Showing papers on "Calorimeter published in 2004"

Impedance measurements and modeling of a transition-edge-sensor calorimeter

Abstract: We describe a method for measuring the complex impedance of transition-edge-sensor (TES) calorimeters. Using this technique, we measured the impedance of a Mo/Au superconducting transition-edge-sensor calorimeter. The impedance data are in good agreement with our linear calorimeter model. From these measurements, we obtained measurements of unprecedented accuracy of the heat capacity and the gradient of resistance with respect to temperature and current of a TES calorimeter throughout the phase transition. The measurements probe the internal state of the superconductor in the phase transition and are useful for characterizing the calorimeter.

Ultrasensitive, fast, thin-film differential scanning calorimeter

Abstract: The equipment for an ultrasensitive, fast, thin-film differential scanning calorimetry [(TDSC) or nanocalorimetry] technique is described. The calorimetric cell (∼0.30 cm2) operates by applying a short (∼10 ms) dc current pulse (∼10 mA) to a thin (∼50 nm) patterned metal strip, which is supported by a thin (∼50 nm) SiNx membrane. The calorimeter operates at high heating rates (15–200 K/ms) and is very sensitive (30 pJ/K). The design of the calorimeter, the timing/synchronization methods, as well as the choice of key components of the instrument are discussed. Comparisons are made between two dc pulsing circuits that generate the current, a battery powered system and a system based on discharge of an assembly of charged capacitors (recommended). Design concepts for the differential as well as a simplified nondifferential technique are discussed and evaluated via experiments on thin films of indium. The differential design shows an increase in sensitivity, making it suitable for small samples. The custom made electronic circuits are also described, including the design of a preamplifier with low (28×) and high (700×) gain options, which are also compared using experimental data. Noise considerations are critical for the method. Simple models which describe noise levels in the calorimetric data are given and methods for reducing noise are discussed in detail. The sources of noise in the instrument are discussed in terms of both fundamental factors such as Johnson noise of the metal strip, as well as the limiting attributes of the sensing and pulsing circuits and instrumentation. These limiting attributes include spurious signals generated by desorption of ambient gases from the sensor, ground loops, switching regulators, and missing codes in analog-to-digital converter instruments. Examples of the experimental data of heat capacity Cp(T) of various thin films of indium, tin, and polystyrene are presented. A complete data set of raw experimental values is included for a 20 nm sample of Sn which shows the values of current and voltage of both the sample and reference sensors, as well as the differential voltage and the final values of the heat capacity.

Hadronic calibration of the ATLAS liquid argon end-cap calorimeter in the pseudorapidity region 1.6 < |$\eta$| < 1.8 in beam tests

Abstract: A full azimuthal φ -wedge of the ATLAS liquid argon end-cap calorimeter has been exposed to beams of electrons, muons and pions in the energy range 6 GeV ⩽ E ⩽ 200 GeV at the CERN SPS. The angular region studied corresponds to the ATLAS impact position around the pseudorapidity interval 1.6 | η | 1.8 . The beam test setup is described. A detailed study of the performance is given as well as the related intercalibration constants obtained. Following the ATLAS hadronic calibration proposal, a first study of the hadron calibration using a weighting ansatz is presented. The results are compared to predictions from Monte Carlo simulations, based on GEANT 3 and GEANT 4 models.

A numerical model and associated calorimeter for predicting temperature profiles in mass concrete

Abstract: This paper describes the development and operation of a finite difference heat model for predicting the time-based temperature profiles in mass concrete elements. The model represents a two-dimensional solution to the Fourier heat flow equation and runs on a commercially available spreadsheet package. An important problem facing heat modelling of concrete is that the rate of heat evolution at any point in the concrete element depends on concrete mixture parameters, time and position within the element. The present model resolves much of this complexity by using, as input, the results of a heat rate determination using a low-cost adiabatic calorimeter together with the Arrhenius maturity function to indicate the rate and extent of hydration at any time and position within the structure, based on the time–temperature history at that point. The paper presents a discussion of the structure of the finite difference model and its application to spreadsheet architecture. A brief description of the calorimeter is also presented together with the results of a verification exercise that was carried out to assess the accuracy of the model using a block of concrete instrumented with thermal probes. The results show that the model is able to predict the temperature at any point in the concrete block to within 2 °C of the measured values.

