the interactions. We found that the interactions of the biopolymers are rather weak. They are likely derived from some local positively charged domains (pH 7) on the protein that neutralize some of the negatively charged GA. These interactions form weak charge adducts. These charge adducts are sufficient to improve its adsorption into the oil-water interface and enhance the emulsion stability. Copyright 2010 Elsevier B.V. All rights reserved.

  11. Analyzing Reaction Rates with the Distortion/Interaction-Activation Strain Model

    NARCIS (Netherlands)

    Bickelhaupt, F. Matthias; Houk, Kendall N.

    2017-01-01

    The activation strain or distortion/interaction model is a tool to analyze activation barriers that determine reaction rates. For bimolecular reactions, the activation energies are the sum of the energies to distort the reactants into geometries they have in transition states plus the interaction

  12. Impact of Flight Enthalpy, Fuel Simulant, and Chemical Reactions on the Mixing Characteristics of Several Injectors at Hypervelocity Flow Conditions

    Science.gov (United States)

    Drozda, Tomasz G.; Baurle, Robert A.; Drummond, J. Philip

    2016-01-01

    The high total temperatures or total enthalpies required to duplicate the high-speed flight conditions in ground experiments often place stringent requirements on the material selection and cooling needs for the test articles and intrusive flow diagnostic equipment. Furthermore, for internal flows, these conditions often complicate the use of nonintrusive diagnostics that need optical access to the test section and interior portions of the flowpath. Because of the technical challenges and increased costs associated with experimentation at high values of total enthalpy, an attempt is often made to reduce it. This is the case for the Enhanced Injection and Mixing Project (EIMP) currently underway in the Arc-Heated Scramjet Test Facility at the NASA Langley Research Center. The EIMP aims to investigate supersonic combustion ramjet (scramjet) fuel injection and mixing physics, improve the understanding of underlying physical processes, and develop enhancement strategies and functional relationships between mixing performance and losses relevant to flight Mach numbers greater than 8. The experiments will consider a "direct-connect" approach and utilize a Mach 6 nozzle to simulate the combustor entrance flow of a scramjet engine. However, while the value of the Mach number is matched to that expected at the combustor entrance in flight, the maximum value of the total enthalpy for these experiments is limited by the thermal-structural limits of the uncooled experimental hardware. Furthermore, the fuel simulant is helium, not hydrogen. The use of "cold" flows and non-reacting mixtures of fuel simulants for mixing experiments is not new and has been extensively utilized as a screening technique for scramjet fuel injectors. In this study, Reynolds-averaged simulations are utilized (RAS) to systematically verify the implicit assumptions used by the EIMP. This is accomplished by first performing RAS of mixing for two injector configurations at planned nominal experimental

  13. Thermodynamic studies on the interaction of folic acid with bovine serum albumin

    International Nuclear Information System (INIS)

    Jha, Niki S.; Kishore, Nand

    2011-01-01

    Research highlights: → Thermodynamics of binding of folic acid with bovine serum albumin studied. → Effect of co-solutes on binding permitted detailed analysis of interactions. → Electrostatic interactions dominate with contribution from hydrogen bonding. → No significant conformational change in protein observed upon drug binding. - Abstract: Binding of the vitamin folic acid with bovine serum albumin (BSA) has been studied using isothermal titration calorimetry (ITC) in combination with fluorescence and circular dichroism spectroscopies. The thermodynamic parameters of binding have been evaluated as a function of temperature, ionic strength, in the presence of nonionic surfactants triton X-100, tetrabutylammonium bromide, and sucrose. The values of the van't Hoff enthalpy calculated from the temperature dependence of the binding constant agree with the calorimetric enthalpies indicating that the binding of folic acid to the BSA is a two state process without involving intermediates. These observations are supported by the intrinsic fluorescence and circular dichroism spectroscopic measurements. With increase in the ionic strength, reduction in the binding affinity of folic acid to BSA is observed suggesting predominance of electrostatic interactions in the binding. The contribution of hydrophobic interactions in the binding is also demonstrated by decrease in the binding affinity in the presence of tetrabutylammonium bromide (TBAB). The value of binding affinity in the presence of sucrose indicates that hydrogen bonding also plays a significant contribution in the complexation process. The calorimetric and spectroscopic results provide quantitative information on the binding of folic acid to BSA and suggest that the binding is dominated by electrostatic interactions with contribution from hydrogen bonding.

  14. Optimization of the exploitation system of a low enthalpy geothermal aquifer with zones of different transmissivities and temperatures

    International Nuclear Information System (INIS)

    Tselepidou, K.; Katsifarakis, K.L.

    2010-01-01

    Market penetration of renewable energy sources, such as geothermal energy, could be promoted even by small cost reductions, achieved through improved development design. This paper deals with optimization of the exploitation system of a low enthalpy geothermal aquifer, by means of the method of genetic algorithms, which has been successfully used in similar problems of groundwater resources management. With respect to water flow, the aquifer consists of two zones of different transmissivities, while from the thermal point of view it may bear any number of zones with different temperatures. The optimization process comprises the annual pumping cost of the required flow and the amortization cost of the pipe network, which carries the hot water from the wells to a central water tank, situated at the border of the geothermal field. Results show that application of the proposed methodology allows better planning of low enthalpy geothermal heating systems, which may be crucial in cases of marginal financial viability. (author)

  15. Cyclin D3 interacts with human activating transcription factor 5 and potentiates its transcription activity

    International Nuclear Information System (INIS)

    Liu Wenjin; Sun Maoyun; Jiang Jianhai; Shen Xiaoyun; Sun Qing; Liu Weicheng; Shen Hailian; Gu Jianxin

    2004-01-01

    The Cyclin D3 protein is a member of the D-type cyclins. Besides serving as cell cycle regulators, D-type cyclins have been reported to be able to interact with several transcription factors and modulate their transcriptional activations. Here we report that human activating transcription factor 5 (hATF5) is a new interacting partner of Cyclin D3. The interaction was confirmed by in vivo coimmunoprecipitation and in vitro binding analysis. Neither interaction between Cyclin D1 and hATF5 nor interaction between Cyclin D2 and hATF5 was observed. Confocal microscopy analysis showed that Cyclin D3 could colocalize with hATF5 in the nuclear region. Cyclin D3 could potentiate hATF5 transcriptional activity independently of its Cdk4 partner. But Cyclin D1 and Cyclin D2 had no effect on hATF5 transcriptional activity. These data provide a new clue to understand the new role of Cyclin D3 as a transcriptional regulator

  16. Improved simplified scheme of atom equivalents to calculate enthalpies of formation of alkyl radicals

    International Nuclear Information System (INIS)

    Castro, Eduardo A.

