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Sample records for heat capacity anomalies

  1. 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

  2. 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.

  3. 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).

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Ocean response to surface heat anomalies

    NASA Technical Reports Server (NTRS)

    Jiang, Xingjian; Fung, Inez

    1994-01-01

    An ocean general circulation model (OGCM) is used to study the response of ocean heat and mass transport to positive and negative heat flux anomalies at the ocean surface. As expected, tropical and low-latitude mixed layers respond rapidly (e-folding time about 50-70 years) to external forcing, while the response of the high-latitude mixed layer, especially the Southern Ocean and northern North Atlantic, is very slow (e-folding time greater than 300 yr). The overall response is faster for negative than positive heat flux anomaly at the surface. The meridional heat transport changes by 15% in the first 50 yr in the southern high latitudes. Surprisingly, for the next 400-500 yr the change is very small. The analysis shows that the meridional mass transport intensifies in response to a negative surface heat flux anomaly but weakens in response to a positive heat flux anomaly. For example, at model year 100 the North Atlantic Deep Water (NADW) is reduced from about 18 Sv to about 10 Sv for the positive heat flux experiment but increased to about 26 Sv for the negative heat flux experiment.

  14. 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

  15. 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.

  16. Heat flux boundary anomalies and thermal winds

    NASA Astrophysics Data System (ADS)

    Dietrich, Wieland; Wicht, Johannes

    2013-04-01

    Several studies have shown strong effects of outer boundary heat flux patterns on the dynamo mechanism in planets. For example, the hemispherical field of the ancient Martian dynamo can be explained by a large scale sinusoidal anomaly of the core mantle boundary heat flux triggered by large scale mantle convection or giant impacts. The magnetic fields show typically the desired effect - though dynamo action is locally stronger where the underneath heat flux is higher. However, it remains an open question if these effects still apply for more realistic planetary parameters, such as vigor of the convection (Rayleigh number) or the rotation rate (Ekman). The sinusoidal variation of the CMB heat flux along the colatitude with larger heat flux in the southern and smaller in the northern hemisphere as used for Mars can lead to a concentration of magnetic field in the south. The shape of such a hemispherical dynamo matches the crustal magnetization pattern at the surface and seems therefore an admissible mode for the ancient Martian dynamo. As the consequence of the emerging latitudinal temperature gradients convection and induction are dominated by thermal winds. These zonal flows were found to be equatorial antisymmetric, axisymmetric, ageostrophic, of strong amplitude and have therefore a severe effect on core convection and especially the induction process. We measure the underlying thermal anomalies as a function of Rayleigh and Ekman number and show that they are responsible for the thermal winds. Our results suggest that temperature anomalies decrease clearly with the supercriticality of the convection due to faster stirring and mixing, but show no additional dependence on the Ekman number. Interestingly, the decline of the latitudinal temperature anomaly follows a recently suggested scaling law for the thickness of thermal boundary layers. Even though the convective supercriticality of planetary cores is rather large and therefore only a minor effect of thermal

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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…

  3. Alternate high capacity heat pipe

    NASA Technical Reports Server (NTRS)

    Voss, F. E.

    1986-01-01

    The performance predictions for a fifty foot heat pipe (4 foot evaporator - 46 foot condensor) are discussed. These performance predictions are supported by experimental data for a four foot heat pipe. Both heat pipes have evaporators with axial groove wick structures and condensers with powder metal external artery wick structures. The predicted performance of a rectangular axial groove/external artery heat pipe operating in space is given. Heat transport versus groove width is plotted for 100, 200 and 300 grooves in the evaporator. The curves show that maximum power is achieved for groove widths from 0.040 to 0.053 as the number of grooves varies from 300 to 100. The corresponding range of maximum power is 3150 to 2400 watts. The relationships between groove width and heat pipe evaporate diameter for 100, 200 and 300 grooves in the evaporator are given. A four foot heat pipe having a three foot condenser and one foot evaporator was built and tested. The evaporator wick structure used axial grooves with rectangular cross sections, and the condenser wick structure used powder metal with an external artery configuration. Fabrication drawings are enclosed. The predicted and measured performance for this heat pipe is shown. The agreement between predicted and measured performance is good and therefore substantiates the predicted performance for a fifty foot heat pipe.

  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. 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.

  6. 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.

  7. 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.

  8. The 55 K specific heat anomaly in palladium hydride

    NASA Technical Reports Server (NTRS)

    Jacobi, N.; Vaughan, R. W.

    1976-01-01

    A specific heat anomaly in PdH and PdD has been observed by Aston et al. (1957) close to 55 K. Its position was found to be independent of hydrogen concentration and its magnitude to be linear in hydrogen concentration. Ferguson's (1965) and Brodowsky's (1972) explanations of the anomaly are shown to be unsatisfactory. This is true also for the detailed mechanical statistical model proposed by Staford and McLellan (1974) for interstitial solid solutions of hydrogen in transition metals. It is shown that Gopal's (1966) simple Schottky model of specific heat anomaly, which considers a system of several levels with Boltzmann statistics, provides much better agreement with experiment than the more elaborate models, both in magnitude and in predicting a linear dependence on hydrogen concentration.

  9. 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

  10. '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.

  11. 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

  12. The surface latent heat flux anomalies related to major earthquake

    NASA Astrophysics Data System (ADS)

    Jing, Feng; Shen, Xuhui; Kang, Chunli; Xiong, Pan; Hong, Shunying

    2011-12-01

    SLHF (Surface Latent Heat Flux) is an atmospheric parameter, which can describe the heat released by phase changes and dependent on meteorological parameters such as surface temperature, relative humidity, wind speed etc. There is a sharp difference between the ocean surface and the land surface. Recently, many studies related to the SLHF anomalies prior to earthquakes have been developed. It has been shown that the energy exchange enhanced between coastal surface and atmosphere prior to earthquakes can increase the rate of the water-heat exchange, which will lead to an obviously increases in SLHF. In this paper, two earthquakes in 2010 (Haiti earthquake and southwest of Sumatra in Indonesia earthquake) have been analyzed using SLHF data by STD (standard deviation) threshold method. It is shows that the SLHF anomaly may occur in interpolate earthquakes or intraplate earthquakes and coastal earthquakes or island earthquakes. And the SLHF anomalies usually appear 5-6 days prior to an earthquake, then disappear quickly after the event. The process of anomaly evolution to a certain extent reflects a dynamic energy change process about earthquake preparation, that is, weak-strong-weak-disappeared.

  13. 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.

  14. 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.

  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. Residential Variable-Capacity Heat Pumps Sized to Heating Loads

    SciTech Connect

    Munk, Jeffrey D.; Jackson, Roderick K.; Odukomaiya, Adewale; Gehl, Anthony C.

    2014-01-01

    Variable capacity heat pumps are an emerging technology offering significant energy savings potential and improved efficiency. With conventional single-speed systems, it is important to appropriately size heat pumps for the cooling load as over-sizing would result in cycling and insufficient latent capacity required for humidity control. These appropriately sized systems are often under-sized for the heating load and require inefficient supplemental electric resistance heat to meet the heating demand. Variable capacity heat pumps address these shortcomings by providing an opportunity to intentionally size systems for the dominant heating season load without adverse effects of cycling or insufficient dehumidification in the cooling season. This intentionally-sized system could result in significant energy savings in the heating season, as the need for inefficient supplemental electric resistance heat is drastically reduced. This is a continuation of a study evaluating the energy consumption of variable capacity heat pumps installed in two unoccupied research homes in Farragut, a suburb of Knoxville, Tennessee. In this particular study, space conditioning systems are intentionally sized for the heating season loads to provide an opportunity to understand and evaluate the impact this would have on electric resistance heat use and dehumidification. The results and conclusions drawn through this research are valid and specific for portions of the Southeastern and Midwestern United States falling in the mixed-humid climate zone. While other regions in the U.S. do not experience this type of climate, this work provides a basis for, and can help understand the implications of other climate zones on residential space conditioning energy consumption. The data presented here will provide a framework for fine tuning residential building EnergyPlus models that are being developed.

  17. 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.

  18. CTS TEP thermal anomalies: Heat pipe system performance

    NASA Technical Reports Server (NTRS)

    Marcus, B. D.

    1977-01-01

    A part of the investigation is summarized of the thermal anomalies of the transmitter experiment package (TEP) on the Communications Technology Satellite (CTS) which were observed on four occasions in 1977. Specifically, the possible failure modes of the variable conductance heat pipe system (VCHPS) used for principal thermal control of the high-power traveling wave tube in the TEP are considered. Further, the investigation examines how those malfunctions may have given rise to the TEP thermal anomalies. Using CTS flight data information, ground test results, analysis conclusions, and other relevant information, the investigation concentrated on artery depriming as the most likely VCHPS failure mode. Included in the study as possible depriming mechanisms were freezing of the working fluid, Marangoni flow, and gas evolution within the arteries. The report concludes that while depriming of the heat pipe arteries is consistent with the bulk of the observed data, the factors which cause the arteries to deprime have yet to be identified.

  19. Specific Heat Anomalies in Solids Described by a Multilevel Model

    NASA Astrophysics Data System (ADS)

    Souza, Mariano de; Paupitz, Ricardo; Seridonio, Antonio; Lagos, Roberto E.

    2016-04-01

    In the field of condensed matter physics, specific heat measurements can be considered as a pivotal experimental technique for characterizing the fundamental excitations involved in a certain phase transition. Indeed, phase transitions involving spin (de Souza et al. Phys. B Condens. Matter 404, 494 (2009) and Manna et al. Phys. Rev. Lett. 104, 016403 (2010)), charge (Pregelj et al. Phys. Rev. B 82, 144438 (2010)), lattice (Jesche et al. Phys. Rev. B 81, 134525 (2010)) (phonons) and orbital degrees of freedom, the interplay between ferromagnetism and superconductivity (Jesche et al. Phys. Rev. B 86, 020501 (2012)), Schottky-like anomalies in doped compounds (Lagos et al. Phys. C Supercond. 309, 170 (1998)), electronic levels in finite correlated systems (Macedo and Lagos J. Magn. Magn. Mater. 226, 105 (2001)), among other features, can be captured by means of high-resolution calorimetry. Furthermore, the entropy change associated with a first-order phase transition, no matter its nature, can be directly obtained upon integrating the specific heat over T, i.e., C( T)/ T, in the temperature range of interest. Here, we report on a detailed analysis of the two-peak specific heat anomalies observed in several materials. Employing a simple multilevel model, varying the spacing between the energy levels Δ i = ( E i - E 0) and the degeneracy of each energy level g i , we derive the required conditions for the appearance of such anomalies. Our findings indicate that a ratio of {Δ }2/{Δ }1thickapprox 10 between the energy levels and a high degeneracy of one of the energy levels define the two-peaks regime in the specific heat. Our approach accurately matches recent experimental results. Furthermore, using a mean-field approach, we calculate the specific heat of a degenerate Schottky-like system undergoing a ferromagnetic (FM) phase transition. Our results reveal that as the degeneracy is increased the Schottky maximum in the specific heat becomes narrow while the peak

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Anomalies.

    ERIC Educational Resources Information Center

    Online-Offline, 1999

    1999-01-01

    This theme issue on anomalies includes Web sites, CD-ROMs and software, videos, books, and additional resources for elementary and junior high school students. Pertinent activities are suggested, and sidebars discuss UFOs, animal anomalies, and anomalies from nature; and resources covering unexplained phenonmenas like crop circles, Easter Island,…

  5. 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.

  6. 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.

  7. High capacity heat pipe performance demonstration

    NASA Technical Reports Server (NTRS)

    1983-01-01

    A high capacity heat pipe which will operate in one-g and in zero-g is investigated. An artery configuration which is self-priming in one-g was emphasized. Two artery modifications were evolved as candidates to achieve one-g priming and will provide the very high performance: the four artery and the eight artery configurations. These were each evaluated analytically for performance and priming capability. The eight artery configuration was found to be inadequate from a performance standpoint. The four artery showed promise of working. A five-inch long priming element test article was fabricated using the four artery design. Plexiglas viewing windows were made on each end of the heat pipe to permit viewing of the priming activity. The five-inch primary element would not successfully prime in one-g. Difficulties on priming in one-g raised questions about zero-g priming. Therefore a small test element heat pipe for verifying that the proposed configuration will self-prime in zero-g was fabricated and delivered.

  8. Entropic anomaly and maximal efficiency of microscopic heat engines.

    PubMed

    Bo, Stefano; Celani, Antonio

    2013-05-01

    The efficiency of microscopic heat engines in a thermally heterogenous environment is considered. We show that-as a consequence of the recently discovered entropic anomaly-quasistatic engines, whose efficiency is maximal in a fluid at uniform temperature, have in fact vanishing efficiency in the presence of temperature gradients. For slow cycles the efficiency falls off as the inverse of the period. The maximum efficiency is reached at a finite value of the cycle period that is inversely proportional to the square root of the gradient intensity. The relative loss in maximal efficiency with respect to the thermally homogeneous case grows as the square root of the gradient. As an illustration of these general results, we construct an explicit, analytically solvable example of a Carnot stochastic engine. In this thought experiment, a Brownian particle is confined by a harmonic trap and immersed in a fluid with a linear temperature profile. This example may serve as a template for the design of real experiments in which the effect of the entropic anomaly can be measured. PMID:23767467

  9. 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.

  10. High-Capacity Heat-Pipe Evaporator

    NASA Technical Reports Server (NTRS)

    Oren, J. A.; Duschatko, R. J.; Voss, F. E.; Sauer, L. W.

    1989-01-01

    Heat pipe with cylindrical heat-input surface has higher contact thermal conductance than one with usual flat surface. Cylindrical heat absorber promotes nearly uniform flow of heat into pipe at all places around periphery of pipe, helps eliminate hotspots on heat source. Lugs in aluminum pipe carry heat from outer surface to liquid oozing from capillaries of wick. Liquid absorbs heat, evaporates, and passes out of evaporator through interlug passages.

  11. Heat kernel for Newton-Cartan trace anomalies

    NASA Astrophysics Data System (ADS)

    Auzzi, Roberto; Nardelli, Giuseppe

    2016-07-01

    We compute the leading part of the trace anomaly for a free non-relativistic scalar in 2 + 1 dimensions coupled to a background Newton-Cartan metric. The anomaly is proportional to 1 /m, where m is the mass of the scalar. We comment on the implications of a conjectured a-theorem for non-relativistic theories with boost invariance.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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)

  20. 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)

  1. 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.

  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. 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.

  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. 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

  7. Specific heat and transport {open_quotes}anomalies{close_quotes} in mixed alkali glasses

    SciTech Connect

    Green, P.F.; Brow, R.K.; Hudgens, J.J.

    1998-11-01

    We show that changes in the relative mole fractions of Li{sub 2}O and Na{sub 2}O in alkali metaphosphate glasses lead to {open_quotes}anomalies{close_quotes} in the specific heat and structural relaxations. The heat capacity change between the liquid and glassy states, {Delta}c{sub p}(T{sub g}), at the calorimetric glass transition temperature, T{sub g}, exhibits a minimum when the mole fractions of Li{sub 2}O and Na{sub 2}O are comparable. Moreover, systematic changes in the temperature dependence of the viscosity, {eta}, i.e., changes in the {open_quotes}fragility{close_quotes} of the system, accompany these changes in mole fraction. This observed dependence of the {open_quotes}fragility{close_quotes} on the mixed alkali ion composition occurs in the absence of apparent changes in the covalent network connectivity which normally accounts for this behavior in glasses. {copyright} {ital 1998 American Institute of Physics.}

  8. 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.

  9. 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.

  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. SU(2)L-TRIPLET Dark Matter and Heat Anomaly in Cosmic Positron Experiment

    NASA Astrophysics Data System (ADS)

    Matsumoto, Shigeki; Hisano, Junji; Saito, Osamu; Senami, Masato

    2007-03-01

    Recently the HEAT collaboration has been reported the anomaly about the positron excess in the comic ray. The anomaly attracts attention because it may originate in the dark matter annihilation in the galactic halo. In this letter, I would like to address about the interesting fact that the SU(2)L-triplet dark matter can explain the anomaly with satisfying the present dark matter abundance observed by WMAP. When the mass of the dark matter is around 2 TeV, which is favored from the thermal relic abundance, the non-perturbation effect significantly enhances the annihilation cross section into positrons in the non-relativistic limit. We show that the effect enables us to account for the HEAT anomaly.

  12. 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

  13. Reductions in labour capacity from heat stress under climate warming

    NASA Astrophysics Data System (ADS)

    Dunne, John P.; Stouffer, Ronald J.; John, Jasmin G.

    2013-06-01

    A fundamental aspect of greenhouse-gas-induced warming is a global-scale increase in absolute humidity. Under continued warming, this response has been shown to pose increasingly severe limitations on human activity in tropical and mid-latitudes during peak months of heat stress. One heat-stress metric with broad occupational health applications is wet-bulb globe temperature. We combine wet-bulb globe temperatures from global climate historical reanalysis and Earth System Model (ESM2M) projections with industrial and military guidelines for an acclimated individual's occupational capacity to safely perform sustained labour under environmental heat stress (labour capacity)--here defined as a global population-weighted metric temporally fixed at the 2010 distribution. We estimate that environmental heat stress has reduced labour capacity to 90% in peak months over the past few decades. ESM2M projects labour capacity reduction to 80% in peak months by 2050. Under the highest scenario considered (Representative Concentration Pathway 8.5), ESM2M projects labour capacity reduction to less than 40% by 2200 in peak months, with most tropical and mid-latitudes experiencing extreme climatological heat stress. Uncertainties and caveats associated with these projections include climate sensitivity, climate warming patterns, CO2 emissions, future population distributions, and technological and societal change.

  14. 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.

  15. 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.

  16. 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

  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. Heat flow anomalies in oil- and gas-bearing structures

    SciTech Connect

    Sergiyenko, S.I.

    1988-02-01

    The main features of the distribution of heat flow values in oil, gas and gas-condensate fields on the continents have been discussed by Makarenko and Sergiyenko. The method of analysis used made it possible to establish that the presence of hydrocarbons in formations leads to high heat-flow, regardless of the age of folding of the potentially oil- and gas-bearing zones. Only in regions adjacent to marginal Cenozoic folded mountain structures and in zones of Cenozoic volcanism is the world average higher, by 2.5 to 10%, than in the oil- and gas-bearing structures in those regions. The earlier analysis of the distribution of heat flow values in oil and gas structures was based on 403 measurements. The author now has nearly doubled the sample population, enabling him substantially to revise the ideas on the distribution of heat flow values and the development of the thermal regime of local oil and gas structures. He notes that the method previously used, comparing heat flow values on young continental platforms with values in local oil and gas structures, makes it possible to estimate the thermal effect of the presence of oil and gas. This conclusion stems from the fact that the overwhelming majority of heat flow measurements were made on various kinds of positive structural forms, and distortions of the thermal field caused by thermal anisotropy phenomena are equally characteristic of both productive and nonproductive structures. As a result, for the first time a continuous time series of heat flow measurements over oil and gas structures in various tectonic regions, with ages of consolidation ranging from the Precambrian to the Cenozoic, was established. 26 references.

  19. 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.

  20. Development of a high capacity variable conductance heat pipe.

    NASA Technical Reports Server (NTRS)

    Kosson, R.; Hembach, R.; Edelstein, F.; Loose, J.

    1973-01-01

    The high-capacity, pressure-primed, tunnel-artery wick concept was used in a gas-controlled variable conductance heat pipe. A variety of techniques were employed to control the size of gas/vapor bubbles trapped within the artery. Successful operation was attained with a nominal 6-foot long, 1-inch diameter cold reservoir VCHP using ammonia working fluid and nitrogen control gas. The pipe contained a heat exchanger to subcool the liquid in the artery. Maximum transport capacity with a 46-inch effective length was 1200 watts level (more than 50,000 watt-inches) and 800 watts at 0.5-inch adverse tilt.

  1. 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.

  2. High capacity demonstration of honeycomb panel heat pipes

    NASA Technical Reports Server (NTRS)

    Tanzer, H. J.; Cerza, M. R., Jr.; Hall, J. B.

    1986-01-01

    High capacity honeycomb panel heat pipes were investigated as heat rejection radiators on future space platforms. Starting with a remnant section of honeycomb panel measuring 3.05-m long by 0.127-m wide that was originally designed and built for high-efficiency radiator fins, features were added to increase thermal transport capacity and thus permit test evaluation as an integral heat transport and rejection radiator. A series of subscale panels were fabricated and reworked to isolate individual enhancement features. Key to the enhancement was the addition of a liquid sideflow that utilizes pressure priming. A prediction model was developed and correlated with measured data, and then used to project performance to large, space-station size radiators. Results show that a honeycomb panel with 5.08-cm sideflow spacing and core modification will meet the design load of a 50 kW space heat rejection system.

  3. High thermal-transport capacity heat pipes for space radiators

    NASA Technical Reports Server (NTRS)

    Carlson, Albert W.; Gustafson, Eric; Roukis, Susan L.

    1987-01-01

    This paper presents the results of performance tests of several dual-slot heat pipe test articles. The dual-slot configuration has a very high thermal transport capability and has been identified as a very promising candidate for the radiator system for the NASA Space Station solar dynamic power modules. Two six-foot long aluminum heat pipes were built and tested with ammonia and acetone. A 20-ft long heat pipe was also built and tested with ammonia. The test results have been compared with performance predictions. A thermal transport capacity of 2000 W at an adverse tilt of 1 in. and a 1000 W capacity at an adverse tilt of 2 in. were achieved on the 20-ft long heat pipe. These values are in close agreement with the predicted performance limits.

  4. Modeling the surface heat flux response to long-lived SST anomalies in the North Atlantic

    SciTech Connect

    Power, S.B.; Kleeman, R.; Colman, R.A.

    1995-09-01

    An atmospheric general circulation model (AGCM), a simplified atmospheric model (SAM) of surface heat flux, and various idealized analytic models have been used to investigate the atmospheric response over the North Atlantic to SST anomalies, including a general cooling associated with a weakened thermohaline circulation. Latent heating dominates the surface heat flux response, while sensible heating plays an important secondary role. The total heat flux response is weaker than presumed in recent studies using ocean models under highly idealized surface boundary conditions. This implies that stability of the thermohaline circulation to high-latitude freshening in more sophisticated coupled systems (that incorporate either AGCMs or models like SAM) will be increased. All three kinds of atmospheric models exhibit nonrestorative behavior away from the anomaly peak that is primarily associated with the advection of cooled air eastward. This simple picture is complicated in the AGCM by the fact that the winds weaken over the SST anomaly, which helps to moderate the response. Analytic models for atmospheric temperature forced using imposed surface temperature anomalies highlight conditions under which a nonrestorative response can arise. Previous work has shown that the length scale of spatially periodic anomalies partially determines the magnitude of the response in a diffusive atmosphere. Here the authors show that this scale dependence has much wider applicability by considering more localized anomalies and by the inclusion of advective transport processes. The modification of the response by sea ice changes and the absence of any statistically significant change in the basin-averaged hydrological cycle are also discussed. 62 refs., 19 figs.

  5. 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.

  6. 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.

  7. 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…

  8. 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

  9. First results of MT studies at the Northern Swiss heat flow anomaly

    NASA Astrophysics Data System (ADS)

    Shah, Neeraj; Samrock, Friedemann; Saar, Martin O.

    2016-04-01

    The North of Switzerland hosts a prominent heat flow anomaly, where the observed surface heat flux exceeds the Swiss average by a factor of two. The anomaly is situated within the permo-carboniferous trough and one hypothesis about its origin is that geothermal fluids migrate upwards along permeable pathways, carrying heat from the crystalline basement into shallower layers. We will present first results of a magnetotelluric (MT) survey covering the extent of the anomaly over the permo-carboniferous trough. The aim of the field measurements is to recover a 3-D resistivity model in order to gain insight into the geometry of the permo-carboniferous trough and permeable structures within it and the crystalline basement. The results would provide important information about the nature and origin of the observed heat flow anomaly. It is known that MT in Switzerland can be challenging due to noise problems that arise from power-lines and local infrastructure. We will test different processing methods using multiple remote reference sites and discuss the feasibility of natural source electromagnetic measurements in this region. Besides the impedance tensor, which is the standard MT response, we estimate and evaluate the quality of recently introduced inter-site phase tensors, which are free of galvanic distortion effects such as static shifts.

  10. 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.

  11. 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.

  12. 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.

