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.
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
Thermal behavior, specific heat capacity and adiabatic time-to-explosion of G(FOX-7).
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.
Cooper, A; Cameron, D; Jakus, J; Pettigrew, G W
2007-12-01
It is widely acknowledged, and usually self-evident, that solvent water plays a crucial role in the overall thermodynamics of protein stabilization and biomolecular interactions. Yet we lack experimental techniques that can probe unambiguously the nature of protein-water or ligand-water interactions and how they might change during protein folding or ligand binding. PPC (pressure perturbation calorimetry) is a relatively new technique based on detection of the heat effects arising from application of relatively small pressure perturbations (+/-5 atm; 1 atm=101.325 kPa) to dilute aqueous solutions of proteins or other biomolecules. We show here how this can be related to changes in solvation/hydration during protein-protein and protein-ligand interactions. Measurements of 'anomalous' heat capacity effects in a wide variety of biomolecular interactions can also be related to solvation effects as part of a quite fundamental principle that is emerging, showing how the apparently unusual thermodynamics of interactions in water can be rationalized as an inevitable consequence of processes involving the co-operative interaction of multiple weak interactions. This leads to a generic picture of the thermodynamics of protein folding stabilization in which hydrogen-bonding plays a much more prominent role than has been hitherto supposed.
Sorai, Michio; Burriel, Ramón; Westrum, Edgar F; Hendrickson, David N
2008-04-10
Magnetic and thermal properties of the iron(III) spin crossover complex [Fe(3MeO-salenEt)(2)]PF(6) are very sensitive to mechanochemical perturbations. Heat capacities for unperturbed and differently perturbed samples were precisely determined by adiabatic calorimetry at temperatures in the 10-300 K range. The unperturbed compound shows a cooperative spin crossover transition at 162.31 K, presenting a hysteresis of 2.8 K. The anomalous enthalpy and entropy contents of the transition were evaluated to be Delta(trs)H = 5.94 kJ mol(-1) and Delta(trs)S = 36.7 J K(-1) mol(-1), respectively. By mechanochemical treatments, (1) the phase transition temperature was lowered by 1.14 K, (2) the enthalpy and entropy gains at the phase transition due to the spin crossover phenomenon were diminished to Delta(trs)H = 4.94 kJ mol(-1) and Delta(trs)S = 31.1 J K(-1) mol(-1), and (3) the lattice heat capacities were larger than those of the unperturbed sample over the whole temperature range. In spite of different mechanical perturbations (grinding with a mortar and pestle and grinding in a ball-mill), two sets of heat capacity measurements provided basically the same results. The mechanochemical perturbation exerts its effect more strongly on the low-spin state than on the high-spin state. It shows a substantial increase of the number of iron(III) ions in the high-spin state below the transition temperature. The heat capacities of the diamagnetic cobalt(III) analogue [Co(3MeO-salenEt)(2)]PF(6) also were measured. The lattice heat capacity of the iron compounds has been estimated from either the measurements on the cobalt complex using a corresponding states law or the effective frequency distribution method. These estimations have been used for the evaluation of the transition anomaly.
Magee, Joseph W.; Deal, Renee J.; Blanco, John C.
1998-01-01
A high-temperature adiabatic calorimeter has been developed to measure the constant-volume specific heat capacities (cV) of both gases and liquids, especially fluids of interest to emerging energy technologies. The chief design feature is its nearly identical twin bomb arrangement, which allows accurate measurement of energy differences without large corrections for energy losses due to thermal radiation fluxes. Operating conditions for the calorimeter cover a range of temperatures from 250 K to 700 K and at pressures up to 20 MPa. Performance tests were made with a sample of twice-distilled water. Heat capacities for water were measured from 300 K to 420 K at pressures to 20 MPa. The measured heat capacities differed from those calculated with an independently developed standard reference formulation with a root-mean-square fractional deviation of 0.48 %. PMID:28009375
THE HEAT CAPACITY OF FLUORINATED PROPANE AND BUTANE DERIVATIVES BY DIFFERENTIAL SCANNING CALORIMETRY
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...
NASA Astrophysics Data System (ADS)
Cruz-Orea, A.; Bentefour, E. H.; Jamée, P.; Chirtoc, M.; Glorieux, C.; Pitsi, G.; Thoen, J.
2003-01-01
Starch is one of the most important carbohydrate sources in human nutrition. For the thermal analysis of starch, techniques such as differential scanning calorimetry have been extensively used. As an alternative, we have applied a photopyroelectric (PPE) configuration and adiabatic scanning calorimetry (ASC) to study the thermal properties of starch-water systems. For this study we used nixtamalized corn flour and potato starch with different quantities of distilled water, in order to obtain samples with different moisture content. By using PPE and ASC methods we have measured, for each technique separately, the heat capacity by unit volume (ρcp) at room temperature for a corn flour sample at 90% moisture. The obtained values agree within experimental uncertainty. By using these techniques we also studied the thermal behavior of potato starch, at 80% moisture, in the temperature range where phase transitions occur. In this case the PPE signal phase could be used as a sensitive and versatile monitor for phase transitions.
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.
ERIC Educational Resources Information Center
Moore, William M.
1984-01-01
Describes the procedures and equipment for an experiment on the adiabatic expansion of gases suitable for demonstration and discussion in the physical chemical laboratory. The expansion produced shows how the process can change temperature and still return to a different location on an isotherm. (JN)
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.
Markin, Alexey V; Markhasin, Evgeny; Sologubov, Semen S; Ni, Qing Zhe; Smirnova, Natalia N; Griffin, Robert G
2015-02-05
We demonstrate application of precise adiabatic vacuum calorimetry to observation of phase transition in the tripeptide L-alanyl-L-prolyl-glycine monohydrate (APG) from 6 to 320 K and report the standard thermodynamic properties of the tripeptide in the entire range. Thus, the heat capacity of APG was measured by adiabatic vacuum calorimetry in the above temperature range. The tripeptide exhibits a reversible first-order solid-to-solid phase transition characterized by strong thermal hysteresis. We report the standard thermodynamic characteristics of this transition and show that differential scanning calorimetry can reliably characterize the observed phase transition with <5 mg of the sample. Additionally, the standard entropy of formation from the elemental substances and the standard entropy of hypothetical reaction of synthesis from the amino acids at 298.15 K were calculated for the studied tripeptide.
Heat capacities and thermodynamic properties of annite (aluminous iron biotite)
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
Zhang, Yu; Wu, Hao; Xu, Kangzhen; Zhang, Wantao; Ren, Zhaoyu; Song, Jirong; Zhao, Fengqi
2014-02-20
A new energetic copper complex of dinitroacetonitrile (DNANT), [Cu(NH3)4](DNANT)2, was first synthesized through an unexpected reaction. The thermal decomposition of [Cu(NH3)4](DNANT)2 was studied with DSC and TG/DTG methods. The gas products were analyzed through a TG-FTIR-MS method. The nonisothermal kinetic equation of the exothermic process is dα/dT = 10(10.92)/β4(1 - α)[-ln(1 - α)](3/4) exp(-1.298 × 10(5)/RT). The self-accelerating decomposition temperature and critical temperature of thermal explosion are 217.9 and 221.0 °C. The specific heat capacity of [Cu(NH3)4](DNANT)2 was determined with a micro-DSC method, and the molar heat capacity is 512.6 J mol(-1) K(-1) at 25 °C. Adiabatic time-to-explosion of Cu(NH3)4(DNANT)2 was also calculated to be about 137 s.
Determination of caloric values of agricultural crops and crop waste by Adiabatic Bomb Calorimetry
Technology Transfer Automated Retrieval System (TEKTRAN)
Calorific values of agricultural crops and their waste were measured by adiabatic bomb calorimetry. Sustainable farming techniques require that all potential sources of revenue be utilized. A wide variety of biomass is beginning to be used as alternative fuels all over the world. The energy potentia...
Bastos, Margarida; Alves, Nuno; Maia, Sílvia; Gomes, Paula; Inaba, Akira; Miyazaki, Yuji; Zanotti, Jean-Marc
2013-10-21
In the present work we bridge neutron scattering and calorimetry in the study of a low-hydration sample of a 15-residue hybrid peptide from cecropin and mellitin CA(1-7)M(2-9) of proven antimicrobial activity. Quasielastic and low-frequency inelastic neutron spectra were measured at defined hydration levels - a nominally 'dry' sample (specific residual hydration h = 0.060 g/g), a H2O-hydrated (h = 0.49) and a D2O-hydrated one (h = 0.51). Averaged mean square proton mobilities were derived over a large temperature range (50-300 K) and the vibrational density of states (VDOS) were evaluated for the hydrated samples. The heat capacity of the H2O-hydrated CA(1-7)M(2-9) peptide was measured by adiabatic calorimetry in the temperature range 5-300 K, for different hydration levels. The glass transition and water crystallization temperatures were derived in each case. The existence of different types of water was inferred and their amounts calculated. The heat capacities as obtained from direct calorimetric measurements were compared to the values derived from the neutron spectroscopy by way of integrating appropriately normalized VDOS functions. While there is remarkable agreement with respect to both temperature dependence and glass transition temperatures, the results also show that the VDOS derived part represents only a fraction of the total heat capacity obtained from calorimetry. Finally our results indicate that both hydration water and the peptide are involved in the experimentally observed transitions.
NASA Astrophysics Data System (ADS)
Nagoe, Atsushi; Oguni, Masaharu; Fujimori, Hiroki
2015-03-01
Heat capacities and spontaneous enthalpy-relaxation effects of the benzene confined in silica MCM-41 and SBA-15 pores with uniform diameters were measured by high-precision adiabatic calorimetry. The fusion temperatures and fusion enthalpies determined were compared with the literature results of benzene confined within pores of CPG glasses. It was confirmed, from the observed spontaneous heat-release or -absorption effects, that there exists a non-crystallizing amorphous component of confined benzene, as reported previously. The pore-diameter dependence of fusion enthalpy observed was inconsistent with the previously proposed model which suggested that the non-crystallizing amorphous component is located on the pore wall in the form of a shell-like structure of a few nm in thickness. A very slow relaxation process corresponding to a translational-diffusion motion of molecule was observed, indicating that the benzene fills the pores incompletely along the pore channel. In addition, we found that the fusion enthalpy as a function of inverse pore-diameter dependence decreases steeply in the range of 60-10 nm in diameter while gradually in the range around 5 nm.
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.
Heat Capacity of Poly(L-lactic acid)
NASA Astrophysics Data System (ADS)
Pyda, Marek; Bopp, C. Bopp Richard C.; Richard, C.; Wunderlich, Bernhard
2002-03-01
The heat capacity of poly(L-lactic acid) (PLA) is reported from 5-520 K from standard differential scanning calorimetry (DSC), temperature modulated DSC (TMDSC), and adiabatic calorimetry. The semicrystalline PLA has a melting endotherm between 418 and 432 K, with variable heats of fusion, depending on thermal history. The thermodynamic heat of fusion is 6.15 kJ/mol. The heat capacity is linked to its group vibrational spectrum and the skeletal vibrations described by the Tarasov equation (theta parameters 574 and 52 K, N = 9). Calculated and experimental heat capacities agree to ±3compares within ±0.5contributions of other polymers with the same constituent groups. The glass transition temperature of liquid PLA is at 333 K with a change in heat capacity of about 41 J/(K mol). With these results, the enthalpy, entropy, and Gibbs function were obtained. For semicrystalline samples one can then discuss the crystallinity changes with temperature, the question of a rigid-amorphous fraction, and the reversible melting. --- Supported by NSF, Polymers Program, DMR-9703692, and the Div. of Mat. Sci., BES, DOE at ORNL, managed by UT-Batelle, LLC, for the U.S. Department of Energy, under contract number DOE-AC05-00OR22725.
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…
MEASUREMENT OF SPECIFIC HEAT CAPACITY OF SALTSTONE
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
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.
Heat capacity of solid proteins by thermal analysis
Zhang, Ge; Wunderlich, B.
1997-11-01
In a continuing effort to better understand the thermodynamic properties of proteins, solid state heat capacities of poly(amino acid)s of all 21 naturally occurring amino 4 copoly(amino acid)s and about 10 proteins have been analyzed by now using the Advanced Thermal Analysis System, ATHAS. The experimental measurements were performed with adiabatic and differential scanning calorimetry from 10 to about 450 K. The heat capacities of the samples in their pure, solid states are linked to an approximate vibrational spectrum by making use of known group vibrations and a set of parameters, {Theta}{sub 1} and {Theta}{sub 3}, of the Tarasov function for the skeletal vibrations. Good agreement is found between experiment and calculation with root mean square errors mostly within {+-}3%. The experimental data were analyzed also with an empirical addition scheme using data for the poly(amino acid)s. Based on this study, vibrational heat capacity can now be predicted for all proteins with an accuracy comparable to common experiments. Furthermore, gradual transitions, indicative of molecular motion prior to devitrification, melting, or decomposition, can be identified. The new experimental data compared here with the prior samples are: bovine {beta}-lactoglobulin, chicken lysozyme and ovalbumin.
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
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.
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.
Hemingway, B.S.; Barton, M.D.; Robie, R.A.; Haselton, H.T.
1986-01-01
The heat capacities of beryl, phenakite, euclase and bertrandite have been measured between approx 5 and 800 K by combined quasi-adiabatic cryogenic calorimetry and differential scanning calorimetry. The heat capacities of chrysoberyl have been measured from 340 to 800 K. The resulting data have been combined with solution and phase-equilibrium experimental data and simultaneously adjusted using the programme PHAS20 to provide an internally consistent set of thermodynamic properties for several important beryllium phases. The experimental heat capacities and tables of derived thermodynamic properties are presented.-J.A.Z.
NASA Astrophysics Data System (ADS)
Fabjan, C. W.; Fournier, D.
This document is part of Part 1 'Principles and Methods' of Subvolume B 'Detectors for Particles and Radiation' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Section '3.2 Calorimetry' of Chapter '3 Particle Detectors and Detector Systems' with the content:
Heat capacity of poly(trimethylene terephthalate)
Pyda, M.; Boller, A.; Wunderlich, B. |; Grebowicz, J.; Chuah, H.
1997-12-01
Thermal analysis of poly(trimethylene terephthalate) (PTT) has been carried out using standard differential scanning calorimetry and temperature-modulated differential scanning calorimetry. Heat capacities of the solid and liquid states of semicrystalline PTT are reported from 190 K to 570 K. The semicrystalline PTT has a glass transition temperature of about 331 K. Between 460 K and 480 K, PTT shows an exothermic ordering. The melting endotherm occurs between 480 K and 505 K with an onset temperature of 489.15 K (216 C). The heat of fusion of typical semicrystalline samples is 13.8 kJ/mol. For 100% crystalline PTT the heat of fusion is estimated to be 28--30 kJ/mol. The heat capacity of solid PTT is linked to an approximate group vibrational spectrum, and the Tarasov equation is used to estimate the skeletal vibrational heat capacity ({Theta}{sub 1} = 542 K and {Theta}{sub 3} = 42 K). A comparison of calculation and experimental heat capacities show agreement of better than {+-}2% between 190--300 K. The experimental heat capacity of liquid PTT can be expressed as a linear function of temperature: C{sub p} {sup L}(exp) = 211.6 + 0.434 T J/(K mol) and compares well with estimations from the ATHAS data bank using group contributions of other polymers with the same constituent groups ({+-} 0.5%). The change of heat capacity at T{sub g} of amorphous PTT has been estimated from the heat capacities of liquid and solid to be 86.4 J/(K mol). Knowing C{sub p} of the solid, liquid, and the transition parameters, the thermodynamic functions: enthalpy, entropy and Gibbs function were obtained.
Heat capacities and thermodynamic properties of braunite (Mn7 SiO12) and rhodonite (MnSiO3)
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
Heat capacities and entropies of rhodochrosite (MnCO3) and siderite (FeCO3) between 5 and 600 K.
Robie, R.A.; Haselton, H.T.; 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.
Heat Capacity of Hydrous Silicate Melts
NASA Astrophysics Data System (ADS)
Robert, G.; Whittington, A. G.; Stechern, A.; Behrens, H.
2015-12-01
We determined the heat capacities of four series of glasses and liquids of basaltic and basaltic andesite compositions including two natural remelts from Fuego volcano, Guatemala, and two Fe-free analogs. The samples are low-alkali, Ca- and Mg-rich aluminosilicates with non-bridging oxygen to tetrahedrally-coordinated cation ratios (NBO/T) ranging between 0.33 and 0.67. Differential scanning calorimetry measurements were performed at atmospheric pressure between room temperature and ≈100 K above the glass transition for hydrous samples and up to ≈1800 K for dry samples. The water contents investigated range up to 5.34 wt.% (16.4 mol%). Water does not measurably affect the heat capacity of glasses (T
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.
Heat capacity change for ribonuclease A folding.
Pace, C. N.; Grimsley, G. R.; Thomas, S. T.; Makhatadze, G. I.
1999-01-01
The change in heat capacity deltaCp for the folding of ribonuclease A was determined using differential scanning calorimetry and thermal denaturation curves. The methods gave equivalent results, deltaCp = 1.15+/-0.08 kcal mol(-1) K(-1). Estimates of the conformational stability of ribonuclease A based on these results from thermal unfolding are in good agreement with estimates from urea unfolding analyzed using the linear extrapolation method. PMID:10422839
NASA Astrophysics Data System (ADS)
Prabhu, Ninad V.; Sharp, Kim A.
2005-05-01
Heat capacity (Cp) is one of several major thermodynamic quantities commonly measured in proteins. With more than half a dozen definitions, it is the hardest of these quantities to understand in physical terms, but the richest in insight. There are many ramifications of observed Cp changes: The sign distinguishes apolar from polar solvation. It imparts a temperature (T) dependence to entropy and enthalpy that may change their signs and which of them dominate. Protein unfolding usually has a positive ΔCp, producing a maximum in stability and sometimes cold denaturation. There are two heat capacity contributions, from hydration and protein-protein interactions; which dominates in folding and binding is an open question. Theoretical work to date has dealt mostly with the hydration term and can account, at least semiquantitatively, for the major Cp-related features: the positive and negative Cp of hydration for apolar and polar groups, respectively; the convergence of apolar group hydration entropy at T ≈ 112°C; the decrease in apolar hydration Cp with increasing T; and the T-maximum in protein stability and cold denaturation.
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.
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
NASA Astrophysics Data System (ADS)
Chen, Wei-Chun; Wang, Yih-Wen; Shu, Chi-Min
2016-06-01
Use of adiabatic calorimetry to characterise thermal runaway of Li-ion cells is a crucial technique in battery safety testing. Various states of charge (SoC) of Li-ion cells were investigated to ascertain their thermal runaway features using a Vent Sizing Package 2 (VSP2) adiabatic calorimeter. To evaluate the thermal runaway characteristics, the temperature-pressure-time trajectories of commercial cylindrical cells were tested, and it was found that cells at a SoC of greater than 50% were subject to thermal explosion at elevated temperatures. Calorimetry data from various 18650 Li-ion cells with different SoC were used to calculate the thermal explosion energies and chemical kinetics; furthermore, a novel self-heating model based on a pseudo-zero-order reaction that follows the Arrhenius equation was found to be applicable for studying the exothermic reaction of a charged cell.
Haselton, H.T.; Hemingway, B.S.; Robie, R.A.
1984-01-01
Low-T heat capacities (5-380 K) have been measured by adiabatic calorimetry for synthetic CaAl2SiO6 glass and pyroxene. High-T unit cell parameters were measured for CaAl2SiO6 pyroxene by means of a Nonius Guinier-Lenne powder camera in order to determine the mean coefficient of thermal expansion in the T range 25-1200oC. -J.A.Z.
Shimizu, Yoshitaka; Ohte, Yoko; Yamamura, Yasuhisa; Saito, Kazuya; Atake, Tooru
2006-07-20
Heat capacities of liquid, stable crystal, and liquid-quenched glass of a room-temperature ionic liquid (RTIL), 1-hexyl-3-methylimidazolium bis(trifluromethylsulfonyl)imide were measured between 5 and 310 K by adiabatic calorimetry. Heat capacity of the liquid at 298.15 K was determined for an IUPAC project as (631.6 +/- 0.5) J K(-1) mol(-1). Fusion was observed at T(fus) = 272.10 K for the stable crystalline phase, with enthalpy and entropy of fusion of 28.34 kJ mol(-1) and 104.2 J K(-1) mol(-1), respectively. The purity of the sample was estimated as 99.83 mol % by the fractional melting method. The liquid could be supercooled easily and the glass transition was observed around T(g) approximately 183 K, which was in agreement with the empirical relation, T(g) approximately ((2)/(3)) T(fus). The heat capacity of the liquid-quenched glass was larger than that of the crystal as a whole. In the lowest temperature region, however, the difference between the two showed a maximum around 6 K and a minimum around 15 K, at which the heat capacity of the glass was a little smaller than that of crystal.
Heat capacities of synthetic hedenbergite, ferrobustamite and CaFeSi2O6 glass
Haselton, H.T.; 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.
The heat capacity of hydrous cordierite above 295 K
NASA Astrophysics Data System (ADS)
Carey, J. William
1993-04-01
The heat capacity of synthetic hydrous cordierite (Mg2Al4Si5O18·nH2O) has been determined by differential scanning calorimetry (DSC) from 295 to 425 K as a function of H2O content. Six samples with H2O contents ranging from 0 to 0.82 per formula unit were examined. The partial molar heat capacity of H2O in cordierite over the measured temperature interval is independent of composition and temperature within experimental uncertainty and is equal to 43.3 ±0.8 J/mol/ K. This value exceeds the molar heat capacity of gaseous H2O by 9.7 J/mol/K, but is significantly smaller than the heat capacity of H2O in several zeolites and liquid H2O. A statistical-mechanical model of the heat capacity of adsorbed gas species (Barrer 1978) is used to extrapolate the heat capacity of hydrous cordierite to temperatures greater than 425 K. In this model, the heat capacity of hydrous cordierite (Crd·nH2O) is represented as follows: Cp(Crd · nH2O) = Cp(Crd)+ n{Cp(H2O, gas)+ R(gas constant)} (1) An examination of calorimetric data for hydrous beryl, analcime, mordenite, and clinoptilolite (Hemingway et al. 1986; Johnson et al. 1982, 1991, 1992) demonstrates the general applicability of the statistical-mechanical model for the extrapolation of heat capacity data of zeolitic minerals. The heat capacity data for cordierite are combined with the data of Carey and Navrotsky (1992) to obtain the molar enthalpy of formation and enthalpy of hydration of hydrous cordierite as a function of temperature.
Quartz: heat capacities from 340 to 1000 K and revised values for the thermodynamic properties.
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.
Hemingway, B.S.; Bohlen, S.R.; Hankins, W.B.; Westrum, E.F.; 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.
Molar heat capacity and entropy of calcium metal
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.
Kurata, Masaki; Devanathan, Ramaswami
2015-10-13
Free energy and heat capacity of actinide elements and compounds are important properties for the evaluation of the safety and reliable performance of nuclear fuel. They are essential inputs for models that describe complex phenomena that govern the behaviour of actinide compounds during nuclear fuel fabrication and irradiation. This chapter introduces various experimental methods to measure free energy and heat capacity to serve as inputs for models and to validate computer simulations. This is followed by a discussion of computer simulation of these properties, and recent simulations of thermophysical properties of nuclear fuel are briefly reviewed.
Robie, R.A.; Evans, H.T.; Hemingway, B.S.
1988-01-01
The heat capacity of ilvaite from Seriphos, Greece was measured by adiabatic shield calorimetry (6.4 to 380.7 K) and by differential scanning calorimetry (340 to 950 K). The thermal expansion of ilvaite was also investigated, by X-ray methods, between 308 and 853 K. At 298.15 K the standard molar heat capacity and entropy for ilvaite are 298.9??0.6 and 292.3??0.6 J/(mol. K) respectively. Between 333 and 343 K ilvaite changes from monoclinic to orthorhombic. The antiferromagnetic transition is shown by a hump in Cp0with a Ne??el temperature of 121.9??0.5 K. A rounded hump in Cp0between 330 and 400 K may possibily arise from the thermally activated electron delocalization (hopping) known to take place in this temperature region. ?? 1988 Springer-Verlag.
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.
Miyazaki, Y; Bhattacharjee, A; Nakano, M; Saito, K; Aubin, S M; Eppley, H J; Christou, G; Hendrickson, D N; Sorai, M
2001-12-17
Accurate heat capacities of the single-molecule magnet [Mn(12)O(12)(O(2)CEt)(16)(H(2)O)(3)] were measured from 0.3 to 311 K by adiabatic calorimetry without an external magnetic field. Heat-capacity anomalies were separated by assuming several contributions including lattice vibration, magnetic anisotropy, and hyperfine splitting. Among them, a tiny thermal anomaly between 1 and 2 K is attributable to the presence of Jahn-Teller isomers. The heat capacities of the polycrystalline sample were also measured with applied magnetic fields from 0 to 9 T in the 2-20 K temperature region by the relaxation method. With an applied magnetic field of up to 2 T, a steplike heat-capacity anomaly was observed around the blocking temperature T(B) approximately 3.5 K. The magnitude of the anomaly reached a maximum at 0.7 T. With a further increase in the magnetic field, the step was decreasing, and finally it disappeared above 3 T. The step at T(B) under 0.7 T can be roughly accounted for by assuming that a conversion between the up-spin and down-spin states is allowed above T(B) by phonon-assisted quantum tunneling, while it is less effective below T(B). Excess heat capacity under a magnetic field revealed a large heat-capacity hump around 14 K and 2 T, which would be attributed to a thermal excitation from the S = 9 ground state to the spin manifold with different S values, where S is the total spin quantum number.
The heat-capacity of ilmenite and phase equilibria in the system Fe-T-O
Anovitz, Lawrence M.; Treiman, A.H.; Essene, E.J.; Hemingway, B.S.; Westrum, E.F.; 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.
Compressibility and heat capacity of rotating plasma
NASA Astrophysics Data System (ADS)
Geyko, V. I.; Fisch, N. J.
2017-02-01
A rotating plasma column is shown to exhibit unusual heat capacity effects under compression. For near equilibrium thermodynamics and smooth wall conditions, the heat capacity depends on the plasma density, on the speed of the rotation, and on the mass ratio. For a certain range of parameters, the storage of energy in the electric field produces a significant increase in the heat capacity.
The low-temperature heat capacity of fullerite C60
NASA Astrophysics Data System (ADS)
Bagatskii, M. I.; Sumarokov, V. V.; Barabashko, M. S.; Dolbin, A. V.; Sundqvist, B.
2015-08-01
The heat capacity at constant pressure of fullerite C60 has been investigated using an adiabatic calorimeter in a temperature range from 1.2 to 120 K. Our results and literature data have been analyzed in a temperature interval from 0.2 to 300 K. The contributions of the intramolecular and lattice vibrations into the heat capacity of C60 have been separated. The contribution of the intramolecular vibration becomes significant above 50 K. Below 2.3 K the experimental temperature dependence of the heat capacity of C60 is described by the linear and cubic terms. The limiting Debye temperature at T →0 K has been estimated (Θ0 = 84.4 K). In the interval from 1.2 to 30 K the experimental curve of the heat capacity of C60 describes the contributions of rotational tunnel levels, translational vibrations (in the Debye model with Θ0 = 84.4 K), and librations (in the Einstein model with ΘE,lib = 32.5 K). It is shown that the experimental temperature dependences of heat capacity and thermal expansion are proportional in the region from 5 to 60 K. The contribution of the cooperative processes of orientational disordering becomes appreciable above 180 K. In the high-temperature phase the lattice heat capacity at constant volume is close to 4.5 R, which corresponds to the high-temperature limit of translational vibrations (3 R) and the near-free rotational motion of C60 molecules (1.5 R).
Heat Capacity of 1D Molecular Chains
NASA Astrophysics Data System (ADS)
Bagatskii, M. I.; Barabashko, M. S.; Sumarokov, V. V.; Jeżowski, A.; Stachowiak, P.
2017-04-01
The heat capacity of 1D chains of nitrogen and methane molecules (adsorbed in the outer grooves of bundles of closed-cap single-walled carbon nanotubes) has been studied in the temperature ranges 2-40 and 2-60 K, respectively. The temperature dependence of the heat capacity of 1D chains of nitrogen molecules below 3 K is close to a linear. It was found that the rotational heat capacity of methane molecules is a significant part of the total heat capacity of the chains throughout the whole investigated temperature range, whereas in the case of nitrogen, the librations are significant only above 15 K. The dependence of the heat capacity for methane below 10 K indicates the presence of a Schottky anomaly caused by the tunneling between the lowest energy levels of the CH4 molecule rotational spectra. Characteristic features observed in the temperature dependence of the heat capacity of 1D methane crystals are also discussed.
The decarbonation and heat capacity of ZnCO3
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.
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.
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…
Heat capacity, enthalpy and entropy of ternary bismuth tantalum oxides
NASA Astrophysics Data System (ADS)
Leitner, J.; Jakeš, V.; Sofer, Z.; Sedmidubský, D.; Růžička, K.; Svoboda, P.
2011-02-01
Heat capacity and enthalpy increments of ternary bismuth tantalum oxides Bi 4Ta 2O 11, Bi 7Ta 3O 18 and Bi 3TaO 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 Cpm =445.8+0.005451 T-7.489×10 6/ T2 J K -1 mol -1, Cpm =699.0+0.05276 T-9.956×10 6/ T2 J K -1 mol -1 and Cpm =251.6+0.06705 T-3.237×10 6/ T2 J K -1 mol -1 for Bi 3TaO 7, Bi 4Ta 2O 11 and for Bi 7Ta 3O 18, respectively, were derived by the least-squares method from the experimental data. The molar entropies at 298.15 K, S° m(298.15 K)=449.6±2.3 J K -1 mol -1 for Bi 4Ta 2O 11, S° m(298.15 K)=743.0±3.8 J K -1 mol -1 for Bi 7Ta 3O 18 and S° m(298.15 K)=304.3±1.6 J K -1 mol -1 for Bi 3TaO 7, were evaluated from the low-temperature heat capacity measurements.
Thermodynamics of micellization from heat-capacity measurements.
Šarac, Bojan; Bešter-Rogač, Marija; Lah, Jurij
2014-06-23
Differential scanning calorimetry (DSC), the most important technique for studying the thermodynamics of structural transitions of biological macromolecules, is seldom used in quantitative thermodynamic studies of surfactant micellization/demicellization. The reason for this could be ascribed to an insufficient understanding of the temperature dependence of the heat capacity of surfactant solutions (DSC data) in terms of thermodynamics, which leads to problems with the design of experiments and interpretation of the output signals. We address these issues by careful design of DSC experiments performed with solutions of ionic and nonionic surfactants at various surfactant concentrations, and individual and global mass-action model analysis of the obtained DSC data. Our approach leads to reliable thermodynamic parameters of micellization for all types of surfactants, comparable with those obtained by using isothermal titration calorimetry (ITC). In summary, we demonstrate that DSC can be successfully used as an independent method to obtain temperature-dependent thermodynamic parameters for micellization.
NASA Astrophysics Data System (ADS)
Tkachenko, E. S.; Druzhinina, A. I.; Varushchenko, R. M.; Tarazanov, S. V.; Nesterova, T. N.; Reshetova, M. D.; Polyakova, O. V.
2013-05-01
The heat capacities of 2-methylbiphenyl and 3,3'-dimethylbiphenyl are measured by means of low-temperature adiabatic calorimetry in the temperature range of 6 to 372 K. The thermodynamic characteristics of fusion and the glass transition of the investigated compounds are determined. The saturation vapor pressure and enthalpy of vaporization of 3,3'-dimethylbiphenyl are determined according to the dynamic method based on the transfer of a substance vapor in a helium flow. The absolute entropies and changes in Gibbs energies of biphenyl derivatives are calculated from the data obtained in the condensed and ideal gas states. The contribution of the Cb-(Cb) group is determined using the Benson additive method for calculating the absolute entropies of biphenyl derivatives in the liquid state (where Cb is the carbon atom in a benzene ring).
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.
Heat Capacity, Body Temperature, and Hypothermia
NASA Astrophysics Data System (ADS)
Kimbrough, Doris R.
1998-01-01
Even when air and water are at the same temperature, water will "feel" distinctly colder to us. This difference is due to the much higher heat capacity of water than of air. Offered here is an interesting life science application of water's high heat capacity and its serious implications for the maintenance of body temperature and the prevention of hypothermia in warm-blooded animals.
The heat capacity of solid antimony selenide
NASA Astrophysics Data System (ADS)
Pashinkin, A. S.; Malkova, A. S.; Mikhailova, M. S.
2008-06-01
The literature data on the heat capacity of solid antimony selenide over the temperature range 53 K- T m were analyzed. The heat capacity of Sb2Se3 was measured from 350 to 600 K on a DSM-2M calorimeter. The experimental data were used to calculate the dependence C p = a + bT + cT -2 and the thermodynamic functions of solid Sb2Se3 over the temperature range 298.15 700 K.
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.
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
Heat Capacity Study of Solution Grown Crystals of Isotactic Polystyrene
Xu,H.; Cebe, P.
2005-01-01
We have performed measurements of the specific heat capacity on isotactic polystyrene (iPS) crystals grown from dilute solution. Solution grown crystal (SGC) samples had larger crystal fractions and greatly reduced rigid amorphous fractions compared to their bulk cold-crystallized counterparts. Heat capacity studies were performed from below the glass transition temperature to above the melting temperature by using quasi-isothermal temperature modulated differential scanning calorimetry (TMDSC) and standard DSC. Two or three endotherms are observed, which represent the melting of crystals. The small rigid amorphous fraction relaxes in a wide temperature range from just above the glass transition temperature to just below the first crystal melting endotherm. As in bulk iPS, 1 multiple reversing melting was found in iPS SGCs, supporting the view that double melting in iPS may be due to dual thermal stability distribution existing along one single lamella.2 The impact of reorganization and annealing on the melt endotherms was also investigated. Annealing occurs as a result of the very slow effective heating rate of the quasi-isothermal measurements compared to standard DSC. The improvement of crystal perfection through annealing causes the reversing melting endotherms to occur at a temperature higher than the endotherms seen in the standard DSC scan.
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.
Specific Heat Capacity Measurement of Single-Crystalline Silicon as New Reference Material
NASA Astrophysics Data System (ADS)
Abe, Haruka; Kato, Hideyuki; Baba, Tetsuya
2011-11-01
We started to develop a new certified reference material for specific heat capacity measurement using a new type of cryogenic adiabatic calorimeter, applying a pulse-tube cryocooler in the temperature range from 50 to 350 K. A candidate certified reference material is single-crystalline silicon. To check the performance of the equipment, we measured the specific heat capacity of NIST SRM720, a type of synthetic sapphire. The relative expanded uncertainty of the measurement was estimated to be 0.65% at 350 K and 8.2% at 50 K, and the certified value of SRM720 was within the limits of uncertainty. In the next step, we measured the temperature dependence of the specific heat capacity of single-crystalline silicon. The result was compared with some reference data, and good agreement within 0.6% residual was found.
Estimating heat capacity and heat content of rocks
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.
NASA Astrophysics Data System (ADS)
Zhi, Chunyi; Bando, Yoshio; Tang, Chengchun; Golberg, Dmitri
2011-01-01
We report on the basic physical quantities of boron nitride nanotubes (BNNTs), namely specific heat capacity and density, which have not been measured to date. A series of differential scanning calorimetry experiments were performed, and specific heat capacity was calculated for multi-walled BNNTs synthesized by chemical vapor deposition using boron and metal oxide as precursor. Very close specific heat capacity values were revealed for BNNTs and a BN powder of hexagonal (h-BN) phase. Densities of BNNTs were measured through density analyses of their epoxy composites. Our work is important as far as bulk properties of large amounts of BNNTs are crucial, for example, thermal property and density prediction for composite materials with BNNTs embedded.
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).
Heat capacity and phase equilibria of almandine, Fe3Al2Si3O12
Anovitz, Lawrence M.; Essene, E.J.; Metz, G.W.; Bohlen, S.R.; Westrum, E.F.; 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.
Yang, Miao; Zhao, Jun-Ning; Liu, Qing-Shan; Sun, Li-Xian; Yan, Pei-Fang; Tan, Zhi-Cheng; Welz-Biermann, Urs
2011-01-07
Two chelated orthoborate ionic liquids (ILs), 1-butyl-3-methylimidazolium bis(oxalato)borate ([Bmim][BOB]) and 1-hexyl-3-methylimidazolium bis(oxalato)borate ([Hmim][BOB]), were prepared and characterized. Their thermodynamic properties were studied using adiabatic calorimetry and differential scanning calorimetry (DSC). The thermodynamic properties of the two ILs were evaluated and compared with each other, and then with those of other [Bmim] type ILs. The results clearly indicate that for a given cation (or anion) and at a certain temperature, the more atoms in the anion (or cation), the higher the heat capacity; the higher glass-transition temperatures of [BOB] type ILs than others are mainly caused by the higher symmetry of the orthoborate anion structure. It is suggested that a high content of strong electronegative atoms and C(n) or C(nv) (n = 1,2,3,…,∞) point group symmetry in the anion are favorable for the design and synthesis of room temperature ILs with a wide liquid range.
Enthalphyand Heat Capacity of Several Candy Products,
They are three types of chocolate : ’Extra with Milk,’ ’Sport,’ and ’Soy Bean’ without ground nuts and sugar. For a caloric investigation of the candy products an adiabatic calorimeter was used.
Seal, R.R.; Robie, R.A.; Hemingway, B.S.; Evans, H.T.
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.
NASA Astrophysics Data System (ADS)
Novikov, A. N.
2014-10-01
The heat capacity and density of potassium iodide solutions in a mixed N-methylpyrrolidone (MP)-water solvent with a low content of the organic component are measured via calorimetry and densimetry at 298.15 K. Standard partial molal heat capacities and volumes of potassium iodide in MP-water mixtures are calculated. Standard heat capacities and volumes of potassium and iodide ions are determined. The character of the changes in heat capacity and volume are discussed on the basis of calculating additivity coefficients δ c and δ v upon the mixing of isomolal binary solutions KI-MP and KI-water, depending on the composition of the MP-H2O mixture and the concentration of the electrolyte.
The Solid-State Heat-Capacity Laser
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.
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.
Modeling the Heat Capacity of Spider Silk Inspired Di-block Copolymers
NASA Astrophysics Data System (ADS)
Huang, W.; Krishnaji, S.; Kaplan, D.; Cebe, P.
2011-03-01
We synthesized and characterized a new family of di-block copolymers based on the amino acid sequences of Nephila clavipes major ampulate dragline spider silk, having the form HABn and HBAn (n=1-6), comprising an alanine-rich hydrophobic block, A, a glycine-rich hydrophilic block, B, and a histidine tag, H. Using temperature modulated differential scanning calorimetry (TMDSC), we captured the effect of bound water acting as a plasticizer for copolymer films which had been cast from water solution and dried. We determined the water content by thermogravimetry and used the weight loss vs. temperature to correct the mass in TMDSC experiments. Our result shows that non-freezing bound water has a strong plasticization effect which lowers the onset of the glass transition by about 10circ; C. The reversing heat capacities, Cp(T), for temperatures below and above the glass transition were also characterized by TMDSC. We then calculated the solid state heat capacities of our novel block copolymers below the glass transition (Tg) based on the vibrational motions of the constituent poly(amino acid)s, whose heat capacities are known from the ATHAS Data Bank. Excellent agreement was found between the measured and calculated values of the heat capacity, showing that this model can serve as a standard method to predict the solid state Cp for other biologically inspired block copolymers. Support was provided from the NSF CBET-0828028 and the MRI Program under DMR-0520655 for thermal analysis instrumentation.
NASA Astrophysics Data System (ADS)
Keilin, V. E.; Kovalev, I. A.; Kruglov, S. L.; Lupanov, D. É.; Shcherbakov, V. I.
2008-05-01
We have studied the thermomagnetic stability (with respect to magnetic flux disturbances) of composite superconductors screened by additives of rare earth compounds possessing extremely high heat capacity at low temperatures. Three tubular composite structures have been manufactured and studied with respect to screening of the central region from variations of an external magnetic field. The effect of large-heat-capacity substances (LHCSs) was evaluated by measuring a jump in the magnetic flux in response to the rate of variation (ramp) of the external magnetic field. It is established that the adiabatic criterion of stability (magnetic-flux jump field) in the sample structures containing LHCSs significantly increases—by 20% for HoCu2 intermetallic compound and 31% for Gd2O2S ceramics—as compared to the control structure free of such additives.
Theoretical calculation of heat capacity by using third virial coefficient
NASA Astrophysics Data System (ADS)
Mamedov, Bahtiyar Akber; Somuncu, Elif
2017-02-01
We have presented a new formula to determine the heat capacity for real gaseous. This formula is a simple and more accurate analytical approximation for heat capacity using third virial coefficient over Lennard-Jones (12-6) potential. The calculation results of heat capacity show a good agreement with the data in the literature. The consistency of results demonstrates that the proposed formula is applicable to real gaseous.
Negative heat capacity in a left-handed system
NASA Astrophysics Data System (ADS)
Palma-Chilla, L.; Flores, J. C.
2017-04-01
This paper models a left-handed system by finite inductively interacting elements. To separate the internal energy a generic double spectral parametrization is proposed. The microcanonical formalism analytically allows to derive the entropy, temperature and heat capacity in each energy set. Particularly, the heat capacity was found to be negative at high energies. These analytical findings are supported through numerical results. Interestingly, numerically the heat capacity of the system seems to decline when increasing internal energy in both sets.