A small-body portable graphite calorimeter for dosimetry in low-energy clinical proton beams

Abstract: Calorimetry has been recommended and performed in proton beams for some time, but never has graphite calorimetry been used as a reference dosimeter in clinical proton beams. Furthermore, only a few calorimetry measurements have been reported in ocular proton beams. In this paper we describe the construction and performance of a small-body portable graphite calorimeter for clinical low-energy proton beams. Perturbation correction factors for the gap effect, volume averaging effect, heat transfer phenomena and impurity effect are calculated and applied in a comparison with ionization chamber dosimetry following IAEA TRS-398. The ratio of absorbed dose to water obtained from the calorimeter measurements and from the ionization measurements varied between 0.983 and 1.019, depending on the beam type and the ionization chamber calibration modality. Standard uncertainties on these values varied between 1.9% and 2.5% including a substantial contribution from the kQ values in IAEA TRS-398. The (Wair/e)p values inferred from these measurements varied between 33.6 J C(-1) and 34.9 J C(-1) with similar standard uncertainties. A number of improvements for the small-body portable graphite calorimeter and the experimental set-up are suggested for potential reduction of the uncertainties.

Calorimeter for adsorption energies of larger molecules on single crystal surfaces

Abstract: A calorimeter for measuring heats of adsorption of large molecules on single crystal surfaces is described. It extends previous instrumentation for single crystal adsorption calorimetry by adding the capability for measuring larger (lower vapor pressure) molecules. This is achieved using a chopped and collimated (∼4 mm diameter) molecular beam capable of stable 100 ms pulses of low vapor pressure substances, and a line-of-sight modification of the King and Wells method for measuring their sticking probabilities at the single crystal’s surface. The heat input to the single crystal due to adsorption is detected using a pyroelectric polymer ribbon pressed against the back of the single crystal, following our previous calorimeter design. Measurements of benzene adsorption on Pt(111) prove the capability to produce a highly stable beam of flux ∼2×1014 molecules/(cm2 s) and measure adsorption energies with an absolute accuracy of ∼5% and a pulse-to-pulse standard deviation of 2 kJ/mol.

Highly sensitive ac nanocalorimeter for microliter-scale liquids or biological samples

Abstract: We developed an ultrasensitive ac nanocalorimeter for use with biological liquids by means of microfabrication technologies. The volume of the cell measurement is only 5 μL. This nanocalorimeter, tested on deionized water, allows the measurement of heat capacity variation above ±150 nJ/K (resolution of ±5×10−6) with an operating temperature ranging from −20 to 120 °C and a stability of 100 μK. Its use is demonstrated on diluted lysosyme solution measured at the frequency of 3 Hz. At 3 Hz, this ac calorimeter gives only the variation of the heat capacity during the denaturation, which allows complementary thermodynamic investigations as regards to classical differential scanning calorimetry measurements.