  13. Working Fluids for Increasing Capacities of Heat Pipes

    NASA Technical Reports Server (NTRS)

    Chao, David F.; Zhang, Nengli

    2004-01-01

    A theoretical and experimental investigation has shown that the capacities of heat pipes can be increased through suitable reformulation of their working fluids. The surface tensions of all of the working fluids heretofore used in heat pipes decrease with temperature. As explained in more detail below, the limits on the performance of a heat pipe are associated with the decrease in the surface tension of the working fluid with temperature, and so one can enhance performance by reformulating the working fluid so that its surface tension increases with temperature. This improvement is applicable to almost any kind of heat pipe in almost any environment. The heat-transfer capacity of a heat pipe in its normal operating-temperature range is subject to a capillary limit and a boiling limit. Both of these limits are associated with the temperature dependence of surface tension of the working fluid. In the case of a traditional working fluid, the decrease in surface tension with temperature causes a body of the liquid phase of the working fluid to move toward a region of lower temperature, thus preventing the desired spreading of the liquid in the heated portion of the heat pipe. As a result, the available capillary-pressure pumping head decreases as the temperature of the evaporator end of the heat pipe increases, and operation becomes unstable. Water has widely been used as a working fluid in heat pipes. Because the surface tension of water decreases with increasing temperature, the heat loads and other aspects of performance of heat pipes that contain water are limited. Dilute aqueous solutions of long-chain alcohols have shown promise as substitutes for water that can offer improved performance, because these solutions exhibit unusual surface-tension characteristics: Experiments have shown that in the cases of an aqueous solution of an alcohol, the molecules of which contain chains of more than four carbon atoms, the surface tension increases with temperature when the

  14. A unified approach to trace surface heat and cold events by using height anomaly

    NASA Astrophysics Data System (ADS)

    Qian, Weihong; Yu, Tiantian; Du, Jun

    2016-03-01

    After decomposing an atmospheric field into climatic and anomalous components, a maximum height anomaly (MHA) in upper troposphere is found to be closely associated with surface anomalous temperature episodes. Thus, a unified method has been proposed to trace both heat and cold events as well as surface temperature anomalies through the following four aspects of this study. (1) First, a global daily MHA database from 1980 to 2010 is derived and its long-term variation is analyzed. (2) The general relationship between surface air temperature anomaly (SATA) and MHA is then studied. Following the hydrostatic balance, positive (negative) MHA center often corresponds well to positive (negative) SATA or heat (cold) event. (3) Potential capability of using MHA signal to extend predictability of SATA events is further examined. It is found that signals in MHA are stronger and appear earlier than that in temperature field. Positive or negative MHA centers can often be traced 9 days ahead on average for many SATA events. The earliest MHA signal to indicate a heat (cold) event can be traced 20 (26) days back in an upstream region. (4) Some challenges in applying MHA to early warning SATA events are discussed, mainly from the irregularity of MHA tracks, the location uncertainty of downward extension of upper air temperature anomaly including missing and false alarm issue, and the inability in quantifying intensity. Therefore, the forecast capability of MHA signal will strongly depend on the quality of an operational model forecasts.

  15. 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.

  16. 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

  17. Effect of Heat Leak and Finite Thermal Capacity on the Optimal Configuration of a Two-Heat-Reservoir Heat Engine for Another Linear Heat Transfer Law

    NASA Astrophysics Data System (ADS)

    Zheng, Tong; Chen, Lingen; Sun, Fengrui; Wu, Chih

    2003-12-01

    Based on a model of a two-heat-reservoir heat engine with a finite high-temperature source and bypass heat leak, the optimal configuration of the cycle is found for the fixed cycle period with another linear heat transfer law . The finite thermal capacity source without heat leak makes the configuration of the cycle to a class of generalized Carnot cycle. The configuration of the cycle with heat leak and finite thermal capacity source is different from others.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. Heat Transfer Capacity of Lotus-Type Porous Copper Heat Sink

    NASA Astrophysics Data System (ADS)

    Chiba, Hiroshi; Ogushi, Tetsuro; Nakajima, Hideo; Ikeda, Teruyuki

    Lotus-type porous copper is a form of copper that includes many straight pores, which are produced by the precipitation of supersaturated gas dissolved in the molten metal during solidification. The lotus-type porous copper is attractive as a heat sink because a higher heat transfer capacity is obtained as the pore diameter decreases. We investigate a fin model for predicting the heat transfer capacity of the lotus-type porous copper. Its heat transfer capacity is verified to be predictable via the straight fin model, in which heat conduction in the porous metal and the heat transfer to the fluid in the pores are taken into consideration by comparison with a numerical analysis. We both experimentally and analytically determine the heat transfer capacities of three types of heat sink: with conventional groove fins, with groove fins that have a smaller fin gap (micro-channels) and with lotus-type porous copper fins. The conventional groove fins have a fin gap of 3mm and a fin thickness of 1mm, the micro-channels have a fin gap of 0.5mm and a fin thickness of 0.5mm, and the lotus-type porous copper fins have pores with a diameter of 0.3mm and a porosity of 0.39. The lotus-type porous copper fins were found to have a heat transfer capacity 4 times greater than the conventional groove fins and 1.3 times greater than the micro-channel heat sink under the same pumping power.

  4. 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.

  5. High capacity demonstration of honeycomb panel heat pipes

    NASA Technical Reports Server (NTRS)

    Tanzer, H. J.

    1989-01-01

    The feasibility of performance enhancing the sandwich panel heat pipe was investigated for moderate temperature range heat rejection radiators on future-high-power spacecraft. The hardware development program consisted of performance prediction modeling, fabrication, ground test, and data correlation. Using available sandwich panel materials, a series of subscale test panels were augumented with high-capacity sideflow and temperature control variable conductance features, and test evaluated for correlation with performance prediction codes. Using the correlated prediction model, a 50-kW full size radiator was defined using methanol working fluid and closely spaced sideflows. A new concept called the hybrid radiator individually optimizes heat pipe components. A 2.44-m long hybrid test vehicle demonstrated proof-of-principle performance.

  6. 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

  7. 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

  8. 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.

  9. On the interaction of surface heating anomalies with zonally symmetric and asymmetric atmospheric flows

    NASA Technical Reports Server (NTRS)

    Phillips, T. J.

    1982-01-01

    Models of intermediate complexity have been used to study some aspects of the climatic effects of anomalous heating, but many aspects of the problem have yet to be explored thoroughly. The present study represents a preliminary investigated of the gaps in scientific understanding of the interaction of heating and atmospheric dynamics. The principle research tool is a model of intermediate complexity, including a time-dependent, nonlinear-two-layer quasi-geostrophic model of relatively high horizontal resolution which incorporates simple heating parameterizations. The model is used to examine systematically the interaction of heating arising from anomalies in surface temperature with zonally symmetric and zonally asymmetric flows characterized by different values of static stability and mean vertical wind shear.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. The Effect of Tropical Atlantic Heating Anomalies upon GCM Rain Forecasts over the Americas.

    NASA Astrophysics Data System (ADS)

    Buchmann, Julio; Paegle, Jan; Buja, Lawrence E.; Dickinson, Robert E.

    1990-02-01

    Severe droughts occurred over eastern sections of North America and central sections of South America in 1986 and 1988. We summarize data suggesting that both periods were characterized by above-normal tropical Atlantic sea surface temperatures and convection, and investigate the response of a general circulation model to positive heating anomalies in the tropical Atlantic sector. An eight-case control ensemble of 30 day global predictions is made starting from the atmospheric state observed on 1 January of each year from 1977 through 1984. The same eight cases are integrated in a second experimental ensemble that is identical to the first control ensemble, except that a heating term is added to the thermodynamic equation in a region centered at 30°W, 6.6°N. This is intended to simulate the latent heating of enhanced tropical Atlantic convection. The third ensemble is identical to the second, except the heating is centered at 6.6°S.Both heated ensembles produce reductions of forecast precipitation over most of North and South America, but these appear to have greater statistical significance over North America. Here the greatest precipitation reductions are forecast over the southern and eastern United States, and this response does not change substantially between the two experiments. The South American response is more sensitive to the placement of the heating anomaly. When the anomaly is located north of the equator, drying occurs over northeast Brazil; meanwhile this region receives increased rainfall when the anomaly is located south of the equator. Both experiment ensembles display a region of reduced rainfall over the Andes Mountains, and over southern portions of Brazil. However, only the former region is statistically significant above the 95% confidence level. The present usage of real initial data and an ensemble of cases permits us to draw quantitatively meaningful estimates of the time scale of response and case-to-case variability. For presently

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Numerical simulation of Tibetan Plateau heating anomaly influence on westerly jet in spring

    NASA Astrophysics Data System (ADS)

    Xinzhou, Li; Xiaodong, Liu

    2015-12-01

    The intensity and location of the westerly jet (WJ) in the mid-latitudes of the Northern Hemisphere has been closely related to weather and climate changes in Eurasia. In this paper, we analyzed the seasonal and inter-annual variations in the strength and position of the WJ, using the NCEP-DOE reanalysis II (NCEP) data. Spring is the period that the Tibetan Plateau (TP) transits from a cold to a warm condition, and at the same time the WJ weakens and moves northward. Correlation analysis showed that the westerly wind over the north (south) of the TP has a significant positive (negative) correlation with the TP surface temperature in spring during 1979-2013 (99.9% significance level). In spring, surface sensible heat release dominates thermal conditions of the TP, while the contribution of latent heat becomes important in summer. We conducted three numerical experiments to determine the effects of the TP surface sensible heat flux anomaly in spring on the intensity and location of the WJ using the community atmosphere model 5 (CAM5). Experimental results indicated that changing the TP surface sensible heat flux can produce changes in the TP heat sources. When the TP sensible heat flux is switched off (TPSHL), the TP surface has a lower temperature and no longer heats up the middle and upper troposphere, and leads to a maximum cooling of -1.2∘C at 200 hPa over the TP with a significance level of 95%. In spring, the abnormal low temperature over the TP caused the WJ to strengthen and move southward compared with the control experiment (CTL), and this results in a westerly (easterly) wind anomaly over the south (north) of the TP with a significance level of 95%. We obtained the opposite conclusion from the comparison of the enhanced TP surface sensible heat flux (TPSHH) with CTL test results. In TPSHL, the WJ is still steadily located near 30∘N in May as well as April, i.e., the first northward jump occurs from May to June which is a delay of one month compared to

  5. NDVI anomalies associated with the European drought and heat wave of 2003

    NASA Astrophysics Data System (ADS)

    Bevan, Suzanne; Los, Sietse; North, Peter

    2013-04-01

    The European drought and heat wave of 2003 is commonly used as an example of extreme summer climate conditions that are likely to become more common towards the end of the 21st century, under predicted climate change scenarios. The extreme conditions are known to have had an impact on biomass primary productivity as reflected in remotely sensed vegetation indices and fAPAR, flux-tower measurements, and the results from a variety of modelling approaches. Early remote sensing analyses were based on relatively short time series of data, 4 or 5 years only. We are now able to make use of 12 years of MODIS observations to highlight the statistical significance of the widespread and persistent anomalies in vegetation greenness in 2003 compared with other summers so far this century. Anomalies in excess of 2 standard deviations initially occur at the start of June in central and eastern France. By the end of July they are common also over Germany, by mid August have spread to the French border with Spain, and by the end of August are common over the north-western corner of France, England and eastern Scotland. Using the One-Degree Daily resolution Global Precipitation Climatology Project precipitation data and European Re-Analysis Interim 2 m air temperatures we are able to show where and whether either precipitation or temperature has the greatest impact on summer vegetation greenness. With the exception of mountainous regions such as the Alps and northern and western parts of the United Kingdom, summer NDVI anomalies are highly correlated with precipitation anomalies of the preceding month. The picture for temperature is more geographically variable with summer NDVI anomalies in southern France, Italy and central England and north-eastern Scotland being negatively correlated with temperature, and northern and western coasts of France and Germany being positively correlated with temperature. In addition, we analyse the anomalies in conjunction with vegetation height from

  6. Testing of a high capacity research heat pipe

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Tests were performed on a high-capacity channel-wick heat pipe to assess the transport limitations of v-grooves and the effects of boiling. The results showed that transport can vary significantly (less than 50 W) under similar conditions and the continuous boiling was observed at power levels as low as 40 W. In addition, some evidence was found to support the predictions using a groove transport model which shows that transport increases with lower groove densities and longer evaporators. However, due to transport variations, these results were not consistent throughout the program. When a glass fiber wick was installed over the grooves, a relatively low transport level was achieved (80 to 140 W). Based on these results and the identification of some potential causes for them, several design suggestions were recommended for reducing the possibility of boiling and improving groove transport.

  7. 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.

  8. 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

  9. Transient response of a high-capacity heat pipe for Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Ambrose, J. H.; Holmes, H. R.

    1991-01-01

    High-capacity heat pipe radiator panels have been proposed as the primary means of heat rejection for Space Station Freedom. In this system, the heat pipe would interface with the thermal bus condensers. Changes in system heat load can produce large temperature and heat load variations in individual heat pipes. Heat pipes could be required to start from an initially cold state, with heat loads temporarily exceeding their low-temperature transport capacity. The present research was motivated by the need for accurate prediction of such transient operating conditions. In this work, the cold startup of a 6.7-meter long high-capacity heat pipe is investigated experimentally and analytically. A transient thermohydraulic model of the heat pipe was developed which allows simulation of partially-primed operation. The results of cold startup tests using both constant temperature and constant heat flux evaporator boundary conditions are shown to be in good agreement with predicted transient response.

  10. Wintertime response of mid-latitude atmospheric circulation to heat anomalies in the Barents Sea in recent decades

    NASA Astrophysics Data System (ADS)

    Schlichtholz, Pawel

    2015-04-01

    Prospects for seasonal prediction of climate variability depend on the strength of feedbacks between different components of the climate system. Sources for seasonal predictability of surface atmospheric anomalies in middle latitudes have been previously sought in teleconnections to the tropical phenomenon of El-Niño-Southern Oscillation and among various extratropical drivers including sea surface temperature anomalies, Arctic sea ice cover extremes, continental snow variability and tropospheric-stratospheric interactions. However, impacts of extratropical subsurface ocean variability on atmospheric teleconnections are poorly known. Here we use a lagged regression analysis between an index of the observed summertime Atlantic water temperature (AWT) anomalies at the entrance to the Barents Sea in the period 1982-2005 and the corresponding year-round data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis to show that subsurface oceanic heat anomalies heading the Arctic Ocean are significant precursors of wintertime atmospheric anomalies over mid-latitude Eurasia and North Pacific. In particular, warm AWT anomalies precede an Arctic warming accompanied by a cooling over Eurasia. The summertime oceanic anomalies explain about 40% of the variance in the surface air temperature averaged over entire Eurasia from 35° to 45° N and 50% of the variance in surface winds over the Far East Asia in the following winter. We find that the remote tropospheric response arises from modification of planetary waves and interaction of mean winds with synoptic eddies leading to a reorganization of the mid-latitude storm tracks. The AWT anomalies explain about 60% of the variance in the upper-tropospheric storm track activity averaged over the Pacific and Eurasia from 35° to 55° N and in the lower-tropospheric poleward transient eddy heat flux over western Eurasia. Finally, we show that the tropospheric response to

  11. 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.

  12. Extreme Heat Wave over European Russia in Summer 2010: Anomaly or a Manifestation of Climatic Trend?

    NASA Astrophysics Data System (ADS)

    Razuvaev, V.; Groisman, P. Y.; Bulygina, O.; Borzenkova, I.

    2010-12-01

    Extraordinary temperature anomalies over European Russia (ER) in summer 2010 raised a legitimate question in the title of this presentation. A 60-days-long hot anticyclonic weather system with daily temperature anomalies as high as +10K and no or negligible amount of rainfall first decimated crops in the forest-steppe zone of ER, gradually dried wetlands in the forest zone and, finally, caused numerous natural and anthropogenic fires that at the time of this abstract preparation have not yet been extinguished. The extreme heat, lack of precipitation, and forest fires have caused hundreds of deaths and multimillion dollars in property losses. Indirect losses of lives due to this weather anomaly, with the ensuing fires and related air pollution, as well as the absence of air conditioning in apartments has yet to be estimated. The center of European Russia was well covered by meteorological observations for the past 130 years. These data, historical weather records (yearbooks or "letopisi" , which were carried on in the major Russian monasteries), and finally, dendroclimatological information, all show that this summer temperature anomaly was well above all known extremes in the past 1000 years. Like ocean waves and ocean tides, weather and climate variability go together strengthening (or mitigating) each other. We shall show the precursors of the current outbreak using principally the most accurate meteorological records of the past century updated to 2009 (at the Session, the 2010 data will also be presented). While a careful analyses of these records and thoughtful analyses of recent similar temperature outbreaks in Western Europe could not prevent the occurrence of this disaster, the lessons learned from these analyses (a) would warn about its increasing probability and (b) mitigation and adaptation measures could well be made to reduce its negative consequences. Among our arguments are: (1)There is a century-long tendency of reduction of equator minus pole

  13. 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.

  14. Droplet Evaporator For High-Capacity Heat Transfer

    NASA Technical Reports Server (NTRS)

    Valenzuela, Javier A.

    1993-01-01

    Proposed heat-exchange scheme boosts heat transfer per unit area. Key component is generator that fires uniform size droplets of subcooled liquid at hot plate. On impact, droplets spread out and evaporate almost instantly, removing heat from plate. In practice, many generator nozzles arrayed over evaporator plate.

  15. 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.

  16. 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).

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Summer precipitation anomalies in Asia and North America induced by Eurasian non-monsoon land heating versus ENSO

    PubMed Central

    Zhao, Ping; Wang, Bin; Liu, Jiping; Zhou, Xiuji; Chen, Junming; Nan, Sulan; Liu, Ge; Xiao, Dong

    2016-01-01

    When floods ravage Asian monsoon regions in summer, megadroughts often attack extratropical North America, which feature an intercontinental contrasting precipitation anomaly between Asia and North America. However, the characteristics of the contrasting Asian-North American (CANA) precipitation anomalies and associated mechanisms have not been investigated specifically. In this article, we firmly establish this summer CANA pattern, providing evidence for a significant effect of the land surface thermal forcing over Eurasian non-monsoon regions on the CANA precipitation anomalies by observations and numerical experiments. We show that the origin of the CANA precipitation anomalies and associated anomalous anticyclones over the subtropical North Pacific and Atlantic has a deeper root in Eurasian non-monsoon land surface heating than in North American land surface heating. The ocean forcing from the ENSO is secondary and tends to be confined in the tropics. Our results have strong implications to interpretation of the feedback of global warming on hydrological cycle over Asia and North America. Under the projected global warming due to the anthropogenic forcing, the prominent surface warming over Eurasian non-monsoon regions is a robust feature which, through the mechanism discussed here, would favor a precipitation increase over Asian monsoon regions and a precipitation decrease over extratropical North America. PMID:26916258

  5. Summer precipitation anomalies in Asia and North America induced by Eurasian non-monsoon land heating versus ENSO.

    PubMed

    Zhao, Ping; Wang, Bin; Liu, Jiping; Zhou, Xiuji; Chen, Junming; Nan, Sulan; Liu, Ge; Xiao, Dong

    2016-01-01

    When floods ravage Asian monsoon regions in summer, megadroughts often attack extratropical North America, which feature an intercontinental contrasting precipitation anomaly between Asia and North America. However, the characteristics of the contrasting Asian-North American (CANA) precipitation anomalies and associated mechanisms have not been investigated specifically. In this article, we firmly establish this summer CANA pattern, providing evidence for a significant effect of the land surface thermal forcing over Eurasian non-monsoon regions on the CANA precipitation anomalies by observations and numerical experiments. We show that the origin of the CANA precipitation anomalies and associated anomalous anticyclones over the subtropical North Pacific and Atlantic has a deeper root in Eurasian non-monsoon land surface heating than in North American land surface heating. The ocean forcing from the ENSO is secondary and tends to be confined in the tropics. Our results have strong implications to interpretation of the feedback of global warming on hydrological cycle over Asia and North America. Under the projected global warming due to the anthropogenic forcing, the prominent surface warming over Eurasian non-monsoon regions is a robust feature which, through the mechanism discussed here, would favor a precipitation increase over Asian monsoon regions and a precipitation decrease over extratropical North America. PMID:26916258

  6. Summer precipitation anomalies in Asia and North America induced by Eurasian non-monsoon land heating versus ENSO

    NASA Astrophysics Data System (ADS)

    Zhao, Ping; Wang, Bin; Liu, Jiping; Zhou, Xiuji; Chen, Junming; Nan, Sulan; Liu, Ge; Xiao, Dong

    2016-02-01

    When floods ravage Asian monsoon regions in summer, megadroughts often attack extratropical North America, which feature an intercontinental contrasting precipitation anomaly between Asia and North America. However, the characteristics of the contrasting Asian-North American (CANA) precipitation anomalies and associated mechanisms have not been investigated specifically. In this article, we firmly establish this summer CANA pattern, providing evidence for a significant effect of the land surface thermal forcing over Eurasian non-monsoon regions on the CANA precipitation anomalies by observations and numerical experiments. We show that the origin of the CANA precipitation anomalies and associated anomalous anticyclones over the subtropical North Pacific and Atlantic has a deeper root in Eurasian non-monsoon land surface heating than in North American land surface heating. The ocean forcing from the ENSO is secondary and tends to be confined in the tropics. Our results have strong implications to interpretation of the feedback of global warming on hydrological cycle over Asia and North America. Under the projected global warming due to the anthropogenic forcing, the prominent surface warming over Eurasian non-monsoon regions is a robust feature which, through the mechanism discussed here, would favor a precipitation increase over Asian monsoon regions and a precipitation decrease over extratropical North America.

  7. Study of heating capacity of focused IR light soldering systems.

    PubMed

    Anguiano, C; Félix, M; Medel, A; Bravo, M; Salazar, D; Márquez, H

    2013-10-01

    An experimental study about four optical setups used for developing a Focused IR Light Soldering System (FILSS) for Surface Mount Technology (SMT) lead-free electronic devices specifically for Ball Grid Arrays (BGA) is presented. An analysis of irradiance and infrared thermography at BGA surface is presented, as well as heat transfer by radiation and conduction process from the surface of the BGA to the solder balls. The results of this work show that the heating provided by our proposed optical setups, measured at the BGA under soldering process, meets the high temperature and uniform thermal distribution requirements, which are defined by the reflow solder method for SMT devices. PMID:24104296

  8. 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.

  9. 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.

  10. 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.

  11. Millimeter Wave Detection of Localized Anomalies in the Space Shuttle External Fuel Tank Insulating Foam and Acreage Heat Tiles

    NASA Technical Reports Server (NTRS)

    Kharkovsky, S.; Case, J. T.; Zoughi, R.; Hepburn, F.

    2005-01-01

    The Space Shuttle Columbia's catastrophic accident emphasizes the growing need for developing and applying effective, robust and life-cycle oriented nondestructive testing (NDT) methods for inspecting the shuttle external fuel tank spray on foam insulation (SOFI) and its protective acreage heat tiles. Millimeter wave NDT techniques were one of the methods chosen for evaluating their potential for inspecting these structures. Several panels with embedded anomalies (mainly voids) were produced and tested for this purpose. Near-field and far-field millimeter wave NDT methods were used for producing millimeter wave images of the anomalies in SOFI panel and heat tiles. This paper presents the results of an investigation for the purpose of detecting localized anomalies in two SOFI panels and a set of heat tiles. To this end, reflectometers at a relatively wide range of frequencies (Ka-band (26.5 - 40 GHz) to W-band (75 - 110 GHz)) and utilizing different types of radiators were employed. The results clearly illustrate the utility of these methods for this purpose.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Evaluating transience of a potential geothermal heat flux anomaly beneath a tributary ice stream of Thwaites Glacier, West Antarctica

    NASA Astrophysics Data System (ADS)

    DeSanto, J. B.; Blankenship, D. D.; Young, D. A.; Lavier, L. L.; Choi, E.

    2012-12-01

    The Amundsen Sea Embayment of the West Antarctic ice sheet (WAIS) is currently one of the most rapidly changing sectors of a continental ice sheet. As a marine ice sheet, the WAIS is in a potentially unstable configuration. In addition to known active volcanoes such as Mt. Takahe and Mt. Murphy, subglacial volcanic activity has been identified using ice layer drawdown anomalies. Drawdown anomalies are features identifiable by a characteristic radar signature and represent significant loss of basal ice. We identify several features with the geometry of drawdown anomalies in the Thwaites Glacier along an ice stream tributary near Mt. Takahe. By modeling the flow of ice along the ice stream, we assess the hypothesis that these drawdown anomalies are a coherent feature caused by basal melt that is consistent with subglacial volcanic activity. The melt rate is then used to determine the spatial and temporal variations of geothermal heat flux in the region. We discuss these variations in the context of their geologic, morphologic and glaciologic setting and their implications for local volcanism and its impact on ice flow.

  20. Complementary impacts of the North Atlantic Oscillation and oceanic heat anomalies in the Nordic seas on the wintertime climate variability in middle latitudes

    NASA Astrophysics Data System (ADS)

    Schlichtholz, Pawel

    2016-04-01

    There is a growing evidence that Arctic sea ice anomalies influence mid-latitude weather and climate through coupled changes in the polar jet stream, planetary waves and storm tracks. In particular, the wintertime atmospheric conditions over Eurasia are sensitive to disturbances of sea ice cover in the Barents Sea. Our previous studies, based on a lagged regression analysis between oceanic observations and atmospheric (NCEP/NCAR) reanalysis data in the period 1982-2006, indicate that more than 70 % of the interannual variance of the total wintertime sea ice area in the Nordic (Greenland-Iceland-Norwegian and Barents) seas region can be explained by Atlantic water temperature (AWT) anomalies at the entrance to the Barents Sea in the preceding summer. When brought to the surface, oceanic heat anomalies influence not only the sea ice cover in the Nordic seas but also the local atmospheric conditions up to the tropopause level. The sea ice and atmospheric anomalies persist in winter because of a feedback between oceanically-driven wind anomalies and wind-driven AWT anomalies. A question is whether remote effects of sea ice anomalies in the Nordic seas are modulated by interannual variability in oceanic forcing. Here we show, using the same oceanic and atmospheric datasets as in the previous studies, that the summertime AWT anomalies are indeed significant precursors of a large-scale wintertime atmospheric variability. In particular, positive AWT anomalies precede predominantly westerly wind anomalies in high latitudes and easterly wind anomalies in middle latitudes. The mid-latitude wind anomalies, while being generally equivalent barotropic in the upper troposphere, have a strong low-level baroclinic contribution over Eurasia. The near-surface easterly wind anomalies in this area are locally deflected southward, maintaining cold spots near orography. As at the same time a strong warm anomaly is forced over the Barents and Greenland Seas, the lower

  1. 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.