Thermodynamics, inequalities, and negative heat capacities
NASA Astrophysics Data System (ADS)
Landsberg, P. T.; Pearić, J. E.
1987-05-01
The relation between thermodynamics and inequalities between means, studied earlier, is extended. If heat capacities Ci are allowed to be negative, as they are in the case of a black hole, it is shown that the weighted arithmetic and geometric means have the following relationships: pT1+qT2>=Tp1Tq2 if p and q have like signs; pT1+qT2<=Tp1Tq2 if p and q have unlike signs. Here p≡C1/(C1+C2) and q≡C2/(C1+C2) so that the weights still add up to unity. This result is shown to be readily accessible from thermodynamics. Similarly, if constant-energy and constant-entropy equilibrations of two bodies lead to final temperatures TE and TS, respectively, then it is shown that TS
High-temperature heat capacity of orthovanadates Ce1- x Bi x VO4
NASA Astrophysics Data System (ADS)
Denisova, L. T.; Chumilina, L. G.; Belousova, N. V.; Denisov, V. M.
2016-09-01
Orthovanadates Ce1- x Bi x VO4 (1 ≥ x ≥ 0) have been produced by solid-phase synthesis from initial oxides CeO2, Bi2O3, and V2O5 upon step-by-step burning. The high-temperature heat capacity of Ce1- x Bi x VO4 has been measured by differential scanning calorimetry. The experimental data on C p = f(T) were used to calculate the thermodynamic properties (the enthalpy changes, the entropy changes, and the Gibbs energy).
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.
NASA Astrophysics Data System (ADS)
Kashtanov, E. A.; Uryash, V. F.; Kokurina, N. Yu.; Larina, V. N.
2014-02-01
The heat capacity of crab chitin and chitosan is measured in a vacuum adiabatic calorimeter at 10-330 K. The thermodynamic characteristics (enthalpy, entropy, and Gibbs function) are calculated at T → 0 K to 330 K. Differential thermal analysis is used to calculate the relaxation transitions and thermal degradation of chitin and chitosan at 80-600 K. Acid hydrolysis is performed and its effect on the physicochemical properties and thermodynamic functions of chitin and chitosan is studied.
Rozners, Eriks; Pilch, Daniel S; Egli, Martin
2015-12-01
This unit describes the application of calorimetry to characterize the thermodynamics of nucleic acids, specifically, the two major calorimetric methodologies that are currently employed: differential scanning (DSC) and isothermal titration calorimetry (ITC). DSC is used to study thermally induced order-disorder transitions in nucleic acids. A DSC instrument measures, as a function of temperature (T), the excess heat capacity (C(p)(ex)) of a nucleic acid solution relative to the same amount of buffer solution. From a single curve of C(p)(ex) versus T, one can derive the following information: the transition enthalpy (ΔH), entropy (ΔS), free energy (ΔG), and heat capacity (ΔCp); the state of the transition (two-state versus multistate); and the average size of the molecule that melts as a single thermodynamic entity (e.g., the duplex). ITC is used to study the hybridization of nucleic acid molecules at constant temperature. In an ITC experiment, small aliquots of a titrant nucleic acid solution (strand 1) are added to an analyte nucleic acid solution (strand 2), and the released heat is monitored. ITC yields the stoichiometry of the association reaction (n), the enthalpy of association (ΔH), the equilibrium association constant (K), and thus the free energy of association (ΔG). Once ΔH and ΔG are known, ΔS can also be derived. Repetition of the ITC experiment at a number of different temperatures yields the ΔCp for the association reaction from the temperature dependence of ΔH.
The heat capacity of a natural monticellite and phase equilibria in the system CaO-MgO-SiO2-CO2
Sharp, Z.D.; Essene, E.J.; Anovitz, Lawrence M.; Metz, G.W.; Westrum, E.F.; 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.
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.
Device for Measuring Heat Capacities of Microcalorimeter Absorber Materials
NASA Astrophysics Data System (ADS)
Kotsubo, Vincent; Beall, James; Ullom, Joel
2009-12-01
We are developing a device for measuring the heat capacity of candidate absorber materials for gamma-ray microcalorimeters with the goal of finding materials with low heat capacity and high stopping power to improve detector efficiency. To date, only Sn has been effective as an absorber, and speculation is that other materials suffer from anomalously high heat capacities at low temperatures. The key component of the measurement device is a 17 mm×17 mm low heat capacity silicon platform suspended by Kevlar fibers designed for accepting 1 g to 2 g samples, and whose heat capacity can be characterized prior to attaching a sample. The platform has a thin film Pd/Au heater deposited directly on the silicon, and a semiconducting thermometer bonded to the surface. The heat capacity is determined from C = Gτ, where G is the in-situ measured conductance and x is the measured temperature decay time from a step change in applied heat. For a platform without samples, decay periods on the order of 0.3 to 0.05 seconds were measured. With samples, decay periods of several seconds are projected, allowing good resolution of the heat capacities. Several thermometers were tested in an effort to find one with the optimum characteristics for measuring platform temperatures. These included a commercial thick-film Ruthenium-oxide surface-mount resistor, a germanium NTD, and a zirconium oxy-nitride thin-film thermometer.
The temperature dependence of the heat capacity change for micellization of nonionic surfactants.
Kresheck, Gordon C
2006-06-01
The thermodynamic parameters that govern micelle formation by four different nonionic surfactants were investigated by ITC and DSC. These included n-dodecyldimethylphosphine oxide (APO12), Triton X-100 (TX-100), n-octyltetraoxyethylene (C8E4), and N,N-dimethyloctylamine-N-oxide (DAO8). All of these surfactants had been previously investigated by solution calorimetry over smaller temperature ranges with conflicting conclusions as to the temperature dependence of the heat capacity change, DeltaCp, for the process. The temperature coefficient of the heat capacity change, B (cal/mol K2), was derived from the enthalpy data that were obtained at small intervals over a broad temperature range. The values obtained for each of the surfactants at 298.2 K for DeltaCp and B were -155+/-2 and 0.50+/-0.36 (APO12), -97+/-3 and -0.24+/-0.18 (TX-100), -105+/-2 and 1.0+/-0.3 (C8E4), and -82+/-1 and 0.36+/-0.04 (DAO8), cal/mol K and cal/mol K2, respectively. The resulting B-values did not correlate with the cmc, aggregation number, or structure of the monomer in an obvious way, but they were found to reflect the relative changes in hydration of the polar and nonpolar portions of the surfactant molecule as the micelles are formed. An analysis of the data obtained from DSC scans was used to describe the temperature dependence of the critical micelle concentration, cmc. An abrupt increase in heat capacity was observed for TX-100 and C8E4 solutions of 36.5+/-0.5 and 21+/-5 cal/mol K, respectively, as the temperature of the scan passed through the cloud point. This change in heat capacity may reflect the increased monomer concentration of the solutions that accompanies phase separation, although other interpretations of this jump are possible.
On heat capacity of nanoclusters with a shell structure
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.
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.
Low Temperature Heat Capacity of a Severely Deformed Metallic Glass
NASA Astrophysics Data System (ADS)
Bünz, Jonas; Brink, Tobias; Tsuchiya, Koichi; Meng, Fanqiang; Wilde, Gerhard; Albe, Karsten
2014-04-01
The low temperature heat capacity of amorphous materials reveals a low-frequency enhancement (boson peak) of the vibrational density of states, as compared with the Debye law. By measuring the low-temperature heat capacity of a Zr-based bulk metallic glass relative to a crystalline reference state, we show that the heat capacity of the glass is strongly enhanced after severe plastic deformation by high-pressure torsion, while subsequent thermal annealing at elevated temperatures leads to a significant reduction. The detailed analysis of corresponding molecular dynamics simulations of an amorphous Zr-Cu glass shows that the change in heat capacity is primarily due to enhanced low-frequency modes within the shear band region.
Heat capacity and thermal expansion of water and helium
NASA Astrophysics Data System (ADS)
Putintsev, N. M.; Putintsev, D. N.
2017-04-01
Original expressions for heat capacity CV and its components, vibrational and configurational components of thermal expansion coefficient were established. The values of CV, Cvib, Cconf, αvib and αconf for water and helium 4He were calculated.
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.
Determination of HEat Capacity of Yucca Mountain Strtigraphic Layers
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
Low temperature heat capacity of phononic crystal membranes
NASA Astrophysics Data System (ADS)
Puurtinen, T. A.; Maasilta, I. J.
2016-12-01
Phononic crystal (PnC) membranes are a promising solution to improve sensitivity of bolometric sensor devices operating at low temperatures. Previous work has concentrated only on tuning thermal conductance, but significant changes to the heat capacity are also expected due to the modification of the phonon modes. Here, we calculate the area-specific heat capacity for thin (37.5 - 300 nm) silicon and silicon nitride PnC membranes with cylindrical hole patterns of varying period, in the temperature range 1 - 350 mK. We compare the results to two- and three-dimensional Debye models, as the 3D Debye model is known to give an accurate estimate for the low-temperature heat capacity of a bulk sample. We found that thin PnC membranes do not obey the 3D Debye T3 law, nor the 2D T2 law, but have a weaker, approximately linear temperature dependence in the low temperature limit. We also found that depending on the design, the PnC patterning can either enhance or reduce the heat capacity compared to an unpatterned membrane of the same thickness. At temperatures below ˜ 100 mK, reducing the membrane thickness unintuitively increases the heat capacity for all samples studied. These observations can have significance when designing calorimetric detectors, as heat capacity is a critical parameter for the speed and sensitivity of a device.
NASA Astrophysics Data System (ADS)
Bulat, L. P.; Pshenay-Severin, D. A.; Ivanov, A. A.; Osvenskii, V. B.; Parkhomenko, Yu. N.
2016-10-01
Copper selenide is a promising thermoelectric material. One of the reasons for its high efficiency is its low thermal conductivity that can be connected with the decrease of heat capacity with temperature. The possibility of the decrease of heat capacity with the increase of temperature in this material can be connected with the liquid-like behavior of copper ions. In order to reveal the influence of this factor, measurements of constant pressure heat capacity c p and calculations of constant volume heat capacity c V were performed for cubic β-Cu2Se at temperatures T = 450-1000 K. Both calculations and measurements made in the present work demonstrate only a small decrease of heat capacity with temperature. The temperature dependence of c p reasonably correlates with the literature data. But, c V values showed a similar trend only up to 770 K; at higher temperatures, the values obtained previously by other authors are considerably smaller. As the diffusion of copper atoms was taken into account in our calculations, the comparison suggests that small c V values obtained at T > 770 K previously are connected mainly with large thermal expansion of Cu2Se in this temperature range.
'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.
Magee, J. W.
1991-01-01
Molar heat capacities at constant volume (Cv,) for nitrogen have been measured with an automated adiabatic calorimeter. The temperatures ranged from 65 to 300 K, while pressures were as high as 35 MPa. Calorimetric data were obtained for a total of 276 state conditions on 14 isochores. Extensive results which were obtained in the saturated liquid region (Cv(2) and Cσ) demonstrate the internal consistency of the Cv (ρ,T) data and also show satisfactory agreement with published heat capacity data. The overall uncertainty of the Cv values ranges from 2% in the vapor to 0.5% in the liquid. PMID:28184144
Differential scanning calorimetry (DSC) of semicrystalline polymers.
Schick, C
2009-11-01
Differential scanning calorimetry (DSC) is an effective analytical tool to characterize the physical properties of a polymer. DSC enables determination of melting, crystallization, and mesomorphic transition temperatures, and the corresponding enthalpy and entropy changes, and characterization of glass transition and other effects that show either changes in heat capacity or a latent heat. Calorimetry takes a special place among other methods. In addition to its simplicity and universality, the energy characteristics (heat capacity C(P) and its integral over temperature T--enthalpy H), measured via calorimetry, have a clear physical meaning even though sometimes interpretation may be difficult. With introduction of differential scanning calorimeters (DSC) in the early 1960s calorimetry became a standard tool in polymer science. The advantage of DSC compared with other calorimetric techniques lies in the broad dynamic range regarding heating and cooling rates, including isothermal and temperature-modulated operation. Today 12 orders of magnitude in scanning rate can be covered by combining different types of DSCs. Rates as low as 1 microK s(-1) are possible and at the other extreme heating and cooling at 1 MK s(-1) and higher is possible. The broad dynamic range is especially of interest for semicrystalline polymers because they are commonly far from equilibrium and phase transitions are strongly time (rate) dependent. Nevertheless, there are still several unsolved problems regarding calorimetry of polymers. I try to address a few of these, for example determination of baseline heat capacity, which is related to the problem of crystallinity determination by DSC, or the occurrence of multiple melting peaks. Possible solutions by using advanced calorimetric techniques, for example fast scanning and high frequency AC (temperature-modulated) calorimetry are discussed.
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.
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.
Soltani, Z; Ziaie, F; Ghaffari, M; Beigzadeh, A M
2017-02-01
In the present work, thermal properties of low density polyethylene (LDPE) and its nano composites are investigated. For this purpose LDPE reinforced with different weight percents of hydroxyapatite (HAP) powder which was synthesized via hydrolysis method are produced. The samples were irradiated with 10MeV electron beam at doses of 75 to 250kGy. Specific heat capacity measurement have been carried out at different temperatures, i.e. 25, 50, 75 and 100°C using modulated temperature differential scanning calorimetry (MTDSC) apparatus and the effect of three parameters include of temperature, irradiation dose and the amount of HAP nano particles as additives on the specific heat capacity of PE/HAP have been investigated precisely. The MTDSC results indicate that the specific heat capacity have decreased by addition of nano sized HAP as reinforcement for LDPE. On the other hand, the effect of radiation dose is reduction in the specific heat capacity in all materials including LDPE and its nano composites. The HAP nano particles along with cross-link junctions due to radiation restrain the movement of the polymer chains in the vicinity of each particle and improve the immobility of polymer chains and consequently lead to reduction in specific heat capacity. Also, the obtained results confirm that the radiation effect on the specific heat capacity is more efficient than the reinforcing effect of nano-sized hydroxyapatite.
Vibrational dynamics and heat capacity of polyglycine I.
Porwal, Vikas; Misra, Radha Mohan; Tandon, Poonam; Gupta, Vishwambhar Dayal
2004-02-01
Earlier works on polyglycine I suffer from several infirmities, such as the dynamic methylene group being replaced by a mass unit and the use of poorly resolved inelastic neutron spectra, which have resulted in wrong assignments and imprecise profile of dispersion curves. In addition, the density-of-states and heat capacity variation as a function of temperature are being reported for the first time. The heat capacity is in good agreement with the measurements reported earlier by Roles and Wunderlich within a certain range (230-350 K). Deviations set in beyond this could be due to the presence of two crystalline states (I and II) in the sample used for the heat capacity measurements.
Testing of a scanning adiabatic calorimeter with Joule effect heating of the sample
NASA Astrophysics Data System (ADS)
Barreiro-Rodríguez, G.; Yáñez-Limón, J. M.; Contreras-Servin, C. A.; Herrera-Gomez, A.
2008-01-01
We evaluated a scanning adiabatic resistive calorimeter (SARC) developed to measure the specific enthalpy of viscous and gel-type materials. The sample is heated employing the Joule effect. The cell is constituted by a cylindrical jacket and two pistons, and the sample is contained inside the jacket between the two pistons. The upper piston can slide to allow for thermal expansion and to keep the pressure constant. The pistons also function as electrodes for the sample. While the sample is heated through the Joule effect, the electrodes and the jacket are independently heated to the same temperature of the sample using automatic control. This minimizes the heat transport between the sample and its surroundings. The energy to the sample is supplied by applying to the electrodes an ac voltage in the kilohertz range, establishing a current in the sample and inducing electric dissipation. This energy can be measured with enough exactitude to determine the heat capacity. This apparatus also allows for the quantification of the thermal conductivity by reproducing the evolution of the temperature as heat is introduced only to one of the pistons. To this end, the system was modeled using finite element calculations. This dual capability proved to be very valuable for correction in the determination of the specific enthalpy. The performance of the SARC was evaluated by comparing the heat capacity results to those obtained by differential scanning calorimetry measurements using a commercial apparatus. The analyzed samples were zeolite, bauxite, hematite, bentonite, rice flour, corn flour, and potato starch.
Testing of a scanning adiabatic calorimeter with Joule effect heating of the sample.
Barreiro-Rodríguez, G; Yáñez-Limón, J M; Contreras-Servin, C A; Herrera-Gomez, A
2008-01-01
We evaluated a scanning adiabatic resistive calorimeter (SARC) developed to measure the specific enthalpy of viscous and gel-type materials. The sample is heated employing the Joule effect. The cell is constituted by a cylindrical jacket and two pistons, and the sample is contained inside the jacket between the two pistons. The upper piston can slide to allow for thermal expansion and to keep the pressure constant. The pistons also function as electrodes for the sample. While the sample is heated through the Joule effect, the electrodes and the jacket are independently heated to the same temperature of the sample using automatic control. This minimizes the heat transport between the sample and its surroundings. The energy to the sample is supplied by applying to the electrodes an ac voltage in the kilohertz range, establishing a current in the sample and inducing electric dissipation. This energy can be measured with enough exactitude to determine the heat capacity. This apparatus also allows for the quantification of the thermal conductivity by reproducing the evolution of the temperature as heat is introduced only to one of the pistons. To this end, the system was modeled using finite element calculations. This dual capability proved to be very valuable for correction in the determination of the specific enthalpy. The performance of the SARC was evaluated by comparing the heat capacity results to those obtained by differential scanning calorimetry measurements using a commercial apparatus. The analyzed samples were zeolite, bauxite, hematite, bentonite, rice flour, corn flour, and potato starch.
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.
NASA Astrophysics Data System (ADS)
Gupta, Ankit; Kavakbasi, Bengü Tas; Dutta, Biswanath; Grabowski, Blazej; Peterlechner, Martin; Hickel, Tilmann; Divinski, Sergiy V.; Wilde, Gerhard; Neugebauer, Jörg
2017-03-01
We explore the competition and coupling of vibrational and electronic contributions to the heat capacity of Al and Al3Sc at temperatures below 50 K, combining experimental calorimetry with highly converged finite-temperature density functional theory calculations. We find that semilocal exchange-correlation functionals accurately describe the rich feature set observed for these temperatures, including electron-phonon coupling. Using different representations of the heat capacity, we are therefore able to identify and explain deviations from the Debye behavior in the low-temperature limit and in the temperature regime 30-50 K as well as the reduction of these features due to the addition of Sc.
On the heat capacity of Ce{sub 3}Al
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.
Phase Diagram and Heat Capacities of the Malonic Acid/Water System
NASA Astrophysics Data System (ADS)
Hansen, A.; Beyer, K. D.
2003-12-01
Malonic acid is one of the more ubiquitous dicarboxylic acids found in the atmosphere and is quite soluble in water. Therefore, its impact on particle/cloud droplet formation needs to be better understood through the study of the thermodynamics of its aqueous solutions. The liquid/solid phase diagram and solution heat capacities of the malonic acid/water binary system have been investigated using differential scanning calorimetry and infrared spectroscopy of thin films. We report here the first measurement of the ice melting envelope as well as the ice/malonic acid eutectic temperature and composition in this binary system. Evidence from both thermal analysis and infrared spectroscopy is shown for a malonic acid hydrate, possibly C3H4O4ṡ6H2O. We have observed the formation of this hydrate over a large range of concentrations, and have found it is a major fraction of samples within that region. We have also determined the enthalpy of fusion of malonic acid as well as the constant pressure heat capacities of solutions in the concentration range 5 - 55 wt% malonic acid from 323 K to the freezing point of each solution.
Heat capacities of lanthanide and actinide monazite-type ceramics
NASA Astrophysics Data System (ADS)
Kowalski, Piotr M.; Beridze, George; Vinograd, Victor L.; Bosbach, Dirk
2015-09-01
(Ln, An)xPO4 monazite-type ceramics are considered as potential matrices for the disposal of nuclear waste. In this study we computed the heat capacities and the standard entropies of these compounds using density functional perturbation theory. The calculations of lanthanide monazites agree well with the existing experimental data and provide information on the variation of the standard heat capacities and entropies along the lanthanide series. The results for AnPO4 monazites are similar to those obtained for the isoelectronic lanthanide compounds. This suggests that the missing thermodynamic data on actinide monazites could be similarly computed or assessed based on the properties of their lanthanide analogs. However, the computed heat capacity of PuPO4 appear to be significantly lower than the measured data. We argue that this discrepancy might indicate potential problems with the existing experimental data or with their interpretation. This shows a need for further experimental studies of the heat capacities of actinide-bearing, monazite-type ceramics.
Heat capacity changes in carbohydrates and protein-carbohydrate complexes.
Chavelas, Eneas A; García-Hernández, Enrique
2009-05-13
Carbohydrates are crucial for living cells, playing myriads of functional roles that range from being structural or energy-storage devices to molecular labels that, through non-covalent interaction with proteins, impart exquisite selectivity in processes such as molecular trafficking and cellular recognition. The molecular bases that govern the recognition between carbohydrates and proteins have not been fully understood yet. In the present study, we have obtained a surface-area-based model for the formation heat capacity of protein-carbohydrate complexes, which includes separate terms for the contributions of the two molecular types. The carbohydrate model, which was calibrated using carbohydrate dissolution data, indicates that the heat capacity contribution of a given group surface depends on its position in the saccharide molecule, a picture that is consistent with previous experimental and theoretical studies showing that the high abundance of hydroxy groups in carbohydrates yields particular solvation properties. This model was used to estimate the carbohydrate's contribution in the formation of a protein-carbohydrate complex, which in turn was used to obtain the heat capacity change associated with the protein's binding site. The model is able to account for protein-carbohydrate complexes that cannot be explained using a previous model that only considered the overall contribution of polar and apolar groups, while allowing a more detailed dissection of the elementary contributions that give rise to the formation heat capacity effects of these adducts.
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…
Heat capacity measurements for cryolite (Na3AlF6) and reactions in the system NaFeAlSiOF
Anovitz, Lawrence M.; Hemingway, B.S.; Westrum, E.F.; Metz, G.W.; Essene, E.J.
1987-01-01
The heat capacity of cryolite (Na3AlF6) has been measured from 7 to 1000 K by low-temperature adiabatic and high-temperature differential scanning calorimetry. Low-temperature data were obtained on material from the same hand specimen in the calorimetric laboratories of the University of Michigan and U.S. Geological Survey. The results obtained are in good agreement, and yield average values for the entropy of cryolite of: S0298 = 238.5 J/mol KS0T-S0298 = 145.114 ln T+ 193.009*10-3T- 10.366* 105 T2- 872.89 J/mol K (273-836.5 K)??STrans = 9.9J/mol KS0T-S0298 =198.414 ln T+73.203* 10-3T-63.814* 105 T2-1113.11 J/mol K (836.5-1153 K) with the transition temperature between ??- and ??-cryolite taken at 836.5 K. These data have been combined with data in the literature to calculate phase equilibria for the system NaFeAlSiOF. The resultant phase diagrams allow constraints to be placed on the fO2, fF2, aSiO2 and T conditions of formation for assemblages in alkalic rocks. A sample application suggests that log fO2 is approximately -19.2, log fF2 is -31.9 to -33.2, and aSiO2 is -1.06 at assumed P T conditions of 1000 K, 1 bar for the villiaumite-bearing Ilimaussaq intrusion in southwestern Greenland. ?? 1987.
Calorimetry Studies of Ammonia, Nitric Acid, and Ammonium Nitrate
1979-10-01
block nmmber) Calorimetry Heat of reaction Ammonium nitrate Heat capacity Nitric acid Heat of solution • Amonia 20. ABSTRACT r(Cmrtfe m,.re a N "no•a.•r sd...identical to the literature spectrum of W NO3. Anhydrous nitric acid was prepared by distillation of 90% HNO 3 from fuming sulfuric acid (oxides of nitrogen
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).
Mairhofer, Jonas; Sadus, Richard J
2013-10-21
Molecular dynamics simulations are reported for the thermodynamic properties of n-m Lennard-Jones fluids, where n = 10 and 12, and m = 5 and 6. Results are reported for the thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient, and speed of sound at supercritical conditions covering a wide range of fluid densities. The thermodynamic criteria for maxima∕minima in the isochoric and isobaric heat capacities are identified and the simulation results are also compared with calculations from Lennard-Jones equations of state. The Johnson et al. [Mol. Phys. 78, 591 (1993)] equation of state can be used to reproduce all heat capacity phenomena reported [T. M. Yigzawe and R. J. Sadus, J. Chem. Phys. 138, 194502 (2013)] from molecular dynamics simulations for the 12-6 Lennard-Jones potential. Significantly, these calculations and molecular dynamics results for other n-m Lennard-Jones potentials support the existence of Cp minima at supercritical conditions. The values of n and m also have a significant influence on many other thermodynamic properties.
Commercial Apparatus for Measuring the Heat Capacity of Small Samples from 1.9 K to 350 K
NASA Astrophysics Data System (ADS)
Black, R. C.; Diederichs, J.; Spagna, S.; Simmonds, M. B.
1998-03-01
We have developed a commercial apparatus which measures the heat capacity of small samples (1 mg to 500 mg) from 1.9 K to 350 K with a nominal accuracy of 2 percent. A high precision, nano-Watt thermometer bridge is integrated onto a custom signal processor board and allows us to cover the entire temperature range using a single thermometer sensor. The raw data from the hybrid adiabatic/relaxation measurement is automatically analyzed using a dual time-constant model to account for thermal gradients between the sample and the sample holder. The full time-dependent temperature response of the calorimeter is fit to the solution of the model using a non-linear least-squares technique. In addition to providing extensive error detection capabilities, this scheme makes it possible to extract accurate sample heat capacity numbers in cases where it is not possible or practical to achieve perfect thermal contact between the sample and holder. A Quantum Design Physical Property Measurement System (PPMS) provides the temperature and magnetic field control, as well as the high vacuum required for thermally isolating the sample holder. We present details of the apparatus as well as heat capacity measurements on a variety of samples. We also discuss work on measuring powder samples, as well as extending the lowest useable temperature below 1 K.
NASA Astrophysics Data System (ADS)
Mairhofer, Jonas; Sadus, Richard J.
2013-10-01
Molecular dynamics simulations are reported for the thermodynamic properties of n-m Lennard-Jones fluids, where n = 10 and 12, and m = 5 and 6. Results are reported for the thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient, and speed of sound at supercritical conditions covering a wide range of fluid densities. The thermodynamic criteria for maxima/minima in the isochoric and isobaric heat capacities are identified and the simulation results are also compared with calculations from Lennard-Jones equations of state. The Johnson et al. [Mol. Phys. 78, 591 (1993)] equation of state can be used to reproduce all heat capacity phenomena reported [T. M. Yigzawe and R. J. Sadus, J. Chem. Phys. 138, 194502 (2013)] from molecular dynamics simulations for the 12-6 Lennard-Jones potential. Significantly, these calculations and molecular dynamics results for other n-m Lennard-Jones potentials support the existence of Cp minima at supercritical conditions. The values of n and m also have a significant influence on many other thermodynamic properties.
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.
Angle-resolved heat capacity of heavy fermion superconductors.
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.
Poly(3-methylpyrrole): vibrational dynamics, phonon dispersion and heat capacity.
Ali, Parvej; Srivastava, Seema; Ansari, Saif-ul-Islam; Gupta, V D
2013-07-01
Normal modes of vibration and their dispersions in poly(3-methylpyrrole) (P3MPy) based on the Urey-Bradley force field are reported. It provides a detailed interpretation of previously reported I.R. spectra. Characteristic features of dispersion curves, such as regions of high density-of-states, repulsion, and character mixing of dispersive modes are discussed. Predictive values of heat capacity as a function of temperature are calculated from dispersion curves via density-of-states.
Hybrid heat capacity-moving slab solid-state laser
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.
Poly(3-methylpyrrole): Vibrational dynamics, phonon dispersion and heat capacity
NASA Astrophysics Data System (ADS)
Ali, Parvej; Srivastava, Seema; Ansari, Saif-ul-Islam; Gupta, V. D.
2013-07-01
Normal modes of vibration and their dispersions in poly(3-methylpyrrole) (P3MPy) based on the Urey-Bradley force field are reported. It provides a detailed interpretation of previously reported I.R. spectra. Characteristic features of dispersion curves, such as regions of high density-of-states, repulsion, and character mixing of dispersive modes are discussed. Predictive values of heat capacity as a function of temperature are calculated from dispersion curves via density-of-states.
Heat capacity contributions to the formation of inclusion complexes.
Olvera, Angeles; Pérez-Casas, Silvia; Costas, Miguel
2007-10-04
An analysis scheme for the formation of the inclusion complexes in water is presented. It is exemplified for the case where the host is alpha-cyclodextrin and the guest is a linear alcohol (1-propanol to 1-octanol) or the isomers of 1-pentanol. Eight transfer isobaric heat capacities, DeltatCp, involving different initial and final states are evaluated at infinite dilution of the guest using both data determined in this work and from the literature. Apart from the usual definition for the inclusion heat capacity change, three inclusion transfers are used. The sign of each DeltatCp indicates if the transfer is an order-formation or an order-destruction process. From the DeltatCp data, the main contributions to the heat capacity of cyclodextrin complexation, namely, those due to dehydration of the hydrophobic section of the guest molecule, H-bond formation, formation of hydrophobic interactions, and release of water molecules from the cyclodextrin cavity, are estimated. The relative weight of each of these contributions to the DeltatCp values is discussed, providing a better characterization of the molecular recognition process involved in the inclusion phenomena.
On the Electron Gas Heat Capacity in Undergraduate Solid State
NASA Astrophysics Data System (ADS)
Hasbun, Javier
2013-03-01
In undergraduate solid state physics the electronic energy, Uel, is calculated through the Fermi distribution function while the energy is weighted with the density of states. The electronic heat capacity is the derivative of the electronic energy with respect to temperature. Through this process, it is possible to obtain a low temperature approximation for the heat capacity, Cel that's proportional to the temperature. It is of interest to do a numerical calculation of Uel from which the numerical Cel is extracted. However, the result obtained, while agreeing with the low temperature approximation, has a slope that's substantially different. The disagreement appears large as the temperature is increased from zero K. Here we show that the reason has to do with the constancy of the Fermi level. By including the self consistent behavior of the chemical potential, the deviation from zero Kelvin is much improved and the result seems to make better sense. The lesson learned is significant enough to be of great pedagogical importance as regards the heat capacity calculation and the behavior of the chemical potential with temperature.
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.
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.
NASA Astrophysics Data System (ADS)
Johari, G. P.
1997-12-01
Calculations for the Gibbs-Thomson effect and the intergranular melting of the ice droplets in (water) emulsions at temperatures below 273.16 K show that water and ice coexist at thermodynamic equilibrium in an apparently frozen emulsion. The fraction of water at this equilibrium increases on heating, which alters further the thermodynamic properties of the emulsion. As some of the ice in the emulsion has already melted, the increase in the enthalpy, H, and heat capacity, Cp, and the decrease in the volume measured on the normal melting at 273.16 K, are less than the values anticipated. The ratio of this increase in H, or Cp, on melting of the emulsion to the corresponding value for pure ice, underestimates the emulsion's water content which, when used for scaling the difference between the Cp of the unfrozen and frozen emulsion at lower temperatures, as in earlier studies, leads to a larger Cp of supercooled water than the actual value. Similar scaling of the corresponding difference between the volume leads to higher volume, or lower density, than the actual value. A formalism for this premelting effect is given for both the adiabatic and differential scanning calorimetry (DSC), and its magnitude is calculated. New experiments show that the rise in the DSC signal, or equivalently in the apparent Cp observed on heating the frozen emulsion, occurs over a temperature range much wider than the Gibbs-Thomson effect and intergranular melting predict, for which reasons are given. It is shown that Cp of the dispersant phase is also affected by the melting of ice droplets. There are four consequences of the premelting effects for all finely dispersed materials, for frozen water emulsions below 273.16 K: (i) water and ice coexist in the emulsion, (ii) its apparent Cp will increase with increase in the heat input used to measure it, (iii) the apparent Cp will increase with decrease in the average size of the droplets, and (iv) the apparent Cp will decrease on annealing the
NASA Technical Reports Server (NTRS)
Stahle, Caroline Kilbourne; McCammon, Dan; Irwin, Kent D.
1999-01-01
Your opponent's serve was almost perfect, but you vigorously returned it beyond his outstretched racquet to win the point. Now the tennis ball sits wedged in the chain-link fence around the court. What happened to the ball's kinetic energy? It has gone to heat the fence, of course, and you realize that if the fence were quite colder, you might be able to measure that heat and determine just how energetic your swing really was. Calorimetry has been a standard measurement technique since James Joule and Julius von Mayer independently concluded, about 150 years ago, that heat is a form of energy. But only in the past 15 years or so has calorimetry been applied, at millikelvin temperatures, to the measurement of the energy of individual photons and particles with exquisite sensitivity. In this article, we have tried to show that continuing research in low-temperature physics leads to a greater understanding of high-temperature astrophysics. Adaptations of the resulting spectrometers will be useful tool for fields of research beyond astrophysics.
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)
Firestone, Ross S; Cameron, Scott A; Karp, Jerome M; Arcus, Vickery L; Schramm, Vern L
2017-02-17
Human 5'-methylthioadenosine phosphorylase (MTAP) catalyzes the phosphorolysis of 5'-methylthioadenosine (MTA). Its action regulates cellular MTA and links polyamine synthesis to S-adenosylmethionine (AdoMet) salvage. Transition state analogues with picomolar dissociation constants bind to MTAP in an entropically driven process at physiological temperatures, suggesting increased hydrophobic character or dynamic structure for the complexes. Inhibitor binding exhibits a negative heat capacity change (-ΔCp), and thus the changes in enthalpy and entropy upon binding are strongly temperature-dependent. The ΔCp of inhibitor binding by isothermal titration calorimetry does not follow conventional trends and is contrary to that expected from the hydrophobic effect. Thus, ligands of increasing hydrophobicity bind with increasing values of ΔCp. Crystal structures of MTAP complexed to transition-state analogues MT-DADMe-ImmA, BT-DADMe-ImmA, PrT-ImmA, and a substrate analogue, MT-tubercidin, reveal similar active site contacts and overall protein structural parameters, despite large differences in ΔCp for binding. In addition, ΔCp values are not correlated with Kd values. Temperature dependence of presteady state kinetics revealed the chemical step for the MTAP reaction to have a negative heat capacity for transition state formation (-ΔCp(‡)). A comparison of the ΔCp(‡) for MTAP presteady state chemistry and ΔCp for inhibitor binding revealed those transition-state analogues most structurally and thermodynamically similar to the transition state. Molecular dynamics simulations of MTAP apoenzyme and complexes with MT-DADMe-ImmA and MT-tubercidin show small, but increased dynamic motion in the inhibited complexes. Variable temperature CD spectroscopy studies for MTAP-inhibitor complexes indicate remarkable protein thermal stability (to Tm = 99 °C) in complexes with transition-state analogues.
Cell asymmetry correction for temperature modulated differential scanning calorimetry
Ishikiriyama, K.; Wunderlich, B. |
1996-12-31
The quality of measurement of heat capacity by differential scanning calorimetry (DSC) is based on strict symmetry of the twin calorimeter, which is important for temperature-modulated DSC. Heat capacities for sapphire-filled and empty aluminium calorimeters (pans) under designed cell imbalance caused by different pan-masses were measured. In addition, positive and negative signs of asymmetry were explored by analyzing the phase-shift between temperature and heat flow for sapphire and empty runs. The phase shifts change by more than 18{degree} depending on asymmetry sign. Once the asymmetry sign is determined, the asymmetry correction for modulated DSC can be made.
Determination of the heat capacities of Lithium/BCX (bromide chloride in thionyl chloride) batteries
NASA Astrophysics Data System (ADS)
Kubow, Stephen A.; Takeuchi, Kenneth J.; Takeuchi, Esther S.
1989-12-01
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.
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.
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.
Magnetic Contribution to heat capacity and entropy of nickel ferrite
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.
On the specific heat capacity enhancement in nanofluids.
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.
Nakamoto, T; Tan, Z C; Sorai, M
2001-07-16
Heat capacities of the spin crossover complex [Fe(2-pic)3]Cl(2)*MeOH (2-pic: 2-picolylamine or 2-aminomethylpyridine) were measured with an adiabatic calorimeter between 12 and 355 K. A broad heat capacity peak, starting from approximately 80 K, culminating at approximately 150 K, and terminating at approximately 250 K, was observed. The temperature range of the heat capacity anomaly corresponds to that where the low-spin and high-spin states coexist in the 57Fe Mössbauer spectra. The enthalpy and entropy changes arising from the heat capacity anomaly were 8.88 kJ x mol(-1) and 59.5 J x K(-1) x mol(-1), respectively. The entropy gain was much larger than the contribution expected from the change in the spin-manifold R ln 5 (13.4 J x K(-1) x mol(-1)) where R is the gas constant. The remaining entropy gain is attributed to the contribution from the change in the internal vibrations. On the basis of the domain model, the number of molecules per domain was found to be very close to unity, implying a very weak cooperativity in the spin crossover occurring in the solid state of this complex.
Heat Capacity Changes Associated with DNA Duplex Formation: Salt- and Sequence-Dependent Effects†
Mikulecky, Peter J.; Feig, Andrew L.
2008-01-01
Duplexes are the most fundamental elements of nucleic acid folding. Although it has become increasingly clear that duplex formation can be associated with a significant change in heat capacity (ΔCp), this parameter is typically overlooked in thermodynamic studies of nucleic acid folding. Analogy to protein folding suggests that base stacking events coupled to duplex formation should give rise to a ΔCp due to the release of waters solvating aromatic surfaces of nucleotide bases. In previous work, we showed that the ΔCp observed by isothermal titration calorimetry (ITC) for RNA duplex formation depended on salt and sequence. In the present work, we apply calorimetric and spectroscopic techniques to a series of designed DNA duplexes to demonstrate that both the salt dependence and sequence dependence of ΔCps observed by ITC reflect perturbations to the same fundamental phenomenon: stacking in the single-stranded state. By measuring the thermodynamics of single strand melting, one can accurately predict the ΔCps observed for duplex formation by ITC at high and low ionic strength. We discuss our results in light of the larger issue of contributions to ΔCp from coupled equilibria and conclude that observed ΔCps can be useful indicators of intermediate states in nucleic acid folding phenomena. PMID:16401089
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
Low-temperature heat capacity of magnetic fluids
NASA Astrophysics Data System (ADS)
Lebedev, A. V.
2008-12-01
This paper continues the previous investigation into a recently discovered phenomenon of magnetic fluid solidification at temperatures essentially exceeding the freezing point of the base fluid. Physically, this phenomenon is related to the fact that at decreasing temperatures the magnetic fluid loses fluidity (with its viscosity tending to infinity) at a temperature higher than the freezing point of the base fluid. The main factor determining the freezing point is the type of the surface-active substance covering the particles. A group of different surfactants is examined with the aim of finding the lowest possible solidification temperature. The best result is obtained for linoleic acid (-100°C). In order to gain a deeper insight into the mechanisms of fluid solidification, a series of thermophysical measurements has been done. Heat capacity measurements made for an isooctane-based magnetic fluid stabilized by oleic acid at a temperature ranging from -130°C to 0 did not reveal any noticeable heat capacity anomalies in the vicinity of the solidification temperature. This suggests that the solidification of the magnetic fluid proceeds without phase transition. The highest peak of the heat flux is observed at the freezing point of isooctane. The position of the maximum slightly changes with the concentration of magnetic particles. With an increase of the concentration the temperature of the heat flux maximum decreases. In the presence of free oleic acid in isooctane a low peak is observed at a temperature of about -15°C. The peak position is independent of the oleic acid concentration. Tables 1, Figs 7, Refs 1.
Magnetocaloric effect in Mn2-pyrazole-[Nb(CN)8] molecular magnet by relaxation calorimetry
NASA Astrophysics Data System (ADS)
Pełka, R.; Gajewski, M.; Miyazaki, Y.; Yamashita, S.; Nakazawa, Y.; Fitta, M.; Pinkowicz, D.; Sieklucka, B.
2016-12-01
Magnetocaloric effect in {[Mn(pyrazole)4]2[Nb(CN)8]·4 H2O}n molecular magnet is reported. It crystallizes in tetragonal I41/a space group. The compound exhibits a phase transition to a long range magnetically ordered state at TN ≈ 22.8 K. Temperature dependences of the magnetic entropy change ΔSM as well as the adiabatic temperature change ΔTad due to applied field change μ0 ΔH in the range of 0.1-9 T have been inferred from the relaxation calorimetry measurements. A systematic approximate approach has been used to determine the lattice contribution to the heat capacity. The maximum value of ΔSM for μ0 ΔH = 5 T is 6.83 J mol-1 K-1 (6.65 J kg-1 K-1) at 24.3 K. The corresponding maximum value of ΔTad is 1.4 K at 23.8 K. The temperature dependence of the exponent n characterizing the field dependence of ΔSM has been estimated. It attains the value of 0.64 at the transition temperature, which is consistent with the 3D Heisenberg universality class. A hitherto unobserved two-peak structure has been revealed in the temperature dependence of ΔTad.
NASA Astrophysics Data System (ADS)
Kasenov, B. K.; Turtubaeva, M. O.; Amerkhanova, Sh. K.; Nikolov, R. N.; Kasenova, Sh. B.; Sagintaeva, Zh. I.