    2002-01-01

    An improved simplified method of atom equivalents is applied to the calculation of enthalpies of formation of several alkyl radicals. Some statistical mechanics and thermodynamic corrections are added to compare theoretical values with available experimental data. The estimation is quite satisfactory and the average error is similar to current experimental uncertainties, thus providing a direct and simple procedure for this sort of calculation when experimental results are unavailable or/and as an independent check when experimental data are in doubt. (Author) [es

  17. Low-cost low-enthalpy geothermal heat for freshwater production: Innovative applications using thermal desalination processes

    KAUST Repository

    Bundschuh, Jochen; Ghaffour, NorEddine; Mahmoudi, Hacè ne; Goosen, Mattheus F A; Mushtaq, Shahbaz; Hoinkis, Jan

    2015-01-01

    The study is dedicated to exploring different types of low-cost low-enthalpy geothermal and their potential integration with conventional thermal-based water desalination and treatment technologies to deliver energy efficient, environmentally friendly solutions for water desalination and treatment, addressing global water crises. Our in-depth investigation through reviews of various low-enthalpy geothermal and conventional thermal-based technologies suggest that the geothermal option is superior to the solar option if low-cost geothermal heat is available because it provides a constant heat source in contrast to solar. Importantly, the stable heat source further allows up-scaling (> 1000 m3/day), which is not currently possible with solar. Solar-geothermal hybrid constellations may also be suitable in areas where both sources are available. The review also discovers that the innovative Membrane distillation (MD) process is very promising as it can be used for many different water compositions, salinity and temperature ranges. Either the geothermal water itself can be desalinated/treated or the geothermal heat can be used to heat feed water from other sources using heat exchangers. However, there are only few economic analyses for large-scale MD units and these are based on theoretical models using often uncertain assumptions resulting in a large variety of results.

  18. Low-cost low-enthalpy geothermal heat for freshwater production: Innovative applications using thermal desalination processes

    KAUST Repository

    Bundschuh, Jochen

    2015-03-01

    The study is dedicated to exploring different types of low-cost low-enthalpy geothermal and their potential integration with conventional thermal-based water desalination and treatment technologies to deliver energy efficient, environmentally friendly solutions for water desalination and treatment, addressing global water crises. Our in-depth investigation through reviews of various low-enthalpy geothermal and conventional thermal-based technologies suggest that the geothermal option is superior to the solar option if low-cost geothermal heat is available because it provides a constant heat source in contrast to solar. Importantly, the stable heat source further allows up-scaling (> 1000 m3/day), which is not currently possible with solar. Solar-geothermal hybrid constellations may also be suitable in areas where both sources are available. The review also discovers that the innovative Membrane distillation (MD) process is very promising as it can be used for many different water compositions, salinity and temperature ranges. Either the geothermal water itself can be desalinated/treated or the geothermal heat can be used to heat feed water from other sources using heat exchangers. However, there are only few economic analyses for large-scale MD units and these are based on theoretical models using often uncertain assumptions resulting in a large variety of results.

  19. Spectroscopic and thermodynamic studies on ferulic acid - Alpha-2-macroglobulin interaction

    Science.gov (United States)

    Rehman, Ahmed Abdur; Sarwar, Tarique; Arif, Hussain; Ali, Syed Saqib; Ahsan, Haseeb; Tabish, Mohammad; Khan, Fahim Halim

    2017-09-01

    Ferulic acid is a major phenolic acid found in numerous plant species in conjugated form. It binds to enzymes and oligomeric proteins and modifies their structure and function. This study was designed to examine the interaction of ferulic acid, an active ingredient of some important medicines, with α2M, a key serum proteinase, under physiological conditions. The mechanism of interaction was studied by spectroscopic techniques such as, UV-visible absorption, fluorescence spectroscopy, circular dichroism along with isothermal titration calorimetry. Fluorescence quenching of α2M by ferulic acid demonstrated the formation of α2M-ferulic acid complex by static quenching mechanism. Binding parameters calculated by Stern-Volmer method showed that ferulic acid binds to α2M with moderate affinity of the order of ∼104 M-1. The thermodynamic signatures reveal that binding was enthalpy driven and hydrogen bonding played a major role in ferulic acid-α2M binding. CD spectra analysis suggests very little conformational changes in α2M on ferulic acid binding.

  20. Influence of lipophilicity on drug-cyclodextrin interactions: A calorimetric study

    International Nuclear Information System (INIS)

    Waters, Laura J.; Bedford, Susan; Parkes, Gareth M.B.; Mitchell, J.C.

    2010-01-01

    This study presents a systematic investigation of the interaction of three functionally related drugs, ibuprofen, ketoprofen and flurbiprofen, with two distinct forms of cyclodextrin at three specific temperatures, 298, 303 and 310 K using isothermal titration calorimetry (ITC). Although all three pharmaceutical compounds have similar pKa values, they exhibit widely differing lipophilicities. While previous authors have presented data regarding the binding of flurbiprofen and ibuprofen with β-cyclodextrin, this is the first report of the interaction of all three drug substances with β-cyclodextrin and 2-(hydroxypropyl)-β-cyclodextrin at controlled pH and temperature. For all scenarios, the associated changes in Gibbs free energy, enthalpy and entropy are presented alongside the stoichiometry and binding constants concerned. In all cases the binding was found to occur at a 1:1 ratio with an associated negative enthalpy and Gibbs free energy with the formation of the complex enthalpically, rather than entropically driven. The data further demonstrates a clear relationship between the thermodynamic behaviour and log P of the drug molecules. This work confirms the suitability of ITC to determine thermodynamic data for drug-cyclodextrin complex formations and provides an insight into the selection of appropriate cyclodextrins for bespoke pharmaceutical formulations.

  1. Influence of lipophilicity on drug-cyclodextrin interactions: A calorimetric study

    Energy Technology Data Exchange (ETDEWEB)

    Waters, Laura J., E-mail: l.waters@hud.ac.uk [School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield, HD1 3DH (United Kingdom); Bedford, Susan; Parkes, Gareth M.B. [School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield, HD1 3DH (United Kingdom); Mitchell, J.C. [Medway Sciences, School of Science, University of Greenwich at Medway, Chatham Maritime, Kent ME4 4TB (United Kingdom)

    2010-11-20

    This study presents a systematic investigation of the interaction of three functionally related drugs, ibuprofen, ketoprofen and flurbiprofen, with two distinct forms of cyclodextrin at three specific temperatures, 298, 303 and 310 K using isothermal titration calorimetry (ITC). Although all three pharmaceutical compounds have similar pKa values, they exhibit widely differing lipophilicities. While previous authors have presented data regarding the binding of flurbiprofen and ibuprofen with {beta}-cyclodextrin, this is the first report of the interaction of all three drug substances with {beta}-cyclodextrin and 2-(hydroxypropyl)-{beta}-cyclodextrin at controlled pH and temperature. For all scenarios, the associated changes in Gibbs free energy, enthalpy and entropy are presented alongside the stoichiometry and binding constants concerned. In all cases the binding was found to occur at a 1:1 ratio with an associated negative enthalpy and Gibbs free energy with the formation of the complex enthalpically, rather than entropically driven. The data further demonstrates a clear relationship between the thermodynamic behaviour and log P of the drug molecules. This work confirms the suitability of ITC to determine thermodynamic data for drug-cyclodextrin complex formations and provides an insight into the selection of appropriate cyclodextrins for bespoke pharmaceutical formulations.

  2. Energy and enthalpy distribution functions for a few physical systems.

    Science.gov (United States)

    Wu, K L; Wei, J H; Lai, S K; Okabe, Y

    2007-08-02

    The present work is devoted to extracting the energy or enthalpy distribution function of a physical system from the moments of the distribution using the maximum entropy method. This distribution theory has the salient traits that it utilizes only the experimental thermodynamic data. The calculated distribution functions provide invaluable insight into the state or phase behavior of the physical systems under study. As concrete evidence, we demonstrate the elegance of the distribution theory by studying first a test case of a two-dimensional six-state Potts model for which simulation results are available for comparison, then the biphasic behavior of the binary alloy Na-K whose excess heat capacity, experimentally observed to fall in a narrow temperature range, has yet to be clarified theoretically, and finally, the thermally induced state behavior of a collection of 16 proteins.