  2. Southern Ocean air-sea heat flux, SST spatial anomalies, and implications for multi-decadal upper ocean heat content trends.

    NASA Astrophysics Data System (ADS)

    Tamsitt, V. M.; Talley, L. D.; Mazloff, M. R.

    2014-12-01

    The Southern Ocean displays a zonal dipole (wavenumber one) pattern in sea surface temperature (SST), with a cool zonal anomaly in the Atlantic and Indian sectors and a warm zonal anomaly in the Pacific sector, associated with the large northward excursion of the Malvinas and southeastward flow of the Antarctic Circumpolar Current (ACC). To the north of the cool Indian sector is the warm, narrow Agulhas Return Current (ARC). Air-sea heat flux is largely the inverse of this SST pattern, with ocean heat gain in the Atlantic/Indian, cooling in the southeastward-flowing ARC, and cooling in the Pacific, based on adjusted fluxes from the Southern Ocean State Estimate (SOSE), a ⅙° eddy permitting model constrained to all available in situ data. This heat flux pattern is dominated by turbulent heat loss from the ocean (latent and sensible), proportional to perturbations in the difference between SST and surface air temperature, which are maintained by ocean advection. Locally in the Indian sector, intense heat loss along the ARC is contrasted by ocean heat gain of 0.11 PW south of the ARC. The IPCC AR5 50 year depth-averaged 0-700 m temperature trend shows surprising similarities in its spatial pattern, with upper ocean warming in the ARC contrasted by cooling to the south. Using diagnosed heat budget terms from the most recent (June 2014) 6-year run of the SOSE we find that surface cooling in the ARC is balanced by heating from south-eastward advection by the current whereas heat gain in the ACC is balanced by cooling due to northward Ekman transport driven by strong westerly winds. These results suggest that spatial patterns in multi-decadal upper ocean temperature trends depend on regional variations in upper ocean dynamics.

  3. On the heat capacity of elements in WMD regime

    NASA Astrophysics Data System (ADS)

    Hamel, Sebatien

    2014-03-01

    Once thought to get simpler with increasing pressure, elemental systems have been discovered to exhibit complex structures and multiple phases at high pressure. For carbon, QMD/PIMC simulations have been performed and the results are guiding alternative modelling methodologies for constructing a carbon equation-of-state covering the warm dense matter regime. One of the main results of our new QMD/PIMC carbon equation of state is that the decay of the ion-thermal specific heat with temperature is much faster than previously expected. An important question is whether this is only found in carbon and not other element. In this presentation, based on QMD calculations for several elements, we explore trends in the transition from condensed matter to warm dense matter regime.

  4. 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.

  5. Empirical relationships between summertime oceanic heat anomalies in the Nordic seas and large-scale atmospheric circulation in the following winter

    NASA Astrophysics Data System (ADS)

    Schlichtholz, Pawel

    2016-01-01

    A lagged regression analysis between an index of observed summertime Atlantic water temperature (AWT) variability at the entrance to the Barents Sea in the period 1982-2005 and year-round atmospheric (NCEP/NCAR) reanalysis data is used to show that subsurface oceanic heat anomalies in high latitudes are significant precursors of wintertime atmospheric variability in middle latitudes. In particular, positive AWT anomalies precede predominantly westerly wind anomalies in high latitudes and easterly wind anomalies in middle latitudes. The mid-latitude wind anomalies, while being generally equivalent barotropic in the upper troposphere, have a strong low-level baroclinic contribution over Eurasia. The near-surface easterly wind anomalies in this area are locally deflected southward, maintaining cold spots near orography. The summertime oceanic anomalies explain about 40 % of the variance in the surface air temperature averaged over Eurasia from 35° to 45°N and about 50 % of the variance in surface winds over the Far East Asia in the following winter. We suggest that the remote connections arise from reorganization of the mid-latitude storm tracks. The AWT anomalies explain about 60 % of the variance in the upper-tropospheric storm track activity averaged over the Pacific and Eurasia from 35° to 55°N and in the lower-tropospheric poleward synoptic eddy heat flux over western Eurasia. Finally, we show that the AWT-associated wintertime atmospheric anomalies appear in quadrature with the concurrent anomalies associated with the North Atlantic Oscillation. These findings suggest that oceanic heat anomalies in high latitudes may be a useful predictor of atmospheric variability.

  6. 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 .

  7. 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.

  8. 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).

  9. Cooling and Heating Season Impacts of Right-Sizing of Fixed- and Variable-Capacity Heat Pumps With Attic and Indoor Ductwork

    SciTech Connect

    Cummings, James; Withers, Charles; Kono, Jamie

    2015-06-01

    A new generation of central, ducted variable-capacity heat pump systems has come on the market, promising very high cooling and heating efficiency. They are controlled differently than standard fixed-capacity systems. Instead of cycling on at full capacity and then cycling off when the thermostat is satisfied, they vary their cooling and heating output over a wide range (approximately 40% - 118% of nominal full capacity), thus staying 'on' for 60% - 100% more hours per day compared to fixed -capacity systems. Experiments in this research examined the performance of 2-ton and 3-ton fixed- and variable-capacity systems and the impacts of system oversizing.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Determining Optimal Equipment Capacities in Cooling, Heating and Power (CHP) Systems

    SciTech Connect

    DeVault, Robert C; Hudson II, Carl Randy

    2006-01-01

    Evaluation of potential cooling, heating and power (CHP) applications requires an assessment of the operations and economics of a particular system in meeting the electric and thermal demands of a specific end-use facility. A key determinate in whether a candidate system will be economic is the proper selection of equipment capacities. A methodology to determine the optimal capacities for CHP prime movers and absorption chillers using nonlinear optimization algorithms has been coded into a Microsoft Excel spreadsheet tool that performs the capacity optimization and operations simulation. This paper presents details on the use and results of this publicly available tool.

  18. THERMAL STUDY OF THE DIII-D MACHINE HEAT REMOVAL CAPACITY

    SciTech Connect

    YIP,H; ADERSON,P.M; HOLTROP,K.L; HARRISON,S

    2003-10-01

    OAK-B135 With each plasma shot, the DIII-D tokamak dissipates 0.5 to 1.0 GJ of energy. Plasma shots may occur as frequently as every ten minutes, and the energy is removed in the form of heat by a cooling water system. to remove heat from the machine, cooling water circulates through each major heat source. These sources include the power supplies, motor/generator, rf current drives, neutral beam power supplies, magnetic field coils, and vacuum vessel. The cooling water system consists of isolated primary and secondary cooling loops separated by intermediate heat exchangers. As future DIII-D plans include operation during summer months and longer pulse duration, the cooling system's overall heat removal capability and performance efficiency must be assessed. Temperature and flow data from around the DIII-D facility are collected by a programmable logic controller (PLC); the data are used to analyze the heat generating sources, the heat transfer rate to intermediate heat exchangers, and the ultimate heat rejection to the environment via the cooling towers. A comparison of the original DIII-D machine design versus the actual performance determines the margin of heat removal capacity. projections of the heat removal rate for various longer plasma shots are made. Improvements in design and/or operational procedure will be necessary to attain the desired pulse duration.

  19. 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.

  20. 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.

  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. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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…

  9. 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...

  10. 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).

  11. Status of Natural Gas Pipeline System Capacity Entering the 2000-2001 Heating Season

    EIA Publications

    2000-01-01

    This special report looks at the capabilities of the national natural gas pipeline network in 2000 and provides an assessment of the current levels of available capacity to transport supplies from production areas to markets throughout the United States during the upcoming heating season. It also examines how completion of currently planned expansion projects and proposed new pipelines would affect the network.

  12. Effect of heat treatment on the phenolic compounds and antioxidant capacity of citrus peel extract.

    PubMed

    Xu, Guihua; Ye, Xingqian; Chen, Jianchu; Liu, Donghong

    2007-01-24

    This paper reports the effects of heat treatment on huyou (Citrus paradisi Changshanhuyou) peel in terms of phenolic compounds and antioxidant capacity. High-performance liquid chromatography (HPLC) coupled with a photodiode array (PDA) detector was used in this study for the analysis of phenolic acids (divided into four fractions: free, ester, glycoside, and ester-bound) and flavanone glycosides (FGs) in huyou peel (HP) before and after heat treatment. The results showed that after heat treatment, the free fraction of phenolic acids increased, whereas ester, glycoside, and ester-bound fractions decreased and the content of total FGs declined (P < 0.05). Furthermore, the antioxidant activity of methanol extract of HP increased (P < 0.05), which was evaluated by total phenolics contents (TPC) assay, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS*+) method, and ferric reducing antioxidant power (FRAP) assay. The correlation coefficients among TPC, ABTS, FRAP assay, and total cinnamics and benzoics (TCB) in the free fraction were significantly high (P < 0.05), which meant that the increase of total antioxidant capacity (TAC) of HP extract was due at least in part to the increase of TCB in free fraction. In addition, FGs may be destroyed when heated at higher temperature for a long time (for example, 120 degrees C for 90 min or 150 degrees C for 30 min). Therefore, it is suggested that a proper and reasonable heat treatment could be used to enhance the antioxidant capacity of citrus peel. PMID:17227062

  13. Resistor-network anomalies in the heat transport of random harmonic chains

    NASA Astrophysics Data System (ADS)

    Weinberg, Isaac; de Leeuw, Yaron; Kottos, Tsampikos; Cohen, Doron

    2016-06-01

    We consider thermal transport in low-dimensional disordered harmonic networks of coupled masses. Utilizing known results regarding Anderson localization, we derive the actual dependence of the thermal conductance G on the length L of the sample. This is required by nanotechnology implementations because for such networks Fourier's law G ∝1 /Lα with α =1 is violated. In particular we consider "glassy" disorder in the coupling constants and find an anomaly which is related by duality to the Lifshitz-tail regime in the standard Anderson model.

  14. 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.

  15. 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.

  16. Evaluation of a large capacity heat pump concept for active cooling of hypersonic aircraft structure

    NASA Technical Reports Server (NTRS)

    Pagel, L. L.; Herring, R. L.

    1978-01-01

    Results of engineering analyses assessing the conceptual feasibility of a large capacity heat pump for enhancing active cooling of hypersonic aircraft structure are presented. A unique heat pump arrangement which permits cooling the structure of a Mach 6 transport to aluminum temperatures without the aid of thermal shielding is described. The selected concept is compatible with the use of conventional refrigerants, with Freon R-11 selected as the preferred refrigerant. Condenser temperatures were limited to levels compatible with the use of conventional refrigerants by incorporating a unique multipass condenser design, which extracts mechanical energy from the hydrogen fuel, prior to each subsequent pass through the condenser. Results show that it is technically feasible to use a large capacity heat pump in lieu of external shielding. Additional analyses are required to optimally apply this concept.

  17. 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.

  18. Enhancing heat capacity of colloidal suspension using nanoscale encapsulated phase-change materials for heat transfer.

    PubMed

    Hong, Yan; Ding, Shujiang; Wu, Wei; Hu, Jianjun; Voevodin, Andrey A; Gschwender, Lois; Snyder, Ed; Chow, Louis; Su, Ming

    2010-06-01

    This paper describes a new method to enhance the heat-transfer property of a single-phase liquid by adding encapsulated phase-change nanoparticles (nano-PCMs), which absorb thermal energy during solid-liquid phase changes. Silica-encapsulated indium nanoparticles and polymer-encapsulated paraffin (wax) nanoparticles have been made using colloid method, and suspended into poly-alpha-olefin (PAO) and water for potential high- and low-temperature applications, respectively. The shells prevent leakage and agglomeration of molten phase-change materials, and enhance the dielectric properties of indium nanoparticles. The heat-transfer coefficients of PAO containing indium nanoparticles (30% by mass) and water containing paraffin nanoparticles (10% by mass) are 1.6 and 1.75 times higher than those of corresponding single-phase fluids. The structural integrity of encapsulation allows repeated use of such nanoparticles for many cycles in high heat generating devices. PMID:20527779

  19. 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.

  20. 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.

  1. Contrasting Metamorphic Record of Heat Production Anomalies in the Penokean Orogen of Northern Michigan.

    PubMed

    Attoh

    2000-05-01

    It is proposed that the contrasting metamorphic mineral assemblages of the isolated amphibolite facies metamorphic highs in the Penokean orogen of northern Michigan may be caused by different heat production rates in the Archean basement. This hypothesis is based on concentrations of K, U, and Th in the Archean basement gneisses and Paleoproterozoic metasediments that indicate significant contribution of radiogenic heating during Penokean metamorphism. Heat production was anomalously high ( approximately 10.6 µWm-3) where andalusite-bearing mineral assemblages indicate that high temperatures were attained at shallow crustal levels ( approximately 550 degrees -600 degrees C at approximately 3 kbar). In contrast, where exposed metamorphic rocks indicate peak temperatures of 600 degrees -650 degrees C at 6-7 kbar, heat production in the Archean basement was lower ( approximately 3.7 µWm-3). The effect of heat production rates on the metamorphic pressure-temperature paths was tested with numerical thermal models. The calculations show (1) that if the heat production rate, where andalusite-bearing assemblages formed, was significantly <6.0 µWm-3, the estimated pressure at peak temperatures (PTmax) would be much higher and lie in the sillimanite or kyanite stability fields; and (2) differences between PTmax estimates for the metamorphic highs based on thermobarometry can be reproduced if thermal history involved significant crustal thickening as well as moderate unroofing rates. PMID:10769161

  2. 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.

  3. Physiological responses to heat of resting man with impaired sweating capacity

    NASA Technical Reports Server (NTRS)

    Totel, G. L.

    1974-01-01

    The effects of total-body heat exposure were studied in three groups of subjects with varied degrees of impaired sweating capacity. The responses of two ectodermal dysplasic men, six quadriplegic men, and a man with widespread burned scar tissue were compared with the responses of three able-bodied men resting in the heat. It was found that the able-bodied and burned subjects competed successfully with a controlled environment of 38 C and 20% relative humidity for up to 150 min, whereas the quadriplegic and ectodermal dysplasic men developed hyperthermia, hyperventilation, and distress after only 120 and 75 min of heat exposure, respectively. The intolerance to heat is thus ascribed directly to the inability to produce and evaporate sweat.

  4. Land surface anomalies preceding the 2010 Russian heat wave and a link to the North Atlantic oscillation

    NASA Astrophysics Data System (ADS)

    Wright, Christopher K.; de Beurs, Kirsten M.; Henebry, Geoffrey M.

    2014-12-01

    The Eurasian wheat belt (EWB) spans a region across Eastern Ukraine, Southern Russia, and Northern Kazakhstan; accounting for nearly 15% of global wheat production. We assessed land surface conditions across the EWB during the early growing season (April-May-June AMJ) leading up to the 2010 Russian heat wave, and over a longer-term period from 2000 to 2010. A substantial reduction in early season values of the normalized difference vegetation index occurred prior to the Russian heat wave, continuing a decadal decline in early season primary production in the region. In 2010, an anomalously cold winter followed by an abrupt shift to a warmer-than-normal early growing season was consistent with a persistently negative phase of the North Atlantic oscillation (NAO). Regression analyses showed that early season vegetation productivity in the EWB is a function of both the winter (December-January-February DJF) and AMJ phases of the NAO. Land surface anomalies preceding the heat wave were thus consistent with highly negative values of both the DJF NAO and AMJ NAO in 2010.

  5. 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

  6. Water treatment capacity of forward osmosis systems utilizing power plant waste heat

    SciTech Connect

    Zhou, Xingshi; Gingerich, Daniel B.; Mauter, Meagan S.

    2015-06-11

    Forward osmosis (FO) has the potential to improve the energy efficiency of membrane-based water treatment by leveraging waste heat from steam electric power generation as the primary driving force for separation. In this study, we develop a comprehensive FO process model, consisting of membrane separation, heat recovery, and draw solute regeneration (DSR) models. We quantitatively characterize three alternative processes for DSR: distillation, steam stripping, and air stripping. We then construct a mathematical model of the distillation process for DSR that incorporates hydrodynamics, mass and heat transport resistances, and reaction kinetics, and we integrate this into a model for the full FO process. Finally, we utilize this FO process model to derive a first-order approximation of the water production capacity given the rejected heat quantity and quality available at U.S. electric power facilities. We find that the upper bound of FO water treatment capacity using low-grade heat sources at electric power facilities exceeds process water treatment demand for boiler water make-up and flue gas desulfurization wastewater systems.

  7. Water treatment capacity of forward osmosis systems utilizing power plant waste heat

    DOE PAGESBeta

    Zhou, Xingshi; Gingerich, Daniel B.; Mauter, Meagan S.

    2015-06-11

    Forward osmosis (FO) has the potential to improve the energy efficiency of membrane-based water treatment by leveraging waste heat from steam electric power generation as the primary driving force for separation. In this study, we develop a comprehensive FO process model, consisting of membrane separation, heat recovery, and draw solute regeneration (DSR) models. We quantitatively characterize three alternative processes for DSR: distillation, steam stripping, and air stripping. We then construct a mathematical model of the distillation process for DSR that incorporates hydrodynamics, mass and heat transport resistances, and reaction kinetics, and we integrate this into a model for the fullmore » FO process. Finally, we utilize this FO process model to derive a first-order approximation of the water production capacity given the rejected heat quantity and quality available at U.S. electric power facilities. We find that the upper bound of FO water treatment capacity using low-grade heat sources at electric power facilities exceeds process water treatment demand for boiler water make-up and flue gas desulfurization wastewater systems.« less

  8. Determining the Heat Exchange Capacity of Underground Coal Mines in Ohio

    NASA Astrophysics Data System (ADS)

    Richardson, J. J.; Lopez, D. A.; Leftwich, T. E.; Wolfe, M. E.; Angle, M. P.; Fugitt, F. L.

    2013-12-01

    Conventionally, Ground Source Heat Pumps (GSHP) exploit either saturated bedrock/soils or large surface water bodies as the heat source/sink for the heating and cooling systems. In areas with flooded mines or large subsurface water bodies, it is possible to utilize the water within the voids as the heat source/sink in GSHPs. Utilizing the water within subsurface voids a heat exchanger instead of the traditional saturated bedrock/soils has the potential to be more efficient in heating and cooling applications. The water within the void space is a better thermal conductor than bedrock and soils. Additionally, it is possible that, in a saturated void the heat can be carried away from the exchange site at a greater rate, improving the potential for thermal exchange. This study is focused on characterizing the potential overall heat exchange capacity for flooded mine sites within Ohio. To achieve the overall potential exchange capacity, possible maximum and minimum mine water residence times, effective mine volumes, groundwater recharge rates, maximum and minimum possible linear groundwater velocity, groundwater flow direction, and average ambient mine temperatures were calculated using GIS software and groundwater recharge data from the United States Geological Survey, and characteristics of physical parameters for the mines from the Ohio Geological Survey. The potential linear mine water velocities were calculated by creating a theoretical cross sectional area in the direction of estimated groundwater flow with a respective length of the mine in the direction of groundwater flow and width of the coal bed thickness. It was assumed that all of water entering the mine void exited the through the cross sectional area. By dividing the volume of water entering the mine per year by the cross sectional area, the linear groundwater velocities were estimated. By using the specific heat of water at the estimated temperatures and the volumes of water within the mines, possible

  9. 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.

  10. 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

  11. 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

  12. Influence of heat treatment on antioxidant capacity and (poly)phenolic compounds of selected vegetables.

    PubMed

    Juániz, Isabel; Ludwig, Iziar A; Huarte, Estibaliz; Pereira-Caro, Gema; Moreno-Rojas, Jose Manuel; Cid, Concepción; De Peña, María-Paz

    2016-04-15

    The impact of cooking heat treatments (frying in olive oil, frying in sunflower oil and griddled) on the antioxidant capacity and (poly)phenolic compounds of onion, green pepper and cardoon, was evaluated. The main compounds were quercetin and isorhamnetin derivates in onion, quercetin and luteolin derivates in green pepper samples, and chlorogenic acids in cardoon. All heat treatments tended to increase the concentration of phenolic compounds in vegetables suggesting a thermal destruction of cell walls and sub cellular compartments during the cooking process that favor the release of these compounds. This increase, specially that observed for chlorogenic acids, was significantly correlated with an increase in the antioxidant capacity measured by DPPH (r=0.70). Griddled vegetables, because of the higher temperature applied during treatment in comparison with frying processes, showed the highest amounts of phenolic compounds with increments of 57.35%, 25.55% and 203.06% compared to raw onion, pepper and cardoon, respectively. PMID:26616976

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. The development of a high-capacity instrument module heat transport system, appendixes

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Data sheets provide temperature requirements for 82 individual instruments that are under development or planned for grouping on a space platform or pallet. The scientific objectives of these instrument packages are related to solar physics, space plasma physics, astronomy, high energy astrophysics, resources observations, environmental observations, materials processing, and life sciences. System specifications are given for a high capacity instrument module heat transport system to be used with future payloads.

  1. 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.

  2. 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

  3. Cooling and Heating Season Impacts of Right-Sizing of Fixed- and Variable-Capacity Heat Pumps With Attic and Indoor Ductwork

    SciTech Connect

    Cummings, James; Withers, Charles; Kono, Jamie

    2015-06-24

    A new generation of full variable-capacity air-conditioning (A/C) and heat pump units has come on the market that promises to deliver very high cooling and heating efficiency. The units are controlled differently than standard single-capacity (fixed-capacity) systems. Instead of cycling on at full capacity and cycling off when the thermostat is satisfied, the new units can vary their capacity over a wide range (approximately 40%–118% of nominal full capacity) and stay on for 60%–100% more hours per day than the fixed-capacity systems depending on load-to-capacity ratios. Two-stage systems were not evaluated in this research effort.

  4. Seasonal and geographical variation in heat tolerance and evaporative cooling capacity in a passerine bird.

    PubMed

    Noakes, Matthew J; Wolf, Blair O; McKechnie, Andrew E

    2016-03-01

    Intraspecific variation in avian thermoregulatory responses to heat stress has received little attention, despite increasing evidence that endothermic animals show considerable physiological variation among populations. We investigated seasonal (summer versus winter) variation in heat tolerance and evaporative cooling in an Afrotropical ploceid passerine, the white-browed sparrow-weaver (Plocepasser mahali; ∼ 47 g) at three sites along a climatic gradient with more than 10 °C variation in mid-summer maximum air temperature (Ta). We measured resting metabolic rate (RMR) and total evaporative water loss (TEWL) using open flow-through respirometry, and core body temperature (Tb) using passive integrated transponder tags. Sparrow-weavers were exposed to a ramped profile of progressively higher Ta between 30 and 52 °C to elicit maximum evaporative cooling capacity (N=10 per site per season); the maximum Ta birds tolerated before the onset of severe hyperthermia (Tb ≈ 44 °C) was considered to be their hyperthermia threshold Ta (Ta,HT). Our data reveal significant seasonal acclimatisation of heat tolerance, with a desert population of sparrow-weavers reaching significantly higher Ta in summer (49.5 ± 1.4 °C, i.e. higher Ta,HT) than in winter (46.8 ± 0.9 °C), reflecting enhanced evaporative cooling during summer. Moreover, desert sparrow-weavers had significantly higher heat tolerance and evaporative cooling capacity during summer compared with populations from more mesic sites (Ta,HT=47.3 ± 1.5 and 47.6 ± 1.3 °C). A better understanding of the contributions of local adaptation versus phenotypic plasticity to intraspecific variation in avian heat tolerance and evaporative cooling capacity is needed for modelling species' responses to changing climates. PMID:26787477

  5. A Heat Vulnerability Index: Spatial Patterns of Exposure, Sensitivity and Adaptive Capacity for Santiago de Chile.

    PubMed

    Inostroza, Luis; Palme, Massimo; de la Barrera, Francisco

    2016-01-01

    Climate change will worsen the high levels of urban vulnerability in Latin American cities due to specific environmental stressors. Some impacts of climate change, such as high temperatures in urban environments, have not yet been addressed through adaptation strategies, which are based on poorly supported data. These impacts remain outside the scope of urban planning. New spatially explicit approaches that identify highly vulnerable urban areas and include specific adaptation requirements are needed in current urban planning practices to cope with heat hazards. In this paper, a heat vulnerability index is proposed for Santiago, Chile. The index was created using a GIS-based spatial information system and was constructed from spatially explicit indexes for exposure, sensitivity and adaptive capacity levels derived from remote sensing data and socio-economic information assessed via principal component analysis (PCA). The objective of this study is to determine the levels of heat vulnerability at local scales by providing insights into these indexes at the intra city scale. The results reveal a spatial pattern of heat vulnerability with strong variations among individual spatial indexes. While exposure and adaptive capacities depict a clear spatial pattern, sensitivity follows a complex spatial distribution. These conditions change when examining PCA results, showing that sensitivity is more robust than exposure and adaptive capacity. These indexes can be used both for urban planning purposes and for proposing specific policies and measures that can help minimize heat hazards in highly dynamic urban areas. The proposed methodology can be applied to other Latin American cities to support policy making. PMID:27606592

  6. Heat capacity study of the magnetic phases in a Nd5Ge3 single crystal

    NASA Astrophysics Data System (ADS)

    Villuendas, D.; Tsutaoka, T.; Hernàndez Ferràs, J. M.