2017-02-01
Temperature dependences of the heat capacity of cobalt manganites NdM2 I CoMnO5 (MI = Li, Na, and K) are studied by means of dynamic calorimetry in the range of 298.15-673 K. It is found that λ-shaped effects are observed on the C p ° f ( T) curve of cobalt manganites, due probably to second order phase transitions. Based on the experimental data, equations for the temperature dependences of the heat capacity of cobalt manganite are derived with allowance for the temperatures of phase transitions. The values of thermodynamic functions H°( T)- H°(298.15), S°( T), and Vxx( T) are calculated.
Robie, R.A.; Haselton, H.T.; 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.
Heat capacity for systems with excited-state quantum phase transitions
NASA Astrophysics Data System (ADS)
Cejnar, Pavel; Stránský, Pavel
2017-03-01
Heat capacities of model systems with finite numbers of effective degrees of freedom are evaluated using canonical and microcanonical thermodynamics. Discrepancies between both approaches, which are observed even in the infinite-size limit, are particularly large in systems that exhibit an excited-state quantum phase transition. The corresponding irregularity of the spectrum generates a singularity in the microcanonical heat capacity and affects smoothly the canonical heat capacity.
Heat Capacity Setup for Superconducting Bolometer Absorbers below 400 mK
NASA Astrophysics Data System (ADS)
Singh, V.; Mathimalar, S.; Dokania, N.; Nanal, V.; Pillay, R. G.; Ramakrishnan, S.
2014-05-01
A calorimeter set up with very low heat capacity (20 nJ/K at 100 mK) has been designed using commercial Carbon based resistors. This calorimeter is used to determine the heat capacity of small samples of superconducting bolometer absorbers. In particular, we present heat capacity studies of Tin, a bolometer candidate for Neutrinoless Double Beta Decay in Sn, in the temperature range of 60-400 mK.
Decoding heat capacity features from the energy landscape
NASA Astrophysics Data System (ADS)
Wales, David J.
2017-03-01
A general scheme is derived to connect transitions in configuration space with features in the heat capacity. A formulation in terms of occupation probabilities for local minima that define the potential energy landscape provides a quantitative description of how contributions arise from competition between different states. The theory does not rely on a structural interpretation for the local minima, so it is equally applicable to molecular energy landscapes and the landscapes defined by abstract functions. Applications are presented for low-temperature solid-solid transitions in atomic clusters, which involve just a few local minima with different morphologies, and for cluster melting, which is driven by the landscape entropy associated with the more numerous high-energy minima. Analyzing these features in terms of the balance between states with increasing and decreasing occupation probabilities provides a direct interpretation of the underlying transitions. This approach enables us to identify a qualitatively different transition that is caused by a single local minimum associated with an exceptionally large catchment volume in configuration space for a machine learning landscape.
Spin density wave (SDW) transition in Ru doped BaFeAs2 investigated by AC steady state calorimetry
NASA Astrophysics Data System (ADS)
Vinod, K.; Sharma, Shilpam; Sundar, C. S.; Bharathi, A.
2015-06-01
Heat capacity measurements were done on sub-micron sized BaFe2-xRuxAs2 single crystals using thin film membrane based the AC steady state calorimetry technique. Noticeable thermal hysteresis is observed in the heat capacity of the BaFe2-xRuxAs2 during cooling and warming cycles, indicating first order nature of the SDW transition.
Vinod, K. Sharma, Shilpam; Sundar, C. S.; Bharathi, A.
2015-06-24
Heat capacity measurements were done on sub-micron sized BaFe{sub 2−x}Ru{sub x}As{sub 2} single crystals using thin film membrane based the AC steady state calorimetry technique. Noticeable thermal hysteresis is observed in the heat capacity of the BaFe{sub 2−x}Ru{sub x}As{sub 2} during cooling and warming cycles, indicating first order nature of the SDW transition.
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.
NASA Astrophysics Data System (ADS)
Lüddecke, T. O.; Magee, J. W.
1996-07-01
Molar heat capacities at constant volume ( C v) of dill uoromethane (R32) and pentalluoroethane (R125) were measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of a high purity, verified by chemical analysis of each fluid. For the samples, calorimetric results were obtained for two-phase ( C {v/(2)}), saturated liquid ( C σ or C' x ), and singlephase ( C v) molar heat capacities. The C σ data were used to estimate vapor pressures for values less than 0.3 MPa by applying a thermodynamic relationship between the saturated liquid heat capacity and the temperature derivatives of the vapor pressure. The triple-point temperature ( T tr) and the enthalpy of fusion (Δfus H) were also measured for each substance. The principal sources of uncertainty are the temperature rise measurement and the change-ofvolume work adjustment. The expanded uncertainty (at the two-sigma level) for C v is estimated to be 0.7%, for C {v/(2)} it is 0.5%, and for C σ it is 0.7%.
Heat capacity of yttrium aluminum garnet, Y{sub 3}Al{sub 5}O{sub 12}, in the range 350-610 K
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.
NASA Astrophysics Data System (ADS)
Kitajima, Hiroshi; Kagawa, Noboru; Tsuruno, Seizo; Endo, Harumi; W. Magee, Joseph
Specific heat capacity at constant volume is one of the most important thermodynamic properties to develop and evaluate thermodynamic equations of state. With this viewpoint, isochoric heat capacities of ethanol-water mixtures have beenmeasured with a twin-cell type adiabatic calorimeter developed at the National Defense Academy. Temperatures were measured with a platinum resistance thermometer on the bottom of each cell and were reported on the ITS-90. Sample pressure measurements were made with a quartz crystal transducer. Densities were calculated from the volume of the calorimeter cell and sample mass. The experimental expanded uncertainty (with a coverage factor k=2)of temperature measurements is ±13mK, and that of pressure measurement is ±8kPa. The expanded relative uncertainty for isochoric heat capacity is estimated to be ±2% for liquid phase measurements, and for density it is ±0.16%. The present measurements for {xC2H5OH + (l-x)H2O} with x=(0.104, 0.253, 0.498 and 0.755), were obtained at temperatures from 280 to 420 K and at pressures up to 30 MPa.
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.
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.
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.
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).
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.
Prediction of heat capacities of solid inorganic salts from group contributions
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.
The heat capacity of solid antimony telluride Sb2Te3
NASA Astrophysics Data System (ADS)
Pashinkin, A. S.; Malkova, A. S.; Mikhailova, M. S.
2008-05-01
The literature data on the heat capacity of solid antimony telluride over the range 53 895 K were analyzed. The heat capacity of Sb2Te3 was measured over the range 350 700 K on a DSM-2M calorimeter. The equation for the temperature dependence was suggested. The thermodynamic functions of Sb2Te3 were calculated over the range 298.15 700 K.
Calorimetry of matrix-isolated sodium nitrite NaNO2
NASA Astrophysics Data System (ADS)
Egorov, V. M.; Markov, Yu. F.; Roginskii, E. M.; Stukova, E. V.
2016-11-01
Differential scanning calorimetry has been used to carry out a high-precision study of sodium nitrite NaNO2 incorporated into different silicate nanoporous matrices. Heat-capacity maxima due to smeared ferroelectric phase transitions have been discovered. Characteristics (intensity, half-width, phase-transition temperature, etc.) of the maxima have been investigated. Heat-capacity maxima related to an incommensurable phase transition have been reliably identified. The maxima can be attributed to the formation of appropriate orientation of sodium-nitrite nanocrystals in matrix pores.
NASA Astrophysics Data System (ADS)
Bakaeva, Z.; Igamberdiev, K.; Khabibulaev, P.; Stepanek, P.; Cernoch, P.
This work reports the results of a study of the microstructural and dynamical properties of self-assembled triblock copolymers. It was performed using adiabatic calorimetry, ultrasonic spectroscopy and dynamic light scattering. In the vicinity of supramolecular transitions, first aggregates occur; with further increasing temperature a spontaneous forming of compact structures was observed in the system. These results are supported by data of the shear viscosity and free internal volume parameters calculated in the framework of the Frenkel-Andrade approach.
Ambient heat capacities and entropies of ionic solids: a unique view using the Debye equation.
Glasser, Leslie
2013-06-03
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.
Highly precise experimental device for determining the heat capacity of liquids under pressure
Gonzalez-Salgado, D.; Valencia, J. L.; Troncoso, J.; Carballo, E.; Peleteiro, J.; Romani, L.; Bessieres, D.
2007-05-15
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.
Specific Heat Capacity of Physically Confined Ethylene glycol in Nano Pores
NASA Astrophysics Data System (ADS)
Amanuel, Samuel; Linthicum, Will
2013-03-01
Sensible heat is a cheap and effective means of storing solar energy where energy storage density can be improved by enhancing the specific heat capacity of the heat transfer materials. Formulating composite materials of heat transfer fluids is a mechanism by which the bulk specific heat capacity can be altered and preferably increased. Traditionally, the specific heat capacity of composite material is evaluated from the weighed average of the individual specific heat capacities of the constituents. This, however, does not take into account the effect of interfacial atoms and molecules. The effect of interfacial atoms and molecules becomes increasingly significant when one of the constituents has dimensions in nano meters. In this study, we evaluate the role of interfacial molecules on the specific heat capacity of composite systems. In order to systematically control the interfacial molecules, we have measured the specific heat capacity of ethylene glycol when it is physically confined in nano pores. This work has been supported financially by Union College Faculty Research Fund, NSF-EEC 0939322 and New York State NASA space grant for financial support.
Calculation of heat capacities of light and heavy water by path-integral molecular dynamics
NASA Astrophysics Data System (ADS)
Shiga, Motoyuki; Shinoda, Wataru
2005-10-01
As an application of atomistic simulation methods to heat capacities, path-integral molecular dynamics has been used to calculate the constant-volume heat capacities of light and heavy water in the gas, liquid, and solid phases. While the classical simulation based on conventional molecular dynamics has estimated the heat capacities too high, the quantum simulation based on path-integral molecular dynamics has given reasonable results based on the simple point-charge/flexible potential model. The calculated heat capacities (divided by the Boltzmann constant) in the quantum simulation are 3.1 in the vapor H2O at 300 K, 6.9 in the liquid H2O at 300 K, and 4.1 in the ice IhH2O at 250 K, respectively, which are comparable to the experimental data of 3.04, 8.9, and 4.1, respectively. The quantum simulation also reproduces the isotope effect. The heat capacity in the liquid D2O has been calculated to be 10% higher than that of H2O, while it is 13% higher in the experiment. The results demonstrate that the path-integral simulation is a promising approach to quantitatively evaluate the heat capacities for molecular systems, taking account of quantum-mechanical vibrations as well as strongly anharmonic motions.
Dynamic Calorimetry for Students
ERIC Educational Resources Information Center
Kraftmakher, Yaakov
2007-01-01
A student experiment on dynamic calorimetry is described. Dynamic calorimetry is a powerful technique for calorimetric studies, especially at high temperatures and pressures. A low-power incandescent lamp serves as the sample. The ScienceWorkshop data-acquisition system with DataStudio software from PASCO Scientific displays the results of the…
Thermal Properties of Trogamid by Conventional and Fast Scanning Calorimetry
NASA Astrophysics Data System (ADS)
Cebe, Peggy; Merfeld, John; Mao, Bin; Wurm, Andreas; Zhuravlev, Evgeny; Schick, Christoph
We use conventional slow scan rate differential scanning calorimetry, and fast scanning chip-based calorimetry (FSC), to investigate the crystallization and melting behavior of Trogamid, a chemical relative of nylon. Fundamental thermal properties of Trogamid were studied, including the melt crystallization kinetics, heat of fusion, and the solid and liquid state heat capacities. Using slow scan DSC (at 5 K/min), Trogamid displays a glass transition relaxation process at ~133 C, melting endotherm peak at 250 C, and is stable upon repeated heating to 310 C. When using slow scan DSC, the isothermal melt crystallization temperatures were restricted to 225 C or above. Trogamid crystallizes rapidly from the melt and conventional calorimetry is unable to cool sufficiently fast to prevent nucleation and crystal growth prior to stabilization at lower crystallization temperatures. Using FSC we were able to cool nano-gram sizes samples at 2000 K/s to investigate a much lower range of melt crystallization temperatures, from 205-225 C. The experimental protocol for performing FSC on semicrystalline polymers to obtain liquid state heat capacity data will be presented. National Science Foundation, Polymers Program DMR-1206010; DAAD; Tufts Faculty Supported Leave.
NASA Astrophysics Data System (ADS)
Polikhronidi, Nikolai G.; Batyrova, Rabiyat G.; Abdulagatov, Ilmutdin M.; Magee, Joseph W.; Wu, Jiangtao
2016-11-01
New measurements are reported for the isochoric heat capacity of the ionic liquid substance 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C6mim][NTf2]). These measurements extend the ranges of our earlier study (Polikhronidi et al. in Phys Chem Liq 52:657, 2014) by 5 % of the compressed liquid density and by 75 K. An adiabatic calorimeter was used to measure one-phase (C_{V1}) liquid and two-phase (C_{V2}) liquid + vapor isochoric heat capacities, densities (ρ _s), and phase-transition temperatures (T_s) of the ionic liquid (IL) substance. The combined expanded uncertainty of the density ρ and isochoric heat capacity C_V measurements at the 95 % confidence level with a coverage factor of k = 2 is estimated to be 0.15 % and 3 %, respectively. Measurements are concentrated in the immediate vicinity of the liquid + vapor phase-transition curve, in order to closely observe phase transitions. The present measurements and those of our earlier study are analyzed together and are presented in terms of thermodynamic properties (T_s, ρ _s, C_{V1} and C_{V2}) evaluated at saturation and in terms of key-derived thermodynamic properties C_P, C_S, W_S^' }}, K_{TS}^' }}, ( {partial P/partial T} ) V^' }, and ( {partial V/partial T} ) _{P}^' }) on the liquid + vapor phase-transition curve. A thermodynamic relation by Yang and Yang is used to confirm the internal consistency of measured two-phase heat capacities C_{V2} , which are observed to fall perfectly on a line as a function of specific volume at a constant temperature. The observed linear behavior is exploited to evaluate contributions to the quantity C_{V2} = f(V, T) from chemical potential C_{{Vμ}} =-Td^{{2}}μ /dT2 and from vapor pressure C_{VP} =VTd2PS /dT2. The physical nature and specific details of the temperature and specific volume dependence of the two-phase isochoric heat capacity and some features of the other derived thermodynamic properties of IL at liquid saturation curve are considered
Optimizing Adiabaticity in NMR
NASA Astrophysics Data System (ADS)
Vandermause, Jonathan; Ramanathan, Chandrasekhar
We demonstrate the utility of Berry's superadiabatic formalism for numerically finding control sequences that implement quasi-adiabatic unitary transformations. Using an iterative interaction picture, we design a shortcut to adiabaticity that reduces the time required to perform an adiabatic inversion pulse in liquid state NMR. We also show that it is possible to extend our scheme to two or more qubits to find adiabatic quantum transformations that are allowed by the control algebra, and demonstrate a two-qubit entangling operation in liquid state NMR. We examine the pulse lengths at which the fidelity of these adiabatic transitions break down and compare with the quantum speed limit.
AC heat capacities of κ-(BEDT-TTF)2Cu2(CN)3 measured by microchip calorimeter
NASA Astrophysics Data System (ADS)
Muraoka, Y.; Yamashita, S.; Yamamoto, T.; Nakazawa, Y.
2011-09-01
Thermodynamic measurements of an organic spin liquid compound of κ-(BEDT-TTF)2Cu2(CN)3 where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene were performed by the ac calorimetry technique using a microchip device of TCG3880. This technique is effective to measure relative temperature and magnetic-field dependences of heat capacity for tiny single crystal samples less than 1μg. Broad hump structures in Cp vs T which are known as so-called 6 K anomaly were observed in κ-(BEDT-TTF)2Cu2(CN)3 and its deuterated compound. The hump temperatures are evaluated as 5.7 K in both compounds. This result demonstrates that the TCG3880 is useful for performing thermodynamic investigations of such kind of organic charge transfer complexes with much reduced sample quantity than the conventional techniques and that the existence of hump structure is intrinsic for κ-(BEDT-TTF)2Cu2(CN)3. The in-plane angular dependence of the magnetic field of 7 T applied parallel to the two dimensional layer is also studied and absence of in-plane anisotropy of the hump structure is discussed in both pristine and deuterated compounds.
A heat capacity model of T(3/2) dependence for quantum dots.
Roslee, Amirul Edham; Muzakir, Saifful Kamaluddin; Ismail, Jamil; Yusoff, Mashitah M; Jose, Rajan
2016-12-21
This article addresses the heat capacity of quantum dots (QDs) using density functional theory (DFT). By analyzing the evolution of phonon density of states and heat capacity as CdSe clusters grow from a molecular cluster into larger quantum confined solids, we have shown that their heat capacity does not fit very well with the Debye T(3) model. We observed that the number of phonon modes, which is discrete, increases as the particles grow, and the dispersion relation shows a quadratic behavior in contrast to the bulk solids whose dispersion relation is linear and equal to the sound velocity. The phonon density of states showed a square root variation with respect to frequency whereas that of the bulk is a quadratic variation of frequency. From the observed variation in the phonon density of states and holding the fact that the atomic vibrations in solids are elastically coupled, we have re-derived the expression for total energy of the QDs and arrive at a T(3/2) model of heat capacity, which fits very well to the observed heat capacity data. These results give promising directions in the understanding of the evolution of the thermophysical properties of solids.
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.
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.
Origin of the low temperature excess heat capacity of isotopically substituted acetylsalicylic acid
NASA Astrophysics Data System (ADS)
Schröder, F.; Winkler, B.; Bauer, J. D.; Haussühl, E.; Rivera Escoto, B.; Tristan López, F.; Avalos Borja, M.; Richter, C.; Ferner, J.
2011-09-01
The low temperature heat capacities of single crystals of fully protonated acetylsalicylic acid, measured between 2 K < T < 80 K, have been compared to samples in which the methyl-group was replaced by CD3, CH2D and 13CH3. For the partially methyl-deuterated crystal (CH2D) a significant excess heat capacity was found below T < 40 K with a broad maximum around T ≈ 14 K. The thermodynamic data are explained on the basis of a Schottky model using results obtained in earlier NMR and neutron spectroscopic experiments. In contrast, the excess heat capacity of the fully deuterated compound can be explained by a change of the phonon density of states.
High energy bursts from a solid state laser operated in the heat capacity limited regime
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.
High energy bursts from a solid state laser operated in the heat capacity limited regime
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.
The Magnetocaloric Effect and Heat Capacity of Suspensions of High-Dispersity Samarium Ferrite
NASA Astrophysics Data System (ADS)
Korolev, V. V.; Aref'ev, I. M.; Ramazanova, A. G.
2008-02-01
The magnetocaloric effect and specific heat capacity of an aqueous suspension of samarium ferrite were determined calorimetrically over the temperature range 288-343 K in magnetic fields of 0-0.7 T. The data obtained were used to calculate changes in the magnetic component of the molar heat capacity and entropy of the magnetic phase and changes in the enthalpy of the process under an applied magnetic field. The magnetocaloric effect was found to increase nonlinearly as the magnetic field induction grew. The corresponding temperature dependences contained a maximum at 313 K related to the second-order magnetic phase transition at the Curie point. The field and temperature dependences of heat capacity contained a maximum in fields of 0.4 T and a minimum at the magnetic phase transition temperature.
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.
Debye temperature, thermal expansion, and heat capacity of TcC up to 100 GPa
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.
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.
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.
NASA Astrophysics Data System (ADS)
Bodryakov, V. Yu.; Bykov, A. A.
2016-05-01
The correlation between the volumetric thermal expansion coefficient β( T) and the heat capacity C( T) of aluminum is considered in detail. It is shown that a clear correlation is observed in a significantly wider temperature range, up to the melting temperature of the metal, along with the low-temperature range where it is linear. The significant deviation of dependence β( C) from the low-temperature linear behavior is observed up to the point where the heat capacity achieves the classical Dulong-Petit limit of 3 R ( R is the universal gas constant).
[Low-temperature heat capacity of DNA in various conformation states].
Andronikashvili, E L; Mrevlishvili, G M; Dzhaparidze, G Sh; Sakhadze, V M; Tatishvili, D A
1988-01-01
Experimental results are presented on temperature--dependent DNA heat capacity in three different states: a) intact--native DNA in the conformation of double helix, b) disordered conformation of polynucleotide chains in the state of statistical coils, c) completely "degenerated" polynucleotide chains--mechanical mixture of nucleotides. Data on heat capacity (4-400 K) at different water content in the specimens allow a definition of relative changes in the pattern of the entropy temperature dependence for these conformational states with the account for the structural effect of water.
Advances in temperature derivative control and calorimetry
Hemmerich, J.L.; Loos, J.; Miller, A.; Milverton, P.
1996-11-01
Temperature stabilization by inertial feedback control has proven a powerful tool to create the ultrastable environment essential for high resolution calorimetry. A thermally insulated mass, connected to a base through Seebeck effect sensors (thermopiles) is used as a reference to control the base temperature. The thermopile signal is proportional to both the heat capacity of the reference mass and the derivative {dot {Theta}} of the base temperature {Theta}. Using vacuum insulation and bismuth telluride thermopiles, we designed and tested temperature derivative sensors (TDSs) with sensitivities up to 3300 VsK{sup {minus}1}. Standard industrial controllers with approximately {plus_minus}1 {mu}V input noise and stability, permit control of temperature derivatives to {plus_minus}3{times}10{sup {minus}10} Ks{sup {minus}1}. Single-cup thermoelectric calorimeters coupled to the TDS-controlled base permitted measurement of heat flow from samples in a power range from 3 {mu}W to 10 W with high accuracy ({plus_minus}100 ppm), resolution ({plus_minus}0.2 {mu}W), and reproducibility ({plus_minus}1 {mu}W). The design of two instruments is described in detail. Their performance is demonstrated on a variety of measurements, e.g., the determination of sample heat capacities with temperature ramp rates {dot {Theta}}={plus_minus}5{times}10{sup {minus}6} Ks{sup {minus}1}, the half-life of a 3 g tritium sample in a uranium getter bed, the decay heat of depleted uranium, and the heat evolution of epoxy resin. {copyright} {ital 1996 American Institute of Physics.}
Salt materials testing for a spacecraft adiabatic demagnetization refrigerator
NASA Astrophysics Data System (ADS)
Savage, M. L.; Kittel, P.; Roellig, T.
As part of a technology development effort to qualify adiabatic demagnetization refrigerators for use in a NASA spacecraft, such as the Space Infrared Telescope Facility, a study of low temperature characteristics, heat capacity and resistance to dehydration was conducted for different salt materials. This report includes results of testing with cerrous metaphosphate, several synthetic rubies, and chromic potassium alum (CPA). Preliminary results show that CPA may be suitable for long-term spacecraft use, provided that the salt is property encapsulated. Methods of salt pill construction and testing for all materials are discussed, as well as reliability tests. Also, the temperature regulation scheme and the test cryostat design are briefly discussed.
Salt materials testing for a spacecraft adiabatic demagnetization refrigerator
NASA Technical Reports Server (NTRS)
Savage, M. L.; Kittel, P.; Roellig, T.
1990-01-01
As part of a technology development effort to qualify adiabatic demagnetization refrigerators for use in a NASA spacecraft, such as the Space Infrared Telescope Facility, a study of low temperature characteristics, heat capacity and resistance to dehydration was conducted for different salt materials. This report includes results of testing with cerrous metaphosphate, several synthetic rubies, and chromic potassium alum (CPA). Preliminary results show that CPA may be suitable for long-term spacecraft use, provided that the salt is property encapsulated. Methods of salt pill construction and testing for all materials are discussed, as well as reliability tests. Also, the temperature regulation scheme and the test cryostat design are briefly discussed.
Scintillator plate calorimetry
Price, L.E.
1990-01-01
Calorimetry using scintillator plates or tiles alternated with sheets of (usually heavy) passive absorber has been proven over multiple generations of collider detectors. Recent detectors including UA1, CDF, and ZEUS have shown good results from such calorimeters. The advantages offered by scintillator calorimetry for the SSC environment, in particular, are speed (<10 nsec), excellent energy resolution, low noise, and ease of achieving compensation and hence linearity. On the negative side of the ledger can be placed the historical sensitivity of plastic scintillators to radiation damage, the possibility of nonuniform response because of light attenuation, and the presence of cracks for light collection via wavelength shifting plastic (traditionally in sheet form). This approach to calorimetry is being investigated for SSC use by a collaboration of Ames Laboratory/Iowa State University, Argonne National Laboratory, Bicron Corporation, Florida State University, Louisiana State University, University of Mississippi, Oak Ridge National Laboratory, Virginia Polytechnic Institute and State University, Westinghouse Electric Corporation, and University of Wisconsin.
Anomalies of low-temperature heat capacity in superconductors with twins
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).
Negative thermal expansion and anomalies of heat capacity of LuB50 at low temperatures.
Novikov, V V; Zhemoedov, N A; Matovnikov, A V; Mitroshenkov, N V; Kuznetsov, S V; Bud'ko, S L
2015-09-28
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. Thus, the glasslike character of the behavior of LuB50 thermal characteristics at low temperatures was confirmed.
First-principles calculations of heat capacities of ultrafast laser-excited electrons in metals
NASA Astrophysics Data System (ADS)
Bévillon, E.; Colombier, J. P.; Recoules, V.; Stoian, R.
2015-05-01
Ultrafast laser excitation can induce fast increases of the electronic subsystem temperature. The subsequent electronic evolutions in terms of band structure and energy distribution can determine the change of several thermodynamic properties, including one essential for energy deposition; the electronic heat capacity. Using density functional calculations performed at finite electronic temperatures, the electronic heat capacities dependent on electronic temperatures are obtained for a series of metals, including free electron like, transition and noble metals. The effect of exchange and correlation functionals and the presence of semicore electrons on electronic heat capacities are first evaluated and found to be negligible in most cases. Then, we tested the validity of the free electron approaches, varying the number of free electrons per atom. This shows that only simple metals can be correctly fitted with these approaches. For transition metals, the presence of localized d electrons produces a strong deviation toward high energies of the electronic heat capacities, implying that more energy is needed to thermally excite them, compared to free sp electrons. This is attributed to collective excitation effects strengthened by a change of the electronic screening at high temperature.
Negative thermal expansion and anomalies of heat capacity of LuB50 at low temperatures
Novikov, V. V.; Zhemoedov, N. A.; Matovnikov, A. V.; ...
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
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…
Heat capacity singularity of binary liquid mixtures at the liquid-liquid critical point.
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.
Gordon, H.A.; Grannis, P.D.
1984-01-01
The activities related to calorimetry at Snowmass took place in three main areas. These were: (1) The performance criteria for SSC calorimetry, including the requirements on hermeticity, shower containment, segmentation and time resolution. The use of calorimetric means of particle identification was studied. (2) The study of triggering methods using calorimeter energy, angle and timing information. (3) A review of a wide variety of calorimeter materials for absorber and sampling, as well as several means of obtaining the readout of the energy deposits. 48 references, 10 figures, 1 table.
Analysis of RNA folding and ligand binding by conventional and high-throughput calorimetry.
Sokoloski, Joshua E; Bevilacqua, Philip C
2012-01-01
Noncoding RNAs serve myriad functions in the cell, but their biophysical properties are not well understood. Calorimetry offers direct and label-free means for characterizing the ligand-binding and thermostability properties of these RNA. We apply two main types of calorimetry--isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC)--to the characterization of these functional RNA molecules. ITC can describe ligand binding in terms of stoichiometry, affinity, and heat (enthalpy), while DSC can provide RNA stability in terms of heat capacity, melting temperature, and folding enthalpy. Here, we offer detailed experimental protocols for studying such RNA systems with commercially available conventional and high-throughput ITC and DSC instruments.
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.
Hemingway, B.S.; Evans, H.T.; Nord, G.L.; Haselton, H.T.; 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.
Wunderlich, B.; Okazaki, I.
1997-03-01
Temperature-modulated differential scanning calorimetry, TMDSC, is new technique that permits to measure the apparent heat capacity vs modulation frequency. The method is briefly described and a quasi- isothermal measurement method is used to derive the kinetic parameters for PET and PS. A first-order kinetics expression was used to describe the approach to equilibrium and point out the limits caused by asymmetry and cooperativity of the kinetics. Use of a complex description of heat capacity and entropy is discussed. Activation energies vary from 75 to 350 kJ/mol, dependent on thermal pretreatment and the preexponential factor is correlated with the activation energy.
Scintillator materials for calorimetry
Weber, M.J.
1994-09-01
Requirements for fast, dense scintillator materials for calorimetry in high energy physics and approaches to satisfying these requirements are reviewed with respect to possible hosts and luminescent species. Special attention is given to cerium-activated crystals, core-valence luminescence, and glass scintillators. The present state of the art, limitations, and suggestions for possible new scintillator materials are presented.
Molar heat capacity and molar excess enthalpy measurements in aqueous amine solutions
NASA Astrophysics Data System (ADS)
Poozesh, Saeed
Experimental measurements of molar heat capacity and molar excess enthalpy for 1, 4-dimethyl piperazine (1, 4-DMPZ), 1-(2-hydroxyethyl) piperazine (1, 2-HEPZ), I-methyl piperazine (1-MPZ), 3-morpholinopropyl amine (3-MOPA), and 4-(2-hydroxy ethyl) morpholine (4, 2-HEMO) aqueous solutions were carried out in a C80 heat flow calorimeter over a range of temperatures from (298.15 to 353.15) K and for the entire range of the mole fractions. The estimated uncertainty in the measured values of the molar heat capacity and molar excess enthalpy was found to be +/- 2%. Among the five amines studied, 3-MOPA had the highest values of the molar heat capacity and 1-MPZ the lowest. Values of molar heat capacities of amines were dominated by --CH 2, --N, --OH, --O, --NH2 groups and increased with increasing temperature, and contributions of --NH and --CH 3 groups decreased with increasing temperature for these cyclic amines. Molar excess heat capacities were calculated from the measured molar heat capacities and were correlated as a function of the mole fractions employing the Redlich-Kister equation. The molar excess enthalpy values were also correlated as a function of the mole fractions employing the Redlich-Kister equation. Molar enthalpies at infinite dilution were derived. Molar excess enthalpy values were modeled using the solution theory models: NRTL (Non Random Two Liquid) and UNIQUAC (UNIversal QUAsi Chemical) and the modified UNIFAC (UNIversal quasi chemical Functional group Activity Coefficients - Dortmund). The modified UNIFAC was found to be the most accurate and reliable model for the representation and prediction of the molar excess enthalpy values. Among the five amines, the 1-MPZ + water system exhibited the highest values of molar excess enthalpy on the negative side. This study confirmed the conclusion made by Maham et al. (71) that -CH3 group contributed to higher molar excess enthalpies. The negative excess enthalpies were reduced due to the contribution of
Wireless adiabatic power transfer
Rangelov, A.A.; Suchowski, H.; Silberberg, Y.; Vitanov, N.V.
2011-03-15
Research Highlights: > Efficient and robust mid-range wireless energy transfer between two coils. > The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. > Wireless energy transfer is insensitive to any resonant constraints. > Wireless energy transfer is insensitive to noise in the neighborhood of the coils. - Abstract: We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.
Schliesser, Jacob M; Woodfield, Brian F
2015-07-22
Low-energy vibrational modes that have a gap in the density of states (DOS) have often been observed in heat capacity data in the form of 'boson' peaks, but the functions used to model these modes are often inadequate or are not physically meaningful. We have adapted the Debye model to represent these gapped modes and have derived the heat capacity equations for these modes in one, two, and three dimensions. Applying these equations to the low-temperature heat capacity data fitting for a large variety of materials substantially improves the fit quality relative to conventional fits. From the fitting parameters, the underlying DOS were estimated, which we show to be comparable to those reported in the literature. This model expands the methods of theoretical low-temperature heat capacity data analysis and improves the procedure of approximating a material's DOS from its low-temperature heat capacity.
NASA Astrophysics Data System (ADS)
Dan, Wen-Yan; di, You-Ying; Liu, Yan-Juan; Kong, Yu-Xia; Tan, Zhi-Cheng
2010-12-01
Dichloro bis(2-aminopyridine) zinc (II), ZnCl2(C5H6N2)2(s), was synthesized by the method of solvonthermal synthesis in which 2-aminopyridine and zinc chloride were chosen as the reactants. X-ray crystallography, chemical analysis, and elemental analysis were applied to characterize the structure and composition of the complex. Low-temperature heat capacities of the title compound were measured with a precise small-sample automated adiabatic calorimeter over the temperature range from 78 K to 398 K. A polynomial equation of the heat capacities as a function of temperature was fitted by a least-squares method. Smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature (298.15 K) were calculated and tabulated at intervals of 5 K based on the fitted polynomial. A reasonable thermochemical cycle was designed, and the standard molar enthalpies of dissolution for the reactants and products of the synthesis reaction in a selected solvent were measured by an isoperibol solution-reaction calorimeter. In addition, the enthalpy change of the reaction was calculated from the data of the above standard molar enthalpies of dissolution. Finally, the standard molar enthalpy of formation of the complex ZnCl2(C5H6N2)2(s) was determined to be -(400.52 ± 1.66) kJ · mol-1 in accordance with Hess's law.
Dynamic heat capacity of the east model and of a bead-spring polymer model.
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.
Magnetic susceptibility and heat capacity of graphene in two-band Harrison model
NASA Astrophysics Data System (ADS)
Mousavi, Hamze; Bagheri, Mehran; Khodadadi, Jabbar
2015-11-01
Using a two-band tight-binding Harrison model and Green's function technique, the influences of both localized σ and delocalized π electrons on the density of states, the Pauli paramagnetic susceptibility, and the heat capacity of a graphene sheet are investigated. We witness an extension in the bandwidth and an increase in the number of Van-Hove singularities as well. As a notable point, besides the magnetic nature which includes diamagnetism in graphene-based nanosystems, a paramagnetic behavior associated with the itinerant π electrons could be occurred. Further, we report a Schottky anomaly in the heat capacity. This study asserts that the contribution of both σ and π electrons play dominant roles in the mentioned physical quantities.
Low-Temperature Heat Capacity of 4 He Films on Graphite
NASA Astrophysics Data System (ADS)
Morishita, Masashi
2017-02-01
Heat capacities of 4 He films have been measured at rather low temperatures between 2 and 80 mK and at areal densities between 2 and 24 nm^{-2} . These areal densities correspond to a monolayer fluid and third-layer fluid. For monolayer films, the results do not contradict previous measurements carried out at high temperatures. On the other hand, at some areal densities, small and broad but definite bumps, whose origin has not yet been understood, have been observed around 15 mK. Between 13 and 24 nm^{-2} , the measured heat capacities above 40 mK are proportional to T2 and hardly change with areal density. These behaviors suggest that the second atomic layer does not solidify before the third-layer promotion, at least not into a commensurate solid, such as the so-called 4/7 phase.
Changes in molar volume and heat capacity of actin upon polymerization.
Quirion, F; Gicquaud, C
1993-11-01
We have used densimetry and microcalorimetry to measure the changes in molar volume and heat capacity of the actin molecule during Mg(2+)-induced polymerization. Molar volume is decreased by 720 ml/mol. This result is in contradiction with previous measurements by Ikkai and Ooi [(1966) Science 152, 1756-1757], and by Swezey and Somero [(1985) Biochemistry 24, 852-860]: both of these groups reported increases in actin volume during polymerization, of 391 ml/mol and 63 ml/mol respectively. We also observed a decrease in heat capacity of about 69.5 kJ.K-1.mol-1 during polymerization. This is in agreement with the concept of conformational fluctuation of proteins proposed by Lumry and Gregory [(1989) J.Mol. Liq. 42, 113-144]whereby either ligand binding by a protein or monomer-monomer interaction decreases the protein's conformational flexibility.
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.
Electrostatic contributions to heat capacity changes of DNA-ligand binding.
Gallagher, K; Sharp, K
1998-01-01
Significant heat capacity changes (DeltaCp) often accompany protein unfolding, protein binding, and specific DNA-ligand binding reactions. Such changes are widely used to analyze contributions arising from hydrophobic and polar hydration. Current models relate the magnitude of DeltaCp to the solvent accessible surface area (ASA) of the molecule. However, for many binding systems-particularly those involving non-peptide ligands-these models predict a DeltaCp that is significantly different from the experimentally measured value. Electrostatic interactions provide a potential source of heat capacity changes and do not scale with ASA. Using finite-difference Poisson-Boltzmann methods (FDPB), we have determined the contribution of electrostatics to the DeltaCp associated with binding for DNA binding reactions involving the ligands DAPI, netropsin, lexitropsin, and the lambda repressor binding domain. PMID:9675178
High-temperature heat capacity of Co3O4 spinel: thermally induced spin unpairing transition
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.
Landau-Placzek ratio for heat density dynamics and its application to heat capacity of liquids.
Bryk, Taras; Ruocco, Giancarlo; Scopigno, Tullio
2013-01-21
Exact relation for contributions to heat capacity of liquids is obtained from hydrodynamic theory. It is shown from analysis of the long-wavelength limit of heat density autocorrelation functions that the heat capacity of simple liquids is represented as a sum of two contributions due to "phonon-like" collective excitations and heat relaxation. The ratio of both contributions being the analogy of Landau-Placzek ratio for heat processes depends on the specific heats ratio. The theory of heat density autocorrelation functions in liquids is verified by computer simulations. Molecular dynamics simulations for six liquids having the ratio of specific heats γ in the range 1.1-2.3, were used for evaluation of the heat density autocorrelation functions and predicted Landau-Placzek ratio for heat processes. The dependence of contributions from collective excitations and heat relaxation process to specific heat on γ is shown to be in excellent agreement with the theory.
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.
Melting by temperature-modulated calorimetry
Wunderlich, B.; Okazaki, Iwao; Ishikiriyama, Kazuhiko; Boller, A. |
1997-09-01
Well-crystallized macromolecules melt irreversibly due to the need of molecular nucleation, while small molecules melt reversibly as long as crystal nuclei are present to assist crystallization. Furthermore, imperfect crystals of low-molar-mass polymers may have a sufficiently small region of metastability between crystallization and melting to show a reversing heat-flow component due to melting of poor crystals followed by crystallization of imperfect crystals which have insufficient time to perfect before the modulation switches to heating and melts the imperfect crystals. Many metals, in turn. melt sharply and reversibly as long as nuclei remain after melting for subsequent crystallization during the cooling cycle. Their analysis is complicated, however, due to thermal conductivity limitations of the calorimeters. Polymers of sufficiently high molar mass, finally, show a small amount of reversible. local melting that may be linked to partial melting of individual molecules. Experiments by temperature-modulated calorimetry and model calculations are presented. The samples measured included poly(ethylene terephthalate)s, poly(ethylene oxide)s, and indium. Two unsolved problems that arose from this research involve the origin of a high, seemingly stable, reversible heat capacity of polymers in the melting region, and a smoothing of melting and crystallization into a close-to-elliptical Lissajous figure in a heat-flow versus sample-temperature plot.
The Ideal Gas and Real Gas Heat Capacity of Sodium Atoms
NASA Astrophysics Data System (ADS)
Biolsi, Louis
2014-10-01
The ideal gas heat capacity of sodium atoms in the vapor phase is calculated to high temperatures using statistical mechanics. Since there are, in principle, an infinite number of atomic energy levels, the partition function and the heat capacity will grow very large unless the summation over energy levels is constrained as temperature increases. At higher temperatures, the increasing size of the atoms, which is a consequence of the increased population of highly excited energy levels, is used as a mechanism for limiting the summation over energy levels. The "" and "Bethe" procedures for cutting off the summation over energy levels will be discussed, and the results obtained using the two methods will be compared. In addition, although experimental information is available about lower atomic energy levels and some theoretical calculations are available for excited energy levels, information is lacking for most individual atomic states associated with highly excited energy levels. A "fill" procedure for approximating the energy of the unknown states will be discussed. Sodium vapor will also be considered to be a real gas that obeys the virial equation of state. The first non-ideal term in the power series expansion of the heat capacity in terms of virial coefficients involves the second virial coefficient, . This depends on the interaction potential energy between two sodium atoms, i.e., the potential energy curves for the sodium dimer. Accurate interaction potential energies can be obtained from either experimental or theoretical information for the lowest ten electronic states of the sodium dimer. These are used to calculate for each state, and the averaged value of for all ten states is used to calculate the non-ideal contribution to the heat capacity of sodium atoms as a function of temperature.
Heat capacity and thermal expansion of icosahedral lutetium boride LuB66
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.
Restrictions on linear heat capacities from Joule-Brayton maximum-work cycle efficiency.
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.
Recent developments in silicon calorimetry
Brau, J.E.
1990-11-01
We present a survey of some of the recent calorimeter applications of silicon detectors. The numerous attractive features of silicon detectors are summarized, with an emphasis on those aspects important to calorimetry. Several of the uses of this technology are summarized and referenced. We consider applications for electromagnetic calorimetry, hadronic calorimetry, and proposals for the SSC.
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.