  3. Water as a solute in aprotic dipolar solvents. 2. D2O-H2O solute isotope effects on the enthalpy of water dissolution in nitromethane, acetonitrile and propylene carbonate at 298.15 K

    International Nuclear Information System (INIS)

    Ivanov, Evgeniy V.; Smirnov, Valeriy I.

    2010-01-01

    The enthalpies of solution of ordinary (H 2 O) and heavy (D 2 O) water in nitromethane (NM), acetonitrile (ACN) and propylene carbonate (PC) were measured calorimetrically at 298.15 K. Standard (at the infinite dilution) enthalpies of solution and solvation, along with D 2 O-H 2 O solute isotope effects on the quantities in question, were calculated. The enthalpies of solution of water H/D isotopologues were found to be positive by sign and substantially increasing in magnitude on going from ACN and PC to NM, whereas the corresponding positive solute H/D isotope effect changes in a consequence: NM > ACN > PC. The qualitative interrelations between the enthalpy-isotopic effect of dissolution (solvation) of water and the electron-accepting/donating ability of aprotic dipolar solvent (within a series considered) were found.

  4. Calorimetric comparison of the interactions between salivary proteins and Streptococcus mutans with and without antigen I/II

    NARCIS (Netherlands)

    Xu, C.P.; Belt-Gritter, van de B.; Busscher, H.J.; Mei, van der H.C.; Norde, W.

    2007-01-01

    Antigen I/II can be found on streptococcal cell surfaces and is involved in their interaction with salivary proteins. In this paper, we determine the adsorption enthalpies of salivary proteins to Streptococcus mutans LT11 and S. mutans IB03987 with and without antigen I/II, respectively, using

  5. Calorimetric comparison of the interactions between salivary proteins and Streptococcus mutans with and without antigen I/II

    NARCIS (Netherlands)

    Xu, Chun-Ping; Belt-Gritter, van de Betsy; Busscher, Henk J.; van der Mei, Henny C.; Norde, Willem

    2007-01-01

    Antigen I/II can be found on streptococcal cell surfaces and is involved in their interaction with salivary proteins. In this paper, we determine the adsorption enthalpies of salivary proteins to Streptococcus mutans LT 11 and S. mutans IB03987 with and without antigen I/II, respectively, using

  6. New insights into the mechanism of interaction between CO2 and polymers from thermodynamic parameters obtained by in situ ATR-FTIR spectroscopy.

    Science.gov (United States)

    Gabrienko, Anton A; Ewing, Andrew V; Chibiryaev, Andrey M; Agafontsev, Alexander M; Dubkov, Konstantin A; Kazarian, Sergei G

    2016-03-07

    This work reports new physical insights of the thermodynamic parameters and mechanisms of possible interactions occurring in polymers subjected to high-pressure CO2. ATR-FTIR spectroscopy has been used in situ to determine the thermodynamic parameters of the intermolecular interactions between CO2 and different functional groups of the polymers capable of specific interactions with sorbed CO2 molecules. Based on the measured ATR-FTIR spectra of the polymer samples subjected to high-pressure CO2 (30 bar) at different temperatures (300-340 K), it was possible to characterize polymer-polymer and CO2-polymer interactions. Particularly, the enthalpy and entropy of the formation of the specific non-covalent complexes between CO2 and the hydroxy (-OH), carbonyl (C[double bond, length as m-dash]O) and hydroxyimino ([double bond, length as m-dash]N-OH) functional groups of the polymer samples have been measured. Furthermore, the obtained spectroscopic results have provided an opportunity for the structure of these complexes to be proposed. An interesting phenomenon regarding the behavior of CO2/polymer systems has also been observed. It has been found that only for the polyketone, the value of enthalpy was negative indicating an exothermic process during the formation of the CO2-polymer non-covalent complexes. Conversely, for the polyoxime and polyalcohol samples there is a positive enthalpy determined. This is a result of the initial polymer-polymer interactions requiring more energy to break than is released during the formation of the CO2-polymer complex. The effect of increasing temperature to facilitate the breaking of the polymer-polymer interactions has also been observed. Hence, a mechanism for the formation of CO2-polymer complexes was suggested based on these results, which occurs via a two-step process: (1) the breaking of the existing polymer-polymer interactions followed by (2) the formation of new CO2-polymer non-covalent interactions.

  7. Determining the Enthalpy of Vaporization of Salt Solutions Using the Cooling Effect of a Bubble Column Evaporator

    Science.gov (United States)

    Fan, Chao; Pashley, Richard M.

    2016-01-01

    The enthalpy of vaporization (?H[subscript vap]) of salt solutions is not easily measured, as a certain quantity of pure water has to be evaporated from a solution, at constant composition, and at a fixed temperature and pressure; then the corresponding heat input has to be measured. However, a simple bubble column evaporator (BCE) was used as a…

  8. Simulation of hypersonic shock wave - laminar boundary layer interactions

    Science.gov (United States)

    Kianvashrad, N.; Knight, D.

    2017-06-01

    The capability of the Navier-Stokes equations with a perfect gas model for simulation of hypersonic shock wave - laminar boundary layer interactions is assessed. The configuration is a hollow cylinder flare. The experimental data were obtained by Calspan-University of Buffalo (CUBRC) for total enthalpies ranging from 5.07 to 21.85 MJ/kg. Comparison of the computed and experimental surface pressure and heat transfer is performed and the computed §ow¦eld structure is analyzed.

  9. A method for the estimation of the enthalpy of formation of mixed oxides in Al2O3-Ln2O3 systems

    International Nuclear Information System (INIS)

    Vonka, P.; Leitner, J.

    2009-01-01

    A new method is proposed for the estimation of the enthalpy of formation (Δ ox H) of various Al 2 O 3 -Ln 2 O 3 mixed oxides from the constituent binary oxides. Our method is based on Pauling's concept of electronegativity and, in particular, on the relation between the enthalpy of formation of a binary oxide and the difference between the electronegativities of the oxide-forming element and oxygen. This relation is extended to mixed oxides with a simple formula given for the calculation of Δ ox H. The parameters of this equation were fitted using published experimental values of Δ ox H derived from high-temperature oxide melt solution calorimetry. Using our proposed method, we obtained a standard deviation (σ) of 4.87 kJ mol -1 for this data set. Taking into account regularities within the lanthanide series, we then estimated the Δ ox H values for Al 2 O 3 -Ln 2 O 3 mixed oxides. The values estimated using our method were compared with those obtained by Aronson's and Zhuang's empirical methods, both of which give significantly poorer results. - Graphical abstract: Enthalpy of formation of Ln-Al-O oxides from the constituent binary ones.

  10. Playful Interactions Stimulating Physical Activity in Public Spaces

    DEFF Research Database (Denmark)

    Sturm, Janienke; Bekker, Tilde; Vanden Abeele, Vero

    In this position paper we describe our vision on designing playful interactions to persuade people to be physically active in public spaces. Social embeddedness and playful interaction are the core elements of this vision. We illustrate how our design vision is incorporated into innovative concepts...... to motivate each other to be physically active by creating challenges for each other. Designing playful solutions for public spaces asks for low-threshold solutions that support easy stepping in and stepping out solutions....