    2016-05-01

    The different magnetic phases of the intermetallic compound Nd5Ge3 are studied in terms of the specific heat, in a broad range of temperatures (350 mK-140 K) and magnetic fields (up to 40 kOe). The expected T3 and T 3 / 2 terms are not found in the antiferromagnetic (AFM) and ferromagnetic (FM) phases respectively, but a gapped T2 contribution that originates from a mixture of AFM and FM interactions in different dimensionalities under a large magnetocrystalline anisotropy, is present in both. An almost identical Schottky anomaly, that arises from the hyperfine splitting of the nuclear levels of the Nd3+ ions, is observed in both phases, which leads us to state that the magnetic-field induced transition AFM → FM that the system experiments below 26 K consists in the flip of the magnetic moments of the Nd ions, conserving the average local moment.

  7. Integration and flight demonstration of a high-capacity monogroove heat-pipe radiator

    NASA Technical Reports Server (NTRS)

    Rankin, J. G.

    1984-01-01

    The cancellation of the TDRS-B satellite as the payload for the eighth Space Shuttle mission provided a unique opportunity to demonstrate on-orbit operation of the high-capacity monogroove heat pipe used in the space constructible radiator subsystem. In less than 4 months, a flight experiment was conceived, designed, fabricated, tested, integrated with a payload carrier, installed in the Orbiter Challenger payload bay, and successfully operated in flight. Still color photographs and direct crew visual observation of color changes in a pattern of temperature-sensitive liquid-crystal tapes provided the temperature data necessary to verify successful on-orbit startup and orbital transient response of the heat pipe when subjected to a heat load from its attached electrical heaters. This successful on-orbit demonstration verified analytical design tools and provided confidence in the use of high-capacity heat pipes for future space applications. The flight experiment hardware and the integration and test activities that led to the flight are described, and the actual flight results are compared to analytical performance predictions.

  8. Heat flow anomaly associated with dike intrusion. II. [in earth crust

    NASA Technical Reports Server (NTRS)

    Horai, K.-I.

    1976-01-01

    An investigation reported by Horai (1974) is continued. A special case of the steady state temperature field associated with dike intrusion is studied, taking into account an infinite vertical downward extension of the isotherm of rectangular shape approximating the dike. The considered case represents a problem of two-dimensional steady state thermal conduction. The technique of conformal mapping used is identical to the method employed by Horai (1974). The characteristics of surface heat flow associated with an infinitesimal thin dike of certain temperature with the considered extension are shown in a graph.

  9. Past analogs of recent climate anomalies and impacts in Portugal. Droughts, storms and heat waves

    NASA Astrophysics Data System (ADS)

    Alcoforado, M. J.; Nunes, M. F.

    2009-09-01

    An indexed reconstruction of precipitation variability, based on documentary and instrumental data, has been done for southern Portugal starting in 1675. The descriptions of the extreme events in the documentary sources have also supplied information about their impacts. We will compare past and recent extreme weather events in Portugal, their causes and their impacts on society. We have selected periods of winter droughts, of storms that triggered great floods and of heat waves. There are a number of documentary sources dating from 1693-94 indicating that that there was no rainfall from December 1693 to at least November 1694 with the exception of light showers in June. Several pro-pluvia rogations ceremonies took place all over the country, even in the Northwest that is generally rainy. There are numerous descriptions of the impact of droughts on agriculture, of shortage of cereals, of escalating prices and the subsequent generalised famine. An analogy will be made for the 20th century using the 1980-81 winter drought that lasted roughly the same time and which also had severe social and economic impacts. The decrease in production of hydroelectric energy (50% below average) between January and July 1981 is also pointed out. In both cases, the lack of rainfall was partly due to a ridge that stayed over the Eastern Atlantic and kept Iberia in aerologic shelter. Apart from urban flash floods there are two types of floods in Portugal: (i) floods from the big river basins (Tagus, Mondego and Douro) that are due to the frequent passage of westerly frontal depressions during days or weeks; and (ii) floods of the small river basins due to convective depressions that affect small areas. The December 1739 flood, caused by the overflow of the great rivers, will be compared with the ones that occurred in February 1978. Both were caused by intensive precipitation all over the country at a time when the soil was already saturated with water from previous rainfall. The damages

  10. 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).

  11. 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.

  12. 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.

  13. 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

  14. Specific heat anomaly in ferroelectric: Bis(imidazolium) pentachloroantimonate(III) (C3 N2 H5)2[SbCl5

    NASA Astrophysics Data System (ADS)

    Przesławski, J.; Piecha-Bisiorek, A.; Jakubas, R.

    2016-04-01

    Single crystals of ferroelectric bis(imidazolium) pentachloroantimonate(III) (C3N2H5)2 [SbCl5 ] have been grown and the heat capacity was measured by the use of AC calorimetric method. The temperature dependence of excess heat capacity and excess entropy in the ferroelectric phase can be described in the frame of the classical Landau-Devonshire theory of phase transitions. The results of experimental studies were analyzed and the α, γ and δ values of the Landau potential coefficients were calculated. The temperature dependence of the order parameter was also evaluated from the heat capacity data.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Mapping temperature and radiant geothermal heat flux anomalies in the Yellowstone geothermal system using ASTER thermal infrared data

    USGS Publications Warehouse

    Vaughan, R. Greg; Lowenstern, Jacob B.; Keszthelyi, Laszlo P.; Jaworowski, Cheryl; Heasler, Henry

    2012-01-01

    The purpose of this work was to use satellite-based thermal infrared (TIR) remote sensing data to measure, map, and monitor geothermal activity within the Yellowstone geothermal area to help meet the missions of both the U.S. Geological Survey Yellowstone Volcano Observatory and the Yellowstone National Park Geology Program. Specifically, the goals were to: 1) address the challenges of remotely characterizing the spatially and temporally dynamic thermal features in Yellowstone by using nighttime TIR data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and 2) estimate the temperature, geothermal radiant emittance, and radiant geothermal heat flux (GHF) for Yellowstone’s thermal areas (both Park wide and for individual thermal areas). ASTER TIR data (90-m pixels) acquired at night during January and February, 2010, were used to estimate surface temperature, radiant emittance, and radiant GHF from all of Yellowstone’s thermal features, produce thermal anomaly maps, and update field-based maps of thermal areas. A background subtraction technique was used to isolate the geothermal component of TIR radiance from thermal radiance due to insolation. A lower limit for the Yellowstone’s total radiant GHF was established at ~2.0 GW, which is ~30-45% of the heat flux estimated through geochemical (Cl-flux) methods. Additionally, about 5 km2 was added to the geodatabase of mapped thermal areas. This work provides a framework for future satellite-based thermal monitoring at Yellowstone as well as exploration of other volcanic / geothermal systems on a global scale.

  8. Heat Stress and Physical Capacity: A Case Study of Semi-Professional Footballers

    PubMed Central

    GOLBABAEI, Farideh; ZAKERIAN, Seyyed Abolfazl; FOULADI DEHAGHI, Behzad; IBRAHIMI GHAVAMABADI, Leila; GHARAGOZLOU, Framarz; MIRZAEI ALIABADI, Mostafa; HEMATJO, Rasol

    2014-01-01

    Abstract Background The aim of this study was to determine heat stress effect on physical capacity of semi-professional footballers in Iran by means of oxygen consumption measurement, heart rate monitoring and WBGT assessment environmental conditions. Methods This study compared two different thermal environmental conditions related to sub-maximal exercise and its effect on human physical capacity. Thirty two male footballers (age 25.9 ± 1.4 year; height 176 ± 2.9 cm and weight 71 ± 9.8 kg) were investigated under four workloads (50,100,150 & 200 W) in two different thermal conditions in the morning (WBGT=21 °C) and afternoon (WBGT=33 °C) in summer. Each test cycle lasted for 10 minutes with a 10 min interval for recovery and rest between every workload. In the end of each stage, the heart rate, blood pressure, skin temperature and oral temperature were measured and recorded. Expired air was collected and its volume was measured using standard Douglas bags. The WBGT index was also used to monitor the stressful heat condition. Results Heart rate and VO2 consumption findings for different workload showed a significant difference between morning and afternoon (P<0.001). HR and VO2 consumption in both morning and afternoon courses showed a liner relation (r=0.88, r=0.9 respectively). Conclusion With increasing work load beside heat stress, heart rate and oxygen consumption increased. It is recommended that with Ta>35 °C or WBGT>28 °C, physical activates and performing exercises should be avoided in order to reduce the risk of heat stress-related conditions in athletes PMID:25988096

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. The Time-lagged Impacts of Spring Sensible Heat over the Tibetan Plateau on the Summer Rainfall Anomaly in East China: Cases Study by Using WRF Model

    NASA Astrophysics Data System (ADS)

    Duan, A.

    2014-12-01

    This study explores the time-lagged impacts of the spring sensible heat (SH) source over the Tibetan Plateau (TP) on summer rainfall anomaly in east China by using the WRF model. Numerical experiments for the 2003 case indicates that spring SH anomaly over the TP can maintains its impact until summer and leads to the overall strong atmospheric heat source, which is characterized by the enhanced both SH over the western TP and condensation latent heat to the east. The wave activity diagnosis revealed that the enhanced TP heating forces a Rossby wave train to the downstream regions. The cyclonic response to the northeast TP brings about the low level northerly anomaly over the northern China, while the anticyclonic response over the western Pacific enhances the subtropical high and the low level southerly in its western flank. As a result, cold and dry airflows from mid-high latitudes and warm and wet airflows from tropical oceans converge around the Huaihe River basin. In addition, warm advection originated from the TP induces vigorous ascending motion over the convergence belt. With such a favourable circulation condition, the eastward propagating vortexes initiated over the TP intensify the torrential rainfall processes over the Huaihe River basin. Another case study of 2001 with weak spring SH over the TP and the overall southward retreat of summer rainfall belt in east China further demonstrates the role of spring SH over the TP in regulating the interannual variability of EASM in terms of wave activity and synoptic disturbance.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Coincidence of collective relaxation anomaly and specific heat peak in a bulk metallic glass-forming liquid

    NASA Astrophysics Data System (ADS)

    Jaiswal, Abhishek; Podlesynak, Andrey; Ehlers, Georg; Mills, Rebecca; O'Keeffe, Stephanie; Stevick, Joseph; Kempton, James; Jelbert, Glenton; Dmowski, Wojciech; Lokshin, Konstantin; Egami, Takeshi; Zhang, Yang

    2015-07-01

    The study of relaxational behavior of multicomponent metallic liquids still holds the key to understanding and improving the glass-forming abilities of bulk metallic glasses. Herein, we report measurements of the collective relaxation times in a melted bulk metallic glass (LM 601 Zr51Cu36Ni4Al9 ) in the kinetic regime (Q : 1.5 -4.0 Å-1) using quasielastic neutron scattering. The results reveal an unusual slope change in the Angell plots of the collective relaxation time of this metallic liquid around 950 ∘C , beyond the melting point of the material. Specific heat capacity measurement also reveals the presence of a peak around the same temperature. The coincidence is rationalized using Adams-Gibbs theory, and motivates more careful experimental and computational studies of the metallic liquids in the future.

  4. Coincidence of collective relaxation anomaly and specific heat peak in a bulk metallic glass-forming liquid

    SciTech Connect

    Jaiswal, Abhishek; Podlesynak, Andrey; Ehlers, Georg; Mills, Rebecca; O'Keeffe, Stephanie; Stevick, Joseph; Kempton, James; Jelbert, Glenton; Dmowski, Wojciech; Lokshin, Konstantin; Egami, Takeshi; Zhang, Yang

    2015-07-21

    The study of multicomponent metallic liquids' relaxational behavior is still the key to understanding and improving the glass-forming abilities of bulk metallic glasses. Here, we report measurements of the collective relaxation times in a melted bulk metallic glass (LM601Zr51Cu36Ni4Al9) in the kinetic regime (Q: 1.5–4.0Å–1) using quasielastic neutron scattering. The results reveal an unusual slope change in the Angell plots of this metallic liquid's collective relaxation time around 950°C, beyond the material's melting point. Measurement of specific heat capacity also reveals a peak around the same temperature. Adams-Gibbs theory is used to rationalize the coincidence, which motivates more careful experimental and computational studies of the metallic liquids in the future.

  5. Coincidence of collective relaxation anomaly and specific heat peak in a bulk metallic glass-forming liquid

    DOE PAGESBeta

    Jaiswal, Abhishek; Podlesynak, Andrey; Ehlers, Georg; Mills, Rebecca; O'Keeffe, Stephanie; Stevick, Joseph; Kempton, James; Jelbert, Glenton; Dmowski, Wojciech; Lokshin, Konstantin; et al

    2015-07-21

    The study of multicomponent metallic liquids' relaxational behavior is still the key to understanding and improving the glass-forming abilities of bulk metallic glasses. Here, we report measurements of the collective relaxation times in a melted bulk metallic glass (LM601Zr51Cu36Ni4Al9) in the kinetic regime (Q: 1.5–4.0Å–1) using quasielastic neutron scattering. The results reveal an unusual slope change in the Angell plots of this metallic liquid's collective relaxation time around 950°C, beyond the material's melting point. Measurement of specific heat capacity also reveals a peak around the same temperature. Adams-Gibbs theory is used to rationalize the coincidence, which motivates more careful experimentalmore » and computational studies of the metallic liquids in the future.« less

  6. 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)

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Estimation of yield capacity of fractured rock aquifer for multi-well groundwater heat pump system

    NASA Astrophysics Data System (ADS)

    Bak, Hyeongmin; Yeo, In Wook

    2015-04-01

    Geothermal heat pump system is classified as closed loop and open loop. Closed loop uses a refrigerant as a heat source. For the reason, when using it for a long time, there is a possibility that the refrigerant pipe is corroded. Accordingly, soil and groundwater can be contaminated. Whereas the open loop system uses a eco-friendly groundwater as a heat source. Thermal circulation of standing column well (SCW) occurs in one well. In contrast, thermal circulation of multi-well groundwater heat pump system (MGHP) occurs through fractured rock aquifer between extraction and injection wells. Therefore, temperature efficiency of MGHP appears to be better than that of SCW. However, the MGHP has problems such as the overflowing in the injection well and the clogging, which restricts the wide use of MGHP. This study aims at how to to array the extraction and injection wells for stable circulating of groundwater and at evaluating the sustainable yield capacity of groundwater circulation between the two wells. The study site is located in Chuncheon, Republic of Korea. Pumping tests were conducted to estimate transmissivity of the two wells (W3, W4). In addition, the step-circulation tests were conducted to estimate the sustainable yield capacity. Transmissivity of W3 and W4 was estimated to be 5.81 x 10^-5 m^2/s and 2.57 x 10^-5 m^2/s, respectively. Preliminary groundwater circulation tests were conducted to figure out the array of the extraction and injection wells. Circulation tests were performed for two cases: first, extraction well was set at the well with higher transmissivity and injection well set at the well with lower transmissivity, and the opposite array was set for the second case. In the first case, when flow rate was set at 70.47 m^3/day, the water level of W3 fell 0.61m and that of W4 rose 1.89m. In the second case, when flow rate was set at 67.70 m^3/day, the water level of W4 fell 2.17m and that of W3 rose 0.5m. Preliminary groundwater

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. Performance of Variable Capacity Heat Pumps in a Mixed Humid Climate

    SciTech Connect

    Munk, Jeffrey D; Gehl, Anthony C; Jackson, Roderick K

    2012-04-01

    Variable capacity heat pumps represent the next wave of technology for heat pumps. In this report, the performance of two variable capacity heat pumps (HPs) is compared to that of a single or two stage baseline system. The units were installed in two existing research houses located in Knoxville, TN. These houses were instrumented to collect energy use and temperature data while both the baseline systems and variable capacity systems were installed. The homes had computer controlled simulated occupancy, which provided consistent schedules for hot water use and lighting. The temperature control and energy use of the systems were compared during both the heating and cooling seasons. Multiple linear regression models were used along with TMY3 data for Knoxville, TN in order to normalize the effect that the outdoor air temperature has on energy use. This enables a prediction of each system's energy use over a year with the same weather. The first system was a multi-split system consisting of 8 indoor units and a single outdoor unit. This system replaced a 16 SEER single stage HP with a zoning system, which served as the baseline. Data was collected on the baseline system from August 2009 to December 2010 and on the multi-split system from January 2011 to January 2012. Soon after the installation of the multi-split system, some of the smaller rooms began over-conditioning. This was determined to be caused by a small amount of continuous refrigerant flow to all of the indoor units when the outdoor unit was running regardless of whether they were calling for heat. This, coupled with the fact that the indoor fans run continuously, was providing enough heat in some rooms to exceed the set point. In order to address this, the indoor fans were disabled when not actively heating per the manufacturer's recommendation. Based on the measured data, the multi-split system was predicted to use 40% more energy in the heating season and 16% more energy in the cooling season than the

  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. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Satellite-derived geoid for the estimation of lithospheric cooling and basal heat flux anomalies over the northern Indian Ocean lithosphere

    NASA Astrophysics Data System (ADS)

    Rajesh, S.; Majumdar, T. J.

    2015-12-01

    The northern Indian Ocean consists of older Bay of Bengal (BOB) oceanic lithosphere with numerous intra-plate loads; whereas, contrasting elements like active Mid-Ocean ridge divergence and slow spreading ridges are present in the relatively younger (<60 Ma) Arabian Sea oceanic lithosphere. The mechanism of lithospheric cooling of young age oceanic lithosphere from the moderately active and slow spreading Carlsberg Ridge is analysed by considering the hypothesis of near lithospheric convective action or whole upper mantle convection. We addressed these issues by studying the marine geoid at different spatial wavelengths and retrieved and compared their lithospheric cooling signatures, plate spreading and distribution of mass and heat anomalies along with seismicity, bathymetry, gravity and isochron age data. Results show that progressive cooling of young-aged oceanic lithosphere from the Mid-Ocean Carlsberg Ridge is because of conductive cooling and those signals are retrieved in the shorter wavelength band (111 < λ< 1900 km) of constrained residual geoid with mass anomaly sources near to sublithospheric. This shows steadiness in the geoid anomaly decay rate (˜-0.1 m/Ma), consistency in the growth of thermal boundary layer and progressive fall of basal temperature and heat flux (900- 300 K and 100-18 mW m-2) with increase of lithospheric age. The above observations are attributed to the fact that the advective-convective action beneath the Mid-Ocean Carlsberg Ridge is driven by the basal temperature gradient between the lithosphere and the near lithospheric low viscose thin layer. But, for the case of old-aged oceanic lithosphere in the BOB, the residual geoid anomaly cooling signals are not prominently seen in the same band as that of the Arabian Sea because of the Ninetyeast Ridge magmatism. However, its cooling anomaly signatures are retrieved at relatively higher band (1335 ≤ λ≤ 3081 km) having erratic geoid decay rates (-0.3 to 0.2 m/Ma) owing to

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. A role for haemolymph oxygen capacity in heat tolerance of eurythermal crabs

    PubMed Central

    Giomi, Folco; Pörtner, Hans-Otto

    2013-01-01

    Heat tolerance in aquatic ectotherms is constrained by a mismatch, occurring at high temperatures, between oxygen delivery and demand which compromises the maintenance of aerobic scope. The present study analyses how the wide thermal tolerance range of an eurythermal model species, the green crab Carcinus maenas is supported and limited by its ability to sustain efficient oxygen transport to tissues. Similar to other eurytherms, C. maenas sustains naturally occurring acute warming events through the integrated response of circulatory and respiratory systems. The response of C. maenas to warming can be characterized by two phases. During initial warming, oxygen consumption and heart rate increase, while stroke volume and haemolymph oxygen partial pressure decrease. During further warming, dissolved oxygen levels in the venous compartment decrease below the threshold of full haemocyanin oxygen saturation. The progressive release of haemocyanin bound oxygen with further warming follows an exponential pattern, thereby saving energy in oxygen transport and causing an associated leveling off of metabolic rate. According to the concept of oxygen and capacity limited thermal tolerance (OCLTT), this indicates that the thermal tolerance window is widened by the increasing contribution of haemocyanin oxygen transport and associated energy savings in cardiocirculation. Haemocyanin bound oxygen sustains cardiac performance to cover the temperature range experienced by C. maenas in the field. To our knowledge this is the first study providing evidence of a relationship between thermal tolerance and blood (haemolymph) oxygen transport in a eurythermal invertebrate. PMID:23720633

  19. 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.

  20. 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.

  1. 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

  2. A role for haemolymph oxygen capacity in heat tolerance of eurythermal crabs.

    PubMed

    Giomi, Folco; Pörtner, Hans-Otto

    2013-01-01

    Heat tolerance in aquatic ectotherms is constrained by a mismatch, occurring at high temperatures, between oxygen delivery and demand which compromises the maintenance of aerobic scope. The present study analyses how the wide thermal tolerance range of an eurythermal model species, the green crab Carcinus maenas is supported and limited by its ability to sustain efficient oxygen transport to tissues. Similar to other eurytherms, C. maenas sustains naturally occurring acute warming events through the integrated response of circulatory and respiratory systems. The response of C. maenas to warming can be characterized by two phases. During initial warming, oxygen consumption and heart rate increase, while stroke volume and haemolymph oxygen partial pressure decrease. During further warming, dissolved oxygen levels in the venous compartment decrease below the threshold of full haemocyanin oxygen saturation. The progressive release of haemocyanin bound oxygen with further warming follows an exponential pattern, thereby saving energy in oxygen transport and causing an associated leveling off of metabolic rate. According to the concept of oxygen and capacity limited thermal tolerance (OCLTT), this indicates that the thermal tolerance window is widened by the increasing contribution of haemocyanin oxygen transport and associated energy savings in cardiocirculation. Haemocyanin bound oxygen sustains cardiac performance to cover the temperature range experienced by C. maenas in the field. To our knowledge this is the first study providing evidence of a relationship between thermal tolerance and blood (haemolymph) oxygen transport in a eurythermal invertebrate. PMID:23720633

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. EFFECT OF HEAT ON THE ADSORPTION CAPACITY OF AN ACTIVATED CARBON FOR DECOLORIZING/DEODORIZING YELLOW ZEIN

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Freundlich model was evaluated for use to assess the effect of heat on the adsorption capacity of an activated carbon for decolorizing/deodorizing corn zein. Because zein protein and its color/odor components are all adsorbed by activated carbon, a method to monitor their removal was needed. Y...

  13. 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.

  14. 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).

  15. 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

  16. 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

  17. Age-related differences in heat loss capacity occur under both dry and humid heat stress conditions

    PubMed Central

    Larose, Joanie; Boulay, Pierre; Wright-Beatty, Heather E.; Sigal, Ronald J.; Hardcastle, Stephen

    2014-01-01

    This study examined the progression of impairments in heat dissipation as a function of age and environmental conditions. Sixty men (n = 12 per group; 20–30, 40–44, 45–49, 50–54, and 55–70 yr) performed four intermittent exercise/recovery cycles for a duration of 2 h in dry (35°C, 20% relative humidity) and humid (35°C, 60% relative humidity) conditions. Evaporative heat loss and metabolic heat production were measured by direct and indirect calorimetry, respectively. Body heat storage was measured as the temporal summation of heat production and heat loss during the sessions. Evaporative heat loss was reduced during exercise in the humid vs. dry condition in age groups 20–30 (−17%), 40–44 (−18%), 45–49 (−21%), 50–54 (−25%), and 55–70 yr (−20%). HE fell short of being significantly different between groups in the dry condition, but was greater in age group 20–30 yr (279 ± 10 W) compared with age groups 45–49 (248 ± 8 W), 50–54 (242 ± 6 W), and 55–70 yr (240 ± 7 W) in the humid condition. As a result of a reduced rate of heat dissipation predominantly during exercise, age groups 40–70 yr stored between 60–85 and 13–38% more heat than age group 20–30 yr in the dry and humid conditions, respectively. These age-related differences in heat dissipation and heat storage were not paralleled by significant differences in local sweating and skin blood flow, or by differences in core temperature between groups. From a whole body perspective, combined heat and humidity impeded heat dissipation to a similar extent across age groups, but, more importantly, intermittent exercise in dry and humid heat stress conditions created a greater thermoregulatory challenge for middle-aged and older adults. PMID:24812643

  18. 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.