Parallelizable adiabatic gate teleportation
NASA Astrophysics Data System (ADS)
Nakago, Kosuke; Hajdušek, Michal; Nakayama, Shojun; Murao, Mio
2015-12-01
To investigate how a temporally ordered gate sequence can be parallelized in adiabatic implementations of quantum computation, we modify adiabatic gate teleportation, a model of quantum computation proposed by Bacon and Flammia [Phys. Rev. Lett. 103, 120504 (2009), 10.1103/PhysRevLett.103.120504], to a form deterministically simulating parallelized gate teleportation, which is achievable only by postselection. We introduce a twisted Heisenberg-type interaction Hamiltonian, a Heisenberg-type spin interaction where the coordinates of the second qubit are twisted according to a unitary gate. We develop parallelizable adiabatic gate teleportation (PAGT) where a sequence of unitary gates is performed in a single step of the adiabatic process. In PAGT, numeric calculations suggest the necessary time for the adiabatic evolution implementing a sequence of L unitary gates increases at most as O (L5) . However, we show that it has the interesting property that it can map the temporal order of gates to the spatial order of interactions specified by the final Hamiltonian. Using this property, we present a controlled-PAGT scheme to manipulate the order of gates by a control qubit. In the controlled-PAGT scheme, two differently ordered sequential unitary gates F G and G F are coherently performed depending on the state of a control qubit by simultaneously applying the twisted Heisenberg-type interaction Hamiltonians implementing unitary gates F and G . We investigate why the twisted Heisenberg-type interaction Hamiltonian allows PAGT. We show that the twisted Heisenberg-type interaction Hamiltonian has an ability to perform a transposed unitary gate by just modifying the space ordering of the final Hamiltonian implementing a unitary gate in adiabatic gate teleportation. The dynamics generated by the time-reversed Hamiltonian represented by the transposed unitary gate enables deterministic simulation of a postselected event of parallelized gate teleportation in adiabatic
Kresheck, Gordon C
2009-05-14
Isothermal titration calorimetry, ITC, was used to determine the enthalpy and heat capacity changes that accompany micelle formation of decyldimethylphosphine oxide, APO10, from 15-79 degrees C in the presence of representative neutral salts from the Hofmeister series. The solutions investigated were water, 0.2, 0.5, and 1.0 NaCl, 0.5 M NaF, KCl, KI, guanidinium chloride (GuHCl) and mannitol, and 0.333 M Na2SO4. The heat capacity change at 25 degrees C (but not the cmc) and the parameter that describes the temperature dependence of the heat capacity change, B (cal/(mol K2)), appear to be correlated. Calculated values of the ion effects on micelle formation from a recent salt ion partitioning model (SPM) of Pegram and Record [J. Phys. Chem. B 2007, 111, 5411-5417] were quantitatively related to the experimental value of the solute free energy increment (SFEI). Use of this model requires a calculation of the solvent accessible area (ASA), which yields values for the extent of hydration of the micelle interior. An alternate method to determine the ASA based on the heat capacity change for micelle formation at 25 degrees C of APO8-12 yielded values for the number of buried carbon atoms (5-12) versus previous estimates (4-8) from analysis of the B parameter.
Xiao, Kechao; Lee, Dongwoo; Vlassak, Joost J.
2014-10-27
Scanning AC nano-calorimetry is a recently developed experimental technique capable of measuring the heat capacity of thin-film samples of a material over a wide range of temperatures and heating rates. Here, we describe how this technique can be used to study solid-gas phase reactions by measuring the change in heat capacity of a sample during reaction. We apply this approach to evaluate the oxidation kinetics of thin-film samples of zirconium in air. The results confirm parabolic oxidation kinetics with an activation energy of 0.59 ± 0.03 eV. The nano-calorimetry measurements were performed using a device that contains an array of micromachined nano-calorimeter sensors in an architecture designed for combinatorial studies. We demonstrate that the oxidation kinetics can be quantified using a single sample, thus enabling high-throughput mapping of the composition-dependence of the reaction rate.
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.
Quantum adiabatic machine learning
NASA Astrophysics Data System (ADS)
Pudenz, Kristen L.; Lidar, Daniel A.
2013-05-01
We develop an approach to machine learning and anomaly detection via quantum adiabatic evolution. This approach consists of two quantum phases, with some amount of classical preprocessing to set up the quantum problems. In the training phase we identify an optimal set of weak classifiers, to form a single strong classifier. In the testing phase we adiabatically evolve one or more strong classifiers on a superposition of inputs in order to find certain anomalous elements in the classification space. Both the training and testing phases are executed via quantum adiabatic evolution. All quantum processing is strictly limited to two-qubit interactions so as to ensure physical feasibility. We apply and illustrate this approach in detail to the problem of software verification and validation, with a specific example of the learning phase applied to a problem of interest in flight control systems. Beyond this example, the algorithm can be used to attack a broad class of anomaly detection problems.
Thermal Properties of Silk Fibroin Using Fast Scanning Calorimetry
NASA Astrophysics Data System (ADS)
Cebe, Peggy; Partlow, Benjamin; Kaplan, David; Wurm, Andreas; Zhuravlev, Evgeny; Schick, Christoph
We performed fast scanning chip-based calorimetry of silk protein using the Mettler Flash DSC1. We suggest the methodology by which to obtain quantitative information on the very first scan to high temperature, including the melting endotherm of the beta pleated sheets. For proteins, this first scan is the most important one, because the crystalline secondary structural features, the beta pleated sheets, melt after the first heating and cannot be thermally reintroduced. To obtain high quality data, the samples must be treated to drying and enthalpy relaxation sequences. The heat flow rates in heating and cooling must be corrected for asymmetric heat loses. We evaluate methods to obtain an estimate of the sample mass, finally choosing internal calibration using the known heat capacity increment at the glass transition. We report that even heating at rates of 2000 K/s, thermal degradation of silk cannot be totally avoided, though it can be minimized. Using a set of nineteen samples, we successfully determine the liquid state heat capacity of silk as: Cpliquid (T) = (1.98 +0.06) J/gK + T (6.82 +1.4) x10-4 J/gK2. Methods for estimation of the sample mass will be presented and compared. National Science Foundation, Polymers Program DMR-1206010; DAAD; Tufts Faculty Supported Leave.
Adiabatic capture and debunching
Ng, K.Y.; /Fermilab
2012-03-01
In the study of beam preparation for the g-2 experiment, adiabatic debunching and adiabatic capture are revisited. The voltage programs for these adiabbatic processes are derived and their properties discussed. Comparison is made with some other form of adiabatic capture program. The muon g-2 experiment at Fermilab calls for intense proton bunches for the creation of muons. A booster batch of 84 bunches is injected into the Recycler Ring, where it is debunched and captured into 4 intense bunches with the 2.5-MHz rf. The experiment requires short bunches with total width less than 100 ns. The transport line from the Recycler to the muon-production target has a low momentum aperture of {approx} {+-}22 MeV. Thus each of the 4 intense proton bunches required to have an emittance less than {approx} 3.46 eVs. The incoming booster bunches have total emittance {approx} 8.4 eVs, or each one with an emittance {approx} 0.1 eVs. However, there is always emittance increase when the 84 booster bunches are debunched. There will be even larger emittance increase during adiabatic capture into the buckets of the 2.5-MHz rf. In addition, the incoming booster bunches may have emittances larger than 0.1 eVs. In this article, we will concentrate on the analysis of the adiabatic capture process with the intention of preserving the beam emittance as much as possible. At this moment, beam preparation experiment is being performed at the Main Injector. Since the Main Injector and the Recycler Ring have roughly the same lattice properties, we are referring to adiabatic capture in the Main Injector instead in our discussions.
Analytical evaluation of thermal conductance and heat capacities of one-dimensional material systems
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.
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.
The heat capacity and enthalpy of condensed UO 2: Critical review and assessment
NASA Astrophysics Data System (ADS)
Hyland, G. J.; Ohse, R. W.
1986-09-01
Having established the role of the heat capacity, Cp( T), of condensed UO 2 in various FBR accident scenarios, e.g. HCDA and PAHR, and having noted the unsatisfactory state of present knowledge concerning this basic thermophysical property of the fuel, all existing enthalpy and heat capacity data are collated and assessed, and certain recommendations made. The conventional method of obtaining Cp( T) by analytical differentiation of some adopted fit to this enthalpy data is then critically examined. The attendant problems are illustrated both for solid UO 2, where the contribution to Cp( T) from the weak, sigmoidal, enthalpy structure (which is just discernible in the data of Hein and Flagella) is missed and for molten UO 2, where not even the direction of the trend of Cp( T) with T can be definitively established, resulting, upon extrapolation to 5000 K, in Cp values which can differ by as much as 60 J mol -1K -1. Some recent progress towards a more acceptable, "model-independent" approach, known as quasi-local linear regression (QLLR), is then reviewed and applied to enthalpy data of UO 2 on both sides of its melting point, Tm. In the case of solid UO 2, a pronounced heat capacity peak, extending over about 100 K and centred on 2610 K., is revealed, whose magnitude and location is very similar to that found in other fluorite structured materials near 0.8 Tm wherein it indicates a (Bredig) transition to a state characterised by giant ionic conductivities. Whilst it is impossible to establish any definite T-dependence for the Cp(QLLR) values in molten UO 2, the tendency to slightly decrease appears to marginally outweigh the converse, in qualitative accord with the dependence advocated by Hoch and Vernardakis. In the post-transitional region Tt< T< Tm the opposite holds, as is necessary for consistency between the independently established T-dependences of the thermal conductivity and diffusivity, which requires that Cp( T) increases with T faster than the density
High energy bursts from a solid state laser operated in the heat capacity limited regime
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.
Isothermal titration calorimetry of ion-coupled membrane transporters.
Boudker, Olga; Oh, SeCheol
2015-04-01
Binding of ligands, ranging from proteins to ions, to membrane proteins is associated with absorption or release of heat that can be detected by isothermal titration calorimetry (ITC). Such measurements not only provide binding affinities but also afford direct access to thermodynamic parameters of binding--enthalpy, entropy and heat capacity. These parameters can be interpreted in a structural context, allow discrimination between different binding mechanisms and guide drug design. In this review, we introduce advantages and limitations of ITC as a methodology to study molecular interactions of membrane proteins. We further describe case studies where ITC was used to analyze thermodynamic linkage between ions and substrates in ion-coupled transporters. Similar type of linkage analysis will likely be applicable to a wide range of transporters, channels, and receptors.
Bacon, Dave; Flammia, Steven T
2009-09-18
The difficulty in producing precisely timed and controlled quantum gates is a significant source of error in many physical implementations of quantum computers. Here we introduce a simple universal primitive, adiabatic gate teleportation, which is robust to timing errors and many control errors and maintains a constant energy gap throughout the computation above a degenerate ground state space. This construction allows for geometric robustness based upon the control of two independent qubit interactions. Further, our piecewise adiabatic evolution easily relates to the quantum circuit model, enabling the use of standard methods from fault-tolerance theory for establishing thresholds.
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.
Heat capacities of aqueous solutions of sodium hydroxide and water ionization up to 300 °C at 10 MPa
NASA Astrophysics Data System (ADS)
Schrödle, Simon; Königsberger, Erich; May, Peter M.; Hefter, Glenn
2008-07-01
A commercial (Setaram C80) calorimeter has been modified to measure the heat capacities of highly caustic solutions at temperatures up to 300 °C and pressures up to 20 MPa. The improvements have allowed more accurate determination of the isobaric volumetric heat capacities of chemically aggressive liquids at high temperatures. Test measurements with aqueous solutions of sodium chloride showed a reproducibility of about ±0.1%, with an accuracy of ˜0.3% or better, over the whole temperature range. Heat capacities of aqueous solutions of sodium hydroxide at concentrations from 0.5 to 8 mol/kg were measured at temperatures from 50 to 300 °C and a pressure of 10 MPa. Apparent molar isobaric heat capacities of NaOH(aq) were calculated using densities determined previously for the same solutions by vibrating-tube densimetry. Standard state (infinite dilution) partial molar isobaric heat capacities of NaOH(aq) were obtained by extrapolation using an extended Redlich-Meyer equation. Values of the standard heat capacity change for the ionization of water up to 300 °C were derived by combining the present results with the literature data for HCl(aq) and NaCl(aq).
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.
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
Adiabatically implementing quantum gates
Sun, Jie; Lu, Songfeng Liu, Fang
2014-06-14
We show that, through the approach of quantum adiabatic evolution, all of the usual quantum gates can be implemented efficiently, yielding running time of order O(1). This may be considered as a useful alternative to the standard quantum computing approach, which involves quantum gates transforming quantum states during the computing process.
Complex Heat Capacity of Lithium Borate Glasses Studied by Modulated DSC
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.
A room-temperature phase transition in maximum microcline - Heat capacity measurements
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.
Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films
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.
Heat capacity from 12 to 305°K and entropy of talc and tremolite
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.
Magnetic Contribution to Heat Capacity and Entropy of Nicke Ferrite (NiFe2O4)
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.
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.
NASA Astrophysics Data System (ADS)
Arthur, Jonathan W.; Haymet, A. D. J.
1999-03-01
Hydrophobic hydration is studied with an information theory approximation, using the first two moments of the number of solvent centers in a cavity in liquid water, calculated from the density and the pair correlation function. The excess chemical potential, entropy, and heat capacity of solvation are determined for three cases: the two-dimensional MB model of water, in both the (i) NPT and (ii) NVT ensembles, and (iii) the central force CF1 model of water in the NPT ensemble. The results are compared with Monte Carlo simulations and experimental measurements from the literature. The information theory approximation, using only the first two moments, accurately determines the excess chemical potential and entropy of solvation but is unable to predict the excess heat capacity of solvation. Little difference is found between the results obtained using the uniform prior and the ideal gas prior. Molecular dynamics simulations are performed to calculate the excess chemical potential of solvation of soft-spheres as a function of solute size. These results are compared with the solvation of a hard sphere using the information theory approximation and previous molecular dynamics simulations of Lennard-Jones spheres in water. The information theory approximation is found to predict the free energy of solvation as a function of size accurately up to a cavity diameter of approximately 3.5 Å.
Low-temperature heat capacity and localized vibrational modes in natural and synthetic tetrahedrites
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.
NASA Astrophysics Data System (ADS)
Novikov, A. N.; Rassokhina, L. Yu.
2015-12-01
The heat capacity and density of the ternary solutions of NaI-KI- N-methylpyrrolidone (MP), NaI-RbI-MP, KI-RbI-MP, and KI-BaI2-MP at 298.15 K were studied by calorimetry and densimetry. The changes in the heat capacity and volume during the formation of the ternary systems from binary solutions were calculated and discussed. Ion association was found to dominate during the mixing of electrolyte solutions of this type in MP, with ion resolvation occasionally producing a significant effect on ion association.
NASA Astrophysics Data System (ADS)
Giordano, D.; Nichols, A. R. L.; Potuzak, M.; Di Genova, D.; Romano, C.; Russell, J. K.
2015-12-01
The specific heat capacity ( C p) of six variably hydrated ( 3.5 wt% H2O) iron-bearing Etna trachybasaltic glasses and liquids has been measured using differential scanning calorimetry from room temperature across the glass transition region. These data are compared to heat capacity measurements on thirteen melt compositions in the iron-free anorthite (An)-diopside (Di) system over a similar range of H2O contents. These data extend considerably the published C p measurements for hydrous melts and glasses. The results for the Etna trachybasalts show nonlinear variations in, both, the heat capacity of the glass at the onset of the glass transition (i.e., C p g ) and the fully relaxed liquid (i.e., C p l ) with increasing H2O content. Similarly, the "configurational heat capacity" (i.e., C p c = C p l - C p g ) varies nonlinearly with H2O content. The An-Di hydrous compositions investigated show similar trends, with C p values varying as a function of melt composition and H2O content. The results show that values in hydrous C p g , C p l and C p c in the depolymerized glasses and liquids are substantially different from those observed for more polymerized hydrous albitic, leucogranitic, trachytic and phonolitic multicomponent compositions previously investigated. Polymerized melts have lower C p l and C p c and higher C p g with respect to more depolymerized compositions. The covariation between C p values and the degree of polymerization in glasses and melts is well described in terms of SMhydrous and NBO/ T hydrous. Values of C p c increase sharply with increasing depolymerization up to SMhydrous 30-35 mol% (NBO/ T hydrous 0.5) and then stabilize to an almost constant value. The partial molar heat capacity of H2O for both glasses ( C_{{{p}{H}2 {O}}}^{g} ) and liquids ( C_{{{p}{H}2 {O}}}^{l} ) appears to be independent of composition and, assuming ideal mixing, we obtain a value for C_{{{p}{H}2 {O}}}^{l} of 79 J mol-1 K-1. However, we note that a range of values for
Recent advances in eye-safe Er:YAG solid-state heat-capacity technology
NASA Astrophysics Data System (ADS)
Eichhorn, Marc; Bigotta, Stefano; Ibach, Thierry
2012-11-01
In order to address the question of the possibility of a high energy laser with an emission in the "eye-safe" wavelength range, various architectures may be considered. To provide a truly scalable and efficient laser source, however, only bulk solid-state lasers using resonantly diode-pumped erbium show the necessary properties, when coupled with the solid-state heat-capacity (SSHCL) principle of operation. Although seen as nearly being impossible to realize, such a quasi-three-level laser medium can be used in heat-capacity operation. In this operation mode, the laser medium is not cooled during lasing in order to avoid the thermal lensing occurring in bulk lasers, which, in actively cooled operation, would result in a low beam quality, destabilize the laser cavity or would even cause crystal fracture. In heat-capacity mode, the laser medium will substantially heat up during operation, which will cause an increase in re-absorption for a quasi-three-level laser medium, resulting in a general drop in output power over time. However, theoretical and experimental investigations have proven that this effectis of no concern for an Er3+:YAG SSHCL. This paper presents an overview on the theoretical background of the Er3+:YAG SSHCL, experimental results including recent advances in output power and efficiency, an investigation on the laser scaling properties and recent results on intra-cavity adaptive optics for beam-quality enhancement. The effect of fluorescence re-absorption on the laser properties, especially on threshold and laser efficiency will also be discussed. Up to 4.65 kW and 440 J in less than 800 ms are achieved using optimized doping levels for upconversion reduction in this resonantly-diode-pumped Er3+:YAG SSHCL, 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.
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
Differential scanning calorimetry.
Spink, Charles H
2008-01-01
Differential scanning calorimetry (DSC) has emerged as a powerful experimental technique for determining thermodynamic properties of biomacromolecules. The ability to monitor unfolding or phase transitions in proteins, polynucleotides, and lipid assemblies has not only provided data on thermodynamic stability for these important molecules, but also made it possible to examine the details of unfolding processes and to analyze the characteristics of intermediate states involved in the melting of biopolymers. The recent improvements in DSC instrumentation and software have generated new opportunities for the study of the effects of structure and changes in environment on the behavior of proteins, nucleic acids, and lipids. This review presents some of the details of application of DSC to the examination of the unfolding of biomolecules. After a brief introduction to DSC instrumentation used for the study of thermal transitions, the methods for obtaining basic thermodynamic information from the DSC curve are presented. Then, using DNA unfolding as an example, methods for the analysis of the melting transition are presented that allow deconvolution of the DSC curves to determine more subtle characteristics of the intermediate states involved in unfolding. Two types of transitions are presented for analysis, the first example being the unfolding of two large synthetic polynucleotides, which display high cooperativity in the melting process. The second example shows the application of DSC for the study of the unfolding of a simple hairpin oligonucleotide. Details of the data analysis are presented in a simple spreadsheet format.
Semiconductor adiabatic qubits
Carroll, Malcolm S.; Witzel, Wayne; Jacobson, Noah Tobias; Ganti, Anand; Landahl, Andrew J.; Lilly, Michael; Nguyen, Khoi Thi; Bishop, Nathaniel; Carr, Stephen M.; Bussmann, Ezra; Nielsen, Erik; Levy, James Ewers; Blume-Kohout, Robin J.; Rahman, Rajib
2016-12-27
A quantum computing device that includes a plurality of semiconductor adiabatic qubits is described herein. The qubits are programmed with local biases and coupling terms between qubits that represent a problem of interest. The qubits are initialized by way of a tuneable parameter, a local tunnel coupling within each qubit, such that the qubits remain in a ground energy state, and that initial state is represented by the qubits being in a superposition of |0> and |1> states. The parameter is altered over time adiabatically or such that relaxation mechanisms maintain a large fraction of ground state occupation through decreasing the tunnel coupling barrier within each qubit with the appropriate schedule. The final state when tunnel coupling is effectively zero represents the solution state to the problem represented in the |0> and |1> basis, which can be accurately read at each qubit location.
Intracavity adaptive correction of a 10 kW, solid-state, heat-capacity laser.
LaFortune, K N; Hurd, R L; Johansson, E M; Dane, C B; Fochs, S N; Brase, J M
2004-01-12
The Solid-State, Heat-Capacity Laser (SSHCL), under development at Lawrence Livermore National Laboratory 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 it is more challenging than external correction, intracavity correction 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.
Intracavity adaptive correction of a 10 kW, solid-state, heat-capacity laser
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.
Electronic heat capacity and magnetic susceptibility of ferromagnetic silicene sheet under strain
NASA Astrophysics Data System (ADS)
Yarmohammadi, Mohsen
2017-01-01
The electronic heat capacity (EHC) and magnetic susceptibility (MS) of the two-dimensional material ferromagnetic graphene's silicon analog, silicene, are investigated by the strain-induced and the applied electric field within the Green's function technique and the Kane-Mele Hamiltonian. Dirac cone approximation has been performed to investigate the system under strain along the zigzag (ZZ) direction. The main attention is focused on the effects of external static electric field in the presence of strain on EHC and MS of a ferromagnetic silicene sheet. In the presence of strain, carriers have a larger effective mass and transport decreases. As a result, the temperature dependence of EHC and MS gives a critical strain around 10%. Furthermore, electric field breaks the reflection symmetry of the structure and a transition to the topological insulator for strained ferromagnetic silicene has occurred when the electric field is increased. In this phase, EHC and MS have weird behaviors with temperature.
NASA Astrophysics Data System (ADS)
Salian, Umesh A.
1998-04-01
The cumulated distribution of velocity components of atoms of a cluster in a constant energy classical molecular dynamics simulation is found to fit very well with Maxwellian distribution. This enables, with carefully prepared initial configurations, a cluster as small as containing just four atoms to be viewed to constitute a canonical ensemble in itself. In addition, the statistical distribution of velocity components provides an unambiguous, independent and robust method of obtaining the thermodynamic temperature of an isolated system. The temperature thus obtained differs from the conventionally used kinetic temperature by a fixed factor of (3N-6)/(3N), implications of which are discussed. A new procedure of sampling the configurational energy landscape is introduced, and the "heat capacity" curve computed using this method—which is actually the second moment of the potential energy fluctuations as a function of cluster kinetic energy—exhibits its usefulness by clearly demonstrating the two stage melting of Ar55.
Low temperature heat capacity of Fe1-xGax alloys with large magnetostriction
Hill, J.M.; McQueeney, R.J.; Wu, Ruqian; Dennis, K.; McCallum, R.W.; Huang, M.; Lograsso, T.A.
2008-01-22
The low temperature heat capacity C{sub p} of Fe{sub 1-x}Ga{sub x} alloys with large magnetostriction has been investigated. The data were analyzed in the standard way using electron ({gamma}T) and phonon ({beta}T{sup 3}) contributions. The Debye temperature {Theta}{sub D} decreases approximately linearly with increasing Ga concentration, consistent with previous resonant ultrasound measurements and measured phonon dispersion curves. Calculations of {Theta}{sub D} from lattice dynamical models and from measured elastic constants C{sub 11}, C{sub 12}, and C{sub 44} are in agreement with the measured data. The linear coefficient of electronic specific heat {gamma} remains relatively constant as the Ga concentration increases, despite the fact that the magnetoelastic coupling increases. Band structure calculations show that this is due to the compensation of majority and minority spin states at the Fermi level.
Low temperature heat capacity of Fe1-xGax alloys with large mafnetosreiction
Hill, J.; McQueeney, R.; Wu, Ruqian; Dennis, K.; McCallum, R.W.; Huang, M.; Lograsso, T.
2008-01-22
The low temperature heat capacity C{sub p} of Fe{sub 1-x}Ga{sub x} alloys with large magnetostriction has been investigated. The data were analyzed in the standard way using electron ({gamma}T) and phonon ({beta}T{sup 3}) contributions. The Debye temperature {Theta}{sub D} decreases approximately linearly with increasing Ga concentration, consistent with previous resonant ultrasound measurements and measured phonon dispersion curves. Calculations of {Theta}{sub D} from lattice dynamical models and from measured elastic constants C{sub 11}, C{sub 12}, and C{sub 44} are in agreement with the measured data. The linear coefficient of electronic specific heat {gamma} remains relatively constant as the Ga concentration increases, despite the fact that the magnetoelastic coupling increases. Band structure calculations show that this is due to the compensation of majority and minority spin states at the Fermi level.
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.
Evaluating depth to shallow groundwater using Heat Capacity Mapping Mission (HCMM) data
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.
THERMAL-INERTIA MAPPING IN VEGETATED TERRAIN FROM HEAT CAPACITY MAPPING MISSION SATELLITE DATA.
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.
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.
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.
Calorimetry in superfluid He II to measure losses in superconducting magnets
Caspi, S.
1982-04-01
A method using calorimetry to measure magnet losses in pressurized Helium II is described. The isothermal nature of He II is used in measuring the overall heat capacity of the system and the net refrigeration power. During the measurements, the refrigeration power is held fixed, and the system (400 liters) temperature is near 1.92 K. The calorimetric measurement was calibrated against known power inputs between 1 and 20 W. This technique can even measure heat loads higher than the available refrigeration. Results of loss measurement on two dipole magnets are reported.
Costa, Éderson D'M; Lemes, Nelson H T; O Alves, Márcio; Braga, João P
2014-08-01
In this study it is reported the retrieval of the phonon density of states for solid aluminium from the temperature dependent heat capacity, the inverse heat capacity problem. The singularity in this ill posed problem was removed by the Tikhonov approach with the regularization parameter calculated as the L curve maximum curvature. A sensitivity analysis was also coupled to the numerical inversion. For temperatures ranging from 15 K to 300 K the heat capacity results, calculated from the inverted phonon density of states, yields an average error of about 0.3%, within the experimental errors that ranged from 2% to 3%. The predicted entropy, enthalpy and Gibbs free energy are also within experimental errors.
NASA Astrophysics Data System (ADS)
Kasenov, B. K.; Kasenova, Sh. B.; Sagintaeva, Zh. I.; Turtubaeva, M. O.; Kakenov, K. S.; Esenbaeva, G. A.
2017-03-01
The heat capacities of nanosized ferro-chromo-manganites LaM0.5 IIFeCrMnO6.5 (MII-Mg, Ca, Sr, Ba) are measured via dynamic calorimetry in the temperature range of 298.15-673 K using an IT-S-400 instrument. It is established that the C°p f( T) function of LaM0.5 IIFeCrMnO6.5 (MII-Mg, Ca, Sr, Ba) has λ-type effects, due probably to phase transitions of the second order. Considering the temperatures of the phase transitions, equations of the heat capacity of ferro-chromo-manganites LaM0.5 IIFeCrMnO6.5 (MII-Mg, Ca, Sr, Ba) as a function of temperature are derived on the basis of experimental data. Thermodynamic functions H°( T)- H°(298.15), S°( T), and V xx( T) are calculated in the temperature range of 298.15-675 K.
NASA Astrophysics Data System (ADS)
Pickl, Peter; Dürr, Detlef
2008-08-01
We give here a rigorous proof of the well known prediction of pair creation as it arises from the Dirac equation with an external time dependent potential. Pair creation happens with probability one if the potential changes adiabatically in time and becomes overcritical, which means that an eigenvalue curve (as a function of time) bridges the gap between the negative and positive spectral continuum. The potential can be thought of as being zero at large negative and large positive times. The rigorous treatment of this effect has been lacking since the pioneering work of Beck, Steinwedel and Süßmann [1] in 1963 and Gershtein and Zeldovich [8] in 1970.
2012-07-01
PA 19104 1 UNIV OF UTAH DEPT OF MECHL ENGRNG R BRANNON 50 S CTRL CAMPUS DR SALT LAKE CITY UT 84112 1 UNIV OF MARYLAND DEPT OF...CHRISTENSEN DURAND BLDG 496 STANFORD CA 947305-4035 4 UNIV OF UTAH DEPT OF MATH A CHERKAEV E CHERKAEV E S FOLIAS R BRANNON SALT ...B RICE RDRL WML H M FERMEN -COKER D SCHEFFLER S SCHRAML B SCHUSTER RDRL WMM J BEATTY R DOWDING RDRL WMM A M
Hemingway, B.S.; Robie, R.A.; Evans, H.T.; 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
Negative thermal expansion and anomalies of heat capacity of LuB_{50} at low temperatures
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 LuB_{50} 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 LuB_{50} 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 LuB_{50} 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 LuB_{50} were compared to the corresponding values for LuB_{66}, which was studied earlier. Negative thermal expansion at low temperatures was experimentally observed for LuB_{50}. The analysis of the experimental temperature dependence for the Gruneisen parameter of LuB_{50} 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 LuB_{50} thermal characteristics at low temperatures was confirmed.
NASA Astrophysics Data System (ADS)
Zad, Hamid Arian; Movahhedian, Hossein
2016-08-01
Heat capacity of a mixed-three-spin (1/2,1,1/2) antiferromagnetic XXX Heisenberg chain is precisely investigated by use of the partition function of the system for which, spins (1,1/2) have coupling constant J1 and spins (1/2,1/2) have coupling constant J2. We verify tripartite entanglement for the model by means of the convex roof extended negativity (CREN) and concurrence as functions of temperature T, homogeneous magnetic field B and the coupling constants J1 and J2. As shown in our previous work, [H. A. Zad, Chin. Phys. B 25 (2016) 030303.] the temperature, the magnetic field and the coupling constants dependences of the heat capacity for such spin system have different behaviors for the entangled and separable states, hence, we did some useful comparisons between this quantity and negativities of its organized bipartite (sub)systems at entangled and separable states. Here, we compare the heat capacity of the mixed-three-spin (1/2,1,1/2) system with the CREN and the tripartite concurrence (as measures of the tripartite entanglement) at low temperature. Ground state phase transitions, and also, transition from ground state to some excited states are explained in detail for this system at zero temperature. Finally, we investigate the heat capacity behavior around those critical points in which these quantum phase transitions occur.
Analysis of the heat capacity of nanoclusters of FCC metals on the example of Al, Ni, Cu, Pd, and Au
NASA Astrophysics Data System (ADS)
Gafner, Yu. Ya.; Gafner, S. L.; Zamulin, I. S.; Redel, L. V.; Baidyshev, V. S.
2015-06-01
The heat capacity of ideal nickel, copper, gold, aluminum, and palladium fcc clusters with diameter of up to 6 nm has been studied in the temperature range of 150-800 K in terms of the molecular-dynamics theory using a tight-binding potential. The heat capacity of individual metallic nanoclusters has been found to exceed that characteristic of the bulk state, but by no more than 16-20%, even in the case of very small clusters. To explain the discrepancy between the simulated data and the experimental results on the compacted metals, aluminum and palladium samples with 80% theoretical density have also been investigated. Based on the simulation results and analysis of the experimental data, it has been established that the increased heat capacity of the compacted nanomaterials does not depend on the enhanced heat capacity of the individual clusters but rather, can be due to either the disordered state of the nanomaterial or a significant content of impurities (mainly, hydrogen).
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.
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.
Moghaddam, Maria Sabaye; Shimizu, Seishi; Chan, Hue Sun
2005-01-12
Temperature-dependent three-body hydrophobic interactions are investigated by extensive constant-pressure simulations of methane-like nonpolar solutes in TIP4P model water at six temperatures. A multiple-body hydrophobic interaction is considered to be (i) additive, (ii) cooperative, or (iii) anti-cooperative if its potential of mean force (PMF) is (i) equal to, (ii) smaller than, or (iii) larger than the corresponding pairwise sum of two-methane PMFs. We found that three-methane hydrophobic interactions at the desolvation barrier are anti-cooperative at low to intermediate T, and vary from essentially additive to slightly cooperative at high T. Interactions at the contact minimum are slightly anti-cooperative over a wider temperature range. Enthalpy, entropy, and heat capacity are estimated from the computed PMFs. Contrary to the common expectation that burial of solvent-accessible nonpolar surface area always leads to a decrease in heat capacity, the present results show that the change in heat capacity upon three-methane association is significantly positive at the desolvation barrier and slightly positive at the contact minimum. This suggests that the heat capacity signature of a hydrophobic polymer need not vary uniformly nor monotonically with conformational compactness. Ramifications for protein folding are discussed.
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.
Intracavity, adaptive correction of a high-average-power, solid-state, heat-capacity laser
LaFortune, K N; Hurd, R L; Brase, J M; Yamamoto, R M
2005-01-05
The Solid-State, Heat-Capacity Laser (SSHCL) program at Lawrence Livermore National Laboratory is a multigeneration laser development effort scalable to the megawatt power levels. Wavefront quality is a driving metric of its performance. A deformable mirror with over 100 degrees of freedom situated within the cavity is used to correct both the static and dynamic aberrations sensed with a Shack-Hartmann wavefront sensor. The laser geometry is an unstable, confocal resonator with a clear aperture of 10 cm x 10 cm. It operates in a pulsed mode at a high repetition rate (up to 200 Hz) with a correction being applied before each pulse. Wavefront information is gathered in real-time from a low-power pick-off of the high-power beam. It is combined with historical trends of aberration growth to calculate a correction that is both feedback and feed-forward driven. The overall system design, measurement techniques and correction algorithms are discussed. Experimental results are presented.
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.
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.
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.
Hobbs, Joanne K; Jiao, Wanting; Easter, Ashley D; Parker, Emily J; Schipper, Louis A; Arcus, Vickery L
2013-11-15
The increase in enzymatic rates with temperature up to an optimum temperature (Topt) is widely attributed to classical Arrhenius behavior, with the decrease in enzymatic rates above Topt ascribed to protein denaturation and/or aggregation. This account persists despite many investigators noting that denaturation is insufficient to explain the decline in enzymatic rates above Topt. Here we show that it is the change in heat capacity associated with enzyme catalysis (ΔC(‡)p) and its effect on the temperature dependence of ΔG(‡) that determines the temperature dependence of enzyme activity. Through mutagenesis, we demonstrate that the Topt of an enzyme is correlated with ΔC(‡)p and that changes to ΔC(‡)p are sufficient to change Topt without affecting the catalytic rate. Furthermore, using X-ray crystallography and molecular dynamics simulations we reveal the molecular details underpinning these changes in ΔC(‡)p. The influence of ΔC(‡)p on enzymatic rates has implications for the temperature dependence of biological rates from enzymes to ecosystems.
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.
Geometry of the Adiabatic Theorem
ERIC Educational Resources Information Center
Lobo, Augusto Cesar; Ribeiro, Rafael Antunes; Ribeiro, Clyffe de Assis; Dieguez, Pedro Ruas
2012-01-01
We present a simple and pedagogical derivation of the quantum adiabatic theorem for two-level systems (a single qubit) based on geometrical structures of quantum mechanics developed by Anandan and Aharonov, among others. We have chosen to use only the minimum geometric structure needed for the understanding of the adiabatic theorem for this case.…
AB INITIO SIMULATIONS FOR MATERIAL PROPERTIES ALONG THE JUPITER ADIABAT
French, Martin; Becker, Andreas; Lorenzen, Winfried; Nettelmann, Nadine; Bethkenhagen, Mandy; Redmer, Ronald; Wicht, Johannes
2012-09-15
We determine basic thermodynamic and transport properties of hydrogen-helium-water mixtures for the extreme conditions along Jupiter's adiabat via ab initio simulations, which are compiled in an accurate and consistent data set. In particular, we calculate the electrical and thermal conductivity, the shear and longitudinal viscosity, and diffusion coefficients of the nuclei. We present results for associated quantities like the magnetic and thermal diffusivity and the kinematic shear viscosity along an adiabat that is taken from a state-of-the-art interior structure model. Furthermore, the heat capacities, the thermal expansion coefficient, the isothermal compressibility, the Grueneisen parameter, and the speed of sound are calculated. We find that the onset of dissociation and ionization of hydrogen at about 0.9 Jupiter radii marks a region where the material properties change drastically. In the deep interior, where the electrons are degenerate, many of the material properties remain relatively constant. Our ab initio data will serve as a robust foundation for applications that require accurate knowledge of the material properties in Jupiter's interior, e.g., models for the dynamo generation.
CALORIMETRY OF TRU WASTE MATERIALS
C. RUDY; ET AL
2000-08-01
Calorimetry has been used for accountability measurements of nuclear material in the US. Its high accuracy, insensitivity to matrix effects, and measurement traceability to National Institute of Standards and Technology have made it the primary accountability assay technique for plutonium (Pu) and tritium in the Department of Energy complex. A measurement of Pu isotopic composition by gamma-ray spectroscopy is required to transform the calorimeter measurement into grams Pu. The favorable calorimetry attributes allow it to be used for verification measurements, for production of secondary standards, for bias correction of other faster nondestructive (NDA) methods, or to resolve anomalous measurement results. Presented in this paper are (1) a brief overview of calorimeter advantages and disadvantages, (2) a description of projected large volume calorimeters suitable for waste measurements, and (3) a new technique, direct measurement of transuranic TRU waste alpha-decay activity through calorimetry alone.
Contactless Calorimetry for Levitated Samples
NASA Technical Reports Server (NTRS)
Lee, M. C.; Dokko, W.
1986-01-01
Temperature and specific heat of hot sample measured with pyrometer in proposed experimental technique. Technique intended expecially for contactless calorimetry of such materials as undercooled molten alloys, samples of which must be levitated to prevent contamination and premature crystallization. Contactless calorimetry technique enables data to be taken over entire undercooling temperature range with only one sample. Technique proves valuable in study of undercooling because difference in specific heat between undercooled-liquid and crystalline phases at same temperature provides driving force to convert metastable undercooled phase to stable crystalline phase.
NASA Astrophysics Data System (ADS)
Ghahremanpour, Mohammad M.; van Maaren, Paul J.; Ditz, Jonas C.; Lindh, Roland; van der Spoel, David
2016-09-01
Large scale quantum calculations for molar enthalpy of formation (ΔfH0), standard entropy (S0), and heat capacity (CV) are presented. A large data set may help to evaluate quantum thermochemistry tools in order to uncover possible hidden shortcomings and also to find experimental data that might need to be reinvestigated, indeed we list and annotate approximately 200 problematic thermochemistry measurements. Quantum methods systematically underestimate S0 for flexible molecules in the gas phase if only a single (minimum energy) conformation is taken into account. This problem can be tackled in principle by performing thermochemistry calculations for all stable conformations [Zheng et al., Phys. Chem. Chem. Phys. 13, 10885-10907 (2011)], but this is not practical for large molecules. We observe that the deviation of composite quantum thermochemistry recipes from experimental S0 corresponds roughly to the Boltzmann equation (S = RlnΩ), where R is the gas constant and Ω the number of possible conformations. This allows an empirical correction of the calculated entropy for molecules with multiple conformations. With the correction we find an RMSD from experiment of ≈13 J/mol K for 1273 compounds. This paper also provides predictions of ΔfH0, S0, and CV for well over 700 compounds for which no experimental data could be found in the literature. Finally, in order to facilitate the analysis of thermodynamics properties by others we have implemented a new tool obthermo in the OpenBabel program suite [O'Boyle et al., J. Cheminf. 3, 33 (2011)] including a table of reference atomization energy values for popular thermochemistry methods.
Kitt, Jay P; Bryce, David A; Harris, Joel M
2016-07-01
Multidimensional least squares analysis is a well-established technique for resolving component vibrational spectra from mixed samples or systems. Component resolution of temperature-dependent vibrational spectra is challenging, however, due to the lack of a suitable model for the variation in sample composition with temperature. In this work, analysis of temperature-dependent Raman spectra of lipid membranes is accomplished by using "concentration" vectors independently derived from enthalpy changes determined by differential scanning calorimetry. Specifically, the lipid-bilayer phase transitions of DMPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) are investigated through Raman spectra acquired from individual, optically trapped vesicles in suspension as a function of temperature. Heat capacity profiles of the same vesicle suspension are measured using differential scanning calorimetry and numerically integrated to generate enthalpy change curves of each phase transition, which are in turn used to construct composition vectors. Multidimensional least squares analysis optimized for a fit to these composition vectors allows resolution of the component spectra corresponding to gel, ripple, and liquid-crystalline phases of the DMPC. The quality of fit of the calorimetry-derived results is confirmed by unstructured residual differences between the data and the model, and a composition variation predicted by the resolved spectra that matches the calorimetry results. This approach to analysis of temperature-dependent spectral data could be readily applied in other areas of materials characterization, where one is seeking to learn about structural changes that occur through temperature-dependent phase transitions.
The equation of state and heat capacity obtained from this work make it possible to determine the energy and pressure of water from its temperature...and density over a wide range of thermodynamic parameters, with an error of 15-20%. The equation of state and heat capacity also determine, in
NASA Astrophysics Data System (ADS)
Chegel, Raad
2017-04-01
By using the tight binding approximation and Green function method, the electronic structure, density of state, electrical conductivity, heat capacity of BN and BN/graphene bilayers are investigated. The AA-, AB1- and AB2- BN/graphene bilayers have small gap unlike to BN bilayers which are wide band gap semiconductors. Unlike to BN bilayer, the energy gap of graphene/BN bilayers increases with external field. The magnitude of the change in the band gap of BN bilayers is much higher than the graphene/BN bilayers. Near absolute zero, the σ(T) is zero for BN bilayers and it increases with temperature until reaches maximum value then decreases. The BN/graphene bilayers have larger electrical conductivity larger than BN bilayers. For both bilayers, the specific heat capacity has a Schottky anomaly.
