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Sample records for adiabatic heat-capacity calorimetry

  1. Accurate Measurement of Heat Capacity by Differential Scanning Calorimetry

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Experience with high quality heat capacity measurement by differential scanning calorimetry is summarized and illustrated, pointing out three major causes of error: (1) incompatible thermal histories of the sample, reference and blank runs; (2) unstable initial and final isotherms; (3) incompatible differences between initial and final isotherm amplitudes for sample, reference and blank runs. Considering these problems, it is shown for the case of polyoxymethylene that accuracies in heat capacity of 0.1 percent may be possible.

  2. Heat capacity of alkanolamines by differential scanning calorimetry

    SciTech Connect

    Chiu, L.F.; Liu, H.F.; Li, M.H.

    1999-05-01

    Measurements of the heat capacities of the alkanolamines monoethanolamine, diethanolamine, diglycolamine, di-2-propanolamine, triethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-l-propanol, and 2-piperidineethanol were performed from 30 to 80 C with a differential scanning calorimeter (DSC). The heat capacity of liquid water has been measured to verify the validity of the C{sub p} measurements. The measured C{sub p} of each alkanolamine has been expressed as a function of temperature. The estimated uncertainty of the measured heat capacities including the effect of impurities in a substance with a purity of 95% is {+-}3%. The measured heat capacities are, in general, of sufficient accuracy for most engineering-design calculations.

  3. Calorimetry on a Chip: Toward Heat Capacities of Microgram Quantities of Iron-bearing Minerals

    NASA Astrophysics Data System (ADS)

    Navrotsky, A.; Hellman, F.; Dorogova, M.; Cooke, D.; Queen, D.

    2005-12-01

    Heat capacities, standard entropies, and magnetic phase transitions in iron-bearing mantle minerals are poorly known because conventional adiabatic calorimetry requires samples too large to be synthesized at very high pressure. Specific heat measurements on microgram sized samples are based on a Si-micromachined calorimetry device. These devices have been in use for a decade in the physics and materials science community for measurements on metals and on selected oxides such as CoO. These calorimeters on a chip have been used for both thin films and small bulk samples. Different designs have been optimized for different uses, but the heart of the device is a thin (1800 ?) 0.5 x 0.5 cm2 amorphous Si3N4 membrane supported by a 1 x 1 cm2 Si frame. On one side of this membrane, we deposit and pattern thin film heater, thermometers, and electrical leads of appropriate resistance and temperature coefficient. On the other side, in a 0.25 x 0.25 cm2 area at the center, we deposit the sample and a thermally conducting material such as gold or copper. This thin membrane provides the necessary thermal isolation of sample from environment, while still providing a sample/thermometer platform. On the frame are matching thermometers to those on the membrane to permit a high sensitivity differential temperature measurement. We have made thousands of these devices and have measured hundreds. The devices are metallurgically stable and physically robust under cycling between 4.2 K and 1000 K, and can withstand photolithographic processing. Because of the nature of the fabrication process, reproducibility of specific heat addenda and of thermal link between sample and environment is very good, varying from device to device by less than 5%. Samples are measured using the relaxation method, requiring a separate determination of the thermal link between sample and environment (the steady state increase of the sample temperature with the sample heater turned on) and the time constant of

  4. Technique for determination of accurate heat capacities of volatile, powdered, or air-sensitive samples using relaxation calorimetry

    NASA Astrophysics Data System (ADS)

    Marriott, Robert A.; Stancescu, Maria; Kennedy, Catherine A.; White, Mary Anne

    2006-09-01

    We introduce a four-step technique for the accurate determination of the heat capacity of volatile or air-sensitive samples using relaxation calorimetry. The samples are encapsulated in a hermetically sealed differential scanning calorimetry pan, in which there is an internal layer of Apiezon N grease to assist thermal relaxation. Using the Quantum Design physical property measurement system to investigate benzoic acid and copper standards, we find that this method can lead to heat capacity determinations accurate to ±2% over the temperature range of 1-300K, even for very small samples (e.g., <10mg and contributing ca. 20% to the total heat capacity).

  5. A sample-saving method for heat capacity measurements on powders using relaxation calorimetry

    NASA Astrophysics Data System (ADS)

    Dachs, Edgar; Benisek, Artur

    2011-08-01

    An experimental method is described for determining the low-temperature heat capacity (Cp) of mg-sized powder samples using the Quantum Design “Physical Properties Measurement System” (PPMS). The powder is contained in an Al pan as an ∼1 mm thick compressed layer. The sample is not mixed with Apiezon N grease, as compared to other methods. Thus, it is not contaminated and can be used for further study. This is necessary for samples that are only available in tiny amounts. To demonstrate the method various samples, all insulating in nature, were studied including benzoic acid, sapphire and different silicate minerals. The measurements show that the method has an accuracy in Cp to better than 1% at T above 30-50 K and ±3-5% up to ±10% below. The experimental procedure is based on three independent PPMS and three independent differential scanning calorimetry (DSC) measurements. The DSC Cp data are used to slightly adjust the PPMS Cp data by a factor C. This is done because heat capacities measured with a DSC device are more accurate around ambient T (⩽0.6%) than PPMS values and is possible because the deviation of PPMS heat capacities from reference values is nearly constant between about 50 K and 300 K. The resulting standard entropies agree with published reference values within 0.21% for the silicates, by 0.34% for corundum, and by 0.9% for powdered benzoic acid. The method thus allows entropy determinations on powders with an accuracy of better than 1%. The advantage of our method compared to other experimental techniques is that the sample powder is not contaminated with grease and that heat capacity values show less scatter at high temperatures.

  6. A sample-saving method for heat capacity measurements on powders using relaxation calorimetry.

    PubMed

    Dachs, Edgar; Benisek, Artur

    2011-08-01

    An experimental method is described for determining the low-temperature heat capacity (C(p)) of mg-sized powder samples using the Quantum Design "Physical Properties Measurement System" (PPMS). The powder is contained in an Al pan as an ∼1 mm thick compressed layer. The sample is not mixed with Apiezon N grease, as compared to other methods. Thus, it is not contaminated and can be used for further study. This is necessary for samples that are only available in tiny amounts. To demonstrate the method various samples, all insulating in nature, were studied including benzoic acid, sapphire and different silicate minerals. The measurements show that the method has an accuracy in C(p) to better than 1% at T above 30-50 K and ±3-5% up to ±10% below. The experimental procedure is based on three independent PPMS and three independent differential scanning calorimetry (DSC) measurements. The DSC C(p) data are used to slightly adjust the PPMS C(p) data by a factor CpDSC/CpPPMSat298K. This is done because heat capacities measured with a DSC device are more accurate around ambient T (⩽0.6%) than PPMS values and is possible because the deviation of PPMS heat capacities from reference values is nearly constant between about 50 K and 300 K. The resulting standard entropies agree with published reference values within 0.21% for the silicates, by 0.34% for corundum, and by 0.9% for powdered benzoic acid. The method thus allows entropy determinations on powders with an accuracy of better than 1%. The advantage of our method compared to other experimental techniques is that the sample powder is not contaminated with grease and that heat capacity values show less scatter at high temperatures. PMID:21886915

  7. Thermal behavior, specific heat capacity and adiabatic time-to-explosion of G(FOX-7).

    PubMed

    Xu, Kangzhen; Song, Jirong; Zhao, Fengqi; Ma, Haixia; Gao, Hongxu; Chang, Chunran; Ren, Yinghui; Hu, Rongzu

    2008-10-30

    [H(2)N=C(NH(2))(2)](+)(FOX-7)(-)-G(FOX-7) was prepared by mixing FOX-7 and guanidinium chloride solution in potassium hydroxide solution. Its thermal decomposition was studied under the non-isothermal conditions with DSC and TG/DTG methods. The apparent activation energy (E) and pre-exponential constant (A) of the two exothermic decomposition stages were obtained by Kissinger's method and Ozawa's method, respectively. The critical temperature of thermal explosion (T(b)) was obtained as 201.72 degrees C. The specific heat capacity of G(FOX-7) was determined with Micro-DSC method and theoretical calculation method and the standard molar specific heat capacity is 282.025 J mol(-1) K(-1) at 298.15 K. Adiabatic time-to-explosion of G(FOX-7) was also calculated to be a certain value between 13.95 and 15.66 s. PMID:18336998

  8. THE HEAT CAPACITY OF FLUORINATED PROPANE AND BUTANE DERIVATIVES BY DIFFERENTIAL SCANNING CALORIMETRY

    EPA Science Inventory

    The paper gives results of the measurement (to 3% accuracy) of the constant-pressure liquid-phase heat capacities of 21 hydrogen-containing fluorinated propane and butane derivatives and one fluorinated ether (CF3OCF2H) with boiling points ranging from -34.6 to 76.7 C, using diff...

  9. Thermal characterization of starch-water system by photopyroelectric technique and adiabatic scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Cruz-Orea, A.; Bentefour, E. H.; Jamée, P.; Chirtoc, M.; Glorieux, C.; Pitsi, G.; Thoen, J.

    2003-01-01

    Starch is one of the most important carbohydrate sources in human nutrition. For the thermal analysis of starch, techniques such as differential scanning calorimetry have been extensively used. As an alternative, we have applied a photopyroelectric (PPE) configuration and adiabatic scanning calorimetry (ASC) to study the thermal properties of starch-water systems. For this study we used nixtamalized corn flour and potato starch with different quantities of distilled water, in order to obtain samples with different moisture content. By using PPE and ASC methods we have measured, for each technique separately, the heat capacity by unit volume (ρcp) at room temperature for a corn flour sample at 90% moisture. The obtained values agree within experimental uncertainty. By using these techniques we also studied the thermal behavior of potato starch, at 80% moisture, in the temperature range where phase transitions occur. In this case the PPE signal phase could be used as a sensitive and versatile monitor for phase transitions.

  10. A simple calorimeter for fast adiabatic heat capacity measurements from 15 to 300 K based on closed cycle cryocooler

    NASA Astrophysics Data System (ADS)

    Catarino, I.; Bonfait, G.

    2000-01-01

    A simple, cryogen-free and inexpensive experimental setup for fast heat capacity measurements of solids from 15 to 300 K is presented. It consists of a thermally controlled cell, coupled to the cold finger of a Gifford-Mac Mahon cryocooler, containing two cheap Pt thin film resistors as thermometers: one is simultaneously the sample holder, the sample heater and the sample thermometer; the other resistor is used for temperature control. This calorimeter allows adiabatic specific heat measurements in the whole temperature range in less than one hour. The heat capacity results for a 106 mg copper sample match the tabulated values within 2% for T > 20 K. This system was used to measure the specific heat of UFe xAl 12-x with sample masses as low as 26 mg without performance degradation.

  11. Heat capacity and entropy of Ni2SiO4-olivine from 5 to 1000 K and heat capacity of Co2SiO4 from 360 to 1000 K.

    USGS Publications Warehouse

    Robie, R.A.; Hemingway, B.S.; Ito, J.; Krupka, K.M.

    1984-01-01

    The heat capacity of Ni2SiO4-olivine has been measured between 5 and 387 K by cryogenic adiabatic-shield calorimetry and between 360 and 1000 K by differential scanning calorimetry. The heat capacity of Co2SiO4-olivine was measured between 360 and 1000 K by differential scanning calorimetry.-J.A.Z.

  12. High Temperature Heat Capacity of Alloy D9 Using Drop Calorimetry Based Enthalpy Increment Measurements

    NASA Astrophysics Data System (ADS)

    Banerjee, Aritra; Raju, S.; Divakar, R.; Mohandas, E.

    2007-02-01

    Alloy D9 is a void-swelling resistant nuclear grade austenitic stainless steel (SS) based on AISI type 316-SS in which titanium constitutes an added predetermined alloying composition. In the present study, the high-temperature enthalpy values of alloy D9 with three different titanium-to-carbon mass percent ratios, namely Ti/C = 4, 6, and 8, have been measured using inverse drop calorimetry in the temperature range from 295 to 1323 K. It is found that within the level of experimental uncertainty, the enthalpy values are independent of the Ti-C mass ratio. The temperature dependence of the isobaric specific heat C P is obtained by a linear regression of the measured enthalpy data. The measured C P data for alloy D9 may be represented by the following best-fit expression: C_P(J \\cdot kg^{-1}\\cdot K^{-1})= 431 + 17.7 × 10^{-2}T + 8.72 × 10^{-5}/T^2. It is found that the measured enthalpy and specific heat values exhibit good agreement with reported data on 316 and other related austenitic stainless steels.

  13. The Adiabatic Expansion of Gases and the Determination of Heat Capacity Ratios: A Physical Chemistry Experiment.

    ERIC Educational Resources Information Center

    Moore, William M.

    1984-01-01

    Describes the procedures and equipment for an experiment on the adiabatic expansion of gases suitable for demonstration and discussion in the physical chemical laboratory. The expansion produced shows how the process can change temperature and still return to a different location on an isotherm. (JN)

  14. Preparation, non-isothermal decomposition kinetics, heat capacity and adiabatic time-to-explosion of NTOxDNAZ.

    PubMed

    Ma, Haixia; Yan, Biao; Li, Zhaona; Guan, Yulei; Song, Jirong; Xu, Kangzhen; Hu, Rongzu

    2009-09-30

    NTOxDNAZ was prepared by mixing 3,3-dinitroazetidine (DNAZ) and 3-nitro-1,2,4-triazol-5-one (NTO) in ethanol solution. The thermal behavior of the title compound was studied under a non-isothermal condition by DSC and TG/DTG methods. The kinetic parameters were obtained from analysis of the DSC and TG/DTG curves by Kissinger method, Ozawa method, the differential method and the integral method. The main exothermic decomposition reaction mechanism of NTOxDNAZ is classified as chemical reaction, and the kinetic parameters of the reaction are E(a)=149.68 kJ mol(-1) and A=10(15.81)s(-1). The specific heat capacity of the title compound was determined with continuous C(p) mode of microcalorimeter. The standard mole specific heat capacity of NTOxDNAZ was 352.56 J mol(-1)K(-1) in 298.15K. Using the relationship between C(p) and T and the thermal decomposition parameters, the time of the thermal decomposition from initialization to thermal explosion (adiabatic time-to-explosion) was obtained. PMID:19446396

  15. Hydroxylamine nitrate self-catalytic kinetics study with adiabatic calorimetry.

    PubMed

    Liu, Lijun; Wei, Chunyang; Guo, Yuyan; Rogers, William J; Sam Mannan, M

    2009-03-15

    Hydroxylamine nitrate (HAN) is an important member of the hydroxylamine compound family with applications that include equipment decontamination in the nuclear industry and aqueous or solid propellants. Due to its instability and autocatalytic behavior, HAN has been involved in several incidents at the Hanford and Savannah River Site (SRS) [Technical Report on Hydroxylamine Nitrate, US Department of Energy, 1998]. Much research has been conducted on HAN in different areas, such as combustion mechanism, decomposition mechanism, and runaway behavior. However, the autocatalytic decomposition behavior of HAN at runaway stage has not been fully addressed due to its highly exothermic and rapid decomposition behavior. This work is focused on extracting HAN autocatalytic kinetics and analyzing HAN critical behavior from adiabatic calorimetry measurements. A lumped autocatalytic kinetic model for HAN and associated model parameters are determined. Also the storage and handling critical conditions of diluted HAN solution without metal presence are quantified. PMID:18639378

  16. Low-Temperature Polymorphic Phase Transition in a Crystalline Tripeptide l-Ala-l-Pro-Gly·H2O Revealed by Adiabatic Calorimetry

    PubMed Central

    Markin, Alexey V.; Markhasin, Evgeny; Sologubov, Semen S.; Ni, Qing Zhe; Smirnova, Natalia N.; Griffin, Robert G.

    2015-01-01

    We demonstrate application of precise adiabatic vacuun calorimetry to observation of phase transition in the tripeptide l-alanyl-l-prolyl-glycine monohydrate (APG) from 6 to 320 K and report the standard thermodynamic properties of the tripeptide in the entire range. Thus, the heat capacity of APG was measured by adiabatic vacuun calorimetry in the above temperature range. The tripeptide exhibits a reversible first-order solid-to-solid phase transition characterized by strong thermal hysteresis. We report the standard thermodynamic characteristics of this transition and show that differential scanning calorimetry can reliably characterize the observed phase transition with <5 mg of the sample. Additionally, the standard entropy of formation from the elemental substances and the standard entropy of hypothetical reaction of synthesis from the amino acids at 298.15 K were calculated for the studied tripeptide. PMID:25588051

  17. Adiabatic calorimetry (RSST and VSP) tests with sodium acetate

    SciTech Connect

    Kirch, N.W.

    1993-09-01

    As requested in the subject reference, adiabatic calorimetry (RSST and VSP) tests have been performed with sodium acetate covering TOC concentrations from 3 to 7% with the following results: Exothermic activity noted around 200{degrees}C. Propagating reaction initiated at about 300{degrees}C. Required TOC concentration for propagation estimated at about 6 w% (dry mixture) or about 20 w% sodium acetate. Heat of reaction estimated to be 3.7 MJ per kg of sodium acetate (based on VSP test with 3 w% TOC and using a dry mixture specific heat of 1000 J kg{sup {minus}1} K{sup {minus}1}). Based upon the above results we estimate that a moisture content in excess of 14 w% would prevent a propagating reaction of a stoichiometric mixture of fuel and oxidizer ({approximately} 38 w% sodium acetate and {approximately}62 w% sodium nitrate). Assuming that the fuel can be treated as sodium acetate equivalent, and considering that the moisture content in the organic containing waste generally is believed to be in excess of 14 w%, it follows that the possibility of propagating reactions in the Hanford waste tanks can be ruled out.

  18. Heat capacities and thermodynamic properties of annite (aluminous iron biotite)

    USGS Publications Warehouse

    Hemingway, B.S.; Robie, R.A.

    1990-01-01

    The heat capacities have been measured between 7 and 650 K by quasi-adiabatic calorimetry and differential scanning calorimetry. At 298.15 K and 1 bar, the calorimetric entropy for our sample is 354.9??0.7 J/(mol.K). A minimum configurational entropy of 18.7 J/(mol.K) for full disorder of Al/Si in the tetrahedral sites should be added to the calorimetric entropy for third-law calculations. The heat capacity equation [Cp in units of J/mol.K)] Cp0 = 583.586 + 0.075246T - 3420.60T-0.5 - (4.4551 ?? 106)T-2 fits the experimental and estimated heat capacities for our sample (valid range 250 to 1000 K) with an average deviation of 0.37%. -from Authors

  19. Determination of caloric values of agricultural crops and crop waste by Adiabatic Bomb Calorimetry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calorific values of agricultural crops and their waste were measured by adiabatic bomb calorimetry. Sustainable farming techniques require that all potential sources of revenue be utilized. A wide variety of biomass is beginning to be used as alternative fuels all over the world. The energy potentia...

  20. Hydration water and peptide dynamics--two sides of a coin. A neutron scattering and adiabatic calorimetry study at low hydration and cryogenic temperatures.

    PubMed

    Bastos, Margarida; Alves, Nuno; Maia, Sílvia; Gomes, Paula; Inaba, Akira; Miyazaki, Yuji; Zanotti, Jean-Marc

    2013-10-21

    In the present work we bridge neutron scattering and calorimetry in the study of a low-hydration sample of a 15-residue hybrid peptide from cecropin and mellitin CA(1-7)M(2-9) of proven antimicrobial activity. Quasielastic and low-frequency inelastic neutron spectra were measured at defined hydration levels - a nominally 'dry' sample (specific residual hydration h = 0.060 g/g), a H2O-hydrated (h = 0.49) and a D2O-hydrated one (h = 0.51). Averaged mean square proton mobilities were derived over a large temperature range (50-300 K) and the vibrational density of states (VDOS) were evaluated for the hydrated samples. The heat capacity of the H2O-hydrated CA(1-7)M(2-9) peptide was measured by adiabatic calorimetry in the temperature range 5-300 K, for different hydration levels. The glass transition and water crystallization temperatures were derived in each case. The existence of different types of water was inferred and their amounts calculated. The heat capacities as obtained from direct calorimetric measurements were compared to the values derived from the neutron spectroscopy by way of integrating appropriately normalized VDOS functions. While there is remarkable agreement with respect to both temperature dependence and glass transition temperatures, the results also show that the VDOS derived part represents only a fraction of the total heat capacity obtained from calorimetry. Finally our results indicate that both hydration water and the peptide are involved in the experimentally observed transitions. PMID:23986181

  1. Crystallization and fusion behaviors, observed by adiabatic calorimetry, of benzene confined in silica mesopores with uniform diameters.

    PubMed

    Nagoe, Atsushi; Oguni, Masaharu; Fujimori, Hiroki

    2015-03-18

    Heat capacities and spontaneous enthalpy-relaxation effects of the benzene confined in silica MCM-41 and SBA-15 pores with uniform diameters were measured by high-precision adiabatic calorimetry. The fusion temperatures and fusion enthalpies determined were compared with the literature results of benzene confined within pores of CPG glasses. It was confirmed, from the observed spontaneous heat-release or -absorption effects, that there exists a non-crystallizing amorphous component of confined benzene, as reported previously. The pore-diameter dependence of fusion enthalpy observed was inconsistent with the previously proposed model which suggested that the non-crystallizing amorphous component is located on the pore wall in the form of a shell-like structure of a few nm in thickness. A very slow relaxation process corresponding to a translational-diffusion motion of molecule was observed, indicating that the benzene fills the pores incompletely along the pore channel. In addition, we found that the fusion enthalpy as a function of inverse pore-diameter dependence decreases steeply in the range of 60-10 nm in diameter while gradually in the range around 5 nm. PMID:25627639

  2. Crystallization and fusion behaviors, observed by adiabatic calorimetry, of benzene confined in silica mesopores with uniform diameters

    NASA Astrophysics Data System (ADS)

    Nagoe, Atsushi; Oguni, Masaharu; Fujimori, Hiroki

    2015-03-01

    Heat capacities and spontaneous enthalpy-relaxation effects of the benzene confined in silica MCM-41 and SBA-15 pores with uniform diameters were measured by high-precision adiabatic calorimetry. The fusion temperatures and fusion enthalpies determined were compared with the literature results of benzene confined within pores of CPG glasses. It was confirmed, from the observed spontaneous heat-release or -absorption effects, that there exists a non-crystallizing amorphous component of confined benzene, as reported previously. The pore-diameter dependence of fusion enthalpy observed was inconsistent with the previously proposed model which suggested that the non-crystallizing amorphous component is located on the pore wall in the form of a shell-like structure of a few nm in thickness. A very slow relaxation process corresponding to a translational-diffusion motion of molecule was observed, indicating that the benzene fills the pores incompletely along the pore channel. In addition, we found that the fusion enthalpy as a function of inverse pore-diameter dependence decreases steeply in the range of 60-10 nm in diameter while gradually in the range around 5 nm.

  3. Schottky contribution to the heat capacity of monazite type (La, Pr)PO4 from low temperature calorimetry and fluorescence measurements

    NASA Astrophysics Data System (ADS)

    Bauer, J. D.; Hirsch, A.; Bayarjargal, L.; Peters, L.; Roth, G.; Winkler, B.

    2016-06-01

    We show that the combination of fluorescence spectroscopy and low temperature heat capacity measurements of Pr-containing samples in the (La, Pr)PO4 solid solution series can be employed to strongly constrain the Stark energy levels of Pr3+ in monazite type structures. The resulting set of Stark energy levels for the 3H4 ground state of Pr3+ reproduces the low temperature Schottky anomaly of the heat capacity much more accurately than theoretical models published earlier. We also show that there is no excess heat capacity along the binary solid solution with respect to an interpolation between the two end members LaPO4 and PrPO4.

  4. Introduction of Differential Scanning Calorimetry in a General Chemistry Laboratory Course: Determination of Heat Capacity of Metals and Demonstration of Law of Dulong and Petit

    ERIC Educational Resources Information Center

    D'Amelia, Ronald P.; Stracuzzi, Vincent; Nirode, William F.

    2008-01-01

    Today's general chemistry students are introduced to many of the principles and concepts of thermodynamics. In first-year general chemistry undergraduate courses, thermodynamic properties such as heat capacity are frequently discussed. Classical calorimetric methods of analysis and thermal equilibrium experiments are used to determine heat…

  5. Heat capacity, configurational heat capacity and fragility of hydrous magmas

    NASA Astrophysics Data System (ADS)

    Di Genova, D.; Romano, C.; Giordano, D.; Alletti, M.

    2014-10-01

    The glassy and liquid heat capacities of four series of dry and hydrous natural glasses and magma as a function of temperature and water content (up to 19.9 mol%) were investigated using differential scanning calorimetry (DSC). The analyzed compositions are basalt, latite, trachyte and pantellerite. The results of this study indicate that the measured heat capacity of glasses (Cpg) is a linear function of composition and is well reproduced by the empirical model of Richet (1987). For the investigated glasses, the partial molar heat capacity of water can be considered as independent of composition, in agreement with Bouhifd et al. (2006). For hydrous liquids, the heat capacity (Cpliq) decreases nonlinearly with increasing water content. Previously published models, combined with the partial molar heat capacity of water from the literature, are not able to reproduce our experimental data in a satisfactory way. We estimated the partial molar heat capacity of water (CpH2O) in hydrous magma over a broad compositional range. The proposed value is 41 ± 3 J mol-1 K-1. Water strongly affects the configurational heat capacity at the glass transition temperature [Cpconf (Tg)]. An increases of Cpconf (Tg) with water content was measured for the polymerized liquids (trachyte and pantellerite), while the opposite behavior was observed for the most depolymerized liquids (basalt and latite). Structural and rheological implications of this behavior are discussed in light of the presented results.

  6. MEASUREMENT OF SPECIFIC HEAT CAPACITY OF SALTSTONE

    SciTech Connect

    Harbour, J; Vickie Williams, V

    2008-09-29

    One of the goals of the Saltstone variability study is to identify (and quantify the impact of) the operational and compositional variables that control or influence the important processing and performance properties of Saltstone grout mixtures. The heat capacity of the Saltstone waste form is one of the important properties of Saltstone mixes that was last measured at SRNL in 1997. It is therefore important to develop a core competency for rapid and accurate analysis of the specific heat capacity of the Saltstone mixes in order to quantify the impact of compositional and operational variations on this property as part of the variability study. The heat capacity, coupled with the heat of hydration data obtained from isothermal calorimetry for a given Saltstone mix, can be used to predict the maximum temperature increase in the cells within the vaults of the Saltstone Disposal Facility (SDF). The temperature increase controls the processing rate and the pour schedule. The maximum temperature is also important to the performance properties of the Saltstone. For example, in mass pours of concrete or grout of which Saltstone is an example, the maximum temperature increase and the maximum temperature difference (between the surface and the hottest location) are controlled to ensure durability of the product and prevent or limit the cracking caused by the thermal gradients produced during curing. This report details the development and implementation of a method for the measurement of the heat capacities of Saltstone mixes as well as the heat capacities of the cementitious materials of the premix and the simulated salt solutions used to batch the mixes. The developed method utilizes the TAM Air isothermal calorimeter and takes advantage of the sophisticated heat flow measurement capabilities of the instrument. Standards and reference materials were identified and used to validate the procedure and ensure accuracy of testing. Heat capacities of Saltstone mixes were

  7. Conformational Contribution to the Heat Capacity of Starch and Starch-Water

    NASA Astrophysics Data System (ADS)

    Pyda, Marek; Wunderlich, Bernhard

    2000-03-01

    The heat capacities of starch and starch-water have been measured using adiabatic calorimetry, and standard differential scanning calorimetry (DSC) and are reported from 5 K to 510 K. The amorphous starch containing 10 wt water shows a glass transition around 350 K. The heat capacities of the solid of amorphous, dry starch is linked to an approximate group vibrational spectrum, and the Tarasov equation is used to estimate the heat capacity contribution due to skeletal vibrations ( theta1 = 830 K and theta2 = 85 K theta3 = 85 K, Nskeletal = 17). The calculated and experimental heat capacities agree to better than ±3between 5 and 250 K. The experimental heat capacities of starch-water and dry starch are compared over the whole range of temperatures. Above the glass transition the differences are interpreted as contributions of different conformational heat capacities from interacting chain of carbohydrate with water. The conformational part is evaluated from a fit of the experimental Cp of starch-water, decreased by the vibrational and the external Cp to a one-dimensional Ising model with two discrete states and stiffness, cooperativity, and degeneracy parameters. NSF, Polymers Program, DMR-9703692, and the Div. of Mat. Sci., BES, DOE at ORNL, managed by Lockheed Martin Energy Research Corp., DE-AC05-96OR22464.

  8. Heat capacity and thermodynamic functions for gehlenite and staurolite: with comments on the Schootky anomaly in the heat capacity of staurolite.

    USGS Publications Warehouse

    Hemingway, B.S.; Robie, R.A.

    1984-01-01

    The heat capacities of a synthetic gehlenite and a natural staurolite were measured from 12 and 5 K, respectively, to 370 K by adiabatic calorimetry, and the heat capacities of staurolite were measured to 900 K by differential scanning calorimetry. At 298.15 K and 1 bar the entropy of gehlenite is 210.1 + or - 0.6 J/(mol.K) and that of staurolite is 1019.6 + or - 12.0 for H2Al2Fe4Al16Si8O48 and 1101.0 + or - 12.0 for 103(H3Al1.15Fe2+0.60)- 324(Fe2+2.07Fe3+0.54 Ti0.08Mn0.02Al1.19)(Mg0.44Al15.26)Si8O48. -J.A.Z.

  9. Heat Capacity Analysis Report

    SciTech Connect

    A. Findikakis

    2004-11-01

    The purpose of this report is to provide heat capacity values for the host and surrounding rock layers for the waste repository at Yucca Mountain. The heat capacity representations provided by this analysis are used in unsaturated zone (UZ) flow, transport, and coupled processes numerical modeling activities, and in thermal analyses as part of the design of the repository to support the license application. Among the reports that use the heat capacity values estimated in this report are the ''Multiscale Thermohydrologic Model'' report, the ''Drift Degradation Analysis'' report, the ''Ventilation Model and Analysis Report, the Igneous Intrusion Impacts on Waste Packages and Waste Forms'' report, the ''Dike/Drift Interactions report, the Drift-Scale Coupled Processes (DST and TH Seepage) Models'' report, and the ''In-Drift Natural Convection and Condensation'' report. The specific objective of this study is to determine the rock-grain and rock-mass heat capacities for the geologic stratigraphy identified in the ''Mineralogic Model (MM3.0) Report'' (BSC 2004 [DIRS 170031], Table 1-1). This report provides estimates of the heat capacity for all stratigraphic layers except the Paleozoic, for which the mineralogic abundance data required to estimate the heat capacity are not available. The temperature range of interest in this analysis is 25 C to 325 C. This interval is broken into three separate temperature sub-intervals: 25 C to 95 C, 95 C to 114 C, and 114 C to 325 C, which correspond to the preboiling, trans-boiling, and postboiling regimes. Heat capacity is defined as the amount of energy required to raise the temperature of a unit mass of material by one degree (Nimick and Connolly 1991 [DIRS 100690], p. 5). The rock-grain heat capacity is defined as the heat capacity of the rock solids (minerals), and does not include the effect of water that exists in the rock pores. By comparison, the rock-mass heat capacity considers the heat capacity of both solids and pore

  10. Liquid heat capacity lasers

    DOEpatents

    Comaskey, Brian J.; Scheibner, Karl F.; Ault, Earl R.

    2007-05-01

    The heat capacity laser concept is extended to systems in which the heat capacity lasing media is a liquid. The laser active liquid is circulated from a reservoir (where the bulk of the media and hence waste heat resides) through a channel so configured for both optical pumping of the media for gain and for light amplification from the resulting gain.

  11. Nanofluid heat capacities

    NASA Astrophysics Data System (ADS)

    Starace, Anne K.; Gomez, Judith C.; Wang, Jun; Pradhan, Sulolit; Glatzmaier, Greg C.

    2011-12-01

    Significant increases in the heat capacity of heat transfer fluids are needed not only to reduce the costs of liquid heating and cooling processes, but also to bring clean energy producing technologies like concentrating solar power (CSP) to price parity with conventional energy generation. It has been postulated that nanofluids could have higher heat capacities than conventional fluids. In this work, nano- and micron-sized particles were added to five base fluids (poly-α olefin, mineral oil, ethylene glycol, a mixture of water and ethylene glycol, and calcium nitrate tetrahydrate), and the resulting heat capacities were measured and compared with those of the neat base fluids and the weighted average of the heat capacities of the components. The particles used were inert metals and metal oxides that did not undergo any phase transitions over the temperature range studied. In the nanofluids studied here, we found no increase in heat capacity upon the addition of the particles larger than the experimental error.

  12. Heat capacity of coal chars

    SciTech Connect

    Wang, W.Y.

    1982-01-01

    The selected starting materials were, a North Dakota lignite, an Illinois No. 6 bituminous and a Virginia coking coal. The carbon content of these coals ranged from 59 to 75 wt% (mineral matter included). Half of each of the received coal sample was demineralized using a standard procedure. Chars were prepared from the received and demineralized pulverized coals by pyrolysis. Heating rate of 5/sup 0/C/minute was employed for the pyrolysis under dry nitrogen gas atmosphere. The pyrolysis temperatures were 700, 900 and 1100/sup 0/C for periods of 0.1, 1 and 24. The char samples were characterized by chemical composition analysis, x-ray diffraction and porosimetry. Heat capacity data were collected over 75 to 300/sup 0/K temperature range using an adiabatic calorimeter. The heat capacity of these samples increases, with increasing temperature and moisture content, and its behavior and order of magnitude are similar to that of carbon when compared on a moisture free basis. Due to the uncertainties of the chemical forms of the mineral matter and the water phase below room temperature, all the heat capacity data are analyzed on a dry mineral matter free basis.

  13. Heat capacities and thermodynamic functions for beryl, Be3Al2Si6O18, phenakite, Be2SiO4, euclase, BeAlSiO4(OH), bertrandite, Be4Si2O7(OH)2, and chrysoberyl, BeAl2O4.

    USGS Publications Warehouse

    Hemingway, B.S.; Barton, M.D.; Robie, R.A.; Haselton, H.T., Jr.

    1986-01-01

    The heat capacities of beryl, phenakite, euclase and bertrandite have been measured between approx 5 and 800 K by combined quasi-adiabatic cryogenic calorimetry and differential scanning calorimetry. The heat capacities of chrysoberyl have been measured from 340 to 800 K. The resulting data have been combined with solution and phase-equilibrium experimental data and simultaneously adjusted using the programme PHAS20 to provide an internally consistent set of thermodynamic properties for several important beryllium phases. The experimental heat capacities and tables of derived thermodynamic properties are presented.-J.A.Z.

  14. Knudsen heat capacity

    SciTech Connect

    Babac, Gulru; Reese, Jason M.

    2014-05-15

    We present a “Knudsen heat capacity” as a more appropriate and useful fluid property in micro/nanoscale gas systems than the constant pressure heat capacity. At these scales, different fluid processes come to the fore that are not normally observed at the macroscale. For thermodynamic analyses that include these Knudsen processes, using the Knudsen heat capacity can be more effective and physical. We calculate this heat capacity theoretically for non-ideal monatomic and diatomic gases, in particular, helium, nitrogen, and hydrogen. The quantum modification for para and ortho hydrogen is also considered. We numerically model the Knudsen heat capacity using molecular dynamics simulations for the considered gases, and compare these results with the theoretical ones.

  15. Heat capacities of crystalline tetraalkylammonium salts

    NASA Astrophysics Data System (ADS)

    Manin, N. G.; Kustov, A. V.; Antonova, O. A.

    2012-05-01

    The behavior of crystalline tetraalkylammonium salts at 290-350 K was studied by differential scanning calorimetry. For tetraethyl- and tetrabutylammonium bromides (Et4NBr and Bu4NBr), the experimental heat capacities agreed well with the literature values. For tetrahexyl-, tetraheptyl-, and tetraoctylam-monium bromides (Hex4NBr, Hep4NBr, and Oct4NBr), phase transitions were found between crystal modifications whose characteristic temperatures depended significantly on the size of the cation. Empirical equations for the temperature dependences of the heat capacities of the salts within the ranges of homogeneous equilibrium phases were derived.

  16. Heat capacities and thermodynamic properties of braunite (Mn7 SiO12) and rhodonite (MnSiO3)

    USGS Publications Warehouse

    Robie, R.A.; Huebner, J.S.; Hemingway, B.S.

    1995-01-01

    The heat capacities, C0P, of synthetic rhodonite and braunite have been measured by adiabatic calorimetry from 6 to ~350 K. The heat capacity of braunite was also measured to ~900 K by differential scanning calorimetry. Brunite exhibits a ??-peak in C0P in the temperature region 93.4-94.2 K. Rhodonite did not show the expected peak in C0P characteristic of the co-operative ordering of the Mn2+ spins at temperatures above 6 K. A revised petrogenetic grid for the system Mn-Si-O-C at 2000 bars is presented and is consistent with both thermochemical values and occurrence of natural assemblages. -from Authors

  17. Heat capacities and entropies of rhodochrosite (MnCO3) and siderite (FeCO3) between 5 and 600 K.

    USGS Publications Warehouse

    Robie, R.A.; Haselton, H.T., Jr.; Hemingway, B.S.

    1984-01-01

    The heat capacities of rhodochrosite, (Mn0.994Fe0.005Mg0.001)CO3, and siderite, 171(Fe0.956Mn0.042Mg0.002)CO3, were measured between 5 and 550 K by combined cryogenic-adiabatic and differential scanning calorimetry. These new data were used to reanalyse the thermodynamic properties of these phases.-J.A.Z.

  18. Temperature calibration of cryoscopic solutions used in the milk industry by adiabatic calorimetry

    NASA Astrophysics Data System (ADS)

    Méndez-Lango, E.; Lira-Cortes, L.; Quiñones-Ibarra, R.

    2013-09-01

    One method to detect extraneous water in milk is through cryoscopy. This method is used to measure the freezing point of milk. For calibration of a cryoscope there are is a set of standardized solution with known freezing points values. These values are related with the solute concentration, based in almost a century old data; it was no found recent results. It was found that reference solution are not certified in temperature: they do not have traceability to the temperature unit or standards. We prepared four solutions and measured them on a cryoscope and on an adiabatic calorimeter. It was found that results obtained with one technique dose not coincide with the other one.

  19. Heat Capacity Mapping Mission

    NASA Technical Reports Server (NTRS)

    Nilsson, C. S.; Andrews, J. C.; Scully-Power, P.; Ball, S.; Speechley, G.; Latham, A. R. (Principal Investigator)

    1980-01-01

    The Tasman Front was delineated by airborne expendable bathythermograph survey; and an Heat Capacity Mapping Mission (HCMM) IR image on the same day shows the same principal features as determined from ground-truth. It is clear that digital enhancement of HCMM images is necessary to map ocean surface temperatures and when done, the Tasman Front and other oceanographic features can be mapped by this method, even through considerable scattered cloud cover.

  20. Reversing and nonreversing heat capacity of poly(lactic acid) in the glass transition region by TMDSC

    SciTech Connect

    Pyda, Marek {nmn}; Wunderlich, Bernhard {nmn}

    2005-11-01

    A study of the glass transition of an amorphous and a semicrystalline poly(lactic acid) (PLA) is performed with adiabatic calorimetry, differential scanning calorimetry (DSC), and temperature-modulated DSC (TMDSC). The reversing, total, and nonreversing apparent heat capacities of samples with different contents of L- and D-lactic acid and with various thermal histories were evaluated. Different modes of TMDSC analyses of amorphous and semicrystalline PLA were compared to the total heat capacity from standard DSC. The enthalpy relaxation and the cold crystallization in the glass transition region are largely irreversible. The melting is largely irreversible, but a 100% reversing fraction is observed at low temperatures from 375 to 420 K, which becomes small inside the major melting peak at about 440 K. From the TMDSC of amorphous PLA, the combined information on endothermic and exothermic enthalpy relaxation and glass transition were deconvoluted into the reversing and nonreversing components. The glass transition temperature from the reversing heat capacity and the enthalpy relaxation peaks from the nonreversing component shift to higher temperature for increasingly annealed PLA. The relaxation times for aging decrease on cooling until the glass transition is reached and then increase. This behavior is linked to cooperativity. All quantitative thermal analyses are based on the heat capacity of the solid and liquid, evaluated earlier with the advanced thermal analysis system (ATHAS).

  1. Adiabatic calorimetry test of the reaction kinetics and self-heating model for 18650 Li-ion cells in various states of charge

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Chun; Wang, Yih-Wen; Shu, Chi-Min

    2016-06-01

    Use of adiabatic calorimetry to characterise thermal runaway of Li-ion cells is a crucial technique in battery safety testing. Various states of charge (SoC) of Li-ion cells were investigated to ascertain their thermal runaway features using a Vent Sizing Package 2 (VSP2) adiabatic calorimeter. To evaluate the thermal runaway characteristics, the temperature-pressure-time trajectories of commercial cylindrical cells were tested, and it was found that cells at a SoC of greater than 50% were subject to thermal explosion at elevated temperatures. Calorimetry data from various 18650 Li-ion cells with different SoC were used to calculate the thermal explosion energies and chemical kinetics; furthermore, a novel self-heating model based on a pseudo-zero-order reaction that follows the Arrhenius equation was found to be applicable for studying the exothermic reaction of a charged cell.

  2. Heat capacity, entropy of Ln2(MoO4)3 (Ln = La, Sm, and Gd), and the high-temperature enthalpy of Ln2(MoO4)3 (Ln = Eu, Dy, and Ho)

    NASA Astrophysics Data System (ADS)

    Lazarev, V. M.; Suponitskiy, Y. L.; Liashenko, S. E.

    2016-05-01

    The low-temperature heat capacity of Ln2(MoO4)3 (Ln = La, Sm, and Gd) is investigated by means of adiabatic calorimetry within the range of 60-300 K. The temperature dependences of the heat capacity are found and the values of the standard entropy are calculated, based on extrapolations to 0 K. Characteristic temperatures for molybdates are determined from the results of IR spectroscopic studies. The high-temperature enthalpy of Ln2(MoO4)3 (Ln = Eu, Dy, and Ho) is measured via high-temperature microcalorimetry, and the temperature dependence of heat capacity is calculated in the range of 298-1000 K. Since samarium and gadolinium molybdates are of the same structural type as terbium molybdate, we can estimate the anomaly of the heat capacity in the low-temperature region using the data for terbium molybdate and find the entropy of samarium and gadolinium molybdates.

  3. Heat capacity measurements - Progress in experimental techniques

    NASA Astrophysics Data System (ADS)

    Lakshmikumar, S. T.; Gopal, E. S. R.

    1981-11-01

    The heat capacity of a substance is related to the structure and constitution of the material and its measurement is a standard technique of physical investigation. In this review, the classical methods are first analyzed briefly and their recent extensions are summarized. The merits and demerits of these methods are pointed out. The newer techniques such as the a.c. method, the relaxation method, the pulse methods, the laser flash calorimetry and other methods developed to extend the heat capacity measurements to newer classes of materials and to extreme conditions of sample geometry, pressure and temperature are comprehensively reviewed. Examples of recent work and details of the experimental systems are provided for each method. The introduction of automation in control systems for the monitoring of the experiments and for data processing is also discussed. Two hundred and eight references and 18 figures are used to illustrate the various techniques.

  4. Heat capacities of kaolinite from 7 to 380 K and of DMSO- intercalated kaolinite from 20 to 310 K. The entropy of kaolinite Al2Si2O5(OH)4

    USGS Publications Warehouse

    Robie, R.A.; Hemingway, B.S.

    1991-01-01

    The heat capacities of kaolinite (7 to 380 K) and of dimethyl sulfoxide (DMSO) intercalated kaolinite (20 to 310 K) were measured by adiabatically shielded calorimetry. The third law entropy of kaolinite, S??298, is 200.9??0.5 J.mol-1.K-1. The "melting point' of the DMSO in the intercalate, 288.0??0.2 K, is 3.7 K lower than that of pure DMSO, 291.67 K. The heat capacity of DMSO in the intercalate above 290 K is approximately 5.2 J.mol-1.K-1 smaller than that of pure liquid DMSO at the same temperature. -Authors

  5. Low-temperature heat capacities of CaAl2SiO6 glass and pyroxene and thermal expansion of CaAl2SiO6 pyroxene.

    USGS Publications Warehouse

    Haselton, H.T., Jr.; Hemingway, B.S.; Robie, R.A.

    1984-01-01

    Low-T heat capacities (5-380 K) have been measured by adiabatic calorimetry for synthetic CaAl2SiO6 glass and pyroxene. High-T unit cell parameters were measured for CaAl2SiO6 pyroxene by means of a Nonius Guinier-Lenne powder camera in order to determine the mean coefficient of thermal expansion in the T range 25-1200oC. -J.A.Z.

  6. Heat capacities of synthetic hedenbergite, ferrobustamite and CaFeSi2O6 glass

    USGS Publications Warehouse

    Haselton, H.T., Jr.; Robie, R.A.; Hemingway, B.S.

    1987-01-01

    Heat capacities have been measured for synthetic hedenbergite (9-647 K), ferrobustamite (5-746 K) and CaFeSi2O6 glass (6-380 K) by low-temperature adiabatic and differential scanning calorimetry. The heat capacity of each of these structural forms of CaFeSiO6 exhibits anomalous behavior at low temperatures. The X-peak in the hedenbergite heat-capacity curve at 34.5 K is due to antiferromagnetic ordering of the Fe2+ ions. Ferrobustamite has a bump in its heat-capacity curve at temperatures less than 20 K, which could be due to weak cooperative magnetic ordering or to a Schottky anomaly. Surprisingly, a broad peak with a maximum at 68 K is present in the heat-capacity curve of the glass. If this maximum, which occurs at a higher temperature than in hedenbergite is caused by magnetic ordering, it could indicate that the range of distortions of the iron sites in the glass is quite small and that coupling between iron atoms is stronger in the glass than in the edge-shared octahedral chains of hedenbergite. The standard entropy change, So298.15 - So0, is 174.2 ?? 0.3, 180.5 ?? 0.3 and 185.7 ?? 0.4 J/mol??K for hedenbergite, ferrobustamite and CaFeSi2O6 glass, respectively. Ferrobustamite is partially disordered in Ca-Fe distribution at high temperatures, but the dependence of the configuratonal entropy on temperature cannot be evaluated due to a lack of information. At high temperatures (298-1600 K), the heat capacity of hedenbergite may be represented by the equation Cop(J/mol??K) = 3l0.46 + 0.01257T-2039.93T -1 2 - 1.84604?? l06T-2 and the heat capacity of ferrobustamite may be represented by Cop(J/mol??K) = 403.83-0.04444T+ 1.597?? 10-5T2-3757.3T -1 2. ?? 1987.

  7. Heat capacity of molten halides.

    PubMed

    Redkin, Alexander A; Zaikov, Yurii P; Korzun, Iraida V; Reznitskikh, Olga G; Yaroslavtseva, Tatiana V; Kumkov, Sergey I

    2015-01-15

    The heat capacities of molten salts are very important for their practical use. Experimental investigation of this property is challenging because of the high temperatures involved and the corrosive nature of these materials. It is preferable to combine experimental investigations with empirical relationships, which allows for the evaluation of the heat capacity of molten salt mixtures. The isobaric molar heat capacities of all molten alkali and alkaline-earth halides were found to be constant for each group of salts. The value depends on the number of atoms in the salt, and the molar heat capacity per atom is constant for all molten halide salts with the exception of the lithium halides. The molar heat capacities of molten halides do not change when the anions are changed. PMID:25530462

  8. Quartz: heat capacities from 340 to 1000 K and revised values for the thermodynamic properties.

    USGS Publications Warehouse

    Hemingway, B.S.

    1987-01-01

    New heat-capacity data for quartz have been measured over the T interval 340-1000 K by differential scanning calorimetry. The data were combined with recent heat-content and heat-capacity data to provide a significantly revised set of thermodynamic properties for alpha -quartz and to resolve the problem of disparate heat-content and heat-capacity data for alpha - and beta -quartz.-J.A.Z.

  9. Heat capacity and thermodynamic properties for coesite and jadeite, reexamination of the quartz-coesite equilibrium boundary

    USGS Publications Warehouse

    Hemingway, B.S.; Bohlen, S.R.; Hankins, W.B.; Westrum, E.F., Jr.; Kuskov, O.L.

    1998-01-01

    The heat capacities of synthetic coesite and jadeite were measured between about 15 and 850 K by adiabatic and differential scanning calorimetry. The experimental data were smoothed and estimates were made of heat capacities to 1800 K. The following equations represent our estimate of the heat capacities of coesite and jadeite between 298.15 and 1800 K: [see original article for formula]. Tables of thermodynamic values for coesite and jadeite to 1800 K are presented. The entropies of coesite and jadeite are 40.38 ?? 0.12 and 136.5 ?? 0.32 J/(mol.K), respectively, at 298.15 K. The entropy for coesite derived here confirms the value published earlier by Holm et al. (1967). We have derived an equation to describe the quartz-coesite boundary over the temperature range of 600 to 1500 K, P(GPa) = 1.76 + 0.001T(K). Our results are in agreement with the enthalpy of transition reported by Akaogi and Navrotsky (1984) and yield -907.6 ?? 1.4 kJ/mol for the enthalpy of formation of coesite from the elements at 298.15 K and 1 bar, in agreement with the value recommended by CODATA (Khodakovsky et al. 1995). Several sources of uncertainty remain unacceptably high, including: the heat capacities of coesite at temperatures above about 1000 K; the heat capacities and volumetric properties of ?? quartz at higher pressures and at temperatures above 844 K; the pressure corrections for the piston cylinder apparatus used to determine the quartz-coesite equilibrium boundary.

  10. Molar heat capacity and entropy of calcium metal

    USGS Publications Warehouse

    Hemingway, B.S.; Robie, R.A.; Chase, M.W.

    1997-01-01

    The heat capacity of calcium has been measured at 85 mean temperatures between T ??? 8 K and T ??? 369 K using an adiabatically-shielded calorimeter in an intermittent heating mode. At T = 298.15 K, the recommended values for the molar heat capacity, molar entropy, and molar enthalpy increment referred to T = 0 are (25.77 ?? 0.08) J??K-1??mol-1, (42.90 ?? 0.11) J??K-1??mol-1, and (5811 ?? 12) J??mol-1, respectively. The uncertainties are twice the standard deviation of the mean. ?? 1997 Academic Press Limited.

  11. Thermophysical properties of ilvaite CaFe22+Fe3+Si2O7O (OH); heat capacity from 7 to 920 K and thermal expansion between 298 and 856 K

    USGS Publications Warehouse

    Robie, R.A.; Evans, H.T., Jr.; Hemingway, B.S.

    1988-01-01

    The heat capacity of ilvaite from Seriphos, Greece was measured by adiabatic shield calorimetry (6.4 to 380.7 K) and by differential scanning calorimetry (340 to 950 K). The thermal expansion of ilvaite was also investigated, by X-ray methods, between 308 and 853 K. At 298.15 K the standard molar heat capacity and entropy for ilvaite are 298.9??0.6 and 292.3??0.6 J/(mol. K) respectively. Between 333 and 343 K ilvaite changes from monoclinic to orthorhombic. The antiferromagnetic transition is shown by a hump in Cp0with a Ne??el temperature of 121.9??0.5 K. A rounded hump in Cp0between 330 and 400 K may possibily arise from the thermally activated electron delocalization (hopping) known to take place in this temperature region. ?? 1988 Springer-Verlag.

  12. An automated flow calorimeter for heat capacity and enthalpy measurements at elevated temperatures and pressures

    SciTech Connect

    Yesavage, V.F.

    1990-08-31

    The need for highly accurate thermal property data for a broad range of new application fluids is well documented. To facilitate expansion of the current thermophysical database, an automated flow calorimeter was developed for the measurement of highly accurate isobaric heat capacities and enthalpies of fluids at elevated temperatures and pressures. The experimental technique utilizes traditional electrical power input, adiabatic flow calorimetry with a precision metering pump that eliminates the need for on-line flow rate monitoring. In addition, a complete automation system, greatly simplifies the operation of the apparatus and increases the rapidity of the measurement process. The range over which the instrument was tested, was 300--600 K and 0--12 Mpa, although the calorimeter should perform up to the original design goals of 700 K and 30 MPa. The new flow calorimeter was evaluated by measuring the mean, isobaric, specific heat capacities of liquid water and n-pentane. These experiments yielded an average deviation from the standard literature data of +0.02% and a total variation of 0.05%. Additional data analysis indicated that the overall measurement uncertainty was conservatively estimated as 0.2% with an anticipated precision of 0.1--0.15% at all operating conditions. 44 refs., 27 figs., 2 tabs.

  13. An automated flow calorimeter for heat capacity and enthalpy measurements at elevated temperatures and pressures

    NASA Astrophysics Data System (ADS)

    Yesavage, Victor F.

    1990-08-01

    The need for highly accurate thermal property data for a broad range of new application fluids is well documented. To facilitate expansion of the current thermophysical database, an automated flow calorimeter was developed for the measurement of highly accurate isobaric heat capacities and enthalpies of fluids at elevated temperatures and pressures. The experimental technique utilizes traditional electrical power input, adiabatic flow calorimetry with a precision metering pump that eliminates the need for on-line flow rate monitoring. In addition, a complete automation system greatly simplifies the operation of the apparatus and increases the rapidity of the measurement process. The range over which the instrument was tested was 300 to 600 K and 0 to 12 Mpa, although the calorimeter should perform up to the original design goals of 700 K and 30 MPa. The new flow calorimeter was evaluated by measuring the mean, isobaric, specific heat capacities of liquid water and n-pentane. These experiments yielded an average deviation from the standard literature data of +0.02 percent and a total variation of 0.05 percent. Additional data analysis indicated that the overall measurement uncertainty was conservatively estimated as 0.2 percent with an anticipated precision of 0.1 to 0.15 percent at all operating conditions.

  14. Thermodynamics of the lanthanide trifluorides. V. The heat capacities of dysprosium trifluoride, DyF3, and erbium trifluoride, ErF3, from 5 to 350 K

    NASA Astrophysics Data System (ADS)

    Flotow, Howard E.; O'Hare, P. A. G.

    1984-01-01

    The heat capacities of pure, well-characterized samples of DyF3 and ErF3 were measured by adiabatic calorimetry from 5 to 350 K. The heat capacities C○p, the entropies S°, the enthalpy increments H°(T)-H°(0), and the Planck functions -[G°(T)-H°(0)]/T are presented in tabular form at selected temperatures to 350 K. The values of the last three functions were adjusted for the removal of degeneracies associated with the magnetic ordering of DyF3 and ErF3 below 5 K. Also presented are recommended thermochemical functions at 298.15 K and tables of recommended high-temperature thermodynamic functions from 400 K to the melting temperatures. The excess heat capacities due to the internal electronic energy levels of Dy+3 in DyF3 and of Er+3 in ErF3 were calculated from calorimetric results. In the case of DyF3, the eight Kramer's doublets derived from spectroscopic measurements were used to calculate an excess heat capacity which is in good agreement with the calorimetric data.

  15. Heat capacities of liquid metals above 1500 K

    NASA Technical Reports Server (NTRS)

    Margrave, J. L.

    1982-01-01

    Heat capacity data are presented for liquid transition metals for temperatures close to the melting point and for 3000, 4000, and 5000 K. The data have been obtained by summarizing the results of levitation, exploding-wire, and drop-calorimetry measurements reported in the literature and by providing analytical estimates where experimental data are not available. The data given here are useful in assigning heat loads and predicting structure survival during extreme temperature excursions caused by nuclear, laser, or particle irradiations.

  16. The heat-capacity of ilmenite and phase equilibria in the system Fe-T-O

    USGS Publications Warehouse

    Anovitz, Lawrence M.; Treiman, A.H.; Essene, E.J.; Hemingway, B.S.; Westrum, E.F., Jr.; Wall, V.J.; Burriel, R.; Bohlen, S.R.

    1985-01-01

    Low temperature adiabatic calorimetry and high temperature differential scanning calorimetry have been used to measure the heat-capacity of ilmenite (FeTiO3) from 5 to 1000 K. These measurements yield S2980 = 108.9 J/(mol ?? K). Calculations from published experimental data on the reduction of ilmenite yield ??2980(I1) = -1153.9 kJ/(mol ?? K). These new data, combined with available experimental and thermodynamic data for other phases, have been used to calculate phase equilibria in the system Fe-Ti-O. Calculations for the subsystem Ti-O show that extremely low values of f{hook}O2 are necessary to stabilize TiO, the mineral hongquiite reported from the Tao district in China. This mineral may not be TiO, and it should be re-examined for substitution of other elements such as N or C. Consideration of solid-solution models for phases in the system Fe-Ti-O allows derivation of a new thermometer/oxybarometer for assemblages of ferropseudobrookite-pseudobrookitess and hematite-ilmenitess. Preliminary application of this new thermometer/oxybarometer to lunar and terrestrial lavas gives reasonable estimates of oxygen fugacities, but generally yields subsolidus temperatures, suggesting re-equilibration of one or more phases during cooling. ?? 1985.

  17. The heat-capacity of ilmenite and phase equilibria in the system Fe-T-O

    NASA Astrophysics Data System (ADS)

    Anovitz, Lawrence M.; Treiman, Allan H.; Essene, Eric J.; Hemingway, Bruce S.; Westrum, Edgar F., Jr.; Wall, Victor J.; Burriel, Ramón; Bohlen, Steven R.

    1985-10-01

    Low temperature adiabatic calorimetry and high temperature differential scanning calorimetry have been used to measure the heat-capacity of ilmenite (FeTiO 3) from 5 to 1000 K. These measurements yield S2980 = 108.9 J/( mol · K). Calculations from published experimental data on the reduction of ilmenite yield Δ2980( I1) = -1153.9 kJ/( mol · K). These new data, combined with available experimental and thermodynamic data for other phases, have been used to calculate phase equilibria in the system Fe-Ti-O. Calculations for the subsystem Ti-O show that extremely low values of ƒO 2 are necessary to stabilize TiO, the mineral hongquiite reported from the Tao district in China. This mineral may not be TiO, and it should be re-examined for substitution of other elements such as N or C. Consideration of solid-solution models for phases in the system Fe-Ti-O allows derivation of a new thermometer/oxybarometer for assemblages of ferropseudobrookite-pseudobrookite ss and hematite-ilmenite ss. Preliminary application of this new thermometer/oxybarometer to lunar and terrestrial lavas gives reasonable estimates of oxygen fugacities, but generally yields subsolidus temperatures, suggesting re-equilibration of one or more phases during cooling.

  18. Heat capacity, enthalpy and entropy of ternary bismuth tantalum oxides

    SciTech Connect

    Leitner, J.; Jakes, V.; Sofer, Z.; Sedmidubsky, D.; Ruzicka, K.; Svoboda, P.

    2011-02-15

    Heat capacity and enthalpy increments of ternary bismuth tantalum oxides Bi{sub 4}Ta{sub 2}O{sub 11}, Bi{sub 7}Ta{sub 3}O{sub 18} and Bi{sub 3}TaO{sub 7} were measured by the relaxation time method (2-280 K), DSC (265-353 K) and drop calorimetry (622-1322 K). Temperature dependencies of the molar heat capacity in the form C{sub pm}=445.8+0.005451T-7.489x10{sup 6}/T{sup 2} J K{sup -1} mol{sup -1}, C{sub pm}=699.0+0.05276T-9.956x10{sup 6}/T{sup 2} J K{sup -1} mol{sup -1} and C{sub pm}=251.6+0.06705T-3.237x10{sup 6}/T{sup 2} J K{sup -1} mol{sup -1} for Bi{sub 3}TaO{sub 7}, Bi{sub 4}Ta{sub 2}O{sub 11} and for Bi{sub 7}Ta{sub 3}O{sub 18}, respectively, were derived by the least-squares method from the experimental data. The molar entropies at 298.15 K, S{sup o}{sub m}(298.15 K)=449.6{+-}2.3 J K{sup -1} mol{sup -1} for Bi{sub 4}Ta{sub 2}O{sub 11}, S{sup o}{sub m}(298.15 K)=743.0{+-}3.8 J K{sup -1} mol{sup -1} for Bi{sub 7}Ta{sub 3}O{sub 18} and S{sup o}{sub m}(298.15 K)=304.3{+-}1.6 J K{sup -1} mol{sup -1} for Bi{sub 3}TaO{sub 7}, were evaluated from the low-temperature heat capacity measurements. -- Graphical Abstract: Temperature dependence of {Delta}{sub ox}C{sub pm} for bismuth tantalum mixed oxides. Display Omitted Research highlights: > Heat capacity, enthalpy and entropy of ternary bismuth tantalum oxides Bi{sub 4}Ta{sub 2}O{sub 11}, Bi{sub 7}Ta{sub 3}O{sub 18} and Bi{sub 3}TaO{sub 7}. > Heat capacity by DSC calorimetry and heat-pulsed calorimetry. > Enthalpy increments by drop calorimetry. > Einstein-Debye model for low-temperature dependence of the heat capacity. > Application of Neumann-Kopp rule.

  19. Excess heat capacity in liquid binary alkali-fluoride mixtures.

    PubMed

    Beilmann, M; Beneš, O; Capelli, E; Reuscher, V; Konings, R J M; Fanghänel, Th

    2013-03-01

    Using drop calorimetry, we measured enthalpy increments of the LiF-KF, LiF-RbF, and LiF-CsF binary systems at temperatures above the melting point. Ten samples with different compositions (four compositions for LiF-KF, one composition for LiF-RbF, and five compositions for LiF-CsF) were prepared and measured between 884 K and 1382 K. To protect the calorimeter from corrosive fluoride vapor at high temperature, an encapsulating technique developed for this purpose was used. The samples were filled in nickel containers that were sealed by laser welding and afterward used for the measurements. From the obtained results, we derived the molar heat capacity functions of the respective samples. The heat capacities of the samples, having different compositions of the same binary system, were compared with the values for ideal behavior and the excess heat capacity function was determined for the entire composition range of the liquid solution. It was found that the excess heat capacities clearly depend on the cation radius and increase in the following order: LiF-NaF < LiF-KF < LiF-RbF < LiF-CsF. PMID:23421448

  20. The heat capacity mapping mission

    NASA Technical Reports Server (NTRS)

    Short, N. M.

    1981-01-01

    The first in a series of low cost Atmospheric Explorer Satellites, the Heat Capacity Mapping Mission (HCMM) was designed to evaluate the utility of thermal inertial and other thermal and reflectance data for: (1) discriminating bedrock and unconsolidated regolith types; (2) mapping soil moisture; (3) measuring plant canopy temperatures; (4) examining thermal circulation in large bodies of water; and (5) monitoring urban heat islands. Final reports from the HCMM investigator's program are beginning to define the utility of day/the night thermal data. Under favorable circumstances, some major rock types can be identified, soil moisture in extensive agricultural and alluvial terrains can be detected and at least semiqualitatively assessed; and circulation of currents in large bodies of water can be followed by noting thermal patterns.

  1. Change in the Specific Heat Capacity of Parenchymal Tissues of Apples due to Dehydration

    NASA Astrophysics Data System (ADS)

    Mikhailik, V. A.; Dmitrenko, N. V.; Snezhkin, Yu. F.

    2014-01-01

    We present the results of measurements of the heat capacity of parenchymal tissues of apples by the differential scanning calorimetry method. An analytical dependence of the specific heat capacity of these tissues on their temperature (10-90°C) and moisture (6.8-90%) is proposed. We have considered the boundary conditions under which it is possible to calculate the heat capacity of moist parenchymal tissues of apples containing simultaneously free and bound water by an additive model. Reliable values of the heat capacity of tissues containing only bound water can be obtained only experimentally. In parenchymal tissues of apples with a low moisture content (0.6-0.43%) in the positive temperature range, a stepwise change in the heat capacity has been revealed.