  19. Anomaly transform methods based on total energy and ocean heat content norms for generating ocean dynamic disturbances for ensemble climate forecasts

    NASA Astrophysics Data System (ADS)

    Romanova, Vanya; Hense, Andreas

    2015-04-01

    In our study we use the anomaly transform, a special case of ensemble transform method, in which a selected set of initial oceanic anomalies in space, time and variables are defined and orthogonalized. The resulting orthogonal perturbation patterns are designed such that they pick up typical balanced anomaly structures in space and time and between variables. The metric used to set up the eigen problem is taken either as the weighted total energy with its zonal, meridional kinetic and available potential energy terms having equal contributions, or the weighted ocean heat content in which a disturbance is applied only to the initial temperature fields. The choices of a reference state for defining the initial anomalies are such that either perturbations on seasonal timescales and or on interannual timescales are constructed. These project a-priori only the slow modes of the ocean physical processes, such that the disturbances grow mainly in the Western Boundary Currents, in the Antarctic Circumpolar Current and the El Nino Southern Oscillation regions. An additional set of initial conditions is designed to fit in a least square sense data from global ocean reanalysis. Applying the AT produced sets of disturbances to oceanic initial conditions initialized by observations of the MPIOM-ESM coupled model on T63L47/GR15 resolution, four ensemble and one hind-cast experiments were performed. The weighted total energy norm is used to monitor the amplitudes and rates of the fastest growing error modes. The results showed minor dependence of the instabilities or error growth on the selected metric but considerable change due to the magnitude of the scaling amplitudes of the perturbation patterns. In contrast to similar atmospheric applications, we find an energy conversion from kinetic to available potential energy, which suggests a different source of uncertainty generation in the ocean than in the atmosphere mainly associated with changes in the density field.

  20. 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.

  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. 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. 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

  5. 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.

  6. 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)

  7. Holonomy anomalies

    SciTech Connect

    Bagger, J.; Nemeschansky, D.; Yankielowicz, S.

    1985-05-01

    A new type of anomaly is discussed that afflicts certain non-linear sigma models with fermions. This anomaly is similar to the ordinary gauge and gravitational anomalies since it reflects a topological obstruction to the reparametrization invariance of the quantum effective action. Nonlinear sigma models are constructed based on homogeneous spaces G/H. Anomalies arising when the fermions are chiral are shown to be cancelled sometimes by Chern-Simons terms. Nonlinear sigma models are considered based on general Riemannian manifolds. 9 refs. (LEW)

  8. Development of a self-priming high-capacity heat pipe for flight on OAO-C.

    NASA Technical Reports Server (NTRS)

    Edelstein, F.; Swerdling, B.; Kosson, R.

    1972-01-01

    This paper describes the development of a 0.500-inch OD heat pipe with a spiral artery designed to fill under surface tension forces in a one-g field. Capacities in excess of 12,000 watt-inches have been achieved with ammonia as the working fluid. The paper presents the analysis, design, and test of the three-foot-long development models. Also included are some design and fabrication details, along with qualification ground test data for a 12-foot-long spiral artery isothermalizer type heat pipe that is installed on the Orbiting Astronomical Observatory C Model scheduled for launch in 1972.

  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. 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

  11. 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.

  12. A method for determination of heat storage capacity of the mold materials using a differential thermal analysis

    NASA Astrophysics Data System (ADS)

    Ol'khovik, E.

    2016-04-01

    The article proposes a method for determining of the heat storage capacity of the mould materials. Modern materials for mouldsare made using a variety of technologies, and the manufacturers of binders and additives ensure thermal properties of certain materials only when using a certain recipe. In practice, for management of the casting solidification process (creation of the volume or directed mode) it is favorable to apply various technological methods, including modification of one of the important properties of the casting mould, which is heat storage capacity. A rather simple technique based on the application of the differential thermal analysis was developed for its experimental definition. The obtained data showed a possibility of industrial application of the method.

  13. 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.

  14. 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…

  15. 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.

  16. Influence of Heat Treatment on Structure and Charge Capacity of Sol-Gel Produced TiO2 Films

    NASA Astrophysics Data System (ADS)

    Özdemir, Orhan; Gökdemir, Fatma Pınar; Keskin, Bahadır; Kutlu, Kubilay

    Titanium dioxide thin films were synthesized by sol-gel route from titanium isopropoxide (TIP) with acetic acid. Prior to the heat treatment, the films were amorphous phase. Above 400 °C, phase transition took place from amorphous into anatase phase. Electrochromic properties of each phase indicated reversible coloration upon Li+ ion intercalation in cyclic voltammetric measurements. Nevertheless, both charge capacity and energy band gap of films begun to decrease with increase in annealing temperature due to the crystallization.

  17. Bangui Anomaly

    NASA Technical Reports Server (NTRS)

    Taylor, Patrick T.

    2004-01-01

    Bangui anomaly is the name given to one of the Earth s largest crustal magnetic anomalies and the largest over the African continent. It covers two-thirds of the Central African Republic and therefore the name derives from the capitol city-Bangui that is also near the center of this feature. From surface magnetic survey data Godivier and Le Donche (1962) were the first to describe this anomaly. Subsequently high-altitude world magnetic surveying by the U.S. Naval Oceanographic Office (Project Magnet) recorded a greater than 1000 nT dipolar, peak-to-trough anomaly with the major portion being negative (figure 1). Satellite observations (Cosmos 49) were first reported in 1964, these revealed a 40nT anomaly at 350 km altitude. Subsequently the higher altitude (417-499km) POGO (Polar Orbiting Geomagnetic Observatory) satellite data recorded peak-to-trough anomalies of 20 nT these data were added to Cosmos 49 measurements by Regan et al. (1975) for a regional satellite altitude map. In October 1979, with the launch of Magsat, a satellite designed to measure crustal magnetic anomalies, a more uniform satellite altitude magnetic map was obtained. These data, computed at 375 km altitude recorded a -22 nT anomaly (figure 2). This elliptically shaped anomaly is approximately 760 by 1000 km and is centered at 6%, 18%. The Bangui anomaly is composed of three segments; there are two positive anomalies lobes north and south of a large central negative field. This displays the classic pattern of a magnetic anomalous body being magnetized by induction in a zero inclination field. This is not surprising since the magnetic equator passes near the center of this body.

  18. Housing, heat stress and health in a changing climate: promoting the adaptive capacity of vulnerable households, a suggested way forward.

    PubMed

    Maller, Cecily J; Strengers, Yolande

    2011-12-01

    In many places extreme heat causes more deaths than floods, cyclones and bushfires. However, efforts to manage the health implications of heat and increase the adaptive capacity of vulnerable populations are in their infancy, requiring urgent attention from research and policy. This paper presents a case for research exploring the influence of social and contextual factors on vulnerable populations' capacity to adapt to heat in the context of climate change. We argue such research is imperative given current prioritization of short-sighted policy solutions such as installation and use of greenhouse-intensive domestic air-conditioners as moderators of heat stress. Globally, vulnerability to heat stress is most often assessed by epidemiological analysis of past morbidity and mortality data; yet a range of other factors need to be accounted for in interpreting and understanding these patterns of ill-health and loss of life, and further in determining how vulnerability is created, exacerbated and alleviated by broader societal conditions. Such factors include: the cooling technologies and infrastructures available to householders, practical knowledge about how to moderate heat stress, and social and cultural understandings of comfort and vulnerability. To investigate these factors, new methodologies are required. Social practice theory, which conceptualizes the dynamic interactions between individuals and wider systems of power, infrastructure, technologies, society and culture as components of practices such as household cooling, is presented as a way forward. The development of a practice-based methodology and conceptual framework to understand adaptation to heat will provide a multidimensional, systems-oriented understanding of how vulnerability can potentially be reduced. PMID:21307023

  19. 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.

  20. 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.

  1. 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.

  2. A complete carbon-nanotube-based on-chip cooling solution with very high heat dissipation capacity

    NASA Astrophysics Data System (ADS)

    Fu, Yifeng; Nabiollahi, Nabi; Wang, Teng; Wang, Shun; Hu, Zhili; Carlberg, Björn; Zhang, Yan; Wang, Xiaojing; Liu, Johan

    2012-02-01

    Heat dissipation is one of the factors limiting the continuous miniaturization of electronics. In the study presented in this paper, we designed an ultra-thin heat sink using carbon nanotubes (CNTs) as micro cooling fins attached directly onto a chip. A metal-enhanced CNT transfer technique was utilized to improve the interface between the CNTs and the chip surface by minimizing the thermal contact resistance and promoting the mechanical strength of the microfins. In order to optimize the geometrical design of the CNT microfin structure, multi-scale modeling was performed. A molecular dynamics simulation (MDS) was carried out to investigate the interaction between water and CNTs at the nanoscale and a finite element method (FEM) modeling was executed to analyze the fluid field and temperature distribution at the macroscale. Experimental results show that water is much more efficient than air as a cooling medium due to its three orders-of-magnitude higher heat capacity. For a hotspot with a high power density of 5000 W cm-2, the CNT microfins can cool down its temperature by more than 40 °C. The large heat dissipation capacity could make this cooling solution meet the thermal management requirement of the hottest electronic systems up to date.

  3. A complete carbon-nanotube-based on-chip cooling solution with very high heat dissipation capacity.

    PubMed

    Fu, Yifeng; Nabiollahi, Nabi; Wang, Teng; Wang, Shun; Hu, Zhili; Carlberg, Björn; Zhang, Yan; Wang, Xiaojing; Liu, Johan

    2012-02-01

    Heat dissipation is one of the factors limiting the continuous miniaturization of electronics. In the study presented in this paper, we designed an ultra-thin heat sink using carbon nanotubes (CNTs) as micro cooling fins attached directly onto a chip. A metal-enhanced CNT transfer technique was utilized to improve the interface between the CNTs and the chip surface by minimizing the thermal contact resistance and promoting the mechanical strength of the microfins. In order to optimize the geometrical design of the CNT microfin structure, multi-scale modeling was performed. A molecular dynamics simulation (MDS) was carried out to investigate the interaction between water and CNTs at the nanoscale and a finite element method (FEM) modeling was executed to analyze the fluid field and temperature distribution at the macroscale. Experimental results show that water is much more efficient than air as a cooling medium due to its three orders-of-magnitude higher heat capacity. For a hotspot with a high power density of 5000 W cm(-2), the CNT microfins can cool down its temperature by more than 40 °C. The large heat dissipation capacity could make this cooling solution meet the thermal management requirement of the hottest electronic systems up to date. PMID:22222357

  4. INTEGRATION OF HEAT CAPACITY AND ELECTRICAL CONDUCTIVITY SENSORS FOR ROOT MODULE WATER AND NUTRIENT ASSESSMENT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of water content and nutrient status during space flight is a critical necessity in plant production systems. Our objectives were to determine if dual-probe heat pulse sensors could improve water content determination accuracy over single-probe heat-pulse sensors, and to test a design usi...

  5. 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

  6. 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

  7. Investigation of heat transfer in high-capacity power transformers having modifications preventing explosions

    NASA Astrophysics Data System (ADS)

    Aksenov, A. A.; Zhluktov, S. V.; Kudimov, N. F.; Son, E. E.; Savitskii, D. V.; Tretiyakova, O. N.; Shishaeva, A. S.

    2014-12-01

    Results of numerical simulation of complex conjugate heat transfer in a high power electric transformer are presented. Simulation of the flow and heat transfer inside a transformer with static blast protection was carried out. Analysis of test calculations performed in the FlowVision software suit was carried out. Comparison of the performance of created numerical model against the real experimental data from the thermal tests of the transformer was made.

  8. Heat-treated Escherichia coli as a high-capacity biosorbent for tungsten anions.

    PubMed

    Ogi, Takashi; Makino, Takahiko; Iskandar, Ferry; Tanabe, Eishi; Okuyama, Kikuo

    2016-10-01

    Adsorption performance in the biosorption of tungsten using Escherichia coli cells can be significantly improved by using cell suspensions that have been heat-treated at ⩽100°C. In the case of E. coli cells suspension heated at 100°C, the aqueous tungsten ions concentration rapidly decreased from 0.8mmol/L to practically zero within 1h. This biosorption time is much shorter than that of non-heat treated E. coli cells (7h). Furthermore, the adsorption saturation amount for cells heat-treated at 100°C was significantly increased up to 1.62mmol-W/g-E. coli compared to the unheated E. coli cells case (0.62mmol-W/g-E. coli). Determination of the surface potential and surface structure along with quantitative analyses of free amino acids of heat-treated E. coli cells were also carried out and revealed that heated cells have a high zeta potential and express a higher concentration of amino acids on the cell surface. PMID:27359063

  9. Avian thermoregulation in the heat: scaling of heat tolerance and evaporative cooling capacity in three southern African arid-zone passerines.

    PubMed

    Whitfield, Maxine C; Smit, Ben; McKechnie, Andrew E; Wolf, Blair O

    2015-06-01

    Many birds can defend body temperature (Tb) far below air temperature (Ta) during acute heat exposure, but relatively little is known about how avian heat tolerance and evaporative cooling capacity varies with body mass (Mb), phylogeny or ecological factors. We determined maximum rates of evaporative heat dissipation and thermal end points (Tb and Ta associated with thermoregulatory failure) in three southern African ploceid passerines, the scaly-feathered weaver (Sporopipes squamifrons, Mb≈10 g), sociable weaver (Philetairus socius, Mb≈25 g) and white-browed sparrow-weaver (Plocepasser mahali, Mb≈40 g). Birds were exposed to a ramped profile of progressively increasing Ta, with continuous monitoring of behaviour and Tb used to identify the onset of severe hyperthermia. The maximum Ta birds tolerated ranged from 48°C to 54°C, and was positively related to Mb. Values of Tb associated with severe heat stress were in the range of 44 to 45°C. Rates of evaporative water loss (EWL) increased rapidly when Ta exceeded Tb, and maximum evaporative heat dissipation was equivalent to 141-222% of metabolic heat production. Fractional increases in EWL between Ta<40°C and the highest Ta reached by each species were 10.8 (S. squamifrons), 18.4 (P. socius) and 16.0 (P. mahali). Resting metabolic rates increased more gradually with Ta than expected, probably reflecting the very low chamber humidity values we maintained. Our data suggest that, within a taxon, larger species can tolerate higher Ta during acute heat stress. PMID:26041032

  10. Energy savings in one-pipe steam heating systems fitted with high-capacity air vents. Final report

    SciTech Connect

    Not Available

    1994-09-01

    Multifamily buildings heated by one-pipe steam systems experience significant temperature gradients from apartment to apartment, often reaching 15{degrees}F. As a result, many tenants are to cold, or if the heating system output is increased so as to heat the coldest apartment adequately, too hot. While both are undesirable, the second is particularly so because it wastes energy. It was thought that insufficient air venting of the steam pipes contributed to the gradient. Theoretically, if steam mains and risers are quickly vented, steam will reach each radiator at approximately the same time and balance apartment temperatures. The project`s objective was to determine if the installation of large-capacity air vents at the ends of steam mains and risers would economically reduce the temperature gradient between apartments and reduce the amount of space heating energy required. The test was conducted by enabling and disabling air vents biweekly in 10 multifamily buildings in New York City between December 1992 to May 1993. The temperatures of selected apartments and total space heating energy were compared during each venting regime. There was no difference in energy consumption between ``vents on`` and ``vents off`` periods (see Tables 2 and 5); however, there was a reduction in the maximum spread of apartment temperatures.

  11. Study on Fuel Cell Network System Considering Reduction in Fuel Cell Capacity Using Load Leveling and Heat Release Loss

    NASA Astrophysics Data System (ADS)

    Obara, Shin'ya; Kudo, Kazuhiko

    Reduction in fuel cell capacity linked to a fuel cell network system is considered. When the power demand of the whole network is small, some of the electric power generated by the fuel cell is supplied to a water electrolysis device, and hydrogen and oxygen gases are generated. Both gases are compressed with each compressor and they are stored in cylinders. When the electric demand of the whole network is large, both gases are supplied to the network, and fuel cells are operated by these hydrogen and oxygen gases. Furthermore, an optimization plan is made to minimize the quantity of heat release of the hot water piping that connects each building. Such an energy network is analyzed assuming connection of individual houses, a hospital, a hotel, a convenience store, an office building, and a factory. Consequently, compared with the conventional system, a reduction of 46% of fuel cell capacity is expected.

  12. 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.

  13. Polymer alloys with balanced heat storage capacity and engineering attributes and applications thereof

    DOEpatents

    Soroushian, Parviz

    2002-01-01

    A thermoplastic polymer of relatively low melt temperature is blended with at least one of thermosets, elastomers, and thermoplastics of relatively high melt temperature in order to produce a polymer blend which absorbs relatively high quantities of latent heat without melting or major loss of physical and mechanical characteristics as temperature is raised above the melting temperature of the low-melt-temperature thermoplastic. The polymer blend can be modified by the addition of at least one of fillers, fibers, fire retardants, compatibilisers, colorants, and processing aids. The polymer blend may be used in applications where advantage can be taken of the absorption of excess heat by a component which remains solid and retains major fractions of its physical and mechanical characteristics while absorbing relatively high quantities of latent heat.

  14. 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
  15. 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

  16. 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

  17. 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).

  18. 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

  19. 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

  20. 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.

    1. Labworks and the Kundt's Tube: A New Way to Determine the Heat Capacities of Gases

      ERIC Educational Resources Information Center

      Bryant, Philip A.; Morgan, Matthew E.

      2004-01-01

      The potency of heat in gases is measured by the application of a computer and the LabWorks interaction, while the speed of sound in gases is determined by an instrument called Kundt's tube. This unique and accurate procedure is repeatable, and greatly reduces data acquisition time.

    2. Heat capacity measurements of alkali, endohedral, and higher fullerene thin films

      NASA Astrophysics Data System (ADS)

      Allen, Kimberly Jo

      Using a novel microcalorimeter, we have measured the specific heat of C60 and K3C60 thin films from 6--400 K. The results can be understood by analyzing the phonon modes; the electronic specific heat of K3C60 is shown to be a small fraction of the total. While C60 shows a clear separation of energy levels between inter- and intraball modes, the added alkali modes in K3C 60 blur this separation because they appear in the gap. Additionally, the acoustic modes of K3C60 actually soften compared to pure C60. We have also performed the first specific heat measurements of C84, Sc2 C84, C82, and La C 82 (10--300 K), and we analyze these results using a similar framework. C84 compares easily to C60 with a clear separation between inter- and intraball modes. For Sc2 C84, in contrast to K 3C60, the added optical modes due to the metal atoms are high-energy Einstein modes comparable to the on-ball modes. Thus, the specific heat of Sc2 C84 is very similar to that of C84; and likewise, Cp of La C82 resembles that of C82. Remarkably, however, C82 contrasts sharply with the other empty fullerenes in that it shows no separation of energy levels between inter- and intraball modes. We speculate about possible causes of this anomalous behavior.

    3. IMP improves water-holding capacity, physical and sensory properties of heat-induced gels from porcine meat.

      PubMed

      Nakamura, Yukinobu; Migita, Koshiro; Okitani, Akihiro; Matsuishi, Masanori

      2014-05-01

      Water-holding capacity (WHC) of heat-induced pork gels was examined. The heat-induced gels were obtained from meat homogenates prepared by adding nine volumes of 0.3-0.5 mol/L NaCl solutions containing 9-36 mmol/L disodium inosine-5'-monophosphate (IMP) or 9 mmol/L tetrapotassium pyrophosphate (KPP) to minced pork. IMP at 36 mmol/L enhanced the WHC to the same level as attained by KPP. Physical and sensory properties of heat-induced gels were also examined. The heat-induced gels were prepared from porcine meat homogenates containing 0.3 mol/L NaCl and 9-36 mmol/L IMP or 9 mmol/L KPP. IMP at 36 mmol/L enhanced the values of hardness, cohesiveness, gumminess and springiness, measured with a Tensipresser, and several organoleptic scores to the same level as the score attained by KPP. Thus, it is concluded that IMP is expected to be a practical substitute for pyrophosphates to improve the quality of sausages. PMID:24428177

    4. Specific heat capacity and dendritic growth kinetics of liquid peritectic Fe-Cu alloys

      NASA Astrophysics Data System (ADS)

      Xia, Z. C.; Wang, W. L.; Luo, S. B.; Wei, B.

      2016-08-01

      The specific heat and dendritic growth of highly undercooled peritectic Fe-Cu alloys were investigated by electromagnetic levitation technique. The specific heat values of liquid peritectic Fe92.8Cu7.2 and hyperperitectic Fe88.5Cu11.5 alloys were determined to be 40.4 and 39.58 J·mol-1·K-1 over wide temperature ranges. The measured growth velocities rose rapidly with increasing undercooling, which reached 69 and 68 m·s-1 at the maximum undercoolings of 401 K (0.23 TL) and 468 K (0.27 TL). The microstructures of peritectic Fe-Cu alloys were refined significantly with enhanced undercooling. Theoretical analyses showed that almost segregationless solidification was realized if undercooling was sufficiently large.

    5. 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

    6. 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

    7. 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.

    8. 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.

    9. 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

    10. 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.

    11. 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

    12. 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.

    13. 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.

    14. 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

    15. Small heat-shock proteins and leaf cooling capacity account for the unusual heat tolerance of the central spike leaves in Agave tequilana var. Weber.

      PubMed

      Luján, Rosario; Lledías, Fernando; Martínez, Luz María; Barreto, Rita; Cassab, Gladys I; Nieto-Sotelo, Jorge

      2009-12-01

      Agaves are perennial crassulacean acid metabolism (CAM) plants distributed in tropical and subtropical arid environments, features that are attractive for studying the heat-shock response. In agaves, the stress response can be analysed easily during leaf development, as they form a spirally shaped rosette, having the meristem surrounded by folded leaves in the centre (spike) and the unfolded and more mature leaves in the periphery. Here, we report that the spike of Agave tequilana is the most thermotolerant part of the rosette withstanding shocks of up to 55 degrees C. This finding was inconsistent with the patterns of heat-shock protein (Hsp) gene expression, as maximal accumulation of Hsp transcripts was at 44 degrees C in all sectors (spike, inner, middle and outer). However, levels of small HSP (sHSP)-CI and sHSP-CII proteins were conspicuously higher in spike leaves at all temperatures correlating with their thermotolerance. In addition, spike leaves showed a higher stomatal density and abated more efficiently their temperature several degrees below that of air. We propose that the greater capacity for leaf cooling during the day in response to heat stress, and the elevated levels of sHSPs, constitute part of a set of strategies that protect the SAM and folded leaves of A. tequilana from high temperatures. PMID:19703117

    16. 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.

    17. 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

    18. Capillary priming characteristics of a high capacity dual passage heat pipe

      NASA Technical Reports Server (NTRS)

      Peterson, G. P.

      1982-01-01

      A parametric study of the forces governing the liquid-vapor interface was performed for the purpose of determining the capillary priming characteristics of Grumman's dual passage monogroove heat pipe when subjected to low-g or zero-g conditions. The static liquid-vapor interface configuration was determined through minimization of the free surface energies and a mathematical model and computer program which describe the time to prime was developed. Modeling predictions confirmed expectations of proper priming action and established the criteria for sizing of the liquid and vapor channels.

    19. DOWN'S ANOMALY.

      ERIC Educational Resources Information Center

      PENROSE, L.S.; SMITH, G.F.

      BOTH CLINICAL AND PATHOLOGICAL ASPECTS AND MATHEMATICAL ELABORATIONS OF DOWN'S ANOMALY, KNOWN ALSO AS MONGOLISM, ARE PRESENTED IN THIS REFERENCE MANUAL FOR PROFESSIONAL PERSONNEL. INFORMATION PROVIDED CONCERNS (1) HISTORICAL STUDIES, (2) PHYSICAL SIGNS, (3) BONES AND MUSCLES, (4) MENTAL DEVELOPMENT, (5) DERMATOGLYPHS, (6) HEMATOLOGY, (7)…

    20. 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.

    1. Specific heat analysis of the low temperature anomalies in orthorhombic PrBa2Cu3O6+ x (x = 1; x = 0.95) compounds

      NASA Astrophysics Data System (ADS)

      Lahoubi, M.

      2016-03-01

      The specific heat Cp(T) and entropy S(T) properties of the orthorhombic PrBa2Cu3O6+x compounds in two states of oxygen concentration x, an over doped (OV) with x = 1 and an optimally doped (OP) with x = 0.95 are reanalyzed below the Néel temperature of the antiferromagnetic ordering of the Pr sublattice T N = 17.5 and 14 K, respectively. Two simultaneous anomalies for both states are observed. The first one occurs near the previous spin reorientation phase transition temperature T 2 ∼ 11.5 and ∼ 9-10 K, respectively whereas the second one remains close to the so called low-critical temperature Tcr ∼ 4-5 K for the OV state as it has been reported before for the OP state. By fitting the C p(T)/T data to A{T 2}-3/2 + γ + C{T 2}1 + D{T1}2 for T < T cr the four coefficients obtained with the best adjusted A-squared values are compared with previous findings. Reduced values for y are confirmed in this work. The results which are well described by the contribution of the DT 5 term to Cp(T) can be connected with the previous Pr-Cu(2) magnetic coupling that is sufficiently enough to cause a modest spin reorientation phase transition at T2 and a critical magnetic behaviour below Tcr .

    2. Effect of heat processing on the profile of pigments and antioxidant capacity of green and red jalapeño peppers.

      PubMed

      Cervantes-Paz, Braulio; Yahia, Elhadi M; Ornelas-Paz, José de Jesús; Gardea-Béjar, Alfonso A; Ibarra-Junquera, Vrani; Pérez-Martínez, Jaime D

      2012-10-31

      Raw and heat-processed jalapeño peppers (green and red) were evaluated for their pigment profile and antioxidant capacity. Sixty-seven pigments were separated and characterized by HPLC-DAD-MS, including carotenoids (isomers and esters), chlorophylls, and pheophytins. The distinctive characteristics of this pepper genotype were the presence of antheraxanthin monoesters, zeaxanthin monoesters, mutatoxanthin diesters, and a higher content of free capsanthin relative to the mono- and diesterified forms. Chlorophyll a and free all-trans-lutein were the major pigments in raw green peppers, whereas free all-trans-capsanthin was the most abundant pigment in raw red peppers. Twelve compounds were generated by the heat treatments, mainly pheophytins and cis isomers of carotenoids. Heat treatments affected differentially the concentration of individual pigments. Red peppers showed a higher antioxidant capacity than green fruits. Heating caused minor changes in the antioxidant capacity of peppers. PMID:23050605

    3. 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

    4. Limits to sustained energy intake. XXIII. Does heat dissipation capacity limit the energy budget of lactating bank voles?