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…
NASA Astrophysics Data System (ADS)
Yan, Zijun; Chen, Jincan
1992-07-01
The characteristics of a magnetic Ericsson refrigeration cycle are investigated on the basis of the thermodynamic properties of the ferromagnetic material. The effect of field-dependent heat capacity on regeneration is discussed. The coefficients of performance of the Ericsson magnetic refrigeration cycle are derived. Finally, it is pointed out that, according to theoretical analysis, the Ericsson magnetic refrigeration cycle can be expected to reach or approach perfect regeneration by using a mixture of several magnetic materials as the working substance.
NASA Astrophysics Data System (ADS)
Loges, André; Herberger, Sabrina; Seegert, Philipp; Wetzel, Thomas
2016-12-01
Thermal models of Li-ion cells on various geometrical scales and with various complexity have been developed in the past to account for the temperature dependent behaviour of Li-ion cells. These models require accurate data on thermal material properties to offer reliable validation and interpretation of the results. In this context a thorough study on the specific heat capacities of Li-ion cells starting from raw materials and electrode coatings to representative unit cells of jelly rolls/electrode stacks with lumped values was conducted. The specific heat capacity is reported as a function of temperature and state of charge (SOC). Seven Li-ion cells from different manufactures with different cell chemistry, application and design were considered and generally applicable correlations were developed. A 2D thermal model of an automotive Li-ion cell for plug-in hybrid electric vehicle (PHEV) application illustrates the influence of specific heat capacity on the effectivity of cooling concepts and the temperature development of Li-ion cells.
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.
Mapping glycoside hydrolase substrate subsites by isothermal titration calorimetry
Zolotnitsky, Gennady; Cogan, Uri; Adir, Noam; Solomon, Vered; Shoham, Gil; Shoham, Yuval
2004-01-01
Relating thermodynamic parameters to structural and biochemical data allows a better understanding of substrate binding and its contribution to catalysis. The analysis of the binding of carbohydrates to proteins or enzymes is a special challenge because of the multiple interactions and forces involved. Isothermal titration calorimetry (ITC) provides a direct measure of binding enthalpy (ΔHa) and allows the determination of the binding constant (free energy), entropy, and stoichiometry. In this study, we used ITC to elucidate the binding thermodynamics of xylosaccharides for two xylanases of family 10 isolated from Geobacillus stearothermophilus T-6. The change in the heat capacity of binding (ΔCp = ΔH/ΔT) for xylosaccharides differing in one sugar unit was determined by using ITC measurements at different temperatures. Because hydrophobic stacking interactions are associated with negative ΔCp, the data allow us to predict the substrate binding preference in the binding subsites based on the crystal structure of the enzyme. The proposed positional binding preference was consistent with mutants lacking aromatic binding residues at different subsites and was also supported by tryptophan fluorescence analysis. PMID:15277671
Application of isothermal titration calorimetry in bioinorganic chemistry.
Grossoehme, Nicholas E; Spuches, Anne M; Wilcox, Dean E
2010-11-01
The thermodynamics of metals ions binding to proteins and other biological molecules can be measured with isothermal titration calorimetry (ITC), which quantifies the binding enthalpy (ΔH°) and generates a binding isotherm. A fit of the isotherm provides the binding constant (K), thereby allowing the free energy (ΔG°) and ultimately the entropy (ΔS°) of binding to be determined. The temperature dependence of ΔH° can then provide the change in heat capacity (ΔC (p)°) upon binding. However, ITC measurements of metal binding can be compromised by undesired reactions (e.g., precipitation, hydrolysis, and redox), and generally involve competing equilibria with the buffer and protons, which contribute to the experimental values (K (ITC), ΔH (ITC)). Guidelines and factors that need to be considered for ITC measurements involving metal ions are outlined. A general analysis of the experimental ITC values that accounts for the contributions of metal-buffer speciation and proton competition and provides condition-independent thermodynamic values (K, ΔH°) for metal binding is developed and validated.
Differential Scanning Calorimetry (DSC) for planetary surface exploration
NASA Technical Reports Server (NTRS)
Gooding, James L.; Ming, Douglas W.
1993-01-01
Differential Scanning Calorimetry (DSC) is the quantitative measurement of the enthalpic response of a material to a systematic change in temperature. In practice, the heat flow into or outward from a sample is measured as the sample is heated or cooled at a carefully controlled rate. DSC superficially resembles, but is not the same as differential thermal analysis (DTA), which is the measurement of temperature differences between a sample and reference material as the pair is heated or cooled. The fundamental properties measured by DSC are enthalpies and temperatures of phase transitions and constant-pressure heat capacities. Depending on instrument design and the nature of the sample, high-quality DSC analyses can be obtained on only a few milligrams of solid materials. DSC requires direct contact with the sample and generally degrades, if not destroys, the sample as a consequence of heating. In laboratory applications, it is common to subject the gaseous effluent from the DSC to analysis by a separate evolved-gas analyzer (EGA).
Differential scanning calorimetry of coal
NASA Technical Reports Server (NTRS)
Gold, P. I.
1978-01-01
Differential scanning calorimetry studies performed during the first year of this project demonstrated the occurrence of exothermic reactions associated with the production of volatile matter in or near the plastic region. The temperature and magnitude of the exothermic peak were observed to be strongly affected by the heating rate, sample mass and, to a lesser extent, by sample particle size. Thermal properties also were found to be influenced by oxidation of the coal sample due to weathering effects.
Glasser, Leslie; Jenkins, H Donald Brooke
2011-09-05
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.
Liu, Jun; Zhu, Jie; Tian, Miao; Gu, Xiaokun; Schmidt, Aaron; Yang, Ronggui
2013-03-01
The increasing interest in the extraordinary thermal properties of nanostructures has led to the development of various measurement techniques. Transient thermoreflectance method has emerged as a reliable measurement technique for thermal conductivity of thin films. In this method, the determination of thermal conductivity usually relies much on the accuracy of heat capacity input. For new nanoscale materials with unknown or less-understood thermal properties, it is either questionable to assume bulk heat capacity for nanostructures or difficult to obtain the bulk form of those materials for a conventional heat capacity measurement. In this paper, we describe a technique for simultaneous measurement of thermal conductivity κ and volumetric heat capacity C of both bulk and thin film materials using frequency-dependent time-domain thermoreflectance (TDTR) signals. The heat transfer model is analyzed first to find how different combinations of κ and C determine the frequency-dependent TDTR signals. Simultaneous measurement of thermal conductivity and volumetric heat capacity is then demonstrated with bulk Si and thin film SiO2 samples using frequency-dependent TDTR measurement. This method is further testified by measuring both thermal conductivity and volumetric heat capacity of novel hybrid organic-inorganic thin films fabricated using the atomic∕molecular layer deposition. Simultaneous measurement of thermal conductivity and heat capacity can significantly shorten the development∕discovery cycle of novel materials.
Zhang, Jiao-Qiang; Gao, Hong-Xu; Ji, Tie-Zheng; Xu, Kang-Zhen; Hu, Rong-Zu
2011-10-15
The specific heat capacity (C(p)) of 37.2/44/16/2.2/0.2/0.4-GAP/CL-20/Al/N-100/PCA/auxiliaries mixture was determined with the continuous C(p) mode of microcalorimeter. The equation of C(p) with temperature was obtained. The standard molar heat capacity of GAP/CL-20/Al/N-100/PCA/auxiliaries mixture was 1.225 J mol(-1)K(-1) at 298.15K. With the help of the peak temperature (T(p)) from the non-isothermal DTG curves of the mixture at different heating rates (β), the apparent activation energy (E(k) and E(o)) and pre-exponential constant (A(K)) of thermal decomposition reaction obtained by Kissinger's method and Ozawa's method. Using density (ρ) and thermal conductivity (λ), the decomposition heat (Q(d), taking half-explosion heat), Zhang-Hu-Xie-Li's formula, the values (T(e0) and T(p0)) of T(e) and T(p) corresponding to β → 0, thermal explosion temperature (T(be) and T(bp)), adiabatic time-to-explosion (t(TIad)), 50% drop height (H(50)) of impact sensitivity, and critical temperature of hot-spot initiation (T(cr,hot spot)) of thermal explosion of the mixture were calculated. The following results of evaluating the thermal safety of the mixture were obtained: T(be) = 441.64K, T(bp) = 461.66 K, t(Tlad) = 78.0 s (n = 2), t(Tlad) = 74.87 s (n = 1), t(Tlad) = 71.85 s (n = 0), H(50) = 21.33 cm.
Increment of specific heat capacity of solar salt with SiO2 nanoparticles
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
Liquid scintillator tiles for calorimetry
Amouzegar, M.; Belloni, A.; Bilki, B.; Calderon, J.; Barbaro, P. De; Eno, S. C.; Hatakeyama, K.; Hirschauer, J.; Jeng, G. Y.; Pastika, N. J.; Pedro, K.; Rumerio, Paolo; Samuel, J.; Sharp, E.; Shin, Y. H.; Tiras, E.; Vishnevskiy, D.; Wetzel, J.; Yang, Z.; Yao, Y.; Youn, S. W.
2016-11-28
Future experiments in high energy and nuclear physics may require large, inexpensive calorimeters that can continue to operate after receiving doses of 50 Mrad or more. Also, the light output of liquid scintillators suffers little degradation under irradiation. However, many challenges exist before liquids can be used in sampling calorimetry, especially regarding developing a packaging that has sufficient efficiency and uniformity of light collection, as well as suitable mechanical properties. We present the results of a study of a scintillator tile based on the EJ-309 liquid scintillator using cosmic rays and test beam on the light collection efficiency and uniformity, and some preliminary results on radiation hardness.
Liquid scintillator tiles for calorimetry
NASA Astrophysics Data System (ADS)
Amouzegar, M.; Belloni, A.; Bilki, B.; Calderon, J.; De Barbaro, P.; Eno, S. C.; Hatakeyama, K.; Hirschauer, J.; Jeng, G. Y.; Pastika, N. J.; Pedro, K.; Rumerio, Paolo; Samuel, J.; Sharp, E.; Shin, Y. H.; Tiras, E.; Vishnevskiy, D.; Wetzel, J.; Yang, Z.; Yao, Y.; Youn, S. W.
2016-11-01
Future experiments in high energy and nuclear physics may require large, inexpensive calorimeters that can continue to operate after receiving doses of 50 Mrad or more. The light output of liquid scintillators suffers little degradation under irradiation. However, many challenges exist before liquids can be used in sampling calorimetry, especially regarding developing a packaging that has sufficient efficiency and uniformity of light collection, as well as suitable mechanical properties. We present the results of a study of a scintillator tile based on the EJ-309 liquid scintillator using cosmic rays and test beam on the light collection efficiency and uniformity, and some preliminary results on radiation hardness.
The Floquet Adiabatic Theorem revisited
NASA Astrophysics Data System (ADS)
Weinberg, Phillip; Bukov, Marin; D'Alessio, Luca; Kolodrubetz, Michael; Davidson, Shainen; Polkovnikov, Anatoli
2015-03-01
The existance of the adiabatic theorem for Floquet systems has been the subject of an active debate with different articles reaching opposite conclusions over the years. In this talk we clarify the situation by deriving a systematic expansion in the time-derivatives of a slow parameter for the occupation probabilities of the Floque states. Our analysis shows that the in a certain limit the transition between Floquet eigenstates are suppressed and it is possible to define an adiabatic theorem for Floquet systems. Crucially we observe however that the conditions for adiabaticity in ordinary and Floquet systems are different and that this difference can become important when the amplitude of the periodic driving is large. We illustrate our results with specific examples of a periodically driven harmonic oscillator and cold atoms in optical lattices which are relevant in current experiments.
Adiabatic losses in Stirling refrigerators
Bauwens, L.
1996-06-01
The Stirling cycle has been used very effectively in cryocoolers; but efficiencies relative to the Carnot limit are typically observed to peak for absolute temperature ratios of about two, which makes it less suitable for low-life refrigeration. The adiabatic loss appears to be responsible for poor performance at small temperature differences. In this paper, adiabatic losses are evaluated, for a temperature ratio of 2/3, taking into account the effect of phase angle between pistons, of volume ratio, of the distribution of the dead volume necessary to reduce the volume ratio, and of the distribution of displacement between expansion and compression spaces. The study is carried out numerically, using an adiabatic Stirling engine model in which cylinder flow is assumed to be stratified. Results show that the best location for the cylinder dead volume is on the compression side. Otherwise, all strategies used to trade off refrigeration for coefficient of performance are found to be roughly equivalent.
NASA Astrophysics Data System (ADS)
Ji, Pengfei; Zhang, Yuwen
2016-03-01
On the basis of ab initio quantum mechanics (QM) calculation, the obtained electron heat capacity is implemented into energy equation of electron subsystem in two temperature model (TTM). Upon laser irradiation on the copper film, energy transfer from the electron subsystem to the lattice subsystem is modeled by including the electron-phonon coupling factor in molecular dynamics (MD) and TTM coupled simulation. The results show temperature and thermal melting difference between the QM-MD-TTM integrated simulation and pure MD-TTM coupled simulation. The successful construction of the QM-MD-TTM integrated simulation provides a general way that is accessible to other metals in laser heating.
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
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:
NASA Astrophysics Data System (ADS)
Kourov, N. I.; Marchenkov, V. V.; Korolev, A. V.; Lukoyanov, A. V.
2016-07-01
The heat capacity of band magnets Fe2 MeAl ( Me = Ti, V, Cr, Mn, Fe, Co, Ni) ordered in crystal structure L21 has been measured in the range 2 K ≤ T ≤ 50 K. The dependences of the Debye temperature ΘD, the Sommerfeld coefficient γ, and the temperature-independent contribution to heat capacity C 0 on the number of valence electrons z in the alloys have been determined.
NASA Astrophysics Data System (ADS)
Leontev, K. L.
1981-07-01
An expression is obtained for heat capacity differences of materials at a constant pressure and volume, on the basis of the rigorous thermodynamic equation (Kittel, 1976), and by using the Grueneisen law (Kikoin and Kikoin, 1976) of constancy of the ratio of the cubic expansion coefficient to the molar heat capacity. Conditions are determined, where the empirical Nernst and Lindemann (Filippov, 1967) equation is regarded as rigorous.
Adiabatic evolution of plasma equilibrium
Grad, H.; Hu, P. N.; Stevens, D. C.
1975-01-01
A new theory of plasma equilibrium is introduced in which adiabatic constraints are specified. This leads to a mathematically nonstandard structure, as compared to the usual equilibrium theory, in which prescription of pressure and current profiles leads to an elliptic partial differential equation. Topologically complex configurations require further generalization of the concept of adiabaticity to allow irreversible mixing of plasma and magnetic flux among islands. Matching conditions across a boundary layer at the separatrix are obtained from appropriate conservation laws. Applications are made to configurations with planned islands (as in Doublet) and accidental islands (as in Tokamaks). Two-dimensional, axially symmetric, helically symmetric, and closed line equilibria are included. PMID:16578729
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.
Differential scanning calorimetry as a tool for protein folding and stability.
Johnson, Christopher M
2013-03-01
Differential scanning calorimetry measures the heat capacity of states and the excess heat associated with transitions that can be induced by temperature change. The integral of the excess heat capacity is the enthalpy for this process. Despite this potentially intimidating sounding physical chemistry background, DSC has found almost universal application in studying biological macromolecules. In the case of proteins, DSC can be used to determine equilibrium thermodynamic stability and folding mechanism but can also be used in a more qualitative manner screening for thermal stability as an indicator for, ligand binding, pharmaceutical formulation or conditions conducive to crystal growth. DSC usually forms part of a wider biophysical characterisation of the biological system of interest and so the literature is diverse and difficult to categorise for the technique in isolation. This review therefore describes the potential uses of DSC in studying protein folding and stability, giving brief examples of applications from the recent literature. There have also been some interesting developments in the use of DSC to determine barrier heights for fast folding proteins and in studying complex protein mixtures such as human plasma that are considered in more detail.
Toledo-Núñez, Citlali; Vera-Robles, L Iraís; Arroyo-Maya, Izlia J; Hernández-Arana, Andrés
2016-09-15
A frequent outcome in differential scanning calorimetry (DSC) experiments carried out with large proteins is the irreversibility of the observed endothermic effects. In these cases, DSC profiles are analyzed according to methods developed for temperature-induced denaturation transitions occurring under kinetic control. In the one-step irreversible model (native → denatured) the characteristics of the observed single-peaked endotherm depend on the denaturation enthalpy and the temperature dependence of the reaction rate constant, k. Several procedures have been devised to obtain the parameters that determine the variation of k with temperature. Here, we have elaborated on one of these procedures in order to analyze more complex DSC profiles. Synthetic data for a heat capacity curve were generated according to a model with two sequential reactions; the temperature dependence of each of the two rate constants involved was determined, according to the Eyring's equation, by two fixed parameters. It was then shown that our deconvolution procedure, by making use of heat capacity data alone, permits to extract the parameter values that were initially used. Finally, experimental DSC traces showing two and three maxima were analyzed and reproduced with relative success according to two- and four-step sequential models.
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.
Heat capacity of the site-diluted spin dimer system Ba₃(Mn1-xVx)₂O₈
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
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.
Fivez, J; Longuemart, S; Glorieux, C
2012-01-28
Starting from the Debye model for frequency-dependent specific heat and the Vogel-Fulcher-Tammann (VFT) model for its relaxation time, an analytic expression is presented for the heat capacity versus temperature trace for differential scanning calorimetry (DSC) of glass transitions, suggesting a novel definition of the glass transition temperature based on a dimensionless criterion. An explicit expression is presented for the transition temperature as a function of the VFT parameters and the cooling rate, and for the slope as a function of fragility. Also a generalization of the results to non-VFT and non-Debye relaxation is given. Two unique ways are proposed to tackle the inverse problem, i.e., to extract the fragility from an experimental DSC trace. Good agreement is found between theoretically predicted DSC traces and experimental DSC traces for glycerol for different cooling rates.
NASA Astrophysics Data System (ADS)
Fivez, J.; Longuemart, S.; Glorieux, C.
2012-01-01
Starting from the Debye model for frequency-dependent specific heat and the Vogel-Fulcher-Tammann (VFT) model for its relaxation time, an analytic expression is presented for the heat capacity versus temperature trace for differential scanning calorimetry (DSC) of glass transitions, suggesting a novel definition of the glass transition temperature based on a dimensionless criterion. An explicit expression is presented for the transition temperature as a function of the VFT parameters and the cooling rate, and for the slope as a function of fragility. Also a generalization of the results to non-VFT and non-Debye relaxation is given. Two unique ways are proposed to tackle the inverse problem, i.e., to extract the fragility from an experimental DSC trace. Good agreement is found between theoretically predicted DSC traces and experimental DSC traces for glycerol for different cooling rates.
Pressure Oscillations in Adiabatic Compression
ERIC Educational Resources Information Center
Stout, Roland
2011-01-01
After finding Moloney and McGarvey's modified adiabatic compression apparatus, I decided to insert this experiment into my physical chemistry laboratory at the last minute, replacing a problematic experiment. With insufficient time to build the apparatus, we placed a bottle between two thick textbooks and compressed it with a third textbook forced…
Transitionless driving on adiabatic search algorithm
Oh, Sangchul; Kais, Sabre
2014-12-14
We study quantum dynamics of the adiabatic search algorithm with the equivalent two-level system. Its adiabatic and non-adiabatic evolution is studied and visualized as trajectories of Bloch vectors on a Bloch sphere. We find the change in the non-adiabatic transition probability from exponential decay for the short running time to inverse-square decay in asymptotic running time. The scaling of the critical running time is expressed in terms of the Lambert W function. We derive the transitionless driving Hamiltonian for the adiabatic search algorithm, which makes a quantum state follow the adiabatic path. We demonstrate that a uniform transitionless driving Hamiltonian, approximate to the exact time-dependent driving Hamiltonian, can alter the non-adiabatic transition probability from the inverse square decay to the inverse fourth power decay with the running time. This may open up a new but simple way of speeding up adiabatic quantum dynamics.
Transitionless driving on adiabatic search algorithm
NASA Astrophysics Data System (ADS)
Oh, Sangchul; Kais, Sabre
2014-12-01
We study quantum dynamics of the adiabatic search algorithm with the equivalent two-level system. Its adiabatic and non-adiabatic evolution is studied and visualized as trajectories of Bloch vectors on a Bloch sphere. We find the change in the non-adiabatic transition probability from exponential decay for the short running time to inverse-square decay in asymptotic running time. The scaling of the critical running time is expressed in terms of the Lambert W function. We derive the transitionless driving Hamiltonian for the adiabatic search algorithm, which makes a quantum state follow the adiabatic path. We demonstrate that a uniform transitionless driving Hamiltonian, approximate to the exact time-dependent driving Hamiltonian, can alter the non-adiabatic transition probability from the inverse square decay to the inverse fourth power decay with the running time. This may open up a new but simple way of speeding up adiabatic quantum dynamics.
Transitionless driving on adiabatic search algorithm.
Oh, Sangchul; Kais, Sabre
2014-12-14
We study quantum dynamics of the adiabatic search algorithm with the equivalent two-level system. Its adiabatic and non-adiabatic evolution is studied and visualized as trajectories of Bloch vectors on a Bloch sphere. We find the change in the non-adiabatic transition probability from exponential decay for the short running time to inverse-square decay in asymptotic running time. The scaling of the critical running time is expressed in terms of the Lambert W function. We derive the transitionless driving Hamiltonian for the adiabatic search algorithm, which makes a quantum state follow the adiabatic path. We demonstrate that a uniform transitionless driving Hamiltonian, approximate to the exact time-dependent driving Hamiltonian, can alter the non-adiabatic transition probability from the inverse square decay to the inverse fourth power decay with the running time. This may open up a new but simple way of speeding up adiabatic quantum dynamics.
Digital waveguide adiabatic passage part 1: theory
NASA Astrophysics Data System (ADS)
Vaitkus, Jesse A.; Steel, M. J.; Greentree, Andrew D.
2017-03-01
Spatial adiabatic passage represents a new way to design integrated photonic devices. In conventional adiabatic passage designs require smoothly varying waveguide separations. Here we show modelling of adiabatic passage devices where the waveguide separation is varied digitally. Despite digitisation, our designs show robustness against variations in the input wavelength and refractive index contrast of the waveguides relative to the cladding. This approach to spatial adiabatic passage opens new design strategies and hence the potential for new photonics devices.
Liquid scintillator tiles for calorimetry
Amouzegar, M.; Belloni, A.; Bilki, B.; ...
2016-11-28
Future experiments in high energy and nuclear physics may require large, inexpensive calorimeters that can continue to operate after receiving doses of 50 Mrad or more. Also, the light output of liquid scintillators suffers little degradation under irradiation. However, many challenges exist before liquids can be used in sampling calorimetry, especially regarding developing a packaging that has sufficient efficiency and uniformity of light collection, as well as suitable mechanical properties. We present the results of a study of a scintillator tile based on the EJ-309 liquid scintillator using cosmic rays and test beam on the light collection efficiency and uniformity,more » and some preliminary results on radiation hardness.« less
NASA Astrophysics Data System (ADS)
Oguni, M.; Angell, C. A.
1983-06-01
Recently reported heat capacity studies of N2H4+H2O and H2O2+H2O solutions, from which an anomalous component of the pure water behavior could be extracted by extrapolation, have been extended to a system NH2CHO+H2O which has the chemical stability needed to permit expansivity and compressibility measurements as well. Data accurate to ±2% for each of these properties as well as for the heat capacity are reported. The expansivity data support almost quantitatively an earlier speculative separation of the bulk and supercooled water expansivity into a ``normal'' (or ``background'') part and an ``anomalous'' part, the latter part fitting a critical law αanom=A(T/Ts-1)-γ with exponent γ=1.0. According to the present analysis, the anomalous part of the expansivity which is always negative, yields Ts in the range 225-228, γ in the range 1.28-1.0, depending on the choice of background extrapolation function. The normal contribution to the heat capacity obtained from the present work is intermediate in character to that from the previous two systems and leads to similar equation parameters. The normal contribution to the compressibility on the other hand is very different from that speculated earlier by Kanno and Angell and approximately verified by Conde et al. for ethanol-water solutions. The background component from the present analysis is ˜50% larger, with the result that the anomalous component, at least when values above 0 °C are included in the analysis, cannot be sensibly fitted to the critical point equation. The possible origin and interest content of these differences is discussed. Combination of the new thermodynamic data permit estimation of Cv values for the solution, and by extrapolation, a normal Cv component for water. The anomalous component of Cv for pure water obtained by difference has the form of a Shottky anomaly in contrast with the corresponding Cp component which diverges.
Tung, L. D.; Ivanov, A.; Schefer, J.; Lees, M. R.; Balakrishnan, G.; Paul, D. McK.
2008-08-01
We report the results of magnetization, heat capacity, and neutron scattering studies of LaVO{sub 3} single crystals. From the neutron-diffraction studies, it was found that the compound is magnetically ordered with a C-type antiferromagnetic spin structure at about 136 K. In the vicinity of the ordering temperature, we also observed hysteresis in the neutron-diffraction data measured on cooling and heating which indicates the first-order nature of the phase transition. In the antiferromagnetically ordered phase, the inelastic neutron scattering studies reveal the presence of a temperature independent c-axis spin-wave gap of about 6 meV which is similar to that previously reported for the sister compound YVO{sub 3}.
Zhou, Huan-Xiang
2002-12-01
The enrichment of salt bridges and hydrogen bonding in thermophilic proteins has long been recognized. Another tendency, featuring lower heat capacity of unfolding (DeltaC(p)) than found in mesophilic proteins, is emerging from the recent literature. Here we present a simple electrostatic model to illustrate that formation of a salt-bridge or hydrogen-bonding network around an ionized group in the folded state leads to increased folding stability and decreased DeltaC(p). We thus suggest that the reduced DeltaC(p) of thermophilic proteins could partly be attributed to enriched polar interactions. A reduced DeltaC(p) might serve as an indicator for the contribution of polar interactions to folding stability.
NASA Astrophysics Data System (ADS)
Schrödle, Simon; Königsberger, Erich; May, Peter M.; Hefter, Glenn
2010-04-01
A modified commercial (Setaram C80) calorimeter has been used to measure the isobaric volumetric heat capacities of concentrated alkaline sodium aluminate solutions at ionic strengths from 1 to 6 mol kg -1, with up to 40 mol.% substitution of hydroxide by aluminate, at temperatures from 50 to 300 °C and a pressure of 10 MPa. Apparent molar heat capacities for the mixtures, C pϕ, derived from these data were found to depend linearly on the aluminate substitution level, i.e., they followed Young's rule. These quantities were used to estimate the apparent molar heat capacities of pure, hypothetical sodium aluminate solutions, C pϕ ('NaAl(OH) 4'(aq)). Slopes of the Young's rule plots were invariant with ionic strength at a given temperature but depended linearly on temperature. The heat capacities of ternary aqueous sodium hydroxide/aluminate mixtures could therefore be modelled using only two parameters in addition to those needed for the correlation of C pϕ (NaOH(aq)) reported previously from these laboratories. An assessment of the standard thermodynamic quantities for boehmite, gibbsite and the aluminate ion yielded a set of recommended values that, together with the present heat capacity data, accurately predicts the solubility of gibbsite and boehmite at temperatures up to 300 °C.
Dijet mass resolution and compensating calorimetry
Green, D.
1991-05-01
The calorimetry for SSC detectors has as its role the detection of the basic particles of the Standard Model. Those germane to calorimetry are quarks, photons, electrons, and gluons. Note that all the hadronic entities appear in the calorimetry as jets. The detection of single hadrons belongs to a past era when quark molecules'' were the focus of intense study. Thus, the goal of calorimetry at the SSC must be the study of jets. In particular, one must understand what defines the limits of accuracy of the jets. If there are intrinsic physical processes which limit the precision of jet measurements, then calorimetry which is more accurate is unnecessary if not wasteful. 5 refs., 5 figs.
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.
NASA Astrophysics Data System (ADS)
Li, Dafa
2016-05-01
The adiabatic theorem was proposed about 90 years ago and has played an important role in quantum physics. The quantitative adiabatic condition constructed from eigenstates and eigenvalues of a Hamiltonian is a traditional tool to estimate adiabaticity and has proven to be the necessary and sufficient condition for adiabaticity. However, recently the condition has become a controversial subject. In this paper, we list some expressions to estimate the validity of the adiabatic approximation. We show that the quantitative adiabatic condition is invalid for the adiabatic approximation via the Euclidean distance between the adiabatic state and the evolution state. Furthermore, we deduce general necessary and sufficient conditions for the validity of the adiabatic approximation by different definitions.
Conner, Benjamin S.; Susner, Michael A.; Lampen-Kelley, Paula; ...
2017-04-04
Advances in crystal growth have allowed for synthesis of large single crystals of Nd1+ϵFe4B4, a well-known phase with a modulated structure. As a result we are able to report heat capacity and resistivity measurements on a single crystal Nd1+ϵFe4B4 sample with a distribution of ϵ that skews towards the solubility limit of Nd near ϵ ≈ 17. Heat capacity measurements show evidence of crystal field splitting at temperatures higher than the long-range ferromagnetic Curie temperature. Heat capacity, resistivity, and magnetization measurements all confirm a Curie temperature of 7 K which is lower than previously reported values in the Nd1+ϵFe4B4 system.more » Here, we also perform measurements of the angular dependence of the magnetization and discover behavior associated with the magnetic anisotropy that is inconsistent with the simple description previously proposed.« less
Izutani, Yusuke; Kanaori, Kenji; Imoto, Toshiaki; Oda, Masayuki
2005-12-01
The physiological phenomenon that the antisweet taste effect of gymnemic acid (GA) is diminished by application of gamma-cyclodextrin (gamma-CD) to the mouth was evaluated at the molecular level using isothermal titration calorimetry, NMR and dynamic light scattering. These analyses showed that GA specifically binds to gamma-CD. Thermodynamic analysis using isothermal titration calorimetry revealed that the association constant of GA and gamma-CD is 10(5)-10(6) m(-1) with favorable enthalpy and entropy changes. The heat capacity change was negative and large, despite the change in accessible surface area upon binding being small. These thermodynamics indicate that the binding is dominated by hydrophobic interactions, which is in agreement with inclusion complex formation of gamma-CD. In addition, NMR measurements showed that in solution the spectra of GA are broad and sharpened by the addition of gamma-CD, indicating that unbound GA is in a water-soluble aggregate that is dispersed when it forms a complex with gamma-CD. Dynamic light scattering showed that the average diameter of unbound GA is > 30 nm and that of GA and gamma-CD complex is 2.2 nm, similar to unbound gamma-CD, supporting the aggregate property of GA and the inclusion complexation of GA by gamma-CD.
Theory of Adiabatic Fountain Resonance
NASA Astrophysics Data System (ADS)
Williams, Gary A.
2017-01-01
The theory of "Adiabatic Fountain Resonance" with superfluid ^4{He} is clarified. In this geometry a film region between two silicon wafers bonded at their outer edge opens up to a central region with a free surface. We find that the resonance in this system is not a Helmholtz resonance as claimed by Gasparini et al., but in fact is a fourth sound resonance. We postulate that it occurs at relatively low frequency because the thin silicon wafers flex appreciably from the pressure oscillations of the sound wave.
Adiabatic Wankel type rotary engine
NASA Technical Reports Server (NTRS)
Kamo, R.; Badgley, P.; Doup, D.
1988-01-01
This SBIR Phase program accomplished the objective of advancing the technology of the Wankel type rotary engine for aircraft applications through the use of adiabatic engine technology. Based on the results of this program, technology is in place to provide a rotor and side and intermediate housings with thermal barrier coatings. A detailed cycle analysis of the NASA 1007R Direct Injection Stratified Charge (DISC) rotary engine was performed which concluded that applying thermal barrier coatings to the rotor should be successful and that it was unlikely that the rotor housing could be successfully run with thermal barrier coatings as the thermal stresses were extensive.
Automatic calorimetry system monitors RF power
NASA Technical Reports Server (NTRS)
Harness, B. W.; Heiberger, E. C.
1969-01-01
Calorimetry system monitors the average power dissipated in a high power RF transmitter. Sensors measure the change in temperature and the flow rate of the coolant, while a multiplier computes the power dissipated in the RF load.
Ultrafast adiabatic second harmonic generation
NASA Astrophysics Data System (ADS)
Dahan, Asaf; Levanon, Assaf; Katz, Mordechai; Suchowski, Haim
2017-03-01
We introduce a generalization of the adiabatic frequency conversion method for an efficient conversion of ultrashort pulses in the full nonlinear regime. Our analysis takes into account dispersion as well as two-photon processes and Kerr effect, allowing complete analysis of any three waves with arbitrary phase mismatched design and any nonlinear optical process. We use this analysis to design an efficient and robust second harmonic generation, the most widely used nonlinear process for both fundamental and applied research. We experimentally show that such design not only allows for very efficient conversion of various of ultrashort pulses, but is also very robust to variations in the parameters of both the nonlinear crystal and the incoming light. These include variation of more than 100 °C in the crystal temperature, a wide bandwidth of up to 75 nm and a chirp variation of 300 fs to 3.5 ps of the incoming pulse. Also, we show the dependency of the adiabatic second harmonic generation design on the pump intensity and the crystal length. Our study shows that two photon absorption plays a critical role in such high influence nonlinear dynamics, and that it must be considered in order to achieve agreement with experimental results.
Ultrafast adiabatic second harmonic generation.
Dahan, Asaf; Levanon, Assaf; Katz, Mordechai; Suchowski, Haim
2017-03-01
We introduce a generalization of the adiabatic frequency conversion method for an efficient conversion of ultrashort pulses in the full nonlinear regime. Our analysis takes into account dispersion as well as two-photon processes and Kerr effect, allowing complete analysis of any three waves with arbitrary phase mismatched design and any nonlinear optical process. We use this analysis to design an efficient and robust second harmonic generation, the most widely used nonlinear process for both fundamental and applied research. We experimentally show that such design not only allows for very efficient conversion of various of ultrashort pulses, but is also very robust to variations in the parameters of both the nonlinear crystal and the incoming light. These include variation of more than 100 °C in the crystal temperature, a wide bandwidth of up to 75 nm and a chirp variation of 300 fs to 3.5 ps of the incoming pulse. Also, we show the dependency of the adiabatic second harmonic generation design on the pump intensity and the crystal length. Our study shows that two photon absorption plays a critical role in such high influence nonlinear dynamics, and that it must be considered in order to achieve agreement with experimental results.
Low-temperature heat-capacity studies of R2Ni3Si5 (R=Pr, Nd, Sm, Gd, Tb, Dy, Ho)
NASA Astrophysics Data System (ADS)
Mazumdar, Chandan; Ghosh, K.; Nagarajan, R.; Ramakrishnan, S.; Padalia, B. D.; Gupta, L. C.
1999-02-01
We report here our low temperature (2-30 K) heat capacity, Cp measurements of R2Ni3Si5 (R=Pr, Nd, Sm, Gd-Ho). Large peaks in heat capacity data at magnetic transition temperatures (TN) confirm the bulk nature of magnetic order in these compounds. In Nd2Ni3Si5, Gd2Ni3Si5, and Dy2Ni3Si5, magnetization studies indicated only one magnetic transition, whereas, heat-capacity data show two transitions. TN of the heavier rare-earth member, Tb2Ni3Si5, showing significant deviation from de Gennes scaling is notable. Magnetic entropy, ΔS, estimated from heat-capacity data suggest that the magnetic ground state is a doublet in R2Ni3Si5 (R=Pr, Nd, Sm, Dy, Ho) and a quartet in Tb2Ni3Si5. In all the cases, ΔS, at TN is slightly less than that expected due to the suggested states, which we attribute to the occurrence of precursor effects of magnetic order above TN. Except for Gd2Ni3Si5, ΔS of the compounds does not reach the saturation limit of R ln(2J+1) even at 30 K, indicating the presence of crystalline electric field (CEF) effects. A hump in Cp is observed below TN in Gd2Ni3Si5 which is interpreted in terms of a possible amplitude-modulated magnetic spin structure.
Spencer, E C; Ross, N L; Parker, S F; Woodfield, B F; Boerio-Goates, J; Smith, S J; Olsen, R E; Kolesnikov, A I; Navrotsky, A; Ma, C
2011-05-25
We present low temperature (11 K) inelastic neutron scattering (INS) data on four hydrated nanoparticle systems: 10 nm CoO·0.10H(2)O (1), 16 nm Co(3)O(4)·0.40H(2)O (2), 25 nm Co(3)O(4)·0.30H(2)O (3) and 40 nm Co(3)O(4)·0.026H(2)O (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 Co(3)O(4), and this is reflected in the reduced heat capacity and vibrational entropy for water on CoO relative to water on Co(3)O(4) 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 Co(3)O(4) 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 Co(3)O(4) 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.
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.
NASA Astrophysics Data System (ADS)
Vishwakarma, V.; Jain, A.
2014-12-01
The separator is a critical, multi-functional component of a Li-ion cell that plays a key role in performance and safety during energy conversion and storage processes. Heat flow through the separator is important for minimizing cell temperature and avoiding thermal runaway. Despite the critical nature of thermal conduction through the separator, very little research has been reported on understanding and measuring the thermal conductivity and heat capacity of the separator. This paper presents first-ever measurements of thermal conductivity and heat capacity of the separator material. These measurements are based on thermal response to an imposed DC heating within a time period during which an assumption of a thermally semi-infinite domain is valid. Experimental data are in excellent agreement with the analytical model. Comparison between the two results in measurement of the in-plane thermal conductivity and heat capacity of the separator. Results indicate very low thermal conductivity of the separator. Measurements at an elevated temperature indicate that thermal conductivity and heat capacity do not change much with increasing temperature. Experimental measurements of previously unavailable thermal properties reported here may facilitate a better fundamental understanding of thermal transport in a Li-ion cell, and enhanced safety due to more accurate thermal prediction.
NASA Astrophysics Data System (ADS)
Yarmohammadi, Mohsen
2017-04-01
In the current work, we theoretically study the electronic band structure (EBS), electronic heat capacity (EHC) and magnetic susceptibility (MS) of three structures including monolayer, AA-stacked and AB-stacked bilayer silicene based on the Kane-Mele Hamiltonian model and Green's function method. The particular attention of this study is paid to the effect of external electric field on the aforementioned physical properties. By variation of the electric field, three phases are found: Topological insulator (TI), valley-spin polarized metal (VSPM) and band insulator (BI). Marvellously, its electronic minibands show that the spin-up contribution of charge carriers with lowest energy bands behaves like relativistic Dirac fermions with linear (parabolic) energy dispersions in monolayer (bilayer) case near the Dirac points. An insightful analysis shows that the maximum and minimum value of EHC peak appear for (AA) AB-stacked bilayer and monolayer silicene in TI (BI) regime while in MS curves appear for (AB) AA-stacked bilayer and monolayer lattices in TI (BI) regime, respectively. Moreover, we have observed a phase transition from antiferromagnetic to ferromagnetic and paramagnetic in the monolayer and bilayer structures in the VSPM regime based on the MS findings, respectively.
Lasfargues, Mathieu; Geng, Qiao; Cao, Hui; Ding, Yulong
2015-01-01
In this study, the effect of nanoparticle concentration was tested for both CuO and TiO2 in eutectic mixture of sodium and potassium nitrate. Results showed an enhancement in specific heat capacity (Cp) for both types of nanoparticles (+10.48% at 440 °C for 0.1 wt % CuO and +4.95% at 440 °C for 0.5 wt % TiO2) but the behavior toward a rise in concentration was different with CuO displaying its highest enhancement at the lowest concentration whilst TiO2 showed no concentration dependence for three of the four different concentrations tested. The production of cluster of nanoparticles was visible in CuO but not in TiO2. This formation of nanostructure in molten salt might promote the enhancement in Cp. However, the size and shape of these structures will most likely impact the energy density of the molten salt. PMID:28347056
Tombari, E; Presto, S; Salvetti, G; Johari, G P
2006-04-21
We report a thermodynamic study of the formation of tetrahydrofuran clathrate hydrate by explosive crystallization of water-deficient, near stoichiometric, and water-rich solutions, as well as of the heat capacity, C(p), of (i) supercooled tetrahydrofuran-H2O solutions and of the clathrate hydrate, (ii) tetrathydrofuran (THF) liquid, and (iii) supercooled water and the ice formed on its explosive crystallization. In explosive freezing of supercooled solutions at a temperature below 257 K, THF clathrate hydrate formed first. The nucleation temperature depends on the cooling rate, and excess water freezes on further cooling. The clathrate hydrate melts reversibly at 277 K and C(p) increases by 770 J/mol K on melting. The enthalpy of melting is 99.5 kJ/mol and entropy is 358 J/mol K. Molar C(p) of the empty host lattice is less than that of the ice, which is inconsistent with the known lower phonon frequency of H2O in the clathrate lattice. Analysis shows that C(p) of THF and ice are not additive in the clathrate. C(p) of the supercooled THF-H2O solutions is the same as that of water at 247 K, but less at lower temperatures and more at higher temperatures. The difference tends to become constant at 283 K. The results are discussed in terms of the hydrogen-bonding changes between THF and H2O.