  11. Measurements of mass-fraction activity coefficient at infinite dilution of aliphatic and aromatic hydrocarbons, thiophene, alcohols, water, ethers, and ketones in hyperbranched polymer, Boltorn H2004, using inverse gas chromatography

    International Nuclear Information System (INIS)

    Domanska, Urszula; Zolek-Tryznowska, Zuzanna

    2010-01-01

    Thermodynamic properties of the hyperbranched polymer, Boltorn H2004 (B-H2004), were investigated by inverse gas chromatography with 42 different solvents: n-alkanes (C 5 -C 10 ), cycloalkanes (C 5 -C 8 ), alkenes (C 5 -C 8 ), alkynes (C 5 -C 8 ), aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-, m-, p-xylene, thiophene), alcohols (C 1 -C 5 ), water, ethers (tetrahydrofuran (THF), methyl-tert-butylether (MTBE), diethyl-, di-n-propyl-, di-n-butyl ether), and ketones (acetone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyclopentanone) at the temperatures from (308.15 to 348.15) K using the inverse gas chromatography (IGC). The density and thermophysical properties of polymer were described. The specific retention volume (V g ), the mass-fraction activity coefficient at infinite dilution (Ω 13 ∞ ), the Flory-Huggins interaction parameter (χ 13 ∞ ), the molar enthalpy of sorption in the polymer (Δ s H), the partial molar excess enthalpy at infinite dilution (ΔH 1 E,∞ ), the molar enthalpy of vaporization to the ideal-gas state for the pure solutes (Δ vap H 0 ), the partial molar Gibbs excess energy at infinite dilution (ΔG 1 E,∞ ), and the solubility parameter of the polymer (δ 3 ), were calculated. The UNIFAC-FV model was used to predict the mass-fraction activity coefficient at infinite dilution for different solutes in the B-H2004 polymer.

  12. Aggregation behavior and intermicellar interactions of cationic Gemini surfactants: Effects of alkyl chain, spacer lengths and temperature

    International Nuclear Information System (INIS)

    Hajy Alimohammadi, Marjan; Javadian, Soheila; Gharibi, Hussein; Tehrani-Bagha, Ali reza; Alavijeh, Mohammad Rashidi; Kakaei, Karim

    2012-01-01

    Graphical abstract: Highlights: → Enthalpy-entropy compensation relation was found between and for gemini surfactants. → The intermicellar interaction parameters are influenced with increasing the lengths of the tail and the spacer of gemini surfactants. → Increasing temperature decreases the intermicellar interaction parameters. → The changes in micellar surface charge density, and phase transition between spherical and rod geometries explain the data. - Abstract: The aggregation behavior of the cationic Gemini surfactants C m H 2m+1 N(CH 3 ) 2 (CH 2 ) S (CH 3 ) 2 N C m H 2m+1 ,2Br - with m = 12, 14 and s = 2, 4 were studied by performing surface tension, electrical conductivity, pulsed field gradient nuclear magnetic resonance (PFG-NMR), and cyclic voltammetry (CV) measurements over the temperature range 298 K to 323 K. The critical micelle concentration (CMC), surface excess (Γ max ), mean molecular surface area (A min ), degree of counter ion dissociation (α), and the thermodynamic parameters of micellization were determined from the surface tension and conductance data. An enthalpy-entropy compensation effect was observed and all the plots of enthalpy-entropy compensation exhibit excellent linearity. The micellar self-diffusion coefficients (D m ) and intermicellar interaction parameters (k d ) were obtained from the PFG-NMR and CV measurements. These results are discussed in terms of the intermicellar interactions, the effects of the chain and spacer lengths on the micellar surface charge density, and the phase transition between spherical and rod geometries. The intermicellar interaction parameters were found to decrease slightly with increasing temperature for 14-4-14, which suggests that the micellar surface charge density decreases with increasing temperature. The mean values of the hydrodynamic radius, R h , and the aggregation number, N agg , of the Gemini surfactants'm-4-m micelles were calculated from the micellar self-diffusion coefficient

  13. Entropy–enthalpy compensation as a fundamental concept and analysis tool for systematical experimental data

    KAUST Repository

    Starikov, E.B.; Nordé n, B.

    2012-01-01

    Enthalpy-entropy compensation (EEC) has a definite physical sense. Here, we review EEC from a new standpoint, using the notion of correlation. The latter has two basic meanings: (a) 'A' is correlated to 'B' means 'A' results from 'B' or vice versa; (b) this same means there is some real, but hidden 'C' in connection to both 'A' and 'B'). In accordance with the interpretation (b), we try rationalizing EEC in terms of hidden, but physically real factors. © 2012 Elsevier B.V. All rights reserved.

  14. Entropy–enthalpy compensation as a fundamental concept and analysis tool for systematical experimental data

    KAUST Repository

    Starikov, E.B.

    2012-06-01

    Enthalpy-entropy compensation (EEC) has a definite physical sense. Here, we review EEC from a new standpoint, using the notion of correlation. The latter has two basic meanings: (a) \\'A\\' is correlated to \\'B\\' means \\'A\\' results from \\'B\\' or vice versa; (b) this same means there is some real, but hidden \\'C\\' in connection to both \\'A\\' and \\'B\\'). In accordance with the interpretation (b), we try rationalizing EEC in terms of hidden, but physically real factors. © 2012 Elsevier B.V. All rights reserved.

  15. Measurement of the enthalpy and specific heat of a Be2C-graphite-UC2 reactor fuel material to 19800K

    International Nuclear Information System (INIS)

    Roth, E.P.

    1980-01-01

    The enthalpy and specific heat of a Be 2 C-graphite-UC 2 composite nuclear fuel material were measured over the temperature range 300 to 1980 0 K using differential scanning calorimetry and liquid argon vaporization calorimetry. The fuel material measured was developed at Sandia National Laboratories for use in pulsed test reactors. The material is a hot-pressed composite consisting of 40 vol % Be 2 C, 49.5 vol % graphite, 3.5 vol % UC 2 and 7.0 vol % void. The specific heat was measured with the differential scanning calorimeter over the temperature range 300 to 950 0 K while the enthalpy was measured over the range 1185 to 1980 0 K with the liquid argon vaporization calorimeter. The normal spectral emittance at a wavelength of 6.5 x 10 -5 cm was measured over the experimental temperature range. The combined experimental enthalpy data were fit using a spline routine and differentiated to give the specific heat. Comparison of the measured specific heat of the composite to the specific heat calculated by summing the contributions of the individual components indicates that the specific heat of the Be 2 C component differs significantly from literature values and is approximately 0.6 cal/g-K (2.5 x 10 3 J/Kg-K) for temperatures above 1000 0 K

  16. Entropy-enthalpy compensation may be a useful interpretation tool for complex systems like protein-DNA complexes: An appeal to experimentalists

    KAUST Repository

    Starikov, E. B.; Nordén, B.

    2012-01-01

    In various chemical systems, enthalpy-entropy compensation (EEC) is a well-known rule of behavior, although the physical roots of it are still not completely understood. It has been frequently questioned whether EEC is a truly physical phenomenon

  17. Host-Guest Interaction between Corona[n]arene and Bisquaternary Ammonium Derivatives for Fabricating Supra-Amphiphile.