  2. Heat Capacity Identification Method Using MT System

    NASA Astrophysics Data System (ADS)

    Suzuki, Arata; Sugimoto, Kenji

    This paper proposes a heat capacity identification method for cooking household appliances. Cooking household appliances select a cooking flow according to a cooking object capacity, hence the heat capacity identification is a very important function. However, a conventional heat capacity identification method has been based on one variable using “if-then rules”, hence it gives a low accuracy. This paper proposes a new heat capacity identification method that uses Mahalanobis-Taguchi System which is similar to discriminant analysis, and the effectiveness of this method is confirmed by the experiment.

  3. Low temperature heat capacity of PuPO 4

    NASA Astrophysics Data System (ADS)

    Thiriet, C.; Konings, R. J. M.; Wastin, F.

    2005-09-01

    PuPO 4 was prepared successfully by coprecipitation and its heat capacity measured between 5 K and 300 K by a hybrid adiabatic relaxation calorimeter. The standard entropy S0 (298.15 K) of PuPO 4 was derived and a semi-empirical method was used to describe the total entropy as the sum of the lattice entropy Slat and the excess entropy Sexs as verified for the iso-electronic lanthanide orthophosphates. Thus the standard entropies of some actinide (III) orthophosphates were estimated.

  4. The decarbonation and heat capacity of ZnCO3

    USGS Publications Warehouse

    Haselton, H.T.; Goldsmith, J.R.

    1987-01-01

    The decarbonation curve for ZnCO3 has been determined in the pressure range 3-20 kbar by using a combination of cold-seal vessels and piston-cylinder apparatus with NaCl assemblies. Heat capacities for both synthetic and natural ZnCO3 samples were measured by differential scanning calorimetry at temperatures ranging from 340 to 497 K. The results of these experiments indicate that the enthalpy of formation for smithsonite, ??Hf(1,298.15), is approximately -817. kJ/mol. which is about 4 kJ more negative than most tabulated values. ?? 1987.

  5. Low-temperature heat capacities of confined liquid benzene, implying the behavior of ordinary bulk liquids.

    PubMed

    Nagoe, A; Oguni, M; Fujimori, H

    2015-11-18

    Isobaric heat capacities C p of benzene confined in silica MCM-41 mesopores with average diameters equal to and smaller than 2.9 nm were measured by precise adiabatic calorimetry. The confined benzene samples revealed no thermal anomaly due to crystallization/fusion and vitrified at low temperatures. The C p curves displayed a hump and a considerably quick decrease on the low-temperature side of the hump as the pore diameter increased. The enthalpy-relaxation effects observed on intermittent heating showed that the anomaly of the C p hump and quick decrease is not assigned to a glass transition. The bend in the temperature dependence of density reported previously was interpreted as corresponding to the quick decrease in C p . We concluded that the anomalous C p and density behaviors originated from the ordering/excitation in the configurational state, close to the ground state, of confined molecular aggregate and proposed a scenario that explains the general C p curves of ordinary bulk supercooled liquids in equilibrium at low temperatures below the glass-transition temperatures. PMID:26490197

  6. Low-temperature heat capacities of confined liquid benzene, implying the behavior of ordinary bulk liquids

    NASA Astrophysics Data System (ADS)

    Nagoe, A.; Oguni, M.; Fujimori, H.

    2015-11-01

    Isobaric heat capacities C p of benzene confined in silica MCM-41 mesopores with average diameters equal to and smaller than 2.9 nm were measured by precise adiabatic calorimetry. The confined benzene samples revealed no thermal anomaly due to crystallization/fusion and vitrified at low temperatures. The C p curves displayed a hump and a considerably quick decrease on the low-temperature side of the hump as the pore diameter increased. The enthalpy-relaxation effects observed on intermittent heating showed that the anomaly of the C p hump and quick decrease is not assigned to a glass transition. The bend in the temperature dependence of density reported previously was interpreted as corresponding to the quick decrease in C p . We concluded that the anomalous C p and density behaviors originated from the ordering/excitation in the configurational state, close to the ground state, of confined molecular aggregate and proposed a scenario that explains the general C p curves of ordinary bulk supercooled liquids in equilibrium at low temperatures below the glass-transition temperatures.

  7. The Heat Capacity of Ideal Gases

    ERIC Educational Resources Information Center

    Scott, Robert L.

    2006-01-01

    The heat capacity of an ideal gas has been shown to be calculable directly by statistical mechanics if the energies of the quantum states are known. However, unless one makes careful calculations, it is not easy for a student to understand the qualitative results. Why there are maxima (and occasionally minima) in heat capacity-temperature curves…

  8. Heat capacity of alkanolamine aqueous solutions

    SciTech Connect

    Chiu, L.F.; Li, M.H.

    1999-12-01

    Heat capacities of monoethanoloamine, diglycolamine, diethanolamine, di-w propanolamine, triethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-l-propanol, and 2-piperidineethanol aqueous solutions were measured from 30 to 80 C with a differential scanning calorimeter (DSC). The mole fractions of alkanolamines studied are 0.2, 0.4, 0.6, and 0.8. Heat capacities of N-methyldiethanolamine aqueous solutions have been measured to verify the validity of C{sub p} measurements for alkanolamine aqueous solutions. The estimated uncertainty of the measured heat capacities is {plus{underscore}minus}3%, including the effect of up to 5% impurities in a substance. An excess molar heat capacity expression using the Redlich-Kister equation for the composition dependence is used to represent the measured C{sub p} of alkanolamine aqueous solutions. For a total of 374 data points, the calculation results for eight alkanolamine solutions give the overall average absolute deviations of 11.9% and 0.29% for the excess molar heat capacity and the heat capacity, respectively. The heat capacities presented in this study are, in general, of sufficient accuracy for most engineering-design calculations. Solutions of alkanolamines are industrially important mixtures used in the natural gas industry, oil refineries, petroleum chemical plants, and synthetic ammonia plants for the removal of acidic components such as CO{sub 2} and H{sub 2}S from gas streams.

  9. Effect of water on the heat capacity of polymerized aluminosilicate glasses and melts

    NASA Astrophysics Data System (ADS)

    Bouhifd, M. Ali; Whittington, Alan; Roux, Jacques; Richet, Pascal

    2006-02-01

    The effect of water on heat capacity has been determined for four series of hydrated synthetic aluminosilicate glasses and supercooled liquids close to albite, phonolite, trachyte, and leucogranite compositions. Heat capacities were measured at atmospheric pressure by differential scanning calorimetry for water contents between 0 and 4.9 wt % from 300 K to about 100 K above the glass transition temperature ( Tg). The partial molar heat capacity of water in polymerized aluminosilicate glasses, which can be considered as independent of composition, is =-122.319+341.631×10-3T+63.4426×105/T2 (J/mol K). In liquids containing at least 1 wt % H 2O, the partial molar heat capacity of water is about 85 J/mol K. From speciation data, the effects of water as hydroxyl groups and as molecular water have tentatively been estimated, with partial molar heat capacities of 153 ± 18 and 41 ± 14 J/mol K, respectively. In all cases, water strongly increases the configurational heat capacity at Tg and exerts a marked depressing effect on Tg, in close agreement with the results of viscosity experiments on the same series of glasses. Consistent with the Adam and Gibbs theory of relaxation processes, the departure of the viscosity of hydrous melts from Arrhenian variations correlates with the magnitude of configurational heat capacities.

  10. High-temperature heat capacity of YFe3(BO3)4

    NASA Astrophysics Data System (ADS)

    Denisov, V. M.; Denisova, L. T.; Gudim, I. A.; Temerov, V. L.; Volkov, N. V.; Patrin, G. S.; Chumilina, L. G.

    2014-02-01

    The molar heat capacity of YFe3(BO3)4 has been measured using differential scanning calorimetry in the temperature range 339-1086 K. It has been found that the dependence C p = f( T) exhibits an extremum at a temperature of 401 K due to the structural transition.

  11. Low temperature heat capacity of water clusters

    NASA Astrophysics Data System (ADS)

    Chen, Hongshan; Hansen, Klavs

    2014-08-01

    Geometry optimization and vibrational frequency calculation are carried out at the MP2/6-31G(d,p) level for 35 low-energy isomers of (H2O)n clusters in the size range n = 6-21. The heat capacities of the clusters are calculated using quantum statistical theories based on the harmonic approximation. The specific heat capacity increases with the cluster size but the difference diminishes gradually with increasing size. The heat capacities divided by the number of intermolecular vibrational modes are very close for all the clusters. The overall picture of the heat capacity of the clusters is bulk-like and it agrees well with the experimental results of size-selected clusters.

  12. The heat capacity of titanium disilicide

    NASA Technical Reports Server (NTRS)

    Sylla, W. K.; Stillman, S. E.; Sabella, M. S.; Cotts, E. J.

    1994-01-01

    The heat capacity of TiSi2 has been measured in the temperature range 105-500 K. The heat capacity of TiSi2 varies monotonically between temperatures of 100 and 500 K with a reference value of 22.0 +/- 0.2 J/g atom K at 298.15 K. Based upon our heat capacity data, the standard molar entropy of TiSi2 at 298.15 K estimated to be 22.2 +/- 0.8 J/g atom K. Our data support estimates of the higher temperature heat capacity of TiSi2 based upon previously measured heat capacities of different, but similar, substances. A number of TiSi2 samples were prepared by rapidly quenching (greater than 10(exp 5) K/s) from the melt. The structure and the measured heat capacity of these samples were similar to those of well annealed samples, underscoring the thermal stability of this material.

  13. Heat capacity and thermodynamic properties of HoMnO3 in the range of 364-1046 K

    NASA Astrophysics Data System (ADS)

    Denisova, L. T.; Chumilina, L. G.; Shaikhutdinov, K. A.; Patrin, G. S.; Denisov, V. M.

    2016-03-01

    The temperature dependence of the molar heat capacity of HoMnO3 has been measured by differential scanning calorimetry. The experimental data have been used to calculate the thermodynamic properties of the oxide compound (changes in the enthalpy H°( T)- H°(364 K), entropy S°( T)- S°(364 K), and reduced Gibbs energy Φ°( T)). The data on the heat capacity of HoMnO3 have been generalized in the range of 40-1000 K.

  14. Classical fluids of negative heat capacity

    SciTech Connect

    Landsberg, P.T.; Woodard, R.P.

    1992-06-01

    It is shown that new parameters X can be defined such that the heat capacity C{sub X} {equivalent_to} T({partial_derivative}S/{partial_derivative}T)X is negative, even when the canonical ensemble (i.e. at fixed T = ({partial_derivative}U/{partial_derivative}S) and Y {ne} X) is stable. As examples we treat black body radiation and general gas systems with nonsingular {kappa}{sub T}. For the case of a simple ideal gas we even exhibit an apparatus which enforces a constraint X(p,V) = const. that makes C{sub X} < 0. Since it is possible to invent constraints for which canonically stable systems have negative heat capacity we speculate that it may also be possible to infer the statistical mechanics of canonically unstable systems - for which even the traditional heat capacities are negative - by imposing constraints that stabilize the associated, inoncanonical ensembles.

  15. Classical fluids of negative heat capacity

    SciTech Connect

    Landsberg, P.T. . Faculty of Mathematical Studies); Woodard, R.P. . Dept. of Physics)

    1992-06-01

    It is shown that new parameters X can be defined such that the heat capacity C{sub X} {equivalent to} T({partial derivative}S/{partial derivative}T)X is negative, even when the canonical ensemble (i.e. at fixed T = ({partial derivative}U/{partial derivative}S) and Y {ne} X) is stable. As examples we treat black body radiation and general gas systems with nonsingular {kappa}{sub T}. For the case of a simple ideal gas we even exhibit an apparatus which enforces a constraint X(p,V) = const. that makes C{sub X} < 0. Since it is possible to invent constraints for which canonically stable systems have negative heat capacity we speculate that it may also be possible to infer the statistical mechanics of canonically unstable systems - for which even the traditional heat capacities are negative - by imposing constraints that stabilize the associated, inoncanonical ensembles.

  16. Meteorite heat capacities: Results to date

    NASA Astrophysics Data System (ADS)

    Consolmagno, G.; Macke, R.; Britt, D.

    2014-07-01

    Heat capacity is an essential thermal property for modeling asteroid internal metamorphism or differentiation, and dynamical effects like YORP or Yarkovsky perturbations. We have developed a rapid, inexpensive, and non-destructive method for measuring the heat capacity of meteorites at low temperature [1]. A sample is introduced into a dewar of liquid nitrogen and an electronic scale measures the amount of nitrogen boiled away as the sample is cooled from the room temperature to the liquid nitrogen temperature; given the heat of vaporization of liquid nitrogen, one can then calculate the heat lost from the sample during the cooling process. Note that heat capacity in this temperature range is a strong function of temperature, but this functional relation is essentially the same for all materials; the values we determine are equivalent to the heat capacity of the sample at 175 K. To correct for systematic errors, samples of laboratory-grade quartz are measured along with the meteorite samples. To date, more than 70 samples of more than 50 different meteorites have been measured in this way, including ordinary chondrites [1], irons [2], basaltic achondrites [3], and a limited number of carbonaceous chondrites [1]. In general, one can draw a number of important conclusions from these results. First, the heat capacity of a meteorite is a function of its mineral composition, independent of shock, metamorphism, or other physical state. Second, given this relation, heat capacity can be strongly altered by terrestrial weathering. Third, the measurement of heat capacity in small (less than 1 g) samples as done typically by commercial systems runs a serious risk of giving misleading results for samples that are heterogeneous on scales of tens of grams or more. Finally, we demonstrate that heat capacity is a useful tool for determining and classifying a sample, especially if used in conjunction with other intrinsic variables such as grain density and magnetic susceptibility

  17. Heat capacity and sound velocities of low dimensional Fermi gases

    NASA Astrophysics Data System (ADS)

    Salas, P.; Solis, M. A.

    2014-03-01

    We report the heat capacity ratio and sound velocities for an interactionless Fermi gas immersed in periodic structures such as penetrable multilayers or multitubes created by one (planes) or two perpendicular (tubes) external Dirac comb potentials. The isobaric specific heat of the fermion gas presents the dimensional crossover previously observed in the isochoric specific heat - from 3D to 2D or to 1D -. The quotient between the two quantities has a prominent bump related to the confinement, and as the temperature increases, it goes towards the monoatomic classical gas value 5/3. We present the isothermal and the adiabatic sound velocities of the fermion gas which show anomalous behavior at temperatures below TF due to the dimensionality of the system, while at higher temperatures again we recover the behavior of a classical Fermi gas. Furthermore, as the temperature goes to zero the sound velocity has a finite value, as expected.

  18. Heat capacity mapping radiometer for AEM spacecraft

    NASA Technical Reports Server (NTRS)

    Sonnek, G. E.

    1977-01-01

    The operation, maintenance, and integration of the applications explorer mission heat capacity mapping radiometer is illustrated in block diagrams and detail schematics of circuit functions. Data format and logic timing diagrams are included along with radiometric and electronic calibration data. Mechanical and electrical configuration is presented to provide interface details for integration of the HCMR instrument to AEM spacecraft.

  19. Estimating heat capacity and heat content of rocks

    USGS Publications Warehouse

    Robertson, Eugene C.; Hemingway, Bruch S.

    1995-01-01

    Our measured heat-capacity values for rocks and other measurements of heat capacity or heat content of rocks found in the literature have been compared with estimated rock heat capacities calculated from the summation of heat capacities of both minerals and oxide components. The validity of calculating the heat content or heat capacity of rocks to better than about ± 3% from its mineral or chemical composition is well demonstrated by the data presented here.

  20. A Study of Specific Heat Capacity Functions of Polyvinyl Alcohol- Cassava Starch Blends

    NASA Astrophysics Data System (ADS)

    Sin, Lee Tin; Rahman, W. A. W. A.; Rahmat, A. R.; Morad, N. A.; Salleh, M. S. N.

    2010-03-01

    The specific heat capacity ( C sp) of polyvinyl alcohol (PVOH) blends with cassava starch (CSS) was studied by the differential scanning calorimetry method. Specimens of PVOH-CSS blends: PPV37 (70 mass% CSS) and PPV46 (60 mass% CSS) were prepared by a melt blending method with glycerol added as a plasticizer. The results showed that the specific heat capacity of PPV37 and PPV46 at temperatures from 330 K to 530 K increased from (2.963 to 14.995) J· g-1 · K-1 and (2.517 to 14.727) J · g-1· K-1, respectively. The specific heat capacity of PVOH-CSS depends on the amount of starch. The specific heat capacity of the specimens can be approximated by polynomial equations with a curve fitting regression > 0.992. For instance, the specific heat capacity (in J · g-1 · K-1) of PPV37 can be expressed by C sp = -17.824 + 0.063 T and PPV46 by C sp = -18.047 + 0.061 T, where T is the temperature (in K).

  1. Heat capacity and phase equilibria of almandine, Fe 3Al 2Si 3O 12

    NASA Astrophysics Data System (ADS)

    Anovitz, L. M.; Essene, E. J.; Metz, G. W.; Bohlen, S. R.; Westrum, E. F., Jr.; Hemingway, B. S.

    1993-09-01

    The heat capacity of a synthetic almandine, Fe 3Al 2Si 3O 12, was measured from 6 to 350 K using equilibrium, intermittent-heating quasi-adiabatic calorimetry and from 420 to 1000 K using differential scanning calorimetry. These measurements yield Cp298 = 342.80 ± 1.4 J/mol · K and S298o = 342.60 J/mol · K. Mössbauer characterizations show the almandine to contain less than 2 ± 1% of the total iron as Fe 3+. X-ray diffraction studies of this synthetic almandine yield a = 11.521 ± 0.001 Å and V298o = 115.11 +- 0.01 cm 3/mol, somewhat smaller than previously reported. The low-temperature Cp data indicate a lambda transition at 8.7 K related to an antiferromagnetic-paramagnetic transition with TN = 7.5 K. Modeling of the lattice contribution to the total entropy suggests the presence of entropy in excess of that attributable to the effects of lattice vibrations and the magnetic transition. This probably arises from a low-temperature electronic transition (Schottky contribution). Combination of the Cp data with existing thermodynamic and phase equilibrium data on almandine yields ΔGf,298 o = -4938.3 kJ/mol and ΔHf,298 o= - 5261.3 kJ/mol for almandine when calculated from the elements. The equilibrium almandine = hercynite + fayalite + quartz limits the upper T/P for almandine and is metastably located at ca. 570°C at P = 1 bar, with a dP/dT of +17 bars/°C. This agrees well with reversed experiments on almandine stability when they are corrected for magnetite and hercynite solid-solutions. In ‖ O2- T space, almandine oxidizes near QFM by the reactions almandine + O2 = magnetite + sillimanite + quartzandalmandine + 02 = hercynite + magnetite + quartz. With suitable correction for reduced activities of solid phases, these equilibria provide useful oxygen barometers for medium- to high-grade metamorphic rocks.

  2. Heat capacity and phase equilibria of almandine, Fe3Al2Si3O12

    USGS Publications Warehouse

    Anovitz, Lawrence M.; Essene, E.J.; Metz, G.W.; Bohlen, S.R.; Westrum, E.F., Jr.; Hemingway, B.S.

    1993-01-01

    The heat capacity of a synthetic almandine, Fe3Al2Si3O12, was measured from 6 to 350 K using equilibrium, intermittent-heating quasi-adiabatic calorimetry and from 420 to 1000 K using differential scanning calorimetry. These measurements yield Cp298 = 342.80 ?? 1.4 J/mol ?? K and S298o = 342.60 J/mol ?? K. Mo??ssbauer characterizations show the almandine to contain less than 2 ?? 1% of the total iron as Fe3+. X-ray diffraction studies of this synthetic almandine yield a = 11.521 ?? 0.001 A?? and V298o = 115.11 +- 0.01 cm3/mol, somewhat smaller than previously reported. The low-temperature Cp data indicate a lambda transition at 8.7 K related to an antiferromagnetic-paramagnetic transition with TN = 7.5 K. Modeling of the lattice contribution to the total entropy suggests the presence of entropy in excess of that attributable to the effects of lattice vibrations and the magnetic transition. This probably arises from a low-temperature electronic transition (Schottky contribution). Combination of the Cp data with existing thermodynamic and phase equilibrium data on almandine yields ??Gf,298o = -4938.3 kJ/mol and ??Hf,298o= -5261.3 kJ/mol for almandine when calculated from the elements. The equilibrium almandine = hercynite + fayalite + quartz limits the upper T P for almandine and is metastably located at ca. 570??C at P = 1 bar, with a dP dT of +17 bars/??C. This agrees well with reversed experiments on almandine stability when they are corrected for magnetite and hercynite solid-solutions. In {norm of matrix}O2-T space, almandine oxidizes near QFM by the reactions almandine + O2 = magnetite + sillimanite + quartz and almandine + 02 = hercynite + magnetite + quartz. With suitable correction for reduced activities of solid phases, these equilibria provide useful oxygen barometers for medium- to high-grade metamorphic rocks. ?? 1993.

  3. Heat capacity and phase equilibria of almandine, Fe[sub 3]Al[sub 2]Si[sub 3]O[sub 12

    SciTech Connect

    Anovitz, L.M. ); Essene, E.J.; Metz, G.W.; Westrum, E.F. Jr. ); Bohlen, S.R. ); Hemingway, B.S. )

    1993-09-01

    The heat capacity of a synthetic almandine, Fe[sub 3]Al[sub 2]Si[sub 3]O[sub 12], was measured from 6 to 350 K using equilibrium, intermittent-heating quasi-adiabatic calorimetry and from 420 to 1000 K using differential scanning calorimetry. These measurements yield Cp[sub 298] = 342.80 [+-] 1.4 J/mol[center dot]K and S[degrees][sub 298] = 342.60 J/mol[center dot]K. Moessbauer characterizations show the almandine to contain less than 2 [+-] 1% of the total iron as Fe[sup 3+]. X-ray diffraction studies of this synthetic almandine yield a = 11.521 [+-] 0.001 [angstrom] and V[degrees][sub 298] = 115.11 [+-] 0.01 cm[sup 3]/mol, somewhat smaller than previously reported. The low-temperature Cp data indicate a lambda transition at 8.7 K related to an antiferromagnetic-paramagnetic transition with T[sub N] = 7.5 K. Modeling of the lattice contribution to the total entropy suggests the presence of entropy in excess of that attributable to the effects of lattice vibrations and the magnetic transition. This probably arises from a low-temperature electronic transition (Schottky contribution).

  4. A calorimetric investigation of spessartine: Vibrational and magnetic heat capacity

    NASA Astrophysics Data System (ADS)

    Dachs, Edgar; Geiger, Charles A.; Withers, Anthony C.; Essene, Eric J.

    2009-06-01

    The heat capacity ( Cp) of two synthetic spessartine samples (Sps) was measured on 20-30 mg-size samples in the temperature range 2-864 K by relaxation calorimetry (RC) and differential scanning calorimetry (DSC). The polycrystalline spessartine samples were synthesized in two different laboratories at high pressures and temperatures from glass and oxide-mixture starting materials and characterized by X-ray powder diffraction and electron-microprobe analysis. The low-temperature heat capacity data show a prominent lambda transition with a peak at 6.2 K, which is interpreted to be the result of a paramagnetic-antiferromagnetic phase transition. The DSC data around ambient T agree excellently with the RC data and can be represented by the Cp polynomial for T > 250 K: CpSps=610-3060·T-0.5-1.45·107·T-2+1.82·109·T-3. Integration of the low temperature Cp data yields a calorimetric standard entropy for the two different samples of So = 334.6 ± 2.7 J/mol · K and 336.0 ± 2.7 J/mol · K. The preferred standard third-law entropy for spessartine is So = 335.3 ± 3.8 J/mol · K, which is the mean value from the two separate determinations. The lattice (vibrational) heat capacity of spessartine was calculated using the single-parameter phonon dispersion model of Komada and Westrum. The lattice entropy at 298.15 K is Svib298.15=297.7J/mol·K, which represents 89% of the calorimetric entropy. The magnetic heat capacity and entropy of spessartine, Smag, at 298.15 K were also calculated. The Smag of the two samples is 38.7 and 37.4 J/mol · K, which is 87% and 83% of the maximum possible magnetic entropy given by 3Rln6 = 44.7 J/mol · K. Published model-dependent lattice-dynamic calculations of Svib298.15 are analyzed and compared to the experimental data. Using the calorimetrically determined So and the Cp polynomial for spessartine, together with high P- T experimental phase-equilibrium data on Mn 2+-Mg partitioning between garnet and olivine, allows calculation of the

  5. Heat capacity and entropy at the temperatures 5 K to 720 K and thermal expansion from the temperatures 298 K to 573 K of synthetic enargite (Cu3AsS4)

    USGS Publications Warehouse

    Seal, R.R., II; Robie, R.A.; Hemingway, B.S.; Evans, H.T., Jr.

    1996-01-01

    The heat capacity of synthetic Cu3AsS4 (enargite) was measured by quasi-adiabatic calorimetry from the temperatures 5 K to 355 K and by differential scanning calorimetry from T = 339 K to T = 720 K. Heat-capacity anomalies were observed at T = (58.5 ?? 0.5) K (??trsHom = 1.4??R??K; ??trsSom = 0.02??R) and at T = (66.5 ?? 0.5) K (??trsHom = 4.6??R??K; ??trsSom = 0.08??R), where R = 8.31451 J??K-1??mol-1. The causes of the anomalies are unknown. At T = 298.15 K, Cop,m and Som(T) are (190.4 ?? 0.2) J??K-1??mol-1 and (257.6 ?? 0.6) J??K-1??mol-1, respectively. The superambient heat capacities are described from T = 298.15 K to T = 944 K by the least-squares regression equation: Cop,m/(J??K-1??mol-1) = (196.7 ?? 1.2) + (0.0499 ?? 0.0016)??(T/K) -(1918 000 ?? 84 000)??(T/K)-2. The thermal expansion of synthetic enargite was measured from T = 298.15 K to T = 573 K by powder X-ray diffraction. The thermal expansion of the unit-cell volume (Z = 2) is described from T = 298.15 K to T = 573 K by the least-squares equation: V/pm3 = 106??(288.2 ?? 0.2) + 104??(1.49 ?? 0.04)??(T/K). ?? 1996 Academic Press Limited.

  6. Heat capacity and thermodynamic functions of thulium tellurites in the range of 298.15-673 K

    NASA Astrophysics Data System (ADS)

    Rustembekov, K. T.; Dyusekeeva, A. T.; Bekturganova, A. Zh.; Kasenov, B. K.; Makhatova, N. A.; Fomin, V. N.

    2016-02-01

    The isobaric heat capacity of double thulium tellurites is studied via dynamic calorimetry in the range of 298.15-673 K. It is used as the basis for deriving the equation C p o ˜ f( T) and determining the thermodynamic functions. Dependences C p o ˜ f( T) are found to have second-order phase λ-transitions.

  7. The Solid-State Heat-Capacity Laser

    SciTech Connect

    Rotter, M D; Dane, C B; Gonzales, S A; Merrill, R D; Mitchell, S C; Parks, C W; Yamamoto, R M

    2003-12-08

    Heat-capacity operation of a laser is a novel method by which high average powers can be generated. In this paper, we present the principles behind heat-capacity operation, in addition to describing the results of recent experiments.

  8. Heat Capacity Mapping Mission (HCMM) Notification Efforts

    NASA Technical Reports Server (NTRS)

    1980-01-01

    To encourage wide use of the Heat Capacity Mapping Mission (HCMM) data, especially among the scientific community, special notifications were prepared to inform them about the data's availability, its form, and the procedures for obtaining them. To achieve the widest distribution to the primary audiences of interest, mailings were made to scientists associated with the OSTA Resource Observation Division programs and to scientific and professional societies and journals. Accompanying the notifications to the societies and journals were samples of the HCMM imagery and a description of the image's predominant characteristics. A follow-up survey was completed to determine the effectiveness of the HCMM notifications.

  9. Hybrid Heat Capacity - Moving Slab Laser Concept

    SciTech Connect

    Stappaerts, E A

    2002-04-01

    A hybrid configuration of a heat capacity laser (HCL) and a moving slab laser (MSL) has been studied. Multiple volumes of solid-state laser material are sequentially diode-pumped and their energy extracted. When a volume reaches a maximum temperature after a ''sub-magazine depth'', it is moved out of the pumping region into a cooling region, and a new volume is introduced. The total magazine depth equals the submagazine depth times the number of volumes. The design parameters are chosen to provide high duty factor operation, resulting in effective use of the diode arrays. The concept significantly reduces diode array cost over conventional heat capacity lasers, and it is considered enabling for many potential applications. A conceptual design study of the hybrid configuration has been carried out. Three concepts were evaluated using CAD tools. The concepts are described and their relative merits discussed. Because of reduced disk size and diode cost, the hybrid concept may allow scaling to average powers on the order of 0.5 MW/module.

  10. Heat capacity, enthalpy and entropy of bismuth niobate and bismuth tantalate

    SciTech Connect

    Hampl, M.; Strejc, A.; Sedmidubsky, D.; Ruzicka, K.; Hejtmanek, J.; Leitner, J. . E-mail: jindrich.leitner@vscht.cz

    2006-01-15

    The heat capacity and the heat content of bismuth niobate BiNbO{sub 4} and bismuth tantalate BiTaO{sub 4} were measured by the relaxation method and Calvet-type heat flux calorimetry. The temperature dependencies of the heat capacities in the form C{sub p} {sub m}=128.628+0.03340 T-1991055/T {sup 2}+136273131/T {sup 3} (J K{sup -1} mol{sup -1}) and 133.594+0.02539 T-2734386/T {sup 2}+235597393/T {sup 3} (J K{sup -1} mol{sup -1}) were derived for BiNbO{sub 4} and BiTaO{sub 4}, respectively, by the least-squares method from the experimental data. Furthermore, the standard molar entropies at 298.15 K S {sub m}(BiNbO{sub 4})=147.86 J K{sup -1} mol{sup -1} and S {sub m}(BiTaO{sub 4})=149.11 J K{sup -1} mol{sup -1} were assessed from the low temperature heat capacity measurements. To complete a set of thermodynamic data of these mixed oxides an attempt was made to estimate the values of the heat of formation from the constituent binary oxides. -- Graphical abstract: Heat content of bismuth niobate and bismuth tantalate-experimental points determined by the drop method and temperature dependencies obtained by the simultaneous fit of heat capacity and heat content data.

  11. Thermodynamic properties of illite, smectite and beidellite by calorimetric methods: Enthalpies of formation, heat capacities, entropies and Gibbs free energies of formation

    NASA Astrophysics Data System (ADS)

    Gailhanou, H.; Blanc, P.; Rogez, J.; Mikaelian, G.; Kawaji, H.; Olives, J.; Amouric, M.; Denoyel, R.; Bourrelly, S.; Montouillout, V.; Vieillard, P.; Fialips, C. I.; Michau, N.; Gaucher, E. C.

    2012-07-01

    The thermodynamic properties of three aluminous 2:1 clay minerals were acquired at 1.013 bars and at temperatures between 5 and 500 K using various calorimetric methods. Calorimetric measurements were performed on hydrated and dehydrated <2 μm clay fractions of smectite MX-80 (Wyoming), illite IMt-2 (Silver Hill) and beidellite SBId-1 (Black Jack Mine). After purification, the mineralogical analyses gave the following structural formulae: Na0.409K0.024Ca0.009 (Si3.738Al0.262) (Al1.598Mg0.214Fe 0.173 3 + Fe 0.035 2 +)O10(OH)2,K0.762Na0.044 (Si3.387Al0.613) (Al1.427Mg0.241Fe 0.292 3 + Fe 0.084 2 +)O10(OH)2 and Ca0.185K0.104 (Si3.574Al0.426) (Al1.812Mg0.09Fe 0.112 3 +)O10(OH)2 for smectite MX-80, illite IMt-2 and beidellite SBId-1, respectively. Heat capacities were measured by low temperature adiabatic calorimetry and differential scanning calorimetry, from 5 to 500 K. Standard enthalpies of formation were obtained from solution-reaction calorimetry at 298.15 K. The standard Gibbs free energies of formation of the clay minerals were also calculated, together with the equilibrium constants at 25 °C, for anhydrous and hydrated minerals. A comparison between these experimental data and estimated values obtained from prediction models available in the literature, enabled the calculation method that appears to be the most relevant to be selected, at least for aluminous 2:1 clay minerals.

  12. Heat capacity of natural fruit juices and of their concentrates at temperatures from 10 to 120°C

    NASA Astrophysics Data System (ADS)

    Magerramov, M. A.

    2007-09-01

    The heat capacity of natural apple, cherry, and raspberry juices and of their concentrates has been studied at temperatures from 10 to 120°C and pressures of 0.1 and 2 MPa. A setup based on the method of adiabatic calorimeter was assembled to carry out investigations. An estimate of the error of setup operation as well as control measurements on water prove the accuracy of experimental data to be within ±0.8% at the indicated parameters of state. For the heat capacity of juices 175 values have been obtained. Equations that describe experimental data as functions of temperature and content of dry matter have been constructed.

  13. High-temperature heat capacity of YVO4

    NASA Astrophysics Data System (ADS)

    Denisova, L. T.; Chumilina, L. G.; Denisov, V. M.

    2014-12-01

    The molar heat capacity of YVO4 has been measured as a function of temperature (363-1000 K). The thermodynamic properties of the oxide compound have been calculated from the experimental data. The generalized equation describing the temperature effect on the heat capacity of yttrium orthovanadate in the range of 25-1000 K has been derived.

  14. Electron heat capacity and lattice properties of Americium

    NASA Astrophysics Data System (ADS)

    Povzner, A. A.; Filanovich, A. N.; Os'kina, V. A.; Volkov, A. G.

    2013-12-01

    The temperature dependence of the electron heat capacity of americium is calculated using the concepts on the electronic structure and magnetic properties of this element. The Debye temperature, the thermal expansion coefficient, and the bulk modulus of americium are determined on the basis of the results of calculations and experimental data on heat capacity.

  15. The heat capacity of a natural monticellite and phase equilibria in the system CaO-MgO-SiO2-CO2

    USGS Publications Warehouse

    Sharp, Z.D.; Essene, E.J.; Anovitz, Lawrence M.; Metz, G.W.; Westrum, E.F., Jr.; Hemingway, B.S.; Valley, J.W.

    1986-01-01

    The heat capacity of a natural monticellite (Ca1.00Mg.09Fe.91Mn.01Si0.99O3.99) measured between 9.6 and 343 K using intermittent-heating, adiabatic calorimetry yields Cp0(298) and S2980 of 123.64 ?? 0.18 and 109.44 ?? 0.16 J ?? mol-1 K-1 respectively. Extrapolation of this entropy value to end-member monticellite results in an S0298 = 108.1 ?? 0.2 J ?? mol-1 K-1. High-temperature heat-capacity data were measured between 340-1000 K with a differential scanning calorimeter. The high-temperature data were combined with the 290-350 K adiabatic values, extrapolated to 1700 K, and integrated to yield the following entropy equation for end-member monticellite (298-1700 K): ST0(J ?? mol-1 K-1) = S2980 + 164.79 In T + 15.337 ?? 10-3 T + 22.791 ?? 105 T-2 - 968.94. Phase equilibria in the CaO-MgO-SiO2 system were calculated from 973 to 1673 K and 0 to 12 kbar with these new data combined with existing data for akermanite (Ak), diopside (Di), forsterite (Fo), merwinite (Me) and wollastonite (Wo). The location of the calculated reactions involving the phases Mo and Fo is affected by their mutual solid solution. A best fit of the thermodynamically generated curves to all experiments is made when the S0298 of Me is 250.2 J ?? mol-1 K-1 less than the measured value of 253.2 J ?? mol-1 K-1. A best fit to the reversals for the solid-solid and decarbonation reactions in the CaO-MgO-SiO2-CO2 system was obtained with the ??G0298 (kJ ?? mole-1) for the phases Ak(-3667), Di(-3025), Fo(-2051), Me(-4317) and Mo(-2133). The two invariant points - Wo and -Fo for the solid-solid reactions are located at 1008 ?? 5 K and 6.3 ?? 0.1 kbar, and 1361 ?? 10 K and 10.2 ?? 0.2 kbar respectively. The location of the thermodynamically generated curves is in excellent agreement with most experimental data on decarbonation equilibria involving these phases. ?? 1986.

  16. How to deal with negative surface heat capacities

    NASA Astrophysics Data System (ADS)

    Schneider, W.

    2015-03-01

    Negative surface heat capacities are observed for many liquids, at least in certain temperature regimes. Since thermodynamic stability of a system requires positive heat capacities, it is usually argued that the surface must not be considered as an autonomous system. This, however, is not possible when the energy balance of the surface plays the role of a boundary condition for the field equations, e.g. the heat diffusion equation. A heat pulse supplied to the surface of a liquid and the stretching of a liquid film provide two examples to demonstrate that negative surface heat capacities may lead to unbounded and unconfined growth of the temperature disturbances in the liquid. To deal with the instabilities associated with negative surface heat capacities it is proposed to introduce a surface layer of small, but finite, thickness that is defined solely in terms of macroscopic thermodynamic quantities. By considering the energy balance of the surface layer, which is an open system, it is shown that the isobaric heat capacity of the liquid contained in the surface layer is to be added to the (possibly negative) surface heat capacity to obtain a positive total heat capacity of the surface layer.

  17. Simultaneous measurement of heat capacity and internal relaxation time.

    PubMed

    Nagasawa, Mitsuharu

    2016-05-01

    A new steady-state method is proposed to simultaneously measure the heat capacity and internal relaxation time using superimposed constant and square-wave power. This method is appropriate for small sample systems with low thermal conductance. The accuracies of the heat capacity and internal relaxation time are almost the same as those determined using other similar methods, but correction for the effect of internal relaxation on the heat capacity is more flexible. The thermal diffusivity and thermal conductivity are also simultaneously determined for rod- and slab-shaped samples. We demonstrate the method for small slabs of synthetic silica in the 80-320 K temperature range. PMID:27250459

  18. Heat capacity of water: A signature of nuclear quantum effects

    NASA Astrophysics Data System (ADS)

    Vega, C.; Conde, M. M.; McBride, C.; Abascal, J. L. F.; Noya, E. G.; Ramirez, R.; Sesé, L. M.

    2010-01-01

    In this note we present results for the heat capacity at constant pressure for the TIP4PQ/2005 model, as obtained from path-integral simulations. The model does a rather good job of describing both the heat capacity of ice Ih and of liquid water. Classical simulations using the TIP4P/2005, TIP3P, TIP4P, TIP4P-Ew, simple point charge/extended, and TIP5P models are unable to reproduce the heat capacity of water. Given that classical simulations do not satisfy the third law of thermodynamics, one would expect such a failure at low temperatures. However, it seems that for water, nuclear quantum effects influence the heat capacities all the way up to room temperature. The failure of classical simulations to reproduce Cp points to the necessity of incorporating nuclear quantum effects to describe this property accurately.

  19. On heat capacity of nanoclusters with a shell structure

    SciTech Connect

    Baturin, V. S. Losyakov, V. V.

    2011-02-15

    Pair correlation effects in nanoclusters with a shell structure are analyzed by the exact diagonalization method. The singularity in the behavior of the heat capacity of such clusters is analyzed using the many-particle spectrum of nanoclusters.

  20. Heat Capacity of Solids--by Courtesy of the Computer.

    ERIC Educational Resources Information Center

    Bligh, P. H.; And Others

    1987-01-01

    Describes a heat capacity experiment designed to provide an interactive environment between the student, the experiment, and the computer. Discusses computer software that has been developed so that the entire interaction can be coordinated from the computer keyboard. (TW)

  1. The Heat Capacity of Metals: A Physical Chemistry Experiment.

    ERIC Educational Resources Information Center

    Shigeishi, R. A.

    1979-01-01

    Presented here are improvements in the original design of an introductory statistical thermodynamics experiment with the result that heat capacities of metals are routinely obtained within ten percent of literature values. (BB)

  2. The heat capacity of water near solid surfaces

    NASA Astrophysics Data System (ADS)

    Vučelić, V.; Vučelić, D.

    1983-11-01

    Anomalous heat capacities of water at solid/water interfaces have been obtained. The solids vary from inorganic (zeolites, porous class, silica gel, activated carbon) to biological (protein lysozyme and adrenal gland). Water heat capacities at all interfaces exhibit the same pattern. At room temperature the small values are close to ice and increase with temperature, reaching the value of free water between 380 and 440 K.

  3. Determination of HEat Capacity of Yucca Mountain Strtigraphic Layers

    SciTech Connect

    T. Hadgu; C. Lum; J.E. Bean

    2006-06-20

    The heat generated from the radioactive waste to be placed in the proposed geologic repository at Yucca Mountain, Nevada, will affect the thermal-hydrology of the Yucca Mountain stratigraphic layers. In order to assess the effect of the movement of repository heat into the fractured rocks accurate determination of thermodynamic and hydraulic properties is important. Heat capacity is one of the properties that are required to evaluate energy storage in the fractured rock. Rock-grain heat capacity, the subject of this study, is the heat capacity of the solid part of the rock. Yucca Mountain consists of alternating lithostratigraphic units of welded and non-welded ash-flow tuff, mainly rhyolitic in composition and displaying varying degrees of vitrification and alteration. A number of methods exist that can be used to evaluate heat capacity of the stratigraphic layers that consist of different compositions. In this study, the mineral summation method has been used to quantify the heat capacity of the stratigraphic layers based on Kopp's rule. The mineral summation method is an addition of the weighted heat capacity of each mineral found in a specific layer. For this study the weighting was done based on the mass percentage of each mineral in the layer. The method utilized a mineralogic map of the rocks at the Yucca Mountain repository site. The Calico Hills formation and adjacent bedded tuff layers display a bimodal mineral distribution of vitric and zeolitic zones with differing mineralogies. Based on this bimodal distribution in zeolite abundance, the boundary between the vitric and zeolitic zones was selected to be 15% zeolitic abundance. Thus, based on the zeolite abundance, subdivisions have been introduced to these layers into ''vitric'' and ''zeolitic'' zones. Heat capacity values have been calculated for these layers both as ''layer average'' and ''zone average''. The heat capacity determination method presented in this report did not account for spatial

  4. Heat capacity and absolute entropy of iron phosphides

    SciTech Connect

    Dobrokhotova, Z.V.; Zaitsev, A.I.; Litvina, A.D.

    1994-09-01

    There is little or no data on the thermodynamic properties of iron phosphides despite their importance for several areas of science and technology. The information available is of a qualitative character and is based on assessments of the heat capacity and absolute entropy. In the present work, we measured the heat capacity over the temperature range of 113-873 K using a differential scanning calorimeter (DSC) and calculated the absolute entropy.

  5. Heat capacities of amino acids, peptides and proteins.

    PubMed

    Makhatadze, G I

    1998-04-20

    The heat capacity is one of the fundamental parameters describing thermodynamic properties of a system. It has wide applications in a number of areas such as polymer chemistry, protein folding and DNA stability. To aid the scientific community in the analysis of such data, I have compiled a database on the experimentally measured heat capacities of amino acids, polyamino acids, peptides, and proteins in solid state and in aqueous solutions. PMID:9648205

  6. Adiabatic Compression of Oxygen: Real Fluid Temperatures

    NASA Technical Reports Server (NTRS)

    Barragan, Michelle; Wilson, D. Bruce; Stoltzfus, Joel M.

    2000-01-01

    The adiabatic compression of oxygen has been identified as an ignition source for systems operating in enriched oxygen atmospheres. Current practice is to evaluate the temperature rise on compression by treating oxygen as an ideal gas with constant heat capacity. This paper establishes the appropriate thermodynamic analysis for the common occurrence of adiabatic compression of oxygen and in the process defines a satisfactory equation of state (EOS) for oxygen. It uses that EOS to model adiabatic compression as isentropic compression and calculates final temperatures for this system using current approaches for comparison.

  7. 'Heat from Above' Heat Capacity Measurements in Liquid He-4

    NASA Technical Reports Server (NTRS)

    Lee, R. A. M.; Chatto, A.; Sergatskov, D. A.; Babkin, A. V.; Boyd, S. T. P.; Churilov, A. M.; McCarson, T. D.; Chui, T. C. P.; Day, P. K.; Dunca, R. V.

    2003-01-01

    We have made heat capacity measurements of superfluid He-4 at temperatures very close to the lambda point, T(sub lambda) , in a constant heat flux, Q, when the helium sample is heated from above. In this configuration the helium enters a self-organized (SOC) heat transport state at a temperature T(sub SOC)(Q), which for Q greater than or = 100 nW/sq cm lies below T(sub lambda). At low Q we observe little or no deviation from the bulk Q = 0 heat capacity up to T(sub SOC)(Q); beyond this temperature the heat capacity appears to be sharply depressed, deviating dramatically from its bulk behaviour. This marks the formation and propagation of a SOC/superfluid two phase state, which we confirm with a simple model. The excellent agreement between data and model serves as an independent confirmation of the existence of the SOC state. As Q is increased (up to 6 micron W/sq cm) we observe a Q dependant depression in the heat capacity that occurs just below T(sub SOC)(Q), when the entire sample is still superfluid. This is due to the emergence of a large thermal resistance in the sample, which we have measured and used to model the observed heat capacity depression. Our measurements of the superfluid thermal resistivity are a factor of ten larger than previous measurements by Baddar et al.

  8. Heat Capacity of Dilute 3He-4He Monolayer Films

    NASA Astrophysics Data System (ADS)

    Morishita, Masashi

    2016-05-01

    The heat capacities of a small amount of 3He dissolved in monolayer 4He films are measured to clarify natures of monolayer 4He films. With increasing areal density, the measured heat capacities gradually increase and subsequently gradually decrease. With further increase in areal density, the measured heat capacity rapidly decreases to zero over a very narrow areal density range near that of the sqrt{3} × sqrt{3} phase. These slightly complex areal-density variations and dependence on 3He concentration are discussed from the viewpoint of the known properties of 4He films. The behaviors can be explained. However, the expected two-dimensional gas-liquid or gas-solid coexistence is not observed in this study.

  9. Heat capacity anomaly in a self-aggregating system: Triblock copolymer 17R4 in water

    NASA Astrophysics Data System (ADS)

    Dumancas, Lorenzo V.; Simpson, David E.; Jacobs, D. T.

    2015-05-01

    The reverse Pluronic, triblock copolymer 17R4 is formed from poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO): PPO14 - PEO24 - PPO14, where the number of monomers in each block is denoted by the subscripts. In water, 17R4 has a micellization line marking the transition from a unimer network to self-aggregated spherical micelles which is quite near a cloud point curve above which the system separates into copolymer-rich and copolymer-poor liquid phases. The phase separation has an Ising-like, lower consolute critical point with a well-determined critical temperature and composition. We have measured the heat capacity as a function of temperature using an adiabatic calorimeter for three compositions: (1) the critical composition where the anomaly at the critical point is analyzed, (2) a composition much less than the critical composition with a much smaller spike when the cloud point curve is crossed, and (3) a composition near where the micellization line intersects the cloud point curve that only shows micellization. For the critical composition, the heat capacity anomaly very near the critical point is observed for the first time in a Pluronic/water system and is described well as a second-order phase transition resulting from the copolymer-water interaction. For all compositions, the onset of micellization is clear, but the formation of micelles occurs over a broad range of temperatures and never becomes complete because micelles form differently in each phase above the cloud point curve. The integrated heat capacity gives an enthalpy that is smaller than the standard state enthalpy of micellization given by a van't Hoff plot, a typical result for Pluronic systems.

  10. Heat Capacity Anomaly Near the Lower Critical Consolute Point of Triethylamine-Water

    NASA Technical Reports Server (NTRS)

    Flewelling, Anne C.; DeFonseka, Rohan J.; Khaleeli, Nikfar; Partee, J.; Jacobs, D. T.

    1996-01-01

    The heat capacity of the binary liquid mixture triethylamine-water has been measured near its lower critical consolute point using a scanning, adiabatic calorimeter. Two data runs are analyzed to provide heat capacity and enthalpy data that are fitted by equations with background terms and a critical term that includes correction to scaling. The critical exponent a was determined to be 0.107 +/- 0.006, consistent with theoretical predictions. When alpha was fixed at 0.11 to determine various amplitudes consistently, our values of A(+) and A(-) agreed with a previous heat capacity measurement, but the value of A(-) was inconsistent with values determined by density or refractive index measurements. While our value for the amplitude ratio A(+)/ A(-) = 0.56 +/- 0.02 was consistent with other recent experimental determinations in binary liquid mixtures, it was slightly larger than either theoretical predictions or recent experimental values in liquid-vapor systems. The correction to scaling amplitude ratio D(+)/D(-) = 0.5 +/- 0.1 was half of that predicted. As a result of several more precise theoretical calculations and experimental determinations, the two-scale-factor universality ratio X, which we found to be 0.019 +/- 0.003, now is consistent among experiments and theories. A new 'universal' amplitude ratio R(sup +/-)(sub Bcr) involving the amplitudes for the specific heat was tested. Our determination of R(sup +/-)(sub Bcr) = -0.5 +/- 0.1 and R(sup -)(sub Bcr) = 1.1 +/- 0.1 is smaller in magnitude than predicted and is the first such determination in a binary fluid mixture.

  11. Quantum Calorimetry

    NASA Technical Reports Server (NTRS)

    Stahle, Caroline Kilbourne; McCammon, Dan; Irwin, Kent D.

    1999-01-01

    Your opponent's serve was almost perfect, but you vigorously returned it beyond his outstretched racquet to win the point. Now the tennis ball sits wedged in the chain-link fence around the court. What happened to the ball's kinetic energy? It has gone to heat the fence, of course, and you realize that if the fence were quite colder, you might be able to measure that heat and determine just how energetic your swing really was. Calorimetry has been a standard measurement technique since James Joule and Julius von Mayer independently concluded, about 150 years ago, that heat is a form of energy. But only in the past 15 years or so has calorimetry been applied, at millikelvin temperatures, to the measurement of the energy of individual photons and particles with exquisite sensitivity. In this article, we have tried to show that continuing research in low-temperature physics leads to a greater understanding of high-temperature astrophysics. Adaptations of the resulting spectrometers will be useful tool for fields of research beyond astrophysics.

  12. On the heat capacity of Ce{sub 3}Al

    SciTech Connect

    Singh, Durgesh Samatham, S. Shanmukharao Venkateshwarlu, D. Gangrade, Mohan Ganesan, V.

    2014-04-24

    Electrical resistivity and heat capacity measurements on Cerium based dense Kondo compound Ce{sub 3}Al have been reported. Clear signatures of first order structural transition at 108K, followed by a Kondo minimum and coherence are clearly seen in resistivity. The structural transition is robust and is not affected by magnetic fields. Heat capacity measurements reveal an anomalous enhancement in the heavy fermion character upon magnetic fields. Vollhardt invariance in specific heat C(T.H) curves have been observed at T=3.7K and at H ≈ 6T.

  13. Heat capacity of RVO4 ( R = La-Gd) orthovanadates

    NASA Astrophysics Data System (ADS)

    Denisova, L. T.; Chumilina, L. G.; Denisov, V. M.

    2015-05-01

    The data on the molar heat capacity of GdVO4 and SmVO4 as a function of the temperature have been obtained. The thermodynamic properties of the oxide compounds have been calculated from the experimental data. It has been shown that the specific heat capacity of La-Gd oxides and their orthovanadates change regularly depending on the ionic radius R 3+ within the first and second tetrads (La-Nd, Pm-Gd). The values of C p 0 (298 K) have been evaluated for PmVO4 and CeVO4.

  14. Study of magnetic entropy and heat capacity in ferrimagnetic Fe3Se4 nanorods

    NASA Astrophysics Data System (ADS)

    Bishwas, Mousumi Sen; Poddar, Pankaj

    2016-05-01

    Change in the magnetic entropy and specific heat capacity in Fe3Se4 nanorods synthesized by a wet-chemical method in a broad temperature (215–340 K) and magnetic field range (0–60 k Oe) was studied. The isothermal magnetic entropy change (ΔS M ) is estimated by an indirect method from the isothermal magnetization curves measured in this temperature range. SM\\max of  ‑46  ×  10‑2 J kg‑1 · K‑1 was obtained at ~317 K when the field was changed from 0 to 60 kOe. The maximum in the isothermal magnetic entropy change (ΔS M ) is observed in close proximity to T C (~323 K), which is linked to the order–disorder transition. The nature of this transition was analyzed by universal curve behavior. The temperature and magnetic field dependence of specific heat capacity was studied and analyzed to estimate the adiabatic temperature change (ΔT ad). The magnetic entropy change of Fe3Se4 nanoparticles is found to be comparable with similar ferrite and manganite nanoparticle systems and a broad operating temperature window of ~30 K was observed around room temperature.

  15. Testing of a scanning adiabatic calorimeter with Joule effect heating of the sample

    NASA Astrophysics Data System (ADS)

    Barreiro-Rodríguez, G.; Yáñez-Limón, J. M.; Contreras-Servin, C. A.; Herrera-Gomez, A.

    2008-01-01

    We evaluated a scanning adiabatic resistive calorimeter (SARC) developed to measure the specific enthalpy of viscous and gel-type materials. The sample is heated employing the Joule effect. The cell is constituted by a cylindrical jacket and two pistons, and the sample is contained inside the jacket between the two pistons. The upper piston can slide to allow for thermal expansion and to keep the pressure constant. The pistons also function as electrodes for the sample. While the sample is heated through the Joule effect, the electrodes and the jacket are independently heated to the same temperature of the sample using automatic control. This minimizes the heat transport between the sample and its surroundings. The energy to the sample is supplied by applying to the electrodes an ac voltage in the kilohertz range, establishing a current in the sample and inducing electric dissipation. This energy can be measured with enough exactitude to determine the heat capacity. This apparatus also allows for the quantification of the thermal conductivity by reproducing the evolution of the temperature as heat is introduced only to one of the pistons. To this end, the system was modeled using finite element calculations. This dual capability proved to be very valuable for correction in the determination of the specific enthalpy. The performance of the SARC was evaluated by comparing the heat capacity results to those obtained by differential scanning calorimetry measurements using a commercial apparatus. The analyzed samples were zeolite, bauxite, hematite, bentonite, rice flour, corn flour, and potato starch.

  16. Testing of a scanning adiabatic calorimeter with Joule effect heating of the sample.

    PubMed

    Barreiro-Rodríguez, G; Yáñez-Limón, J M; Contreras-Servin, C A; Herrera-Gomez, A

    2008-01-01

    We evaluated a scanning adiabatic resistive calorimeter (SARC) developed to measure the specific enthalpy of viscous and gel-type materials. The sample is heated employing the Joule effect. The cell is constituted by a cylindrical jacket and two pistons, and the sample is contained inside the jacket between the two pistons. The upper piston can slide to allow for thermal expansion and to keep the pressure constant. The pistons also function as electrodes for the sample. While the sample is heated through the Joule effect, the electrodes and the jacket are independently heated to the same temperature of the sample using automatic control. This minimizes the heat transport between the sample and its surroundings. The energy to the sample is supplied by applying to the electrodes an ac voltage in the kilohertz range, establishing a current in the sample and inducing electric dissipation. This energy can be measured with enough exactitude to determine the heat capacity. This apparatus also allows for the quantification of the thermal conductivity by reproducing the evolution of the temperature as heat is introduced only to one of the pistons. To this end, the system was modeled using finite element calculations. This dual capability proved to be very valuable for correction in the determination of the specific enthalpy. The performance of the SARC was evaluated by comparing the heat capacity results to those obtained by differential scanning calorimetry measurements using a commercial apparatus. The analyzed samples were zeolite, bauxite, hematite, bentonite, rice flour, corn flour, and potato starch. PMID:18248058

  17. DHC: a diurnal heat capacity program for microcomputers

    SciTech Connect

    Balcomb, J.D.

    1985-01-01

    A computer program has been developed that can predict the temperature swing in direct gain passive solar buildings. The diurnal heat capacity (DHC) program calculates the DHC for any combination of homogeneous or layered surfaces using closed-form harmonic solutions to the heat diffusion equation. The theory is described, a Basic program listing is provided, and an example solution printout is given.

  18. Improved Method for Determining the Heat Capacity of Metals

    ERIC Educational Resources Information Center

    Barth, Roger; Moran, Michael J.

    2014-01-01

    An improved procedure for laboratory determination of the heat capacities of metals is described. The temperature of cold water is continuously recorded with a computer-interfaced temperature probe and the room temperature metal is added. The method is more accurate and faster than previous methods. It allows students to get accurate measurements…

  19. Heat capacity measurements for cryolite (Na3AlF6) and reactions in the system NaFeAlSiOF

    USGS Publications Warehouse

    Anovitz, Lawrence M.; Hemingway, B.S.; Westrum, E.F., Jr.; Metz, G.W.; Essene, E.J.

    1987-01-01

    The heat capacity of cryolite (Na3AlF6) has been measured from 7 to 1000 K by low-temperature adiabatic and high-temperature differential scanning calorimetry. Low-temperature data were obtained on material from the same hand specimen in the calorimetric laboratories of the University of Michigan and U.S. Geological Survey. The results obtained are in good agreement, and yield average values for the entropy of cryolite of: S0298 = 238.5 J/mol KS0T-S0298 = 145.114 ln T+ 193.009*10-3T- 10.366* 105 T2- 872.89 J/mol K (273-836.5 K)??STrans = 9.9J/mol KS0T-S0298 =198.414 ln T+73.203* 10-3T-63.814* 105 T2-1113.11 J/mol K (836.5-1153 K) with the transition temperature between ??- and ??-cryolite taken at 836.5 K. These data have been combined with data in the literature to calculate phase equilibria for the system NaFeAlSiOF. The resultant phase diagrams allow constraints to be placed on the fO2, fF2, aSiO2 and T conditions of formation for assemblages in alkalic rocks. A sample application suggests that log fO2 is approximately -19.2, log fF2 is -31.9 to -33.2, and aSiO2 is -1.06 at assumed P T conditions of 1000 K, 1 bar for the villiaumite-bearing Ilimaussaq intrusion in southwestern Greenland. ?? 1987.

  20. Isothermal titration calorimetry of RNA.

    PubMed

    Salim, Nilshad N; Feig, Andrew L

    2009-03-01

    Isothermal titration calorimetry (ITC) is a fast and robust method to study the physical basis of molecular interactions. A single well-designed experiment can provide complete thermodynamic characterization of a binding reaction, including K(a), DeltaG, DeltaH, DeltaS and reaction stoichiometry (n). Repeating the experiment at different temperatures allows determination of the heat capacity change (DeltaC(P)) of the interaction. Modern calorimeters are sensitive enough to probe even weak biological interactions making ITC a very popular method among biochemists. Although ITC has been applied to protein studies for many years, it is becoming widely applicable in RNA biochemistry as well, especially in studies which involve RNA folding and RNA interactions with small molecules, proteins and with other RNAs. This review focuses on best practices for planning, designing and executing effective ITC experiments when one or more of the reactants is an RNA. PMID:18835447

  1. High-temperature heat capacity of stannates Pr2Sn2O7 and Nd2Sn2O7

    NASA Astrophysics Data System (ADS)

    Denisova, L. T.; Irtyugo, L. A.; Beletskii, V. V.; Denisov, V. M.

    2016-07-01

    Oxide compounds Pr2Sn2O7 and Nd2Sn2O7 have been obtained by solid-phase synthesis. The effect of temperature on the heat capacity of Pr2Sn2O7 (360-1045 K) and Nd2Sn2O7 (360-1030 K) has been studied using differential scanning calorimetry. The thermodynamic properties of the compounds (changes in enthalpy, entropy, and the reduced Gibbs energy) have been calculated by the experimental data of C p = f( T).

  2. Angle-resolved heat capacity of heavy fermion superconductors

    NASA Astrophysics Data System (ADS)

    Sakakibara, Toshiro; Kittaka, Shunichiro; Machida, Kazushige

    2016-09-01

    Owing to a strong Coulomb repulsion, heavy electron superconductors mostly have anisotropic gap functions which have nodes for certain directions in the momentum space. Since the nodal structure is closely related to the pairing mechanism, its experimental determination is of primary importance. This article discusses the experimental methods of the gap determination by bulk heat capacity measurements in a rotating magnetic field. The basic idea is based on the fact that the quasiparticle density of states in the vortex state of nodal superconductors is field and direction dependent. We present our recent experimental results of the field-orientation dependence of the heat capacity in heavy fermion superconductors CeTIn5 (T  =  Co, Ir), UPt3, CeCu2Si2, and UBe13 and discuss their gap structures.

  3. Angle-resolved heat capacity of heavy fermion superconductors.

    PubMed

    Sakakibara, Toshiro; Kittaka, Shunichiro; Machida, Kazushige

    2016-09-01

    Owing to a strong Coulomb repulsion, heavy electron superconductors mostly have anisotropic gap functions which have nodes for certain directions in the momentum space. Since the nodal structure is closely related to the pairing mechanism, its experimental determination is of primary importance. This article discusses the experimental methods of the gap determination by bulk heat capacity measurements in a rotating magnetic field. The basic idea is based on the fact that the quasiparticle density of states in the vortex state of nodal superconductors is field and direction dependent. We present our recent experimental results of the field-orientation dependence of the heat capacity in heavy fermion superconductors CeTIn5 (T  =  Co, Ir), UPt3, CeCu2Si2, and UBe13 and discuss their gap structures. PMID:27482621

  4. Nuclear spin heat capacity of 3He adsorbed on graphite

    NASA Astrophysics Data System (ADS)

    Greywall, Dennis S.

    1989-10-01

    The heat capacity of 3He adsorbed on graphite has been measured for films between one and five atomic layers and for temperatures between 2 and 200 mK. These results are compared with recent magnetization data which also show several anomalies in this coverage regime. Prior to third layer promotion the second layer is found to solidify into a registered structure with unusual propertis. This contradicts the model proposed to explain the NMR measurements.

  5. Estimation of the heat capacity of CdTe semiconductor

    NASA Astrophysics Data System (ADS)

    Koç, Hüseyin; Eser, Erhan

    2016-01-01

    The aim of this paper is to provide a simple and reliable analytical expression for the thermodynamic properties calculated in terms of the Debye model using the binomial coefficient, and examine specific heat capacity of CdTe in the 300-1400 K temperature range. The obtained results have been compared with the corresponding experimental and theoretical results. The calculated results are in good agreement with the other results over the entire temperature range.

  6. Hybrid heat capacity-moving slab solid-state laser

    DOEpatents

    Stappaerts, Eddy A.

    2005-03-01

    Laser material is pumped and its stored energy is extracted in a heat capacity laser mode at a high duty factor. When the laser material reaches a maximum temperature, it is removed from the lasing region and a subsequent volume of laser material is positioned into the lasing region to repeat the lasing process. The heated laser material is cooled passively or actively outside the lasing region.

  7. GENERAL: Low-temperature heat capacities and standard molar enthalpy of formation of N-methylnorephedrine C11H17NO(s)

    NASA Astrophysics Data System (ADS)

    Di, You-Ying; Wang, Da-Qi; Shi, Quan; Tan, Zhi-Cheng

    2008-08-01

    This paper reports that low-temperature heat capacities of N-methylnorephedrine C11H17NO(s) have been measured by a precision automated adiabatic calorimeter over the temperature range from T = 78 K to T = 400K. 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 polynomial 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 reference 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 = 298.15K was measured by means of an isoperibol precision 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.

  8. Heat capacities and thermal conductivities of AmO 2 and AmO 1.5

    NASA Astrophysics Data System (ADS)

    Nishi, Tsuyoshi; Itoh, Akinori; Ichise, Kenichi; Arai, Yasuo

    2011-07-01

    The thermal diffusivity of AmO 2 was measured from 473 to 773 K and that of AmO 1.5 between 473 and 1373 K using a laser flash method. The enthalpy increment of AmO 2 was measured from 335 to 1081 K and that of AmO 1.5 between 335 and 1086 K using drop calorimetry. The heat capacities of AmO 2 and AmO 1.5 were derived from the enthalpy increment measurements. The thermal conductivity was determined from the measured thermal diffusivity, heat capacity and bulk density. The heat capacities of AmO 2 was found larger than that of AmO 1.5. The thermal conductivities of AmO 2 and AmO 1.5 were found to decrease with increasing temperature in the investigated temperature range. The thermal conductivity of AmO 1.5 with A -type hexagonal structure was smaller than that of AmO 2 with C-type fluorite structure but larger than that of sub-stoichiometric AmO 1.73.