NASA Astrophysics Data System (ADS)
Lion, Alexander; Mittermeier, Christoph; Johlitz, Michael
2017-01-01
A novel approach to represent the glass transition is proposed. It is based on a physically motivated extension of the linear viscoelastic Poynting-Thomson model. In addition to a temperature-dependent damping element and two linear springs, two thermal strain elements are introduced. In order to take the process dependence of the specific heat into account and to model its characteristic behaviour below and above the glass transition, the Helmholtz free energy contains an additional contribution which depends on the temperature history and on the current temperature. The model describes the process-dependent volumetric and caloric behaviour of glass-forming materials, and defines a functional relationship between pressure, volumetric strain, and temperature. If a model for the isochoric part of the material behaviour is already available, for example a model of finite viscoelasticity, the caloric and volumetric behaviour can be represented with the current approach. The proposed model allows computing the isobaric and isochoric heat capacities in closed form. The difference c_p -c_v is process-dependent and tends towards the classical expression in the glassy and equilibrium ranges. Simulations and theoretical studies demonstrate the physical significance of the model.
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.
NASA Astrophysics Data System (ADS)
Povzner, A. A.; Volkov, A. G.; Nogovitsyna, T. A.
2017-02-01
The influence of spin fluctuations on the thermodynamic properties of a helical ferromagnet MnSi has been investigated in the framework of the Hubbard model with the electronic spectrum determined from the first-principles LDA + U + SO calculation, which is extended taking into account the Hund coupling and the Dzyaloshinskii-Moriya antisymmetric exchange. It has been shown that the ground state of the magnetic material is characterized by large zero-point fluctuations, which disappear at the temperature T* (< T c is the temperature of the magnetic phase transition). In this case, the entropy abruptly increases, and a lambdashaped anomaly appears in the temperature dependence of the heat capacity at constant volume ( C V ( T)). In the temperature range T* < T < T c , thermal fluctuations lead to the disappearance of the inhomogeneous magnetization. The competition between the increase in the entropy due to paramagnon excitations and its decrease as a result of the reduction in the amplitude of local magnetic moments, under the conditions of strong Hund exchange, is responsible for in the appearance of a "shoulder" in the dependence C V ( T)).
Eckart, Megan E.; Adams, Joseph S.; Smith, Stephen J.; Bandler, Simon R.; Brekosky, Regis P.; Chervenak, James A.; Finkbeiner, Fred M.; Kelley, Richard L.; Kilbourne, Caroline A.; Scott Porter, F.; Sadleir, John E.
2009-12-16
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.
Kim, J.S.; Park, Y.; Lee, H.; Yu, S.I.
1997-03-01
Heat capacities of the water + lithium bromide + ethanolamine (LiBr/H{sub 2}N(CH{sub 2}){sub 2}OH mass ratio = 3.5) and water + lithium bromide + 1,3-propanediol (LiBr/HO(CH{sub 2}){sub 3}OH mass ratio = 3.5) systems were measured by using an isoperibol solution calorimeter at four temperatures (283.15, 298.15, 313.15, and 333.15 K) and absorbent (LiBr + H{sub 2}N(CH{sub 2}){sub 2}OH and LiBr + HO(CH{sub 2}){sub 3}OH) concentration ranges of (29.2 to 70.7)% and (30.7 to 68.3)%, respectively. The measured values were fitted with a simple equation by a least-squares method and the average absolute deviations between experimental and calculated values were 0.21% for the water + lithium bromide + ethanolamine system and 0.15% for the water + lithium bromide + 1,3-propanediol system, respectively.
Bruylants, G; Wouters, J; Michaux, C
2005-01-01
All biological phenomena depend on molecular recognition, which is either intermolecular like in ligand binding to a macromolecule or intramolecular like in protein folding. As a result, understanding the relationship between the structure of proteins and the energetics of their stability and binding with others (bio)molecules is a very interesting point in biochemistry and biotechnology. It is essential to the engineering of stable proteins and to the structure-based design of pharmaceutical ligands. The parameter generally used to characterize the stability of a system (the folded and unfolded state of the protein for example) is the equilibrium constant (K) or the free energy (deltaG(o)), which is the sum of enthalpic (deltaH(o)) and entropic (deltaS(o)) terms. These parameters are temperature dependent through the heat capacity change (deltaCp). The thermodynamic parameters deltaH(o) and deltaCp can be derived from spectroscopic experiments, using the van't Hoff method, or measured directly using calorimetry. Along with isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC) is a powerful method, less described than ITC, for measuring directly the thermodynamic parameters which characterize biomolecules. In this article, we summarize the principal thermodynamics parameters, describe the DSC approach and review some systems to which it has been applied. DSC is much used for the study of the stability and the folding of biomolecules, but it can also be applied in order to understand biomolecular interactions and can thus be an interesting technique in the process of drug design.
Novikov, V V; Zhemoedov, N A; Mitroshenkov, N V; Matovnikov, A V
2016-11-01
We experimentally study the heat capacity and thermal expansion of thulium boride (TmB50) at temperatures of 2-300 K. The wide temperature range (2-180 K) of boride negative expansion was revealed. We found the anomalies in C(T) heat capacity temperature dependence, attributed to the Schottky contribution (i.e. the influence of the crystal electric field: CEF), as well as the magnetic phase transition. CEF-splitting of the f-levels of the Tm(3+) ion was described by the Schottky function of heat capacity with a quasi-quartet in the ground state. Excited multiplets are separated from the ground state by energy gaps δ1 = 100 K, and δ2 ≈ 350 K. The heat capacity maximum at Tmax ≈ 2.4 K may be attributed to the possible magnetic transition in TmB50. Other possible causes of the low-temperature maximum of C(T) dependence are the nonspherical surroundings of rare earth atoms due to the boron atoms in the crystal lattice of the boride and the emergence of two-level systems, as well as the splitting of the ground multiplet due to local magnetic fields of the neighboring ions of thulium. Anomalies in heat capacity are mapped with the thermal expansion features of boride. It is found that the TmB50 thermal expansion characteristic features are due to the influence of the CEF, as well as the asymmetry of the spatial arrangement of boron atoms around the rare earth atoms in the crystal lattice of RB50. The Grüneisen parameters, corresponding to the excitation of different multiplets of CEF-splitting, were determined. A satisfactory accordance between the experimental and estimated temperature dependencies of the boride thermal expansion coefficient was achieved.
An interacting adiabatic quantum motor
NASA Astrophysics Data System (ADS)
Viola Kusminskiy, Silvia; Bruch, Anton; von Oppen, Felix
We consider the effect of electron-electron interactions on the performance of an adiabatic quantum motor based on a Thouless pump operating in reverse. We model such a device by electrons in a 1d wire coupled to a slowly moving periodic potential associated with the classical mechanical degree of freedom of the motor. This periodic degree of freedom is set into motion by a bias voltage applied to the 1d electron channel. We investigate the Thouless motor with interacting leads modeled as Luttinger liquids. We show that interactions enhance the energy gap opened by the periodic potential and thus the robustness of the Thouless motor against variations in the chemical potential. We show that the motor degree of freedom can be described as a mobile impurity in a Luttinger liquid obeying Langevin dynamics with renormalized coefficients due to interactions, for which we give explicit expressions.
Quantum and classical dynamics in adiabatic computation
NASA Astrophysics Data System (ADS)
Crowley, P. J. D.; Äńurić, T.; Vinci, W.; Warburton, P. A.; Green, A. G.
2014-10-01
Adiabatic transport provides a powerful way to manipulate quantum states. By preparing a system in a readily initialized state and then slowly changing its Hamiltonian, one may achieve quantum states that would otherwise be inaccessible. Moreover, a judicious choice of final Hamiltonian whose ground state encodes the solution to a problem allows adiabatic transport to be used for universal quantum computation. However, the dephasing effects of the environment limit the quantum correlations that an open system can support and degrade the power of such adiabatic computation. We quantify this effect by allowing the system to evolve over a restricted set of quantum states, providing a link between physically inspired classical optimization algorithms and quantum adiabatic optimization. This perspective allows us to develop benchmarks to bound the quantum correlations harnessed by an adiabatic computation. We apply these to the D-Wave Vesuvius machine with revealing—though inconclusive—results.
Opatowski, Ella; Kozlov, Michael M; Pinchuk, Ilya; Lichtenberg, Dov
2002-02-15
Micelle formation by many surfactants is endothermic at low temperatures but exothermic at high temperatures. In this respect, dissociation of micelles (demicellization) is similar to dissolving hydrocarbons in water. However, a remarkable difference between the two processes is that dissolving hydrocarbons is isocaloric at about 25 degrees C, almost independently of the hydrocarbon chain length, whereas the temperature (T*) at which demicellization of different surfactants is athermal varies over a relatively large range. We have investigated the temperature dependence of the heat of demicellization of three alkylglucosides with hydrocarbon chains of 7, 8, and 9 carbon atoms. At about 25 degrees C, the heat of demicellization of the three studied alkylglucosides varied within a relatively small range (DeltaH=-7.8+/-0.4 kJ/mol). The temperature dependence of DeltaH(demic) indicates that within the studied temperature range the heat capacity of demicellization (DeltaC(P,demic)) is about constant. The value of DeltaC(P,demic) exhibited an apparently linear dependence on the surfactant's chain length (DeltaC(P,demic)/n(CH(2))=47+/-7 kJ/mol K). Our interpretation of these results is that (i) the transfer of the head groups from micelles to water is exothermic and (ii) the temperature dependence of the heat associated with water-hydrocarbon interactions is only slightly affected by the head group. This implies that the deviation of the value of T* from 25 degrees C results from the contribution of the polar head to the overall heat of demicellization. Calorimetric studies of other series of amphiphiles will have to be conducted to test whether the latter conclusion is general.
Seebacher, Frank; Elsey, Ruth M; Trosclair, Phillip L
2003-01-01
Regulation of body temperature may increase fitness of animals by ensuring that biochemical and physiological processes proceed at an optimal rate. The validity of current methods of testing whether or not thermoregulation in reptiles occurs is often limited to very small species that have near zero heat capacity. The aim of this study was to develop a method that allows estimation of body temperature null distributions of large reptiles and to investigate seasonal thermoregulation in the American alligator (Alligator mississippiensis). Continuous body temperature records of wild alligators were obtained from implanted dataloggers in winter (n=7, mass range: 1.6-53.6 kg) and summer (n=7, mass range: 1.9-54.5 kg). Body temperature null distributions were calculated by randomising behavioural postures, thereby randomly altering relative animal surface areas exposed to different avenues of heat transfer. Core body temperatures were predicted by calculations of transient heat transfer by conduction and blood flow. Alligator body temperatures follow regular oscillations during the day. Occasionally, body temperature steadied during the day to fall within a relatively narrow range. Rather than indicating shuttling thermoregulation, however, this pattern could be predicted from random movements. Average daily body temperature increases with body mass in winter but not in summer. Daily amplitudes of body temperature decrease with increasing body mass in summer but not in winter. These patterns result from differential exposure to heat transfer mechanisms at different seasons. In summer, alligators are significantly cooler than predictions for a randomly moving animal, and the reverse is the case in winter. Theoretical predictions show, however, that alligators can be warmer in winter if they maximised their sun exposure. We concluded that alligators may not rely exclusively on regulation of body temperature but that they may also acclimatise biochemically to seasonally
Vibrational mode analysis and heat capacity calculation of K2SiSi3O9-wadeite
NASA Astrophysics Data System (ADS)
Chang, Linlin; Liu, Xi; Liu, Hong; Kojitani, Hiroshi; Wang, Sicheng
2013-07-01
The phonon dispersions and vibrational density of state (VDoS) of the K2SiSi3O9-wadeite (Wd) have been calculated by the first-principles method using density functional perturbation theory. The vibrational frequencies at the Brillouin zone center are in good correspondence with the Raman and infrared experimental data. The calculated VDoS was then used in conjunction with a quasi-harmonic approximation to compute the isobaric heat capacity ( C P ) and vibrational entropy (S_{298}0), yielding C P ( T) = 469.4(6) - 2.90(2) × 103 T -0.5 - 9.5(2) × 106 T -2 + 1.36(3) × 109 T -3 for the T range of 298-1,000 K and S_{298}0 = 250.4 J mol-1 K-1. In comparison, these thermodynamic properties were calculated by a second method, the classic Kieffer's lattice vibrational model. On the basis of the vibrational mode analysis facilitated by the first-principles simulation result, we developed a new Kieffer's model for the Wd phase. This new Kieffer's model yielded C P ( T) = 475.9(6) - 3.15(2) × 103 T -0.5 - 8.8(2) × 106 T -2 + 1.31(3) × 109 T -3 for the T range of 298-1,000 K and S_{298}0 = 249.5(40) J mol-1 K-1, which are in good agreement both with the results from our first method containing the component of the first-principles calculation and with some calorimetric measurements in the literature.
Oliynyk, Vitaliy; Jäger, Markus; Heimburg, Thomas; Buckin, Vitaly; Kaatze, Udo
2008-05-01
An experimental study of phosphocholine membranes made from one lipid, from mixtures of DPPC and DLPC, and also from lipids and small amounts of alamethicin is presented. We used atomic force microscopy to investigate the spatial organization and structure of lipid domains and also of the defects induced by the peptide. Alamethicin was found to alter the state of lipids in the gel state in a way that domains of fluid lipids are formed close to the defects. Differential calorimetry revealed phase characteristics of the lipid mixtures and the effect of small amounts of alamethicin on the phase behavior. It was also shown that the sound velocity profiles of the membranes suspensions can be well calculated from the heat capacity traces of the samples. This result confirms the correlation between the mechanical properties and the specific heat of membrane systems.
Extruded scintillator for the calorimetry applications
Dyshkant, A.; Rykalin, V.; Pla-Dalmau, A.; Beznosko, D.; /SUNY, Stony Brook
2006-08-01
An extrusion line has been installed and successfully operated at FNAL (Fermi National Accelerator Laboratory) in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new Facility will serve to further develop and improve extruded plastic scintillator. Recently progress has been made in producing co-extruded plastic scintillator, thus increasing the potential HEP applications of this Facility. The current R&D work with extruded and co-extruded plastic scintillator for a potential ALICE upgrade, the ILC calorimetry program and the MINERvA experiment show the attractiveness of the chosen strategy for future experiments and calorimetry. We extensively discuss extruded and co-extruded plastic scintillator in calorimetry in synergy with new Solid State Photomultipliers. The characteristics of extruded and co-extruded plastic scintillator will be presented here as well as results with non-traditional photo read-out.
Extruded scintillator for the Calorimetry applications
NASA Astrophysics Data System (ADS)
Dyshkant, A.; Rykalin, V.; Pla-Dalmau, A.; Beznosko, D.
2006-10-01
An extrusion line has been installed and successfully operated at FNAL (Fermi National Accelerator Laboratory) in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new Facility will serve to further develop and improve extruded plastic scintillator. Recently progress has been made in producing co-extruded plastic scintillator, thus increasing the potential HEP applications of this Facility. The current R&D work with extruded and co-extruded plastic scintillator for a potential ALICE upgrade, the ILC calorimetry program and the MINERvA experiment show the attractiveness of the chosen strategy for future experiments and calorimetry. We extensively discuss extruded and co-extruded plastic scintillator in calorimetry in synergy with new Solid State Photomultipliers. The characteristics of extruded and co-extruded plastic scintillator will be presented here as well as results with non-traditional photo read-out.
NASA Astrophysics Data System (ADS)
Toner, J. D.; Catling, D. C.
2016-05-01
Perchlorate salts found on Mars are extremely hygroscopic and form low eutectic temperature aqueous solutions, which could allow liquid water to exist on Mars despite cold and dry conditions. The formation, dynamics, and potential habitability of perchlorate salt solutions can be broadly understood in terms of water activity. Water activity controls condensation and evaporation of water vapor in brines, deliquescence and efflorescence of crystalline salts, and ice formation during freezing. Furthermore, water activity is a basic parameter defining the habitability of aqueous solutions. Despite the importance of water activity, its value in perchlorate solutions has only been measured at 298.15 K and at the freezing point of water. To address this lack of data, we have determined water activities in NaClO4, Ca(ClO4)2, and Mg(ClO4)2 solutions using experimental heat capacities measured by Differential Scanning Calorimetry. Our results include concentrations up to near-saturation and temperatures ranging from 298.15 to 178 K. We find that water activities in NaClO4 solutions increase with decreasing temperature, by as much as 0.25 aw from 298.15 to 178 K. Consequently, aw reaches ∼0.6-0.7 even for concentrations up to 15 molal NaClO4 below 200 K. In contrast, water activities in Ca(ClO4)2 and Mg(ClO4)2 solutions generally decrease with decreasing temperature. The temperature dependence of water activity indicates that low-temperature NaClO4 solutions will evaporate and deliquesce at higher relative humidity, crystallize ice at higher temperature, and potentially be more habitable for life (at least in terms of water activity) compared to solutions at 298.15 K. The opposite effects occur in Ca(ClO4)2 and Mg(ClO4)2 solutions.
Adiabatic heating in impulsive solar flares
NASA Technical Reports Server (NTRS)
Maetzler, C.; Bai, T.; Crannell, C. J.; Frost, K. J.
1977-01-01
The dynamic X-ray spectra of two simple, impulsive solar flares are examined together with H alpha, microwave and meter wave radio observations. X-ray spectra of both events were characteristic of thermal bremsstrahlung from single temperature plasmas. The symmetry between rise and fall was found to hold for the temperature and emission measure. The relationship between temperature and emission measure was that of an adiabatic compression followed by adiabatic expansion; the adiabatic index of 5/3 indicated that the electron distribution remained isotropic. Observations in H alpha provided further evidence for compressive energy transfer.
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.
NASA Astrophysics Data System (ADS)
Liu, Z. J.; Song, T.; Sun, X. W.; Ma, Q.; Wang, T.; Guo, Y.
2017-03-01
Thermal expansion coefficient, heat capacity, and Grüneisen parameter of iridium phosphide Ir2P are reported by means of quasi-harmonic Debye model for the first time in the current study. This model combines with first-principles calculations within generalized gradient approximation using pseudopotentials and a plane-wave basis in the framework of density functional theory, and it takes into account the phononic effects within the quasi-harmonic approximation. The Debye temperature as a function of volume, the Grüneisen parameter, thermal expansion coefficient, constant-volume and constant-pressure heat capacities, and entropy on the temperature T are also successfully obtained. All the thermodynamic properties of Ir2P in the whole pressure range from 0 to 100 GPa and temperature range from 0 to 3000 K are summarized and discussed in detail.
NASA Astrophysics Data System (ADS)
Yong, W.; Dachs, E.; Withers, A. C.; Essene, E. J.
2007-12-01
The low-temperature heat capacity (Cp) of γ-Fe2SiO4 was measured between 5 and 303 K using the heat capacity option of a physical properties measurement system (PPMS). Fayalite powder was used as the starting material to synthesize the γ-Fe2SiO4 at 8.5 GPa and 1273 K by a 1,000-ton Walker-type multi-anvil device at the university of Minnesota. The heat capacity data were measured at more than 100 different temperatures with both logarithmic spacing and linear spacing. The measured heat capacity data show a broad lambda-transition at 11.8 K, probably related to a paramagnetic-antiferromagnetic transition just like the 65 K transition in fayalite. The difference in the Cp between fayalite and γ-Fe2SiO4 is reduced as the temperature increases in the range of 50-300 K. The Cp and entropy of γ- Fe2SiO4 at standard temperature and pressure (S°298) are 131.1±0.6 J mol-1K-1 and 140.2±0.4 J mol-1K-1, respectively. The Gibbs free energy at standard pressure and temperature (G°f,298) is calculated to be 1,369.3±2.7 J mol-1 based on the new entropy data. Based on current thermodynamic data, the calculated phase boundary for the fayalite - γ- Fe2SiO4 transition at high temperatures and pressures is consistent with the results of previous experimental studies.
Monte Carlo studies of uranium calorimetry
Brau, J.; Hargis, H.J.; Gabriel, T.A.; Bishop, B.L.
1985-01-01
Detailed Monte Carlo calculations of uranium calorimetry are presented which reveal a significant difference in the responses of liquid argon and plastic scintillator in uranium calorimeters. Due to saturation effects, neutrons from the uranium are found to contribute only weakly to the liquid argon signal. Electromagnetic sampling inefficiencies are significant and contribute substantially to compensation in both systems. 17 references.
Isothermal Titration Calorimetry in the Student Laboratory
ERIC Educational Resources Information Center
Wadso, Lars; Li, Yujing; Li, Xi
2011-01-01
Isothermal titration calorimetry (ITC) is the measurement of the heat produced by the stepwise addition of one substance to another. It is a common experimental technique, for example, in pharmaceutical science, to measure equilibrium constants and reaction enthalpies. We describe a stirring device and an injection pump that can be used with a…
Final Technical Report CMS fast optical calorimetry
Winn, David R.
2012-07-12
This is the final report of CMS FAST OPTICAL CALORIMETRY, a grant to Fairfield University for development, construction, installation and operation of the forward calorimeter on CMS, and for upgrades of the forward and endcap calorimeters for higher luminosity and radiation damage amelioration.
Calculation of Temperature Rise in Calorimetry.
ERIC Educational Resources Information Center
Canagaratna, Sebastian G.; Witt, Jerry
1988-01-01
Gives a simple but fuller account of the basis for accurately calculating temperature rise in calorimetry. Points out some misconceptions regarding these calculations. Describes two basic methods, the extrapolation to zero time and the equal area method. Discusses the theoretical basis of each and their underlying assumptions. (CW)
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.
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.
Experimental demonstration of composite adiabatic passage
NASA Astrophysics Data System (ADS)
Schraft, Daniel; Halfmann, Thomas; Genov, Genko T.; Vitanov, Nikolay V.
2013-12-01
We report an experimental demonstration of composite adiabatic passage (CAP) for robust and efficient manipulation of two-level systems. The technique represents a altered version of rapid adiabatic passage (RAP), driven by composite sequences of radiation pulses with appropriately chosen phases. We implement CAP with radio-frequency pulses to invert (i.e., to rephase) optically prepared spin coherences in a Pr3+:Y2SiO5 crystal. We perform systematic investigations of the efficiency of CAP and compare the results with conventional π pulses and RAP. The data clearly demonstrate the superior features of CAP with regard to robustness and efficiency, even under conditions of weakly fulfilled adiabaticity. The experimental demonstration of composite sequences to support adiabatic passage is of significant relevance whenever a high efficiency or robustness of coherent excitation processes need to be maintained, e.g., as required in quantum information technology.
Adiabatic Quantum Search in Open Systems.
Wild, Dominik S; Gopalakrishnan, Sarang; Knap, Michael; Yao, Norman Y; Lukin, Mikhail D
2016-10-07
Adiabatic quantum algorithms represent a promising approach to universal quantum computation. In isolated systems, a key limitation to such algorithms is the presence of avoided level crossings, where gaps become extremely small. In open quantum systems, the fundamental robustness of adiabatic algorithms remains unresolved. Here, we study the dynamics near an avoided level crossing associated with the adiabatic quantum search algorithm, when the system is coupled to a generic environment. At zero temperature, we find that the algorithm remains scalable provided the noise spectral density of the environment decays sufficiently fast at low frequencies. By contrast, higher order scattering processes render the algorithm inefficient at any finite temperature regardless of the spectral density, implying that no quantum speedup can be achieved. Extensions and implications for other adiabatic quantum algorithms will be discussed.
Adiabatic Quantum Search in Open Systems
NASA Astrophysics Data System (ADS)
Wild, Dominik S.; Gopalakrishnan, Sarang; Knap, Michael; Yao, Norman Y.; Lukin, Mikhail D.
2016-10-01
Adiabatic quantum algorithms represent a promising approach to universal quantum computation. In isolated systems, a key limitation to such algorithms is the presence of avoided level crossings, where gaps become extremely small. In open quantum systems, the fundamental robustness of adiabatic algorithms remains unresolved. Here, we study the dynamics near an avoided level crossing associated with the adiabatic quantum search algorithm, when the system is coupled to a generic environment. At zero temperature, we find that the algorithm remains scalable provided the noise spectral density of the environment decays sufficiently fast at low frequencies. By contrast, higher order scattering processes render the algorithm inefficient at any finite temperature regardless of the spectral density, implying that no quantum speedup can be achieved. Extensions and implications for other adiabatic quantum algorithms will be discussed.
General conditions for quantum adiabatic evolution
Comparat, Daniel
2009-07-15
Adiabaticity occurs when, during its evolution, a physical system remains in the instantaneous eigenstate of the Hamiltonian. Unfortunately, existing results, such as the quantum adiabatic theorem based on a slow down evolution [H({epsilon}t),{epsilon}{yields}0], are insufficient to describe an evolution driven by the Hamiltonian H(t) itself. Here we derive general criteria and exact bounds, for the state and its phase, ensuring an adiabatic evolution for any Hamiltonian H(t). As a corollary, we demonstrate that the commonly used condition of a slow Hamiltonian variation rate, compared to the spectral gap, is indeed sufficient to ensure adiabaticity but only when the Hamiltonian is real and nonoscillating (for instance, containing exponential or polynomial but no sinusoidal functions)
Adiabatic limits on Riemannian Heisenberg manifolds
Yakovlev, A A
2008-02-28
An asymptotic formula is obtained for the distribution function of the spectrum of the Laplace operator, in the adiabatic limit for the foliation defined by the orbits of an invariant flow on a compact Riemannian Heisenberg manifold. Bibliography: 21 titles.
Simulation of periodically focused, adiabatic thermal beams
Chen, C.; Akylas, T. R.; Barton, T. J.; Field, D. M.; Lang, K. M.; Mok, R. V.
2012-12-21
Self-consistent particle-in-cell simulations are performed to verify earlier theoretical predictions of adiabatic thermal beams in a periodic solenoidal magnetic focusing field [K.R. Samokhvalova, J. Zhou and C. Chen, Phys. Plasma 14, 103102 (2007); J. Zhou, K.R. Samokhvalova and C. Chen, Phys. Plasma 15, 023102 (2008)]. In particular, results are obtained for adiabatic thermal beams that do not rotate in the Larmor frame. For such beams, the theoretical predictions of the rms beam envelope, the conservations of the rms thermal emittances, the adiabatic equation of state, and the Debye length are verified in the simulations. Furthermore, the adiabatic thermal beam is found be stable in the parameter regime where the simulations are performed.
Symmetry of the Adiabatic Condition in the Piston Problem
ERIC Educational Resources Information Center
Anacleto, Joaquim; Ferreira, J. M.
2011-01-01
This study addresses a controversial issue in the adiabatic piston problem, namely that of the piston being adiabatic when it is fixed but no longer so when it can move freely. It is shown that this apparent contradiction arises from the usual definition of adiabatic condition. The issue is addressed here by requiring the adiabatic condition to be…
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.
A conceptual approach for noncontact calorimetry in space
NASA Technical Reports Server (NTRS)
Fecht, H. J.; Johnson, W. L.
1991-01-01
A concept is developed and described which allows to measure the heat capacity and the effective thermal conductivity of stable and undercooled liquid metals and alloys in an electromagnetic levitation apparatus. A proposal is made to use an ac pulse heating method which is used nowadays as a standard technique for precision measurement of low-temperature heat capacities. The ideal process parameters, including the drop diameter D, temperature T, and frequency of measurement omega, can be optimized when the following relations hold for the external and internal relaxation time constants tau-1 and tau-2, respectively: omega(tau-1) greater than 10 and omega(tau-2) less than 0.1. Then, heat capacity data can be obtained with an accuracy of better than 1 percent with D about 5 to 10 mm, T between 1200 and 1800 K, and omega between 0.1 and 1 Hz for typical metals and alloys.
A novel optical calorimetry dosimetry approach applied to an HDR Brachytherapy source
NASA Astrophysics Data System (ADS)
Cavan, A.; Meyer, J.
2013-06-01
The technique of Digital Holographic Interferometry (DHI) is applied to the measurement of radiation absorbed dose distribution in water. An optical interferometer has been developed that captures the small variations in the refractive index of water due to the radiation induced temperature increase ΔT. The absorbed dose D is then determined with high temporal and spatial resolution using the calorimetric relation D=cΔT (where c is the specific heat capacity of water). The method is capable of time resolving 3D spatial calorimetry. As a proof-of-principle of the approach, a prototype DHI dosimeter was applied to the measurement of absorbed dose from a High Dose Rate (HDR) Brachytherapy source. Initial results are in agreement with modelled doses from the Brachyvision treatment planning system, demonstrating the viability of the system for high dose rate applications. Future work will focus on applying corrections for heat diffusion and geometric effects. The method has potential to contribute to the dosimetry of diverse high dose rate applications which require high spatial resolution such as microbeam radiotherapy (MRT) or small field proton beam dosimetry but may potentially also be useful for interface dosimetry.
Assessment of total efficiency in adiabatic engines
NASA Astrophysics Data System (ADS)
Mitianiec, W.
2016-09-01
The paper presents influence of ceramic coating in all surfaces of the combustion chamber of SI four-stroke engine on working parameters mainly on heat balance and total efficiency. Three cases of engine were considered: standard without ceramic coating, fully adiabatic combustion chamber and engine with different thickness of ceramic coating. Consideration of adiabatic or semi-adiabatic engine was connected with mathematical modelling of heat transfer from the cylinder gas to the cooling medium. This model takes into account changeable convection coefficient based on the experimental formulas of Woschni, heat conductivity of multi-layer walls and also small effect of radiation in SI engines. The simulation model was elaborated with full heat transfer to the cooling medium and unsteady gas flow in the engine intake and exhaust systems. The computer program taking into account 0D model of engine processes in the cylinder and 1D model of gas flow was elaborated for determination of many basic engine thermodynamic parameters for Suzuki DR-Z400S 400 cc SI engine. The paper presents calculation results of influence of the ceramic coating thickness on indicated pressure, specific fuel consumption, cooling and exhaust heat losses. Next it were presented comparisons of effective power, heat losses in the cooling and exhaust systems, total efficiency in function of engine rotational speed and also comparison of temperature inside the cylinder for standard, semi-adiabatic and full adiabatic engine. On the basis of the achieved results it was found higher total efficiency of adiabatic engines at 2500 rpm from 27% for standard engine to 37% for full adiabatic engine.
Foward Calorimetry in ALICE at LHC
NASA Astrophysics Data System (ADS)
Chujo, Tatsuya; Alice Focal Collaboration
2014-09-01
We present an upgrade proposal for calorimetry in the forward direction, FOCAL, to measure direct photons in η = 3 . 3 - 5 . 3 in ALICE at the Large Hadron Collider (LHC). We suggest to use an electromagnetic calorimeter based on the novel technology of silicon sensors with W absorbers for photons, together with a conventional hadron calorimeter for jet measurements and photon isolation. The current status of the FOCAL R&D project will be presented.
Overabundance of carbon monoxide in calorimetry tests
Ree, F.H.; Pitz, W.J.; Thiel, M. van; Souers, P.C.
1996-04-04
The amount of carbon monoxide recovered from calorimetry tests of high explosives is far larger than the amount predicted by equilibrium calculations. The present kinetics study of PETN [(nitro(oxy)methyl]-propanediol dinitrate) has revealed that the cooling of the calorimetry bomb after detonation of a PETN sample sufficiently slows those reactions that would otherwise lead to equilibrium so that these reactions are effectively frozen in the time scale of recovery of detonation products. Among these reactions, those that can create CH{sub 4} are the most important ones. Their rates are generally slow at all temperatures relevant to calorimetry tests. This and the slowing down of a reaction, CO + H{sub 2}O {yields} H{sub 2} + CO{sub 2} at temperatures below 1500 K are the main caus of the freeze-out of CO. A possible slow rate of the soot formation (i.e., condensed carbon) is not responsible for it. The sensitivity of the present result to the cooling rate of the detonation products and to free radicals is also examined. 10 refs., 5 figs., 2 tabs.
Izutani, Yusuke; Kanaori, Kenji; Oda, Masayuki
2014-06-17
The structural properties of glycyrrhizic acid, a sweet-tasting constituent of Glycyrrhiza glabra, and its interaction with cyclodextrins were analyzed using dynamic light scattering, isothermal titration calorimetry, and NMR. The dynamic light scattering and NMR studies showed that glycyrrhizic acid forms a water-soluble aggregate that disperses upon the addition of γ-cyclodextrin. The high sweetness of glycyrrhizic acid can be closely correlated with this aggregation, because the multimers of glycyrrhizic acid can simultaneously bind to the sweet taste receptors on the human tongue. The isothermal titration calorimetry experiments demonstrated that γ-cyclodextrin binds to glycyrrhizic acid more strongly than β-cyclodextrin, however, both reactions are accompanied by a favorable change in binding entropy. Considering the large negative change in heat capacity that is observed during the binding of γ-cyclodextrin, the main driving force for the binding is hydrophobic interactions with dehydration, which is typical for inclusion complex. NMR experiments showed that γ-cyclodextrin interacts with the central part of the aglycone moiety, not the glucuronic acid moieties, resulting in high binding affinity. It should also be noted that the two distinct complexes of glycyrrhizic acid with γ-cyclodextrin would exist in aqueous solution.
Timmer, Christine M; Michmerhuizen, Nicole L; Witte, Amanda B; Van Winkle, Margaret; Zhou, Dejian; Sinniah, Kumar
2014-02-20
The binding of insulin to the G-quadruplexes formed by the consensus sequence of the insulin-linked polymorphic region (ILPR) was investigated with differential scanning calorimetry (DSC) and isothermal titration calorimetry (ITC). The thermal denaturation temperature of insulin was increased by almost 4 °C upon binding to ILPR G-quadruplex DNA as determined by DSC. The thermodynamic parameters (K(D), ΔH, ΔG, and ΔS) of the insulin-G-quadruplex complex were further investigated by temperature-dependent ITC measurement over the range of 10-37 °C. The binding of insulin to the ILPR consensus sequence displays micromolar affinity in phosphate buffer at pH 7.4, which is mainly driven by entropic factors below 25 °C but by enthalpic terms above 30 °C. The interaction was also examined in several different buffers, and results showed that the observed ΔH is dependent on the ionization enthalpy of the buffer used. This indicates proton release upon the binding of G-quadruplex DNA to insulin. Additionally, the large negative change in heat capacity for this interaction may be associated with the dominant hydrophobicity of the amino acid sequence of insulin's β subunit, which is known to bind to the ILPR G-quadruplex DNA.
2013-01-01
In this study, different nanofluids with phase change behavior were developed by mixing a molten salt base fluid (selected as phase change material) with nanoparticles using the direct-synthesis method. The thermal properties of the nanofluids obtained were investigated. These nanofluids can be used in concentrating solar plants with a reduction of storage material if an improvement in the specific heat is achieved. The base salt mixture was a NaNO3-KNO3 (60:40 ratio) binary salt. The nanoparticles used were silica (SiO2), alumina (Al2O3), titania (TiO2), and a mix of silica-alumina (SiO2-Al2O3). Three weight fractions were evaluated: 0.5, 1.0, and 1.5 wt.%. Each nanofluid was prepared in water solution, sonicated, and evaporated. Measurements on thermophysical properties were performed by differential scanning calorimetry analysis and the dispersion of the nanoparticles was analyzed by scanning electron microscopy (SEM). The results obtained show that the addition of 1.0 wt.% of nanoparticles to the base salt increases the specific heat of 15% to 57% in the solid phase and of 1% to 22% in the liquid phase. In particular, this research shows that the addition of silica-alumina nanoparticles has a significant potential for enhancing the thermal storage characteristics of the NaNO3-KNO3 binary salt. These results deviated from the predictions of the theoretical model used. SEM suggests a greater interaction between these nanoparticles and the salt. PMID:24168168
Chieruzzi, Manila; Cerritelli, Gian F; Miliozzi, Adio; Kenny, José M
2013-10-29
In this study, different nanofluids with phase change behavior were developed by mixing a molten salt base fluid (selected as phase change material) with nanoparticles using the direct-synthesis method. The thermal properties of the nanofluids obtained were investigated. These nanofluids can be used in concentrating solar plants with a reduction of storage material if an improvement in the specific heat is achieved. The base salt mixture was a NaNO3-KNO3 (60:40 ratio) binary salt. The nanoparticles used were silica (SiO2), alumina (Al2O3), titania (TiO2), and a mix of silica-alumina (SiO2-Al2O3). Three weight fractions were evaluated: 0.5, 1.0, and 1.5 wt.%. Each nanofluid was prepared in water solution, sonicated, and evaporated. Measurements on thermophysical properties were performed by differential scanning calorimetry analysis and the dispersion of the nanoparticles was analyzed by scanning electron microscopy (SEM). The results obtained show that the addition of 1.0 wt.% of nanoparticles to the base salt increases the specific heat of 15% to 57% in the solid phase and of 1% to 22% in the liquid phase. In particular, this research shows that the addition of silica-alumina nanoparticles has a significant potential for enhancing the thermal storage characteristics of the NaNO3-KNO3 binary salt. These results deviated from the predictions of the theoretical model used. SEM suggests a greater interaction between these nanoparticles and the salt.
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.
Adiabatic optimization versus diffusion Monte Carlo methods
NASA Astrophysics Data System (ADS)
Jarret, Michael; Jordan, Stephen P.; Lackey, Brad
2016-10-01
Most experimental and theoretical studies of adiabatic optimization use stoquastic Hamiltonians, whose ground states are expressible using only real nonnegative amplitudes. This raises a question as to whether classical Monte Carlo methods can simulate stoquastic adiabatic algorithms with polynomial overhead. Here we analyze diffusion Monte Carlo algorithms. We argue that, based on differences between L1 and L2 normalized states, these algorithms suffer from certain obstructions preventing them from efficiently simulating stoquastic adiabatic evolution in generality. In practice however, we obtain good performance by introducing a method that we call Substochastic Monte Carlo. In fact, our simulations are good classical optimization algorithms in their own right, competitive with the best previously known heuristic solvers for MAX-k -SAT at k =2 ,3 ,4 .
Nonadiabatic exchange dynamics during adiabatic frequency sweeps.
Barbara, Thomas M
2016-04-01
A Bloch equation analysis that includes relaxation and exchange effects during an adiabatic frequency swept pulse is presented. For a large class of sweeps, relaxation can be incorporated using simple first order perturbation theory. For anisochronous exchange, new expressions are derived for exchange augmented rotating frame relaxation. For isochronous exchange between sites with distinct relaxation rate constants outside the extreme narrowing limit, simple criteria for adiabatic exchange are derived and demonstrate that frequency sweeps commonly in use may not be adiabatic with regard to exchange unless the exchange rates are much larger than the relaxation rates. Otherwise, accurate assessment of the sensitivity to exchange dynamics will require numerical integration of the rate equations. Examples of this situation are given for experimentally relevant parameters believed to hold for in-vivo tissue. These results are of significance in the study of exchange induced contrast in magnetic resonance imaging.
Complexity of the Quantum Adiabatic Algorithm
NASA Technical Reports Server (NTRS)
Hen, Itay
2013-01-01
The Quantum Adiabatic Algorithm (QAA) has been proposed as a mechanism for efficiently solving optimization problems on a quantum computer. Since adiabatic computation is analog in nature and does not require the design and use of quantum gates, it can be thought of as a simpler and perhaps more profound method for performing quantum computations that might also be easier to implement experimentally. While these features have generated substantial research in QAA, to date there is still a lack of solid evidence that the algorithm can outperform classical optimization algorithms.
On black hole spectroscopy via adiabatic invariance
NASA Astrophysics Data System (ADS)
Jiang, Qing-Quan; Han, Yan
2012-12-01
In this Letter, we obtain the black hole spectroscopy by combining the black hole property of adiabaticity and the oscillating velocity of the black hole horizon. This velocity is obtained in the tunneling framework. In particular, we declare, if requiring canonical invariance, the adiabatic invariant quantity should be of the covariant form Iadia = ∮pi dqi. Using it, the horizon area of a Schwarzschild black hole is quantized independently of the choice of coordinates, with an equally spaced spectroscopy always given by ΔA = 8 π lp2 in the Schwarzschild and Painlevé coordinates.
On adiabatic invariant in generalized Galileon theories
Ema, Yohei; Jinno, Ryusuke; Nakayama, Kazunori; Mukaida, Kyohei E-mail: jinno@hep-th.phys.s.u-tokyo.ac.jp E-mail: kazunori@hep-th.phys.s.u-tokyo.ac.jp
2015-10-01
We consider background dynamics of generalized Galileon theories in the context of inflation, where gravity and inflaton are non-minimally coupled to each other. In the inflaton oscillation regime, the Hubble parameter and energy density oscillate violently in many cases, in contrast to the Einstein gravity with minimally coupled inflaton. However, we find that there is an adiabatic invariant in the inflaton oscillation regime in any generalized Galileon theory. This adiabatic invariant is useful in estimating the expansion law of the universe and also the particle production rate due to the oscillation of the Hubble parameter.
Spontaneous emission in stimulated Raman adiabatic passage
Ivanov, P. A.; Vitanov, N. V.; Bergmann, K.
2005-11-15
This work explores the effect of spontaneous emission on the population transfer efficiency in stimulated Raman adiabatic passage (STIRAP). The approach uses adiabatic elimination of weakly coupled density matrix elements in the Liouville equation, from which a very accurate analytic approximation is derived. The loss of population transfer efficiency is found to decrease exponentially with the factor {omega}{sub 0}{sup 2}/{gamma}, where {gamma} is the spontaneous emission rate and {omega}{sub 0} is the peak Rabi frequency. The transfer efficiency increases with the pulse delay and reaches a steady value. For large pulse delay and large spontaneous emission rate STIRAP degenerates into optical pumping.