Comprehensive handbook of calorimetry and thermal analysis

Abstract: Preface. Acknowledgements. List of Contributors. Part I PRINCIPLES OF CALORIMETRY AND THERMAL ANALYSIS. 1.1 Calorimetry. 1.1.1 Overview. 1.1.2 Thermodynamic quantities characteristic of multi--component system. 1.1.3 Thermodynamic quantities characteristic of surface and interface. 1.1.4 Thermodynamic quantities in chemical reactions. 1.1.5 Thermodynamics of non--equilibrium states. 1.1.6 Biothermodynamics. 1.2 Thermal Analysis. 1.2.1 Overview. 1.2.2 Thermal analysis for chemical reactions. 1.2.3 Thermal analysis for mechanical properties. 1.2.4 Dynamic viscoelastic phenomena and thermal analysis. 1.2.5 Reaction kinetics in the solid state. 1.2.6 Periodic heating method. Part II EXPERIMENTAL METHODS. 2.1 Temperature Measurement in Thermal Study. 2.2 Principles and Methods of Calorimetry. 2.2.1 Classification and basic principles of calorimeters. 2.2.2 Adiabatic heat capacity calorimetry. 2.2.3 Heat capacity calorimetry by relaxation method. 2.2.4 AC calorimetry. 2.2.5 Laser--flash calorimetry. 2.2.6 High--temperature calorimetry. 2.2.7 Low--temperature calorimetry. 2.2.8 Calorimetry under pressure. 2.2.9 Calorimetry under magnetic field. 2.2.10 Temperature jump calorimetry. 2.2.11 Calvet calorimeter. 2.2.12 Heat of vaporization and sublimation. 2.2.13 Reaction calorimetry. 2.2.14 Heat of solution and mixing. 2.2.15 Heat of immersion and adsorption. 2.2.16 Titration calorimetry. 2.2.17 Flow calorimetry. 2.2.18 Heat capacity spectroscopy. 2.2.19 Calorimetry at extremely high temperatures. 2.2.20 Adiabatic differential scanning calorimetry for biothermodynamics. 2.3 Principles and Methods of Thermal Analysis. 2.3.1 Thermogravimetry (TG) and controlled--rate TG. 2.3.2 Differential thermal analysis (DTA) and differential scanning calorimetry (DSC). 2.3.3 Thermomechanical analysis (TMA) and dynamic mechanical analysis (DMA). 2.3.4 Temperature--modulated DSC. 2.3.5 Temperature wave analysis. 2.3.6 Triple--cell DSC. 2.3.7 Simultaneous thermal analysis. 2.3.8 Micro thermal analysis by scanning probe microscopes. 2.3.9 Micromechanical calorimetry. 2.4 Other Experiments. 2.4.1 Determination of thermal expansivity. 2.4.2 Steady state method of determination of thermal conductivity/diffusivity. 2.4.3 Transient method for determination of thermal conductivity/diffusivity. 2.4.4 Mass spectrometry. 2.4.5 Determination of electromotive force. 2.4.6 Surface tension. Part III DATA ANALYSIS. 3.1 Data Analysis of Calorimetry. 3.1.1 Purity determination. 3.1.2 Phase transition and normal heat capacity. 3.1.3 Determination of partial molar quantities. 3.1.4 Statistical thermodynamic analysis in biocalorimetry. 3.1.5 Data analysis in titration calorimetry. 3.2 Techniques of Thermal Analysis and the Data Analysis. 3.2.1 Solid--state reaction kinetics by TG. 3.2.2 Baseline and thermal anomaly in DTA and DSC. 3.2.3 Heat capacity measurement by DSC and TM--DSC. 3.2.4 Analysis of isothermal crystallization by DSC. 3.2.5 Glass transition and relaxation phenomena. 3.2.6 Determination of phase diagrams by DTA/DSC. 3.2.7 Purity determination by DSC. Part IV HOW TO UTILIZE THE THERMODYNAMIC DATABASE. 4.1 Thermodynamic and Related Database. 4.1.1 Recent development of thermodynamic database systems. 4.1.2 Phase diagram calculations. 4.1.3 Thermophysical property database. 4.2 Utilization of Thermodynamic Database. 4.2.1 Calculated phase diagram vs observed phase diagram. 4.2.2 Application of chemical equilibrium calculations. 4.2.3 Application of chemical potential diagram. 4.3 Thermodynamic Database for Biomolecules. 4.3.1 Proteins and mutants. 4.3.2 Protein--nucleic acid interaction. Part V ACTUAL APPLICATIONS. 5.1 Metals and Alloys. 5.1.1 Thermal analysis of amorphous alloys. 5.1.2 Thermal analysis of hydrogen--absorbing alloy. 5.1.3 Thermal analyses of heat--resistant type steels and alloys. 5.1.4 Thermodynamic analysis of liquid alloys by temperature--jump calorimetry. 5.1.5 EMF method with solid electrolyte for liquid alloys. 