  9. Measurement of transformation temperatures and specific heat capacity of tungsten added reduced activation ferritic-martensitic steel

    NASA Astrophysics Data System (ADS)

    Raju, S.; Jeya Ganesh, B.; Rai, Arun Kumar; Mythili, R.; Saroja, S.; Mohandas, E.; Vijayalakshmi, M.; Rao, K. B. S.; Raj, Baldev

    2009-06-01

    The on-heating phase transformation temperatures up to the melting regime and the specific heat capacity of a reduced activation ferritic-martensitic steel (RAFM) with a nominal composition (wt%): 9Cr-0.09C-0.56Mn-0.23V-1W-0.063Ta-0.02N, have been measured using high temperature differential scanning calorimetry. The α -ferrite + carbides → γ-austenite transformation start and finish temperatures, namely A c1, and A c3, are found to be 1104 and 1144 K, respectively for a typical normalized and tempered microstructure. It is also observed that the martensite start ( MS) and finish ( Mf) temperatures are sensitive to the austenitising conditions. Typical MS and Mf values for the 1273 K normalized and 1033 K tempered samples are of the order 714 and 614 K, respectively. The heat capacity CP of the RAFM steel has been measured in the temperature range 473-1273 K, for different normalized and tempered samples. In essence, it is found that the CP of the fully martensitic microstructure is found to be lower than that of its tempered counterpart, and this difference begins to increase in an appreciable manner from about 800 K. The heat capacity of the normalized microstructure is found to vary from 480 to 500 J kg -1 K -1 at 500 K, where as that of the tempered steel is found to be higher by about, 150 J kg -1 K -1.

  10. Heat Capacity Uncertainty Calculation for the Eutectic Mixture of Biphenyl/Diphenyl Ether Used as Heat Transfer Fluid: Preprint

    SciTech Connect

    Gomez, J. C.; Glatzmaier, G. C.; Mehos, M.

    2012-09-01

    The main objective of this study was to calculate the uncertainty at 95% confidence for the experimental values of heat capacity of the eutectic mixture of biphenyl/diphenyl ether (Therminol VP-1) determined from 300 to 370 degrees C. Twenty-five samples were evaluated using differential scanning calorimetry (DSC) to obtain the sample heat flow as a function of temperature. The ASTM E-1269-05 standard was used to determine the heat capacity using DSC evaluations. High-pressure crucibles were employed to contain the sample in the liquid state without vaporizing. Sample handling has a significant impact on the random uncertainty. It was determined that the fluid is difficult to handle, and a high variability of the data was produced. The heat capacity of Therminol VP-1 between 300 and 370 degrees C was measured to be equal to 0.0025T+0.8672 with an uncertainty of +/- 0.074 J/g.K (3.09%) at 95% confidence with T (temperature) in Kelvin.

  11. Heat capacity and thermodynamic properties of europium orthovanadate EuVO4 in the temperature range of 400-1010 K

    NASA Astrophysics Data System (ADS)

    Denisova, L. T.; Chumilina, L. G.; Belousova, N. V.; Denisov, V. M.

    2015-08-01

    The molar heat capacity of EuVO4 is measured as a function of temperature by means of high-temperature scanning calorimetry. Thermodynamic properties of the oxide compound (variations in enthalpy H po( T) - H po(400 K), entropy S po( T) - S po(400 K) and reduced Gibbs energy Φpo( T)) are calculated from the experimental data: C p = f( T).

  12. Specific heat capacity of nanoporous Al2O3

    NASA Astrophysics Data System (ADS)

    Huang, Cong-Liang; Feng, Yan-Hui; Zhang, Xin-Xin; Li, Jing; Wang, Ge

    2013-09-01

    Based on Lindemann's criterion, a specific heat capacity model for nanoporous material was proposed by defining the surface-atom layer, to take the surface atoms and the volume atoms separately into account. The height of the surface-atom layer was determined from the experiment, and results show that only the first layer atoms on the surface should be separately considered for nanoporous Al2O3. The shape factor of the pore was also introduced in the model with values between 2 (for cylindrical pore) and 3 (for spherical pore) to characterize the morphology of the pore. It turns out experimentally that the specific heat capacity of the analyzed nanoporous Al2O3 is much larger than that of the bulk, which can be interpreted as due to the fact that the surface atom plays a more important role than the volume one. And the smaller the radius and/or the larger the porosity, which lead to a larger surface-volume ratio, the larger the specific heat capacity becomes. The nanoporous material could be a better heat storage medium than the corresponding bulk with a much lighter weight, smaller volume but higher heat storage capacity.

  13. Heat capacities of freely evaporating charged water clusters.

    PubMed

    Sundén, A E K; Støchkel, K; Panja, S; Kadhane, U; Hvelplund, P; Nielsen, S Brøndsted; Zettergren, H; Dynefors, B; Hansen, K

    2009-06-14

    We report on evaporation studies on positively charged water clusters (H(+)(H(2)O)(N)) and negatively charged mixed clusters (X(-)(H(2)O)(N)) with a small core ion X (X=O(2), CO(3), or NO(3)), in the size range N=5-300. The clusters were produced by corona discharge in ambient air, accelerated to 50 keV and mass selected by an electromagnet. The loss of monomers during the subsequent 3.4 m free flight was recorded. The average losses are proportional to the clusters' heat capacities and this allowed the determination of size-dependent heat capacities. The values are found to increase almost linearly with clusters size for both species, with a rate of 6k(B)-8k(B) per added molecule. For clusters with N<21 the heat capacities per molecule are lower but the incremental increase higher. For N>21 the values are intermediate between the bulk liquid and the solid water 0 degrees C values. PMID:19530769

  14. Heat capacities, order-disorder transitions, and thermodynamic properties of rare-earth orthoferrites and rare-earth iron garnets

    SciTech Connect

    Parida, S.C. Rakshit, S.K.; Singh, Ziley

    2008-01-15

    Rare-earth orthoferrites, RFeO{sub 3}, and rare-earth iron garnets (RIGs) R{sub 3}Fe{sub 5}O{sub 12} (R=rare-earth elements) were prepared by citrate-nitrate gel combustion method and characterized by X-ray diffraction method. Isobaric molar heat capacities of these oxides were determined by using differential scanning calorimetry from 130 to 860 K. Order-disorder transition temperatures were determined from the heat capacity measurements. The Neel temperatures (T{sub N}) due to antiferromagentic to paramagnetic transitions in orthoferrites and the Curie temperatures (T{sub C}) due to ferrimagnetic to paramagnetic transitions in garnets were determined from the heat capacity data. Both T{sub N} and T{sub C} systematically decrease with increasing atomic number of R across the series. Lattice, electronic and magnetic contributions to the total heat capacity were calculated. Debye temperatures as a function of absolute temperature were calculated for these compounds. Thermodynamic functions like C{sub p,m}{sup o}, S{sub m}{sup o}, H{sup o}, G{sup o}, (H{sub T}{sup o}-H{sub 0}{sup o}), (H{sub T}{sup o}-H{sub 298.15K}{sup o}), -(G{sub T}{sup o}-H{sub 298.15K}{sup o})/T, {delta}{sub f}H{sub m}{sup o}, and {delta}{sub f}G{sub m}{sup o} have been generated for the compounds RFeO{sub 3}(s) and R{sub 3}Fe{sub 5}O{sub 12}(s) based on the experimental data obtained in this study and the available data in the literature. - Graphical abstract: Plot of molar heat capacities (C{sub p,m}{sup o}) of R{sub 3}Fe{sub 5}O{sub 12}(s) (R=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) against temperature (T). The inset shows the magnified portion of the heat capacity plot near the transition region indicating nearly same values of Curie temperatures for different R{sub 3}Fe{sub 5}O{sub 12}(s)

  15. Measurement of Specific Heat Capacity Using Differential Scanning Calorimeter

    SciTech Connect

    J. E. Daw

    2008-11-01

    This document describes the process used at the Idaho National Laboratory’s (INL) High Temperature Test Laboratory (HTTL) for measuring specific heat capacity using a differential scanning calorimeter (DSC). The document is divided into four sections: Approach, in which the technique is described; Setup, in which the physical system is described; Procedure, in which the testing steps are listed and detailed; and Example Test, in which a typical test is outlined following the steps listed in the Procedure section. Example data, results, photos, and curves are provided throughout the document to assist other users of this system.

  16. Ground water applications of the heat capacity mapping mission

    NASA Technical Reports Server (NTRS)

    Heilman, J. L.; Moore, D. G.

    1981-01-01

    The paper discusses the ground water portion of a hydrologic investigation of eastern South Dakota using data from the Heat Capacity Mapping Mission (HCMM) satellite. The satellite carries a two-channel radiometer (0.5-1.1 and 10.5-12.5 microns) in a sun synchronous orbit and collects data at approximately 0230 and 1330 local standard time with repeat coverage of 5 to 16 days depending on latitude. It is shown that HCMM data acquired at appropriate periods of the diurnal and annual temperature cycle can provide useful information on shallow ground water.

  17. Heat Capacity Mapping Mission investigation no. 25 (Tellus project)

    NASA Technical Reports Server (NTRS)

    Deparatesi, S. G. (Principal Investigator); Reiniger, P. (Editor)

    1982-01-01

    The TELLUS pilot project, utilizing 0.5 to 1.1 micron and 10.5 to 12.5 micron day and/or night imagery from the Heat Capacity Mapping Mission, is described. The application of remotely sensed data to synoptic evaluation of evapotranspiration and moisture in agricultural soils was considered. The influence of topography, soils, land use, and meteorology on surface temperature distribution was evaluated. Anthropogenic heat release was investigated. Test areas extended from semi-arid land in southern Italy to polders in the Netherlands, and from vine-growing hills in the Rhineland to grasslands in Buckinghamshire.

  18. Determination of the heat capacities of Lithium/BCX (bromide chloride in thionyl chloride) batteries

    NASA Technical Reports Server (NTRS)

    Kubow, Stephen A.; Takeuchi, Kenneth J.; Takeuchi, Esther S.

    1989-01-01

    Heat capacities of twelve different Lithium/BCX (BrCl in thionyl chloride) batteries in sizes AA, C, D, and DD were determined. Procedures and measurement results are reported. The procedure allowed simple, reproducible, and precise determinations of heat capacities of industrially important Lithium/BCX cells, without interfering with performance of the cells. Use of aluminum standards allowed the accuracy of the measurements to be maintained. The measured heat capacities were within 5 percent of calculated heat capacity values.

  19. On the specific heat capacity enhancement in nanofluids

    NASA Astrophysics Data System (ADS)

    Hentschke, Reinhard

    2016-02-01

    Molten salts are used as heat transfer fluids and for short-term heat energy storage in solar power plants. Experiments show that the specific heat capacity of the base salt may be significantly enhanced by adding small amounts of certain nanoparticles. This effect, which is technically interesting and economically important, is not yet understood. This paper presents a critical discussion of the existing attendant experimental literature and the phenomenological models put forward thus far. A common assumption, the existence of nanolayers surrounding the nanoparticles, which are thought to be the source of, in some cases, the large increase of a nanofluid's specific heat capacity is criticized and a different model is proposed. The model assumes that the influence of the nanoparticles in the surrounding liquid is of long range. The attendant long-range interfacial layers may interact with each other upon increase of nanoparticle concentration. This can explain the specific heat maximum observed by different groups, for which no other theoretical explanation appears to exist.

  20. Magnetic Contribution to heat capacity and entropy of nickel ferrite

    SciTech Connect

    Ziemniak, S. E.; Anovitz, Lawrence {Larry} M; Castelli, R. A.; Porter, Wallace D

    2006-01-01

    The heat capacity of nickel ferrite was measured as a function of temperature from 50 to 1200 C using a differential scanning calorimeter. A thermal anomaly was observed at 584.9 C, the expected Curie temperature, TC. The observed behavior was interpreted by recognizing the sum of three contributions: (1) lattice (vibrational), (2) a spin wave (magnetic) component and (3) a ?-transition (antiferromagnetic-paramagnetic transition) at the Curie temperature. The first was modeled using vibrational frequencies derived from an experimentally-based IR absorption spectrum, while the second was modeled using a spin wave analysis that provided a T3/2 dependency in the low-temperature limit, but incorporated an exchange interaction between cation spins in the octahedral and tetrahedral sites at elevated temperatures, as first suggested by Grimes [15]. The ?-transition was fitted to an Inden-type model which consisted of two truncated power law series in dimensionless temperature (T/TC). Exponential equality (m=n=7) was observed below and above TC, indicating symmetry about the Curie temperature. Application of the methodology to existing heat capacity data for other transition metal ferrites (AFe2O4, A=Fe, Co) revealed nearly the same exponential equality, i.e., m=n=5.

  1. On the specific heat capacity enhancement in nanofluids.

    PubMed

    Hentschke, Reinhard

    2016-12-01

    Molten salts are used as heat transfer fluids and for short-term heat energy storage in solar power plants. Experiments show that the specific heat capacity of the base salt may be significantly enhanced by adding small amounts of certain nanoparticles. This effect, which is technically interesting and economically important, is not yet understood. This paper presents a critical discussion of the existing attendant experimental literature and the phenomenological models put forward thus far. A common assumption, the existence of nanolayers surrounding the nanoparticles, which are thought to be the source of, in some cases, the large increase of a nanofluid's specific heat capacity is criticized and a different model is proposed. The model assumes that the influence of the nanoparticles in the surrounding liquid is of long range. The attendant long-range interfacial layers may interact with each other upon increase of nanoparticle concentration. This can explain the specific heat maximum observed by different groups, for which no other theoretical explanation appears to exist. PMID:26873263

  2. Heat capacity changes in RNA folding: application of perturbation theory to hammerhead ribozyme cold denaturation

    PubMed Central

    Mikulecky, Peter J.; Feig, Andrew L.

    2004-01-01

    In proteins, empirical correlations have shown that changes in heat capacity (ΔCP) scale linearly with the hydrophobic surface area buried upon folding. The influence of ΔCP on RNA folding has been widely overlooked and is poorly understood. In addition to considerations of solvent reorganization, electrostatic effects might contribute to ΔCPs of folding in polyanionic species such as RNAs. Here, we employ a perturbation method based on electrostatic theory to probe the hot and cold denaturation behavior of the hammerhead ribozyme. This treatment avoids much of the error associated with imposing two-state folding models on non-two-state systems. Ribozyme stability is perturbed across a matrix of solvent conditions by varying the concentration of NaCl and methanol co-solvent. Temperature-dependent unfolding is then monitored by circular dichroism spectroscopy. The resulting array of unfolding transitions can be used to calculate a ΔCP of folding that accurately predicts the observed cold denaturation temperature. We confirm the accuracy of the calculated ΔCP by using isothermal titration calorimetry, and also demonstrate a methanol-dependence of the ΔCP. We weigh the strengths and limitations of this method for determining ΔCP values. Finally, we discuss the data in light of the physical origins of the ΔCPs for RNA folding and consider their impact on biological function. PMID:15282329

  3. Modeling of Material Removal by Solid State Heat Capacity Lasers

    SciTech Connect

    Boley, C D; Rubenchik, A M

    2002-04-17

    Pulsed lasers offer the capability of rapid material removal. Here we present simulations of steel coupon tests by two solid state heat capacity lasers built at LLNL. Operating at 1.05 pm, these deliver pulse energies of about 80 J at 10 Hz, and about 500 J at 20 Hz. Each is flashlamp-pumped. The first laser was tested at LLNL, while the second laser has been delivered to HELSTF, White Sands Missile Range. Liquid ejection appears to be an important removal mechanism. We have modeled these experiments via a time-dependent code called THALES, which describes heat transport, melting, vaporization, and the hydrodynamics of liquid, vapor, and air. It was previously used, in a less advanced form, to model drilling by copper vapor lasers [1] . It was also used to model vaporization in beam dumps for a high-power laser [2]. The basic model is in 1D, while the liquid hydrodynamics is handled in 2D.

  4. Soil moisture applications of the heat capacity mapping mission

    NASA Technical Reports Server (NTRS)

    Heilman, J. L.; Moore, D. G.

    1981-01-01

    Results are presented of ground, aircraft and satellite investigations conducted to evaluate the potential of the Heat Capacity Mapping Mission (HCMM) to monitor soil moisture and the depth of shallow ground water. The investigations were carried out over eastern South Dakota to evaluate the relation between directly measured soil temperatures and water content at various stages of canopy development, aircraft thermal scanner measurements of apparent canopy temperature and the reliability of actual HCMM data. The results demonstrate the possibility of evaluating soil moisture on the basis of HCMM apparent canopy temperature and day-night soil temperature difference measurements. Limitations on the use of thermal data posed by environmental factors which influence energy balance interactions, including phase transformations, wind patterns, topographic variations and atmospheric constituents are pointed out.

  5. Heat capacity mapping mission. [satellite for earth surface temperature measurement

    NASA Technical Reports Server (NTRS)

    Price, J. C.

    1978-01-01

    A Heat Capacity Mapping Mission (HCMM), part of a series of Applications Explorers Missions, is designed to provide data on surface heating as a response to solar energy input. The data is obtained by a two channel scanning radiometer, with one channel covering the visible and near-IR band between 0.5 and 1.1 micrometers, and the other covering the thermal-IR between 10.5 and 12.5 micrometers. The temperature range covered lies between 260 and 340 K, in 0.3 deg steps, with an accuracy at 280 K of plus or minus 0.5 K. Nominal altitude is 620 km, with a ground swath 700 km wide.

  6. LC-circuit calorimetry

    SciTech Connect

    Bossen, O.; Schilling, A.

    2011-09-15

    We present a new type of calorimeter in which we couple an unknown heat capacity with the aid of Peltier elements to an electrical circuit. The use of an electrical inductance and an amplifier in the circuit allows us to achieve autonomous oscillations, and the measurement of the corresponding resonance frequency makes it possible to accurately measure the heat capacity with an intrinsic statistical uncertainty that decreases as {approx}t{sub m}{sup -3/2} with measuring time t{sub m}, as opposed to a corresponding uncertainty {approx}t{sub m}{sup -1/2} in the conventional alternating current method to measure heat capacities. We have built a demonstration experiment to show the feasibility of the new technique, and we have tested it on a gadolinium sample at its transition to the ferromagnetic state.

  7. Spin density wave (SDW) transition in Ru doped BaFeAs{sub 2} investigated by AC steady state calorimetry

    SciTech Connect

    Vinod, K. Sharma, Shilpam; Sundar, C. S.; Bharathi, A.

    2015-06-24

    Heat capacity measurements were done on sub-micron sized BaFe{sub 2−x}Ru{sub x}As{sub 2} single crystals using thin film membrane based the AC steady state calorimetry technique. Noticeable thermal hysteresis is observed in the heat capacity of the BaFe{sub 2−x}Ru{sub x}As{sub 2} during cooling and warming cycles, indicating first order nature of the SDW transition.

  8. Heat capacities and entropies at 298.15 K of MgTiO3 (geikielite), ZnO (zincite), and ZnCO3 (smithsonite)

    USGS Publications Warehouse

    Robie, R.A.; Haselton, H.T., Jr.; Hemingway, B.S.

    1989-01-01

    Heat capacities of synthetic MgTiO3 (geikielite), ZnO (zincite), and natural crystals of smithsonite (ZnCO3) were measured between 9 and 366 K using an automatic adiabatically shielded calorimeter. At 298.15 K the standard molar entropies Smo of MgTiO3, ZnO, and ZnCO3 are (74.64 ?? 0.15), (43.16 ?? 0.09), and (81.19 ?? 0.16) J??K-1??mol-1, respectively. Debye temperatures for MgTiO3 and ZnO calculated from our Cp, mo values below 20 K are (900 ?? 20) K and (440 ?? 25) K respectively. Heat capacities for MgTiO3 and ZnO were combined with enthalpy increments from the literature to derive heat-capacity equations for these phases from 260 to about 1800 K. The heat capacities of MgTiO3 between 260 and 1720 K were fitted with an average deviation of 0.3 per cent by the equation: C??p,m/(J??K-1??mol-1) = 222.5-0.05274(T/K)-6.092x105(T/K)-1-1874.6(T/K) -1/2+1.878x10-5(T/K)2 and for ZnO the equation: C??p,m/(J??K-1??mol-1) = 53.999+7.851x10-4(T/K)-5.868x105(T/K)-2 -127.50(T/K)-:1/2+1.9376x10-6(T/K)2 fits the heat capacities in the temperature interval of 250 to 1800 K with an average deviation of 0.7 per cent. ?? 1989.

  9. Heat capacity of xenon adsorbed on nanobundle grooves

    NASA Astrophysics Data System (ADS)

    Chishko, K. A.; Sokolova, E. S.

    2016-02-01

    A model of a one-dimensional nonideal gas in an external transverse force field is used to interpret the experimentally observed thermodynamic properties of xenon deposited in grooves on the surface of carbon nanobundles. A nonideal gas model with pairwise interactions is not entirely adequate for describing dense adsorbates (at low temperatures), but makes it easy to account for the exchange of particles between the 1D adsorbate and the 3D atmosphere, which is an important factor at intermediate (on the order of 35 K for xenon) and, especially, high (˜100 K) temperatures. In this paper, we examine a 1D real gas taking only the one-dimensional Lennard-Jones interaction into account, but under exact equilibrium with respect to the number of particles between the 1D adsorbate and the 3D atmosphere of the measurement cell. The low-temperature branch of the specific heat is fitted independently by an elastic chain model so as to obtain the best agreement between theory and experiment over the widest possible region, beginning at zero temperature. The gas approximation sets in after temperatures for which the phonon specific heat of the chain essentially transforms to a one-dimensional equipartition law. Here the basic parameters of both models can be chosen so that the heat capacity C(T) of the chain transforms essentially continuously into the corresponding curve for the gas approximation. Thus, it can be expected that an adequate interpretation of the real temperature dependences of the specific heat of low-dimensionality atomic adsorbates can be obtained through a reasonable combination of the phonon and gas approximations. The main parameters of the gas approximation (such as the desorption energy) obtained by fitting the theory to experiments on the specific heat of xenon correlate well with published data.

  10. Heat Capacity Changes and Disorder-to-Order Transitions in Allosteric Activation.

    PubMed

    Cressman, William J; Beckett, Dorothy

    2016-01-19

    Allosteric coupling in proteins is ubiquitous but incompletely understood, particularly in systems characterized by coupling over large distances. Binding of the allosteric effector, bio-5'-AMP, to the Escherichia coli biotin protein ligase, BirA, enhances the protein's dimerization free energy by -4 kcal/mol. Previous studies revealed that disorder-to-order transitions at the effector binding and dimerization sites, which are separated by 33 Å, are integral to functional coupling. Perturbations to the transition at the ligand binding site alter both ligand binding and coupled dimerization. Alanine substitutions in four loops on the dimerization surface yield a range of energetic effects on dimerization. A glycine to alanine substitution at position 142 in one of these loops results in a complete loss of allosteric coupling, disruption of the disorder-to-order transitions at both functional sites, and a decreased affinity for the effector. In this work, allosteric communication between the effector binding and dimerization surfaces in BirA was further investigated by performing isothermal titration calorimetry measurements on nine proteins with alanine substitutions in three dimerization surface loops. In contrast to BirAG142A, at 20 °C all variants bind to bio-5'-AMP with free energies indistinguishable from that measured for wild-type BirA. However, the majority of the variants exhibit altered heat capacity changes for effector binding. Moreover, the ΔCp values correlate with the dimerization free energies of the effector-bound proteins. These thermodynamic results, combined with structural information, indicate that allosteric activation of the BirA monomer involves formation of a network of intramolecular interactions on the dimerization surface in response to bio-5'-AMP binding at the distant effector binding site. PMID:26678378

  11. Temperature dependence of electronic heat capacity in Holstein model of DNA

    NASA Astrophysics Data System (ADS)

    Fialko, N.; Sobolev, E.; Lakhno, V.

    2016-04-01

    The dynamics of charge migration was modeled to calculate temperature dependencies of its thermodynamic equilibrium values such as energy and electronic heat capacity in homogeneous adenine fragments. The energy varies from nearly polaron one at T ∼ 0 to midpoint of the conductivity band at high temperatures. The peak on the graph of electronic heat capacity is observed at the polaron decay temperature.

  12. Dynamic Calorimetry for Students

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2007-01-01

    A student experiment on dynamic calorimetry is described. Dynamic calorimetry is a powerful technique for calorimetric studies, especially at high temperatures and pressures. A low-power incandescent lamp serves as the sample. The ScienceWorkshop data-acquisition system with DataStudio software from PASCO Scientific displays the results of the…

  13. Heat capacity and heat content measurements on binary compounds in the Ru-Si, Ru-Ge, and Ru-Sn systems

    SciTech Connect

    Kuntz, J.J.; Gachon, J.C.; Feschotte, P.; Perring, L. |

    1997-11-01

    Molar heat capacities of Ru{sub 0.5}Si{sub 0.5} Ru{sub 0.4}Si{sub 0.6}, Ru{sub 0.5}Ge{sub 0.5}, Ru{sub 0.4}Ge{sub 0.6}, Ru{sub 0.4}Sn{sub 0.6}, and Ru{sub 0.3}Sn{sub 0.7} were determined every 10 K by differential scanning calorimetry in the temperature range from 310 to 1080 K. The present results have been fitted by a polynomial function of temperature: C{sub p} = a+bT-cT{sup -2}. Heat contents of the six phases have been verified by drop calorimetry. Standard enthalpies of formation are given for the studied compounds.

  14. Low Temperature Heat Capacities and Standard Molar Enthalpy of Formation of 2-Pyrazinecarboxylic Acid (C5H4N2O2)(s).

    PubMed

    Kong, Yu-Xia; Di, You-Ying; Yang, Wei-Wei; Gao, Sheng-Li; Tan, Zhi-Cheng

    2010-06-01

    Low-temperature heat capacities of 2-pyrazinecarboxylic acid (C5H4N2O2)(s) were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of heat capacities as a function of temperature was fitted by least squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at 10 K intervals. The constant-volume energy of combustion of the compound at T = 298.15 K was measured by a precision rotating-bomb combustion calorimeter to be ΔcU = -(17839.40 ± 7.40) J g-1. The standard molar enthalpy of combustion of the compound was determined to be ΔcH0m = -(2211.39 ± 0.92) KJ mol-1, according to the definition of combustion enthalpy. Finally, the standard molar enthalpy of formation of the compound was calculated to be ΔfH0m = -(327.82 ± 1.13) kJ mol-1 in accordance with Hess law. PMID:24061733

  15. Low-temperature Heat Capacities and Thermodynamic Properties of Crystalline 2-Aminopyridinium Benzoate (C12H12N2O2) (s).

    PubMed

    He, Dong-Hua; Di, You-Ying; Dan, Wen-Yan; Liu, Yu-Pu; Wang, Da-Qi

    2010-06-01

    2-Aminopyridinium benzoate was synthesized. Chemical analysis, elemental analysis, and X-ray crystallography were applied to characterize the composition and crystal structure of the compound. The lattice potential energy of the title compound was calculated to be UPOT = 284.297 kJ mol-1. Low-temperature heat capacities of the compound were measured by a precision automatic adiabatic calorimeter over the temperature range from 78 K to 365 K. A polynomial equation of heat capacities against the temperature in the region of 78 K to 365 K was fitted by a least square method. Based on the fitted polynomial equation, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated at intervals of 5 K. According to the synthesis reaction, the standard molar enthalpies of dissolution for the reactants and product in the selected solvent were measured by an isoperibol solution-reaction calorimeter, respectively. Accordingly, the enthalpy change of the synthesis reaction was calculated to be ΔrHom = -(20.016 ± 0.182) kJ mol-1. Finally, the standard molar enthalpy of formation of 2-aminopyridinium benzoate was determined to be ΔfHom = - (365.416 ± 0.961) kJ mol-1 in accordance with Hess law. PMID:24061744

  16. Heat capacity of yttrium aluminum garnet, Y{sub 3}Al{sub 5}O{sub 12}, in the range 350-610 K

    SciTech Connect

    Pashinkin, A.S.; Malkova, A.S.; Ivanov, I.A.

    1995-12-01

    Yttrium aluminum garnet (YAG), Y{sub 3}Al{sub 5}O{sub 12}, doped most often with neodymium (Nd{sup 3+}), is widely used as a gain medium in lasers. In thermodynamic and physical calculations aimed at optimizing conditions for the preparation of YAG, data on its thermodynamic properties, including heat capacity C{sub p}, are of key importance. In earlier studies, C{sub p} of undoped YAG in the range 4.25-300.8 K was measured and its standard entropy calculated. At higher temperatures (223 - 673), heat capacity measurements with an IT-S-400 calorimeter yielded values about 4% greater than an adiabatic calorimeter. This systematic error was taken into account in further calculations so as to match the C{sub p} data in the range 298-673 K with low-temperature measurements. These results should, however, be considered preliminary. Further measurements and more thorough data treatment revealed a pronounced scatter in C{sub p} data in the range 448 - 673 K. Therefore, we undertook repeat measurements of the isobaric heat capacity of YAG with a DSM-2M differential scanning calorimeter.

  17. Measuring the Imaginary Part of the Permittivity Using Calorimetry

    NASA Astrophysics Data System (ADS)

    Kashuri, Hektor; Sigdel, Krishna; Kashuri, Klaida; Iannacchione, Germano S.

    2011-03-01

    Modulated or AC calorimetry is a well established technique for measuring the temperature dependence of the heat capacity of many complex fluids. Employing a dielectric or RF heating method, the heat capacity, thermal conductivity, and the dielectric properties of the sample are all probed simultaneously. Combining the results obtained by this technique for the liquid crystal 4-n-pentyl-4-cyanophenyl (5CB) with those obtained by our novel AC calorimetric technique employing RF (dielectric) heating, we have been able to directly measure the temperature dependence of the imaginary part of the permittivity of this liquid crystal. Measurements were performed over a temperature range from 303 to 313 K, spanning the nematic to isotropic phase transition, as well as radio frequencies from 10 to 30 MHz Worcester Polytechnic Institute (WPI).

  18. Thermal Properties of Trogamid by Conventional and Fast Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Cebe, Peggy; Merfeld, John; Mao, Bin; Wurm, Andreas; Zhuravlev, Evgeny; Schick, Christoph

    We use conventional slow scan rate differential scanning calorimetry, and fast scanning chip-based calorimetry (FSC), to investigate the crystallization and melting behavior of Trogamid, a chemical relative of nylon. Fundamental thermal properties of Trogamid were studied, including the melt crystallization kinetics, heat of fusion, and the solid and liquid state heat capacities. Using slow scan DSC (at 5 K/min), Trogamid displays a glass transition relaxation process at ~133 C, melting endotherm peak at 250 C, and is stable upon repeated heating to 310 C. When using slow scan DSC, the isothermal melt crystallization temperatures were restricted to 225 C or above. Trogamid crystallizes rapidly from the melt and conventional calorimetry is unable to cool sufficiently fast to prevent nucleation and crystal growth prior to stabilization at lower crystallization temperatures. Using FSC we were able to cool nano-gram sizes samples at 2000 K/s to investigate a much lower range of melt crystallization temperatures, from 205-225 C. The experimental protocol for performing FSC on semicrystalline polymers to obtain liquid state heat capacity data will be presented. National Science Foundation, Polymers Program DMR-1206010; DAAD; Tufts Faculty Supported Leave.

  19. Direct Observation of a Majorana Quasiparticle Heat Capacity in 3He

    NASA Astrophysics Data System (ADS)

    Bunkov, Y. M.

    2014-04-01

    The Majorana fermion, which acts as its own antiparticle, was suggested by Majorana in 1937 (Nuovo Cimento 14:171). While no stable particle with Majorana properties has yet been observed, Majorana quasiparticles (QP) may exist at the boundaries of topological insulators. Here we report the preliminary results of direct observation of Majorana QPs by a precise measurements of superfluid 3He heat capacity. The bulk superfluid 3He heat capacity falls exponentially with cooling at the temperatures significantly below the energy gap. Owing to the zero energy gap mode the Majorana heat capacity falls in a power law. The Majorana heat capacity can be larger than bulk one at some temperature, which depends on surface to volume ratio of the experimental cell. Some times ago we developed the Dark matter particles detector (DMD) on a basis of superfluid 3He which is working at the frontier of extremely low temperatures (Winkelmann et al., Nucl. Instrum. Meth. A 559:384-386, 2006). Here we report the observation of zero gap mode of Majorana, follows from the new analyses of DMD heat capacity, published early. We have found a 10 % deviation from the bulk superfluid 3He heat capacity at the temperature of 135 μK. This deviation corresponds well to the theoretical value for Majorana heat capacity at such low temperature. (Note, there were no fitting parameters).

  20. Looking for Small Changes in Heat Capacity using Differential Scanning Calorimeter

    NASA Astrophysics Data System (ADS)

    Linthicum, Will; Laugharn, Andrew; Amanuel, Samuel

    2014-03-01

    One of the major drawbacks of renewable energy is the lack of adequate and economical means of storage. In the case of concentrated solar power a large amount of thermal fluid is required to store a reasonable amount of energy to meet demands. This is primarily because the fluids tend to have a low specific heat capacity. Formulating composites of these fluids can enhance their specific heat capacity and avails opportunities to make concentrated solar power more attractive. Traditionally, the specific heat capacity of composite materials is computed from the weighted average of the individual heat capacities. This, however, does not take into account interfacial effects where the heat capacity could be different. Although, these changes in heat capacity may be small in traditional composites, they could be significant in the case of nanocomposites. From our phase transition studies of fluids confined in nano pores, we have demonstrated that the molecules at the interface have different thermodynamic behavior. In this presentation, we show our systematic studies and development of a baseline useful in evaluating small changes in heat capacity using a power compensated differential scanning calorimeter NY-State NASA Space grant

  1. Experimental Study of the Isochoric Heat Capacity of Diethyl Ether (DEE) in the Critical and Supercritical Regions

    NASA Astrophysics Data System (ADS)

    Polikhronidi, N. G.; Abdulagatov, I. M.; Batyrova, R. G.; Stepanov, G. V.; Wu, J. T.; Ustuzhanin, E. E.

    2012-02-01

    Two- and one-phase liquid and vapor isochoric heat capacities ( C V ρ T relationship) of diethyl ether (DEE) in the critical and supercritical regions have been measured with a high-temperature and high-pressure nearly constant-volume adiabatic calorimeter. The measurements were carried out in the temperature range from 347 K to 575 K for 12 liquid and 5 vapor densities from 212.6 kg·m-3 to 534.6 kg·m-3. The expanded uncertainties (coverage factor k = 2, two-standard deviation estimate) for values of the heat capacity were 2% to 3% in the near-critical region, 1.0% to 1.5% for the liquid isochores, and 3% to 4% for the vapor isochores. The uncertainties of density ( ρ) and temperature ( T) measurements were 0.02% and 15 mK, respectively. The values of the internal energy, U( T, V), and second temperature derivative of pressure, (∂2 P/∂ T 2) ρ , were derived using the measured C V data near the critical point. The critical anomaly of the measured C V and derived values of U( T, V) and (∂2 P/∂ T 2) ρ in the critical and supercritical regions were interpreted in terms of the scaling theory of critical phenomena. The asymptotic critical amplitudes {({A_0^+} and {A_0^- )}} of the scaling power laws along the critical isochore for one- and two-phase C V were calculated from the measured values of C V . Experimentally derived values of the critical amplitude ratio for {CV left({A_0^+ /A_0^- = 0.521}right)} are in good agreement with the values predicted by scaling theory. The measured C V data for DEE were analyzed to study the behavior of loci of isothermal and isochoric C V maxima and minima in the critical and supercritical regions.

  2. Orientation and heat capacity of horizontally adsorbed molecules in electric fields

    NASA Astrophysics Data System (ADS)

    Liao, Ying-Yen

    2014-02-01

    The orientation and the heat capacity of horizontally adsorbed molecules are investigated in static electric fields. We evaluate the energy spectrum and the wave function to probe the rotational characteristics of the molecule. Numerical results indicate that the electric field and the effect of quantum confinement lead to anticrossing behaviors in the energy levels. The orientation reveals a stepped feature due to the anticrossing in the ground state. Moreover, the heat capacity displays two peaks near the anticrossing. By means of comparison, each peak of the heat capacity corresponds to a particular degree of orientation.

  3. S = 1 Excitations in Heat Capacity of the Haldane Compound TMNIN Doped with a Nonmagnetic Impurity

    NASA Astrophysics Data System (ADS)

    Kawae, Tatsuya; Ito, Masakazu; Mito, Masaki; Takeda, Kazuyoshi

    1999-03-01

    We have studied the field dependence of the heat capacity of a typicalHaldane antiferromagnet (CH3)4NNi(NO)3 (TMNIN) doped with thenonmagnetic impurity Zn2+, as well as of a pure TMNIN. The overallfeatures of the magnetic heat capacity, including the characteristic broadmaximum, are almost reproduced by the theoretical curve with J/k B =-12 K for both systems in zero field. The field dependence in the impuresystems is described well by assuming the Schottky heat capacity with S =1, not S = 1/2 expected from the VBS model. A possible reason why the S= 1 model is suitable is discussed.

  4. Heat capacity of the n-InSe single crystal layered semiconductor

    NASA Astrophysics Data System (ADS)

    Dmitriev, A. I.; Lashkarev, G. V.; Baida, A. A.; Kovalyuk, Z. D.; Szewczyk, A.; Piotrowski, K.; Gutowska, M.

    2002-11-01

    Measurements of heat capacity and conductivity of InSe single crystal have been carried out over the temperature range 5-300 K. Heat capacity Cp, entropy DeltaS, and enthalpy DeltaH as well as Debye temperatures have been calculated. The singularities observed on the temperature dependencies of heat capacity and electric conductivity can be attributed to a phase transition to the charge density wave state. This transition perturbs considerably the electron and phonon spectra of the studied layered crystal.

  5. The Collapse of Hydrodynamic Radii In Pluronic Pe6400 Micelles In Vicinity of Supramolecular Transition: Dynamic Light Scattering, Heat Capacity and Sound Velocity Measurements

    NASA Astrophysics Data System (ADS)

    Bakaeva, Z.; Igamberdiev, K.; Khabibulaev, P.; Stepanek, P.; Cernoch, P.

    This work reports the results of a study of the microstructural and dynamical properties of self-assembled triblock copolymers. It was performed using adiabatic calorimetry, ultrasonic spectroscopy and dynamic light scattering. In the vicinity of supramolecular transitions, first aggregates occur; with further increasing temperature a spontaneous forming of compact structures was observed in the system. These results are supported by data of the shear viscosity and free internal volume parameters calculated in the framework of the Frenkel-Andrade approach.

  6. Prediction of heat capacities of solid inorganic salts from group contributions

    SciTech Connect

    Mostafa, A.T.M.G.; Eakman, J.M.; Yarbro, S.L.

    1997-01-01

    A group contribution technique is proposed to predict the coefficients in the heat capacity correlation, C{sub p} = a + bT + c/T{sup 2} + dT{sup 2}, for solid inorganic salts. The results from this work are compared with fits to experimental data from the literature. It is shown to give good predictions for both simple and complex solid inorganic salts. Literature heat capacities for a large number (664) of solid inorganic salts covering a broad range of cations (129), anions (17) and ligands (2) have been used in regressions to obtain group contributions for the parameters in the heat capacity temperature function. A mean error of 3.18% is found when predicted values are compared with literature values for heat capacity at 298{degrees} K. Estimates of the error standard deviation from the regression for each additivity constant are also determined.

  7. Determination of the specific heat capacity of a graphite sample using absolute and differential methods

    NASA Astrophysics Data System (ADS)

    Picard, Susanne; Burns, David T.; Roger, Philippe

    2007-10-01

    An experimental assembly has been constructed to measure the specific heat capacity of macroscopic graphite samples at room temperature. The same batch of graphite constitutes the core of a graphite calorimeter, which is currently being realized to measure the absorbed dose due to ionizing radiation. Two different experimental procedures have been applied. In the first method the specific heat capacity of graphite was measured directly, where its value is corrected for the influence of impurities. The second method, to our knowledge not previously applied to macroscopic samples, is based on a series of differential measurements where no correction for added impurities is needed. By its nature, the second method reduces systematic effects. The specific heat capacity of a particular graphite sample is determined to be 706.9 J K-1 kg-1 with a combined relative standard uncertainty of 9 parts in 104 at 295.15 K. The specific heat capacity of cyanoacrylate has also been determined.

  8. Solvation thermodynamics and heat capacity of polar and charged solutes in water

    SciTech Connect

    Sedlmeier, Felix; Netz, Roland R.

    2013-03-21

    The solvation thermodynamics and in particular the solvation heat capacity of polar and charged solutes in water is studied using atomistic molecular dynamics simulations. As ionic solutes we consider a F{sup -} and a Na{sup +} ion, as an example for a polar molecule with vanishing net charge we take a SPC/E water molecule. The partial charges of all three solutes are varied in a wide range by a scaling factor. Using a recently introduced method for the accurate determination of the solvation free energy of polar solutes, we determine the free energy, entropy, enthalpy, and heat capacity of the three different solutes as a function of temperature and partial solute charge. We find that the sum of the solvation heat capacities of the Na{sup +} and F{sup -} ions is negative, in agreement with experimental observations, but our results uncover a pronounced difference in the heat capacity between positively and negatively charged groups. While the solvation heat capacity {Delta}C{sub p} stays positive and even increases slightly upon charging the Na{sup +} ion, it decreases upon charging the F{sup -} ion and becomes negative beyond an ion charge of q=-0.3e. On the other hand, the heat capacity of the overall charge-neutral polar solute derived from a SPC/E water molecule is positive for all charge scaling factors considered by us. This means that the heat capacity of a wide class of polar solutes with vanishing net charge is positive. The common ascription of negative heat capacities to polar chemical groups might arise from the neglect of non-additive interaction effects between polar and apolar groups. The reason behind this non-additivity is suggested to be related to the second solvation shell that significantly affects the solvation thermodynamics and due to its large spatial extent induces quite long-ranged interactions between solvated molecular parts and groups.

  9. Single-ion heat capacities, C(p)(298)ion, of solids: with a novel route to heat-capacity estimation of complex anions.

    PubMed

    Glasser, Leslie; Jenkins, H Donald Brooke

    2012-06-01

    Single-ion heat capacities, C(p)(298)(ion), are additive values for the estimation of room-temperature (298 K) heat capacities of ionic solids. They may be used for inferring the heat capacities of ionic solids for which values are unavailable and for checking reported values, thus complementing our independent method of estimation from formula unit volumes (termed volume-based thermodynamics, VBT). Analysis of the reported heat-capacity data presented here provides a new self-consistent set of heat capacities for both cations and anions that is compatible (and thus may be combined) with an extensive set developed by Spencer. The addition of a large range of silicate species permits the estimation of the heat capacities of many silicate minerals. The single-ion heat capacities of individual silicate anions are observed to be strictly proportional to the total number of atoms (Si plus O), n, contained within the silicate anion complex itself (e.g., for the anion Si(2)O(7)(2-), n = 9, for SiO(4)(2-), n = 5), C(p)(silicate anion)/J K(-1) mol(-1) = 13.8n, in a new rule that is an extension of the Neumann-Kopp relationship. The same linear relationship applies to other homologous anion series (for example, oxygenated heavy-metal anion complexes such as niobates, bismuthates, and tantalates), although with a different proportionality constant. A similar proportionality, C(p)(complex anion)/J K(-1) mol(-1) ≈ 17.5n, which may be regarded as a convenient "rule of thumb", also applies, although less strictly, to complex anions in general. The proportionality constants reflect the rigidity of the complex anion, being always less than the Dulong-Petit value of 25 J K(-1) mol(-1). An emergent feature of our VBT and single-ion approaches to an estimation of the thermodynamic properties is the identification of anomalies in measured values, as is illustrated in this paper. PMID:22583202

  10. Highly precise experimental device for determining the heat capacity of liquids under pressure.

    PubMed

    González-Salgado, D; Valencia, J L; Troncoso, J; Carballo, E; Peleteiro, J; Romaní, L; Bessières, D

    2007-05-01

    An experimental device for making isobaric heat capacity measurements of liquids under pressure is presented. The device is an adaptation of the Setaram micro-DSC II atmospheric-pressure microcalorimeter, including modifications of vessels and a pressure line allowing the pressure in the measurement system to be set, controlled, and stabilized. The high sensitivity of the apparatus combined with a suitable calibration procedure allows very accurate heat capacity measurements under pressure to be made. The relative uncertainty in the isobaric molar heat capacity measurements provided by the new device is estimated to be 0.08% at atmospheric pressure and 0.2% at higher levels. The device was validated from isobaric molar heat capacity measurements for hexane, nonane, decane, undecane, dodecane, and tridecane, all of which were highly consistent with reported data. It also possesses a high sensitivity as reflected in its response to changes in excess isobaric molar heat capacity with pressure, which were examined in this work for the first time by making heat capacity measurements throughout the composition range of the 1-hexanol+n-hexane system. Finally, preliminary measurements at several pressures near the critical conditions for the nitromethane+2-butanol binary system were made that testify to the usefulness of the proposed device for studying critical phenomena in liquids under pressure. PMID:17552856

  11. Ambient heat capacities and entropies of ionic solids: a unique view using the Debye equation.

    PubMed

    Glasser, Leslie

    2013-06-01

    Entropies of solids are obtained experimentally as integrals of measured heat capacities over the temperature range from zero to ambient. Correspondingly, the Debye phonon distribution equation for solids provides a theoretical connection between these two chemical thermodynamic measures. We examine how the widely applicable Debye equation illuminates the relation between the corresponding experimental measures using more than 250 ionic solids. Estimation of heat capacities for simple ionic solids by the Dulong-Petit heat capacity limit, by the Neumann-Kopp elemental sum, and by the ion sum method is examined in relation to the Debye equation. We note that, and explain why, the ambient temperature heat capacities and entropies of ionic solids are found to be approximately equal, and how deviations from equality may be related to the Debye temperature, ΘD, which characterizes the Debye equation. It is also demonstrated that Debye temperatures may be readily estimated from the experimental ratio of ambient heat capacity to entropy, C(p)/S(p), rather than requiring resort to elaborate theoretical or experimental procedures for their determination. Correspondingly, ambient mineral entropies and heat capacities are linearly correlated and may thus be readily estimated from one another. PMID:23687944

  12. Scintillator plate calorimetry

    SciTech Connect

    Price, L.E.

    1990-01-01

    Calorimetry using scintillator plates or tiles alternated with sheets of (usually heavy) passive absorber has been proven over multiple generations of collider detectors. Recent detectors including UA1, CDF, and ZEUS have shown good results from such calorimeters. The advantages offered by scintillator calorimetry for the SSC environment, in particular, are speed (<10 nsec), excellent energy resolution, low noise, and ease of achieving compensation and hence linearity. On the negative side of the ledger can be placed the historical sensitivity of plastic scintillators to radiation damage, the possibility of nonuniform response because of light attenuation, and the presence of cracks for light collection via wavelength shifting plastic (traditionally in sheet form). This approach to calorimetry is being investigated for SSC use by a collaboration of Ames Laboratory/Iowa State University, Argonne National Laboratory, Bicron Corporation, Florida State University, Louisiana State University, University of Mississippi, Oak Ridge National Laboratory, Virginia Polytechnic Institute and State University, Westinghouse Electric Corporation, and University of Wisconsin.

  13. Calorimetry for the SSC

    SciTech Connect

    Gordon, H.A.; Grannis, P.D.

    1984-01-01

    The activities related to calorimetry at Snowmass took place in three main areas. These were: (1) The performance criteria for SSC calorimetry, including the requirements on hermeticity, shower containment, segmentation and time resolution. The use of calorimetric means of particle identification was studied. (2) The study of triggering methods using calorimeter energy, angle and timing information. (3) A review of a wide variety of calorimeter materials for absorber and sampling, as well as several means of obtaining the readout of the energy deposits. 48 references, 10 figures, 1 table.

  14. Scintillator materials for calorimetry

    SciTech Connect

    Weber, M.J.

    1994-09-01

    Requirements for fast, dense scintillator materials for calorimetry in high energy physics and approaches to satisfying these requirements are reviewed with respect to possible hosts and luminescent species. Special attention is given to cerium-activated crystals, core-valence luminescence, and glass scintillators. The present state of the art, limitations, and suggestions for possible new scintillator materials are presented.

  15. Measuring the heat capacity in a Bose-Einstein condensation using global variables

    NASA Astrophysics Data System (ADS)

    Shiozaki, R. F.; Telles, G. D.; Castilho, P.; Poveda-Cuevas, F. J.; Muniz, S. R.; Roati, G.; Romero-Rochin, V.; Bagnato, V. S.

    2014-10-01

    Phase transitions are well understood and generally followed by the behavior of the associated thermodynamic quantities, such as in the case of the λ -point superfluid transition of liquid He, which is observed in its heat capacity. In the case of a trapped Bose-Einstein condensate, the heat capacity cannot be directly measured. In this work, we present a technique capable of determining the global heat capacity from the density distribution of a weakly interacting gas trapped in an inhomogeneous potential. This approach represents an alternative to models based on the local density approximation. By defining a pair of global conjugate variables, we determine the total internal energy and its temperature derivative, the heat capacity. We then apply the technique to a trapped 87Rb BEC, and a λ -type transition dependent on the atom number is observed, and the deviations from the noninteracting, ideal gas case are discussed. Finally, we discuss the chances of using this method to study the heat capacity at T →0 .

  16. Conformational Heat Capacity of Interacting Systems of Polymers and Small Molecules

    NASA Astrophysics Data System (ADS)

    Pyda, M.; Bartkowiak, M.; Wunderlich, B.

    1998-03-01

    The total heat capacity of systems of macromolecules interacting with small molecules is estimated as a sum of the vibrational, external and conformational contributions. The conformational contribution is calculated using a simple model in which monolayers or clusters of small molecules (such as polar or dispersive solvents) are assumed to interact with the flexible liner chains of the macromolecules. The conformational states of the chain are described by Ising variables. The interaction influences the conformational states energies, and the resulting one-dimensional model is solved exactly using the transfer matrix method. Depending on the model parameters, the presence of the small molecules can lead to a double-peaked structure of the heat capacity as a function of temperature. The interaction causes an increase of the heat capacity in the low temperature region. Formation of cluster of small molecules leads to a significant conformational heat capacity contribution for high temperatures. Specific results for polyethylene (PE), poly(oxyethylene) (POE), poly(oxymethylene) (POM) and polytetrafluoroethylene (PTFE) are presented as examples. The proposed approach can also be used to provide a more realistic description of heat capacities of protein-water, cellulose-water or starch-water systems.

  17. High energy bursts from a solid state laser operated in the heat capacity limited regime

    DOEpatents

    Albrecht, Georg; George, E. Victor; Krupke, William F.; Sooy, Walter; Sutton, Steven B.

    1996-01-01

    High energy bursts are produced from a solid state laser operated in a heat capacity limited regime. Instead of cooling the laser, the active medium is thermally well isolated. As a result, the active medium will heat up until it reaches some maximum acceptable temperature. The waste heat is stored in the active medium itself. Therefore, the amount of energy the laser can put out during operation is proportional to its mass, the heat capacity of the active medium, and the temperature difference over which it is being operated. The high energy burst capacity of a heat capacity operated solid state laser, together with the absence of a heavy, power consuming steady state cooling system for the active medium, will make a variety of applications possible. Alternately, cooling takes place during a separate sequence when the laser is not operating. Industrial applications include new material working processes.

  18. Debye temperature, thermal expansion, and heat capacity of TcC up to 100 GPa

    SciTech Connect

    Song, T.; Ma, Q.; Tian, J.H.; Liu, X.B.; Ouyang, Y.H.; Zhang, C.L.; Su, W.F.

    2015-01-15

    Highlights: • A number of thermodynamic properties of rocksalt TcC are investigated for the first time. • The quasi-harmonic Debye model is applied to take into account the thermal effect. • The pressure and temperature up to about 100 GPa and 3000 K, respectively. - Abstract: Debye temperature, thermal expansion coefficient, and heat capacity of ideal stoichiometric TcC in the rocksalt structure have been studied systematically by using ab initio plane-wave pseudopotential density functional theory method within the generalized gradient approximation. Through the quasi-harmonic Debye model, in which the phononic effects are considered, the dependences of Debye temperature, thermal expansion coefficient, constant-volume heat capacity, and constant-pressure heat capacity on pressure and temperature are successfully predicted. All the thermodynamic properties of TcC with rocksalt phase have been predicted in the entire temperature range from 300 to 3000 K and pressure up to 100 GPa.

  19. Dependence of the isobaric specific heat capacity of water vapor on the pressure and temperature

    NASA Astrophysics Data System (ADS)

    Vestfálová, Magda; Šafařík, Pavel

    2016-03-01

    The fundamental base for the calculation of the thermodynamic properties of substances is the thermal equation of state and the dependence of some of the basic specific heat capacities on temperature. Dependence of isobaric specific heat capacity on the pressure can already be deduced from these relations. International standards of the properties of water and steam are based on the new scientific formulation IAPWS-95. The equation is in the form of Helmholtz dimensionless function with very much parameters. The aim of this paper is to design the simple dependence of the isobaric specific heat capacity of water vapor on the pressure and temperature in the range in which the steam occurs in the atmospheric moist air.

  20. First-Principles Calculation of Phonon and Schottky Heat Capacities of Plutonium Dioxide

    NASA Astrophysics Data System (ADS)

    Nakamura, Hiroki; Machida, Masahiko; Kato, Masato

    2015-05-01

    Plutonium dioxide (PuO2) is a key ingredient of mixed oxide (MOX) and advanced nuclear fuels. Its thermophysical data is crucial in understanding the high-temperature behaviors of nuclear fuels. In particular, the high-temperature heat capacity is of great importance for their safety and performance analyses. Here, we evaluate the main contributions to the heat capacity of PuO2 from 0 to 1400 K through suitable first-principles calculations. Consequently, we successfully obtain a temperature dependence in good agreement with experimental measurements. This success mainly results from accurate calculations of the Schottky heat capacity caused by the excited levels of f-electrons of Pu. Our calculations resolve the mystery of why previous works failed to reproduce the measurement data. This study extends the possibility of performing simulation-based nuclear-fuel research instead of difficult measurements.

  1. High energy bursts from a solid state laser operated in the heat capacity limited regime

    DOEpatents

    Albrecht, G.; George, E.V.; Krupke, W.F.; Sooy, W.; Sutton, S.B.

    1996-06-11

    High energy bursts are produced from a solid state laser operated in a heat capacity limited regime. Instead of cooling the laser, the active medium is thermally well isolated. As a result, the active medium will heat up until it reaches some maximum acceptable temperature. The waste heat is stored in the active medium itself. Therefore, the amount of energy the laser can put out during operation is proportional to its mass, the heat capacity of the active medium, and the temperature difference over which it is being operated. The high energy burst capacity of a heat capacity operated solid state laser, together with the absence of a heavy, power consuming steady state cooling system for the active medium, will make a variety of applications possible. Alternately, cooling takes place during a separate sequence when the laser is not operating. Industrial applications include new material working processes. 5 figs.

  2. GENERAL: Low-temperature heat capacities and standard molar enthalpy of formation of 4-(2-aminoethyl)-phenol (C8H11NO)

    NASA Astrophysics Data System (ADS)

    Di, You-Ying; Kong, Yu-Xia; Yang, Wei-Wei; Tan, Zhi-Cheng

    2008-09-01

    This paper reports that low-temperature heat capacities of 4-(2-aminoethyl)-phenol (C8H11NO) are measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of heat capacities as a function of the temperature was fitted by the least square method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at the interval of 5 K. The energy equivalent, ɛcalor, of the oxygen-bomb combustion calorimeter has been determined from 0.68 g of NIST 39i benzoic acid to be ɛcalor = (14674.69±17.49)J.K-1. The constant-volume energy of combustion of the compound at T = 298.15 K was measured by a precision oxygen-bomb combustion calorimeter to be ΔcU = -(32374.25±12.93)J.g-1. The standard molar enthalpy of combustion for the compound was calculated to be ΔcHmominus = -(4445.47 ± 1.77) k. J · mol-1 according to the definition of enthalpy of combustion and other thermodynamic principles. Finally, the standard molar enthalpy of formation of the compound was derived to be ΔfHmominus(C8H11NO, s) = -(274.68 ± 2.06) kJ · mol-1, in accordance with Hess law.

  3. Low-temperature molar heat capacities and entropies of MnO2 (pyrolusite), Mn3O4 (hausmanite), and Mn2O3 (bixbyite)

    USGS Publications Warehouse

    Robie, R.A.; Hemingway, B.S.

    1985-01-01

    Pyrolusite (MnO2), hausmanite (Mn3O4), and bixbyite (Mn2O3), are important ore minerals of manganese and accurate values for their thermodynamic properties are desirable to understand better the {p(O2), T} conditions of their formation. To provide accurate values for the entropies of these important manganese minerals, we have measured their heat capacities between approximately 5 and 380 K using a fully automatic adiabatically-shielded calorimeter. All three minerals are paramagnetic above 100 K and become antiferromagnetic or ferrimagnetic at lower temperatures. This transition is expressed by a sharp ??-type anomaly in Cpmo for each compound with Ne??el temperatures TN of (92.2??0.2), (43.1??0.2), and (79.45??0.05) K for MnO2, Mn3O4, and Mn2O3, respectively. In addition, at T ??? 308 K, Mn2O3 undergoes a crystallographic transition, from orthorhombic (at low temperatures) to cubic. A significant thermal effect is associated with this change. Hausmanite is ferrimagnetic below TN and in addition to the normal ??-shape of the heat-capacity maxima in MnO2 and Mn2O3, it has a second rounded maximum at 40.5 K. The origin of this subsidiary bump in the heat capacity is unknown but may be related to a similar "anomalous bump" in the curve of magnetization against temperature at about 39 K observed by Dwight and Menyuk.(1) At 298.15 K the standard molar entropies of MnO2, Mn3O4, and Mn2O3, are (52.75??0.07), (164.1??0.2), and (113.7??0.2) J??K-1??mol-1, respectively. Our value for Mn3O4 is greater than that adopted in the National Bureau of Standards tables(2) by 14 per cent. ?? 1985.

  4. Investigations of temperature dependences of electrical resistivity and specific heat capacity of metals

    NASA Astrophysics Data System (ADS)

    Eser, Erhan; Koç, Hüseyin

    2016-07-01

    In this study, we calculated the electrical resistivity and heat capacities of some ideal metals (Cu, Pt, and Pd) using a method that it employs the statistical model and Debye functions. The method is used to provide a simple and reliable analytical procedure for wide temperature range. The results obtained for the electrical resistivity and heat capacity have been compared with the results in literature. The results obtained at low temperature are in excellent agreement with experimental and theoretical results. Finally the used approximation and analytical method are a useful approach to calculate thermophysical properties of metals.

  5. High accuracy heat capacity measurements through the lambda transition of helium with very high temperature resolution

    NASA Technical Reports Server (NTRS)

    Fairbanks, W. M.; Lipa, J. A.

    1984-01-01

    A measurement of the heat capacity singularity of helium at the lambda transition was performed with the aim of improving tests of the Renormalization Group (RG) predictions for the static thermodynamic behavior near the singularity. The goal was to approach as closely as possible to the lambda-point while making heat capacity measurements of high accuracy. To do this, a new temperature sensor capable of unprecedented resolution near the lambda-point, and two thermal control systems were used. A short description of the theoretical background and motivation is given. The initial apparatus and results are also described.

  6. Heat Capacity of Superfluid (sup 4)He in the Presence of a Heat Current Near T

    NASA Technical Reports Server (NTRS)

    Chui, Talso C. P.; Goodstein, David L.; Harter, Alexa W.; Mukhopadhyay, Ranjan

    1996-01-01

    The thermodynamic theory of superfluid helium in the presence of a heat current is presented. We show that there is a thermodynamic relation between the heat capacity and the expression ps(W), which describes the depression of the superfluid density with the counterflow velocity W. Using this relation we show that the heat capacity of superfluid super4He in the presence of a heat current diverges at a depressed lambda transition temperature, suggesting the possibility of a new second order phase transition where the superfluid wave function is not the order parameter.

  7. a Heat Capacity Study of Para-Hydrogen Monolayers on Graphite.

    NASA Astrophysics Data System (ADS)

    Motteler, Frederick Clark

    The heat capacity of monolayer p-H(,2) adsorbed on graphite foam has been measured over the 0.0631(ANGSTROM)(' -2) to 0.0891(ANGSTROM)('-2) density range and the 2 to 25(DEGREES)K temperature range. Specific heat peaks are observed over almost the entire density range and are similar to those observed for ('4)He and ('3)He monolayers on graphite for similar densities. Low density data (0.0631(ANGSTROM)('-2) to 0.0727(ANGSTROM)(' -2)) contains a heat capacity peak attributed to the commensurate order-disorder transition. At commensurate density. 0.0637(ANGSTROM)(' -2), the peak attains a maximum height of C/Nk(,b) = 11.7 at 21.4(DEGREES)K and may be characterized by the critical exponent (alpha) = 0.33. For temperatures below the order -disorder transition, the commensurate monolayer heat capacity is characterized by Einstein like behavior with (theta)(,E) = 53.4(DEGREES)K. High density data (0.0787(ANGSTROM)('-2) to 0.0815(ANGSTROM)(' -2)) contains a heat capacity peak attributed to the disordering of a close packed triangular incommensurate solid. The incommensurate solid is characterized by its Debye like heat capacity behavior. The density region between the commensurate structure and incommensurate solid (0.0707(ANGSTROM)('-2) to 0.772(ANGSTROM)(' -2)) contains two heat capacity peaks. At about 20(DEGREES)K there is broad rounded remnant of the order-disorder peak. At lower temperatures (6 to 9(DEGREES)K) there is a small, but very sharp heat capacity peak. The peak attains a maximum height of C/Nk(,b) = 0.89 at a density of 0.0727(ANGSTROM)(' -2) and a temperature of 9.54(DEGREES)K. The remnant of the order-disorder transition seen in p-H(,2) data, together with re-examination of ('4)He data indicates that a shoulder-like remnant intersects the melting line. The melting peak of ('4)He undergoes significant change at the intersection point. The low temperature intermediate density region is consistent with a striped phase of domain walls. The sharp low

  8. Temperature-modulated calorimetry of the frequency dependence of the glass transition of poly(ethylene terephthalate) and ....

    SciTech Connect

    Wunderlich, B.; Okazaki, I.

    1997-03-01

    Temperature-modulated differential scanning calorimetry, TMDSC, is new technique that permits to measure the apparent heat capacity vs modulation frequency. The method is briefly described and a quasi- isothermal measurement method is used to derive the kinetic parameters for PET and PS. A first-order kinetics expression was used to describe the approach to equilibrium and point out the limits caused by asymmetry and cooperativity of the kinetics. Use of a complex description of heat capacity and entropy is discussed. Activation energies vary from 75 to 350 kJ/mol, dependent on thermal pretreatment and the preexponential factor is correlated with the activation energy.

  9. Melting by temperature-modulated calorimetry

    SciTech Connect

    Wunderlich, B.; Okazaki, Iwao; Ishikiriyama, Kazuhiko; Boller, A. |

    1997-09-01

    Well-crystallized macromolecules melt irreversibly due to the need of molecular nucleation, while small molecules melt reversibly as long as crystal nuclei are present to assist crystallization. Furthermore, imperfect crystals of low-molar-mass polymers may have a sufficiently small region of metastability between crystallization and melting to show a reversing heat-flow component due to melting of poor crystals followed by crystallization of imperfect crystals which have insufficient time to perfect before the modulation switches to heating and melts the imperfect crystals. Many metals, in turn. melt sharply and reversibly as long as nuclei remain after melting for subsequent crystallization during the cooling cycle. Their analysis is complicated, however, due to thermal conductivity limitations of the calorimeters. Polymers of sufficiently high molar mass, finally, show a small amount of reversible. local melting that may be linked to partial melting of individual molecules. Experiments by temperature-modulated calorimetry and model calculations are presented. The samples measured included poly(ethylene terephthalate)s, poly(ethylene oxide)s, and indium. Two unsolved problems that arose from this research involve the origin of a high, seemingly stable, reversible heat capacity of polymers in the melting region, and a smoothing of melting and crystallization into a close-to-elliptical Lissajous figure in a heat-flow versus sample-temperature plot.