      PubMed

      Sadowska, Edyta T; Król, Elżbieta; Chrzascik, Katarzyna M; Rudolf, Agata M; Speakman, John R; Koteja, Paweł

      2016-03-01

      Understanding factors limiting sustained metabolic rate (SusMR) is a central issue in ecological physiology. According to the heat dissipation limit (HDL) theory, the SusMR at peak lactation is constrained by the maternal capacity to dissipate body heat. To test that theory, we shaved lactating bank voles (Myodes glareolus) to experimentally elevate their capacity for heat dissipation. The voles were sampled from lines selected for high aerobic exercise metabolism (A; characterized also by increased basal metabolic rate) and unselected control lines (C). Fur removal significantly increased the peak-lactation food intake (mass-adjusted least square means ± s.e.; shaved: 16.3 ± 0.3 g day(-1), unshaved: 14.4 ± 0.2 g day(-1); P<0.0001), average daily metabolic rate (shaved: 109 ± 2 kJ day(-1), unshaved: 97 ± 2 kJ day(-1); P<0.0001) and metabolisable energy intake (shaved: 215 ± 4 kJ day(-1), unshaved: 185 ± 4 kJ day(-1); P<0.0001), as well as the milk energy output (shaved: 104 ± 4 kJ day(-1); unshaved: 93 ± 4 kJ day(-1); P=0.021) and litter growth rate (shaved: 9.4 ± 0.7 g 4 days(-1), unshaved: 7.7 ± 0.7 g 4 days(-1); P=0.028). Thus, fur removal increased both the total energy budget and reproductive output at the most demanding period of lactation, which supports the HDL theory. However, digestive efficiency was lower in shaved voles (76.0 ± 0.3%) than in unshaved ones (78.5 ± 0.2%; P<0.0001), which may indicate that a limit imposed by the capacity of the alimentary system was also approached. Shaving similarly affected the metabolic and reproductive traits in voles from the A and C lines. Thus, the experimental evolution model did not reveal a difference in the limiting mechanism between animals with inherently different metabolic rates. PMID:26747907

    5. 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.

    6. 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

    7. Zeolite Y adsorbents with high vapor uptake capacity and robust cycling stability for potential applications in advanced adsorption heat pumps

      SciTech Connect

      Li, XS; Narayanan, S; Michaelis, VK; Ong, TC; Keeler, EG; Kim, H; Mckay, IS; Griffin, RG; Wang, EN

      2015-01-01

      Modular and compact adsorption heat pumps (AHPs) promise an energy-efficient alternative to conventional vapor compression based heating, ventilation and air conditioning systems. A key element in the advancement of AHPs is the development of adsorbents with high uptake capacity, fast intracrystalline diffusivity and durable hydrothermal stability. Herein, the ion exchange of NaY zeolites with ingoing Mg2+ ions is systematically studied to maximize the ion exchange degree (IED) for improved sorption performance. It is found that beyond an ion exchange threshold of 64.1%, deeper ion exchange does not benefit water uptake capacity or characteristic adsorption energy, but does enhance the vapor diffusivity. In addition to using water as an adsorbate, the uptake properties of Mg, Na-Y zeolites were investigated using 20 wt.% MeOH aqueous solution as a novel anti-freeze adsorbate, revealing that the MeOH additive has an insignificant influence on the overall sorption performance. We also demonstrated that the lab-scale synthetic scalability is robust, and that the tailored zeolites scarcely suffer from hydrothermal stability even after successive 108-fold adsorption/desorption cycles. The samples were analyzed using N-2 sorption, Al-27/Si-29 MAS NMR spectroscopy, ICP-AES, dynamic vapor sorption, SEM, Fick's 2nd law and D-R equation regressions. Among these, close examination of sorption isotherms for H2O and N-2 adsorbates allows us to decouple and extract some insightful information underlying the complex water uptake phenomena. This work shows the promising performance of our modified zeolites that can be integrated into various AHP designs for buildings, electronics, and transportation applications. (C) 2014 Elsevier Inc. All rights reserved.

    8. Zeolite Y Adsorbents with High Vapor Uptake Capacity and Robust Cycling Stability for Potential Applications in Advanced Adsorption Heat Pumps

      PubMed Central

      Li, Xiansen; Narayanan, Shankar; Michaelis, Vladimir K.; Ong, Ta-Chung; Keeler, Eric G.; Kim, Hyunho; McKay, Ian S.; Griffin, Robert G.; Wang, Evelyn N.

      2014-01-01

      Modular and compact adsorption heat pumps (AHPs) promise an energy-efficient alternative to conventional vapor compression based heating, ventilation and air conditioning systems. A key element in the advancement of AHPs is the development of adsorbents with high uptake capacity, fast intracrystalline diffusivity and durable hydrothermal stability. Herein, the ion exchange of NaY zeolites with ingoing Mg2+ ions is systematically studied to maximize the ion exchange degree (IED) for improved sorption performance. It is found that beyond an ion exchange threshold of 64.1%, deeper ion exchange does not benefit water uptake capacity or characteristic adsorption energy, but does enhance the vapor diffusivity. In addition to using water as an adsorbate, the uptake properties of Mg,Na-Y zeolites were investigated using 20 wt.% MeOH aqueous solution as a novel anti-freeze adsorbate, revealing that the MeOH additive has an insignificant influence on the overall sorption performance. We also demonstrated that the labscale synthetic scalability is robust, and that the tailored zeolites scarcely suffer from hydrothermal stability even after successive 108-fold adsorption/desorption cycles. The samples were analyzed using N2 sorption, 27Al/29Si MAS NMR spectroscopy, ICP-AES, dynamic vapor sorption, SEM, Fick’s 2nd law and D-R equation regressions. Among these, close examination of sorption isotherms for H2O and N2 adsorbates allows us to decouple and extract some insightful information underlying the complex water uptake phenomena. This work shows the promising performance of our modified zeolites that can be integrated into various AHP designs for buildings, electronics, and transportation applications. PMID:25395877

    9. Zeolite Y Adsorbents with High Vapor Uptake Capacity and Robust Cycling Stability for Potential Applications in Advanced Adsorption Heat Pumps.

      PubMed

      Li, Xiansen; Narayanan, Shankar; Michaelis, Vladimir K; Ong, Ta-Chung; Keeler, Eric G; Kim, Hyunho; McKay, Ian S; Griffin, Robert G; Wang, Evelyn N

      2015-01-01

      Modular and compact adsorption heat pumps (AHPs) promise an energy-efficient alternative to conventional vapor compression based heating, ventilation and air conditioning systems. A key element in the advancement of AHPs is the development of adsorbents with high uptake capacity, fast intracrystalline diffusivity and durable hydrothermal stability. Herein, the ion exchange of NaY zeolites with ingoing Mg(2+) ions is systematically studied to maximize the ion exchange degree (IED) for improved sorption performance. It is found that beyond an ion exchange threshold of 64.1%, deeper ion exchange does not benefit water uptake capacity or characteristic adsorption energy, but does enhance the vapor diffusivity. In addition to using water as an adsorbate, the uptake properties of Mg,Na-Y zeolites were investigated using 20 wt.% MeOH aqueous solution as a novel anti-freeze adsorbate, revealing that the MeOH additive has an insignificant influence on the overall sorption performance. We also demonstrated that the labscale synthetic scalability is robust, and that the tailored zeolites scarcely suffer from hydrothermal stability even after successive 108-fold adsorption/desorption cycles. The samples were analyzed using N2 sorption, (27)Al/(29)Si MAS NMR spectroscopy, ICP-AES, dynamic vapor sorption, SEM, Fick's 2(nd) law and D-R equation regressions. Among these, close examination of sorption isotherms for H2O and N2 adsorbates allows us to decouple and extract some insightful information underlying the complex water uptake phenomena. This work shows the promising performance of our modified zeolites that can be integrated into various AHP designs for buildings, electronics, and transportation applications. PMID:25395877

    10. 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

    11. 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

    12. 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

    13. 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.

    14. Chemical forces and water holding capacity study of heat-induced myofibrillar protein gel as affected by high pressure.

      PubMed

      Zhang, Ziye; Yang, Yuling; Tang, Xiaozhi; Chen, Yinji; You, Yuan

      2015-12-01

      The effects of high pressure (100-500 MPa) on chemical forces and water holding capacity of heat-induced myofibrillar protein (MP) gel were investigated. As pressure increased, total sulfhydryl (SH) group content decreased and absolute value of zeta potential increased, which suggested the formation of disulfide bonds and increased the strength of electrostatic repulsion. Surface hydrophobicity and normalized intensity of the 760 cm(-1) band showed a maximum value at 200 MPa, indicating that 200 MPa was the optimum pressure for hydrophobic interactions. Hydrogen bonding of MP gel was strengthened at pressures of 300 MPa and above. Bound water (T2b) had lower water mobility and was more closely associated with proteins. Free water (T22) had higher water mobility. More free water was attracted by proteins or trapped in gel structure, and transferred to bound or immobilized water as pressure increased. A value of 200 MPa was the optimum pressure for the water holding capacity of MP gel. PMID:26041172

    15. Heat capacity of quantum adsorbates: Hydrogen and helium on evaporated gold films

      SciTech Connect

      Birmingham, J.T. |

      1996-06-01

      The author has constructed an apparatus to make specific heat measurements of quantum gases adsorbed on metallic films at temperatures between 0.3 and 4 K. He has used this apparatus to study quench-condensed hydrogen films between 4 and 923 layers thick with J = 1 concentrations between 0.28 and 0.75 deposited on an evaporated gold surface. He has observed that the orientational ordering of the J = 1 molecules depends on the substrate temperature during deposition of the hydrogen film. He has inferred that the density of the films condensed at the lowest temperatures is 25% higher than in bulk H{sub 2} crystals and have observed that the structure of those films is affected by annealing at 3.4 K. The author has measured the J = 1 to J = 0 conversion rate to be comparable to that of the bulk for thick films; however, he found evidence that the gold surface catalyzes conversion in the first two to four layers. He has also used this apparatus to study films of {sup 4}He less than one layer thick adsorbed on an evaporated gold surface. He shows that the phase diagram of the system is similar to that for {sup 4}He/graphite although not as rich in structure, and the phase boundaries occur at different coverages and temperatures. At coverages below about half a layer and at sufficiently high temperatures, the {sup 4}He behaves like a two-dimensional noninteracting Bose gas. At lower temperatures and higher coverages, liquidlike and solidlike behavior is observed. The Appendix shows measurements of the far-infrared absorptivity of the high-{Tc} superconductor La{sub 1.87}Sr{sub 0.13}CuO{sub 4}.

    16. Synergistic Utilization of Microwave Satellite Data and GRACE-Total Water Storage Anomaly for Improving Available Water Capacity Prediction in Lower Mekong Basin

      NASA Astrophysics Data System (ADS)

      Gupta, M.; Bolten, J. D.; Lakshmi, V.

      2015-12-01

      The Mekong River is the longest river in Southeast Asia and the world's eighth largest in discharge with draining an area of 795,000 km² from the eastern watershed of the Tibetan Plateau to the Mekong Delta including three provinces of China, Myanmar, Lao PDR, Thailand, Cambodia and Viet Nam. This makes the life of people highly vulnerable to availability of the water resources as soil moisture is one of the major fundamental variables in global hydrological cycles. The day-to-day variability in soil moisture on field to global scales is an important quantity for early warning systems for events like flooding and drought. In addition to the extreme situations the accurate soil moisture retrieval are important for agricultural irrigation scheduling and water resource management. The present study proposes a method to determine the effective soil hydraulic parameters directly from information available for the soil moisture state from the recently launched SMAP (L-band) microwave remote sensing observations. Since the optimized parameters are based on the near surface soil moisture information, further constraints are applied during the numerical simulation through the assimilation of GRACE Total Water Storage (TWS) within the physically based land surface model. This work addresses the improvement of available water capacity as the soil hydraulic parameters are optimized through the utilization of satellite-retrieved near surface soil moisture. The initial ranges of soil hydraulic parameters are taken in correspondence with the values available from the literature based on FAO. The optimization process is divided into two steps: the state variable are optimized and the optimal parameter values are then transferred for retrieving soil moisture and streamflow. A homogeneous soil system is considered as the soil moisture from sensors such as AMSR-E/SMAP can only be retrieved for the top few centimeters of soil. To evaluate the performance of the system in helping

    17. Avian thermoregulation in the heat: evaporative cooling capacity in an archetypal desert specialist, Burchell's sandgrouse (Pterocles burchelli).

      PubMed

      McKechnie, Andrew E; Smit, Ben; Whitfield, Maxine C; Noakes, Matthew J; Talbot, William A; Garcia, Mateo; Gerson, Alexander R; Wolf, Blair O

      2016-07-15

      Sandgrouse (Pterocliformes) are quintessential examples of avian adaptation to desert environments, but relatively little is known about the limits to their heat tolerance and evaporative cooling capacity. We predicted that evaporative cooling in Burchell's sandgrouse (Pterocles burchelli) is highly efficient and provides the basis for tolerance of very high air temperature (Ta). We measured body temperature (Tb), resting metabolic rate (RMR) and evaporative water loss (EWL) at Ta between 25°C and ∼58°C in birds exposed to successive increments in Ta Normothermic Tb averaged 39.0°C, lower than typical avian values. At Ta>34.5°C, Tb increased linearly to a maximum of 43.6°C at Ta=56°C. The upper critical limit of thermoneutrality (Tuc) was Ta=43.8°C, closely coinciding with the onset of panting and gular flutter. Above the Tuc, RMR increased 2.5-fold to 2.89 W at Ta=56°C, a fractional increase far exceeding that of many other species under comparable conditions. Rates of EWL increased rapidly at Ta>42.9°C to 7.84±0.90 g h(-1) at Ta=56°C, an 11-fold increase above minimal levels. Maximum evaporative cooling efficiency (ratio of evaporative heat loss to metabolic heat production) was 2.03, but could be as high as 2.70 if our assumption that the birds were metabolising lipids is incorrect. Thermoregulation at very high Ta in P. burchelli was characterised by large increases in RMR and EWL, and is much less efficient than in taxa such as columbids and caprimulgids. PMID:27207634

    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. Imbalance between oxygen photoreduction and antioxidant capacities in Symbiodinium cells exposed to combined heat and high light stress

      NASA Astrophysics Data System (ADS)

      Roberty, S.; Fransolet, D.; Cardol, P.; Plumier, J.-C.; Franck, F.

      2015-12-01

      During the last decades, coral reefs have been affected by several large-scale bleaching events, and such phenomena are expected to increase in frequency and severity in the future, thus compromising their survival. High sea surface temperature accompanied by high levels of solar irradiance has been found to be responsible for the induction of oxidative stress ultimately ending with the disruption of the symbiosis between cnidarians and Symbiodinium. For two decades, many studies have pointed to the water-water cycle (WWC) as being one of the primary mediators of this phenomenon, but the impacts of environmental stress on the O2 reduction by PSI and the associated reactive oxygen species (ROS)-detoxifying enzymes remain to be determined. In this study, we analyzed the impacts of acute thermal and light stress on the WWC in the model Symbiodinium strain A1. We observed that the high light treatment at 26 °C resulted in the up-regulation of superoxide dismutase, ascorbate peroxidase, and glutathione reductase activities and an increased production of ROS with no significant change in O2-dependent electron transport. Under high light and at 33 °C, O2-dependent electron transport was significantly increased relative to total electron transport. This increase was concomitant with a twofold increase in ROS generation compared with the treatment at 26 °C, while enzymes involved in the WWC were largely inactivated. These data show for the first time that combined heat and light stress inactivate antioxidant capacities of the WWC and suggests that its photoprotective functions are overwhelmed under these conditions. This study also indicates that cnidarians may be more prone to bleach if they harbor Symbiodinium cells having a highly active Mehler-type electron transport, unless they are able to quickly up-regulate their antioxidant capacities.

    1. Relationship between heat-labile enterotoxin secretion capacity and virulence in wild type porcine-origin enterotoxigenic Escherichia coli strains.

      PubMed

      Wijemanne, Prageeth; Xing, Jun; Berberov, Emil M; Marx, David B; Francis, David H; Moxley, Rodney A

      2015-01-01

      Heat-labile enterotoxin (LT) is an important virulence factor secreted by some strains of enterotoxigenic Escherichia coli (ETEC). The prototypic human-origin strain H10407 secretes LT via a type II secretion system (T2SS). We sought to determine the relationship between the capacity to secrete LT and virulence in porcine-origin wild type (WT) ETEC strains. Sixteen WT ETEC strains isolated from cases of severe diarrheal disease were analyzed by GM1ganglioside enzyme-linked immunosorbent assay to measure LT concentrations in culture supernatants. All strains had detectable LT in supernatants by 2 h of culture and 1 strain, which was particularly virulent in gnotobiotic piglets (3030-2), had the highest LT secretion level all porcine-origin WT strains tested (P<0.05). The level of LT secretion (concentration in supernatants at 6-h culture) explained 92% of the variation in time-to-a-moribund-condition (R2 = 0.92, P<0.0001) in gnotobiotic piglets inoculated with either strain 3030-2, or an ETEC strain of lesser virulence (2534-86), or a non-enterotoxigenic WT strain (G58-1). All 16 porcine ETEC strains were positive by PCR analysis for the T2SS genes, gspD and gspK, and bioinformatic analysis of 4 porcine-origin strains for which complete genomic sequences were available revealed a T2SS with a high degree of homology to that of H10407. Maximum Likelihood phylogenetic trees constructed using T2SS genes gspC, gspD, gspE and homologs showed that strains 2534-86 and 3030-2 clustered together in the same clade with other porcine-origin ETEC strains in the database, UMNK88 and UMN18. Protein modeling of the ATPase gene (gspE) further revealed a direct relationship between the predicted ATP-binding capacities and LT secretion levels as follows: H10407, -8.8 kcal/mol and 199 ng/ml; 3030-2, -8.6 kcal/mol and 133 ng/ml; and 2534-86, -8.5 kcal/mol and 80 ng/ml. This study demonstrated a direct relationship between predicted ATP-binding capacity of GspE and LT secretion, and

    2. Relationship between Heat-Labile Enterotoxin Secretion Capacity and Virulence in Wild Type Porcine-Origin Enterotoxigenic Escherichia coli Strains

      PubMed Central

      Wijemanne, Prageeth; Xing, Jun; Berberov, Emil M.; Marx, David B.; Francis, David H.; Moxley, Rodney A.

      2015-01-01

      Heat-labile enterotoxin (LT) is an important virulence factor secreted by some strains of enterotoxigenic Escherichia coli (ETEC). The prototypic human-origin strain H10407 secretes LT via a type II secretion system (T2SS). We sought to determine the relationship between the capacity to secrete LT and virulence in porcine-origin wild type (WT) ETEC strains. Sixteen WT ETEC strains isolated from cases of severe diarrheal disease were analyzed by GM1ganglioside enzyme-linked immunosorbent assay to measure LT concentrations in culture supernatants. All strains had detectable LT in supernatants by 2 h of culture and 1 strain, which was particularly virulent in gnotobiotic piglets (3030-2), had the highest LT secretion level all porcine-origin WT strains tested (P<0.05). The level of LT secretion (concentration in supernatants at 6-h culture) explained 92% of the variation in time-to-a-moribund-condition (R2 = 0.92, P<0.0001) in gnotobiotic piglets inoculated with either strain 3030-2, or an ETEC strain of lesser virulence (2534-86), or a non-enterotoxigenic WT strain (G58-1). All 16 porcine ETEC strains were positive by PCR analysis for the T2SS genes, gspD and gspK, and bioinformatic analysis of 4 porcine-origin strains for which complete genomic sequences were available revealed a T2SS with a high degree of homology to that of H10407. Maximum Likelihood phylogenetic trees constructed using T2SS genes gspC, gspD, gspE and homologs showed that strains 2534-86 and 3030-2 clustered together in the same clade with other porcine-origin ETEC strains in the database, UMNK88 and UMN18. Protein modeling of the ATPase gene (gspE) further revealed a direct relationship between the predicted ATP-binding capacities and LT secretion levels as follows: H10407, -8.8 kcal/mol and 199 ng/ml; 3030-2, -8.6 kcal/mol and 133 ng/ml; and 2534-86, -8.5 kcal/mol and 80 ng/ml. This study demonstrated a direct relationship between predicted ATP-binding capacity of GspE and LT secretion, and

    3. 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.

    4. 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.

    5. 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.

    6. 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.

    7. 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.

    8. 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…

    9. 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.

    10. 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.

    11. 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.

    12. 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.

    13. Gauge anomalies, gravitational anomalies, and superstrings

      SciTech Connect

      Bardeen, W.A.

      1985-08-01

      The structure of gauge and gravitational anomalies will be reviewed. The impact of these anomalies on the construction, consistency, and application of the new superstring theories will be discussed. 25 refs.

    14. Heat shock protein induction by certain chemical stressors is correlated with their cytotoxicity, lipophilicity and protein-denaturing capacity.

      PubMed

      Neuhaus-Steinmetz, U; Rensing, L

      1997-12-01

      Seven agents were analyzed with respect to their ability to induce heat shock protein (HSP) synthesis in C6 rat glioma cells. Induction of HSP synthesis was correlated with cytotoxicity and lipophilicity of the substances. In addition to the first four n-alcohols (methanol, ethanol, propanol and butanol) and phenol, whose capacity to induce HSP was analyzed earlier (Neuhaus-Steinmetz et al., 1994. Mol. Pharmacol. 45, 36-41), isopropanol, 1,4-dinitrophenol (DNP), diethylstilbestrol (DES), carbonylcyanide-m-chlorophenylhydrazone (CCCP), rotenone, paracetamol and acetyl salicylic acid (ASA) induced HSP synthesis after a 1-h incubation at a substance-specific concentration. The maximal induction of HSPs was closely correlated with the cytotoxicity of all substances and occurred when cell viability was reduced to 75 +/- 11% of the controls. Cytotoxicity and the ability to induce HSP were correlated with the lipophilicity of the alcohols, phenol, rotenone and paracetamol. Calculation of the hypothetical membrane concentrations of these compounds yielded a nearly equal value (0.54 +/- 0.13 M), indicating that interaction of substances with lipophilic cellular compounds, such as membranes or lipophilic core regions of proteins, is a critical step leading to HSP induction. This assumption is supported by a correlation between HSP induction and protein denaturation by the different alcohols (Herskovits et al., 1970. J. Biol. Chem. 245, 2588-2598). We assume that the amount of misfolded proteins induced by these lipophilic agents is responsible for the induction of HSP synthesis. ASA, DNP and CCCP induced HSP at lower concentrations than substances with a similar lipophilicity, which may be due to effects which add to the misfolding of proteins or to other signal pathways. PMID:9355937

    15. 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.

    16. ANOMALY STRUCTURE OF SUPERGRAVITY AND ANOMALY CANCELLATION

      SciTech Connect

      Butter, Daniel; Gaillard, Mary K.

      2009-06-10

      We display the full anomaly structure of supergravity, including new D-term contributions to the conformal anomaly. This expression has the super-Weyl and chiral U(1){sub K} transformation properties that are required for implementation of the Green-Schwarz mechanism for anomaly cancellation. We outline the procedure for full anomaly cancellation. Our results have implications for effective supergravity theories from the weakly coupled heterotic string theory.

    17. The elliptic anomaly

      NASA Technical Reports Server (NTRS)

      Janin, G.; Bond, V. R.

      1980-01-01

      An independent variable different from the time for elliptic orbit integration is used. Such a time transformation provides an analytical step-size regulation along the orbit. An intermediate anomaly (an anomaly intermediate between the eccentric and the true anomaly) is suggested for optimum performances. A particular case of an intermediate anomaly (the elliptic anomaly) is defined, and its relation with the other anomalies is developed.

    18. Satellite Magnetic Anomalies of Africa and Europe

      NASA Technical Reports Server (NTRS)

      Hinze, W. J.; Vonfrese, R. R. B. (Principal Investigator); Olivier, R.

      1984-01-01

      Preliminary MAGSAT scalar magnetic anomaly data of Africa, Europe, and adjacent marine areas were reduced to the pole assuming a constant inducing Earth's magnetic field of 60,000 nT. This process leads to a consistent anomaly data set free from marked variations in directional and intensity effects of the Earth's magnetic field over this extensive region. The resulting data are correlated with long wave length-pass filtered free-air gravity anomalies; regional heat flow, and tectonic data to investigate magatectonic elements and the region's geologic history. Magnetic anomalies are related to both ancient as well as more recent Cenozoic structural features.

    19. 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.

    20. 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.

    1. 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

    2. 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.