    Science.gov (United States)

    Zeng, Lingda; Guo, Qing-Hui; Feng, Yuanning; Xu, Jiang-Fei; Wei, Yuhan; Li, Zhibo; Wang, Mei-Xiang; Zhang, Xi

    2017-06-13

    The interactions between a host, water-soluble corona[n]arene (S6-CAP), and a series of guests, bisquaternary ammonium derivatives (CnDAs), in water, were investigated. The host and guest can form 1:1 host-guest complex. Their binding constants decrease as the alkyl length of CnDAs increases, which can be tunable ranging from 10 3 to 10 6 M -1 . The binding processes are mainly entropy-driven, while the enthalpy changes also play an important role in enhancing the host-guest interactions. In addition, a supra-amphiphile was fabricated with S6-CAP and a normal surfactant bearing bisquaternary ammonium (C4R). The S6-CAP·C4R complex forms micellar aggregates in water, and the system possesses better assembling activity and dilution stability than its building block C4R. This study enriches the families of supra-amphiphiles with a new architecture, and employing such a supra-amphiphile in biofunctional materials is highly anticipated.

  18. Prediction of enthalpy and entropy of solute segregation at individua grain boundaries of α-iron and ferrite steels

    Czech Academy of Sciences Publication Activity Database

    Lejček, Pavel; Hofmann, S.; Janovec, J.

    2007-01-01

    Roč. 462, - (2007), s. 76-85 ISSN 0921-5093 R&D Projects: GA ČR(CZ) GA106/05/0134 Institutional research plan: CEZ:AV0Z10100520 Keywords : segregation * grain boundaries * enthalpy/entropy relationship * α-iron * prediction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.457, year: 2007

  19. Measuring Enthalpy of Sublimation of Volatiles by Means of Piezoelectric Crystal Microbalances

    Science.gov (United States)

    Dirri, Fabrizio; Palomba, Ernesto; Longobardo, Andrea; Zampetti, Emiliano

    2017-12-01

    Piezoelectric Crystal Microbalances (PCM's) are widely used to study the chemical processes involving volatile compounds in any environment, such as condensation process. Since PCM's are miniaturized sensor, they are very suitable for planetary in situ missions, where can be used to detect and to measure the mass amount of astrobiologically significant compounds, such as water and organics. This work focuses on the realization and testing of a new experimental setup, able to characterize volatiles which can be found in a planetary environment. In particular the enthalpy of sublimation of some dicarboxylic acids has been measured. The importance of dicarboxylic acids in planetology and astrobiology is due to the fact that they have been detected in carbonaceous chondritic material (e.g. Murchinson), among the most pristine material present in our Solar System. In this work, a sample of acid was heated in an effusion cell up to its sublimation. For a set of temperatures (from 30 °C to 75 °C), the deposition rate on the PCM surface has been measured. From these measurements, it has been possible to infer the enthalpy of sublimation of Adipic acid, i.e. ΔH = 141.6 ± 0.8 kJ/mol and Succinic acid, i.e. ΔH = 113.3 ± 1.3 kJ/mol. This technique has so demonstrated to be a good choice to recognise a single compound or a mixture (with an analysis upstream) even if some improvements concerning the thermal stabilization of the system will be implemented in order to enhance the results' accuracy. The experiment has been performed in support of the VISTA (Volatile In Situ Thermogravimetry Analyzer) project, which is included in the scientific payload of the ESA MarcoPolo-R mission study.

  20. Enthalpic pair wise self-interactions of four deoxynucleosides (dU, dC, dG, dT) in (dimethylsulfoxide + water) mixtures at T = 298.15 K

    International Nuclear Information System (INIS)

    Jia, Zhao-Peng; Chen, Nan; Wang, Hua-Qin; Zhu, Li-Yuan; Hu, Xin-Gen

    2014-01-01

    Graphical abstract: Enthalpic pairwise self-interaction coefficients (h xx ) of the four 2′-deoxynucleosides are of uneven increasing magnitudes (■, 2′-deoxyuridine; ▪, 2′-deoxycytidine; ▪, 2′-deoxyguanosine; ▪, 2′-deoxythymidine). - Highlights: • Dilution enthalpies of 2′-deoxynucleosides in (DMSO + water) mixtures were determined. • Enthalpic coefficients (h xx ) were calculated based on McMillan–Mayer’ theory. • The values of h xx are large negative cross the studied range of mixed solvents. • Hydrophilic interactions are proved to be prevailing in the ternary solutions. • The trends of h xx depend on the (hydrophobic / hydrophilic) equilibrium of solutes. - Abstract: The dilution enthalpies of four 2′-deoxynucleosides, namely 2′-deoxyuridine (dU), 2′-deoxycytidine (dC), 2′-deoxyguanosine (dG) and 2′-deoxythymidine (dT), in (dimethylsulfoxide (DMSO) + water) mixtures of various mass fractions (w DMSO = 0 to 0.30) have been determined at T = 298.15 K, respectively, using an isothermal titration calorimeter (ITC200 MicroCal). On the basis of McMillan–Mayer’ theory, enthalpic pair wise self-interaction coefficients (h xx ) of each compound at different values of w DMSO have been evaluated from successive dilution enthalpies. It was found that the values of h xx are all large negative and increase gradually with w DMSO across the whole composition range of the mixed solvent studied, though the degree of variation among them is somewhat different. The results indicate that (hydrophilic + hydrophilic) interactions are prevailing over (hydrophobic + hydrophobic) and (hydrophobic + hydrophilic) interactions in the ternary aqueous solutions under study

  1. Investigations to explore interactions in (polyhydroxy solute + L-ascorbic acid + H2O) solutions at different temperatures: Calorimetric and viscometric approach

    International Nuclear Information System (INIS)

    Banipal, Parampaul K.; Sharma, Mousmee; Aggarwal, Neha; Banipal, Tarlok S.

    2016-01-01

    Highlights: • The hydrophilic-hydrophilic interactions predominate at low temperatures. • Enthalpy change for polyol is less exothermic than its parent saccharide. • Δ dil C o p,2,m values suggest structural increase in presence of L-ascorbic acid. • Solutes act as kosmotropes in L-ascorbic acid (aq) solutions as indicated by dB/dT. - Abstract: Isothermal titration micro-calorimeter has been used to measure the enthalpy change (q) of polyhydroxy solutes [(+)-D-xylose, xylitol, (+)-D-glucose, 2-deoxy-D-glucose, (+)-methyl-α-D-glucopyranoside, and (+)-maltose monohydrate] in water and in (0.05, 0.15, and 0.25) mol·kg −1 L-ascorbic acid (aq) solutions at (288.15, 298.15, 308.15, and 318.15) K. Limiting enthalpies of dilution (Δ dil H°) of these solutes were calculated from heat evolved/absorbed during calorimetric experiments. Further thermodynamic quantities such as limiting enthalpies of dilution of transfer (Δ tr Δ dil H°), change in heat capacity (Δ dil C o p,2,m ), and pair (h AB ) and triplet (h ABB ) enthalpic interaction coefficients were also calculated and used to explore the nature of interactions of solutes with cosolute (L-ascorbic acid). The Jones-Dole viscosity B-coefficients for (+)-D-xylose, xylitol, (+)-D-galactose, galactitol, (+)-D-glucose, 2-deoxy-D-glucose, (+)-methyl-α-D-glucopyranoside, and (+)-maltose monohydrate in water and in (0.05, 0.15, 0.25, and 0.35) mol·kg −1 L-ascorbic acid (aq) solutions have been determined from viscosity (η) data measured over temperature range (288.15–318.15) K and at pressure, P = 101.3 kPa. The temperature dependence of B-coefficients (dB/dT), and viscosity B-coefficients of transfer (Δ tr B) of solutes from water to cosolute have also been estimated. These parameters have been discussed in terms of structure-making (kosmotropic) or -breaking (chaotropic) behavior of solutes.