  10. Heat capacity singularity of binary liquid mixtures at the liquid-liquid critical point.

    PubMed

    Méndez-Castro, Pablo; Troncoso, Jacobo; Peleteiro, José; Romaní, Luis

    2013-10-01

    The critical anomaly of the isobaric molar heat capacity for the liquid-liquid phase transition in binary nonionic mixtures is explained through a theory based on the general assumption that their partition function can be exactly mapped into that of the Ising three-dimensional model. Under this approximation, it is found that the heat capacity singularity is directly linked to molar excess enthalpy. In order to check this prediction and complete the available data for such systems, isobaric molar heat capacity and molar excess enthalpy near the liquid-liquid critical point were experimentally determined for a large set of binary liquid mixtures. Agreement between theory and experimental results-both from literature and from present work-is good for most cases. This fact opens a way for explaining and predicting the heat capacity divergence at the liquid-liquid critical point through basically the same microscopic arguments as for molar excess enthalpy, widely used in the frame of solution thermodynamics. PMID:24229116

  11. Conformational Contribution to the Heat Capacity of Interacting System of Carbohydrate Polymer - Water.

    NASA Astrophysics Data System (ADS)

    Pyda, Marek; Wunderlich, Bernhard

    2001-03-01

    Based on the measured heat capacities of amorphous, dry starch and starch with low concentration of water above the partial glass transition of starch, the calculated Cp has been estimated from its vibrational, external, and conformational contributions. The conformational part is evaluated from a fit of the experimental Cp of starch and starch-water, decreased by the vibrational and the external Cp to a one-dimensional Ising-type model for two discrete states, and stiffness, cooperativity, and degeneracy parameters. These differences above the glass transition are interpreted as contributions of different conformational heat capacities from interacting chains of carbohydrate with water. The vibrational contribution was calculated as the heat capacity contributions from group and skeletal vibrations. The external contribution was computed based on thermal expansivity and compressibility as a function of temperature from experimental data of the partial liquid state of both dry starch and starch-water. The calculated and experimental heat capacities of starch-water and dry starch are compared over the whole range of temperatures measurements from 8 to 490 K. NSF, Polymers Program, DMR-9703692, and the Div. of Mat. Sci., BES, DOE at ORNL, managed UT-Batelle, LLC, for the U.S. Department of Energy, under contract number DOE- AC05-00OR22725.

  12. Conformational Heat Capacity of Liquid Biodegradable Polymers in the Absence and Presence Water

    NASA Astrophysics Data System (ADS)

    Pyda, Marek; Nowak-Pyda, Elzbieta

    2007-03-01

    The conformational heat capacity of biodegradable polymers such as amorphous poly(lactic acid) PLA and starch with and without water have been evaluated from a fit of experimental data to a one-dimensional Ising-like model for two discrete states, characterized by parameters linked to stiffness, cooperativity, and degeneracy. For the starch-water system the additional changes in the conformational heat capacity arise from the interaction of the carbohydrate chains with water. The liquid heat capacities at constant pressure Cp, of amorphous PLA and partially liquid state of starch, starch-water have been computed as the sum of vibrational, external, and conformational contributions. The vibrational contribution was calculated as the heat capacity arising from group and skeletal vibrations. The external contribution was estimated from experimental data of the thermal expansivity and compressibility in the liquid state. The experimental liquid Cp agrees with these calculations to better than ±3%. The calculated liquid Cp with the solid Cp was employed in the quantitative thermal analysis of the experimental Cp of biodegradable polymer PLA, starch, and starch-water. Supported by European Union, grant (MIRG-CT-2006-036558), Cargill Dow LLC

  13. Anomalies of low-temperature heat capacity in superconductors with twins

    SciTech Connect

    Gurevich, A.V.; Mints, R.G.

    1989-01-01

    Our earlier paper showed that superconductors with twins may give rise to metastable superconducting domains that differ by /pi/ in the phase of the order parameter. The antiphase domain wall(ADW) separating them contains a plane on which the superconducting gap /Delta/ vanishes. This paper discusses the contribution of electron states localized in ADW to the electron heat capacity C(T).

  14. Magnetic susceptibility and heat capacity of Ce/sub 2/Sn/sub 5/

    SciTech Connect

    Dhar, S.K.; Gschneidner K.A. Jr.; McMasters, O.D.

    1987-03-01

    Low-temperature (1.5--20 K) high-field (0--10 T) heat-capacity and magnetic-susceptibility (1.5--300 K) studies have been carried out on Ce/sub 2/Sn/sub 5/. These studies reveal that Ce/sub 2/Sn/sub 5/ orders magnetically at 3 K and exhibits Curie-Weiss behavior above 120 K with p/sub eff/ = 2.56..mu../sub B/ indicating that Ce is trivalent in Ce/sub 2/Sn/sub 5/. The peak in the heat capacity is suppressed in applied magnetic fields and disappears completely at high fields (>5.4 T) which suggests that the magnetic ordering is antiferromagnetic or ferrimagnetic. The magnetic entropy is about 42% of the theoretical expected entropy for a doublet ground state. The coefficient of the electronic heat capacity, which was derived from extrapolation of the heat-capacity data above the ordering temperature, is 22 mJ/mole-CeX sup 2: . It is suggested that both magnetic Ruderman-Kittel-Kasuya-Yosida and Kondo exchange interactions coexist in this compound.

  15. The Determination of Heat Capacity Ratios in a Simple Open System

    ERIC Educational Resources Information Center

    Holden, Glen L.

    2007-01-01

    A virtually closed system is treated as open and compared to known results. The classic experiment of Clement and Desormes provides the conceptual framework for this open system approach in determining the molar heat capacity ratios, lambda. This alternate view, extends the theoretical treatment beyond the first law of thermodynamics for closed…

  16. Heat capacity of rare-earth cuprates, orthovanadates, and aluminum garnets, gallium garnets, and iron garnets

    NASA Astrophysics Data System (ADS)

    Denisova, L. T.; Kargin, Yu. F.; Denisov, V. M.

    2015-08-01

    The correlation between the heat capacities of rare-earth cuprates, orthovanadates, and garnets with ionic radius R 3+ has been analyzed. It has been shown that the values of C {/p 0} change consistently depending on the radius R 3+ within the corresponding tetrads (La-Nd, Pm-Gd, Gd-Ho, Eu-Lu).

  17. Negative thermal expansion and anomalies of heat capacity of LuB50 at low temperatures

    DOE PAGESBeta

    Novikov, V. V.; Zhemoedov, N. A.; Matovnikov, A. V.; Mitroshenkov, N. V.; Kuznetsov, S. V.; Bud'ko, S. L.

    2015-07-20

    Heat capacity and thermal expansion of LuB50 boride were experimentally studied in the 2–300 K temperature range. The data reveal an anomalous contribution to the heat capacity at low temperatures. The value of this contribution is proportional to the first degree of temperature. It was identified that this anomaly in heat capacity is caused by the effect of disorder in the LuB50 crystalline structure and it can be described in the soft atomic potential model (SAP). The parameters of the approximation were determined. The temperature dependence of LuB50 heat capacity in the whole temperature range was approximated by the summore » of SAP contribution, Debye and two Einstein components. The parameters of SAP contribution for LuB50 were compared to the corresponding values for LuB66, which was studied earlier. Negative thermal expansion at low temperatures was experimentally observed for LuB50. The analysis of the experimental temperature dependence for the Gruneisen parameter of LuB50 suggested that the low-frequency oscillations, described in SAP mode, are responsible for the negative thermal expansion. As a result, the glasslike character of the behavior of LuB50 thermal characteristics at low temperatures was confirmed.« less

  18. Heat capacity of the neutron star inner crust within an extended nuclear statistical equilibrium model

    NASA Astrophysics Data System (ADS)

    Burrello, S.; Gulminelli, F.; Aymard, F.; Colonna, M.; Raduta, Ad. R.

    2015-11-01

    Background: Superfluidity in the crust is a key ingredient for the cooling properties of proto-neutron stars. Present theoretical calculations employ the quasiparticle mean-field Hartree-Fock-Bogoliubov theory with temperature-dependent occupation numbers for the quasiparticle states. Purpose: Finite temperature stellar matter is characterized by a whole distribution of different nuclear species. We want to assess the importance of this distribution on the calculation of heat capacity in the inner crust. Method: Following a recent work, the Wigner-Seitz cell is mapped into a model with cluster degrees of freedom. The finite temperature distribution is then given by a statistical collection of Wigner-Seitz cells. We additionally introduce pairing correlations in the local density BCS approximation both in the homogeneous unbound neutron component, and in the interface region between clusters and neutrons. Results: The heat capacity is calculated in the different baryonic density conditions corresponding to the inner crust, and in a temperature range varying from 100 KeV to 2 MeV. We show that accounting for the cluster distribution has a small effect at intermediate densities, but it considerably affects the heat capacity both close to the outer crust and close to the core. We additionally show that it is very important to consider the temperature evolution of the proton fraction for a quantitatively reliable estimation of the heat capacity. Conclusions: We present the first modelization of stellar matter containing at the same time a statistical distribution of clusters at finite temperature, and pairing correlations in the unbound neutron component. The effect of the nuclear distribution on the superfluid properties can be easily added in future calculations of the neutron star cooling curves. A strong influence of resonance population on the heat capacity at high temperature is observed, which deserves to be further studied within more microscopic calculations.

  19. Akermanite: phase transitions in heat capacity and thermal expansion, and revised thermodynamic data.

    USGS Publications Warehouse

    Hemingway, B.S.; Evans, H.T., Jr.; Nord, G.L., Jr.; Haselton, H.T., Jr.; Robie, R.A.; McGee, J.J.

    1986-01-01

    A small but sharp anomaly in the heat capacity of akermanite at 357.9 K, and a discontinuity in its thermal expansion at 693 K, as determined by XRD, have been found. The enthalpy and entropy assigned to the heat-capacity anomaly, for the purpose of tabulation, are 679 J/mol and 1.9 J/(mol.K), respectively. They were determined from the difference between the measured values of the heat capacity in the T interval 320-365 K and that obtained from an equation which fits the heat-capacity and heat-content data for akermanite from 290 to 1731 K. Heat-capacity measurements are reported for the T range from 9 to 995 K. The entropy and enthalpy of formation of akermanite at 298.15 K and 1 bar are 212.5 + or - 0.4 J/(mol.K) and -3864.5 + or - 4.0 kJ/mol, respectively. Weak satellite reflections have been observed in hk0 single-crystal X-ray precession photographs and electron-diffraction patterns of this material at room T. With in situ heating by TEM, the satellite reflections decreased significantly in intensity above 358 K and disappeared at about 580 K and, on cooling, reappeared. These observations suggest that the anomalies in the thermal behaviour of akermanite are associated with local displacements of Ca ions from the mirror plane (space group P421m) and accompanying distortion of the MgSi2O7 framework.-L.C.C.

  20. Estimation of the standard molal heat capacities, entropies and volumes of 2:1 clay minerals

    NASA Astrophysics Data System (ADS)

    Ransom, Barbara; Helgeson, Harold C.

    1994-11-01

    The dearth of accurate values of the thermodynamic properties of 2:1 clay minerals severely hampers interpretation of their phase relations, the design of critical laboratory experiments and geologically realistic computer calculations of mass transfer in weathering, diagenetic and hydrothermal systems. Algorithms and strategies are described below for estimating to within 2% the standard molal heat capacities, entropies, and volumes of illites, smectites and other 2:1 clay minerals. These techniques can also be used to estimate standard molal thermodynamic properties of fictive endmembers of clay mineral solid solutions. Because 2:1 clay minerals like smectite and vermiculite are always hydrated to some extent in nature, contribution of interlayer H 2O to their thermodynamic properties is considered explicitly in the estimation of the standard molal heat capacities, entropies, and volumes of these minerals. Owing to the lack of accurate calorimetric data from which reliable values of the standard molal heat capacity and entropy of interlayer H 2O can be retrieved, these properties were taken in a first approximation to be equal to those of zeolitic H 2O in analcite. The resulting thermodynamic contributions per mole of interlayer H 2O to the standard molal heat capacity, entropy, and volume of hydrous clay minerals at 1 bar and 25°C are 11.46 cal mol -1, 13.15 cal mol -1 K -1 and 17.22 cm 3 mol, respectively. Estimated standard molal heat capacities, entropies and volumes are given for a suite of smectites and illites commonly used in models of clay mineral and shale diagenesis.

  1. Salt materials testing for a spacecraft adiabatic demagnetization refrigerator

    NASA Technical Reports Server (NTRS)

    Savage, M. L.; Kittel, P.; Roellig, T.

    1990-01-01

    As part of a technology development effort to qualify adiabatic demagnetization refrigerators for use in a NASA spacecraft, such as the Space Infrared Telescope Facility, a study of low temperature characteristics, heat capacity and resistance to dehydration was conducted for different salt materials. This report includes results of testing with cerrous metaphosphate, several synthetic rubies, and chromic potassium alum (CPA). Preliminary results show that CPA may be suitable for long-term spacecraft use, provided that the salt is property encapsulated. Methods of salt pill construction and testing for all materials are discussed, as well as reliability tests. Also, the temperature regulation scheme and the test cryostat design are briefly discussed.

  2. Dynamic heat capacity of the east model and of a bead-spring polymer model.

    SciTech Connect

    McCoy, John Dwane; Brown, Jonathan R.; Adolf, Douglas Brian

    2011-10-01

    In this report we have presented a brief review of the glass transition and one means of characterizing glassy materials: linear and nonlinear thermodynamic oscillatory experiments to extract the dynamic heat capacity. We have applied these methods to the east model (a variation of the Ising model for glass forming systems) and a simple polymeric system via molecular dynamics simulation, and our results match what is seen in experiment. For the east model, since the dynamics are so simple, a mathematical model is developed that matches the simulated dynamics. For the polymeric system, since the system is a simulation, we can instantaneously 'quench' the system - removing all vibrational energy - to separate the vibrational dynamics from dynamics associated with particle rearrangements. This shows that the long-time glassy dynamics are due entirely to the particle rearrangements, i.e. basin jumping on the potential energy landscape. Finally, we present an extension of linear dynamic heat capacity to the nonlinear regime.

  3. Theory and simulation of the dynamic heat capacity of the east Ising model.

    PubMed

    Brown, Jonathan R; McCoy, John D; Borchers, Brian

    2010-08-14

    A recently developed methodology for the calculation of the dynamic heat capacity from simulation is applied to the east Ising model. Results show stretched exponential relaxation with the stretching exponent, beta, decreasing with decreasing temperature. For low temperatures, the logarithm of the relaxation time is approximately proportional to the inverse of the temperature squared, which is the theoretical limiting behavior predicted by theories of facilitated dynamics. In addition, an analytical approach is employed where the overall relaxation is a composite of relaxation processes of subdomains, each with their own characteristic time. Using a Markov chain method, these times are computed both numerically and in closed form. The Markov chain results are seen to match the simulations at low temperatures and high frequencies. The dynamics of the east model are tracked very well by this analytic procedure, and it is possible to associate features of the spectrum of the dynamic heat capacity with specific domain relaxation events. PMID:20707576

  4. High-temperature heat capacity of Co3O4 spinel: thermally induced spin unpairing transition

    USGS Publications Warehouse

    Mocala, K.; Navrotsky, A.; Sherman, David M.

    1992-01-01

    A strong anomaly was found in the heat capacity of Co3O4 between 1000 K and the decomposition temperature. This anomaly is not related to the decomposition of Co3O4 to CoO. The measured entropy of transition, ??S=46??4 J mol-1 K-1 of Co3O4, supports the interpretation that this anomaly reflects a spin unpairing transition in octahedrally coordinated Co3+ cations. Experimental values of heat capacity, heat content and entropy of Co3O4 in the high temperature region are provided. The enthalpy of the spin unpairing transition is 53??4 kJ mol-1 of Co3O4. ?? 1992 Springer-Verlag.

  5. Phonon Mechanisms for Excess Heat Capacity in Membrane Isolated Superconducting Transition Edge Sensors

    NASA Technical Reports Server (NTRS)

    Chervenak, James A.

    2012-01-01

    The mechanics of phonon transport in membrane-isolated superconducting transition edge sensors is discussed. Surveys of the literature on this type of sensor reveal a number of designs with excess heat capacity and a smaller subset that exhibit decoupling of the superconducting film from the underlying dielectric. A simple model is addressed in which the membrane, despite its thermal isolation, fails to fully thermalize to the temperature of the metal film heating it. A population of phonons exists which is emitted by the metal film, partially thermalizes the dielectric and is then reabsorbed in the metal film without escaping from the device structure to the thermal bath. The size of this population and its contribution to the heat capacity are estimated for several device scenarios.

  6. Influence of the potential range on the heat capacity of 13-atom Morse clusters

    NASA Astrophysics Data System (ADS)

    Moseler, Michael; Nordiek, Johannes

    1999-10-01

    Heat capacity curves as a function of temperature were studied for 13-atom clusters bound by Morse potentials with different range parameters ρ0 ɛ \\{3,4,5,6,14\\} using J-walking Monte Carlo. Decreasing the range of the pair potential (i.e., increasing ρ0) increases the peak of the heat capacity in the melting transition region and decreases the boiling temperature. For ρ0=14 the melting and boiling peaks merge. The short-range potential favors a transition from the catchment region of the icosahedral ground state to the basins of higher minima. On the other hand, clusters bound by the long-range potential (ρ0=3) remain in the ground-state basin even for elevated temperatures, which can be explained by the destabilization of important higher minima for ρ0<4.

  7. Low-Temperature Heat Capacity and Localized Vibrational Modes in Natural and Synthetic Tetrahedrites

    SciTech Connect

    Lara-Curzio, Edgar; May, Andrew F; Delaire, Olivier A; McGuire, Michael A; Lu, Xu; Li, Cheng-Yun; Case, Eldon D; Morelli, Donold

    2014-01-01

    The heat capacity of natural (Cu12-x (Fe, Zn, Ag)x(Sb, As)4S13) and synthetic (Cu12-xZnxSb4S13 with x=0, 1, 2) tetrahedrite compounds was measured between 2K and 380K. It was found that the temperature dependence of the heat capacity can be described using a Debye term and three Einstein oscillators with characteristic temperatures that correspond to energies of ~1.0 meV, ~2.8 meV and ~8.4 meV. The existence of localized vibration modes, which are assigned to the displacements of the trigonally coordinated Cu atoms in the structure, is discussed in the context of anharmonicity and its effect on the low lattice thermal conductivity exhibited by these compounds.

  8. Heat capacity of {sup 4}He in Vycor near the critical coverage

    SciTech Connect

    Van Keuls, F.W.; Crowell, P.A.; Reppy, J.D.

    1993-04-01

    The authors report heat capacity measurements of {sup 4}He films in Vycor near the critical coverage. The goal of these studies is to determine whether the low temperature phase at coverages below the onset of superfluidity is a glass or an insulator with a gap. The data cover a temperature range of 5 mK to 600 mK. At the lowest temperatures, a CMN DC-SQUID thermometer is used. This thermometer contains 3 mg of CMN to minimize its heat capacity. The sensitivity at 10 mK is better than 500 pK/{radical}Hz. The CMN powder is mixed with a Ag sinter to improve thermal conductivity. The resistance thermometers mounted on the cell are found to be reliable down to 14 mK.

  9. Isobaric Heat Capacity, Isothermal Compressibility and Fluctuational Properties of 1-Bromoalkanes

    NASA Astrophysics Data System (ADS)

    Korotkovskii, V. I.; Ryshkova, O. S.; Neruchev, Yu. A.; Goncharov, A. L.; Postnikov, E. B.

    2016-06-01

    We present results of the experimental measurements of the isobaric heat capacity for 1-bromohexane, 1-bromoheptane, 1-bromooctane, 1-bromononane, 1-bromodecane, 1-bromoundecane, 1-bromododecane and 1-bromotetradecane at normal pressure and the speed of sound and the density for 1-bromotetradecane within the temperature range 298.15-423.15 K. These data on the isobaric heat capacity and the literature-based reference data for the density and the speed of sound were used to calculate the isothermal compressibility and the inverse reduced fluctuations. Based on the comparison of the results for pure n-alkanes and α ,ω -dibromoalkanes, we discuss the influence of bromine atom on the volume fluctuations.

  10. A new approach for non-contact calorimetry: system identification using pseudo-white noise perturbation

    NASA Astrophysics Data System (ADS)

    Schetelat, Pascal; Etay, Jacqueline

    2011-07-01

    This paper presents a new technique for non-contact calorimetry measurement of specific heat capacity and thermal conductivity. Based on pseudo-white noise modulation and system identification, commonly used in electronics and communication engineering, this procedure can be used to measure the transfer function of the sample temperature variation due to heating power variation. The heat capacity and internal heat transfer coefficient are then determined using the equivalence between the identified transfer functions of the temperatures measured at two locations and the analytical model proposed by Fecht and Johnson (Rev Sci Instrum 62:1299-1303, 1991) and Wunderlich and Fecht (Measur Sci Technol 16:402-416, 2005). This inverse problem is solved numerically using a Gauss-Seidel algorithm. A numerical simulation of a non-contact modulated calorimetry experiment is used to demonstrate the relevance of this new technique for indirect measurement of the heat capacity and heat transfer coefficients of solid samples presenting large Biot numbers ( Bi > 0.4).

  11. Heat capacity and thermal expansion of icosahedral lutetium boride LuB66

    SciTech Connect

    Novikov, V V; Avdashchenko, D V; Matovnikov, A V; Mitroshenkov, N V; Bud’ko, S L

    2014-01-07

    The experimental values of heat capacity and thermal expansion for lutetium boride LuB66 in the temperature range of 2-300 K were analysed in the Debye-Einstein approximation. It was found that the vibration of the boron sub-lattice can be considered within the Debye model with high characteristic temperatures; low-frequency vibration of weakly connected metal atoms is described by the Einstein model.

  12. Restrictions on linear heat capacities from Joule-Brayton maximum-work cycle efficiency

    NASA Astrophysics Data System (ADS)

    Angulo-Brown, F.; Gonzalez-Ayala, Julian; Arias-Hernandez, L. A.

    2014-02-01

    This paper discusses the possibility of using the Joule-Brayton cycle to determine the accessible value range for the coefficients a and b of the heat capacity at constant pressure Cp, expressed as Cp=a+bT (with T the absolute temperature) by using the Carnot theorem. This is made for several gases which operate as the working fluids. Moreover, the landmark role of the Curzon-Ahlborn efficiency for this type of cycle is established.

  13. Low temperature heat capacity of permanently densified SiO2 glasses

    NASA Astrophysics Data System (ADS)

    Carini, Giovanni; Carini, Giuseppe; Cosio, Daniele; D'Angelo, Giovanna; Rossi, Flavio

    2016-03-01

    A study of low temperature specific heat capacity (1-30 K) has been performed on samples of vitreous SiO2, which have been compacted under pressures up to 8 GPa to explore different glassy phases having growing density. Increasing densification by more than 21% leads to a progressive reduction of the specific heat capacity Cp and to a shift from 10 K up to about 17 K of the broad hump, the calorimetric Boson peak (BP), observed above 1 K in a Cp(T)/T3 vs. T plot. The revealed changes are not accounted for by the modifications of the elastic continuum, implying a nature of additional vibrations at variance with the extended sound waves. Increasing atomic packing of the glassy network leads to a progressively decreasing excess heat capacity over that of α-quartz, a crystalline polymorph of SiO2. By using the low-frequency Raman intensity measured in these glasses to determine the temperature dependence of the low temperature heat capacity, it has been evaluated the density of low-frequency vibrational states. The observations are compared with some theoretical pictures explaining the nature of the BP, disclosing qualitative agreement with the predictions of the Soft Potential Model and the results of a simulation study concerning the vibrations of jammed particles. This finding leads to evaluate a nanometer length scale which suggests the existence of poorly packed domains formed from several n-membered rings involving SiO4 tetrahedra. These soft regions are believed to be the main source of low-frequency vibrations giving rise to the BP.

  14. Heat capacity measurements of sub-nanoliter volumes of liquids using bimaterial microchannel cantilevers

    NASA Astrophysics Data System (ADS)

    Khan, M. F.; Miriyala, N.; Lee, J.; Hassanpourfard, M.; Kumar, A.; Thundat, T.

    2016-05-01

    Lab-on-a-Chip compatible techniques for thermal characterization of miniaturized volumes of liquid analytes are necessary in applications such as protein blotting, DNA melting, and drug development, where samples are either rare or volume-limited. We developed a closed-chamber calorimeter based on a bimaterial microchannel cantilever (BMC) for sub-nanoliter level thermal analysis. When the liquid-filled BMC is irradiated with infrared (IR) light at a specific wavelength, the IR absorption by the liquid analyte results in localized heat generation and the subsequent deflection of the BMC, due to a thermal expansion mismatch between the constituent materials. The time constant of the deflection, which is dependent upon the heat capacity of the liquid analyte, can be directly measured by recording the time-dependent bending of the BMC. We have used the BMC to quantitatively measure the heat capacity of five volatile organic compounds. With a deflection noise level of ˜10 nm and a signal-to-noise ratio of 68:1, the BMC offers a sensitivity of 30.5 ms/(J g-1 K-1) and a resolution of 23 mJ/(g K) for ˜150 pl liquid for heat capacity measurements. This technique can be used for small-scale thermal characterization of different chemical and biological samples.

  15. Inverse Identification of Temperature-Dependent Volumetric Heat Capacity by Neural Networks

    NASA Astrophysics Data System (ADS)

    Czél, Balázs; Woodbury, Keith A.; Gróf, Gyula

    2013-02-01

    An artificial neural network (NN)-based solution of the inverse heat conduction problem of identifying the temperature-dependent volumetric heat capacity function of a solid material is presented in this paper. The inverse problem was defined according to the evaluation of the BICOND thermophysical property measurement method. The volumetric heat capacity versus temperature function is to be determined using the measured transient temperature history of a single sensor. In this study, noiseless and noisy artificial measurements were generated by the numerical solution of the corresponding direct heat conduction problem. The inverse problem was solved by back-propagation and radial basis function type neural networks applying the whole history mapping approach. The numerical tests included the comparison of two different data representations of the network inputs (i.e., temperature vs. time and time vs. temperature) and accuracy analysis of the two network types with noiseless and noisy inputs. Based on the results presented, it can be stated that feed-forward NNs are powerful tools in a non-iterative solution of function estimation inverse heat conduction problems and they are likely to be very effective in evaluation of real measured temperature histories to determine the volumetric heat capacity as an arbitrary function of temperature.

  16. Kinetics of solid-gas reactions characterized by scanning AC nano-calorimetry with application to Zr oxidation

    SciTech Connect

    Xiao, Kechao; Lee, Dongwoo; Vlassak, Joost J.

    2014-10-27

    Scanning AC nano-calorimetry is a recently developed experimental technique capable of measuring the heat capacity of thin-film samples of a material over a wide range of temperatures and heating rates. Here, we describe how this technique can be used to study solid-gas phase reactions by measuring the change in heat capacity of a sample during reaction. We apply this approach to evaluate the oxidation kinetics of thin-film samples of zirconium in air. The results confirm parabolic oxidation kinetics with an activation energy of 0.59 ± 0.03 eV. The nano-calorimetry measurements were performed using a device that contains an array of micromachined nano-calorimeter sensors in an architecture designed for combinatorial studies. We demonstrate that the oxidation kinetics can be quantified using a single sample, thus enabling high-throughput mapping of the composition-dependence of the reaction rate.

  17. Thermal Properties of Silk Fibroin Using Fast Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Cebe, Peggy; Partlow, Benjamin; Kaplan, David; Wurm, Andreas; Zhuravlev, Evgeny; Schick, Christoph

    We performed fast scanning chip-based calorimetry of silk protein using the Mettler Flash DSC1. We suggest the methodology by which to obtain quantitative information on the very first scan to high temperature, including the melting endotherm of the beta pleated sheets. For proteins, this first scan is the most important one, because the crystalline secondary structural features, the beta pleated sheets, melt after the first heating and cannot be thermally reintroduced. To obtain high quality data, the samples must be treated to drying and enthalpy relaxation sequences. The heat flow rates in heating and cooling must be corrected for asymmetric heat loses. We evaluate methods to obtain an estimate of the sample mass, finally choosing internal calibration using the known heat capacity increment at the glass transition. We report that even heating at rates of 2000 K/s, thermal degradation of silk cannot be totally avoided, though it can be minimized. Using a set of nineteen samples, we successfully determine the liquid state heat capacity of silk as: Cpliquid (T) = (1.98 +0.06) J/gK + T (6.82 +1.4) x10-4 J/gK2. Methods for estimation of the sample mass will be presented and compared. National Science Foundation, Polymers Program DMR-1206010; DAAD; Tufts Faculty Supported Leave.

  18. Wireless adiabatic power transfer

    SciTech Connect

    Rangelov, A.A.; Suchowski, H.; Silberberg, Y.; Vitanov, N.V.

    2011-03-15

    Research Highlights: > Efficient and robust mid-range wireless energy transfer between two coils. > The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. > Wireless energy transfer is insensitive to any resonant constraints. > Wireless energy transfer is insensitive to noise in the neighborhood of the coils. - Abstract: We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.

  19. Isothermal titration calorimetry of ion-coupled membrane transporters

    PubMed Central

    SeCheol, Oh

    2015-01-01

    Binding of ligands, ranging from proteins to ions, to membrane proteins is associated with absorption or release of heat that can be detected by isothermal titration calorimetry (ITC). Such measurements not only provide binding affinities but also afford direct access to thermodynamic parameters of binding - enthalpy, entropy and heat capacity. These parameters can be interpreted in a structural context, allow discrimination between different binding mechanisms and guide drug design. In this review, we introduce advantages and limitations of ITC as a methodology to study molecular interactions of membrane proteins. We further describe case studies where ITC was used to analyze thermodynamic linkage between ions and substrates in ion-coupled transporters. Similar type of linkage analysis will likely be applicable to a wide range of transporters, channels, and receptors. PMID:25676707

  20. Adiabatically driven Brownian pumps.

    PubMed

    Rozenbaum, Viktor M; Makhnovskii, Yurii A; Shapochkina, Irina V; Sheu, Sheh-Yi; Yang, Dah-Yen; Lin, Sheng Hsien

    2013-07-01

    We investigate a Brownian pump which, being powered by a flashing ratchet mechanism, produces net particle transport through a membrane. The extension of the Parrondo's approach developed for reversible Brownian motors [Parrondo, Phys. Rev. E 57, 7297 (1998)] to adiabatically driven pumps is given. We demonstrate that the pumping mechanism becomes especially efficient when the time variation of the potential occurs adiabatically fast or adiabatically slow, in perfect analogy with adiabatically driven Brownian motors which exhibit high efficiency [Rozenbaum et al., Phys. Rev. E 85, 041116 (2012)]. At the same time, the efficiency of the pumping mechanism is shown to be less than that of Brownian motors due to fluctuations of the number of particles in the membrane. PMID:23944411

  1. Calorimetry of epitaxial thin films.

    PubMed

    Cooke, David W; Hellman, F; Groves, J R; Clemens, B M; Moyerman, S; Fullerton, E E

    2011-02-01

    Thin film growth allows for the manipulation of material on the nanoscale, making possible the creation of metastable phases not seen in the bulk. Heat capacity provides a direct way of measuring thermodynamic properties of these new materials, but traditional bulk calorimetric techniques are inappropriate for such a small amount of material. Microcalorimetry and nanocalorimetry techniques exist for the measurements of thin films but rely on an amorphous membrane platform, limiting the types of films which can be measured. In the current work, ion-beam-assisted deposition is used to provide a biaxially oriented MgO template on a suspended membrane microcalorimeter in order to measure the specific heat of epitaxial thin films. Synchrotron x-ray diffraction showed the biaxial order of the MgO template. X-ray diffraction was also used to prove the high quality of epitaxy of a film grown onto this MgO template. The contribution of the MgO layer to the total heat capacity was measured to be just 6.5% of the total addenda contribution. The heat capacity of a Fe(.49)Rh(.51) film grown epitaxially onto the device was measured, comparing favorably to literature data on bulk crystals. This shows the viability of the MgO∕SiN(x)-membrane-based microcalorimeter as a way of measuring the thermodynamic properties of epitaxial thin films. PMID:21361612

  2. Thermodynamic properties of zeolites: low-temperature heat capacities and thermodynamic functions for phillipsite and clinoptilolite. Estimates of the thermochemical properties of zeolitic water at low temperature.

    USGS Publications Warehouse

    Hemingway, B.S.; Robie, R.A.

    1984-01-01

    Measured heat capacities between 15 and 305 K and calculated heat capacities, entropies, enthalpy functions and Gibbs energy functions are reported and analysed for phillipsite and clinoptilolite. - J.A.Z.

  3. Parallelizable adiabatic gate teleportation

    NASA Astrophysics Data System (ADS)

    Nakago, Kosuke; Hajdušek, Michal; Nakayama, Shojun; Murao, Mio

    2015-12-01

    To investigate how a temporally ordered gate sequence can be parallelized in adiabatic implementations of quantum computation, we modify adiabatic gate teleportation, a model of quantum computation proposed by Bacon and Flammia [Phys. Rev. Lett. 103, 120504 (2009), 10.1103/PhysRevLett.103.120504], to a form deterministically simulating parallelized gate teleportation, which is achievable only by postselection. We introduce a twisted Heisenberg-type interaction Hamiltonian, a Heisenberg-type spin interaction where the coordinates of the second qubit are twisted according to a unitary gate. We develop parallelizable adiabatic gate teleportation (PAGT) where a sequence of unitary gates is performed in a single step of the adiabatic process. In PAGT, numeric calculations suggest the necessary time for the adiabatic evolution implementing a sequence of L unitary gates increases at most as O (L5) . However, we show that it has the interesting property that it can map the temporal order of gates to the spatial order of interactions specified by the final Hamiltonian. Using this property, we present a controlled-PAGT scheme to manipulate the order of gates by a control qubit. In the controlled-PAGT scheme, two differently ordered sequential unitary gates F G and G F are coherently performed depending on the state of a control qubit by simultaneously applying the twisted Heisenberg-type interaction Hamiltonians implementing unitary gates F and G . We investigate why the twisted Heisenberg-type interaction Hamiltonian allows PAGT. We show that the twisted Heisenberg-type interaction Hamiltonian has an ability to perform a transposed unitary gate by just modifying the space ordering of the final Hamiltonian implementing a unitary gate in adiabatic gate teleportation. The dynamics generated by the time-reversed Hamiltonian represented by the transposed unitary gate enables deterministic simulation of a postselected event of parallelized gate teleportation in adiabatic

  4. Laser-Material Interaction Studies Utilizing the Solid-State Heat Capacity Laser

    SciTech Connect

    Yamamoto, R; Parker, J; Boley, C; Cutter, K; Fochs, S; Rubenchik, A

    2007-04-19

    A variety of laser-material interaction experiments have been conducted at Lawrence Livermore National Laboratory (LLNL) utilizing the solid-state heat capacity laser (SSHCL). For these series of experiments, laser output power is 25kW, on-target laser spot sizes of up to 16 cm by 16 cm square, with air speeds of approximately 100 meters per second flowing across the laser-target interaction surface as shown in Figure 1. The empirical results obtained are used to validate our simulation models.

  5. Reduction of heat capacity and phonon group velocity in silicon nanowires

    NASA Astrophysics Data System (ADS)

    Marchbanks, Christopher; Wu, Zhigang

    2015-02-01

    We report on ab initio linear-response calculations of lattice vibrations in narrow silicon nanowires on the order of 1 nm along the [001], [011], and [111] growth directions. The confinement and nanowire structure substantially alter phonon distributions, resulting in an 15% to 23% reduction in heat capacity and an averaged decrease of 31% in acoustic velocities compared with bulk silicon. Based on these, we estimate an improvement up to 4 fold on thermoelectric performance due solely to the modified lattice vibrations in narrow silicon nanowires over bulk silicon.

  6. Restrictions on linear heat capacities from Joule-Brayton maximum-work cycle efficiency.

    PubMed

    Angulo-Brown, F; Gonzalez-Ayala, Julian; Arias-Hernandez, L A

    2014-02-01

    This paper discusses the possibility of using the Joule-Brayton cycle to determine the accessible value range for the coefficients a and b of the heat capacity at constant pressure C(p), expressed as C(p) = a + bT (with T the absolute temperature) by using the Carnot theorem. This is made for several gases which operate as the working fluids. Moreover, the landmark role of the Curzon-Ahlborn efficiency for this type of cycle is established. PMID:25353449

  7. The effect of mechanical activation on the heat capacity of powdered tungsten

    NASA Astrophysics Data System (ADS)

    Malkin, A. I.; Kiselev, M. R.; Klyuev, V. A.; Loznetsova, N. N.; Toporov, Yu. P.

    2012-06-01

    We have studied the heat capacity ( C p ) of a mechanically activated tungsten powder. It is established that the mechanical processing leads to an increase in C p of the metal powder at low temperatures and modifies the character of the temperature dependence of this parameter. The dependences of C p and its heating-induced variation on the treatment duration have been determined. It is concluded that the observed effects are related to the accumulation of defects in the metal grain volume during mechanical activation and their annealing in the course of heating.

  8. Evaluating near-surface soil moisture using Heat Capacity Mapping Mission data

    NASA Technical Reports Server (NTRS)

    Heilman, J. L.; Moore, D. G.

    1982-01-01

    Four dates of Heat Capacity Mapping Mission (HCMM) data were analyzed in order to evaluate HCMM thermal data use in estimating near-surface soil moisture in a complex agricultural landscape. Because of large spatial and temporal ground cover variations, HCMM radiometric temperatures alone did not correlate with soil water content. The radiometric temperatures consisted of radiance contributions from different canopies and their respective soil backgrounds. However, when surface soil temperatures were empirically estimated from HCMM temperatures and percent cover of each pixel, a highly significant correlation was obtained between the estimated soil temperatures and near-surface soil water content.

  9. Snow hydrology studies using data from the Heat Capacity Mapping Mission

    NASA Technical Reports Server (NTRS)

    Barnes, J. C.; Bowley, C. J.

    1981-01-01

    This paper describes a study of the snow hydrology application of thermal infrared (IR) data from the Heat Capacity Mapping Mission (HCMM) satellite. The HCMM data in both imagery and digital tape formats are analyzed for two study areas: the Salt-Verde Watershed in central Arizona and the southern Sierra Nevada in California. The analysis procedures are described, including the development of a unique contour plotting program that makes it possible to overlay HCMM thermal contours directly onto the visible channel imagery. The results indicate that satellite thermal-IR data can provide the hydrologist with additional useful information on snow cover.

  10. Very high-resolution heat-capacity measurements near the lambda point of helium

    NASA Technical Reports Server (NTRS)

    Lipa, J. A.; Chui, T. C. P.

    1983-01-01

    New measurements of the heat capacity of a sample of helium 3-mm high are reported, which extend to within 5 x 10 to the -8th deg of the lambda transition at the vapor pressure. From an analysis of the results allowing for the effect of gravity, the values -0.0127 + or - 0.0026 (2 sigma) for the exponent alpha (= alpha-prime) and 1,058 + or - 0.004 for the leading singularity ratio A/A-prime are obtained. These values are in closer agreement with the theoretical predictions than those reported previously.

  11. The lambda point experiment in microgravity. [He heat capacity close to phase transition point

    NASA Technical Reports Server (NTRS)

    Lipa, J. A.; Chui, T. C. P.; Marek, D.

    1987-01-01

    An experiment for performing high-resolution measurements of the heat capacity singularity at the lambda point of helium in microgravity conditions is described. By obtaining such measurements in space, it is expected that the intrinsic distortion of the transition would be reduced by at least two orders of magnitude, allowing the theory of cooperative phase transitions to be more effectively tested. Technology developments for the lambda point experiment include a new high-resolution thermometer, an advanced thermal control system, and a reusable flight-qualified superfluid helium dewar.

  12. Analytical evaluation of thermal conductance and heat capacities of one-dimensional material systems

    SciTech Connect

    Saygi, Salih

    2014-02-15

    We theoretically predict some thermal properties versus temperature dependence of one dimensional (1D) material nanowire systems. A known method is used to provide an efficient and reliable analytical procedure for wide temperature range. Predicted formulas are expressed in terms of Bloch-Grüneisen functions and Debye functions. Computing results has proved that the expressions are in excellent agreement with the results reported in the literature even if it is in very low dimension limits of nanowire systems. Therefore the calculation method is a fully predictive approach to calculate thermal conductivity and heat capacities of nanowire material systems.

  13. High energy bursts from a solid state laser operated in the heat capacity limited regime

    SciTech Connect

    Albrecht, G.; George, E.V.; Krupke, W.

    1994-12-31

    Solid state laser technology is a very well developed field and numerous embodiments and modes of operation have been demonstrated. A more recent development has been the pumping of a solid state laser active medium with an array of diode lasers (diode pumping, for short). These diode pump packages have previously been developed to pump solid state lasers with good efficiency, but low average power. This invention is a method and the resulting apparatus for operating a solid state laser in the heat capacity mode. Instead of cooling the laser, the active medium will heat up until it reaches some maximum acceptable temperature. The waste heat is stored in the active medium itself.

  14. Formation enthalpies and heat capacities of rear earth titanates: RE{sub 2}TiO{sub 5} (RE=La, Nd and Gd)

    SciTech Connect

    Hayun, Shmuel; Navrotsky, Alexandra

    2012-03-15

    The formation enthalpies and heat capacities of orthorhombic rare earth titanates, RE{sub 2}TiO{sub 5} (RE=La, Nd and Gd), have been studied by high temperature differential scanning calorimetry (300-1473 K) and oxide-melt solution calorimetry. The RE{sub 2}TiO{sub 5} samples are stable in enthalpy with respect to their oxides and the pyrochlore RE{sub 2}Ti{sub 2}O{sub 7} phase. The general trend that has been demonstrated in other RE-ternary systems; decreasing thermodynamic stability with decreasing R{sub A}/R{sub B} was found to be valid for the RE{sub 2}TiO{sub 5}, and their enthalpies of formation from oxides become more negative with increasing RE{sup 3+} ionic radius. - Graphical abstract: Normalized enthalpy of formation for one RE{sup 3+} cation from the oxides for several RE ternary oxide systems vs. the cation radius ratio R{sub A}/R{sub B} (A=RE, B=Ti, Zr, P). All the RE ternary oxide systems are stable relative to constituent oxides, with increasing stability as R{sub A}/R{sub B} increases. The Roman numerals above the cations represent the coordination number. Highlights: Black-Right-Pointing-Pointer Formation enthalpies and heat capacities of RE{sub 2}TiO{sub 5} (RE=La, Nd and Gd) were determined. Black-Right-Pointing-Pointer Enthalpies of formation of RE{sub 2}TiO{sub 5} from oxides become more negative with increasing RE{sup 3+} ionic radius. Black-Right-Pointing-Pointer RE{sub 2}TiO{sub 5} phases are stable in enthalpy with respect to their oxides and the pyrochlore RE{sub 2}Ti{sub 2}O{sub 7} phases. Black-Right-Pointing-Pointer Thermodynamic stability of orthorhombic RE{sub 2}TiO{sub 5} decrease with increasing R{sub B} to R{sub A} ratio.

  15. Heat capacity, enthalpy of mixing, and thermal conductivity of Hg(1-x)Cd(x)Te pseudobinary melts

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua

    1986-01-01

    Heat capacity and enthalpy of mixing of Hg(1-x)Cd(x)Te pseudobinary melts were calculated assuming an associated solution model for the liquid phase. The thermal conductivity of the pseudobinary melts for x = 0, 0.05, 0.1, and 0.2 was then calculated from the heat capacity values and the experimental values of thermal diffusivity and density for these melts. The thermal conductivity for the pseudobinary solid solution is also discussed.

  16. New approaches to the simulation of heat-capacity curves and phase diagrams of pseudobinary phospholipid mixtures.

    PubMed Central

    Johann, C; Garidel, P; Mennicke, L; Blume, A

    1996-01-01

    A simulation program using least-squares minimization was developed to calculate and fit heat capacity (cp) curves to experimental thermograms of dilute aqueous dispersions of phospholipid mixtures determined by high-sensitivity differential scanning calorimetry. We analyzed cp curves and phase diagrams of the pseudobinary aqueous lipid systems 1,2-dimyristoyl-sn-glycero-3-phosphatidylglycerol/ 1,2-dipalmitoyl-sn-glycero-3phosphatidylcholine (DMPG/DPPC) and 1,2-dimyristoyl-sn-glycero-3-phosphatidic acid/1, 2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DMPA/DPPC) at pH 7. The simulation of the cp curves is based on regular solution theory using two nonideality parameters rho g and rho l for symmetric nonideal mixing in the gel and the liquid-crystalline phases. The broadening of the cp curves owing to limited cooperativity is incorporated into the simulation by convolution of the cp curves calculated for infinite cooperativity with a broadening function derived from a simple two-state transition model with the cooperative unit size n = delta HVH/delta Hcal as an adjustable parameter. The nonideality parameters and the cooperative unit size turn out to be functions of composition. In a second step, phase diagrams were calculated and fitted to the experimental data by use of regular solution theory with four different model assumptions. The best fits were obtained with a four-parameter model based on nonsymmetric, nonideal mixing in both phases. The simulations of the phase diagrams show that the absolute values of the nonideality parameters can be changed in a certain range without large effects on the shape of the phase diagram as long as the difference of the nonideality parameters for rho g for the gel and rho l for the liquid-crystalline phase remains constant. The miscibility in DMPG/DPPC and DMPA/DPPC mixtures differs remarkably because, for DMPG/DPPC, delta rho = rho l -rho g is negative, whereas for DMPA/DPPC this difference is positive. For DMPA/DPPC, this

  17. Magnetic Contribution to Heat Capacity and Entropy of Nicke Ferrite (NiFe2O4)

    SciTech Connect

    S Ziemniak, L Anovitz, R Castelli

    2005-12-15

    The heat capacity of nickel ferrite was measured as a function of temperature over the range from 50 to 1200 C using a differential scanning calorimeter. A thermal anomaly was observed at 584.9 C, the expected Curie temperature, T{sub c}. The observed behavior was interpreted by recognizing the sum of three contributions: (1) lattice (vibrational), (2) a spin wave (magnetic) component and (3) a {lambda}-transition (antiferromagnetic-paramagnetic transition) at the Curie temperature. The first was modeled using vibrational frequencies derived from an experimentally-based ir absorption spectrum, while the second was modeled using a spin wave analysis that provided a T{sup 3/2} dependency in the low temperature limit, but incorporated an exchange interaction between cation spins in the octahedral and tetrahedral sites at elevated temperatures, as first suggested by Grimes [15]. The {lambda}-transition was fitted to an Inden-type model which consisted of two truncated power law series in dimensionless temperature (T/T{sub c}). Exponential equality was observed below and above T{sub c}, indicating symmetry about the Curie temperature. Application of the methodology to existing heat capacity data for other transition metal ferrites (AFe{sub 2}O{sub 4}, A = Fe, Co) revealed the same exponential equality, i.e., m = n = 5.

  18. A room-temperature phase transition in maximum microcline - Heat capacity measurements

    USGS Publications Warehouse

    Openshaw, R.E.; Hemingway, B.S.; Robie, R.A.; Krupka, K.M.

    1979-01-01

    The thermal hysteresis in heat capacity measurements recently reported (Openshaw et al., 1976) for a maximum microcline prepared from Amelia albite by fused-salt ion-exchange is described in detail. The hysteresis is characterized by two limiting and reproducible curves which differ by 1% of the measured heat capacities. The lower curve, denoted curve B, represents the values obtained before the sample had been cooled below 300 K. Measurements made immediately after cooling the sample below 250 K followed a second parallel curve, curve A, to at least 370 K. Values intermediate to the two limiting curves were also obtained. The transitions from the B to the A curve were rapid and observed to occur three times. The time required to complete the transition from the A to the B curve increased from 39 h to 102 h in the two times it was observed to occur. The hysteresis is interpreted as evidence of a phase change in microcline at 300??10 K The heat effect associated with the phase change has not been evaluated. ?? 1979 Springer-Verlag.

  19. Heat Capacity Mapping Radiometer (HCMR) data processing algorithm, calibration, and flight performance evaluation

    NASA Technical Reports Server (NTRS)

    Bohse, J. R.; Bewtra, M.; Barnes, W. L.

    1979-01-01

    The rationale and procedures used in the radiometric calibration and correction of Heat Capacity Mapping Mission (HCMM) data are presented. Instrument-level testing and calibration of the Heat Capacity Mapping Radiometer (HCMR) were performed by the sensor contractor ITT Aerospace/Optical Division. The principal results are included. From the instrumental characteristics and calibration data obtained during ITT acceptance tests, an algorithm for post-launch processing was developed. Integrated spacecraft-level sensor calibration was performed at Goddard Space Flight Center (GSFC) approximately two months before launch. This calibration provided an opportunity to validate the data calibration algorithm. Instrumental parameters and results of the validation are presented and the performances of the instrument and the data system after launch are examined with respect to the radiometric results. Anomalies and their consequences are discussed. Flight data indicates a loss in sensor sensitivity with time. The loss was shown to be recoverable by an outgassing procedure performed approximately 65 days after the infrared channel was turned on. It is planned to repeat this procedure periodically.

  20. Heat capacity from 12 to 305°K and entropy of talc and tremolite

    USGS Publications Warehouse

    Robie, R.A.; Stout, J.W.

    1963-01-01

    The heat capacities of talc, Mg3Si4O10(OH)2, and tremolite, Ca2Mg6Si8O22(OH)2, have been measured between 12 and 305??K. Smoothed values of heat capacity, entropy, enthalpy, and free energy are tabulated. At 298.15?? K. the values of the thermodynamic functions are: talc, Cp?? = 76.89 ?? 0.23 cal. deg.-1 mole-1, S?? = 62.33 ?? 0.19 cal. deg.-1 mole-1, H?? - H6?? = 11,206 ?? 34 cal. mole-1; tremolite, Cp?? = 156.7 ?? 0.6 cal. deg.-1 mole-1, S?? = 131.2 ?? 0.5 cal. deg.-1 mole-1, H?? - H6?? = 23,335 ?? 90 cal. mole-1. From the equilibrium data of Bowen and Tuttle and the entropy of talc, the heat of formation of talc from MgO, SiO2, and H2O (liq.) is calculated to be ??H??f298 = -43.6 ?? 1 kcal.

  1. Phonon Density of States and Heat Capacity of La$_{3-x}$Te$_4$

    SciTech Connect

    Delaire, Olivier A; May, Andrew F.; McGuire, Michael A; Porter, Wallace D; Lucas,; Stone, Matthew B; Abernathy, Douglas L; Snyder, G. J.

    2009-01-01

    The phonon density of states (DOS) of La$_{3-x}$Te$_4$ compounds ($x=0.0, 0.18, 0.32$) was measured at 300, 520, and 780$\\,$K, using inelastic neutron scattering. A significant stiffening of the phonon DOS, and a large broadening of features were observed upon introduction of vacancies on La sites (increasing $x$). Heat capacity measurements were performed at temperatures $~1.85 \\leqslant T \\leqslant 1200 \\,$K, and were analyzed to quantify the contributions of phonons and electrons. The Debye temperature and the electronic coefficient of heat capacity determined from these measurements are consistent with the neutron scattering results, and with previously reported first-principles calculations. Our results indicate that La vacancies in La$_{3-x}$Te$_4$ strongly scatter phonons, and this source of scattering appears to be independent of temperature. The stiffening of the phonon DOS induced by the introduction of vacancies is explained in terms of the electronic structure and the change in bonding. The temperature dependence of the phonon DOS is captured satisfactorily by the quasiharmonic approximation.

  2. Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films

    SciTech Connect

    Kenny, T.W.

    1989-05-01

    Investigations of the properties of absorbed monolayers have received great experimental and theoretical attention recently, both because of the importance of surface processes in practical applications such as catalysis, and the importance of such systems to the understanding of the fundamentals of thermodynamics in two dimensions. We have adapted the composite bolometer technology to the construction of microcalorimeters. For these calorimeters, the adsorption substrate is an evaporated film deposited on one surface of an optically polished sapphire wafer. This approach has allowed us to make the first measurements of the heat capacity of submonolayer films of /sup 4/He adsorbed on metallic films. In contrast to measurements of /sup 4/He adsorbed on all other insulating substrates, we have shown that /sup 4/He on silver films occupies a two-dimensional gas phase over a broad range of coverages and temperatures. Our apparatus has been used to study the heat capacity of Indium flakes. CO multilayers, /sup 4/He adsorbed on sapphire and on Ag films and H/sub 2/ adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs.

  3. Complex Heat Capacity of Lithium Borate Glasses Studied by Modulated DSC

    SciTech Connect

    Matsuda, Yu; Ike, Yuji; Matsui, Chihiro; Kodama, Masao; Kojima, Seiji

    2006-05-05

    Complex heat capacity, C{sub p}* = C{sub p}' - iC{sub p}'', of lithium borate glasses Li2O{center_dot}(1-x)B2O3 (x = 0.00 - 0.33) has been investigated by Modulated DSC (MDSC). We have successfully observed the frequency dependent C{sub p}* by MDSC in the frequency range 0.01 to 0.1 Hz, and the average relaxation time of glass transition has been determined as a function of temperature. Moreover, the composition dependence of the thermal properties has been investigated. The calorimetric glass transition temperatures become higher with the increase of concentration of Li2O and show the board maximum around x = 0.26-0.28. The width of glass transition region becomes narrower as Li2O increases. These results relate to the change of the fragility of the system. It has been proven that the complex heat capacity spectroscopy by MDSC is a powerful tool to investigate the glass transition phenomena.

  4. Magnetic contribution to heat capacity and entropy of nickel ferrite (NiFe2O4)

    NASA Astrophysics Data System (ADS)

    Ziemniak, S. E.; Anovitz, L. M.; Castelli, R. A.; Porter, W. D.

    2007-01-01

    The heat capacity of nickel ferrite was measured as a function of temperature from 50 to 1200 °C using a differential scanning calorimeter. A thermal anomaly was observed at 584.9 °C, the expected Curie temperature, TC. The observed behavior was interpreted by recognizing the sum of three contributions: (1) lattice (vibrational), (2) a spin wave (magnetic) component and (3) a λ-transition (antiferromagnetic paramagnetic transition) at the Curie temperature. The first was modeled using vibrational frequencies derived from an experimentally-based IR absorption spectrum, while the second was modeled using a spin wave analysis that provided a T3/2 dependency in the low-temperature limit, but incorporated an exchange interaction between cation spins in the octahedral and tetrahedral sites at elevated temperatures, as first suggested by Grimes [15]. The λ-transition was fitted to an Inden-type model which consisted of two truncated power law series in dimensionless temperature (T/TC). Exponential equality (m=n=7) was observed below and above TC, indicating symmetry about the Curie temperature. Application of the methodology to existing heat capacity data for other transition metal ferrites (AFe2O4, A=Fe, Co) revealed nearly the same exponential equality, i.e., m=n=5.

  5. Kinetics and thermodynamics of sucrose hydrolysis from real-time enthalpy and heat capacity measurements.

    PubMed

    Tombari, E; Salvetti, G; Ferrari, C; Johari, G P

    2007-01-25

    We report a real time study of the enthalpy release and heat capacity during the course of HCl-catalyzed hydrolysis of sucrose to fructose and glucose. Measurements were performed during both isothermal conditions and during slow heating and then cooling at a controlled rate. The reaction rate constant of the first-order kinetics follows an Arrhenius relation with activation energy of 109.2 kJ/mol of sucrose. On hydrolysis, the enthalpy decreases by 14.4 kJ/mol of sucrose at 310 K, and the heat capacity, Cp, increases by 61 J mol-1 K-1 of sucrose in the solution. The enthalpy of hydrolysis decreases with increase in the temperature and DeltaCp on hydrolysis increases. The effects are attributed to change in the configurational and vibrational partition functions as one covalent bond in sucrose breaks to form two molecules, which then individually form additional hydrogen bonds and alter the water's structure in the solution. Cp of the solution increases with temperature less rapidly before sucrose hydrolysis than after it. This may reflect an increase in the configurational contribution to Cp as the hydrogen bond population changes. PMID:17228904

  6. Low-temperature heat capacity and localized vibrational modes in natural and synthetic tetrahedrites

    SciTech Connect

    Lara-Curzio, E. May, A. F.; Delaire, O.; McGuire, M. A.; Lu, X.; Liu, Cheng-Yun; Case, E. D.; Morelli, D. T.

    2014-05-21

    The heat capacity of natural (Cu{sub 12−x} (Fe, Zn, Ag){sub x}(Sb, As){sub 4}S{sub 13}) and synthetic (Cu{sub 12−x}Zn{sub x}Sb{sub 4}S{sub 13} with x = 0, 1, 2) tetrahedrite compounds was measured between 2 K and 380 K. It was found that the temperature dependence of the heat capacity can be described using a Debye term and three Einstein oscillators with characteristic temperatures that correspond to energies of ∼1.0 meV, ∼2.8 meV, and ∼8.4 meV. The existence of localized vibrational modes, which are assigned to the displacements of the trigonally coordinated Cu atoms in the structure, is discussed in the context of anharmonicity and its effect on the low lattice thermal conductivity exhibited by these compounds.

  7. Energy storage capacity of reversible liquid phase Diels-Alder reactions as determined by drop calorimetry

    SciTech Connect

    Chung, C.P.

    1983-01-01

    Several Diels-Alder reactions were evaluated as possible candidates for energy storage. The goal was to use simple drop calorimetry to screen reactions and to identify those with high energy storage capacities. The dienes used were furan and substituted furans. The dienophiles used were maleic anhydride and substituted maleic anhydrides. Sixteen reactions have been examined. Three had energy storage capacities that were increased due to reaction (maleic anhydride and 2-methyl furan, maleic anhydride and 2-ethyl furan, maleic anhydride and 2,5-dimethyl furan). The remaining thirteen showed no increase in apparent heat capacity due to reaction.

  8. Adiabatic cooling of antiprotons.

    PubMed

    Gabrielse, G; Kolthammer, W S; McConnell, R; Richerme, P; Kalra, R; Novitski, E; Grzonka, D; Oelert, W; Sefzick, T; Zielinski, M; Fitzakerley, D; George, M C; Hessels, E A; Storry, C H; Weel, M; Müllers, A; Walz, J

    2011-02-18

    Adiabatic cooling is shown to be a simple and effective method to cool many charged particles in a trap to very low temperatures. Up to 3×10(6) p are cooled to 3.5 K-10(3) times more cold p and a 3 times lower p temperature than previously reported. A second cooling method cools p plasmas via the synchrotron radiation of embedded e(-) (with many fewer e(-) than p in preparation for adiabatic cooling. No p are lost during either process-a significant advantage for rare particles. PMID:21405511

  9. Adiabatic Cooling of Antiprotons

    SciTech Connect

    Gabrielse, G.; Kolthammer, W. S.; McConnell, R.; Richerme, P.; Kalra, R.; Novitski, E.; Oelert, W.; Grzonka, D.; Sefzick, T.; Zielinski, M.; Fitzakerley, D.; George, M. C.; Hessels, E. A.; Storry, C. H.; Weel, M.; Muellers, A.; Walz, J.

    2011-02-18

    Adiabatic cooling is shown to be a simple and effective method to cool many charged particles in a trap to very low temperatures. Up to 3x10{sup 6} p are cooled to 3.5 K--10{sup 3} times more cold p and a 3 times lower p temperature than previously reported. A second cooling method cools p plasmas via the synchrotron radiation of embedded e{sup -} (with many fewer e{sup -} than p) in preparation for adiabatic cooling. No p are lost during either process--a significant advantage for rare particles.

  10. Adiabatically implementing quantum gates

    SciTech Connect

    Sun, Jie; Lu, Songfeng Liu, Fang

    2014-06-14

    We show that, through the approach of quantum adiabatic evolution, all of the usual quantum gates can be implemented efficiently, yielding running time of order O(1). This may be considered as a useful alternative to the standard quantum computing approach, which involves quantum gates transforming quantum states during the computing process.

  11. Heat capacity of hydrous trachybasalt from Mt Etna: comparison with CaAl2Si2O8 (An)-CaMgSi2O6 (Di) as basaltic proxy compositions

    NASA Astrophysics Data System (ADS)

    Giordano, D.; Nichols, A. R. L.; Potuzak, M.; Di Genova, D.; Romano, C.; Russell, J. K.

    2015-12-01

    The specific heat capacity ( C p) of six variably hydrated ( 3.5 wt% H2O) iron-bearing Etna trachybasaltic glasses and liquids has been measured using differential scanning calorimetry from room temperature across the glass transition region. These data are compared to heat capacity measurements on thirteen melt compositions in the iron-free anorthite (An)-diopside (Di) system over a similar range of H2O contents. These data extend considerably the published C p measurements for hydrous melts and glasses. The results for the Etna trachybasalts show nonlinear variations in, both, the heat capacity of the glass at the onset of the glass transition (i.e., C p g ) and the fully relaxed liquid (i.e., C p l ) with increasing H2O content. Similarly, the "configurational heat capacity" (i.e., C p c = C p l - C p g ) varies nonlinearly with H2O content. The An-Di hydrous compositions investigated show similar trends, with C p values varying as a function of melt composition and H2O content. The results show that values in hydrous C p g , C p l and C p c in the depolymerized glasses and liquids are substantially different from those observed for more polymerized hydrous albitic, leucogranitic, trachytic and phonolitic multicomponent compositions previously investigated. Polymerized melts have lower C p l and C p c and higher C p g with respect to more depolymerized compositions. The covariation between C p values and the degree of polymerization in glasses and melts is well described in terms of SMhydrous and NBO/ T hydrous. Values of C p c increase sharply with increasing depolymerization up to SMhydrous 30-35 mol% (NBO/ T hydrous 0.5) and then stabilize to an almost constant value. The partial molar heat capacity of H2O for both glasses ( C_{{{p}{H}2 {O}}}^{g} ) and liquids ( C_{{{p}{H}2 {O}}}^{l} ) appears to be independent of composition and, assuming ideal mixing, we obtain a value for C_{{{p}{H}2 {O}}}^{l} of 79 J mol-1 K-1. However, we note that a range of values for

  12. Entanglement and adiabatic quantum computation

    NASA Astrophysics Data System (ADS)

    Ahrensmeier, D.

    2006-06-01

    Adiabatic quantum computation provides an alternative approach to quantum computation using a time-dependent Hamiltonian. The time evolution of entanglement during the adiabatic quantum search algorithm is studied, and its relevance as a resource is discussed.

  13. Assessment of bulk modulus, thermal expansion and heat capacity of minerals

    NASA Astrophysics Data System (ADS)

    Saxena, S. K.