5.1.6 Construction of alloy phase diagrams. 5.1.7 Electronic density of states of quasicrystals. 5.1.8 Kinetics of oxidation in thin metal films. 5.1.9 Lattice--defect concentration in solids from thermal expansion. 5.2 Inorganic Materials and Ceramics. 5.2.1 Heat capacity of UO2 up to 8000K. 5.2.2 Battery materials: Spinels containing Mn for lithium secondary battery. 5.2.3 Thermal conductivity of diamond film. 5.2.4 Kinetic features of the thermal dehydration of inorganic hydrates. 5.2.5 Dehydration of inorganic salts under reduced pressure. 5.2.6 Thermal analysis of water--containing silicate minerals. 5.2.7 Heat of adsorption and evaluation of active sites on the surface. 5.2.8 Nonstoichiometry of oxides by constant temperature TG. 5.2.9 Heat of hydration of zeolite. 5.2.10 Heat capacity of yttria--stabilized zirconia. 5.2.11 Acoustic emission and thermal analysis of phase transitions. 5.2.12 Pore--size distributions in silica gels. 5.2.13 Calorimetry for fast ion conducting glasses. 5.2.14 Negative thermal expansion of ZrW2O8. 5.2.15 Calorimetry of high--pressure minerals. 5.2.16 Heat capacity of diamond and graphite. 5.2.17 Heat capacity anomaly in lead--based complex perovskite relaxors. 5.3 Organic Materials and Polymers. 5.3.1 Strain and resonance energies of fullerenes. 5.3.2 Heat capacity of molecular monolayers. 5.3.3 Entropy of transition of mixed crystals. 5.3.4 Glass transition and residual entropy. 5.3.5 Heat capacity of exotic superconductors. 5.3.6 Magnetic dimensionality and spin--wave excitation of molecule--based magnet. 5.3.7 Calorimetry of liquid crystals. 5.3.8 Alkyl--chain--length dependence of entropy of transition. 5.3.9 High--pressure DTA of liquid crystals. 5.3.10 Crystallization of polymers. 5.3.11 Melting of polymer crystals studied by temperature--modulated DSC. 5.3.12 Origin of double melting peaks of drawn nylon 6. 5.3.13 Glass transition and relaxation in polymers. 5.3.14 Thermal decomposition of polyurethanes containing natural compounds. 5.3.15 Curing of epoxy resins containing plant components. 5.3.16 Phase transition in spin--crossover complex. 5.3.17 Frequency--dependent heat capacity near a glass transition. 5.3.18 Heat capacity of molecular magnets under magnetic field. 5.3.19 Micro thermal analysis of polymers by scanning probe microscopy. 5.4 Biomolecules. 5.4.1 Phase transition of lipid. 5.4.2 Thermal stability and function of Myb protein. 5.4.3 Thermal stability of mutant lysozymes. 5.4.4 Stepwise melting of plasmid DNA in the presence of Mg2+ ion. 5.4.5 Volume and compressibility of proteins. 5.4.6 Enzyme activity. 5.4.7 Protein--DNA interaction. 5.4.8 Molecular recognition of antibody. 5.4.9 Glass transition of protein. 5.5 Medicines. 5.5.1 Purity determination of medicines by DSC. 5.5.2 Evaluation of polymorphic transformation of drugs. 5.5.3 Determination of heat of hydration and hydration kinetics of theophylline hydrates. 5.5.4 Inclusion compound formation between host material and medicinal molecules. 5.5.5 Estimation of initial dissolution rate of drug substances by thermal analysis. 5.5.6 Long--term stability. 5.5.7 Effect of drugs on microbial growth activities. 5.5.8 Drug interaction in human blood. 5.6 Foods and Biomaterials. 5.6.1 Phase transition of glycolipids. 5.6.2 Sol--gel transition in polysaccharides. 5.6.3 Phase transition of polysaccharide helix. 5.6.4 Interaction between starch and water. 5.6.5 Novel biomaterial--water interaction produced by heat treatment. 5.6.6 Nonfreezing water in food. 5.6.7 Quantitative evaluation of food putrefaction. 5.6.8 Thermal analysis of various plant materials. 5.6.9 Dynamic viscoelasticity of hair. APPENDIX. A.1 The international temperature scale of 1990 (ITS--90). A.2 Electromotive force of thermocouples. A.3 Standard reference materials for thermal analysis. A.4 Symbols and notations for thermodynamic and related quantities and their printing. A.5 Guidelines for presentation of experimental results. Index.