Adiabatic Hyperspherical Analysis of Realistic Nuclear Potentials
NASA Astrophysics Data System (ADS)
Daily, K. M.; Kievsky, Alejandro; Greene, Chris H.
2015-12-01
Using the hyperspherical adiabatic method with the realistic nuclear potentials Argonne V14, Argonne V18, and Argonne V18 with the Urbana IX three-body potential, we calculate the adiabatic potentials and the triton bound state energies. We find that a discrete variable representation with the slow variable discretization method along the hyperradial degree of freedom results in energies consistent with the literature. However, using a Laguerre basis results in missing energy, even when extrapolated to an infinite number of basis functions and channels. We do not include the isospin T = 3/2 contribution in our analysis.
Adiabatic cluster-state quantum computing
Bacon, Dave; Flammia, Steven T.
2010-09-15
Models of quantum computation (QC) are important because they change the physical requirements for achieving universal QC. For example, one-way QC requires the preparation of an entangled ''cluster'' state, followed by adaptive measurement on this state, a set of requirements which is different from the standard quantum-circuit model. Here we introduce a model based on one-way QC but without measurements (except for the final readout), instead using adiabatic deformation of a Hamiltonian whose initial ground state is the cluster state. Our results could help increase the feasibility of adiabatic schemes by using tools from one-way QC.
Markovian quantum master equation beyond adiabatic regime.
Yamaguchi, Makoto; Yuge, Tatsuro; Ogawa, Tetsuo
2017-01-01
By introducing a temporal change time scale τ_{A}(t) for the time-dependent system Hamiltonian, a general formulation of the Markovian quantum master equation is given to go well beyond the adiabatic regime. In appropriate situations, the framework is well justified even if τ_{A}(t) is faster than the decay time scale of the bath correlation function. An application to the dissipative Landau-Zener model demonstrates this general result. The findings are applicable to a wide range of fields, providing a basis for quantum control beyond the adiabatic regime.
Markovian quantum master equation beyond adiabatic regime
NASA Astrophysics Data System (ADS)
Yamaguchi, Makoto; Yuge, Tatsuro; Ogawa, Tetsuo
2017-01-01
By introducing a temporal change time scale τA(t ) for the time-dependent system Hamiltonian, a general formulation of the Markovian quantum master equation is given to go well beyond the adiabatic regime. In appropriate situations, the framework is well justified even if τA(t ) is faster than the decay time scale of the bath correlation function. An application to the dissipative Landau-Zener model demonstrates this general result. The findings are applicable to a wide range of fields, providing a basis for quantum control beyond the adiabatic regime.
NASA Astrophysics Data System (ADS)
Kalnačs, J.; Grehovs, V.; Mežinskis, G.; Bidermanis, L.
2013-10-01
Differential scanning calorimetry was carried out to determine the heat capacity (Cp) of the high temperature resistant ceramic materials to be used as protective coatings for stainless steel tubes of parabolic trough solar collectors in concentrated solar power (CSP) systems. The Cp(T) measurements and calculations were performed at continuous scanning in the temperature range 20-800 °C. In the work, calibration curves have been derived for conversion of measuring units from mcV into mW. To achieve a better repeatability of measurements, methods for stabilization of the thermal contact between the sample-containing vessel and the probe have been developed. The Cp(T) dependence was obtained for different ceramic materials. Rakstā izklāstīta izstrādātā metodika keramikas un emalju siltumietilpības noteikšanai pēc diferenciālās skenējošās kalorimetrijas mērījumiem. Parādīta virkne traucējošo faktoru kalibrēšanas līknes un mērījumu veikšanai, piedāvātas metodes to samazināšanai vai novēršanai, precīzāku rezultātu ieguvei. Noteikta siltumietilpības atkarība no temperatūras virknei emalju, kas var tikt izmantotas saules siltuma kolektoros, kā aizsargpārklājumi. Parādīta siltumietilpības noteikšanas atkārtojamības atkarība no siltuma kontakta. Izstrādāta metode termiskā kontakta stabilizācijai. Virknei emalju noteikta siltumietilpības atkarība no temperatūras diapazonā 20 - 800°C.
Calorimetry of the CMD-3 detector
NASA Astrophysics Data System (ADS)
Shebalin, V. E.; Akhmetshin, R. R.; Anisenkov, A. V.; Aulchenko, V. M.; Bashtovoy, N. S.; Epifanov, D. A.; Epshteyn, L. B.; Erofeev, A. L.; Grebenuk, A. A.; Grigoriev, D. N.; Ignatov, F. V.; Kazanin, V. F.; Kovalenko, O. A.; Kozyrev, A. N.; Kuzmenko, A. E.; Kuzmin, A. S.; Logashenko, I. B.; Mikhailov, K. Yu.; Okhapkin, V. S.; Razuvaev, G. P.; Ruban, A. A.; Shwartz, B. A.; Titov, V. M.; Talyshev, A. A.; Yudin, Yu. V.
2016-07-01
CMD-3 is a general purpose detector designed to study e+e- annihilation into hadrons. It is mounted at VEPP-2000 collider which operates in the wide energy range, E c . m . s = 0.32 - 2 GeV. The calorimetry at the detector is based on three subsystems: closest to the beam pipe barrel Liquid Xenon calorimeter, outer barrel calorimeter based on CsI scintillation crystals and the endcap calorimeter made of BGO scintillation crystals. We describe the structure of the calorimeters, their electronics and the energy calibration procedures.
From biochemistry to physiology: the calorimetry connection.
Hansen, Lee D; Russell, Donald J; Choma, Christin T
2007-01-01
This article provides guidelines for selecting optimal calorimetric instrumentation for applications in biochemistry and biophysics. Applications include determining thermodynamics of interactions in non-covalently bonded structures, and determining function through measurements of enzyme kinetics and metabolic rates. Specific examples illustrating current capabilities and methods in biological calorimetry are provided. Commercially available calorimeters are categorized by application and by instrument characteristics (isothermal or temperature-scanning, reaction vessel volume, heat rate detection limit, fixed or removable reaction vessels, etc.). Advantages and limitations of commercially available calorimeters are listed for each application in biochemistry, biophysics, and physiology.
Determining enzyme kinetics via isothermal titration calorimetry.
Demarse, Neil A; Killian, Marie C; Hansen, Lee D; Quinn, Colette F
2013-01-01
Isothermal titration calorimetry (ITC) has emerged as a powerful tool for determining the thermodynamic properties of chemical or physical equilibria such as protein-protein, ligand-receptor, and protein-DNA binding interactions. The utility of ITC for determining kinetic information, however, has not been fully recognized. Methods for collecting and analyzing data on enzyme kinetics are discussed here. The step-by-step process of converting the raw heat output rate into the kinetic parameters of the Michaelis-Menten equation is explicitly stated. The hydrolysis of sucrose by invertase is used to demonstrate the capability of the instrument and method.
Uniformity requirements in CMS hadron calorimetry
Green, D.
1996-02-01
Practical considerations of calorimeter systems require a specification of the allowed manufacturing tolerances. The tightness of these requirements directly makes an impact on the assembly costs of the calorimeter. For that reason, a precise and well defined set of criteria is mandatory. In addition, the intrinsic limitations of hadron calorimetry define the level of accuracy needed in the manufacture of such devices. Therefore, considerations of the limitations on energy measurement accuracy due to Physics should define the needed level of effort to produce a uniform calorimetric device.
Heat capacity of the site-diluted spin dimer system Ba₃(Mn_{1-x}V_{x})₂O₈
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(Mn_{1-x}V_{x})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.
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.
Adiabatic Compression in a Fire Syringe.
ERIC Educational Resources Information Center
Hayn, Carl H.; Baird, Scott C.
1985-01-01
Suggests using better materials in fire syringes to obtain more effective results during demonstrations which show the elevation in temperature upon a very rapid (adiabatic) compression of air. Also describes an experiment (using ignition temperatures) which introduces students to the use of thermocouples for high temperature measurements. (DH)
Apparatus to Measure Adiabatic and Isothermal Processes.
ERIC Educational Resources Information Center
Lamb, D. W.; White, G. M.
1996-01-01
Describes a simple manual apparatus designed to serve as an effective demonstration of the differences between isothermal and adiabatic processes for the general or elementary physics student. Enables students to verify Boyle's law for slow processes and identify the departure from this law for rapid processes and can also be used to give a clear…
Calorimetry exchange program. Annual report, 1988
Lyons, J.E.
1988-12-31
The goals of the Calorimetry Sample Program are: 1. Discuss measurement differences, 2. Review and improve analytical measurements and methods, 3. Discuss new measurement capabilities, 4. Provide data to DOE on measurement capabilities to evaluate shipper- receiver differences, 5. Provide characterized or standard materials as necessary for exchange participants, 6. Provide a measurement control program for plutonium analysis. A sample of PuO{sub 2} powder is available at each participating site for NDA measurement, including either or both calorimetry and high-resolution gamma-ray spectroscopy, the elements which are typically combined to provide a calorimetric assay of plutonium. The facilities measure the sample as frequently and to the level of precision which they desire, and then submit the data to the Exchange for analysis. Statistical tests are used to evaluate the data and to determine if there are significant differences from accepted values for the exchange or from data previously reported by that facility. Data included in this report is a compilation of all exchange data received in 1988. Since a large number of data points were recorded, a change was made to the analysis method to account for the uncertainty in the accepted values.
Adiabatic and Non-adiabatic quenches in a Spin-1 Bose Einstein Condensate
NASA Astrophysics Data System (ADS)
Boguslawski, Matthew; Hebbe Madhusudhana, Bharath; Anquez, Martin; Robbins, Bryce; Barrios, Maryrose; Hoang, Thai; Chapman, Michael
2016-05-01
A quantum phase transition (QPT) is observed in a wide range of phenomena. We have studied the dynamics of a spin-1 ferromagnetic Bose-Einstein condensate for both adiabatic and non-adiabatic quenches through a QPT. At the quantum critical point (QCP), finite size effects lead to a non-zero gap, which makes an adiabatic quench possible through the QPT. We experimentally demonstrate such a quench, which is forbidden at the mean field level. For faster quenches through the QCP, the vanishing energy gap causes the reaction timescale of the system to diverge, preventing the system from adiabatically following the ground state. We measure the temporal evolution of the spin populations for different quench speeds and determine the exponents characterizing the scaling of the onset of excitations, which are in good agreement with the predictions of Kibble-Zurek mechanism.
Fixed-point adiabatic quantum search
NASA Astrophysics Data System (ADS)
Dalzell, Alexander M.; Yoder, Theodore J.; Chuang, Isaac L.
2017-01-01
Fixed-point quantum search algorithms succeed at finding one of M target items among N total items even when the run time of the algorithm is longer than necessary. While the famous Grover's algorithm can search quadratically faster than a classical computer, it lacks the fixed-point property—the fraction of target items must be known precisely to know when to terminate the algorithm. Recently, Yoder, Low, and Chuang [Phys. Rev. Lett. 113, 210501 (2014), 10.1103/PhysRevLett.113.210501] gave an optimal gate-model search algorithm with the fixed-point property. Previously, it had been discovered by Roland and Cerf [Phys. Rev. A 65, 042308 (2002), 10.1103/PhysRevA.65.042308] that an adiabatic quantum algorithm, operating by continuously varying a Hamiltonian, can reproduce the quadratic speedup of gate-model Grover search. We ask, can an adiabatic algorithm also reproduce the fixed-point property? We show that the answer depends on what interpolation schedule is used, so as in the gate model, there are both fixed-point and non-fixed-point versions of adiabatic search, only some of which attain the quadratic quantum speedup. Guided by geometric intuition on the Bloch sphere, we rigorously justify our claims with an explicit upper bound on the error in the adiabatic approximation. We also show that the fixed-point adiabatic search algorithm can be simulated in the gate model with neither loss of the quadratic Grover speedup nor of the fixed-point property. Finally, we discuss natural uses of fixed-point algorithms such as preparation of a relatively prime state and oblivious amplitude amplification.
Adiabatic burst evaporation from bicontinuous nanoporous membranes.
Ichilmann, Sachar; Rücker, Kerstin; Haase, Markus; Enke, Dirk; Steinhart, Martin; Xue, Longjian
2015-05-28
Evaporation of volatile liquids from nanoporous media with bicontinuous morphology and pore diameters of a few 10 nm is an ubiquitous process. For example, such drying processes occur during syntheses of nanoporous materials by sol-gel chemistry or by spinodal decomposition in the presence of solvents as well as during solution impregnation of nanoporous hosts with functional guests. It is commonly assumed that drying is endothermic and driven by non-equilibrium partial pressures of the evaporating species in the gas phase. We show that nearly half of the liquid evaporates in an adiabatic mode involving burst-like liquid-to-gas conversions. During single adiabatic burst evaporation events liquid volumes of up to 10(7) μm(3) are converted to gas. The adiabatic liquid-to-gas conversions occur if air invasion fronts get unstable because of the built-up of high capillary pressures. Adiabatic evaporation bursts propagate avalanche-like through the nanopore systems until the air invasion fronts have reached new stable configurations. Adiabatic cavitation bursts thus compete with Haines jumps involving air invasion front relaxation by local liquid flow without enhanced mass transport out of the nanoporous medium and prevail if the mean pore diameter is in the range of a few 10 nm. The results reported here may help optimize membrane preparation via solvent-based approaches, solution-loading of nanopore systems with guest materials as well as routine use of nanoporous membranes with bicontinuous morphology and may contribute to better understanding of adsorption/desorption processes in nanoporous media.
Adiabatic circuits: converter for static CMOS signals
NASA Astrophysics Data System (ADS)
Fischer, J.; Amirante, E.; Bargagli-Stoffi, A.; Schmitt-Landsiedel, D.
2003-05-01
Ultra low power applications can take great advantages from adiabatic circuitry. In this technique a multiphase system is used which consists ideally of trapezoidal voltage signals. The input signals to be processed will often come from a function block realized in static CMOS. The static rectangular signals must be converted for the oscillating multiphase system of the adiabatic circuitry. This work shows how to convert the input signals to the proposed pulse form which is synchronized to the appropriate supply voltage. By means of adder structures designed for a 0.13µm technology in a 4-phase system there will be demonstrated, which additional circuits are necessary for the conversion. It must be taken into account whether the data arrive in parallel or serial form. Parallel data are all in one phase and therefore it is advantageous to use an adder structure with a proper input stage, e.g. a Carry Lookahead Adder (CLA). With a serial input stage it is possible to read and to process four signals during one cycle due to the adiabatic 4-phase system. Therefore input signals with a frequency four times higher than the adiabatic clock frequency can be used. This reduces the disadvantage of the slow clock period typical for adiabatic circuits. By means of an 8 bit Ripple Carry Adder (8 bit RCA) the serial reading will be introduced. If the word width is larger than 4 bits the word can be divided in 4 bit words which are processed in parallel. This is the most efficient way to minimize the number of input lines and pads. At the same time a high throughput is achieved.
The dynamic instability of adiabatic blast waves
NASA Technical Reports Server (NTRS)
Ryu, Dongsu; Vishniac, Ethan T.
1991-01-01
Adiabatic blastwaves, which have a total energy injected from the center E varies as t(sup q) and propagate through a preshock medium with a density rho(sub E) varies as r(sup -omega) are described by a family of similarity solutions. Previous work has shown that adiabatic blastwaves with increasing or constant postshock entropy behind the shock front are susceptible to an oscillatory instability, caused by the difference between the nature of the forces on the two sides of the dense shell behind the shock front. This instability sets in if the dense postshock layer is sufficiently thin. The stability of adiabatic blastwaves with a decreasing postshock entropy is considered. Such blastwaves, if they are decelerating, always have a region behind the shock front which is subject to convection. Some accelerating blastwaves also have such region, depending on the values of q, omega, and gamma where gamma is the adiabatic index. However, since the shock interface stabilizes dynamically induced perturbations, blastwaves become convectively unstable only if the convective zone is localized around the origin or a contact discontinuity far from the shock front. On the other hand, the contact discontinuity of accelerating blastwaves is subject to a strong Rayleigh-Taylor instability. The frequency spectra of the nonradial, normal modes of adiabatic blastwaves have been calculated. The results have been applied to the shocks propagating through supernovae envelopes. It is shown that the metal/He and He/H interfaces are strongly unstable against the Rayleigh-Taylor instability. This instability will induce mixing in supernovae envelopes. In addition the implications of this work for the evolution of planetary nebulae is discussed.
Caleman, Carl; van Maaren, Paul J; Hong, Minyan; Hub, Jochen S; Costa, Luciano T; van der Spoel, David
2012-01-10
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
Pressure perturbation calorimetry of unfolded proteins.
Tsamaloukas, Alekos D; Pyzocha, Neena K; Makhatadze, George I
2010-12-16
We report the application of pressure perturbation calorimetry (PPC) to study unfolded proteins. Using PPC we have measured the temperature dependence of the thermal expansion coefficient, α(T), in the unfolded state of apocytochrome C and reduced BPTI. We have shown that α(T) is a nonlinear function and decreases with increasing temperature. The decrease is most significant in the low (2-55 °C) temperature range. We have also tested an empirical additivity approach to predict α(T) of unfolded state from the amino acid sequence using α(T) values for individual amino acids. A comparison of the experimental and calculated functions shows a very good agreement, both in absolute values of α(T) and in its temperature dependence. Such an agreement suggests the applicability of using empirical calculations to predict α(T) of any unfolded protein.
Isothermal Titration Calorimetry of Chiral Polymeric Nanoparticles.
Werber, Liora; Preiss, Laura C; Landfester, Katharina; Muñoz-Espí, Rafael; Mastai, Yitzhak
2015-09-01
Chiral polymeric nanoparticles are of prime importance, mainly due to their enantioselective potential, for many applications such as catalysis and chiral separation in chromatography. In this article we report on the preparation of chiral polymeric nanoparticles by miniemulsion polymerization. In addition, we describe the use of isothermal titration calorimetry (ITC) to measure the chiral interactions and the energetics of the adsorption of enantiomers from aqueous solutions onto chiral polymeric nanoparticles. The characterization of chirality in nano-systems is a very challenging task; here, we demonstrate that ITC can be used to accurately determine the thermodynamic parameters associated with the chiral interactions of nanoparticles. The use of ITC to measure the energetics of chiral interactions and recognition at the surfaces of chiral nanoparticles can be applied to other nanoscale chiral systems and can provide further insight into the chiral discrimination processes of nanomaterials.
Isothermal Titration Calorimetry to Characterize Enzymatic Reactions.
Mazzei, Luca; Ciurli, Stefano; Zambelli, Barbara
2016-01-01
Isothermal titration calorimetry (ITC) is a technique that measures the heat released or absorbed during a chemical reaction as an intrinsic probe to characterize any chemical process that involves heat changes spontaneously occurring during the reaction. The general features of this method to determine the kinetic and thermodynamic parameters of enzymatic reactions (kcat, KM, ΔH) are described and discussed here together with some detailed applications to specific cases. ITC does not require any modification or labeling of the system under analysis, can be performed in solution, and needs only small amounts of enzyme. These properties make ITC an invaluable, powerful, and unique tool to extend the knowledge of enzyme kinetics to drug discovery.
Quantum-Classical Correspondence of Shortcuts to Adiabaticity
NASA Astrophysics Data System (ADS)
Okuyama, Manaka; Takahashi, Kazutaka
2017-04-01
We formulate the theory of shortcuts to adiabaticity in classical mechanics. For a reference Hamiltonian, the counterdiabatic term is constructed from the dispersionless Korteweg-de Vries (KdV) hierarchy. Then the adiabatic theorem holds exactly for an arbitrary choice of time-dependent parameters. We use the Hamilton-Jacobi theory to define the generalized action. The action is independent of the history of the parameters and is directly related to the adiabatic invariant. The dispersionless KdV hierarchy is obtained from the classical limit of the KdV hierarchy for the quantum shortcuts to adiabaticity. This correspondence suggests some relation between the quantum and classical adiabatic theorems.
The high-temperature heat capacity of the (Th,U)O2 and (U,Pu)O2 solid solutions
NASA Astrophysics Data System (ADS)
Vălu, S. O.; Beneš, O.; Manara, D.; Konings, R. J. M.; Cooper, M. W. D.; Grimes, R. W.; Guéneau, C.
2017-02-01
The enthalpy increment data for the (Th,U)O2 and (U,Pu)O2 solid solutions are reviewed and complemented with new experimental data (400-1773 K) and many-body potential model simulations. The results of the review show that from room temperature up to about 2000 K the enthalpy data are in agreement with the additivity rule (Neumann-Kopp) in the whole composition range. Above 2000 K the effect of Oxygen Frenkel Pair (OFP) formation leads to an excess enthalpy (heat capacity) that is modeled using the enthalpy and entropy of OFP formation from the end-members. A good agreement with existing experimental work is observed, and a reasonable agreement with the results of the many-body potential model, which indicate the presence of the diffuse Bredig (superionic) transition that is not found in the experimental enthalpy increment data.
Lai, Chih-Chung; Chang, Wen-Chih; Hu, Wen-Liang; Wang, Zhiming M; Lu, Ming-Chang; Chueh, Yu-Lun
2014-05-07
We demonstrated enhanced solar-thermal storage by releasing the latent heat of Sn/SiO(x) core-shell nanoparticles (NPs) embedded in a eutectic salt. The microstructures and chemical compositions of Sn/SiO(x) core-shell NPs were characterized. In situ heating XRD provides dynamic crystalline information about the Sn/SiO(x) core-shell NPs during cyclic heating processes. The latent heat of ∼29 J g(-1) for Sn/SiO(x) core-shell NPs was measured, and 30% enhanced heat capacity was achieved from 1.57 to 2.03 J g(-1) K(-1) for the HITEC solar salt without and with, respectively, a mixture of 5% Sn/SiO(x) core-shell NPs. In addition, an endurance cycle test was performed to prove a stable operation in practical applications. The approach provides a method to enhance energy storage in solar-thermal power plants.
NASA Astrophysics Data System (ADS)
Kruglov, S. L.; Shutova, D. I.; Shcherbakov, V. I.
2017-02-01
The stability against magnetic flux jumps has experimentally been studied in the external magnetic field for three samples from NbTi composite superconductors, one monofilamentary and two multifilamentary. A comparison between the experiment and theory of thermomagnetic stability of composite superconductors has been carried out. We have determined threshold values of the rates of the external magnetic fields, starting from which heat capacity and conductivity of the normal composite matrix become determining stabilizing factors. For the first time, the increasing dependence of field of first magnetic flux jump on the rate of the rise in the external magnetic field has been experimentally registered in the superconducting wire for MRI. The reason for this effect is the shunting effect of a high pure copper matrix and the low volume fraction of a superconductor in the composite ( 10%).
NASA Astrophysics Data System (ADS)
Yarmohammadi, Mohsen
2017-03-01
In this work, we have studied the influences of electron-phonon (e-ph) coupling and chemical potential on the boron nitride graphene-like sheet. In particular, by starting the Green's function technique and Holstein model, the electronic density of states (DOS), electronic heat capacity (EHC) and magnetic susceptibility (MS) of this system have been investigated in the context of self-consistent second order perturbation theory which has been implemented to find the electronic self-energy. Our findings show that the band gap size decreases (increases) with e-ph coupling (chemical potential) parameters. The Schottky anomaly (crossover) decreases in EHC (MS) as soon as e-ph coupling increases. Also, the corresponding temperature with Schottky anomaly is considerably affected by e-ph coupling.
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.
Analytical calculation of adiabatic processes in real gases
NASA Astrophysics Data System (ADS)
Amarskaja, I. B.; Belousov, V. S.; Filippov, P. S.
2016-10-01
The impact of gases nonideality in the compression and expansion processes on the specific heat ratio and the heat capacity is analyzed. The specific heat ratio variation leads to temperature variation during compression in the compressor and expansion in the turbine and, consequently, the gas turbine cycle efficiency factor variation. It is also essential to consider the gases nonideality in the compression and expansion processes in the compression processes in compressor. Generally it is assumed during calculations that the heat capacities depend only on temperature, in this case the reference data presented by various authors differs markedly. In the real processes the heat capacity and the specific heat ratio depend on temperature and within the particular temperatures and pressures range depend on pressure. Consequently, the operating fluid nonideality in the gas turbine cycle should be considered.
Adiabatic Quantum Simulation of Quantum Chemistry
NASA Astrophysics Data System (ADS)
Babbush, Ryan; Love, Peter J.; Aspuru-Guzik, Alán
2014-10-01
We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions.
Ramsey numbers and adiabatic quantum computing.
Gaitan, Frank; Clark, Lane
2012-01-06
The graph-theoretic Ramsey numbers are notoriously difficult to calculate. In fact, for the two-color Ramsey numbers R(m,n) with m, n≥3, only nine are currently known. We present a quantum algorithm for the computation of the Ramsey numbers R(m,n). We show how the computation of R(m,n) can be mapped to a combinatorial optimization problem whose solution can be found using adiabatic quantum evolution. We numerically simulate this adiabatic quantum algorithm and show that it correctly determines the Ramsey numbers R(3,3) and R(2,s) for 5≤s≤7. We then discuss the algorithm's experimental implementation, and close by showing that Ramsey number computation belongs to the quantum complexity class quantum Merlin Arthur.
Comment on ``Adiabatic theory for the bipolaron''
NASA Astrophysics Data System (ADS)
Smondyrev, M. A.; Devreese, J. T.
1996-05-01
Comments are given on the application of the Bogoliubov-Tyablikov approach to the bipolaron problem in a recent paper by Lakhno [Phys. Rev. B 51, 3512 (1995)]. This author believes that his model (1) is the translation-invariant adiabatic theory of bipolarons and (2) gives asymptotically exact solutions in the adiabatic limit while the other approaches are considered as either phenomenological or variational in nature. Numerical results by Lakhno are in contradiction with all other papers published on the subject because his model leads to much lower energies. Thus, the author concludes that bipolarons ``are more stable than was considered before.'' We prove that both the analytical and the numerical results presented by Lakhno are wrong.
Shortcuts to adiabaticity from linear response theory
Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian
2015-10-23
A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts to adiabaticity for specific and very short driving times.
Shortcuts to adiabaticity from linear response theory
Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian
2015-10-23
A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts tomore » adiabaticity for specific and very short driving times.« less
Adiabatic state preparation study of methylene
Veis, Libor Pittner, Jiří
2014-06-07
Quantum computers attract much attention as they promise to outperform their classical counterparts in solving certain type of problems. One of them with practical applications in quantum chemistry is simulation of complex quantum systems. An essential ingredient of efficient quantum simulation algorithms are initial guesses of the exact wave functions with high enough fidelity. As was proposed in Aspuru-Guzik et al. [Science 309, 1704 (2005)], the exact ground states can in principle be prepared by the adiabatic state preparation method. Here, we apply this approach to preparation of the lowest lying multireference singlet electronic state of methylene and numerically investigate preparation of this state at different molecular geometries. We then propose modifications that lead to speeding up the preparation process. Finally, we decompose the minimal adiabatic state preparation employing the direct mapping in terms of two-qubit interactions.
Fast forward to the classical adiabatic invariant
NASA Astrophysics Data System (ADS)
Jarzynski, Christopher; Deffner, Sebastian; Patra, Ayoti; Subaşı, Yiǧit
2017-03-01
We show how the classical action, an adiabatic invariant, can be preserved under nonadiabatic conditions. Specifically, for a time-dependent Hamiltonian H =p2/2 m +U (q ,t ) in one degree of freedom, and for an arbitrary choice of action I0, we construct a so-called fast-forward potential energy function VFF(q ,t ) that, when added to H , guides all trajectories with initial action I0 to end with the same value of action. We use this result to construct a local dynamical invariant J (q ,p ,t ) whose value remains constant along these trajectories. We illustrate our results with numerical simulations. Finally, we sketch how our classical results may be used to design approximate quantum shortcuts to adiabaticity.
Adiabatic invariance with first integrals of motion.
Adib, Artur B
2002-10-01
The construction of a microthermodynamic formalism for isolated systems based on the concept of adiabatic invariance is an old but seldom appreciated effort in the literature, dating back at least to P. Hertz [Ann. Phys. (Leipzig) 33, 225 (1910)]. An apparently independent extension of such formalism for systems bearing additional first integrals of motion was recently proposed by Hans H. Rugh [Phys. Rev. E 64, 055101 (2001)], establishing the concept of adiabatic invariance even in such singular cases. After some remarks in connection with the formalism pioneered by Hertz, it will be suggested that such an extension can incidentally explain the success of a dynamical method for computing the entropy of classical interacting fluids, at least in some potential applications where the presence of additional first integrals cannot be ignored.
Trapped Ion Quantum Computation by Adiabatic Passage
Feng Xuni; Wu Chunfeng; Lai, C. H.; Oh, C. H.
2008-11-07
We propose a new universal quantum computation scheme for trapped ions in thermal motion via the technique of adiabatic passage, which incorporates the advantages of both the adiabatic passage and the model of trapped ions in thermal motion. Our scheme is immune from the decoherence due to spontaneous emission from excited states as the system in our scheme evolves along a dark state. In our scheme the vibrational degrees of freedom are not required to be cooled to their ground states because they are only virtually excited. It is shown that the fidelity of the resultant gate operation is still high even when the magnitude of the effective Rabi frequency moderately deviates from the desired value.
Adiabatic quantum simulation of quantum chemistry.
Babbush, Ryan; Love, Peter J; Aspuru-Guzik, Alán
2014-10-13
We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions.
Multiphoton adiabatic passage for atom optics applications
Demeter, Gabor; Djotyan, Gagik P.
2009-04-15
We study the force exerted on two-level atoms by short, counterpropagating laser pulses. When the counterpropagating pulses overlap each other partially, multiphoton adiabatic processes are possible in several configurations, which amplify the force exerted on the atoms. We investigate the practical usefulness of such multiphoton adiabatic transitions for the manipulation of the atoms' mechanical state. In particular, we compare the efficiency of a pair of constant frequency, oppositely detuned laser pulses and that of a pair of frequency-chirped pulses. We also consider the case of prolonged exposure to a sequence of laser pulses for a duration that is comparable to or much larger than the spontaneous lifetime of the atoms. We use numerical methods to calculate the reduction of the force and the heating of the atomic ensemble when spontaneous emission cannot be neglected during the interaction. In addition, we derive simple approximate formulas for the force and the heating, and compare them to the numerical results.
Adiabatic quantum optimization for associative memory recall
Seddiqi, Hadayat; Humble, Travis S.
2014-12-22
Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO). Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are storedmore » in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.« less
Adiabatic quantum optimization for associative memory recall
Seddiqi, Hadayat; Humble, Travis S.
2014-12-22
Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO). Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are stored in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.
Adiabatic Quantum Simulation of Quantum Chemistry
Babbush, Ryan; Love, Peter J.; Aspuru-Guzik, Alán
2014-01-01
We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions. PMID:25308187
Computer Code For Turbocompounded Adiabatic Diesel Engine
NASA Technical Reports Server (NTRS)
Assanis, D. N.; Heywood, J. B.
1988-01-01
Computer simulation developed to study advantages of increased exhaust enthalpy in adiabatic turbocompounded diesel engine. Subsytems of conceptual engine include compressor, reciprocator, turbocharger turbine, compounded turbine, ducting, and heat exchangers. Focus of simulation of total system is to define transfers of mass and energy, including release and transfer of heat and transfer of work in each subsystem, and relationship among subsystems. Written in FORTRAN IV.
Adiabatic charging of nickel-hydrogen batteries
NASA Technical Reports Server (NTRS)
Lurie, Chuck; Foroozan, S.; Brewer, Jeff; Jackson, Lorna
1995-01-01
Battery management during prelaunch activities has always required special attention and careful planning. The transition from nickel-cadium to nickel-hydrogen batteries, with their high self discharge rate and lower charge efficiency, as well as longer prelaunch scenarios, has made this aspect of spacecraft battery management even more challenging. The AXAF-I Program requires high battery state of charge at launch. The use of active cooling, to ensure efficient charging, was considered and proved to be difficult and expensive. Alternative approaches were evaluated. Optimized charging, in the absence of cooling, appeared promising and was investigated. Initial testing was conducted to demonstrate the feasibility of the 'Adiabatic Charging' approach. Feasibility was demonstrated and additional testing performed to provide a quantitative, parametric data base. The assumption that the battery is in an adiabatic environment during prelaunch charging is a conservative approximation because the battery will transfer some heat to its surroundings by convective air cooling. The amount is small compared to the heat dissipated during battery overcharge. Because the battery has a large thermal mass, substantial overcharge can occur before the cells get too hot to charge efficiently. The testing presented here simulates a true adiabatic environment. Accordingly the data base may be slightly conservative. The adiabatic charge methodology used in this investigation begins with stabilizing the cell at a given starting temperature. The cell is then fully insulated on all sides. Battery temperature is carefully monitored and the charge terminated when the cell temperature reaches 85 F. Charging has been evaluated with starting temperatures from 55 to 75 F.
Aspects of adiabatic population transfer and control
NASA Astrophysics Data System (ADS)
Demirplak, Mustafa
This thesis explores two different questions. The first question we answer is how to restore a given population transfer scenario given that it works efficiently in the adiabatic limit but fails because of lack of intensity and/or short duration. We derive a very simple algorithm to do this and apply it to both toy and realistic models. Two results emerge from this study. While the mathematical existence of the programme is certain it might not always be physically desirable. The restoration of adiabaticity is phase sensitive. The second question that is answered in this thesis is not how to invent new control paradigms, but rather what would happen to them in the presence of stochastic perturbers. We first use a phenomenological model to study the effect of stochastic dephasing on population transfer by stimulated Raman adiabatic passage. The results of this Monte Carlo calculation are qualitatively explained with a perturbation theoretical result in the dressed state basis. The reliability of our phenomenological model is questioned through a more rigorous hybrid quantal-classical simulation of controlled population transfer in HCl in Ar.
Adiabatic graph-state quantum computation
NASA Astrophysics Data System (ADS)
Antonio, B.; Markham, D.; Anders, J.
2014-11-01
Measurement-based quantum computation (MBQC) and holonomic quantum computation (HQC) are two very different computational methods. The computation in MBQC is driven by adaptive measurements executed in a particular order on a large entangled state. In contrast in HQC the system starts in the ground subspace of a Hamiltonian which is slowly changed such that a transformation occurs within the subspace. Following the approach of Bacon and Flammia, we show that any MBQC on a graph state with generalized flow (gflow) can be converted into an adiabatically driven holonomic computation, which we call adiabatic graph-state quantum computation (AGQC). We then investigate how properties of AGQC relate to the properties of MBQC, such as computational depth. We identify a trade-off that can be made between the number of adiabatic steps in AGQC and the norm of \\dot{H} as well as the degree of H, in analogy to the trade-off between the number of measurements and classical post-processing seen in MBQC. Finally the effects of performing AGQC with orderings that differ from standard MBQC are investigated.
Random matrix model of adiabatic quantum computing
Mitchell, David R.; Adami, Christoph; Lue, Waynn; Williams, Colin P.
2005-05-15
We present an analysis of the quantum adiabatic algorithm for solving hard instances of 3-SAT (an NP-complete problem) in terms of random matrix theory (RMT). We determine the global regularity of the spectral fluctuations of the instantaneous Hamiltonians encountered during the interpolation between the starting Hamiltonians and the ones whose ground states encode the solutions to the computational problems of interest. At each interpolation point, we quantify the degree of regularity of the average spectral distribution via its Brody parameter, a measure that distinguishes regular (i.e., Poissonian) from chaotic (i.e., Wigner-type) distributions of normalized nearest-neighbor spacings. We find that for hard problem instances - i.e., those having a critical ratio of clauses to variables - the spectral fluctuations typically become irregular across a contiguous region of the interpolation parameter, while the spectrum is regular for easy instances. Within the hard region, RMT may be applied to obtain a mathematical model of the probability of avoided level crossings and concomitant failure rate of the adiabatic algorithm due to nonadiabatic Landau-Zener-type transitions. Our model predicts that if the interpolation is performed at a uniform rate, the average failure rate of the quantum adiabatic algorithm, when averaged over hard problem instances, scales exponentially with increasing problem size.
NASA Astrophysics Data System (ADS)
Brambleby, J.; Goddard, P. A.; Singleton, J.; Jaime, M.; Lancaster, T.; Huang, L.; Wosnitza, J.; Topping, C. V.; Carreiro, K. E.; Tran, H. E.; Manson, Z. E.; Manson, J. L.
2017-01-01
We present the magnetic and thermal properties of the bosonic-superfluid phase in a spin-dimer network using both quasistatic and rapidly changing pulsed magnetic fields. The entropy derived from a heat-capacity study reveals that the pulsed-field measurements are strongly adiabatic in nature and are responsible for the onset of a significant magnetocaloric effect (MCE). In contrast to previous predictions we show that the MCE is not just confined to the critical regions, but occurs for all fields greater than zero at sufficiently low temperatures. We explain the MCE using a model of the thermal occupation of exchange-coupled dimer spin states and highlight that failure to take this effect into account inevitably leads to incorrect interpretations of experimental results. In addition, the heat capacity in our material is suggestive of an extraordinary contribution from zero-point fluctuations and appears to indicate universal behavior with different critical exponents at the two field-induced critical points. The data at the upper critical point, combined with the layered structure of the system, are consistent with a two-dimensional nature of spin excitations in the system.
Brambleby, J.; Goddard, P. A.; Singleton, John; ...
2017-01-05
We present the magnetic and thermal properties of the bosonic-superfluid phase in a spin-dimer network using both quasistatic and rapidly changing pulsed magnetic fields. The entropy derived from a heat-capacity study reveals that the pulsed-field measurements are strongly adiabatic in nature and are responsible for the onset of a significant magnetocaloric effect (MCE). In contrast to previous predictions we show that the MCE is not just confined to the critical regions, but occurs for all fields greater than zero at sufficiently low temperatures. We explain the MCE using a model of the thermal occupation of exchange-coupled dimer spin states andmore » highlight that failure to take this effect into account inevitably leads to incorrect interpretations of experimental results. In addition, the heat capacity in our material is suggestive of an extraordinary contribution from zero-point fluctuations and appears to indicate universal behavior with different critical exponents at the two field-induced critical points. Finally, the data at the upper critical point, combined with the layered structure of the system, are consistent with a two-dimensional nature of spin excitations in the system.« less
Differential scanning calorimetry study of glass transition in frozen starch gels.
Tananuwong, Kanitha; Reid, David S
2004-06-30
The effects of initial water content, maximum heating temperature, amylopectin crystallinity type, and annealing on the glass transition of starch gels were studied by differential scanning calorimetry (DSC). The glass transition temperatures of the frozen gels measured as the onset (T(g,onset)) or midpoint temperature (T(g,midpoint)), heat capacity change during the glass transition (deltaC(p)), unfrozen water of starch gels, and additional unfrozen water (AUW) arising from gelatinization were reported. The results show that T(g,onset) and T(g,midpoint) of the partially gelatinized gels are independent of the initial water content, while both of the T(g) values of the fully gelatinized gel increase as the initial water content increases. These observations might result from the difference in the level of structural disruption associated with different heating conditions, resulting in different gel structures as well as different concentrations of the sub-T(g) unfrozen matrix. The amylopectin crystallinity type does not greatly affect T(g,onset) and T(g,midpoint) of the gels. Annealing at a temperature near T(g,onset) increases both T(g,onset) and T(g,midpoint) of the gels, possibly due to an increase in the extent of the freeze concentration as evidenced by a decrease in AUW. Annealing results in an increase in the deltaC(p) value of the gels, presumably due to structural relaxation. A devitrification exotherm may be related to AUW. The annealing process decreases AUW, thus also decreasing the size of the exotherm.
Sahu, Debashish; Bastidas, Monique; Lawrence, Chad W; Noid, William G; Showalter, Scott A
2016-01-01
Broad interest in the thermodynamic driving forces of coupled macromolecular folding and binding is motivated by the prevalence of disorder-to-order transitions observed when intrinsically disordered proteins (IDPs) bind to their partners. Isothermal titration calorimetry (ITC) is one of the few methods available for completely evaluating the thermodynamic parameters describing a protein-ligand binding event. Significantly, when the effective ΔH° for the coupled folding and binding process is determined by ITC in a temperature series, the constant-pressure heat capacity change (ΔCp) associated with these coupled equilibria is experimentally accessible, offering a unique opportunity to investigate the driving forces behind them. Notably, each of these molecular-scale events is often accompanied by strongly temperature-dependent enthalpy changes, even over the narrow temperature range experimentally accessible for biomolecules, making single temperature determinations of ΔH° less informative than typically assumed. Here, we will document the procedures we have adopted in our laboratory for designing, executing, and globally analyzing temperature-dependent ITC studies of coupled folding and binding in IDP interactions. As a biologically significant example, our recent evaluation of temperature-dependent interactions between the disordered tail of FCP1 and the winged-helix domain from Rap74 will be presented. Emphasis will be placed on the use of publically available analysis programs written in MATLAB that facilitate quantification of the thermodynamic forces governing IDP interactions. Although motivated from the perspective of IDPs, the experimental design principles and data fitting procedures presented here are general to the study of most noncooperative ligand binding equilibria.