    1989-04-01

    Since the heat capacity of a solid at constant pressure ( CP) is related to the isothermal bulk modulus ( KT) and isobaric thermal expansion ( αP), an assessment of the experimental data on these properties is necessary to establish the internal consistency of a thermodynamic data set. Through suitable formulations of the temperature dependence of bulk modulus, thermal expansion and heat capacity at constant volume ( CV) and the application of non-linear programming techniques, it is possible to assess the internal consistency of these data and the measured heat capacity at constant pressure. Such optimization of the data on periclase has been performed with the following results: αP = 0.3754 × 10 -4 + 0.791 × 10 -8T - 0.784 T-2 + 0.9148 T-3 (11) KT = 1.684 × 10 6-241 T - 0.056 T2 + 0.167 × 10 -4T3( bar) (12) CV = 48.02 - 0.572 × 10 6T(13) -2 - 0.4876 × 10 11T-4 - 0.1502 × 10 12T-6 + 0.9836 × 10 20T-8V (1, 298) = 11.245 (cm 3/mol). (14) If appropriate CP data are available, it is possible to estimate the temperature dependence of αP and KT for any solid. In suitable cases, the method may be used through a combination of the data on CP and phase equilibrium to calculate Kt, its pressure derivative and thermal expansion. Such optimized data for brucite are: H0f(1, 298.15) = -924620, S0(1, 298.15) = 64.08 αP = 0.1002 E - 4 + 0.1468 E - 7 T + 1.8606 T-2 (18) kt = 0.5712 Mb, ( ∂K T/∂P) = 4.712Cv= 118.58 - 0.639 E + 7 T-2 + 0.34574 E + 12 T-4 - 0.10538 E + 17 T-6. (19)

  14. Heat capacity of multilayers of 3He adsorbed on graphite at low millikelvin temperatures

    NASA Astrophysics Data System (ADS)

    Greywall, Dennis S.

    1990-02-01

    Precise heat-capacity results are presented for 3He adsorbed on graphite. The temperature range of the data is from 2 to 200 mK, while the coverages span from somewhat below monolayer completion up through five atomic layers. Promotion of atoms into the second, third, and fourth layers is clearly observed. Nuclear-spin exchange energies of the order of a few tenths of a mK are found for the submonolayer incommensurate solid phase. These values differ significantly from those recently inferred from NMR experiments. Data for the second-layer fluid yield 3He quasiparticle effective masses that agree well with the corresponding first-layer values and range from one to five times the bare 3He mass. Prior to third-layer promotion, the second layer undergoes a first-order phase transition. By comparison with the phase diagram for the first layer, the new phase in the second layer is assumed to be a registered solid. Registry is now with respect to the first 3He layer, which continues to exist as a triangular-lattice solid incommensurate with the graphite substrate. The registered phase exhibits a large, sharp heat-capacity anomaly at 2.5 mK. This anomaly may be due to antiferromagnetic polarons which form around zero-point vacancies or may be the signature of an unusual registered phase in which some of the atoms are positioned at substrate potential maxima. As the coverage is increased further, the second-layer spin peak remains located at 2.5 mK but suddenly grows in amplitude, while the temperature dependence above the peak changes from T-0.5 towards T-2. The anomaly reaches its greatest magnitude at 0.24 atoms/AṦ where, perhaps coincidentally, promotion of atoms into the fourth layer also occurs. At this same coverage previous magnetization measurements have shown a large ferromagnetic peak. The heat-capacity data indicate that the ferromagnetic peak occurs when the second layer exists in a state intermediate between a registered solid and the incommensurate

  15. Latest developments on the Er3+:YAG solid state heat-capacity laser

    NASA Astrophysics Data System (ADS)

    Bigotta, Stefano; Ibach, Thierry; Eichhorn, Marc

    2013-10-01

    In this paper, we illustrate the latest advancement on the eye-safe Solid State Heat-Capacity Laser (SSHCL) investigated for the development of medium and high energy laser sources. Nearly all the solid-state lasers considered for defence applications in the range of 10 kW up to over 100 kW emit at a wavelength of 1.03 μm- 1.06 μm. Therefore, we perform research on an alternative emitting around 1.6 μm, which unites many advantages in use (robustness, a simple technology, flexibility in volume and weight). The heat-capacity principle, in which the laser material is cooled only after the laser action has ended, results in low temperature gradients in the laser medium, leading to a good beam quality and a high performance. Previous investigations on Er3+:YAG SSHCL demonstrated the scalability of the heat-capacity laser principle and up to 4.65 kW and 440 J in less than 800 ms have been achieved, representing the current world record in eye-safe diode-pumped solid-state laser technology. Optical-to-optical efficiencies of over 41% and slope efficiencies of over 51% are obtained with respect to the incident pump power. In this report we further investigate the possibility of compensating any parasitic residual heating. Indeed, it has been shown that the optimal laser operation is directly coupled with the intensity distribution of the laser mode inside the laser medium. The ideal resonator configurations are those which allow an extraction of the laser energy as homogeneous as possible. Using an intra-cavity adaptive optics system beams with phase fronts as flat as possible, on the order of less that 1/10 of the wavelength for each of the considered Zernike polynomials have been generated, and the shot duration has been lengthened by 50%. The influence of the crystal geometry on the pump distribution homogeneity and the possible ways for maximizing the extraction efficiency are investigated.

  16. New equations for density, entropy, heat capacity, and potential temperature of a saline thermal fluid

    NASA Astrophysics Data System (ADS)

    Sun, Hongbing; Feistel, Rainer; Koch, Manfred; Markoe, Andrew

    2008-10-01

    A set of fitted polynomial equations for calculating the physical variables density, entropy, heat capacity and potential temperature of a thermal saline fluid for a temperature range of 0-374 °C, pressure range of 0.1-100 MPa and absolute salinity range of 0-40 g/kg is established. The freshwater components of the equations are extracted from the recently released tabulated data of freshwater properties of Wagner and Pruß [2002. The IAPWS formulation 1995 for the thermodynamic properties of ordinary water substance for general and scientific use. Journal of Physical and Chemical Reference Data 31, 387-535]. The salt water component of the equation is based on the near-linear relationship between density, salinity and specific heat capacity and is extracted from the data sets of Feistel [2003. A new extended Gibbs thermodynamic potential of seawater. Progress in Oceanography 58, 43-114], Bromley et al. [1970. Heat capacities and enthalpies of sea salt solutions to 200 °C. Journal of Chemical and Engineering Data 15, 246-253] and Grunberg [1970. Properties of sea water concentrates. In: Third International Symposium on Fresh Water from the Sea, vol. 1, pp. 31-39] in a temperature range 0-200 °C, practical salinity range 0-40, and varying pressure and is also calibrated by the data set of Millero et al. [1981. Summary of data treatment for the international high pressure equation of state for seawater. UNESCO Technical Papers in Marine Science 38, 99-192]. The freshwater and salt water components are combined to establish a workable multi-polynomial equation, whose coefficients were computed through standard linear regression analysis. The results obtained in this way for density, entropy and potential temperature are comparable with those of existing models, except that our new equations cover a wider temperature—(0-374 °C) than the traditional (0-40 °C) temperature range. One can apply these newly established equations to the calculation of in-situ or

  17. Contrasting Effects of Salt and Temperature on Niosome-Bound Norharmane: Direct Evidence for Positive Heat Capacity Change in the Niosome:β-Cyclodextrin Interaction.

    PubMed

    Paul, Bijan K; Ghosh, Narayani; Mondal, Ramakanta; Mukherjee, Saptarshi

    2016-05-01

    The modulation of the prototropic equilibrium of a cancer cell photosensitizer, norharmane (NHM), within a niosome microheterogeneous environment has been investigated. The contrasting effects of temperature and extrinsically added salt on the photophysics of niosome-bound drug have been meticulously explored from steady-state and time-resolved spectroscopic techniques. The cation ⇌ neutral prototropic equilibrium of NHM is found to be preferentially favored toward the neutral species with increasing salt concentration, and the results are rationalized on the basis of water penetration to the hydration layer of niosome. The effects are typically reversed with temperature. The differential rotational relaxation behavior of NHM under various conditions has also been addressed from fluorescence anisotropy decay. Further, the study delineates the application of β-cyclodextrin (βCD) as a potential host system, leading to drug sequestration from the niosome-encapsulated state. To this end, a detailed investigation of the thermodynamics of the niosome:βCD interaction has been undertaken by isothermal titration calorimetry (ITC) to unravel the notable dependence of the thermodynamic parameters on temperature. Consequently, a critical analysis of the variation of the enthalpy change (ΔH) of the process with temperature leads to the unique observation of a positive heat capacity change (ΔCp) marking the hallmark of hydrophobic hydration. PMID:27082934

  18. On the critical specific heat capacity of a classical anharmonic crystal with long-range interaction

    NASA Astrophysics Data System (ADS)

    Pisanova, E.; Ivanov, S.

    2014-12-01

    The bulk critical specific heat capacity of a classical anharmonic crystal with long-range interaction (decreasing at large distances r as r-d-a, where d is the space dimensionality and 0 < σ <= 2) is studied. An exact analytical expression is obtained at the upper critical dimension d = 2σ of the system. This result depends on both the deviation from the critical point and the space dimensionality of the system, while the known asymptotic one depends only on the deviation from the critical point. For real systems (chains, thin layers, i.e. films and three-dimensional systems) the exact result and the asymptotic one are graphically presented and compared on the basis of the calculated relative errors. The obtained result holds true in a broader neighborhood of the critical point. The expansion of the critical region is estimated at the three real physical dimensionalities.

  19. Heat capacity and magnetization of CoNb2O6 near quantum critical point

    NASA Astrophysics Data System (ADS)

    Liang, Tian; Koohpayeh, Seyed; Krizan, Jason; Dutton, Sian; McQueen, Tyrel; Cava, Robert; Phuan Ong, N.

    2012-02-01

    CoNb2O6 is a quasi-1D quantum magnet in which magnetic Co^2+ ions are ferromagnetically arranged into nearly isolated chains along the c axis with the magnetic moment confined in the ac-plane. By applying transverse magnetic field along b-axis, quantum phase transition from magnetically ordered phase to paramagnetic phase occurs. Evidence for emergent E8 symmetry was recently obtained by neutron scattering near the quantum critical point (QCP) in an applied transverse magnetic field of 5.5 T We will report on experiments to investigate the behavior of the heat capacity and torque magnetization in the vicinity of the QCP and discuss their implications.

  20. Difference in the heat capacity and the coefficient of thermal expansion responses during thermal cycling

    NASA Astrophysics Data System (ADS)

    Medvedev, Grigori; Lee, Eun-Woong; Caruthers, James

    2011-03-01

    An observation that different experimental methods give different values of Tg is part of the lore of the field of the glassy polymers. We report on a careful study of a series of polymeric systems both thermoplastic and thermoset, including PMMA, PC, PS, and 3,3' DDS Epon 825, conducted using DSC and TMA techniques. We found that for the same thermal history the heat capacity and the coefficient of thermal expansion (both measured upon heating) as functions of temperature transition from the glassy asymptote to the equilibrium asymptote at significantly different temperatures; this difference was in the range from 8 to 17 degrees, depending on the system. We argue that such a large difference in the enthalpy and volume responses during the same thermal history is inconsistent with the commonly used material clock models, but is consistent with the view of the glassy materials as containing dynamically heterogeneous regions.

  1. Temperature Dependence of the Molar Heat Capacity for Ferromagnets Within the Mean Field Theory

    NASA Astrophysics Data System (ADS)

    Fernández Rodríguez, J.; Blanco, J. A.

    2005-01-01

    We describe, using the Mean Field Theory, a detailed analysis of the magnetic contribution to the molar heat capacity Cmag for ferromagnetic systems. This calculation is designed to be used as a teaching homework problem for physics undergraduates. The description emphasises that Cmag at the transition temperature TC is characterised by the existence of a simple jump discontinuity anomaly, but when the temperature is lowered down to 0 K the shape of Cmag depends strongly on the magnitude of the spin S. In fact, the appearance of a shoulder in Cmag for S > 3/2 is expected. The origin of this shoulder could be understood as a Schottky-like anomaly in the ordered state. These physical results are in good agreement with those from real systems, and give the student a valuable insight into the behaviour of the thermodynamical response of a ferromagneticmaterial.

  2. Evaluating depth to shallow groundwater using Heat Capacity Mapping Mission (HCMM) data

    USGS Publications Warehouse

    Heilman, J. L.; Moore, Donald G.

    1982-01-01

    Four dates of Heat Capacity Mapping Mission (HCMM) data were analyzed to evaluate the utility of HCMM thermal data for evaluating depth to shallow groundwater. During the summer, shallow water tables can create lower soil temperatures throughout the diurnal temperature cycle. Because of large spatial and temporal ground cover variations, HCMM daytime radiometric temperatures alone did not correlate with water table depth. The radiometric temperatures consisted of radiance contributions from different crop canopies and their respective soil backgrounds. However, when surface soil temperatures were empirically estimated from HCMM temperatures and percent cover of each pixel, significant correlations were obtained between estimated soil temperatures and water table depth. Correlations increased as the season progressed and temperature gradients within the soil profile increased. However, estimated soil temperatures were also correlated with near-surface soil moisture since during the daytime, increasing soil moisture reduced surface soil temperature. Complementary effects of shallow water tables and soil moisture on daytime temperatures cannot be separated.

  3. THERMAL-INERTIA MAPPING IN VEGETATED TERRAIN FROM HEAT CAPACITY MAPPING MISSION SATELLITE DATA.

    USGS Publications Warehouse

    Watson, Ken; Hummer-Miller, Susanne

    1984-01-01

    Thermal-inertia data, derived from the Heat Capacity Mapping Mission (HCMM) satellite, were analyzed in areas of varying amounts of vegetation cover. Thermal differences which appear to correlate with lithologic differences have been observed previously in areas of substantial vegetation cover. However, the energy exchange occurring within the canopy is much more complex than that used to develop the methods employed to produce thermal-inertia images. Because adequate models are lacking at present, the interpretation is largely dependent on comparison, correlation, and inference. Two study areas were selected in the western United States: the Richfield, Utah and the Silver City, Arizona-New Mexico, 1 degree multiplied by 2 degree quadrangles. Many thermal-inertia highs were found to be associated with geologic-unit boundaries, faults, and ridges. Lows occur in valleys with residual soil cover.

  4. Some examples of the utility of HCMM data in geologic remote sensing. [Heat Capacity Mapping Mission

    NASA Technical Reports Server (NTRS)

    Kahle, A. B.; Schieldge, J. P.; Abrams, M. J.; Alley, R. E.

    1981-01-01

    Examples of HCMM (Heat Capacity Mapping Mission) data in geologic remote sensing are presented, and the data set is composed of HCMM and aircraft digital scanner data and ground truth data from four western U.S. test sites. Data are used in the thermal model to test thermal data effectiveness, and changes in temperature with depth and time for dry soils are described by the model. It is found that the HCMM thermal inertia image is useful in the separability of bedrock and alluvium in Death Valley, and aa and pahoehoe flows in the Pisgah basalt flow. In a color composite of HCMM day temperature, night temperature, and day visible images of the Pisgah Crater test site, it is possible to distinguish alluvium, playa, aa and pahoehoe basalt flow, rhyolite intrusives, and other elements. Ground checking of units at a few points will extend capabilities to large areas and assist in creating telegeologic maps.

  5. Surface temperature variations as measured by the Heat Capacity Mapping Mission

    NASA Technical Reports Server (NTRS)

    Price, J. C.

    1979-01-01

    The AEM-1 satellite, the Heat Capacity Mapping Mission, has acquired high-quality thermal infrared data at times of day especially suited for studying the earth's surface and the exchange of heat and moisture with the atmosphere. Selected imagery illustrates the considerable variability of surface temperature in and around cities, in the dry southwestern United States, in the Appalachian Mountains, and in agricultural areas. Through simplifying assumptions, an analytic experience is derived that relates day/night temperature differences to the near-surface layer (thermal inertia) and to meteorological factors. Analysis of the result suggests that, in arid regions, estimates of relative thermal inertia may be inferred, whereas, in agricultural areas, a hydrologic interpretation is possible.

  6. Thermal conductivity and heat capacity of n-decane and n-hexadecane through molecular simulations

    NASA Astrophysics Data System (ADS)

    Shelton, John

    2014-11-01

    Atomistic molecular dynamics simulations were carried out at equilibrium to calculate the constant pressure heat capacity and thermal conductivity of n-decane and n-hexadecane within the range of ambient to extreme temperature and pressure conditions (i.e. up to 500 °F and 35,000 psi). Both a computationally efficient united-atom force field and an all-atom force field were employed in this investigation. A quantitative comparison of the results was performed against experimental values and values predicted from a high temperature - high pressure perturbed chain - statistically associated fluid theory (HPHT PC-SAFT) model. Analysis of the intra- and inter-molecular structure of the fluid as well as its dynamical characteristics were performed.

  7. The electronic heat capacity of YBa2Cu3O7-δ superconductor

    NASA Astrophysics Data System (ADS)

    Singh, Anu; Singh, Hempal; Indu, B. D.

    2016-07-01

    The contributions due to the point defects or disorder and anharmonicities which play deterministic role in the understanding of electronic heat capacity (EHC) of high temperature superconductors (HTS) have been investigated via electron density of states (EDOS) approach on the basis of quantum dynamical many body theory. The evaluation of EDOS has been carried out with the help of most versatile method of double time temperature dependent electron Green's functions (GF) via a Hamiltonian (non BCS type) which includes the effects of electrons, phonons, defects, anharmonicity, and electron-phonon interactions which enables to account the effects of cubic anharmonicity besides with both the force constant changes and mass difference caused by the impurities in developing the results for EDOS and EHC. The new results reveal some striking features of EHC of HTS.

  8. Heat capacity, p-T phase diagram, and structure of Rb2KTiOF5

    NASA Astrophysics Data System (ADS)

    Fokina, V. D.; Flerov, I. N.; Molokeev, M. S.; Pogorel'Tsev, E. I.; Bogdanov, E. V.; Krylov, A. S.; Bovina, A. F.; Voronov, V. N.; Laptash, N. M.

    2008-11-01

    Elpasolite Rb2KTiOF5 (space group, Fm bar 3 m, Z = 4) was synthesized using a solid-phase reaction method. The temperature dependences of the heat capacity, the unit cell parameters, the structure, the permittivity, the response to an external pressure, and the Raman spectra were studied. A nonferroelectric phase transition was revealed at T 0 = 215 K; the transition is accompanied by a tetragonal distortion of the unit cell (space group I4/ m, Z = 10) and a change in the entropy (Δ S 0 = Rln8), which is anomalously large for perovskite-like oxyfluorides with atomic cations. The specific features of the mechanism of structure distortion are discussed in combination with the previous experimental data obtained for cryolite (NH4)3TiOF5 and elpasolite Rb2KGaF6.

  9. Intracavity adaptive correction of a 10 kW, solid-state, heat-capacity laser

    SciTech Connect

    LaFortune, K N; Hurd, R L; Brase, J M; Yamamoto, R M

    2004-05-13

    The Solid-State, Heat-Capacity Laser (SSHCL), under development at Lawrence Livermore National Laboratory (LLNL) is a large aperture (100 cm{sup 2}), confocal, unstable resonator requiring near-diffraction-limited beam quality. There are two primary sources of the aberrations in the system: residual, static aberrations from the fabrication of the optical components and predictable, time-dependent, thermally-induced index gradients within the gain medium. A deformable mirror placed within the cavity is used to correct the aberrations that are sensed externally with a Shack-Hartmann wavefront sensor. Although the complexity of intracavity adaptive correction is greater than that of external correction, it enables control of the mode growth within the resonator, resulting in the ability to correct a more aberrated system longer. The overall system design, measurement techniques and correction algorithms are discussed. Experimental results from initial correction of the static aberrations and dynamic correction of the time-dependent aberrations are presented.

  10. CALORIMETRY OF TRU WASTE MATERIALS

    SciTech Connect

    C. RUDY; ET AL

    2000-08-01

    Calorimetry has been used for accountability measurements of nuclear material in the US. Its high accuracy, insensitivity to matrix effects, and measurement traceability to National Institute of Standards and Technology have made it the primary accountability assay technique for plutonium (Pu) and tritium in the Department of Energy complex. A measurement of Pu isotopic composition by gamma-ray spectroscopy is required to transform the calorimeter measurement into grams Pu. The favorable calorimetry attributes allow it to be used for verification measurements, for production of secondary standards, for bias correction of other faster nondestructive (NDA) methods, or to resolve anomalous measurement results. Presented in this paper are (1) a brief overview of calorimeter advantages and disadvantages, (2) a description of projected large volume calorimeters suitable for waste measurements, and (3) a new technique, direct measurement of transuranic TRU waste alpha-decay activity through calorimetry alone.

  11. General characteristics and availability of Landsat 3 and heat capacity mapping mission thermal infrared data

    USGS Publications Warehouse

    Southworth, C. Scott

    1983-01-01

    Two satellite systems launched by the National Aeronautics and Space Administration (NASA) in 1978 carried sensors which operated in the thermal infrared (IR) region of the electromagnetic spectrum, The final IR radiation data provide spectral information about the physical properties of the Earth's surficial materials not duplicated in either the visible or reflective IR wavelength regions. Landsat 3, launched on March 5, 1978, contained a thermal sensor as part of the multispectral scanner (MSS) system. The sensor operated in the 10.4- to 12.6-?m (band 8) wavelength region and produced imagery with a ground resolution of approximately 235 m. Launched on April 26) 1978) the Heat Capacity Mapping Mission (HCMM) spacecraft carried a sensor, the heat capacity mapping radiometer (HCMR) which operated in the 10.5- to 12.5?m wavelength region and produced imagery with a ground resolution of approximately 600 m at nadir. The HCMM satellite acquired over 6,600 data passes of visible (0.55-1.1 ?m), as well as thermal IR data, over North America, Europe, and Australia. General characteristics and availability of Landsat 3 and HCMM thermal IR data are discussed. Landsat 3 reflected IR band 7 (0.55-1.1 ?m) and Landsat 3 band 8 thermal data acquired over the eastern and western United States are analyzed and compared with HCMM visible, thermal IR, thermal inertia, and day-night temperature difference imagery for geologic applications. Digitally processed and enhanced HCMM data (high-pass filters, diagonal derivatives, and band ratios), produced by the U.S. Geological Survey, Flagstaff) Ariz., are presented for geologic interpretation.

  12. Contactless Calorimetry for Levitated Samples

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Dokko, W.

    1986-01-01

    Temperature and specific heat of hot sample measured with pyrometer in proposed experimental technique. Technique intended expecially for contactless calorimetry of such materials as undercooled molten alloys, samples of which must be levitated to prevent contamination and premature crystallization. Contactless calorimetry technique enables data to be taken over entire undercooling temperature range with only one sample. Technique proves valuable in study of undercooling because difference in specific heat between undercooled-liquid and crystalline phases at same temperature provides driving force to convert metastable undercooled phase to stable crystalline phase.

  13. Adiabatic topological quantum computing

    NASA Astrophysics Data System (ADS)

    Cesare, Chris; Landahl, Andrew J.; Bacon, Dave; Flammia, Steven T.; Neels, Alice

    2015-07-01

    Topological quantum computing promises error-resistant quantum computation without active error correction. However, there is a worry that during the process of executing quantum gates by braiding anyons around each other, extra anyonic excitations will be created that will disorder the encoded quantum information. Here, we explore this question in detail by studying adiabatic code deformations on Hamiltonians based on topological codes, notably Kitaev's surface codes and the more recently discovered color codes. We develop protocols that enable universal quantum computing by adiabatic evolution in a way that keeps the energy gap of the system constant with respect to the computation size and introduces only simple local Hamiltonian interactions. This allows one to perform holonomic quantum computing with these topological quantum computing systems. The tools we develop allow one to go beyond numerical simulations and understand these processes analytically.

  14. Invited Article: Micron resolution spatially resolved measurement of heat capacity using dual-frequency time-domain thermoreflectance

    NASA Astrophysics Data System (ADS)

    Wei, Changdong; Zheng, Xuan; Cahill, David G.; Zhao, Ji-Cheng

    2013-07-01

    A pump-probe photothermal technique - dual-frequency time-domain thermoreflectance - was developed for measuring heat capacity with a spatial resolution on the order of 10 μm. The method was validated by measuring several common materials with known heat capacity. Rapid measurement of composition-phase-property relationships was demonstrated on Ti-TiSi2 and Ni-Zr diffusion couples; experimental values of heat capacity of the intermetallic compounds in these diffusion couples were compared with literature values and CALPHAD (CALculation of PHAse Diagram) calculations. The combination of this method and diffusion multiples provides an efficient way to generate thermodynamic data for CALPHAD modeling and database construction. The limitation of this method in measuring low thermal diffusivity materials is also discussed.

  15. Invited article: micron resolution spatially resolved measurement of heat capacity using dual-frequency time-domain thermoreflectance.

    PubMed

    Wei, Changdong; Zheng, Xuan; Cahill, David G; Zhao, Ji-Cheng

    2013-07-01

    A pump-probe photothermal technique - dual-frequency time-domain thermoreflectance - was developed for measuring heat capacity with a spatial resolution on the order of 10 μm. The method was validated by measuring several common materials with known heat capacity. Rapid measurement of composition-phase-property relationships was demonstrated on Ti-TiSi2 and Ni-Zr diffusion couples; experimental values of heat capacity of the intermetallic compounds in these diffusion couples were compared with literature values and CALPHAD (CALculation of PHAse Diagram) calculations. The combination of this method and diffusion multiples provides an efficient way to generate thermodynamic data for CALPHAD modeling and database construction. The limitation of this method in measuring low thermal diffusivity materials is also discussed. PMID:23902037

  16. Mound calorimetry for explosive surveillance

    SciTech Connect

    Shockey, G.C.; Rodenburg, W.W.

    1985-01-01

    Heat of reaction determinations of pyrotechnics and explosives is made at MRC-Mound by bomb calorimetry. Energy releases from ten calories to 94 kilocalories have been measured accurately using four different calorimeter systems. Each system is described and some heat of reaction results are given. 3 figs., 4 tabs.

  17. Heat capacity and magnetic properties of fluoride CsFe2+Fe3+F6 with defect pyrochlore structure

    NASA Astrophysics Data System (ADS)

    Gorev, M. V.; Flerov, I. N.; Tressaud, A.; Bogdanov, E. V.; Kartashev, A. V.; Bayukov, O. A.; Eremin, E. V.; Krylov, A. S.

    2016-05-01

    Heat capacity, Mössbauer and Raman spectra as well as magnetic properties of fluoride CsFe2F6 with defect pyrochlore structure were studied. In addition to recently found above room temperature three successive structural transformations Pnma-Imma-I41amd-Fd-3m, phase transition of antiferromagnetic nature with the 13.7 K Neel temperature and a broad heat capacity anomaly with a maximum at about 30 K were observed. The room temperature symmetry Pnma is unchanged at least down to 7 K. Simple model of indirect bond used to estimate the exchange interactions and to propose a magnetic structure model.

  18. Impact of Plastic Deformation and Shear Band Formation on the Boson Heat Capacity Peak of a Bulk Metallic Glass

    NASA Astrophysics Data System (ADS)

    Mitrofanov, Yu. P.; Peterlechner, M.; Divinski, S. V.; Wilde, G.

    2014-04-01

    The effect of annealing on the low-temperature heat capacity of a bulk Pd38.5Ni40P21.5 metallic glass is investigated for as-quenched and deformed (rolled) states. Although the boson heat capacity peak increases with increasing strain, it relaxes faster and to a lower level compared to that of the as-quenched state after annealing treatments both below and above the glass transition temperature Tg. The glass is found to retain a certain "memory" on the room-temperature plastic deformation even after annealing above Tg. Indications for two counteracting processes that might be related to different types of shear bands are observed.

  19. Estimation of the Heat Capacities of Organic Liquids as a Function of Temperature using Group Additivity. I. Hydrocarbon Compounds

    NASA Astrophysics Data System (ADS)

    Růžička, Vlastimil; Domalski, Eugene S.

    1993-05-01

    A second-order group additivity method has been developed for the estimation of the heat capacity of liquid hydrocarbons as a function of temperature in the range from the melting temperature to the normal boiling temperature. The temperature dependence of group contributions and structural corrections has been represented by a polynomial expression. The adjustable parameters in the polynomials have been calculated using a weighted least squares minimization procedure. Recommended heat capacities from a large compilation of critically evaluated data that contains over 1300 organic liquids served as a database both for the development and testing of the method.

  20. Apparent molar heat capacity and other thermodynamic properties of aqueous KCL solutions to high temperatures and pressures

    SciTech Connect

    Pabalan, R.T.; Pitzer, K.S.

    1988-07-01

    Heat capacities of KCl solutions have been measured from 413 to 573 K at 200 bar over the molality range of 0.05-3.0 mol kg/sup -1/. These were combined with literature data on volumes, heat capacities, enthalpies, and osmotic coefficients up to a temperature of 599 K and a pressure of 500 bar to yield comprehensive equations for the calculation of the thermodynamic properties of KCl(aq) to high temperatures and pressures by using ion-interaction approach of Pitzer.

  1. Simultaneous determination of temperature-dependent thermal conductivity and volumetric heat capacity by an inverse technique

    SciTech Connect

    Woodbury, K.A.; Boohaker, C.G.

    1996-12-31

    Determination of thermal properties by inverse methods often involves limited thermal excitation of a relatively small sample. If these thermal properties are to be found as functions of temperature, then this procedure must be replicated at several artificially elevated temperatures. For some types of materials (for example, those bearing moisture) this approach is impractical. In this paper, a procedure is developed for determining thermal properties (conductivity k and volumetric heat capacity C {equivalent_to} {rho}c{sub p}) as functions of temperature from a single experiment. This procedure is targeted for determination of k(T) and C(T) for sand molds used in castings. An inverse method based on a Gauss linearization is used to estimate these functions. The experiment used to determine these properties consists of heating a one-dimensional specimen of the material from one end. The variation of thermal properties with temperature is assumed to be a piecewise linear function, with values of properties to be determined at prescribed temperatures. A numerical experiment is used to demonstrate the technique.

  2. Analytical insight into the lattice thermal conductivity and heat capacity of monolayer MoS2

    NASA Astrophysics Data System (ADS)

    Saha, Dipankar; Mahapatra, Santanu

    2016-09-01

    We report, a detailed theoretical study on the lattice thermal conductivity of a suspended monolayer MoS2, far beyond its ballistic limit. The analytical approach adopted in this work mainly relies on the use of Boltzmann transport equation (BTE) within the relaxation time approximation (RTA), along with the first-principles calculations. Considering the relative contributions from the various in-plane and out-of-plane acoustic modes, we derive the closed-form expressions of the mode specific heat capacities, which we later use to obtain the phonon thermal conductivities of the monolayer MoS2. Besides finding the intrinsic thermal conductivity, we also analyse the effect of the phonon-boundary scattering, for different dimensions and edge roughness conditions. The viability of the semi-analytic solution of lattice thermal conductivity reported in this work ranges from a low temperature (T∼30 K) to a significantly high temperature (T∼550 K), and the room temperature (RT) thermal conductivity value has been obtained as 34.06 Wm-1K-1 which is in good agreement with the experimental result.

  3. An automated flow calorimeter for heat capacity and enthalpy measurements at elevated temperatures and pressures

    NASA Astrophysics Data System (ADS)

    Yesavage, V. F.

    1987-10-01

    The need for thermal property data at process conditions in the design of petrochemical and synfuel plants has been well documented. As such, the primary objective of this work is to construct an automated flow calorimeter to measure isobaric heat capacities and enthalpies of vaporization over the range 0 to 30MPa and 300 to 700K with an anticipated accuracy of 0.1%. The method of measurement is by the traditional electrical power input technique with a unique calorimeter design utilizing a concentric coil/radiation shield structure which minimizes heat loss errors and simplifies the replacement of plugged components. Flow generation is accomplished with a precision Ruska pump eliminating the need for on-line flow rate measurement. In addition, the proposed instrument will be fully automated minimizing the need for highly skilled operators which had previously been a severe limitation with this type of instrument. Significant progress has been made on the project this last year with the completion of construction of all major system hardware components and the associated automation electronics. Initial tests of the equipment are encouraging and no significant delays are foreseen in the completion of the apparatus. During the next year the automation and data acquisition software will be written and the completed unit will be tested with water.

  4. Low Temperature heat capacity of Uranium-Plutonium MOX single crystals

    NASA Astrophysics Data System (ADS)

    Griveau, Jean-Christophe; Colineau, Eric; Eloirdi, Rachel; Caciuffo, Roberto

    2015-03-01

    The establishment of the basic properties of actinides based materials is crucial for the understanding of conventional and advanced nuclear fuels. Accessing ground state properties at very low temperature for these systems gives a direct overview of their fundamental features. Moreover, when these materials can be produced as single crystals, side effects due to the presence of grains and impurities phases are drastically reduced, giving a very powerful add-in for theoretical and industrial oriented studies. This clearly ensures the reliability of the parameters determined while existing models of these strategic materials can be probed especially in the purpose of applications/developments and safety concerns. Here we report on heat capacity measurements performed on U-Pu MOX in single crystal form. Tiny crystals with mass of 2 to 15 mg have been produced by solid-solid chemical vapour transport technique with several different compositions ranging from pure UO2 to PuO2. Compositions close to UO2 (U rich) present a persistent signature similarly to the magnetic transition reported for the pure phase TN ~ 31 K while plutonium rich concentrations do not show any hint of the magnetic transition down to the minimum temperature achieved.

  5. Modeling Antimortar Lethality by a Solid-State Heat-Capacity Laser

    SciTech Connect

    Boley, C D; Rubenchik, A M

    2005-02-15

    We have studied the use of a solid-state heat-capacity laser (SSHCL) in mortar defense. This type of laser, as built at LLNL, produces high-energy pulses with a wavelength of about 1 {micro}m and a pulse repetition rate of 200 Hz. Currently, the average power is about 26 kW. Our model of target interactions includes optical absorption, two-dimensional heat transport in the metal casing and explosive, melting, wind effects (cooling and melt removal), high-explosive reactions, and mortar rotation. The simulations continue until HE initiation is reached. We first calculate the initiation time for a range of powers on target and spot sizes. Then we consider an engagement geometry in which a mortar is fired at an asset defended by a 100-kW SSHCL. Propagation effects such as diffraction, turbulent broadening, scattering, and absorption are calculated for points on the trajectory, by means of a validated model. We obtain kill times and fluences, as functions of the rotation rate. These appear quite feasible.

  6. Heat capacity and thermal relaxation of bulk helium very near the lambda point

    NASA Technical Reports Server (NTRS)

    Lipa, John A.; Swanson, D. R.; Nissen, J. A.; Chui, T. C. P.

    1994-01-01

    In October 1992 a low temperature experiment was flown on the Space Shuttle in low Earth orbit. The objective of the mission was to measure the heat capacity and thermal conductivity of helium very close to the lambda point with the smearing effect of gravity removed. We report preliminary results from the experiment, and compare them with related measurements performed on the ground. The sample was s sphere of helium 3.5 cm in diameter contained within a copper calorimeter of vey high thermal conductivity. The calorimeter was attached to a pair of high resolution paramagnetic salt thermometers with noise levels in the 10(exp -10) K range and suspended from a high stability thermal isolation system. During the mission we found that the resolution of the thermometers was degraded somewhat due to the impact of charged particles. This effect limited the useful resolution of the measurements to about two nanokelvins from the lambda point. The results reported here are limited to about ten nanokelvins from the transition.

  7. The Stone-Wales transformation: from fullerenes to graphite, from radiation damage to heat capacity.

    PubMed

    Heggie, M I; Haffenden, G L; Latham, C D; Trevethan, T

    2016-09-13

    The Stone-Wales (SW) transformation, or carbon-bond rotation, has been fundamental to understanding fullerene growth and stability, and ab initio calculations show it to be a high-energy process. The nature and topology of the fullerene energy landscape shows how the Ih-C60 must be the final product, if SW transformations are fast enough, and various mechanisms for their catalysis have been proposed. We review SW transformations in fullerenes and then discuss the analogous transformation in graphite, where they form the Dienes defect, originally posited to be a transition state in the direct exchange of a bonded atom pair. On the basis of density functional theory calculations in the local density approximation, we propose that non-equilibrium concentrations of the Dienes defect arising from displacing radiation are rapidly healed by point defects and that equilibrium concentrations of Dienes defects are responsible for the divergent ultra-high-temperature heat capacity of graphite.This article is part of the themed issue 'Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene'. PMID:27501968

  8. The Ideal and Real Gas Heat Capacity of Potassium Atoms at High Temperatures

    NASA Astrophysics Data System (ADS)

    Biolsi, Louis; Biolsi, Michael

    2016-04-01

    The ideal gas heat capacity, Cp, of potassium atoms is calculated to high temperatures using statistical mechanics. Since there are a large number of electronic energy levels in the partition function (Boltzmann sum) below the first ionization potential, the partition function and Cp will become very large as the temperature increases unless the number of energy levels contributing to the partition function is constrained. Two primary categories of arguments are used to do this. First, at high temperatures, the increased size of the atoms constrains the sum (Bethe method). Second, an argument based on the existence of interacting charged species at higher temperatures is used to constrain the sum (ionization potential lowering method). When potassium atoms are assumed to constitute a real gas that obeys the virial equation of state, the lowest non-ideal contribution to Cp depends on the second derivative of the second virial coefficient, B( T), which depends on the interaction potential energy curves between two potassium atoms. When two ground-state (2{S}) atoms interact, they can follow either of the two potential energy curves. When a 2{S} atom interacts with an atom in the first electronically excited (2{P}) state, they can follow any of the eight potential energy curves. The values of B( T) for the ten states are determined, then averaged, and used to calculate the nonideal contribution to Cp.

  9. Thermodynamics of trapped gases: Generalized mechanical variables, equation of state, and heat capacity

    NASA Astrophysics Data System (ADS)

    Sandoval-Figueroa, Nadia; Romero-Rochín, Víctor

    2008-12-01

    We present the full thermodynamics of an interacting fluid confined by an arbitrary external potential. We show that for each confining potential, there emerge “generalized” volume and pressure variables V and P , that replace the usual volume and hydrostatic pressure of a uniform system. This scheme is validated with the derivation of the virial expansion of the grand potential. We discuss how this approach yields experimentally amenable procedures to find the equation of state of the fluid, P=P(V/N,T) with N the number of atoms, as well as its heat capacity at constant generalized volume CV=CV(V,N,T) . With these two functions, all the thermodynamics properties of the system may be found. As specific examples we study weakly interacting Bose gases trapped by harmonic and by linear quadrupolar potentials within the Hartree-Fock approximation. We claim that this route provides an additional and useful tool to analyze both the thermodynamic variables of an ultracold trapped gas as well as its elementary excitations.

  10. Heat capacity decomposition by partition function zeros for interacting self-avoiding walks

    NASA Astrophysics Data System (ADS)

    Chen, Chi-Ning; Hsieh, Yu-Hsin; Hu, Chin-Kun

    2013-10-01

    A novel method based on partition function zeros is developed to demonstrate the additional advantages by considering both loci of partition function zeros and thermodynamical functions associated with them. With this method, the first pair of complex conjugate zeros (first zeros) can be defined without ambiguity and the critical point of a small system can be defined as the peak position of the heat capacity component associated with the first zeros. For the system with two phase transitions, two pairs of first zeros corresponding to two phase transitions can be identified and two overlapping phase transitions can be well separated. This method is applied to the interacting self-avoiding walk (ISAW) of homopolymer with N monomers on the simple cubic lattice, which has a collapse transition at a higher temperature and a freezing transition at a low temperature. The exact partition functions ZN with N up to 27 are calculated and our approach gives a clear scenario for the collapse and the freezing transitions.

  11. Observation of low heat capacities for vapor-deposited glasses of indomethacin as determined by AC nanocalorimetry

    SciTech Connect

    Kearns, Kenneth L.; Whitaker, Katherine R.; Ediger, M. D.; Huth, Heiko; Schick, Christoph

    2010-07-07

    Highly stable glass films of indomethacin (IMC) with thicknesses ranging from 75 to 2900 nm were prepared by physical vapor deposition. Alternating current (AC) nanocalorimetry was used to evaluate the heat capacity and kinetic stability of the glasses as a function of thickness. Glasses deposited at a substrate temperature of 0.84T{sub g} displayed heat capacities that were approximately 19 J/(mol K) (4.5%) lower than glasses deposited at T{sub g} (315 K) or the ordinary glass prepared by cooling the liquid. This difference in heat capacity was observed over the entire thickness range and is significantly larger than the {approx}2 J/(mol K) (0.3%) difference previously observed between aged and ordinary glasses. The vapor-deposited glasses were isothermally transformed into the supercooled liquid above T{sub g}. Glasses with low heat capacities exhibited high kinetic stability. The transformation time increased by an order of magnitude as the film thickness increased from 75 to 600 nm and was independent of film thickness for the thickest films. We interpret these results to indicate that the transformation of stable glass into supercooled liquid can occur by either a surface-initiated or bulk mechanism. In these experiments, the structural relaxation time of the IMC supercooled liquid was observed to be nearly independent of sample thickness.

  12. Calibration of High Temperature Thermal Conductivity System: New Algorithm to Measure Heat Capacity Using Flash Thermal Diffusivity in Thermoelectric Materials

    NASA Technical Reports Server (NTRS)

    Deb, Rahul; Snyder, Jeff G.

    2005-01-01

    A viewgraph presentation describing thermoelectric materials, an algorithm for heat capacity measurements and the process of flash thermal diffusivity. The contents include: 1) What are Thermoelectrics?; 2) Thermoelectric Applications; 3) Improving Thermoelectrics; 4) Research Goal; 5) Flash Thermal Diffusivity; 6) Background Effects; 7) Stainless Steel Comparison; 8) Pulse Max Integral; and 9) Graphite Comparison Algorithm.

  13. Heat capacity of aqueous monoethanolamine, diethanolamine, N-methyldiethanolamine, and N-methyldiethanolamine-based blends with carbon dioxide

    SciTech Connect

    Weiland, R.H.; Dingman, J.C.; Cronin, D.B.

    1997-09-01

    New data are reported on the heat capacity of CO{sub 2}-loaded, aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), N-methyldiethanolamine (MDEA), and aqueous MDEA-based blends with MEA and DEA. The work reported here was motivated by the need to quantify the effect of acid gas loading on the important physical properties of gas-sweetening solvents.

  14. Negative thermal expansion and anomalies of heat capacity of LuB50 at low temperatures

    SciTech Connect

    Novikov, V. V.; Zhemoedov, N. A.; Matovnikov, A. V.; Mitroshenkov, N. V.; Kuznetsov, S. V.; Bud'ko, S. L.

    2015-07-20

    Heat capacity and thermal expansion of LuB50 boride were experimentally studied in the 2–300 K temperature range. The data reveal an anomalous contribution to the heat capacity at low temperatures. The value of this contribution is proportional to the first degree of temperature. It was identified that this anomaly in heat capacity is caused by the effect of disorder in the LuB50 crystalline structure and it can be described in the soft atomic potential model (SAP). The parameters of the approximation were determined. The temperature dependence of LuB50 heat capacity in the whole temperature range was approximated by the sum of SAP contribution, Debye and two Einstein components. The parameters of SAP contribution for LuB50 were compared to the corresponding values for LuB66, which was studied earlier. Negative thermal expansion at low temperatures was experimentally observed for LuB50. The analysis of the experimental temperature dependence for the Gruneisen parameter of LuB50 suggested that the low-frequency oscillations, described in SAP mode, are responsible for the negative thermal expansion. As a result, the glasslike character of the behavior of LuB50 thermal characteristics at low temperatures was confirmed.

  15. Thermal diffusivity and heat capacity of SiGe/Si superlattice from 374 K to 674 K

    NASA Astrophysics Data System (ADS)

    Davidson, Anthony L.; Twigg, Mark; Thompson, Phillip E.; Worchesky, Terrance; Aifer, Edward

    2015-10-01

    In this work, we examine the thermal diffusivity of Si/SiGe thin-film superlattice (SL) structures and use these results with pervious thermal conductivity results to calculate the heat capacity from 374 K to 674 K. The thermal properties of semiconductor layered structures can be altered through the use of SL structures. This alteration occurs through two possible mechanisms: increased phonon scattering due to rough interfaces and phonon zone folding due to boundary conditions of the propagating waves. Examining the heat capacity allows for the observation of phonon zone folding effects while limiting effects due to scattering. Structures studied here consist of SiGe SLs grown at different temperatures and with varying SL spacing allowing the examination of period and crystallinity effects on thermal properties. Previously reported results show that for SL structures both crystalline and polycrystalline have a thermal conductivity of approximately 1 W/mK measured over temperatures ranging from 374 K to 674 K. In this work, thermal diffusivity was measured through laser flash analysis, with crystalline SL structures showing values <1 mm2/s, while the thermal diffusivity of the polycrystalline structure was found to be twice that of the crystalline structure over the temperature range. In all instances, the heat capacities for the SL structures are found to be lower than that for a uniform thin film alloy, indicating a significant contribution of phonon dispersion modification to the heat capacity.

  16. Adiabatic Halo Formation

    SciTech Connect

    Bazzani, A.; Turchetti, G.; Benedetti, C.; Rambaldi, S.; Servizi, G.

    2005-06-08

    In a high intensity circular accelerator the synchrotron dynamics introduces a slow modulation in the betatronic tune due to the space-charge tune depression. When the transverse motion is non-linear due to the presence of multipolar effects, resonance islands move in the phase space and change their amplitude. This effect introduces the trapping and detrapping phenomenon and a slow diffusion in the phase space. We apply the neo-adiabatic theory to describe this diffusion mechanism that can contribute to halo formation.

  17. Heat capacities and entropies of sillimanite, fibrolite, andalusite, kyanite, and quartz and the Al2SiO5 phase diagram

    USGS Publications Warehouse

    Hemingway, B.S.; Robie, R.A.; Evans, H.T., Jr.; Kerrick, Derrill M.

    1991-01-01

    Low-temperature heat capacities for sillimanite, fibrolite, and both fine-grained and coarse-grained quartz have been measured. Superambient heat capacities have been measured for four sillimanite, two andalusite, one kyanite, and two fibrolite samples. Equations are recommended for the temperature dependence of the heat capacities of kyanite, andalusite, sillimanite, and fibrolite. The heat capacity functions have been combined with thermal expansion (fibrolite and sillimanite reported here), enthalpy of solution, and phase equilibrium data in order to construct a phase diagram for the Al2SiO5 polymorphs. -from Authors

  18. Differential scanning calorimetry of coal

    NASA Technical Reports Server (NTRS)

    Gold, P. I.

    1978-01-01

    Differential scanning calorimetry studies performed during the first year of this project demonstrated the occurrence of exothermic reactions associated with the production of volatile matter in or near the plastic region. The temperature and magnitude of the exothermic peak were observed to be strongly affected by the heating rate, sample mass and, to a lesser extent, by sample particle size. Thermal properties also were found to be influenced by oxidation of the coal sample due to weathering effects.

  19. Measurement of the Heat Capacity of He-II Under a Heat Current Near the Lambda Transition

    NASA Technical Reports Server (NTRS)

    Harter, Alexa W.; Lee, Richard A. M.; Chui, Talso C. P.; Goodstein, David L.

    2000-01-01

    We present preliminary measurements of the heat capacity of superfluid helium-4 under an applied heat current near the lambda transition. The calorimeter is a standard cylindrical thermal conductivity cell with a 0.6 mm gap between two copper endplates. The sidewall is made of stainless steel. A heat current density in the range of 1 to 4 microW/sq cm is applied through the helium sample while a pulse method is used to measure the heat capacity. Temperature changes are recorded with high-resolution thermometers (HRTs) located on the top and bottom endplates. Corrections are made to the readings of the HRTs to account for the Kapitza boundary resistance and the anomalous Kapitza boundary resistance. After the corrections, both the top and the bottom HRTs. give the same heat capacity values. The heat capacity is found to be much larger than the prediction of recent theories. We also plotted our data on a scaled plot to test the prediction of scaling by the theories. The result and its interpretation will be presented. The cell height was deliberately made to be thin to reduce the effects of gravity. Nonetheless, gravity is expected to have significant effects on the heat capacity data in the temperature range of our measurement. A space experiment would remove this unwanted gravity effect and allow the true physics to be examined. Moreover, in the absence of gravity, a deeper cell can be used allowing HRTs to be mounted on to the sidewall providing direct measurements of the helium temperature, unaffected by the anomalous Kapitza boundary resistance.

  20. Differential Scanning Calorimetry (DSC) for planetary surface exploration

    NASA Technical Reports Server (NTRS)

    Gooding, James L.; Ming, Douglas W.

    1993-01-01

    Differential Scanning Calorimetry (DSC) is the quantitative measurement of the enthalpic response of a material to a systematic change in temperature. In practice, the heat flow into or outward from a sample is measured as the sample is heated or cooled at a carefully controlled rate. DSC superficially resembles, but is not the same as differential thermal analysis (DTA), which is the measurement of temperature differences between a sample and reference material as the pair is heated or cooled. The fundamental properties measured by DSC are enthalpies and temperatures of phase transitions and constant-pressure heat capacities. Depending on instrument design and the nature of the sample, high-quality DSC analyses can be obtained on only a few milligrams of solid materials. DSC requires direct contact with the sample and generally degrades, if not destroys, the sample as a consequence of heating. In laboratory applications, it is common to subject the gaseous effluent from the DSC to analysis by a separate evolved-gas analyzer (EGA).

  1. Novel Anthropometry-Based Calculation of the Body Heat Capacity in the Korean Population.

    PubMed

    Pham, Duong Duc; Lee, Jeong Hoon; Lee, Young Boum; Park, Eun Seok; Kim, Ka Yul; Song, Ji Yeon; Kim, Ji Eun; Leem, Chae Hun

    2015-01-01

    Heat capacity (HC) has an important role in the temperature regulation process, particularly in dealing with the heat load. The actual measurement of the body HC is complicated and is generally estimated by body-composition-specific data. This study compared the previously known HC estimating equations and sought how to define HC using simple anthropometric indices such as weight and body surface area (BSA) in the Korean population. Six hundred participants were randomly selected from a pool of 902 healthy volunteers aged 20 to 70 years for the training set. The remaining 302 participants were used for the test set. Body composition analysis using multi-frequency bioelectrical impedance analysis was used to access body components including body fat, water, protein, and mineral mass. Four different HCs were calculated and compared using a weight-based HC (HC_Eq1), two HCs estimated from fat and fat-free mass (HC_Eq2 and HC_Eq3), and an HC calculated from fat, protein, water, and mineral mass (HC_Eq4). HC_Eq1 generally produced a larger HC than the other HC equations and had a poorer correlation with the other HC equations. HC equations using body composition data were well-correlated to each other. If HC estimated with HC_Eq4 was regarded as a standard, interestingly, the BSA and weight independently contributed to the variation of HC. The model composed of weight, BSA, and gender was able to predict more than a 99% variation of HC_Eq4. Validation analysis on the test set showed a very high satisfactory level of the predictive model. In conclusion, our results suggest that gender, BSA, and weight are the independent factors for calculating HC. For the first time, a predictive equation based on anthropometry data was developed and this equation could be useful for estimating HC in the general Korean population without body-composition measurement. PMID:26529594

  2. Novel Anthropometry-Based Calculation of the Body Heat Capacity in the Korean Population

    PubMed Central

    Pham, Duong Duc; Lee, Jeong Hoon; Lee, Young Boum; Park, Eun Seok; Kim, Ka Yul; Song, Ji Yeon; Kim, Ji Eun; Leem, Chae Hun

    2015-01-01

    Heat capacity (HC) has an important role in the temperature regulation process, particularly in dealing with the heat load. The actual measurement of the body HC is complicated and is generally estimated by body-composition-specific data. This study compared the previously known HC estimating equations and sought how to define HC using simple anthropometric indices such as weight and body surface area (BSA) in the Korean population. Six hundred participants were randomly selected from a pool of 902 healthy volunteers aged 20 to 70 years for the training set. The remaining 302 participants were used for the test set. Body composition analysis using multi-frequency bioelectrical impedance analysis was used to access body components including body fat, water, protein, and mineral mass. Four different HCs were calculated and compared using a weight-based HC (HC_Eq1), two HCs estimated from fat and fat-free mass (HC_Eq2 and HC_Eq3), and an HC calculated from fat, protein, water, and mineral mass (HC_Eq4). HC_Eq1 generally produced a larger HC than the other HC equations and had a poorer correlation with the other HC equations. HC equations using body composition data were well-correlated to each other. If HC estimated with HC_Eq4 was regarded as a standard, interestingly, the BSA and weight independently contributed to the variation of HC. The model composed of weight, BSA, and gender was able to predict more than a 99% variation of HC_Eq4. Validation analysis on the test set showed a very high satisfactory level of the predictive model. In conclusion, our results suggest that gender, BSA, and weight are the independent factors for calculating HC. For the first time, a predictive equation based on anthropometry data was developed and this equation could be useful for estimating HC in the general Korean population without body-composition measurement. PMID:26529594

  3. Unification of the low-energy excitation peaks in the heat capacity that appears in clathrates

    NASA Astrophysics Data System (ADS)

    Wu, Jiazhen; Akagi, Kazuto; Xu, Jingtao; Shimotani, Hidekazu; Huynh, Khuong K.; Tanigaki, Katsumi

    2016-03-01

    We report that anomalous low-energy excitation (ALE) peaks in the heat capacity emerging from single-crystal cage materials can be successfully rationalized in terms of a single unified exponential line for a variety of type-I clathrates by employing a parameter associated with the freedom of space and the modified radii of guest atoms estimated by band calculations. The origin of these low-energy excitations is interpreted in the framework of quasiharmonic van der Waals type guest-host interactions based on a unified picture with the help of first-principles calculations. It is shown that the influence of guest-host ionic and covalent bonding interactions on the phonon anharmonicity, which have so far been considered to play an important role, are not significant as long as high symmetry of the cage structure is preserved. The dominant van der Waals interactions explain the soft vibrational modes of the rattling, which suppress phonon transport and lead to the concept of "phonon-glass electron-crystal" (PGEC) for thermoelectric applications. A few exceptions existing in type-I clathrates, as indicated by deviations from the unified line, suggest that a quasiharmonic potential can become more asymmetric via lower symmetry of the cage structure, towards glasslike disordered states at even lower temperatures. Although the origin of the boson peaks appearing in disordered materials is still under debate due to incomplete information on the real structure, the understanding provided by the present paper for crystalline cage materials may provide information partly applicable to other disordered systems.

  4. Army Solid State Laser Program: Design, Operation, and Mission Analysis for a Heat-Capacity Laser

    SciTech Connect

    Dane, C B; Flath, L; Rotter, M; Fochs, S; Brase, J; Bretney, K

    2001-05-18

    Solid-state lasers have held great promise for the generation of high-average-power, high-quality output beams for a number of decades. However, the inherent difficulty of scaling the active solid-state gain media while continuing to provide efficient cooling has limited demonstrated powers to <5kW. Even at the maximum demonstrated average powers, the output is most often delivered as continuous wave (CW) or as small energy pulses at high pulse repetition frequency (PRF) and the beam divergence is typically >10X the diffraction limit. Challenges posed by optical distortions and depolarization arising from internal temperature gradients in the gain medium of a continuously cooled system are only increased for laser designs that would attempt to deliver the high average power in the form of high energy pulses (>25J) from a single coherent optical aperture. Although demonstrated phase-locking of multiple laser apertures may hold significant promise for the future scaling of solid-state laser systems,1 the continuing need for additional technical development and innovation coupled with the anticipated complexity of these systems effectively limits this approach for near-term multi-kW laser operation outside of a laboratory setting. We have developed and demonstrated a new operational mode for solid-state laser systems in which the cooling of the gain medium is separated in time from the lasing cycle. In ''heat-capacity'' operation, no cooling takes place during lasing. The gain medium is pumped very uniformly and the waste heat from the excitation process is stored in the solid-state gain medium. By depositing the heat on time scales that are short compared to thermal diffusion across the optical aperture, very high average power operation is possible while maintaining low optical distortions. After a lasing cycle, aggressive cooling can then take place in the absence of lasing, limited only by the fracture limit of the solid-state medium. This mode of operation is

  5. Adiabatic Quantum Computing

    NASA Astrophysics Data System (ADS)

    Landahl, Andrew

    2012-10-01

    Quantum computers promise to exploit counterintuitive quantum physics principles like superposition, entanglement, and uncertainty to solve problems using fundamentally fewer steps than any conventional computer ever could. The mere possibility of such a device has sharpened our understanding of quantum coherent information, just as lasers did for our understanding of coherent light. The chief obstacle to developing quantum computer technology is decoherence--one of the fastest phenomena in all of physics. In principle, decoherence can be overcome by using clever entangled redundancies in a process called fault-tolerant quantum error correction. However, the quality and scale of technology required to realize this solution appears distant. An exciting alternative is a proposal called ``adiabatic'' quantum computing (AQC), in which adiabatic quantum physics keeps the computer in its lowest-energy configuration throughout its operation, rendering it immune to many decoherence sources. The Adiabatic Quantum Architectures In Ultracold Systems (AQUARIUS) Grand Challenge Project at Sandia seeks to demonstrate this robustness in the laboratory and point a path forward for future hardware development. We are building devices in AQUARIUS that realize the AQC architecture on up to three quantum bits (``qubits'') in two platforms: Cs atoms laser-cooled to below 5 microkelvin and Si quantum dots cryo-cooled to below 100 millikelvin. We are also expanding theoretical frontiers by developing methods for scalable universal AQC in these platforms. We have successfully demonstrated operational qubits in both platforms and have even run modest one-qubit calculations using our Cs device. In the course of reaching our primary proof-of-principle demonstrations, we have developed multiple spinoff technologies including nanofabricated diffractive optical elements that define optical-tweezer trap arrays and atomic-scale Si lithography commensurate with placing individual donor atoms with

  6. Geometry of the Adiabatic Theorem

    ERIC Educational Resources Information Center

    Lobo, Augusto Cesar; Ribeiro, Rafael Antunes; Ribeiro, Clyffe de Assis; Dieguez, Pedro Ruas

    2012-01-01

    We present a simple and pedagogical derivation of the quantum adiabatic theorem for two-level systems (a single qubit) based on geometrical structures of quantum mechanics developed by Anandan and Aharonov, among others. We have chosen to use only the minimum geometric structure needed for the understanding of the adiabatic theorem for this case.…

  7. AB INITIO SIMULATIONS FOR MATERIAL PROPERTIES ALONG THE JUPITER ADIABAT

    SciTech Connect

    French, Martin; Becker, Andreas; Lorenzen, Winfried; Nettelmann, Nadine; Bethkenhagen, Mandy; Redmer, Ronald; Wicht, Johannes

    2012-09-15

    We determine basic thermodynamic and transport properties of hydrogen-helium-water mixtures for the extreme conditions along Jupiter's adiabat via ab initio simulations, which are compiled in an accurate and consistent data set. In particular, we calculate the electrical and thermal conductivity, the shear and longitudinal viscosity, and diffusion coefficients of the nuclei. We present results for associated quantities like the magnetic and thermal diffusivity and the kinematic shear viscosity along an adiabat that is taken from a state-of-the-art interior structure model. Furthermore, the heat capacities, the thermal expansion coefficient, the isothermal compressibility, the Grueneisen parameter, and the speed of sound are calculated. We find that the onset of dissociation and ionization of hydrogen at about 0.9 Jupiter radii marks a region where the material properties change drastically. In the deep interior, where the electrons are degenerate, many of the material properties remain relatively constant. Our ab initio data will serve as a robust foundation for applications that require accurate knowledge of the material properties in Jupiter's interior, e.g., models for the dynamo generation.

  8. Heat capacity and latent heat measurements of CoMnSi using a microcalorimeter.

    PubMed

    Miyoshi, Y; Morrison, K; Moore, J D; Caplin, A D; Cohen, L F

    2008-07-01

    A new method of utilizing a commercial silicon nitride membrane calorimeter to measure the latent heat at a first order phase transition is presented. The method is a direct measurement of the thermoelectric voltage jump induced by the latent heat, in a thermally isolated system ideally suited for single crystal and small microgram samples. We show that when combined with the ac calorimetry technique previously developed, the resultant thermal measurement capabilities are extremely powerful. We demonstrate the applicability of the combined method with measurements on a 100 microm size fragment of CoMnSi exhibiting a sizable magnetocaloric effect near room temperature, and obtain good agreement with previously reported values on bulk samples. PMID:18681727

  9. Phonon spectra and heat capacity of Li2B4O7 and LiB3O5 crystals

    NASA Astrophysics Data System (ADS)

    Maslyuk, V. V.; Bredow, T.; Pfnür, H.

    2004-12-01

    The results of calculations of the phonon dispersion, the vibrational density of states and the heat capacity of lithium tetraborate and lithium triborate crystals are presented. They are obtained in the framework of a potential model that takes into account the non-equivalence of boron atoms in different structural positions (BO3 and BO4 units). A symmetry analysis of the phonon modes at Γ point was performed, and calculated frequencies are compared to experimental spectra. Analysis of Li contributions to the vibrational density of states reveals that the Li-O bonds in both crystals are relatively weak. This is in line with the experimentally observed high mobility of lithium ions at high temperatures. A good agreement between calculated and measured heat capacities from the literature was obtained.

  10. Estimation of the Heat Capacities of Organic Liquids as a Function of Temperature Using Group Additivity. An Amendment

    NASA Astrophysics Data System (ADS)

    Zábranský, Milan; Růžička, Vlastimil

    2004-12-01

    An amendment to a second-order group additivity method for the estimation of the heat capacity of pure organic liquids as a function of temperature in the range from the melting temperature to the normal boiling temperature is reported. The temperature dependence of various group contributions and structural corrections is represented by a series of second order polynomial expressions. The group contribution parameters have been developed from an extended database of more than 1800 recommended heat capacity values. The present method should be more versatile and more accurate than the previous one [Růžička and Domalski, J. Phys. Chem. Ref. Data 22, 597, 619 (1993)] due to the use of a larger database and an improved procedure for parameter calculation.

  11. Theoretical thermodynamics connections between Dual (Left-Handed) and Direct (Right Handed) systems: Entropy, temperature, pressure and heat capacity

    NASA Astrophysics Data System (ADS)

    Flores, J. C.; Palma-Chilla, L.

    2015-11-01

    Spectral frequencies for Dual systems, a subclass of Left Handed materials, are straight connected to their corresponding Direct counterparts (conventional materials). This allows us to link the thermodynamics properties of both. We found analytically these connections for temperature, pressure and heat capacity. Entropies are also correlated being a basic tool to attach thermodynamically both categories of systems. It is explicitly showed that the Dual has negative temperatures and positive pressures.

  12. Laser Measurement of the Speed of Sound in Gases: A Novel Approach to Determining Heat Capacity Ratios and Gas Composition

    ERIC Educational Resources Information Center

    Baum, J. Clayton; Compton, R. N.; Feigerle, Charles S.

    2008-01-01

    The speed of sound is measured in several gases using a pulsed laser to create a micro-spark on a carbon rod and a microphone connected to a digital oscilloscope to measure the time-of-flight of the resulting shockwave over a known distance. These data are used to calculate the heat capacity ratios (C[subscript p]/C[subscript V]) of the gases and…

  13. Heat capacity, glass transition temperature, size of cooperatively rearranging regions, and network connectivity of sodium silicate and alkali borate glasses

    SciTech Connect

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

    1994-07-01

    The radius of cooperatively rearranging domains at the glass transition in sodium silicate glasses and the number of bridging oxygen atoms in these domains are assessed within the framework of the kinetic theory of thermal fluctuations. The tendencies of the heat capacity, T{sub g}, and the cooperative rearrangement scale with the alkali oxide concentration in sodium silicate and alkali borate glasses are compared. The points of similarity and distinctions between them are revealed.