    3. A reduced core to skin temperature gradient, not a critical core temperature, affects aerobic capacity in the heat.

      PubMed

      Cuddy, John S; Hailes, Walter S; Ruby, Brent C

      2014-07-01

      in beginning and ending core temperatures or baseline 3-mile run time. This capacity difference appears to result from a magnified core to skin gradient via an environmental temperature advantageous to convective heat loss, and in part from an increased sweat rate. PMID:24956952

    4. Correlation of Arrhenius behaviors in power and capacity fades with cell impedance and heat generation in cylindrical lithium-ion cells

      NASA Astrophysics Data System (ADS)

      Liaw, Bor Yann; Roth, E. Peter; Jungst, Rudolph G.; Nagasubramanian, Ganesan; Case, Herbert L.; Doughty, Daniel H.

      A series of cylindrical 18650 lithium-ion cells with an MAG-10|1.2 M LiPF 6 ethylene carbonate (EC):ethyl methyl carbonate (EMC) (w:w=3:7)|Li xNi 0.8Co 0.15Al 0.05O 2 configuration were made and tested for power-assist hybrid electric vehicle (HEV) applications under various aging conditions of temperature and state-of-charge (SOC). The cells were intermittently characterized for changes in power capability, rate capacity, and impedance as aging progressed. The changes of these properties with temperature, as depicted by Arrhenius equations, were analyzed. We found that the degradation in power and capacity fade seems to relate to the impedance increase in the cell. The degradation follows a multi-stage process. The initial stage of degradation has an activation energy of the order of 50-55 kJ/mol, as derived from power fade and C1 capacity fade measured at C/1 rate. In addition, microcalorimetry was performed on two separate unaged cells at 80% SOC at various temperatures to measure static heat generation in the cells. We found that the static heat generation has an activation energy of the order of 48-55 kJ/mol, similar to those derived from power and C1 capacity fade. The correspondence in the magnitude of the activation energy suggests that the power and C1 capacity fades were related to the changes of the impedance in the cells, most likely via the same fading mechanism. The fading mechanism seemed to be related to the static heat generation of the cell.

    5. 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).

    6. 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.

    7. Assessing the potential for increased capacity of combined heat and power facilities based on available corn stover and forest logging residue in Mississippi

      NASA Astrophysics Data System (ADS)

      Radhakrishnan, Selvarani

      The amount of available biomass feedstock and associated cost components were analyzed to determine the potential increase in energy capacity of two existing combined heat and power plants in Mississippi. The amount of corn stover and forest logging residue within a 10-mile radius can satisfy the existing requirements of CHP plants in Scott (1 MW) and Washington counties (5 MW). Transporting feedstock within a smaller source area had lower transportation costs, but higher total unit cost than the two other source buffer scenarios. However, capital costs associated with higher plant capacities were significantly higher and plant expansion may not be economically advantageous. Increasing the CHP capacity from 1 MW to 2 MW in Scott county and 5 MW to 10 MW in Washington county might be a sustainable approach by drawing feedstock from a smaller area and at lower utilization rates, while keeping transportation costs low.

    8. 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.

    9. 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.

    10. 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.

    11. 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

    12. 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

    13. 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.

    14. Apparent First-Order Liquid-Liquid Transition with Pre-transition Density Anomaly, in Water-Rich Ideal Solutions.

      PubMed

      Zhao, Zuofeng; Angell, C Austen

      2016-02-12

      The striking increases in response functions observed during supercooling of pure water have been the source of much interest and controversy. Imminent divergences of compressibility etc. unfortunately cannot be confirmed due to pre-emption by ice crystallization. Crystallization can be repressed by addition of second components, but these usually destroy the anomalies of interest. Here we study systems in which protic ionic liquid second components dissolve ideally in water, and ice formation is avoided without destroying the anomalies. We observe a major heat capacity spike during cooling, which is reversed during heating, and is apparently of first order. It occurs just before the glassy state is reached and is preceded by water-like density anomalies. We propose that it is the much-discussed liquid-liquid transition previously hidden by crystallization. Fast cooling should allow the important fluctuations/structures to be preserved in the glassy state for leisurely investigation. PMID:26756943

    15. Impact of oxygen annealing on the heat capacity and magnetic resonance of superconducting Pr0.88LaCe0.12CuO4−

      SciTech Connect

      Li, Shiliang; Chi, Songxue; Zhao, Jun; Wen, H. H.; Stone, Matthew B; Lynn, J. W.; Dai, Pengcheng

      2008-01-01

      We use thermodynamic and neutron-scattering measurements to study the effect of oxygen annealing on the superconductivity and magnetism in Pr0.88LaCe0.12CuO4−. Although the transition temperature Tc measured by susceptibility and superconducting coherence length increases smoothly with gradual oxygen removal from the annealing process, bulk superconductivity, marked by a specific-heat anomaly at Tc and the presence of a neutron magnetic resonance, only appears abruptly when Tc is close to the largest value. These results suggest that the effect of oxygen annealing must first be determined in order to establish a Ce doping dependence of antiferromagnetism and superconductivity phase diagram for electron-doped copper oxides.

    16. 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.

    17. Numerical anomalies mimicking physical effects

      NASA Astrophysics Data System (ADS)

      Menikoff, R.

      Numerical simulations of flows with shock waves typically use finite-difference shock-capturing algorithms. These algorithms give a shock a numerical width in order to generate the entropy increase that must occur across a shock wave. For algorithms in conservation form, steady-state shock waves are insensitive to the numerical dissipation because of the Hugoniot jump conditions. However, localized numerical errors occur when shock waves interact. Examples are the 'excess wall heating' in the Noh problem (shock reflected from rigid wall), errors when a shock impacts a material interface or an abrupt change in mesh spacing, and the start-up error from initializing a shock as a discontinuity. This class of anomalies can be explained by the entropy generation that occurs in the transient flow when a shock profile is formed or changed. The entropy error is localized spatially but under mesh refinement does not decrease in magnitude. Similar effects have been observed in shock tube experiments with partly dispersed shock waves. In this case, the shock has a physical width due to a relaxation process. An entropy anomaly from a transient shock interaction is inherent in the structure of the conservation equations for fluid flow. The anomaly can be expected to occur whenever heat conduction can be neglected and a shock wave has a non-zero width, whether the width is physical or numerical. Thus, the numerical anomaly from an artificial shock width mimics a real physical effect.

    18. Effects of Longwave Cloud Radiative Forcing Anomalies on the Atmospheric Response to Equatorial Pacific Sea Surface Temperature Anomalies

      NASA Technical Reports Server (NTRS)

      Chen, M.; Cess, Robert D.; Zhang, Ming-Hua

      1995-01-01

      The latest version of the National Center for Atmospheric Research community climate model (CCM2) has been used to investigate cloud radiative forcing (CRF) anomalies associated with equatorial Pacific sea surface temperature (SST) anomalies and the effects of the longwave CRF (LWCRF) anomalies on the atmospheric response to the SST anomalies. The SST anomalies cause large CRF anomalies, both longwave and shortwave, as well as latent heat anomalies at low latitudes on a global scale. The relative magnitude of the simulated longwave and shortwave CRF anomalies is consistent with the result of the Earth Radiation Budget Experiment (ERBE), implying that cloud height and cloud radiative properties such as emissivity and reflectivity are well simulated by the model. The LWCRF anomaly strongly enhances the precipitation anomaly in the whole tropical belt. The positive (negative) LWCRF anomaly warms (cools) the troposphere and destabilizes (stabilizes) the upper troposphere. The LWCRF anomaly enhances the Southern Oscillation and the related Walker circulation anomaly. The effects of the LWCRF anomaly are essential to the northern hemispheric extratropical circulation anomaly, the Pacific/North American pattern.

    19. Data use investigations for applications Explorer Mission A (Heat Capacity Mapping Mission): HCMM's role in studies of the urban heat island, Great Lakes thermal phenomena and radiometric calibration of satellite data. [Buffalo, Syracuse, and Rochester New York and Lake Ontario

      NASA Technical Reports Server (NTRS)

      Schott, J. R. (Principal Investigator); Schimminger, E. W.

      1981-01-01

      The utility of data from NASA'a heat capacity mapping mission satellite for studies of the urban heat island, thermal phenomena in large lakes and radiometric calibration of satellite sensors was assessed. The data were found to be of significant value in all cases. Using HCMM data, the existence and microstructure of the heat island can be observed and associated with land cover within the urban complex. The formation and development of the thermal bar in the Great Lakes can be observed and quantitatively mapped using HCMM data. In addition, the thermal patterns observed can be associated with water quality variations observed both from other remote sensing platforms and in situ. The imaging radiometer on-board the HCMM satellite is shown to be calibratible to within about 1.1 C of actual surface temperatures. These findings, as well as the analytical procedures used in studying the HCMM data, are included.

    20. Lymphatic Anomalies Registry

      ClinicalTrials.gov

      2016-07-26

      Lymphatic Malformation; Generalized Lymphatic Anomaly (GLA); Central Conducting Lymphatic Anomaly; CLOVES Syndrome; Gorham-Stout Disease ("Disappearing Bone Disease"); Blue Rubber Bleb Nevus Syndrome; Kaposiform Lymphangiomatosis; Kaposiform Hemangioendothelioma/Tufted Angioma; Klippel-Trenaunay Syndrome; Lymphangiomatosis

    1. 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.

    2. Preparation of Nano-Composite Ca2-αZnα(OH)4 with High Thermal Storage Capacity and Improved Recovery of Stored Heat Energy

      NASA Astrophysics Data System (ADS)

      Zheng, M.; Sun, S. M.; Hu, J.; Zhao, Y.; Yu, L. J.

      2014-11-01

      Thermal energy storage has very important prospects in many applications related to the use of renewable energies (solar energy, etc.) or other energy sources, such as waste heat from industrial processes. Thermochemical storage is very attractive for long-term storage, since it could be conducted at room temperature without energy losses. In the present paper, a novel nanocomposite material, Ca2-αZnα(OH)4, is prepared using coprecipitation methodology and is characterized by XRD and DSC tests. The XRD result shows that the grain size of the nano-composite ranges from 40 nm to 95 nm. The DSC test result shows that the nano-composite exhibits high thermal storage capacity: 764.5 J/g at α = 0.8555. Its thermal decomposition temperature was found to be approximately 180º. Itwas found possible to recover 63.25% of the stored heat energy.

    3. Effects of Chlorination and Heat Treatment on Flour and Gluten Functionality Explored by Solvent Retention Capacity (SRC) and Mixograph

      Technology Transfer Automated Retrieval System (TEKTRAN)

      The effects of chlorination and heat treatment on flour and gluten functionality were explored by SRC and mixograph for the soft wheat cultivar, Croplan 594W. Regardless of milling yield, SRC results for chlorinated flour samples showed a decrease in lactic acid SRC values with increasing extent of...

    4. Analysis of spacecraft anomalies

      NASA Technical Reports Server (NTRS)

      Bloomquist, C. E.; Graham, W. C.

      1976-01-01

      The anomalies from 316 spacecraft covering the entire U.S. space program were analyzed to determine if there were any experimental or technological programs which could be implemented to remove the anomalies from future space activity. Thirty specific categories of anomalies were found to cover nearly 85 percent of all observed anomalies. Thirteen experiments were defined to deal with 17 of these categories; nine additional experiments were identified to deal with other classes of observed and anticipated anomalies. Preliminary analyses indicate that all 22 experimental programs are both technically feasible and economically viable.

    5. Specific features of low-frequency vibrational dynamics and low-temperature heat capacity of double-walled carbon nanotubes

      NASA Astrophysics Data System (ADS)

      Avramenko, M. V.; Roshal, S. B.

      2016-05-01

      A continuous model has been constructed for low-frequency dynamics of a double-walled carbon nanotube. The formation of the low-frequency part of the phonon spectrum of a double-walled nanotube from phonon spectra of its constituent single-walled nanotubes has been considered in the framework of the proposed approach. The influence of the environment on the phonon spectrum of a single double-walled carbon nanotube has been analyzed. A combined method has been proposed for estimating the coefficients of the van der Waals interaction between the walls of the nanotube from the spectroscopic data and the known values of the elastic moduli of graphite. The low-temperature specific heat has been calculated for doublewalled carbon nanotubes, which in the field of applicability of the model ( T < 35 K) is substantially less than the sum of specific heats of two individual single-walled nanotubes forming it.

    6. 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.

    7. 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.

    8. 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.

    9. Kinetic-freezing and unfreezing of local-region fluctuations in a glass structure observed by heat capacity hysteresis

      SciTech Connect

      Aji, D. P. B.; Johari, G. P.

      2015-06-07

      Fluctuations confined to local regions in the structure of a glass are observed as the Johari-Goldstein (JG) relaxation. Properties of these regions and their atomic configuration are currently studied by relaxation techniques, by electron microscopy, and by high-energy X-ray scattering and extended x-ray absorption fine structure methods. One expects that these fluctuations (i) would kinetically freeze on cooling a glass, and the temperature coefficient of its enthalpy, dH/dT, would consequently show a gradual decrease with decrease in T, (ii) would kinetically unfreeze on heating the glass toward the glass-liquid transition temperature, T{sub g}, and dH/dT would gradually increase, and (iii) there would be a thermal hysteresis indicating the time and temperature dependence of the enthalpy. Since no such features have been found, thermodynamic consequences of these fluctuations are debated. After searching for these features in glasses of different types, we found it in one of the most stable metal alloy glasses of composition Pd{sub 40}Ni{sub 10}Cu{sub 30}P{sub 20}. On cooling from its T{sub g}, dH/dT decreased along a broad sigmoid-shape path as local-region fluctuations kinetically froze. On heating thereafter, dH/dT increased along a similar path as these fluctuations unfroze, and there is hysteresis in the cooling and heating paths, similar to that observed in the T{sub g}-endotherm range. After eliminating other interpretations, we conclude that local-region fluctuations seen as the JG relaxation in the non-equilibrium state of a glass contribute to its entropy, and we suggest conditions under which such fluctuations may be observed.

    10. Thermal management of instruments on space platforms using a high capacity two-phase heat transport system

      NASA Technical Reports Server (NTRS)

      Ollendorf, S.; Fowle, A.; Almgren, D.

      1981-01-01

      A system utilizing a pumped, two-phase single component working fluid for heat exchange and transport services necessary to meet the temperature control requirements of typical orbiting instrument payloads on space platforms is described. The design characteristics of the system is presented, together with a presentation of a laboratory apparatus for demonstration of proof of concept. Results indicate that the pumped two-phase design concept can meet a wide range of thermal performance requirements with the only penalty being the requirement for a small liquid pump.

    11. Negative entropy, energy, and heat capacity in connection with surface tension: artifact of a model or real

      SciTech Connect

      Lubkin, E.

      1987-05-01

      It is only by neglecting self-adsorption (a treatment referred to as pure-energy, PE) that one gets textbook thermodynamics of a surface, based upon the tension L as a function of temperature T, and one finds negative specific heat for hot water. Any lower critical point and PE provides the other exciting negatives: nicotine-and-water is an example. In order to include adsorption, T must be known in terms of T and chemical potentials as independent variables; this forces measurement of the tension of curved menisci. Will the minus signs remain.

    12. The Expression of Carnosine and Its Effect on the Antioxidant Capacity of Longissimus dorsi Muscle in Finishing Pigs Exposed to Constant Heat Stress

      PubMed Central

      Yang, Peige; Hao, Yue; Feng, Jinghai; Lin, Hai; Feng, Yuejin; Wu, Xin; Yang, Xin; Gu, Xianhong

      2014-01-01

      The objective of this study was to assess the effects of constant high ambient temperatures on meat quality, antioxidant capacity, and carnosine expression in longissimus dorsi muscle of finishing pigs. Castrated 24 male DLY (crossbreeds between Landrace×Yorkshire sows and Duroc boars) pigs were allocated to one of three treatments: constant ambient temperature at 22°C and ad libitum feeding (CON, n = 8); constant high ambient temperature at 30°C and ad libitum feeding (H30, n = 8); and constant ambient temperature at 22°C and pair-fed with H30 (PF, n = 8). Meat quality, malondialdehyde (MDA) content, antioxidant capacity, carnosine content, and carnosine synthetase (CARNS1) mRNA expression in longissimus dorsi muscle were measured after three weeks. The results revealed that H30 had lower pH24 h, redness at 45 min, and yellowness at 24 h post-mortem (p<0.05), and higher drip loss at 48 h and lightness at 24 h post-mortem (p<0.01). Constant heat stress disrupted the pro-oxidant/antioxidant balance in longissimus dorsi muscle with higher MDA content (p<0.01) and lower antioxidant capacity (p<0.01). Carnosine content and CARNS1 mRNA expression in longissimus dorsi muscle of H30 pigs were significantly decreased (p<0.01) after three weeks at 30°C. In conclusion, constant high ambient temperatures affect meat quality and antioxidant capacity negatively, and the reduction of muscle carnosine content is one of the probable reasons. PMID:25358371

    13. [Kimmerle's anomaly and stroke].

      PubMed

      Barsukov, S F; Antonov, G I

      1992-10-01

      The anomaly of cranio-vertebral area can frequently be the reason of acute cerebrovascular disorders in vertebro-basilar field. The frequent C1 pathology in the Kimmerle's anomaly. The anatomic studies has shown that 30% of people had this type of anomaly. This pathology can lead to severe vascular diseases of cerebrum because of the squeezing effect upon vertebral arteries in the zone of osteal ponticulus of the rear arch of atlas. PMID:1481402

    14. Single crystal growth and heat capacity measurements of triangular lattice R2Pt6Ga15 (R =rare earth)

      NASA Astrophysics Data System (ADS)

      Matsumoto, Y.; Ueda, T.; Ohara, S.

      2016-02-01

      We have succeeded in synthesizing the single crystal of R2Pt6Ga15 (R=La-Nd, Sm- Lu) with hexagonal Sc0.67Fe2Si5-type structure using Ga self flux method. The crystal structure was confirmed by the powder X-ray method. The unit-cell volume V of R2Pt6Ga15 follows the lanthanide concentration except R = Ce, Eu and Yb, indicating that the valences of R = La, Pr, Nd, Sm, Gd-Tm, and Lu ion are trivalent, whereas those of R = Ce, Eu and Yb ion are deviate from trivalent. We have measured the specific heat C(T) of R2Pt6Ga15. It is found that the magnetic order takes place in R2Pt6Ga15 (R=Pr, Nd, Sm-Tm). Moreover, the multiple phase transitions were observed in R2Pt6Ga15 (R = Nd, Eu, Gd and Ho).

    15. Low field magnetocaloric effect and heat capacity of A-site ordered NdBaMn 2O 6 manganite

      NASA Astrophysics Data System (ADS)

      Aliev, A. M.; Gamzatov, A. G.; Kalitka, V. S.; Kaul, A. R.

      2011-12-01

      The magnetocaloric effect (MCE) in the A-site ordered manganite NdBaMn 2O 6 is studied. The MCE in this compound has an anomalous behavior. In low magnetic fields, the abrupt transitions between the direct and inverse magnetocaloric effects are observed. In a relatively strong magnetic field H=11 kOe, the direct and inverse effects are observed only at cooling, while the heating mode reveals only an inverse MCE. The value of the MCE ( -ΔS=0.7 J/kg K and ΔS=1.02 J/kg K for ΔH=11 kOe) does not reach high values, but the proximity of the effects occurring at room temperatures expects the use of both effects in the magnetic cooling technology.

    16. 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

    17. Taussig-Bing Anomaly

      PubMed Central

      Konstantinov, Igor E.

      2009-01-01

      Taussig-Bing anomaly is a rare congenital heart malformation that was first described in 1949 by Helen B. Taussig (1898–1986) and Richard J. Bing (1909–). Although substantial improvement has since been achieved in surgical results of the repair of the anomaly, management of the Taussig-Bing anomaly remains challenging. A history of the original description of the anomaly, the life stories of the individuals who first described it, and the current outcomes of its surgical management are reviewed herein. PMID:20069085

    18. 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.

    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. Alternating current calorimeter for specific heat capacity measurements at temperatures below 10 K and pressures up to 10 GPa

      NASA Astrophysics Data System (ADS)

      Umeo, Kazunori

      2016-06-01

      A developed alternating current calorimeter for measuring the absolute value of specific heat C of a very small sample under a pressure up to 10 GPa and low temperature below 10 K is described. A Bridgman anvil cell made of tungsten carbide with a top diameter of 3 mm is used. A hollow at the top prevents expansion of the sample space over the anvil top. Two chip resistors, which act as a thermometer and a heater, are mounted on the outer part of a copper-beryllium gasket with a frying pan-like shape. Thus, the thermometer is not pressurized. In order to isolate the gasket from the anvil thermally, diamond powder with a grain size of 0.25 μm is placed on the anvil top. Two jumps of C at the superconducting transitions of Pb (3.3 mg) and In (5.0 mg) are observed under various pressures up to 9 GPa, as clearly as those at the ambient pressure.

    1. Alternating current calorimeter for specific heat capacity measurements at temperatures below 10 K and pressures up to 10 GPa.

      PubMed

      Umeo, Kazunori

      2016-06-01

      A developed alternating current calorimeter for measuring the absolute value of specific heat C of a very small sample under a pressure up to 10 GPa and low temperature below 10 K is described. A Bridgman anvil cell made of tungsten carbide with a top diameter of 3 mm is used. A hollow at the top prevents expansion of the sample space over the anvil top. Two chip resistors, which act as a thermometer and a heater, are mounted on the outer part of a copper-beryllium gasket with a frying pan-like shape. Thus, the thermometer is not pressurized. In order to isolate the gasket from the anvil thermally, diamond powder with a grain size of 0.25 μm is placed on the anvil top. Two jumps of C at the superconducting transitions of Pb (3.3 mg) and In (5.0 mg) are observed under various pressures up to 9 GPa, as clearly as those at the ambient pressure. PMID:27370464

    2. Analysis of wall heat capacity effects on core makup tank drain-down behavior in ROSA/AP600 experiments

      SciTech Connect

      Kondo, Masaya; Yonomoto, Taisuke; Asaka, Hideaki

      1997-12-01

      The thermal-hydraulic behavior of the core makeup tank (CMT) during scaled integral experiments on the Westinghouse AP600 reactor design was analyzed using the RELAP5/Mod3 (version 5M5) code. The natural circulation rate through the CMT was predicted well, although the prediction of the thermal stratification in the CMT had a problem due to inability to predict multidimensional mixing in the CMT upper regions. The over-scaled CMT metal mass in the experimental facility affected the CMT drain-down behavior in two experiments: (i) a multiple-failure experiment where the system depressurization became extremely slow due to the simulated failure of the ADS valves; and (ii) a relatively-large break experiment where the CMT started draining before thermal stratification developed in the CMT water inventory. In both experiments, the CMT wall became a heat sink and was a large steam condensation site. This had a effect to limit the CMT drain rate. 6 refs., 15 figs.

    3. Systematic Studies on Anharmonicity of Rattling Phonons in Type I Clathrates by Low Temperature Heat Capacity Measurements

      NASA Astrophysics Data System (ADS)

      Tanigaki, Katsumi; Wu, Jiazhen; Tanabe, Yoichi; Heguri, Satoshi; Shiimotani, Hidekazu; Tohoku University Collaboration

      2014-03-01

      Clathrates are featured by cage-like polyhedral hosts mainly composed of the IVth group elements of Si, Ge, or Sn and alkali metal or alkaline-earth metal elements can be accommodated inside as a guest atom. One of the most intriguing issues in clathrates is their outstanding high thermoelectric performances thanks to the low thermal conductivity. Being irrespective of good electric conductivity σ, the guest atom motions provide a low-energy lying less-dispersive phonons and can greatly suppress thermal conductivity κ. This makes clathrates close to the concept of ``phonon glass electron crystal: PGEC'' and useful in thermoelectric materials from the viewpoint of the figure of merit. In the present study, we show that the local phonon anharmonicity indicated by the tunneling-term of the endohedral atoms (αT) and the itinerant-electron term (γeT), both of which show T-linear dependences in specific heat Cp, can successfully be separated by employing single crystals with various carrier concentrations in a wide range of temperture experimennts. The factors affecting on the phonon anharmonicity as well as the strength of electron-phonon interactions will be discussed based on our recent experiments. The research was financially supported by Ministry of Education, Science, Sports and Culture, Grant in Aid for Science, and Technology of Japan.

    4. Hot Flow Anomalies at Venus

      NASA Technical Reports Server (NTRS)

      Collinson, G. A.; Sibeck, David Gary; Boardsen, Scott A.; Moore, Tom; Barabash, S.; Masters, A.; Shane, N.; Slavin, J.A.; Coates, A.J.; Zhang, T. L.; Sarantos, M.

      2012-01-01

      We present a multi-instrument study of a hot flow anomaly (HFA) observed by the Venus Express spacecraft in the Venusian foreshock, on 22 March 2008, incorporating both Venus Express Magnetometer and Analyzer of Space Plasmas and Energetic Atoms (ASPERA) plasma observations. Centered on an interplanetary magnetic field discontinuity with inward convective motional electric fields on both sides, with a decreased core field strength, ion observations consistent with a flow deflection, and bounded by compressive heated edges, the properties of this event are consistent with those of HFAs observed at other planets within the solar system.

    5. Hot flow anomalies at Venus

      NASA Astrophysics Data System (ADS)

      Collinson, G. A.; Sibeck, D. G.; Masters, A.; Shane, N.; Slavin, J. A.; Coates, A. J.; Zhang, T. L.; Sarantos, M.; Boardsen, S.; Moore, T. E.; Barabash, S.