  2. Hospital's activity-based financing system and manager-physician [corrected] interaction.

    Science.gov (United States)

    Crainich, David; Leleu, Hervé; Mauleon, Ana

    2011-10-01

    This paper examines the consequences of the introduction of an activity-based reimbursement system on the behavior of physicians and hospital's managers. We consider a private for-profit sector where both hospitals and physicians are initially paid on a fee-for-service basis. We show that the benefit of the introduction of an activity-based system depends on the type of interaction between managers and physicians (simultaneous or sequential decision-making games). It is shown that, under the activity-based system, a sequential interaction with physician leader could be beneficial for both agents in the private sector. We further model an endogenous timing game à la Hamilton and Slutsky (Games Econ Behav 2: 29-46, 1990) in which the type of interaction is determined endogenously. We show that, under the activity-based system, the sequential interaction with physician leader is the unique subgame perfect equilibrium.

  3. The hydroxyflavone, fisetin, suppresses mast cell activation induced by interaction with activated T cell membranes

    Science.gov (United States)

    Nagai, K; Takahashi, Y; Mikami, I; Fukusima, T; Oike, H; Kobori, M

    2009-01-01

    Background and purpose: Cell-to-cell interactions between mast cells and activated T cells are increasingly recognized as a possible mechanism in the aetiology of allergic or non-allergic inflammatory disorders. To determine the anti-allergic effect of fisetin, we examined the ability of fisetin to suppress activation of the human mast cell line, HMC-1, induced by activated Jurkat T cell membranes. Experimental approach: HMC-1 cells were incubated with or without fisetin for 15 min and then co-cultured with Jurkat T cell membranes activated by phorbol-12-myristate 13-acetate for 16 h. We determined gene expression in activated HMC-1 cells by DNA microarray and quantitative reverse transcription (RT)-PCR analysis. We also examined activation of the transcription factor NF-κB and MAP kinases (MAPKs) in activated HMC-1 cells. Key results: Fisetin suppresses cell spreading and gene expression in HMC-1 cells stimulated by activated T cell membranes. Additionally, we show that these stimulated HMC-1 cells expressed granzyme B. The stimulatory interaction also induced activation of NF-κB and MAPKs; these activations were suppressed by fisetin. Fisetin also reduced the amount of cell surface antigen CD40 and intercellular adhesion molecule-1 (ICAM-1) on activated HMC-1 cells. Conclusions and implications: Fisetin suppressed activation of HMC-1 cells by activated T cell membranes by interfering with cell-to-cell interaction and inhibiting the activity of NF-κB and MAPKs and thereby suppressing gene expression. Fisetin may protect against the progression of inflammatory diseases by limiting interactions between mast cells and activated T cells. PMID:19702784

  4. Experimental study on an innovative enthalpy recovery technology based on indirect flash evaporative cooling

    DEFF Research Database (Denmark)

    Nie, Jinzhe; Yuan, Shu; Fang, Lei

    2018-01-01

    recovery unit. The principle of the technology is to over saturate indoor exhaust air by ultrasonic atomizing humidification. The evaporation of ultrafine mists cools down indoor exhaust air to its wet-bulb temperature and makes not only sensible heat transfer but also moisture condensed in outdoor supply...... were measured to investigate and analyze its energy recover efficiencies. The results showed that in hot and humid climate, up to 71% of total heat recover efficiency could be achieved by the prototype unit, and more than 50% of the enthalpy recovered was contributed by moisture condensation...

  5. Low-tmperature Heat Capacities and Standard Molar Enthalpy of Formation of 4-Nitrobenzyl Alcohol

    Institute of Scientific and Technical Information of China (English)

    MENG, Qingfen; TAN, Zhicheng; WANG, Xiaohuan; DONG, Yaping; LI, Wu; SHI, Quan

    2009-01-01

    Low-temperature heat capacities of 4-nitrobenzyl alcohol (4-NBA) have been measured by a high precision automated adiabatic calorimeter over the temperature range from 78 to 396 K. The melting temperature, the molar calculated in the range from 80 to 400 K at the interval of 5 K. The constant-volume energy and standard molar en- at T=298.15 K. The standard molar enthalpy of formation has been derived, ΔfHom(C7H7NO3, s)=-(206.49± namic quantities through a Hess thermochemical cycle.

  6. Playing Goffman's Information Game: A Classroom Activity Involving Student Interactions

    Science.gov (United States)

    McCoy, Charles Allan

    2017-01-01

    Goffman's dramaturgical approach is frequently used to introduce undergraduate students to the sociological understanding of human interaction. While a number of scholars have designed engaging student activities that highlight Goffman's approach, most of these activities tend to involve atypical embarrassing interactions or norm-breaking…

  7. Characterizing Interactive Engagement Activities in a Flipped Introductory Physics Class

    Science.gov (United States)

    Wood, Anna K.; Galloway, Ross K.; Donnelly, Robyn; Hardy, Judy

    2016-01-01

    Interactive engagement activities are increasingly common in undergraduate physics teaching. As research efforts move beyond simply showing that interactive engagement pedagogies work towards developing an understanding of "how" they lead to improved learning outcomes, a detailed analysis of the way in which these activities are used in…

  8. Pore size distribution and supercritical hydrogen adsorption in activated carbon fibers

    Science.gov (United States)

    Purewal, J. J.; Kabbour, H.; Vajo, J. J.; Ahn, C. C.; Fultz, B.

    2009-05-01

    Pore size distributions (PSD) and supercritical H2 isotherms have been measured for two activated carbon fiber (ACF) samples. The surface area and the PSD both depend on the degree of activation to which the ACF has been exposed. The low-surface-area ACF has a narrow PSD centered at 0.5 nm, while the high-surface-area ACF has a broad distribution of pore widths between 0.5 and 2 nm. The H2 adsorption enthalpy in the zero-coverage limit depends on the relative abundance of the smallest pores relative to the larger pores. Measurements of the H2 isosteric adsorption enthalpy indicate the presence of energy heterogeneity in both ACF samples. Additional measurements on a microporous, coconut-derived activated carbon are presented for reference.

  9. Pore size distribution and supercritical hydrogen adsorption in activated carbon fibers

    International Nuclear Information System (INIS)

    Purewal, J J; Kabbour, H; Ahn, C C; Fultz, B; Vajo, J J

    2009-01-01

    Pore size distributions (PSD) and supercritical H 2 isotherms have been measured for two activated carbon fiber (ACF) samples. The surface area and the PSD both depend on the degree of activation to which the ACF has been exposed. The low-surface-area ACF has a narrow PSD centered at 0.5 nm, while the high-surface-area ACF has a broad distribution of pore widths between 0.5 and 2 nm. The H 2 adsorption enthalpy in the zero-coverage limit depends on the relative abundance of the smallest pores relative to the larger pores. Measurements of the H 2 isosteric adsorption enthalpy indicate the presence of energy heterogeneity in both ACF samples. Additional measurements on a microporous, coconut-derived activated carbon are presented for reference.