Heat conduction calorimeter for massively parallel high throughput measurements with picoliter sample volumes

Abstract: We have developed a bulk micromachined calorimeter with a sensitivity of 1.5nW∕Hz1∕2 and a 1ms time constant using a thin film thermopile as the sensing element. The thermopile consists of seven titanium and bismuth thermocouples with a total Seebeck coefficient of 574μV∕K. The device is capable of measuring enthalpies in chemical or biological reactions in volumes as small as a few picoliters. The device can be fabricated and operated in a massively parallel fashion in combination with ink-jet printing technologies in air and at room temperature, making it ideally suited for biological and biochemical experiments.

A compensated heat-pulse calorimeter for low temperatures

Abstract: We describe a technique for measuring heat capacities (Cmin≈1 μJ/K at 0.1 K) of small solid samples at low temperatures (0.03 K

Development of a microwave calorimeter for simultaneous thermal analysis, infrared spectroscopy and dielectric measurements

Abstract: An instrument has been developed for monitoring cure processes under microwave heating conditions. The main function of the instrument was a calorimeter for performing microwave thermal analysis. A single mode resonant cavity was used as the heating cell in the microwave calorimeter. Thermal analysis measurements were obtained by monitoring the variation in the microwave power that was required to maintain controlled heating of the sample. The microwave thermal analysis data were analogous to conventional differential scanning calorimetry measurements. The dielectric properties of the sample, as a function of the extent of cure, have been obtained using perturbation theory from the changes in resonant frequency and quality factor of the microwave cavity during heating. Additionally, remote sensing fibre-optic probes have been employed to measure real time in situ infrared spectra of the sample during the cure reaction. In this paper, we describe the design and operation of the microwave calorimeter. Examples of experimental results are also presented.

Surface temperature measurements on burning materials using an infrared pyrometer: accounting for emissivity and reflection of external radiation

Abstract: This paper demonstrates the successful use of an infrared pyrometer, operating in the 8–10 µm wavelength band, to measure the surface temperature of combustible specimens in a heat release calorimeter. The temperature histories of ten different materials were measured in the ICAL (intermediate scale calorimeter). The set of materials comprised four wood products, gypsum board, polyisocyanurate foam, PVC floor tile, PMMA and two non-combustible boards. A small-diameter bare thermocouple was installed on each specimen in order to determine an accurate temperature for comparison. The spectral emissivity and the spectral flux reflected from the surface were measured simultaneously and used to correct the apparent temperature measured by the pyrometer. The spectral emissivity and reflected spectral flux were both constant prior to ignition for all the combustible materials. During the burning phase all the combustible materials had a spectral emissivity very close to unity. The agreement between the temperatures measured with the pyrometer and thermocouple was not affected by the flame. The wood products, the polyisocyanurate foam and the calcium silicate board required no correction for reflected spectral flux over the whole temperature range. Copyright © 2004 John Wiley & Sons, Ltd.

Metallic magnetic calorimeters (MMC): detectors for high-resolution X-ray spectroscopy

Abstract: X-ray detectors based on the concept of magnetic calorimetry are well suited for high-resolution spectroscopy. Metallic magnetic calorimeters (MMC) make use of a metallic paramagnetic temperature sensor, which is in tight thermal contact with a metallic X-ray absorber. The paramagnetic sensor is placed in a small magnetic field. Its magnetization is used to monitor the temperature, which in turn is related to the internal energy of the calorimeter. High-energy resolution can be obtained by using a low-noise, high-bandwidth DC SQUID to measure the small change in magnetization upon the absorption of an X-ray. With recent prototype detectors an energy resolution of Δ E FWHM =3.4 eV for X-ray energies up to 6.5 keV has been achieved. We discuss general design considerations, the thermodynamic properties of such calorimeters, the energy resolution, and the various sources of noise, which are observed in MMCs.

Threshold calorimeter/shelf life monitor

Abstract: Threshold calorimeter/shelf life monitors having a thermally moderating housing containing a liquid solution and one or more low melting point solids all having properties correlated relative to one another and calibrated to closely match a thermal decay profile (time-temperature profile) of a perishable product being monitored and indicate, by a change in color, electrical capacitance and/or impedance, transmitted RF signals, or combination thereof, the cumulative thermal history of the product while in transit or storage and whether its time-temperature profile has been violated to a detrimental extent or if a significant amount of shelf life has been consumed.