  14. Mössbauer spectroscopy, magnetization, magnetic susceptibility, and low temperature heat capacity of α-Na₂NpO₄.

    PubMed

    Smith, Anna L; Hen, Amir; Magnani, Nicola; Sanchez, Jean-Pierre; Colineau, Eric; Griveau, Jean-Christophe; Raison, Philippe E; Caciuffo, Roberto; Konings, Rudy J M; Cheetham, Anthony K

    2016-03-01

    The physical and chemical properties at low temperatures of hexavalent disodium neptunate α-Na2NpO4 are investigated for the first time in this work using Mössbauer spectroscopy, magnetization, magnetic susceptibility, and heat capacity measurements. The Np(VI) valence state is confirmed by the isomer shift value of the Mössbauer spectra, and the local structural environment around the neptunium cation is related to the fitted quadrupole coupling constant and asymmetry parameters. Moreover, magnetic hyperfine splitting is reported below 12.5 K, which could indicate magnetic ordering at this temperature. This interpretation is further substantiated by the existence of a λ-peak at 12.5 K in the heat capacity curve, which is shifted to lower temperatures with the application of a magnetic field, suggesting antiferromagnetic ordering. However, the absence of any anomaly in the magnetization and magnetic susceptibility data shows that the observed transition is more intricate. In addition, the heat capacity measurements suggest the existence of a Schottky-type anomaly above 15 K associated with a low-lying electronic doublet found about 60 cm(-1) above the ground state doublet. The possibility of a quadrupolar transition associated with a ground state pseudoquartet is thereafter discussed. The present results finally bring new insights into the complex magnetic and electronic peculiarities of α-Na2NpO4. PMID:26823458

  15. Calculation of the standard heat capacity at constant pressure for cobalt ferrite-zinc ferrite solid solutions

    SciTech Connect

    Chachanidze, G.D.; Pavlenishvili, T.A.; Machaladze, T.E.; Khutsishvili, D.I.

    1994-08-01

    Magnetic, electrical, and other properties of Co{sub 1-x}Zn{sub x}Fe{sub 2}O{sub 4} solid solutions are widely studied because of their high coercive force and Curie temperature ({Tc}), which makes these compounds applicable in modern electronic devices. However, the information published on their thermodynamic properties is limited. This paper focuses on calculation of the standard heat capacity C{sub p}{sup 0} (298 K) for cobalt zinc ferrites using correlation analysis of the relationship between C{sub p}{sup 0} (298 K) and the saturation magnetic moment {mu}{sub o}. The authors studied the solid solutions Co{sub 1-x}Zn{sub x}Fe{sub 2}O{sub 4} (x = 0.2, 0.4, 0.5, 0.6, and 0.8), whose magnetic and thermal parameters, crucial in our calculations, are known to be strongly dependent on the preparation conditions. An equation was derived for calculation of the standard heat capacity at constant pressure from the saturation magnetic moment of Co{sub 1-x}Zn{sub x}Fe{sub 2}O{sub 4} solid solutions. The equation allows a satisfactory estimation of the standard heat capacity at 298 Kelvin for any cobalt ferrite-zinc ferrite solid, providing the saturation magnetic moment is available.

  16. Thermal-Diffusivity and Heat-Capacity Measurements of Sandstone at High Temperatures Using Laser Flash and DSC Methods

    NASA Astrophysics Data System (ADS)

    Abdulagatov, I. M.; Abdulagatova, Z. Z.; Kallaev, S. N.; Bakmaev, A. G.; Ranjith, P. G.

    2015-04-01

    The well-known contact-free, laser-flash method was used for measurement of the thermal diffusivity of natural sandstone samples. The experimental procedure was conducted using the microflash apparatus (LFA 457). The measurements have been made over the temperature range from (302.9 to 774.3) K. The isobaric heat capacities of the same sample were measured over the temperature range from (308 to 763) K using DSC 204 F1. Uncertainties are 3 % and 1 % for and , respectively. Measured values of and together with density data were used to calculate the thermal conductivity of sandstone. Theoretically based correlations for the thermal diffusivity (damped harmonic oscillator, DHO) and heat capacity (Debye and Einstein theories) were adopted to accurately represent the measured data. Correlation equations for the thermal diffusivity and heat capacity have been developed using the well-known theoretical asymptotic behavior of and for various temperature ranges (low- and high-temperature limits). The microscopic nature of the effect of temperature on and behavior of sandstone is discussed. Detailed interpretation and testing of the measured property data for sandstone using various existing theoretical and empirical models, in order to check their accuracy, predictive capability, and applicability, are provided.

  17. Stepwise heat-capacity change at an orientation transition in liquid crystals

    NASA Astrophysics Data System (ADS)

    Aya, Satoshi; Sasaki, Yuji; Pociecha, Damian; Araoka, Fumito; Górecka, Ewa; Ema, Kenji; Muševič, Igor; Orihara, Hiroshi; Ishikawa, Ken; Takezoe, Hideo

    2014-02-01

    During a phase transition in a bulk material, heat is exchanged with matter to balance the changes in the internal energy and the entropy of the system. Here we report on the thermal detection of a surface-mediated anchoring transition, a spontaneous and discontinuous orientation change between planar (P) and homeotropic (H) alignments within a single nematic phase by changing temperature. In this case a stepwise change in the heat flow, similar to a glass transition, is observed by means of high-resolution differential scanning calorimetry. We found that the jump in the specific heat does not depend on the sample volume, although the contribution of molecules in the vicinity of surfaces, which trigger the transition, becomes less with increasing the sample volume. This means that different molecular orientations, H and P, with respect to surfaces have different thermodynamic free energies. We also address why the anchoring transition occurs by means of grazing-incidence x-ray diffraction measurements, which clearly reveal the formation of quasismectic layers parallel to surfaces in the nematic phase.

  18. Ambient isobaric heat capacities, C(p,m), for ionic solids and liquids: an application of volume-based thermodynamics (VBT).

    PubMed

    Glasser, Leslie; Jenkins, H Donald Brooke

    2011-09-01

    Thermodynamic properties, such as standard entropy, among others, have been shown to correlate well with formula volume, V(m), thus permitting prediction of these properties on the basis of chemical formula and density alone, with no structural detail required. We have termed these procedures "volume-based thermodynamics" (VBT). We here extend these studies to ambient isobaric heat capacities, C(p,m), of a wide range of materials. We show that heat capacity is strongly linearly correlated with formula volume for large sets of minerals, for ionic solids in general, and for ionic liquids and that the results demonstrate that the Neumann-Kopp rule (additivity of heat capacity contributions per atom) is widely valid for ionic materials, but the smaller heat capacity contribution per unit volume for ionic liquids is noted and discussed. Using these correlations, it is possible to predict values of ambient (298 K) heat capacities quite simply. We also show that the heat capacity contribution of water molecules of crystallization is remarkably constant, at 41.3 ± 4.7 J K(-1) (mol of water)(-1), so that the heat capacities of various hydrates may be reliably estimated from the values of their chemical formula neighbors. This result complements similar observations that we have reported for other thermodynamic differences of hydrates. PMID:21812409

  19. Non-isothermal decomposition kinetics, heat capacity and thermal safety of 37.2/44/16/2.2/0.2/0.4-GAP/CL-20/Al/N-100/PCA/auxiliaries mixture.

    PubMed

    Zhang, Jiao-Qiang; Gao, Hong-Xu; Ji, Tie-Zheng; Xu, Kang-Zhen; Hu, Rong-Zu

    2011-10-15

    The specific heat capacity (C(p)) of 37.2/44/16/2.2/0.2/0.4-GAP/CL-20/Al/N-100/PCA/auxiliaries mixture was determined with the continuous C(p) mode of microcalorimeter. The equation of C(p) with temperature was obtained. The standard molar heat capacity of GAP/CL-20/Al/N-100/PCA/auxiliaries mixture was 1.225 J mol(-1)K(-1) at 298.15K. With the help of the peak temperature (T(p)) from the non-isothermal DTG curves of the mixture at different heating rates (β), the apparent activation energy (E(k) and E(o)) and pre-exponential constant (A(K)) of thermal decomposition reaction obtained by Kissinger's method and Ozawa's method. Using density (ρ) and thermal conductivity (λ), the decomposition heat (Q(d), taking half-explosion heat), Zhang-Hu-Xie-Li's formula, the values (T(e0) and T(p0)) of T(e) and T(p) corresponding to β → 0, thermal explosion temperature (T(be) and T(bp)), adiabatic time-to-explosion (t(TIad)), 50% drop height (H(50)) of impact sensitivity, and critical temperature of hot-spot initiation (T(cr,hot spot)) of thermal explosion of the mixture were calculated. The following results of evaluating the thermal safety of the mixture were obtained: T(be) = 441.64K, T(bp) = 461.66 K, t(Tlad) = 78.0 s (n = 2), t(Tlad) = 74.87 s (n = 1), t(Tlad) = 71.85 s (n = 0), H(50) = 21.33 cm. PMID:21820242

  20. Deconvolution of complex differential scanning calorimetry profiles for protein transitions under kinetic control.

    PubMed

    Toledo-Núñez, Citlali; Vera-Robles, L Iraís; Arroyo-Maya, Izlia J; Hernández-Arana, Andrés

    2016-09-15

    A frequent outcome in differential scanning calorimetry (DSC) experiments carried out with large proteins is the irreversibility of the observed endothermic effects. In these cases, DSC profiles are analyzed according to methods developed for temperature-induced denaturation transitions occurring under kinetic control. In the one-step irreversible model (native → denatured) the characteristics of the observed single-peaked endotherm depend on the denaturation enthalpy and the temperature dependence of the reaction rate constant, k. Several procedures have been devised to obtain the parameters that determine the variation of k with temperature. Here, we have elaborated on one of these procedures in order to analyze more complex DSC profiles. Synthetic data for a heat capacity curve were generated according to a model with two sequential reactions; the temperature dependence of each of the two rate constants involved was determined, according to the Eyring's equation, by two fixed parameters. It was then shown that our deconvolution procedure, by making use of heat capacity data alone, permits to extract the parameter values that were initially used. Finally, experimental DSC traces showing two and three maxima were analyzed and reproduced with relative success according to two- and four-step sequential models. PMID:27402175

  1. Modulated calorimetry of poly(1,4-oxybenzoate), poly(2,6-oxynaphthoate), and their copolymers

    SciTech Connect

    Ma, J; Habenschuss, A; Wunderlich, B

    2008-01-01

    Poly(1,4-oxybenzoate) (POB) and poly(2,6-oxynaphthoate) (PON) and their copolymers which have a well-established phase diagram have been studied with temperature-modulated differential scanning calorimetry (TMDSC). All the analyzed polymers have more than one disordering transition between the glass transition (from 400 to 430 K) and decomposition (starting at 700 K). Above the glass transition, the reversible heat capacity, Cp, increases beyond that calculated from the crystallinity and the known Cp of the solid and melt. This is likely due to an increase of mobility within the crystals and/or a possible rigid-amorphous fraction (mainly for the copolymers). The disordering transitions are largely irreversible, supporting the observation that semicrystalline, linear macromolecules show decreasing amounts of locally reversible melting with increasing rigidity and crystal perfection.

  2. Increment of specific heat capacity of solar salt with SiO2 nanoparticles

    PubMed Central

    2014-01-01

    Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500°C. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable. PACS 65.: Thermal properties of condensed matter; 65.20.-w: Thermal properties of liquids; 65.20.Jk: Studies of thermodynamic properties of specific liquids PMID:25346648

  3. Ferrocyanide safety program: Final report on adiabatic calorimetry and tube propagation tests with synthetic ferrocyanide materials

    SciTech Connect

    Fauske, H.F.; Meacham, J.E.; Cash, R.J.

    1995-09-29

    Based on Fauske and Associates, Inc. Reactive System Screening Tool tests, the onset or initiation temperature for a ferrocyanide-nitrate propagating reaction is about 250 degrees Celcius. This is at about 200 degrees Celcius higher than current waste temperatures in the highest temperature ferrocyanide tanks. Furthermore, for current ambient waste temperatures, the tube propagation tests show that a ferrocyanide concentration of 15.5 wt% or more is required to sustain a propagation reaction in the complete absence of free water. Ignoring the presence of free water, this finding rules out propagating reactions for all the Hanford flowsheet materials with the exception of the ferrocyanide waste produced by the original In Farm flowsheet

  4. Heat capacity, entropy, and magnetic properties of jarosite-group compounds

    NASA Astrophysics Data System (ADS)

    Majzlan, Juraj; Glasnák, Peter; Fisher, Robert A.; White, Mary Anne; Johnson, Michel B.; Woodfield, Brian; Boerio-Goates, Juliana

    2010-10-01

    Jarosite phases are common minerals in acidic, sulfate-rich environments. Here, we report heat capacities ( C p) and standard entropies ( S°) for a number of jarosite samples. Most samples are close to the nominal composition AFe3(SO4)2(OH)6, where A = K, Na, Rb, and NH4. One of the samples has a significant number of defects on the Fe sites and is called the defect jarosite; others are referred to as A-jarosite. The samples, their compositions, and the entropies at T = 298.15 K are:

    Sample Chemical composition S o/(J mol-1 K-1) K-jarosite K0.92(H3O)0.08Fe2.97(SO4)2(OH)5.90(H2O)0.10 427.4 ± 0.7 Na-jarosite Na0.95(H3O)0.05Fe3.00(SO4)2(OH)6.00 436.4 ± 4.4 Rb-jarosite RbFe2.98(SO4)2(OH)5.95(H2O)0.05 411.9 ± 4.1 NH4-jarosite (NH4)0.87(H3O)0.13Fe3.00(SO4)2(OH)6.00
  5. Thermal sensitivity analysis data utilizing Q10 scanning, Boltzmann slope factor and the change of molar heat capacity

    PubMed Central

    Kang, KyeongJin

    2016-01-01

    As a further elaboration of the recently devised Q10 scanning analysis (“Exceptionally high thermal sensitivity of rattlesnake TRPA1 correlates with peak current amplitude” [1]), the interval between current data points at two temperatures was shortened and the resulting parameters representing thermal sensitivities such as peak Q10s and temperature points of major thermosensitivity events are presented for two TRPA1 orthologues from rattlesnakes and boas. In addition, the slope factors from Boltzmann fitting and the change of molar heat capacity of temperature-evoked currents were evaluated and compared as alternative ways of thermal sensitivity appraisal of TRPA1 orthologues. PMID:26870758

  6. Thermal sensitivity analysis data utilizing Q10 scanning, Boltzmann slope factor and the change of molar heat capacity.

    PubMed

    Kang, KyeongJin

    2016-03-01

    As a further elaboration of the recently devised Q10 scanning analysis ("Exceptionally high thermal sensitivity of rattlesnake TRPA1 correlates with peak current amplitude" [1]), the interval between current data points at two temperatures was shortened and the resulting parameters representing thermal sensitivities such as peak Q10s and temperature points of major thermosensitivity events are presented for two TRPA1 orthologues from rattlesnakes and boas. In addition, the slope factors from Boltzmann fitting and the change of molar heat capacity of temperature-evoked currents were evaluated and compared as alternative ways of thermal sensitivity appraisal of TRPA1 orthologues. PMID:26870758

  7. Propogation of the 1(mu) High-Power Beam from a Solid-State Heat-Capacity Laser

    SciTech Connect

    Dane, C B; Moriss, J R; Rubenchik, A M; Boley, C D

    2002-06-25

    A solid-state laser system, used as a directed energy defensive weapon, possesses many compelling logistical advantages over high-average-power chemical laser systems. As an electrically-powered laser, it uses no chemicals, generates no effluents, and requires no specialized logistics support--the laser is recharged by running the vehicle engine. It provides stealth, having low signature operation without the generation of temperature, smoke, or visible light. It is silent in operation, limited only by the onboard vehicle electrical charging and propulsion system. Using the heat-capacity mode of operation, scaling of average power from a solid-state laser has been demonstrated beyond 10kW and work in progress will result in the demonstration of a 100 kW solid-state heat-capacity laser (SSHCL). The heat-capacity approach provides unprecedented power-to-weight ratios in a compact platform that is readily adapted to mobile operation. A conceptual engineering and packaging study has resulted in a 100kW SSHCL design that we believe can be integrated onto a hybrid-electric HMMWV or onto new vehicle designs emerging from the future combat system (FCS) development. 100 kW has been proposed as a power level that demonstrates a significant scaling beyond what has been demonstrated for a solid-state laser system and which could have a significant lethality against target sets of interest. However, the characteristics of heat-capacity laser scaling are such that designs with output powers in excess of 1 MW can be readily formulated. An important question when addressing the military utility of a high-power solid-state laser system is that of the required average power during engagement with a target. The answer to this question is complex, involving atmospheric propagation, beam interaction with the target, and the damage response of the target. Successful target shoot-downs with the THEL deuterium fluoride (DF) laser system provide what is probably the best understanding of

  8. Compressibility, thermal expansion coefficient and heat capacity of CH4 and CO2 hydrate mixtures using molecular dynamics simulations.

    PubMed

    Ning, F L; Glavatskiy, K; Ji, Z; Kjelstrup, S; H Vlugt, T J

    2015-01-28

    Understanding the thermal and mechanical properties of CH4 and CO2 hydrates is essential for the replacement of CH4 with CO2 in natural hydrate deposits as well as for CO2 sequestration and storage. In this work, we present isothermal compressibility, isobaric thermal expansion coefficient and specific heat capacity of fully occupied single-crystal sI-CH4 hydrates, CO2 hydrates and hydrates of their mixture using molecular dynamics simulations. Eight rigid/nonpolarisable water interaction models and three CH4 and CO2 interaction potentials were selected to examine the atomic interactions in the sI hydrate structure. The TIP4P/2005 water model combined with the DACNIS united-atom CH4 potential and TraPPE CO2 rigid potential were found to be suitable molecular interaction models. Using these molecular models, the results indicate that both the lattice parameters and the compressibility of the sI hydrates agree with those from experimental measurements. The calculated bulk modulus for any mixture ratio of CH4 and CO2 hydrates varies between 8.5 GPa and 10.4 GPa at 271.15 K between 10 and 100 MPa. The calculated thermal expansion and specific heat capacities of CH4 hydrates are also comparable with experimental values above approximately 260 K. The compressibility and expansion coefficient of guest gas mixture hydrates increase with an increasing ratio of CO2-to-CH4, while the bulk modulus and specific heat capacity exhibit the opposite trend. The presented results for the specific heat capacities of 2220-2699.0 J kg(-1) K(-1) for any mixture ratio of CH4 and CO2 hydrates are the first reported so far. These computational results provide a useful database for practical natural gas recovery from CH4 hydrates in deep oceans where CO2 is considered to replace CH4, as well as for phase equilibrium and mechanical stability of gas hydrate-bearing sediments. The computational schemes also provide an appropriate balance between computational accuracy and cost for predicting

  9. Heat capacity, structural disorder, and the phase transition in cryolite (NH4)3Ti(O2)F5

    NASA Astrophysics Data System (ADS)

    Flerov, I. N.; Gorev, M. V.; Fokina, V. D.; Molokeev, M. S.; Vasil'Ev, A. D.; Bovina, A. F.; Laptash, N. M.

    2006-08-01

    The heat capacity, T-p phase diagrams, and unit cell parameters of cryolite (NH4)3Ti(O2)F5 were studied over a wide temperature range. A phase transition was found near 226 K, and its thermodynamic characteristics and their dependence on the crystallization conditions were determined. The coordinates and thermal parameters of atoms in the Fm3m phase were refined. An analysis of the electron density distribution and the transition entropy showed that the mechanism of the structural transition involves, above all, rotation of the Ti(O2)F5 octahedra. Possible models of disordering of tetrahedral ammonium groups are considered.

  10. Calorimetry with meta-crystals

    NASA Astrophysics Data System (ADS)

    Auffray, Etiennette; Lecoq, Paul; Mavromanolakis, Georgios

    2011-04-01

    We present the meta-crystals concept, an approach that consists of using both undoped and properly doped heavy crystal fibers of identical material as the active medium of a calorimeter. The undoped fibers behave as Cherenkov radiators while the doped ones behave as scintillators. A dual readout calorimeter can be built with its sensitive volume composed of a mixture of both types of crystals. In addition if the calorimeter is adequately finely segmented it can also function as a particle flow calorimeter at the same time. In this way one could possibly combine the advantages of both the particle flow concept and the dual-readout scheme. We discuss the approach of dual readout calorimetry with meta-crystals made of Lutetium Aluminium Garnet (LuAG) and present studies on the material development, first testbeam activities and results based on simulation for understanding the performance trends. We close with a brief outlook on open issues and further R&D needed to proceed from an ideal conceptual case to the design of a realistic detector.

  11. Effectiveness and humidification capacity investigation of liquid-to-air membrane energy exchanger under low heat capacity ratios at winter air conditions

    NASA Astrophysics Data System (ADS)

    Kassai, Miklos

    2015-06-01

    In this research, a novel small-scale single-panel liquid-to-air membrane energy exchanger has been used to numerically investigate the effect of given number of heat transfer units (4.5), different cold inlet air temperature (1.7, 5.0, 10.0 °C) and different low heat capacity ratio (0.4, 0.5, 0.6, 0.7, 0.8, 0.9) on the steady-state performance of the energy exchanger. This small-scale energy exchanger represents the full-scale prototypes well, saving manufacturing costs and time. Lithium chloride is used as a salt solution in the system and the steady-state total effectiveness of the exchanger is evaluated for winter inlet air conditions. The results show that total effectiveness of the energy exchanger decreases with heat capacity ratio in the mentioned range. Maximum numerical total effectiveness of 97% is achieved for the energy exchanger. Increasing the heat capacity ratio values on given inlet air temperature, the humidification capacity of energy exhanger is also investigated in this paper. The humidification performance increases with heat capacity ratio. The highest humidification performance (4.53 g/kg) can be reached when inlet air temperature is 1.7 °C, and heat capacity ratio is 1.0 in winter inlet air conditions in the range of low heat capacity ratio.

  12. Heat capacity of one-dimensional chains of methane molecules in the outer grooves of carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Bagatskii, M. I.; Sumarokov, V. V.; Barabashko, M. S.

    2016-02-01

    The heat capacity at constant pressure CP of 1D-chains of methane molecules adsorbed in the grooves on the outer surface of the bundles of closed single-walled nanotubes was measured in the temperature range from 2 to 60 K for the first time. The behavior of the temperature dependence of CP below 12 K indicates the presence of a Schottky-type anomaly originated from the tunneling between the lowest energy levels of the rotational spectra of the A, T, and E nuclear-spin species of methane molecules. The feature observed in the vicinity of 14 K is presumably caused by an orientational phase transition, in which the nature of the rotational motion of the molecules changes from libration to hindered rotation. It was found that the rotational heat capacity in the temperature range of 30-40 K is close to that of freely rotating methane molecules. An increase in the derivative dCP(T)/dT above 40 K and the feature in the CP(T) near 52 K are due to the decay of 1D chains of CH4.

  13. Heat capacity peak at the quantum critical point of the transverse Ising magnet CoNb2O6

    PubMed Central

    Liang, Tian; Koohpayeh, S. M.; Krizan, J. W.; McQueen, T. M.; Cava, R. J.; Ong, N. P.

    2015-01-01

    The transverse Ising magnet Hamiltonian describing the Ising chain in a transverse magnetic field is the archetypal example of a system that undergoes a transition at a quantum critical point (QCP). The columbite CoNb2O6 is the closest realization of the transverse Ising magnet found to date. At low temperatures, neutron diffraction has observed a set of discrete collective spin modes near the QCP. Here, we ask if there are low-lying spin excitations distinct from these relatively high-energy modes. Using the heat capacity, we show that a significant band of gapless spin excitations exists. At the QCP, their spin entropy rises to a prominent peak that accounts for 30% of the total spin degrees of freedom. In a narrow field interval below the QCP, the gapless excitations display a fermion-like, temperature-linear heat capacity below 1 K. These novel gapless modes are the main spin excitations participating in, and affected by, the quantum transition. PMID:26146018

  14. Discontinuity in heat capacity of Fe0.5Co0.5(110) alloy thin films

    NASA Astrophysics Data System (ADS)

    Ramírez-Dámaso, G.; Castillo-Alvarado, F.-L.; Cruz-Torres, A.; Rójas-Hernández, E.

    2016-07-01

    In this work we calculate heat capacity of alloy thin films of FeCo on the surface of the plane (110), using three parameters, the concentration x(i), the lattice long range order parameter t(i) and the magnetic order parameter σ(i), being i the number of layers of the thin film. The formulations reported by Hill [1] in the context of small particles and Valenta's model [2] can be applied to the film structure when we treat a thin film as a system divided into subsystems equivalent to two-dimensional parallel layers. The FeCo bulk alloy is completely homogeneous while a thin film have spatial discontinuities in their surfaces. We consider three ferromagnetic thin films formed by 11, 15 and 19 layers in the Helmholtz's free energy, which is minimized applying their first partial derivatives with respect to chemical composition, long range order parameter and magnetic order parameter. We calculate internal energy and heat capacity as a function of temperature and we verify that have two jumps as are reported in literature for the bulk; there are many results of bulk or surface effects of FeCo, but no enough results about ferromagnetic FeCo thin films and this fact does this work interesting.

  15. Prediction of heat of melting and heat capacity of inorganic liquids by the method of group contributions

    SciTech Connect

    Williams, J.D.; Eakman, J.M.; Montoya, M.M.

    1997-11-17

    Complex salts and salt/oxide combinations are being considered for the immobilization and storage or disposal of hazardous or radioactive wastes. There is very little information concerning such fundamental properties as heat of fusion and heat capacities for many of these inorganic materials. This work focuses on the use of elements or simple functional groups to estimate some of these fundamental thermodynamic properties for a variety of inorganic compounds. The major emphasis will be on properties for a variety of inorganic compounds. The major emphasis will be on properties for which some ancillary information may be easily measured, but which may be very difficult to measure directly. An example of such a property is the heat of fusion (or melting). The melting temperature for most pure materials is relatively easy to measure. However, the actual amount of energy required to liquefy, or conversely, the amount of energy which must be removed to solidify those same materials has not been measured. Similarly, important properties such as heat capacities of liquids are unavailable for many compounds. Such information is essential in the chemical industry and are paramount for chemical engineers if they are to design, build and operate plants and facilities in an economical and efficient manner.

  16. Heat capacity peak at the quantum critical point of the transverse Ising magnet CoNb2O6

    NASA Astrophysics Data System (ADS)

    Liang, Tian; Koohpayeh, S. M.; Krizan, J. W.; McQueen, T. M.; Cava, R. J.; Ong, N. P.

    2015-07-01

    The transverse Ising magnet Hamiltonian describing the Ising chain in a transverse magnetic field is the archetypal example of a system that undergoes a transition at a quantum critical point (QCP). The columbite CoNb2O6 is the closest realization of the transverse Ising magnet found to date. At low temperatures, neutron diffraction has observed a set of discrete collective spin modes near the QCP. Here, we ask if there are low-lying spin excitations distinct from these relatively high-energy modes. Using the heat capacity, we show that a significant band of gapless spin excitations exists. At the QCP, their spin entropy rises to a prominent peak that accounts for 30% of the total spin degrees of freedom. In a narrow field interval below the QCP, the gapless excitations display a fermion-like, temperature-linear heat capacity below 1 K. These novel gapless modes are the main spin excitations participating in, and affected by, the quantum transition.

  17. Heat capacity peak at the quantum critical point of the transverse Ising magnet CoNb2O6.

    PubMed

    Liang, Tian; Koohpayeh, S M; Krizan, J W; McQueen, T M; Cava, R J; Ong, N P

    2015-01-01

    The transverse Ising magnet Hamiltonian describing the Ising chain in a transverse magnetic field is the archetypal example of a system that undergoes a transition at a quantum critical point (QCP). The columbite CoNb2O6 is the closest realization of the transverse Ising magnet found to date. At low temperatures, neutron diffraction has observed a set of discrete collective spin modes near the QCP. Here, we ask if there are low-lying spin excitations distinct from these relatively high-energy modes. Using the heat capacity, we show that a significant band of gapless spin excitations exists. At the QCP, their spin entropy rises to a prominent peak that accounts for 30% of the total spin degrees of freedom. In a narrow field interval below the QCP, the gapless excitations display a fermion-like, temperature-linear heat capacity below 1 K. These novel gapless modes are the main spin excitations participating in, and affected by, the quantum transition. PMID:26146018

  18. On the heat capacities of M2AlC (M=Ti,V,Cr) ternary carbides

    NASA Astrophysics Data System (ADS)

    Drulis, Monika K.; Drulis, H.; Gupta, S.; Barsoum, M. W.; El-Raghy, T.

    2006-05-01

    In this paper, we report on the heat capacities cp of bulk polycrystalline samples of Ti2AlC, V2AlC, and Cr2AlC in the 3-260 K temperature range. Given the structural and chemical similarities of these compounds it is not surprising that the cp's and their temperature dependencies were quite similar. Nevertheless, at all temperatures the heat capacity of Cr2AlC was higher than the other two. The density of states at the Fermi level were 3.9, 7.5, and 14.6 (eV unit cell)-1 for Ti2AlC, V2AlC, and Cr2AlC, respectively. The results obtained are analyzed using the Debye and Einstein model approximations for cp. Good description of cp is obtained if one assumes that nine phonon modes vibrate according to the Debye model approximation whereas the remaining 3 of 12 modes expected for M2AlC formula unit fulfill an Einstein-like phonon vibration pattern. Debye temperatures θD describing acoustic phonon and Einstein temperature θE describing optical phonon contributions have been estimated for the studied compounds. The Debye temperatures are reasonably high and fall in the range of 600-700 K. A linear dependence was found between the number of d electrons along the row Ti, V, and Cr and the density of states at the Fermi level.

  19. Heat capacity of the site-diluted spin dimer system Ba₃(Mn1-xVx)₂O₈

    DOE PAGESBeta

    Samulon, E. C.; Shapiro, M. C.; Fisher, I. R.

    2011-08-05

    Heat-capacity and susceptibility measurements have been performed on the diluted spin dimer compound Ba₃(Mn1-xVx)₂O₈. The parent compound Ba₃Mn₂O₈ is a spin dimer system based on pairs of antiferromagnetically coupled S=1, 3d² Mn⁵⁺ ions such that the zero-field ground state is a product of singlets. Substitution of nonmagnetic S=0, 3d⁰ V⁵⁺ ions leads to an interacting network of unpaired Mn moments, the low-temperature properties of which are explored in the limit of small concentrations 0≤x≤0.05. The zero-field heat capacity of this diluted system reveals a progressive removal of magnetic entropy over an extended range of temperatures, with no evidence for amore » phase transition. The concentration dependence does not conform to expectations for a spin-glass state. Rather, the data suggest a low-temperature random singlet phase, reflecting the hierarchy of exchange energies found in this system.« less

  20. Improving the accuracy of the transient plane source method by correcting probe heat capacity and resistance influences

    NASA Astrophysics Data System (ADS)

    Li, Yanning; Shi, Chunfeng; Liu, Jian; Liu, Errui; Shao, Jian; Chen, Zhi; Dorantes-Gonzalez, Dante J.; Hu, Xiaotang

    2014-01-01

    The transient plane source (TPS) method is a relatively newly developed transient approach for thermal conductivity measurement. Compared with the steady-state method, it is fast, and applicable to either solid, liquid or gas state materials; therefore, it has gained much popularity in recent years. However, during measurement, the measured power is influenced by the heat capacity of the electrical isolation films as well as the electrical resistance change of the metallic thin wire of the TPS probes. This further influences the measurement precision. Meanwhile, these two factors have been ignored in the traditional model of TPS developed by Gustafsson. In this paper, the influence of both the heat capacity and the resistance change of the TPS probe on the measured power is studied, and mathematical formulas relating the two factors and their respective corrections are deduced. Thereafter an improved model is suggested based on the traditional TPS model and the above theoretical models. Experiments on polymethylmethacrylate (PMMA) standard materials have been conducted using a home-made system, including TPS probes, data acquisition module and analysis software. The results show that the improved model can effectively improve the measurement precision of the TPS method by about 1.8-2.3% as evaluated by relative standard deviation.

    1. Adiabatic evolution of plasma equilibrium

      PubMed Central

      Grad, H.; Hu, P. N.; Stevens, D. C.

      1975-01-01

      A new theory of plasma equilibrium is introduced in which adiabatic constraints are specified. This leads to a mathematically nonstandard structure, as compared to the usual equilibrium theory, in which prescription of pressure and current profiles leads to an elliptic partial differential equation. Topologically complex configurations require further generalization of the concept of adiabaticity to allow irreversible mixing of plasma and magnetic flux among islands. Matching conditions across a boundary layer at the separatrix are obtained from appropriate conservation laws. Applications are made to configurations with planned islands (as in Doublet) and accidental islands (as in Tokamaks). Two-dimensional, axially symmetric, helically symmetric, and closed line equilibria are included. PMID:16578729

    2. Automatic calorimetry system monitors RF power

      NASA Technical Reports Server (NTRS)

      Harness, B. W.; Heiberger, E. C.

      1969-01-01

      Calorimetry system monitors the average power dissipated in a high power RF transmitter. Sensors measure the change in temperature and the flow rate of the coolant, while a multiplier computes the power dissipated in the RF load.

    3. Pressure Oscillations in Adiabatic Compression

      ERIC Educational Resources Information Center

      Stout, Roland

      2011-01-01

      After finding Moloney and McGarvey's modified adiabatic compression apparatus, I decided to insert this experiment into my physical chemistry laboratory at the last minute, replacing a problematic experiment. With insufficient time to build the apparatus, we placed a bottle between two thick textbooks and compressed it with a third textbook forced…

    4. Adiabatic dynamics of magnetic vortices

      NASA Astrophysics Data System (ADS)

      Papanicolaou, N.

      1994-03-01

      We formulate a reasonably detailed adiabatic conjecture concerning the dynamics of skew deflection of magnetic vortices in a field gradient, which is expected to be valid at sufficiently large values of the winding number. The conjecture is consistent with the golden rule used to describe the dynamics of realistic magnetic bubbles and is verified here numerically within the 2-D isotropic Heisenberg model.

    5. Calculation of protein heat capacity from replica-exchange molecular dynamics simulations with different implicit solvent models.

      PubMed

      Yeh, In-Chul; Lee, Michael S; Olson, Mark A

      2008-11-27

      The heat capacity has played a major role in relating microscopic and macroscopic properties of proteins and their disorder-order phase transition of folding. Its calculation by atomistic simulation methods remains a significant challenge due to the complex and dynamic nature of protein structures, their solvent environment, and configurational averaging. To better understand these factors on calculating a protein heat capacity, we provide a comparative analysis of simulation models that differ in their implicit solvent description and force-field resolution. Our model protein system is the src Homology 3 (SH3) domain of alpha-spectrin, and we report a series of 10 ns replica-exchange molecular dynamics simulations performed at temperatures ranging from 298 to 550 K, starting from the SH3 native structure. We apply the all-atom CHARMM22 force field with different modified analytical generalized Born solvent models (GBSW and GBMV2) and compare these simulation models with the distance-dependent dielectric screening of charge-charge interactions. A further comparison is provided with the united-atom CHARMM19 plus a pairwise GB model. Unfolding-folding transition temperatures of SH3 were estimated from the temperature-dependent profiles of the heat capacity, root-mean-square distance from the native structure, and the fraction of native contacts, each calculated from the density of states by using the weighted histogram analysis method. We observed that, for CHARMM22, the unfolding transition and energy probability density were quite sensitive to the implicit solvent description, in particular, the treatment of the protein-solvent dielectric boundary in GB models and their surface-area-based hydrophobic term. Among the solvent models tested, the calculated melting temperature varied in the range 353-438 K and was higher than the experimental value near 340 K. A reformulated GBMV2 model of employing a smoother molecular-volume dielectric interface was the most accurate

    6. Transitionless driving on adiabatic search algorithm

      SciTech Connect

      Oh, Sangchul; Kais, Sabre

      2014-12-14

      We study quantum dynamics of the adiabatic search algorithm with the equivalent two-level system. Its adiabatic and non-adiabatic evolution is studied and visualized as trajectories of Bloch vectors on a Bloch sphere. We find the change in the non-adiabatic transition probability from exponential decay for the short running time to inverse-square decay in asymptotic running time. The scaling of the critical running time is expressed in terms of the Lambert W function. We derive the transitionless driving Hamiltonian for the adiabatic search algorithm, which makes a quantum state follow the adiabatic path. We demonstrate that a uniform transitionless driving Hamiltonian, approximate to the exact time-dependent driving Hamiltonian, can alter the non-adiabatic transition probability from the inverse square decay to the inverse fourth power decay with the running time. This may open up a new but simple way of speeding up adiabatic quantum dynamics.

    7. Transitionless driving on adiabatic search algorithm

      NASA Astrophysics Data System (ADS)

      Oh, Sangchul; Kais, Sabre

      2014-12-01

      We study quantum dynamics of the adiabatic search algorithm with the equivalent two-level system. Its adiabatic and non-adiabatic evolution is studied and visualized as trajectories of Bloch vectors on a Bloch sphere. We find the change in the non-adiabatic transition probability from exponential decay for the short running time to inverse-square decay in asymptotic running time. The scaling of the critical running time is expressed in terms of the Lambert W function. We derive the transitionless driving Hamiltonian for the adiabatic search algorithm, which makes a quantum state follow the adiabatic path. We demonstrate that a uniform transitionless driving Hamiltonian, approximate to the exact time-dependent driving Hamiltonian, can alter the non-adiabatic transition probability from the inverse square decay to the inverse fourth power decay with the running time. This may open up a new but simple way of speeding up adiabatic quantum dynamics.

    8. Transitionless driving on adiabatic search algorithm.

      PubMed

      Oh, Sangchul; Kais, Sabre

      2014-12-14

      We study quantum dynamics of the adiabatic search algorithm with the equivalent two-level system. Its adiabatic and non-adiabatic evolution is studied and visualized as trajectories of Bloch vectors on a Bloch sphere. We find the change in the non-adiabatic transition probability from exponential decay for the short running time to inverse-square decay in asymptotic running time. The scaling of the critical running time is expressed in terms of the Lambert W function. We derive the transitionless driving Hamiltonian for the adiabatic search algorithm, which makes a quantum state follow the adiabatic path. We demonstrate that a uniform transitionless driving Hamiltonian, approximate to the exact time-dependent driving Hamiltonian, can alter the non-adiabatic transition probability from the inverse square decay to the inverse fourth power decay with the running time. This may open up a new but simple way of speeding up adiabatic quantum dynamics. PMID:25494733

    9. Studies in Chaotic adiabatic dynamics

      SciTech Connect

      Jarzynski, C.

      1994-01-01

      Chaotic adiabatic dynamics refers to the study of systems exhibiting chaotic evolution under slowly time-dependent equations of motion. In this dissertation the author restricts his attention to Hamiltonian chaotic adiabatic systems. The results presented are organized around a central theme, namely, that the energies of such systems evolve diffusively. He begins with a general analysis, in which he motivates and derives a Fokker-Planck equation governing this process of energy diffusion. He applies this equation to study the {open_quotes}goodness{close_quotes} of an adiabatic invariant associated with chaotic motion. This formalism is then applied to two specific examples. The first is that of a gas of noninteracting point particles inside a hard container that deforms slowly with time. Both the two- and three-dimensional cases are considered. The results are discussed in the context of the Wall Formula for one-body dissipation in nuclear physics, and it is shown that such a gas approaches, asymptotically with time, an exponential velocity distribution. The second example involves the Fermi mechanism for the acceleration of cosmic rays. Explicit evolution equations are obtained for the distribution of cosmic ray energies within this model, and the steady-state energy distribution that arises when this equation is modified to account for the injection and removal of cosmic rays is discussed. Finally, the author re-examines the multiple-time-scale approach as applied to the study of phase space evolution under a chaotic adiabatic Hamiltonian. This leads to a more rigorous derivation of the above-mentioned Fokker-Planck equation, and also to a new term which has relevance to the problem of chaotic adiabatic reaction forces (the forces acting on slow, heavy degrees of freedom due to their coupling to light, fast chaotic degrees).

    10. Thermodynamic properties underlying the alpha-helix-to-beta-sheet transition, aggregation, and amyloidogenesis of polylysine as probed by calorimetry, densimetry, and ultrasound velocimetry.

      PubMed

      Smirnovas, Vytautas; Winter, Roland; Funck, Theodor; Dzwolak, Wojciech

      2005-10-20

      In this work, we performed a detailed thermodynamic study of an aggregation-prone polypeptide, polylysine, to gain a deeper insight into the scenario of physicochemical events during its unfolding, aggregation, and amyloidogenesis. The precise and simultaneous determination of the partial molar volume, the heat capacity, and the coefficients of thermal expansion, as well as adiabatic and isothermal compressibility of the protein upon unfolding and aggregation, yields a thermodynamic picture of the aggregation process highlighting the importance of volume fluctuations during unfolding and amyloidogenesis of proteins. PMID:16853453

    11. Analytic investigation of the AEM-A/HCMM attitude control system performance. [Application Explorer Missions/Heat Capacity Mapping Mission

      NASA Technical Reports Server (NTRS)

      Lerner, G. M.; Huang, W.; Shuster, M. D.

      1977-01-01

      The Heat Capacity Mapping Mission (HCMM), scheduled for launch in 1978, will be three-axis stabilized relative to the earth in a 600-kilometer altitude, polar orbit. The autonomous attitude control system consists of three torquing coils and a momentum wheel driven in response to error signals computed from data received from an infrared horizon sensor and a magnetometer. This paper presents a simple model of the attitude dynamics and derives the equations that determine the stability of the system during both attitude acquisition (acquisition-mode) and mission operations (mission-mode). Modifications to the proposed mission-mode control laws which speed the system's response to transient attitude errors and reduce the steady-state attitude errors are suggested. Numerical simulations are performed to validate the results obtained with the simple model.

    12. A Monte Carlo simulation study of protein-induced heat capacity changes and lipid-induced protein clustering.

      PubMed Central

      Heimburg, T; Biltonen, R L

      1996-01-01

      Monte Carlo simulations were used to describe the interaction of peripheral and integral proteins with lipids in terms of heat capacity profiles and protein distribution. The simulations were based on a two-state model for the lipid, representing the lipid state as being either gel or fluid. The interaction between neighboring lipids has been taken into account through an unlike nearest neighbor free energy term delta omega, which is a measure of the cooperativity of the lipid transition. Lipid/protein interaction was considered using the experimental observation that the transition midpoints of lipid membranes are shifted upon protein binding, a thermodynamic consequence of different binding constants of protein with fluid or gel lipids. The difference of the binding free energies was used as an additional parameter to describe lipid-protein interaction. The heat capacity profiles of lipid/protein complexes could be well described for both peripheral and integral proteins. Binding of proteins results in a shift and an asymmetric broadening of the melting profile. The model results in a coexistence of gel and fluid lipid domains in the proximity of the thermotropic transition. As a consequence, bound peripheral proteins aggregate in the temperature range of the lipid transition. Integral proteins induce calorimetric melting curves that are qualitatively different from that of peripheral proteins and aggregate in either gel or liquid crystalline lipid phase. The results presented here are in good agreement with calorimetric experiments on lipid-protein complexes and have implementations for the functional control of proteins. Images FIGURE 1 FIGURE 5 FIGURE 8 PMID:8770189

    13. Calculation of thermal conductivity, thermal diffusivity and specific heat capacity of sedimentary rocks using petrophysical well logs

      NASA Astrophysics Data System (ADS)

      Fuchs, Sven; Balling, Niels; Förster, Andrea

      2015-12-01

      In this study, equations are developed that predict for synthetic sedimentary rocks (clastics, carbonates and evapourates) thermal properties comprising thermal conductivity, specific heat capacity and thermal diffusivity. The rock groups are composed of mineral assemblages with variable contents of 15 major rock-forming minerals and porosities of 0-30 per cent. Petrophysical properties and their well-logging-tool-characteristic readings were assigned to these rock-forming minerals and to pore-filling fluids. Relationships are explored between each thermal property and other petrophysical properties (density, sonic interval transit time, hydrogen index, volume fraction of shale and photoelectric absorption index) using multivariate statistics. The application of these relations allows computing continuous borehole profiles for each rock thermal property. The uncertainties in the prediction of each property vary depending on the selected well-log combination. Best prediction is in the range of 2-8 per cent for the specific heat capacity, of 5-10 per cent for the thermal conductivity, and of 8-15 for the thermal diffusivity, respectively. Well-log derived thermal conductivity is validated by laboratory data measured on cores from deep boreholes of the Danish Basin, the North German Basin, and the Molasse Basin. Additional validation of thermal conductivity was performed by comparing predicted and measured temperature logs. The maximum deviation between these logs is <3 °C. The thermal-conductivity calculation allowed an evaluation of the depth range in which the palaeoclimatic effect on the subsurface temperature field can be observed in the North German Basin. This effect reduces the surface heat-flow density by 25 mW m-2.

    14. Group additive values for the gas-phase standard enthalpy of formation, entropy and heat capacity of oxygenates.

      PubMed

      Paraskevas, Paschalis D; Sabbe, Maarten K; Reyniers, Marie-Françoise; Papayannakos, Nikos; Marin, Guy B

      2013-11-25

      A complete and consistent set of 60 Benson group additive values (GAVs) for oxygenate molecules and 97 GAVs for oxygenate radicals is provided, which allow to describe their standard enthalpies of formation, entropies and heat capacities. Approximately half of the GAVs for oxygenate molecules and the majority of the GAVs for oxygenate radicals have not been reported before. The values are derived from an extensive and accurate database of thermochemical data obtained by ab initio calculations at the CBS-QB3 level of theory for 202 molecules and 248 radicals. These compounds include saturated and unsaturated, α- and β-branched, mono- and bifunctional oxygenates. Internal rotations were accounted for by using one-dimensional hindered rotor corrections. The accuracy of the database was further improved by adding bond additive corrections to the CBS-QB3 standard enthalpies of formation. Furthermore, 14 corrections for non-nearest-neighbor interactions (NNI) were introduced for molecules and 12 for radicals. The validity of the constructed group additive model was established by comparing the predicted values with both ab initio calculated values and experimental data for oxygenates and oxygenate radicals. The group additive method predicts standard enthalpies of formation, entropies, and heat capacities with chemical accuracy, respectively, within 4 kJ mol(-1) and 4 J mol(-1) K(-1) for both ab initio calculated and experimental values. As an alternative, the hydrogen bond increment (HBI) method developed by Lay et al. (T. H. Lay, J. W. Bozzelli, A. M. Dean, E. R. Ritter, J. Phys. Chem.- 1995, 99, 14514) was used to introduce 77 new HBI structures and to calculate their thermodynamic parameters (Δ(f)H°, S°, C(p)°). The GAVs reported in this work can be reliably used for the prediction of thermochemical data for large oxygenate compounds, combining rapid prediction with wide-ranging application. PMID:24123572

    15. First principles based group additive values for the gas phase standard entropy and heat capacity of hydrocarbons and hydrocarbon radicals.

      PubMed

      Sabbe, Maarten K; De Vleeschouwer, Freija; Reyniers, Marie-Françoise; Waroquier, Michel; Marin, Guy B

      2008-11-27

      In this work a complete and consistent set of 95 Benson group additive values (GAVs) for standard entropies S(o) and heat capacities C(p)(o) of hydrocarbons and hydrocarbon radicals is presented. These GAVs include 46 groups, among which 25 radical groups, which, to the best of our knowledge, have not been reported before. The GAVs have been determined from a set of B3LYP/6-311G(d,p) ideal gas statistical thermodynamics values for 265 species, consistently with previously reported GAVs for standard enthalpies of formation. One-dimensional hindered rotor corrections for all internal rotations are included. The computational methodology has been compared to experimental entropies (298 K) for 39 species, with a mean absolute deviation (MAD) between experiment and calculation of 1.2 J mol(-1) K(-1), and to 46 experimental heat capacities (298 K) with a resulting MAD = 1.8 J mol(-1) K(-1). The constructed database allowed evaluation of corrections on S(o) and C(p)(o) for non-nearest-neighbor effects, which have not been determined previously. The group additive model predicts the S(o) and C(p)(o) within approximately 5 J mol(-1) K(-1) of the ab initio values for 11 of the 14 molecules of the test set, corresponding to an acceptable maximal deviation of a factor of 1.6 on the equilibrium coefficient. The obtained GAVs can be applied for the prediction of S(o) and C(p)(o) for a wide range of hydrocarbons and hydrocarbon radicals. The constructed database also allowed determination of a large set of hydrogen bond increments, which can be useful for the prediction of radical thermochemistry. PMID:18980365

    16. Thermodynamics of nucleotide binding to actomyosin V and VI: a positive heat capacity change accompanies strong ADP binding.

      PubMed

      Robblee, James P; Cao, Wenxiang; Henn, Arnon; Hannemann, Diane E; De La Cruz, Enrique M

      2005-08-01

      We have measured the energetics of ATP and ADP binding to single-headed actomyosin V and VI from the temperature dependence of the rate and equilibrium binding constants. Nucleotide binding to actomyosin V and VI can be modeled as two-step binding mechanisms involving the formation of collision complexes followed by isomerization to states with high nucleotide affinity. Formation of the actomyosin VI-ATP collision complex is much weaker and slower than for actomyosin V. A three-step binding mechanism where actomyosin VI isomerizes between two conformations, one competent to bind ATP and one not, followed by rapid ATP binding best accounts for the data. ADP binds to actomyosin V more tightly than actomyosin VI. At 25 degrees C, the strong ADP-binding equilibria are comparable for actomyosin V and VI, and the different overall ADP affinities arise from differences in the ADP collision complex affinity. The actomyosin-ADP isomerization leading to strong ADP binding is entropy driven at >15 degrees C and occurs with a large, positive change in heat capacity (DeltaC(P) degrees ) for both actomyosin V and VI. Sucrose slows ADP binding and dissociation from actomyosin V and VI but not the overall equilibrium constants for strong ADP binding, indicating that solvent viscosity dampens ADP-dependent kinetic transitions, presumably a tail swing that occurs with ADP binding and release. We favor a mechanism where strong ADP binding increases the dynamics and flexibility of the actomyosin complex. The heat capacity (DeltaC(P) degrees ) and entropy (DeltaS degrees ) changes are greater for actomyosin VI than actomyosin V, suggesting different extents of ADP-induced structural rearrangement. PMID:16042401

    17. Robust adiabatic sum frequency conversion.

      PubMed

      Suchowski, Haim; Prabhudesai, Vaibhav; Oron, Dan; Arie, Ady; Silberberg, Yaron

      2009-07-20

      We discuss theoretically and demonstrate experimentally the robustness of the adiabatic sum frequency conversion method. This technique, borrowed from an analogous scheme of robust population transfer in atomic physics and nuclear magnetic resonance, enables the achievement of nearly full frequency conversion in a sum frequency generation process for a bandwidth up to two orders of magnitude wider than in conventional conversion schemes. We show that this scheme is robust to variations in the parameters of both the nonlinear crystal and of the incoming light. These include the crystal temperature, the frequency of the incoming field, the pump intensity, the crystal length and the angle of incidence. Also, we show that this extremely broad bandwidth can be tuned to higher or lower central wavelengths by changing either the pump frequency or the crystal temperature. The detailed study of the properties of this converter is done using the Landau-Zener theory dealing with the adiabatic transitions in two level systems. PMID:19654679

    18. Heat capacity measurements on UBe13 in rotated magnetic fields: Anisotropic response in the normal state and absence of nodal quasiparticles

      NASA Astrophysics Data System (ADS)

      Shimizu, Yusei; Kittaka, Shunichiro; Sakakibara, Toshiro; Haga, Yoshinori; Yamamoto, Etsuji; Amitsuka, Hiroshi; Tsutsumi, Yasumasa; Machida, Kazushige

      2016-02-01

      In order to gain insight into the superconducting (SC) gap of UBe13, we studied its quasiparticle excitations by means of heat-capacity measurements. Quite unexpectedly, we found the isotropic C(H) ∝ H behavior in low fields at low temperatures, implying the absence of nodal quasiparticle excitations. This result indicates that the SC gap in UBe13 is fully open over the Fermi surfaces. Furthermore, we observed a characteristic oscillation of heat capacity both in the SC and non-Fermi-liquid normal states above ∼2 T, and the angular variation of heat capacity possibly originates from anisotropic magnetic response of the heavy-electron state. Our result regarding the low-energy quasiparticle excitations in the SC and normal states will be a clue to understand the unusual nature of UBe13.

    19. Ideal-Gas Heat Capacity for 2,3,3,3-Tetrafluoropropene (HFO-1234yf) Determined from Speed-of-Sound Measurements

      NASA Astrophysics Data System (ADS)

      Kano, Yuya; Kayukawa, Yohei; Fujii, Kenichi; Sato, Haruki

      2010-12-01

      The isobaric ideal-gas heat capacity for HFO-1234yf, which is expected to be one of the best alternative refrigerants for HFC-134a, was determined on the basis of speed-of-sound measurements in the gaseous phase. The speed of sound was measured by means of the acoustic resonance method using a spherical cavity. The resonance frequency in the spherical cavity containing the sample gas was measured to determine the speed of sound. After correcting for some effects such as the thermal boundary layer and deformation of the cavity on the resonance frequency, the speed of sound was obtained with a relative uncertainty of 0.01 %. Using the measured speed-of-sound data, the acoustic-virial equation was formulated and the isobaric ideal-gas heat capacity was determined with a relative uncertainty of 0.1 %. A temperature correlation function of the isobaric ideal-gas heat capacity for HFO-1234yf was also developed.

    20. Adiabaticity in open quantum systems

      NASA Astrophysics Data System (ADS)

      Venuti, Lorenzo Campos; Albash, Tameem; Lidar, Daniel A.; Zanardi, Paolo

      2016-03-01

      We provide a rigorous generalization of the quantum adiabatic theorem for open systems described by a Markovian master equation with time-dependent Liouvillian L (t ) . We focus on the finite system case relevant for adiabatic quantum computing and quantum annealing. Adiabaticity is defined in terms of closeness to the instantaneous steady state. While the general result is conceptually similar to the closed-system case, there are important differences. Namely, a system initialized in the zero-eigenvalue eigenspace of L (t ) will remain in this eigenspace with a deviation that is inversely proportional to the total evolution time T . In the case of a finite number of level crossings, the scaling becomes T-η with an exponent η that we relate to the rate of the gap closing. For master equations that describe relaxation to thermal equilibrium, we show that the evolution time T should be long compared to the corresponding minimum inverse gap squared of L (t ) . Our results are illustrated with several examples.

    1. Particle Flow Calorimetry at the ILC

      SciTech Connect

      Thomson, M. A.

      2007-03-19

      One of the most important requirements for a detector at the ILC is good jet energy resolution. It is widely believed that the particle flow approach to calorimetry is the key to achieving the goal of 0.3/{radical}(E(GeV)). In contrast to the traditional approach to calorimetry, potentially the performance of particle flow calorimetry is sensitive to the detailed structure of hadronic showers. This paper describes the current performance of the PANDORAPFA particle flow algorithm. For 45 GeV jets in the Tesla TDR detector concept, the ILC jet energy resolution goal is reached. First detector optimisation studies are presented and the aspects of hadronic showers which are most likely to impact particle flow performance are discussed.

    2. Extruded scintillator for the calorimetry applications

      SciTech Connect

      Dyshkant, A.; Rykalin, V.; Pla-Dalmau, A.; Beznosko, D.; /SUNY, Stony Brook

      2006-08-01

      An extrusion line has been installed and successfully operated at FNAL (Fermi National Accelerator Laboratory) in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new Facility will serve to further develop and improve extruded plastic scintillator. Recently progress has been made in producing co-extruded plastic scintillator, thus increasing the potential HEP applications of this Facility. The current R&D work with extruded and co-extruded plastic scintillator for a potential ALICE upgrade, the ILC calorimetry program and the MINERvA experiment show the attractiveness of the chosen strategy for future experiments and calorimetry. We extensively discuss extruded and co-extruded plastic scintillator in calorimetry in synergy with new Solid State Photomultipliers. The characteristics of extruded and co-extruded plastic scintillator will be presented here as well as results with non-traditional photo read-out.

    3. Extruded scintillator for the Calorimetry applications

      SciTech Connect

      Dyshkant, A.; Rykalin, V.; Pla-Dalmau, A.; Beznosko, D.

      2006-10-27

      An extrusion line has been installed and successfully operated at FNAL (Fermi National Accelerator Laboratory) in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new Facility will serve to further develop and improve extruded plastic scintillator. Recently progress has been made in producing co-extruded plastic scintillator, thus increasing the potential HEP applications of this Facility. The current R and D work with extruded and co-extruded plastic scintillator for a potential ALICE upgrade, the ILC calorimetry program and the MINERvA experiment show the attractiveness of the chosen strategy for future experiments and calorimetry. We extensively discuss extruded and co-extruded plastic scintillator in calorimetry in synergy with new Solid State Photomultipliers. The characteristics of extruded and co-extruded plastic scintillator will be presented here as well as results with non-traditional photo read-out.

    4. Invalidity of the quantitative adiabatic condition and general conditions for adiabatic approximations

      NASA Astrophysics Data System (ADS)

      Li, Dafa

      2016-05-01

      The adiabatic theorem was proposed about 90 years ago and has played an important role in quantum physics. The quantitative adiabatic condition constructed from eigenstates and eigenvalues of a Hamiltonian is a traditional tool to estimate adiabaticity and has proven to be the necessary and sufficient condition for adiabaticity. However, recently the condition has become a controversial subject. In this paper, we list some expressions to estimate the validity of the adiabatic approximation. We show that the quantitative adiabatic condition is invalid for the adiabatic approximation via the Euclidean distance between the adiabatic state and the evolution state. Furthermore, we deduce general necessary and sufficient conditions for the validity of the adiabatic approximation by different definitions.

    5. Calculation of Temperature Rise in Calorimetry.

      ERIC Educational Resources Information Center

      Canagaratna, Sebastian G.; Witt, Jerry

      1988-01-01

      Gives a simple but fuller account of the basis for accurately calculating temperature rise in calorimetry. Points out some misconceptions regarding these calculations. Describes two basic methods, the extrapolation to zero time and the equal area method. Discusses the theoretical basis of each and their underlying assumptions. (CW)

    6. Isothermal Titration Calorimetry in the Student Laboratory

      ERIC Educational Resources Information Center

      Wadso, Lars; Li, Yujing; Li, Xi

      2011-01-01

      Isothermal titration calorimetry (ITC) is the measurement of the heat produced by the stepwise addition of one substance to another. It is a common experimental technique, for example, in pharmaceutical science, to measure equilibrium constants and reaction enthalpies. We describe a stirring device and an injection pump that can be used with a…

    7. Final Technical Report CMS fast optical calorimetry

      SciTech Connect

      Winn, David R.

      2012-07-12

      This is the final report of CMS FAST OPTICAL CALORIMETRY, a grant to Fairfield University for development, construction, installation and operation of the forward calorimeter on CMS, and for upgrades of the forward and endcap calorimeters for higher luminosity and radiation damage amelioration.

    8. Liquid argon calorimetry for the SSC

      SciTech Connect

      Gordon, H.A.

      1990-01-01

      Liquid argon calorimetry is a mature technique. However, adapting it to the challenging environment of the SSC requires a large amount of R D. The advantages of the liquid argon approach are summarized and the issues being addressed by the R D program are described. 18 refs.

    9. Heat capacity and thermal expansion anomalies in the nitromethane-1-butanol mixture near its upper critical point

      NASA Astrophysics Data System (ADS)

      Cerdeiriña, C. A.; Troncoso, J.; Carballo, E.; Romaní, L.

      2002-09-01

      The heat capacity per unit volume Cp and density ρ of the nitromethane-1-butanol critical mixture near its upper consolute point are determined in this work. Cp data are obtained at atmospheric pressure as a function of temperature in the one-phase and two-phase regions, using a differential scanning calorimeter. The suitability of DSC for recording Cp as a function of T in the critical region is confirmed by measurements of the nitromethane-cyclohexane mixture, the results being quite consistent with reported data. By fitting the Cp data in the one-phase region, the critical exponent α is found to be 0.110+/-0.014-and hence consistent with the universal accepted value-and the critical amplitude A+=0.0606+/-0.0006 J K-1 cm-3. ρ data were only obtained in the one-phase region, using a vibrating tube densimeter. The amplitude of the density anomaly was found to be C+1=-0.017+/-0.003 g cm-3, which is moderately low in spite of the large difference between the densities of the pure liquids. The thermodynamic consistency of the A+ and C+1 values was examined in relation to the previously reported value for the slope of the critical line dTc/dp. The results of this analysis were consistent with previous work on this matter.

    10. Speed-of-sound measurements and ideal-gas heat capacity for 1,1,1,2-tetrafluoroethane and difluoromethane

      SciTech Connect

      Hozumi, T.; Sato, H.; Watanabe, K.

      1996-09-01

      The speed of sound in gaseous 1,1,1,2-tetrafluoroethane (R-134a, CF{sub 3}CH{sub 2}F) and difluoromethane (R-32, CH{sub 2}F{sub 2}) has been measured by using a spherical resonator. The measurements for R-134a have been carried out along two isotherms at 323 K and 343 K and at pressures up to 400 kPa for a total of 26 values. For R-32 the measurements were made at 308 K, 323 K, 333 K, and 343 K and at pressures up to 500 kPa for a total of 44 measurements. The experimental uncertainties for R-134a in temperature, pressure, and speed of sound are estimated to be not greater than {+-}6 mK, {+-}0.2 kPa, and {+-}0.0061%, respectively. The experimental uncertainties for R-32 in temperature, pressure, and speed of sound are estimated to be not greater than {+-}8 mK, {+-}0.2 kPa, and {+-}0.0061%, respectively. The purities of the R-134a and R-32 samples were better than 99.95% and 99.99% of area percent of the gas chromatography, respectively. The authors have determined the ideal-gas heat capacities and the second acoustic virial coefficients from the speed-of-sound measurements.

    11. Application of Heat Capacity Mapping Mission data to regional geologic analysis for mineral and energy resource evaluation

      NASA Technical Reports Server (NTRS)

      Watson, K. (Principal Investigator); Hummer-Miller, S.; Knepper, D. H., Jr.; Krohn, M. D.; Podwysocki, M. H.; Pohn, H. H.; Raines, G. L.; Rowan, L. C.

      1983-01-01

      Heat Capacity Mapping Mission thermal-inertia images of a diversity of terrains and geologic settings were examined in conjunction with topographic, geologic, geophysical, and LANDSAT data. The images were found to have attributes similar to bedrock maps. In the Cascades region, two new features were identified and a method was developed to characterize regional terranes using linear feature data. Two northeast-trending Lineaments were discovered in the Overthrust Belt of Montana and Idaho. The longer of the two extends from the Idaho-Oregon border, through the Idaho batholith and across the Lewis thrust. It coincides, along segments, with mapped faults and an aeromagnetic pattern change. A major lineament crossing the Colorado Plateau and the Southern Rocky Mountians was detected on several thermal-inertial images and evidence was found for the existence of a geologic discontinuity. Vegetation-covered areas in Richfield and the Silver City quadrangle (Arizona and New Mexico) displayed thermal-inertia differences within heavily vegetation areas although no apreciable correlation was found between vegetation cover and thermal inertia. Resistant ridges and knolls have high thermal inertias and thermal-inertia contrasts occurred at lithologic and fault contacts. In the heavy vegetated Pinaleno Mountains, Arizona, a Lithologic unit obscured on LANDSAT MSS data due to the vegetation cover, exhibited a thermal-inertia contrast with its surroundings.

    12. Probing 2-band superconductivity of Al and C-substituted MgB2 with heat capacity measurements

      NASA Astrophysics Data System (ADS)

      Zambano, Antonio J.

      2005-03-01

      We study the changes in the heat capacity Cp(T) in Mg1-xAlxB2 (x <= 0.19) and Mg(B1-yCy)2 (y <= 0.08). The two band model is used to fit Cp(T) and extract the two energy gaps and electron-phonon coupling matrix for the different dopant concentrations. These fitting routines are sensitive to background subtraction, and we discuss what constraints this places on sample quality and preparation. Like previous results, fits for Al doping do not indicate merging of the gaps, suggesting Al does not increase interband scattering. However, we also notice trends that are different from those seen in previous experiments, which we also discuss. For instance, the main peak due to the sigma band does not smear with increasing Al content, but remains fairly abrupt. Other characterization suggests the Al doped samples are of very high quality. Results for C doping are also discussed in terms of filling the sigma band hole states with electrons and increased interband scattering.