  10. Interaction of biocompatible natural rosin-based surfactants with human serum albumin: A biophysical study

    International Nuclear Information System (INIS)

    Ishtikhar, Mohd; Ali, Mohd Sajid; Atta, Ayman M.; Al-Lohedan, H.A.; Nigam, Lokesh; Subbarao, Naidu; Hasan Khan, Rizwan

    2015-01-01

    Biophysical insight into interaction of biocompatible rosin-based surfactants with human serum albumin (HSA) was studied at physiological conditions using various spectroscopic, calorimetric and molecular docking approaches. The binding constant (K b ), enthalpy (ΔH 0 ), entropy (ΔS 0 ) and Gibbs free energy change (ΔG 0 ) were calculated by spectroscopic and calorimetric method. We have also calculated the probability of energy transfer by FRET analysis. The circular dichroism study showed that the cationic surfactant QRMAE significantly altered the secondary structure of HSA as compared to the nonionic rosin surfactants. The thermodynamic study was performed by ITC to determine binding constant as well as change in enthalpy of HSA in presence of rosin surfactants. It clearly showed that hydrogen binding and hydrophobic interaction play an important role in the binding of HSA to rosin surfactants. We have also performed molecular docking studies to locate the binding site on HSA and to visualize the mode of interaction. The present study provides a significant insight into HSA–rosin surfactants interaction, which also improves our understanding of the possible effect of rosin surfactants on human health. - Highlights: • RMPEG 750 has the highest Kb, Kq and Ksv value as compared to other rosin surfactants. • The probability of energy transfer from HSA to rosin surfactants was maximum in the case of RMPEG 750. • Cationic surfactant QRMAE significantly altered the secondary structure of the HSA as compared to other rosin surfactants. • Molecular docking and ITC experiment studies, to locate the binding site on HSA and to investigate the mode of interaction

  11. Membranolytic Activity of Bile Salts: Influence of Biological Membrane Properties and Composition

    Directory of Open Access Journals (Sweden)

    Alfred Blume

    2007-10-01

    Full Text Available The two main steps of the membranolytic activity of detergents: 1 the partitioning of detergent molecules in the membrane and 2 the solubilisation of the membrane are systematically investigated. The interactions of two bile salt molecules, sodium cholate (NaC and sodium deoxycholate (NaDC with biological phospholipid model membranes are considered. The membranolytic activity is analysed as a function of the hydrophobicity of the bile salt, ionic strength, temperature, membrane phase properties, membrane surface charge and composition of the acyl chains of the lipids. The results are derived from calorimetric measurements (ITC, isothermal titration calorimetry. A thermodynamic model is described, taking into consideration electrostatic interactions, which is used for the calculation of the partition coefficient as well as to derive the complete thermodynamic parameters describing the interaction of detergents with biological membranes (change in enthalpy, change in free energy, change in entropy etc. The solubilisation properties are described in a so-called vesicle-to-micelle phase transition diagram. The obtained results are supplemented and confirmed by data obtained from other biophysical techniques (DSC differential scanning calorimetry, DLS dynamic light scattering, SANS small angle neutron scattering.

  12. Interactions Increase Forager Availability and Activity in Harvester Ants.

    Directory of Open Access Journals (Sweden)

    Evlyn Pless

    Full Text Available Social insect colonies use interactions among workers to regulate collective behavior. Harvester ant foragers interact in a chamber just inside the nest entrance, here called the 'entrance chamber'. Previous studies of the activation of foragers in red harvester ants show that an outgoing forager inside the nest experiences an increase in brief antennal contacts before it leaves the nest to forage. Here we compare the interaction rate experienced by foragers that left the nest and ants that did not. We found that ants in the entrance chamber that leave the nest to forage experienced more interactions than ants that descend to the deeper nest without foraging. Additionally, we found that the availability of foragers in the entrance chamber is associated with the rate of forager return. An increase in the rate of forager return leads to an increase in the rate at which ants descend to the deeper nest, which then stimulates more ants to ascend into the entrance chamber. Thus a higher rate of forager return leads to more available foragers in the entrance chamber. The highest density of interactions occurs near the nest entrance and the entrances of the tunnels from the entrance chamber to the deeper nest. Local interactions with returning foragers regulate both the activation of waiting foragers and the number of foragers available to be activated.

  13. Biochemical investigation of yttrium(III) complex containing 1,10-phenanthroline: DNA binding and antibacterial activity.

    Science.gov (United States)

    Khorasani-Motlagh, Mozhgan; Noroozifar, Meissam; Moodi, Asieh; Niroomand, Sona

    2013-03-05

    Characterization of the interaction between yttrium(III) complex containing 1,10-phenanthroline as ligand, [Y(phen)2Cl(OH2)3]Cl2⋅H2O, and DNA has been carried out by UV absorption, fluorescence spectra and viscosity measurements in order to investigate binding mode. The experimental results indicate that the yttrium(III) complex binds to DNA and absorption is decreasing in charge transfer band with the increase in amount of DNA. The binding constant (Kb) at different temperatures as well as thermodynamic parameters, enthalpy change (ΔH°) and entropy change (ΔS°), were calculated according to relevant fluorescent data and Vant' Hoff equation. The results of interaction mechanism studies, suggested that groove binding plays a major role in the binding of the complex and DNA. The activity of yttrium(III) complex against some bacteria was tested and antimicrobial screening tests shown growth inhibitory activity in the presence of yttrium(III) complex. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Determination of the enthalpy of fusion and thermal diffusivity for ternary Cu_6_0_−_xSn_xSb_4_0 alloys

    International Nuclear Information System (INIS)

    Zhai, W.; Zhou, K.; Hu, L.; Wei, B.

    2016-01-01

    Highlights: • The increasing Sn content reduces the liquidus temperature. • High Sn content results in lower enthalpy of fusion by polynomial functions. • The thermal diffusivity drops from the solid toward the semi-solid state. • Undercoolability of alloys with primary Cu_2Sb phase is stronger than others. - Abstract: The liquidus and solidus temperatures, enthalpy of fusion, and the temperature dependence of thermal diffusivity for ternary Cu_6_0_−_xSn_xSb_4_0 alloys were systematically measured by DSC and laser flash methods. It is found that both the liquidus temperature and the enthalpy of fusion decrease with the rise of Sn content, and their relationships with alloy composition were established by polynomial functions. The thermal diffusivity usually drops from the solid toward the semi-solid state. The undercoolability of those liquid Cu_6_0_−_xSn_xSb_4_0 alloys with primary Cu_2Sb solid phase is stronger than the others with primary β(SnSb) intermetallic compound, and the increase of cooling rate facilitates further undercooling. Microstructural observation indicates that both of the primary Cu_2Sb and β(SnSb) intermetallic compounds in ternary Cu_6_0_−_xSn_xSb_4_0 alloys grow in faceted mode, and develop into coarse flakes and polygonal blocks.