Heat Capacity Changes Accompanying Micelle Formation upon Burial of Hydrophobic Tail of Nonionic Surfactants

Abstract: The heat of micellization ΔHm for five nonionic surfactants (C10E5, C10E6, C10E7, C10E8, C8E5) was measured as a function of temperature by using an isothermal titration calorimeter. The abbreviati...

Low thermal inertia scanning adiabatic calorimeter

Abstract: A new adiabatic scanning calorimeter allows the thermal mass of a high-pressure reaction vessel to be dynamically compensated during a test. This allows the effective Φ factor for the experiment to be reduced to 1.0 without the use of complex pressure balancing equipment. Endothermic events can be quantified and sample specific heats can be measured. The time required for test completion is much shorter than for conventional adiabatic calorimeters, thus considerably improving apparatus productivity. The sensitivity to exotherm detection is at least as good as existing adiabatic calorimeters employing the Heat-Wait-Search strategy, but does depend on the temperature-scanning rate. In addition, the heat of reaction is obtained without reference to the heat capacity of the sample, pressure is measured continuously, reactants may be injected into the test vessel and the sample can be mixed during the test.

Calorimetric Study of Dynamical Heterogeneity in Toluene Solutions of Polystyrene

Abstract: In an effort to clarify the effect of dynamical heterogeneity on the glass transition in binary systems, we measured the heat capacity Cp on concentrated toluene solutions of polystyrene (PS) using an adiabatic calorimeter. We also carried out dielectric measurements on the same system. Results indicate that the Cp vs temperature T curve of the solvent toluene/xylene(90/10) exhibits a sharp stepwise increase of Cp at the glass transition temperature Tg (= 115 K). In contrast, the Cp curves of PS/toluene solutions exhibit a double-sigmoidal shape. The configurational heat capacity ΔCp around Tg has been determined by subtracting the heat capacity due to the lattice vibrations and intramolecular vibrations. We have further resolved ΔCp into two sigmoidal curves using an empirical function. The Tgs corresponding to the two sigmoids are denoted as Tg1 and Tg2 (Tg1 > Tg2). Two dielectric loss peaks termed α and β are assigned to segmental motions of PS and rotation of the toluene molecules, respectively. The d...

Light detector development for CRESST II

Abstract: CRESST-II detector modules rely on the ability to actively discriminate electron recoils from nuclear recoils via simultaneous measurement of phonons and scintillation light. The scintillation light produced in each target crystal is detected via an associated calorimeter consisting of a thin silicon wafer read out by a tungsten phase transition thermometer deposited on its surface. About 1% of the energy deposited in CaWO4 is detected as scintillation light; therefore, the sensitivity of the light detector is crucial for the discrimination of electron recoils from nuclear recoils at energies relevant for WIMP searches. We report the detector performance obtained using a thermometer geometry characterized by phonon collectors and a thin film thermal coupling to the heat sink (Fig. 1). This concept allows a high sensitivity by decoupling the area required for the collection of non-thermal phonons and the heat capacity of the sensor. With a 30×30×0.45 mm3 light detector, energy thresholds below 5 keV referred to energy deposition in CaWO4 have been obtained. Results achieved will be presented and an overview on further possibilities of development will be given.

Development of a portable free-air ionization chamber as an absolute intensity monitor for high-energy synchrotron radiation up to 150 keV

Abstract: As an intensity monitor for high-energy synchrotron radiation, a parallel-plate free-air ionization chamber was developed. An EGS4 Monte-Carlo transport calculation considering linear polarization showed that the electron escape fraction was within 0.5% below 70 keV, 2.7–3.3% below 150 keV and 1.1% at 150 keV when the plate separation was 8.5 cm. Without polarization, the electron loss increased to 4–5% at 70–100 keV and 3% at 150 keV. Using the chamber, photon intensity was measured at SPring-8 and compared to that of another free-air ionization chamber with a 5-cm plate separation at 30 and 40 keV, which had been calibrated with a calorimeter, and to that of a Si-PIN photodiode between 50 and 150 keV. As expected by the Monte Carlo calculation considering linear polarization, agreement was obtained within 1.3% below 70 keV, 2.2% up to 100 keV and 1.0% at 150 keV. If the collection efficiency corresponding to the result is used at each energy level, the uncertainty is limited to about 3% for the photon intensity monitoring.