Differential Scanning Calorimetry Techniques: Applications in Biology and Nanoscience
Gill, Pooria; Moghadam, Tahereh Tohidi; Ranjbar, Bijan
2010-01-01
This paper reviews the best-known differential scanning calorimetries (DSCs), such as conventional DSC, microelectromechanical systems-DSC, infrared-heated DSC, modulated-temperature DSC, gas flow-modulated DSC, parallel-nano DSC, pressure perturbation calorimetry, self-reference DSC, and high-performance DSC. Also, we describe here the most extensive applications of DSC in biology and nanoscience. PMID:21119929
Differential scanning calorimetry techniques: applications in biology and nanoscience.
Gill, Pooria; Moghadam, Tahereh Tohidi; Ranjbar, Bijan
2010-12-01
This paper reviews the best-known differential scanning calorimetries (DSCs), such as conventional DSC, microelectromechanical systems-DSC, infrared-heated DSC, modulated-temperature DSC, gas flow-modulated DSC, parallel-nano DSC, pressure perturbation calorimetry, self-reference DSC, and high-performance DSC. Also, we describe here the most extensive applications of DSC in biology and nanoscience.
Non-adiabatic effects in near-adiabatic mixed-field orientation and alignment
NASA Astrophysics Data System (ADS)
Maan, Anjali; Ahlawat, Dharamvir Singh; Prasad, Vinod
2016-11-01
We present a theoretical study of the impact of a pair of moderate electric fields tilted an angle with respect to one another on a molecule. As a prototype, we consider a molecule with large rotational constant (with corresponding small rotational period) and moderate dipole moment. Within rigid-rotor approximation, the time-dependent Schrodinger equation is solved using fourth-order Runge-Kutta method. We have analysed that lower rotational states are significantly influenced by variation in pulse durations, the tilt angle between the fields and also on the electric field strengths. We also suggest a control scheme of how the rotational dynamics, orientation and alignment of a molecule can be enhanced by a combination of near-adiabatic pulses in comparision to non-adiabatic or adiabatic pulses.
Differential scanning calorimetry of plant cell walls
Lin, Liangshiou; Varner, J.E. ); Yuen, H.K. )
1991-03-15
High-sensitivity differential scanning calorimetry has been used to study the phase transition of cell wall preparations of the elongating and mature regions of soybean hypocotyls and of celery epidermis and collenchyma strands. A step-like transition believed to be glass transition was observed in walls isolated from the elongating region of soybean hypocotyls at 52.9C. Addition of 1 mM CaCl{sub 2} to the cell wall preparation increased the transition temperature to 60.8C and greatly reduced the transition magnitude. In walls from the mature region, the transition was small and occurred at a higher temperature (60.1C). Addition of calcium to the mature region cell wall had little effect on the transition. Based on the known interactions between calcium and pectin, the authors propose that calcium affects the glass transition by binding to the polygalacturonate backbone of wall pectin, resulting in a more rigid wall with a smaller transition at a higher temperature. The mature region either has more calcium in the wall or has more methyl-esterified pectin, making it less responsive to added calcium.
Ice premelting during differential scanning calorimetry
Wilson, PW; Arthur, JW; Haymet, AD
1999-01-01
Premelting at the surface of ice crystals is caused by factors such as temperature, radius of curvature, and solute composition. When polycrystalline ice samples are warmed from well below the equilibrium melting point, surface melting may begin at temperatures as low as -15 degrees C. However, it has been reported (. Biophys. J. 65:1853-1865) that when polycrystalline ice was warmed in a differential scanning calorimetry (DSC) pan, melting began at about -50 degrees C, this extreme behavior being attributed to short-range forces. We show that there is no driving force for such premelting, and that for pure water samples in DSC pans curvature effects will cause premelting typically at just a few degrees below the equilibrium melting point. We also show that the rate of warming affects the slope of the DSC baseline and that this might be incorrectly interpreted as an endotherm. The work has consequences for DSC operators who use water as a standard in systems where subfreezing runs are important. PMID:10545382
Current status of tritium calorimetry at TLK
Buekki-Deme, A.; Alecu, C.G.; Kloppe, B.; Bornschein, B.
2015-03-15
Inside a tritium facility, calorimetry is an important analytical method as it is the only reference method for accountancy (it is based on the measurement of the heat generated by the radioactive decay). Presently, at Tritium Laboratory Karlsruhe (TLK), 4 calorimeters are in operation, one of isothermal type and three of inertial guidance control type (IGC). The volume of the calorimeters varies between 0.5 and 20.6 liters. About two years ago we started an extensive work to improve our calorimeters with regard to reliability and precision. We were forced to upgrade 3 of our 4 calorimeters due to the outdated interfaces and software. This work involved creating new LabView programs driving the devices, re-tuning control loops and replacing obsolete hardware components. In this paper we give a review on the current performance of our calorimeters, comparing it to recently available devices from the market and in the literature. We also show some ideas for a next generation calorimeter based on experiences with our IGC calorimeters and other devices reported in the literature. (authors)
Paukov, I.E.; Samsonenko, D.G.; Pischur, D.P.; Kozlova, S.G.; Gabuda, S.P.
2014-12-15
Thermodynamic properties of high-porous metal-organic framework (MOF) compound Zn{sub 2}(C{sub 8}H{sub 4}O{sub 4}){sub 2}·N{sub 2}(CH{sub 2}){sub 6} were studied in the temperature range 8.9–300 K using low-temperature adiabatic calorymetry and DSC methods. Phase transitions were observed at ∼15, ∼60, and ∼135 K. It is shown that specific heat of the compound obeys the classical Debye law C{sub p}∼T{sup 3} only below 15 K, whereas above 15 K it is proportional to the first degree of temperature, C{sub p}∼T, to indicate a strong anisotropy of crystal vibrations corresponding to 1D continuum. It is shown that the strong anisotropy can be related to coordination interaction of Zn{sup 2+} and N{sub 2}(CH{sub 2}){sub 6} ligands in the specific structure of compound Zn{sub 2}(C{sub 8}H{sub 4}O{sub 4}){sub 2}·N{sub 2}(CH{sub 2}){sub 6}. - Graphical abstract: Specific heat C{sub p} is proportional to the first degree of temperature showing a strong anisotropy of crystal vibrations corresponding to 1D continuum in Zn{sub 2}(C{sub 8}H{sub 4}O{sub 4}){sub 2}·N{sub 2}(CH{sub 2}){sub 6.} - Highlights: • Specific heat capacity of Zn{sub 2}(C{sub 8}H{sub 4}O{sub 4}){sub 2}·N{sub 2}(CH{sub 2}){sub 6} was first studied at 8.9–300 K. • Phase transitions were observed at ∼15, ∼60, and ∼135 K. • The heat capacity is proportional to the first degree of temperature above 15 K. • The discovered dependency corresponds to a one-dimensional vibration continuum.
Kocherbitov, Vitaly; Arnebrant, Thomas
2006-05-25
We have studied hydration (and dehydration) of thermally denatured hen egg lysozyme using sorption calorimetry. Two different procedures of thermal denaturation of lysozyme were used. In the first procedure the protein was denatured in an aqueous solution at 90 degrees C, in the other procedure a sample that contained 20% of water was denatured at 150 degrees C. The protein denatured at 90 degrees C showed very similar sorption behavior to that of the native protein. The lysozyme samples denatured at 150 degrees C were studied at several temperatures in the range of 25-60 degrees C. In the beginning of sorption, the sorption isotherms of native and denatured lysozyme are almost identical. At higher water contents, however, the denatured lysozyme can absorb a greater amount of water than the native protein due to the larger number of available sorption sites. Desorption experiments did not reveal a pronounced hysteresis in the sorption isotherm of denatured lysozyme (such hysteresis is typical for native lysozyme). Despite the unfolded structure, the denatured lysozyme binds less water than does the native lysozyme in the desorption experiments at water contents up to 34 wt %. Glass transitions in the denatured lysozyme were observed using both differential scanning calorimetry and sorption calorimetry. Partial molar enthalpy of mixing of water in the glassy state is strongly exothermic, which gives rise to a positive temperature dependence of the water activity. The changes of the free energy of the protein induced by the hydration stabilize the denatured form of lysozyme with respect to the native form.
Bond selective chemistry beyond the adiabatic approximation
Butler, L.J.
1993-12-01
One of the most important challenges in chemistry is to develop predictive ability for the branching between energetically allowed chemical reaction pathways. Such predictive capability, coupled with a fundamental understanding of the important molecular interactions, is essential to the development and utilization of new fuels and the design of efficient combustion processes. Existing transition state and exact quantum theories successfully predict the branching between available product channels for systems in which each reaction coordinate can be adequately described by different paths along a single adiabatic potential energy surface. In particular, unimolecular dissociation following thermal, infrared multiphoton, or overtone excitation in the ground state yields a branching between energetically allowed product channels which can be successfully predicted by the application of statistical theories, i.e. the weakest bond breaks. (The predictions are particularly good for competing reactions in which when there is no saddle point along the reaction coordinates, as in simple bond fission reactions.) The predicted lack of bond selectivity results from the assumption of rapid internal vibrational energy redistribution and the implicit use of a single adiabatic Born-Oppenheimer potential energy surface for the reaction. However, the adiabatic approximation is not valid for the reaction of a wide variety of energetic materials and organic fuels; coupling between the electronic states of the reacting species play a a key role in determining the selectivity of the chemical reactions induced. The work described below investigated the central role played by coupling between electronic states in polyatomic molecules in determining the selective branching between energetically allowed fragmentation pathways in two key systems.
Quantized adiabatic transport in momentum space.
Ho, Derek Y H; Gong, Jiangbin
2012-07-06
Though topological aspects of energy bands are known to play a key role in quantum transport in solid-state systems, the implications of Floquet band topology for transport in momentum space (i.e., acceleration) have not been explored so far. Using a ratchet accelerator model inspired by existing cold-atom experiments, here we characterize a class of extended Floquet bands of one-dimensional driven quantum systems by Chern numbers, reveal topological phase transitions therein, and theoretically predict the quantization of adiabatic transport in momentum space. Numerical results confirm our theory and indicate the feasibility of experimental studies.
Adiabatic demagnetization refrigerator for space use
NASA Technical Reports Server (NTRS)
Serlemitsos, A. T.; Warner, B. A.; Castles, S.; Breon, S. R.; San Sebastian, M.; Hait, T.
1990-01-01
An Adiabatic Demagnetization Refrigerator (ADR) for space use is under development at NASA's Goddard Space Flight Center (GSFC). The breadboard ADR operated at 100 mK for 400 minutes. Some significant changes to that ADR, designed to eliminate shortcomings revealed during tests, are reported. To increase thermal contact, the ferric ammonium sulfate crystals were grown directly on gold-plated copper wires which serve as the thermal bus. The thermal link to the X-ray sensors was also markedly improved. To speed up the testing required to determine the best design parameters for the gas gap heat switch, the new heat switch has a modular design and is easy to disassemble.
Shortcuts to adiabaticity for quantum annealing
NASA Astrophysics Data System (ADS)
Takahashi, Kazutaka
2017-01-01
We study the Ising Hamiltonian with a transverse field term to simulate the quantum annealing. Using shortcuts to adiabaticity, we design the time dependence of the Hamiltonian. The dynamical invariant is obtained by the mean-field ansatz, and the Hamiltonian is designed by the inverse engineering. We show that the time dependence of physical quantities such as the magnetization is independent of the speed of the Hamiltonian variation in the infinite-range model. We also show that rotating transverse magnetic fields are useful to achieve the ideal time evolution.
Phase avalanches in near-adiabatic evolutions
Vertesi, T.; Englman, R.
2006-02-15
In the course of slow, nearly adiabatic motion of a system, relative changes in the slowness can cause abrupt and high magnitude phase changes, ''phase avalanches,'' superimposed on the ordinary geometric phases. The generality of this effect is examined for arbitrary Hamiltonians and multicomponent (>2) wave packets and is found to be connected (through the Blaschke term in the theory of analytic signals) to amplitude zeros in the lower half of the complex time plane. Motion on a nonmaximal circle on the Poincare-sphere suppresses the effect. A spectroscopic transition experiment can independently verify the phase-avalanche magnitudes.
Decoherence in a scalable adiabatic quantum computer
Ashhab, S.; Johansson, J. R.; Nori, Franco
2006-11-15
We consider the effects of decoherence on Landau-Zener crossings encountered in a large-scale adiabatic-quantum-computing setup. We analyze the dependence of the success probability--i.e., the probability for the system to end up in its new ground state--on the noise amplitude and correlation time. We determine the optimal sweep rate that is required to maximize the success probability. We then discuss the scaling of decoherence effects with increasing system size. We find that those effects can be important for large systems, even if they are small for each of the small building blocks.
Cavity-state preparation using adiabatic transfer
NASA Astrophysics Data System (ADS)
Larson, Jonas; Andersson, Erika
2005-05-01
We show how to prepare a variety of cavity field states for multiple cavities. The state preparation technique used is related to the method of stimulated adiabatic Raman passage. The cavity modes are coupled by atoms, making it possible to transfer an arbitrary cavity field state from one cavity to another and also to prepare nontrivial cavity field states. In particular, we show how to prepare entangled states of two or more cavities, such as an Einstein-Podolsky-Rosen state and a W state, as well as various entangled superpositions of coherent states in different cavities, including Schrödinger cat states. The theoretical considerations are supported by numerical simulations.
Generalized Ramsey numbers through adiabatic quantum optimization
NASA Astrophysics Data System (ADS)
Ranjbar, Mani; Macready, William G.; Clark, Lane; Gaitan, Frank
2016-09-01
Ramsey theory is an active research area in combinatorics whose central theme is the emergence of order in large disordered structures, with Ramsey numbers marking the threshold at which this order first appears. For generalized Ramsey numbers r( G, H), the emergent order is characterized by graphs G and H. In this paper we: (i) present a quantum algorithm for computing generalized Ramsey numbers by reformulating the computation as a combinatorial optimization problem which is solved using adiabatic quantum optimization; and (ii) determine the Ramsey numbers r({{T}}m,{{T}}n) for trees of order m,n = 6,7,8, most of which were previously unknown.
NASA Astrophysics Data System (ADS)
Lai, Chih-Chung; Chang, Wen-Chih; Hu, Wen-Liang; Wang, Zhiming M.; Lu, Ming-Chang; Chueh, Yu-Lun
2014-04-01
We demonstrated enhanced solar-thermal storage by releasing the latent heat of Sn/SiOx core-shell nanoparticles (NPs) embedded in a eutectic salt. The microstructures and chemical compositions of Sn/SiOx core-shell NPs were characterized. In situ heating XRD provides dynamic crystalline information about the Sn/SiOx core-shell NPs during cyclic heating processes. The latent heat of ~29 J g-1 for Sn/SiOx core-shell NPs was measured, and 30% enhanced heat capacity was achieved from 1.57 to 2.03 J g-1 K-1 for the HITEC solar salt without and with, respectively, a mixture of 5% Sn/SiOx core-shell NPs. In addition, an endurance cycle test was performed to prove a stable operation in practical applications. The approach provides a method to enhance energy storage in solar-thermal power plants.We demonstrated enhanced solar-thermal storage by releasing the latent heat of Sn/SiOx core-shell nanoparticles (NPs) embedded in a eutectic salt. The microstructures and chemical compositions of Sn/SiOx core-shell NPs were characterized. In situ heating XRD provides dynamic crystalline information about the Sn/SiOx core-shell NPs during cyclic heating processes. The latent heat of ~29 J g-1 for Sn/SiOx core-shell NPs was measured, and 30% enhanced heat capacity was achieved from 1.57 to 2.03 J g-1 K-1 for the HITEC solar salt without and with, respectively, a mixture of 5% Sn/SiOx core-shell NPs. In addition, an endurance cycle test was performed to prove a stable operation in practical applications. The approach provides a method to enhance energy storage in solar-thermal power plants. Electronic supplementary information (ESI) available: Detailed experimental results are included for the following: SEM images of the HITEC molten salt with and without a mixture of Sn/SiOx core-shell NPs; statistical diameter distribution of pure Sn and Sn/SiOx core-shell NPs; the HAADF image and EDS linescan profile of a Sn/SiOx core-shell NP; XRD analysis for Sn NPs annealing at different heating
NASA Astrophysics Data System (ADS)
Tombari, Elpidio; Pieruccini, Marco
2016-11-01
The glass transition region in nonconfined polymeric and low-molecular-weight supercooled liquids is probed by temperature-modulated calorimetry at a frequency of 3.3 mHz. From the distribution of relaxation times derived by analyzing the complex heat capacity, the number Nα of cooperatively rearranging units is estimated. This is done by resorting to a method in which cooperative motion is viewed as a result of a spontaneous regression of energy fluctuations. After a first, local, structural transition occurs, the energy threshold for the rearrangement of adjacent molecular units decreases progressively. This facilitation process is associated to a corresponding evolution of the density of states in a canonical representation and may be considered as a continuous spanning through different dynamic states toward a condition in which configurational constraints disappear. A good agreement is found with the Nα values obtained from the same calorimetric data within the framework of Donth's fluctuation theory. It is shown that, at variance from previous treatments, Nα can be estimated from just the relaxation function, without resorting to the knowledge of the configurational entropy. Examples point to a modest dependence of the Nα estimates on the experimental method used to derive the relaxation function.
Generating shortcuts to adiabaticity in quantum and classical dynamics
NASA Astrophysics Data System (ADS)
Jarzynski, Christopher
2013-10-01
Transitionless quantum driving achieves adiabatic evolution in a hurry, using a counterdiabatic Hamiltonian to stifle nonadiabatic transitions. Here this shortcut to adiabaticity is cast in terms of a generator of adiabatic transport. This yields a classical analog of transitionless driving, and provides a strategy for constructing quantal counterdiabatic Hamiltonians. As an application of this framework, exact classical and quantal counterdiabatic terms are obtained for a particle in a box and for even-power-law potentials in one degree of freedom.
Numerical simulations of solar spicules: Adiabatic and non-adiabatic studies
NASA Astrophysics Data System (ADS)
Kuźma, B.; Murawski, K.; Zaqarashvili, T. V.; Konkol, P.; Mignone, A.
2017-01-01
Aims: We aim to study the formation and evolution of solar spicules using numerical simulations of a vertical velocity pulse that is launched from the upper chromosphere. Methods: With the use of the PLUTO code, we numerically solved adiabatic and non-adiabatic magnetohydrodynamic (MHD) equations in 2D cylindrical geometry. We followed the evolution of spicules triggered by pulses that are launched in a vertical velocity component from the upper chromosphere. Then we compared the results obtained with and without non-adiabatic terms in the MHD equations. Results: Our numerical results reveal that the velocity pulse is steepened into a shock that propagates upward into the corona. The chromospheric cold and dense plasma follows the shock and rises into the corona with the mean speed of 20-25 km s-1. The nonlinear wake behind the pulse in the stratified atmosphere leads to quasi-periodic rebound shocks, which lead to quasi-periodic rising of chromospheric plasma into the corona with a period close to the acoustic cut-off period of the chromosphere. We found that the effect of non-adiabatic terms on spicule evolution is minor; the general properties of spicules such as their heights and rising-time remain slightly affected by these terms. Conclusions: In the framework of the axisymmetric model we devised, we show that the solar spicules can be triggered by the vertical velocity pulses, and thermal conduction and radiative cooling terms do not exert any significant influence on the dynamics of these spicules.
On the Role of Prior Probability in Adiabatic Quantum Algorithms
NASA Astrophysics Data System (ADS)
Sun, Jie; Lu, Songfeng; Yang, Liping
2016-03-01
In this paper, we study the role of prior probability on the efficiency of quantum local adiabatic search algorithm. The following aspects for prior probability are found here: firstly, only the probabilities of marked states affect the running time of the adiabatic evolution; secondly, the prior probability can be used for improving the efficiency of the adiabatic algorithm; thirdly, like the usual quantum adiabatic evolution, the running time for the case of multiple solution states where the number of marked elements are smaller enough than the size of the set assigned that contains them can be significantly bigger than that of the case where the assigned set only contains all the marked states.
Adiabatic following for a three-state quantum system
NASA Astrophysics Data System (ADS)
Huang, Wei; Shore, Bruce W.; Rangelov, Andon; Kyoseva, Elica
2017-01-01
Adiabatic time-evolution - found in various forms of adiabatic following and adiabatic passage - is often advantageous for controlled manipulation of quantum systems due to its insensitivity to deviations in the pulse shapes and timings. In this paper we discuss controlled adiabatic evolution of a three-state quantum system, a natural advance to the widespread use of two-state systems in numerous contemporary applications. We discuss, and illustrate, not only possibilities for population transfer but also for creating, with prescribed relative phase, 50:50 superpositions of two Zeeman sublevels in a letter-vee coupling linkage.
Adiabatic approximation via hodograph translation and zero-curvature equations
NASA Astrophysics Data System (ADS)
Karasev, M. V.
2014-04-01
For quantum as well classical slow-fast systems, we develop a general method which allows one to compute the adiabatic invariant (approximate integral of motion), its symmetries, the adiabatic guiding center coordinates and the effective scalar Hamiltonian in all orders of a small parameter. The scheme does not exploit eigenvectors or diagonalization, but is based on the ideas of isospectral deformation and zero-curvature equations, where the role of "time" is played by the adiabatic (quantization) parameter. The algorithm includes the construction of the zero-curvature adiabatic connection and its splitting generated by averaging up to an arbitrary order in the small parameter.
Quantum Adiabatic Algorithms and Large Spin Tunnelling
NASA Technical Reports Server (NTRS)
Boulatov, A.; Smelyanskiy, V. N.
2003-01-01
We provide a theoretical study of the quantum adiabatic evolution algorithm with different evolution paths proposed in this paper. The algorithm is applied to a random binary optimization problem (a version of the 3-Satisfiability problem) where the n-bit cost function is symmetric with respect to the permutation of individual bits. The evolution paths are produced, using the generic control Hamiltonians H (r) that preserve the bit symmetry of the underlying optimization problem. In the case where the ground state of H(0) coincides with the totally-symmetric state of an n-qubit system the algorithm dynamics is completely described in terms of the motion of a spin-n/2. We show that different control Hamiltonians can be parameterized by a set of independent parameters that are expansion coefficients of H (r) in a certain universal set of operators. Only one of these operators can be responsible for avoiding the tunnelling in the spin-n/2 system during the quantum adiabatic algorithm. We show that it is possible to select a coefficient for this operator that guarantees a polynomial complexity of the algorithm for all problem instances. We show that a successful evolution path of the algorithm always corresponds to the trajectory of a classical spin-n/2 and provide a complete characterization of such paths.
The genesis of adiabatic shear bands
Landau, P.; Osovski, S.; Venkert, A.; Gärtnerová, V.; Rittel, D.
2016-01-01
Adiabatic shear banding (ASB) is a unique dynamic failure mechanism that results in an unpredicted catastrophic failure due to a concentrated shear deformation mode. It is universally considered as a material or structural instability and as such, ASB is hardly controllable or predictable to some extent. ASB is modeled on the premise of stability analyses. The leading paradigm is that a competition between strain (rate) hardening and thermal softening determines the onset of the failure. It was recently shown that microstructural softening transformations, such as dynamic recrystallization, are responsible for adiabatic shear failure. These are dictated by the stored energy of cold work, so that energy considerations can be used to macroscopically model the failure mechanism. The initial mechanisms that lead to final failure are still unknown, as well as the ASB formation mechanism(s). Most of all - is ASB an abrupt instability or rather a gradual transition as would be dictated by microstructural evolutions? This paper reports thorough microstructural characterizations that clearly show the gradual character of the phenomenon, best described as a nucleation and growth failure mechanism, and not as an abrupt instability as previously thought. These observations are coupled to a simple numerical model that illustrates them. PMID:27849023
Accurate Variational Description of Adiabatic Quantum Optimization
NASA Astrophysics Data System (ADS)
Carleo, Giuseppe; Bauer, Bela; Troyer, Matthias
Adiabatic quantum optimization (AQO) is a quantum computing protocol where a system is driven by a time-dependent Hamiltonian. The initial Hamiltonian has an easily prepared ground-state and the final Hamiltonian encodes some desired optimization problem. An adiabatic time evolution then yields a solution to the optimization problem. Several challenges emerge in the theoretical description of this protocol: on one hand, the exact simulation of quantum dynamics is exponentially complex in the size of the optimization problem. On the other hand, approximate approaches such as tensor network states (TNS) are limited to small instances by the amount of entanglement that can be encoded. I will present here an extension of the time-dependent Variational Monte Carlo approach to problems in AQO. This approach is based on a general class of (Jastrow-Feenberg) entangled states, whose parameters are evolved in time according to a stochastic variational principle. We demonstrate this approach for optimization problems of the Ising spin-glass type. A very good accuracy is achieved when compared to exact time-dependent TNS on small instances. We then apply this approach to larger problems, and discuss the efficiency of the quantum annealing scheme in comparison with its classical counterpart.
Nonadiabatic Transitions in Adiabatic Rapid Passage
NASA Astrophysics Data System (ADS)
Lu, T.; Miao, X.; Metcalf, H.
2006-05-01
Optical forces much larger than the ordinary radiative force can be achieved on a two-level atom by multiple repetitions of adiabatic rapid passage sweeps with counterpropagating light beams. Chirped light pulses drive the atom-laser system up a ladder of dressed state energy sheets on sequential trajectories, thereby decreasing the atomic kinetic energy. Nonadiabatic transitions between the energy sheets must be avoided for this process to be effective. We have calculated the nonadiabatic transition probability for various chirped light pulses numerically. These results were compared to the first Demkov-Kunike model and the well-known Landau-Zener model. In addition, an analytical form of the nonadiabatic transition probability has been found for linearly chirped pulses and an approximate form for generic symmetric finite-time pulses has been found for the entire parameter space using the technique of unitary integration. From this, the asymptotic transition probability in the adiabatic limit was derived. T. Lu, X. Miao, and H. Metcalf, Phys., Rev. A 71 061405(R) (2005). Yu. Demkov and M. Kunike, Vestn. Leningr. Univ. Fis. Khim., 16, 39 (1969); K.-A. Suominen and B. Garraway, Phys. Rev. A45, 374 (1992)
The formation of multiple adiabatic shear bands
NASA Astrophysics Data System (ADS)
Zhou, F.; Wright, T. W.; Ramesh, K. T.
2006-07-01
In a previous paper, Zhou et al. [2006. A numerical methodology for investigating adiabatic shear band formation. J. Mech. Phys. Solids, 54, 904-926] developed a numerical method for analyzing one-dimensional deformation of thermoviscoplastic materials. The method uses a second order algorithm for integration along characteristic lines, and computes the plastic flow after complete localization with high resolution and efficiency. We apply this numerical scheme to analyze localization in a thermoviscoplastic material where multiple shear bands are allowed to form at random locations in a large specimen. As a shear band develops, it unloads neighboring regions and interacts with other bands. Beginning with a random distribution of imperfections, which might be imagined as arising qualitatively from the microstructure, we obtain the average spacing of shear bands through calculations and compare our results with previously existing theoretical estimates. It is found that the spacing between nucleating shear bands follows the perturbation theory due to Wright and Ockendon [1996. A scaling law for the effect of inertia on the formation of adiabatic shear bands. Int. J. Plasticity 12, 927-934], whereas the spacing between mature shear bands is closer to that predicted by the momentum diffusion theory of Grady and Kipp [1987. The growth of unstable thermoplastic shear with application to steady-wave shock compression in solids. J. Mech. Phys. Solids 35, 95-119]. Scaling laws for the dependence of band spacing on material parameters differ in many respects from either theory.
Adiabatic cooling of solar wind electrons
NASA Technical Reports Server (NTRS)
Sandbaek, Ornulf; Leer, Egil
1992-01-01
In thermally driven winds emanating from regions in the solar corona with base electron densities of n0 not less than 10 exp 8/cu cm, a substantial fraction of the heat conductive flux from the base is transfered into flow energy by the pressure gradient force. The adiabatic cooling of the electrons causes the electron temperature profile to fall off more rapidly than in heat conduction dominated flows. Alfven waves of solar origin, accelerating the basically thermally driven solar wind, lead to an increased mass flux and enhanced adiabatic cooling. The reduction in electron temperature may be significant also in the subsonic region of the flow and lead to a moderate increase of solar wind mass flux with increasing Alfven wave amplitude. In the solar wind model presented here the Alfven wave energy flux per unit mass is larger than that in models where the temperature in the subsonic flow is not reduced by the wave, and consequently the asymptotic flow speed is higher.
Non-adiabatic Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Canfield, Jesse; Denissen, Nicholas; Reisner, Jon
2016-11-01
Onset of Rayleigh-Taylor instability (RTI) in a non-adiabatic environment is investigated with the multi-physics numerical model, FLAG. This work was inspired by laboratory experiments of non-adiabatic RTI, where a glass vessel with a layer of tetrahyrdofuran (THF) below a layer of toluene was placed inside a microwave. THF, a polar solvent, readily absorbs electromagnetic energy from microwaves. Toluene, a non-polar solvent, is nearly transparent to microwave heating. The presence of a heat source in the THF layer produced convection and a time-dependent Atwood number (At). The system, initially in stable hydrostatic equilibrium At < 0 , was set into motion by microwave induced, volumetric heating of the THF. The point when At > 0 , indicates that the system is RTI unstable. The observed dominant mode at the onset of RTI was the horizontal length scale of the vessel. This scale is contrary to classical RTI, where the modes start small and increases in scale with time. It is shown that the dominant RTI mode observed in the experiments was determined by the THF length scale prior to RTI. The dominant length scale transitions from the THF to the toluene via the updrafts and downdrafts in the convective cells. This happens when At passes from negative to positive. This work was funded by the Advanced Simulation and Computing Program.
Heat capacity, Raman, and Brillouin scattering studies of M2O-MgO-WO3-P2O5 glasses (M=K,Rb).
Maczka, M; Hanuza, J; Baran, J; Hushur, A; Kojima, S
2006-12-28
The authors report the results of temperature-dependent Brillouin scattering from both transverse and longitudinal acoustic waves, heat capacity studies as well as room temperature Raman scattering studies on M2O-MgO-WO3-P2O5 glasses (M=K,Rb). These results were used to obtain information about structure and various properties of the studied glasses such as fragility, elastic moduli, ratio of photoelastic constants, and elastic anharmonicity. They have found that both glasses have similar properties but replacement of K+ ions by Rb+ ions in the glass network leads to decrease of elastic parameters and P44 photoelastic constant due to increase of fragility. Based on Brillouin spectroscopy they show that a linear correlation between longitudinal and shear elastic moduli holds over a large temperature range. This result supports the literature data that the Cauchy-type relation represents a general rule for amorphous solids. An analysis of the Boson peak revealed that the form of the frequency distribution of the excess density of states is in agreement with the Euclidean random matrix theory. The reason of the observed shift of the maximum frequency of the Boson peak when K+ ions are substituted for Rb+ ions is also briefly discussed.
Vugmeyster, Liliya; Ostrovsky, Dmitry; Khadjinova, Anastasia; Ellden, Jeremy; Hoatson, Gina L.; Vold, Robert L.
2012-01-01
We have investigated microsecond to millisecond time scale dynamics in several key hydrophobic core methyl groups of chicken villin headpiece subdomain protein (HP36) using a combination of single-site labeling, deuteron solid-state NMR line shape analysis, and computational modeling. Deuteron line shapes of hydrated powder samples are dominated by rotameric jumps and show a large variability of rate constants, activation energies, and rotameric populations. Site-specific activation energies vary from 6 to 38 kJ/mol. An additional mode of diffusion on a restricted arc is significant for some sites. In dry samples, the dynamics is quenched. Parameters of the motional models allow for calculations of configurational entropy and heat capacity, which, together with the rate constants, allow for observation of interplay between thermodynamic and kinetic picture of the landscape. Mutations at key phenylalanine residues at both distal (F47L&F51L) and proximal (F58L) locations to a relatively rigid side-chain of L69 have a pronounced effect on alleviating the rigidity of this side chain at room temperature and demonstrate the sensitivity of the hydrophobic core environment to such perturbations. PMID:22085262
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 TAI(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.
NASA Astrophysics Data System (ADS)
Masunaga, S. H.; Rebello, A.; Schye, A. T.; Prasai, N.; Neumeier, J. J.; Cohn, J. L.
2015-10-01
Structural phase transitions at 87 K and 103 K are reported for single-crystalline Han Blue (BaCuSi4O10) by means of high-resolution thermal-expansion, thermal conductivity and heat capacity measurements. The phase transition at 103 K results in differing lengths of the a and b lattice parameters, and thus a lowering of the crystallographic symmetry. Negative thermal-expansion coefficients are observed perpendicular to the c-axis over a wide temperature range (108 K < T < 350 K). The thermal conductivity is small, and decreases with temperature, both of which suggest strong scattering of heat-carrying phonons. The principle Grüneisen parameter within the plane and perpendicular to it was determined to be γ1=-1.09 and γ3=1.06 at room temperature; the bulk Grüneisen parameter is γ=0.10. The results are consistent with the presence of low-energy vibrations associated with the collective motions of CuO4 and Si4O10 polyhedral subunits.
NASA Astrophysics Data System (ADS)
Śliwa, Izabela; Zakharov, A. V.
2014-11-01
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 TAI(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.
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.
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.
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.
NASA Astrophysics Data System (ADS)
Hoi, Bui Dinh; Yarmohammadi, Mohsen; Mirabbaszadeh, Kavoos
2017-04-01
Dirac theory and Green's function technique are carried out to compute the spin dependent band structures and corresponding electronic heat capacity (EHC) of monolayer (ML) and AB-stacked bilayer (BL) molybdenum disulfide (MoS2) two-dimensional (2D) crystals. We report the influence of induced exchange magnetic field (EMF) by magnetic insulator substrates on these quantities for both structures. The spin-up (down) subband gaps are shifted with EMF from conduction (valence) band to valence (conduction) band at both Dirac points in the ML because of the spin-orbit coupling (SOC) which leads to a critical EMF in the K point and EHC returns to its initial states for both spins. In the BL case, EMF results split states and the decrease (increase) behavior of spin-up (down) subband gaps has been observed at both K and K‧ valleys which is due to the combined effect of SOC and interlayer coupling. For low and high EMFs, EHC of BL MoS2 does not change for spin-up subbands while increases for spin-down subbands.
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)
NASA Astrophysics Data System (ADS)
Tanjia, Fatema; Mamun, A. A.
2009-02-01
A dusty plasma consisting of negatively charged cold dust, adiabatic hot ions, and inertia-less adiabatic hot electrons has been considered. The adiabatic effects of electrons and ions on the basic properties of electro-acoustic solitary waves associated with different types of electro-acoustic (viz. ion-acoustic (IA), dust ion-acoustic (DIA), and dust acoustic (DA)) waves are thoroughly investigated by the reductive perturbation method. It is found that the basic properties of the IA, DIA, and DA waves are significantly modified by the adiabatic effects of ions and inertia-less electrons. The implications of our results in space and laboratory dusty plasmas are briefly discussed.
Determination of Purity by Differential Scanning Calorimetry (DSC).
ERIC Educational Resources Information Center
Brown, M. E.
1979-01-01
An exercise is presented which demonstrates the determination of sample purity by differential scanning calorimetry. Data and references are provided to enable the exercise to be carried out as a dry-lab experiment. (BB)
Gritti, Fabrice; Guiochon, Georges
2013-11-01
The influence of the modifier concentration in supercritical mixtures of carbon dioxide and methanol on the speed-resolution properties of columns packed with 1.7μm core-shell particles was investigated from a theoretical viewpoint. Molar fractions of methanol up to 30% were considered. The column was assumed to be operated under strict adiabatic conditions in order to maximize its efficiency. Four inlet temperatures were tested, between 297 and 337K. Four different pressure drops along the column were considered, between 25 and 200bar. The physico-chemical properties (density, viscosity, and heat capacity) of the mixtures of carbon dioxide and methanol were derived from the NIST REFPROP program for temperatures between 287 and 337K and pressures between 150 and 390bar. The axial heterogeneity of the column was taken into account by segmenting it into 500 hundreds slices in each of which all physical and chromatographic properties were assumed to be uniform. The apparent kinetic Poppe plots were built from the apparent column efficiency calculated from the sum of the increments of the retention times and time variances from the column inlet to its outlet. The numerical results showed that the axial heterogeneity of the column due to axial variations of the temperature and the equilibrium constant decreases with increasing molar fraction of methanol in the eluent when the pressure drop is increased from 25 to 200bar. The methanol content decreases the speed-resolution of the column more particularly when the analysis is done at low pressure drops. The results demonstrate also that under adiabatic conditions, for pressure drops larger than 100bar, an increase of methanol concentration does not cause a dramatic loss of speed-resolution. For example, at 310K and with a pressure drop of 25bar, the longest column is expected to deliver 17,000 plates; increasing the molar fractions of methanol from 0 to 30% decreases this efficiency by about 15% and increases the
A Modified Adiabatic Quantum Algorithm for Evaluation of Boolean Functions
NASA Astrophysics Data System (ADS)
Sun, Jie; Lu, Songfeng; Liu, Fang
2015-09-01
In this paper, we propose a modified construction of the quantum adiabatic algorithm for Boolean functions studied by M. Andrecut et al. [13, 14]. Our algorithm has the time complexity O(1) for the evaluation of Boolean functions, without additional computational cost of implementing the driving Hamiltonian, which is required by the adiabatic evolution described in [13, 14].
Adiabat-shaping in indirect drive inertial confinement fusion
Baker, K. L.; Robey, H. F.; Milovich, J. L.; Jones, O. S.; Smalyuk, V. A.; Casey, D. T.; MacPhee, A. G.; Pak, A.; Celliers, P. M.; Clark, D. S.; Landen, O. L.; Peterson, J. L.; Berzak-Hopkins, L. F.; Weber, C. R.; Haan, S. W.; Döppner, T. D.; Dixit, S.; Hamza, A. V.; Jancaitis, K. S.; Kroll, J. J.; and others
2015-05-15
Adiabat-shaping techniques were investigated in indirect drive inertial confinement fusion experiments on the National Ignition Facility as a means to improve implosion stability, while still maintaining a low adiabat in the fuel. Adiabat-shaping was accomplished in these indirect drive experiments by altering the ratio of the picket and trough energies in the laser pulse shape, thus driving a decaying first shock in the ablator. This decaying first shock is designed to place the ablation front on a high adiabat while keeping the fuel on a low adiabat. These experiments were conducted using the keyhole experimental platform for both three and four shock laser pulses. This platform enabled direct measurement of the shock velocities driven in the glow-discharge polymer capsule and in the liquid deuterium, the surrogate fuel for a DT ignition target. The measured shock velocities and radiation drive histories are compared to previous three and four shock laser pulses. This comparison indicates that in the case of adiabat shaping the ablation front initially drives a high shock velocity, and therefore, a high shock pressure and adiabat. The shock then decays as it travels through the ablator to pressures similar to the original low-adiabat pulses when it reaches the fuel. This approach takes advantage of initial high ablation velocity, which favors stability, and high-compression, which favors high stagnation pressures.
The Adiabatic Invariance of the Action Variable in Classical Dynamics
ERIC Educational Resources Information Center
Wells, Clive G.; Siklos, Stephen T. C.
2007-01-01
We consider one-dimensional classical time-dependent Hamiltonian systems with quasi-periodic orbits. It is well known that such systems possess an adiabatic invariant which coincides with the action variable of the Hamiltonian formalism. We present a new proof of the adiabatic invariance of this quantity and illustrate our arguments by means of…
Kinetic Theory Derivation of the Adiabatic Law for Ideal Gases.
ERIC Educational Resources Information Center
Sobel, Michael I.
1980-01-01
Discusses how the adiabatic law for ideal gases can be derived from the assumption of a Maxwell-Boltzmann (or any other) distribution of velocities--in contrast to the usual derivations from thermodynamics alone, and the higher-order effect that leads to one-body viscosity. An elementary derivation of the adiabatic law is given. (Author/DS)
Quantum Adiabatic Optimization and Combinatorial Landscapes
NASA Technical Reports Server (NTRS)
Smelyanskiy, V. N.; Knysh, S.; Morris, R. D.
2003-01-01
In this paper we analyze the performance of the Quantum Adiabatic Evolution (QAE) algorithm on a variant of Satisfiability problem for an ensemble of random graphs parametrized by the ratio of clauses to variables, gamma = M / N. We introduce a set of macroscopic parameters (landscapes) and put forward an ansatz of universality for random bit flips. We then formulate the problem of finding the smallest eigenvalue and the excitation gap as a statistical mechanics problem. We use the so-called annealing approximation with a refinement that a finite set of macroscopic variables (verses only energy) is used, and are able to show the existence of a dynamic threshold gamma = gammad, beyond which QAE should take an exponentially long time to find a solution. We compare the results for extended and simplified sets of landscapes and provide numerical evidence in support of our universality ansatz.
Number Partitioning via Quantum Adiabatic Computation
NASA Technical Reports Server (NTRS)
Smelyanskiy, Vadim N.; Toussaint, Udo; Clancy, Daniel (Technical Monitor)
2002-01-01
We study both analytically and numerically the complexity of the adiabatic quantum evolution algorithm applied to random instances of combinatorial optimization problems. We use as an example the NP-complete set partition problem and obtain an asymptotic expression for the minimal gap separating the ground and exited states of a system during the execution of the algorithm. We show that for computationally hard problem instances the size of the minimal gap scales exponentially with the problem size. This result is in qualitative agreement with the direct numerical simulation of the algorithm for small instances of the set partition problem. We describe the statistical properties of the optimization problem that are responsible for the exponential behavior of the algorithm.