  15. Thermodynamics of interaction of ionic liquids with lipid monolayer.

    Science.gov (United States)

    Bhattacharya, G; Mitra, S; Mandal, P; Dutta, S; Giri, R P; Ghosh, S K

    2018-06-01

    Understanding the interaction of ionic liquids with cellular membrane becomes utterly important to comprehend the activities of these liquids in living organisms. Lipid monolayer formed at the air-water interface is employed as a model system to follow this interaction by investigating important thermodynamic parameters. The penetration kinetics of the imidazolium-based ionic liquid 1-decyl-3-methylimidazolium tetrafluoroborate ([DMIM][BF4]) into the zwitterionic 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid layer is found to follow the Boltzmann-like equation that reveals the characteristic time constant which is observed to be the function of initial surface pressure. The enthalpy and entropy calculated from temperature-dependent pressure-area isotherms of the monolayer show that the added ionic liquids bring about a disordering effect in the lipid film. The change in Gibbs free energy indicates that an ionic liquid with longer chain has a far greater disordering effect compared to an ionic liquid with shorter chain. The differential scanning calorimetric measurement on a multilamellar vesicle system shows the main phase transition temperature to shift to a lower value, which, again, indicates the disordering effect of the ionic liquid on lipid membrane. All these studies fundamentally point out that, when ionic liquids interact with lipid molecules, the self-assembled structure of a cellular membrane gets perturbed, which may be the mechanism of these molecules having adverse effects on living organisms.

  16. Thermogravimetric determination of the enthalpy of astatine and radon adsorption on palladium surfaces

    International Nuclear Information System (INIS)

    Eichler, B.; Son Chun, K.

    1985-01-01

    In order to investigate the adsorption of astatine and radon on a palladium surface some on- and off-line thermochromatographic experiments were carried out with 210 At and 220 Rn tracers. The partial molar adsorption enthalpy for zero covering was found to be ΔH/sub a//sup 0, loc./(At) = -(15S +- 10) kJ mole -1 and ΔH/sub a//sup 0, mob./(Rn) = -(37 +- 4) kJ mole -1 . The results are compared with theoretical and experimental values for other elements of the sixth period. The adsorption behaviour of At is in conformity with that of the p-metals on a palladium surface. (author)

  17. Hydrodynamic Interactions in Active and Passive Matter

    Science.gov (United States)

    Krafnick, Ryan C.

    Active matter is present at all biological length scales, from molecular apparatuses interior to cells, to swimming microscopic organisms, to birds, fish, and people. Its properties are varied and its applications diverse, but our understanding of the fundamental driving forces of systems with these constituents remains incomplete. This thesis examines active matter suspensions, exploring the role of hydrodynamic interactions on the unique and emergent properties therein. Both qualitative and quantitative impacts are considered, and care is taken in determining the physical origin of the results in question. It is found that fluid dynamical interactions are fundamentally, qualitatively important, and much of the properties of a system can be explained with an effective energy density defined via the fluid fields arising from the embedded self-propelling entities themselves.

  18. Study on the interaction of the toxic food additive carmoisine with serum albumins: A microcalorimetric investigation

    International Nuclear Information System (INIS)

    Basu, Anirban; Kumar, Gopinatha Suresh

    2014-01-01

    Highlights: • Carmoisine binds to both the serum albumins with affinity of the order of 10 6 M −1 . • The binding was favored by negative enthalpy and positive entropy changes. • The binding was dominated by hydrophobic forces. • Carmoisine enhanced the thermal stability of both the proteins remarkably. - Abstract: The interaction of the synthetic azo dye and food colorant carmoisine with human and bovine serum albumins was studied by microcalorimetric techniques. A complete thermodynamic profile of the interaction was obtained from isothermal titration calorimetry studies. The equilibrium constant of the complexation process was of the order of 10 6 M −1 and the binding stoichiometry was found to be 1:1 with both the serum albumins. The binding was driven by negative standard molar enthalpy and positive standard molar entropy contributions. The binding affinity was lower at higher salt concentrations in both cases but the same was dominated by mostly non-electrostatic forces at all salt concentrations. The polyelectrolytic forces contributed only 5–8% of the total standard molar Gibbs energy change. The standard molar enthalpy change enhanced whereas the standard molar entropic contribution decreased with rise in temperature but they compensated each other to keep the standard molar Gibbs energy change almost invariant. The negative standard molar heat capacity values suggested the involvement of a significant hydrophobic contribution in the complexation process. Besides, enthalpy–entropy compensation phenomenon was also observed in both the systems. The thermal stability of the serum proteins was found to be remarkably enhanced on binding to carmoisine

  19. Effect of the composition of a solution on the enthalpies of solvation of piperidine in methanol-acetonitrile and dimethylsulfoxide-acetonitrile mixed solvents

    Science.gov (United States)

    Kuz'mina, I. A.; Volkova, M. A.; Sitnikova, K. A.; Sharnin, V. A.

    2014-01-01

    Heat effects of dissolution of piperidine (ppd) are measured by calorimetry at 298.15 K over the range of composition of acetonitrile-methanol (AN-MeOH) mixed solvents. Based on the Δsol H ○(ppd)AN-MeOH values obtained using the literature data on Δsol H ○ (ppd) in acetonitrile-dimethylsulfoxide (AN-DMSO) mixed solvents and the vaporization enthalpy of ppd, the enthalpies of solvation of amine in AN-MeOH and AN-DMSO binary mixtures are calculated. A rise in the exothermicity of solvation of piperidine is observed upon the transition from AN to DMSO and MeOH, due mainly to the enhanced solvation of the amino group of ppd as a result of changes in the acid-base properties of the mixed solvent.

  20. On the synthesis of a compound with positive enthalpy of formation: Zinc-blende-like RuN thin films obtained by rf-magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Cattaruzza, E., E-mail: cattaruz@unive.it [Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155/B, 30172 Mestre-VE (Italy); Battaglin, G.; Riello, P. [Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155/B, 30172 Mestre-VE (Italy); Cristofori, D. [Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice and Centre for Electron Microscopy “Giovanni Stevanato”, Via Torino 155/B, 30172 Mestre-VE (Italy); Tamisari, M. [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1, 44121 Ferrara (Italy)

    2014-11-30

    Highlights: • RuN thin films in the zinc-blende structure have been synthesized by rf-magnetron sputtering. • Contribute is given to the understanding of phase-formation mechanisms in systems that under ambient conditions present positive enthalpies of formation. • Contribute is given to the understanding of phenomena occurring during reactive sputtering processes. • Nanopillar structure: suitable for application requiring a high effective area, like sensing, catalysis, and electrode material for energy-storage devices. - Abstract: 4d- and 5d-transition metal nitrides are of interest both because of their importance for the understanding of mechanisms of phase formation in systems that under ambient conditions present positive enthalpies of formation and because of their appealing structural and electronic properties. In this study, we report the synthesis of thin films of ruthenium mononitride (RuN) in the zinc-blende structure by radio-frequency-magnetron sputtering. Films present a characteristic structure of packed columns ending with tetrahedral tips. The effect of changing the synthesis parameters was investigated in detail. It was found that RuN can be formed if the nitrogen partial pressure exceeds a minimum value and that the addition of argon has the major effect of increasing the deposition rate because of its higher sputter ability. Temperature plays an important role: if it is too high, decomposition/desorption effects overcome those leading to the formation of the compound. Phenomena resulting in the formation of RuN occur at the surface of the growing films and are related to the interactions of ruthenium with energetic nitrogen ions, or atoms, which can penetrate the first atomic layers by low energy implantation. Because of its properties and structure, this material is a promising candidate for applications like sensing, catalysis, and electrode material for energy-storage devices.