Heat Capacities, Densities, and Speeds of Sound for {(1,5-Dichloropentane or 1,6-Dichlorohexane) + Dodecane}

Abstract: Densities and speeds of sound for {(1,5-dichloropentane or 1,6-dichlorohexane) + dodecane} in the temperature interval (278.15 to 328.15) K were determined using a tube vibrating densimeter and sound analyzer (Anton-Paar DSA-48). Isobaric heat capacities per unit volume for the same systems were measured in the temperature interval (283.15 to 323.15) K by means of a micro DSC II calorimeter using the scanning method. In all cases, measurements were made at atmospheric pressure. From these data, the molar volumes, isobaric and isochoric molar heat capacities, isentropic and isothermal compressibilities, and isobaric thermal expansivities as well as their excess quantities were calculated. Some comments related to the influence of the well-known effects of {polar + long alkyl chain linear alkane} on excess properties were included.

Experimental determination of isobaric heat capacities of R227 (CF3CHFCF3) from 223 to 283 K at pressures up to 20 MPa.

Abstract: A new experimental method for measuring isobaric heat capacity cp down to 223 K at pressures up to 30 MPa was developed with the aim to study alternative refrigerants at sub-ambient temperatures and elevated pressures. The experiments are carried out in a batch mode, using a differential fluxmetric calorimeter Setaram BT-215, equipped with a customized high-pressure unit. The measurements are performed at constant pressure with a continuous scan of temperature. First, the method was tested at atmospheric pressure with methanol in the temperature range 223–283 K. The relative deviation from recommended isobaric heat capacity data in the literature is about 0.5%. Second, the measurements were performed at pressure up to 18.2 MPa with an alternative refrigerant R134a (1,1,1,2-tetrafluoroethane) of well-known heat capacity. Our results agree with representative literature values within 0.4%. New original results were obtained for refrigerant R227 (1,1,1,2,3,3,3-heptafluoropropane) in the temperature range from 223 to 283 K and at pressures of 1.1, 5, 10, 15, and 20 MPa. The consistency of our isobaric heat capacities with calorimetric values above 273 K and with pVT data reported in the literature is discussed.

Low-temperature heat capacities and standard molar enthalpy of formation of aspirin

Abstract: Molar heat capacities (Cp,m) of aspirin were precisely measured with a small sample precision automated adiabatic calorimeter over the temperature range from 78 to 383 K. No phase transition was observed in this temperature region. The polynomial function of Cp,mvs. T was established in the light of the low-temperature heat capacity measurements and least square fitting method. The corresponding function is as follows: for 78 K≤T≤383 K, Cp,m/J mol-1 K-1=19.086X4+15.951X3-5.2548X2+90.192X+176.65, [X=(T-230.50/152.5)]. The thermodynamic functions on the base of the reference temperature of 298.15 K, {ΔHT -ΔH298.15} and {ST-S298.15}, were derived. Combustion energy of aspirin (ΔcUm) was determined by static bomb combustion calorimeter. Enthalpy of combustion (ΔcHom) and enthalpy of formation (ΔfHom) were derived through ΔcUm as - (3945.26±2.63) kJ mol-1 and - (736.41±1.30) kJ mol-1, respectively.

Colorimeter measured value control system and colorimeter measured value control method thereof, and a color control information providing system and a color control information providing method thereof

Abstract: A calorimeter measured value control system for controlling the measured values of plural calorimeters, including: a plurality of terminal apparatuses, each arranged for each base, having transmission section for transmitting the measured values of a color sample measured by each calorimeter; and a control server having: a storage section for storing measured values of the color sample measured by a standard calorimeter as standard values; a reception section for receiving the measured values; a determining section for determining the correction formula for approximating the measured values to the standard values stored; and a registration section for registering the correction formula, as the correction formula for correcting the error of the measured values of the calorimeter.