    13. Experimental Results and Modeling of Low-Heat-Capacity TES Microcalorimeters for Soft-X-ray Spectroscopy

      NASA Astrophysics Data System (ADS)

      Eckart, Megan E.; Adams, Joseph S.; Bandler, Simon R.; Brekosky, Regis P.; Chervenak, James A.; Finkbeiner, Fred M.; Kelley, Richard L.; Kilbourne, Caroline A.; Scott Porter, F.; Sadleir, John E.; Smith, Stephen J.

      2009-12-01

      Transition-edge-sensor (TES) X-ray microcalorimeters have mostly been targeted at mid-band energies from 0.05-10 keV and high energies to above 100 keV. However, many other optimizations are possible. Here we present results from devices optimized for soft X-ray applications. For spectroscopy below 1 keV, the X-ray stopping power and heat capacity (C) of the TES itself are high enough that we can omit a separate absorber. The resulting devices have low C and the best-achievable energy resolution should be under 1 eV. We are interested in pursuing such devices primarily for astrophysical applications and laboratory astrophysics at LLNL's Electron-Beam Ion Trap. To this end, we have studied arrays in which `bare' TESs are interspersed with broad-band pixels that have absorbers. By extending the absorbers to cover the area where the leads contact the low-energy pixels, we have eliminated a significant source of non-Gaussian detector response. The bare devices are in a different regime from our typical devices in that C is ten times lower and the conductance to the bath is four times lower. We have explored this regime through simultaneous fitting of noise and impedance data. These data cannot be fit by the simple model we employ to describe our typical broad-band devices. In this contribution we present X-ray spectra and the results from modeling.

    14. Structure and thermal properties of salicylate-based-protic ionic liquids as new heat storage media. COSMO-RS structure characterization and modeling of heat capacities.

      PubMed

      Jacquemin, Johan; Feder-Kubis, Joanna; Zorębski, Michał; Grzybowska, Katarzyna; Chorążewski, Mirosław; Hensel-Bielówka, Stella; Zorębski, Edward; Paluch, Marian; Dzida, Marzena

      2014-02-28

      During this research, we present a study on the thermal properties, such as the melting, cold crystallization, and glass transition temperatures as well as heat capacities from 293.15 K to 323.15 K of nine in-house synthesized protic ionic liquids based on the 3-(alkoxymethyl)-1H-imidazol-3-ium salicylate ([H-Im-C1OC(n)][Sal]) with n = 3-11. The 3D structures, surface charge distributions and COSMO volumes of all investigated ions are obtained by combining DFT calculations and the COSMO-RS methodology. The heat capacity data sets as a function of temperature of the 3-(alkoxymethyl)-1H-imidazol-3-ium salicylate are then predicted using the methodology originally proposed in the case of ionic liquids by Ge et al. 3-(Alkoxymethyl)-1H-imidazol-3-ium salicylate based ionic liquids present specific heat capacities higher in many cases than other ionic liquids that make them suitable as heat storage media and in heat transfer processes. It was found experimentally that the heat capacity increases linearly with increasing alkyl chain length of the alkoxymethyl group of 3-(alkoxymethyl)-1H-imidazol-3-ium salicylate as was expected and predicted using the Ge et al. method with an overall relative absolute deviation close to 3.2% for temperatures up to 323.15 K. PMID:24413748

    15. Determination of the magnetic contribution to the heat capacity of cobalt oxide nanoparticles and the thermodynamic properties of the hydration layers

      SciTech Connect

      Spencer, Elinor; Ross, Dr. Nancy; Parker, Stewart F.; Woodfield, Brian; Boerio-Goates, Juliana; Smith, S. J.; Olsen, R. E.; Kolesnikov, Alexander I; Navrotsky, Alexandra; Ma, C

      2011-01-01

      We present low temperature (11 K) inelastic neutron scattering (INS) data on four hydrated nanoparticle systems: 10 nm CoO 0.10H2O (1), 16 nmCo3O4 0.40H2O (2), 25 nm Co3O4 0.30H2O (3) and 40 nmCo3O4 0.026H2O (4). The vibrational densities of states were obtained for all samples and from these the isochoric heat capacity and vibrational energy for the hydration layers confined to the surfaces of these nanoparticle systems have been elucidated. The results show that water on the surface of CoO nanoparticles is more tightly bound than water confined to the surface of Co3O4, and this is reflected in the reduced heat capacity and vibrational entropy for water on CoO relative to water on Co3O4 nanoparticles. This supports the trend, seen previously, for water to be more tightly bound in materials with higher surface energies. The INS spectra for the antiferromagnetic Co3O4 particles (2 4) also show sharp and intense magnetic excitation peaks at 5 meV, and from this the magnetic contribution to the heat capacity of Co3O4 nanoparticles has been calculated; this represents the first example of use of INS data for determining the magnetic contribution to the heat capacity of any magnetic nanoparticle system.

    16. Adiabatic Wankel type rotary engine

      NASA Technical Reports Server (NTRS)

      Kamo, R.; Badgley, P.; Doup, D.

      1988-01-01

      This SBIR Phase program accomplished the objective of advancing the technology of the Wankel type rotary engine for aircraft applications through the use of adiabatic engine technology. Based on the results of this program, technology is in place to provide a rotor and side and intermediate housings with thermal barrier coatings. A detailed cycle analysis of the NASA 1007R Direct Injection Stratified Charge (DISC) rotary engine was performed which concluded that applying thermal barrier coatings to the rotor should be successful and that it was unlikely that the rotor housing could be successfully run with thermal barrier coatings as the thermal stresses were extensive.

    17. Low T heat capacity measurements and new entropy data for titanite (sphene): implications for thermobarometry of high-pressure rocks

      NASA Astrophysics Data System (ADS)

      Manon, M. R. F.; Dachs, E.; Essene, E. J.

      2008-12-01

      The accepted standard state entropy of titanite (sphene) has been questioned in several recent studies, which suggested a revision from the literature value 129.3 ± 0.8 J/mol K to values in the range of 110-120 J/mol K. The heat capacity of titanite was therefore re-measured with a PPMS in the range 5 to 300 K and the standard entropy of titanite was calculated as 127.2 ± 0.2 J/mol K, much closer to the original data than the suggested revisions. Volume parameters for a modified Murgnahan equation of state: V P,T = V 298° × [1 + a°( T - 298) - 20a°( T - 298)] × [1 - 4 P/( K 298 × (1 - 1.5 × 10-4 [ T - 298]) + 4 P)]1/4 were fit to recent unit cell determinations at elevated pressures and temperatures, yielding the constants V 298° = 5.568 J/bar, a° = 3.1 × 10-5 K-1, and K = 1,100 kbar. The standard Gibbs free energy of formation of titanite, -2456.2 kJ/mol (∆ H°f = -2598.4 kJ/mol) was calculated from the new entropy and volume data combined with data from experimental reversals on the reaction, titanite + kyanite = anorthite + rutile. This value is 4-11 kJ/mol less negative than that obtained from experimental determinations of the enthalpy of formation, and it is slightly more negative than values given in internally consistent databases. The displacement of most calculated phase equilibria involving titanite is not large except for reactions with small ∆ S. Re-calculated baric estimates for several metamorphic suites yield pressure differences on the order of 2 kbar in eclogites and 10 kbar for ultra-high pressure titanite-bearing assemblages.

    18. Water activities of NaClO4, Ca(ClO4)2, and Mg(ClO4)2 brines from experimental heat capacities: Water activity >0.6 below 200 K

      NASA Astrophysics Data System (ADS)

      Toner, J. D.; Catling, D. C.

      2016-05-01

      Perchlorate salts found on Mars are extremely hygroscopic and form low eutectic temperature aqueous solutions, which could allow liquid water to exist on Mars despite cold and dry conditions. The formation, dynamics, and potential habitability of perchlorate salt solutions can be broadly understood in terms of water activity. Water activity controls condensation and evaporation of water vapor in brines, deliquescence and efflorescence of crystalline salts, and ice formation during freezing. Furthermore, water activity is a basic parameter defining the habitability of aqueous solutions. Despite the importance of water activity, its value in perchlorate solutions has only been measured at 298.15 K and at the freezing point of water. To address this lack of data, we have determined water activities in NaClO4, Ca(ClO4)2, and Mg(ClO4)2 solutions using experimental heat capacities measured by Differential Scanning Calorimetry. Our results include concentrations up to near-saturation and temperatures ranging from 298.15 to 178 K. We find that water activities in NaClO4 solutions increase with decreasing temperature, by as much as 0.25 aw from 298.15 to 178 K. Consequently, aw reaches ∼0.6-0.7 even for concentrations up to 15 molal NaClO4 below 200 K. In contrast, water activities in Ca(ClO4)2 and Mg(ClO4)2 solutions generally decrease with decreasing temperature. The temperature dependence of water activity indicates that low-temperature NaClO4 solutions will evaporate and deliquesce at higher relative humidity, crystallize ice at higher temperature, and potentially be more habitable for life (at least in terms of water activity) compared to solutions at 298.15 K. The opposite effects occur in Ca(ClO4)2 and Mg(ClO4)2 solutions.

    19. Degenerate adiabatic perturbation theory: Foundations and applications

      NASA Astrophysics Data System (ADS)

      Rigolin, Gustavo; Ortiz, Gerardo

      2014-08-01

      We present details and expand on the framework leading to the recently introduced degenerate adiabatic perturbation theory [Phys. Rev. Lett. 104, 170406 (2010), 10.1103/PhysRevLett.104.170406], and on the formulation of the degenerate adiabatic theorem, along with its necessary and sufficient conditions [given in Phys. Rev. A 85, 062111 (2012), 10.1103/PhysRevA.85.062111]. We start with the adiabatic approximation for degenerate Hamiltonians that paves the way to a clear and rigorous statement of the associated degenerate adiabatic theorem, where the non-Abelian geometric phase (Wilczek-Zee phase) plays a central role to its quantitative formulation. We then describe the degenerate adiabatic perturbation theory, whose zeroth-order term is the degenerate adiabatic approximation, in its full generality. The parameter in the perturbative power-series expansion of the time-dependent wave function is directly associated to the inverse of the time it takes to drive the system from its initial to its final state. With the aid of the degenerate adiabatic perturbation theory we obtain rigorous necessary and sufficient conditions for the validity of the adiabatic theorem of quantum mechanics. Finally, to illustrate the power and wide scope of the methodology, we apply the framework to a degenerate Hamiltonian, whose closed-form time-dependent wave function is derived exactly, and also to other nonexactly solvable Hamiltonians whose solutions are numerically computed.

    20. Shortcut to adiabatic gate teleportation

      NASA Astrophysics Data System (ADS)

      Santos, Alan C.; Silva, Raphael D.; Sarandy, Marcelo S.

      2016-01-01

      We introduce a shortcut to the adiabatic gate teleportation model of quantum computation. More specifically, we determine fast local counterdiabatic Hamiltonians able to implement teleportation as a universal computational primitive. In this scenario, we provide the counterdiabatic driving for arbitrary n -qubit gates, which allows to achieve universality through a variety of gate sets. Remarkably, our approach maps the superadiabatic Hamiltonian HSA for an arbitrary n -qubit gate teleportation into the implementation of a rotated superadiabatic dynamics of an n -qubit state teleportation. This result is rather general, with the speed of the evolution only dictated by the quantum speed limit. In particular, we analyze the energetic cost for different Hamiltonian interpolations in the context of the energy-time complementarity.

    1. Large adiabatic temperature and magnetic entropy changes in EuTi O3

      NASA Astrophysics Data System (ADS)

      Midya, A.; Mandal, P.; Rubi, Km.; Chen, Ruofan; Wang, Jiang-Sheng; Mahendiran, R.; Lorusso, G.; Evangelisti, M.

      2016-03-01

      We have investigated the magnetocaloric effect in single and polycrystalline samples of quantum paraelectric EuTi O3 by magnetization and heat capacity measurements. Single crystalline EuTi O3 shows antiferromagnetic ordering due to E u2 + magnetic moments below TN=5.6 K . This compound shows a giant magnetocaloric effect around its Néel temperature. The isothermal magnetic entropy change is 49 J kg-1K-1 , the adiabatic temperature change is 21 K, and the refrigeration capacity is 500 J kg-1 for a field change of 7 T at TN. The single crystal and polycrystalline samples show similar values of the magnetic entropy and adiabatic temperature changes. The large magnetocaloric effect is due to suppression of the spin entropy associated with the localized 4 f moment of E u2 + ions. The giant magnetocaloric effect, together with negligible hysteresis, suggest that EuTi O3 could be a potential material for magnetic refrigeration below 40 K.

    2. Quantum gates with controlled adiabatic evolutions

      NASA Astrophysics Data System (ADS)

      Hen, Itay

      2015-02-01

      We introduce a class of quantum adiabatic evolutions that we claim may be interpreted as the equivalents of the unitary gates of the quantum gate model. We argue that these gates form a universal set and may therefore be used as building blocks in the construction of arbitrary "adiabatic circuits," analogously to the manner in which gates are used in the circuit model. One implication of the above construction is that arbitrary classical boolean circuits as well as gate model circuits may be directly translated to adiabatic algorithms with no additional resources or complexities. We show that while these adiabatic algorithms fail to exhibit certain aspects of the inherent fault tolerance of traditional quantum adiabatic algorithms, they may have certain other experimental advantages acting as quantum gates.

    3. On a Nonlinear Model in Adiabatic Evolutions

      NASA Astrophysics Data System (ADS)

      Sun, Jie; Lu, Song-Feng

      2016-08-01

      In this paper, we study a kind of nonlinear model of adiabatic evolution in quantum search problem. As will be seen here, for this problem, there always exists a possibility that this nonlinear model can successfully solve the problem, while the linear model can not. Also in the same setting, when the overlap between the initial state and the final stare is sufficiently large, a simple linear adiabatic evolution can achieve O(1) time efficiency, but infinite time complexity for the nonlinear model of adiabatic evolution is needed. This tells us, it is not always a wise choice to use nonlinear interpolations in adiabatic algorithms. Sometimes, simple linear adiabatic evolutions may be sufficient for using. Supported by the National Natural Science Foundation of China under Grant Nos. 61402188 and 61173050. The first author also gratefully acknowledges the support from the China Postdoctoral Science Foundation under Grant No. 2014M552041

    4. A conceptual approach for noncontact calorimetry in space

      NASA Technical Reports Server (NTRS)

      Fecht, H. J.; Johnson, W. L.

      1991-01-01

      A concept is developed and described which allows to measure the heat capacity and the effective thermal conductivity of stable and undercooled liquid metals and alloys in an electromagnetic levitation apparatus. A proposal is made to use an ac pulse heating method which is used nowadays as a standard technique for precision measurement of low-temperature heat capacities. The ideal process parameters, including the drop diameter D, temperature T, and frequency of measurement omega, can be optimized when the following relations hold for the external and internal relaxation time constants tau-1 and tau-2, respectively: omega(tau-1) greater than 10 and omega(tau-2) less than 0.1. Then, heat capacity data can be obtained with an accuracy of better than 1 percent with D about 5 to 10 mm, T between 1200 and 1800 K, and omega between 0.1 and 1 Hz for typical metals and alloys.

    5. A conceptual approach for noncontact calorimetry in space

      NASA Astrophysics Data System (ADS)

      Fecht, H. J.; Johnson, W. L.

      1991-05-01

      A concept is developed and described which allows to measure the heat capacity and the effective thermal conductivity of stable and undercooled liquid metals and alloys in an electromagnetic levitation apparatus. A proposal is made to use an ac pulse heating method which is used nowadays as a standard technique for precision measurement of low-temperature heat capacities. The ideal process parameters, including the drop diameter D, temperature T, and frequency of measurement omega, can be optimized when the following relations hold for the external and internal relaxation time constants tau-1 and tau-2, respectively: omega(tau-1) greater than 10 and omega(tau-2) less than 0.1. Then, heat capacity data can be obtained with an accuracy of better than 1 percent with D about 5 to 10 mm, T between 1200 and 1800 K, and omega between 0.1 and 1 Hz for typical metals and alloys.

    6. On the low-temperature behavior of the critical specific heat capacity of an anharmonic crystal with long-range interaction

      NASA Astrophysics Data System (ADS)

      Pisanova, Ekaterina S.; Krushkov, Angel Y.

      2016-03-01

      An exactly solvable lattice model describing structural phase transitions in an anharmonic crystal with long-range interaction (decreasing at large distances r as r-d-σ, where d is the space dimensionality and 0 < σ ≤ 2) is considered near to its zero-temperature critical point. The low-temperature behavior of the bulk specific heat capacity at the lower classical critical dimension (d = σ) is studied in different regions of the (T, λ)-phase diagram, where T is the temperature and λ is a parameter which switches on quantum fluctuations. From the results obtained one can see that when T → 0+ the specific heat capacity tends to zero in a different way in the regions: (a) renormalized classical region - as T raised to the second power and (b) quantum disordered region - exponentially.

    7. Debye’s temperature and heat capacity for Sr0.15Ba0.85Bi2Nb2O9 relaxor ferroelectric ceramic

      NASA Astrophysics Data System (ADS)

      Peláiz-Barranco, A.; González-Abreu, Y.; Saint-Grégoire, P.; Guerra, J. D. S.; Calderón-Piñar, F.

      2016-02-01

      A lead-free relaxor ferroelectric, Sr0.15Ba0.85Bi2Nb2O9, was synthesized via solid-state reaction and the temperature-dependence of the heat capacity was measured in a wide temperature range. The dielectric permittivity was also measured between 500Hz and 5MHz in the same temperature range. No anomaly has been detected in the heat capacity curve for the whole temperature range covered in the present experiments, while broad peaks have been observed in the dielectric permittivity with high frequency dispersion. A typical relaxor behavior has been observed from the dielectric analysis. The Debye’s temperature has showed a minimum value near the freezing temperature. The results are discussed considering the spin-glass model and the high frequency dispersion, which has been observed for the studied relaxor system.

    8. Temperature and compression effects on electron heat capacity and electron-phonon coupling in aluminum and beryllium: Insights from ab initio simulations

      SciTech Connect

      Li, Zi; Li, Chuanying; Wang, Cong; Zhang, Ping; Kang, Wei

      2015-11-15

      Ultrafast laser experiments on metals usually induce a high electron temperature and a low ion temperature and, thus, an energy relaxation process. The electron heat capacity and electron-phonon coupling factor are crucial thermal quantities to describe this process. We perform ab initio theoretical studies to determine these thermal quantities and their dependence on density and electron temperature for the metals aluminum and beryllium. The heat capacity shows an approximately linear dependence on the temperature, similar to free electron gas, and the compression only slightly affects the capacity. The electron-phonon coupling factor increases with both temperature and density, and the change observed for beryllium is more obvious than that for aluminum. The connections between thermal quantities and electronic/atomic structures are discussed in detail, and the different behaviors of aluminum and beryllium are well explained.

    9. HTFLO: a computer model of a resistively-heated UO/sub 2/ pin with a rate-dependent heat capacity. [LMFBR

      SciTech Connect

      Smaardyk, J.E.

      1980-02-01

      A one-dimensional model is presented to describe the thermal behavior of an uranium dioxide (UO/sub 2/) rod that is heated resistively and cooled by surface radiation. A standard forward differencing scheme is used for the heat transfer calculations. Temperature-dependent electrical and thermal properties are calculated at the beginning of each time step. In addition, the heat capacity is calculated from a dynamic enthalpy model based on equilibrium and instantaneous heat capacity models with a user-selectable relaxation time. This report describes the finite difference equations used, the treatment of the source and boundary terms, and the dynamic enthalpy model. Detailed input instructions are provided and a sample calculation is shown.

    10. Temperature and compression effects on electron heat capacity and electron-phonon coupling in aluminum and beryllium: Insights from ab initio simulations

      NASA Astrophysics Data System (ADS)

      Li, Zi; Wang, Cong; Kang, Wei; Li, Chuanying; Zhang, Ping

      2015-11-01

      Ultrafast laser experiments on metals usually induce a high electron temperature and a low ion temperature and, thus, an energy relaxation process. The electron heat capacity and electron-phonon coupling factor are crucial thermal quantities to describe this process. We perform ab initio theoretical studies to determine these thermal quantities and their dependence on density and electron temperature for the metals aluminum and beryllium. The heat capacity shows an approximately linear dependence on the temperature, similar to free electron gas, and the compression only slightly affects the capacity. The electron-phonon coupling factor increases with both temperature and density, and the change observed for beryllium is more obvious than that for aluminum. The connections between thermal quantities and electronic/atomic structures are discussed in detail, and the different behaviors of aluminum and beryllium are well explained.

    11. Systematic studies on anharmonicity of rattling phonons in type-I clathrates by low-temperature heat capacity measurements

      NASA Astrophysics Data System (ADS)

      Wu, Jiazhen; Xu, Jingtao; Prananto, Dwi; Shimotani, Hidekazu; Tanabe, Yoichi; Heguri, Satoshi; Tanigaki, Katsumi

      2014-06-01

      A systematic study on the anharmonicity of phonons is made for single-crystal type-I clathrates: n-type Ba8Ga16Ge30 (n-BGG), p-type Ba8Ga16Ge30 (p-BGG), n-type Sr8Ga16Ge30 (n-SGG), n-type K8Ga16Sn30 (n-KGSn), and n-type Ba8Ga16Sn30 (n-BGSn), based on their heat capacity Cp at low temperatures (T) down to 360 mK. The low-T linear terms obsγT of Cp, including the tunneling term of the atoms accommodated in the host cages (γphT =αT) and the Sommerfeld itinerant-electron term (γeT), are successfully separated through careful measurements of single crystals with various carrier concentrations. The values of the minimum density of anharmonic potentials are deduced from α to be 0.12±0.24 for n-KGSn, 0.47±0.24 for n-BGG, 1.9±0.8 for p-BGG, 6.0±0.9 for n-SGG, and 10.9±0.7 for n-BGSn in units of ×1015 cm-3. The effective mass (m*/m0) is determined from γe to be 1.01±0.25 for n-BGG, 1.20±0.19 for p-BGG, 1.68±0.24 for n-SGG, 1.86±0.54 for n-KGSn, and 2.05±0.48 for n-BGSn in units of free electron mass m0, and the electron-phonon interaction strength can be evaluated from these values. It is shown that both the thermal conductivity (κ) and the electron-phonon interaction strength (λ) agree well with the α parameters deduced from Cp. The differences in κ known between n- and p-BGGs are ascribed to the influence of defects at the crystallographic 6c sites, which are clearly indicated by magnetic susceptibility measurements. This is very different from the situation in the other clathrates.

    12. Rotational tunneling of methyl groups and the electronic heat capacity of EtMe3Sb[Pd(dmit)2]2 under magnetic fields

      NASA Astrophysics Data System (ADS)

      Yamashita, Satoshi; Yoshizumi, Masayuki; Akutsu, Hiroki; Nakazawa, Yasuhiro

      2016-03-01

      In order to discuss the stability of the gapless features in the spin liquid state against magnetic fields, we report results and analyses of low-temperature heat capacity measurements of EtMe3Sb[Pd(dmit)2]2 under magnetic fields. The large upturn of CpT‑1 at 0 T observed previously in EtMe3Sb[Pd(dmit)2]2 can be attributed to the rotational tunneling of the methyl groups in the counter cations and this upturn is suppressed by applying magnetic fields. The phenomenological resemblance of the feature under magnetic field was confirmed by comparative discussion of heat capacity measurement of metal complex of [Cu(acac)(OCH3)]2 having similar methyl groups. The gapless character evidenced by the finite electronic heat capacity coefficient, γ was found to be retained upon applying 17 T in EtMe3Sb[Pd(dmit)2]2, which means that spin liquid ground state is stable against high magnetic fields. The finite γ in the spin liquid compounds is considered to be related to a kind of density of states in spin excitations rather than those determined by disorders such as spin glasses.

    13. Temperature dependent electron-phonon coupling and heat capacity in thin slabs of topological insulator Bi2Te3 as pertinent to the thermal spike model

      NASA Astrophysics Data System (ADS)

      Patra, Paramita; Srivastava, S. K.

      2016-07-01

      Electron-phonon coupling strength and electronic heat capacity are essential ingredients of the widely accepted thermal spike model of swift heavy ion matter interaction. The concept, although applicable very well in metals, loses its validity in materials with a band gap, wherein it is customary to take the two quantities merely as adjustable parameters to fit the experimental results. Topological insulators, like Bi2Te3, are quite interesting in this regard because they are also metallic albeit near the surface. In this work, we compute by first-principles the electron density of states of ∼16 Å thick Bi2Te3 slabs of different orientations and demonstrate an unusually high metallicity for the [0 0 1] slab. The density of states is then used to calculate the electron-phonon coupling strength and electronic heat capacity as a function of electron temperature. Strongly electron temperature dependent but weak electron-phonon coupling has been observed, along with systematic deviations of the electronic heat capacity from the linear free-electron metal values.

    14. The Numerical Comparison of Magnetic Susceptibility and Heat Capacity of TMNIN with the Result of a Quantum Monte Carlo Method for the Haldane System

      NASA Astrophysics Data System (ADS)

      Ito, Masakazu; Mito, Masaki; Deguchi, Hiroyuki; Takeda, Kazuyoshi

      1994-03-01

      The measurements of magnetic heat capacity and susceptibility of one-dimensional S=1 antiferromagnet (CH3)4NNi(NO2)3 (TMNIN) have been carried out in order to make comparison with the theoretical results of a quantum Monte Carlo method for the Haldane system. The results for the heat capacity, which show a broad maximum around 10 K, are well reproduced by the theory with the interaction J/k B=-12.0±1.0 K in the temperature range T>0.2\\mid J\\mid S(S+1)/k_B. The low temperature heat capacity exhibits an exponential decay with gap energy Δ/k B=5.3±0.2 K, which gives {\\mitΔ}=0.44\\mid J\\mid , in contrast to the linear dependence on temperature as in the case for half integer spin. The residual magnetic entropy below 0.7 K is estimated to be 0.07% of Nk B ln 3, which denies the possibility of three-dimensional ordering of the spin system at lower temperatures. The observed susceptibility also agrees with the theory with J/k B=-10.9 K and g=2.02 in the whole temperature region, when we take the effect from the finite length of the chains into consideration.

    15. Mössbauer spectroscopy, magnetization, magnetic susceptibility, and low temperature heat capacity of α-Na2NpO4

      NASA Astrophysics Data System (ADS)

      Smith, Anna L.; Hen, Amir; Magnani, Nicola; Sanchez, Jean-Pierre; Colineau, Eric; Griveau, Jean-Christophe; Raison, Philippe E.; Caciuffo, Roberto; Konings, Rudy J. M.; Cheetham, Anthony K.

      2016-03-01

      The physical and chemical properties at low temperatures of hexavalent disodium neptunate α-Na2NpO4 are investigated for the first time in this work using Mössbauer spectroscopy, magnetization, magnetic susceptibility, and heat capacity measurements. The Np(VI) valence state is confirmed by the isomer shift value of the Mössbauer spectra, and the local structural environment around the neptunium cation is related to the fitted quadrupole coupling constant and asymmetry parameters. Moreover, magnetic hyperfine splitting is reported below 12.5 K, which could indicate magnetic ordering at this temperature. This interpretation is further substantiated by the existence of a λ-peak at 12.5 K in the heat capacity curve, which is shifted to lower temperatures with the application of a magnetic field, suggesting antiferromagnetic ordering. However, the absence of any anomaly in the magnetization and magnetic susceptibility data shows that the observed transition is more intricate. In addition, the heat capacity measurements suggest the existence of a Schottky-type anomaly above 15 K associated with a low-lying electronic doublet found about 60 cm-1 above the ground state doublet. The possibility of a quadrupolar transition associated with a ground state pseudoquartet is thereafter discussed. The present results finally bring new insights into the complex magnetic and electronic peculiarities of α-Na2NpO4.

    16. Heating and cooling in adiabatic mixing process

      NASA Astrophysics Data System (ADS)

      Zhou, Jing; Cai, Zi; Zou, Xu-Bo; Guo, Guang-Can

      2010-12-01

      We study the effect of interaction on the temperature change in the process of adiabatic mixing of two components of Fermi gases using the real-space Bogoliubov-de Gennes method. We find that in the process of adiabatic mixing, the competition between the adiabatic expansion and the attractive interaction makes it possible to cool or heat the system depending on the strength of the interaction and the initial temperature of the system. The changes of the temperature in a bulk system and in a trapped system are investigated.

    17. Calorimetry of the CMD-3 detector

      NASA Astrophysics Data System (ADS)

      Shebalin, V. E.; Akhmetshin, R. R.; Anisenkov, A. V.; Aulchenko, V. M.; Bashtovoy, N. S.; Epifanov, D. A.; Epshteyn, L. B.; Erofeev, A. L.; Grebenuk, A. A.; Grigoriev, D. N.; Ignatov, F. V.; Kazanin, V. F.; Kovalenko, O. A.; Kozyrev, A. N.; Kuzmenko, A. E.; Kuzmin, A. S.; Logashenko, I. B.; Mikhailov, K. Yu.; Okhapkin, V. S.; Razuvaev, G. P.; Ruban, A. A.; Shwartz, B. A.; Titov, V. M.; Talyshev, A. A.; Yudin, Yu. V.

      2016-07-01

      CMD-3 is a general purpose detector designed to study e+e- annihilation into hadrons. It is mounted at VEPP-2000 collider which operates in the wide energy range, E c . m . s = 0.32 - 2 GeV. The calorimetry at the detector is based on three subsystems: closest to the beam pipe barrel Liquid Xenon calorimeter, outer barrel calorimeter based on CsI scintillation crystals and the endcap calorimeter made of BGO scintillation crystals. We describe the structure of the calorimeters, their electronics and the energy calibration procedures.

    18. Multisurface Adiabatic Reactive Molecular Dynamics.

      PubMed

      Nagy, Tibor; Yosa Reyes, Juvenal; Meuwly, Markus

      2014-04-01

      Adiabatic reactive molecular dynamics (ARMD) simulation method is a surface-crossing algorithm for modeling chemical reactions in classical molecular dynamics simulations using empirical force fields. As the ARMD Hamiltonian is time dependent during crossing, it allows only approximate energy conservation. In the current work, the range of applicability of conventional ARMD is explored, and a new multisurface ARMD (MS-ARMD) method is presented, implemented in CHARMM and applied to the vibrationally induced photodissociation of sulfuric acid (H2SO4) in the gas phase. For this, an accurate global potential energy surface (PES) involving 12 H2SO4 and 4 H2O + SO3 force fields fitted to MP2/6-311G++(2d,2p) reference energies is employed. The MS-ARMD simulations conserve total energy and feature both intramolecular H-transfer reactions and water elimination. An analytical treatment of the dynamics in the crossing region finds that conventional ARMD can approximately conserve total energy for limiting cases. In one of them, the reduced mass of the system is large, which often occurs for simulations of solvated biomolecular systems. On the other hand, MS-ARMD is a general approach for modeling chemical reactions including gas-phase, homogeneous, heterogeneous, and enzymatic catalytic reactions while conserving total energy in atomistic simulations. PMID:26580356

    19. Anharmonic phonon quasiparticle theory of zero-point and thermal shifts in insulators: Heat capacity, bulk modulus, and thermal expansion

      NASA Astrophysics Data System (ADS)

      Allen, Philip B.

      2015-08-01

      The quasiharmonic (QH) approximation uses harmonic vibrational frequencies ωQ ,H(V ) computed at volumes V near V0 where the Born-Oppenheimer (BO) energy Eel(V ) is minimum. When this is used in the harmonic free energy, QH approximation gives a good zeroth order theory of thermal expansion and first-order theory of bulk modulus, where nth-order means smaller than the leading term by ɛn, where ɛ =ℏ ωvib/Eel or kBT /Eel , and Eel is an electronic energy scale, typically 2 to 10 eV. Experiment often shows evidence for next-order corrections. When such corrections are needed, anharmonic interactions must be included. The most accessible measure of anharmonicity is the quasiparticle (QP) energy ωQ(V ,T ) seen experimentally by vibrational spectroscopy. However, this cannot just be inserted into the harmonic free energy FH. In this paper, a free energy is found that corrects the double-counting of anharmonic interactions that is made when F is approximated by FH( ωQ(V ,T ) ) . The term "QP thermodynamics" is used for this way of treating anharmonicity. It enables (n +1 ) -order corrections if QH theory is accurate to order n . This procedure is used to give corrections to the specific heat and volume thermal expansion. The QH formulas for isothermal (BT) and adiabatic (BS) bulk moduli are clarified, and the route to higher-order corrections is indicated.

    20. Energetics of anhydrite, barite, celestine, and anglesite: a high-temperature and differential scanning calorimetry study

      NASA Astrophysics Data System (ADS)

      Majzlan, J.; Navrotsky, A.; Neil, J. M.

      2002-05-01

      The thermochemistry of anhydrous sulfates (anglesite, anhydrite, arcanite, barite, celestine) was investigated by high-temperature oxide melt calorimetry and differential scanning calorimetry. Complete retention and uniform speciation of sulfur in the solvent was documented by (a) chemical analyses of the solvent (3Na 2O · 4MoO 3) with dissolved sulfates, (b) Fourier transform infrared spectroscopy confirming the absence of sulfur species in the gases above the solvent, and (c) consistency of experimental determination of the enthalpy of drop solution of SO 3 in the solvent. Thus, the principal conclusion of this study is that high-temperature oxide melt calorimetry with 3Na 2O · 4MoO 3 solvent is a valid technique for measurement of enthalpies of formation of anhydrous sulfates. Enthalpies of formation (in kJ/mol) from the elements (ΔH fo) were determined for synthetic anhydrite (CaSO 4) (-1433.8 ± 3.2), celestine (SrSO 4) (-1452.1 ± 3.3), anglesite (PbSO 4) (-909.9 ± 3.4), and two natural barite (BaSO 4) samples (-1464.2 ± 3.7, -1464.9 ± 3.7). The heat capacity of anhydrite, barite, and celestine was measured between 245 and 1100 K, with low- and high-temperature Netzsch (DSC-404) differential scanning calorimeters. The results for each sample were fitted to a Haas-Fisher polynomial of the form C p(245 K < T < 1100 K) = a + bT + cT -2 + dT -0.5 + eT 2. The coefficients of the equation are as follows: for anhydrite a = 409.7, b = -1.764 × 10 -1, c = 2.672 × 10 6, d = -5.130 × 10 3, e = 8.460 × 10 -5; for barite, a = 230.5, b = -0.7395 × 10 -1, c = -1.170 × 10 6, d = -1.587 × 10 3, e = 4.784 × 10 -5; and for celestine, a = 82.1, b = 0.8831 × 10 -1, c = -1.213 × 10 6, d = 0.1890 × 10 3, e = -1.449 × 10 -5. The 95% confidence interval of the measured C p varies from 1 to 2% of the measured value at low temperature up to 2 to 5% at high temperature. The measured thermochemical data improve or augment the thermodynamic database for anhydrous

    1. Calorimetry exchange program. Annual report, 1988

      SciTech Connect

      Lyons, J.E.

      1988-12-31

      The goals of the Calorimetry Sample Program are: 1. Discuss measurement differences, 2. Review and improve analytical measurements and methods, 3. Discuss new measurement capabilities, 4. Provide data to DOE on measurement capabilities to evaluate shipper- receiver differences, 5. Provide characterized or standard materials as necessary for exchange participants, 6. Provide a measurement control program for plutonium analysis. A sample of PuO{sub 2} powder is available at each participating site for NDA measurement, including either or both calorimetry and high-resolution gamma-ray spectroscopy, the elements which are typically combined to provide a calorimetric assay of plutonium. The facilities measure the sample as frequently and to the level of precision which they desire, and then submit the data to the Exchange for analysis. Statistical tests are used to evaluate the data and to determine if there are significant differences from accepted values for the exchange or from data previously reported by that facility. Data included in this report is a compilation of all exchange data received in 1988. Since a large number of data points were recorded, a change was made to the analysis method to account for the uncertainty in the accepted values.

    2. Electronics for calorimetry: An overview of requirements

      SciTech Connect

      Radeka, V.

      1995-10-01

      Calorimetry in large detectors at LHC poses some requirements on readout electronics which are quite different than for central tracking and muon tracking. The main distinction is, (a) in the large dynamic range of the energies to be measured; and (b) uniformity of response and accuracy of calibration over the whole detector. As in all other functions of the detector, low noise is essential. High luminosity results in pileup effects, which are present in every measurement, and in high radiation for front and forward parts of the calorimeter. Power dissipation and cooling is a concern as in any other detector component, in some respects only more so, since all the elements of the signal processing chain require more power due to the large dynamic range, speed of response, high precision and low noise required. The key requirements on the calorimetry readout electronics are briefly discussed here, with an emphasis on the dynamic range. While there are quite significant differences in the principles and technology among the crystals, tiles with fibers and liquid ionization, the signal is finally reduced to a charge measurement from a capacitive source in all three cases, and the signal processing chain becomes remarkably identical.

    3. Adiabatic limits on Riemannian Heisenberg manifolds

      SciTech Connect

      Yakovlev, A A

      2008-02-28

      An asymptotic formula is obtained for the distribution function of the spectrum of the Laplace operator, in the adiabatic limit for the foliation defined by the orbits of an invariant flow on a compact Riemannian Heisenberg manifold. Bibliography: 21 titles.

    4. Experimental demonstration of composite adiabatic passage

      NASA Astrophysics Data System (ADS)

      Schraft, Daniel; Halfmann, Thomas; Genov, Genko T.; Vitanov, Nikolay V.

      2013-12-01

      We report an experimental demonstration of composite adiabatic passage (CAP) for robust and efficient manipulation of two-level systems. The technique represents a altered version of rapid adiabatic passage (RAP), driven by composite sequences of radiation pulses with appropriately chosen phases. We implement CAP with radio-frequency pulses to invert (i.e., to rephase) optically prepared spin coherences in a Pr3+:Y2SiO5 crystal. We perform systematic investigations of the efficiency of CAP and compare the results with conventional π pulses and RAP. The data clearly demonstrate the superior features of CAP with regard to robustness and efficiency, even under conditions of weakly fulfilled adiabaticity. The experimental demonstration of composite sequences to support adiabatic passage is of significant relevance whenever a high efficiency or robustness of coherent excitation processes need to be maintained, e.g., as required in quantum information technology.

    5. An Adiabatic Architecture for Linear Signal Processing

      NASA Astrophysics Data System (ADS)

      Vollmer, M.; Götze, J.

      2005-05-01

      Using adiabatic CMOS logic instead of the more traditional static CMOS logic can lower the power consumption of a hardware design. However, the characteristic differences between adiabatic and static logic, such as a four-phase clock, have a far reaching influence on the design itself. These influences are investigated in this paper by adapting a systolic array of CORDIC devices to be implemented adiabatically. We present a means to describe adiabatic logic in VHDL and use it to define the systolic array with precise timing and bit-true calculations. The large pipeline bubbles that occur in a naive version of this array are identified and removed to a large degree. As an example, we demonstrate a parameterization of the CORDIC array that carries out adaptive RLS filtering.

    6. General conditions for quantum adiabatic evolution

      SciTech Connect

      Comparat, Daniel

      2009-07-15

      Adiabaticity occurs when, during its evolution, a physical system remains in the instantaneous eigenstate of the Hamiltonian. Unfortunately, existing results, such as the quantum adiabatic theorem based on a slow down evolution [H({epsilon}t),{epsilon}{yields}0], are insufficient to describe an evolution driven by the Hamiltonian H(t) itself. Here we derive general criteria and exact bounds, for the state and its phase, ensuring an adiabatic evolution for any Hamiltonian H(t). As a corollary, we demonstrate that the commonly used condition of a slow Hamiltonian variation rate, compared to the spectral gap, is indeed sufficient to ensure adiabaticity but only when the Hamiltonian is real and nonoscillating (for instance, containing exponential or polynomial but no sinusoidal functions)

    7. Adiabatic invariance of oscillons/I -balls

      NASA Astrophysics Data System (ADS)

      Kawasaki, Masahiro; Takahashi, Fuminobu; Takeda, Naoyuki

      2015-11-01

      Real scalar fields are known to fragment into spatially localized and long-lived solitons called oscillons or I -balls. We prove the adiabatic invariance of the oscillons/I -balls for a potential that allows periodic motion even in the presence of non-negligible spatial gradient energy. We show that such a potential is uniquely determined to be the quadratic one with a logarithmic correction, for which the oscillons/I -balls are absolutely stable. For slightly different forms of the scalar potential dominated by the quadratic one, the oscillons/I -balls are only quasistable, because the adiabatic charge is only approximately conserved. We check the conservation of the adiabatic charge of the I -balls in numerical simulation by slowly varying the coefficient of logarithmic corrections. This unambiguously shows that the longevity of oscillons/I -balls is due to the adiabatic invariance.

    8. Symmetry of the Adiabatic Condition in the Piston Problem

      ERIC Educational Resources Information Center

      Anacleto, Joaquim; Ferreira, J. M.

      2011-01-01

      This study addresses a controversial issue in the adiabatic piston problem, namely that of the piston being adiabatic when it is fixed but no longer so when it can move freely. It is shown that this apparent contradiction arises from the usual definition of adiabatic condition. The issue is addressed here by requiring the adiabatic condition to be…

    9. Calorimetry for Fast Authentication of Edible Oils

      NASA Astrophysics Data System (ADS)

      Angiuli, Marco; Bussolino, Gian Carlo; Ferrari, Carlo; Matteoli, Enrico; Righetti, Maria Cristina; Salvetti, Giuseppe; Tombari, Elpidio

      2009-06-01

      There are little data in the literature on how to authenticate edible oils through calorimetry techniques. However, oil melting curves can be used to represent correlations between calorimetric results and oil quality. A calorimetric method has been developed for studying the solid-liquid phase transitions of olive oil and seed oils, in which melting peak behavior is correlated to the type, quality, and composition of the oil. Good reproducible thermograms were obtained by defining precise protocols for use in testing, which take into account the specific characteristics of a particular oil. This approach does not replace classical analytical methods; nevertheless, it is believed that calorimetric tests could be a useful preliminary stage for quality testing. The calorimetric technique allows the detection of the adulterant (seed oils or refined olive oil), oil origin, and possible photo-oxidation degradation processes, before more complex and expensive procedures and analyses are applied.

    10. Synergies between electromagnetic calorimetry and PET

      SciTech Connect

      Moses, William W.

      2002-07-30

      The instrumentation used for the nuclear medical imaging technique of Positron Emission Tomography (PET) shares many features with the instrumentation used for electromagnetic calorimetry. Both fields can certainly benefit from technical advances in many common areas, and this paper discusses both the commonalties and the differences between the instrumentation needs for the two fields. The overall aim is to identify where synergistic development opportunities exist. While such opportunities exist in inorganic scintillators, photodetectors, amplification and readout electronics, and high-speed computing, it is important to recognize that while the requirements of the two fields are similar, they are not identical, and so it is unlikely that advances specific to one field can be transferred without modification to the other.

    11. Calorimetry At Very High Energy Colliders

      SciTech Connect

      Chiu, Mickey

      2011-06-01

      The capability of hadron colliders has increased to where it will soon be possible to collide protons at center of mass energies of 14 TeV with the advent of the LHC. With increasing collision energy, calorimeters become ever more essential components of a detector, and collaborations often choose very different technologies to meet their goals. From the perspective of a high energy particle and nuclear physicist, a survey is presented of the differences in design considerations and actual performance of the wide variety of calorimeters used in modern hadron colliders such as the Tevatron, RHIC, and LHC. The lessons learned and some ideas for future development of calorimetry will also be discussed.

    12. Graph isomorphism and adiabatic quantum computing

      NASA Astrophysics Data System (ADS)

      Gaitan, Frank; Clark, Lane

      2014-02-01

      In the graph isomorphism (GI) problem two N-vertex graphs G and G' are given and the task is to determine whether there exists a permutation of the vertices of G that preserves adjacency and transforms G →G'. If yes, then G and G' are said to be isomorphic; otherwise they are nonisomorphic. The GI problem is an important problem in computer science and is thought to be of comparable difficulty to integer factorization. In this paper we present a quantum algorithm that solves arbitrary instances of GI and which also provides an approach to determining all automorphisms of a given graph. We show how the GI problem can be converted to a combinatorial optimization problem that can be solved using adiabatic quantum evolution. We numerically simulate the algorithm's quantum dynamics and show that it correctly (i) distinguishes nonisomorphic graphs; (ii) recognizes isomorphic graphs and determines the permutation(s) that connect them; and (iii) finds the automorphism group of a given graph G. We then discuss the GI quantum algorithm's experimental implementation, and close by showing how it can be leveraged to give a quantum algorithm that solves arbitrary instances of the NP-complete subgraph isomorphism problem. The computational complexity of an adiabatic quantum algorithm is largely determined by the minimum energy gap Δ (N) separating the ground and first-excited states in the limit of large problem size N ≫1. Calculating Δ (N) in this limit is a fundamental open problem in adiabatic quantum computing, and so it is not possible to determine the computational complexity of adiabatic quantum algorithms in general, nor consequently, of the specific adiabatic quantum algorithms presented here. Adiabatic quantum computing has been shown to be equivalent to the circuit model of quantum computing, and so development of adiabatic quantum algorithms continues to be of great interest.

    13. Response to 'Comment on 'Heat capacity, enthalpy fluctuations, and configurational entropy in broken ergodic systems'' [J. Chem. Phys. 134, 147101 (2011)

      SciTech Connect

      Mauro, John C.; Loucks, Roger J.; Sen, Sabyasachi

      2011-04-14

      We show that Johari's critique of our work is based on a misunderstanding of ergodic theory and a disregard for the broken ergodic nature of glass. His analysis is in contradiction with well established experimental results in specific heat spectroscopy, shear-mechanical spectroscopy, and the vanishing of heat capacity in the limit of zero temperature. Based on these misinterpretations, Johari arrives at the erroneous conclusion that the residual entropy of glass is real. However, we show that Johari's result is an artifact in direct contradiction with both rigorous theory and experimental measurements.

    14. Accurate adiabatic correction in the hydrogen molecule

      SciTech Connect

      Pachucki, Krzysztof; Komasa, Jacek

      2014-12-14

      A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10{sup −12} at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H{sub 2}, HD, HT, D{sub 2}, DT, and T{sub 2} has been determined. For the ground state of H{sub 2} the estimated precision is 3 × 10{sup −7} cm{sup −1}, which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels.

    15. Accurate adiabatic correction in the hydrogen molecule

      NASA Astrophysics Data System (ADS)

      Pachucki, Krzysztof; Komasa, Jacek

      2014-12-01

      A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10-12 at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H2, HD, HT, D2, DT, and T2 has been determined. For the ground state of H2 the estimated precision is 3 × 10-7 cm-1, which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels.

    16. Symmetry-Protected Quantum Adiabatic Transistors

      NASA Astrophysics Data System (ADS)

      Williamson, Dominic J.; Bartlett, Stephen D.

      2014-03-01

      An essential development in the history of computing was the invention of the transistor as it allowed logic circuits to be implemented in a robust and modular way. The physical characteristics of semiconductor materials were the key to building these devices. We aim to present an analogous development for quantum computing by showing that quantum adiabatic transistors (as defined by Flammia et al.) are built upon the essential qualities of symmetry-protected (SP) quantum ordered phases in one dimension. Flammia et al. and Renes et al. have demonstrated schemes for universal adiabatic quantum computation using quantum adiabatic transistors described by interacting spin chain models with specifically chosen Hamiltonian terms. We show that these models can be understood as specific examples of the generic situation in which all SP phases lead to quantum computation on encoded edge degrees of freedom by adiabatically traversing a symmetric phase transition into a trivial symmetric phase. This point of view is advantageous as it allows us to readily see that the computational properties of a quantum adiabatic transistor arise from a phase of matter rather than due to carefully tuned interactions.

    17. Low-temperature heat capacities, entropies and enthalpies of Mg2SiO4 polymorphs, and α-β-γ and post-spinel phase relations at high pressure

      NASA Astrophysics Data System (ADS)

      Akaogi, M.; Takayama, H.; Kojitani, H.; Kawaji, H.; Atake, T.

      2007-04-01

      The low-temperature isobaric heat capacities ( C p) of β- and γ-Mg2SiO4 were measured at the range of 1.8 304.7 K with a thermal relaxation method using the Physical Property Measurement System. The obtained standard entropies ( S°298) of β- and γ-Mg2SiO4 are 86.4 ± 0.4 and 82.7 ± 0.5 J/mol K, respectively. Enthalpies of transitions among α-, β- and γ-Mg2SiO4 were measured by high-temperature drop-solution calorimetry with gas-bubbling technique. The enthalpies of the α-β and β-γ transitions at 298 K (Δ H°298) in Mg2SiO4 are 27.2 ± 3.6 and 12.9 ± 3.3 kJ/mol, respectively. Calculated α-β and β-γ transition boundaries were generally consistent with those determined by high-pressure experiments within the errors. Combining the measured Δ H°298 and Δ S°298 with selected data of in situ X-ray diffraction experiments at high pressure, the Δ H°298 and Δ S°298 of the α-β and β-γ transitions were optimized. Calculation using the optimized data tightly constrained the α-β and β-γ transition boundaries in the P, T space. The slope of α-β transition boundary is 3.1 MPa/K at 13.4 GPa and 1,400 K, and that of β-γ boundary 5.2 MPa/K at 18.7 GPa and 1,600 K. The post-spinel transition boundary of γ-Mg2SiO4 to MgSiO3 perovskite plus MgO was also calculated, using the optimized data on γ-Mg2SiO4 and available enthalpy and entropy data on MgSiO3 perovskite and MgO. The calculated post-spinel boundary with a Clapeyron slope of -2.6 ± 0.2 MPa/K is located at pressure consistent with the 660 km discontinuity, considering the error of the thermodynamic data.

    18. A Calorimetric Method for Determination of Heat Capacity of Ceramics for Concentrated Solar Thermal Systems / Skenējošās Kalorimetrijas Metode Siltumietilpības Noteikšanai Saules Kolektoru Keramikā

      NASA Astrophysics Data System (ADS)

      Kalnačs, J.; Grehovs, V.; Mežinskis, G.; Bidermanis, L.

      2013-10-01

      Differential scanning calorimetry was carried out to determine the heat capacity (Cp) of the high temperature resistant ceramic materials to be used as protective coatings for stainless steel tubes of parabolic trough solar collectors in concentrated solar power (CSP) systems. The Ср(Т) measurements and calculations were performed at continuous scanning in the temperature range 20-800 °С. In the work, calibration curves have been derived for conversion of measuring units from mcV into mW. To achieve a better repeatability of measurements, methods for stabilization of the thermal contact between the sample-containing vessel and the probe have been developed. The Ср(Т) dependence was obtained for different ceramic materials. Rakstā izklāstīta izstrādātā metodika keramikas un emalju siltumietilpības noteikšanai pēc diferenciālās skenējošās kalorimetrijas mērījumiem. Parādīta virkne traucējošo faktoru kalibrēšanas līknes un mērījumu veikšanai, piedāvātas metodes to samazināšanai vai novēršanai, precīzāku rezultātu ieguvei. Noteikta siltumietilpības atkarība no temperatūras virknei emalju, kas var tikt izmantotas saules siltuma kolektoros, kā aizsargpārklājumi. Parādīta siltumietilpības noteikšanas atkārtojamības atkarība no siltuma kontakta. Izstrādāta metode termiskā kontakta stabilizācijai. Virknei emalju noteikta siltumietilpības atkarība no temperatūras diapazonā 20 - 800°С.

    19. Differential Scanning Calorimetry Techniques: Applications in Biology and Nanoscience

      PubMed Central

      Gill, Pooria; Moghadam, Tahereh Tohidi; Ranjbar, Bijan

      2010-01-01

      This paper reviews the best-known differential scanning calorimetries (DSCs), such as conventional DSC, microelectromechanical systems-DSC, infrared-heated DSC, modulated-temperature DSC, gas flow-modulated DSC, parallel-nano DSC, pressure perturbation calorimetry, self-reference DSC, and high-performance DSC. Also, we describe here the most extensive applications of DSC in biology and nanoscience. PMID:21119929

    20. Nonadiabatic exchange dynamics during adiabatic frequency sweeps

      NASA Astrophysics Data System (ADS)

      Barbara, Thomas M.

      2016-04-01

      A Bloch equation analysis that includes relaxation and exchange effects during an adiabatic frequency swept pulse is presented. For a large class of sweeps, relaxation can be incorporated using simple first order perturbation theory. For anisochronous exchange, new expressions are derived for exchange augmented rotating frame relaxation. For isochronous exchange between sites with distinct relaxation rate constants outside the extreme narrowing limit, simple criteria for adiabatic exchange are derived and demonstrate that frequency sweeps commonly in use may not be adiabatic with regard to exchange unless the exchange rates are much larger than the relaxation rates. Otherwise, accurate assessment of the sensitivity to exchange dynamics will require numerical integration of the rate equations. Examples of this situation are given for experimentally relevant parameters believed to hold for in-vivo tissue. These results are of significance in the study of exchange induced contrast in magnetic resonance imaging.

    1. Adiabatic approximation for the density matrix

      NASA Astrophysics Data System (ADS)

      Band, Yehuda B.

      1992-05-01

      An adiabatic approximation for the Liouville density-matrix equation which includes decay terms is developed. The adiabatic approximation employs the eigenvectors of the non-normal Liouville operator. The approximation is valid when there exists a complete set of eigenvectors of the non-normal Liouville operator (i.e., the eigenvectors span the density-matrix space), the time rate of change of the Liouville operator is small, and an auxiliary matrix is nonsingular. Numerical examples are presented involving efficient population transfer in a molecule by stimulated Raman scattering, with the intermediate level of the molecule decaying on a time scale that is fast compared with the pulse durations of the pump and Stokes fields. The adiabatic density-matrix approximation can be simply used to determine the density matrix for atomic or molecular systems interacting with cw electromagnetic fields when spontaneous emission or other decay mechanisms prevail.

    2. Extensive Adiabatic Invariants for Nonlinear Chains

      NASA Astrophysics Data System (ADS)

      Giorgilli, Antonio; Paleari, Simone; Penati, Tiziano

      2012-09-01

      We look for extensive adiabatic invariants in nonlinear chains in the thermodynamic limit. Considering the quadratic part of the Klein-Gordon Hamiltonian, by a linear change of variables we transform it into a sum of two parts in involution. At variance with the usual method of introducing normal modes, our constructive procedure allows us to exploit the complete resonance, while keeping the extensive nature of the system. Next we construct a nonlinear approximation of an extensive adiabatic invariant for a perturbation of the discrete nonlinear Schrödinger model. The fluctuations of this quantity are controlled via Gibbs measure estimates independent of the system size, for a large set of initial data at low specific energy. Finally, by numerical calculations we show that our adiabatic invariant is well conserved for times much longer than predicted by our first order theory, with fluctuation much smaller than expected according to standard statistical estimates.

    3. Anderson localization makes adiabatic quantum optimization fail

      PubMed Central

      Altshuler, Boris; Krovi, Hari; Roland, Jérémie

      2010-01-01

      Understanding NP-complete problems is a central topic in computer science (NP stands for nondeterministic polynomial time). This is why adiabatic quantum optimization has attracted so much attention, as it provided a new approach to tackle NP-complete problems using a quantum computer. The efficiency of this approach is limited by small spectral gaps between the ground and excited states of the quantum computer’s Hamiltonian. We show that the statistics of the gaps can be analyzed in a novel way, borrowed from the study of quantum disordered systems in statistical mechanics. It turns out that due to a phenomenon similar to Anderson localization, exponentially small gaps appear close to the end of the adiabatic algorithm for large random instances of NP-complete problems. This implies that unfortunately, adiabatic quantum optimization fails: The system gets trapped in one of the numerous local minima. PMID:20616043

    4. Omnidirectional Measurements of Angle-Resolved Heat Capacity for Complete Detection of Superconducting Gap Structure in the Heavy-Fermion Antiferromagnet UPd2 Al3

      NASA Astrophysics Data System (ADS)

      Shimizu, Yusei; Kittaka, Shunichiro; Sakakibara, Toshiro; Tsutsumi, Yasumasa; Nomoto, Takuya; Ikeda, Hiroaki; Machida, Kazushige; Homma, Yoshiya; Aoki, Dai

      2016-07-01

      Quasiparticle excitations in UPd2 Al3 were studied by means of heat-capacity (C ) measurements under rotating magnetic fields using a high-quality single crystal. The field dependence shows C (H )∝H1 /2-like behavior at low temperatures for both two hexagonal crystal axes, i.e., H ∥[0001 ] (c axis) and H ∥[11 2 ¯0 ] (a axis), suggesting the presence of nodal quasiparticle excitations from heavy bands. At low temperatures, the polar-angle (θ ) dependence of C exhibits a maximum along H ∥[0001 ] with a twofold symmetric oscillation below 0.5 T, and an unusual shoulder or hump anomaly has been found around 30°-60° from the c axis in C (θ ) at intermediate fields (1 ≲μ0H ≲2 T ). These behaviors in UPd2 Al3 purely come from the superconducting nodal quasiparticle excitations, and can be successfully reproduced by theoretical calculations assuming the gap symmetry with a horizontal linear line node. We demonstrate the whole angle-resolved heat-capacity measurements done here as a novel spectroscopic method for nodal gap determination, which can be applied to other exotic superconductors.

    5. Equation of state and ideal-gas heat capacity of a gaseous mixture of 1,1,1,2-tetrafluoroethane, pentafluoroethane, and difluoromethane

      SciTech Connect

      Hurly, J.J.; Schmidt, J.W.; Gillis, K.A.

      1997-05-01

      The authors present the gas-phase equation of state and ideal-gas heat capacity of a ternary mixture of 1,1,1,2-tetrafluoroethane (35%), pentafluoroethane (30%), and difluoromethane (35%) for temperatures between 260 and 453 K and pressures between 0.05 and 7.7 MPa. These results were based on two very different measurement techniques. The first technique measured the gas density of the mixture in a Burnett apparatus from 313 to 453 K and from 0.2 to 7.7 MPa. The second technique deduced the gas density and ideal-gas heat capacity from high-accuracy speed-of-sound measurements in the mixture at temperatures between 260 and 400 K and at pressures between 0.05 and 1.0 MPa. The data from the two techniques were analyzed together to obtain an equation of state that reproduced the densities from the Burnett technique with a fractional RMS deviation of 0.038%, and it also reproduced the sound speeds with a fractional RMS deviation of 0.003%. Finally, the results are compared to a predictive model based on the properties of the pure fluids.

    6. Cu/Nb-Ti MRI wires with improved stability by incorporating filaments of large heat capacity substance PrB6

      NASA Astrophysics Data System (ADS)

      Keilin, V. E.; Kovalev, I. A.; Kruglov, S. L.; Sсherbakov, V. I.; Shutova, D. I.; Vorobjeva, A. E.; Salunin, N. I.; Potanina, L. V.

      2015-03-01

      In this paper we report our recent research on thermal stabilization of low-temperature superconducting magnets by means of large heat capacity substances (LHCS). Two samples (lengths ˜100 m) of NbTi composite wires with additional internal filaments made from intermetallic compound PrB6 (5.9-7.3 vol.%) were produced and tested. The design of the wires was similar to that of the conventional MRI sc wires, except for their smaller diameter (0.835 mm instead of 1.345 mm). Our final goal was the investigation of the possibility to minimize (or even eliminate completely) the necessity of MRI magnets training before their commissioning. The comparative stability measurements showed a twofold increase of the minimum quench energies (MQEs) of the doped wires against short heat disturbances. The magnetic field corresponding to the first flux jump increased by 50%. In MQE tests, the PrB6 heat capacity was fully utilized over the course of a 1 ms heat pulse. In the thermomagnetic stability measurements, the efficiency of LHCS doping was about 75% due to the fast evolution of the flux jumps.

    7. Omnidirectional Measurements of Angle-Resolved Heat Capacity for Complete Detection of Superconducting Gap Structure in the Heavy-Fermion Antiferromagnet UPd_{2}Al_{3}.

      PubMed

      Shimizu, Yusei; Kittaka, Shunichiro; Sakakibara, Toshiro; Tsutsumi, Yasumasa; Nomoto, Takuya; Ikeda, Hiroaki; Machida, Kazushige; Homma, Yoshiya; Aoki, Dai

      2016-07-15

      Quasiparticle excitations in UPd_{2}Al_{3} were studied by means of heat-capacity (C) measurements under rotating magnetic fields using a high-quality single crystal. The field dependence shows C(H)∝H^{1/2}-like behavior at low temperatures for both two hexagonal crystal axes, i.e., H∥[0001] (c axis) and H∥[112[over ¯]0] (a axis), suggesting the presence of nodal quasiparticle excitations from heavy bands. At low temperatures, the polar-angle (θ) dependence of C exhibits a maximum along H∥[0001] with a twofold symmetric oscillation below 0.5 T, and an unusual shoulder or hump anomaly has been found around 30°-60° from the c axis in C(θ) at intermediate fields (1≲μ_{0}H≲2  T). These behaviors in UPd_{2}Al_{3} purely come from the superconducting nodal quasiparticle excitations, and can be successfully reproduced by theoretical calculations assuming the gap symmetry with a horizontal linear line node. We demonstrate the whole angle-resolved heat-capacity measurements done here as a novel spectroscopic method for nodal gap determination, which can be applied to other exotic superconductors. PMID:27472129

    8. Heat capacity of the site-diluted spin dimer system Ba₃(Mn1-xVx)₂O₈

      SciTech Connect

      Samulon, E. C.; Shapiro, M. C.; Fisher, I. R.

      2011-08-05

      Heat-capacity and susceptibility measurements have been performed on the diluted spin dimer compound Ba₃(Mn1-xVx)₂O₈. The parent compound Ba₃Mn₂O₈ is a spin dimer system based on pairs of antiferromagnetically coupled S=1, 3d² Mn⁵⁺ ions such that the zero-field ground state is a product of singlets. Substitution of nonmagnetic S=0, 3d⁰ V⁵⁺ ions leads to an interacting network of unpaired Mn moments, the low-temperature properties of which are explored in the limit of small concentrations 0≤x≤0.05. The zero-field heat capacity of this diluted system reveals a progressive removal of magnetic entropy over an extended range of temperatures, with no evidence for a phase transition. The concentration dependence does not conform to expectations for a spin-glass state. Rather, the data suggest a low-temperature random singlet phase, reflecting the hierarchy of exchange energies found in this system.

    9. Temperature-dependent determination of electron heat capacity and electron-phonon coupling factor for Fe0.72Cr0.18Ni0.1

      NASA Astrophysics Data System (ADS)

      Winter, Jan; Sotrop, Jürgen; Borek, Stephan; Huber, Heinz P.; Minár, Jan

      2016-04-01

      A theoretical approach using ab initio calculations was applied to study the interaction of an ultrashort laser pulse with the metal alloy Fe0.72Cr0.18Ni0.1 (AISI 304). The electronic structure was simulated by taking into account the chemical and magnetic disorder of the alloy by the coherent potential approximation implemented in a fully relativistic Korringa-Kohn-Rostoker formalism in the framework of spin density functional theory. A self-consistent calculation of the electronic structure using the Matsubara technique in the paramagnetic state of Fe0.72Cr0.18Ni0.1 for finite temperatures was applied. Utilizing these predictions we determined the electron heat capacity and the electron-phonon coupling factor of Fe0.72Cr0.18Ni0.1 in dependence on the electron temperature for two-temperature model applications. Compared with pure Fe a maximum deviation of 5% for the electron heat capacity and 25% for the electron-phonon coupling factor was found.

    10. Spontaneous emission in stimulated Raman adiabatic passage

      SciTech Connect

      Ivanov, P. A.; Vitanov, N. V.; Bergmann, K.

      2005-11-15

      This work explores the effect of spontaneous emission on the population transfer efficiency in stimulated Raman adiabatic passage (STIRAP). The approach uses adiabatic elimination of weakly coupled density matrix elements in the Liouville equation, from which a very accurate analytic approximation is derived. The loss of population transfer efficiency is found to decrease exponentially with the factor {omega}{sub 0}{sup 2}/{gamma}, where {gamma} is the spontaneous emission rate and {omega}{sub 0} is the peak Rabi frequency. The transfer efficiency increases with the pulse delay and reaches a steady value. For large pulse delay and large spontaneous emission rate STIRAP degenerates into optical pumping.