      2012-04-01

      We present a multi-instrument study of a hot flow anomaly (HFA) observed by the Venus Express spacecraft in the Venusian foreshock, on 22 March 2008, incorporating both Venus Express Magnetometer and Analyzer of Space Plasmas and Energetic Atoms (ASPERA) plasma observations. Centered on an interplanetary magnetic field discontinuity with inward convective motional electric fields on both sides, with a decreased core field strength, ion observations consistent with a flow deflection, and bounded by compressive heated edges, the properties of this event are consistent with those of HFAs observed at other planets within the solar system.

    6. Competing Orders and Anomalies.

      PubMed

      Moon, Eun-Gook

      2016-01-01

      A conservation law is one of the most fundamental properties in nature, but a certain class of conservation "laws" could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the 't Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed. PMID:27499184

    7. Competing Orders and Anomalies

      NASA Astrophysics Data System (ADS)

      Moon, Eun-Gook

      2016-08-01

      A conservation law is one of the most fundamental properties in nature, but a certain class of conservation “laws” could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the ’t Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed.

    8. Competing Orders and Anomalies

      PubMed Central

      Moon, Eun-Gook

      2016-01-01

      A conservation law is one of the most fundamental properties in nature, but a certain class of conservation “laws” could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the ’t Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed. PMID:27499184

    9. 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).

    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. Thermal Control and Enhancement of Heat Transport Capacity of Two-Phase Loops With Electrohydrodynamic Conduction Pumping

      NASA Technical Reports Server (NTRS)

      Seyed-Yagoobi, J.; Didion, J.; Ochterbeck, J. M.; Allen, J.

      2000-01-01

      electric power requirements making the EHD conduction pumping attractive to applications such as two-phase systems (e.g. capillary pumped loops and heat pipes). Currently, the EHD conduction pump performance is being tested on a two-phase loop under various operating conditions in the laboratory environment. The simple non-mechanical and lightweight design of the EHD pump combined with the rapid control of performance by varying the applied electric field, low power consumption, and reliability offer significant advantages over other pumping mechanisms; particularly in reduced gravity applications.

    12. Effects of dietary addition of heat-killed Mycobacterium phlei on growth performance, immune status and anti-oxidative capacity in early weaned piglets.

      PubMed

      Zhong, Jin-Feng; Wu, Wei-Gao; Zhang, Xiao-Qing; Tu, Wei; Liu, Zhen-Xiang; Fang, Re-Jun

      2016-08-01

      The contradiction between high susceptibility of early weaned piglets to enteric pathogens and rigid restriction of antibiotic use in the diet is still prominent in the livestock production industry. To address this issue, the study was designed to replace dietary antibiotics partly or completely by an immunostimulant, namely heat-killed Mycobacterium phlei (M. phlei). Piglets (n = 192) were randomly assigned to one of the four groups: (1) basal diet (Group A), (2) basal diet + a mixture of antibiotics (80 mg/kg diet, Group B), (3) basal diet + a mixture of antibiotics (same as in Group B, but 40 mg/kg diet) + heat-killed M. phlei (1.5 g/kg diet) (Group C) and (4) basal diet + heat-killed M. phlei (3 g/kg diet) (Group D). All piglets received the respective diets from days 21 to 51 of age and were weaned at the age of 28 d. Compared with the Control (Group A), in all other groups the average daily gain, average daily feed intake, small intestinal villus height:crypt depth ratio and protein levels of occludin and ZO-1 in the jejunal mucosa were increased. A decreased incidence of diarrhoea in conjunction with an increased sIgA concentration in the intestinal mucosa and serum IL-12 and IFN-γ concentrations was found in groups supplemented with heat-killed M. phlei (Groups C and D), but not in Group B. Groups C and D also showed decreased IL-2 concentrations in the intestinal mucosa with lower TLR4 and phosphor-IκB protein levels. The antioxidant capacity was reinforced in Groups C and D, as evidenced by the reduction in malondialdehyde and enhanced activities of antioxidant enzymes in serum. These data indicate that heat-killed M. phlei is a promising alternative to antibiotic use for early weaned piglets via induction of protective immune responses. PMID:27216553

    13. 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.

    14. Müllerian anomalies.

      PubMed

      Gell, Jennifer S

      2003-11-01

      The reproductive organs in both males and females consist of gonads, internal ductal structures, and external genitalia. Normal sexual differentiation is dependent on the genetic sex determined by the presence or absence of the Y chromosome at fertilization. Testes develop under the influence of the Y chromosome and ovaries develop when no Y chromosome is present. In the absence of testes and their normal hormonal products, sexual differentiation proceeds along the female pathway, resulting in a normal female phenotype. Anatomic gynecologic anomalies occur when there is failure of normal embryologic ductal development. These anomalies include congenital absence of the vagina as well as defects in lateral and vertical fusion of the Müllerian ducts. Treatment of müllerian anomalies begins with the correct identification of the anomaly and an understanding of the embryologic origin. This includes evaluation for other associated anomalies such as renal or skeletal abnormalities. After correct identification, treatment options include nonsurgical as well as surgical intervention. This chapter serves to review the embryology and development of the reproductive system and to describe common genital tract anomalies. Details of surgical or nonsurgical correction of these anomalies are presented. PMID:14724770

    15. Variability of winter extreme precipitation in Southeast China: contributions of SST anomalies

      NASA Astrophysics Data System (ADS)

      Zhang, Ling; Sielmann, Frank; Fraedrich, Klaus; Zhu, Xiuhua; Zhi, Xiefei

      2015-11-01

      Tropical SST anomalies are among the largest drivers of circulation regime changes on interannual time scales due to its characteristic heat capacity decay time scales. The circulation anomalies associated with extreme precipitation and the corresponding atmospheric response to SST anomalies are derived from ECMWF ERA-Interim reanalysis data by employing composite analysis and lagged maximum covariance analysis. Our results show that interannual variability of extreme winter precipitation in Southeast China is in close accordance with the interannual variability of total winter precipitation. Both are associated with similar abnormal circulation regimes, but for extreme precipitation events the circulation anomalies and moisture transport channels are significantly intensified. Two main moisture transport channels are captured: one extends from the North Indian Ocean through India and the Bay of Bengal to South China, and the other from the West Pacific Ocean through Maritime Continent and South China Sea towards South China, which are related to the preceding autumn SST patterns, El Niño and the Indian Ocean dipole (IOD), respectively. El Niño (La Niña) SST anomalies induce anomalous anticyclonic (cyclonic) circulation over Philippine Sea, which is favorable (unfavorable) to warm and humid air transport to South China from the tropical West Pacific by southwesterly (northeasterly) anomalies. Under these circulations, northeasterlies of East Asian Winter Monsoon are weakened (strengthened) resulting in extreme precipitation to be more (less) frequent in Southeast China. During the positive (negative) IOD phase, abundant (reduced) moisture transport to South China from tropical regions through India and Bay of Bengal is observed due to weakened (strengthened) Walker circulations and abnormal anticyclonic (cyclonic) circulation over India, leading to a higher (lower) likelihood for extreme precipitation events in Southeast China. The underlying physical mechanisms

    16. Heat capacity and neutron diffraction studies on the frustrated magnetic Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} [0{<=}x{<=}1] solid solution

      SciTech Connect

      Pedro, I. de; Rojo, J.M.; Rodriguez Fernandez, J.; Sanchez Marcos, J.; Fernandez-Diaz, M.T.; Rojo, T.

      2012-04-15

      The Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} [0{<=}x{<=}1] solid solution exhibits a complex magnetic behaviour due to the bond-frustration in its magnetic structure. Heat capacity measurements of the (x=0.1-0.5) phases show a three-dimensional magnetic ordering ({lambda} anomaly) that shifts to lower temperatures and becomes broader as the AsO{sub 4}{sup 3-} content increases. For x=0.75, no significant feature was observed whereas for higher arsenate ion content, x=0.9 and 1, a small maximum was detected. The magnetic structures of solid solution are consistent with the existence of predominant antiferromagnetic superexchange interactions through the |OH| and |XO{sub 4}| (X=P and As) groups between the Co{sup +2} ions. The substitution of PO{sub 4}{sup 3-} by AsO{sub 4}{sup 3-} anions by more than 90% substantially modifies the magnetic exchange pathways in the solid solution, leading to an incommensurate antiferromagnetic structure in Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} [x=0.9 and 1] phases. - Graphical abstract: Magnetic structures of Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} [0{<=}x{<=}1]. The ordering of the magnetic moments of Co{sup 2+} is in c direction for the two crystallographic positions (dimers and chains) in all compounds. The unit cell is surrounded by a red line. Highlights: Black-Right-Pointing-Pointer Synthesis of a new adamite-type compounds, Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} (0.1, 0.25, 0.5, 0.75, 0.9) phases. Black-Right-Pointing-Pointer Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} (0-1) solid solution; magnetic frustrated system. Black-Right-Pointing-Pointer High resolution neutron powder diffraction to determine the crystal structures. Black-Right-Pointing-Pointer Incommensurate magnetic structures at low temperature. Black-Right-Pointing-Pointer Magnetostructural correlations in cobalt-based Co{sub 2}(OH)XO{sub 4} (X=P and As) insulation compounds.

    17. Behavioral economics without anomalies.

      PubMed Central

      Rachlin, H

      1995-01-01

      Behavioral economics is often conceived as the study of anomalies superimposed on a rational system. As research has progressed, anomalies have multiplied until little is left of rationality. Another conception of behavioral economics is based on the axiom that value is always maximized. It incorporates so-called anomalies either as conflicts between temporal patterns of behavior and the individual acts comprising those patterns or as outcomes of nonexponential time discounting. This second conception of behavioral economics is both empirically based and internally consistent. PMID:8551195

    18. 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

    19. 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.

    20. 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

    1. Dual diaphragmatic anomalies.

      PubMed

      Padmanabhan, Arjun; Thomas, Abin Varghese

      2016-01-01

      Although diaphragmatic anomalies such as an eventration and hiatus hernia are commonly encountered in incidental chest X-ray imaging, the presence of concomitant multiple anomalies is extremely rare. This is all the more true in adults. Herein, we present the case of a 75-year-old female, while undergoing a routine chest X-ray imaging, was found to have eventration of right hemidiaphragm along with a hiatus hernia as well. PMID:27625457

    2. Dual diaphragmatic anomalies

      PubMed Central

      Padmanabhan, Arjun; Thomas, Abin Varghese

      2016-01-01

      Although diaphragmatic anomalies such as an eventration and hiatus hernia are commonly encountered in incidental chest X-ray imaging, the presence of concomitant multiple anomalies is extremely rare. This is all the more true in adults. Herein, we present the case of a 75-year-old female, while undergoing a routine chest X-ray imaging, was found to have eventration of right hemidiaphragm along with a hiatus hernia as well.

    3. Anomalies and entanglement entropy

      NASA Astrophysics Data System (ADS)

      Nishioka, Tatsuma; Yarom, Amos

      2016-03-01

      We initiate a systematic study of entanglement and Rényi entropies in the presence of gauge and gravitational anomalies in even-dimensional quantum field theories. We argue that the mixed and gravitational anomalies are sensitive to boosts and obtain a closed form expression for their behavior under such transformations. Explicit constructions exhibiting the dependence of entanglement entropy on boosts is provided for theories on spacetimes with non-trivial magnetic fluxes and (or) non-vanishing Pontryagin classes.

    4. On isostatic geoid anomalies

      NASA Technical Reports Server (NTRS)

      Haxby, W. F.; Turcotte, D. L.

      1978-01-01

      In regions of slowly varying lateral density changes, the gravity and geoid anomalies may be expressed as power series expansions in topography. Geoid anomalies in isostatically compensated regions can be directly related to the local dipole moment of the density-depth distribution. This relationship is used to obtain theoretical geoid anomalies for different models of isostatic compensation. The classical Pratt and Airy models give geoid height-elevation relationships differing in functional form but predicting geoid anomalies of comparable magnitude. The thermal cooling model explaining ocean floor subsidence away from mid-ocean ridges predicts a linear age-geoid height relationship of 0.16 m/m.y. Geos 3 altimetry profiles were examined to test these theoretical relationships. A profile over the mid-Atlantic ridge is closely matched by the geoid curve derived from the thermal cooling model. The observed geoid anomaly over the Atlantic margin of North America can be explained by Airy compensation. The relation between geoid anomaly and bathymetry across the Bermuda Swell is consistent with Pratt compensation with a 100-km depth of compensation.

    5. Anomalies in bulk supercooled water at negative pressure.

      PubMed

      Pallares, Gaël; El Mekki Azouzi, Mouna; González, Miguel A; Aragones, Juan L; Abascal, José L F; Valeriani, Chantal; Caupin, Frédéric

      2014-06-01

      Water anomalies still defy explanation. In the supercooled liquid, many quantities, for example heat capacity and isothermal compressibility κT, show a large increase. The question arises if these quantities diverge, or if they go through a maximum. The answer is key to our understanding of water anomalies. However, it has remained elusive in experiments because crystallization always occurred before any extremum is reached. Here we report measurements of the sound velocity of water in a scarcely explored region of the phase diagram, where water is both supercooled and at negative pressure. We find several anomalies: maxima in the adiabatic compressibility and nonmonotonic density dependence of the sound velocity, in contrast with a standard extrapolation of the equation of state. This is reminiscent of the behavior of supercritical fluids. To support this interpretation, we have performed simulations with the 2005 revision of the transferable interaction potential with four points. Simulations and experiments are in near-quantitative agreement, suggesting the existence of a line of maxima in κT (LMκT). This LMκT could either be the thermodynamic consequence of the line of density maxima of water [Sastry S, Debenedetti PG, Sciortino F, Stanley HE (1996) Phys Rev E 53:6144-6154], or emanate from a critical point terminating a liquid-liquid transition [Sciortino F, Poole PH, Essmann U, Stanley HE (1997) Phys Rev E 55:727-737]. At positive pressure, the LMκT has escaped observation because it lies in the "no man's land" beyond the homogeneous crystallization line. We propose that the LMκT emerges from the no man's land at negative pressure. PMID:24843177

    6. Anomalies in bulk supercooled water at negative pressure

      PubMed Central

      Pallares, Gaël; El Mekki Azouzi, Mouna; González, Miguel A.; Aragones, Juan L.; Abascal, José L. F.; Valeriani, Chantal; Caupin, Frédéric

      2014-01-01

      Water anomalies still defy explanation. In the supercooled liquid, many quantities, for example heat capacity and isothermal compressibility κT, show a large increase. The question arises if these quantities diverge, or if they go through a maximum. The answer is key to our understanding of water anomalies. However, it has remained elusive in experiments because crystallization always occurred before any extremum is reached. Here we report measurements of the sound velocity of water in a scarcely explored region of the phase diagram, where water is both supercooled and at negative pressure. We find several anomalies: maxima in the adiabatic compressibility and nonmonotonic density dependence of the sound velocity, in contrast with a standard extrapolation of the equation of state. This is reminiscent of the behavior of supercritical fluids. To support this interpretation, we have performed simulations with the 2005 revision of the transferable interaction potential with four points. Simulations and experiments are in near-quantitative agreement, suggesting the existence of a line of maxima in κT (LMκT). This LMκT could either be the thermodynamic consequence of the line of density maxima of water [Sastry S, Debenedetti PG, Sciortino F, Stanley HE (1996) Phys Rev E 53:6144–6154], or emanate from a critical point terminating a liquid–liquid transition [Sciortino F, Poole PH, Essmann U, Stanley HE (1997) Phys Rev E 55:727–737]. At positive pressure, the LMκT has escaped observation because it lies in the “no man’s land” beyond the homogeneous crystallization line. We propose that the LMκT emerges from the no man’s land at negative pressure. PMID:24843177

    7. 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.

    8. 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.

    9. The decrease in the IgG-binding capacity of intensively dry heated whey proteins is associated with intense Maillard reaction, structural changes of the proteins and formation of RAGE-ligands.

      PubMed

      Liu, Fahui; Teodorowicz, Małgorzata; van Boekel, Martinus A J S; Wichers, Harry J; Hettinga, Kasper A

      2016-01-01

      Heat treatment is the most common way of milk processing, inducing structural changes as well as chemical modifications in milk proteins. These modifications influence the immune-reactivity and allergenicity of milk proteins. This study shows the influence of dry heating on the solubility, particle size, loss of accessible thiol and amino groups, degree of Maillard reaction, IgG-binding capacity and binding to the receptor for advanced glycation end products (RAGE) of thermally treated and glycated whey proteins. A mixture of whey proteins and lactose was dry heated at 130 °C up to 20 min to mimic the baking process in two different water activities, 0.23 to mimic the heating in the dry state and 0.59 for the semi-dry state. The dry heating was accompanied by a loss of soluble proteins and an increase in the size of dissolved aggregates. Most of the Maillard reaction sites were found to be located in the reported conformational epitope area on whey proteins. Therefore the structural changes, including exposure of the SH group, SH-SS exchange, covalent cross-links and the loss of available lysine, subsequently resulted in a decreased IgG-binding capacity (up to 33%). The binding of glycation products to RAGE increased with the heating time, which was correlated with the stage of the Maillard reaction and the decrease in the IgG-binding capacity. The RAGE-binding capacity was higher in samples with a lower water activity (0.23). These results indicate that the intensive dry heating of whey proteins as it occurs during baking may be of importance to the immunological properties of allergens in cow's milk, both due to chemical modifications of the allergens and formation of AGEs. PMID:26524422

    10. 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

    11. 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.

    12. 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.

    13. 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.

    14. 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.

    15. Gibbs free energy of formation and heat capacity of PdO: A new calibration of the PdPdO buffer to high temperatures and pressures

      NASA Astrophysics Data System (ADS)

      Nell, J.; O'Neill, H. St. C.

      1996-07-01

      The oxygen potential defined by the reaction 2Pd + O 2 = 2PdO has been measured from 730 K to 1200 K using the electrochemical cell: Pt, Pd + PdO|CSZ|YDT (air), Pt. Measurements were taken while going up and down in temperature. Two rigorous tests of the reversibility of the data were also conducted by perturbing the composition of the gas phase in the cell. The Gibbs free energy of formation (in terms of 1 mol of O 2) relative to a reference pressure of 1 bar is given by Δ fGPdOo = -238842 + 316.129 T - 15.192 T ln T (J·mol -1 , temperature in K). The uncertainty is estimated to be ±40 J·mol -1 above 800 K and ±200 J·mol -1 at lower temperatures. This is in good agreement with several other studies conducted with a variety of different techniques. Cp of PdO was measured between 370 K and 1065 K using a differential scanning calorimeter operated in step heating mode. The data were fitted to a two-term expression, Cp = 71.08 - 531.6 T-0.5 (J·mol -1·K -1) . The uncertainty in the data is estimated to be ±1 J·mol -1·K -1. The heat capacity results are significantly different from the measurements of the only previous study, but a third-law analysis proved the Gibbs free energy of formation and heat capacity data to be internally consistent. From the third-law analysis we obtained values of 33.74J·mol -1·K -1 for S298.15o (PdO) and -117.42 KJ·mol -1 for Δ fH298.15o (PdO). The new thermodynamic data for PdO was used to revise the temperature and pressure dependence of the oxygen fugacity of the PdPdO buffer. Including corrections for the thermal expansivity and compressibility of Pd and PdO we obtain log 10fO 2 = 16.510 - 12473.4 T-1 - 1.826 log 10T + P{0.0627 T-1 - 5.22 × 10 -7 (1 - 298 T -1) + 10 -8 PT-1} ( T in Kelvin and P in bar) referenced to a standard state of 1 bar. It is also now possible to quantify the unexpected decrease in the activity coefficient of PdO in silicate melt with increasing temperature (in a diopside-anorthite eutectic melt

    16. Density variations and anomalies in palladium compacts

      SciTech Connect

      Back, D.; Jones, T.; Ransick, M.; Walburg, T.; Werkmeister, D.

      1992-05-14

      Low-density compacts of palladium powder have relative densities of about 30{plus_minus}10% TD. The variations in density are of concern for operations such as chemical/hydrogen pump systems because heat, mass, and momentum transport properties can be affected. Variations in density result from the inherent nature and interacting forces of UASA compaction of powder in cylinders. In addition to these expected variations, discontinuous density anomalies, such as cracks or high density ridges, are also found. An anomaly of particular concern was found to resemble a ``steer`s head.`` it is a symmetrical region of low density located at or near the center of a compact. Typically, this region is surrounded by a band of high density, compacted palladium that sometimes exceeds the density of the surrounding compact matrix by a factor of three. This report examines these density variations and anomalies both theoretically and empirically.

    17. Density variations and anomalies in palladium compacts

      SciTech Connect

      Back, D.; Jones, T.; Ransick, M.; Walburg, T.; Werkmeister, D.

      1992-05-14

      Low-density compacts of palladium powder have relative densities of about 30{plus minus}10% TD. The variations in density are of concern for operations such as chemical/hydrogen pump systems because heat, mass, and momentum transport properties can be affected. Variations in density result from the inherent nature and interacting forces of UASA compaction of powder in cylinders. In addition to these expected variations, discontinuous density anomalies, such as cracks or high density ridges, are also found. An anomaly of particular concern was found to resemble a steer's head.'' it is a symmetrical region of low density located at or near the center of a compact. Typically, this region is surrounded by a band of high density, compacted palladium that sometimes exceeds the density of the surrounding compact matrix by a factor of three. This report examines these density variations and anomalies both theoretically and empirically.

    18. Trace anomaly on a quantum spacetime manifold

      SciTech Connect

      Spallucci, Euro; Smailagic, Anais; Nicolini, Piero

      2006-04-15

      In this paper we investigate the trace anomaly in a space-time where single events are delocalized as a consequence of short distance quantum coordinate fluctuations. We obtain a modified form of heat kernel asymptotic expansion which does not suffer from short distance divergences. Calculation of the trace anomaly is performed using an IR regulator in order to circumvent the absence of UV infinities. The explicit form of the trace anomaly is presented and the corresponding 2D Polyakov effective action and energy-momentum tensor are obtained. The vacuum expectation value of the energy-momentum tensor in the Boulware, Hartle-Hawking and Unruh vacua is explicitly calculated in a rt section of a recently found, noncommutative inspired, Schwarzschild-like solution of the Einstein equations. The standard short distance divergences in the vacuum expectation values are regularized in agreement with the absence of UV infinities removed by quantum coordinate fluctuations.

    19. Astrometric solar system anomalies

      SciTech Connect

      Nieto, Michael Martin; Anderson, John D

      2009-01-01

      There are at least four unexplained anomalies connected with astrometric data. perhaps the most disturbing is the fact that when a spacecraft on a flyby trajectory approaches the Earth within 2000 km or less, it often experiences a change in total orbital energy per unit mass. next, a secular change in the astronomical unit AU is definitely a concern. It is increasing by about 15 cm yr{sup -1}. The other two anomalies are perhaps less disturbing because of known sources of nongravitational acceleration. The first is an apparent slowing of the two Pioneer spacecraft as they exit the solar system in opposite directions. Some astronomers and physicists are convinced this effect is of concern, but many others are convinced it is produced by a nearly identical thermal emission from both spacecraft, in a direction away from the Sun, thereby producing acceleration toward the Sun. The fourth anomaly is a measured increase in the eccentricity of the Moon's orbit. Here again, an increase is expected from tidal friction in both the Earth and Moon. However, there is a reported unexplained increase that is significant at the three-sigma level. It is produent to suspect that all four anomalies have mundane explanations, or that one or more anomalies are a result of systematic error. Yet they might eventually be explained by new physics. For example, a slightly modified theory of gravitation is not ruled out, perhaps analogous to Einstein's 1916 explanation for the excess precession of Mercury's perihelion.

    20. Improved methods for Feynman path integral calculations and their application to calculate converged vibrational–rotational partition functions, free energies, enthalpies, entropies, and heat capacities for methane

      SciTech Connect

      Mielke, Steven L. E-mail: truhlar@umn.edu; Truhlar, Donald G. E-mail: truhlar@umn.edu

      2015-01-28

      We present an improved version of our “path-by-path” enhanced same path extrapolation scheme for Feynman path integral (FPI) calculations that permits rapid convergence with discretization errors ranging from O(P{sup −6}) to O(P{sup −12}), where P is the number of path discretization points. We also present two extensions of our importance sampling and stratified sampling schemes for calculating vibrational–rotational partition functions by the FPI method. The first is the use of importance functions for dihedral angles between sets of generalized Jacobi coordinate vectors. The second is an extension of our stratification scheme to allow some strata to be defined based only on coordinate information while other strata are defined based on both the geometry and the energy of the centroid of the Feynman path. These enhanced methods are applied to calculate converged partition functions by FPI methods, and these results are compared to ones obtained earlier by vibrational configuration interaction (VCI) calculations, both calculations being for the Jordan–Gilbert potential energy surface. The earlier VCI calculations are found to agree well (within ∼1.5%) with the new benchmarks. The FPI partition functions presented here are estimated to be converged to within a 2σ statistical uncertainty of between 0.04% and 0.07% for the given potential energy surface for temperatures in the range 300–3000 K and are the most accurately converged partition functions for a given potential energy surface for any molecule with five or more atoms. We also tabulate free energies, enthalpies, entropies, and heat capacities.