    11. Adiabatic Hyperspherical Analysis of Realistic Nuclear Potentials

      NASA Astrophysics Data System (ADS)

      Daily, K. M.; Kievsky, Alejandro; Greene, Chris H.

      2015-12-01

      Using the hyperspherical adiabatic method with the realistic nuclear potentials Argonne V14, Argonne V18, and Argonne V18 with the Urbana IX three-body potential, we calculate the adiabatic potentials and the triton bound state energies. We find that a discrete variable representation with the slow variable discretization method along the hyperradial degree of freedom results in energies consistent with the literature. However, using a Laguerre basis results in missing energy, even when extrapolated to an infinite number of basis functions and channels. We do not include the isospin T = 3/2 contribution in our analysis.

    12. On black hole spectroscopy via adiabatic invariance

      NASA Astrophysics Data System (ADS)

      Jiang, Qing-Quan; Han, Yan

      2012-12-01

      In this Letter, we obtain the black hole spectroscopy by combining the black hole property of adiabaticity and the oscillating velocity of the black hole horizon. This velocity is obtained in the tunneling framework. In particular, we declare, if requiring canonical invariance, the adiabatic invariant quantity should be of the covariant form Iadia = ∮pi dqi. Using it, the horizon area of a Schwarzschild black hole is quantized independently of the choice of coordinates, with an equally spaced spectroscopy always given by ΔA = 8 π lp2 in the Schwarzschild and Painlevé coordinates.

    13. Complexity of the Quantum Adiabatic Algorithm

      NASA Technical Reports Server (NTRS)

      Hen, Itay

      2013-01-01

      The Quantum Adiabatic Algorithm (QAA) has been proposed as a mechanism for efficiently solving optimization problems on a quantum computer. Since adiabatic computation is analog in nature and does not require the design and use of quantum gates, it can be thought of as a simpler and perhaps more profound method for performing quantum computations that might also be easier to implement experimentally. While these features have generated substantial research in QAA, to date there is still a lack of solid evidence that the algorithm can outperform classical optimization algorithms.

    14. Adiabatic approximation for nucleus-nucleus scattering

      SciTech Connect

      Johnson, R.C.

      2005-10-14

      Adiabatic approximations to few-body models of nuclear scattering are described with emphasis on reactions with deuterons and halo nuclei (frozen halo approximation) as projectiles. The different ways the approximation should be implemented in a consistent theory of elastic scattering, stripping and break-up are explained and the conditions for the theory's validity are briefly discussed. A formalism which links few-body models and the underlying many-body system is outlined and the connection between the adiabatic and CDCC methods is reviewed.

    15. Differential scanning calorimetry of plant cell walls

      SciTech Connect

      Lin, Liangshiou; Varner, J.E. ); Yuen, H.K. )

      1991-03-15

      High-sensitivity differential scanning calorimetry has been used to study the phase transition of cell wall preparations of the elongating and mature regions of soybean hypocotyls and of celery epidermis and collenchyma strands. A step-like transition believed to be glass transition was observed in walls isolated from the elongating region of soybean hypocotyls at 52.9C. Addition of 1 mM CaCl{sub 2} to the cell wall preparation increased the transition temperature to 60.8C and greatly reduced the transition magnitude. In walls from the mature region, the transition was small and occurred at a higher temperature (60.1C). Addition of calcium to the mature region cell wall had little effect on the transition. Based on the known interactions between calcium and pectin, the authors propose that calcium affects the glass transition by binding to the polygalacturonate backbone of wall pectin, resulting in a more rigid wall with a smaller transition at a higher temperature. The mature region either has more calcium in the wall or has more methyl-esterified pectin, making it less responsive to added calcium.

    16. Calorimetry using organic scintillators, 'a sideways perspective'.

      SciTech Connect

      Proudfoot, J.

      1999-09-10

      Over the last two decades, calorimetry baaed on organic scintillators has developed into an excellent technology for many experimental situations in high energy physics. The primary difficulty, that of extracting the light signals, has benefited from two milestone innovations. The first was the use of wavelength-shifting bars to allow light to be efficiently collected from large areas of scintillator and then readily piped to a readout device. The second of these was the extension of this approach to plastic wavelength-shifting optical fibers whose great flexibility and small diameter allowed a minimum of detector volume to be compromised by the read-out. These two innovations coupled with inventiveness have produced many varied and successful calorimeters. Equal response to both hadronic and electromagnetic showers can be realized in scintillator-based calorimeters. However, in general this is not the case and it is likely that in the search for greater performance, in the future, combined tracking and calorimeter systems will be required.

    17. Current status of tritium calorimetry at TLK

      SciTech Connect

      Buekki-Deme, A.; Alecu, C.G.; Kloppe, B.; Bornschein, B.

      2015-03-15

      Inside a tritium facility, calorimetry is an important analytical method as it is the only reference method for accountancy (it is based on the measurement of the heat generated by the radioactive decay). Presently, at Tritium Laboratory Karlsruhe (TLK), 4 calorimeters are in operation, one of isothermal type and three of inertial guidance control type (IGC). The volume of the calorimeters varies between 0.5 and 20.6 liters. About two years ago we started an extensive work to improve our calorimeters with regard to reliability and precision. We were forced to upgrade 3 of our 4 calorimeters due to the outdated interfaces and software. This work involved creating new LabView programs driving the devices, re-tuning control loops and replacing obsolete hardware components. In this paper we give a review on the current performance of our calorimeters, comparing it to recently available devices from the market and in the literature. We also show some ideas for a next generation calorimeter based on experiences with our IGC calorimeters and other devices reported in the literature. (authors)

    18. Immersion Calorimetry: Molecular Packing Effects in Micropores.

      PubMed

      Madani, S Hadi; Silvestre-Albero, Ana; Biggs, Mark J; Rodríguez-Reinoso, Francisco; Pendleton, Phillip

      2015-12-21

      Repeated and controlled immersion calorimetry experiments were performed to determine the specific surface area and pore-size distribution (PSD) of a well-characterized, microporous poly(furfuryl alcohol)-based activated carbon. The PSD derived from nitrogen gas adsorption indicated a narrow distribution centered at 0.57±0.05 nm. Immersion into liquids of increasing molecular sizes ranging from 0.33 nm (dichloromethane) to 0.70 nm (α-pinene) showed a decreasing enthalpy of immersion at a critical probe size (0.43-0.48 nm), followed by an increase at 0.48-0.56 nm, and a second decrease at 0.56-0.60 nm. This maximum has not been reported previously. After consideration of possible reasons for this new observation, it is concluded that the effect arises from molecular packing inside the micropores, interpreted in terms of 2D packing. The immersion enthalpy PSD was consistent with that from quenched solid density functional theory (QSDFT) analysis of the nitrogen adsorption isotherm. PMID:26394883

    19. Isothermal titration calorimetry with micelles: Thermodynamics of inhibitor binding to carnitine palmitoyltransferase 2 membrane protein.

      PubMed

      Perspicace, Samantha; Rufer, Arne C; Thoma, Ralf; Mueller, Francis; Hennig, Michael; Ceccarelli, Simona; Schulz-Gasch, Tanja; Seelig, Joachim

      2013-01-01

      Carnitine palmitoyl transferase 2 (CPT-2) is a key enzyme in the mitochondrial fatty acid metabolism. The active site is comprised of a Y-shaped tunnel with distinct binding sites for the substrate acylcarnitine and the cofactor CoA. We investigated the thermodynamics of binding of four inhibitors directed against either the CoA or the acylcarnitine binding sites using isothermal titration calorimetry (ITC). CPT-2 is a monotopic membrane protein and was solubilized by β-octylglucoside (β-OG) above its critical micellar concentration (CMC) to perform inhibitor titrations in solutions containing detergent micelles. The CMC of β-OG in the presence of inhibitors was measured with ITC and small variations were observed. The inhibitors bound to rat CPT-2 (rCPT-2) with 1:1 stoichiometry and the dissociation constants were in the range of K D = 2-20 μM. New X-ray structures and docking models of rCPT-2 in complex with inhibitors enable an analysis of the thermodynamic data in the context of the interaction observed for the individual binding sites of the ligands. For all ligands the binding enthalpy was exothermic, and enthalpy as well as entropy contributed to the binding reaction, with the exception of ST1326 for which binding was solely enthalpy-driven. The substrate analog ST1326 binds to the acylcarnitine binding site and a heat capacity change close to zero suggests a balance of electrostatic and hydrophobic interactions. An excellent correlation of the thermodynamic (ITC) and structural (X-ray crystallography, models) data was observed suggesting that ITC measurements provide valuable information for optimizing inhibitor binding in drug discovery. PMID:23772395

    20. Isothermal titration calorimetry with micelles: Thermodynamics of inhibitor binding to carnitine palmitoyltransferase 2 membrane protein☆

      PubMed Central

      Perspicace, Samantha; Rufer, Arne C.; Thoma, Ralf; Mueller, Francis; Hennig, Michael; Ceccarelli, Simona; Schulz-Gasch, Tanja; Seelig, Joachim

      2013-01-01

      Carnitine palmitoyl transferase 2 (CPT-2) is a key enzyme in the mitochondrial fatty acid metabolism. The active site is comprised of a Y-shaped tunnel with distinct binding sites for the substrate acylcarnitine and the cofactor CoA. We investigated the thermodynamics of binding of four inhibitors directed against either the CoA or the acylcarnitine binding sites using isothermal titration calorimetry (ITC). CPT-2 is a monotopic membrane protein and was solubilized by β-octylglucoside (β-OG) above its critical micellar concentration (CMC) to perform inhibitor titrations in solutions containing detergent micelles. The CMC of β-OG in the presence of inhibitors was measured with ITC and small variations were observed. The inhibitors bound to rat CPT-2 (rCPT-2) with 1:1 stoichiometry and the dissociation constants were in the range of KD = 2–20 μM. New X-ray structures and docking models of rCPT-2 in complex with inhibitors enable an analysis of the thermodynamic data in the context of the interaction observed for the individual binding sites of the ligands. For all ligands the binding enthalpy was exothermic, and enthalpy as well as entropy contributed to the binding reaction, with the exception of ST1326 for which binding was solely enthalpy-driven. The substrate analog ST1326 binds to the acylcarnitine binding site and a heat capacity change close to zero suggests a balance of electrostatic and hydrophobic interactions. An excellent correlation of the thermodynamic (ITC) and structural (X-ray crystallography, models) data was observed suggesting that ITC measurements provide valuable information for optimizing inhibitor binding in drug discovery. PMID:23772395

    1. The Phase Structures of Nylon 6.6 as Studied by Temperature-modulated Calorimetry and Their Link to X-ray Structure and Molecular Motion.

      SciTech Connect

      Qui, Wulin; Habenschuss, Anton {Tony}; Wunderlich, Bernhard {nmn}

      2007-01-01

      The phase behavior of semicrystalline, dry nylon 6.6 is analyzed on the basis of differential scanning calorimetry, DSC, and quasi-isothermal, temperature-modulated DSC, TMDSC. The data were collected over the temperature range from below the glass transitions to above the isotropization. Based on the contributions of the vibrational motion to the heat capacity, as is available from the ATHAS Data Bank, and the multifaceted new calorimetry, as well as on information on X-ray diffraction, molecular dynamics simulation of paraffin crystals, and quasielastic neutron scattering, the following observations are made: (a) beginning at the glass transition temperature of the mobile-amorphous phase (Tg= 323 K), a broadened transition of the semicrystalline sample is observed which reaches to 342 K (Tg = 332.7 K). An additional rigid-amorphous phase, RAF, undergoes its separate, broad glass transition immediately thereafter (340-400 K, Tg {approx} 370 K). (b) The transition of the RAF, in turn, overlaps with increasing large-amplitude motion of the CH2 groups within the crystals and latent heat effects due to melting, recrystallization, and crystal annealing. (c) From 390 to 480 K the heat capacity of the crystals increasingly exceeds that of the melt due to additional entropy (disordering) contributions. Above 440 K, close to the Brill temperature, the heat capacity seems to drop to the level of the melt. (d) If observation (c) is confirmed, some locally reversible melting is present on the crystal surfaces. (e) The increasing large-amplitude motion is described as a glass transition of the crystals, occurring below the melting point, at 409 K. The assumption of a separate glass transition in the ordered phase was previously successful in analyzing aliphatic poly(oxide)s and mesophases. The full description of the globally metastable, semicrystalline phase structure of nylons, thus, needs information on the glass transitions of the two amorphous phases and the ordered phase

    2. Adiabatic Compression in a Fire Syringe.

      ERIC Educational Resources Information Center

      Hayn, Carl H.; Baird, Scott C.

      1985-01-01

      Suggests using better materials in fire syringes to obtain more effective results during demonstrations which show the elevation in temperature upon a very rapid (adiabatic) compression of air. Also describes an experiment (using ignition temperatures) which introduces students to the use of thermocouples for high temperature measurements. (DH)

    3. Apparatus to Measure Adiabatic and Isothermal Processes.

      ERIC Educational Resources Information Center

      Lamb, D. W.; White, G. M.

      1996-01-01

      Describes a simple manual apparatus designed to serve as an effective demonstration of the differences between isothermal and adiabatic processes for the general or elementary physics student. Enables students to verify Boyle's law for slow processes and identify the departure from this law for rapid processes and can also be used to give a clear…

    4. Force Field Benchmark of Organic Liquids: Density, Enthalpy of Vaporization, Heat Capacities, Surface Tension, Isothermal Compressibility, Volumetric Expansion Coefficient, and Dielectric Constant

      PubMed Central

      2011-01-01

      The chemical composition of small organic molecules is often very similar to amino acid side chains or the bases in nucleic acids, and hence there is no a priori reason why a molecular mechanics force field could not describe both organic liquids and biomolecules with a single parameter set. Here, we devise a benchmark for force fields in order to test the ability of existing force fields to reproduce some key properties of organic liquids, namely, the density, enthalpy of vaporization, the surface tension, the heat capacity at constant volume and pressure, the isothermal compressibility, the volumetric expansion coefficient, and the static dielectric constant. Well over 1200 experimental measurements were used for comparison to the simulations of 146 organic liquids. Novel polynomial interpolations of the dielectric constant (32 molecules), heat capacity at constant pressure (three molecules), and the isothermal compressibility (53 molecules) as a function of the temperature have been made, based on experimental data, in order to be able to compare simulation results to them. To compute the heat capacities, we applied the two phase thermodynamics method (Lin et al. J. Chem. Phys.2003, 119, 11792), which allows one to compute thermodynamic properties on the basis of the density of states as derived from the velocity autocorrelation function. The method is implemented in a new utility within the GROMACS molecular simulation package, named g_dos, and a detailed exposé of the underlying equations is presented. The purpose of this work is to establish the state of the art of two popular force fields, OPLS/AA (all-atom optimized potential for liquid simulation) and GAFF (generalized Amber force field), to find common bottlenecks, i.e., particularly difficult molecules, and to serve as a reference point for future force field development. To make for a fair playing field, all molecules were evaluated with the same parameter settings, such as thermostats and barostats

    5. Communication: Adiabatic and non-adiabatic electron-nuclear motion: Quantum and classical dynamics

      NASA Astrophysics Data System (ADS)

      Albert, Julian; Kaiser, Dustin; Engel, Volker

      2016-05-01

      Using a model for coupled electronic-nuclear motion we investigate the range from negligible to strong non-adiabatic coupling. In the adiabatic case, the quantum dynamics proceeds in a single electronic state, whereas for strong coupling a complete transition between two adiabatic electronic states takes place. It is shown that in all coupling regimes the short-time wave-packet dynamics can be described using ensembles of classical trajectories in the phase space spanned by electronic and nuclear degrees of freedom. We thus provide an example which documents that the quantum concept of non-adiabatic transitions is not necessarily needed if electronic and nuclear motion is treated on the same footing.

    6. The dynamic instability of adiabatic blast waves

      NASA Technical Reports Server (NTRS)

      Ryu, Dongsu; Vishniac, Ethan T.

      1991-01-01

      Adiabatic blastwaves, which have a total energy injected from the center E varies as t(sup q) and propagate through a preshock medium with a density rho(sub E) varies as r(sup -omega) are described by a family of similarity solutions. Previous work has shown that adiabatic blastwaves with increasing or constant postshock entropy behind the shock front are susceptible to an oscillatory instability, caused by the difference between the nature of the forces on the two sides of the dense shell behind the shock front. This instability sets in if the dense postshock layer is sufficiently thin. The stability of adiabatic blastwaves with a decreasing postshock entropy is considered. Such blastwaves, if they are decelerating, always have a region behind the shock front which is subject to convection. Some accelerating blastwaves also have such region, depending on the values of q, omega, and gamma where gamma is the adiabatic index. However, since the shock interface stabilizes dynamically induced perturbations, blastwaves become convectively unstable only if the convective zone is localized around the origin or a contact discontinuity far from the shock front. On the other hand, the contact discontinuity of accelerating blastwaves is subject to a strong Rayleigh-Taylor instability. The frequency spectra of the nonradial, normal modes of adiabatic blastwaves have been calculated. The results have been applied to the shocks propagating through supernovae envelopes. It is shown that the metal/He and He/H interfaces are strongly unstable against the Rayleigh-Taylor instability. This instability will induce mixing in supernovae envelopes. In addition the implications of this work for the evolution of planetary nebulae is discussed.

    7. Adiabatic circuits: converter for static CMOS signals

      NASA Astrophysics Data System (ADS)

      Fischer, J.; Amirante, E.; Bargagli-Stoffi, A.; Schmitt-Landsiedel, D.

      2003-05-01

      Ultra low power applications can take great advantages from adiabatic circuitry. In this technique a multiphase system is used which consists ideally of trapezoidal voltage signals. The input signals to be processed will often come from a function block realized in static CMOS. The static rectangular signals must be converted for the oscillating multiphase system of the adiabatic circuitry. This work shows how to convert the input signals to the proposed pulse form which is synchronized to the appropriate supply voltage. By means of adder structures designed for a 0.13µm technology in a 4-phase system there will be demonstrated, which additional circuits are necessary for the conversion. It must be taken into account whether the data arrive in parallel or serial form. Parallel data are all in one phase and therefore it is advantageous to use an adder structure with a proper input stage, e.g. a Carry Lookahead Adder (CLA). With a serial input stage it is possible to read and to process four signals during one cycle due to the adiabatic 4-phase system. Therefore input signals with a frequency four times higher than the adiabatic clock frequency can be used. This reduces the disadvantage of the slow clock period typical for adiabatic circuits. By means of an 8 bit Ripple Carry Adder (8 bit RCA) the serial reading will be introduced. If the word width is larger than 4 bits the word can be divided in 4 bit words which are processed in parallel. This is the most efficient way to minimize the number of input lines and pads. At the same time a high throughput is achieved.

    8. The dynamic instability of adiabatic blast waves

      NASA Astrophysics Data System (ADS)

      Ryu, Dongsu; Vishniac, Ethan T.

      1991-02-01

      Adiabatic blastwaves, which have a total energy injected from the center E varies as tq and propagate through a preshock medium with a density rhoE varies as r-omega are described by a family of similarity solutions. Previous work has shown that adiabatic blastwaves with increasing or constant postshock entropy behind the shock front are susceptible to an oscillatory instability, caused by the difference between the nature of the forces on the two sides of the dense shell behind the shock front. This instability sets in if the dense postshock layer is sufficiently thin. The stability of adiabatic blastwaves with a decreasing postshock entropy is considered. Such blastwaves, if they are decelerating, always have a region behind the shock front which is subject to convection. Some accelerating blastwaves also have such region, depending on the values of q, omega, and gamma where gamma is the adiabatic index. However, since the shock interface stabilizes dynamically induced perturbations, blastwaves become convectively unstable only if the convective zone is localized around the origin or a contact discontinuity far from the shock front. On the other hand, the contact discontinuity of accelerating blastwaves is subject to a strong Rayleigh-Taylor instability. The frequency spectra of the nonradial, normal modes of adiabatic blastwaves have been calculated. The results have been applied to the shocks propagating through supernovae envelopes. It is shown that the metal/He and He/H interfaces are strongly unstable against the Rayleigh-Taylor instability. This instability will induce mixing in supernovae envelopes. In addition the implications of this work for the evolution of planetary nebulae is discussed.

    9. The dynamic instability of adiabatic blastwaves

      NASA Astrophysics Data System (ADS)

      Ryu, Dongsu; Vishniac, Ethan T.

      1990-05-01

      Adiabatic blastwaves, which have a total energy injected from the center E varies as t(sup q) and propagate through a preshock medium with a density rho(sub E) varies as r(sup -omega) are described by a family of similarity solutions. Previous work has shown that adiabatic blastwaves with increasing or constant postshock entropy behind the shock front are susceptible to an oscillatory instability, caused by the difference between the nature of the forces on the two sides of the dense shell behind the shock front. This instability sets in if the dense postshock layer is sufficiently thin. The stability of adiabatic blastwaves with a decreasing postshock entropy is considered. Such blastwaves, if they are decelerating, always have a region behind the shock front which is subject to convection. Some accelerating blastwaves also have such region, depending on the values of q, omega, and gamma where gamma is the adiabatic index. However, since the shock interface stabilizes dynamically induced perturbations, blastwaves become convectively unstable only if the convective zone is localized around the origin or a contact discontinuity far from the shock front. On the other hand, the contact discontinuity of accelerating blastwaves is subject to a strong Rayleigh-Taylor instability. The frequency spectra of the nonradial, normal modes of adiabatic blastwaves have been calculated. The results have been applied to the shocks propagating through supernovae envelopes. It is shown that the metal/He and He/H interfaces are strongly unstable against the Rayleigh-Taylor instability. This instability will induce mixing in supernovae envelopes. In addition the implications of this work for the evolution of planetary nebulae is discussed.

    10. Adiabatic burst evaporation from bicontinuous nanoporous membranes

      PubMed Central

      Ichilmann, Sachar; Rücker, Kerstin; Haase, Markus; Enke, Dirk

      2015-01-01

      Evaporation of volatile liquids from nanoporous media with bicontinuous morphology and pore diameters of a few 10 nm is an ubiquitous process. For example, such drying processes occur during syntheses of nanoporous materials by sol–gel chemistry or by spinodal decomposition in the presence of solvents as well as during solution impregnation of nanoporous hosts with functional guests. It is commonly assumed that drying is endothermic and driven by non-equilibrium partial pressures of the evaporating species in the gas phase. We show that nearly half of the liquid evaporates in an adiabatic mode involving burst-like liquid-to-gas conversions. During single adiabatic burst evaporation events liquid volumes of up to 107 μm3 are converted to gas. The adiabatic liquid-to-gas conversions occur if air invasion fronts get unstable because of the built-up of high capillary pressures. Adiabatic evaporation bursts propagate avalanche-like through the nanopore systems until the air invasion fronts have reached new stable configurations. Adiabatic cavitation bursts thus compete with Haines jumps involving air invasion front relaxation by local liquid flow without enhanced mass transport out of the nanoporous medium and prevail if the mean pore diameter is in the range of a few 10 nm. The results reported here may help optimize membrane preparation via solvent-based approaches, solution-loading of nanopore systems with guest materials as well as routine use of nanoporous membranes with bicontinuous morphology and may contribute to better understanding of adsorption/desorption processes in nanoporous media. PMID:25926406

    11. Adiabatic evolution of an irreversible two level system

      SciTech Connect

      Kvitsinsky, A.; Putterman, S. )

      1991-05-01

      The adiabatic dynamics of a two level atom with spontaneous decay is studied. The existence of a complex adiabatic phase shift is established: The real part being the usual Berry's phase. A closed-form expression for this phase and the adiabatic transition amplitudes is obtained. Incorporation of a finite preparation time for the initial state yields a new asymptotic form for the adiabatic transition amplitudes which is significantly different from the standard Landau--Zener--Dykhne formula.

    12. Heat capacities, magnetic properties, and resistivities of ternary RPdBi alloys where R = La, Nd, Gd, Dy, Er, and Lu

      SciTech Connect

      Riedemann, T.M.

      1996-05-01

      Over the past four and a half decades research on the rare earths, their compounds, and their alloys has yielded significant insights into the nature of materials. The rare earths can be used to systematically study a series of alloys or compounds. Magnetic ordering, crystalline fields, spin fluctuations, the magnetocaloric effect, and magnetostriction are a small sample of phenomena studied that are exhibited by the rare earth family. A significant portion of research has been conducted on the abundant RM{sub 2} and RM phases, where R is the rare earth and M is a transition metal. The natural progression of science has led to the study of related RMX ternary phases, where X is either another transition metal or semimetal. There are now over 1,000 known RMX phases. The focus of this study is on RPdBi where R = La, Nd, Gd, Dy, Er, and Lu. Their heat capacities, magnetic properties, and resistivities are studied.

    13. Magnetic susceptibility and heat-capacity studies of NiS2-xSex single crystals: A study of transitions at nonzero temperature

      NASA Astrophysics Data System (ADS)

      Yao, X.; Kuo, Y.-K.; Powell, D. K.; Brill, J. W.; Honig, J. M.

      1997-09-01

      Heat-capacity and magnetic-susceptibility studies have been carried out on NiS2-xSex single crystals for 0.38<=x<=0.58 and 0<=x<=0.71, respectively. These and earlier physical measurements document the gradual evolution, with rising x, of the alloys from good insulators to poor metals at low temperatures. The transitions between various magnetically ordered or disordered phases are marked by anomalies in these physical measurements. The trend of magnetic susceptibility with temperature indicates that alloys near the crossover to the highly correlated metallic state exhibit increasing charge-carrier localization with rising temperature; this is ascribed to the dominance of entropic contributions to the free energy. It is stressed that these variations in properties are achieved by isoelectronic substitutions in the anion sublattice that leave the cation sublattice undisturbed.

    14. Determination of Purity by Differential Scanning Calorimetry (DSC).

      ERIC Educational Resources Information Center

      Brown, M. E.

      1979-01-01

      An exercise is presented which demonstrates the determination of sample purity by differential scanning calorimetry. Data and references are provided to enable the exercise to be carried out as a dry-lab experiment. (BB)

    15. Non-adiabatic perturbations in multi-component perfect fluids

      SciTech Connect

      Koshelev, N.A.

      2011-04-01

      The evolution of non-adiabatic perturbations in models with multiple coupled perfect fluids with non-adiabatic sound speed is considered. Instead of splitting the entropy perturbation into relative and intrinsic parts, we introduce a set of symmetric quantities, which also govern the non-adiabatic pressure perturbation in models with energy transfer. We write the gauge invariant equations for the variables that determine on a large scale the non-adiabatic pressure perturbation and the rate of changes of the comoving curvature perturbation. The analysis of evolution of the non-adiabatic pressure perturbation has been made for several particular models.

    16. Adiabatic Far Field Sub-Diffraction Imaging

      PubMed Central

      Cang, Hu; Salandrino, Alessandro; Wang, Yuan; Zhang, Xiang

      2015-01-01

      The limited resolution of a conventional optical imaging system stems from the fact that the fine feature information of an object is carried by evanescent waves, which exponentially decay in space thus cannot reach the imaging plane. We introduce here a new concept of adiabatic lens, which utilizes a geometrically conformal surface to mediate the interference of slowly decompressed electromagnetic waves at far field to form images. The decompression is satisfying an adiabatic condition, and by bridging the gap between far field and near field, it allows far field optical systems to project an image of the near field features directly. Using these designs, we demonstrated the magnification can be up to 20 times and it is possible to achieve sub-50nm imaging resolution in visible. Our approach provides a means to extend the domain of geometrical optics to a deep sub-wavelength scale. PMID:26258769

    17. Shortcuts to adiabaticity from linear response theory.

      PubMed

      Acconcia, Thiago V; Bonança, Marcus V S; Deffner, Sebastian

      2015-10-01

      A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. With the help of phenomenological response functions, a simple expression for the excess work is found-quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. Finally, we propose a degenerate family of protocols, which facilitates shortcuts to adiabaticity for specific and very short driving times. PMID:26565209

    18. Arbitrary qudit gates by adiabatic passage

      NASA Astrophysics Data System (ADS)

      Rousseaux, B.; Guérin, S.; Vitanov, N. V.

      2013-03-01

      We derive an adiabatic technique that implements the most general SU(d) transformation in a quantum system of d degenerate states, featuring a qudit. This technique is based on the factorization of the SU(d) transformation into d generalized quantum Householder reflections, each of which is implemented by a two-shot stimulated Raman adiabatic passage with appropriate static phases. The energy of the lasers needed to synthesize a single Householder reflection is shown to be remarkably constant as a function of d. This technique is directly applicable to a linear trapped ion system with d+1 ions. We implement the quantum Fourier transform numerically in a qudit with d=4 (defined as a quartit) as an example.

    19. Trapped Ion Quantum Computation by Adiabatic Passage

      SciTech Connect

      Feng Xuni; Wu Chunfeng; Lai, C. H.; Oh, C. H.

      2008-11-07

      We propose a new universal quantum computation scheme for trapped ions in thermal motion via the technique of adiabatic passage, which incorporates the advantages of both the adiabatic passage and the model of trapped ions in thermal motion. Our scheme is immune from the decoherence due to spontaneous emission from excited states as the system in our scheme evolves along a dark state. In our scheme the vibrational degrees of freedom are not required to be cooled to their ground states because they are only virtually excited. It is shown that the fidelity of the resultant gate operation is still high even when the magnitude of the effective Rabi frequency moderately deviates from the desired value.

    20. Adiabatic Quantum Optimization for Associative Memory Recall

      NASA Astrophysics Data System (ADS)

      Seddiqi, Hadayat; Humble, Travis

      2014-12-01

      Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO). Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are stored in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.

    1. Quantum adiabatic evolution with energy degeneracy levels

      NASA Astrophysics Data System (ADS)

      Zhang, Qi

      2016-01-01

      A classical-kind phase-space formalism is developed to address the tiny intrinsic dynamical deviation from what is predicted by Wilczek-Zee theorem during quantum adiabatic evolution on degeneracy levels. In this formalism, the Hilbert space and the aggregate of degenerate eigenstates become the classical-kind phase space and a high-dimensional subspace in the phase space, respectively. Compared with the previous analogous study by a different method, the current result is qualitatively different in that the first-order deviation derived here is always perpendicular to the degeneracy subspace. A tripod-scheme Hamiltonian with two degenerate dark states is employed to illustrate the adiabatic deviation with degeneracy levels.

    2. Shortcuts to adiabaticity from linear response theory

      NASA Astrophysics Data System (ADS)

      Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian

      2015-10-01

      A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. With the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. Finally, we propose a degenerate family of protocols, which facilitates shortcuts to adiabaticity for specific and very short driving times.

    3. Adiabatic quantum optimization for associative memory recall

      DOE PAGESBeta

      Seddiqi, Hadayat; Humble, Travis S.

      2014-12-22

      Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO). Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are storedmore » in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.« less

    4. Adiabatic quantum optimization for associative memory recall

      SciTech Connect

      Seddiqi, Hadayat; Humble, Travis S.

      2014-12-22

      Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO). Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are stored in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.

    5. Shortcuts to adiabaticity from linear response theory

      SciTech Connect

      Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian

      2015-10-23

      A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts to adiabaticity for specific and very short driving times.

    6. Shortcuts to adiabaticity from linear response theory

      DOE PAGESBeta

      Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian

      2015-10-23

      A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts tomore » adiabaticity for specific and very short driving times.« less

    7. Adiabatic Quantization of Andreev Quantum Billiard Levels

      NASA Astrophysics Data System (ADS)

      Silvestrov, P. G.; Goorden, M. C.; Beenakker, C. W.

      2003-03-01

      We identify the time T between Andreev reflections as a classical adiabatic invariant in a ballistic chaotic cavity (Lyapunov exponent λ), coupled to a superconductor by an N-mode constriction. Quantization of the adiabatically invariant torus in phase space gives a discrete set of periods Tn, which in turn generate a ladder of excited states ɛnm=(m+1/2)πℏ/Tn. The largest quantized period is the Ehrenfest time T0=λ-1ln(N. Projection of the invariant torus onto the coordinate plane shows that the wave functions inside the cavity are squeezed to a transverse dimension W/(N), much below the width W of the constriction.

    8. Adiabatic state preparation study of methylene

      SciTech Connect

      Veis, Libor Pittner, Jiří

      2014-06-07

      Quantum computers attract much attention as they promise to outperform their classical counterparts in solving certain type of problems. One of them with practical applications in quantum chemistry is simulation of complex quantum systems. An essential ingredient of efficient quantum simulation algorithms are initial guesses of the exact wave functions with high enough fidelity. As was proposed in Aspuru-Guzik et al. [Science 309, 1704 (2005)], the exact ground states can in principle be prepared by the adiabatic state preparation method. Here, we apply this approach to preparation of the lowest lying multireference singlet electronic state of methylene and numerically investigate preparation of this state at different molecular geometries. We then propose modifications that lead to speeding up the preparation process. Finally, we decompose the minimal adiabatic state preparation employing the direct mapping in terms of two-qubit interactions.

    9. Adiabatic Quantum Simulation of Quantum Chemistry

      PubMed Central

      Babbush, Ryan; Love, Peter J.; Aspuru-Guzik, Alán

      2014-01-01

      We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions. PMID:25308187

    10. Pulse sequences in photoassociation via adiabatic passage

      NASA Astrophysics Data System (ADS)

      Li, Xuan; Dupre, William; Parker, Gregory A.

      2012-07-01

      We perform a detailed study of pulse sequences in a photoassociation via adiabatic passage (PAP) process to transfer population from an ensemble of ultracold atomic clouds to a vibrationally cold molecular state. We show that an appreciable final population of ultracold NaCs molecules can be achieved with optimized pulses in either the ‘counter-intuitive’ (tP > tS) or ‘intuitive’ (tP < tS) PAP pulse sequences, with tP and tS denoting the temporal centers of the pump and Stokes pulses, respectively. By investigating the dependence of the reactive yield on pulse sequences, in a wide range of tP-tS, we show that there is not a fundamental preference to either pulse sequence in a PAP process. We explain this no-sequence-preference phenomenon by analyzing a multi-bound model so that an analogy can be drawn to the conventional stimulated Raman adiabatic passage.

    11. Adiabatic charging of nickel-hydrogen batteries

      NASA Technical Reports Server (NTRS)

      Lurie, Chuck; Foroozan, S.; Brewer, Jeff; Jackson, Lorna

      1995-01-01

      Battery management during prelaunch activities has always required special attention and careful planning. The transition from nickel-cadium to nickel-hydrogen batteries, with their high self discharge rate and lower charge efficiency, as well as longer prelaunch scenarios, has made this aspect of spacecraft battery management even more challenging. The AXAF-I Program requires high battery state of charge at launch. The use of active cooling, to ensure efficient charging, was considered and proved to be difficult and expensive. Alternative approaches were evaluated. Optimized charging, in the absence of cooling, appeared promising and was investigated. Initial testing was conducted to demonstrate the feasibility of the 'Adiabatic Charging' approach. Feasibility was demonstrated and additional testing performed to provide a quantitative, parametric data base. The assumption that the battery is in an adiabatic environment during prelaunch charging is a conservative approximation because the battery will transfer some heat to its surroundings by convective air cooling. The amount is small compared to the heat dissipated during battery overcharge. Because the battery has a large thermal mass, substantial overcharge can occur before the cells get too hot to charge efficiently. The testing presented here simulates a true adiabatic environment. Accordingly the data base may be slightly conservative. The adiabatic charge methodology used in this investigation begins with stabilizing the cell at a given starting temperature. The cell is then fully insulated on all sides. Battery temperature is carefully monitored and the charge terminated when the cell temperature reaches 85 F. Charging has been evaluated with starting temperatures from 55 to 75 F.

    12. Advanced Adiabatic Demagnetization Refrigerators for Continuous Cooling

      NASA Technical Reports Server (NTRS)

      Chu, Paul C. W.

      2004-01-01

      The research at Houston was focused on optimizing the design of superconducting magnets for advanced adiabatic demagnetization refrigerators (ADRs), assessing the feasibility of using high temperature superconducting (HTS) magnets in ADRs in the future, and developing techniques to deposit HTS thin and thick films on high strength, low thermal conductivity substrates for HTS magnet leads. Several approaches have been tested for the suggested superconducting magnets.

    13. Computer Code For Turbocompounded Adiabatic Diesel Engine

      NASA Technical Reports Server (NTRS)

      Assanis, D. N.; Heywood, J. B.

      1988-01-01

      Computer simulation developed to study advantages of increased exhaust enthalpy in adiabatic turbocompounded diesel engine. Subsytems of conceptual engine include compressor, reciprocator, turbocharger turbine, compounded turbine, ducting, and heat exchangers. Focus of simulation of total system is to define transfers of mass and energy, including release and transfer of heat and transfer of work in each subsystem, and relationship among subsystems. Written in FORTRAN IV.

    14. Siphon flows in isolated magnetic flux tubes. II - Adiabatic flows

      NASA Technical Reports Server (NTRS)

      Montesinos, Benjamin; Thomas, John H.

      1989-01-01

      This paper extends the study of steady siphon flows in isolated magnetic flux tubes surrounded by field-free gas to the case of adiabatic flows. The basic equations governing steady adiabatic siphon flows in a thin, isolated magnetic flux tube are summarized, and qualitative features of adiabatic flows in elevated, arched flux tubes are discussed. The equations are then cast in nondimensional form and the results of numerical computations of adiabatic siphon flows in arched flux tubes are presented along with comparisons between isothermal and adiabatic flows. The effects of making the interior of the flux tube hotter or colder than the surrounding atmosphere at the upstream footpoint of the arch is considered. In this case, is it found that the adiabatic flows are qualitatively similar to the isothermal flows, with adiabatic cooling producing quantitative differences. Critical flows can produce a bulge point in the rising part of the arch and a concentration of magnetic flux above the bulge point.

    15. Random matrix model of adiabatic quantum computing

      SciTech Connect

      Mitchell, David R.; Adami, Christoph; Lue, Waynn; Williams, Colin P.

      2005-05-15

      We present an analysis of the quantum adiabatic algorithm for solving hard instances of 3-SAT (an NP-complete problem) in terms of random matrix theory (RMT). We determine the global regularity of the spectral fluctuations of the instantaneous Hamiltonians encountered during the interpolation between the starting Hamiltonians and the ones whose ground states encode the solutions to the computational problems of interest. At each interpolation point, we quantify the degree of regularity of the average spectral distribution via its Brody parameter, a measure that distinguishes regular (i.e., Poissonian) from chaotic (i.e., Wigner-type) distributions of normalized nearest-neighbor spacings. We find that for hard problem instances - i.e., those having a critical ratio of clauses to variables - the spectral fluctuations typically become irregular across a contiguous region of the interpolation parameter, while the spectrum is regular for easy instances. Within the hard region, RMT may be applied to obtain a mathematical model of the probability of avoided level crossings and concomitant failure rate of the adiabatic algorithm due to nonadiabatic Landau-Zener-type transitions. Our model predicts that if the interpolation is performed at a uniform rate, the average failure rate of the quantum adiabatic algorithm, when averaged over hard problem instances, scales exponentially with increasing problem size.

    16. Adiabatic heating in impulsive solar flares

      NASA Technical Reports Server (NTRS)

      Maetzler, C.; Bai, T.; Crannell, C. J.; Frost, K. J.

      1978-01-01

      A study is made of adiabatic heating in two impulsive solar flares on the basis of dynamic X-ray spectra in the 28-254 keV range, H-alpha, microwave, and meter-wave radio observations. It is found that the X-ray spectra of the events are like those of thermal bremsstrahlung from single-temperature plasmas in the 10-60 keV range if photospheric albedo is taken into account. The temperature-emission correlation indicates adiabatic compression followed by adiabatic expansion and that the electron distribution remains isotropic. H-alpha data suggest compressive energy transfer. The projected areas and volumes of the flares are estimated assuming that X-ray and microwave emissions are produced in a single thermal plasma. Electron densities of about 10 to the 9th/cu cm are found for homogeneous, spherically symmetric sources. It is noted that the strong self-absorption of hot-plasma gyrosynchrotron radiation reveals low magnetic field strengths.

    17. Aspects of adiabatic population transfer and control

      NASA Astrophysics Data System (ADS)

      Demirplak, Mustafa

      This thesis explores two different questions. The first question we answer is how to restore a given population transfer scenario given that it works efficiently in the adiabatic limit but fails because of lack of intensity and/or short duration. We derive a very simple algorithm to do this and apply it to both toy and realistic models. Two results emerge from this study. While the mathematical existence of the programme is certain it might not always be physically desirable. The restoration of adiabaticity is phase sensitive. The second question that is answered in this thesis is not how to invent new control paradigms, but rather what would happen to them in the presence of stochastic perturbers. We first use a phenomenological model to study the effect of stochastic dephasing on population transfer by stimulated Raman adiabatic passage. The results of this Monte Carlo calculation are qualitatively explained with a perturbation theoretical result in the dressed state basis. The reliability of our phenomenological model is questioned through a more rigorous hybrid quantal-classical simulation of controlled population transfer in HCl in Ar.

    18. Non-adiabatic effect on quantum pumping

      NASA Astrophysics Data System (ADS)

      Uchiyama, Chikako

      2014-03-01

      We study quantum pumping for an anharmonic junction model which interacts with two kinds of bosonic environments. We provide an expression for the quantum pumping under a piecewise modulation of environmental temperatures with including non-adiabatic effect under Markovian approximation. The obtained formula is an extension of the one expressed with the geometrical phase(Phys. Rev. Lett. 104,170601 (2010)). This extension shows that the quantum pumping depends on the initial condition of the anharmonic junction just before the modulation, as well as the characteristic environmental parameters such as interaction strength and cut-off frequencies of spectral density other than the conditions of modulation. We clarify that the pumping current including non-adiabatic effect can be larger than that under the adiabatic condition. This means that we can find the optimal condition of the current by adjusting these parameters. (The article has been submitted as http://arxiv.org/submit/848201 and will be appeared soon.) This work is supported by a Grant-in-Aid for Scientific Research (B) (KAKENHI 25287098).

    19. An adiabatic approximation for grain alignment theory

      NASA Astrophysics Data System (ADS)

      Roberge, W. G.

      1997-10-01

      The alignment of interstellar dust grains is described by the joint distribution function for certain `internal' and `external' variables, where the former describe the orientation of the axes of a grain with respect to its angular momentum, J, and the latter describe the orientation of J relative to the interstellar magnetic field. I show how the large disparity between the dynamical time-scales of the internal and external variables - which is typically 2-3 orders of magnitude - can be exploited to simplify calculations of the required distribution greatly. The method is based on an `adiabatic approximation' which closely resembles the Born-Oppenheimer approximation in quantum mechanics. The adiabatic approximation prescribes an analytic distribution function for the `fast' dynamical variables and a simplified Fokker-Planck equation for the `slow' variables which can be solved straightforwardly using various techniques. These solutions are accurate to O(epsilon), where epsilon is the ratio of the fast and slow dynamical time-scales. As a simple illustration of the method, I derive an analytic solution for the joint distribution established when Barnett relaxation acts in concert with gas damping. The statistics of the analytic solution agree with the results of laborious numerical calculations which do not exploit the adiabatic approximation.

    20. An Adiabatic Approximation for Grain Alignment Theory

      NASA Astrophysics Data System (ADS)

      Roberge, W. G.

      1997-12-01

      The alignment of interstellar dust grains is described by the joint distribution function for certain ``internal'' and ``external'' variables, where the former describe the orientation of a grain's axes with respect to its angular momentum, J, and the latter describe the orientation of J relative to the interstellar magnetic field. I show how the large disparity between the dynamical timescales of the internal and external variables--- which is typically 2--3 orders of magnitude--- can be exploited to greatly simplify calculations of the required distribution. The method is based on an ``adiabatic approximation'' which closely resembles the Born-Oppenheimer approximation in quantum mechanics. The adiabatic approximation prescribes an analytic distribution function for the ``fast'' dynamical variables and a simplified Fokker-Planck equation for the ``slow'' variables which can be solved straightforwardly using various techniques. These solutions are accurate to cal {O}(epsilon ), where epsilon is the ratio of the fast and slow dynamical timescales. As a simple illustration of the method, I derive an analytic solution for the joint distribution established when Barnett relaxation acts in concert with gas damping. The statistics of the analytic solution agree with the results of laborious numerical calculations which do not exploit the adiabatic approximation.

    1. Electronically- and crystal-structure-driven magnetic structures and physical properties of RScSb (R = rare earth) compounds. A neutron diffraction, magnetization and heat capacity study

      SciTech Connect

      Ritter, C; Dhar, S K; Kulkarni, R; Provino, A; Paudyal, Durga; Manfrinetti, Pietro; Gschneidner, Karl A

      2014-08-14

      The synthesis of the new equiatomic RScSb ( R = La-Nd, Sm, Gd-Tm, Lu, Y) compounds has been recently reported. These rare earth compounds crystallize in two different crystal structures, adopting the CeScSi-type ( I 4/ mmm) for the lighter R (La-Nd, Sm) and the CeFeSi-type (P4 /nmm) structure for the heavier R ( R = Gd-Tm, Lu, Y). Here we report the results of neutron diffraction, magnetization and heat capacity measurements on some of these compounds ( R = Ce, Pr, Nd, Gd and Tb). Band structure calculations have also been performed on CeScSb and GdScGe (CeScSi-type), and on GdScSb and TbScSb (CeFeSi-type) to compare and understand the exchange interactions in CeScSi and CeFeSi structure types. The neutron diffraction investigation shows that all five compounds order magnetically, with the highest transition temperature of 66 K in TbScSb and the lowest of about 9 K in CeScSb. The magnetic ground state is simple ferromagnetic (τ = [0 0 0]) in CeScSb, as well in NdScSb for 32 >T > 22 K. Below 22 K a second magnetic transition, with propagation vector τ = [¼ ¼ 0], appears in NdScSb. PrScSb has a magnetic structure within, determined by mostly ferromagnetic interactions and antiferromagnetic alignment of the Pr-sites connected through the I-centering ( τ = [1 0 0]). A cycloidal spiral structure with a temperature dependent propagation vector τ = [δ δ ½] is found in TbScSb. The results of magnetization and heat capacity lend support to the main conclusions derived from neutron diffraction. As inferred from a sharp peak in magnetization, GdScSb orders antiferromagnetically at 56 K. First principles calculations show lateral shift of spin split bands towards lower energy from the Fermi level as the CeScSi-type structure changes to the CeFeSi-type structure. This rigid shift may force the system to transform from exchange split ferromagnetic state to the antiferromagnetic state in RScSb compounds (as seen for example in GdScSb and TbScSb) and is proposed to

    2. Heat Capacity Mapping Mission (HCMM)

      NASA Technical Reports Server (NTRS)

      Jackson, R. D. (Principal Investigator)

      1980-01-01

      Tapes for day and night passes on May 16 and May 20, 1978 and a day pass on May 3, 1980 were processed. Results indicate that it is extremely difficult to locate a field of 9 pixel size and temperature data from the HCMM are consistently lower than temperatures measured with a scanner flown at low altitudes. The temperature differences between the satellite and aircraft data appear to be temperature dependent, being smaller at lower temperatures. Three data points are in the format (airc, HCMM) (12,9), (30,23), and (39,30). The linear equation for these three points is T sub HCMM = 0.778 T sub airc -0.33.

    3. HCMM Heat Capacity Mapping Mission

      NASA Technical Reports Server (NTRS)

      Jackson, R. D. (Principal Investigator)

      1978-01-01

      The author has identified the following significant results. Thermal imagery shows a large temperature variation over the 640 acre experimental site. The variation is due to the slope and aspect of the terrain as well as the aircraft flight direction (east-west versus north-south). In spite of these individual temperature differences, mean temperature values from 40 to 640 acre blocks are essentially identical regardless of aircraft flight direction.

    4. Chemistry Lab--Heat Capacity.

      ERIC Educational Resources Information Center

      Stern, Robert

      1998-01-01

      Explores measuring the specific heat of a metal ball. The ball is heated to a known temperature then placed in cold water. Students measure the temperature gain of the water in this investigation of the principle of Conservation of Energy. As a second task, students make a precise determination of the density of the ball. (PVD)

    5. Multiple pulse-heating experiments with different current to determine total emissivity, heat capacity, and electrical resistivity of electrically conductive materials at high temperatures.

      PubMed

      Watanabe, Hiromichi; Yamashita, Yuichiro

      2012-01-01

      A modified pulse-heating method is proposed to improve the accuracy of measurement of the hemispherical total emissivity, specific heat capacity, and electrical resistivity of electrically conductive materials at high temperatures. The proposed method is based on the analysis of a series of rapid resistive self-heating experiments on a sample heated at different temperature rates. The method is used to measure the three properties of the IG-110 grade of isotropic graphite at temperatures from 850 to 1800 K. The problem of the extrinsic heating-rate effect, which reduces the accuracy of the measurements, is successfully mitigated by compensating for the generally neglected experimental error associated with the electrical measurands (current and voltage). The results obtained by the proposed method can be validated by the linearity of measured quantities used in the property determinations. The results are in reasonably good agreement with previously published data, which demonstrate the suitability of the proposed method, in particular, to the resistivity and total emissivity measurements. An interesting result is the existence of a minimum in the emissivity of the isotropic graphite at around 1120 K, consistent with the electrical resistivity results. PMID:22299976

    6. Negative heat-capacity at phase-separations in microcanonical thermostatistics of macroscopic systems with either short or long-range interactions

      NASA Astrophysics Data System (ADS)

      Gross, D. H. E.

      2006-06-01

      Conventional thermo-statistics address infinite homogeneous systems within the canonical ensemble. However, some 170 years ago the original motivation of thermodynamics was the description of steam engines, i.e., boiling water. Its essential physics is the separation of the gas phase from the liquid. Of course, boiling water is inhomogeneous and as such cannot be treated by conventional thermo-statistics. Then it is not astonishing, that a phase transition of first order is signaled canonically by a Yang Lee singularity. Thus, it is only treated correctly by microcanonical Boltzmann Planck statistics. This was elaborated in the talk presented at this conference. It turns out that the Boltzmann Planck statistics is much richer and gives fundamental insight into statistical mechanics and especially into entropy. This can be done to a far extend rigorously and analytically. The deep and essential difference between “extensive” and “intensive” control parameters, i.e., microcanonical and canonical statistics, was exemplified by rotating, self-gravitating systems. In the present paper the necessary appearance of a convex entropy S(E) and the negative heat capacity at phase separation in small as well macroscopic systems independently of the range of the force is pointed out.

    7. Effects of changes in packed cell volume on the specific heat capacity of blood: implications for studies measuring heat exchange in extracorporeal circuits.

      PubMed

      Blake, A S; Petley, G W; Deakin, C D

      2000-01-01

      Extracorporeal circuits such as cardiopulmonary bypass (CPB) and renal dialysis machines cause active and/or passive loss of body heat. Attempts to quantify this heat loss are generally based on the Fick principle which requires knowledge of the specific heat capacity (SHC) of blood. As changes in packed cell volume are common, we investigated the effect of these changes on the SHC of blood over a range of packed cell volumes (PCV) from whole blood at 43.1% (3594 J kg-1 degrees C-1) to pure Hartmann's solution (4153 J kg-1 degrees C-1). The SHC of other fluids used during CPB was also measured and found to be 4139 J kg-1 degrees C-1 and 4082 J kg-1 degrees C-1 for normal saline and Gelofusine, respectively. The maximum variability in SHC over the range of PCV values encountered during CPB was calculated to be small (5.5%). We conclude that use of a constant value of SHC for calculation of thermal energy transfer is currently justified. PMID:10740543

    8. Heat Capacity Study of the Field-Induced Gap in the Linear, S=1/2, Antiferromagnetic Heisenberg Spin Chain Copper Benzoate

      NASA Astrophysics Data System (ADS)

      Hammar, P. R.; Dender, D. C.; Broholm, C.; Reich, D. H.

      1997-03-01

      Copper Benzoate is an established S=1/2 linear antiferromagnetic Heisenberg spin chain. A recent inelastic neutron scattering experiment found low lying excitations at incommensurate wave vectors in a magnetic field.(D. C. Dender, P. R. Hammar, C. Broholm, D. H. Reich, G. Aeppli, (to be published)) However, contrary to theoretical predictions,(G. Müller, H. Thomas, H. Beck, J. C. Bonner, Phys. Rev. B 24) 1428 (1981). this experiment showed a field-induced gap in the magnetic excitation spectrum. We present heat capacity data that explore the evolution of this gap with applied magnetic field. The gap is highly dependent on field direction, and is a result of the relative anisotropies in the plane perpendicular to the field. The gaps in the largest field measured (H = 8.8 T) are Δb = 2.81 K, Δ_a^'' = 1.57(5) K, and Δ_c^'' = 5.4(1) K where b, c^'' and a^'' are the antiferromagnetic principal axes.

    9. Heat Capacity and Thermal Conductance Measurements of a Superconducting-Normal Mixed State by Detection of Single 3 eV Photons in a Magnetic Penetration Thermometer

      NASA Technical Reports Server (NTRS)

      Stevenson, T. R.; Balvin, M. A.; Bandler, S. R.; Denis, K. L.; Lee, S.-J.; Nagler, P. C.; Smith, S. J.

      2015-01-01

      We report on measurements of the detected signal pulses in a molybdenum-gold Magnetic Penetration Thermometer (MPT) in response to absorption of one or more 3 eV photons. We designed and used this MPT sensor for x-ray microcalorimetry. In this device, the diamagnetic response of a superconducting MoAu bilayer is used to sense temperature changes in response to absorbed photons, and responsivity is enhanced by a Meissner transition in which the magnetic flux penetrating the sensor changes rapidly to minimize free energy in a mixed superconducting normal state. We have previously reported on use of our MPT to study a thermal phonon energy loss to the substrate when absorbing x-rays. We now describe results of extracting heat capacity C and thermal conductance G values from pulse height and decay time of MPT pulses generated by 3 eV photons. The variation in C and G at temperatures near the Meissner transition temperature (set by an internal magnetic bias field) allow us to probe the behavior in superconducting normal mixed state of the condensation energy and the electron cooling power resulting from quasi-particle recombination and phonon emission. The information gained on electron cooling power is also relevant to the operation of other superconducting detectors, such as Microwave Kinetic Inductance Detectors.

    10. Transition Helmholtz free energy, entropy, and heat capacity of free-standing smectic films in water: A mean-field treatment

      SciTech Connect

      Śliwa, Izabela; Zakharov, A. V.

      2014-11-21

      Using the extended McMillan's mean field approach with anisotropic forces a study of both the structural and thermodynamic properties of free-standing smectic film (FSSF) in water on heating to the isotropic temperature is carried out numerically. By solving the self-consistent nonlinear equations for the order parameters, we obtained that the smectic-A-isotropic (AI) transition occurs through the series of layer-thinning transitions causing the films to thin in the stepwise manner as the temperature is increased above the bulk smectic-A-isotropic temperature T{sub AI}(bulk). With enhanced pair interactions in the bounding layers, the smectic-isotropic transition corresponds to smectic melting of the central layers. The effects of surface “enhanced” pair interactions in the bounding layers and of film thickness on the orientational and translational order parameters, the Helmholtz free energy and entropy, as well as the temperature dependence of the heat capacity of FSSFs, have also been investigated. Reasonable agreement between the theoretically predicted and the experimentally obtained – by means of optical microscopy and ellipsometry techniques – data of the temperature when the thin decylcyanobiphenyl smectic film immersing in water ruptures has been obtained.

    11. Bond selective chemistry beyond the adiabatic approximation

      SciTech Connect

      Butler, L.J.

      1993-12-01

      One of the most important challenges in chemistry is to develop predictive ability for the branching between energetically allowed chemical reaction pathways. Such predictive capability, coupled with a fundamental understanding of the important molecular interactions, is essential to the development and utilization of new fuels and the design of efficient combustion processes. Existing transition state and exact quantum theories successfully predict the branching between available product channels for systems in which each reaction coordinate can be adequately described by different paths along a single adiabatic potential energy surface. In particular, unimolecular dissociation following thermal, infrared multiphoton, or overtone excitation in the ground state yields a branching between energetically allowed product channels which can be successfully predicted by the application of statistical theories, i.e. the weakest bond breaks. (The predictions are particularly good for competing reactions in which when there is no saddle point along the reaction coordinates, as in simple bond fission reactions.) The predicted lack of bond selectivity results from the assumption of rapid internal vibrational energy redistribution and the implicit use of a single adiabatic Born-Oppenheimer potential energy surface for the reaction. However, the adiabatic approximation is not valid for the reaction of a wide variety of energetic materials and organic fuels; coupling between the electronic states of the reacting species play a a key role in determining the selectivity of the chemical reactions induced. The work described below investigated the central role played by coupling between electronic states in polyatomic molecules in determining the selective branching between energetically allowed fragmentation pathways in two key systems.

    12. Analysis of the heat capacity for pure CH4 and CH4/CCl4 on graphite near the melting point and calculation of the T-X phase diagram for (CH3)CCl3 + CCl4

      NASA Astrophysics Data System (ADS)

      Yurtseven, Hamit; Yılmaz, Aygül

      2016-06-01

      We study the temperature dependence of the heat capacity Cp for the pure CH4 and the coadsorbed CH4/CCl4 on graphite near the melting point. The heat capacity peaks are analyzed using the experimental data from the literature by means of the power-law formula. The critical exponents for the heat capacity are deduced below and above the melting point for CH4 (Tm = 104.8 K) and CH4/CCl4 (Tm = 99.2 K). Our exponent values are larger as compared with the predicted values of some theoretical models exhibiting second order transition. Our analyses indicate that the pure methane shows a nearly second order (weak discontinuity in the heat capacity peak), whereas the transition in coadsorbed CH4/CCl4 is of first order (apparent discontinuity in Cp). We also study the T – X phase diagram of a two-component system of CH3CCl3+CCl4 using the Landau phenomenological model. Phase lines of the R+L (rhombohedral+liquid) and FCC+L (face-centred cubic + liquid) are calculated using the observed T – X phase diagram of this binary mixture. Our results show that the Landau mean field theory describes the observed behavior of CH3CCl3+CCl4 adequately. From the calculated T – X phase diagram, critical behavior of some thermodynamic quantities can be predicted at various temperatures and concentrations (CCl4) for a binary mixture of CH3CCl3+CCl4.

    13. Phase avalanches in near-adiabatic evolutions

      SciTech Connect

      Vertesi, T.; Englman, R.

      2006-02-15

      In the course of slow, nearly adiabatic motion of a system, relative changes in the slowness can cause abrupt and high magnitude phase changes, ''phase avalanches,'' superimposed on the ordinary geometric phases. The generality of this effect is examined for arbitrary Hamiltonians and multicomponent (>2) wave packets and is found to be connected (through the Blaschke term in the theory of analytic signals) to amplitude zeros in the lower half of the complex time plane. Motion on a nonmaximal circle on the Poincare-sphere suppresses the effect. A spectroscopic transition experiment can independently verify the phase-avalanche magnitudes.

    14. Adiabatic chaos in the spin orbit problem

      NASA Astrophysics Data System (ADS)

      Benettin, Giancarlo; Guzzo, Massimiliano; Marini, Valerio

      2008-05-01

      We provide evidences that the angular momentum of a symmetric rigid body in a spin orbit resonance can perform large scale chaotic motions on time scales which increase polynomially with the inverse of the oblateness of the body. This kind of irregular precession appears as soon as the orbit of the center of mass is non-circular and the angular momentum of the body is far from the principal directions with minimum (maximum) moment of inertia. We also provide a quantitative explanation of these facts by using the theory of adiabatic invariants, and we provide numerical applications to the cases of the 1:1 and 1:2 spin orbit resonances.

    15. Experimental breaking of an adiabatic invariant

      NASA Astrophysics Data System (ADS)

      Notte, J.; Fajans, J.; Chu, R.; Wurtele, J. S.

      1993-06-01

      When a cylindrical pure electron plasma is displaced from the center of the trap, it performs a bulk circular orbital motion known as the l=1 diocotron mode. The slow application of a perturbing potential to a patch on the trap wall distorts the orbit into a noncircular closed path. Experiments and a simple theoretical model indicate that the area by the loop is an adiabatic invariant. Detailed studies are made of the breaking of the invariant when perturbations are rapidly applied. When the perturbation is applied with discontinuous time derivatives, the invariant breaking greatly exceeds the predictions of the standard theory for smooth perturbations.

    16. [Bond selective chemistry beyond the adiabatic approximation

      SciTech Connect

      Butler, L.J.

      1993-02-28

      The adiabatic Born-Oppenheimer potential energy surface approximation is not valid for reaction of a wide variety of energetic materials and organic fuels; coupling between electronic states of reacting species plays a key role in determining the selectivity of the chemical reactions induced. This research program initially studies this coupling in (1) selective C-Br bond fission in 1,3- bromoiodopropane, (2) C-S:S-H bond fission branching in CH[sub 3]SH, and (3) competition between bond fission channels and H[sub 2] elimination in CH[sub 3]NH[sub 2].

    17. Adiabatic passage in the presence of noise

      NASA Astrophysics Data System (ADS)

      Noel, T.; Dietrich, M. R.; Kurz, N.; Shu, G.; Wright, J.; Blinov, B. B.

      2012-02-01

      We report on an experimental investigation of rapid adiabatic passage (RAP) in a trapped barium ion system. RAP is implemented on the transition from the 6S1/2 ground state to the metastable 5D5/2 level by applying a laser at 1.76 μm. We focus on the interplay of laser frequency noise and laser power in shaping the effectiveness of RAP, which is commonly assumed to be a robust tool for high-efficiency population transfer. However, we note that reaching high state transfer fidelity requires a combination of small laser linewidth and large Rabi frequency.

    18. Adiabatic demagnetization refrigerator for space use

      NASA Technical Reports Server (NTRS)

      Serlemitsos, A. T.; Warner, B. A.; Castles, S.; Breon, S. R.; San Sebastian, M.; Hait, T.

      1990-01-01

      An Adiabatic Demagnetization Refrigerator (ADR) for space use is under development at NASA's Goddard Space Flight Center (GSFC). The breadboard ADR operated at 100 mK for 400 minutes. Some significant changes to that ADR, designed to eliminate shortcomings revealed during tests, are reported. To increase thermal contact, the ferric ammonium sulfate crystals were grown directly on gold-plated copper wires which serve as the thermal bus. The thermal link to the X-ray sensors was also markedly improved. To speed up the testing required to determine the best design parameters for the gas gap heat switch, the new heat switch has a modular design and is easy to disassemble.

    19. An adiabatic demagnetization refrigerator for infrared bolometers

      NASA Technical Reports Server (NTRS)

      Britt, R. D.; Richards, P. L.

      1981-01-01

      Adiabatic demagnetization refrigerators have been built and installed in small portable liquid helium cryostats to test the feasibility of this method of cooling infrared bolometric detectors to temperatures below 0.3 K. Performance has been achieved which suggests that bolometer temperatures of 0.2 K can be maintained for periods of approximately 60 hours. Applications to sensitive infrared detection from ground-based telescopes and space satellites are discussed. Design data are given which permit the evaluation of refrigerator performance for a variety of design parameters.

    20. Generalized Ramsey numbers through adiabatic quantum optimization

      NASA Astrophysics Data System (ADS)

      Ranjbar, Mani; Macready, William G.; Clark, Lane; Gaitan, Frank

      2016-06-01

      Ramsey theory is an active research area in combinatorics whose central theme is the emergence of order in large disordered structures, with Ramsey numbers marking the threshold at which this order first appears. For generalized Ramsey numbers r(G, H), the emergent order is characterized by graphs G and H. In this paper we: (i) present a quantum algorithm for computing generalized Ramsey numbers by reformulating the computation as a combinatorial optimization problem which is solved using adiabatic quantum optimization; and (ii) determine the Ramsey numbers r({{T}}m,{{T}}n) for trees of order m,n = 6,7,8 , most of which were previously unknown.